REACTION OF CP-ASTERISK(CO)(2)RE=RE(CO)(2)CP-ASTERISK IN THF WITH DIETHYL FUMARATE PRODUCES CP-ASTERISK-RE(CO)(3) AND P-ASTERISK-RE(CO)(ETA(2)-(E)-ETO2CCH=CHCO2ET)(THF)

The rhenium dimer complex Cp(CO)(2)Re=Re(CO)(2)Cp* (1) (Cp* = C5Me5) reacted in THF with diethyl fumarate in a fragmentation reaction to fo rm CpRe(CO)(3) (3) and Cp*Re(CO)(eta(2)-(E)-EtO2CCH=CHCO2Et)(THF) (6) . Reaction of 6 with CO resulted in substitution of the THF ligand wit h CO to form the alkene complex CpRe(CO)(2)(eta(2)-(E)-EtO2CCH=HCO2Et ) (7). Variable temperature H-1-NMR spectroscopy of 7 showed that rota tion of the alkene ligand is slow below -50 degrees C. (C) 1998 Elsevi er Science S.A. All rights reserved.