The Ni(II) complexes [(N boolean AND O)Ni(H)(PMe3)] (1) and [(N boolean AND O)Ni(CH2CH3)(dmso)] (3) (N boolean AND O = kappa(2)-{(2,6-(3,5-(F3C)(2)C6H3)(2)C6H3)-N=C(H)-(3,5-l(2)-2-O-C6H2)}) were found to be well-defined model compounds to study the reactivity of polymerization active neutral Ni(II) species toward polar vinyl monomers. Methyl acrylate (MA) insertion into the Ni(II)-hydride bond of 1 was monitored at T >= -40 degrees C by NMR spectroscopy. 2,1-Insertion yields the functionalized Ni(II) alkyl complex [(N boolean AND O)Ni(C alpha H(CH3)C-beta(O)OCH3)(PMe3)] (4). Low-temperature 2D ROESY data indicate a weak Ni(II)center dot center dot center dot O=C-beta interaction in 4. This is supported by ab initio calculations at the gradient-corrected DFT (BP86/LACPV*) level of theory. Exposure of 1 to equal amounts of MA and ethylene afforded 4 and the Ni(II) ethyl complex 7 in a 9:1 ratio, which indicates that MA and ethylene effectively compete with each other for coordination and insertion. NMR spectroscopic monitoring revealed that 4 is stable in the absence of residual 1 at low temperatures but is subject to rapid bimolecular elimination of the functionalized alkyl moiety in the presence of free Ni(II) hydride species even at T = -40 degrees C. Isomerization into the 1,2-MA-insertion product was observed at T = 25 degrees C but occurred slowly compared to decomposition, which occurs at 0 degrees C by reaction of 4 with Ni(II) hydride formed by beta-elimination from 4 itself at this temperature. Exposure of the higher Ni(II) alkyl complex 3 to MA in the presence of excess ethylene results in the immediate formation of methyl pentanoate as the ultimate decomposition product. Functionalized Ni(II) alkyl species formed from 2,1-insertion of MA into the metal-carbon bond of higher Ni(II) alkyls are subject to rapid hydrolysis in the presence of trace amounts of water in. the reaction medium, which contrasts the stability of nonfunctionalized Ni(II) alkyls toward water. Exposure of 1 to vinyl acetate (VA) affords the kinetic 1,2-insertion product [(N boolean AND O)Ni(CH2CH2OC gamma'(O)CH3)(PMe3)] (5) at temperatures T >= -10 degrees C, which rearranges into the thermodynamically favored 2,1-insertion product [(N boolean AND O)Ni(CH(CH3)OC(O)CH3)(PMe3)] (6). NMR data and ab initio calculations suggest a Ni(II)center dot center dot center dot O=C-gamma' interaction in 6. 5 decomposes via beta-acetate elimination to yield ethylene and Ni(II) acetate species. Notably, VA does not undergo observable nickel-carbon bond insertion with 3, but reacted with Ni(II) hydride species in equilibrium with 3 to yield 5* which is subject to rapid decomposition via beta-acetate elimination.