Reaction of tetramethylimidazol-2-ylidene with (TptBu,Me)YbE(thf) (E=I, CH2SMe3):: simple adduct and a hydrocarbyl tethered carbene ligand

Treatment of (Tp(tBu,Me))YbE(thf) (E=I (1), CH2SiMe3 (2)) with tetramethylimidazol-2-ylidene (ImMe(4)) resulted in very different outcomes depending on the nature of the anionic ligand E. ImMe(4) acts as a simple Lewis base toward 1 resulting in substitution of the thf (tetrahydrofuran) ligand and formation of (Tp(tBu,Me))YbI(ImMe(4)) (3). However, reaction with 2, in addition to displacement of thf, proceeded by metalation of one of the N-CH3 substituents of ImMe(4) and gave (Tp(tBu,Me))Yb(ImMe(4))(CH2N(C(CH3)C(CH3)N(CH3)C) (4), featuring a hydrocarbyl tethered carbene ligand. The X-ray structures of 3 and 4 are reported. (c) 2006 Published by Elsevier B.V.