Synthesis and characterization of [trans-di(mu-acetato)(mu-bis(diphenylphosphino)methylamine)-bis(pyridine)dimolybdenum(II)]bis(tetrafluoroborate) and derivatives

Reaction of trans-[Mo-2(mu-O2CCH3)(2)(mu-dppma)(2)(MeCN)(2)](BF4)(2) (1, dp pma = diphenylphosphinomethylamine) with a variety of pyridine derivatives leads to axially substituted complexes of formula trans-[Mo-2(mu-O2CCH3)(2) (mu-dppma)(2)(NC5H4-R)(2)](BF4)(2) (R = H, 2; C(CH3)(3), 3; C6H5, 4; CH=CHC 6H5, 5; CCH, 6; CN, 7). The obtained complexes were characterized by H-1-, C-13- and P-31{H-1}-NMR, IR, Raman spectroscopy and elemental analyses. Ram an spectroscopy shows a weakening of the metal-metal interaction due to the axially coordinated pyridine ligands in all examined cases. Compound 2 was additionally examined by single-crystal X-ray analysis, revealing a Mo-Mo distance of 215.04(2) pm, which is slightly longer than that in compound 1 (213.15(3) pm). (C) 2000 Elsevier Science S.A. All rights reserved.