Crystal structure and elastic properties of betaine fumarate and of betaine maleate, two isomers of ((CH3)3NCH2COOH . OOC(CH)2COOH
-
E. Haussühl
Abstract
X-ray structure analyses of orthorhombic betaine fumarate and monoclinic betaine maleate yielded space group Pnma, a1=26.510(5) Å, a2=6.684(1)Å, a3=6.376(1)Å, Z=4, ρcalc=1.371g cm-3, ρobs=1.370 g cm-3 and, respectively, space group P21/n, a1=6.132(1)Å, a2=10.823(2)Å, a3=17.246(3)Å, α2=92.87(3)°, Z=4, ρcalc=1.355 g cm-3, ρobs=1.351 g cm-3. In both compounds the hydrogen betaine cations are joined to the corresponding anions by strong H-bonds with O···O distances of about 2.48Å. Large single crystals of optical quality of betaine maleate have been grown from aqueous solutions. Further, we determined their coefficients of thermal expansion and their elastic and thermoelastic constants. In comparison to the pronounced anisotropy of the mechanical properties of betaine fumarate, the elastic constants of betaine, maleate appear only slightly anisotropic. Between 80 K and 305 K no phase transision could be detected in betaine maleate. However, softening of certain acoustic modes at temperatures below about 160 K might be a hint at structural instabilities at even lower temperatures.
© 2001 Oldenbourg Wissenschaftsverlag GmbH
Articles in the same Issue
- Thermal expansion of decagonal Al70.7Co13.3Ni16.0 in the temperature range 15–300 K
- The intermediate phase of strontium chromate aluminate sodalite
- Crystal structure and elastic properties of betaine fumarate and of betaine maleate, two isomers of ((CH3)3NCH2COOH . OOC(CH)2COOH
- Synthesis, electronic and crystal structure of a new organic semiconductor tetramethyltetrathiafulvalene-trinitroresorcinol (2:1), (TMTTF)2(C6H2N3O8)
- Synthesis and crystal structure determination of 6-phenyl-5-phenylsulfonyl-1,2,3,4-tetrahydropyrimidine-2-thione from neutron powder diffraction data
- A contribution to the crystal chemistry of DL-malates
- Absorption correction for crystal-environment attachments from direction cosines
- Book Review
Articles in the same Issue
- Thermal expansion of decagonal Al70.7Co13.3Ni16.0 in the temperature range 15–300 K
- The intermediate phase of strontium chromate aluminate sodalite
- Crystal structure and elastic properties of betaine fumarate and of betaine maleate, two isomers of ((CH3)3NCH2COOH . OOC(CH)2COOH
- Synthesis, electronic and crystal structure of a new organic semiconductor tetramethyltetrathiafulvalene-trinitroresorcinol (2:1), (TMTTF)2(C6H2N3O8)
- Synthesis and crystal structure determination of 6-phenyl-5-phenylsulfonyl-1,2,3,4-tetrahydropyrimidine-2-thione from neutron powder diffraction data
- A contribution to the crystal chemistry of DL-malates
- Absorption correction for crystal-environment attachments from direction cosines
- Book Review
