M. Abla, Takakazu Yamamoto
Jun 15, 1999
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Influential Citations
10
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Journal
Bulletin of the Chemical Society of Japan
Abstract
Ligand exchange reactions of bis(1,5-cyclooctadiene)nickel(0), Ni(cod)2, with bpy, DMbpy, and TMbpy (bpy = 2,2′-bipyridine, DMbpy = 4,4′-dimethyl-2,2′-bipyridine, TMbpy = 4,4′,5,5′-tetramethyl-2,2′-bipyridine) in THF and DMF have been investigated kinetically. The reaction obeys the pseudo first-order kinetics, R = −d[Ni(cod)2]/dt = kobs[Ni(cod)2], with respect to the concentration of Ni(cod)2 in both the solutions. In THF, the kobs value linearly increases with [L] at a low concentration region of the exchanging ligand L; but it levels off at high concentrations of L and approaches a limiting value (e.g., about 1.0 × 10−4 s−1 at 25 °C). Addition of cod to the THF solution accelerates the exchange reaction. On the other hand, in DMF, the rate of the reaction (R) obeys the second-order rate law, R = k[Ni(cod)2][L], over a wide range of [L]. In DMF, the k value is independent of the concentration of cod added. Based on the kinetic results and NMR analysis, a reaction mechanism involving coordination of bpy,...