Barriers to rotation about the amide (N-CO) and sulphenamide (N-S) bonds in methyl n-arylsulphenyl-n-benzylurethanes. A simple molecular orbital model to explain substituent effects on sulphenamide rotational barriers

Daniel Kost, Arie Zeichner, Milon S. Sprecher

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Barriers to rotation about both the N-S and N-CO bonds have been measured in a series of substituted methyl N-arylsulphenyl-N-benzylurethanes, XC 6H4SN(CH2C6H5)CO 2CH3, by analysis of the temperature dependent n.m.r. spectra of the benzyl methylene protons. N-S Torsional barriers increase linearly with increasing electron demand of the substituants (σ- substituent constant), while N-CO barriers are substituent independent This result is inconsistent with a mechanism for S-N torsion involving (p-d)π conjugation between the nitrogen Ione pair and sulphur. An alternative rationale is proposed, based on a simple perturbational molecular orbital model. Application of the model to various experiments is discussed, with the conclusion that it adequately rationalizes all the currently available (and sometimes inexplicable) results on sulphenamides.

Original languageEnglish
Pages (from-to)317-325
Number of pages9
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number2
DOIs
StatePublished - 1 Jan 1980

ASJC Scopus subject areas

  • General Chemistry

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