Dec.. 1960
COMMUNICATIONS TO THE EDITOR
Racemization Procedure .-Solutions having initial rotations of 2-6' were heated in a constant temperature bath until the rotation had decreased by one-half. The rotations were measured with a Kern polarimeter, and the re-
1959
producibility was f0.03'. The high pressure apparatus and sample holder already have been described.* (8) K.
R. Brower, J . Am. Cham. Soc., 80, 2105 (1958).
COMMUNICATIONS TO THE EDITOR TRIMERIC BISMUTH(1) : AN X-RAY DIFFRACTION STUDY OF SOLID AND MOLTEN BISMUTH(1) CHLOROALUMINATE
tained' a t this laboratory from measurements of optical absorp6ion.
t
sir:
50 This report summarizes an X-ray diffraction study of molten, polycrystalline, and monocrystalline BiA1C14 which indicates the occurrence of a trimer of bismuth atoms separated by 3.04 A. in the configuration of an equilateral triangle. The compound was prepared as previously described. l X-Ray diffraction patterns of the powder and melt were measured with monochromatized M o K a radiation in the range of (4?r/X) sin 0 less than 16. The powder pattern included diffuse as well as Bragg scattering. The patterns were interpreted, by procedures described elsewhere12m3 to yield the radial pair distribution functions shown in Fig. 1. The principal feature of both functions, a prominent sharp peak a t about 30.0 A. partially resolved from another a t about 3.4 A., requires the existence of a bismuth polymer. Further analysis, to be described in detail elsewhere, led to the probable configuration (Bi3)3+. The figure demonstrates by means of synthetic peaks that the proposed model is consistent with the observed distributions. Single crystals of BiA1C14have been shown4 to be rhombohedral with space group R3c, a = 12.12 A., 0 .I 2 3 4 5 6 CY = 58' 23', 2 = 6. This cell accounts for the powder pattern of BiAlCL, thereby demonstrating f , A. the identity of the two materials. Equivalent bis- Fig. 1.-Radial pair distribution functions for BiAlCL, solid muth atoms a t a separation of 3 A. can be accomand melt, from X-ray diffraction data. modated in this cell only if related by the triad axis; DIVISION thus the symmetry of the crystal also indicates the CHEMISTRY OAKRIDGENATIONAL LABORATORY H. A. LEVY existence of a trimer. OAK RIDGE,TENNESSEE M. A. BREDIG FOR THE U.S.A.E.C. M. D. DANFORD The finding of the trimer (Bi3)3+casts consider- OPERATED BY UNIONCARBIDE CORPORATION P. A. AGRON able doubt on an earlier tentative p r o p o ~ a lbased ,~ RECEIVED OCTOBER12, 1960 on cryoscopic and vapor pressure data, of a species (BQ2+in the system Bi-BiC1,. Recent measure(7) C. R. Boston and G. P. Smith, Jr., personal communication, to ments6 of e.m.f. in molten Bi-BiCL solutions also be published. suggest the species (Bi3)3+ in this system. Additional evidence of polymer formation has been obSORPTION O F GASEOUS HYDROGEN (1) -1. D. Corbett and R. K. hIcMullm, J. A m . Chem. Soc.. 7 8 , 2906 CHLORIDE BY NYLON AND PROTEINS
50r
(1956). (2) H.-4. Levy, P. A. Agron and M. D. Danford, J. Chem. Phys., 30, 1486 (1959); 31, 1458 (1959). (3) H. A. Levy, P. 4. Agron. hl. -4.Bredig and M. D. Danford, Annals of the h'ew Y o r k Academy of Scaences, 79, 762 (1960). (4) H..4. Levy, P. A. Agron and R. D. Ellison, t o be reported. ( 5 ) M. A. Bredig, THIS JOURNAL, 63, 978 (1959). (6) L. E. Topol, S. J. Yosim and R. A. Osteryoung. Xeeting American Chemical Society, New York, N. Yo, 1960,division of Physical Chemistry. Abstracts p. 6-6.
Sir: I n the course of work published in 1956' it was noticed that when Nylon with sorbed hydrogen chloride was exposed to water vapor or liquid water, it lost its tensile strength, felt sticky to the (1) L. 13. Reyerson and L. E. Peterson, THISJOURNAL,60, 1172 (1956).
