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General Position (general + position)
Selected AbstractsOn Fodor's Analogy: Why Psychology is Like Philosophy of Science After AllMIND & LANGUAGE, Issue 5 2006DOMINIC MURPHY Peter Carruthers and Stephen Pinker have attacked this analogy between science and ordinary inference. I examine their arguments and show that they fail. This does not show that Fodor's more general position is correct. [source] Three new types of interpenetrating sphere packingsACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2009Heidrun Sowa Three new types of homogeneous interpenetrating sphere packings are described. In the general position of space group Ccce, two sphere packings of type 3/10/o1 can be combined to form interpenetrating sphere packings of type o[3/10/o1]2. The other two types of interpenetrating sphere packings show symmetry Fddd: two packings of type 3/10/t4 are intertwined in o[3/10/t4]2 and three packings of type 3/4/t1 in o[3/4/t1]3. [source] An ice-like water hexamer with symmetry in the hydrogen-bonded structure of 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-ylmethyl)benzene dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Huan Xu An ice-like hexameric water cluster, stabilized by the flexible bis-imidazolyl compound 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-ylmethyl)benzene (Fbix), is found in the trigonal R crystal structure of the title compound, C14H10F4N4·2H2O or Fbix·2H2O. The Fbix molecule lies about an inversion centre with one water molecule in the asymmetric unit in a general position. A cyclic chair-like hexameric water cluster with symmetry is generated with a hydrogen-bonded O...O distance within the hexamer of 2.786,(3),Å. The Fbix molecule adopts a trans conformation, where the imidazole ring makes a dihedral angle of 70.24,(11)° with the central tetrafluorinated aromatic ring. Each water hexamer is connected by six Fbix molecules through intermolecular O,H...N hydrogen bonds [N...O = 2.868,(3),Å] to yield a three-dimensional supramolecular network with primitive cubic (pcu) topology. Large voids in each single pcu network lead to fourfold interpenetrated aggregates of Fbix·2H2O. [source] p -Phenylenediamine and its dihydrate: two-dimensional isomorphism and mechanism of the dehydration process, and N,H...N and N,H..., interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2010Agnieszka Czapik p -Phenylenediamine can be obtained as the dihydrate, C6H8N2·2H2O, (I), and in its anhydrous form, C6H8N2, (II). The asymmetric unit of (I) contains one half of the p -phenylenediamine molecule lying about an inversion centre and two halves of water molecules, one lying on a mirror plane and the other lying across a mirror plane. In (II), the asymmetric unit consists of one molecule in a general position and two half molecules located around inversion centres. In both structures, the p -phenylenediamine molecules are arranged in layers stabilized by N,H..., interactions. The diamine layers in (I) are isostructural with half of the layers in (II). On dehydration, crystals of (I) transform to (II). Comparison of their crystal structures suggests the most plausible mechanism of the transformation process which requires, in addition to translational motion of the diamine molecules, in-plane rotation of every fourth p -phenylenediamine molecule by ca 60°. A search of the Cambridge Structural Database shows that the formation of hydrates by aromatic amines should be considered exceptional. [source] Two different one-dimensional structural motifs in [catena -{Cu(tacn)}2Pd(CN)4]Br2·[catena -Cu(tacn)Pd(CN)4]2·H2O (tacn is 1,4,7-triazacyclononane)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Juraj Kuchár The title compound, catena -poly[[bis[(triazacyclononane-,3N,N,,N,,)copper(II)]-di-,-cyanido-,4N:C -palladate(II)-di-,-cyanido-,4C:N] dibromide bis[[(triazacyclononane-,3N,N,,N,,)copper(II)]-,-cyanido-,2N:C -[dicyanidopalladate(II)]-,-cyanido-,2C:N] monohydrate], {[Cu2Pd(CN)4(C6H15N3)2]Br2·[Cu2Pd2(CN)8(C6H15N3)2]·H2O}n, (I), was isolated from an aqueous solution containing tacn·3HBr (tacn is 1,4,7-triazacyclononane), Cu2+ and tetracyanidopalladate(2,) anions. The crystal structure of (I) is essentially ionic and built up of 2,2-electroneutral chains, viz. [Cu(tacn)(NC),Pd(CN)2,(CN),], positively charged 2,4-ribbons exhibiting the composition {[Cu(tacn)(NC)2,Pd(CN)2,Cu(tacn)]2n+}n, bromide anions and one disordered water molecule of crystallization. The O atom of the water molecule occupies two unique