Role of B(C6F5)3 in activating the nickel-methyl complex (η-C5H5)Ni(CH3)(PPh3) to initiate the vinyl polymerization of norbornene |
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| Authors: | Takeo Yamamoto Chie Shikada Shojiro Kaita Tardif Olivier Yooichiroh Maruyama Yasuo Wakatsuki |
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| Affiliation: | aCollege of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550, Japan;bRIKEN (The Institute of Physical and Chemical Research), Hirosawa 2-1, Wako, Saitama 351-0198, Japan;cJSR Corporation, Kawajiri-cho 100, Yokkaichi, Mie 510-8552, Japan |
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| Abstract: | The Ni-methyl complex (η5-C5H5)Ni(CH3)(PPh3) (1) reacted with B(C6F5)3 to give an unstable contact ion-pair complex with a μ-methyl bridge between the Ni and B atoms. Formation of the B-CH3 bond was confirmed by the reaction of this complex with PPh3 to give [(η5-C5H5)Ni(PPh3)2][B(CH3)(C6F5)3] which was structurally characterized. Spontaneous decomposition of the contact ion-pair complex yielded (η5-C5H5)Ni(C6F5)(PPh3) which is very stable and does not show any reactions with norbornene with or without added B(C6F5)3. 19F NMR study showed that the polynorbornene obtained by the catalysis of 1/B(C6F5)3 system has the C6F5 end-group. A series of reactions, which includes CH3/C6F5 exchange between the Ni and B centers with concomitant dissociation of PPh3 to accept coordination of a norbornene monomer, is proposed as the route to active species that can initiate vinyl polymerization of norbornene. |
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| Keywords: | Polymerization Norbornene Nickel Co-catalyst Activation |
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