The iodine cation, I2 +, in antimony pentafluoride

Abstract

Blue solutions and blue solids obtained from the reactions between iodine and antimony pentafluoride, and between iodine, iodine pentafluoride, and antimony pentafluoride, have been studied by chemical, spectroscopic, and magnetic techniques. Similar solutions are formed by iodine in the presence of iodine pentafluoride and the pentafluorides of P. As. Nb, and Ta, but only in the case of Ta is a stable solid isolated. The results are discussed in terms of the iodine molecule cation, 12+.THE anticipation that halogen cations, hal+, should be paramagnetic, was followed by the discovery that a blue species, formed from iodine and iodine monochloride under conditions that should favour the formation of I+, was indeed strongly paramagnetic. This led to an identification1 which appeared to be supported by a variety of measurement^.^^^ Other explanations were discussed, and the possibility that I,+ was responsible was considered. The latter in particular was rejected one one ground; that the formation did not accord with some conductivity data.l However, the more recent discovery that the blue species could be formed in solvents very different from the original sulphuric acid and oleums, and that the absorption bands in the visible region 3-5 were almost completely unaffected by the change, threw considerable doubt on the I+ theory. This required the visible bands to be due to p-9 transitions, depending upon an asymmetric solvation for a ' crystal-field ' splitting3After the present studies were well advanced both in Melbourne and Leicester, Gillespie and Milne published data for solutioss in fluorosulphuric acid which show conclusively that the blue species is not I+. Their results are, however, in good accord with the formulation 12+. They have also extended earlier observations 6,7 and have confirmed the presence of the cations Isf, I,+, and IO+ in strongly acidic media. Their evidence, both for I,+ and the other cations, rests largely on careful R.

Iodosylbenzene Coordination Chemistry Relevant to Metal–Organic Framework Catalysis

“…The ionizability of iodine is manifest in a rich body of iodine-centered redox chemistry and the availability of families of compounds featuring iodine in oxidation states greater than zero (Figure ). For example, exposure of I 2 to SbF 5 results in the formation of the [I 2 + ]-containing salt [I 2 ]­[Sb 2 F 11 ] (Figure a). , Dimerization of I 2 + to afford I 4 2+ has been observed, , and higher-order iodine cations such as I 3 + , I 5 + , I 7 + , and I 15 + have been characterized . Higher oxidation state iodine species are also commonly encountered in iodine oxyacids of I­(I), I­(III), I­(V), and I­(VII) (i.e., HIO, HIO 2 , HIO 3 , and HIO 4 ), iodine oxides, and iodine fluorides (i.e., IF 7 ) (Figure b).…”

Opening of the four-membered ring in perfluorinated 1-alkyl-2-phenyl- and 1-aryl-1,2-dihydrocyclobutabenzenes in the system I2-SbF5

“…It was presumed that cleavage of the C 1 -C 2 bond occurs with participation of I 2 molecule although iodine in SbF 5 exists mainly as I 2 + species [11]. The fact that compounds V and XI react with I 2 -SbF 5 in the presence of HF more readily (Schemes 1-3) may be rationalized assuming increase in the concentration of I 2 and reduction in the concentration of I 2 + in the system upon addition of HF [12].…”

Formation of perfluorinated 1,2-dialkylbenzenes from perfluoroalkylbenzocyclobutenes in the system I2-SbF5

“…The conversion of compounds II-V into perfl uoro-odialkyl benzenes VII, IX, XI, XII effected by I 2 -SbF 5 (on the system I 2 -SbF 5 , see [8]) may be presumed as occurring through the intermediate formation of a cationoid species A (or B) followed by the opening of its four-membered ring (Scheme 3). The species A and B may be regarded as heteroatomic analogs of perfl uorobenzocyclobutenylalkyl cations whose four-membered ring opening along analogous route was discussed previously [6,7].…”