Electronic structure of Ru3(CO)6(CH3C?CHCH = NC3H7-i)2 as indicated by UV-photoelectron spectroscopy and DV-X? quantum mechanical calculations

The electronic structure of a novel trinuclear open (or acyclic) cluster of ruthenium [Ru3(CO)6(CH3C?CHCH?NC3H7-i)2], isolobal with ruthenocene, has been investigated by combining He I/He II gas phase UV photoelectron spectroscopy and Hartree-Fock-Slater first-principle discrete variational (DV-)X? calculations. The derived bonding scheme emphasizes the leading role played by a 3-center-2-electron interaction between the Ru atoms in determining the stability of the bent open metal core, in spite of the absence of any ligand bridging the peripheral ruthenium. Moreover, the bent arrangement of the open metal core has been calculated to be ca. 3 Kcal/mol more stable than the linear one.