Carbon Halide Bond Activation of Aroyl Halides using an NHC‐stabilized Nickel(0) Complex

Aroyl complexes of the type trans ‐[Ni( i Pr 2 Im) 2 (X)( C (O)Ar)] (X = Cl and Ar = Ph ( 2 ), 4‐ t Bu‐C 6 H 4 ( 3 ) and C 6 F 5 ( 4 ) and X = Br and Ar = Ph ( 5 )) were prepared by oxidative addition reactions of carboxylic acid halides with the dinuclear nickel(0) complex [Ni 2 ( i Pr 2 Im) 4 (COD)] ( 1 ) ( i Pr 2 Im = 1, 3‐di iso propylimidazolin‐2‐ylidene; COD = 1, 5‐cyclooctadien). The reported compounds were characterized by multinuclear NMR spectroscopy, EI‐mass spectroscopy, IR spectroscopy, and elemental analysis. The benzoyl chloride complex trans‐ [Ni( i Pr 2 Im) 2 (Cl)( C (O)Ph)] ( 2 ) as well as its bromide analogue trans ‐[Ni( i Pr 2 Im) 2 (Br)( C (O)Ph)] ( 5 ) were additionally structurally characterized by single‐crystal X‐ray crystallography. NMR spectra of the crude products revealed the formation of minor amounts of the corresponding bis(halide) complexes trans ‐[Ni( i Pr 2 Im) 2 (Cl) 2 ] ( 6 ) and trans ‐[Ni( i Pr 2 Im) 2 (Br) 2 ] ( 7 ), depending on the aroyl halide used. Decarbonylation of the benzoyl complexes was observed upon irradiation of the complexes 2 and 5 with UV light. NMR analysis of the resulting mixtures of products revealed the formation of the phenyl halide complexes trans ‐[Ni( i Pr 2 Im) 2 (Cl)(Ph)] ( 8 ) and [Ni( i Pr 2 Im) 2 (Br)(Ph)] ( 9 ), as well as the formation of the bis(halide) complexes 6 and 7 .