Preparation of ruthenium(0) and osmium(0) cyclooctatetraene complexes

Four separate fluxional processes in (η6-cyclo-octatetraene)(η4-cyclo-octa-1,5-diene)osmium. A novel example of a metal [1,5] shift on a π-co-ordinated polyene ligand

“…For q6-cyclo-octatetraene complexes, octatetraene)(~4-l,5-cyclo-octadiene), ( l ) . 5 The 1H and l3C fav 0s…”

“…spectrum of Os(r16-C8H8)(r14-CsH12) in [2H8]toluene at -93 "C shows that the molecule possesses no symmetry, and a low energy twitch occurs with AG* 8.9 kcal mol-1 producing an apparent plane of symmetry; at higher temperature, the cyclo-octatetraene and cyclo-octadiene ligands mutually rotate, with AG* ca. 11.5 kcal mol-1, exchange commencing at room temperature on the cyclo-octatetraene ring by a novel [ 1,5] shift mechanism with A G = 16.5 kcal mol-1 and at slightly higher temperature a general shift of the metal around the cyclo-octatetraene ring occuring with AG* ca. 19.5 kcal mol-1 (1 cal = 4.184 J).…”

“…0.1 s-1, while the pairwise exchange occurred at 12 s-1. The pairwise exchange is only explicable in terms of a [1,5] shift mechanism, with AGt 16.6 kcal mol-1.T Following the mechanism for the [1,3] shift observed in Cr(q6-C8H8)(Co)3, involving a 1--.$-q4intermediate, it is proposed that the [1,5] to the olefinic carbon atoms, and the CH2 signals at 6 31.0 (intensity 2), 29.1, and 28.2. Clearly, the molecule must be of low symmetry.…”

Narrowly dispersed silica supported osmium nanoparticles prepared by an organometallic approach: H2 and CO adsorption stoichiometry and hydrogenolysis catalytic activity

“…5 In view of the similar reactivity of silica supported Ru-and Os-nanoparticles in the Fischer-Tropsch reaction, the homologation of alkenes under H 2 or the hydrogenolysis of alkanes, 6,7 we considered the possibility of generating the corresponding silica supported Os nanoparticles by the same approach. Here, we report the preparation of silica supported Os NPs prepared from [osmium(0) (η 4 -1,5-cyclooctadiene)(η 6 -1,3,5,7-cyclooctatetraene)] Os(cod)(cot), 8 along with the determination of the nanoparticles H : Os surf. and CO : Os surf.…”

Ru(η6-1,3,5-cyclooctatriene)(η2-dimethyl fumarate)2: a novel, versatile zerovalent ruthenium complex with electron-deficient olefinic ligands

“…Especially, extensive efforts have been made towards the synthesis and elucidation of the reactivity of a versatile zerovalent complex, Ru(g 4 -cod) (g 6 -cot) (1) (cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene) and its derivatives, to date [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. During the course of a specific C-C bond forming reaction involving 1 as a precatalyst (Eq. (1)), we found that the unique dimerization of 2,5-nor-0022-328X/$ -see front matter Ó 2004 Elsevier B.V. All rights reserved.…”