Reduction Reaction of the Copper(II) Complex Bearing 1,3-Di(pyridine-2-carboxaldimino)propane (pitn) by Decamethylferrocene in Acetonitrile

• Published in: Journal of solution chemistry Vol. 43; no. 9-10; pp. 1479 - 1486
• Main Authors: Yamada, Atsutoshi, Watanabe, Yuki, Noda, Kyoko, Itoh, Sumitaka, Ishihara, Koji, Inamo, Masahiko, Hassan, Refat Moustafa, Takagi, Hideo D.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.10.2014
• Subjects: Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Geochemistry; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Oceanography; Physical Chemistry; Cyclic voltammetry; Decemethylferrocene; Rate constants; Cu(II)(pitn); Acetonitrile
• ISSN: 0095-9782; 1572-8927
• DOI: 10.1007/s10953-014-0154-7

The reduction reaction of the Cu(II)–pitn complex (pitn = 1,3-di(pyridine-2-carboxaldimino)propane) by decamethylferrocene [Fe(Cp*) 2 ] was examined in acetonitrile. The observed pseudo-first-order rate constants exhibited saturation kinetics with increasing excess amount of [Fe(Cp*) 2 ]. Detailed analyses revealed that the reaction is controlled by a structural change prior to the electron transfer step, rather than a conventional bimolecular electron transfer process preceded by ion pair (encounter complex) formation. The rate constant for the structural change was estimated to be 275 ± 13 s −1 at 298 K (∆ H * = 33.3 ± 1.0 kJ·mol −1 , ∆ S * = 86 ± 5 J·mol −1 ·K −1 ), which is the fastest among gated reactions involving CuN 4 complexes. It was confirmed by EPR measurement and Conflex calculations that the dihedral angle between the two N–N planes is significantly large (40°) in solution whereas it is merely 17.14° in the crystal.