in tetrahydrofuran all operations in sealed evacuated tubes with thoroughly dried and degassed solvents; soln. of the cuprate added to a soln. of La complex; stirred for 0.5 h at ca. 20° and for 2 h at 60°; ppt. of CuI sepd. by centrifugation; reaction mixt. concd. and kept at 80° until complete dissolution of a finely dispersed ppt.; cooledslowly to 20°; crystals sepd. and dried in vacuo; identified by elem. anal. and IR spectrum;