Synthesis and structural characterization of new mixed-ring indenyl derivatives of molybdenum containing phosphorus ligands

Reaction of NaBH4 with [IndCpMo(dppe)](BF4)2 (1) in acetone yields [IndMo(η4-C5H6)(dppe)]BF4 (2) quantitatively. The hydride addition takes place at the external face of the Cp ring. Dissolution of 2 in dichloromethane gives [IndMo(η4-C5H5-exo-CH2Cl)(dppe)]BF4, as confirmed by elemental analysis, IR and 1H NMR spectroscopy. The similar dication [IndCpMo{P(OMe)3}2](BF4)2 (4) reacts with NaBH4, in a solvent dependent manner. In acetonitrile, [IndMo(η4-C5H6){P(OMe)3}2]BF4 (5) is obtained and in acetone a P(OMe)3 ligand is lost resulting in the asymmetric phosphite-hydride, [IndCpMoH{P(OMe)3}]+ (6). The molecular structures of [IndMo(η4-C5H6){P(OMe)3}2]PF6 and [IndCpMoH{P(OMe)3}]PF6 were characterized by single-crystal X-ray diffraction.