Aggregation of Polybismuthide Anions in a Single Compound Using +Rh-CO Units: Heterometallic Cluster Ions [Rh@Bi10(RhCO)6]3- and [Rh@Bi9(RhCO)5]3.

In the presence of the roughly flat sequestering agent, [K(18-crown-6)]+, the reaction of Rh2(CO)4Cl2 with K5Bi4 in ethylenediamine (en) solution at room temperature yielded the heterometallic cluster anion [Rh@Bi10(RhCO)6]3- (1), in which two hitherto unknown Binm- building blocks (i.e., Bi6 crown and Bi4 pyramid) were stabilized by six +Rh-CO units. When the reaction was carried out at 60 °C using Rh(acac)(CO)2 (acac = acetylacetonate) as the source of +Rh-CO units, one obtained the anion [Rh@Bi9(RhCO)5]3- (2) in which two different Binn- units (n = 2, 3) and two weakly bonded Bi atoms were stabilized by five +Rh-CO units. The structures and bonding of the novel heterometallic cluster anions 1 and 2 were discussed.