The tetracyanoborate anion as a building block for the heterocubane cluster cage [Cr4{B(CN)4}4]4−

The tetracyanoborate anion [B(CN)4]− (TCB) was utilized as a building block for the synthesis of polynuclear chromium carbonyl compounds upon photolytic reaction with [Cr(CO)6]. Up to four κN-coordinated cyano groups of TCB can be involved in binding to chromium, giving mixtures of [B(CN)4−x{CN-Cr(CO)5}x]− (x = 1-4; 1-4) and [{Cr(CO)4(B(CN)4)}2]2− (5). The reaction of [B(CN)4]− with fac-[Cr(CO)3(MeCN)3] led to isolation of salts of the tetraanionic heterocubane cage [{Cr(CO)3(B(CN)4)}4]4−