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Crystal structure and DFT calculations of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) complex
*Corresponding author. Tel./fax: +98 341 322 2033 i_shoaie@yahoo.com (Iran Sheikhshoaie)
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Available online 22 August 2010
Abstract
The crystal and molecular structure of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) was determined by single crystal X-ray diffraction. B3LYP/DZP basis set theoretical calculations nicely reproduce the X-ray experimental geometry. The obtained results are discussed in connection with the electronic and structural properties of the compound.
Keywords
Crystal structure
Dioxomolybdenum (VI)
Theoretical calculation
B3LYP DZP basis sets
1 Introduction
Molybdenum (VI) dioxo compounds are commonly encountered in enzyme and metal surface models, oxidation catalysis and oxygen atom transfer reactions (Cervilla et al., 1991). We and others have reported on the epoxidation of sulfides and olefins catalyzed by a large of molybdenum (VI) dioxo complexes (Sheikhshoaie et al., 2009; Rezaeifard et al., 2010; Bagherzadeh et al., 2008; Hroch et al., 2000; Herrmann et al., 1997; Gómez et al., 2001; Kuhn et al., 2000a,b, 2001a,b). We report here the single crystal X-ray structure for the methanol {E-N′-(2- hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) complex, this compound has been studied theoretically and experimentally by NMR, IR and UV-vis spectroscopy.
2 Synthesis
The titled (Scheme 1) complex was prepared by this common method. A dry methanol solution (15 ml) of MoO2 (acac)2 (0.327 g) was added to another solution (15 ml) of (E)-N′-(2-hydroxybenzlidene)benzohydrazid (0.240 g). The mixture was refluxed for 6 h. The clear solution was cooled to room temperature. A yellow powder separated was collected by filtration and dried in air. Crystals of the title MoVI complex, suitable for X-ray analysis, were obtained as yellow blocks by slow evaporation at room temperature in a solution of ethanol.
2.1 X-ray structure determination
Suitable crystals of methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) were obtained as yellow rods. The intensity data were collected at 233 K (−40 °C) on a Stoe Mark II-Image Plate Diffraction System (Stoe, 2009) equipped with a two-circle goniometry and using MoKα graphite monochromatic radiation (λ = 0.71073 Å). Image plate distance 130 mm, ω rotation scans 0–180° at φ 0°, and 0–92.0° at φ 90°, step Δω = 1.0°, exposures of 6 mines per image, 2θ range 1.76–52.59°, dmin–dmax = 23.107–0.802 Å. The structure was solved by direct methods using the program SHELXS-97 (Sheldrick, 2008). The refinement and all further calculations were carried out using SHELXL-97 (Spek, 2009). The OH H-atom was located from a difference electron-density map and refined with a distance restraint of 0.84(2) Å. The remaining H-atoms were included in calculated positions and treated as riding atoms using SHELXL default parameters. The non-H atoms were refined anisotropically, using weighted full-matrix least-squares on F2. An empirical absorption correction was applied using the MUL scan ABS routine in PLATON. The molecular structure and crystallographic numbering scheme are illustrated in the PLATON drawing, Fig. 1, and the crystal packing viewed along the b-axis is illustrated in Fig. 2 (the O–H···N hydrogen bonds are shown as dashed lines). Some of X-ray’s data for the titled compound were shown in Tables 1–3.

