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

Molecules of the formula Mo(2)X(2)(OAc)(2)(mu-dppa)(2) (X = Cl (2), Br (3), I (4); dppa = bis(diphenylphosphino)-amine; OAc = CH3COO-) can be synthesized by the reaction of Mo-2(OAc)(4) (1) With dppa and (CH3)(3)SiX. All three compounds were characterized by IR and UV-visible spectroscopy, mass spectrometry, and P-31{H-1} NMR spectroscopy. Single-crystal diffraction studies yield the following pertinent crystal data: for 2 . 2EtOH, orthorhombic Pbca (No. 61), a = 16.830(2) Angstrom, b = 20.310(4) Angstrom, c = 16.751(2) Angstrom, V = 5726(2) Angstrom(3), Z = 4; for 3 . 2(toluene), monoclinic C2/c (No. 15), a = 22.481(2) Angstrom, b = 19.151(9) Angstrom, c = 14.358(2) Angstrom, beta = 95.19(2)degrees, V = 6156(3) Angstrom(3), Z = 4; for 4 . EtOH . CH3CN, monoclinic P2(1)/c (No. 14), a = 20.607(9)Angstrom, b = 16.020(3) Angstrom, c = 17.189(5) Angstrom, beta = 95.81(2)degrees, V = 5645(3) Angstrom(3), Z = 4. The Mo-Mo distances for compounds 2-4 are 2.158(1), 2.176(1), and 2.164(1) Angstrom, respectively. Both crystallographic data and physical measurements indicate that 2 and 3 have nearly identical Mo-X bond distances while those in 3 and 4 differ more significantly; the spectroscopic data bear this out. The Mo-O and Mo-P distances are very similar in all three of the complexes reported.