Reactivity of nickel metal precursors towards amido linked N-heterocyclic carbenes and their catalytic studies for cross coupling reactions

Abstract

The refluxing of chloroacetamide derivatives with n-butyl imidazole resulted in their corresponding salt of composition 1-(n-butyl)-3-N-(2-Ar)acetamido-1, 3-imidazolium chloride (Ar = furylmethyl (1a); phenylmethyl (1b)). The latter salt on treatment with DBU followed by the addition of chalcogen atom resulted into a compound [(1-(n-butyl)-3-N-(2-Ar)acetamido-1,3-imidazol-3-ylidine)E] (Ar = furylmethyl; E = S (2a); Ar = phenylmthyl; E = Se (2b)). Similarly, the reaction of the imidazolium salts with, excess K2CO3 and NiCl2·6H2O yielded compounds [(1-(n-butyl)-3-N-(2-Ar)acetamido-1,3-imidazol-3-ylidine)]2Ni (Ar = furylmethyl (3a); phenylmethyl (3b)). The latter complexes have also been isolated by using Ni(II) phosphine precursors [NiCl2(PP)] (PP = PPh3, dppf). The molecular structure of [(1-(n-butyl)-3-N-(2-furylmethyl)acetamido-1, 3-imidazol-3-ylidine)]2Ni and [(1-(n-butyl)-3-N-(2-phenylmethyl)acetamido-1, 3-imidazol-3-ylidine)]2Ni were established by single crystal X-ray diffraction analysis. The catalytic property of complex 3a and 3b for cross coupling reactions has been studied.