Coordination chemistry of pyrazolone based Schiff bases relevant to uranyl sequestering agents: Synthesis, characterization and 3D molecular modeling of some octa-coordinate mono- and binuclear-dioxouranium(VI) complexes

R.C. Maurya; B. Shukla; J. Chourasia; S. Roy; P. Bohre; S. Sahu; M.H. Martin

doi:10.1016/j.arabjc.2011.01.035

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Original article

8 (

); 655-670

doi:

10.1016/j.arabjc.2011.01.035

Coordination chemistry of pyrazolone based Schiff bases relevant to uranyl sequestering agents: Synthesis, characterization and 3D molecular modeling of some octa-coordinate mono- and binuclear-dioxouranium(VI) complexes

R.C. Maurya^⁎, B. Shukla, J. Chourasia, S. Roy, P. Bohre, S. Sahu, M.H. Martin

Coordination and Bioinorganic Chemistry Laboratory,Department of P.G. Studies and Research Chemistry,R.D. University,Jabalpur 482 001,India

⁎Corresponding author. Tel.: +91 761 2601303; fax: +91 761 2603752. rcmaurya1@gmail.com (R.C. Maurya)

Received: 2010-11-7, Accepted: 2011-1-31, Published: 2011-09-01

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Peer review under responsibility of King Saud University.

Abstract

Synthesis of two new series of octa-coordinate dioxouranum(VI) chelates: (i) mononuclear chelates of compositions, [UO₂(L¹)₂(H₂O)₂] (where L¹H = N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-anisidine (bumphp-paH, I), N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-m-phenetidine (bumphp-mpH, II) or N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-toluidine (bumphp-ptH, III), and [UO₂(L²)(H₂O)₂] (where L²H₂ = N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-o-phenylenediamine (bumphp-ophdH₂, IV), and (ii) the ligand bridged binuclear chelate of composition [UO₂(μ-L³)(H₂O)₂]₂ (where L³H₂ = N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-benzidine (bumphp-bzH₂, V), are described. These complexes have been characterized by elemental analyses, uranium determination, molar conductance, decomposition temperature and magnetic measurements, thermogravimetric studies, ¹H NMR, IR, and electronic spectral studies. The 3D molecular modeling and analysis for bond lengths and bond angles have also been carried out for the two representative compounds, [UO₂(bumphp-pa)₂(H₂O)₂] (1) and [UO₂(bumphp-bz)(H₂O)₂]₂ (5) to substantiate the proposed structures.

Keywords

Dioxouranium(VI) chelates

Mono- and binuclear

Pyrazolone based Schiff base ligands

3D Molecular modeling

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1 Introduction

Uranium is the second and most commonly naturally occurring actinide (after thorium), and is more widely used than thorium. Uranium is most commonly used as nuclear fuel in fission reactors for civilian purpose. The hexavalent uranyl ion { ${UO}_{2}^{+}$ , U(VI)} was proved to be the most stable form in aqueous solutions and in vivo at physiological pH (Hamilton, 1948).

With the commercial development of nuclear reactors, the actinides have become important industrial elements. A major concern of the nuclear industry is the biological hazard associated with nuclear fuels and their wastes. When actinides such as uranium are introduced in the body in the case of internal contamination or in the event of a nuclear accident by ingestion, inhalation or through wounds, they are chelated in the body by complexing agents such as proteins or carbonates. After chelation, toxic species are distributed and retained in target organs such as kidneys, liver and bones (Balman, 1980). This causes kidney damage from chemical toxicity/interactions (Raymond et al., 1984, 1999) and internally deposited high specific activity (alpha emission) of uranium isotopes can cause bone cancer (Finkel, 1953).

Increased handling of uranium in the nuclear fuel cycle worldwide and the threat of internal contamination of military personnel wounded with finely divided uranium shrapnel has stimulated interest in the development of uranium chelators suitable for human use. In fact, non-toxic chelators can form highly stable complexes so that the body can rapidly excrete the poison from blood and target organs. Furthermore, the uranyl chelates must be soluble and stable in physiological fluids in a pH range 2–9 to be subsequently eliminated from the body after crossing the renal and hepatic barriers (Leydier et al., 2008). Thus, uranyl concentrations and radiation doses, and subsequently tumor risks may be reduced.

During the past 30 years, several uranyl ligands were synthesized, based on different complexing functions. Phosphorous containing molecules, especially biophosphonates were found to be very effective uranyl Ligands (Sawicki et al., 2005; Bailly et al., 2002; Burgada et al., 2007; Xu et al., 2004 ), but few significant decorporation work has been reported so far concerning the decorporation efficacy of ethane-1-hydroxy-1,1-bisphosphonate (EHBP) (Martinez et al., 2000; Ubios et al., 1998, 1994; Fukuda et al., 2005 ). Bidentate methyl-terphthalimide (MeTAM)-based chelating ligands were also studied and found not to be suitable for biological decorporation due to their high toxicity (Durbin et al., 2000). A rational design of uranyl sequestering agents based on 3-hydroxy-2(1H)-pyridinone and sulfocatacholamide (CAMS) ligands resulted in the first effective agent for mammalian uranyl decorporation (Gorden et al., 2003). A new family of CAMS ligands as sequestering agents for uranyl chelation has been recently reported by Leydier et al. (2008).

Uranium(VI)-bearing inorganic–organic hybrid materials have been gaining considerable attention due to their interesting structural topologies and diverse physical–chemical properties for potential optical, magnetic, catalytic and ion-exchange applications as well as their ability for the binding and activation of N₂ for nitrogen fixation (Krivovichev and Burns, 2002; Frisch and Cahill, 2005, 2006; Salmon et al., 2006; Fox et al., 2008; Hutchings et al., 1996; Evans et al., 2003; Fortiera and Hayton, 2010; Sun et al., 2010 ). Uranium prefers to bind two axial O atoms to form the linear uranyl species ${UO}_{2}^{2 +}$ in its +6 oxidation state. The uranyl ion exhibits good stability and forms complexes with various O-, N- and S-donor ligands (Thuéry et al., 2004; Sarsfield and Helliwell, 2004; Sarsfield et al., 2003; Berthetm et al., 2004; Rowland et al., 2010; Pan et al., 2010; Back et al., 2010 ). Furthermore, the U(VI) takes on a variety of coordination environments ranging from tetragonal six-coordination, to pentagonal seven-coordination and to hexagonal bipyramidal eight-coordination (Cotton and Wilkinson, 1988). These features of U(VI) lead to a large structural diversity of uranyl complexes (Yu et al., 2003, 2005, 2004; Chen et al., 2003; Jiang et al., 2006a,b; Liao et al., 2008 ).

In continuation with our laboratory’s serialized studies on the interaction between the chelating Schiff bases of 4-acyl-3-methyl-1-phenyl-2-pyrazolin-5-one and transition/inner transition metal ions (Maurya et al., 1993, 1994, 1997a,b,c, 2002, 2006; Maurya and Rajput, 2006, 2007 ) in non-aqueous media, the entitled complexes were synthesized and characterized. Apart from the strong analgesic, antihistaminic and anti-fungal properties (Goodman and Gilman, 1970; Alaudeen et al., 2003) of pyrazolones, the 4-acyl derivatives have been shown to be very efficient extractants for (Zolotov and Kuzmin, 1977; Mirza, 1968; Karalova and Pyzhova, 1968 ) metal ions in various aqueous media. Attempts at using other derivatives of pyrazolones in constructing mixed-ligand resins for trapping toxic metals chromatographically (Chouhan and Rao, 1982; Korotkin, 1981) have been made.

Maurya and Maurya have recently reviewed coordination chemistry of Schiff base complexes of uranium (Maurya and Maurya, 1995). Previous reports (Maurya et al., 1998, 2007, 2008 ) from our laboratory describe the preparation and characterization of mononuclear, dinuclear and trinuclear complexes of dioxouranium(VI) with a series of multidentate chelating Schiff bases. A literature Survey on chelating Schiff base complexes of dioxouranium(VI) reveals that there is no report on such complexes involving chelating Schiff bases derived from 4-butryl-3-methyl-1-phenyl-2-pyrazolin-5-one. Owing to the lack of work on coordination complexes of dioxouranuim(VI) uranium with pyrazolone based Schiff bases and, obviously, the potential application of 4-acylpyrazolones in medicine and in the extraction and construction of ion exchange resins for metal ions, it was thought that it would be of interest to synthesize and characterize some dioxouranium(VI) complexes with chelating Schiff bases derived from 4-butryl-3-methyl-1-phenyl-2-pyrazolin-5-one and aromatic amines, such as, N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-anisidine (bumphp-paH, I), N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-m-phenetidine (bumphp-mpH, II) or N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-toluidine (bumphp-ptH, III), N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-o-phenylenediamine (bumphp-ophdH₂, IV) and N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-benzidine (bumphp-bzH₂, V). The designing of the Schiff base ligands (Fig. 1) in the present study is based on the consideration that the uranyl ion, a hard Lewis acid, has a high affinity for hard donor (O, N) groups in order to form stable complexes.

2 Experimental

2.1

2.1 Materials

3-Methyl-1-phenyl-2-pyrazolin-5-one (Johnson Chemical Co., Bombay), benzidine (B.D.H. Chemicals, Bombay), p-anisidine, and m-phenetidine (Aldrich Chemical Co., USA), p-toluidine (Sarabhi M. Chemicals, Baroda), o and m-phenylenediamine (Fluka A.G., Switzerland), uranyl acetate dihydrate (B.D.H. Chemicals, Poole, English) and butyryl chloride (B.D.H. Chemicals, Bombay) were used as supplied. All other chemicals used were of an analytical reagent grade.

2.2

2.2 Preparation of 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one (bumphpH)

It was prepared by the interaction of 3-methyl-1-phenyl-2-pyrazolin-5-one in dioxane with calcium hydroxide and butyryl chloride by the procedure reported by Jensen (1959), and was recrystallized from ethanol, m.p. = 65 °C.

2.3

2.3 Synthesis of the Schiff bases

The Schiff bases used in the present investigation were synthesized by the usual condensation of bumphpH and aromatic amines, viz., p-anisidine, m-phenetidine, p-toluidine, o-phenylenediamine or benzidine as reported in our previous communication (Maurya et al., 2002).

2.4

2.4 Synthesis of complexes

The complexes were prepared by following general method. An ethanolic solution (∼15 mL) of the appropriate Schiff base, I (0.002 mol, 0.698 g)/II (0.002 mol, 0.726 g)/III (0.002 mol, o.666 g)/IV (0.002 mol, 1.120 g)/V (0.002 mol, 1.272 g) was added to an ethanolic solution (∼15 ml) of uranyl acetate dihydrate [(0.001 mol, 0.424 g) in case of the ligands I–III and (0.002 mol, 0.848 g) in case of the ligands IV and V] with a stirring and the resulting mixture was kept under reflux for 6–7 h. The reaction mixture was then concentrated to a small volume by direct heating and left overnight. The crystalline mass thus obtained was filtered by suction and washed several times with ethanol, and dried in vaco. The analytical data of complexes are given in Table 1.

