Bis-indenyl molybdenum(iv) halide complexes: synthesis and X-ray studies

Abstract

A stepwise route to bis-indenyl halide derivatives of molybdenum is reported. Treatment of [Ind₂Mo(CO)₂][BF₄]₂ with one equivalent of Bu₄NBr in CH₂Cl₂ yielded [Ind₂Mo(CO)Br][BF₄] (1). When 1 was refluxed in NCMe and irradiated with a 60 W tungsten bulb [Ind₂Mo(NCMe)Br][BF₄] (2) was isolated. The reaction of [Ind₂Mo(CO)Br][BF₄] with LiBr afforded Ind₂MoBr₂ (3). The Ind₂MoCl₂ (4) analogue has been prepared directly by reaction of [Ind₂Mo(CO)₂][BF₄]₂ with LiCl.

The reaction of Ind₂MoBr₂ with AlMe₃ in toluene produces the bromo-methyl species Ind₂MoBrMe (5). Treatment of Ind₂MoBr₂ with TlPF₆ in the presence of P(OMe)₃ afforded [Ind₂Mo{P(OMe)₃}₂][PF₆]₂ (6) which was readily reduced by two equivalents of cobaltocene to yield the neutral species Ind₂Mo{P(OMe)₃}₂ (7). Reaction of [Ind₂Mo(CO)₂][BF₄]₂ with P(OMe)₃ in dichloromethane yielded [Ind₂Mo(CO)Cl][BF₄] (8). The molecular structures of [Ind₂Mo(CO)X][BF₄] [X = Cl (8) or Br (1)], Ind₂MoBr₂ (3) and [Ind₂Mo{P(OMe)₃}₂][PF₆]₂ (6) have been determined by single crystal X-ray diffraction. The synthesis and characterisation of [(η³-Ind)Mo(CO)₂]₂[μ-η⁵-η⁵-(C₅H₄)₂SiMe₂] (9) is also reported.