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

The tetracyanoborate anion [B(CN) 4 ] − was used as a building block for the synthesis of polynuclear chromium carbonyls, such as the tetraanionic heterocubane cage [{Cr(CO) 3 (B(CN) 4 )} 4 ] 4− .