Pt2II and Pt2III dimers containing a Pt2(2,2′-bipyridine)2(μ-N,N-dimethyl­guanidinato)2 unit

The syntheses and crystal structures of the title Pt2II and Pt2III dimers doubly bridged with N,N-dimethyl­guanidinate ligands, namely bis­(μ-N,N-dimethyl­guanidinato)bis­[(2,2′-bipyridine)platinum(II)](Pt—Pt) bis­(hexa­fluoro­phosphate) acetonitrile disolvate, [Pt2II(C3H8N3)2(C10H8N2)2](PF6)2·2CH3CN, (I), and guanidinium bis­(μ-N,N-dimethyl­guanidinato)bis­[(2,2′-bipyridine)sulfatoplatinum(III)](Pt—Pt) bis­(hexa­fluoro­phosphate) nitrate hexa­hydrate, (C3H10N3)[PtIII2(C3H8N3)2(SO4)2(C10H8N2)2]NO3·6H2O, (II), are reported. The oxidation of the Pt2II dimer into the Pt2III dimer results in a marked shortening of the Pt—Pt distance from 2.8512 (6) to 2.5656 (4) A. The change is mainly compensated for by the change in the dihedral angle between the two Pt coordination planes upon oxidation, from 21.9 (2) to 16.9 (3)°. We attribute the relatively strong one-dimensional stack of dimers achieved in the Pt2II compound in part to the strong PtII⋯C(bpy) associations (bpy is 2,2′-bipyridine) in the crystal structure [Pt⋯C = 3.416 (10) and 3.361 (12) A].