crystallographic positions, one on a centre of symmetry, which is half occupied, and the other in a general position with one-quarter occupancy. One of the tacn ligands also exhibits disorder. The formation of two different types of one-dimensional structural motif within the same structure is a unique feature of this compound. [source] Two polymeric nickel(II) complexes with aromatic benzene-1,2,4,5-tetracarboxylate and pyridine-2,5-dicarboxylate linkersACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Ana María Atria (,-Benzene-1,2,4,5-tetracarboxylato-,2O1:O4)bis[aquabis(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)] methanol disolvate tetrahydrate, [Ni2(C10H2O8)(C5H14N2)4(H2O)2]·2CH4O·4H2O, (I), is dinuclear, with elemental units built up around an inversion centre halving the benzene-1,2,4,5-tetracarboxylate (btc) anion, which bridges two symmetry-related NiII cations. The octahedral Ni polyhedron is completed by two chelating 2,2-methylpropane-1,3-diamine (dmpda) groups and a terminal aqua ligand. Two methanol and four water solvent molecules are involved in a number of N,H...O and O,H...O hydrogen bonds which define a strongly bound two-dimensional supramolecular structure. The structure of catena -poly[[[bis(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)]-,-pyridine-2,5-dicarboxylato-,3O5:N,O2 -[(2,2-methylpropane-1,3-diamine-,2N,N,)nickel(II)]-,-pyridine-2,5-dicarboxylato-,3N,O2:O5] octahydrate], {[Ni2(C7H3NO4)2(C5H14N2)3]·8H2O}n, (II), is polymeric, forming twisted chains around three independent Ni centres, two of which lie on inversion centres and the third in a general position. There are three chelating dmpda ligands (one disordered over two equally populated positions), which are each attached to a different cation, and two pyridine-2,5-dicarboxylate (pdc) anions, both chelating the Ni centre in general positions through an ,O,C,C,N, loop, while acting as bridges to the remaining two centrosymmetric Ni atoms. There are, in addition, eight noncoordinated water molecules in the structure, some of which are disordered. [source] Bis[4-(trimethylammonio)phenyl] disulfide diiodide acetone solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Zheng Zhang The title compound, C18H26N2S22+·2I,·2C3H6O, is an intermediate in the design of the zwitterionic thiolate 4-(trimethylammonio)benzenethiolate (Tab), in which a pair of aryl-substituted S atoms are linked by a covalent bond. The central S,S bond length is 2.020,(3),Å and the Car,S,S,Car torsion angle is ,84.1,(2)°. The crystal structure is stabilized by nonclassical hydrogen bonds which occur as intramolecular C,H...I interactions and intermolecular C,H...S and C,H...O contacts. In the crystal structure, both the dication and the two symmetrically independent iodide counter-anions are located on twofold crystallographic axes, whereas the acetone solvent molecule occupies a general position. [source] Lithium barium silicate, Li2BaSiO4, from synchrotron powder dataACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Jinyoung Kim The structure of lithium barium silicate, Li2BaSiO4, has been determined from synchrotron radiation powder data. The title compound was synthesized by high-temperature solid-state reaction and crystallizes in the hexagonal space group P63cm. It contains two Li atoms, one Ba atom (both site symmetry ..m on special position 6c), two Si atoms [on special positions 4b (site symmetry 3..) and 2a (site symmetry 3.m)] and four O atoms (one on general position 12d, and three on special positions 6c, 4b and 2a). The basic units of the structure are (Li6SiO13)5, units, each comprising seven tetrahedra sharing edges and vertices. These basic units are connected by sharing corners parallel to [001] and through sharing (SiO4)4, tetrahedra in (001). The relationship between the structures and luminescence properties of Li2SrSiO4, Li2CaSiO4 and the title compound is discussed. [source] Poly[deca-,2 -cyanido-dicyanidobis(,2 -ethylenediamine)bis(ethylenediamine)tricadmium(II)dicobalt(III)]: a two-dimensional coordination polymerACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Olha Sereda The title coordination polymer, [Cd3Co2(CN)12(C2H8N2)4]n, has an infinite two-dimensional network structure. The asymmetric unit is composed of two crystallographically independent CdII atoms, one of which is located on a twofold rotation axis. There are two independent ethylenediamine (en) ligands, one of which bis-chelates to the Cd atom that sits in a general position, while the other bridges this Cd atom