Nineteen-electron complexes

Astruc D. Nineteen-electron complexes and their role in organometallic mechanisms. Chem Rev 1988 88(7) 1189-1216. 

D. Astruc, Nineteen-electron Complexes and Their Role in Organometallic Mechanisms, Chem. Rev. 88, 1189-1216 (1988). 

There are ammoniates of PtCl2, of halides of other platinum metals and of cobalt and nickel, too, some of which have been mentioned before in, Section 50. The cobalt complexes clearly show the importance of the completed d shells for the stability of the complex. Non complex compounds of trivalent cobalt are very unstable. Solutions of divalent cobalt in ammonia, however, are readily oxidized by air, because the NH3 complex of trivalent cobalt Co(NH3)6 3+ClT has eighteen electrons used in bond formation, whereas the ion Co(NH3) + would have nineteen electrons. 

Stiegman AE, Tyler DR. Reactivity of seventeen- and nineteen-valence electron complexes in organometallic chemistry. Comments Inorg Chem 1986 5(5) 215—245. 

Nineteen-electron organometallic complexes are rare and generally quite reactive. Recently, the ligand substitution kinetics have been studied for the following system ... 

Ion—molecule reactions in olefins, especially in those higher than ethylene, are characterized by their complexity due to multiple products from a given reactant and multiple reactants for a given product. Thus, even restricting ourselves to reactions of parent ions with parent molecules, at least five reactions in propene, eight reactions in 1-butene, and nineteen reactions in 1-pentene are observed. Occurrence of several primary fragment ions in ordinary electron impact and radiolysis systems makes the situation more complicated. 

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