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Crystal structures of novel pyridyl functionalised [Tl(L)]∞ (L = (N-benzyl-N-methylpyridyl) dithiocarbamate(L1) 1, bis(N-methylpyridyl) dithiocarbamate(L2) 2, (N-methyl(1,4-benzodioxane-6-yl)-N-methylpyridyl)dithiocarbamate(L3) 3, (N-ferrocenyl-N-methylpyridyl) dithiocarbamate(L4) 4) complexes revealed rare intermolecular C-H···Tl anagostic and C-S···Tl interactions forming a six-membered chelate ring about the metal center, which have been assessed by DFT calculations. The strong thallophilic bonding is responsible for the strong luminescent characteristics of the complexes in the solid phase.

Biferrocene bearing planar metal dithiocarbamates, namely, [M(FcCH2dtc)2] (dtc = furan-2-ylmethyldithiocarbamate, M = Cu(II) 1, Ni(II) 4; dtc = benzo[d][1,3]dioxol-5-ylmethyl dithiocarbamate, M = Cu(II) 2, Ni(II) 5; dtc = pyridin-2-ylmethyldithiocarbamate, M = Cu(II) 3, Ni(II) 6; Fc = ferrocenyl; Fe(η(5)-C5H5)(η(5)-C5H4-)), have been synthesized and characterized by microanalysis, magnetic susceptibility and cyclic voltammetry. Structures of 1, 2 and 4 have been obtained by single crystal X-ray diffraction. These complexes with pyridyl, piperonyl and furfuryl as heteroaromatic groups in the dithiocarbamate ligands have been exploited as sensitizers in dye sensitized TiO2 solar cells for converting sunlight into electrical energy. Light-to-electrical energy conversion efficiencies achieved using these sensitizers are considerably greater than those obtained with analogous compounds previously reported by us. The overall conversion efficiency (η) is found to be dependent upon the nature of the heteroaromatic conjugated linkers and increases in the order η (ferrocenylfurfuryl) > η (ferrocenylpiperonyl) > η (ferrocenylpyridyl) all values being lower than that obtained in the reference Ru dye N719 under similar experimental conditions. The conversion efficiencies also vary with the metal being higher for Ni (4, 5 and 6) than for Cu complexes (1, 2 and 3). The X-ray structural analyses reveal the existence of rare M···H-C intermolecular anagostic interactions involving the metal atom in chain motifs in 1 and 4, which are retained in solution as evidenced by (1)H NMR spectroscopy.

Two new heterobimetallic phenylmercury(ii) dithiocarbamate complexes incorporating the ferrocenyl moiety (C(5)H(5))Fe(C(5)H(4)) (Fc), namely PhHgS(2)CN(CH(2)Fc)CH(2)C(5)H(4)N, (1) and PhHgS(2)CN(CH(2)Fc)CH(2)C(4)H(3)O, (2) have been prepared and characterized by elemental analysis, UV-Vis, IR, (1)H and (13)C NMR spectroscopies. The crystal structures of 1 and 2 showed a linear core at the Hg(ii) centre of the molecule, bound by the sulfur atom of the dithiocarbamate ligand and carbon atom of the aromatic ring. Weak intermolecular HgS interactions form "head-to-tail" dimers in the cases of 1 and 2. The observed quasi-reversible cyclic voltammograms of the complexes have been corroborated by calculating gross natural electron population and gross natural electron spin population at each atom for the neutral as well its oxidized species obtained at density functional level (DFT) of theory, which suggests that the delocalization of electron spin population can affect the magnitude of ΔE(p). The electronic absorption bands of both the complexes were assigned with the help of time dependent density functional theory (TD-DFT) calculations. The light harvesting properties of both 1 and 2 in conjunction with our previously reported compound PhHgS(2)CN(CH(2)Fc)CH(2)C(6)H(5) (3) have been reported.

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