to that sitting on the twofold axis. The Cd atom located on the twofold rotation axis is linked to four equivalent CoIII atoms via cyanide bridges, while the Cd atom that sits in a general position is connected to three equivalent CoIII atoms via cyanide bridges. In this way, a series of trinuclear, tetranuclear and pentanuclear macrocycles are linked to form a two-dimensional network structure lying parallel to the bc plane. In the crystal structure, these two-dimensional networks are linked via N,H...N hydrogen bonds involving an en NH2 H atom and a cyanide N atom, leading to the formation of a three-dimensional structure. This coordination polymer is only the second example involving a cyanometallate where the en ligand is present in both chelating and bridging coordination modes. [source] An unusual two-dimensional hydrogen-bonding network in bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) peroxodisulfate dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2008Miguel Angel Harvey The title compound, 2C14H13N2+·S2O82,·2H2O, is a protonated amine salt which is formed from two rather uncommon ionic species, namely a peroxodisulfate (pds2,) anion, which lies across a crystallographic inversion centre, and a 2,9-dimethyl-1,10-phenanthrolin-1-ium (Hdmph+) cation lying in a general position. Each pds2, anion binds to two water molecules through strong water,peroxo O,H...O interactions, giving rise to an unprecedented planar network of hydrogen-bonded macrocycles which run parallel to (100). The atoms of the large R88(30) rings are provided by four water molecules bridging in fully extended form (...H,O,H...) and four pds2, anions alternately acting as long (...O,S,O,O,S,O...) and short (...O,S,O...) bridges. The Hdmph+ cations, in turn, bind to these units through hydrogen bonds involving their protonated N atoms. In addition, the crystal structure also contains ,,, and aromatic,peroxo C,H...O interactions. [source] Ce20Mg19Zn81: a new structure type with a giant cubic cellACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2008Volodymyr Pavlyuk Icosacerium nonadecamagnesium henoctacontazinc, Ce20Mg19Zn81, synthesized by fritting of the pure elements with subsequent arc melting, crystallizes with an unusually large cubic unit cell [space group F3m, a = 21.1979,(8),Å] and represents a new structure type among the technologically important family of ternary rare earth,transition metal,magnesium intermetallics. The majority of atoms (two Ce and five Zn) display .3m site symmetry, two Ce and one Mg atom occupy three 2.mm positions, one Mg and one Zn have 3m site symmetry, one Mg and three Zn atoms sit in ..m positions, and one Zn atom is in a general position. The Ce20Mg19Zn81 structure can be described using the geometric concept of nested polyhedral units, by which it consists of four different polyhedral units, viz. A (Zn+Zn4+Zn4+Zn12+Ce6), B (Mg+Zn12+Ce4+Zn24+Ce4), C (Zn4+Zn12+Mg6) and D (Zn4+Zn4+Mg12+Ce6), with the outer construction unit being an octahedron or tetrahedron. All interatomic distances in the structure indicate metallic-type bonding. [source] Synthetic aenigmatite analog Na2(Mn5.26Na0.74)Ge6O20: structure and crystal chemical considerationsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2008Günther J. Redhammer Disodium hexamanganese(II,III) germanate is the first aenigmatite-type compound with significant amounts of manganese. Na2(Mn5.26Na0.74)Ge6O20 is triclinic and contains two different Na positions, six Ge positions and 20 O positions (all with site symmetry 1 on general position 2i of space group P). Five out of the seven M positions are also on general position 2i, while the remaining two have site symmetry (Wyckoff positions 1f and 1c). The structure can be described in terms of two different layers, A and B, stacked along the [011] direction. Layer A contains pyroxene-like chains and isolated octahedra, while layer B is built up by slabs of edge-sharing octahedra connected to one another by bands of Na polyhedra. The GeO4 tetrahedra show slight polyhedral distortion and are among the most regular found so far in germanate compounds. The M sites of layer A are occupied by highly charged (trivalent) cations, while in layer B a central pyroxene-like zigzag chain can be identified, which contains divalent (or low-charged) cations. This applies to the aenigmatite-type compounds in general and to the title compound in particular. [source] Monoclinic PZN-8%PT [Pb(Zn0.3066Nb0.6133Ti0.08)O3] at 4,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2007Jennifer