Table 1 Analytical data and some physical properties of the synthesized complexes.

S. No.	Complex^a (empirical formula)(F.W.)	Analyses, found/(calc.), %				Color	Deco. temp.(°C)	Yield (%)	AM (ohm⁻¹ cm² mol⁻¹)
		C	H	N	U
1	[UO₂(bumphp-pa)₂(H₂O)₂]	50.74	4.48	8.15	23.38	Raw silk	180	55	18.7
1	(C4₂H₄₈N₆O₈U) (1002.02)	(50.30)	(4.79)	(8.38)	(23.75)	Raw silk	180	55	18.7
2	[UO₂(bumphp-mp)₂(H₂O)₂]	51.67	4.82	8.48	23.50	Mid cream	185	55	16.5
2	(C₄₄H₅₂N₆O₈U) (1030.02)	(51.26)	(5.05)	(8.16)	(23.11)	Mid cream	185	55	16.5
3	[UO₂(bumphp-pt)₂(H₂O)₂]	51.48	5.15	8.85	24.25	Cream	205	58	17.1
3	(C₄₂H₄₈N₆O₈U)(790.02)	(51.96)	(4.95)	(8.66)	(24.54)	Cream	205	58	17.1
4	[UO₂(bumphp-ophd)(H2O)₂]	47.64	4.22	9.50	27.32	Pepper-mint	190	60	25.4
4	(C₃₄H₃₈N₆O₈U) (864.02)	(47.22)	(4.40)	(9.72)	(27.55)	Pepper-mint	190	60	25.4
5	[UO₂(bumphp-bz)(H₂O)₂]2	51.42	4.20	8.53	25.67	White	220	52	20.5
5	(C₈₀H₈₄N₁₂O₁₂U) (1880.04)	(51.06)	(4.47)	(8.94)	(25.32)	White	220	52	20.5

a IUPAC name of the complexes: (1) diaquabis{N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-ono)-p-anisidine}dioxouranium(VI); (2) diaquabis{N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-ono)-m-phenetidine}dioxouranium(VI); (3) diaquabis{N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-ono)-p-toluidine}dioxouranium(VI); (4) diaqua{N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-ono)-o-phenylenediamine}dioxouranium(VI); (5) bis[μ-{N,N′-bis(4′-butyrylidene-3′-methyl-r-phenyl-2′-pyrazolin-5′-ono)-benzidine}]di{diaquadioxournium(VI)}.

2.5

2.5 Analyses

Carbon, hydrogen and nitrogen were determined micro-analytically at the Central Drug Research Institute, Lucknow. The uranium contents of all the synthesized complexes were determined gravimetrically (Vogel, 1961) as U₃O₈ after decomposing the complexes with concentrated nitric acid and igniting the residue.

3 Physical methods

The room temperature magnetic susceptibilities of the complexes were measured with a PAR VSM 155 vibrating sample magnetometer at the Regional Sophisticated Instrumentation Centre, Indian Institutes of Technology, Chennai. Electronic Spectra of complexes were recorded on ATI Unicam UV-2-100 UV/visible Spectrophotometer in our department. Solid-state infrared spectra were recorded in Nujol mulls at Central Drug Research Institute, Lucknow. Conductance measurements were performed at room temperature in dimethylformamide using a Toshniwal conductivity bridge and dip type cell with a smooth platinum electrode of cell constant 1.02. Thermogravimetric curves were recorded by heating the sample at the rate of 20 °C min⁻¹ up to 740 °C on a thermal analyzer, Mettler Toledo Star^e system at the Regional Sophisticated Instrumentation Centre, Nagpur.

4 Results and discussion

The dioxouranium(VI) complexes with chelating Schiff bases were prepared according to the following Eqs. (1)–(3).

(1)

{UO}_{2} {({CH}_{3} COO)}_{2} \cdot 2 H_{2} O + 2 LH ⟶_{Reflux}^{Ethanol} [{UO}_{2} {(L)}_{2} {(H_{2} O)}_{2}] + 2 {CH}_{3} COOH

where LH = bumphp-paH (1), bumphp-mpH (2) or bumphp-ptH (3),

(2)

{UO}_{2} {({CH}_{3} COO)}_{2} \cdot 2 H_{2} O + {LH}_{2} ⟶_{Reflux}^{Ethanol} [{UO}_{2} (L) {(H_{2} O)}_{2}] + 2 {CH}_{3} COOH

where LH₂ = bumphp-ophdH₂ (4),

(3)

2 {UO}_{2} {({CH}_{3} COO)}_{2} \cdot 2 H_{2} O + 2 {LH}_{2} ⟶_{Reflux}^{Ethanol} {[{UO}_{2} (μ - L) {(H_{2} O)}_{2}]}_{2} + 4 {CH}_{3} COOH

where LH₂ = bumphp-bzH₂ (5).

The synthesized complexes are colored, non-hygroscopic and air-stable solids. They are soluble in dimethylformamide, dimethylsulfoxide and insoluble in all other common organic solvent. The resulting complexes were characterized using the following physical studies.

4.1

4.1 Infrared spectra

The infrared spectra of all the five Schiff bases display (Maurya et al., 2002) a medium broad band (except the ligands IV and V which exhibits two bands at 3480–3490 and 3200–3300 cm⁻¹) with fine structure in the region 3500–3150 cm⁻¹. This indicates that all the ligands exist in the enol form (Fig. 1) in solid state. Hence, the ligands bumphp-paH, bumphp-mpH and bumphp-ptH contain four potential donor sites: (i) the enolic oxygen, (ii) the azomethine nitrogen, (iii) the cyclic nitrogen N¹ and (iv) the cyclic nitrogen N² of the pyrazolon skeleton. On the other hand the rest of the Schiff bases, such as, bumphp-ophdH₂ and bumphp-bzH₂ have eight potential donor sites: (i) the two enolic oxygen, (ii) the two azomethine nitrogens, (iii) the two cyclic nitrogens N¹ and (iv) the two cyclic nitrogens N² of the pyrazolon skeleton.

The IR spectra of all the ligands display (Maurya et al., 2002) a strong band at 1616–1635 cm⁻¹, which is assigned to ν(C⚌N) of azomethine group. In the spectra of all the six complexes, this band is shifted to lower frequency side and is observed at 1605–1620 cm⁻¹ suggesting coordination of the azomethine nitrogen to the ${UO}_{2}^{2 +}$ moiety (Maurya et al., 2002).

All the complexes exhibit a medium-intensity band at 901–932 cm⁻¹ and a strong band at 817–858 cm⁻¹ assignable to ν_as(O⚌U⚌O) and ν_s(O⚌U⚌O) modes, respectively. This observation indicates that the UO₂ moiety is virtually linear (Maurya and Maurya, 1995).

The force constants [f_(U–O)] for all the complexes were calculated by the method of McGlynn et al. (1961) and bonds lengths of the U–O bond for all the complexes were calculated using the Jones equation (Jones, 1958, 1959). The values of f (6.74–7.21 mdyne/Å) and R_U–O (1.72–1.74Å) (Table 2) are found in the usual range observed for other dioxouranuim(VI) complexes (Maurya and Maurya, 1995). For the sake of convenience, the remaining interpretation of infrared spectra is divided into three parts.

Table 2 Important IR spectral bands (cm⁻¹), force constant and bond distance of U–O bond in synthesized complexes.

S. No.	Compound	ν(C⚌N) (Azometh.)	ν(C–O) (Enolic)	ν_as(O⚌U⚌O)	ν_s(O⚌U⚌O)	ν(OH) (H₂O)	F_U–O mdyne (Å)	U–O (bond dist.) (Å)
1	[UO₂(bumphp-pa)₂(H₂O)₂]	1620	1205	901	839	3470	6.74	1.74
2	[UO₂(bumphp-mp)₂(H₂O)₂]	1620	1232	910	817	3480	6.87	1.73
3	[UO₂(bumphp-pt)₂(H₂O)₂]	1610	1225	930	840	3500	7.18	1.72
4	[UO₂(bumphp-ophd)(H₂O)₂]	1608	1360	925	850	3470	7.10	1.73
5	[UO₂(bumphp-bz)(H₂O)₂]₂	1605	1340	920	840	3580–3300	7.03	1.71

4.1.1

4.1.1 Complexes with bumphp-paH (I), bumphp-mpH (II) or bumphp-ptH (III)

The coordination of ring nitrogen N¹ in these Schiff base ligands is unlikely due to the presence of bulky phenyl group attached to it. Considering the planarity of the ligands, the coordination of ring nitrogens, N₂ is also unlikely due to being back side of the suitable donor sites: (i), (ii), with reference to the details of donor sites given above. In fact, the coordination of the ring nitrogen N² in these ligands is found to be inert to the metal center as revealed by the almost unaltered positions of the ν(C⚌N²) (cyclic) (1592–1594 cm⁻¹) (Maurya et al., 2002) mode of the respective ligands after complexation. The interaction of these enolic ligands with the ${UO}_{2}^{2 +}$ moiety with elimination of a proton is revealed by the presence of a new band in the complexes at 1205–1232 cm⁻¹ due to the ν(C–O) enol (Ledon et al., 1979) mode. The appearance of two medium broad bands in 3470–3500 and 3360–3410 cm⁻¹ regions due to ν(OH) indicates that these complexes contain at least one coordinated water molecule.

4.1.2

4.1.2 Complex with bumphp-ophdH₂ (IV)

The coordination of the two ring nitrogens N¹ and two ring nitrogens N² in this ligand is not taking place to the uranyl center by the same reasoning already given in case of ligands I–III. However, the coordination of the two enolic oxygens, after deprotonation, to the uranyl center in these complexes is indicated by the appearance of a new band at 1330–1360 cm⁻¹ due to ν(C–O) (enolic) (Maurya et al., 1998). The overall IR results conclude that the ligand under discussion is chelating dibasic tetradentate.

4.1.3

4.1.3 Complex bumphp-bzH₂ (V)

The analytical data suggest that this complex is a binuclear involving ligand bridging. The significant absorption band due to coordinated enolic oxygens in this complex is ν(C–O) (enol). This band is observed at 1340 cm⁻¹ in this complex, similar to the complex (4). Again the overall IR results conclude that ligand under discussion is also behaving as a chelating dibasic tetradentate. The appearance of a broad band at 3580–3500 cm⁻¹ may be due to coordinated water in the complex. The formation of a binuclear complex may be attributed due the presence of two azomethine nitrogens at 1,6-positions in the ligand, wherein coordination of both the azomethine nitriogens to the same metal center is difficult. The above-mentioned observations suggest that compound (5) is a ligand bridged binuclear dioxouranium(VI) complex. Such a result has already been reported elsewhere (Maurya et al., 2008).

