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(R 1 -acac) 2 ] (R 1 = Me or Et; acac = acetylacetonate) with Na[HB(pz) 3 ] (pz = pyrazole) or Na[HB(3,5-Me 2 pz) 3 ] in MeOH gave a series of new oxovanadium (IV) complexes: [VO{HB(pz) 3 }(Me-acac)] (1), [VO{HB(3,5-Me 2 pz) 3 }(Me-acac)] (2), [VO{HB(pz) 3 }(Et-acac)] ( 3) and [VO{HB(3,5-Me 2 pz) 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 N 4 , N 6 atoms from the tridentate ligand and the O 2 , O 3 atoms from the R 1 -acac ligand. However, the dihedral angles between the plane formed by O 2 , 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.