Abstract
Interactions between the nitrogen lone pair and the biradical centers are weak in 3,4- and 3,5-pyridyne, but can be large enough in the remaining pyridynes (where at least one radical site is adjacent to nitrogen) to change singlet-triplet splittings by up to 19.6 kcal/mol compared to the corresponding benzynes. Singlet pyridynes having one dehydro site at the 2-position are stabilized relative to analogous benzynes because of increased contributions from zwitterionic resonance structures; this stabilization is not available to the triplets. Singlet-triplet splittings in the pyridynes and 1H hyperfine couplings in the pyridyl radicals are well correlated.
Original language | English (US) |
---|---|
Pages (from-to) | 320-326 |
Number of pages | 7 |
Journal | Chemical Physics Letters |
Volume | 287 |
Issue number | 3-4 |
DOIs | |
State | Published - May 1 1998 |
Bibliographical note
Funding Information:We are grateful for high-performance vector and parallel computing resources made available by the Minnesota Supercomputer Institute and the University of Minnesota-IBM Shared Research Project, respectively. This work was supported in part by the National Science Foundation. Eric Patterson is thanked for research assistance.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.