Hydrogen-Bonded Complexes of Methylnitrene

Understanding the microsolvation effects of nitrenes is of vital importance in applied nitrene chemistry. Herein, we report the structures and reactivity of the prototype microsolvated systems consisting of the simplest alkylnitrene CH₃N and hydrogen bond donors HX (X = OH, Cl). Specifically, the 1:1 complexes of triplet CH₃N with H₂O and HCl were generated from photolysis of the corresponding amine precursors CH₃NHX in solid Ar-matrices at 6 K. Characterization of the two complexes CH₃N···HX with matrix-isolation IR and UV-vis spectroscopy is supported by D-isotope labeling experiments and quantum chemical calculations, and the results confirm that the electron-deficient nitrene center acts as hydrogen bond acceptor. Consistent with the observed absorptions at around 310 nm for the hydrogen-bonded nitrene, photoexcitation of CH₃N···HX at 310 nm promotes competing rearrangement of the nitrene to imine via 1,2-H migration and H-X bond insertion reactions, for which the underlying mechanism has been revealed by the CASPT2//CASSCF calculations.