Crystal structure of di-μ-amido-bis[diammineplatinum(II)] nitrate

Di-μ-amido-bis[diammineplatinum(II)] nitrate (1) was synthesized as a byproduct during preparation of tetraammineplatinum(II) nitrate. One possible pathway to produce 1 is that [(H3N)2Pt(μ- OH)2Pt(NH3)2](NO3)2, a well-known complex forming on treatment of cis-Pt(NH3)2I2 with AgNO3, reacts with aqueous ammonia. The other possible pathway involves deprotonation of [Pt(NH3)4](NO3)2 to form monomeric Pt(NH3)3(NH2)NO3 followed by elimination of NH3. Crystals of 1 (from water) are monoclinic (C2/c) with a = 16.834(2) A, b = 10.573(1) A, c = 7.415(1) A, β = 114.846(1)°, and Z = 4. The cationic portion consists of two symmetrical square-planar Pt centers with the inversion center at the midpoint of the Pt(1)∙∙∙Pt(1A) vector. The Pt(II) ion is coordinated by four N atoms from two ammonia molecules and two bridging amido groups affording a slightly distorted square. The molecules are stacked in such a way that the planes of coordination squares turn out to be parallel to each other with a distance of 3.501 A. Intermolecular Pt–H interaction between the μ-NH2 hydrogens and the platinum(II) centers of the adjacent molecule are observed.