http://journals.iucr.org/b/issues/2008/06/00/isscontsbdy.html Acta Crystallographica Section B: Structural Science publishes papers in which structure is the primary focus of the work reported. The central themes of Structural Science are the acquisition of structural knowledge from novel experimental observations or from existing data, the correlation of structural knowledge with physico-chemical and other properties, and the application of this knowledge to solve problems in the structural domain. Structural Science has broad chemical coverage, encompassing metals and alloys, inorganics and minerals, metal-organics and purely organic compounds. en Copyright (c) 2008 International Union of Crystallography 2008-12-01 International Union of Crystallography International Union of Crystallography http://journals.iucr.org urn:issn:0108-7681 Acta Crystallographica Section B: Structural Science publishes papers in which structure is the primary focus of the work reported. The central themes of Structural Science are the acquisition of structural knowledge from novel experimental observations or from existing data, the correlation of structural knowledge with physico-chemical and other properties, and the application of this knowledge to solve problems in the structural domain. Structural Science has broad chemical coverage, encompassing metals and alloys, inorganics and minerals, metal-organics and purely organic compounds. text/html Acta Crystallographica Section B: Structural Science, Volume 64, Part 6, 2008 text yearly 6 2002-02-01T00:00+00:00 6 64 2008-12-01 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science 645 urn:issn:0108-7681 med@iucr.org December 2008 2008-12-01 http://journals.iucr.org/logos/rss10b.gif http://journals.iucr.org/b/issues/2008/06/00/isscontsbdy.html Still image http://scripts.iucr.org/cgi-bin/paper?bp5013 Dioxotetrafluorotungstates (NH4)2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W—O and W—F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Udovenko, A.A. Laptash, N.M. 2008-11-14 doi:10.1107/S0108768108033053 International Union of Crystallography Orientational disorder in Rb2WO2F4 and (NH4)2WO2F4 have been compared. In the ammonium compound, but not in the rubidium compound, it was possible to distinguish between O and F atoms in the distorted cis-[WO2F4]2 octahedron and to determine its true geometry owing to the dynamic nature of the disorder. The ammonium compound undergoes phase transitions of the order–disorder type when the temperature is lowered but the rubidium compound does not. en oxofluorotungstates dynamic and static orientational disorder reorientation motions NMR Raman spectra phase transition twin structure Dioxotetrafluorotungstates (NH4)2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W—O and W—F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature. text/html Disorder in crystals of dioxofluorotungstates, (NH4)2WO2F4 and Rb2WO2F4 text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 645 651 http://scripts.iucr.org/cgi-bin/paper?sn5072 The structure of YbV4O8 is related to the CaFe2O4 structure type. VO6 octahedra form a three-dimensional framework with tunnels in which the Yb3+ ions are incorporated. Two different polymorphs α and β are known and differ mainly in the arrangement of the Yb ions within the framework. We studied the structure and magnetic properties of α-YbV4O8 as a function of temperature. At approximately 70 K α-YbV4O8 undergoes a first-order isosymmetrical phase transition (P21/n → P21/n). While in the high-temperature α phase the three V3+ and one V4+ are disordered over the four symmetrically independent octahedral sites, in the low-temperature α′ phase complete charge ordering is observed. The transition is accompanied by a paramagnetic–paramagnetic anomaly in the magnetic susceptibility data which can be interpreted on the basis of spin-gap formation. The transition mechanism in the α polymorph is very similar to that observed earlier in the β polymorph at 185 K. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Friese, K. Kanke, Y. Fitch, A.N. Morgenroth, W. Grzechnik, A. 2008-10-10 doi:10.1107/S0108768108026153 International Union of Crystallography The mixed-valence vanadate α-YbV4O8 undergoes an isosymmetrical phase transition at 70 K. The transition is accompanied by a paramagnetic–paramagnetic anomaly and leads to complete charge ordering. en phase transition polymorphism magnetic properties charge ordering The structure of YbV4O8 is related to the CaFe2O4 structure type. VO6 octahedra form a three-dimensional framework with tunnels in which the Yb3+ ions are incorporated. Two different polymorphs α and β are known and differ mainly in the arrangement of the Yb ions within the framework. We studied the structure and magnetic properties of α-YbV4O8 as a function of temperature. At approximately 70 K α-YbV4O8 undergoes a first-order isosymmetrical phase transition (P21/n → P21/n). While in the high-temperature α phase the three V3+ and one V4+ are disordered over the four symmetrically