Isomerization of the osmium–tellurium cluster Os3(μ-TeR)2(CO)10: a kinetic and computational study

Abstract

The kinetics for the isomerization of the 50e cluster Os₃(μ-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⋯Os edge (4) have been measured experimentally by ¹H NMR spectroscopy. The determined activation parameters are ΔH^‡ = 77 ± 9 kJ mol⁻¹ and ΔS^‡ = −12 ± 28 J mol⁻¹ K. The conversion of 3 to 4 has been computationally investigated by electronic structure calculations using the model compound Os₃(μ-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.