Dinitrogen complexes Subject

Since the first step of all of these reactions is dinitrogen coordination to either the surface of the catalyst or transition metal center of the complex, let us briefly discuss the nature and importance of the M-N2 interaction, and the possible coordination modes ofN2 to transition metal centers. These issues were the subjects of many discussions in the literature [10, 11] and it is commonly agreed that the interaction of the N2 molecule with transition metal centers facilitates the activation of the N=N triple bond the stronger the M-N2 interaction, the easier to break the N=N triple bond. 

Reduction of dinitrogen molecule by divalent lanthanide complexes has been a popular subject in coordination and organometallic chemistry of the lanthanide elements. In the course of these studies, a large number of polynuclear lanthanide clusters featuring a core of lanthanide atoms organized around a dinitrogen unit have been obtained and structurally characterized. 

A more detailed study of the decomposition of osmium(ii) dinitrogen species in aqueous solutions confirms that both [Os(NH3)s(N2)] and [Os(NH3)4-(N2)2] are very stable in neutral water. However, in both acidic and basic solution the decomposition of the former complex is subject to autocatalysis. Surprisingly, cis-[Os(NH3)4(N2)2] is stable between pH 1 and 14, although it was expected to be less stable than the mono-complex on the basis of i.r. frequency positions. These observations can be rationalized if one assumes Sf 2 attack on osmium by OH , and that the positive charge on the metal is smaller for [Os(NH3)4(N2)2] than for the mono-complex. 

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