Houcine Naïli

Potassium gadolinium polyphosphate, KGd(PO3)4

Potassium gadolinium polyphosphate, KGd(PO(3))(4), was synthesized using the flux method. The atomic arrangement consists of an infinite long-chain polyphosphate organization. Two types of chains, with a period of eight PO(4) tetrahedra, run along the [101] direction. The Gd atoms have an eightfold coordination, while the K atoms have nine O-atom neighbours.

Crystal structure, characterisation and vibrational study of a mixed compound Cs0.4Rb0.6H2PO4

Abstract The crystal structure of Cs1-x Rb x H2PO4, x = 0.6 (CRDP) which crystallises in space group P21/m and is isostructural with the monoclinic phase of CsH2PO4 (CDP), has been refined at room temperature using single-crystal X-ray diffractometer data. The cell parameters are a = 4.8183(9)å, b = 6.2671(6) å, c = 7.7620(10)å, β= 108.260(10)°, V = 222.58(5)å3, Z = 2, Dx = 3.009g cm−3. F(000)=187, T = 298(2)K (room-temperature phase), R = 0.0355 and wR = 0.0949 for 654 observed reflections. CRDP contains two crystallography inequivalent hydrogen bonds in the unit cell. The shorter bond (Ko – o = 2.453(7) A) links the phosphate groups into chains running along the b-axis and the longer bond (Ko – o = 2.488(6) A) which is always ordered, crosslinks the chains to form (001) layers. The phase transitions in the mixed Cs0.4Rb0.6H2PO4 (CRDP) were characterised by differential scanning calorimetry which shows two anomalies at about 293 and 525 K. The Raman and infrared spectra at room temperature were investigated in the frequency ranges 10–3500 and 200–4000 cm−1 respectively. An assignment of all the bands is given. The bands are in agreement with the monoclinic room-temperature phase implying high dynamical disorder of the acidic proton O-H s–O hydrogen bond.

Preparation, crystal structure, and physical characterization of a new hybrid material (C5H9N3)ZnCl4·H2O

An organic–inorganic hybrid compound (C5H9N3)ZnCl4 · H2O was synthesized by slow evaporation and characterized by single-crystal X-ray diffraction, differential scanning calorimetry, thermogravimetry, temperature-dependent X-ray powder diffraction, infrared spectroscopy, and some preliminary theoretical calculations of non-linear optic activity. The compound crystallizes in the non-centrosymmetric space group Pca21 with unit cell parameters: a = 22.714(5), b = 7.313(5), c = 7.301(5) Å, Z = 4, and V = 1212.8(12) Å3. The structure was solved using direct methods and refined by least-squares analysis [R 1 = 0.0484 and wR 2 = 0.1255]. It is built from isolated [ZnCl4]2− anions, 2,5-diaminopyridinediium [C5H9N3]2+ cations, and water molecules which are connected by a 3-D hydrogen-bond network. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through four stages leading to a new crystalline anhydrous phases.

Piperazinediium Diselenatohexaaquacobaltate(II) Dihydrate (C4H12N2)[Co(SeO4)2(H2O)4]·2H2O

The new hybrid material, (C4H12N2)[Co(H2O)4(SeO4)2]·2H2O, has been synthesized by the slow evaporation method at room temperature and crystallographically characterized. It crystallizes in the monoclinic system, space group P21 /n. The crystal structure of this compound consists of transition metal, Co(II), octahedrally coordinated by four water molecules and two selenate groups forming the [Co(H2O)4(SeO4)2]2- anions, water molecules and piperazinediium cations (C4H12N2)2+ linked together by two types of hydrogen bonds, OW–H…O and N–H…O.

Ethyl­enediammonium tetraaquadi­sulfatomagnesium(II)

The title compound, [NH3(CH2)2NH3][Mg(SO4)2(H2O)4], was synthesized by the slow evaporation method. Its crystal structure can be described as an alternate stacking of inorganic layers of tetraaquabis(sulfato-O)magnesium [Mg(SO4)2(H2O)4]2− anions ( symmetry) and organic layers of [NH3(CH2)2NH3]2+ cations along the crystallographic b axis. The anions, built up from tetrahedral SO4 units and octahedral Mg(H2O)4O2 units, and the cations are linked together through N—H⋯O hydrogen bonds, forming a three-dimensional network. O—H⋯O interactions are also present.

Inorganic layered structures in hybrid double sulfates: related phases and thermal reactivity

The use of benzimidazole as an aromatic diamine template in the synthesis of a series of hybrid double sulfate salts containing transition metals provided a new structure topology that gathers between the supramolecular aspect and the lamellar aspect, which is not very much encountered in the literature. The obtained materials with the general formula (C7H7N2)2[MII(H2O)6](SO4)2·4H2O (MII = Zn, Cu, Ni, Co) and (C7H7N2)2[Fe(H2O)6](SO4)2·3H2O crystallize according to the triclinic symmetry (S.G. P) and to the monoclinic symmetry (S.G. P21/n), respectively. The mineral layer is built from sulfate (SO4), hexaaquametal-complex[MII(H2O)6] and free H2O molecules, linked together by hydrogen bonds only. The aromatic amines are intercalated between the inorganic layers and form chains through π⋯π interactions. The orientation of the amine molecule in two different directions can modify the interlayer space, which is able to vary from 12.3 to 13.2 A depending upon on the nature of the metal. The thermal behaviour of the five metal compounds, studied by TDXD and TG, shows a good stability of precursors and indicates that the dehydration proceeds differently according to the metal incorporated into the structure leading to the formation of crystalline phases during heating. In particular, the Fe-related compound becomes amorphous when subjected to temperature increase.

