Journal Article Benzoin Breslow intermediate L7J6A1NE81 N-heterocyclic carbenes Research Support, Non-U.S. Gov't benzoin condensation carbene ligands carbocyclic carbenes computational chemistry coordination chemistry of main group elements divalent NI compounds donor-acceptor systems donor‐acceptor interactions electronic structure electronic structure analysis energy decomposition analysis nitrogen nitrogen cations organocatalysis quantum chemistry thiazetidin-2-ylidene