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The Bond-Rotational Mobility of Guanidinium Ion

✍ Scribed by Thomas Bally; Peter Diehl; Edwin Haselbach; Alan S. Tracey

Publisher
John Wiley and Sons
Year
1975
Tongue
German
Weight
610 KB
Volume
58
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The NMR. spectrum of guanidinium ion 1 is studied in anisotropic liquid crystalline nematic solution. Assuming an HNH‐angle of 120°, the distance ratio NH/NC = 0.784 is obtained, from which using NC = 1.330 Å (from X‐ray data) NH = 1.043 Å results. An upper bound for the free energy of activation for bond rotation of Δ__G__^+^ ≤ 13 kcal/mol is deduced. The bondrotational mobility of 1 is also investigated using the MINDO/3‐SCF‐procedure. The results obtained for the three conceivable consecutive activation energies for bond‐rotation indicate that the observed bond‐rotational mobility of 1 does not involve cooperative two‐ or three‐bond rotations. The ‘conjugative stabilization’ of 1 has been estimated to be of the order of 24–26 kcal/mol.

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