Nickel tetracarbonyl properties

We recognized that the isoelectronic hydrides H2Fe(CO)4 and HCo(CO)4 behaved as pseudo-nickel tetracarbonyls (hydride displacement principle). Moreover, manganese pentacarbonyl hydride (VII, 11), on which we later worked in Munich, was similar in many physical properties to iron pentacarbonyl, leading us to postulate a Drawing-in of the hydrogen... 

While Mond was aware of the unusual properties of nickel tetracarbonyl, he had for a long time... no suspicion that this substance... should ever become available for industrial purposes . But the longer he and his... 

Properties Mobile, yellow liquid. D 1.466 (18C), bp 102.8C (749 mm Hg), decomposes at 200C, mp -21C, flash p 5F (-15C). Evolves carbon monoxide on exposure to air or to light. Soluble in nickel tetracarbonyl and most organic solvents soluble with decomposition in acids and alkalies insoluble in water. 

The lack of any knowledge on the structure and bonds of these compounds was responsible for the poor results. In fact, when tetracarbonyl-nickel was first prepared, Werner s theory had not as yet been postulated, and even later the theory was not extended to the carbonyls because they were considered anomalous compounds, owing to their chemical and physical properties. 

At variance with the easy accessibility of Ni(CO)4, the corresponding tetracarbonyls of palladium (0) and platinum (0), Pd(CO)4 and Pt(CO)4, have been identified only spectroscopically (IR) at low temperature, both being prepared by vaporization of the metal followed by reaction with CO in a solid matrix at about 20 K. These compounds decompose at higher temperature. Table 2 shows the IR spectroscopic properties of the tetracarbonyls of nickel, palladium, and platinum, as obtained by vaporization of the corresponding metal, measured under the same experimental conditions. The compounds show one carbonyl stretching vibration, as expected for the tetrahedral geometry. The values of v>co and the C-0 force constant of Pd(CO)4 are higher than those of both Ni(CO)4 and Pt(CO)4 (see Section Attempts have... 

Equally strong interactions do not necessarily have to exist in square planar binuclear complexes, a problem that is of great concern to us. There is very little information in the literature about the synthesis or properties of such materials. Possibly planar binuclear systems are the ethanetetraaldehyde-bridged nickel aminotroponeiminato complexes, 2, reported by Trofimenko (26). The preparation of the bisimidazole complexes 3 was described (27) of which the tetracarbonyl derivatives might well be the very first example of completely planar binuclear transition metal compounds that are capable of extended interactions. 

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