Synthesis, structure and thermal decomposition of nitrogen-iodine charge-transfer complexes
ACS Citation
Bailey, R. D.; Drake, G. W.; Grabarczyk, M.; Hanks, T. W.; Hook, L. L.; Pennington, W. T. Synthesis, structure and thermal decomposition of nitrogen-iodine charge-transfer complexes. J. Chem. Soc., Perkin Trans. 2 (1972-1999) 1997, 2773-2780.
Version of Record
Abstract
Dipyridylquinoxaline (dpq), 4-cyanopyridine (4-CNpy), 4,4-€²-bipyridine (4,4-€²-bpy) and quinoxaline form n-†’σ* charge-transfer complexes with iodine (I2), in which the N-·- -·- -·I distance 2.532(3) Ã… for dpq-·I2; 2.543(9) and 2.555(9) Ã… for 4-CNpy-·I2; 2.406(7) Ã… for 4,4-€²-bpy-·2I2; 2.92(1) and 2.95(1) Ã… for quinox-·I2] is shorter than the sum of the van der Waals radii for nitrogen (1.55 Ã…) and iodine (1.98 Ã…). Donation of electron density into the antibonding orbital of iodine weakens the I-I bond resulting in elongation relative to the value observed in elemental iodine (2.715 Ã…). Dpq, 4-CNpy and 4,4-€²-bpy form molecular adducts, while quinoxaline forms a polymeric species in which there are interactions at both ends of the I2 molecule. The type of complex which forms depends on the nucleophilic character of the donor (and its corresponding effect of the I2 molecule) and on the lattice energy of the complex. The strength of the N-·- -·- -·I interaction in each of the reported complexes has been investigated by X-ray crystallographic analysis and vibrational spectroscopy (far-IR). All of the complexes undergo thermal decomposition involving loss of I2, and their lattice energy, as a function of thermal stability, has been explored.
Source Name
Journal of the Chemical Society, Perkin Transactions 2: Physical Organic Chemistry (1972-1999)
Publication Date
1-1-1997
Issue
12
Page(s)
141-151
Document Type
Citation
Citation Type
Article