Syntheses, crystal, photoluminescence and electrochemical investigation of some new phenylmercury(II) dithiocarbamate complexes involving ferrocene

A series of new heterobimetallic phenylmercury(II) dithiocarbamate complexes incorporating the ferrocenyl moiety (C5H5)Fe(C5H4) (Fc), namely PhHgS2CN(CH(2)Fc)CH2C6H5, (1), PhHgS2CN(CH(2)Fc)CH(CH3)(2), (2), PhHgS2CN(CH(2)Fc)(CH2)(3)CH3, (3) and [PhHgS2CN(CH(2)Fc)](2)(CH2C6H4CH2), (4) have been prepared and characterized by elemental analysis, UV-Vis, IR, H-1 and C-13 NMR spectroscopies. The crystal structures of 1, 2 and 4 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 Hg center dot center dot center dot S interactions form "head-to-tail" dimers in the cases of 1 and 2. 4 forms a similar dimeric structure, forming two pairs of Hg center dot center dot center dot S interactions to generate a tetrametallic unit. The observed quasi-reversible cyclic voltammograms of the complexes have been corroborated by calculating gross electron population at each atom for the neutral as well its oxidized species obtained at the density functional level (DFT) of theory, which suggests an electron withdrawing effect from the organomercury(II)-dithiocarbamate group. The electronic absorption bands of all the four complexes were assigned with the help of time dependent density functional theory (TD-DFT) calculations. Upon excitation at similar to 440 nm 1, 3 and 4 exhibited a medium strong photoluminescence emission at similar to 500 nm as a consequence of MLCT intraligand charge transfer. 1, when excited at 256 nm exhibits photoluminescence emission at 398 nm.