ORIGINAL PAPER Li 2 HPO 3 ,H 2 O: Crystal Structure and IR Spectrum Souad Chaouche • Rachid Ouarsal • Brahim El Bali • Mohammed Lachkar • Michael Bolte • Michal Dusek Received: 27 June 2006 / Accepted: 6 January 2010 / Published online: 19 January 2010 Ó Springer Science+Business Media, LLC 2010 Abstract Crystal structure of Li 2 HPO 3 ,H 2 O was deter- mined by single-crystal X-Ray diffraction analysis at 173(2) K. It crystallizes in the monoclinic system (P2 1/c ) with the parameters: a = 5.0322(9) A ˚ , b = 8.9795(17) A ˚ , c = 17.088(4) A ˚ , b = 92.672(16)° and Z = 8. The struc- ture was refined to R = 0.0237 and xR = 0.0650 for 1449 reflexions. The framework of Li 2 HPO 3 , H 2 O can be described as layers perpendicular to the crystallographic c axis. The structure contains two types of Li-tetrahedrons. In one kind each O atom belongs to one HPO 3 group, while in the second kind one apex is an O from water. A network of hydrogen bonds interactions insures the connection between the layers. Keywords Phosphite Á Crystal structure Á IR-spectroscopy Introduction Neutral phosphites compounds are obtained by neutral- ization of phosphorous acid solutions by appropriate bases until pH 8 is reached. Acid phosphites are obtained by dissolution of corresponding bases in solutions of H 3 PO 3 up to pH 3.4, by adding alkali metals, ammonium and divalent or trivalent 3d metals. Crystal structures of the acid salts of inorganic oxyacids are distinguished by the formation of hydrogen bonding systems. Some properties, such as the proton conductivity or segnetoelectric transitions, can be explained by the specific features of the hydrogen bonding systems in the above compounds. Data on the structural studies of hydrogen bonds in acid oxysalts are generalized [1]. The structural studies on monocristal of acid and neutral salts of acid phosphorous have not yet been systematized, although the synthesis of alkali acid phosphites and alkaline earth have been described in some references [2–5]. Lately other studies, that cover structures of the crystal of the acidic phosphite of mono- and bivalent metals, were published: Superacid Univalent Metal Phosphites (MH 2 PO 3 ) 2 Á H 3 PO 3 (M = Rb, Tl(I)) and MH 2 PO 3 Á H 3 PO 3 (M = K, Cs) [6], Sr(H 2 PO 3 ) 2 [7, 8] and Ba(H 2 PO 3 ) 2 , 0.5H 2 O[9]. The present paper deals with the synthesis, crystal structure investigation and IR study of the new phosphite material Li 2 HPO 3 ,H 2 O. Experimental The compound is obtained by reacting 0.2 g (4.7 mmol) of lithium hydroxide with 0.13 g (1.6 mmol) of phosphorous acid solution H 3 PO 3 at a molar ratio 3:1. The solution is leaved at room temperature for 2 weeks, small colourless S. Chaouche Á R. Ouarsal Á M. Lachkar LIMOM, De ´partement de Chimie, Faculte ´ des Sciences, Universite ´ Sidi Mohamed Ben Abdellah, B.P. 1796 (Atlas), 30000 Fez, Morocco B. E. Bali (&) Laboratory of Mineral Solid and Analytical Chemistry ‘‘LCSMA’’, Department of Chemistry, Faculty of Sciences, University Mohamed 1er, 717, 60000 Oujda, Morocco e-mail: belbali@fso.ump.ma M. Bolte Institut fuer Organische Chemie, J. W. Goethe-Universitaet Frankfurt, Marie-Curie-Str. 11, 60439 Frankfurt Main, Germany M. Dusek Institute of Physics, Na Slovance 2, 182 21 Praha 8, Czech Republic 123 J Chem Crystallogr (2010) 40:526–530 DOI 10.1007/s10870-010-9690-1