| Formula | C15 H14 Mo N2 O5 |
| Formula weight | 398.22 |
| Crystal system | Triclinic |
| Space group | P-1 |
| a, b, c [Å] | 7.8478 (13), 9.7989 (16), 10.3766(17) |
| Alpha, beta, gamma (deg) | 94.315 (13), 107.834 (13), 90.565(13) |
| V (Å3) | 757.0 (2) |
| Z | 2 |
| D(calc) (g/cm**3) | 1.747 |
| Mu(MoKα) (/mm) | 0.894 |
| F (0 0 0) | 400 |
| Crystal size (mm) | 0.15 × 0.15 × 0.40 |
| Temperature (K) | 233 |
| Radiation (Angstrom) | MoKα 0.71073 |
| Theta Min–Max (deg) | 2.1, 25.1 |
| Dataset | −9: 9; −11: 11; −12: 12 |
| Tot., Uniq. data, R (int) | 7483, 2696, 0.123 |
| Observed data (I > 2.0 sigma (I)) | 2195 |
| Nref, Npar | 2696, 213 |
| R, wR2, S | 0.0632, 0.1511, 1.00 |
| Atom | x | y | z | U (eq) (Ang^2) |
|---|---|---|---|---|
| Mo1 | 0.18299(7) | 0.74501(5) | 0.35415(5) | 0.0349(2) |
| O1 | 0.2149(6) | 0.8351(4) | 0.5321(5) | 0.0426(16) |
| O2 | 0.2402(6) | 0.5888(4) | 0.2376(4) | 0.0406(12) |
| O3 | −0.0407(6) | 0.7151(5) | 0.3074(5) | 0.0510(17) |
| O4 | 0.2168(6) | 0.8739(5) | 0.2642(5) | 0.0510(17) |
| O5 | 0.4978(6) | 0.7478(5) | 0.4335(5) | 0.0455(16) |
| N1 | 0.2485(6) | 0.5613(5) | 0.4755(5) | 0.0305(16) |
| N2 | 0.2980(6) | 0.4449(5) | 0.4082(5) | 0.0324(16) |
| C1 | 0.1760(8) | 0.7958(7) | 0.6427(6) | 0.0379(19) |
| C2 | 0.1307(8) | 0.8984(7) | 0.7266(7) | 0.047(2) |
| C3 | 0.1037(9) | 0.8622(8) | 0.8460(8) | 0.051(3) |
| Bond | Experimental (X-ray) | Theoretical (B3LYP/DZP) | Bond | Experimental (X-ray) | Theoretical (B3LYP/DZP) |
|---|---|---|---|---|---|
| Mo1–O1 | 1.928 | 2.025 | N1–N2 | 1.412 | 1.376 |
| Mo1–O2 | 2.019 | 2.069 | N1–C7 | 1.281 | 1.291 |
| Mo1–O3 | 1.688 | 1.743 | N2–C8 | 1.303 | 1.305 |
| Mo1–O4 | 1.691 | 1.756 | C1–C2 | 1.40 | 1.402 |
| Mo1–O5 | 2.352 | 2.539 | C1–C6 | 1.39 | 1.421 |
| Mo1–N1 | 2.248 | 2.326 | C2–C3 | 1.39 | 1.387 |
| O1–C1 | 1.356 | 1.340 | C5–C6 | 1.42 | 1.411 |
| O2–C8 | 1.301 | 1.318 | C6–C7 | 1.458 | 1.448 |
| O5–C15 | 1.415 | 1.444 | C7–H7 | 0.940 | 1.090 |
| O5–H5O | 0.84 | 0.976 | C8–C9 | 1.470 | 1.479 |
CCDC 785592 contains the supplementary crystallographic data for this paper, this data can be obtained free of charge at www.ccdc.cam.ac.uk (or from the Cambridge Crystallographic Data Center (CCDC), 12 Union Road, Cambridge CB2 1EZ, UK; +44 (0) 1223 336033; e-mail: deposit@ccdc.cam.ac.uk).
2.2 Theoretical calculations
All calculations in the present study were performed by using the ADF 2009.01 program (Spek, 2003; te Velde et al., 2001; Fonseca Guerra et al., 1998; ADF, 2009.01). The stationary points on potential energy surfaces were located by using B3LYP density functional calculations (Becke, 1993,1988; Lee et al., 1988; Canal Neto et al., 2005), with the DZP basis sets (all-electron double zeta plus polarization function) (Lee et al., 1988; Camiletti et al., 2008). The geometrical parameters of the titled complex have been optimized with B3LYP DZP basis sets.
