G. Nowogrocki

Structural studies of CsKBi mixed chlorides relation to the crystal structures of A2BMX6, A3MX6, and A2MX6

Abstract The room-temperature crystal structures of Cs3BiCl6(I) and CsK2BiCl6(II) have been determined from X-ray single-crystal data. These compounds are both monoclinic, space group C2 c , with eight formula units per cell and cell parameters a = 27.017(17), b = 8.252(8), c = 13.121(10) A, β = 99.70(11)° (I), a = 25.653(13), b = 7.799(5), c = 12.874(9) A, β = 99.24(8)° (II). The crystal structures have been refined to final R values of 0.069(I) and 0.044(II) from 1706(I) and 2008(II) independent reflections and 93 variable parameters. The BiCl6 octahedra are slightly distorted (average dBiue5f8Cl = 2.699 A) and the alkaline cations are coordinated with eleven or eight chlorine atoms. These structures are better described using the notion of “layers of close-packed octahedra” and can therefore be easily compared with the A2BMX6 (elpasolite type), A3MX6 (cryolite type), and A2MX6 (K2PtCl6 type) crystal structures. In these compounds, the “layers” of isolated octahedral MX6 entities (X = F, Cl, Br, O) define “tetrahedral” and “octahedral” holes, entirely or partially occupied by the A and/or B cations.

Chemical, structural and electrical characterizations in the BIZNVOX family

The BIZNVOX solid solution domain, stable at room temperature, nhas been determined. α-, β- and γ-type compounds can be stabilized ndepending on the x and y values of the general Bi2(V1xa0−xa0xxa0−xa0yZnxBiy)Oz nformula. The α- and β-type phases exhibit incommensurate modulations nstudied by X-ray powder diffraction. The lock-in of their wave vectors non the three-fold and two-fold superstructures of the undoped α- nand β-Bi4V2O11, respectively, is clearly nevidenced. SAEDand HREM observations reveal very complex disorder correlated nwith the attractive oxide ion conductivity of these materials.

N-[(Ethyl-1 pyrrolidinyl-2) méthyl] méthoxy-2 sulfamoyl-5 benzamide (sulpiride)

CIsH23N304S, triclinic, P i , Z = 2, a = 11.173(2), b = 9.082(2), c = l l . 2 9 5 ( 2 ) / k , a = 90 .5 (1 ) , f l = 130.9(1), 7 = 100.1 (1)°; De= 1.34, D m = 1.34 Mg m -3. The structure was solved by direct methods and refined by a full-matrix least-squares procedure to a final R value of 0.077 for 1622 observed 0567-7408/81/040981-04501.00 reflexions using Cu Ka radiation. The molecule of sulpiride is in extended configuration. A partial disorder was observed around the amide function. Hydrogen bonds occur between the H atoms of the sulfamoyl group and the amide function and the pyrrolidinyl group of two different molecules.

Crystal structure determination and stability of copper (II) hydroxymethylphosphonate dihydrate

Abstract Copper(II) hydroxymethylphosphonate dihydrate HOCH2PO3Cu, 2 H2O is triclinic : a = 10.870(3), b = 5.130(2), c = 5.628(2) A , α = 96.6(1)β = 114.6(1), γ = 97.2(1)°, S.G. Pl, Z = 2. The structure was solved by the heavy atom method and full matrix least-squares refinement to a final R value = 0.035. The two Cu atoms in the cell are structurally different : Cu(1) is octahedrally surrounded by four phosphonate oxygen atoms and two hydroxyl groups. Cu(1)O6 octahedra chains extend along [010]. Cu(2) is coordinated to two phosphonate oxygen atoms and four water molecules. Cu(2)O6 octahedra link the chains to form infinite layers parallel to [101]. These layers are held together by means of hydrogen bonds. The right formula must therefore be written [Cu(HOCH2PO3)2] Cu, 4 H2O. The greater stability of the octahedral configuration versus the t.b.p. one and the occurence of bonding between copper atoms and hydroxyl groups can explain the increase of stability observed from methylphosphonate to hydroxymethylphosphonate copper complexes.