Monomeric pyridyl-2-selenolate complexes of cadmium and mercury: Synthesis, characterization and their conversion to metal selenide nanoparticles

Reactions of [MCl2(tmeda)] (M = Cd or Hg; tmeda = N,N,N',N'-tetramethylethylenediamine) with M'SeC5H3(R-3)N (R = H or Me) gave selenolate complexes of the general formula [M{SeC5H3(R-3)N}(2)(tmeda)(n)] (M/R/n = Cd/H/1 (1); Cd/Me/1 (2); Hg/H/1 (3) and Hg/Me/0 (4)). The complexes were characterized by elemental analysis, UV-Vis and NMR (H-1, C-13, Se-77, Cd-113 and Hg-199) spectroscopy. The crystal structures of {SeC5H3(Me-3)N}(2), [M(SeC5H4N)(2)(tmeda)] (M = Cd or Hg) and [Hg{SeC5H3(Me-3)N}(2)] were established by single crystal X-ray diffraction. The complex, [Cd(SeC5H4N)(2)(tmeda)] comprises of an octahedral cadmium atom containing three chelating, two SeC5H4N and one tmeda, ligands. The corresponding mercury complex adopts a severely distorted tetrahedral configuration defined by the two-monodentate selenolate and chelating tmeda. The complex, [Hg{SeC5H3(Me-3)N}(2)] has a linear structure with monodentate selenolate ligand. The cadmium complexes undergo a two-step decomposition (TGA) leading to the formation of CdSe. Thermolysis of [Cd{SeC5H3(R-3)N}(2)(tmeda)(n)] in hexadecylamine (HDA)/tri-n-octylphosphineoxide (TOPO) yields CdSe nanoparticles, which were characterized by UV-Vis, XRD, SEM and TEM (in part). (C) 2010 Elsevier B. V. All rights reserved.