independent octahedral sites, in the low-temperature α′ phase complete charge ordering is observed. The transition is accompanied by a paramagnetic–paramagnetic anomaly in the magnetic susceptibility data which can be interpreted on the basis of spin-gap formation. The transition mechanism in the α polymorph is very similar to that observed earlier in the β polymorph at 185 K. text/html Isosymmetrical phase transition in α-YbV4O8 text 6 64 2008-10-10 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 652 660 http://scripts.iucr.org/cgi-bin/paper?bp5014 Synthetic Co2SiO4 has an olivine structure with isolated SiO4 groups (space group Pnma) and shows magnetic ordering below 50 K. Single-crystal neutron diffraction was applied to determine precise crystal structure parameters at low temperatures. No structural phase transition was revealed in the temperature range 2.5–300 K. Lattice parameters were determined by high-resolution X-ray powder diffraction between 15 and 300 K. There is a clear evidence of an anomalous thermal expansion related to the magnetic phase transition which can be attributed to magnetostriction. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Sazonov, A. Meven, M. Hutanu, V. Kaiser, V. Heger, G. Trots, D. Merz, M. 2008-11-14 doi:10.1107/S010876810803214X International Union of Crystallography The crystal structure of the synthetic cobalt olivine, Co2SiO4, is determined by means of single-crystal neutron diffraction and X-ray powder diffraction in the temperature range 300–2.5 K. en olivine structure low temperature phase transitions thermal expansion Synthetic Co2SiO4 has an olivine structure with isolated SiO4 groups (space group Pnma) and shows magnetic ordering below 50 K. Single-crystal neutron diffraction was applied to determine precise crystal structure parameters at low temperatures. No structural phase transition was revealed in the temperature range 2.5–300 K. Lattice parameters were determined by high-resolution X-ray powder diffraction between 15 and 300 K. There is a clear evidence of an anomalous thermal expansion related to the magnetic phase transition which can be attributed to magnetostriction. text/html Structural behaviour of synthetic Co2SiO4 at low temperatures text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 661 668 http://scripts.iucr.org/cgi-bin/paper?ck5034 Prismatic crystals of the title compound, up to 100 µm long and {001} twinned by metric merohedry, were obtained as a side-product of a hydrothermal run devoted to synthesizing the heterophyllosilicate lamprophyllite. Single-crystal X-ray diffraction data were collected on a Bruker-AXS Smart Apex diffractometer from a crystal with approximate composition (Ba0.80Sr0.20)4Ti6Si4O24·H2O. The structure was solved and refined as a disordered structure in the space group Cmmm [ao = 5.906 (2), bo = 20.618 (8), co = 16.719 (6) Å, R = 0.089 for 682 reflections with Io > 2σ(Io)], and then deciphered by the order–disorder (OD) theory as an ordered structure and refined in the space group P2/c [a = 5.906, b = 16.719, c = 10.724 Å, β = 105.99°, R = 0.083 for 1090 reflections with Io > 2σ(Io)]. The discussion based on the OD theory shows that the refined ordered structure corresponds to one (2M) of two maximum degree of order (MDO) polytypes. The structure of the second MDO polytype (4O) was modelled but not refined because it does not substantially occur in our sample. In the structure, infinite (001) ribbons of Ti octahedra elongated along the [100] direction are connected by (SiO3)4 four-membered rings, thus realising a new type of heteropolyhedral framework. The ribbons are three-octahedra wide and one-octahedron thick; they are formed by linking, via edge-sharing, rutile-type edge-sharing rows of octahedra. This ribbon represents a slice of the octahedral sheet that occurs in perrierite-(Ce), Ce4MgFe2Ti2O8(Si2O7)2. The (Ba,Sr) ions are hosted within two independent [100] narrow channels both delimited by four Ti octahedra and four Si tetrahedra. The disorder of H2O is discussed on the basis of a Raman spectrum. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Cadoni, M. Bloise, A. Ferraris, G. Merlino, S. 2008-11-08 doi:10.1107/S0108768108032631 International Union of Crystallography The ordered P2/c structure of (Ba,Sr)4Ti6Si4O24·H2O was obtained first by solving the disordered Cmmm structure by single-crystal X-ray diffraction data and then applying the order–disorder theory. en titanosilicate order–disorder theory polytypism twinning metric merohedry heteropolyhedral structure Prismatic crystals of the title compound, up to 100 µm long and {001} twinned by metric merohedry, were obtained as a side-product of a hydrothermal run devoted to synthesizing the heterophyllosilicate lamprophyllite. Single-crystal X-ray diffraction data were collected on a Bruker-AXS Smart Apex diffractometer from a crystal with approximate composition (Ba0.80Sr0.20)4Ti6Si4O24·H2O. The structure was solved and refined as a disordered structure in the space group Cmmm [ao = 5.906 (2), bo = 20.618 (8), co = 16.719 (6) Å, R = 0.089 for 682 reflections with Io > 2σ(Io)], and then deciphered by the order–disorder (OD) theory as an ordered structure and refined in the space group P2/c [a = 5.906, b = 16.719, c = 10.724 Å, β = 105.99°, R = 0.083 for 1090 reflections with Io > 2σ(Io)]. The discussion based on the OD theory shows that the refined ordered structure corresponds to one (2M) of two maximum degree of order (MDO) polytypes. The structure of the second MDO polytype (4O) was modelled but not refined because it does not substantially occur in our sample. In the structure, infinite (001) ribbons of Ti octahedra elongated along the [100] direction are connected by (SiO3)4 four-membered rings, thus realising a new type of heteropolyhedral framework. The ribbons are three-octahedra wide and one-octahedron thick; they are formed by linking, via edge-sharing, rutile-type edge-sharing rows of octahedra. This ribbon represents a slice of the octahedral sheet that occurs in perrierite-(Ce), Ce4MgFe2Ti2O8(Si2O7)2. The (Ba,Sr) ions are hosted within two independent [100] narrow channels both delimited by four Ti octahedra and four Si tetrahedra. The disorder of H2O is discussed on the basis of a Raman spectrum. text/html Order–disorder character and twinning in the structure of a new synthetic titanosilicate: (Ba,Sr)4Ti6Si4O24·H2O text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 669 675 http://scripts.iucr.org/cgi-bin/paper?sn5073 A structural phase transition is shown around 400 K for the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62. This transition is related to a rearrangement of the central [CoO] layer of the [Ca2CoO3] slab of this structure, characterized by a commensurate intrinsic modulation q2 = 2\over 3a* − 1\over 3c*. The partial residual disorder related to split Co and O atomic sites along the misfit b direction disappears and one can describe this layer with its triple chains as a modulated configuration with a regular and not distorted periodicity along b. This phase transition is associated with small changes observed in the transport and magnetic properties as a function of temperature. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Muguerra, H. Grebille, D. 2008-11-08 doi:10.1107/S0108768108030152 International Union of Crystallography A structural phase transition is shown around 400 K for the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62. This transition is related to a rearrangement of the central [CoO] layer of the [Ca2CoO3] slab. en disorder–order magnetic properties commensurate intrinsic modulation A structural phase transition is shown around 400 K for the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62. This transition is related to a rearrangement of the central [CoO] layer of the [Ca2CoO3] slab of this structure, characterized by a commensurate intrinsic modulation q2 = 2\over 3a* − 1\over 3c*. The partial residual disorder related to split Co and O atomic sites along the misfit b direction disappears and one can describe this layer with its triple chains as a modulated configuration with a regular and not distorted periodicity along b. This phase transition is associated with small changes observed in the transport and magnetic properties as a function of temperature. text/html Original disorder–order transition related to electronic and magnetic properties in the thermoelectric misfit phase [Ca2CoO3][CoO2]1.62 text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 676 683 http://scripts.iucr.org/cgi-bin/paper?sn5074 The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Elcoro, L. Perez-Mato, J.M. Friese, K. Petříček, V. Balić-Žunić, T. Olsen, L.A. 2008-11-08 doi:10.1107/S0108768108031492 International Union of Crystallography The use of the superspace formalism is extended to the analysis and refinement of homologous series of modular structures, with two symmetry-related modules. This approach has been successfully applied to the lillianite homologous series. en modulated structures homologous series superspace formalism misfit compound The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated composite description with two basic subsystems corresponding to the two different modules, it is shown how a more efficient description can be achieved using so-called zigzag modulation functions. These linear zigzag modulations, newly implemented in the program JANA2006, have very large fixed amplitudes and introduce in the starting model the two orientations of the underlying module sublattices. We show that a composite approach with this type of function, which treats the cations and anions as two separate subsystems forming a misfit compound, is the most appropriate and robust method for the refinements. text/html Modular crystals as modulated structures: the case of the lillianite homologous series text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 684 701 http://scripts.iucr.org/cgi-bin/paper?wf5033 In this study a total of 186 complex halide systems were collected; the formabilities of ABX3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. A