Interaction of sulfur-containing compounds with transition metal clusters and metal surfaces: Final report, March 1, 1986-February 28, 1987

Molecular orbital calculations using effective core potentials (ECP) have been carried out on several nickel clusters. Optimization of internuclear distances and angles between the nickel atoms was carried out. The results are strongly dependent on the initial atomic configuration. Atomic closed shells gave no interactions between nickel atoms. Open shell systems, on the contrary, were shown to be more stable and the singly occupied 4s orbital accounted for the chemical bonding between the nickel atoms. Ground states of maximum multiplicity were obtained by considering that each nickel atom has a singly occupied d-orbital. These singly occupied d-orbitals did not participate in the bonding. According to these SCF results, the electronic configuration for each nickel atom in a particular cluster can be approximated as a localized 3d/sup 9/4s/sup 1/. In addition to theoretical calculations, metal complexes have been prepared in order to examine the bonding and structure of organic sulfur types in coal with transition metals known to activate carbon-sulfur bond cleavages, leading to desulfurization. Complexes of the general formula (M(Y)/sub 2/X/sub 2/) have been synthesized by the reaction of various Mo(II) tertiary phosphine complexes with thiolate and thioether ligands. The reaction of dichlorotris(triphenylphosphine) ruthenium(II), RuCl/sub 2/(PPh/sub 3/)/sub 3/ with 4-thiomethyldibenzothiophenemore » afforded RuCl/sub 2/(4-SCH/sub 2/(DBT))/sub 2/. The reaction of RuCl/sub 2/(PPh/sub 3/)/sub 3/ with 4-S-methyldibenzothiophene afforded RuCl/sub 2/(4-CH/sub 3/S(DBT))/sub 2/. The reaction of bis(triphenylphosphine) molybdenum dicarbonyl dibromide, Mo(CO)/sub 2/Br/sub 2/(PPh/sub 3/)/sub 2/ with 4-thiomethyldibenzothiophene afforded MoBr/sub 2/(4-SCH/sub 2/(DBT))/sub 2/. These complexes were characterized by IR, FABMS, MS, /sup 1/H- and /sup 13/C-NMR spectroscopy.« less