Pb(OAc)4 in ethanol; dichloromethane byproducts: CH3COOH; under inert atm., Pb(OAc)4 was added to CH2Cl2 soln. of Re-complex at -40 °C portionwise over 10-20 min, stirring at 0 °C for 10 min, solvent was removed in vac., treatment with EtOH contg. excess of NaBPh4; solid was filtered off, crystd. by cooling from 25 to -25 °C in CH2Cl2 and EtOH, methyleneimine-deriv. was recrystd., crystn. by further cooling or by Pasteur sepn., elem. anal.;