556
A. P. CARON,J. L. RAGLE,M. E. YORRE, AND H. YEH
The Powder Patterns and Lattice Constants of Ammonia Boron Trifluoride and Ammonium Tetrafluoroborate
by A. P. Caron, J. L. Ragle, M. E. Yorke, and H. Yeh Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
(Received July 17,1967)
The X-ray diffraction powder patterns of ammonia boron trifluoride, NH3BF3,and ammonium tetrafluoroborate, NH4BF4, were recorded on film and the unit-cell constants of the two orthorhombic lattices were calculated by a least-squares treatment: a = 8.130 i 1, b = 8.035 f 1, c = 9.252 f 1 b for NHsBF3; and a = 9.077 f 3, b = 5.679 f 2, c = 7.279 f 3 A for NH4BF4.
Introduction I n the course of a spectroscopic study of crystalline NH3BF3, it was discovered that, under certain recrystallization conditions, this compound may be contaminated by significant amounts of NH4BF4. The rapid decomposition of NH3BF3 to NH4BF4in water was recognized earlier by Parry, Kodama, and Schultz,’ although Ryss2 has claimed that the rate of hydrolysis of NH3BF3is about 10- 6 min-l. The X-ray powder method is the simplest method to determine the purity of NH3BFa. Three sets of unindexed powder patterns, with no more than 14 lines, have been published4+ and compared by Jenkins.6 Two of these patterns (those of Jenkins6 and Keenan and McDowel16) are in agreement and have been confirmed by Parry’ and Koenig;’ on the other hand, Laubengayer’~~ pattern is in complete disagreement with all others. The most accurate and reliable powder pattern for NH4BF4has been reported by Swanson, et aL8 However, this pattern does not extend beyond a Bragg angle of 37”, and calculated intensities are not listed. The structures of both NH3BFs and NH4BF4have been solved by single-crystal methods by Hoard and cow0rkers.~J0 These determinations make it then possible to calculate the intensities of the powder lines and facilitate indexing which would otherwise be difficult (both structures are orthorhombic). I n view of the analytical utility of the powder patterns of NH3BF3 and NH4BF4,it was judged worthwhile to obtain complete indexed patterns for both compounds as well as lattice constants.
(1) R. W.Parry, G. Kodama, and D. R. Schultz, J. Am. Chem. SOC. 80, 24 (1958). (2) I. G.Ryss, Dokl. Akad. Nauk SSSR, 120, 797 (1958). (3) I. G. Ryss and S. L. Idel’s, Zh. Fir. Khim., 3 3 , 374 (1959). (4) A. W.Laubengayer and G. F. Condike, J. Am. Chem. SOC.,70, 2274 (1948). (5) C. W.Keenan and W. 3. McDowell, ibid., 75, 6348 (1953). (6) W.A. Jenkins, ibid., 7 8 , 5500 (1956). (7) F. J. Koenig, Summary Report XVI, Mathieson Chemical Corp. Project, Subcontract M-3181-14,Department of Chemistry, St.
Experimental Section Ammonia boron trifluoride was prepared by the method of Leane and Richards.” Accordingly, 100 ml of doubly distilled boron trifluoride ethyl etherate, BF3 .Et20,purchased from Eastman Organic Chemicals (purified grade), was added to the same volume of
(1951). (10) J. L. Hoard and V. Blair, J . Am. Chem. Soc., 57, 1985 (1935). (11) J. B. Leane and R. E. Richards, Spectrochim. Acta, 10, 154 (1958).
