Iodine charge transfer complexes

Li-I 2 Li + I2 2 Lil 2.8 0.9 290 soHd electrolyte, 10+ year life welded constmction, used in most of heart pacers, iodine charge transfer complex Medtronic Catalyst WUson Greatbatch... 

Fig. 2. Orientation principle in the benzene-iodine charge-transfer complex (a) S and P Oi (b) jS and = 0.

Ma and Wu [152] have carried out SERS studies on pyridine-iodine charge-transfer complex on pc-Ag electrode. 

Addition of I2 to liquid ammonia at temperatures below 240 K results in the precipitation of green NI3-3NH3. The reaction proceeds via ammonia-iodine charge transfer complexes (I2 NH3 and I2 2NH3 are known), to iodamine, diiodamine, and to triiodamine. At temperatures below 200 K, red NI3-5NH3 is obtained. ... 

The equihbria (426) are reversible, and on the side of the ammonia-iodine charge transfer complex. Solvation of NI3 NH3 in diethylether in the presence of ammonium iodide yields the ether-soluble charge transfer complex NH3 I2. 

Direct excitation of electron-transfer states may yield surprising results. This is the case with the bimolecular benzene iodine charge-transfer complex. In solutions this system is the prototypical case of charge transfer as reported by Mulliken [262]. The characteristic 280 nm absorption band of the benzene-iodine system is distinct from any absorption features of neat iodine or benzene. It has been identified as being due to a promotion of the HOMO benzene n electron to a a LUMO orbital on iodine resulting in benzene iodine electron transfer. 

The poly(vinyl alcohol)-iodine charge transfer complexes have been the subject of many investigations " Water-soluble iodine complexes with ix)ly(l-vinyl-pyrrolidone) are commercially available as disinfecting agents PoIy(N-vinyl car-bazole) polyamides and poly(ethylene oxide) are also found to form molecular addition complexes with iodine and iodine compounds. An account of the different types of molecular complexes formed with various polymers has been published ... 

These assumptions were later proved directly, on the example of the formation of the pyridine-iodine charge-transfer complex [Le 72b]. It was shown that the rate of the reaction of Ps with iodine bound by pyridine in a comparatively stable complex was only half of the value expected on the basis of the theory of diffusion-controlled reactions, taking into account the changes due to complex formation in the diffusion coefficients. 

Adsorption of pyridine, a rigid molecule able to attain various orientations with respect to the metal surface, evidently remains the most studied process of adsorption of organic molecules at the electrodes. Pyridine replaces water molecules at the electrode surface the number of removed H2O molecules depends on the orientation of pyridine molecules with respect to the electrode surface. This process is associated with the partial charge transfer across the electrode surface. Using the SERS method, Ma and Wu have studied the pyridine-iodine charge-transfer complex at the Ag electrode [152]. Yang et al. 

Iodine Charge-Transfer Complex. Alkanes exhibit a negative iodine... 

Figure 7.14 Formation and dissociation of the excited benzene-iodine charge-transfer complex. Top Transient of free iodine atoms following the excitation of the Bz-l2 complex to its charge-transfer state. (The full line is a single exponential convoluted with the response time of the detector system.) Bottom The four panels (a), (b), (c) and (d) illustrates a possible series of structural changes see text...

Lang, F.T. and Strong, R.L. (1965) Gas-phase molecular complexes. The diethyl ether-iodine and benzene-iodine charge-transfer complexes. /. Am. Chem. Soc., 87, 2345—2349. 

Kwun, O.C. and Hartmann, H. (1976) The thermodynamics of the formation of monoalkylbenzene-iodine charge transfer complexes. Z Phys. Chem., 100,139-148. 

Gardner, R.C. and Ragsdale, R.O. (1968) Equilibrium studies of 4-substituted pyridine 1-oxide-iodine charge transfer complexes. Inorg. Chim. Acta, 2,139-142. 

McKinney, W.J. and Popov, A.I. (1969) Studies on the Chemistry of halogens and of poly-haUdes. XXX. Influence of solvent properties on the formation of pyridine-iodine charge-transfer complexes. J. Am. Chem. Soc., 91, 5215-5218. 

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