Syntheses, structures and vibrational spectroscopy of some unusual silver(I) (pseudo-) halide/unidentate nitrogen base polymers

The meagre (structurally defined) array of 1:2 silver(I) (pseudo-)halide:unidentate nitrogen base adducts is augmented by the single-crystal X-ray structural characterization of the 1:2 silver(I) thiocyanate:piperidine ('pip') adduct. It is of the one-dimensional,castellated polymer' type previously recorded for the chloride: Ag-...(pip)(2)(mu-SCN)Ag(pip)(2)(...) a single bridging atom (S) linking successive silver atoms. By contrast, in its copper(l) counterpart, also a one-dimensional polymer, the thiocyanate bridges as end-bound SN-ambidentate: (CuSCNCuSCN...)-Cu-... A study of the 1:1 silver(I) bromide: quinoline ('quin') adduct is recorded, as the 0.25 quin solvate, isomorphous with its previous reported 'saddle polymer' chloride counterpart.Recrystaflization of 1:1 silver(I) iodide: tris(2,4,6-trimethoxyphenyl)phosphine ('tmpp') mixtures from py and quinoline ('quin')/acetonitrile solutions has yielded crystalline materials which have also been characterized by X-ray studies. In both cases the products are salts, the cation in each being the linearly coordinated silver(I) species [Ag(tmpp)(2)](+), while the anions are, respectively, the discrete [Ag5I7(py)(2)](2-) species, based on the already known but unsolvated [Cu5I7](2-) discrete, and the [Ag5I7]((infinity vertical bar infinity))(2-) polymeric, arrays, and polymeric [Ag5I6(quin)]((infinity vertical bar infinity))(-), The detailed stereochemistry of the [Ag(tmpp)(2)](+) cation is a remarkably constant feature of all structures, as is its tendency to close-pack in sheets normal to their P-Ag-P axes.The far-IR spectra of the above species and of several related complexes have been recorded and assigned. The vibrational modes of the single stranded polymeric AgX chains in [XAg(pip)2]((infinity vertical bar infinity)) (X = Cl, SCN) are discussed, and the assignments v(AgX) = 155,190 cm(-1) (X = Cl) and 208 cm(-1) (X = SCN) are made. The v(AgX) and v(AgN) modes in the cubane tetramers [XAg(pip)](4) (X = Br, I) are assigned and discussed in relation to the assignments for the polymeric AgX:pip (1:2) complexes, and those for the polymeric [XAg(quin)]((infinity vertical bar infinity)) (X = Cl, Br) compounds. The far-IR spectra of [Ag(tmpp)(2)](2)[Ag5I7(py)(2)] and its corresponding 2-methylpyridine complex show a single strong band at about 420 cm(-1) which is assigned to the coordinated tmpp ligand in [Ag(tmpp)(2)](+), and a partially resolved triplet at about 90, 110 and 140 cm(-1) which is assigned to the v(AgI) modes of the [Ag5I7L2](2-) anion. An analysis of this pattern is given using a model which has been used previously to account for unexpectedly simple v(CuI) spectra for oligomeric iodocuprate(I) species. (c) 2005 Elsevier B.V. All rights reserved.