4.2

4.2 Conductance measurements

The observed molar conductances of these complexes measured in 10⁻³ M dimethylformamide solutions are in the range 16.5–25.4 ohm⁻¹ cm² mol⁻¹, and thereby indicate their non-electrolytic (Geary, 1971) nature.

4.3

4.3 Magnetic measurements

The magnetic measurements of these complexes indicate that they are diamagnetic, as expected for the dioxouranium(IV) complexes.

4.4

4.4 Electronic spectra

Electronic Spectra compounds were recorded in 10⁻³ M dimethylformamide solution. The electronic spectral peaks observed along with their molar extinction coefficient are given in Table 3. In view of the high intensity of the first four peaks in each of the complexes analyzed, they appear to be due to intra-ligand transitions. The fifth peak of lower intensity (ε = 2368–2538 L mol⁻¹ cm⁻¹) in each of the complex may be due to $^{1} E_{g}^{+} \to^{3} ν_{U}$ transition (Maurya and Maurya, 1995).

Table 3 Electronic spectra data of some complexes.

Compound No.	Compound	λ_max (nm)	ε (L mol⁻¹ cm⁻¹)	Peak assignment
1	[UO₂(bumphp-pa)₂(H₂O)₂]	305	4230
		335	4145	Intra-ligand
		360	4245	transitions
		370	4085
		445	2538	¹E_g→ ³π_u
2	[UO₂(bumphp-mp)₂(H₂O)₂]	315	4378
		345	4162	Intra-ligand
		357	4342	transitions
		368	4000
		450	2445	¹E_g→ ³π_u
3	[UO₂(bumphp-pt)₂(H₂O)₂]	310	4250
		350	4160	Intra-ligand
		362	4260	transitions
		372	4065
		440	2530	¹E_g→ ³π_u
4	[UO₂(bumphp-ophd)(H₂O)₂]	305	4280
		335	4090	Intra-ligand
		345	4550	transitions
		365	4845
		410	2460	¹E_g→ ³π_u
5	[UO₂(bumphp-bz)(H₂O)₂]₂	297	4378
		326	4000	Intra-ligand
		340	5297	transitions
		359	5297
		396	2368	¹E_g→ ³π_u

4.5

4.5 ¹H NMR spectra

The proton NMR spectrum of a representative compound [UO₂(bumphp-pa)₂(H₂O)₂] was recorded in DMSO-d₆. The proton signals observed at δ 7.05–8.03 ppm are assigned for the aromatic protons present in the ligand. The appearance of a proton signal at δ 12.65 ppm may be due to the presence of coordinated water molecule in the complex. Other significant proton signals were also observed in the lower ppm range in the complex as δ 3.85 (singlet)-OCH₃ (a), δ 3.39 (singlet)-solvent/CH₃ (b), δ 2.29–2.66 (multiplet)-CH₂ (d), δ 1.43–1.55 (triplett)-CH₃ (e) and δ 0.78–0.85 (triplet)-CH₂ (c). The indexing of various protons is given in Fig. 2.

Indexing of various protons in [UO2 (bumphp-pa)2(H2O)2].

4.6

4.6 Thermogravimetric analysis

The thermograms of two compounds [UO₂(bumphp-pa)₂(H₂O)₂] (1) and [UO₂(bumphp-mp)₂(H₂O)₂] (2) were recorded in the temperature range 30–850 °C at the heating rate of 20 °C min⁻¹. Observations of thermograms of these two compounds indicate that they are stable up to 250 and 300 °C, respectively. Thereafter, they start decomposing and their weights became constant beyond 400 °C. In case of the compound (1), the weight loss observed in the temperature range 250–400 °C roughly corresponds to elimination of two coordinated water molecules and two ligand moieties (bumphp-pa). Similar to compound (1), the observed weight loss in the temperature range 300–400 °C for the compound (2) also roughly matches with the elimination of two coordinated water molecules and two ligand moieties (bumphp-mp). The thermograms of these two compounds, therefore, corroborate some of the observations made by IR spectral studies for these complexes (vide supra).

4.7

4.7 3D Molecular modeling and analysis

Based on the proposed structures (Fig. 4), the 3D molecular modeling of one of the representative compounds, viz., [UO₂(bumphp-pa)₂(H₂O)₂] (1) and [UO₂(bumphp-bz)(H₂O)₂]₂ (5), were carried out with the CS Chem 3D Ultra Molecular Modeling and Analysis Program. The details of bond lengths, bond angles as per the 3D structures (Figs. 3 and 4) are given in Tables 4a1, 4a2, 4b1, and 4b2 , respectively. For convenience of looking over the different bond lengths and bond angles, the various atoms in the compound in question are numbered in Arabic numerals. Compound (1) displays a total of 320 measurements of the bond lengths (112 in number), plus the bond angles (208 in number, while compound (5) displays a total of 594 measurements of the bond lengths (206 in number), plus the bond angles (388 in number). Except few cases, optimal values of both the bond lengths and the bond angles are given in the Tables along with the actual ones. The actual bond lengths/bond angles given in Tables are calculated values as a result of energy optimization in CHEM 3D Ultra (www.cambridgesoft.com), while the optimal bond length/optimal bond angle values are the most desirable/favorable (standard) bond lengths/bond angles established by the builder unit of the CHEM 3D. The missing of some values of standard bond lengths/bond angles may be due to the limitations of the software, which we had already noticed in modeling of other systems (Maurya et al., 2006, 2007, 2008, 2010, 2011 ). In most of the cases, the observed bond lengths and bond angles are close to the optimal values, and thus the proposed structures of compound (1) and (4) (and also others) are acceptable (Maurya et al., 2006, 2007, 2008, 2010, 2015 ).

Table 4a1 Various bond lengths of compound (1).

S. No.	Atoms	Actual bond length	Optimal bond length	S. No.	Atoms	Actual bond length	Optimal bond length
1	N(1)–N(2)	1.614	1.426	57	C(29)–O(30)	1.355	1.355
2	N(1)–C(5)	1.266	1.462	58	O(30)–U(49)	2.06	–
3	N(1)–C(7)	1.266	1.462	59	C(31)–C(32)	1.337	1.42
4	N(2)–C(3)	1.26	1.26	60	C(31)–C(36)	1.337	1.42
5	C(3)–C(4)	1.337	1.503	61	C(32)–C(33)	1.337	1.42
6	C(3)–C(13)	1.497	1.497	62	C(32)–H(81)	1.1	1.1
7	C(4)–C(5)	1.337	1.337	63	C(33)–C(34)	1.337	1.42
8	C(4)–C(14)	1.337	1.503	64	C(33)–H(82)	1.1	1.1
9	C(5)–O(6)	1.355	1.355	65	C(34)–C(35)	1.337	1.42
10	O(6)–U(49)	2.06	–	66	C(34)–H(83)	1.1	1.1
11	C(7)–C(8)	1.337	1.42	67	C(35)–C(36)	1.337	1.42
12	C(7)–C(12)	1.337	1.42	68	C(35)–H(84)	1.1	1.1
13	C(8)–C(9)	1.337	1.42	69	C(36)–H(85)	1.1	1.1
14	C(8)–H(62)	1.1	1.1	70	C(37)–H(86)	1.113	1.113
15	C(9)–C(10)	1.337	1.42	71	C(37)–H(87)	1.113	1.113
16	C(9)–H(63)	1.1	1.1	72	C(37)–H(88)	1.113	1.113
17	C(10)–C(11)	1.337	1.42	73	C(38)–N(39)	1.266	1.266
18	C(10)–H(64)	1.1	1.1	74	C(38)–C(40)	1.497	1.497
19	C(11)–C(12)	1.337	1.42	75	C(48)–N(39)	1.266	1.462
20	C(11)–H(65)	1.1	1.1	76	N(39)–U(49)	2.0961	–
21	C(12)–H(66)	1.1	1.1	77	C(40)–C(41)	1.523	1.523
22	C(13)–H(67)	1.113	1.113	78	C(40)–H(89)	1.113	1.113
23	C(13)–H(68)	1.113	1.113	79	C(40)–H(90)	1.113	1.113
24	C(13)–H(69)	1.113	1.113	80	C(41)–C(42)	1.523	1.523
25	C(14)–N(15)	1.266	1.266	81	C(41)–H(91)	1.113	1.113
26	C(14)–C(16)	1.497	1.497	82	C(41)–H(92)	1.113	1.113
27	C(24)–N(15)	1.266	1.462	83	C(42)–H(93)	1.113	1.113
28	N(15)–U(49)	2.096	–	84	C(42)–H(94)	1.113	1.113
29	C(16)–C(17)	1.523	1.523	85	C(42)–H(95)	1.113	1.113
30	C(16)–H(70)	1.113	1.113	86	C(43)–C(44)	1.337	1.42
31	C(16)–H(71)	1.113	1.113	87	C(48)–C(43)	1.337	1.42
32	C(17)–C(18)	1.523	1.523	88	C(43)–H(96)	1.1	1.1
33	C(17)–H(72)	1.113	1.113	89	C(44)–C(45)	1.337	1.42
34	C(17)–H(73)	1.113	1.113	90	C(44)–H(97)	1.1	1.1
35	C(18)–H(74)	1.113	1.113	91	C(45)–C(46)	1.337	1.42
36	C(18)–H(75)	1.113	1.113	92	C(45)–O(54)	1.355	1.355
37	C(18)–H(76)	1.113	1.113	93	C(46)–C(47)	1.337	1.42
38	C(19)–C(20)	1.337	1.42	94	C(46)–H(98)	1.1	1.1
39	C(24)–C(19)	1.337	1.42	95	C(47)–C(48)	1.337	1.42
40	C(19)–H(77)	1.1	1.1	96	C(47)–H(99)	1.1	1.1
41	C(20)–C(21)	1.337	1.42	97	U(49)–O(50)	2.2659	–
42	C(20)–H(78)	1.1	1.1	98	U(49)–O(51)	1.6391	–
43	C(21)–C(22)	1.337	1.42	99	O(59)–U(49)	1.9972	–
44	C(21)–O(52)	1.355	1.355	100	O(56)–U(49)	2.0358	–
45	C(22)–C(23)	1.337	1.42	101	O(52)–C(53)	1.402	1.396
46	C(22)–H(79)	1.1	1.1	102	C(53)–H(100)	1.113	1.111
47	C(23)–C(24)	1.337	1.42	103	C(53)–H(101)	1.113	1.111
48	C(23)–H(80)	1.1	1.1	104	C(53)–H(102)	1.113	1.111
49	N(25)–N(26)	1.23	1.426	105	O(54)–C(55)	1.402	1.396
50	N(25)–C(29)	1.266	1.462	106	C(55)–H(103)	1.113	1.111
51	N(25)–C(31)	1.266	1.462	107	C(55)–H(104)	1.113	1.111
52	N(26)–C(27)	1.5526	1.26	108	C(55)–H(105)	1.113	1.111
53	C(27)–C(28)	1.337	1.503	109	O(56)–H(57)	0.986	–
54	C(27)–C(37)	1.497	1.497	110	O(56)–H(58)	0.986	–
55	C(28)–C(29)	1.337	1.337	111	O(59)–H(60)	0.986	–
56	C(28)–C(38)	1.337	1.503	112	O(59)–H(61)	0.986	–

Table 4a2 Various bond angles of compound (1).

