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

Abstract

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) Å, b = 10.573(1) Å, c = 7.415(1) Å, 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 Å. Intermolecular Pt–H interaction between the μ-NH₂ hydrogens and the platinum(II) centers of the adjacent molecule are observed.