An Isolable Mononuclear Palladium(Ⅰ) Amido Complex

摘要

Mononuclear Pd(Ⅰ) species are putative intermediates in Pd-catalyzed reactions, but our knowledge about them is limited due to difficulties in accessing them. Herein, we report the isolation of a Pd(Ⅰ) amido complex, [(BINAP)Pd(NHAr~(Trip))] (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthalene, Ar~(Trip) = 2,6-bis(2',4',6'-triisopropylphenyl)phenyl), from the reaction of (BINAP)PdCl_2 with LiNHAr~(Trip). This Pd(Ⅰ) amido species has been characterized by X-ray crystallography, electron paramagnetic resonance, and multiedge Pd X-ray absorption spectroscopy. Theoretical study revealed that, while the three-electron-two-center π-interaction between Pd and N in the Pd(Ⅰ) complex imposes severe Pauli repulsion in its Pd-N bond, pronounced attractive interligand dispersion force aids its stabilization. In accord with its electronic features, reactions of homolytic Pd-N bond cleavage and deprotonation of primary amines are observed on the Pd(Ⅰ) amido complex.