Synthesis of new oxy and thiolate [hydro-tris(pyrazol-1-yl)borato] titanium and zirconium(IV) complexes. Molecular structure of [Ti(HB(3,5-Me 2pz) 3)Cl 3

Abstract

The complexes [M(HB(3,5-Me 2pz) 3)Cl 2(LL)] (pz=pyrazolyl, M=Ti, LL=2-oxy-6-methylpyridine, 2,4-dimethyl-6-oxypyrimidine; M=Zr, LL=4,6-dimethyl-2-thiolatepyrimidine) have been prepared by the reaction of the starting materials [M(HB(3,5-Me 2pz) 3)Cl 3] (M=Ti, Zr) and one equivalent of the lithium salt or the protic form of the corresponding hydroxy or thiolato pyridine or pyrimidine. The complexes were characterized by spectroscopic methods. While the titanium complexes are rigid in solution, the zirconium complex is fluxional at room temperature, although limiting static spectra can be obtained at low temperature. The variable temperature 1H-NMR spectra indicate that a mechanism involving interchange of both nitrogen atoms of pyrimidine, in the coordination sphere of the zirconium atom, can explain this dynamic behavior. In addition, the molecular structure of the starting material [Ti(HB(3,5-Me 2pz) 3)Cl 3] has been determined by X-ray diffraction methods.