in benzene react. under vac. or N2 atmosphere; combination of Ph2GaBr and As-compd. in C6H6 (ratio Ph2GaCl : As-compd. = 2:1), stirring for 65 h at room temp.; removal of solvent and Me3SiBr in vac., extn. with ligroin, cooling of the combined exts. to -17°C for 44 h; elem. anal.;