S. No.	Atoms	Actual bond angles	Optimal bond angles	S. No.	Atoms	Actual bond angles	Optimal bond angles
1	O(54)–C(55)–H(103)	109.5002	106.7	105	C(23)–C(22)–H(79)	120.0003	120
2	O(54)–C(55)–H(104)	109.4417	106.7	106	C(20)–C(21)–C(22)	120.0003	120
3	O(54)–C(55)–H(105)	109.4616	106.7	107	C(20)–C(21)–O(52)	119.9998	124.3
4	H(103)–C(55)–H(104)	109.4419	109	108	C(22)–C(21)–O(52)	120	124.3
5	H(103)–C(55)–H(105)	109.4621	109	109	C(19)–C(20)–C(21)	119.9996	–
6	H(104)–C(55)–H(105)	109.5199	109	110	C(19)–C(20)–H(78)	120.0002	120
7	O(52)–C(53)–H(100)	109.4999	106.7	111	C(21)–C(20)–H(78)	120.0002	120
8	O(52)–C(53)–H(101)	109.4419	106.7	112	C(22)–C(23)–C(24)	120.0005	–
9	O(52)–C(53)–H(102)	109.462	106.7	113	C(22)–C(23)–H(80)	119.9997	120
10	H(100)–C(53)–H(101)	109.4417	109	114	C(24)–C(23)–H(80)	119.9999	120
11	H(100)–C(53)–H(102)	109.4618	109	115	C(20)–C(19)–C(24)	120.0005	–
12	H(101)–C(53)–H(102)	109.5201	109	116	C(20)–C(19)–H(77)	119.9995	120
13	C(41)–C(42)–H(93)	109.5002	110	117	C(24)–C(19)–H(77)	120	120
14	C(41)–C(42)–H(94)	109.4417	110	118	U(49)–O(59)–H(60)	128.2036	–
15	C(41)–C(42)–H(95)	109.4618	110	119	U(49)–O(59)–H(61)	72.307	–
16	H(93)–C(42)–H(94)	109.4415	109	120	H(60)–O(59)–H(61)	120	–
17	H(93)–C(42)–H(95)	109.4621	109	121	U(49)–O(56)–H(57)	129.351	–
18	H(94)–C(42)–H(95)	109.5199	109	122	U(49)–O(56)–H(58)	74.6503	–
19	C(40)–C(41)–C(42)	109.5002	109.5	123	H(57)–O(56)–H(58)	120.0001	–
20	C(40)–C(41)–H(91)	109.442	109.41	124	C(38)–N(39)–C(48)	120.001	120
21	C(40)–C(41)–H(92)	109.4617	109.41	125	C(38)–N(39)–U(49)	119.9983	–
22	C(42)–C(41)–H(91)	109.4417	109.41	126	C(48)–N(39)–U(49)	120.0007	–
23	C(42)–C(41)–H(92)	109.4619	109.41	127	C(29)–O(30)–U(49)	109.4998	–
24	H(91)–C(41)–H(92)	109.52	109.4	128	O(6)–U(49)–N(15)	71.7457	–
25	C(17)–C(18)–H(74)	109.5002	110	129	O(6)–U(49)–O(30)	109.5	–
26	C(17)–C(18)–H(75)	109.442	110	130	O(6)–U(49)–N(39)	38.2999	–
27	C(17)–C(18)–H(76)	109.4618	110	131	O(6)–U(49)–O(50)	78.5201	–
28	H(74)–C(18)–H(75)	109.4414	109	132	O(6)–U(49)–O(51)	30.7545	–
29	H(74)–C(18)–H(76)	109.4619	109	133	O(6)–U(49)–O(59)	78.0668	–
30	H(75)–C(18)–H(76)	109.5201	109	134	O(6)–U(49)–O(56)	44.1709	–
31	C(16)–C(17)–C(18)	109.4998	109.5	135	N(15)–U(49)–O(30)	109.5	–
32	C(16)–C(17)–H(72)	109.4421	109.41	136	N(15)–U(49)–N(39)	90.0729	–
33	C(16)–C(17)–H(73)	109.4624	109.41	137	N(15)–U(49)–O(50)	15.4074	–
34	C(18)–C(17)–H(72)	109.4419	109.41	137	N(15)–U(49)–O(51)	64.078	–
35	C(18)–C(17)–H(73)	109.4615	109.41	139	N(15)–U(49)–O(59)	55.5905	–
36	H(72)–C(17)–H(73)	109.5197	109.4	140	N(15)–U(49)–O(56)	29.672	–
37	C(45)–O(54)–C(55)	120.0001	110.8	141	O(30)–U(49)–N(39)	71.7348	–
38	C(45)–C(46)–C(47)	120	–	142	O(30)–U(49)–O(50)	121.1086	–
39	C(45)–C(46)–H(98)	120	120	143	O(30)–U(49)–O(51)	140.0634	–
40	C(47)–C(46)–H(98)	120	120	144	O(30)–U(49)–O(59)	161.338	–
41	C(44)–C(45)–C(46)	120.0002	120	145	O(30)–U(49)–O(56)	104.9506	–
42	C(44)–C(45)–O(54)	119.9997	124.3	146	N(39)–U(49)–O(50)	103.1382	–
43	C(46)–C(45)–O(54)	120.0001	124.3	147	N(39)–U(49)–O(51)	68.9921	–
44	C(43)–C(44)–C(45)	120.0002	–	148	N(39)–U(49)–O(59)	116.0123	–
45	C(43)–C(44)–H(97)	119.9996	120	149	N(39)–U(49)–O(56)	61.5736	–
46	C(45)–C(44)–H(97)	120.0003	120	150	O(50)–U(49)–O(51)	62.9126	–
47	C(46)–C(47)–C(48)	119.9997	–	151	O(50)–U(49)–O(59)	42.1519	–
48	C(46)–C(47)–H(99)	119.9996	120	152	O(50)–U(49)–O(56)	41.5663	–
49	C(48)–C(47)–H(99)	120.0006	120	153	O(51)–U(49)–O(59)	48.2077	–
50	C(44)–C(43)–C(48)	119.9996	–	154	O(51)–U(49)–O(56)	48.7064	–
51	C(44)–C(43)–H(96)	120.0006	120	155	O(59)–U(49)–O(56)	68.0171	–
52	C(48)–C(43)–H(96)	119.9998	120	156	N(15)–C(24)–C(19)	119.9999	120
53	C(34)–C(35)–C(36)	120.0003	–	157	N(15)–C(24)–C(23)	120.0006	120
54	C(34)–C(35)–H(84)	119.9999	120	158	C(19)–C(24)–C(23)	119.9995	120
55	C(36)–C(35)–H(84)	119.9998	120	159	C(14)–C(16)–C(17)	109.4996	109.5
56	C(33)–C(34)–C(35)	120	–	160	C(14)–C(16)–H(70)	109.4416	109.41
57	C(33)–C(34)–H(83)	119.9997	120	161	C(14)–C(16)–H(71)	109.462	109.41
58	C(35)–C(34)–H(83)	120.0003	120	162	C(17)–C(16)–H(70)	109.4417	109.41
59	C(32)–C(33)–C(34)	120.0001	–	163	C(17)–C(16)–H(71)	109.462	109.41
60	C(32)–C(33)–H(82)	119.9996	120	164	H(70)–C(16)–H(71)	109.5205	109.4
61	C(34)–C(33)–H(82)	120.0004	120	165	C(14)–N(15)–C(24)	119.9997	124
62	C(31)–C(36)–C(35)	119.9997	–	166	C(14)–N(15)–U(49)	120.001	–
63	C(31)–C(36)–H(85)	120.0004	120	167	C(24)–N(15)–U(49)	119.9993	–
64	C(35)–C(36)–H(85)	119.9999	120	168	C(10)–C(11)–C(12)	120.0003	–
65	C(31)–C(32)–C(33)	119.9996	–	169	C(10)–C(11)–H(65)	120.0003	120
66	C(31)–C(32)–H(81)	120	120	170	C(12)–C(11)–H(65)	119.9994	120
67	C(33)–C(32)–H(81)	120.0003	120	171	C(9)–C(10)–C(11)	120.0001	–
68	N(25)–C(31)–C(32)	119.9998	120	172	C(9)–C(10)–H(64)	120	120
69	N(25)–C(31)–C(36)	119.9999	120	173	C(11)–C(10)–H(64)	119.9999	120
70	C(32)–C(31)–C(36)	120.0003	120	174	C(8)–C(9)–C(10)	120.0001	–
71	C(27)–C(37)–H(86)	109.5	110	175	C(8)–C(9)–H(63)	120	120
72	C(27)–C(37)–H(87)	109.442	110	176	C(10)–C(9)–H(63)	120	120
73	C(27)–C(37)–H(88)	109.4623	110	177	C(7)–C(12)–C(11)	119.9996	–
74	H(86)–C(37)–H(87)	109.4415	109	178	C(7)–C(12)–H(66)	119.9997	120
75	H(86)–C(37)–H(88)	109.4614	109	179	C(11)–C(12)–H(66)	120.0006	120
76	H(87)–C(37)–H(88)	109.5203	109	180	C(7)–C(8)–C(9)	120.0001	–
77	N(25)–N(26)–C(27)	108.8315	115	181	C(7)–C(8)–H(62)	120.0001	120
78	N(39)–C(48)–C(43)	119.9999	120	182	C(9)–C(8)–H(62)	119.9998	120
79	N(39)–C(48)–C(47)	119.9998	120	183	N(1)–C(7)–C(8)	119.9998	120
80	C(43)–C(48)–C(47)	120.0003	120	184	N(1)–C(7)–C(12)	120.0003	120
81	C(38)–C(40)–C(41)	109.5	109.5	185	C(8)–C(7)–C(12)	119.9999	120
82	C(38)–C(40)–H(89)	109.4423	109.41	186	C(4)–C(14)–N(15)	119.9999	120
83	C(38)–C(40)–H(90)	109.4619	109.41	187	C(4)–C(14)–C(16)	120.0004	121.4
84	C(41)–C(40)–H(89)	109.4414	109.41	188	N(15)–C(14)–C(16)	119.9997	125.3
85	C(41)–C(40)–H(90)	109.4618	109.41	189	C(5)–O(6)–U(49)	109.4999	–
86	H(89)–C(40)–H(90)	109.5199	109.4	190	N(1)–C(5)–C(4)	111.0005	120
87	C(28)–C(38)–N(39)	120.0002	120	191	N(1)–C(5)–O(6)	124.6978	–
88	C(28)–C(38)–C(40)	119.9999	121.4	192	C(4)–C(5)–O(6)	124.2983	124.3
89	N(39)–C(38)–C(40)	119.9999	125.3	193	C(3)–C(13)–H(67)	109.5	110
90	N(26)–C(27)–C(28)	98.1693	120	194	C(3)–C(13)–H(68)	109.4422	110
91	N(26)–C(27)–C(37)	130.9157	115.1	195	C(3)–C(13)–H(69)	109.4618	110
92	C(28)–C(27)–C(37)	130.915	121.4	196	H(67)–C(13)–H(68)	109.4419	109
93	N(26)–N(25)–C(29)	111.0003	124	197	H(67)–C(13)–H(69)	109.4618	109
94	N(26)–N(25)–C(31)	124.4998	124	198	H(68)–C(13)–H(69)	109.5197	109
95	C(29)–N(25)–C(31)	124.4999	124	199	C(3)–C(4)–C(5)	110.9999	120
96	C(27)–C(28)–C(29)	111.0001	120	200	C(3)–C(4)–C(14)	128.9978	120
97	C(27)–C(28)–C(38)	128.9982	120	201	C(5)–C(4)–C(14)	119.9989	120
98	C(29)–C(28)–C(38)	119.9982	120	202	N(2)–N(1)–C(5)	103.2925	124
99	N(25)–C(29)–C(28)	110.9989	120	203	N(2)–N(1)–C(7)	128.3533	124
100	N(25)–C(29)–O(30)	124.6986	–	204	C(5)–N(1)–C(7)	128.3542	124
101	C(28)–C(29)–O(30)	124.3004	124.3	205	N(2)–C(3)–C(4)	111	120
102	C(21)–O(52)–C(53)	119.9999	110.8	206	N(2)–C(3)–C(13)	124.5	115.1
103	C(21)–C(22)–C(23)	119.9996	–	207	C(4)–C(3)–C(13)	124.5	121.4
104	C(21)–C(22)–H(79)	120.0001	120	208	N(1)–N(2)–C(3)	103.7071	105

