in tetrahydrofuran all manipulations under N2 atm.; calcd. amt. of metal chloride added to soln. of Hf complex in THF at 25°C, mixt. stirred at 25°C for 4 h; volatiles removed under vac., residue dissolved in Et2O/n-pentane (2/1),filtered through kieselgur, chromy. (kieselgel, n-pentane, -20°C ), evapd.;

in tetrahydrofuran all manipulations under N2 atm.; calcd. amt. of metal chloride added to soln. of Hf complex in THF at 25°C, mixt. stirred at 25°C for 4 h; volatiles removed under vac., residue dissolved in Et2O/n-pentane (2/1),filtered through kieselgur, chromy. (kieselgel, n-pentane, -20°C ), evapd.;

in tetrahydrofuran all manipulations under N2 atm.; calcd. amt. of metal chloride added to soln. of Hf complex in THF at 25°C, mixt. stirred at 25°C for 4 h; volatiles removed under vac., residue dissolved in Et2O/n-pentane (2/1),filtered through kieselgur, chromy. (kieselgel, n-pentane, -20°C ), evapd.;