Oxidation potential of benzylferrocenes and related compounds: effects of the ortho-methoxy substituent in the phenyl group

• Published in: Journal of organometallic chemistry 2000-04, Vol.601 (2), p.246-252
• Main Authors: Asahara, Masahiro, Natsume, Satoko, Kurihara, Hideaki, Yamaguchi, Takuya, Erabi, Tatsuo, Wada, Masanori
• Format: Article
• Language: English
• Subjects: Benzylferrocenes; Ferrocenyl derivatives; o-Methoxyphenyl; Oxidation potential; X-ray crystal structure
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(00)00075-9

Oxidation potentials of some ferrocenyl derivatives of type Fc-CHΦOH, FcCΦΦ′OH, FcCH 2Φ, FcCHΦΦ′ [Fc=Fe(η 5-C 5H 5)(η 5-C 5H 4); Φ, Φ′=2,4,6-(MeO) 3C 6H 2, 2,6-(MeO) 2·C 6H 3, 2,5-(MeO) 2·C 6H 3, 2,4-(MeO) 2·C 6H 3, 2-MeOC 6H 4, 4-MeOC 6H 4, C 6H 5] were measured in acetonitrile. All of them exhibited a reversible one-electron oxidation–reduction wave based on the ferrocene–ferrocenium redox couple with a wide range of shift. Compounds having ortho-methoxy groups showed lower redox potentials than those of compounds having para-methoxy groups. The X-ray crystal structure of FcCHΦ 2 a showed that the ortho-methoxy oxygens were situated very close to the central carbon, and there is a possibility that one of the oxygen lone-pairs interacts with the antibonding orbital of CFc σ-bond. Some other possibilities are also discussed.