Spectroscopic and structural studies on adducts of silver(I) cyanide with ER3 ligands (E = P, As or Sb)

The adducts AgCN:EPh3 (E = P, As or Sb) (1:2) and AgCN:PPh3 (1 : 1) have been characterized by room temperature single crystal structure determination and low frequency vibrational spectroscopy. The compounds AgCN:EPh3 (E = P or As) (1 :2) [as pyridine (py) monosolvates] are isomorphous and of the form [(Ph3E)(3)Ag(CN)Ag(EPh3)(3)][Ag(CN)(2)], an agua-2-methylpyridine solvate and an acetonitrile solvate also being structurally characterized for the E = P adduct. For E = Sb the complex is a simple single stranded polymer ... Ag(SbPh3)(2)(CN)Ag(SbPh3)(2)(CN)... as is AgCN:PPh3 (1:1), ... Ag(PPh3)(2)(CN)Ag(CN)Ag(PPh3)(2).... An adduct of the form AgCN:PR, (1 : 1) is also obtained for tris(2,4,6-trimethoxyphenyl)phosphine (tmpp) as a pyridine hemisolvate, now ionic but with the pyridine loosely co-ordinated to the anion, [Ag(tmmp)(2)][Ag(CN)(2)(py)]. By contrast, in the AgCN:P(o-tol)(3) (tol = o-tolyl): py(1:0.5:0.5) adduct, Ag{P(o-tol)(3)}(py) moieties are linked in a single-stranded polymer by NCAgCN units, ... Ag[P(o-tol)(3)](py)(NCAgCN).... The structural characterization of [Ag(PPh3)(3)(CN)] has also been made. The far-infrared spectra of AgCN . 2AgNO(3), [Ag(SbPh3)(2)(CN)] and [Ag(SbPh3)(3)(CN)] show v(AgX) bands (X = CN) at 435, 358 and 310 cm(-1). The relationship between the v(AgX) wavenumbers and the Ag-X bond lengths r(AgX) for the case of terminally bound CN groups has been established, and this has the same form as that found previously for a range of AgX complexes (X = Cl, Br or I) with phosphine and arsine ligands. The v(AgX) wavenumbers for the CN-bridged compounds AgCN . 2AgNO(3) and [Ag(SbPh3)(2)(CN)] are about 50 cm(-1) higher than those for compounds with terminal Ag-CN bonds of similar bond length. Similar behaviour is observed for the bridging CN groups in the cations of the ionic 1 :2 complexes [{Ag(EPh3)(3)}(2)CN](+)[Ag(CN)(2)](-). 3py(E = P or As), where the v(AgX) wavenumbers (301, 354 cm(-1) respectively) are about 80 cm(-1) higher than those predicted for terminal bonding.