AMPLIFICATION OF METAL-TO-METAL COMMUNICATION IN THE RUTHENIUM(IV)-RUTHENIUM(III) MIXED-VALENCE STATE OF BINUCLEAR BETA-DIKETONATORUTHENIUM COMPLEXES BY INSERTING THIOPHENE AND ANTHRACENE UNITS INTO ACETYLENE LINKERS

摘要

Two new binuclear beta-diketonatoruthenium(III) complexes linked by bis(ethynyl) thiophene (1) and bis(ethynyl) anthracene (2) were prepared. Both the binuclear complexes exhibited two well-defined one-electron oxidation steps and two overlapping one-electron reduction steps in triangular-wave voltammograms in dichloromethane medium at 25 degrees C. These reduction and oxidation steps can be assigned to the reduction and the oxidation of the central metals. The difference in reversible half-wave potentials between the first and the second oxidation steps was 175 and 183 mV for 1 and 2, respectively. The comproportionation constants for the Ru-IV-Ru-III mixed-valence state of 1 and 2 were larger by a factor of about 10 than that of an analogous binuclear complex linked by three acetylene linkers. [References: 16]