Novel vanadium complexes supported by a bulky tris(pyrazolyl)borate ligand

Abstract

The V(III) complex [V(TptBu2)Cl2] (1, TptBu2=hydrotris(3,5-di-tert-butylpyrazolyl)borate) was synthesized by the reaction of [VCl3(THF)3] (prepared in situ) and K(TptBu2). Reduction of 1 with potassium mirror afforded the V(II) complex [V(TptBu2)Cl] (2). Both complexes were characterized by means of a single crystal X-ray diffraction. 1 represents the first example of pentacoordinated vanadium tris(pyrazolyl)borate (Tp) complexes. The V(III) ion environment is a distorted trigonal bipyramid. 2 is the first V(II) Tp-complex. The V(II) ion has tetrahedral environment, and the Cl atom is deviated from the B–V axis (∠B(1)–V(1)–Cl(1)=157.8°). Magnetic susceptibility measurements showed reasonable µeff values at 300K: 2.80 (1) and 3.78 (2) µB, those prove the oxidation states of V: +3 (1) and +2 (2).