Solution and solid-state complexes of the potentially tetradentate pyridyl-thiazole ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine with CoII, NiII, CuII, CdII, HgII, CuI and AgI

Reaction of the potentially tetradentate N-donor ligand 6,6'-bis(4-methylthiazol-2-yl)-2,2'-bipyridine (L-1) with the transition metal dications Co-II, Ni-II, Cu-II, Cd-II, and Hg-II results in the formation of mononuclear [M(L-1)](2+) complexes, in which a planar ligand coordinates to the metals via all four N-donors. In contrast, reaction of L-1 with Cu-1 and Ag-1 monocations, affords dinuclear double stranded helicate species [M-2(L-1)(2)](2+) (where M = Cu-1 or Ag-1), in which partitioning of the ligand into two bis-bidentate pyridyl-thiazole chelating units allows each ligand to bridge both metal centres. X-Ray crystallography, electrospray mass spectroscopy and NMR spectroscopy reveal that the complexes [M-n(L-1)(m)](2+) (where n = 1, m = 1 and z = 2, when M = Co-II, Ni-II, Cu-II, Cd-II and Hg-II; n = 2, m = 2 and z = 2, when M = Cu-1), retain their solid-state structures in solution. Conversely, whilst H-1 NMR studies suggest that combination of equimolar amounts of Ag(X) (where X = OTf-, BF4- or NO3-) and L-1 (in either nitromethane or acetonitrile) results in the formation of a helicate in solution, in the solid-state, an anion-templating effect gives rise to either mononuclear or dinuclear helicate structures [Ag-n(L-1)(n)][X](n) (where n = 2 when X = OTf-; n = 1 when X = BF4- or NO3-). (c) 2005 Elsevier B.V. All rights reserved.