Pt···Pt vs Pt···S contacts between Pt-containing heterobimetallic lantern complexes.

A trio of Pt-based heterobimetallic lantern complexes of the form [(py)PtM(SAc)4(py)] (M = Co, 1; Ni, 2; Zn, 3) with unusual octahedral coordination of Pt(II) was prepared from a reaction of [PtM(SAc)4] with excess pyridine. These dipyridine lantern complexes could be converted to monopyridine derivatives with gentle heat to give the series [PtM(SAc)4(py)] (M = Co, 4; Ni, 5; Zn, 6). An additional family of the form [PtM(SAc)4(pyNH2)] (M = Co, 7; Ni, 8; Zn, 9) was synthesized from reaction of [PtM(SAc)4(OH2)] or [PtM(SAc)4] with 4-aminopyridine. Dimethylsulfoxide and N,N-dimethylformamide were also determined to react with [PtM(SAc)4] (M = Co, Ni), respectively, to give PtCo(SAc)4(DMSO), 10, and PtNi(SAc)4(DMF), 11. Structural and magnetic data for these compounds and those for two other previously published families, [PtM(tba)4(OH2)] and [PtM(SAc)4(L)], L = OH2, pyNO2, are used to divide the structures among three distinct categories based on Pt···Pt and Pt···S distances. In general, the weaker donors H2O and pyNO2 seem to favor metallophilicity and antiferromagnetic coupling between 3d metal centers. When Pt···S interactions are favored over Pt···Pt ones, no coupling is observed and the pKa of the pyridine donor correlates with the interlantern S···S distance. UV-vis-NIR electronic and (1)H NMR spectra provide complementary characterization as well.