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

Reaction of trans-[Mo2(μ-O2CCH3)2(μ-dppma)2(MeCN)2](BF4)2 (1, dppma=diphenylphosphinomethylamine) with a variety of pyridine derivatives leads to axially substituted complexes of formula trans-[Mo2(μ-O2CCH3)2(μ-dppma)2(NC5H4-R)2](BF4)2 (R=H, 2; C(CH3)3, 3; C6H5, 4; CHCHC6H5, 5; CCH, 6; CN, 7). The obtained complexes were characterized by 1H-, 13C- and 31P{1H}-NMR, IR, Raman spectroscopy and elemental analyses. Raman 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).