Cyclotriveratrylene-tethered trinuclear palladium( ii )–NHC complexes; reversal of site selectivity in Suzuki–Miyaura reactions

DOI: 10.1039/C9DT03400E

Authors: Jonathan M. Fowler (University of Leeds) , Edward Britton (University of Leeds) , Christopher M. Pask (University of Leeds) , Charlotte E. Willans (University of Leeds) , Michaele J. Hardie (University of Leeds)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Dalton Transactions , VOL 48 , PAGES 14687 - 14695

State: Published (Approved)
Published: October 2019
Diamond Proposal Number(s): 15059

Abstract: The trinuclear complexes [{PdI2(pyCl)}3(L1)] C1 and [{PdI2(pyCl)}3(L2)] C2, where pyCl = 3-chloropyridine, L1 = methyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene and L2 = benzyl(cyclotriguaiacylenyl)methylbenzimidazol-2-ylidene, each feature three palladium N-heterocyclic carbene (NHC) centres tethered onto a host-type cyclotriguaiacylene scaffold. Crystal structures of different solvates of complex C1 reveal different host–guest motifs including intra-cavity binding of dioxane guests concomitant with intramolecular halogen bonding interactions of C1. Mononuclear NHC analogues of C1 and C2, namely [PdI2(pyCl)(L3)] C3 and [PdI2(pyCl)(L4)] C4, where L3 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-methylbenzimidazol-2-ylidene and L4 = (3-chloropyridyl)-1-(2-methoxyphenyoxy)methyl-3-benzylbenzimidazol-2-ylidene, were also synthesised and their crystal structures determined. Complexes C1–C4 are competent catalysts for Suzuki Miyaura cross-coupling, and interestingly exhibit a switch in the normal regioselectivity observed for reactions of 2,4-dibromopyridine with aryl boronic acids, usually C2-selective, yielding C4-arylated product preferentially over C2-arylated product.

Subject Areas: Chemistry


Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 23/03/2020 18:39

Discipline Tags:

Molecular Complexes Chemistry Organic Chemistry

Technical Tags:

Diffraction Single Crystal X-ray Diffraction (SXRD)