The final positional parameters for some important atoms are given in Table 2, and some experimental and theoretical bond lengths are summarized in Table 3 and some experimental and theoretical bond angles are listed in Table 3.
Some of electronic properties of this molybdenum (VI) complex were shown in Table 5.
The contributions of atomic orbital in each molecular orbital (HOMO and LUMO) are shown in Table 6. Each percentage contribution in the table below corresponds to the indicated SFO. In general, a SFO may be a linear combination of several fragment orbital on the same, or on symmetry-related fragments. Plots of frontier molecular orbitals of HOMO and LUMO are shown in Figs. 5 and 6; also the orbital energies are given in Table 5.
| % (contribution of atomic orbital) | SFO | E (eV) | Number of MO | Fragment | |
|---|---|---|---|---|---|
| HOMO with 2 electrons (60A) | 14.42% | 1 P:x | −7.531 | 1.00 | N2 |
| 6.42% | 1 P:x | −7.531 | 1.00 | N1 | |
| 5.90% | 1 P:x | −5.298 | 0.67 | C6 | |
| 4.99% | 1 P:x | −5.298 | 0.67 | C1 | |
| 4.36% | 1 P:x | −5.298 | 0.67 | C12 | |
| 4.24% | 1 P:x | −5.298 | 0.67 | C8 | |
| 3.85% | 1 P:x | −5.298 | 0.67 | C7 | |
| 3.80% | 1 P:x | −5.298 | 0.67 | C4 | |
| 3.63% | 1 P:x | −10.182 | 1.33 | O1 | |
| 3.58% | 1 P:x | −5.298 | 0.67 | C3 | |
| 3.41% | 1 P:z | −5.298 | 0.67 | C6 | |
| 3.32% | 1 P:z | −5.298 | 0.67 | C1 | |
| 3.13% | 1 P:x | −5.298 | 0.67 | C9 | |
| 2.81% | 1 P:x | −10.182 | 1.33 | O2 | |
| 2.74% | 1 P:z | −5.298 | 0.67 | C4 | |
| 2.66% | 1 P:x | −5.298 | 0.67 | C10 | |
| 2.57% | 1 P:z | −5.298 | 0.67 | C3 | |
| 1.95% | 1 P:z | −7.531 | 1.00 | N2 | |
| 1.72% | 1 P:x | −5.298 | 0.67 | C14 | |
| 1.48% | 1 P:z | −7.531 | 1.00 | N1 | |
| 1.29% | 1 P:z | −10.182 | 1.33 | O1 | |
| 1.12% | 1 P:z | −10.182 | 1.33 | O2 | |
| 1.11% | 1 P:y | −10.182 | 1.33 | O3 | |
| 1.08% | 1 P:x | −5.298 | 0.67 | C13 | |
| LUMO (61 A) | 9.39% | 1 D:x2–y2 | −3.661 | 1.00 | Mo1 |
| 8.52% | 1 D:xz | −3.661 | 1.00 | Mo1 | |
| 8.44% | 1 P:x | −5.298 | 0.67 | C7 | |
| 7.65% | 1 D:xy | −3.661 | 1.00 | Mo1 | |
| 7.57% | 1 P:y | −10.182 | 1.33 | O3 | |
| 6.72% | 1 P:z | −10.182 | 1.33 | O4 | |
| 6.51% | 1 D:yz | −3.661 | 1.00 | Mo1 | |
| 5.09% | 1 P:z | −10.182 | 1.33 | O3 | |
| 4.70% | 1 P:x | −5.298 | 0.67 | C8 | |
| 2.99% | 1 P:x | −7.531 | 1.00 | N1 | |
| 2.70% | 1 P:x | −5.298 | 0.67 | C3 | |
| 2.38% | 1 P:y | −10.182 | 1.33 | O4 | |
| 1.99% | 1 P:z | −5.298 | 0.67 | C1 | |
| 1.98% | 1 P:z | −5.298 | 0.67 | C7 | |
| 1.62% | 1 P:x | −5.298 | 0.67 | C5 | |
| 1.61% | 1 P:z | −5.298 | 0.67 | C3 | |
| 1.54% | 1 P:x | −5.298 | 0.67 | C12 | |
| 1.50% | 1 P:z | −5.298 | 0.67 | C5 | |
| 1.30% | 2 D:xz | 4.940 | 0.00 | Mo1 | |
| 1.29% | 1 P:x | −5.298 | 0.67 | C1 | |
| 1.17% | 1 P:x | −5.298 | 0.67 | C10 | |
| 1.13% | 1 P:x | −5.298 | 0.67 | C14 | |
| 1.04% | 2 D:x2–y2 | 4.940 | 0.00 | Mo1 |


DFT calculations predict two close lying transitions (440 nm (HOMO/LUMO with oscillator strength 0.0669726) and 340 nm (HOMO/LUMO+4 with oscillator strength 0.265256) (see Fig. 4).
