Cell Dimensions. a. = 18.23 f 0.02 A., bo = 17.76 f 0.02 A.&co = 5.86 iz 0.01 A., 9, = 90.6 0.1 ; cell volume
1897 A3; a : b : c = 1.03:1:0.33. Formula Weights per Cell. 12. Formula Weight. 270.20. Density. 2.84 grams per cc. (calculated; weight of unit atomic weight 1.6602 X gram); 2.73 and 2 . i i [measured pycnometrically ( 1 ) ] .
152.
OPTICALPROPERTIES Refractive Indices (5893 A), n.r = 2.01, n y = 2.02, nz = 2.08; geometric mean 2.038. Molecular refraction 48.7 cc. (Crystals react with high refractive index liquids. Refractive indices can be measured by immersion in piperine-iodide melts, if care is taken to avoid overheating.) Optic Orientation. Y = b; S or Zhc = 45 & 1”.
LITERATURE CITED
(1) Balke, C. \V,j Smith, E. F., J. -4rtc. C h e m SOC.30, 1637 (1908). WORKdone under the auspices of the Atomic Energy Commission.
Copper Monocyanide, CuCN
D. T. CROMER, R. M. DOUGLASS,
and EUGENE STARITZKY
The University of California, Los Alamos Scientific Laboratory, Los Alamos,
copper monocyanide was placed in the thimble of a Soxhlet extractor and water was refluxed through the solid for about 2 weeks. Although copper monocyanide is very insoluble i n water, a t the end of this time small, colorless, euhedral crystals had formed at the bottom of the extractor. Analysis of the commercial material gave (by weight) 70.8% copper and 29.2% cyanide, corresponding t o the molecular ratio Cu/CN = 0.993. Powder x-ray diffraction patterns of the commercial material and of the recrystallized material are identical and agree with the Dowder d a t a given for comer monocyanide in the ASTM C$rh File (1-
C
OMMERCIAL
Dark Green Crystals Mean mole ratio Cu/CN = 0 91 Orthorhombic 17 84 6 80 21 89
From morphological measurements Dauber in 1850 ( 1 ) described crystals of copper monocyanide as monoclinic. Although Groth did not report the color of the crystals described b y Dauber, i t seems likely t h a t these crystals correspond t o the monoclinic crystals of h’orberg and Jacobson. (The elements of Dauber are evplicable in terms of the monoclinic unit cell of Norberg and Jacobson by the transformation matrix 101/020/~00.) The phase described in the present paper clearly is neither of the two mentioned above. CRYSTAL MORPHOLOGY System and Class. Orthorhombic, probably dipyramidal. No piezoelectric effect was detected with a Giebe-Scheibe-type apparatus. ANALYTICAL CHEMISTRY
=Z I
C=2 i
-
l Figure 1. Orthographic projection of crystal of copper monocyanide on (100) and (010)
Norberg and Jacobson (a)described two different kinds of copper monocyanide crystals as follows: Dark Red Crystals Mean mole ratio CU/CX = 0 94 Monoclinic UO, -4. 17 82 bo, A. 6 80 CO, A. 21014 P 99
N. M.
h
0492).
316
Optic Axial Angle (5893 A.), 2Vz = 55 f:3’; T < u very strong. Color. Pale yellow.
Axial Elements. a : b : c = 0.69:l:O 41 calculated from measured angles); 0.705 :1:0,431 (calculated from cell dimensions). Habit. Dipyramidal { 151) with less prominent ( 100 ] and (0511. Cleavage. ( 100) prominent giving rise to rhomb-shaped cleavage fragments with a 50-degree vertex angle. X-RAYDIFFRACTION DATA Diffraction Symbol. Formally mmmB2]-, but because only one (OkO)reflection, (0,18.0), was observed even on Weissenberg photographs exposed as long as 80 hours, diffraction symbol mmmB- may be considered as a possibility. Cell Dimensions. aa = 12.79, bo = 18.14, co = 7.82 A. Formula Units per Cell. 36; volume per formula unit 50.40 A3 Formula Weight. 89.56. Density. 2.95 grams per cc. (calculated; weight of unit atomic weight 1.6602 X 10-24 gram), 2.97 i= 0.01 (measured).
PROPERTIES OPTICAL Refractive Indices (5893 -4.).n x = 1.73, n y = 1.80, n~ = 2.07; geometric mean 1.861. Molecular refraction 13.7 cc. Optic orientation. X = b, Y = a,2 = C.
Optico Axial Angle (5893 A , ) . 2Vz = 63 5 2 ; r
