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

Anilines Gn -{(C6H4)N(SiMe3)2}m, based on simple or dendritic carbosilanes, have been used to synthesized (imido)tantalum compounds Gn -{(C6H4)NTaCl2Cp∗}m (1, n = 0, m = 1; 2, n = 1, m = 4; Cp∗ = η 5-C5Me5), by the reaction with [TaCl4Cp∗] and elimination of SiMe3Cl. (Imido)niobocene compounds of general formula View the MathML sourceGn-{(C6H4)NNbClCp2′}m (3–5; n = 0, 1, 2; m = 1, 4, 8, respectively) have been readily prepared from their corresponding half-sandwich complexes Gn -{(C6H4)NNbCl2Cp′}m by the reaction with m equiv. of LiCp′ (Cp′ = η 5-C5H4SiMe3). 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 View the MathML source[NbCl(O)Cp2′] (6). The molecular structure of 6 has been determined by X-ray diffraction studies.