Variable Coordination Modes of NO2- in a Series of Ag(I) Complexes Containing Triorgano-phosphines, -arsines and –stibines. Syntheses, Spectroscopic Characterization (IR, 1H and 13C NMR, Electrospray Ionization Mass) and Structures of (R3E)xAgNO2 adducts (E = P, As, Sb, x = 1-3)

Adducts of triorganophosphine, triphenylarsine, and triphenylstibine with silver(l) nitrite have been synthesized and characterized both in solution (H-1, P-31 NMR) and in the solid state (IR, single-crystal X-ray structure analysis). In addition aggregates of AgNO2 and ER3 (E = P, As, Sb) have been identified in solution by electrospray ionization mass spectrometry (ESI-MS). The topology of the structures in the solid state was found to depend on the nature of ER3 and on the stoichiometric ratio AgNO2:ER3. The adducts AgNO2:EPh3 (1:1) (E = P or Sb) are one-dimensional polymers, the role of NO2- being to bridge successive metal atoms by coordination of the two oxygens to one silver atom and the nitrogen lone pair to a successive Ag. The adduct AgNO2:P(o-tolyl)(3) (1:1) is mononuclear, due to steric hindrance of the phosphine, the nitrite being O,O'-bidentate, a rare example of a quasi-linear P-Ag-X array, AgNO2:P(p-F-C6H4)(3) (1:1) is a dimer, the nitrite being coordinated through both oxygens, the first unidentate, the second bridging bidentate. P(o-tolyl)(3) and Pcy(3) form 1:2 adducts, also mononuclear, the nitrite still an O,O'-chelate. In contrast, the adduct AgNO2:AsPh3 (1:2) is a centrosymmetric dimer, essentially an aggregate of a pair of [Ag(O2N)(AsPh3)(2)] arrays with one nitrite oxygen being the bridging atom, The adducts AgNO2:EPh3 (1:3) (E = As, Sb) are mononuclear, the nitrite behaving as a consistently strong O,O'-chelate. The E = As adduct is a triclinic solvated form, whereas the unsolvated E = Sb species is monoclinic, ESI-MS spectra of acetonitrile solutions of these complexes show the existence of [Ag(ER3)](+), [Ag(CH3CN)](+), [Ag(CH3CN)(2)](+), [AgCl2](-), [Ag(NO2)(2)](-), [Ag(ER3)(CH3CN)](+), and [Ag(ER3)(2)](+) as well as higher aggregates [Ag-2(NO2)(ER3)(2)](+), [Ag-2(NO2)(3)](-) and [Ag2Cl2(NO2)](-), which are less prevalent.