title: Electronic and infrared spectral and thermal studies on the molecular complex of dibenzo-18-crown-6 and iodine.
abstract: The interaction of the crown ether dibenzo-18-crown-6 (DBC) with iodine has been studied in CHCl3 at room temperature. The charge-transfer absorptions, far infrared and thermal measurements of the formed charge-transfer complex were recorded and discussed. The results obtained show the formation of the pentaiodide complex with the general formula [(DBC)]+ I5-. The pentaiodide ion, I5-, is described as I3-(I2) confirmed by the observation of the characteristic absorptions for I3- ion around 365 and 290 nm. In addition, the far infrared spectrum of the solid complex shows the three vibrations of I3- unit is at 141, 113 and 71 cm(-1) assigned to nu(as)(I-I) and nu(s)(I-I) and delta(I3-), respectively, while the band related to the vibration of I2 unit is observed at 180 cm(-1). Vibration analysis of the obtained data shows that the symmetry of I3- unit could be non-linear with C2v symmetry. The structure of the formed pentaiodide complex was further supported by thermal gravimetric analysis measurements.
authors.affiliation: Department of Chemistry, College of Science, University of Qatar, P. O. Box 2713, Doha, Qatar. lshahada@yahoo.com
authors.forename: L A
authors.initials: LA
authors.lastname: Shahada
mesh_terms: D002244:Carbon / Q000737:chemistry; D043844:Crown Ethers / Q000737:chemistry*; D004583:Electrons; D006358:Hot Temperature; D007454:Iodides / Q000737:chemistry; D007455:Iodine / Q000737:chemistry*; D007477:Ions; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013696:Temperature
chemical_list: D043844:Crown Ethers; D007454:Iodides; D007477:Ions; C002564:dibenzo-18-crown-6; D002244:Carbon; D007455:Iodine