New scorpionate oxovanadium complexes: Syntheses and crystal structures of a series of vanadium (IV) complexes with mixed ligands of polypyrazolylborates and substituted acetylacetonates

Abstract

The reaction of [VO(R1-acac)2] (R1 = Me or Et; acac = acetylacetonate) with Na[HB(pz)3] (pz = pyrazole) or Na[HB(3,5-Me2pz)3] in MeOH gave a series of new oxovanadium (IV) complexes: [VO{HB(pz)3}(Me-acac)] (1), [VO{HB(3,5-Me2pz)3}(Me-acac)] (2), [VO{HB(pz) 3}(Et-acac)] (3) and [VO{HB(3,5-Me2pz)3}(Et- acac)] (4), respectively. All complexes have similar distorted octahedral coordination about vanadium, [VO(N3O2)], in which the basal plane is defined by the N4, N6 atoms from the tridentate ligand and the O 2, O3 atoms from the R1-acac ligand. However, the dihedral angles between the plane formed by O2, V and O 3, and the plane of the pentane-2, 4-dionato ligand (O2, C1, C2, C3 and O3) are variously different; 3.59° for 1, 74.54° for 2, 0.92° for 3, and 29.50° for 4, respectively. In addition, ab initio calculations on 1,2,3 and 4 have given the energies and characters of the selected MOs, the atomic net charge and the NBO bond order. The order of stability of the complexes is 1 ≅ 2 ≅ 4 > 3.