Self-Assembly of Palladium-Based Macrocycles with N-Heterocyclic Carbene as the “Corner” Ligand

Abstract

Metallacyclic complexes [( Mes C−C meth )Pd(L)] 2 (OTf) 4 ( Mes C−C meth = 1,1′-dimesityl-3,3′-methylenediimidazolin-2,2′-diylidene; L = 4,4′-dithiodipyridine ( L 1 ) ( 5 ), 1,2-bis(4-pyridylthio)ethane ( L 2 ) ( 6 ), 1,3-bis(4-pyridylthio)propane ( L 3 ) ( 7 )) were obtained by the self-assembly of [( Mes C−C meth )Pd(CH 3 CN) 2 ](OTf) 2 with flexible pyridine-based ligands L 1 − L 3 in high yields. The reaction of [( Mes C−C meth )Pd(CH 3 CN) 2 ](OTf) 2 with a rigid pyrazine ligand led to the formation of mononuclear [( Mes C−C meth )Pd(pyrazine) 2 ](OTf) 2 ( 4 ), which can be ascribed to the effect of the steric bulk of the substituent. Complexes 4 − 6 have been well characterized by elemental analyses, 1 H NMR and IR spectra, and single-crystal molecular structure analysis.