Di-p-tolylhafnocene,di-o-tolylhafnocene and di-m-tolylhafnocene were synthesized by reaction of aryllithium with hafnooene dichloride.The steric effect of o-methyl group in the ditolylmetallocenes(M=Ti,Zr,and Hf) were compared.It decreases in the order:di(o-tolyl) >vitanocone >di(o-tolyl) zireonocene>di(o-tolyl)-hafnocene.These compounds readily react with electrophilic reagents such as hydrogon chloride,acetyl chloride and bromine,resulting in the cleavage of the carbon-hafnium bond.The diphenylhafnocene and ditolylhafnocenes lost one phenyl or tolyl group by hydrolysis and gave the compounds with general formula [(η⁵-C₅H₅)₂ Ar Hf]₂O.The reaction of the latter with HCl lad to the cleavages of Ar-Hf and Hf-O-Hf bonds and the formation of hafnocene dichloride.The lR and NMR spectra of these new serial of organometallic compounds were given.