Electrochemical studies on (η5-C5H5)Ru(PPh3)(L)X(L= PPh3, pyridine; X =H, CI) and (η5-C5H5) Ru{P(OMe)3}2 CI in non-aqueous solvents

Abstract

The redox properties of a series of cyclopentadienylruthenium compounds, (η⁵-C₅H₅)Ru(PPh₃)(L)X(L= PPh₃, pyridine; X = H, Cl) and (η⁵-C₅H₅)Ru{p(OMe)₃}₂Cl, have been studied in different nonaqueous solvents (MeCN, THF, CH₂Cl₂). The ruthenium(II)/ruthenium(III) couple is observed in the potential range of + 0.05 V to + 0.70 V (vs SCE) depending upon the type of ligands and the solvent medium. The E<img src='http://www.niscair.res.in/jinfo/equation95.gif' border=0> values vary in the order THF> CH₂CI₂ > MeCN. While the couple is nearly reversible in MeCN, the electron transfer is sluggish (i.e., quasireversible) in other solvents. The E<img src='http://www.niscair.res.in/jinfo/equation95.gif' border=0> values follow the order: (η-Cp)Ru-{p(OMe)₃}₂Cl > (η-Cp)Ru(PPh₃)(py)Cl ≥ (η-Cp)Ru(PPh₃)₂Cl > (η-Cp)Ru(PPh₃)₂H- (η-Cp = η⁵-C₅H₅).