Formation of carbocationic sigma-alkyl Ni(I) complexes in the catalytic system Ni(PPh3)(4)+BF3 center dot OEt2 center dot ionic coordination transformations of unsaturated hydrocarbons

The reactions of the individual cationic complex [(PPh3)(3)Ni]BF4 with unsa turated hydrocarbons (ethene, propene, and styrene), as well as the reactio n of the sigma -alkyl Ni(I) complex (PPh3)(2)Ni-CH(COOC2H5)(2) (obtained in situ) with ethene, were studied using EPR, UV, and NMR spectroscopy. It wa s found that stable dimeric carbocationic sigma -alkyl Ni(I) complexes are intermediates in the reactions of unsaturated hydrocarbons with cationic Ni (I) complexes. The transformations of unsaturated hydrocarbons on cationic Ni(I) complexes were explained in terms of an experimentally justified ioni c coordination mechanism. A stable mononuclear Ni(I) complex with a Ni-C si gma -bond was synthesized and characterized using EPR. An organonickel(I) c omplex with pi- and sigma -bonded carbon atoms was identified using EPR and NMR methods.