Mono- and Tris-Phenoxo-Tethered N-Heterocyclic Carbene Yttrium Complexes: Syntheses and Molecular Structures

Abstract

The reaction of LiY[NiPr2]4 with H2LCl (L = O-4,6-di-tBu-C6H2-2-CH2-[C{N(CHCH)NiPr}]) and BuLi in the molar ratio of 1:3:2 at −78 °C affords a yttrium complex supported by three anionic NHC ligands, L3Y (1). Reaction temperature has a great effect on the reaction outcome. The same reaction at room temperature yields a monoanionic NHC yttrium complex co-supported by a bridged bisphenoxo group, LY[(O-4,6-di-tBu-C6H2)2(CH2)][iPrIm]2 (iPrIm = N-isopropylimidazole) (2) formed from the cleavage of NHC.