Synthesis, Properties, and Crystal and Molecular Structures of the Complexes [Mo(XC₆H₄CSN₂)(XC₆H₄CSN₂H)(XC₆H₄CSNNC(CH₃)₂)] (X = P-Chloro, P-Methyl). Species Possessing Three Chemically and Crystallographically Distinct Chelate Rings

The crystal and molecular structures of the complexes [Mo(XC₆H4CSN2)(XC₆H4CSN2H)(XC₆H₄CSNNCMe₂)], X = CH₃ (III) and C1 (IV), have been investigated by X-ray diffraction techniques. Compound III crystallizes in the triclinic space group PI with two molecules in the unit cell of dimensions a = 12.505 (9) Å, b = 12.533 (10) Å, c = 10.274 (8) Å, α = 115.62 (1)°, β = 86.41 (2)°, and γ = 93.45 (1)°, while compound IV displays monoclinic symmetry, space group P2\jc with four molecules in the unit cell of dimensions a = 13.049 (1) Å, b = 12.838 (1) Å, c = 17.183 (1) Å, and β = 90.87 (1)°. The structures were solved by using 2573 and 2889 symmetry-independent reflections, respectively, with I ≥ 2.58σ(7). Refinement by full-matrix least-squares methods, using anisotropic temperature factors for all nonhydrogen atoms, gave a final R factor of 0.073 for III. Similar refinement, with the inclusion of hydrogen atoms with isotropic thermal parameters, yielded a final residual of 0.038 for IV. The structures are essentially identical with a coordination polyhedra intermediate between trigonal-prismatic and octahedral geometries with the sulfur and nitrogen donor atoms disposed on opposite triangular faces in a facial configuration. In complex IV the chelate rings exhibit Mo-N bond distances and Mo-N-N valence angles of 1.786 (5) Å and 142.8 (3)° for the diazenido(l-) ligand, 1.967 (5) Å and 131.6 (4)° for the diazene ring, and 2.216 (5) Å and 116.9 (4)° for the hydrazonido form. The Mo-S distance of 2.48 Å for the sulfur trans to the multiply bonded diazenido nitrogen is significantly longer than the average distance 2, 457 (2) Å for the other Mo-S bonds and indicates a structural trans influence. The severe distortions from the trigonal-prismatic geometry are partially steric in origin, arising from the introduction of the hydrazonido group and resultant nonbonding interactions in the N1N3N5 plane.