Synthesis, Structure and Fluxional Behaviour of Sulfido-Capped Triruthenium Clusters Containing a Bridging 1,1’-Bis(diphenylphosphino)ferrocene Ligand

The reactivity of dppf-bridged triruthenium [Ru3(CO)10(µ-dppf)] with three thiourea derivatives namely N,N´-diisopropylthiourea, N,N´-dimethylthiourea and tetramethylthiourea has been examined. The reaction of [Ru3(CO)10(µ-dppf)] with N,N´-diisopropylthiourea or N,N´-dimethylthiourea affords [Ru3(CO)6κ1-SC(NHR)2(µ-dppf)(µ3-S)2] (1, R = CHMe2; 2, R = Me) that contains an intact thiourea ligand coordinated to a single ruthenium atom using the sulfur atom. The previously reported [Ru3(CO)7(µ-dppf)(µ3-S)2] (3) is also isolated as the minor product from the reaction with N, N´-dimethylthiourea. Both 1 and 2 furnishes 3 upon thermolysis in boiling toluene as confirmed by control experiments. In contrast, similar reaction between [Ru3(CO)10(µ-dppf)] and tetramethylthiourea furnishes [Ru3(CO)5(µ-CO)µ-η1,κ1-COPh(µ-PhPFcPPh2)(µ3-S)] (4) and [HRu3(CO)7(µ-OH)(µ-dppf)(µ3-S)] (5) together with small amount of 3. All the new clusters are fluxional in solution which has been probed by VT NMR experiments and their molecular structures have been established by single-crystal X-ray diffraction analysis.