Comparison of {O,S}- vs {N,S}-donor ligands in PtNi heterobimetallic lantern complexes

A pair of thiocarboxylate lantern complexes, [PtNi(SAc)(4)(L)] (L = pyCN (2), HpipCN (3)) and three new {N,S} chelated mercaptopyridine lantern complexes [PtNi(mpyS)(4)(L)] (L = H2O (4), MeCN (5), pyCN (6)) have been synthesized and characterized by SCXRD, H-1 NMR and UV-vis spectroscopies, as well as elemental analysis and RT solution magnetization. A detailed structural comparison was made of the {O,S} and {N, S} donor systems that demonstrates that the stronger field mercaptopyridine ligand decreases the Pt (donor) - M (acceptor) character within the lantern, reducing the Pt(II) Lewis acidity and therefore preventing the formation of intermolecular interactions in Ni(II) complexes 4-6. An unexpected pentameric species [Pt(PtNi(mpyS)(4)(Cl))(2)] (7) was also formed, albeit in very low quantities, that showed the importance of the choice of Ni(II) starting material. Additionally, the development of an improved air- and water-stable synthesis for the formation of the homo-leptic, Pt-2(PYS)(4)], is reported.