Preparation of a cobalt-containing P,N-bidentate ligand ligated palladium complex: Its applications in amination and Suzuki cross-coupling reactions

A cobalt-containing P,N-ligand, alkyne-bridged dicobalt phosphine [(μ-PPh2CH2PPh2)Co2(CO)4(μ,η-Me2NCH2Ctriple bond; length of mdashCP(Cy)2)] (4c), was prepared from the reaction of Me2NCH2Ctriple bond; length of mdashCPR2 (2c) with a dppm-bridged dicobalt complex [Co2(CO)6(μ-P,P-PPh2CH2PPh2)] (3). Further reaction of 4c with Pd(COD)Cl2 gave a 4c-chelated palladium dichloride complex (μ-PPh2CH2PPh2)Co2(CO)4(μ,η-Cy2PCtriple bond; length of mdashCCH2NMe2)PdCl2 (5c). Compound 5c was characterized by spectroscopic methods and crystal structure of 5c was determined by single-crystal X-ray diffraction techniques. It shows that 4c is an authentic cobalt-containing P,N-bidentate ligand. Amination and Suzuki reactions employing either a 4c/palladium salt system or an isolated 5c as the catalytic precursor led to satisfactory results.