Synthesis and crystal sructure of a new dihydrogenomonophosphate (4-C 2 H 5 C 6 H 4 NH 3 )H 2 PO 4 K. Kaabi a , A. Rayes a , C. Ben Nasr a , M. Rzaigui a,* , F. Lefebvre b a Laboratoire de Chimie des Mate ´riaux, Faculte ´ des Sciences, 7021 Zarzouna, Bizerte, Tunisia b Laboratoire de Chimie Organome ´tallique de Surface (LCOMS), Ecole Supe ´rieure de Chimie Physique Electronique de Lyon, Lyon, France Received 26 July 2002; received in revised form 17 February 2003; accepted 3 March 2003 Abstract Chemical preparation, crystal structure, calorimetric, and spectroscopic investigations are given for a new organic-cation dihydrogenomonophosphate, (4-C 2 H 5 C 6 H 4 NH 3 )H 2 PO 4 in the solid state. This compound crys- tallizes in the orthorhombic space group Pbca with the following unit cell parameters: a ¼ 8:286ð3Þ A ˚ , b ¼ 9:660ð2Þ A ˚ , c ¼ 24:876ð4Þ A ˚ , Z ¼ 8, V ¼ 1991:2ð7Þ A ˚ 3 , and D X ¼ 1:442 g cm 3 . Crystal structure was solved with a final R ¼ 0:054 for 3305 independent reflections. The atomic arrangement coaled described as H 2 PO 4  layers between which are located the 4-ethylanilinium cations. # 2003 Elsevier Science Ltd. All rights reserved. Keywords: C. X-ray diffraction; D. Crystal structure; C. Nuclear magnetic resonance (NMR) 1. Introduction In organic-cation monophosphates, the phosphate anions generally observed are the acidic ones [HPO 4 ] 2 or [H 2 PO 4 ]  . Such anions are interconnected by strong hydrogen bonds so as to build infinite networks with various geometries: ribbons [1], chains [2,3], two-dimensional network [4–6], and three-dimensional network [7]. These entities can be associated to organic molecules to produce compounds having a particular interest as non-linear optical materials. In the present investigation we report the synthesis and crystal structure of a new organic-cation diacidic dihydrogenomonopho- sphate (4-C 2 H 5 C 6 H 4 NH 3 )H 2 PO 4 . The characterization by 31 P solid state NMR spectroscopy is also reported. Materials Research Bulletin 38 (2003) 741–747 * Corresponding author. Tel.: þ216-2-591-906; fax: þ216-2-590-566. E-mail address: Cherif.BenNasr@fsb.rnu.tn (M. Rzaigui). 0025-5408/03/$ – see front matter # 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0025-5408(03)00072-2