Synthesis and Structures of Mono- and Dinuclear Molybdenum Complexes with Reduced -Diimine Ligands

The mononuclear molybdenum complex [Mo(L-H)(2)] (1), Mo-Mo single-bond compound [(LClMo)-L-H(mu-Cl)(3)(MoLCl)-L-H] [2; Mo-Mo 2.832(7) angstrom], and MoMo triple-bond compounds [Mo2Cl2(mu-L-H)(2)] [3; Mo-Mo 2.194(6) angstrom] and [Mo2Cl2(mu-Cl)(mu-L-H)Cl2Na(THF)(3)] [4; Mo-Mo 2.167(2) angstrom] have been synthesized by the reaction of L-H {L-H = [(2,6-iPr(2)C(6)H(3))NCH](2)} with 0.5, 1, and 2 equiv. of MoCl5 and different amounts of Na metal. In the single-bond compound 2, the -diimine ligand L-H displays the normal chelating coordination mode. In contrast, the triple-bond compounds 3 and 4 feature the less common bridging mode of -diimine ligands. Complexes 1-4 have been characterized by X-ray diffraction, H-1 and C-13 NMR, IR spectroscopy, elemental analysis, and their electronic structures were studied by EPR and DFT computations.