Showing papers by "Thomas F. Koetzle published in 1980"

Isolation and characterization of penta-.mu.2-carbonyl-decacarbonylpentarhodate(1-): a key product in rhodium carbonyl chemistry

Abstract: The species, (Rh/sub 12/(CO)/sub approx.34/)/sup 2 -/ has been reformulated as (Rh/sub 5/(CO)/sub 15/J); and the pentanuclear cluster was obtained by starting from Rh/sub 4/(CO)/sub 12/ and the (Rh(CO)/sub 4/J)/sup -/ anion. At low temperature (-78/sup 0/C), reaction of (Rh/sub 12/(CO)/sub 30/)/sup 2 -/ with carbon monoxide (laton P) in THF led to slow precipitation of Rh/sub 6/(CO)/sub 16/ in such a way that the resultant equilibrium shifted toward formation of the labile species. The x-ray structural analysis showed the anionic species to be (Rh/sub 5/(CO)/sub 15/)/sup -/. The (PPN)/sup +/ (Rh/sub 5/(CO)/sub 15/)/sup -/ salt has been characterized by single-crystal x-ray diffraction techniques. The structure of the (Rh/sub 5/(CO)/sub 15/)/sup -/ anion in the crystalline state is illustrated. The present structure is an example of a trigonal-bipyramidal cluster with 76 valence electrons. At -80/sup 0/C in perdeuterioacetone, the 25- and 90-MHz /sup 13/C NMR spectra of the (Rh/sub 5/(CO)/sub 15/)/sup -/ anion are identical and are the same as that previously reported for (Rh/sub 12/(CO)/sub approx.34/)/sup 2 -/. It was observed that the slow decomposition of (Rh/sub 5/(CO)/sub 15/)/sup -/ species in THF solution under nitrogen takes place. The equation appears to be a key reaction involved in themore » reported equilibrium between (Rh/sub 12/(CO)/sub approx. 34/)/sup 2 -/ and (Rh/sub 12/(CO)/sub 30/)/sup 2 -/. 3 figures. (DP)« less