New bidentate 20 membered macrocyclic bis(N-heterocyclic carbene) trans chelating ligands were synthesized and characterized. Silver carbene complexes were synthesized for transmetallation of Group 10 metals. Single X-ray diffraction studies on a silver(I)-bis(NHC) complexes show an unusual tetramer consists of an [Ag2Br4]2- core connected to two Ag(NHC) cations. The silver core consists of strong Ag-Ag bond with bond distances of 2.9328 Å. The Silver carbene complexes can serve as a carbene transfer reagent. The reaction between silver carbene and 1 equivalent of bis(acetonitrile)dichloro-palladium(II) in methylene chloride afforded bis(NHC)Pd(II)Cl2 complexes. The silver carbene and trans-bis(NHC)Pd(II)Cl2 complexes were fully characterized by nuclear magnetic resonance spectroscopy, high resolution mass spectroscopy and X-ray diffraction. X-ray diffraction analysis revealed that trans-bis(NHC)Pd(II)Cl2 molecules adopts C2 symmetric structure, in which the bis(NHC) ligand is coordinated from opposite sides with a 180 degree angle forming a square planar palladium center. These trans-bis(NHC)Pd(II)Cl2 complexes were surveyed for Heck and Suzuki cross coupling reactions.

Macrocyclic bidentate N-heterocyclic carbene ligands for group 10 metals for catalysis

254th National Meeting (2017)

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