Mono and dinuclear hydrotris(3,5-dimethylpyrazolyl)borato tantalum complexes

摘要

In an effort to obtain suitable starting materials, the synthesis and crystal structure of hydrotris(3,5-dimethylpyrazolyl)borato (Tp(Me2)) tantalum(III) complexes are reported. Reaction of KTp(Me2) with [TaCl2(tht)](2)(mu-Cl)(2)(mu-tht) (1) (tht = tetrahydrothiophene) gives the X-ray characterized unsymmetrical (Tp(Me2)Ta)(TaCl3)(mu-tht) (2) in fair yield. This doubly bonded Ta=Ta complex [2.6791(5) Angstrom, diamagnetic, 18e per Ta] is a rare example of an unsymmetrical Ta2X6L3 complex. The X-ray structure of Tp(Me2) TaCl2(PhCdropCMe) (3) is also reported. It has the (4e)-alkyne in the symmetry plane of the molecule. The trans effects of tht and phenylpropyne are discussed. 1 is inert towards the reaction with a second equivalent of KTp(Me2). (C) 2003 Elsevier Ltd. All rights reserved.