Table 4b1 Various bond length of compound (5).

S. No.	Atoms	Actual bond length	Optimal bond length	S. No.	Atoms	Actual bond length	Optimal bond length
1	O(112)–H(114)	0.942	0.942	104	U(52)–O(54)	2.4608	–
2	O(112)–H(113)	0.942	0.942	105	U(52)–O(53)	5.0866	–
3	O(109)–H(111)	0.942	0.942	106	N(61)–U(49)	2.096	–
4	O(109)–H(110)	0.942	0.942	107	U(49)–O(103)	2.8441
5	O(104)–H(106)	0.942	0.942	108	U(49)–O(104)	4.8259
6	O(104)–H(105)	0.942	0.942	109	O(74)–U(49)	2.06	–
7	O(103)–H(108)	0.942	0.942	110	U(49)–O(51)	4.5152	–
8	O(103)–H(107)	0.942	0.942	111	U(49)–O(50)	2.6457	–
9	C(102)–H(190)	1.113	1.113	112	C(48)–H(152)	1.113	1.113
10	C(102)–H(189)	1.113	1.113	113	C(48)–H(151)	1.113	1.113
11	C(102)–H(188)	1.113	1.113	114	C(48)–H(150)	1.113	1.113
12	C(101)–H(187)	1.113	1.113	115	C(47)–H(149)	1.113	1.113
13	C(101)–H(186)	1.113	1.113	116	C(47)–H(148)	1.113	1.113
14	C(101)–C(102)	1.523	1.523	117	C(47)–C(48)	1.523	1.523
15	C(100)–H(185)	1.113	1.113	118	C(46)–H(147)	1.113	1.113
16	C(100)–H(184)	1.113	1.113	119	C(46)–H(146)	1.113	1.113
17	C(100)–C(101)	1.523	1.523	120	C(46)–C(47)	1.523	1.523
18	C(99)–C(100)	1.497	1.497	121	C(45)–C(46)	1.497	1.497
19	C(98)–H(183)	1.113	1.113	122	C(44)–H(145)	1.113	1.113
20	C(98)–H(182)	1.113	1.113	123	C(44)–H(144)	1.113	1.113
21	C(98)–H(181)	1.113	1.113	124	C(44)–H(143)	1.113	1.113
22	C(97)–H(180)	1.1	1.1	125	C(43)–H(142)	1.1	1.1
23	C(96)–H(179)	1.1	1.1	126	C(42)–H(141)	1.1	1.1
24	C(96)–C(97)	1.3949	1.42	127	C(42)–C(43)	1.3949	1.42
25	C(95)–H(178)	1.1001	1.1	128	C(41)–H(140)	1.1	1.1
26	C(95)–C(96)	1.3948	1.42	129	C(41)–C(42)	1.3948	1.42
27	C(94)–H(177)	1.1	1.1	130	C(40)–H(139)	1.1	1.1
28	C(94)–C(95)	1.3948	1.42	131	C(40)–C(41)	1.3948	1.42
29	C(93)–H(176)	1.1	1.1	132	C(39)–H(138)	1.1	1.1
30	C(93)–C(94)	1.3948	1.42	133	C(39)–C(40)	1.3949	1.42
31	C(92)–C(97)	1.3948	1.42	134	C(38)–C(43)	1.3948	1.42
32	C(92)–C(93)	1.3948	1.42	135	C(38)–C(39)	1.3948	1.42
33	C(90)–O(91)	1.355	1.355	136	U(52)–O(37)	2.06	–
34	C(89)–C(99)	1.337	1.503	137	C(36)–O(37)	1.355	1.355
35	C(89)–C(90)	1.337	1.42	137	C(35)–C(45)	1.337	1.503
36	C(88)–C(98)	1.497	1.497	139	C(35)–C(36)	1.337	1.42
37	C(88)–C(89)	1.337	1.42	140	C(34)–C(44)	1.497	1.497
38	N(87)–C(88)	1.5526	1.358	141	C(34)–C(35)	1.337	1.42
39	N(86)–C(92)	1.266	1.462	142	N(33)–C(34)	1.5526	1.358
40	N(86)–C(90)	1.266	1.364	143	N(32)–C(38)	1.266	1.462
41	N(86)–N(87)	1.23	1.328	144	N(32)–C(36)	1.266	1.364
42	C(85)–H(175)	1.113	1.113	145	N(32)–N(33)	1.23	1.328
43	C(85)–H(174)	1.113	1.113	146	C(31)–H(137)	1.113	1.113
44	C(85)–H(173)	1.113	1.113	147	C(31)–H(136)	1.113	1.113
45	C(84)–H(172)	1.113	1.113	148	C(31)–H(135)	1.113	1.113
46	C(84)–H(171)	1.113	1.113	149	C(30)–H(134)	1.113	1.113
47	C(84)–C(85)	1.523	1.523	150	C(30)–H(133)	1.113	1.113
48	C(83)–H(170)	1.113	1.113	151	C(30)–C(31)	1.523	1.523
49	C(83)–H(169)	1.113	1.113	152	C(29)–H(132)	1.113	1.113
50	C(83)–C(84)	1.523	1.523	153	C(29)–H(131)	1.113	1.113
51	C(82)–C(83)	1.497	1.497	154	C(29)–C(30)	1.523	1.523
52	C(81)–H(168)	1.113	1.113	155	C(28)–C(29)	1.497	1.497
53	C(81)–H(167)	1.113	1.113	156	C(27)–H(130)	1.113	1.113
54	C(81)–H(166)	1.113	1.113	157	C(27)–H(129)	1.113	1.113
55	C(80)–H(165)	1.1	1.1	158	C(27)–H(128)	1.113	1.113
56	C(79)–H(164)	1.1	1.1	159	C(26)–H(127)	1.1	1.1
57	C(79)–C(80)	1.3949	1.42	160	C(25)–H(126)	1.1	1.1
58	C(78)–H(163)	1.1	1.1	161	C(25)–C(26)	1.3949	1.42
59	C(78)–C(79)	1.3948	1.42	162	C(24)–H(125)	1.1	1.1
60	C(77)–H(162)	1.1	1.1	163	C(24)–C(25)	1.3948	1.42
61	C(77)–C(78)	1.3948	1.42	164	C(23)–H(124)	1.1	1.1
62	C(76)–H(161)	1.1	1.1	165	C(23)–C(24)	1.3948	1.42
63	C(76)–C(77)	1.3949	1.42	166	C(22)–H(123)	1.1	1.1
64	C(75)–C(80)	1.3948	1.42	167	C(22)–C(23)	1.3949	1.42
65	C(75)–C(76)	1.3948	1.42	168	C(21)–C(26)	1.3948	1.42
66	C(73)–O(74)	1.355	1.355	169	C(21)–C(22)	1.3948	1.42
67	C(72)–C(82)	1.337	1.503	170	O(20)–U(49)	2.06	–
68	C(72)–C(73)	1.337	1.42	171	C(19)–O(20)	1.355	1.355
69	C(71)–C(81)	1.497	1.497	172	C(18)–C(28)	1.337	1.503
70	C(71)–C(72)	1.337	1.42	173	C(18)–C(19)	1.337	1.42
71	N(70)–C(71)	1.5526	1.358	174	C(17)–C(27)	1.497	1.497
72	N(69)–C(75)	1.266	1.462	175	C(17)–C(18)	1.337	1.42
73	N(69)–C(73)	1.266	1.364	176	N(16)–C(17)	1.5526	1.358
74	N(69)–N(70)	1.23	1.328	177	N(15)–C(21)	1.266	1.462
75	C(99)–N(68)	1.5106	1.26	178	N(15)–C(19)	1.266	1.364
76	C(67)–H(160)	1.1	1.1	179	N(15)–N(16)	1.23	1.328
77	C(66)–N(68)	1.26	1.456	180	U(52)–N(14)	2.0961	–
78	C(66)–C(67)	1.337	1.42	181	C(45)–N(14)	1.451	1.26
79	C(65)–H(159)	1.1	1.1	182	C(13)–H(122)	1.1	1.1
80	C(65)–C(66)	1.337	1.42	183	C(12)–N(14)	1.2599	1.456
81	C(64)–H(158)	1.1	1.1	184	C(12)–C(13)	1.337	1.42
82	C(64)–C(65)	1.2955	1.42	185	C(11)–H(121)	1.1	1.1
83	C(63)–C(64)	1.337	1.42	186	C(11)–C(12)	1.337	1.42
84	C(62)–H(157)	1.1	1.1	187	C(10)–H(120)	1.1	1.1
85	C(67)–C(62)	1.363	1.42	188	C(10)–C(11)	1.3371	1.42
86	C(62)–C(63)	1.337	1.42	189	C(9)–C(10)	1.337	1.42
87	C(82)–N(61)	1.5186	1.26	190	C(8)–H(119)	1.1	1.1
88	C(60)–H(156)	1.1	1.1	191	C(13)–C(8)	1.337	1.42
89	C(59)–C(63)	1.337	1.503	192	C(8)–C(9)	1.337	1.42
90	C(59)–C(60)	1.337	1.42	193	N(7)–U(49)	2.096	–
91	C(58)–H(155)	1.1	1.1	194	C(28)–N(7)	1.4433	1.26
92	C(58)–C(59)	1.337	1.42	195	C(6)–H(118)	1.1	1.1
93	C(57)–H(154)	1.1	1.1	196	C(5)–C(9)	1.337	1.503
94	C(57)–C(58)	1.3371	1.42	197	C(5)–C(6)	1.337	1.42
95	C(56)–N(61)	1.26	1.456	198	C(4)–H(117)	1.1	1.1
96	C(56)–C(57)	1.337	1.42	199	C(4)–C(5)	1.337	1.42
97	C(55)–H(153)	1.1	1.1	200	C(3)–H(116)	1.1	1.1
98	C(60)–C(55)	1.337	1.42	201	C(3)–C(4)	1.3371	1.42
99	C(55)–C(56)	1.337	1.42	202	C(2)–N(7)	1.26	1.456
100	N(68)–U(52)	2.096	–	203	C(2)–C(3)	1.337	1.42
101	U(52)–O(112)	3.5907	–	204	C(1)–H(115)	1.1	1.1
102	U(52)–O(109)	4.6793	–	205	C(6)–C(1)	1.337	1.42
103	O(91)–U(52)	2.06	–	206	C(1)–C(2)	1.337	1.42

