Synthesis, structure and thermal decomposition of tetra(2-pyridyl)pyrazineâ I2 charge-transfer complexes
Bailey, R. D.; Grabarczyk, M.; Hanks, T. W.; Pennington, W. T. Synthesis, structure and thermal decomposition of tetra(2-pyridyl)pyrazineâ I2 charge-transfer complexes. J. Chem. Soc., Perkin Trans. 2 (1972-1999) 1997, 2781-2786.
In both the solid state and in solution, 2,3,5,6-tetrakis(2-€²-pyridyl)pyrazine (tpp) reacts with iodine to form charge-transfer complexes. The solid state process results in the exclusive production of a mono-I2 adduct, 3, while the solution reaction can produce both 3 and a bis-I2 adduct, 4. The X-ray crystal structure of 4 is described and a structure for 3 is proposed based upon spectroscopic evidence and molecular orbital calculations. The thermal decompositions of 3 and 4 proceed by I2 evolution at very different rates and lead to different polymorphs of tpp. The mechanism of this process is described in terms of solid state reaction theory.
Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999)