Syntheses, structures and vibrational spectroscopy of some 1:1 and 1:2 adducts of silver(I) oxyanion salts with 2,2'-bis(pyridine) chelates

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for a number of adducts of 1:1 stoichiometry of silver(I) oxyanion salts (perchlorate, nitrate, trifluoroacetate ('tfa') (increasing basicity)) with 2,2'-bis(pyridine) ligands (2,2'-bipyridyl, 'bpy'; 2,2'-biquinolyl, 'bq'; 2,2'-dipyridylketone, 'dpk'; 2,9-dimethylphenanthroline, 'dmp'). The adducts take two forms: (a) neutral mononuclear molecules, in which the 2,2'-bis(pyridine) ligand behaves as a chelate, with the silver coordination number dependent on the denticity of the anion; these are Agtfa:bpy (1:1) and AgClO4:bq (1:1) (and various (ionic) acetonitrile or pyridine solvates AgClO4:bq/dmp:MeCN/py (1:1:1), in which the solvent molecules are coordinated); and (b) one-dimensional polymers. The latter are diverse: in AgClO4:bpy, dpk (1:1), the anion is discrete, the polymer made up of an array of two-coordinate silver atoms linked by bpy ligands twisted about their central connecting element. In AgNO3:bpy, bq (1:1), the bpy ligands are chelating with the oxyanions bridging, cf. previously reported AgNO3:dpk (1:1), in which the nitrate chelates the metal, with the dpk bridging, chelating N,O to one silver, while the other nitrogen bridges to the next. With Agtfa, a novel binuclear adduct has been isolated in conjunction with the hydrated ligand, Agtfa:dpk:(dpk (.) H2O) (1:1:2). The far-IR spectra of several of these complexes show bands that can be assigned to the v(AgN) modes, the positions of these bands correlating well with the relative Ag-N bond lengths. Syntheses and single-crystal X-ray structural characterizations are also reported for various adducts of silver(l) perchlorate, nitrate and trifluoromethanesulfonate with bpy, bq,'phen'(= 1,10-phenanthroline), and 'dmp', of stoichiometry AgX:L (1:2). In each case the complex is ionic [AgL2]X; the silver atom is four-coordinate, but diverse and remarkable variations in stereochemistries associated with changes in the interligand N-Ag-N angles, presumably influenced by the different packing arrangements, are observed. (c) 2005 Elsevier B.V. All rights reserved.