Fig. 7 shows the calculated molecular orbitals diagram for methanol {E-N′-(2-hydroxybenzlidene)benzohydrazido}dioxidomolybdenum (VI) molecule calculated by using B3LYP DZP method.
3 Results and discussion
In the present study, we have carried out B3LYP DZP calculations using ADF 2009.01 program to determine the best molecular configuration of the title complex. The initial geometry for input to the DFT calculation was obtained by means of the MM+ molecular mechanic program for gas phase. In order to optimize the geometry of the compound, the DFT method is used. As a result of energy minimizing study on this metal complex, some selected bond distances and bond angles are given in Tables 3 and 4. According to the geometry optimization in the gas phase, proposed molecular structure of this complex are shown in Fig.3. In this paper, we compare the DFT calculated geometries data of the titled molybdenum complex with its X-ray data. We saw a good agreement between theoretical and experimental data in this study.
| Angle | Experimental (X-ray) | Theoretical (B3LYP/DZP) | Angle | Experimental (X-ray) | Theoretical (B3LYP/DZP) |
|---|---|---|---|---|---|
| O1–Mo1–O2 | 149.1 | 142.4 | Mo1–O1–C1 | 132.6 | 126.8 |
| O1–Mo1–O3 | 98.4 | 101.0 | Mo1–O2–C8 | 121.6 | 120.1 |
| O1–Mo1–O4 | 103.1 | 103.3 | Mo1–O5–C15 | 126.7 | 117.9 |
| O1–Mo1–O5 | 82.1 | 74.8 | Mo1–O5–H5O | 122 | 102.9 |
| O1–Mo1–N1 | 81.5 | 79.0 | C15–O5–H5O | 111 | 109.9 |
| O2–Mo1–O3 | 97.5 | 102.7 | Mo1–N1–N2 | 115.4 | 115.5 |
| O2–Mo1–O4 | 97.6 | 97.4 | Mo1–N1–C7 | 127.4 | 125.8 |
| O2–Mo1–O5 | 77.7 | 77.5 | N2–N1–C7 | 117.1 | 118.3 |
| O2–Mo1–N1 | 71.0 | 69.9 | N1–N2–C8 | 109.3 | 110.2 |
| O3–Mo1–O4 | 106.2 | 106.6 | O1–C1–C2 | 117.2 | 118.0 |
| O3–Mo1–O5 | 169.8 | 171.5 | O1–C1–C6 | 121.8 | 122.7 |
| O3–Mo1–N1 | 94.5 | 95.7 | C1–C6–C7 | 124.1 | 123.1 |
| O4–Mo1–O5 | 83.4 | 81.8 | N1–C7–C6 | 122.9 | 123.7 |
| O4–Mo1–N1 | 157.7 | 156.6 | N1–C7–H7 | 118.6 | 118.0 |
| O5–Mo1–N1 | 75.5 | 76.3 | O2–C8–N2 | 122.8 | 124.1 |

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