Controlled coordination in vanadium(V) dimethylhydrazido compounds

Abstract

The vanadium(V) dimethylhydrazido compounds were structurally characterized to elucidate the effect of the alkoxide ligands in the coordination environment of vanadium(V) hydrazido center. The single-crystal X-ray structure determination of the vanadium(V) dimethylhydrazido compound with isopropoxide ligands revealed a dimeric structure with the V(1)-N(1) distance of 1.680(5)Å, in which each vanadium atom is coordinated in a distorted trigonal-bipyramidal geometry (τ=0.81) with the hydrazido and bridging isopropoxide ligands in the apical positions. On the contrary, nearly tetrahedral arrangement around the vanadium metal center (τ=0.06) with the V(1)-N(1) distance of 1.660(2)Å was observed in the vanadium(V) dimethylhydrazido compound with tert-butoxide ligands. The introduction of the 2,2',2″-nitrilotriethoxide ligand led to a pseudo-trigonal-bipyramidal geometry (τ=0.92) at the vanadium center with the V(1)-N(1) distance of 1.691(5)Å, wherein vanadium atom is pulled out of the plane formed by the nitrilotriethoxide oxygen atoms in the direction of the hydrazido nitrogen. The coordination from the apical ligand in the vanadium(V) dimethylhydrazido compound was found to result in the longer V(1)-N(1) distance.

Structural Characterization of (Diphenylhydrazido)vanadium(V) Compounds

“…A dihedral angle between the least‐squares planes of the benzene rings Aph and Bph is 58.3(2)°. Furthermore, compared with N(1)‐N(2) distance of (dimethylhydrazido)vanadium(V) nitrilotriethoxide (1.311(7) Å), the longer N(1)‐N(2) distance of 2 was observed probably due to the π conjugation. In the crystal packing, meta hydrogen atom of the benzene ring Aph is almost facing the π electrons of the benzene ring Bph of the neighboring molecule.…”

“…These results suggest that the nitrogen of the V−N bond has an sp‐hybridized character. The N(1)‐N(2) distance of 1 is longer than that of (dimethylhydrazido)vanadium(V) triisopropoxide (1.321(8) Å), because of conjugation between the lone pair on N(2) and benzene rings. A dihedral angle between the least‐squares plane of the benzene ring Aph and the plane of C(16)‐N(2)‐N(1) is 4.1(1)°, indicating that π orbital of the N−N bond appears to interact with aryl π orbitals.…”

“…Although (imido)vanadium(V) alkoxides with vanadium‐nitrogen multiple bond have been demonstrated to dimerize through μ ‐alkoxido‐bridging, self‐assembling properties of hydrazido compounds of vanadium(V) with alkoxide ligands have not been studied extensively. Recently, alkoxide ligands of (dimethylhydrazido)vanadium(V) have been demonstrated to regulate the self‐association properties through the control of coordination environment, wherein isopropoxide ligands were found to induce a μ ‐isopropoxido‐bridged dimeric structure with a trigonal‐bipyramidal geometry although a monomeric tetrahedral structure was observed in the case of tert ‐butoxide ligands . Substituents on the hydrazido moiety of (hydrazido)vanadium(V) alkoxides is envisioned to affect the electronic and steric properties of the vanadium‐nitrogen multiple bond and self‐assembling properties.…”