Styrene Aziridination by Iron(IV) Nitrides

Thermolysis of the iron(IV) nitride complex [PhB(tBuIm)(3)FeN] with styrene leads to formation of the high-spin iron(II) aziridino complex [PhB(tBuIm)(3)Fe-N(CH2CHPh)]. Similar aziridination occurs with both electron-rich and electron-poor styrenes, while bulky styrenes hinder the reaction. The aziridino complex [PhB(tBuIm)(3)Fe-N(CH2CHPh)] acts as a nitride synthon, reacting with electron-poor styrenes to generate their corresponding aziridino complexes, that is, aziridine cross-metathesis. Reaction of [PhB(tBuIm)(3)Fe-N(CH2CHPh)] with Me3SiCl releases the N-functionalized aziridine Me3SiN(CH2CHPh) while simultaneously generating [PhB(tBuIm)(3)FeCl]. This closes a synthetic cycle for styrene azirdination by a nitride complex. While the less hindered iron(IV) nitride complex [PhB(MesIm)(3)FeN] reacts with styrenes below room temperature, only bulky styrenes lead to tractable aziridino products.