537
Z. Kristallogr. NCS 215 (2000) 537-538
© by Oldenbourg Wissenschaftsverlag, München
Crystal structure of betaine potassium bromide dihydrate,
C5H11NO2 • KBr • 2H 2 0
L. C. R. Andrade*1, M. M. R. Costa1, F. Pinto11, J. A. Paixäo1, A. Almeida11, M. R. Chaves" and A. Klöpperpieper111
1
Universidade de Coimbra, Faculdade de Ciencias e Tecnología, Departamento de Física, P-3004-516 Coimbra, Portugal
" Universidade do Porto, Faculdade de Ciencias, Departamento de Física, 1MAT (núcleo IFIMUP), CFUP, Rúa do Campo Alegre, 687,
P-4169-007 Porto, Portugal
111
Universität des Saarlandes, Fachbereich Physik, D-66041 Saarbrücken, Germany
Received March 1, 2000, CCDC-No. 1267/414
The potassium ion is octahedrally coordinated by four O atoms of
two betaine molecules and by two water molecules. The ions
form chains along the [001 ] direction in the unit cell. The bromine
ion is involved in two hydrogen bonds being an acceptor of both
water molecules 0 3 — H 3 4 - B r 3.230(3) A and 0 4 — H 4 4 - B r
3.396(4) A . The later molecule is lying disorderly either above or
below the mirror plane of the aminoacid molecule. This observation is compatible with preliminary Raman results obtained for
this compound [3]. The examination of the crystal structure with
PLATON92 [4] shows that there are no solvent-accessible voids
in the lattice.
o C1
\
,n
T
J
O I U
u
Abstract
C 5 Hi 5 BrKN0 4 , orthorhombic, Pbcm (No. 57), a = 5.7170(5) A ,
b = 25.181(2) A, c = 7.4923(7) A , V= 1078.6 A 3 , Z = 4,
Rgt(F) = 0.027, wRlef(F2) = 0.069, T= 293 K.
Source of material
Single crystals of the compound have been grown from aqueous
solution with the stoichiometric composition betaine:KBr = 2:1
by the evaporation method.
Experimental details
Hydrogen atoms participating in C—H bonds were placed at calculated positions and refined as riding using the SHELXL-97 defaults [1], The hydrogen atoms of the two water molecules were
located on a Fourier difference synthesis and refined as riding.
Discussion
Betaine potassium bromide dihydrate, (C5H1 iN02)KBr • 2H2O is
a new member of the family of compounds BetKX (X = CI,Br,I)
[2]. The study of dielectric properties as a function of temperature
disclosed a structural phase transition occuring close to 150 K. No
pyroelectric effect was detected in the temperature range 10 K
- 300 K. Examination of the structure shows that the betaine molecule and the bromine ions lie on a mirror plane parallel to the ab
plane.
Table 1. Data collection and handling.
Crystal:
Wavelength:
It:
Diffractometer, scan mode:
20max:
N(hkl)measured, N(hkl)unique:
Criterion for /0bs, Nfhkl)^:
N(param)Krmd'
Programs:
colourless, transparent, truncated pyramid.
size 0.1 x 0.1 x 0.15 mm
Mo Ka radiation (0.70930 Â)
41.78 cm" 1
Enraf-Nonius CAD4, co/29
54.14°
3822, 128
/obs > 2 a(/obs), 840
103
SHELXL-97 [1], PLATON [4],
SDP-plus [5], O R T E P [6]
Table 2. Atomic coordinates and displacement parameters (in  2 ).
Atom
Site Occ.
H(4A)
H(2A)
H(2B)
H(3A)
H(3B)
H(3C)
H(33)
H(34)
H(43)
H(44)
8e
4d
8<?
