Carbosilane dendrimers containing peripheral cyclopentadienyl niobium- and tantalum-imido complexes

Abstract

Anilines G n-{(C 6H 4)N(SiMe 3) 2} m , based on simple or dendritic carbosilanes, have been used to synthesized (imido)tantalum compounds G n-{(C 6H 4)NTaCl 2Cp ∗} m ( 1, n = 0, m = 1; 2, n = 1, m = 4; Cp ∗ = η 5-C 5Me 5), by the reaction with [TaCl 4Cp ∗] and elimination of SiMe 3Cl. (Imido)niobocene compounds of general formula G n - { ( C 6 H 4 ) NNbCl Cp 2 ′ } m ( 3– 5; n = 0, 1, 2; m = 1, 4, 8, respectively) have been readily prepared from their corresponding half-sandwich complexes G n-{(C 6H 4)NNbCl 2Cp′} m by the reaction with m equiv. of LiCp′ (Cp′ = η 5-C 5H 4SiMe 3). Compounds 1– 5 are all found to be exceedingly moisture sensitive, and in the case of the (imido)niobocene materials the hydrolytic reaction selectively leads to the formation of [ NbCl ( O ) Cp 2 ′ ] ( 6). The molecular structure of 6 has been determined by X-ray diffraction studies.