Tribromide Salts of the Organic Donor Tetra(methylthio)tetrathiafulvalene, [TTM-TTF]+(Br3-) and [TTM-TTF]2+(Br3-)2

The 1:1 and 1:2 phases (TTM -TTF)Br3 and (TTM -TTF)(Br3)2, TTM -TTF = tetra(methylthio)tetrathiafulvalene, C10H12S8, have been crystallized by diffusion of bromine vapour into solutions of the donor. The 1:1 salt is monoclinic, P 21/n, a = 7.587(2), b = 11.424(3), c = 23.145(8) Å , β = 95.80(3)°, V = 1997 Å3, Z = 4, Mr = 628.45, dc = 2.09 g cm-3, final Rw = 0.028 for 912 reflections. The 1:2 salt is monoclinic, C2/m, a = 11.510(3), b = 17.039(4), c = 9.770(3), β = 141.62(1)°, V = 1190 Å3, Z = 2, Mr = 868.16, dc = 2.42 g cm-3, final Rw = 0.029 for 899 reflections. Diadic stacks of the monopositive donor cations are found in the 1:1 salt, whereas the dipositive cations in the 1:2 salt form sheets via short intermolecular S···S contacts. A relation between bond lengths and charge is indicated.

The chemistry of pyrrolic compounds. XII. Dipyrrylmethanes

The synthesis of a range of dipyrrylmethanes, substituted with electrophilic substituents at one or more �-positions, is described. Bromine vapour has been found to be a useful reagent for identifying dipyrrylmethanes on thin-layer plates.

An experimental investigation of thermal conduction through vapours

Both the viscosity and the thermal conductivity of a gas are, according to Maxwell’s Law, independent of pressure over a wide range. This law is deduced by the application of the kinetic theory to a gas that obeys the gas laws, and there is, for real gases under normal conditions, abundant experimental evidence of its truth. In the case of vapours, however, the position is very different. The viscosities of various vapours have been made the subject of several investigations, but there is little direct evidence that the viscosity of an almost saturated vapour does not vary with its pressure. For instance, Rankine, in his work on the viscosity of bromine vapour, found that, although similar values could be obtained by different methods—using widely different pressure conditions—when the vapour at these pressures was at a temperature several degrees higher than its condensing point, definite irregularities were obtained when it was only slightly superheated. The same irregularties were noticed by Braune, Basch, and Wentzel for bromine vapour and, to a less extent, are apparent in their work on mercury vapour. Similar effects appear in the determination of vapour viscosities by Braune and Linke. Again, in C. J. Smith’s account of his experiments on the viscosity of water vapour it is admitted that, although the results, which were obtained under con­ditions of considerable superheating, agree fairly well with those of Speyerer for almost saturated steam, the methods of calculation depend, in both cases, on the validity of the gas laws when applied to the vapour. On the other hand, it has been shown by Boyd in work on the viscosities of nitrogen and hydrogen under pressure that the respective viscosities are increased by as much as 25 and 10% by an increase of pressure of about 100 atmospheres.

The scattering of electrons in bromine vapour

The angular distribution of the electrons scattered elastically from a primary beam in passing through the vapours of halogens and their compounds has recently been measured by one of us. Diffraction maxima and minima were found in all the curves; and although the scattering was produced by molecules the form of each curve was similar to those previously obtained by the author for the adjacent monatomic rare gases. We have now calculated theoretical curves for the same energies for which experimental curves were obtained in diatomic bromine. These results are given in the present paper, and a comparison is made between the theoretical and experimental scattering curves.

XXI.—The Influence of Air and Moisture on the Budde Effect in Bromine

SummaryA survey is given of recent work on the action of light on bromine vapour, both dry and in presence of air and moisture.Suggested explanations of the facts are discussed. It is concluded that the influence of water is due to a “poisoning” of the walls of the vessel, which prevents them from catalysing the recombination of bromine atoms.

On the viscosity of the vapour of iodine

In a previous communication I have described the measurements I have made of the viscosity of bromine vapour. The method used for this purpose involved the distillation of bromine from one vessel to another through a capillary tube. The pressure difference between the two ends of the capilllary was established by maintaining the two vessels at suitable different temperatures, and the rate of transpiration of the bromine vapour was estimated by observing the volume of the liquid bromine which evaporated in a given time. It was hoped that the same method could be applied to iodine by adjusting the temperatures of evaporation and condensation of values above the melting point of iodine (113° C.), and measuring the transpiration rate by means of the disappearance of liquid from the evaporation vessel. Preliminary experiments, however, soon revealed the fact that the liquid iodine was not sufficiently mobile, and its surface was too indefinite and variable in shape to allow small changes of volume to be observed. It was, therefore, found necessary to modify in several respects the method used with bromine.