Spectroscopic studies of the reaction of iodine with 2,3-diaminopyridine

The char.-e-transfer interaction of 2,3-diaminopyridine (DAPY) and iodine has been investigated spectrophotometrically in the solvents chloroform and dichloromethane at room temperature. The results indicate the fort-nation of 1:2 charge-transfer complex in each solvent with the observation of the two characteristic absorptions for triiodide ion around 355 and 295 nm. The iodine complex is formulated as [(DAPY)I](+ .) I-3(-). The formation of the triiodide ion, I-3(-), is further confirmed by the observation of the characteristic bands for non-linear I-3(-) ion with C-2v symmetry at 151 and 132 cm(-1) assigned to v(as)(I-I) and v(s)(I-I) of the I-I bonds and at 61 cm(-1) due to bending delta(I-3(-)). The mid infrared spectra of (DAPY) and triiodide complex are also obtained and assigned. (C) 2003 Elsevier B.V. All rights reserved.