Preparation and Characterization of Bis[dihalo(μ-bis(diphenylphosphino)amine)molybdenum(II)] Complexes

Complexes having the formula Mo₂X₄-dppa)₂ (X = Cl (2) Br (3); dppa = bis(diphenylphosphino)amine) can be synthesized by the reaction of Mo₂(OAc)₄ (OAc = μ-CH₃COO) with dppa and an excess of (CH₃ )₃SiX under reflux conditions. Both compounds were characterized by IR and UV/vis spectroscopy and by ³¹P{¹H} and ¹H NMR spectroscopy. Single-crystal diffraction studies afford the following pertinent crystal data for 2 and 3, respectively: monoclinic P2₁/c, a = 15.522(4) Å, b = 17.881(5) Å, c = 16.898(3) Å, β= 91.15(2)°, Z = 4; orthorhombic P2₁2₁2₁, 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) Å; 3, d(Mo-Mo) = 2.137(2) Å).