Novel α-spirocyclic (alkyl)(amino)carbenes at the theoretical crossroad of flexibility and rigidity

M. Z. Kassaee, Mohammadreza Momenitaheri, F. A. Shakib, M. Ghambarian, S. M. Musavi

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Spirocyclic (alkyl)(amino)carbenes (CAACs) with reasonable conformations of cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl substituents in the position α to the carbenic center are investigated at B3LYP/AUG-cc-pVTZ//B3LYP/6-31+G*. The singlet-triplet energy separations (ΔEs-t), HOMO-LUMO energy gaps (ΔEHOMO-LUMO), hydrogenation energies (ΔEH), heats of methylene formation (ΔE) as well as philicity indices (N and ω) of these carbenes are compared and contrasted. The highest ΔEs-t is encountered for the cyclopropyl substituted CAAC (54.2 kcal/mol), while the other ones lay in a narrow range of 48.2-51.8 kcal/mol. Assignment of the barriers for ring inversions is carried out in order to probe the "flexible steric bulk" of cyclic substituents, showing negligible differences with those of the unsubstituted rings. The calculated N and ω indices indicate that in contrast to the popular belief, CAACs appear less electrophilic than N-heteorcyclic carbenes (NHCs).

Original languageEnglish (US)
Pages (from-to)593-598
Number of pages6
JournalStructural Chemistry
Volume21
Issue number3
DOIs
StatePublished - Feb 8 2010

Keywords

  • CAAC
  • DFT
  • NHC
  • Nucleophilicity and electrophilicity
  • Ring inversion

Fingerprint Dive into the research topics of 'Novel α-spirocyclic (alkyl)(amino)carbenes at the theoretical crossroad of flexibility and rigidity'. Together they form a unique fingerprint.

Cite this