Coordination Chemistry of New Sulfur-Containing Ligands. 25. Reduction and Deoxygenation of MoO3+(Aq) by Pyrrole-N-Carbodithioate (L) to Yield Eight-Coordinate MoL4: Crystal and Molecular Structure of Tetrakis(Pyrrole-N-Carbodithioato)Molybdenum-Hemi(Methylene Chloride)

The reaction between MoCl5 and potassium pyrrole-N-carbodithioate (K(pdc)) in an aqueous solution led to a surprising product with the stoichiometry Mo(pdc)4. Optical spectra and infrared spectra suggested an eight-coordinate, nonoxygenated molybdenum product. A single-crystal structural study on this material recrystallized from CH2Cl2 was carried out, and the eight-coordinate geometry was confirmed. The crystal Mo(pdc)4·½CH2Cl2 crystallizes in the centrosymmetric space group P1 with a = 11.197 (6) Å, b = 11.220 (5) Å, c = 13.165 (7) Å, α = 73.36 (4)°, β = 67.07 (4)°, γ = 66.75 (4) °, V = 1382 (1) Å3, and ρ(calcd) = 1.700 g cm-3 for mol wt 707.3 and Z = 2. A unique set of data (h,±k, ±l; 3° \u3c 2θ \u3c 45°; Mo Kα) were collected with a Nicolet R3m automated diffractometer using graphite-monochromatized radiation. The structure was solved via a combination of Patterson, Fourier, and least-squares techniques. The final discrepancy indices were RF = 3.17% and RuF = 3.26% for the 2822 unique data with F \u3e 6σ(F). The molecule has approximate D2d symmetry with the sulfurs located at the vertices of a D2d dodecahedron. The average Mo-S bond lengths are 2.54l and 2.507 Å for the dodecahedral a and b sites, respectively