Kinetic investigation of a ruthenium metathesis catalyst

The complex [(IMesH2)(PPh2Cy)Cl2Rudouble bond; length as m-dashCHPh] was synthesised and shown to be an active catalyst in ring-closing metathesis of a diallylmalonate. Its phosphine exchange was investigated in C6D6 using magnetisation transfer 31P NMR spectroscopy and it was found to operate via a dissociative mechanism with k353 = 4.1 ± 0.9 s−1, ΔH‡ = 84 ± 10 kJ mol−1 and ΔS‡ = 4 ± 28 J mol−1 K−1.