model for halide perovskite formability was built up. In this model obtained, for all 186 complex halides systems, only one system (CsF–MnF2) without perovskite structure and six systems (RbF–PbF2, CsF–BeF2, KCl–FeCl2, TlI–MnI2, RbI–SnI2, TlI–PbI2) with perovskite structure were wrongly classified, so its predicting accuracy reaches 96%. It is also indicated that both the tolerance factor and the octahedral factor are a necessary but not sufficient condition for ABX3 halide perovskite formability, and a lowest limit of the octahedral factor exists for halide perovskite formation. This result is consistent with our previous report for ABO3 oxide perovskite, and may be helpful to design novel halide materials with the perovskite structure. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Li, C. Lu, X. Ding, W. Feng, L. Gao, Y. Guo, Z. 2008-11-14 doi:10.1107/S0108768108032734 International Union of Crystallography A total of 186 complex halide systems were collected; the formabilities of ABX3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. en halide perovskites tolerance factor octahedral factor In this study a total of 186 complex halide systems were collected; the formabilities of ABX3 (X = F, Cl, Br and I) halide perovskites were investigated using the empirical structure map, which was constructed by Goldschmidt's tolerance factor and the octahedral factor. A model for halide perovskite formability was built up. In this model obtained, for all 186 complex halides systems, only one system (CsF–MnF2) without perovskite structure and six systems (RbF–PbF2, CsF–BeF2, KCl–FeCl2, TlI–MnI2, RbI–SnI2, TlI–PbI2) with perovskite structure were wrongly classified, so its predicting accuracy reaches 96%. It is also indicated that both the tolerance factor and the octahedral factor are a necessary but not sufficient condition for ABX3 halide perovskite formability, and a lowest limit of the octahedral factor exists for halide perovskite formation. This result is consistent with our previous report for ABO3 oxide perovskite, and may be helpful to design novel halide materials with the perovskite structure. text/html Formability of ABX3 (X = F, Cl, Br, I) halide perovskites text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 702 707 http://scripts.iucr.org/cgi-bin/paper?zb5001 The single-crystal diffraction study of Ce10W22O81 and powder X-ray diffraction (XRD) experiments on Ce10W22O81 and Nd10W22O81 show that the true space group of these phases is Pbnm, contrary to the previous literature reports of the space groups Pbcn and Pbcm for the rare-earth tungstates (RE = La, Ce, Pr, Nd) with this general formula. The structure contains rare-earth cations in seven-, eight- and ninefold coordination. W atoms are found in corner-sharing WO5 groups, and also in WO6 and WO7 polyhedra which share edges and corners to form W6O17 units. The new model obtained from our single-crystal work gives better agreement with powder XRD data on both Ce10W22O81 and Nd10W22O81, and gives more plausible coordination environments and bond-valence sums. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Barker, R.S. Radosavljevic Evans, I. 2008-11-14 doi:10.1107/S0108768108033430 International Union of Crystallography The single-crystal X-ray diffraction study of Ce10W22O81 and powder X-ray diffraction experiments on Ce10W22O81 and Nd10W22O81 show that the true space group of these phases is Pbnm. en rare-earth tungstates X-ray diffraction bond-valence sum coordination environments The single-crystal diffraction study of Ce10W22O81 and powder X-ray diffraction (XRD) experiments on Ce10W22O81 and Nd10W22O81 show that the true space group of these phases is Pbnm, contrary to the previous literature reports of the space groups Pbcn and Pbcm for the rare-earth tungstates (RE = La, Ce, Pr, Nd) with this general formula. The structure contains rare-earth cations in seven-, eight- and ninefold coordination. W atoms are found in corner-sharing WO5 groups, and also in WO6 and WO7 polyhedra which share edges and corners to form W6O17 units. The new model obtained from our single-crystal work gives better agreement with powder XRD data on both Ce10W22O81 and Nd10W22O81, and gives more plausible coordination environments and bond-valence sums. text/html Structural characterization of RE10W22O81 rare-earth tungstates (RE = Ce, Nd) text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 708 712 http://scripts.iucr.org/cgi-bin/paper?ck5032 The crystal structure of a new phase consisting of the inclusion of the hyperpolarizable molecule p-N,N-dimethylnitroaniline (dimethyl-para-nitroaniline or dmpNA) in the large-pore zeolite mordenite (MOR) has been determined from high-resolution synchrotron powder diffraction at 300 and 90 K. The unit-cell parameters and space group at 300 K are similar to those of as-synthesized mordenite. The crystallographic study indicates that the MOR straight channels are almost fully loaded with molecules that are disordered over eight symmetry-related sites. As expected, the molecules are located in the large 12-membered ring channel, at the intersection with the secondary eight-membered channel with which they might form hydrogen bonds. The elongation axes (and then the dipole moments) of the molecules are slightly tilted (28.57°) from [001]. The configuration found suggests an interaction of dmpNA with framework O atoms through its methyl groups. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Porcher, F. Borissenko, E. Souhassou, M. Takata, M. Kato, K. Rodriguez-Carvajal, J. Lecomte, C. 2008-10-10 doi:10.1107/S0108768108025287 International Union of Crystallography The crystal structure of mordenite zeolite hosting guest molecules of p-N,N-dimethylnitroaniline has been solved by synchrotron powder diffraction. The localization of the molecules in the channel system and the possible stabilizing interactions are discussed and compared with literature results. en zeolite guest–host system synchrotron powder diffraction localization in channel system The crystal structure of a new phase consisting of the inclusion of the hyperpolarizable molecule p-N,N-dimethylnitroaniline (dimethyl-para-nitroaniline or dmpNA) in the large-pore zeolite mordenite (MOR) has been determined from high-resolution synchrotron powder diffraction at 300 and 90 K. The unit-cell parameters and space group at 300 K are similar to those of as-synthesized mordenite. The crystallographic study indicates that the MOR straight channels are almost fully loaded with molecules that are disordered over eight symmetry-related sites. As expected, the molecules are located in the large 12-membered ring channel, at the intersection with the secondary eight-membered channel with which they might form hydrogen bonds. The elongation axes (and then the dipole moments) of the molecules are slightly tilted (28.57°) from [001]. The configuration found suggests an interaction of dmpNA with framework O atoms through its methyl groups. text/html Synchrotron powder diffraction characterization of the zeolite-based (p-N,N-dimethylnitroaniline–mordenite) guest–host phase text 6 64 2008-10-10 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 713 724 http://scripts.iucr.org/cgi-bin/paper?bs5068 Initial attempts to make [Ni(H2O)2(15-crown-5)](NO3)2, i.e. to insert the Ni2+ ion into the 15-crown-5 macrocycle, gave the mono- (two polymorphs) and dihydrate of a co-crystal of [Ni(H2O)6](NO3)2 and 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane = 15C5). Synthetic routes designed to restrict the water available to the Ni2+ cation gave three additional compounds, [Ni(H2O)6](NO3)2-trans-[Ni(H2O)4(MeOH)2](NO3)2·2(15C5), cis-[Ni(H2O)4(NO3)2]-trans-[Ni(H2O)4(NO3)2]·2(15C5) and [Ni(H2O)2(MeCN)(NO3)2]·15C5·MeCN. All five compounds contain Ni2+ ions with two trans aqua ligands. In all six structures these aqua ligands make hydrogen bonds to the 15C5 molecules to form stacks in which the Ni complexes and 15C5 molecules alternate. The structures are surprisingly complicated: all are co-crystals, some are also solvates, and most have Z′ > 1. The target compound was finally prepared by heating pale green crystals of [Ni(H2O)6](NO3)2·15C5·2H2O to over 350 K and then cooling the resulting mixture of yellow crystals and solution to room temperature. Formation of the target compound seems to be favored at higher temperatures by a positive ΔrxnSo and an increased rate of ligand exchange. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Siegler, M.A. Parkin, S. Selegue, J.P. Brock, C.P. 2008-11-14 doi:10.1107/S0108768108034058 International Union of Crystallography The yellow compound [Ni(H2O)2(15C5)](NO3)2, 15C5 = 15-crown-5, has been made by heating pale green crystals of [Ni(H2O)6](NO3)2·15C5·2H2O to over 350 K. While trying to obtain the Ni2+ ion inside the crown ligand five other compounds were prepared, all of which have surprisingly complicated crystal structures organized by the hydrogen-bonded motif ...15C5...H2O—NiII—OH2...15C5...H2O—NiII—OH2.... en crown ligand macrocycles hydrogen bonding ligand exchange Initial attempts to make [Ni(H2O)2(15-crown-5)](NO3)2, i.e. to insert the Ni2+ ion into the 15-crown-5 macrocycle, gave the mono- (two polymorphs) and dihydrate of a co-crystal of [Ni(H2O)6](NO3)2 and 15-crown-5 (1,4,7,10,13-pentaoxacyclopentadecane = 15C5). Synthetic routes designed to restrict the water available to the Ni2+ cation gave three additional compounds, [Ni(H2O)6](NO3)2-trans-[Ni(H2O)4(MeOH)2](NO3)2·2(15C5), cis-[Ni(H2O)4(NO3)2]-trans-[Ni(H2O)4(NO3)2]·2(15C5) and [Ni(H2O)2(MeCN)(NO3)2]·15C5·MeCN. All five compounds contain Ni2+ ions with two trans aqua ligands. In all six structures these aqua ligands make hydrogen bonds to the 15C5 molecules to form stacks in which the Ni complexes and 15C5 molecules alternate. The structures are surprisingly complicated: all are co-crystals, some are also solvates, and most have Z′ > 1. The target compound was finally prepared by heating pale green crystals of [Ni(H2O)6](NO3)2·15C5·2H2O to over 350 K and then cooling the resulting mixture of yellow crystals and