Synthesis, characterization and structure of the ethylene-bridged dimer [Cp(CO)(2)RuCH2CH2Ru(CO)(2)Cp] and comparison of its reactivity with that of [Cp(CO)(2)RuCH2CH3] and [Cp(CO)(2)R(CH2)(5)Ru(CO)(2)Cp]: Models for Fischer-Tropsch surface intermediates

The diruthenium ethylene-bridged complex [Cp(CO)(2)RuCH2CH2Ru(CO)(2)Cp] (Cp=eta(5)-C5H5) (1) has been prepared by two different synthetic routes. The complex has been fully characterized by IR, H-1 and C-13 NMR spectroscopy, mass spectrometry and X-ray crystallography. The complex crystallizes in the triclinic space group <P(1)over bar> (Z = 1) with a = 6.060(1), b = 6.990(2) and c = 10.097(1) Angstrom and alpha = 85.30(1), beta = 76.86(1) and gamma = 74.46(2)degrees. The structure was refined to R(F) = 0.029 and shows that the CpRu(CO)(2) units are centrosymmetrically bonded to each end of the ethylene fragment in a trans arrangement. The use of 1 as a model for ethylene on a metal catalyst surface is explored and some reactivity studies of 1 are described. Some reactions of [Cp(CO)(2)RuCH2CH3] (2) are also reported and compared with the reactions found for 1. A reaction sequence of the pentamethylene-bridged compound [Cp(CO)(2)Ru(CH2)(5)Ru(CO)(2)Cp] (3) is found to give a high yield of 1-pentene.