A series of bimetallic chain coordination polymers bearing [Ag(PPh3)2] chromophores: Synthesis, structure and luminescence

A series of three cyanide-bridged chain coordination compounds with the formulae [M(CN)2(PPh3)2Ag]n (M is Ag, Cu or Au) is presented. The compounds have been prepared by room temperature reactions of triphenylphosphane with the cyanide salts of silver(I), copper(I) and gold(I). The compounds are characterised with IR, elemental analyses, SEM-EDX and X-ray powder diffraction, and the molecular structures were elucidated by single crystal X-ray diffraction. The three compounds are best described as one-dimensional cyanide-bridged chain coordination polymers, where the tetrahedral AgI ions are coordinated by 2 triphenylphosphane ligands and 2 cyanides, forming a AgN2P2 chromophore. The linear Ag(I), Cu(I) and Au(I) centers are in two-coordinate geometry with C-bound cyanides. No aurophilic or argentophilic interactions are observed, but in the lattice only C-H…π and C-H…M hydrogen bonds are present. The solid-state luminescence properties of the three compounds are discussed and assigned, in agreement with DFT calculations, to MMLCT.