Syntheses, characterization and electrochemical and spectroscopic properties of ruthenium-iron complexes of 2,3,5,6-tetrakis(2-pyridyl)pyrazine and ferrocene-acetylide ligands

摘要

Heterodimetallic Ru-Fe complexes [(tppz)(PPh3)(2)RuL](ClO4) (L = C equivalent to CFc, [1](ClO4); CuC-C6H4-C equivalent to CFc), [2](ClO4); C equivalent to C-C6H4-C6H4-C equivalent to CFc, [3](ClO4)) were synthesized by the reactions of [(tppz)(PPh3)(2)RuCl](ClO4) (tppz = 2,3,5,6-tetrakis(2-pyridyl) pyrazine) with ferrocence-acetylide ligands and characterized by ESI-MS, and H-1 and P-31 NMR spectroscopies. The structure of [1](PF6) was determined by X-ray crystallography. The electrochemical studies show that compounds [1](ClO4)-[3](ClO4) possess two widely separated anodic peaks, ascribable to one-electron oxidation of Fc and Ru-II, respectively. This assignment is further corroborated by the results of UV-vis-NIR, XPS, and theoretical calculation studies. Compound [1](ClO4) exhibits significant Ru. Fe metal-metal interactions across the Ru-C equivalent to C-Fc backbone. As revealed by electrochemical, spectroscopic and theoretical computational studies, one-electron oxidized species [1a](ClO4)(2) is between the electronically delocalized and valence-trapped state and shows a typical Robin-Day class II mixed-valence behavior.