S. Forrester The structure of the relaxor ferroelectric Pb(Zn0.3066Nb0.6133Ti0.08)O3 (lead zinc niobium titanium trioxide), known as PZN-8%PT, was determined at 4,K from very high resolution neutron powder diffraction data. The material is known for its extraordinary piezoelectric properties, which are closely linked to the structure. Pseudo-cubic lattice parameters have led to considerable controversy over the symmetry of the structure. We find the structure to be monoclinic in the space group Cm (No. 8), with the Zn, Nb and Ti cations sharing the octahedrally coordinated B site (site symmetry m, special position 2a) and Pb occupying the 12-coordinate A site (site symmetry m, special position 2a). O atoms occupy a disorted octahedron around the B site (site symmetry m and special position 2a, and site symmetry 1 and general position 4b). Atomic coordinates have been determined for the first time, allowing the direction of spontaneous polarization to be visualized. [source] Two pseudo-polymorphic copper,benzene-1,2,4,5-tetracarboxylate complexesACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2007Jian-Hai Luo Two pseudo-polymorphic polymers, poly[ethylenediammonium [[aquacopper(II)]-,4 -benzene-1,2,4,5-tetracarboxylato] dihydrate], {(C2H10N2)[Cu(C10H2O8)(H2O)]·2H2O}n, (I), and poly[ethylenediammonium [copper(II)-,4 -benzene-1,2,4,5-tetracarboxylato] 2.5-hydrate], {(C2H10N2)[Cu(C10H2O8)]·2.5H2O}n, (II), contain two-dimensional anionic layers, ethylenediammonium (H2en) cations acting as counter-ions and free water molecules. Although the topological structures of the two anionic layers are homologous, the coordination environments of the CuII centres are different. In (I), the CuII centre, sitting on a general position, has a square-pyramidal environment. The two independent benzene-1,2,4,5-tetracarboxylate (btc) anions rest on centres of inversion. The CuII cation in (II) is located on a twofold axis in a square-planar coordination. The H2en cation is on an inversion centre and the btc ligand is split by a mirror plane. Extensive hydrogen-bonding interactions between the complexes, H2en cations and water molecules lead to the formation of three-dimensional supramolecular structures. [source] 2,4,6-Triamino-1,3,5-triazine,1H -isoindole-1,3(2H)-dione (1/3)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2007Genivaldo Júlio Perpétuo The asymmetric unit of the title compound, C3H6N6·3C8H5NO2, contains a melamine and a phthalimide [1H -isoindole-1,3(2H)-dione] molecule, both residing on a mirror plane, and a second phthalimide molecule residing on a general position. The two components are linked by almost linear N,H...O and N,H...N hydrogen bonds, forming an essentially planar superstructure. These aggregates, related by a twofold screw axis, interact through weak C,H...O contacts, forming chains parallel to the b axis, while those related by translation along the c axis interact via,,, interactions between the , clouds of the aromatic triazine and phthalimide rings to form a stacked structure. [source] Paddlewheel dirhodium complexes bridged by para -substituted benzoatesACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2006Kaori Yamada The dirhodium complex bis(benzonitrile)tetrakis[,-4-(diethylamino)benzoato-,2O:O,]dirhodium(II)(Rh,Rh) benzonitrile disolvate, [Rh2(C11H14NO2)4(C7H5N)2]·2C7H5N, lies about an inversion centre. The dirhodium complex (methanol)tetrakis(,-4-nitrobenzoato-,2O:O,)(pyridine)dirhodium(II)(Rh,Rh) dichloromethane solvate, [Rh2(C7H4NO4)4(C5H5N)(CH4O)]·CH2Cl2, lies in a general position in the unit cell, but the complexes dimerize around an inversion centre via O,H,O hydrogen bonding of the axial MeOH to a carboxylate O atom. In the latter crystal structure, ,,, stacking interactions between the bridging 4-nitrobenzoate ligands and the axial pyridine ligand are observed between adjacent molecules. [source] Rubidium dimolybdate, Rb2Mo2O7, and caesium dimolybdate, Cs2Mo2O7ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2006Zoya A. Solodovnikova The crystal structures of dirubidium heptaoxodimolybdate, Rb2Mo2O7, and dicaesium heptaoxodimolybdate, Cs2Mo2O7, in the space groups Ama2 and P21/c, respectively, have been determined for the first time by single-crystal X-ray diffraction. The structures represent two novel structure types of monovalent ion dimolybdates, A2Mo2O7 (A = alkaline elements, NH4, Ag or Tl). In the structure of Rb2Mo2O7, Mo atoms are on a twofold axis, on a mirror plane and in a general position. One of the Rb atoms lies on a