Systematic analysis of substituent effects. II. Charges and energies of atoms in fluorochloroethanes

✍ Scribed by Jerzy Cioslowski; Tereza Varnali

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 302 KB
• Volume: 72
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1999)72:4<331::aid-qua16>3.0.co;2-2

✦ Synopsis

Valuable insights into the nature of substituent effects are obtained by analyzing the variability of quantum mechanically defined fragment properties in terms of additive contributions. With the set of 92 fluorochloroethanes used as an example, the question of the relative importance of the direct and indirect influences of substituents upon properties of molecular fragments is addressed. The trends observed in electronic properties of entire molecules are found to originate from the additivities present at the level of individual atoms. Transferability of molecular fragments is shown to be severely compromised by the presence of significant substituent-induced charge transfer. Contrary to some recent claims, the kinetic energies of those fragments do not correlate with the extent of charge transfer.