PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (476673)

Clipboard (0)
None

Related Articles

1.  Crystal structures of Sr(ClO4)2·3H2O, Sr(ClO4)2·4H2O and Sr(ClO4)2·9H2O 
The crystal structures of the tri-, tetra- and nona­hydrate phases of Sr(ClO4)2 consist of Sr2+ ions coordinated by nine oxygen atoms from water mol­ecules and perchlorate tetra­hedra. O—H⋯O hydrogen bonds between water mol­ecules and ClO4 units lead to the formation of a three-dimensional network in each of the structures.
The title compounds, strontium perchlorate trihydrate {di-μ-aqua-aquadi-μ-perchlorato-strontium, [Sr(ClO4)2(H2O)3]n}, strontium perchlorate tetra­hydrate {di-μ-aqua-bis­(tri­aqua­diperchloratostrontium), [Sr2(ClO4)4(H2O)8]} and strontium perchlorate nona­hydrate {hepta­aqua­diperchloratostrontium dihydrate, [Sr(ClO4)2(H2O)7]·2H2O}, were crystallized at low temperatures according to the solid–liquid phase diagram. The structures of the tri- and tetra­hydrate consist of Sr2+ cations coordinated by five water mol­ecules and four O atoms of four perchlorate tetra­hedra in a distorted tricapped trigonal–prismatic coordination mode. The asymmetric unit of the trihydrate contains two formula units. Two [SrO9] polyhedra in the trihydrate are connected by sharing water mol­ecules and thus forming chains parallel to [100]. In the tetra­hydrate, dimers of two [SrO9] polyhedra connected by two sharing water mol­ecules are formed. The structure of the nona­hydrate contains one Sr2+ cation coordinated by seven water mol­ecules and by two O atoms of two perchlorate tetra­hedra (point group symmetry ..m), forming a tricapped trigonal prism (point group symmetry m2m). The structure contains additional non-coordinating water mol­ecules, which are located on twofold rotation axes. O—H⋯O hydrogen bonds between the water mol­ecules as donor and ClO4 tetra­hedra and water mol­ecules as acceptor groups lead to the formation of a three-dimensional network in each of the three structures.
doi:10.1107/S1600536814024726
PMCID: PMC4257379  PMID: 25552979
crystal structure; low-temperature salt hydrates; perchlorate hydrates; strontium salts
2.  Crystal structure of the ternary silicide Gd2Re3Si5  
The crystal structure of this ternary silicide belongs to the U2Mn3Si5 structure type. The coordination polyhedra of the Gd atoms have 21 vertices, while those of the Re atoms are cubo­octa­hedra and 13-vertex polyhedra, and the Si atoms are arranged as tricapped trigonal prisms, bicapped square anti­prisms, or 11-vertex polyhedra.
A single crystal of the title compound, the ternary silicide digadolinium trirhenium penta­silicide, Gd2Re3Si5, was isolated from an alloy of nominal composition Gd20Re30Si50 synthesized by arc melting and investigated by X-ray single-crystal diffraction. Its crystal structure belongs to the U2Mn3Si5 structure type. All atoms in the asymmetric lie on special positions. The Gd site has site symmetry m..; the two Mn atoms have site symmetries m.. and 2.22; the three Si atoms have site symmetries m.., ..2 and 4.. . The coordination polyhedra of the Gd atoms have 21 vertices, while those of the Re atoms are cubo­octa­hedra and 13-vertex polyhedra. The Si atoms are arranged as tricapped trigonal prisms, bicapped square anti­prisms, or 11-vertex polyhedra. The crystal structure of the title compound is also related to the structure types CaBe2Ge2 and W5Si3. It can be represented as a stacking of Gd-centred polyhedra of composition [GdSi9]. The Re atoms form infinite chains with an Re—Re distance of 2.78163 (5) Å and isolated squares with an Re—Re distance of 2.9683 (6) Å.
doi:10.1107/S1600536814024234
PMCID: PMC4257405  PMID: 25552967
crystal structure; gadolinium; rhenium; silicon; inter­metallic compound; ternary silicide
3.  An ortho­rhom­bic polymorph of the ultraphosphate YP5O14  
Single crystals of yttrium penta­phosphate(V), YP5O14, were obtained by solid-state reaction. The ortho­rhom­bic title compound belongs to the family of ultraphosphates and is the second polymorph of this composition. It is isotypic with its Ho and Er analogues. The structure contains two bridging Q 2-type PO4 tetra­hedra and one branching Q 3-type PO4 tetra­hedron, leading to infinite ultraphosphate ribbons running along the a axis. The coordination polyhedron around the Y3+ cation may be described as distorted bicapped trigonal-prismatic. The YO8 polyhedra are isolated from each other. They are linked by corner-sharing to the O atoms of six Q 2-type and of two Q 3-type PO4 tetra­hedra into a three-dimensional framework.