twofold axis, while three others are on mirror planes. Two O atoms attached to the Mo atom on a mirror plane are located on the same plane. Rubidium dimolybdate contains a new kind of infinite Mo,O chain formed from linked MoO4 tetrahedra and MoO6 octahedra alternating along the a axis, with two terminal MoO4 tetrahedra sharing corners with each octahedron. The chains stack in the [001] direction to form channels of an approximately square section filled by ten-coordinate Rb ions. Seven- and eight-coordinate Rb atoms are located between chains connected by a c translation. In the structure of Cs2Mo2O7, all atoms are in general positions. The MoO6 octahedra share opposite corners to form separate infinite chains running along the c axis and strengthened by bridging MoO4 tetrahedra. The same Mo,O polyhedral chain occurs in the structure of Na2Mo2O7. Eight- to eleven-coordinate Cs atoms fill the space between the chains. The atomic arrangement of caesium dimolybdate has an orthorhombic pseudosymmetry that suggests a possible phase transition P21/c,Pbca at elevated temperatures. [source] Manganoan rockbridgeite Fe4.32Mn0.62Zn0.06(PO4)3(OH)5: structure analysis and 57Fe Mössbauer spectroscopyACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2006Günther J. Redhammer The structure of the basic iron phosphate rockbridgeite [iron manganese zinc tris(phosphate) pentahydroxide] was reinvestigated with special emphasis on the cation distribution deduced from new X-ray and 57Fe Mössbauer data. Rockbridgeite is orthorhombic, space group Cmcm, and shows three different Fe sites, one with symmetry, another with m symmetry and the third in a general position. One phosphate group has the P atom on a site with m symmetry, while the other has the P atom at a site with mm symmetry. Two Fe sites are fully occupied by ferric iron, while Mn3+ and Fe2+ are situated at a third, principally Fe, site. Structural data, bond-valence sums and polyhedral distortion parameters suggest a new interpretation of the rockbridgeite 57Fe Mössbauer spectrum. [source] Lithium and beryllium hypophosphitesACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2004Dmitry Yu. The structures of monoclinic (C2/m) lithium dihydrogenphosphate, LiH2PO2, and tetragonal (P41212) beryllium bis(dihydrogenphosphate), Be(H2PO2)2, have been determined by single-crystal X-ray diffraction. The structures consist of layers of hypophosphite anions and metal cations in tetrahedral coordination by O atoms. Within the layers, the anions bridge four Li+ and two Be2+ cations, respectively. In LiH2PO2, the Li atom lies on a twofold axis and the H2PO2, anion has the PO2 atoms on a mirror plane. In Be(H2PO2)2, the Be atom lies on a twofold axis and the H2PO2, anion is in a general position. [source] Bis(pentane-1,5-diammonium) decaiodotriplumbate(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2004David G. Billing The title compound, {(NH3C5H10NH3)2[Pb3I10]}n, crystallizes as an organic,inorganic hybrid. As such, the structure consists of extended chains of [Pb3I10]n4n, ions extending along [111]. The asymmetric unit contains two independent Pb atoms: one is in a general position and the other is on an inversion centre. Each Pb atom is octahedrally coordinated by six iodide ions and exhibits both face- and edge-sharing with adjacent atoms in the inorganic chain. The organic counter-ion, viz. pentane-1,5-diammonium, lies in channels formed by the chains and interacts with these chains via N,H,I hydrogen bonding. [source] Mediating, Interactive, and Non-linear Effects in Service Quality and Satisfaction with Services ResearchCANADIAN JOURNAL OF ADMINISTRATIVE SCIENCES, Issue 2 2002Gordon Fullerton This study examines a number of different hypotheses about the relationship between service quality and satisfaction with services and some important loyalty-related consequences of these constructs. The study confirms the general position in the service quality literature that satisfaction mediates the relationship between service quality and switching intentions, advocacy intentions, and willingness to pay more for the service. In particular, satisfaction is a strong mediator of the effects of service quality on customer retention. The study also finds good support for the existence of a non-linear relationship between satisfaction and these loyalty intentions. The nature of this non-linear relationship is such that the effect of satisfaction on these loyalty-related intentions is more positive at higher levels of satisfaction than it is at lower levels