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-Me₂NCH₂CCP(Cy)₂)] (4c), was prepared from the reaction of Me₂NCH₂CCPR₂ (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-Cy₂PCCCH₂NMe₂)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.