Addition Products of Dinitrogen to Transition Metal Complexes

3 Addition Products of Dinitrogen to Transition Metal Complexes 

Metal — dinitrogen complexes are discussed briefly in this book, because they are structurally related to diazo and diazonium coupounds. In these complexes a diazo group is bonded to a metal and not to a C-atom, as in organic compounds. Addition products of aliphatic and aromatic diazo compounds will be reviewed in Chapter 10. 

The first indirect evidence for the formation of such complexes is due to Volpin and Shur (1964). They observed that a mixture of an organotitanium compound and a reducing agent absorbs dinitrogen from the gas phase under nonaqueous anaerobic conditions. After the addition of aqueous acid, ammonia was detected. 

The first dinitrogen complex of a transition metal was discovered by Allen and Senoff (1965). They attempted the synthesis of the hexaamminoruthenium complex [Ru(NH3)6] + by the reaction of hydrazine with ruthenium trichloride trihydrate in water, and they found that the dinitrogen complex [Ru(NH3)5(N2)] (3.16) was formed. The origin of dinitrogen was disproportionation of hydrazine in situ, with simultaneous formation of ammonia (3-19 and 3-20). 

Shortly afterwards, Shilov et al. (1966) showed that free N2 can also be taken up as a ligand in Ru complexes. 

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