Organometallic chemistry is a powerful tool for coupling simple unsaturated molecules into complex structures. Isonitriles (RNC's) are isoelectronic with CO, and alternative sources of C1 in C-C coupling reactions. Changes on the N substituent in RNCs can effect insertion chemistry that is complementary to that of CO.
We have explored the reaction of isonitriles (RNC's) with Group 4 (Ti, Zr, and Hf) diene complexes. The nature of the insertion product changes with the metal and the isonitrile (RNC), yielding metallaaziridines (Ti), diazametallacyclopentanes (Hf), and eta2-iminoacyl complexes (Zr).
The titanium complex below fragments in the presence of pyridine to the known imido complex Cp*(Cl)Ti(NtBu)py and an alpha-methylene cyclopentenimine. The overall reaction is the first example of a formal [4 + 1] cycloaddition between an isonitrile and a diene.