Benzyne − an acetylene- or cumulene-like electronic structure?. Issue 33 (16th August 2019)

• Record Type: Journal Article
• Authors: Kleinpeter, Erich; Koch, Andreas
• Is Part Of: Tetrahedron. Volume 75:Issue 33(2019)
• Page Start: 4663
• Page End: 4668
• Publication Date: 2019-08-16
• Subjects: Benzyne−allene or cumulene-like structure -- Trough-space NMR shieldings (TSNMRS) -- NICS -- Iso-chemical shielding surfaces (ICSS) -- Ring current effect; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2019.07.011
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzyne1 and analogues (benzene2, 1, 2, 3-cyclohexatriene3, cyclohexen-3-yne4, cyclohexen-4-yne5, cyclohexyne6 ) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values could be employed to compare the diatropic ring current effects of benzene and benzyne, and, when compared with the spatial magnetic properties of the analogues, to answer the question whether the benzyne electronic structure is more acetylene- or cumulene-like, supported by structural data and δ ( 13 C)/ppm values. Graphical abstract: Image 1 Highlights: Both structures and spatial magnetic properties (TSNMRS) of benzyne1, and relatives 2-6 have been calculated. Available experimental and computed structural data are coincident. The diatropic ring current effects of benzyne1 and benzene2 are nearly identical. When comparing the TSNMRS of3, with4, 5, 6, the six-membered ring-deformed acetylene structure 1a of benzyne is its major contributing form.