Table 4b2 Various bond angles of compound (5).

S. No.	Atoms	Actual bond angles	Optimal bond angles	S. No.	Atoms	Actual bond angles	Optimal bond angles
1	H(190)–C(102)–H(189)	109.52	109	195	H(111)–O(109)–H(110)	120.0006	–
2	H(190)–C(102)–H(188)	109.462	109	196	H(111)–O(109)–U(52)	44.9277	–
3	H(190)–C(102)–C(101)	109.46	110	197	H(110)–O(109)–U(52)	155.2078	–
4	H(189)–C(102)–H(188)	109.4412	109	198	C(90)–O(91)–U(52)	109.5017	–
5	H(189)–C(102)–C(101)	109.4429	110	199	C(99)–N(68)–C(66)	142.1348	–
6	H(188)–C(102)–C(101)	109.5013	110	200	C(99)–N(68)–U(52)	88.3756	–
7	H(187)–C(101)–H(186)	109.52	109.4	201	C(66)–N(68)–U(52)	120.0002	–
8	H(187)–C(101)–C(102)	109.46	109.41	202	H(145)–C(44)–H(144)	109.5214	109
9	H(187)–C(101)–C(100)	109.4592	109.41	203	H(145)–C(44)–H(143)	109.4628	109
10	H(186)–C(101)–C(102)	109.4429	109.41	204	H(145)–C(44)–C(34)	109.4592	110
11	H(186)–C(101)–C(100)	109.4424	109.41	205	H(144)–C(44)–H(143)	109.4439	109
12	C(102)–C(101)–C(100)	109.5028	109.5	206	H(144)–C(44)–C(34)	109.4407	110
13	H(175)–C(85)–H(174)	109.5202	109	207	H(143)–C(44)–C(34)	109.4994	110
14	H(175)–C(85)–H(173)	109.4617	109	208	C(43)–C(38)–C(39)	120.0016	120
15	H(175)–C(85)–C(84)	109.4622	110	209	C(43)–C(38)–N(32)	120.0004	120
16	H(174)–C(85)–H(173)	109.4416	109	210	C(39)–C(38)–N(32)	119.9979	120
17	H(174)–C(85)–C(84)	109.4417	110	211	C(34)–N(33)–N(32)	108.8333	115
18	H(173)–C(85)–C(84)	109.5	110	212	U(52)–O(37)–C(36)	109.5002	–
19	H(172)–C(84)–H(171)	109.5202	109.4	213	C(38)–N(32)–C(36)	124.4989	124
20	H(172)–C(84)–C(85)	109.4621	109.41	214	C(38)–N(32)–N(33)	124.4995	124
21	H(172)–C(84)–C(83)	109.4619	109.41	215	C(36)–N(32)–N(33)	111.0016	124
22	H(171)–C(84)–C(85)	109.4418	109.41	216	O(37)–C(36)–C(35)	124.3013	124.3
23	H(171)–C(84)–C(83)	109.4415	109.41	217	O(37)–C(36)–N(32)	124.7002	–
24	C(85)–C(84)–C(83)	109.4998	109.5	218	C(35)–C(36)–N(32)	110.9964	120
25	H(152)–C(48)–H(151)	109.5198	109	219	C(44)–C(34)–C(35)	130.916	121.4
26	H(152)–C(48)–H(150)	109.4634	109	220	C(44)–C(34)–N(33)	130.9171	115.1
27	H(152)–C(48)–C(47)	109.4633	110	221	C(35)–C(34)–N(33)	98.1669	120
28	H(151)–C(48)–H(150)	109.4378	109	222	H(147)–C(46)–H(146)	109.5191	109.4
29	H(151)–C(48)–C(47)	109.4404	110	223	H(147)–C(46)–C(47)	109.4614	109.41
30	H(150)–C(48)–C(47)	109.5027	110	224	H(147)–C(46)–C(45)	109.4622	109.41
31	H(149)–C(47)–H(148)	109.5196	109.4	225	H(146)–C(46)–C(47)	109.4432	109.41
32	H(149)–C(47)–C(48)	109.4635	109.41	226	H(146)–C(46)–C(45)	109.4421	109.41
33	H(149)–C(47)–C(46)	109.4615	109.41	227	C(47)–C(46)–C(45)	109.4994	109.5
34	H(148)–C(47)–C(48)	109.4404	109.41	228	C(45)–C(35)–C(36)	119.9963	120
35	H(148)–C(47)–C(46)	109.4428	109.41	229	C(45)–C(35)–C(34)	128.9985	120
36	C(48)–C(47)–C(46)	109.4995	109.5	230	C(36)–C(35)–C(34)	111.0018	120
37	H(137)–C(31)–H(136)	109.5199	109	231	O(112)–U(52)–O(109)	51.6495	–
38	H(137)–C(31)–H(135)	109.4613	109	232	O(112)–U(52)–O(91)	42.0125	–
39	H(137)–C(31)–C(30)	109.4618	110	233	O(112)–U(52)–N(68)	147.4002	–
40	H(136)–C(31)–H(135)	109.4421	109	234	O(112)–U(52)–O(54)	38.054	–
41	H(136)–C(31)–C(30)	109.4421	110	235	O(112)–U(52)–O(53)	22.6309	–
42	H(135)–C(31)–C(30)	109.5	110	236	O(112)–U(52)–O(37)	76.7568	–
43	H(134)–C(30)–H(133)	109.5199	109.4	237	O(112)–U(52)–N(14)	97.4632	–
44	H(134)–C(30)–C(31)	109.4618	109.41	237	O(109)–U(52)–O(91)	79.6415	–
45	H(134)–C(30)–C(29)	109.4616	109.41	239	O(109)–U(52)–N(68)	120.1793	–
46	H(133)–C(30)–C(31)	109.4422	109.41	240	O(109)–U(52)–O(54)	20.9895	–
47	H(133)–C(30)–C(29)	109.4418	109.41	241	O(109)–U(52)–O(53)	30.7916	–
48	C(31)–C(30)–C(29)	109.5	109.5	242	O(109)–U(52)–O(37)	29.8936	–
49	H(179)–C(96)–C(97)	119.9991	120	243	O(109)–U(52)–N(14)	123.009	–
50	H(179)–C(96)–C(95)	120.0055	120	244	O(91)–U(52)–N(68)	109.3268	–
51	C(97)–C(96)–C(95)	119.9954	–	245	O(91)–U(52)–O(54)	75.782	–
52	H(178)–C(95)–C(96)	119.9972	120	246	O(91)–U(52)–O(53)	51.4273	–
53	H(178)–C(95)–C(94)	119.9978	120	247	O(91)–U(52)–O(37)	109.5011	–
54	C(96)–C(95)–C(94)	120.0049	–	248	O(91)–U(52)–N(14)	109.5014	–
55	H(177)–C(94)–C(95)	119.9988	120	249	N(68)–U(52)–O(54)	141.1103	–
56	H(177)–C(94)–C(93)	120.0009	120	250	N(68)–U(52)–O(53)	134.6609	–
57	C(95)–C(94)–C(93)	120.0003	–	251	N(68)–U(52)–O(37)	109.4998	–
58	H(180)–C(97)–C(96)	120.002	120	252	N(68)–U(52)–N(14)	109.4981	–
59	H(180)–C(97)–C(92)	119.998	120	253	O(54)–U(52)–O(53)	25.2039	–
60	C(96)–C(97)–C(92)	120	–	254	O(54)–U(52)–O(37)	38.8859	–
61	H(176)–C(93)–C(94)	120.0044	120	255	O(54)–U(52)–N(14)	104.2898	–
62	H(176)–C(93)–C(92)	119.9985	120	256	O(53)–U(52)–O(37)	59.216	–
63	C(94)–C(93)–C(92)	119.9972	–	257	O(53)–U(52)–N(14)	115.6337	–
64	H(183)–C(98)–H(182)	109.5203	109	258	O(37)–U(52)–N(14)	109.4999	–
65	H(183)–C(98)–H(181)	109.4624	109	259	C(46)–C(45)–C(35)	112.9853	121.4
66	H(183)–C(98)–C(88)	109.4598	110	260	C(46)–C(45)–N(14)	112.9863	115.1
67	H(182)–C(98)–H(181)	109.444	109	261	C(35)–C(45)–N(14)	134.0284	120
68	H(182)–C(98)–C(88)	109.4413	110	262	H(126)–C(25)–C(26)	120.0012	120
69	H(181)–C(98)–C(88)	109.4995	110	263	H(126)–C(25)–C(24)	120.0009	120
70	C(97)–C(92)–C(93)	120.0021	120	264	C(26)–C(25)–C(24)	119.9979	–
71	C(97)–C(92)–N(86)	119.999	120	265	H(125)–C(24)–C(25)	119.999	120
72	C(93)–C(92)–N(86)	119.9989	120	266	H(125)–C(24)–C(23)	119.9993	120
73	C(88)–N(87)–N(86)	108.8333	115	267	C(25)–C(24)–C(23)	120.0017	–
74	C(92)–N(86)–C(90)	124.5007	124	268	H(124)–C(23)–C(24)	119.9993	120
75	C(92)–N(86)–N(87)	124.5019	124	269	H(124)–C(23)–C(22)	119.9994	120
76	C(90)–N(86)–N(87)	110.9975	124	270	C(24)–C(23)–C(22)	120.0013	–
77	O(91)–C(90)–C(89)	124.2987	124.3	271	H(127)–C(26)–C(25)	120.0005	120
78	O(91)–C(90)–N(86)	124.6986		272	H(127)–C(26)–C(21)	120.0002	120
79	C(89)–C(90)–N(86)	111.0006	120	273	C(25)–C(26)–C(21)	119.9994	–
80	C(98)–C(88)–C(89)	130.913	121.4	274	H(123)–C(22)–C(23)	120.0015	120
81	C(98)–C(88)–N(87)	130.9156	115.1	275	H(123)–C(22)–C(21)	120.0015	120
82	C(89)–C(88)–N(87)	98.1714	120	276	C(23)–C(22)–C(21)	119.997	–
83	H(164)–C(79)–C(80)	120.0009	120	277	H(106)–O(104)–H(105)	120.0002	–
84	H(164)–C(79)–C(78)	120.0013	120	278	H(106)–O(104)–U(49)	38.7833	–
85	C(80)–C(79)–C(78)	119.9977	–	279	H(105)–O(104)–U(49)	87.3774	–
86	H(163)–C(78)–C(79)	119.9991	120	280	H(108)–O(103)–H(107)	119.9999	–
87	H(163)–C(78)–C(77)	119.9989	120	281	H(108)–O(103)–U(49)	54.1558	–
88	C(79)–C(78)–C(77)	120.002	–	282	H(107)–O(103)–U(49)	136.9383	–
89	H(162)–C(77)–C(78)	119.9997	120	283	C(73)–O(74)–U(49)	109.5	–
90	H(162)–C(77)–C(76)	119.9992	120	284	C(82)–N(61)–C(56)	137.9429	–
91	C(78)–C(77)–C(76)	120.0011	–	285	C(82)–N(61)–U(49)	88.4062	–
92	H(165)–C(80)–C(79)	120	120	286	C(56)–N(61)–U(49)	120.0004	–
93	H(165)–C(80)–C(75)	120.0005	120	287	H(130)–C(27)–H(129)	109.5204	109
94	C(79)–C(80)–C(75)	119.9994	–	288	H(130)–C(27)–H(128)	109.4621	109
95	H(161)–C(76)–C(77)	120.002	120	289	H(130)–C(27)–C(17)	109.4618	110
