Synthesis And Reactivity Studies Of A Series Of Nickel(Ii) Arylchalcogenolates

Two series of high-spin nickel complexes, [Tp(Ph,Me)]Ni(EAr) (E = O, Se, Te; Ar = C6H5) and [Tp(Ph,Me)]Ni(SeC6H4-4-X) (X = H, Cl, Me, OMe), were prepared by metathetical reaction of the nickel(II) halide precursor with sodium salts of the corresponding chalcogen, NaEAr. X-ray crystallographic characterization and spectroscopic studies have established the geometric and electronic structures of these complexes. The observed spectroscopic and structural characteristics reveal distinct trends in accordance with the variation of the identity of the arylchalcogenolate and para substituent. Reaction of the [Tp(Ph,Me)]Ni(EAr) complexes with methyl iodide proceeded readily, producing the corresponding methylarylchalcogen and [Tp(Ph,Me)]NiI. A kinetic and computational analysis of the reaction of [Tp(Ph,Me)]Ni(SeC6H5) with MeI supports that the electrophilic alkylation reactions occur via an associative mechanism via a classical S(N)2 transition state.