s3
The Journal of Physical Chemistry
dry distilled ether. Gaseous ammonia was then passed through a trap containing sodium metal and was allowed to bubble slowly for 2-3 hr through the boron trifluoride solution, which was cooled with an ice-salt bath. Subsequently, the excess ether was decanted and pumped off the white precipitate at room temperature. Finally, recrystallization was accomplished by dissolving the solid product in distilled water at room temperature, cooling, and filtrating rapidly. If recrystallization is carried out too slowly, significant amounts of NH4BF4 may crystallize with NH3BF3. I n one instance, where the water solution was left standing overnight at room temperature, the product was essentially pure NHdBF4, although a powder pattern of the original crude product had shown only small traces of NH4BF4. Also, similarly poor results were obtained when the crude R”3BF3 was dissolved in dry methanol and precipitated by the addition of dry methylene chloride at room temperature. The sample of NH4BF4 used in this work was purchased from Alfa Inorganics and was recrystallized from cold, slightly basic ethanol. Samples of both NH3BF3 and NH4BF4were finely
Louis University, St. Louis, Mo. (8) H. E. Swanson, M , C. Morris, E. H. Evans, and L. Ulmer, U. S. National Bureau of Standards Monograph, NO. 26, U. S. Government Printing Office, Washington, D. C. 1964,Section 3. (9) J. L. Hoard, S. Geller, and W. M. Cashin, Acta Cryst., 4, 396
557
POWDER PATTERNS AND LATTICE CONSTANTS OF NHaBFa AND NHdBF4 Table I : NHaBPsPowder Pattern hkl
111 002
2o01 102 021
dobsd
4.. 873
4.642
dcalcd
4.862 4.626 4.065
Iobsd
dobsd
labsd
m
1.713
vw
1.684
W
1.662
W
1.647
m
1.620
vw
1.611
m
1.595
m
1.571
m
vs
1.556
W
S
1 531
vw
1.526
W
1.515" 1.507"
vw
S
vs
4:. 027
[ 43.685 .02J 8.680
vs
3.613
vs
8.380
vs
8.043
m
112
121
022 2.857 2.851
S
122 2.727
113
...
2.474 2.470 131
[2.45d 2.446 2.434
222 213 1231 302 004
S
[2.43j vs
2.348 2.313
2.313
2.237 321 231 114 223
2.185
...
2.145 2,097
a
I
S
vs 2.183 2.174 2.144 2.096
315' 414 135 250, 144 116 521,
1.494
W
'1.501' 1.500 1.496 .1.494 1.491 1.489 ,1.488,
m
1.471"
vw
1.440"
vw
1.431
m
1.419
m
W
1.357"
m
W
1.344"
vw
1.339"
vw
W
6 24 44 27 53 19 , 6
a
m W
2.013
W
1.966
m
040
133 124 411 141
1,947 1.928 1.908
1.946 1.927 1.908
1.865 402 042 420 233 4121
1 843 I
1.842
1.813
W W
vw S
1.810 1.801
304
a
1.325
m
*..
a
S
142 1.762
...
m
... 1.303"
*..
a vw a Volume 78, Number 8 February 1068
A. P. CARON,J. L.RAULE,M. E.YORKE,AND H.YEH
558 (Continued) dobed
Iobsd
dobad
lobad
1.072
W
256' 1.287
W
...
a
634 625'
1.271
m
318,
53 48
' 35 1.055
W
1,053'
vw
1.252" 1.242"
1.039
W
a
1.227
1.220
>
1.029
vw
013 122 113. 401,
10-2pF2
4.503 4.043 3.853 3,635 3.546 3.379 3.187 2.905
{4.47J i: 4.016 3.851 3.640 3.545 3.378 3.187 2.903
]::l[
vw
S
S W 5
6
2.791 2.542 2,504 2,408 2.345 2.329 2.287
...
2.236 2.169
2.794 2.540 2.507 2.407 2.344 2.327 2.286 2.269 '2.239' . l
2.231 '2.174' * 2.167. (2.166)
1 31 25 40 2 87 84
S
S
vw S
m
m m S
S
a
hkl
dobad
dodad
9
9
vs
2.837
202 301 121 311 220 103 302 22 1 400 022
Iobsd
1: 16 118 22 38 36 92 75 6 ' 32
m
W
444
