Nickel complexes cyano

Structural models, which are synthesized to imitate features of the proposed structure of the active site. These may be used to demonstrate the chemical conditions, which allow such structures to exist, to investigate their chemical properties and to give a better understanding of the spectroscopic characteristics of the native proteins. Examples of these include the mixed carbonyl/cyano complexes of iron, used to verify the infrared spectra to the hydrogenases (Fig 7.4) (Lai et al. 1998) and the nickel-thiolate complexes which have low redox potentials like the hydrogenases (Franolic et al. 1992). 

Only a limited number of cyano and isocyano complexes and mixed carbonyl, nitrosyl and phosphine cyano complexes of nickel(O) have been described so far.16... 

No cyano complexes of nickel(III) and nickel(IV) have been isolated to date. 

In recent years there has been considerable interest in the reactions of nitriles in the coordination sphere of metal ions. Breslow et al.312 first reported that the hydrolysis of 2-cyano-l,10-phenanthro-line to the corresponding carboxamide is strongly promoted by metal ions such as copper(II), nickel(II) and zinc(II). Base hydrolysis of the 1 1 nickel complex is 107 times faster than that of the uncomplexed substrate. The entire rate acceleration arises from a more positive value of AS. Somewhat similar effects have been observed for base hydrolysis of 2-cyanopyridine to the corresponding carboxamide. In this case rate accelerations of 109 occurred with the nickel(II) complex.313... 

A tripod-type Schiff-base ligand, (127), was prepared by a 3 1 condensation reaction of 2-phenyl-4-formylimidazole in methanol.204 In two nickel(II) complexes, the screw coordination arrangement of the tripod ligand (127) around the metal ion induces chirality, resulting in a A (clockwise) or a A (anticlockwise) enantiomer.204 A multifunctional tripodal ligand possessing two different functionalities, such as pyridine and cyano moieties, (128), has been prepared by the reaction of 2-aminomethylpyridine, excess acrylonitrile, and glacial acetic acid. 

Nickel(III) complexes, 5, 287-300 amides, 291 amines, 290 amino acids, 290 arsines, 296 cyano,290... 

Cyanide is determined by measuring the atomic absorption of either silver, copper, or nickel in their corresponding cyano complexes, Ag(CN)2, Cu(CN)3, and Ni(CN)4. The most sensitive of these is based on the silver complex. 

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