Di-mu-pivalamidato-kappa4N:O;O:N-bis[(2,2'-bipyridine-kappa2N,N')(sulfato-kappaO)platinum(III)] tetrahydrate in a head-to-tail isomerism.

The title compound, [Pt(2)(III)(C(5)H(10)NO)(2)(SO(4))(2)(C(10)H(8)N(2))(2)].4H(2)O, is the first reported example of a complex in which an amidate-bridged Pt(bpy) dimer is stabilized in the oxidation level of Pt(III) (bpy is 2,2'-bipyridine). The asymmetric unit consists of one half of the formula unit with a twofold axis passing through the center of the dimer. The intradimer Pt(III)-Pt(III) bond distance [2.5664 (6) A] is comparable to those reported for alpha-pyridonate-bridged cis-diammineplatinum(III) dimers [2.5401 (5)-2.5468 (8) A; Hollis & Lippard (1983). Inorg. Chem. 22, 2605-2614], in spite of the close contact between the bpy planes within the dimeric unit. The axial Pt-O(sulfate) distance is 2.144 (7) A.