Transition-Metal-Induced Rearrangement of [(PhSn)4 S6 ] Towards Ternary CuI /Sn/S or CuII /Sn/S Clusters.

Direct access of ternary copper-tin sulfide clusters by reactions of a binary organotin sulfide cluster, [(PhSn)4 S6 ] (A), with transition metal complexes was achieved for the first time without extra addition of further chalcogenide sources. This indicates that an in situ rearrangement of the inorganic core takes place even without initial formation of anionic fragments. The use of [Cu(PPh3 )3 Cl] or [Cu(PPh3 )2 Cl2 ] as reactants yielded the ternary clusters [(CuPPh3 )4 (PhSn)18 Cu6 S31 Cl2 ] (1) and [{Cu(PPh3 )2 }2 (PhSn)3 (SnCl)S8 ] (2), respectively. Whereas 1 represents the largest neutral Cu/Sn/S cluster known to date, compound 2, which is the first example of a ternary Cu/Sn/E (E=S, Se) cluster containing copper in the +II oxidation state, may be viewed as a very early stage of cluster formation. Apparently, the presence of CuII inhibits effective cluster growth, which rationalizes the lack of such species so far. The two ternary clusters exhibit very similar optical absorption energies despite their markedly different cluster sizes. According to time-dependent DFT calculations, this is due to different characters of the electronic excitation in the triplet compound 2, as compared to the excitation of the closed shell cluster 1, which serve to compensate for the different extensions of the clusters.