Role of paramagnetic Ni(I) and Ni(III) complexes in catalytic reactions of unsaturated hydrocarbons

By analyzing experimental data collected by systematic investigation of Ni(I) complex formation conditions, it is demonstrated that, when a system simultaneously contains Ni(0) and Ni(II) complexes, whether cationic or electroneutral, stabilized by olefinic or organoelement ligands, the complexes undergo comproportionation to form Ni(I) complexes. Using individual Ni(II) complexes as examples, it is shown that the spontaneous decomposition of hydrido and organometallic Ni(II) complexes yields Ni(I) complexes. The Ni(I) and Ni(III) complexes are involved in the catalytic cycles of reactions of olefins and acetylenes.