NOVEL SYNTHESIS, SOLUTION STRUCTURE, DYNAMICS, AND PROTONATION OF H(MU-H)RU-3(CO)(11)

The reaction of the lightly stabilized cluster Ru-3(CO)(11)(NCCH3) wit h H-2 quantitatively affords H2Ru3(CO)(11), which is sufficiently stab le under an H-2 atmosphere to be characterized by H-1 and C-13 spectro scopy. In solution, the structure of the dihydride product is differen t from that previously reported, and it corresponds to a novel bonding scheme, intermediate between those of the two structures previously r eported for H2M3(CO)(11) species (M = Fe, Ru, Os). The stereochemical nonrigidity of the title compound is investigated by VT C-13 NMR spect roscopy, and an exchange mechanism involving edge hopping of the bridg ing hydride in concert with the motion of the carbonyl ligands is prop osed. The reactivity of the title compound with CF3COOH is also invest igated. At low temperature, the addition of the strong acid to the clu ster yields a reversible O-protonation at the bridging carbonyl site. When the temperature is raised, the formation of (mu-H)Ru-3(mu-eta(3)- OOCCF3)(CO)(10) is observed.