Exploration Of Nickel Complexes Supported By Trimethylphosphine In Activation And Functionalization Of C(sp~2)-Cl And N(sp~3)-H Bonds

Nickel belongs to VIII family of transition metals. Because of its fine coordination activity and relatively low price, it has been widely used in organic synthesis, industrial catalysis, etc. Trivalent phosphine as a strong ligand can form stable complexes with transition metals, and can be widely found in organometallic compouds. Organonickel compound supported by trimethylphosphine has high reaction activity and selectivity.1. Application of nickel(0) complexes supported by trimethylphosphine in C(sp2)-Cl bond activationChloroarenes play an important role in many fields of the society, especially in industry and agriculture, but also lead to seriously social and environmental problems. They are commonly found as soil and groundwater contaminants, because most of them are toxic and thermally stable. How to cope with these issues has driven several research groups to examine practical and effective methods in order to transform highly toxic or inert chloroarenes into useful or environment-friendly substances. Activation of the comparatively inert C-Cl bond seems to be a feasible approach using transition metal complexes under stoichiometric and catalytic conditions, which could be found in cross-coupling reactions such as the Heck reaction, the Suzuki coupling, and the Stille coupling. Catalytic activation of the C(sp2)-Cl bond by transition-metal complexes is the first key step in these reactions.Reactions of Ni(PMe3)4 with ortho-Chlorinated benzamides (1-4), proceed by oxidative addition of the C(sp2)-Cl bond to give rise to the organo nickel (II) complexes (5-8), respectively.Under nitrogen, when a solution of 5-8 was treated under 1 bar of CO, new phosphinium salts (9-12) were isolated as a white powder which were also gotten through one-pot reaction of Ni(PMe3)4 with ortho-Chlorinated benzamides (1-4) in CO atmosphere. 2. Application of Ni(II) Complexes Supported with trimethylphosphine in N(sp3)-H bond activationActivation of the N-H bond of amides, amines and ammonia by a transition-metal center may play a role in developing new catalytic processes based on these abundant compounds. However, this process is not simple because amines tend to bind to vacant coordination sites of metal complexes via their lone electron pair, thereby making subsequent N-H bond cleavage difficult.Treatment of Ni(Me)2(PMe3)3 with 2,6-difluoro-Benzamide results in the corresponding coordinately unsaturated four-coordinate nickel (Ⅱ) complex 18. Then the reaction of 18 with CO gives rise to the organic fluoride 19 which could be also obtained through one-pot reaction of Ni(Me)2(PMe3)3 with 2,6-difluoro-Benzamide in CO atmosphere.All of the new complexes are characterized by IR,1H NMR,13C NMR and 31P NMR. Structures of some compounds have been confirmed by X-ray diffraction techniques.