Diazenido ligand

The third area is the synthesis and characterization of aryldiazenido complexes of transition metals. In 1964 King and Bisnette isolated the first metal complex with an aryldiazenido ligand. The interest of organometallic chemists was concentrated mainly on the isolation and characterization of stable aryldiazenido complexes and not on potential metastable intermediates involved in metal-catalyzed dediazonia-tions. The situation is different, however, for metal complexes with alkyl-diazenido ligands. Complexes with aryl- and alkyldiazenido ligands are the subject of Chapter 10 in the forthcoming second book (Zollinger, 1995). 

Diazenido ligand, 27 218-226 alkyl and acyl complexes of, formation, 27 ... 

The corresponding compound with thiobenzoyl diazenido ligands also has been prepared (37). 

The oxidation of preformed hydrazine or hydrazido(l —) complexes can also lead to the formation of diazenido ligands (equations 137 and 138). 

The presence of three lone pairs of electrons in the diazenido ligand (R-N = ISO allows it to bind in a bridging fashion to several metals at once. Three bridging modes of binding for diazenido ligands have been observed (25-27). 

There are several interesting and useful reactions of coordinated —NNR ligands. Diazenido complexes undergo protonation or alkylation on Np in some d4 complexes and d6 complexes (N2R considered to have positive charge) and protonation on N0 in five-coordinate dz complexes and in complexes with doubly bent diazenido ligands (equations 147-151). 

Other Lewis acids including transiton metals also bind to N in these complexes.386 Hydride sources can attack diazenido ligands at N forming the expected diazene complex (equation 152). 

It can be envisaged that, depending upon the electronic requirements of the metal, the diazenido ligand can adopt one of the following geometries. 

Of the two possible modes of bonding for bridging diazenido ligands, form 10 has been authenticated in [ Mn(N2Ph)(CO)4 2] (1) and... 

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