Trans-Cis Isomerisation of Bis(dioxolene)bis(pyridine)Ruthenium Complexes

摘要

The isomerization of trans to cis bis(3,5-di-t-butylbenzo semiquinonato) bis(R-Pyridine) ruthenium, Ru(R-Py)2(DTBDiox)2, is induced by warming with an excess of R-pyridine, where R = 3-chloro, 4-methyl, 4-phenyl or 4-butyl. The rates of these reactions, for the species with R-Py = 3-chloropyridine, were monitored in o-dichlorobenzene by uv-visible spectroscopy, against varying 3-chloropyridine and varying trans-Ru(3-ClPy)2(DTBDiox)2 concentration. The data were found to obey first order kinetics. A plot of 1/kobsd vs. 3-chloropyridine is linear with a positive intercept. A dissociative mechanism is proposed for the isomerisation reaction. The activation parameters were determined for the specific case of R-Py = 3-chloropyridine. Electronic and electrochemical features of these species are briefly discussed.