Novel dithiocarbamate-Hg(II) complexes containing mixed ligands: synthesis, spectroscopic characterization, and H[sub]2 storage capacity

A tetrahedral Hg(II) diethyl dithiocarbamate (Et2Dt) complex containing triphenylphosphine (PPh3) of the composition [HgCl(╬║2-Et2Dt)2(PPh3)] (1) is prepared. Furthermore, complex (1) is used as a synthone to prepare a novel series of complexes of the following composition [Hg(Et2Dt)L(PPh3)] {L = saccharinate (2), thiosaccharinate (3), benzisothiazolinate (4), benzothiozole-2-thiolate (5), and benzooxazole-2-thiolate (6) anions}. The resulted complexes (1)-(6) are characterized by elemental analysis, molar conductivity, powder X-ray diffraction, fourier transform Infrared, and NMR (1H and 31P) spectroscopic techniques. The Et2Dt ligand is coordinated as bidentate chelate through the sulfur atoms, whereas the L ligands are bonded as monodentate ligands to afford a tetrahedral geometry around the Hg(II) ion. Nitrogen adsorption-desorption isotherm for two of as-prepared complexes (2) and (3) are measured first to get their Brunauer-Emmett-Teller surface area. Moreover, the mentioned two complexes are evaluated for their ability to store hydrogen gas at 77 K. However, the results of the hydrogen storage tests proved that the selected complexes are all capable of storing hydrogen, but in varying degrees, where complex (2) exhibited a storage capacity of 4.22 wt% under 88 bar.