Interstitial Bismuth Atoms in Icosahedral Rhodium Cages: Syntheses, Characterizations, and Molecular Structures of the [Bi@Rh12(CO)27]3-, [(Bi@Rh12(CO)26)2Bi]5-, [Bi@Rh14(CO)27Bi2]3-, and [Bi@Rh17(CO)33Bi2]4- Carbonyl Clusters.

The reaction of [Rh7(CO)16]3- with BiCl3 under N2 and at room temperature results in the formation of the new heterometallic [Bi@Rh12(CO)27]3- cluster in high yields. Further controlled addition of BiCl3 leads first to the formation of the dimeric [(Bi@Rh12(CO)26)2Bi]5- and the closo-[Bi@Rh14(CO)27Bi2]3- species in low yields, and finally, to the [Bi@Rh17(CO)33Bi2]4- cluster. All clusters were spectroscopically characterized by IR and electrospray ionization mass spectrometry, and their molecular structures were fully determined by X-ray diffraction studies. Notably, they represent the first examples of Bi atoms interstitially lodged in metallic cages that, in this specific case, are all based on an icosahedral geometry. Moreover, [Bi@Rh14(CO)27Bi2]3- forms an exceptional network of infinite zigzag chains in the solid state, thanks to intermolecular Bi-Bi distances.