Carbonyl chromium complexes thermal

The thermal reactions of [Et2NCH2CN] with chromium, molybdenum, tungsten, manganese, and iron carbonyls gave complexes of the type... 

Catalysts suitable specifically for reduction of carbon-oxygen bonds are based on oxides of copper, zinc and chromium Adkins catalysts). The so-called copper chromite (which is not necessarily a stoichiometric compound) is prepared by thermal decomposition of ammonium chromate and copper nitrate [50]. Its activity and stability is improved if barium nitrate is added before the thermal decomposition [57]. Similarly prepared zinc chromite is suitable for reductions of unsaturated acids and esters to unsaturated alcohols [52]. These catalysts are used specifically for reduction of carbonyl- and carboxyl-containing compounds to alcohols. Aldehydes and ketones are reduced at 150-200° and 100-150 atm, whereas esters and acids require temperatures up to 300° and pressures up to 350 atm. Because such conditions require special equipment and because all reductions achievable with copper chromite catalysts can be accomplished by hydrides and complex hydrides the use of Adkins catalyst in the laboratory is very limited. 

The complex [Cr(CO)5GeNR2 ] is obtained in 38% yield when bis(2,2,6,6-tetra-methylpiperidinato)germanium is combined with a chromium carbonyl derivative. Similarly, Ge[N(SiMe3)2] promotes the elimination of CO2 from a platinum precursor under thermal conditions in 64% yield ll... 

Group 6 metal (chromium, molybdenum, tungsten) carbonyls trapped in zeolites have been found to undergo partial thermal decomposition to produce M(CO)3 species which react with phosphines, polyolefins, and arenes to form the expected complexes, e.g. ( / -C6H6)Cr(CO)3 [210]. 

In the case of metal-containing PAN the spectral picture is qualitatively the same (as compared with the initial PAN) however, ftie nature of tiie metal carbonyl introduced into the polymer somewhat influences the character of file transformations. By FTIR, ESCA and ESR, it was found that under thermal treatment in air at 220 C, first metal carbonyl complexes decompose (by FTIR spectroscopy tungsten and molybdenum carbonyl complexes lose carbon monoxide at 150-160 C, chromium carbonyl ones at 110°C) and chromium, molybdenum and tungsten oxide particles form. 

Cyclopentadiene iron tricarbonyl has been prepared and decomposes thermally to the binuclear carbonyl [a -C5H5Fe(CO)2]2 [26o]. The binuclear iron complex may further react with cyclopentadiene or thermally decompose ( 200°) [27, 28] to give ferrocene. Monosubstituted ferrocenes may be prepared by the former reaction [27]. Chromium hexacarbonyl and cyclopentadiene at 280-350° react to give chromocene [29] the reaction is reversible since treatment of chromocene with carbon monoxide under pressure affords chromium hexacarbonyl, together with intermediate products such as [jr-CpCr(CO)3]2, [jr-Cp2Cr][3r-CpCr(CO)3] and, when hydrogen is also present, the cyclopentenyl complex jr-CsH5CrC5H7(CO)2, 4.1, is formed [30, 31, 32]. 

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