Crystal structures of two enantiomorphous 2-ethylpiperazinediium hexaaquacopper sulfates [(R or S)-C5H14N2][Cu(H2O)6](SO4)2

Two new non-centrosymmetric copper sulfates are synthesized under slow evaporation conditions through the use of enantiomorphically pure sources of either (R)-2-methylpiperazine or (S)-2-methylpiperazine. Both crystallize in the non-centrosymmetric P21 space group, crystal data for [(R)-C5H14N2][Cu(H2O)6](SO4)2 (I), a = 6.5276(2) Å, b = 11.1955(3) Å, c = 12.4559(4) Å, β = 101.196(2)°, Z = 2, V = 892.95(5) Å3 and [(S)-C5H14N2][Cu(H2O)6](SO4)2 (II), a = 6.5188(2) Å, b = 11.1786(2) Å, c = 12.4365(3) Å, β = 101.205(1)°, Z = 2, V = 888.99(4) Å3. The three-dimensional structure networks for these compounds consist of isolated [Cu(H2O)6]2+ and [(R)-C5H14N2]2+ or [(S)-C5H14N2]2+ cations and SO 42− anions linked only by hydrogen bonds. The Cu atom is in a slightly distorted octahedral coordination environment. The crystal packings are influenced by cation-to-anion N-H…O and OW-H…O hydrogen bonds leading to an open framework structures.

Crystallisation, thermal analysis and acetal protection activity of new layered Zn(II) hybrid polymorphs

Two new polymorphic mononuclear complexes, with analogous structural formula (C6H9N2)2[Zn(H2O)6](SO4)2·2H2O, of zinc(II) templated by 2-amino-6-methylpyridinium ligand have been discovered. These polymorphic hybrid crystals, which differ only in terms of their crystal structures, were prepared in one-step synthesis under ambient conditions and investigated for their thermal and catalytic properties. Single-crystal X-ray diffraction of the obtained materials revealed that polymorphs 1 and 2 crystallise in the triclinic system, space group P. In an effort to further explore the form diversity of these compounds, the structural arrangements and intermolecular interactions such as hydrogen-bonding and π⋯π interactions are discussed from which supramolecular assembly was formed. Meanwhile, these new polymorphic forms can be described as the stacking of 3D layers where the interlayer distances are 13.23 and 12.59 A for 1 and 2, respectively. The thermal behaviour of the precursors checked by TG-DTA analysis for both zinc sulfate polymorphs and variable temperature powder X-ray diffraction (VT-PXRD) show successive intermediate crystalline anhydrous phases upon dehydration in 1. The catalytic activity of both polymorphic structures has been tested in the acetalisation reaction of aldehydes as a benchmark process. Interestingly, both complexes showed excellent activity with almost total conversion in many examples and using MeOH as solvent and as the unique source of acetalisation.

Noncentrosymmetry in new 2-methylpiperazinediium hexaaquazinc(II) bis(sulfate)

Two new noncentrosymmetric polar zinc sulfates have been synthesized by slow evaporation through the use of enantiomorphically pure sources of either (R)-2-methylpiperazine or (S)-2-methylpiperazine. A centrosymmetric analog was also prepared using a racemic source of the amine. The 3-D structure networks for these compounds consist of isolated [Zn(H2O)6]2+, [C5H14N2]2+, and linked by hydrogen bonds. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers, while using a single enantiomer destroys the inversion symmetry and orders of the amines. These structures were determined using single-crystal X-ray diffraction, infrared spectroscopy, and thermal analyses. Crystal data are as follows: [C5H14N2][Zn(H2O)6](SO4)2 (1), a = 6.5988(1) Å, b = 10.9613(2) Å, c = 12.5479(2) Å, β = 101.385(1)°, V = 889.75(3) Å3, P21/n (No. 14), Z = 2; [(R)-C5H14N2][Zn(H2O)6](SO4)2 (2), a = 10.8665(2) Å, b = 7.8600(1) Å, c = 11.7029(2) Å, β = 116.283(1)°, V = 896.22(3) Å3, P21 (No. 4), Z = 2; [(S)-C5H14N2][Zn(H2O)6](SO4)2 (3), a = 6.5819(2) Å, b = 11.0014(2) Å, c = 12.5229(3) Å, β = 101.489(1)°, V = 888.62(4) Å3, P21 (No. 14), Z = 2.

1-Methyl­piperazine-1,4-diium tetra­chloridozincate hemihydrate

The crystal structure of the title compound, (C5H14N2)[ZnCl4]·0.5H2O, is built up from discrete 1-methylpiperazinediium cations with chair conformation, tetrahedral tetrachloridozincate anions and uncoordinated solvent water molecules linked together by three types of intermolecular hydrogen bonds, viz. N—H⋯Cl, N—H⋯O and O—H⋯Cl.