in diethyl ether (Ar); reaction at -30°C (3 h), stirring (0°C), evapn. of the solvent (vacuum), addn. of n-pentane to the residue, filtration, cooling (-78°C, 24 h); filtration, recrystn. (n-pentane, -78°C, 20 h);

in diethyl ether T=-103.16°C;

in diethyl ether T=-103.16°C;

in tetrahydrofuran Ar atmosphere, -23°C;

in diethyl ether T=-103.16°C;