solution to room temperature. Formation of the target compound seems to be favored at higher temperatures by a positive ΔrxnSo and an increased rate of ligand exchange. text/html The elusive [Ni(H2O)2(15-crown-5)]2+ cation and related co-crystals of nickel(II) hydrates and 15-crown-5 text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 725 737 http://scripts.iucr.org/cgi-bin/paper?bs5069 The structures of five more phases of the structural family of compounds [M(H2O)2(15-crown-5)](NO3)2 have been determined. All of these phases are stable at room temperature or above, but transform to other phases if cooled slowly. All five phase transitions take place without significant damage to the single crystal. The M = Co phase, which has a three-dimensional hydrogen-bonding pattern, is a disordered version of the structure known at room temperature; Z′ changes from 2 to ½. The other four structures have a two-dimensional hydrogen-bonding pattern, are all modulated variants of the same basic cell (or subcell) and are at least mostly ordered. For M = Mg and Zn the structure found somewhat above room temperature is the Z′ = 8 variant found previously for M = Fe. For M = Cu and Ni the Z′ = 2 phase found is the same as seen previously for one of the room-temperature polymorphs with M = Mn. There are now two phases and one transition known for each M studied that has a two-dimensional hydrogen-bonding pattern. The changes in the modulation patterns during these transitions are Z′ 3 ↔ 8 (Mg, Fe, Zn), Z′ 3 ↔ 2 (Mn, Ni) and Z′ 5 ↔ 2 (Cu). In all two-dimensional hydrogen-bonded crystals the alternation pattern of conformational enantiomers along the modulation direction becomes more perfect above the phase transition. All stable [M(H2O)2(15-crown-5)](NO3)2 phases whose existence at accessible temperatures is indicated by differential scanning calorimetry (DSC) have now been characterized. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Siegler, M.A. Hao, X. Parkin, S. Brock, C.P. 2008-11-14 doi:10.1107/S0108768108034046 International Union of Crystallography Structures of five more phases of the [M(H2O)2(15-crown-5)](NO3)2 (M = Mg, Mn, Fe, Co, Ni, Cu and Zn) family have been determined. All stable phases whose existence at accessible temperatures is indicated by differential scannng calorimetry have now been characterized. en phase transitions hydrogen bonding The structures of five more phases of the structural family of compounds [M(H2O)2(15-crown-5)](NO3)2 have been determined. All of these phases are stable at room temperature or above, but transform to other phases if cooled slowly. All five phase transitions take place without significant damage to the single crystal. The M = Co phase, which has a three-dimensional hydrogen-bonding pattern, is a disordered version of the structure known at room temperature; Z′ changes from 2 to ½. The other four structures have a two-dimensional hydrogen-bonding pattern, are all modulated variants of the same basic cell (or subcell) and are at least mostly ordered. For M = Mg and Zn the structure found somewhat above room temperature is the Z′ = 8 variant found previously for M = Fe. For M = Cu and Ni the Z′ = 2 phase found is the same as seen previously for one of the room-temperature polymorphs with M = Mn. There are now two phases and one transition known for each M studied that has a two-dimensional hydrogen-bonding pattern. The changes in the modulation patterns during these transitions are Z′ 3 ↔ 8 (Mg, Fe, Zn), Z′ 3 ↔ 2 (Mn, Ni) and Z′ 5 ↔ 2 (Cu). In all two-dimensional hydrogen-bonded crystals the alternation pattern of conformational enantiomers along the modulation direction becomes more perfect above the phase transition. All stable [M(H2O)2(15-crown-5)](NO3)2 phases whose existence at accessible temperatures is indicated by differential scanning calorimetry (DSC) have now been characterized. text/html Five more phases of the structural family [M(H2O)2(15-crown-5)](NO3)2 text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 738 749 http://scripts.iucr.org/cgi-bin/paper?ws5058 Three l-hydroxylysine structures have been determined at 100 K by single-crystal X-ray diffraction. High-resolution data using either a laboratory or synchrotron source were collected and subjected to invariom- and independent atom-model (IAM) refinements. Anisotropic displacement parameters (ADPs) obtained from invariom refinement were compared (i) with results from a full multipole and (ii) with an IAM high-order refinement. Differences were visualized with the program PEANUT and were complemented by quantitative results from a Hirshfeld test. Influences of scale factor differences, and of refinement against F^2 versus F, have been investigated. Systematic errors were observed in the IAM, especially when only low-order data were available. Although these errors were reduced in high-order IAM refinements, they only disappeared in charge density – and likewise – invariom refinements. