Tetrahedron, March 18, 2013, Vol.69(11), p.2436(10)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tet.2013.01.027 Byline: Erich Kleinpeter, Peter Werner, Andreas Koch Abstract: Structures,.sup.1H/.sup.13C chemical shifts, and I electron distribution/conjugation of an experimentally available and theoretically completed set of push-pull allenes Acc.sub.2 C C CDon.sub.2 (Acc=F, CHO, CF.sub.3, CN; Don=t-Bu, OMe, OEt, SMe, SEt, NCH.sub.2R) have been computed at the DFT level of theory. Both orthogonal linear and orthogonal bent structures have been obtained. In the latter case the push-pull character could be quantified by the quotient method. The.sup.13C chemical shift of the central allene carbon atom C-2 and chemical shift differences [DELTA][delta](C-1, C-2) and [DELTA][delta](C-2, C-3) of allene carbon atoms proved to be a quantitative alternative. TSNMRS of ring-closed push-pull allenes have been computed in addition and were employed to identify polar, carbene-like and carbone-like canonical structures of these molecules. Author Affiliation: Universitat Potsdam, Institut fur Chemie, Karl-Liebknecht-Str. 24-25, D-14476 Potsdam, Golm, Germany Article History: Received 30 November 2012; Revised 7 January 2013; Accepted 10 January 2013
Push–Pull Allenes ; Push–Pull Character ; 13 C NMR Spectroscopy ; Quotient Method ; Tsnmrs ; Icss ; Aromaticity;
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