Sn-centred icosahedral Rh carbonyl clusters: synthesis and structural characterization and 13C-{103Rh} HMQC NMR studies

The reaction of Rh(7)(CO)(16)](3-) with SnCl(2).2H(2)O in a 1 : 1 molar ratio under N(2) results in the formation of the new heterometallic cluster, Rh(12)Sn(CO)(27)](4-), in very high yield (ca. 86%). Further controlled additions of SnCl(2).2H(2)O, or solutions of HCl, or RhCl(COD)](2), give Rh(12)(micro-Cl)(2)Sn(CO)(23)](4-). Similarly, addition of HBr to Rh(12)Sn(CO)(27)](4-) gives the related cluster Rh(12)(micro-Br)(2)Sn(CO)(23)](4-). Notably, if the addition of SnCl(2).2H(2)O to Rh(12)Sn(CO)(27)](4-) is carried out under a CO atmosphere, the reaction takes a different course and leads to the formation of the new cluster, Rh(12)Sn(micro(3)-RhCl)(CO)(27)](4-). All the above clusters have been shown by single-crystal X-ray diffraction studies to have a metal framework based on an icosahedron, which is centred by the unique Sn atom. Their chemical reactivity and (13)C-{(103)Rh} HMQC NMR spectroscopic characterization are also reported.