Unconventional Pathways in Nitrogen-Centered S2 Reactions: From Roundabout to Hydride Transfer.

The mechanisms and dynamics of bimolecular nucleophilic substitution (S2) reactions are complex and influenced by the nature of the central atom. In this study, we explore S2 at a nitrogen center (S2@N) by investigating the reaction of chloramine (NHCl) with methoxide ion (CHO) using ab initio classical trajectory simulations at the MP2(fc)/aug-cc-pVDZ level of theory. We observe that, in addition to the expected S2 product formation (CHONH + Cl), a high-energy proton-transfer pathway leading to CHOH and NHCl dominates, with near-quantitative agreement between simulations and experimental data.

Computational Studies of Nucleophilic Substitution at Nitrogen Center: Reactions of NHCl with HO, CHO and CHO.

The atomic-level mechanisms of the nucleophilic substitution reactions at the nitrogen center (S2@N) were investigated for the reactions of chloramine (NHCl) with the alkoxide ions (RO, where R=H, CH, and CH) using DFT and MP2 methods. The computed potential energy profiles for the S2@N pathways involving the back-side attack of the nucleophiles show the typical double-well potential with submerged barriers similar to the S2 reactions at the carbon center (S2@C). However, the pre-reaction and post-reaction complexes are, respectively, the N-H⋅⋅⋅O and N-H⋅⋅⋅Cl hydrogen-bonded intermediates, which are different from those generally seen in S2@C reactions.

Coordination and Stabilization of a Lithium Ion with a Silylene.

Herein, we report the stabilization of lithium-ion as the source of lithium to use as a trans-metalation reagent [{PhC(N Bu) Si( Bu)Li} I( BuN) CPh] (1). The reaction of 3 equivalents of the LSi Bu (L=PhC(N Bu) ) and lithium iodide at low temperature leads to a silylene stabilized lithium-ion with an additional coordination of amidinate ligand. Compound 1 shows two four membered and one six membered ring as confirmed by QTAIM calculations.