Dimeric polybismuth heteroanion of [Rh@Bi 10 (RhCO) 5 ] 2- constructed using Bi 10 -bowl and square pyramidal Rh@(Rh-CO) 5 .

Redox reaction of the monovalent Rh 2 (CO) 4 Cl 2 and Bi n n - ( n = 2, 3) from K 5 Bi 4 in ethylenediamine ( en ) solution produced the decabismuthide-hexarhodium dianion [Rh@Bi 10 (RhCO) 5 ] 2- (1a) wherein a novel Bi 10 -bowl was constructed from oxidized 2Bi 3 /2Bi 2 open triangles/dimers, which was stabilized by strong bonding to a reduced Rh@(RhCO) 5 square pyramid. Two 1a dianons are held together by weak interactions (van der Waals forces and spatial resistance) to form a dimer [Rh@Bi 10 (RhCO) 5 ] 2 4- (1). The structure and bonding of the novel polybismuthide heteroanion 1 are discussed.