Formation of the paramagletic Ni(I) π-allyl complex in the Ni(allyl)2 – (2,6-diisopropylphenyl)diazabutadiene system

It has been shown that the reaction of Ni(allyl)2 with (2,6-diisopropylphenyl)diazabutadiene gives the imino-amide Ni complex (1). The imino-amide moiety of this complex undergoes some complicated rearrangements resulting in spontaneous formation of a paramagnetic π-allyl Ni(I) complex. Nickel complexes formed in the system have been studied with ESR, FTIR, 2D NMR, and mass spectrometry. The structure of complex 1 was studied with X-ray diffraction.

Graphical abstractThe system, initially formed from “hydrogen-deficit” nickel (II) diamagnetic allyl complexes and containing no potential one-electron reducers, spontaneously evolves toward the formation of nickel (I) paramagnetic complexes which proved to be the final products of the complicated and multistep route of spontaneous transformations of the nickel (II) individual organometallic complex.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ni(allyl)2 reacts with diimine ligand to give a Ni(II) complex. ► This complex spontaneously undergoes a sequence of rearrangements. ► The process ultimately ceased with transformation of Ni(II) to paramagnetic Ni(I). ► Ni(II) turns spontaneously to Ni(I) with hydrogen evolution. ► A mechanism for the spontaneous transformation of Ni(II) to Ni(I) was proposed.