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Dittrich, B. McKinnon, J.J. Warren, J.E. 2008-11-08 doi:10.1107/S0108768108032163 International Union of Crystallography Three l-hydroxylysine structures have been determined at 100 K by single-crystal X-ray diffraction to high resolution using a laboratory or synchrotron source. Visualizations of anisotropic displacement parameter (ADP) differences with the program PEANUT indicate the high quality of the invariom ADPs, which are similar to ADPs from a free multipole refinement and superior to ADPs from IAM and high-order IAM refinements. en invariom-model refinements anisotropic displacement parameters charge-density refinements Three l-hydroxylysine structures have been determined at 100 K by single-crystal X-ray diffraction. High-resolution data using either a laboratory or synchrotron source were collected and subjected to invariom- and independent atom-model (IAM) refinements. Anisotropic displacement parameters (ADPs) obtained from invariom refinement were compared (i) with results from a full multipole and (ii) with an IAM high-order refinement. Differences were visualized with the program PEANUT and were complemented by quantitative results from a Hirshfeld test. Influences of scale factor differences, and of refinement against F^2 versus F, have been investigated. Systematic errors were observed in the IAM, especially when only low-order data were available. Although these errors were reduced in high-order IAM refinements, they only disappeared in charge density – and likewise – invariom refinements. text/html Improvement of anisotropic displacement parameters from invariom-model refinements for three l-hydroxylysine structures text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 750 759 http://scripts.iucr.org/cgi-bin/paper?bs5063 Within a research project aimed at the design of new sweeteners, the tetrazole moiety was introduced to arylsulfonylalkanoic acids (ASA) as a bioisostere of the carboxyl group. The crystal structures of four newly synthesized tetrazole derivatives and one intermediate product of the reaction were determined in order to explain the bitter taste of these compounds. Three chiral compounds crystallize as racemic mixtures in centrosymmetric space groups of the monoclinic system, whereas the non-chiral compound, with a higher dipole moment, crystallizes in the polar space group Cc. Intermolecular N—H...N hydrogen bonds between tetrazole moieties were observed in all four structures and are compared with the analogous interactions observed in tetrazole derivatives deposited in the Cambridge Structural Database (CSD). Specifically, the typical N1—H...N4 as well as N1—H...N3 interactions, which are less abundant in the CSD, are described. The formation of the latter interaction type can be hypothetically explained by an asymmetry of π-electron distribution in the tetrazole rings caused by the crystalline environment. Important features of the crystal architecture are the chains of molecules linked by N—H...N bonds. A possible reason for the lack of a sweet taste of the tetrazoles investigated may be the improper position of the tetrazole H atom, and the mutual orientation of the proton donor and acceptor in their molecules. This orientation does not allow the tetrazoles to interact with the sweet-taste receptor in a way similar to that of ASA. The bitter taste of the investigated compounds needs further study. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Kalinowska-Tłuścik, J. Jarzembek, K. Śliwiński, J. Oleksyn, B.J. Kozik, V. Polański, J. 2008-11-08 doi:10.1107/S0108768108027481 International Union of Crystallography The crystal structures of four derivatives of arylsulfonylalkanoids obtained in the course of the syntheses of new artificial sweeteners have been determined and compared with other tetrazole-containing structures identified from a CSD search. The lack of a sweet taste of the four tetrazole derivatives is tentatively explained. en sweeteners tetrazole derivatives arylsulfonylalkanoids hydrogen bonding CSD study Within a research project aimed at the design of new sweeteners, the tetrazole moiety was introduced to arylsulfonylalkanoic acids (ASA) as a bioisostere of the carboxyl group. The crystal structures of four newly synthesized tetrazole derivatives and one intermediate product of the reaction were determined in order to explain the bitter taste of these compounds. Three chiral compounds crystallize as racemic mixtures in centrosymmetric space groups of the monoclinic system, whereas the non-chiral compound, with a higher dipole moment, crystallizes in the polar space group Cc. Intermolecular N—H...N hydrogen bonds between tetrazole moieties were observed in all four structures and are compared with the analogous interactions observed in tetrazole derivatives deposited in the Cambridge Structural Database (CSD). Specifically, the typical N1—H...N4 as well as N1—H...N3 interactions, which are less abundant in the CSD, are described. The formation of the latter interaction type can be hypothetically explained by an asymmetry of π-electron distribution in the tetrazole rings