doi:10.1107/S1600536809007193
PMCID: PMC2968816  PMID: 21582306
4.  SrMnII 2MnIII(PO4)3  
The title compound, strontium trimanganese tris­(ortho­phosphate), was synthesized under hydro­thermal conditions. Its structure is isotypic to that of the lead analogue PbMnII 2MnIII(PO4)3. Two O atoms are in general positions, whereas all others atoms are in special positions. The Sr and one P atom exhibit mm2 symmetry, the MnII atom 2/m symmetry, the MnIII atom and the other P atom .2. symmetry and two O atoms are located on mirror planes. The three-dimensional network of the crystal structure is made up of two types of chains running parallel to [010]. One chain is linear and is composed of alternating MnIIIO6 octa­hedra and PO4 tetra­hedra sharing vertices; the other chain has a zigzag arrangement and is built up from two edge-sharing MnIIO6 octa­hedra connected to PO4 tetra­hedra by edges and vertices. The two types of chains are linked through PO4 tetra­hedra, leading to the formation of channels parallel to [100] and [010] in which the SrII ions are located. They are surrounded by eight O atoms in the form of a slightly distorted bicapped trigonal prism.
doi:10.1107/S1600536813020977
PMCID: PMC3884376  PMID: 24426976
5.  BaMnII 2MnIII(PO4)3  
The title compound, barium trimanganese tris­(ortho­phosphate), was synthesized hydro­thermally. Its structure is isotypic with the lead and strontium analogues AMnII 2MnIII(PO4)3 (A = Pb, Sr). Except for two O atoms on general positions, all atoms are located on special positions. The Ba and one P atom exhibit mm2 symmetry, the MnII atom 2/m symmetry, the MnIII atom and the other P atom .2. symmetry and two O atoms are located on mirror planes. The crystal structure contains two types of chains running parallel to [010]. One chain is linear and is composed of alternating MnIIIO6 octa­hedra and PO4 tetra­hedra sharing vertices; the other chain has a zigzag arrangement and is built up from two edge-sharing MnIIO6 octa­hedra connected to PO4 tetra­hedra by edges and vertices. The two types of chains are linked through PO4 tetra­hedra into an open three-dimensional framework which contains channels parallel to [100] and [010] in which the BaII ions are located. The alkaline earth cation is surrounded by eight O atoms in the form of a slightly distorted bicapped trigonal prism.
doi:10.1107/S1600536813023106
PMCID: PMC3884417  PMID: 24426979
6.  A new mixed-valence lead(II) mangan­ese(II/III) phosphate(V): PbMnII 2MnIII(PO4)3  
The title compound, lead trimanganese tris(orthophosphate), has been synthesized by hydro­thermal methods. In this structure, only two O atoms are in general positions and all others atoms are in the special positions of the Imma space group. Indeed, the atoms in the Wyckoff positions are namely: Pb1 and P1 on 4e (mm2); Mn1 on 4b (2/m); Mn2 and P2 on 8g (2); O1 on 8h (m); O2 on 8i (m). The crystal structure can be viewed as a three-dimensional network of corner- and edge-sharing PO4 tetra­hedra and MnO6 octa­hedra, building two types of chains running along the b axis. The first is an infinite linear chain, formed by alternating MnIIIO6 octa­hedra and PO4 tetra­hedra which share one vertex. The second chain is built up from two adjacent edge-sharing octa­hedra (MnII 2O10 dimers) whose ends are linked to two PO4 tetra­hedra by a common edge. These chains are linked together by common vertices of polyhedra in such a way as to form porous layers parallel to (001). These sheets are bonded by the first linear chains, leading to the appearance of two types of tunnels, one propagating along the a axis and the other along b. The PbII ions are located within the inter­sections of the tunnels with eight neighbouring O atoms in form of a trigonal prism that is capped by two O atoms on one side. The three-dimensional framework of this structure is compared with similar phosphates such as Ag2Co3(HPO4)(PO4)2 and Ag2Ni3(HPO4)(PO4)2.
doi:10.1107/S1600536813016504
PMCID: PMC3772398  PMID: 24046541
7.  Zirconium(IV) dilanthanum(III) penta­sulfide 
Zirconium(IV) dilanthanum(III) penta­sulfide, ZrLa2S5, crystallizes with four formula units in the space group Pnma in the U3S5 structure type. The asymmetric unit comprises one Zr, one La and four S atoms. The Zr and three S atoms are situated on mirror planes. The structure consists of LaS8 face-sharing bicapped distorted trigonal prisms and ZrS7 edge-sharing monocapped octa­hedra.
doi:10.1107/S1600536811045193
PMCID: PMC3238577  PMID: 22199468
8.  NaSr(AsO4)(H2O)9: the (Sr,As) analogue of nabaphite and nastrophite 
The crystal structure of the title compound, sodium strontium orthoarsenate(V) nona­hydrate, is isotypic with NaSr(PO4)(H2O)9 and the minerals nabaphite [NaBa(PO4)(H2O)9] and nastrophite [Na(Sr,Ba)(PO4)(H2O)9]. The Na and Sr atoms are located on threefold rotation axes and are in the centres of slightly distorted Na(H2O)6 octa­hedra and Sr(H2O)9 tricapped trigonal prisms, respectively. A framework structure is established via edge-sharing of these polyhedra. Disordered AsO4 tetra­hedra (with threefold symmetry) are situated in the inter­stitial space of the framework. Although reasonable H-atom positions of the water mol­ecules were not established, close O⋯O contacts between the disordered AsO4 tetra­hedra and the water mol­ecules suggest strong O—H⋯O hydrogen bonding.
