Solvent (methanol) coordinated vanadium(V) chalcogenido complexes bearing chlorido and methoxido ligands have been studied computationally by means of density functional (DFT) methods. The gas phase complexes were fully optimized using B3LYP/GEN functionals with 6-31+
Chalcogens (Ch) (group of 16 elements) form one of the interesting groups of elements on the periodic table. They represent the first group of nonmetals for which all the nonradioactive members (except Po) are known to form multiple bonds with the transition metals [
Vanadium chalcogenido complexes are known for their biological and catalytic functions [
Interest in softer chalcogen (S and Se) containing complexes is rapidly increasing because of their potential application in bioinorganic and coordination chemistry [
Version 5.38 of the CSD (November 2016) plus one update was used for the analysis of the full interaction maps. The CSD program
The input files of the respective complexes were prepared using the GaussView 5.0.8 molecular structure viewer [
The optimized geometries and selected atomic numbering scheme of the complexes in the gas phase are shown in Figure
Optimized geometries of the respective complexes. A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2. Hydrogen atoms have been removed for clarity.
Selected bond lengths and angles of the optimized and reference structures are listed in Table
Selected bond lengths (Å) and angles (°) for the respective complexes.
Parameter |
|
Calculated | ||
---|---|---|---|---|
|
|
| ||
V-Ch | 1.5778(16) | 1.561 | 2.002 | 2.147 |
V-O(6) | 1.7446(15) | 1.737 | 1.727 | 1.724 |
V-O(2) | 2.1132(16) | 2.250 | 2.257 | 2.250 |
V-O(7) | 2.2268(16) | 2.403 | 2.444 | 2.426 |
V-Cl(4) | 2.3108(7) | 2.314 | 2.318 | 2.331 |
V-Cl(3) | 2.3442(8) | 2.333 | 2.328 | 2.317 |
Ch-V-O(6) | 99.65(8) | 100.74 | 100.74 | 101.17 |
Ch-V-O(2) | 92.33(8) | 94.83 | 96.11 | 96.06 |
Ch-V-O(7) | 171.62(8) | 173.99 | 172.61 | 171.94 |
O(6)-V-O(2) | 167.77(7) | 163.93 | 161.92 | 162.52 |
O(6)-V-Cl(4) | 96.68(6) | 97.65 | 97.32 | 96.27 |
O(2)-V-Cl(4) | 84.26(5) | 83.64 | 83.68 | 83.61 |
O(6)-V-Cl(3) | 94.64(5) | 96.10 | 95.46 | 96.22 |
O(2)-V-Cl(3) | 81.38(5) | 77.27 | 76.94 | 77.22 |
ref: [
The selected bond lengths and angles of the optimized oxido complex compare favorably with those of the reference compound. The slight differences are as a result of the fact that the theoretical calculations were carried out on a single molecule in the gas phase, whereas in the crystal there are lattice interactions which could affect the bond parameters. From Table
NBO and second-order perturbation theory analysis of Fock Matrix provide details about the electron distribution in the various atomic and molecular orbitals and the strength of the interactions between metal ions and donor atoms [
Electronic configuration of selected atoms.
Atom | Electronic configuration | ||
---|---|---|---|
|
|
| |
V(1) | [core]4s0.273d3.744p0.49 | [core]4s0.323d4.234p0.64 | [core]4s0.353d4.254p0.7 |
O(2) | [core]2s1.642p5.05 | [core]2s1.642p5.05 | [core]2s1.632p5.04 |
Cl(3) | [core]3s1.863p5.40 | [core]3s1.853p5.37 | [core]3s1.853p5.36 |
Cl(4) | [core]3s1.863p5.38 | [core]3s1.853p5.37 | [core]3s1.853p5.38 |
O(5) | [core]2s1.782p4.39 | — | — |
S(21) | — | [core]3s1.743p3.86 | — |
Se(21) | — | — | [core]4s1.754p3.79 |
O(6) | [core]2s1.632p4.77 | [core]2s1.612p4.76 | [core]2s1.602p4.76 |
O(7) | [core]2s1.662p5.06 | [core]2s1.662p5.05 | [core]2s1.662p5.04 |
A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2.
NPA charge distribution of respective atoms in the complexes.
Atom | Charge | ||
---|---|---|---|
|
|
| |
V(1) | 0.447 | −0.222 | −0.331 |
O(2) | −0.715 | −0.707 | −0.681 |
Cl(3) | −0.270 | −0.235 | −0.212 |
Cl(4) | −0.251 | −0.228 | −0.233 |
O(5) | −0.187 | — | — |
S(21) | — | 0.391 | — |
Se(21) | — | — | 0.445 |
O(6) | −0.420 | −0.394 | −0.377 |
O(7) | −0.749 | −0.744 | −0.716 |
A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2.
Similar charges of −0.222 and −0.331 were calculated for the sulfido and selenido congeners. These reduced ionic charges can be attributed to the significant charge delocalization from the respective Ch ligand. As shown in Table
The molecular electrostatic potential, in Hartrees, at the 0.001 electron Bohr−3 isodensity surface of the respective complexes. A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2.
The presence of empty vanadium
The 3d-orbital occupancy and energy of the central vanadium ion in the various complexes.
Orbital |
|
|
| |||
---|---|---|---|---|---|---|
Occupancy | Energy | Occupancy | Energy | Occupancy | Energy | |
|
0.6890 | −0.204 | 0.8219 | −0.210 | 0.8744 | −0.193 |
|
0.7166 | −0.203 | 0.7369 | −0.210 | 0.9648 | −0.205 |
|
0.8034 | −0.230 | 0.9646 | −0.238 | 0.6912 | −0.198 |
|
0.7676 | −0.229 | 0.8871 | −0.226 | 0.8740 | −0.240 |
|
0.7618 | −0.208 | 0.8151 | −0.218 | 0.8464 | −0.235 |
A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2.
The strength of the interaction between ligand orbitals and the central vanadium orbitals was investigated by second-order interaction energy (
Despite the fact that selenium has the largest electron cloud among the selected chalcogens (O, S, Se), least interaction energies were recorded for molecular orbitals of the seleno complex. A value of 4.83 kcal/mol (the highest) was observed for LP(1)Se21→
The frontier orbitals direct the electronic and chemical properties of molecules [
Frontier orbital energies of the respective complexes. A: VOCl2(OMe)(HOMe)2, B: VSCl2(OMe)(HOMe)2, and C: VSeCl2(OMe)(HOMe)2.
Finally, the full interaction map for the reference complex [
Full interaction map of the reference complex.
Generally, this work has been shown by DFT computational analyses that octahedral solvated (methanol) oxovanadium(V) complexes bearing chlorido and methoxido ligands are more stable than the corresponding sulfido and seleno congeners because of substantial O p
In this paper, the relative stability of three octahedral solvent (methanol) coordinated chalcogenido (O, S, Se) vanadium(V) complexes bearing chlorido ligands has been investigated by DFT computational analyses. The stability of the complexes is in the order
The authors declare that there are no conflicts of interest regarding the preparation and publication of this manuscript.
The authors are grateful to The Cambridge Crystallographic Data Centre (CCDC) for the opportunity to use the Cambridge Structural Database (CSD) for the molecular searches and full interaction map (FIM) studies.