N−C Bond Formation Promoted by a Hafnocene Dinitrogen Complex:  Comparison of Zirconium and Hafnium Congeners Wesley H. Bernskoetter Andrea V. Olmos Jaime A. Pool Emil Lobkovsky Paul J. Chirik 10.1021/ja064163k.s003 https://acs.figshare.com/articles/dataset/N_C_Bond_Formation_Promoted_by_a_Hafnocene_Dinitrogen_Complex_Comparison_of_Zirconium_and_Hafnium_Congeners/3063580 Nitrogen−carbon bond formation from coordinated dinitrogen has been observed upon addition of 2 equiv of PhNCO to the hafnocene dinitrogen complex, [(η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>H)<sub>2</sub>Hf]<sub>2</sub>(μ<sub>2</sub>,η<sup>2</sup>,η<sup>2</sup>-N<sub>2</sub>). The resulting product most likely arises from initial NC cycloaddition of the first equivalent of heterocumulene, followed by carbonyl insertion of a second equivalent into the newly formed hafnium−nitrogen bond. The resulting product has considerable hafnium imido character, as evidenced by the metrical parameters determined from the solid-state structure as well as reactivity studies, whereby PhNCO, <i>p</i>-tolyl isocyanate, and <i>t</i>-BuC⋮CH each undergo cycloaddition with the hafnium−nitrogen bond. The origin of the nitrogen−carbon-forming chemistry is likely derived from the reluctance of the hafnocene dinitrogen complex to undergo ligand-induced N<sub>2</sub> isomerization, as was observed with the zirconium congener. 2006-08-23 00:00:00 cycloaddition hafnium imido character equivalent hafnocene dinitrogen PhNCO bond