Formation of a Dirhenium Carbene Complex from Reaction of (η5-C5H4Li)Re(CO)3with (η5-C5H5)Re(CO)3

The ring-metalated complex (η 5 -C 5 H 4 Li)Re(CO) 3 generated by reaction of (η 5 -C 5 H 5 )Re(CO) 3 with n -BuLi in THF at −78 °C reacted with additional (η 5 -C 5 H 5 )Re(CO) 3 to produce the dirhenium acyl anion (η 5 -C 5 H 5 )(CO) 2 Re(C O)[(η 5 -C 5 H 4 )Re(CO) 3 ] - Li + . Protonation of this acyl anion gave the dirhenium hydroxycarbene complex (η 5 -C 5 H 5 )(CO) 2 Re C(OH)[(η 5 -C 5 H 4 )Re(CO) 3 ], while methylation gave the methoxycarbene complex (η 5 -C 5 H 5 )(CO) 2 Re C(OCH 3 )[(η 5 -C 5 H 4 )Re(CO) 3 ], which was characterized by X-ray crystallography. The methoxycarbene complex reacted with n -BuLi to produce the butylcarbene complex (η 5 -C 5 H 5 )(CO) 2 Re C(CH 2 CH 2 CH 2 CH 3 )[(η 5 -C 5 H 4 )Re(CO) 3 ].