in 1,4-dioxane; toluene Ar atmosphere; cooling soln. of ligand (-78°C), mixing with soln. of n-BuLi (-78°C), warming to room temp. (2 h), cooling to -78°C, addn. of ZrCl4, warming to room temp., stirring (overnight); filtration (Celite), washing (toluene), solvent removal; elem. anal.;

in toluene ZrCl4 added to suspn. of Li salt at -30 °C, heated to 20 °C, stirred at 20 °C for 15 h, heated at 95 °C for 4 h, cooled to 20 °C, stand for 18 h; soln. decanted, residue extracted with toluene, concd., cooled to 0 °C, ppt. separated from mother liquor, washed with cold toluene, thenwith Et2O, dried under vac., mother liquor worked up again; elem. anal.;