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The Effects of Ring Strain on Cyclic Tetraaryl[5]cumulenes |
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| Authors: | Dr Bozheng Sun Dr Meagan S Oakley Dr Kota Yoshida Yanwen Yang Prof Matteo Tommasini Dr Chiara Zanchi Dr Andrea Lucotti Dr Michael J Ferguson Dr Frank Hampel Prof Mariusz Klobukowski Prof Rik R Tykwinski |
| Institution: | 1. Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2 Canada;2. Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan;3. Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy;4. Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), University of Erlangen-Nuremberg, Nikolaus-Fiebiger Str. 10, 91058 Erlangen, Germany |
| Abstract: | Cyclic tetraaryl5]cumulenes ( 1 a–f ) have been synthesized and studied as a function of increasing ring strain. The magnitude of ring strain is approximated by the extent of bending of the cumulenic core as assessed by a combination of X-ray crystallographic analysis and DFT calculations. Trends are observed in 13C NMR, UV-vis, and Raman spectra associated with ring strain, but the effects are small. In particular, the experimental HOMO-LUMO gap is not appreciably affected by bending of the 5]cumulene framework from ca. 174° (λmax=504 nm) in 1 a to ca. 178° (λmax=494 nm) in 1 f . |
| Keywords: | cumulenes macrocycles Raman spectroscopy ring strain X-ray crystallography |