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Ring currents 314 INDEX

Several theoretical studies concerned with the quantitation of aromaticity that have been reported during the past decade also revealed the lack of aromaticity of oxazole. A ring current index was... [Pg.269]

A calculation with the semiempirical SIND01 method yields a ring current index of 1.720 for indicative of an aromatic ion. The anion c-NgH " was found to be unstable,... [Pg.155]

Proton chemical shifts are also a potential index of aromaticity. Thus, in pyrazine 7 the protons resonate at S = 8.6 ppm, whereas in its antiaromatic 162 and nonaromatic 163 derivatives the double bond protons show signals at 4.64 and 5.38 ppm, respectively <1983AGE171>. There is qualitative agreement with the ring current influencing... [Pg.77]

This is an aromaticity index based on the idea of ring current whose magnitude is determined by its weakest link in the ring [Jug, 1983 Jug, 1984], The weakest link is considered as the bond with the minimum total bond order ... [Pg.378]

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Ring current

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