New bulky phosphinopyridineligands. P∼N∼C Tridentates in palladium complexes

Abstract

The sterically bulky pyridinyl phosphine (P∼N) ligands have been prepared from the phosphinylation of 2,4-di-tert-butyl-6-methylpyridine. Due to the steric hindrance, substitution reaction of these P∼N ligands with (COD)PdMeCl yields the chloro-bridged dipalladium species [(P∼N)₂Pd₂Me₂Cl₂], in which the P∼N ligand acts as a monodentate. Treatment of these dimeric palladium compounds with AgBF₄ in the presence of acetonitrile gives the corresponding C–H activation metal complex [(P∼N∼C)Pd(CH₃CN)]BF₄. Both spectral and X-ray single-crystal characterization of these palladium complexes are presented.