R. Masse

Quadratic nonlinear-optical properties of a new transparent and highly efficient organic-inorganic crystal : 2-amino-5-nitropyridinium-dihydrogen phosphate [2A5NPDP]

Linear and quadratic nonlinear-optical (NLO) properties of a new organic–inorganic crystal, 2-amino-5-nitro-pyridinium-dihydrogen phosphate (2A5NPDP), are reported. 2A5NPDP was designed to display high NLO efficiency by incorporating highly polarizable organic molecules arranged in a polar order between phosphate polyanion sheets. The material is transparent in the visible and the near-IR (from 0.42 to 2 μm) with favorable phase-matching (PM) conditions for second-harmonic generation in the 1-μm region. Crystal nonlinear coefficients responsible for PM were determined by the Maker fringe method, leading at 1.06 μm to d15 ≅ 7.2 pm/V and d24 ≅ 1.3 pm/V. The measured crystal coefficients significantly depart from oriented gas model calculations based on molecular hyperpolarizability values measured in an aprotic solution, thus suggesting important crystal-field effects and protonation contributions. Thermal sensitivity of the PM angle at 1.34 μm is found to be 155″/°C, which is considerably larger than typical values of inorganic NLO crystals and opens the way to efficient thermal tuning of phase-matched processes.

An inorganic complex of silver (III): K5Ag(IO5OH)2 · 8H2O

Abstract The chemical preparation and crystal structure of the trivalent silver salt K5Ag(IO5OH)2 · 8H2O are described (monoclinic, space group Cc; a = 21.79(4), b = 6.320(3), c = 15.16(3) A, β = 96.14(4); four formula units per unit cell). The structure is refined until R = 0.033 for 2718 reflections. Isolated Ag(IO5OH)5−2 units occur, which contain trivalent silver ions surrounded by four oxygen atoms from two IO6 octahedra in rectangular configuration. The differences in the IO bond lengths, as well as the small deviations of the crystal structure from centrosymmetry, are in agreement with an antiperiplanar position of the OH groups in both octahedra.

Contribution to the crystal chemistry of MIMIIPO4 monophosphates (MI = K, Rb, Cs; MII = Be)

Abstract Single-crystal growth experiments and crystal structures of KBePO 4 , RbBePO 4 , and CsBePO 4 are reported. KBePO 4 is orthorhombic, Pc 2 1 n , with a = 8.506(4), b = 4.937(4), c = 8.344(5) A, and Z = 4. RbBePO 4 is orthorhombic, Pcmn or Pc 2 1 n , with a = 8.636(3), b = 5.012(2), c = 8.587(3) A, and Z = 4. CsBePO 4 is orthorhombic, Pnam with a = 8.713(4), b = 8.836(5), c = 5.147(4) A, and Z = 4. The crystal structures of KBePO 4 and CsBePO 4 have been solved with respective final R values of 0.043 (472 reflections) and 0.027 (717 reflections). They are closely related to that of β-tridymite.

Crystal structures of phosphomolybdyl salts: Pb(MoO2)2(PO4)2 and Ba(MoO2)2(PO4)2

Abstract Crystal structures of Pb(MoO 2 ) 2 (PO 4 ) 2 and Ba(MoO 2 ) 2 (PO 4 ) 2 were determined. Both compounds contain the molybdyl group MoO 2 . The monoclinic unit-cell parameters are a = 6.353(7), b = 12.289(4), c = 11.800 A, β = 92°56(6), and Z = 4 for the lead salt and a = 6.383(8), b = 7.142(7), c = 9.953(8) A, β = 95°46(8), and Z = 2 for the barium salt. P2 1 c is the common space group. The R values are respectively R = 0.027 and R = 0.031 for 1964 and 1714 independent reflections. The frameworks built up by a three-dimensional network of monophosphate PO 4 and molybdyl MoO 2 groups are similar, characterized mainly by corner-sharing PO 4 and MoO 6 polyhedra. Two oxygen atoms of each MoO 6 group are bonded to the molybdenum atom only as in other molybdyl salts.

Chemical preparation and crystal structure refinement of KBaPO4 monophosphate

Abstract Single-crystal preparation of KBaPO4 is reported. KBaPO4 is orthorhombic, Pnma, with a = 7.709(4), b = 5.663(4), c = 9.972(5) A and Z = 4. The β-K2SO4-like model previously proposed for this salt from X-ray powder data is confirmed by the present single-crystal study. R = 0.016 for 970 reflections.

Pre´paration chimique et structure cristalline de l'iodate d'argent AgIO3

Abstract A new chemical preparation of silver iodate AgIO3 is given. The crystal structure has been determined by single-crystal X-ray diffraction methods and refined to a finalR value of 0.051 for 1280 independent reflections. The unit cell is orthorhombic witha = 7.265(2), b = 15.17(4), c = 5.786(2)A˚,Z = 8. The space group isPbc21. IO3 groups and AgO6 octaedra form a compact bidimensional framework perpendicular to theb axis.

Structure cristalline du monophosphate AgHg2PO4. Données cristallographiques sur AgHg2AsO4

Abstract Crystal structure of AgHg2PO4 has been determined by single crystal X-ray diffraction methods. The unit cell is orthorombic with a = 9.256(2), b = 8.614(2), c = 6.152(2) A, Z = 4. The space group is Pbam. The structure is built of individual tetraedra PO4 bridged with a pair of atoms HgHg and AgAg. AgHg2AsO4 is isostructural with AgHg2PO4. Crystal data are given for this last salt.

The 2-methyl 4-nitroanilinium dihydrogenmonophosphate, C7H9N2O+2 · H2PO−4, a layer structure which evidences the structural properties of (H2PO−4)n flexible polyanion

Abstract Chemical preparation and crystal structure of the 2-methyl 4-nitroanilinium dihydrogenmonophosphate are described. The cell constants are: a = 32.16(5), b = 8.230(6), c = 8.056(6)A, z= 8, space group Pbca. This layer structure is compared through its anionic network to various alkyl and aryl ammonium dihydrogenmonophosphates. A procedure for the crystal engineering of a new class of ferroic materials is suggested.

Structure cristalline du nitro-phosphate mercureux: Hg4PO4NO3,H2O

Hg 4 PO 4 NO 3 ,H 2 O is monoclinic, P2 1/n , with a = 18.38(9), b = 8.258(3), c = 5.952(2)A, β = 91°2(1), with Z = 4. The crystal structure was solved from single-crystal diffractometer data by direct method and refined by a least-squares method. The structure is built of individual PO 4 and NO 3 anions and water molecules bridged by Hg Hg pairs.

A copper (III) periodate peroxo complex: K4H4Cu(IO6)2O2 · 6H2O

Abstract The chemical preparation and crystal structure of the trivalent copper salt K4H4Cu(IO6)2O2 · 6H2O are described. Crystals are monoclinic (space group P2 1 n ; a = 12.650(2), b = 9.780(2), c = 7.710(2) A, β = 95.2°(1), Z = 2). The structure is refined until R = 0.038 for 2223 reflections. Isolated Cu(IO6)7−2 units and O−2 superoxide groups occur. In the Cu(IO6)7−2 unit, the trivalent copper ion is surrounded by four oxygen atoms in a rectangular configuration.