کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5212234 | 1383109 | 2017 | 10 صفحه PDF | دانلود رایگان |
The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of amino-substituted heteroaromatic six-membered ring systems such as pyrylium/thiopyrylium analogues 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 were employed to quantify and visualize the existing aromaticity of the studied compounds. Due to strong conjugation of six-membered ring Ï-electrons and lone pairs of the exo-cyclic amino substituents (restricted rotation about partial C,N double bonds) the interplay of still aromatic and already dominating trimethine cyanine/merocyanine-like substructures can be estimated.
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Journal: Tetrahedron - Volume 73, Issue 30, 27 July 2017, Pages 4265-4274