of satisfaction. This is consistent with emerging findings on the nature and consequences of customer delight. Résumé Cette étude examine un certain nombre de différentes hypothèses concernant le rapport entre la qualité de service et la satisfaction des clients, et passe en revue quelques conséquences importantes des ces hypothèses qui illuminent la loyauté des consommateurs envers produits et services. L'étude confirme la validité de la théorie dominante de la qualité de service, à savoir que la satisfaction réglemente le rapport entre la qualité de service et l'intention de commuter de service, comme entre la propensité de recommander un produit ou service et la volonté de supporter un prix plus élevé pour le même service. En particulier, la satisfaction régit les standards de la qualité de service et la retention de la clientèle. L'étude confirme également l'existence d'un rapport non-linéaire entre la satisfaction et la fidelité. Ce rapport indique que l'effet de la satisfaction sur la fidélité est proportionellement plus fort à des niveaux de satisfaction plus élevé qu'à des niveaux plus bas. Cette tendance par ailleurs est conforme à d'autres études récentes sur la nature et les conséquences de la satisfaction des clients. [source] How political parties frame European integrationEUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 4 2010MARC HELBLING This article analyses how political parties frame European integration, and gauges the consistency of their argumentation. Over the course of investigation, one can see how actors' positions are justified, and how the European Union is perceived (i.e., what forces give rise to Euroscepticism and Europeanism). It is argued here that the parties' framing of issues depends on the interests they traditionally defend at the national level, their general positions on European integration, and whether or not they belong to the established political actors in their respective countries. The coding approach enables the relation of frames to actors and positions, moving beyond the techniques employed by existing studies that analyse the media presentation of European integration. Sophisticated frame categorisations are provided to capture the complex structure of argumentation, going beyond a simple dichotomy of economic and cultural frames. Relying on a large and original media dataset covering the period 2004,2006, six Western European countries are investigated. [source] CONTRASTING SUBSISTENCE STRATEGIES IN THE EARLY IRON AGE?OXFORD JOURNAL OF ARCHAEOLOGY, Issue 2 2009AND THE THRACIAN PLAIN, BULGARIA, HUNGARY, NEW RESULTS FROM THE ALFÖLD PLAIN Summary. What can students of the past do to establish the predominant land-use and settlement practices of populations who leave little or no artefactual discard as a testament to their lifeways? The traditional answer, especially in Eastern Europe, is to invoke often exogenous nomadic pastoralists whose dwelling in perpetuo mobile was based on yurts, minimal local ceramic production and high curation levels of wooden and metal containers. Such a lacuna of understanding settlement structure and environmental impacts typifies Early Iron Age (henceforth ,EIA') settlements in both Bulgaria and eastern Hungary , a period when the inception of the use of iron in Central and South-East Europe has a profound effect on the flourishing regional bronze industries of the Late Bronze Age (henceforth ,LBA'). The methodological proposal in this paper is the high value of palynological research for subsistence strategies and human impacts in any area with a poor settlement record. This proposal is illustrated by two new lowland pollen diagrams , Ezero, south-east Bulgaria, and Sarló-hát, north-east Hungary , which provide new insights into this research question. In the Thracian valley, there is a disjunction between an area of high arable potential, the small size and short-lived nature of most LBA and EIA settlements and the strong human impact from the LBA and EIA periods in the Ezero diagram. In the Hungarian Plain, the pollen record suggests that, during the LBA,EIA, extensive grazing meadows were established in the alluvial plain, with the inception of woodland clearance on a massive scale from c.800 cal BC, that contradicts the apparent decline in human population in this area. An attempted explanation of these results comprises the exploration of three general positions , the indigenist thesis, the exogenous thesis and the interactionist thesis. Neither of these results fits well with the traditional view