title: Selective and adaptable access to N,N'-asymmetrically substituted imidazol-2-ylidene bis-NHC ligands: Pd(II) complexes featuring wide variation in N-alkyl and aryl steric bulk.
abstract: N,N'-Asymmetrically substituted, methylene-linked bis(imidazol-2-ylidene) complexes have been prepared subsequent to a selective synthesis of the bis(imidazolium) salt precursors involving the quarternisation of N-alkyl and -aryl imidazoles with N-halomethyl imidazolium salts. The adaptability of the ligand precursor synthesis is illustrated through access to the N-Me/N'-Mes and N-Mes/N'-2,6-(i-Pr)2Ph systems, leading to the Pd(II) complexes [{(MeIm)(MesIm)CH2}Pd(L)2](n+), L = Cl/I (n = 0) and NCMe (n = 2), and [{(MesIm)[2,6-(i-Pr)2PhIm]CH2}Pd(L)2], L = Cl/I. The dicationic hybrid N,N'-alkyl/aryl complex was inactive in the copolymerisation of ethylene/carbon monoxide, displaying reactivity akin to N,N'-dialkyl analogues.
authors: School of Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia. Michael.Gardiner@utas.edu.au
authors: Michael G
authors: MG
authors: Gardiner
authors: Curtis C
authors: CC
authors: Ho
authors: Felicity M
authors: FM
authors: Mackay
authors: David S
authors: DS
authors: McGuinness
authors: Matthew
authors: M
authors: Tucker