96	H(161)–C(76)–C(75)	120.0011	120	290	H(129)–C(27)–H(128)	109.4423	109
97	C(77)–C(76)–C(75)	119.9969	–	291	H(129)–C(27)–C(17)	109.4414	110
98	H(168)–C(81)–H(167)	109.5199	109	292	H(128)–C(27)–C(17)	109.4993	110
99	H(168)–C(81)–H(166)	109.4623	109	293	C(26)–C(21)–C(22)	120.0027	120
100	H(168)–C(81)–C(71)	109.4615	110	294	C(26)–C(21)–N(15)	119.9989	120
101	H(167)–C(81)–H(166)	109.4422	109	295	C(22)–C(21)–N(15)	119.9983	120
102	H(167)–C(81)–C(71)	109.4417	110	296	C(17)–N(16)–N(15)	108.8313	115
103	H(166)–C(81)–C(71)	109.4997	110	297	U(49)–O(20)–C(19)	109.5	–
104	C(80)–C(75)–C(76)	120.0028	120	298	C(21)–N(15)–C(19)	124.5003	124
105	C(80)–C(75)–N(69)	119.9985	120	299	C(21)–N(15)–N(16)	124.4995	124
106	C(76)–C(75)–N(69)	119.9986	120	300	C(19)–N(15)–N(16)	111.0001	124
107	C(71)–N(70)–N(69)	108.8317	115	301	O(20)–C(19)–C(18)	124.2997	124.3
108	C(75)–N(69)–C(73)	124.5001	124	302	O(20)–C(19)–N(15)	124.6987	–
109	C(75)–N(69)–N(70)	124.5001	124	303	C(18)–C(19)–N(15)	110.9995	120
110	C(73)–N(69)–N(70)	110.9998	124	304	C(27)–C(17)–C(18)	130.9158	121.4
111	O(74)–C(73)–C(72)	124.2999	124.3	305	C(27)–C(17)–N(16)	130.9152	115.1
112	O(74)–C(73)–N(69)	124.6986		306	C(18)–C(17)–N(16)	98.169	120
113	C(72)–C(73)–N(69)	110.9995	120	307	H(132)–C(29)–H(131)	109.5202	109.4
114	C(81)–C(71)–C(72)	130.9157	121.4	308	H(132)–C(29)–C(30)	109.4614	109.41
115	C(81)–C(71)–N(70)	130.9154	115.1	309	H(132)–C(29)–C(28)	109.4621	109.41
116	C(72)–C(71)–N(70)	98.1689	120	310	H(131)–C(29)–C(30)	109.4416	109.41
117	H(185)–C(100)–H(184)	109.5198	109.4	311	H(131)–C(29)–C(28)	109.4419	109.41
118	H(185)–C(100)–C(101)	109.4597	109.41	312	C(30)–C(29)–C(28)	109.5002	109.5
119	H(185)–C(100)–C(99)	109.4592	109.41	313	C(28)–C(18)–C(19)	119.9988	120
120	H(184)–C(100)–C(101)	109.4426	109.41	314	C(28)–C(18)–C(17)	128.9977	120
121	H(184)–C(100)–C(99)	109.4428	109.41	315	C(19)–C(18)–C(17)	111	120
122	C(101)–C(100)–C(99)	109.5033	109.5	316	O(104)–U(49)–O(103)	53.8556	–
123	C(99)–C(89)–C(90)	119.9972	120	317	O(104)–U(49)–O(74)	37.1357	–
124	C(99)–C(89)–C(88)	129.002	120	318	O(104)–U(49)–N(61)	98.1849	–
125	C(90)–C(89)–C(88)	110.9972	120	319	O(104)–U(49)–O(51)	31.8285	–
126	C(100)–C(99)–C(89)	109.1842	121.4	320	O(104)–U(49)–O(50)	22.3214	–
127	C(100)–C(99)–N(68)	109.1789	115.1	321	O(104)–U(49)–O(20)	143.9394	–
128	C(89)–C(99)–N(68)	141.6369	120	322	O(104)–U(49)–N(7)	81.0862	–
129	H(160)–C(67)–C(66)	121.2629	120	323	O(103)–U(49)–O(74)	41.1877	–
130	H(160)–C(67)–C(62)	121.2633	120	324	O(103)–U(49)–N(61)	149.2458	–
131	C(66)–C(67)–C(62)	117.4738		325	O(103)–U(49)–O(51)	27.0507	–
132	N(68)–C(66)–C(67)	119.9999	120	326	O(103)–U(49)–O(50)	51.007	–
133	N(68)–C(66)–C(65)	119.999	120	327	O(103)–U(49)–O(20)	92.7494	–
134	C(67)–C(66)–C(65)	119.9987	120	328	O(103)–U(49)–N(7)	81.1091	–
135	H(159)–C(65)–C(66)	121.3739	120	329	O(74)–U(49)–N(61)	109.3273	–
136	H(159)–C(65)–C(64)	121.3743	120	330	O(74)–U(49)–O(51)	18.0181	–
137	C(66)–C(65)–C(64)	117.2517	–	331	O(74)–U(49)–O(50)	53.571	–
137	H(158)–C(64)–C(65)	120.9014	120	332	O(74)–U(49)–O(20)	109.5	–
139	H(158)–C(64)–C(63)	120.902	120	333	O(74)–U(49)–N(7)	109.5	–
140	C(65)–C(64)–C(63)	118.1965	–	334	N(61)–U(49)–O(51)	122.1951	–
141	H(157)–C(62)–C(67)	120.4759	120	335	N(61)–U(49)–O(50)	108.5971	–
142	H(157)–C(62)–C(63)	120.4761	120	336	N(61)–U(49)–O(20)	109.5	–
143	C(67)–C(62)–C(63)	119.048	–	337	N(61)–U(49)–N(7)	109.4999	–
144	C(64)–C(63)–C(62)	119.9993	120	337	O(51)–U(49)–O(50)	40.7173	–
145	C(64)–C(63)–C(59)	119.9985	120	339	O(51)–U(49)–O(20)	112.1193	–
146	C(62)–C(63)–C(59)	119.9997	120	340	O(51)–U(49)–N(7)	92.3342	–
147	H(156)–C(60)–C(59)	119.9998	120	341	O(50)–U(49)–O(20)	141.7797	–
148	H(156)–C(60)–C(55)	120.0004	120	342	O(50)–U(49)–N(7)	59.2489	–
149	C(59)–C(60)–C(55)	119.9999	–	343	O(20)–U(49)–N(7)	109.5	–
150	C(63)–C(59)–C(60)	119.9999	120	344	C(29)–C(28)–C(18)	113.4969	121.4
151	C(63)–C(59)–C(58)	119.9986	120	345	C(29)–C(28)–N(7)	113.4966	115.1
152	C(60)–C(59)–C(58)	119.999	120	346	C(18)–C(28)–N(7)	133.0065	120
153	H(155)–C(58)–C(59)	120.0034	120	347	U(52)–N(14)–C(45)	85.6895	–
154	H(155)–C(58)–C(57)	120.0029	120	348	U(52)–N(14)–C(12)	120.002	–
155	C(59)–C(58)–C(57)	119.9937	–	349	C(45)–N(14)–C(12)	108.3424	–
156	H(154)–C(57)–C(58)	120.0003	120	350	H(122)–C(13)–C(12)	119.9996	120
157	H(154)–C(57)–C(56)	120.0011	120	351	H(122)–C(13)–C(8)	120.0001	120
158	C(58)–C(57)–C(56)	119.9986	–	352	C(12)–C(13)–C(8)	120.0003	–
159	H(153)–C(55)–C(60)	120.0002	120	353	N(14)–C(12)–C(13)	120.0004	120
160	H(153)–C(55)–C(56)	120	120	354	N(14)–C(12)–C(11)	119.9986	120
161	C(60)–C(55)–C(56)	119.9998		355	C(13)–C(12)–C(11)	119.9985	120
162	H(170)–C(83)–H(169)	109.5195	109.4	356	H(121)–C(11)–C(12)	120.0006	120
163	H(170)–C(83)–C(84)	109.4622	109.41	357	H(121)–C(11)–C(10)	120.0008	120
164	H(170)–C(83)–C(82)	109.4621	109.41	358	C(12)–C(11)–C(10)	119.9986	–
165	H(169)–C(83)–C(84)	109.4418	109.41	359	H(120)–C(10)–C(11)	120.0003	120
166	H(169)–C(83)–C(82)	109.4415	109.41	360	H(120)–C(10)–C(9)	120.0007	120
167	C(84)–C(83)–C(82)	109.5001	109.5	361	C(11)–C(10)–C(9)	119.999	–
168	C(82)–C(72)–C(73)	119.9987	120	362	H(119)–C(8)–C(13)	120.0001	120
169	C(82)–C(72)–C(71)	128.9977	120	363	H(119)–C(8)–C(9)	119.9998	120
170	C(73)–C(72)–C(71)	111.0001	120	364	C(13)–C(8)–C(9)	120.0002	–
171	C(83)–C(82)–C(72)	108.9982	121.4	365	C(10)–C(9)–C(8)	119.9985	120
172	C(83)–C(82)–N(61)	108.998	115.1	366	C(10)–C(9)–C(5)	119.9988	120
173	C(72)–C(82)–N(61)	142.0038	120	367	C(8)–C(9)–C(5)	120.0002	120
174	N(61)–C(56)–C(57)	119.999	120	368	H(118)–C(6)–C(5)	120.0003	120
175	N(61)–C(56)–C(55)	119.9995	120	369	H(118)–C(6)–C(1)	120.0001	120
176	C(57)–C(56)–C(55)	119.999	120	370	C(5)–C(6)–C(1)	119.9997	–
177	H(141)–C(42)–C(43)	120.0002	120	371	C(9)–C(5)–C(6)	119.9997	120
178	H(141)–C(42)–C(41)	120.002	120	372	C(9)–C(5)–C(4)	119.9985	120
179	C(43)–C(42)–C(41)	119.9978		373	C(6)–C(5)–C(4)	119.9993	120
180	H(140)–C(41)–C(42)	119.9998	120	374	H(117)–C(4)–C(5)	120.0033	120
181	H(140)–C(41)–C(40)	119.9978	120	375	H(117)–C(4)–C(3)	120.0033	120
182	C(42)–C(41)–C(40)	120.0024	–	376	C(5)–C(4)–C(3)	119.9934	–
183	H(139)–C(40)–C(41)	120.0002	120	377	U(49)–N(7)–C(28)	84.7503	–
184	H(139)–C(40)–C(39)	119.9993	120	378	U(49)–N(7)–C(2)	120	–
185	C(41)–C(40)–C(39)	120.0005	–	379	C(28)–N(7)–C(2)	105.6275	–
186	H(142)–C(43)–C(42)	120	120	380	H(116)–C(3)–C(4)	120.0001	120
187	H(142)–C(43)–C(38)	119.9993	120	381	H(116)–C(3)–C(2)	120.0012	120
188	C(42)–C(43)–C(38)	120.0006	–	382	C(4)–C(3)–C(2)	119.9987	–
189	H(138)–C(39)–C(40)	120.002	120	383	N(7)–C(2)–C(3)	119.9986	120
190	H(138)–C(39)–C(38)	120.001	120	384	N(7)–C(2)–C(1)	120	120
191	C(40)–C(39)–C(38)	119.9971	–	385	C(3)–C(2)–C(1)	119.9989	120
192	H(114)–O(112)–H(113)	119.9989	–	386	H(115)–C(1)–C(6)	119.9999	120
193	H(114)–O(112)–U(52)	48.4389	–	387	H(115)–C(1)–C(2)	120	120
194	H(113)–O(112)–U(52)	152.1891	–	388	C(6)–C(1)–C(2)	120.0001	–

