Nuclear magnetic resonance studies of iodine-amine complexes

✍ Scribed by M. Ciureanu; M. Contineanu

• Publisher: Elsevier Science
• Year: 1979
• Weight: 719 KB
• Volume: 15
• Category: Article
• ISSN: 0378-4487
• DOI: 10.1016/0378-4487(79)80028-x

✦ Synopsis

The charge transfer equilibria in aromatic amine-iodine systems are investigated by chemical shift measurements. The formation constants K, determined by a new method, are compared with the results obtained from optical data. The pure complex shifts A0 are also determined and compared with those obtained by two classical n.m.r. methods. The A0 values of the amino protons are found to vary linearly with the Bammett o constant of the ring substituent in the donor molecule. Various contributions to the shift of the pure complex are discussed in relation to the structure of the complex and the determining role of the intermolecular charge transfer is stressed. The change of electron density on the nitrogen atom is used to evaluate the change in diamagnetic shielding as a result of intermolecular charge transfer. The A0 values for the aromatic protons are found to be smaller than for the amino protons.and are assigned mainly to the delocalization of the nitrogen lone pair electrons on the aromatic ring.