[Pd(NHC)(allyl)Cl] Complexes: Synthesis and Determination of the NHC Percent Buried Volume (%Vbur) Steric Parameter

Abstract Complexes of palladium bearing NHC ligands (NHC=N‐heterocyclic carbene) were synthesized and fully characterized. The [Pd(NHC)(allyl)Cl] series was obtained by simple cleavage of [Pd(allyl)Cl] 2 by using either the isolated free NHC or the in situ generated NHC. The NHC ligand sterics were varied by introduction of groups attached to the C4–C5 carbon atoms of the NHC backbone. Results of the X‐ray diffraction study permitted determination of the NHC steric parameters within this series. It was observed that the NHC backbone induces variations in its percent buried volume (% V bur ) as a function of the N‐substituents.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)