in diethyl ether -78°C; recrystn. from toluene;

in diethyl ether stirred under argon for 10 min at -78°C, allowed to warm from -78°C to room temp., after 1.5 h evapd., stirred with toluene; filtered, washed, extd. in vac., dried in vac., recrystd. from cold (-78°C) toluene, elem. anal.;

LiCH(Si(CH3)3)2 or KN(Si(CH3)3)2 in not given (inert atm.); treatment of uranium compd. with bis(trimethylsilyl)methyllithium or potassium amide deriv.; detected by NMR;

in benzene U complex was reacted with catecholborane in C6H6 at room temp. for 24 h;