Azides organic, reduction with metals

This mechanism can be illustrated by the reaction of ferrous ions with hydrogen peroxide (42), the reduction of organic peroxides by cuprous ions (63), as well as by the reduction of perchlorate ions by Ti(III) (35), V(II) (58), Eu(II) (71), The oxidation of chromous ions by bromate and nitrate ions may also be classified in this category. In the latter cases, an oxygen transfer from the ligand to the metal ion has been demonstrated (8), As analogous cases one may cite the oxidation of Cr(H20)6+2 by azide ions (15) (where it has been demonstrated that the Cr—N bond is partially retained after oxidation), and the oxidation of Cr(H20)6+2 by 0-iodo-benzoic acid (6, 8), where an iodine transfer was shown to take place. 

The reduction of alkylazides by single electron transfer (SET) cleanly furnishes the alkyl-aminyl radicals plus molecular nitrogen. A variety of metal reagents and photochemical methods exist. The reaction can also be performed with organic radicals, which add to the azide and release dinitrogen, too (see also Section 8.3.2). The resulting aminyl radical can be simply reduced to the corresponding amine or can further react with radical traps (olefins) to form C-N bonds. 

Photochemical reactions of the iridium(m) and rhodium(m) complexes [M(NH3)6(N3)] + result in the production of a co-ordinated nitrene intermediate. In concentrated hydrochloric add the iridium(m) product is [Ir(NH3)6(NH2Cl)] +, as in the equivalent thermal reaction. These iridium(ra) and rhodium(m) complexes thus behave photochemically in a similar mmmer to hydrazoic acid and to organic azides. Their behaviour contrasts with that of some other transition-metal azide complexes, e.g. those of ruthenium(n), where an azido-radical is the photochemical intermediate. One can indeed group transition-metal azide complexes into three groups, with their thermal and photochemical reactions depending on the relative ease of oxidation or reduction (or neither) of the transition-metal centre. ... 

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