Abstract: An object of the present invention is to provide a method for directly performing arylation (particularly ?-arylation) of carbonyl or thiocarbonyl compounds using a more inexpensive phenol derivative and nickel catalyst. Another object of the present invention is to provide a novel nickel catalyst that can be used in this method, and a novel ligand of the nickel catalyst. The novel compounds of the present invention are a compound having a diphosphine skeleton in which a five- or six-membered heterocyclic ring is substituted with two dialkylphosphines and/or dicycloalkylphosphines, or a salt thereof, and a compound having the diphosphine skeleton that is bound to nickel. Moreover, coupling reaction of a carbonyl compound and a phenol derivative can be advanced in the presence of a nickel compound having a monodentate or bidentate dialkylphosphine and/or dicycloalkylphosphine skeleton.