Metal atom reactions with ammonia

For over 15 years we have conducted research utilizing metal atoms in low temperature spectroscopic and synthetic studies at Rice University.8 Our synthetic work was started in the late 1960s with the work of Krishnan, on lithium atom reactions with carbon monoxide, extended by Meier- in his studies of lithium atom reactions with water and ammonia and expanded over the next several years to include metal atom interactions with HF, H2O, H3N, H4C, and their hundreds of organic analogs—RF, R2O, ROH, R3N,. . . H3N, R4C, R3CH, etc. A most exciting aspect of... 

Some enzymes require cofactors to activate catalysis. Typical cofactors are metal atoms, ammonia, and small organic molecules that associate with the enzyme and help to structure the catalytic site. To conduct an enz5anatic reaction, the necessary cofactors must be suppUed along with the substrate and the enzyme. In cell metabolism, a variety of these cofactors act in conjunction with inhibitors to control the metabolic rate. 

Water, in its reaction with the alkali- and alkaline-earth metals, resembles ammonia, but the complexes with the halides of the platinum metals are different. The water molecule has two lone pairs of electrons, but these pairs seem to be less active in complex formation. There are many cases in which from the magnetic moment it can be concluded that the hydrates are still ionic, whereas in the corresponding NH3 complex there is covalency, the NH3 molecules sharing their lone electron-pairs with the metal atom. 

K2[Fe(NO)2(CN)2]. My former co-worker R. Nast (83) showed that the reaction of carbon monoxide with K4[Ni2I(CN)6] and K4[Ni°(CN)4] in liquid ammonia gave nickel cyanocarbonyl complexes with monovalent and zero-valent metal atoms. The isoelectronic hexacyanoiron(III) or tetra-cyanonickel(II) complexes correspond to the cyanocarbonyls [Feu(CN)5 CO]3-, [Ni (CN)3CO]2-, or [Ni°(CN)2(CO)2]2-. Cobalt is analogous to nickel in forming the complex [Co(CN)3CO]2-. According to our earlier work, [Fe"(CN)5CO]3- and [Fem(CN)6]3- are isosteric (87). Other structural investigations were concerned with tetracyano and tetracarbonyl complexes (88). 

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