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Syntheses, crystal structures and thermal behaviour of novel L-alanine halogenide compounds

2008; Slovenian Chemical Society; Volume: 55; Issue: 4 Linguagem: Inglês

1580-3155

Μ. Fleck, Christian L. Lengauer, L. Bohatý, Е. Тиллманнс,

Solid-state spectroscopy and crystallography

Two new L-alanine compounds (alanine alaninium triiodide (1), s.g. P2 i 2 i 2 i , a = 8.366(2) A, b = 8.912(2) A, c = 41.889(8) A and alanine SrCl 2 3H 2 O (2), s.g. P2 i , a = 8.540(2) A, b = 7.167(1) A, c = 8.769(2) A, β = 95.02(3)°) have been prepared and characterised by X-ray single crystal analysis. The crystal structure of (1) features the presence of two independent molecules of alanine, alaninium and triiodide, respectively, in the asymmetric unit, with a very strong hydrogen bond between the carboxylate groups of alanine and alaninium. Compound (2) is composed of infinite zig-zag chains of [SrO 7 Cl]-polyhedra, with alanine molecules and chloride ions in the interstices. By the study of the thermal behaviour of (1) via thermogravimetry and temperature resolved X-ray powder diffraction it was found that the compound is stable up to approx. 363 K and that the thermal expansion along c is only about 1/3 compared to a and b.