Pyrolysis of [Ru3(CO)10(dppe)]: activation of C?H and P?Ph bonds.: The crystal structure and dynamical behavior of [Ru4(CO)9(?-CO){?4?2-PCH2CH2P(C6H5)2}(?4?4-C6H4)]

The pyrolysis reaction of [Ru3(CO)10(dppe)], compound 1, in toluene yields as the main product [Ru4(CO)9(?-CO){?4?2-PCH2CH2P(C6H5)2}(?4?4-C6H4)], compound 2. The X-ray structure of 2 shows a benzyne group coordinated to a square of ruthenium atoms and a ?4?2-PCH2CH2PPh2 fragment. Variable-temperature NMR experiments showed three independent dynamic processes: a rotation of the benzyne group, CO migration and a twisting movement of the CH2?CH2 fragment. The thermolysis of [Ru3(CO)10(dfppe)], compound 3, (dfppe=1,2-bis(dipentafluorophenylphosphino)ethane, carried out under the same conditions, showed 3 to be stable.