of EIA populations as incoming steppe nomadic pastoralists. Instead, this study seeks to explore the tensions between local productivity and the wider exchange networks in which they are entangled. [source] A novel In3O16 fragment in Cs3In3(PO4)4ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Igor V. Zatovsky The double phosphate Cs3In3(PO4)4, prepared by a flux technique, features a fragment of composition In3O16 formed by three corner-sharing InO6 polyhedra. The central In atom resides on a twofold rotation axis, while the other two In atoms are on general positions. The O atoms in this fragment also belong to PO4 tetrahedra, which link the structure into an overall three-dimensional anionic In,O,P network that is penetrated by tunnels running along c. Two independent Cs+ cations reside inside the tunnels, one of which sits on a centre of inversion. In general, the organization of the framework is similar to that of K3In3(PO4)4, which also contains an In3O16 fragment. However, in the latter case the unit consists of one InO7 polyhedron and one InO6 polyhedron sharing an edge, with a third InO6 octahedron connected via a shared corner. Calculations of the Voronoi,Dirichlet polyhedra of the alkali metals give coordination schemes for Cs of [9+2] and [8+4] ( symmetry), and for K of [8+1], [7+2] and [7+2]. This structural analysis shows that the coordination requirements of the alkali metals residing inside the tunnels cause the difference in the In3O16 geometry. [source] Novel heptavalent actinide compounds: tetrasodium dihydroxidotetraoxidoneptunate(VII) hydroxide dihydrate and its plutonium analogueACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Mikhail S. Grigoriev The title compounds, Na4[NpO4(OH)2]OH·2H2O and Na4[PuO4(OH)2]OH·2H2O, are isostructural and isomorphous, and contain complex [AnO4(OH)2]3, anions (Ac is an actinide) in the form of distorted tetragonal bipyramids, Na+ cations, crystallization water molecules and outer-sphere OH groups. The complex [AnO4(OH)2]3, anions occupy general positions and the coordinated OH groups deviate significantly from a centrosymmetric relative orientation. The [AnO4(OH)2]3, anions exhibit anisotropic actinide contraction; the shortening of the An,O(hydroxide) bonds on going from Np to Pu is greater than that of the AnO4 groups. [source] A novel three-dimensional copper(I) coordination polymer constructed from a copper,bromide net and nicotinic acid ligandsACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Ming-Hua Yang The title compound, poly[,3 -bromido-(pyridine-3-carboxylato-,N)copper(I)], [CuBr(C6H5NO2)]n, is a novel coordination polymer based on a copper,bromide net and nicotinic acid ligands. The asymmetric unit contains one copper(I) ion, one bromide ligand and one nicotinic acid ligand, all on general positions. The CuI atom is tetrahedral and coordinated by three bridging Br atoms and the N atom from the nicotinic acid ligand. The Cu,Br units form alternating six-membered chair-patterned rings in net-like layers. The attached nicotinic acid units point alternately up and down. The layers are assembled into a three-dimensional network via intermolecular O,H...O and C,H...Br hydrogen-bonding interactions. [source] New vanadium(IV) and titanium(IV) oxyfluorotellurates(IV): V2Te2O7F2 and TiTeO3F2ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Jean Paul Laval As part of a continuing study of oxyfluorotellurates(IV), materials likely to present interesting nonlinear optical properties, two new phases, titanium(IV) tellurium(IV) trioxide difluoride, TiTeO3F2, and divanadium(IV) ditellurium(IV) heptaoxide difluoride, V2Te2O7F2, have been characterized and present, respectively, titanium and vanadium in the tetravalent state. The TiTeO3F2 structure is based on linear double rows of TiO3F3 polyhedra sharing vertices. These rows are connected to adjacent rows via two vertices of Te2O5 bipolyhedra. The Te, Ti, one F and two O atoms are on general positions, with one O and F statistically occupying the same site with half-occupancy for each anion. One O and one F occupy sites with .m. symmetry. The V2Te2O7F2 structure consists of zigzag chains of VO4F2 octahedra alternately sharing O,O and F,F edges. These chains are connected via Te2O5 bipolyhedra, forming independent mixed layers. The Te, V, one F and three O atoms are on general positions while one O atom occupies a site of symmetry. In both phases, the electronic lone pair E of the TeIV atom is stereochemically active. A full O/F anionic ordering is observed in V2Te2O7F2, but