8e
&e
&e
Ad
Ad
Ad
8«
X
y
-0.286(4)
-0.042(8)
-0.244(4)
0.226(5)
0.043(5)
0.245(5)
0.204(7)
0.382(9)
0.829(9)
0.520 0.79(1)
0.125(1)
0.007(2)
0.035(1)
0.118(1)
0.085(1)
0.054(1)
0.328(2)
0.359(2)
0.291(1)
0.348(3)
z
0.352(3)
1/4
0.147(3)
0.085(4)
-0.015(5)
0.096(4)
1/4
1/4
1/4
0.21(1)
t/iso
0.039
0.05(1)
0.035(7)
0.057
0.057
0.057
0.04(1)
0.09(2)
0.093
0.093
* Correspondence author (e-mail: [email protected])
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538
Betaine potassium bromide dihydrate
Table 3. Atomic coordinates and displacement parameters (in Ä 2 ).
Atom
Site
Occ.
x
Br
K
O(l)
0(2)
C(5)
N
C(4)
C(2)
C(3)
0(3)
0(4)
4d
4c
4d
4d
4d
4d
4d
4d
8«
4d
8e
0.61799(6)
0.4006(1)
0.1165(4)
-0.2609(4)
-0.0960(6)
-0.0111(5)
-0.1855(6)
-0.1505(8)
0.1403(5)
0.3471(6)
0.520(5) 0.8919(7)
y
z
Un
U22
t/33
0.43822(1)
1/4
0.19758(9)
0.2202(1)
0.1878(1)
0.0849(1)
0.1301(1)
0.0345(2)
0.0859(1)
0.3257(1)
0.3203(2)
1/4
0
1/4
1/4
1/4
1/4
1/4
1/4
0.0870(3)
1/4
0.1820(6)
0.0406(2)
0.0547(5)
0.030(1)
0.036(1)
0.031(2)
0.028(1)
0.021(2)
0.046(2)
0.041(1)
0.041(2)
0.051(2)
0.0381(2)
0.0480(5)
0.035(1)
0.031(1)
0.033(2)
0.026(1)
0.030(2)
0.028(2)
0.042(1)
0.043(2)
0.047(2)
0.0457(2)
0.0269(4)
0.051(1)
0.069(2)
0.032(2)
0.027(1)
0.045(2)
0.047(2)
0.030(1)
0.084(2)
0.088(4)
Acknowledgments. We thank gratefully Dr. J. Albers for his collaboration in
the study of betaine compounds and Dr.Y. Yuzyuk his helpful suggestions.
We are indebted to the Cultural Service of the German Federal Republic Embassy, the Deutscher Akademischer Austauschdienst (DAAD) and the German Agency for Technical Cooperation (GTZ) for the offer of a CAD-4
automatic diffractometer which enabled the experimental work to be carried
out. This work was supported by Funda^ao para a Ciencia e Tecnologia and by
PRAXIS/2/2.l/FIS/26/94 and by PRAXIS/C/FIS/14287/98. Filipa Pinto
thanks Project PRAXIS XXI for her grant BICI/4688/96.
C/12
-0.0020(2)
0
-0.006(1)
0.005(1)
-0.002(2)
-0.001(1)
-0.000(1)
-0.007(2)
0.001(1)
0.001(1)
0.003(2)
U13
0
0
0
0
0
0
0
0
0.007(1)
0
0.017(2)
U23
0
0.0029(3)
0
0
0
0
0
0
-0.002(1)
0
0.015(2)
References
1. Sheldrick, G. M.: SHELXL-97, a program for refining crystal structures.
University of Gottingen, Germany 1997.
2. Almeida, A.; Chaves, M.R.; Agostinho Moreira, J.; Pinto, Filipa;
Klopperpieper, A.: Betaine potassium iodide dihydrate: a new compound
of betaine. J. Phys.: Condens. Matter 10 (1998) L773-L777.
3. Almeida, A.; Pinto, Filipa; Chaves, M.R.; Klopperpieper, A.: Dielectric
properties and freezing of water molecules vibrations in betaine potassium
bromide dihydrate. To be published.
4. Spek, A. L.: PLATON. Molecular Geometry Program. University of
Utrecht, Utrecht, The Netherlands 1995.
5. Frenz, B. A.: Enraf Nonius SDP-plus Structure Determination Package.
Version 3.0. Enraf-Nonius, Delft, The Netherlands 1985.
6. Johnson, C. K.: ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA, USA 1976.
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