caused by the crystalline environment. Important features of the crystal architecture are the chains of molecules linked by N—H...N bonds. A possible reason for the lack of a sweet taste of the tetrazoles investigated may be the improper position of the tetrazole H atom, and the mutual orientation of the proton donor and acceptor in their molecules. This orientation does not allow the tetrazoles to interact with the sweet-taste receptor in a way similar to that of ASA. The bitter taste of the investigated compounds needs further study. text/html Bitter sweeteners: tetrazole derivatives of arylsulfonylalcanoids – synthesis, structure and comparative study text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 760 770 http://scripts.iucr.org/cgi-bin/paper?dr5021 The crystal structures of the \beta ^{\prime}_1-2, the β′-3 and the β2-3 polymorphs of 1,3-dilauroyl-2-oleoylglycerol have been solved from powder diffraction data. The packing of the β2-3 polymorph is similar to that of other cis mono-unsaturated triacylglycerols. Both the β′ polymorphs are crystallized in a novel type of packing in which one of the saturated lauroyl chains is packed side-by-side with part of the unsaturated oleoyl chain. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 van Mechelen, J.B. Goubitz, K. Pop, M. Peschar, R. Schenk, H. 2008-11-08 doi:10.1107/S0108768108031601 International Union of Crystallography The polymorphism of 1,3-dilauroyl-2-oleoylglycerol has been studied and the structures of the \beta ^{\prime}_1-2, β′-3 and β2-3 polymorphs have been solved from high-resolution powder diffraction data. en triacylglycerols powder diffraction β polymorph The crystal structures of the \beta ^{\prime}_1-2, the β′-3 and the β2-3 polymorphs of 1,3-dilauroyl-2-oleoylglycerol have been solved from powder diffraction data. The packing of the β2-3 polymorph is similar to that of other cis mono-unsaturated triacylglycerols. Both the β′ polymorphs are crystallized in a novel type of packing in which one of the saturated lauroyl chains is packed side-by-side with part of the unsaturated oleoyl chain. text/html Structures of mono-unsaturated triacylglycerols. V. The β′1-2, β′-3 and β2-3 polymorphs of 1,3-dilauroyl-2-oleoylglycerol (LaOLa) from synchrotron and laboratory powder diffraction data text 6 64 2008-11-08 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 771 779 http://scripts.iucr.org/cgi-bin/paper?bs5070 The crystal structures of co-crystals of two systems of chiral carboxylic acids, optically active and racemic 2-phenylpropionic acid and 2-phenylbutyric acid, with isonicotinamide are reported to investigate the effects of the chirality of the chiral carboxylic acids on the melting point of the co-crystal complexes. It was found that the racemic co-crystal has a higher melting point than the optically active co-crystal, which correlates with the denser packing arrangement inherent in centrosymmetric space groups. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Lemmerer, A. Báthori, N.B. Bourne, S.A. 2008-11-14 doi:10.1107/S0108768108034526 International Union of Crystallography The crystal structures of co-crystals of two systems of chiral carboxylic acids, optically active and racemic 2-phenylpropionic acid and 2-phenylbutyric acid, with isonicotinamide are reported to investigate the effects of the chirality of the chiral carboxylic acids on the melting point of the co-crystal complexes. en co-crystals chirality Wallach's Rule carboxylic acids melting-point behaviour The crystal structures of co-crystals of two systems of chiral carboxylic acids, optically active and racemic 2-phenylpropionic acid and 2-phenylbutyric acid, with isonicotinamide are reported to investigate the effects of the chirality of the chiral carboxylic acids on the melting point of the co-crystal complexes. It was found that the racemic co-crystal has a higher melting point than the optically active co-crystal, which correlates with the denser packing arrangement inherent in centrosymmetric space groups. text/html Chiral carboxylic acids and their effects on melting-point behaviour in co-crystals with isonicotinamide text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science research papers 780 790 http://scripts.iucr.org/cgi-bin/paper?ws9067 A replacement Fig. 6 to the paper by Ibberson et al. (2008), Acta Cryst. B64, 573–582 is given. Copyright (c) 2008 International Union of Crystallography urn:issn:0108-7681 Ibberson, R.M. Parsons, S. Allan, D.R. Bell, A.M.T. 2008-11-14 doi:10.1107/S0108768108036197 International Union of Crystallography A corrigendum to the paper by Ibberson et al. (2008), Acta Cryst. B64, 573–582. en neutron powder diffraction low-temperature crystallography hydrogen bonding phase transitions A replacement Fig. 6 to the paper by Ibberson et al. (2008), Acta Cryst. B64, 573–582 is given. text/html Polymorphism in cyclohexanol. Corrigendum text 6 64 2008-11-14 Copyright (c) 2008 International Union of Crystallography Acta Crystallographica Section B: Structural Science addenda and errata 791 791