Theoretical study of salicylaldehyde conformal isomers and their intramolecular oxygen and hydrogen relations

✍ Scribed by Cheng Chen; Shuang-Fuh Shyu; Fu-Sheng Hsu

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 210 KB
• Volume: 74
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1999)74:4<395::aid-qua3>3.0.co;2-q

✦ Synopsis

To verify the semiempirical-type localized hydrogen bonding analysis methods introduced by us several years ago, the intramolecular oxygen and hydrogen relations within salicylaldehyde are selected as the major topic in this theoretical study. The B3LYPr6-31G** density functional method is chosen for both the full-optimization and frequency-type calculations. Four ortho-type planar conformal isomers are proven to be local minima, and four internal rotation transition states are found by QST3-type calculation. The special interpretations of -CHO and -OH characteristic frequencies, energy barriers, and thermal chemical results are discussed. In the semiempirical scheme, both local hydrogen bonding population analysis and localized hydrogen bond energy breaking procedures are applied to five pairs of related oxygen and hydrogen atoms in each isomer. The explanations for the strong or weak hydrogen bonds and intra-CHO repulsion relationships are discussed.