Platinum carbonyl clusters stabilized by Sn(II)-based fragments: Syntheses and structures of [Pt6(CO)6(SnCl2)2(SnCl3)4]4-, [Pt9(CO)8(SnCl2)3(SnCl3)2(Cl2SnOCOSnCl2)]4- and [Pt10(CO)14{Cl2Sn(OH)SnCl2}2]2-

The reaction of [Pt15(CO)30]2- with increasing amounts of SnCl2 affords [Pt8(CO)10(SnCl2)4]2- (2), [Pt10(CO)14{Cl2Sn(OH)SnCl2}2]2- (5), [Pt6(CO)6(SnCl2)2(SnCl3)4]4- (3), [Pt9(CO)8(SnCl2)3(SnCl3)2(Cl2SnOCOSnCl2)]4- (4) and [Pt5(CO)5{Cl2Sn(OR)SnCl2}3]3- (R = H, Me, Et, and iPr) (1-R). 1-R and 2 have been previously described, whereas 3-5 are herein reported for the first time. The species 1-3 are the main products of the reaction under different experimental conditions, whereas 4 and 5 are by-products of the synthesis of 3 and 2, respectively. From a structural point of view, the clusters 1-5 all show a perfect segregation of the two metals, which are composed of a low valent Pt core decorated on the surface by Sn(ii) fragments such as SnCl2, [SnCl3]-, [Cl2Sn(OH)SnCl2]- and [Cl2SnOCOSnCl2]2-. These fragments behave as two electron donor ligands via each Sn-atom (and also the C-atom in the case of [Cl2SnOCOSnCl2]2-). The [Cl2SnOCOSnCl2]2- ligand is rather unique and may be viewed as a bis-stannyl-carboxylate, a carbon dioxide μ3:k3-C,O,O′-CO2 or a carbonite ion [CO2]2- stabilized by coordination to metal atoms. Compounds 1-5 have been fully characterised via IR spectroscopy, X-ray crystallography and DFT calculations.