Bimetallic Organoplatinum(II)-Ag(I) Cluster Cations with Ag-Pt Interactions Unsupported by Conventional Bridging Ligands

The organoplatinum complex of a primary amine and AgClO4 aggregate in methanol to oligonuclear mixed-metal species. A perchlorate salt 3 with the empirical formula C96H146Ag7Cl13N12O62Pt6 could be isolated and structurally characterized with the help of X-ray diffraction at the DESY synchrotron. The product contains both a penta- and a tetra-nuclear complex cation in which Ag(I) and Pt(II) alternate, held together without any conventional bridge. The cationic species feature short Ag...Pt distances between 2.7 and 2.9 angstrom and contacts longer than 2.4 angstrom between Ag and C atoms in aromatic rings. In addition to the interactions with Ag(I) cations, Pt(II) is in a square-planar arrangement, coordinated by a chelating and a terminal amine and an aqua ligand. The central Ag(I) in the pentanuclear cation is located on a twofold crystallographic axis and not involved in any obvious coordinative bond; it exclusively shows short contacts to the neighboring Pt(II) ions and the Pt-bonded, formally anionic carbon atoms of the cyclometallated organic ligand. Powder diffraction shows that 3 melts and re-solidifies without decomposition.

Automated summary

A mixed-metal complex containing platinum and silver has been characterized using X-ray diffraction, revealing alternating arrangements of silver and platinum without conventional bridging. Short interactions between silver and platinum, as well as contact between silver and carbon atoms in aromatic rings, have been observed.