Nitrogen reactions with metal cations

It is thought that the function of the glue or gelatin is to combine with very slight traces of heavy metal cations, for example Cu, which are known to catalyse the nitrogen-forming reaction. 

A chiral pyrrolizidine (53) catalyses asymmetric Baylis-Hillman reactions. Important structural features include an accessible nitrogen lone pair and a strategically placed hydroxy group the latter may also interact with alkali metal cations, which catalyse the reaction. 

As known (Addison and Logan 1964), anhydrons nitrates exhibit oxidizing properties. Their oxidizing activity increases from ionic nitrates with alkali and alkali-earth metal cations to covalent nitrates with transient metal cations. Oxidation reactions result in the formation of nitrogen-containing oxides. Depending on the kind of a nitrate salt and reaction conditions, one of these oxides can be predominant. Organic snbstrates can evidently serve as reductant. 

The building block [Au(CN)2] has been revealed as a versatile unit in the formation of heteronuclear arrays which, in some cases, display unusual and interesting luminescent properties, such as vapochromic behavior. In many of these complexes the cyanide group uses the carbon and nitrogen ends as Lewis bases able to coordinate two different metal cations (i.e., Au-CN-M) [82-86]. These ideas may be illustrated by the reaction of K[Au(CN)2] with MX2 salts (M = Cu, Ni, Co, Mn ... 

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