in TiTeO3F2 one of the six anionic sites is occupied by half oxygen and half fluorine, all the others being strictly ordered. These compounds represent new members of a growing family of oxyfluorotellurates(IV), including the recently characterized members of formula MTeO3F, M being a trivalent cation. As was true for the previous members, they are characterized by an unusually high thermal and chemical stability in relation to the absence of direct Te,F bonds. [source] Bis[S -6-(2,2:6,,2,,-terpyridin-4,-yloxy)hexyl thioacetate]manganese(II) bis(hexafluorophosphate)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Kasper Moth-Poulsen The structure of a manganese(II) complex of terpyridine functionalized with acetylsulfanyl-terminated hexyloxy chains, [Mn(C23H25N3O2S)2](PF6)2, is described. This type of complex is of interest in the study of single-molecule transport properties in open-shell systems. The manganese coordination environment is distorted octahedral but, importantly, with no larger deviations from the idealized geometry than those observed for other metal,terpyridine complexes. The Mn,N bond lengths range from 2.192,(2) to 2.272,(3),Å. The title compound crystallizes with the cation and anions all on general positions, with the hexafluorophosphate anions exhibiting orientational disorder. When compared with other bis-terpyridine complexes, this structure demonstrates that manganese(II) is no more prone to undergo low-symmetry distortions than systems with ligand field stabilization energy contributions. [source] A new polymorph of poly[bis(,2 -perchlorato-,2O:O,)(2,2,:6,,2,,-terpyridine-,3N,N,,N,,)lead(II)] with a greatly extended chain repeat distanceACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Alexander J. Blake In the title compound, [Pb(ClO4)2(C15H11N3)]n, two molecules occupy general positions while the third lies on a crystallographic twofold axis, giving a total of two and a half molecules per asymmetric unit. Each metal centre is coordinated equatorially by three 2,2,:6,,2,,-terpyridine (terpy) N-donor atoms and axially by two perchlorate O-donor atoms. The distorted pentagonal bipyramidal geometry is completed by two equatorial O-donor atoms from two perchlorate anions which bridge to two different adjacent metal centres. The coordination about each metal centre is very similar to that seen at the unique PbII centre in the previously published polymorph [Engelhardt, Harrowfield, Miyamae, Patrick, Skelton, Soudi & White (1996). Aust. J. Chem.49, 1135,1146], but the new polymorph differs from it by the insertion on each side of an existing [bis(perchlorato)(terpy)lead(II)] molecule of two additional such units. Pairs of asymmetrically bridging perchlorate anions link irregularly spaced PbII centres into undulating chains parallel to [201] which exhibit a repeat distance of 26.280,(4),Å. The significance of this new polymorph lies in the fact that, while it is chemically identical to the known polymorph, it is structurally distinct from it. [source] Chromium-based clinopyroxene-type germanates NaCrGe2O6 and LiCrGe2O6 at 298,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2008Günther J. Redhammer The structure analyses of sodium chromium digermanate, NaCrGe2O6, (I), and lithium chromium digermanate, LiCrGe2O6, (II), provide important structural information for the clinopyroxene family, and form part of our ongoing studies on the phase transitions and magnetic properties of clinopyroxenes. (I) shows C2/c symmetry at 298,K, contains one Na, one Cr (both site symmetry 2 on special position 4e), one Ge and three O-atom positions (on general positions 8f) and displays the well known clinopyroxene topology. The basic units of the structure of (I) are infinite zigzag chains of edge-sharing Cr3+O6 octahedra (M1 site), infinite chains of corner-sharing GeO4 tetrahedra, connected to the M1 chains by common corners, and Na sites occupying interstitial space. (II) was found to have P21/c symmetry at 298,K. The structure contains one Na, one Cr, two distinct Ge and six O-atom positions, all on general positions 4e. The general topology of the structure of (II) is similar to that of (I); however, the loss of the twofold symmetry makes it possible for two distinct tetrahedral chains, having different conformation states, to exist. While sodium is (6+2)-fold coordinated, lithium displays a pure sixfold coordination. Structural details are given and chemical comparison is made between silicate and germanate chromium-based clinopyroxenes. [source] | |||||||||||||