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Mechanism and Activation Parameters for the κO to μ,κ2O,O′ Bonding Mode of the Maleic Acid Ligand on an Osmium Carbonyl Cluster

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journal contribution
posted on 08.08.2011, 00:00 authored by Rakesh Ganguly, Weng Kee Leong
The reaction of maleic acid and [Os3(CO)10(NCCH3)2] afforded initially the cluster [Os3(μ-H)(CO)10(O2CCHCHCO2H)(CH3CN)], in which the maleic acid was κO bonded. This slowly converted to [Os3(μ-H)(CO)10(μ-O2CCHCHCO2H)], in which the ligand adopted the more usual μ,κ2O,O′ bonding mode. The conversion was followed by monitoring the metal hydride resonance in the 1H NMR spectrum, and analysis of the data yielded ΔH = 110 ± 3 kJ mol–1 and ΔS = 14 ± 10 J mol–1 K–1 for this process, thus suggesting an ID mechanism. The calculated values are in good agreement with the experimental values.