Synthesis, structure and spectroscopic properties of bis(triphenylphosphane)iminium (chlorido)(cyanido)argentates(I)

Abstract

Four new compounds containing the (chlorido)(2-x)(cyanido)xargentate(I) anion (x = 2, 1.63, 1 and 0.5) are reported. Their solid-state structures with the monocation PPN, bis(triphenylphosphane)iminium, are described; in a few cases the products also contain solvent molecules. The compounds have the formula (PPN)2[Ag2Cl3(CN)], (PPN)[Ag(CN)Cl](CH2Cl2) and (PPN)[Ag(CN)1.63Cl0.37](hexane)0.5 and (PPN)[Ag(CN)2](CH2Cl2). Apart from the molecular structures and the synthetic process, also the solid-state luminescence has been studied. In the case of (PPN)2[Ag2Cl3(CN)], the silver ions are pseudo-trigonally coordinated, with 2 chloride bridges between the Ag+ ions. The terminal Cl- and terminal CN- ligands are disordered over two positions, but only a single 13C NMR signal is observed for the cyanide ligands of this compound. The compound (PPN)[Ag(CN)2] serves as a reference compound and contains the linear [Ag(CN)2] unit. The compound with CN/Cl = 1.0 shows disorder of the [AgCl(CN)] unit, and also in the compounds with other CN/Cl ratios, disorder among the Cl- and CN- ligands is seen. The Ag+ ion is linearly coordinated by two ligands in these two cases, and for cyanides normal Ag-C bond lengths are observed in both cases (1.97-1.99 Å). The [Ag(CN)2] anion is linear and uneventful. The PPN cation has normal bond lengths in all 4 compounds and no short contacts with other atoms in the lattice are observed. The luminescence properties of the new compounds were explored as solid powders. Only one of the compounds (compound 2, with x = 1) shows luminescence under excitation. The other three compounds do not show emission when irradiated at 320 nm, 350 nm or 380 nm.