Syntheses, structures and spectroscopy of uni- and bi-dentate nitrogen base complexes of silver(i) trifluoromethanesulfonate?

Dalton Transactions Pub Date: 2009-11-17 DOI: 10.1039/B913173F

Abstract

In extension of recent synthetic and crystallographic studies of adducts of silver(I) oxyanion salts with uni- and bi-dentate nitrogen-donor ligands, AgX : L (1 : n), a parallel series of complexes formed with silver(I) trifluoromethanesulfonate (‘tfs’, ‘triflate’) has been similarly defined, showing rather more divergence from tendencies established with the previous ClO4, NO3, F3CCO2 core arrays than might be expected from basicity arguments. Thus, while silver triflate crystallised from neat base forms 1 : 2 mononuclear adducts with 2,4,6-trimethylpyridine and quinoline which comprise essentially linear two-coordinate [LAgL]+ cations, perturbed by approaches of the anions, 1 : 2 adducts obtained similarly from pyridine and 2-methylpyridine are [L2Ag(μ-tfs)2AgL2] dimers, with central four- and eight-membered rings arising from μ-OSO2CF3 and extended μ-(O,O′SOCF3) anion bridging modes, respectively. With piperidine, a single-stranded polymer reminiscent of the arrays [(pip)2AgX]∞|∞, X = Cl, NCS, is formed, the triflate bridging through two of its oxygen atoms, rather than via a single atom bridge. With 2- and 4-cyanopyridine, the former a 1 : 1 adduct (being an acetonitrile solvate (MeCN coordinated)), and the latter 1 : 2, both are more complex structures in which the nitrile functionalities now coordinate weakly. The 1 : 2 adduct with 2-acetylpyridine parallels its perchlorate analogue, the ligands being bidentate in a mononuclear complex [L2AgOSO2CF3], while adducts of 2,9-dimethylphenanthroline and 2,2′-biquinolyl, both acetonitrile monosolvates, take the form [LAg(NCMe)]tfs. Agtfs : dpk (8 : 8)∞|∞·EtOH (‘dpk’ = bis(2-pyridyl)ketone) is a complex polymer. The nature of the interactions is explored by way of spectroscopy (IR, NMR and ESI MS) and a density functional theory approach.

Graphical abstract: Syntheses, structures and spectroscopy of uni- and bi-dentate nitrogen base complexes of silver(i) trifluoromethanesulfonate
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