Synthesis and characterization of molybdenum and tungsten complexes containing tert-butylcyclopentadienyl ligand

New molybdenum and tungsten complexes containing tert-butylcyclopentadienyl ligand (Cp'= ^tBu-C₅H₄) have been prepared and characterized. The reaction of M(CO)₃(CH₃CN)₃ with tert-butylcyclopentadiene provide improved route to the metal-metal bond compounds [Cp'M(CO)₃]₂ (M= Mo (Ia), W (Ib)) in good isolated yields. New examples of mononuclear complexes have also been prepared. The yellow complexes Cp'M(CO)₃R (R= CH₃, CH₂C₆H₅) (IV) and [Cp'Mo(CO)₃SO₂(p-C₆H₄X)] (V) (X= CH₃, Cl) have been prepared from the reaction of the anions, [Cp'M(CO)₃]^-, with alkyl halides or arylsulfonyl chlorides in THF solvent, respectively. Protonation of the anion [Cp'M(CO)₃]^- with glacial acetic acid, which gave the hydride complexes, followed by stirring in CCl₄ / THF or refluxing with CH₃I in benzene produce the corresponding halides Cp'M(CO)₃Cl (II) or Cp'M(CO)₃I (III), respectively.