5 Conclusions

The satisfactory analytical data and all the studies presented above suggest that the complexes are of the compositions, [(UO₂)(L¹)₂(H₂O)₂], L¹H = N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-anisidine (bumphp-paH), N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-m-phenetidine (bumphp-mpH) or N-(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazolin-5′-one)-p-toluidine (bumphp-ptH), [UO₂(L²)(H₂O)₂] (where L²H₂ = N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-o-phenylenediamine (bumphp-ophdH₂), and [UO₂(μ-L³)(H₂O)₂]₂ (where L³H₂ = N,N′-bis(4′-butyrylidene-3′-methyl-1′-phenyl-2′-pyrazo-lin-5′-one)-benzidine (bumphp-bzH₂, V). The designing of the Schiff base ligands for the present study is based on the consideration that the uranyl ion, a hard Lewis acid, has a high affinity for hard donor (O, N) groups in order to form stable complexes. From the analytical data and the physical studies discussed above, the ligands L¹H, L²H and L³H have been shown to act as monobasic bidentate (N,O), dibasic tetradentate (N₂O₂) and ligand bridging dibasic tetradentate (N₂O₂), respectively. The coordination numbers of the complexes are 8 (Maurya and Maurya, 1995; Maurya et al., 1998), and based on these coordination numbers, the structures proposed for the complexes are shown in Fig. 5. X-ray crystallographic studies, which might confirm the proposed structures, could not be carried out as we failed to grow crystals of any of these complexes.

Acknowledgements

We are thankful to Prof. R. R. Miahra, Vice-Chancellor of this University, for encouragement. Analytical facilities provided by the Central Drug Research Institute, Lucknow, India, and the Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Chennai, India are gratefully acknowledged.

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Show Sections

[1] Alaudeen M.P., Sushama G., Dorothy A.M., . Indian J. Chem.. 2003;42A:1617. and references therein

[2] Back D.F., de Oliveira G.M., Ballin M.A., Corbellini V.A., . Inorg. Chim. Acta. 2010;363:807.

[3] Bailly T., Burgada R., Prange T., Lecouvey M., . Tetrahedron Lett.. 2002;44:189.

[4] Balman R.A., . Coord. Chem. Rev.. 1980;31:221.

[5] Berthetm J.-C., Nierlich M., Ephritikhine M., . J. Chem. Soc., Dalton Trans. 2004:2814.

[6] Burgada R., Bailly T., Prange T., Lecouvey M., . Tetrahedron Lett.. 2007;48:2315.

[7] Chen W., Yuan H.-M., Wang J.-Y., Liu Z.-Y., Xu J.-J., Yang M., Chen J.-S., . J. Am. Chem. Soc.. 2003;125:9266.

[8] Chouhan V.S., Rao G.N., . Bull. Chem. Soc. Japn.. 1982;55:301.

[9] Cotton F.A., Wilkinson G., . Advanced Inorganic Chemistry (fifth ed.). New York: Wiley; 1988. p. 992

[10] CS Chem 3D Ultra, Molecular Modeling and Analysis, Cambridge. Available from: <www.cambridgesoft.com>.

[11] Durbin P., Kullgren B., Ebbe S.N., Xu J., Raymond K.N., . Health Phys.. 2000;78:511.

[12] Evans W.J., Kozimor S.A., Ziller J.W., . J. Am. Chem. Soc.. 2003;125:14264.

[13] Finkel M.P., . Proc. Soc. Exp. Bio. Med.. 1953;83:494.

[14] Fortiera S., Hayton T.W., . Coord. Chem. Rev.. 2010;254:197.

[15] Fox A.R., Bart S.C., Meyer K., Cummins C.C., . Nature. 2008;455:341.

[16] Frisch M., Cahill C.L., . Dalton Trans. 2005:1518.

[17] Frisch M., Cahill C.L., . Dalton Trans. 2006:4679.

[18] Fukuda S., Iida H., Ikeda M., Yan X., Xie Y., . Health Phys.. 2005;89:81.

[19] Geary W.J., . Coord. Chem. Rev.. 1971;7:81.

[20] Goodman L.S., Gilman A., . The Pharmacological Basis of Therapeutics (fourth ed.). London: Macmillan; 1970.

[21] Gorden A.E.V., Xu J., Raymond K.N., Durbin P., . Chem. Rev.. 2003;103:4207.

[22] Hamilton J.G., . Rev. Mod. Phys.. 1948;20:718.

[23] Hutchings G.J., Heneghan C.S., Hudson I.D., Taylor S.H., . Nature. 1996;384:341.

[24] Jensen B.S., . Chem. Scand. Acta. 1959;13:1668.

[25] Jiang Y.-S., Li G.-H., Ye T., Liao Z.-L., Chen J.-S., . Inorg. Chem. Comm.. 2006;9:595.

[26] Jiang Y.-S., Yu Z.-T., Liao Z.-L., Li G.-H., Chen J.-S., . Polyhedron. 2006;25:1359.

[27] Jones L.H., . Specrochim. Acta.. 1958;10:359.

[28] Jones L.H., . Specrochim. Acta. 1959;11:409.

[29] Karalova Z.K., Pyzhova I., . Zh. Anal. Khim.. 1968;23:1564. Chem. Abstr. 69, 63899v

[30] Korotkin Y.S., . Radiokhim.. 1981;23:186. Chem. Abstr. 95, 69620f

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Coordination chemistry of pyrazolone based Schiff bases relevant to uranyl sequestering agents: Synthesis, characterization and 3D molecular modeling of some octa-coordinate mono- and binuclear-dioxouranium(VI) complexes

Abstract

Keywords

Dioxouranium(VI) chelates

Mono- and binuclear

Pyrazolone based Schiff base ligands

3D Molecular modeling

1 Introduction

2 Experimental

2.1 Materials

2.2 Preparation of 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one (bumphpH)

2.3 Synthesis of the Schiff bases

2.4 Synthesis of complexes

2.5 Analyses

3 Physical methods

4 Results and discussion

4.1 Infrared spectra

4.1.1 Complexes with bumphp-paH (I), bumphp-mpH (II) or bumphp-ptH (III)

4.1.2 Complex with bumphp-ophdH2 (IV)

4.1.3 Complex bumphp-bzH2 (V)

4.2 Conductance measurements

4.3 Magnetic measurements

4.4 Electronic spectra

4.5 1H NMR spectra

4.6 Thermogravimetric analysis

4.7 3D Molecular modeling and analysis

5 Conclusions

Acknowledgements

References

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4.1.2 Complex with bumphp-ophdH₂ (IV)

4.1.3 Complex bumphp-bzH₂ (V)

4.5 ¹H NMR spectra