Complexes with Inorganic Main Group Substrates

Metal Complexes with Inorganic (Main Group) Substrates 

A number of studies have been reported on the reduction of nitrate by metal ions. In dilute HNO3 solution, the ruthenium(ii) species [(py)(bipy)2Ru(OH2)]2+ is oxidized by NO3- to the corresponding Ru complex. The metal nitrosyl cation [(py)(bipy)2Ru(NO)] + is also formed as a product, resulting from the nitrosation reaction of (initial product) HNO2 with ruthenium(ii) aquo-species. This side reaction is eliminated when the HNOj scavenger sulphamate ion (N112803 ) is present. The reaction mechanism involves an initial substitution of the nitrate to yield the species [(py)(bipy)2Ru(0 -NOa)], which in an intramolecular redox step produces HNOa and a ruthenium(iv) ion, 

Monomeric molybdenum(v) complexes of the type [M0OCI3L] (L = bipy or phen), [M0OCIL2] (L = 8-hydroxy- or 8-mercapto-quinoline), and [MoOCl-(MeOH)L] [L = 0-(salicyIidenimino)phenol] reduce NO3 in a one-electron step (in DMF) producing NO 2 and the corresponding Mo complex. The kinetics are complex with some deviations from linearity under first-order conditions. In the presence of added Cl and excess NO3 , however, linearity to 87 % reaction is observed. The rate law is of the form 

Omitting the ligand groups, a mechanism is proposed in which the initial dissociation of a chloride ion is followed by the formation of a nitrato-complex  

Reaction of a nickel(ii) tetra-aza-annulene with NOs in methanol results in the formation of a dinuclear nickel(iii) complex. In conditions of dilute acid, the reaction is slower than the corresponding reaction of HNO2 (which is reduced to NgO). In the reaction of the related tetra-azacyclotetradecadienenickel(n) ion with HNO3, however, oxidation takes place on the ring with tetraimine formation.  

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