Dipole Moment of Iodine

Abstract

THE problem of the dipole moment of iodine is of considerable interest. Some years ago, Williams1 and Muller and Sack2 measured the moment of iodine in benzene and carbon disulphide solutions and obtained a value of 11·2 × 1018 C.G.S. units. It is well known, however, that the iodine molecule should have a symmetrical structure. It is scarcely likely that iodine would react chemically with benzene under the conditions of their experiments. The moment observed was due to some interaction between I2 and C6H6. It seemed strange to us that a moment of the order of magnitude of l Debye, that is, a moment characteristic of a molecule of a marked polarity, should arise through the influence of Van der Waals' forces. The discrepancy between the value observed and that to be expected from theoretical considerations can be attributed to the imperfection of the method of measurements.