Reactions of Group 4 Metallocene Alkyne Complexes with Azobenzene: Formation of Diazametallacyclopropanes and NN Bond Activation

The alkyne complex Cp2Zr(py)(η2-Me3SiC2SiMe3) (1) (Cp = η5-cyclopentadienyl, py = pyridine) reacts with azobenzene to give the known diazene complex Cp2Zr(py)(N2Ph2) (2). The same method was used to synthesize the new complexes rac-(ebthi)M(N2Ph2) (ebthi = 1,2-ethylene-1,1′-bis(η5-tetrahydroindenyl), M = Ti (5), Zr (6)) by alkyne exchange. The reaction of Cp*2Ti(η2-Me3SiC2SiMe3) (7) (Cp* = η5-pentamethylcyclopentadienyl) and azobenzene gave the analogous diazene complex 8 and two different dinuclear complexes, 9 and 10, with two or three bridging phenylimido groups, respectively. The molecular structures of 6, 8, 9, and 10 were confirmed by X-ray crystallography and compared to former structural data shown in the literature.