Pt₂^II and Pt₂^III dimers containing a Pt₂(2,2′-bipyridine)₂(μ-N,N-dimethyl­guanidinato)₂ unit

The syntheses and crystal structures of the title Pt₂^II and Pt₂^III 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, [Pt₂^II(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)[Pt^III₂(C₃H₈N₃)₂(SO₄)₂(C₁₀H₈N₂)₂]NO₃·6H₂O, (II), are reported. The oxidation of the Pt₂^II dimer into the Pt₂^III dimer results in a marked shortening of the Pt—Pt distance from 2.8512 (6) to 2.5656 (4) Å. 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 Pt₂^II compound in part to the strong Pt^II...C(bpy) associations (bpy is 2,2′-bipyridine) in the crystal structure [Pt...C = 3.416 (10) and 3.361 (12) Å].