Electrochemical and Theoretical Study of a New Series of Bicyclic Oxazaborines

ABSTRACTOxazaborines are stable precursors in the synthesis of triazaborine chromophores. Eight new oxazaborine derivatives bearing different donor and acceptor substituents were electrochemically investigated and the results were correlated with quantum calculations. The attention was focused on determination of the first oxidation and the first reduction potentials, their differences, and the relationships with the calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies. The electrochemical results, reflecting the locations of oxidation and reduction centers and intramolecular electron communication due to substituents, were correlated with the Hammett type sigma (para) constants using linear free energy relationships. Special cases are discussed and the reaction mechanisms are proposed.