Diborane(4) compounds with bidentate diamino groups

The reaction between B-2(NMe2)(4) and 1,2-(NH2)(2)-4-(BuC6H3)-C-t affords the diborane(4) compound 1,2-B-2{1,2-(NH)(2)-4-(BuC6H3)-C-t}(2) as the exclusive product whilst the reaction between rac-1,2-(NH2)(2)C6H10 and B-2(NMe2)(4) also affords only the 1,2-isomer, i.e. 1,2-B-2{1,2-(NH)(2)C6H10}(2), which is shown to be the more stable isomer by computational methods. The previously reported compounds 1,1-B-2{1,2-(NH)(2)C6H4}(2) and 1,2-B-2{1,2-(NH)(2)C6H4}(2) both react with four equivalents of (BuLi)-Li-n to give what are presumed to be tetra-anions which react further with MeI, SnClMe3 or SnClPh3 to give the tetrasubstituted products 1,1-B-2{1,2-(NMe)(2)C6H4}(2), 1,1-B-2{1,2-(NSnMe3)(2)C6H4}(2) and 1,2-B-2{1,2-(NSnPh3)(2)C6H4}(2) respectively. The compound 1,1-B2{1,8-(NH)(2)C10H6}(2) has also been prepared from the reaction between B-2(NMe2)(4) and 1,8-diaminonaphthalene. Lithiation and subsequent reaction with SnClMe3, SnCl2Me2 or SnCl2Ph2 affords 1,1-B-2{1,8-(NSnMe3)(2)C10H6}(2), 1,1-B-2{1,8-(N-2-mu-SnMe2)C10H6}(2) and 1,1-B-2{1,8-(N-2-mu-SnPh2)C10H6}(2) respectively. All new compounds have been characterised by X-ray crystallography.