in benzene byproducts: P(C6H5)2P(C6H5)2; PPh2Cl injected into soln. of Hf complex in C6H6, stirred for 3 min at room temp.; solvent removed, solid extd. with n-hexane to leave Hf product;

in benzene byproducts: Si(CH3)3P(C6H5)2; SiMe3Cl added to soln. of complex at room temp.; solvent removed, residue washed with n-hexane to give Hf(cp)2Cl2;

in benzene byproducts: P(C6H5)2As(C6H5)2; AsPh2Cl injected into soln. of Hf complex in C6H6, stirred for 3 min atroom temp.; solvent removed, solid extd. with n-hexane to leave Hf product;