An ab initio study of the influence of substituents and intramolecular hydrogen bonding on the carbonyl bond length and stretching force constant. I. Monosubstituted carbonyl compounds

✍ Scribed by Charles W. Bock; Mendel Trachtman; Philip George

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 597 KB
• Volume: 2
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/jcc.540020107

✦ Synopsis

The C=O bond length and fc=o,c=o, the corresponding harmonic stretching force constant, are calculated ab initio using the 4-31G basis set (augmented by polarization functions on the sulfur and chlorine) with full geometry optimization for the monosubstituted carbonyl compounds RCHO, where R = H, CHO, CH=CH2, C02H, CH=CHOH, OH, OC(=O)OH, OOH, S-H, Li, F, C1, and NH2. Straight-line relationships are found in plots of lnVc=o,c=o] vs. ln [rc=o] for the series of compounds in which carbon atoms and oxygen atoms are bonded directly to the carbonyl carbon, in accordance with the empirical expression f = C'/rn. The slopes and intercepts give n = 7.62 and 6.47, C' = 62.6 and 48.6, for the lines with carbon and oxygen as the atom bonded directly to the carbonyl carbon, respectively. The point for formaldehyde lies very close to the C line, whereas the points for SH, Li, F, C1, and NH2 lie closer to the 0 line.