SYNTHESIS AND CHARACTERIZATION OF NEW NIOBIUM HYDRIDOTRIS(3,5-DIMETHYLPYRAZOL-1-YL)BORATO COMPLEXES

Reaction of the binuclear alkoxide species [Nb(Cl)(3)(OR)(2)](2) (R =M e, Et) with potassium hydridotris (3,5-dimethylpyrazol-1-yl)borate, KT p, leads to Tp*Nb(O)(Cl)(OR) (R =Me(1), Et(2)). These complexes react with Me3SiCl or PCl3 to give TpNb(O)(Cl)(2) (3). The binuclear compl ex [{TpNb(O)(Cl)}(2)(mu-O)] (4) was prepared by the controlled hydrol ysis of 1 or 2. Finally, complex 3 reacts with (Me3Si)(2)NMe or LiN(Si Me3)(2). Et2O to give TpNb(O)(HNSiMe3)(2) (5) as the only isolated ni obium product. Compounds 4 and 5 were characterized by X-ray diffracti on.