Synthesis, structure, and spectroelectrochemical investigation of novel ternary Co/S(Se)/Sn clusters derived from binary cobalt stannanediyl complexes

The synthesis and structure of heterobimetalic Co/Sn complexes [(eta(5)-Cp- R)Co-Sn(CH(SiMe,)(2))(2)] (Cp-R = C5Me5 2; C5EtMe4 3) are described. Insert ion reactions of sulfur and selenium into the unbridged heteronuclear Co-Sn bonds of 1, 2, and 3 (R = H-5 1, Me-5 2, EtMe4 3) have been studied. Depen ding on the stoichiometry of the chalcogen element used, novel ternary Sn-c halcogen-Co clusters (8, 9, 15, and 16) can be synthesized, and their molec ular structures, which represent rare examples of crystallographically char acterized cases of ternary transition metal/chalcogen/tin complexes, have b een determined. Electrochemistry shows that complexes 8 and 9 are able to s upport reversibly either the removal or addition of one electron. Insertion of a further (Cp)Co-E (E=chalcogen) fragment significantly affects the ele ctron distribution and causes complexes 9 and 16 to undergo two consecutive one-electron oxidations. The EPR spectra of the respective monocations hav e been recorded. In all cases, the unpaired electron strongly interacts wit h the cobalt nucleus(i), thus testifying that the main contribution to the relevant HOMO orbitals comes from the cobalt atom(s).