Preparation and characterization of bis[dihalo(mu-bis(diphenylphosphino)amine)molybdenum(II)] complexes

Complexes having the formula Mo(2)X(4)(mu-dppa)(2) (X = Cl (2) Br (3); dppa = bis(diphenylphosphino)amine) can be synthesized by the reaction of Mo-2(OAc)(4) (OAc = mu-CH3COO) with dppa and an excess of (CH3)(3)SiX under reflux conditions. Both compounds were characterized by IR and UV/vis spectroscopy and by P-31{H-1} and H-1 NMR spectroscopy. Single-crystal diffraction studies afford the following pertinent crystal data for 2 and 3, respectively: monoclinic P2(1)/c, a = 15.522(4) Angstrom, b = 17.881(5) Angstrom, c = 16.898(3) Angstrom, beta = 91.15(2)degrees, Z = 4; orthorhombic P2(1)2(1)2(1), a = 19.654(2), b = 19.865(2) c = 14.792(1), Z = 4. Both compounds exhibit significant torsion angles but, nevertheless, have comparatively short Mo-Mo bond distances (2, d(Mo-Mo) = 2.134(1) Angstrom; 3, d(Mo-Mo) = 2.137(2) Angstrom).