Cobalt tetracarbonyl hydride dicobalt octacarbonyl

Certain of the properties of cobalt tetracarbonyl hydride have been summarized previously.4 The pure compound decomposes thermally by a second-order process5 to hydrogen and dicobalt octacarbonyl. The compound is strongly... 

Co(CO)4K Cobalt tetracarbonyl hydride, potassium salt, 2 238 [Co(CO)4]2 Dicobalt octacarbonyl, 2 238, 242 6 190, 194 [Co(CO)4]2[Co(C6H5N)6] Cobalt tetracarbonyl hydride, hexa-pyridinecobalt(II) salt, 5 192 [Co(CO)4]2[Ni(C,2H8N2)3] Cobalt tetracarbonyl hydride, tris-(1,10-phenanthroline)nickel-(II) salt, 5 193n., 195 [Co (C204) 3JK3 Potassium trioxa-latocobaltate(III), 1 37 [Co(C5H5N)a][Co(CO)4]2 Cobalt tetracarbonyl hydride, hexa-pyridinecobalt(II) salt, 5 192 Co(C5H702)3 Cobalt(III) acetyl-acetonate, 6 188... 

The alkali salt of cobalt tetracarbonyl hydride can best be prepared by the absorption of carbon monoxide in an alkaline cobalt(II) cyanide suspension. Treatment of this solution with nitric oxide yields the volatile cobalt nitrosyl tricarbonyl/ while treatment with acid yields the volatile cobalt tetracarbonyl hydride. At room temperature, the latter compound decomposes into hydrogen and the nonvolatile dicobalt octacarbonyl, [Co(CX))4]2. 

Cobalt tetracarbonyl hydride cannot be preserved at room temperature except at pressures that would burst the usual glass sample tube. However, small quantities of the material as a yellow vapor will remain in equilibrium with hydrogen and the solid dicobalt octacarbonyl. 

The resulting Fischer-Tropsch process led to both alkanes and alkenes from the reduction of carbon monoxide (CO) by hydrogen (H2) over a cobalt catalyst (which is a mixture of dicobalt octacarbonyl [Co2(CO)8] and cobalt tetracarbonyl hydride [HCo(CO)4] and which is used at temperatures over 120°C and pressures above 200 atm), that is,... 

E. Hydroformylation and related carbonylation reactions Treatment of olefins with carbon monoxide and hydrogen under pressure and in the presence of dicobalt octacarbonyl gives mainly aldehydes or ketones. Alcohols and paraffins are formed as by-products. The hydroformylation of olefins to aldehydes is of considerable industrial importance. The prediction that cobalt tetracarbonyl hydride was a catalyst in these reactions [93, 94] has been amply verified for example the stoicheio-metric hydroformylation of 1-pentene by HCo(CO)4 proceeds at room temperature giving isomeric alddiydes [95]. It has been shown that HCo(CO)4 is formed under the hig pressure (100 atm. 1 1 H2 CO) and temperature (100-300°) conditions used in hydroformylation reactions [95, 96]. 

Cool the reactor to —196° and remove the noncondensable materials by pumping. Allow the reactor to warm to 0° and remove the excess trifluorosilane, tetracarbonyl(trifluorosilyl)-cobalt, and any cobalt carbonyl hydride formed by pumping the volatile products through a — 78° (Dry Ice-acetone mixture) trap into a —196° trap. A dark residue will remain in the reactor consisting of unreacted dicobalt octacarbonyl and decomposition products. Unreacted trifluorosilane will be in the —196° trap. 

Cobalt hydrocarbonyl also readily reduces acylcobalt tetracarbonyls, producing aldehydes and cobalt octacarbonyl (4). In this reaction, as in the hydrogen reduction, carbon monoxide is an inhibitor. The reaction probably involves the addition of cobalt hydrocarbonyl to an acylcobalt tricarbonyl followed by a hydride shift from cobalt to carbon, producing aldehyde and dicobalt heptacarbonyl. 

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