Synthesis and Reactivity of 1,2-Bis(chlorodimethylgermyl)carborane and 1,2-Bis(bromodimethylstannyl)carborane

The 1,2-bis(chlorogermyl)- (1) and 1,2-bis(bromostannyl)carborane (2) have been prepared by the reaction of dilithio-o-carborane with Me2GeCl2 and Me2SnBr2, respectively. Compounds 1 and 2 are found to be good precursors for the synthesis of a variety of cyclization compounds. The Wurtz-type coupling reaction of 1 and 2 using sodium metal afforded the four-membered digerma compound 3 and five-membered tristanna compound 4, respectively. The salt elimination reactions of 1 and 2 using Li2NtBu and Li2PC6H5 afforded the cyclic products (5, M = Ge, E = NtBu; 6, M = Sn, E = NtBu; 7, M = Ge, E = PC6H5; 8, M = Sn, E = PC6H5). The 1,2-bis(dimethylgermyl)carborane 9 and 1,2-bis(dimethylstannyl)carborane 10 were prepared by the reaction of 1 and 2 with sodium cyanoborohydride. The reactions of 9 and 10 with Pd(PPh3)4 afforded the bis(germyl)palladium 12 and bis(stannyl)palladium 13 complexes, respectively.