Observation of Linkage Isomerization in W(CO)₅(2,5-Dihydrofuran)

Abstract

UV photolysis of a cyclohexane solution of W(CO)6 in the presence of 2,5-dihydrofuran (DHF) yields W(CO)5(η1(O)-DHF) with a bimolecular rate constant on the order of 107 L mol-1 s-1. Time-resolved IR (TRIR) absorption spectroscopy is used to monitor the consequent intramolecular isomerization to W(CO)5(η2-(C,C)-DHF), which occurs with a rate constant on the order of 1−10 s-1 at 20−60 °C; activation parameters for the isomerization are determined to be ΔH⧧ = 17.3 ± 0.3 kcal/mol and ΔS⧧ = 0.9 ± 0.9 eu.