Diazenido ligand preparation

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

In contrast to nitrosyls, the absence of a transferable oxygen atom in N2R ligands allows the preparation of stable diazenido complexes of oxophilic, early transition metals see for example Cp2TiCl(N2Ph). Furthermore, there are as yet no diazotate (RN=NO-) forming reactions anolo-gous to the nitrite forming reactions in nitrosyl chemistry (see equations 112 and 113). 

The nonspecialist reader of this section may come to the conclusion that the area of transition-metal complexes with alkyldiazenido ligands is not very large. This impression is reinforced by the fact that these complexes lose the diazo group relatively easily, as mentioned in the beginning of the section. It is wrong, however, if one considers the fact that diazoalkanes have been used, and still are, extensively in the preparation of carbenes via metastable diazenido intermediates of metal-complex catalysts in laboratory scale syntheses, in the Fischer-Tropsch reaction, and in olefin metathesis (see, e.g., Herrmann, 1978 Doyle 1986a, 1986b and Sects. 8.7 and 8.8 of this book). 

---