Hydrogenation catalysts Arene chromium complexes

Hydrogenation catalysts Arene(tricarbonyl)chromium complexes, 19... 

Hydrogenation by (7r-arene)chromium tricarbonyl complexes has also been shown to convert dienes to c/s-monoenes, but these catalysts appear to add to conjugated dienes in a 1,4 manner (73, 74). 

Bisbenzene chromium has been found to be a catalyst for the polymerization of ethylene at 200°-250°C. Chromium metal was postulated as the active catalyst in the system 410, 411). The polymerization of ethylene by bisarene chromium(I) salts in the presence of (i-Bu)3Al has also been studied (406). The catalytic activity was found to be a function of both the arene and the anion present. When bisarene chromium complexes are air oxidized in water, hydrogen peroxide is produced ... 

Chromium, Molybdenum, and Tungsten.— Applications of benchrotrenes and analogous Mo complexes in organic synthesis have been reviewed, and studies of the use of such complexes as catalysts for alkene polymerization, isomerization, and hydrogenation have been reported. Decomplexation of the arene ligand of benchrotrenes can be conveniently effected by treatment with boiling pyridine. Spectroscopic studies of ( -arene)M(CO)3 complexes have been described, including discussions of carbonyl vibrational spectra, ih 2 and... 

Chromium. The complexes Cr(arene)(CO)s are highly selective catalysts for the hydrogenation of dienes to monoenes. A recent study concentrated on the reduction of methyl hexa-2,4-dienoate (sorbate), and the mechanism was found to be similar to that for reaction with iron-carbonyl catalysts. It does not involve rate-determining loss of the arene to give Cr(CO>3 as the active species, as suggested earlier for a different catalytic system, but rather the arene becoming bi- or uni- rather than ter-dentate, so that the diene can be co-ordinated ... 

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