Topology-driven physicochemical properties of π-electron systems. 1. Does the clar rule work in cyclic π-electron systems with the intramolecular hydrogen or lithium bond?

• Published in: Journal of organic chemistry Vol. 71; no. 20; pp. 7678 - 7682
• Main Authors: KRYGOWSKI, T. M, ZACHARA, J. E, OSMIALOWSKI, B, GAWINECKI, R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 29.09.2006
• Subjects: Chemistry; Condensed benzenic and aromatic compounds; Exact sciences and technology; Organic chemistry; Preparations and properties; Intramolecular reaction; Phenanthrene derivatives; Stability; Separation; Aromaticity; Prediction; Theoretical study; Lithium; Anthracene derivatives; Naphthalene derivatives; Pi electron system; Triphenylene; Ketoenol; Cyclic compound; Phenols; Cations; Aromatic compound; Moller Plesset partition; Physicochemical properties
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo061068l

The Clar model predicting stability and electron distribution in benzenoid hydrocarbons seems to be also a good predictor for related properties in lithium o-acylphenolates and to a lesser extent in the phenols themselves. This conclusion is based on analysis of geometry changes in the analogues of naphthalene, phenanthrene, anthracene, and triphenylene, where benzene rings are systematically replaced with a quasi-ring formed as a beta-ketoenol or beta-ketoenolate complex with a lithium cation, i.e., where CH-CH-CH fragments are replaced with O...Li...O or O...H...O fragments. These systems were optimized at the MP2/6-31G(2d,p) level of theory. The energy of bond separation reactions in line with aromaticity indices HOMA and NICSs supported the above statement.