Reactivity Study of Pyridyl‐Substituted 1‐Metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes of Group 4 Metallocenes

In this work the reactivity of 1‐metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes of group 4 metallocenes, especially of the pyridyl‐substituted examples, towards small molecules is investigated. The addition of H 2 , CO 2 , Ph−C≡N, 2‐py−C≡N, 1,3‐dicyanobenzene or 2,6‐dicyanopyridine results in exchange reactions, which are accompanied by the elimination of a nitrile. For CO 2 , a coordination to the five‐membered cycle occurs in case of Cp* 2 Zr(N=C(2‐py)−C(2‐py)=N). A 1,4‐diaza‐buta‐1,3‐diene complex is formed by H‐transfer in the conversion of the analogous titanocene compound with CH 3 −C≡N, PhCH 2 −C≡N or acetone. For CH 3 −C≡N a coupling product of three acetonitrile molecules is established additionally. In order to split off the metallocene from the coupled nitriles, we examined reactions with HCl, PhPCl 2 , PhPSCl 2 and SOCl 2 . In the last case, the respective thiadiazole oxides and the metallocene dichlorides were obtained. A subsequent reaction produced thiadiazoles.