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

New molybdenum and tungsten complexes containing tert-butylcyclopentadienyl ligand (Cp'= Bu-t-C5H4) have been prepared and characterized. The reaction of M(CO)(3)(CH3CN)(3) with tert-butylcyclopentadiene provide improved rout e to the metal-metal bond compounds [Cp'M(CO)(3)](2) (M= Mo (Ia), W (Ib)) i n good isolated yields. New examples of mononuclear complexes have also bee n prepared. The yellow complexes Cp'M(CO)(3)R (R= CH3, CH2C6H5) (IV) and [C p'Mo(CO)(3)SO2(p-C6H4X)] (V) (X= CH3, Cl) have been prepared from the react ion of the anions, [Pp'M(CO)(3)](-), with alkyl halides or arylsulfonyl chl orides in THF solvent, respectively. Protonation of the anion [Cp'M(CO)(3)] (-) wit glacial acetic acid, which gave the hydride complexes, followed by stirring in CCl4/THF or refluxing with CH3I in benzene produce the correspo nding halides Cp'M(CO)(3)Cl (II) or Cp'M(CO)(3)I (III) respectively.