Nickel tetracarbonyl reduction

Nickel tetracarbonyl is made by passing carbon monoxide over finely divided nickel at 50 to 100°C. (The finely divided nickel is obtained from reduction of nickel oxide by hydrogen below 400°C.)... 

Nickel Tetracarbonyl, Ni(CO)4, is obtained when carbon monoxide is passed over metallic nickel 3 in a finely divided condition, such as is obtained by the reduction of nickel oxide in hydrogen at 400° C., the best temperature for obtaining the carbonyl being about 30-50° C. The carbonyl is condensed in a cooled vessel. The reaction may be advantageously carried out under a pressure of 2-100 atmospheres of carbon monoxide, in which case the temperature may be raised even to 250° C. without fear of decomposition.4... 

Yields are moderate to good, the conditions mild (35eC, 1 atmos.) but as yet the approach is restricted to the 4-methyl derivatives (341). Nickel tetracarbonyl is useful as a catalyst for the reductive... 

A species formerly known as Ni(o-phen)(CO)2 and assumed to be a substitution product of nickel tetracarbonyl is now believed to be the salt [Ni(o-phen)3][Ni2(CO)6] 33). Reduction of nickel tetracarbonyl with sodium or other very active metals in liquid ammonia is believed first to produce the [NijCCO) ] " ion, which is reported to react with liquid ammonia to form a red unstable ammoniate of the hydride H2Ni2(CO)6 58, 59). 

Salts of the dianion [Ni6(CO)12]2- have been prepared by reduction of tetracarbonyl nickel under a variety of experimental conditions with yields seldom exceeding 40 to 50%.1,2... 

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