Isomerization of the osmium-tellurium cluster Os-3(mu-TeR)(2)(CO)(10): a kinetic and computational study

摘要

The kinetics for the isomerization of the 50e cluster Os-3(mu-TeTol-p)(2)(CO)(10) (3), where the tellurides bridge two different Os-Os edges, to one in which the tellurides bridge the same open Os center dot center dot center dot Os edge (4) have been measured experimentally by H-1 NMR spectroscopy. The determined activation parameters are Delta H-double dagger = 77 +/- 9 kJ mol(-1) and Delta S-double dagger = -12 +/- 28 J mol(-1) K. The conversion of 3 to 4 has been computationally investigated by electronic structure calculations using the model compound Os-3(mu-TeMe)(2)(CO)(10). The computed isomerization pathway is consistent with the kinetic data and the thermodynamic preference for the product stereoisomer that possesses a slipped, eclipsed conformation for the two p-tolyl groups.