Preparation and Characterization of Bis(dialkyldithiocarbamato)[hydrotris(3,5-dimethyl-1-pyrazolyl)borato]molybdenum(III) Complexes Produced by the Oxidative Decarbonylation of [{HB(3,5-Me₂C₃N₂H)3}Mo(CO)3]^- by Tetraaikylthiuram Disulfides. Crystal Structure of {HB(3,5-Me₂C₃N₂H)₃}Mo(η²-S₂CNEt₂)(η¹-S₂CNEt₂)

The reactions of Et₄N[(HB(Me₂pz)₃}Mo(CO)₃] [HB(Me₂pz)₃^-= hydrotris(3,5-dimethyl-1-pyrazolyl)borate anion] and tetraaikylthiuram disulfides in refluxing acetonitrile produce the yellow or orange, air-sensitive compounds {HB(Me₂pz)₃}Mo(η²-S₂CNR₂)(η¹-S₂CNR₂) (1, R = Me; 2, R = Et). The compounds are monomeric, paramagnetic (μ_eff: 1, 3.93 μ_B, 2, 3.84 μ_B) and exhibit infrared bands characteristic of both mono- and bidentate dithiocarbamate ligands. Complex 2 crystallizes in triclinic space group P1 with a = 10.162 (4) Å, b = 11.089 (4) Å, c = 31.10 (1) Å, α = 88.49 (3)°, β = 86.34 (3)°, γ = 68.37 (3)°, V = 3251 (3) ų, and Z = 4. The structure was solved by Patterson and Fourier methods, followed by least-squares refinement, using 5547 reflections, to a conventional R value of 0.043 (R_w= 0.049). The complex possesses a distorted octahedral fac-N₃-fac-S₃ coordination sphere composed of tridentate HB(Me₂pz)₃^-, bidentate S₂CNEt₂^-, and monodentate S₂CNEt₂^- ligands. Structural comparison of the two dithiocarbamate ligands indicates considerable thioureide character in the η¹ -ligand framework.