Abdelaziz Daoud

Structure cristalline et etude par spectrometrie de vibration (IR et Raman) du bis(ethylenediammonium) diphosphate (NH3(CH2)2NH3)2 · P2O7

Abstract Classical methods extensively known for the synthesis of inorganic condensed phosphates are used to give compounds that are intermediate between inorganic and organic. We prepared the title compound to examine the possibility of using, in this new field, the ion exchange resin and Boulle´s methods. Chemical preparation, crystal structure, and vibrational studies are given for a new diphosphate. The bis(ethylenediammonium) diphosphate salt is monoclinic with the unit cell dimensions a = 8.724(1), b = 13.511(2), c = 10.039(1)A, β = 96.25(1)°, V = 1176.3(5)A 3 , D m = 1.673Mg m −3 , D x = 1.684Mg m −3 , μ = 2.163 mm −1 , space group C 2 c with Z = 4. The structure was solved by the Patterson method and refined to a final R value of 0.059 for 2602 observed independent reflections. The P O(L) P bridge is symmetrical with a P O(L) distance of 1.570(1)Aand a POP angle of 141.94(7)°. The P 2 O 4− 7 anions are located around the twofold axis. The ethylenediammonium dications have a trans configuration. Half of them, having a crystallographic inversion center, are located in channels delimited by the diphosphate anions. The others, located around the twofold axis, are sandwiched along the c axis between two diphosphate anions. The cohesion and the stability of the atomic arrangement result from the N H···O hydrogen bonds. The IR and Raman spectra of [NH 3 (CH) 2 NH 3 2 · P 2 O 7 are recorded and analyzed. From the spectra it is inferred that the P 2 O 4− 7 anion has a C 2 symmetry in the crystal; all the POP modes (stretching and bending) are active in IR and Raman.

Disorder and protonic conductivity in RbH(SO4)0.81(SeO4)0.19 mixed crystals

Abstract X-ray diffraction, calorimetry, vibrational and impedance spectroscopy studies of a new protonic conductor with the RbH(SO 4 ) 0.81 (SeO 4 ) 0.19 composition are offered. Crystals of this composition undergo five phase transitions at T =245, 288, 353, 380 and 482K. The transition at 380 K is a superionic–protonic transition (SPT) related to a rapid [HS(Se)O 4 − ]reorientation and fast H + diffusion. A sudden jump in the temperature dependance of conductivity confirms the presence of this transition. Above 380 K, this high temperature phase is characterized by a high electrical conductivity (10 −3 Ω −1 cm −1 ) and low activation energy ( E a

Crystal structure of pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate, (NH3(CH2)2NH3)5(Sb2Cl11)2.4H2O

The pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate salt is monoclinic with the following unit cell dimensions:a=16.271(5) Å,b=13.004(4) Å,c=13.932(4) Å, β=111.72(2)°, space groupP21/c withZ=2. The structure was solved by Patterson methods and refined to a finalR value of 0.023 for 4435 reflections withF0>4σ(F0). The structure shows a layer arrangement perpendicular to thea axis: planes of the [Sb2Cl11]5− bioctahedra alternate with planes of [NH3(CH2)2NH3]2+ dications. The [Sb2Cl11]5− bioctahedra are connected through O−H...Cl hydrogen bonds, such that infinite chains of composition [Sb2Cl11(H2O]n5n− are formed in the structure, parallel to the twofold axis. These chains are themselves interconnected by means of N−H...Cl and O−H...Cl bonds originating from the [NH3(CH2)2NH3]2+ entities and the water molecules, respectively, and form a threedimensional network.

4-Benzyl-pyridinium hydrogen selenate.

The structure of the title salt, C12H12N+·HSeO4 −, consists of infinite parallel two-dimensional planes built of 4-benzylpyridinium and hydrogen selenate ions that are mutually connected by strong O—H⋯O and N—H⋯O hydrogen bonds. There are no contacts other than normal van der Waals interactions between the layers.

Crystal structure of mixed rubidium–ammonium hydrogen sulfate Rb0.7(NH4)0.3HSO4 at room temperature

The structure of Rb0.7(NH4)0.3HSO4 has been determined by X-ray analysis. The mixed compound crystallizes in the monoclinic space group P21/n with unit cell parameters a = 14.374(6) Å, b = 4.618(6) Å, c = 14.412(2) Å, β = 118.03(2)°, V = 844.4(4) Å3, and Dcal = 1.536 g cm−3 for Z = 8. The mixed compound Rb0.7(NH4)0.3HSO4 is a chain-based structure. The Rb+ and NH4+ cations are intercalated between chains, formed of HSO4- groups linked with OH⋯O hydrogen-bonding. Rb0.7(NH4)0.3HSO4 presents a new type of structural arrangement different from those of pure RbHSO4 and NH4HSO4.