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Influence of the 1,1,3,3-tetramethylguanidinyl substituent on the charge distribution in chlorobenzenes, studied by 35Cl NQR

✍ Scribed by Boleslaw Nogaj; Przemyslaw Pruszyński

Publisher: John Wiley and Sons
Year: 1987
Tongue: English
Weight: 341 KB
Volume: 25
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260250405

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✦ Synopsis

35Cl NQR measurements were carried out on a series of chlorobenzenes with the 1,1,3,3-tetramethylguanidinyl substituent {TMG = -N=C[N(CH,)&}.

The substituent constants up, a,,, , a, and aR for the TMG group were estimated from the relationships between the NQR resonance frequencies, vQ , and substituent constant values, u.

The vQ value for 2-(4-chlorophenyl)-1,1,3,3-tetramethylguanidine is the lowest observed for all chlorobenzenes, and arises from the strong positive conjugative effect of the TMG group. This effect is attributed to the possible resonance stabilization of the positive charge. Steric inhibition of resonance is observed for the ortho-substituted isomers.

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