doi:10.1107/S1600536809040355
PMCID: PMC2971340  PMID: 21578034
9.  Poly[[aqua­tris­(μ4-benzene-1,2-dicarboxyl­ato)dilanthanum(III)] hemihydrate] 
The asymmetric unit of the title coordination polymer, {[La2(C8H4O4)3(H2O)]·0.5H2O}n, contains two independent LaIII atoms, one of which is surrounded by eight carboxyl­ate-O atoms from six benzene-1,2-dicarboxyl­ate (BDC) anions in a bicapped trigonal–prismatic geometry. The other LaIII atom is nine-coordinated in a tricapped trigonal–prismatic geometry, formed by eight carboxyl­ate-O atoms from six BDC anions and a coordinated water mol­ecule. The BDC anions bridge the LaIII atoms, forming a two-dimensional polymeric complex parallel to (001). The crystal structure contains weak O—H⋯O and non-classical C—H⋯O hydrogen bonds. A C—H⋯π inter­action is also present in the crystal structure. The uncoordinated water molecule shows half-occupation.
doi:10.1107/S1600536811036282
PMCID: PMC3201334  PMID: 22064614
10.  Crystal structures of Ca(ClO4)2·4H2O and Ca(ClO4)2·6H2O 
The crystal structures of the tetra- and hexa­hydrate phases of Ca(ClO4)2 consist of Ca2+ ions in distorted square-anti­prismatic environments and of perchlorate tetra­hedra. O—H⋯O hydrogen bonds between water mol­ecules and ClO4 units lead to the formation of a three-dimensional network in the structures.
The title compounds, calcium perchlorate tetra­hydrate and calcium perchlorate hexa­hydrate, were crystallized at low temperatures according to the solid–liquid phase diagram. The structure of the tetra­hydrate consists of one Ca2+ cation eightfold coordinated in a square-anti­prismatic fashion by four water mol­ecules and four O atoms of four perchlorate tetra­hedra, forming chains parallel to [01-1] by sharing corners of the ClO4 tetra­hedra. The structure of the hexa­hydrate contains two different Ca2+ cations, each coordinated by six water mol­ecules and two O atoms of two perchlorate tetra­hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra­hedra. The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra­hedra. O—H⋯O hydrogen bonds between the water mol­ecules as donor and ClO4 tetra­hedra and water mol­ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures. Ca(ClO4)2·6H2O was refined as a two-component inversion twin, with an approximate twin component ratio of 1:1 in each of the two structures.
doi:10.1107/S1600536814024532
PMCID: PMC4257416  PMID: 25552974
crystal structure; low-temperature salt hydrates; perchlorate hydrates; calcium salts; Mars minerals
11.  Poly[diaqua­tris(μ4-isophthalato)dilanthanum(III)] 
In the title coordination polymer, [La2(C8H4O4)3(H2O)2]n, there are two independent LaIII atoms which are coordinated differently in slightly distorted penta­gonal-bipyramidal and slightly disorted bicapped trigonal-prismatic environments. The LaIII ions are bridged by μ4-isophthalate ligands, forming two-dimensional layers. In the crystal structure, these layers are connected by inter­molecular O—H⋯O hydrogen bonds into a three-dimensional network.
doi:10.1107/S1600536809054543
PMCID: PMC2979801  PMID: 21579693
12.  Crystal structures of Na2SeO4·1.5H2O and Na2SeO4·10H2O 
The crystal structures of the 1.5- and 10-hydrates of Na2SeO4 are isotypic with those of the corresponding chromates.
The crystal structures of Na2SeO4·1.5H2O (sodium selenate sesquihydrate) and Na2SeO4·10H2O (sodium selenate deca­hydrate) are isotypic with those of Na2CrO4·1.5H2O and Na2 XSeO4·10H2O (X = S, Cr), respectively. The asymmetric unit of the sesquihydrate contains two Na+ cations, one SeO4 tetra­hedron and one and a half water mol­ecules, the other half being generated by twofold rotation symmetry. The coordination polyhedra of the cations are a distorted monocapped octa­hedron and a square pyramid; these [NaOx] polyhedra are linked through common edges and corners into a three-dimensional framework structure, the voids of which are filled with the Se atoms of the SeO4 tetra­hedra. The structure is consolidated by O—H⋯O hydrogen bonds between coordinating water mol­ecules and framework O atoms. The asymmetric unit of the deca­hydrate consists of two Na+ cations, one SeO4 tetra­hedron and ten water mol­ecules. Both Na+ cations are octa­hedrally surrounded by water mol­ecules and by edge-sharing condensed into zigzag chains extending parallel to [001]. The SeO4 tetra­hedra and two uncoordinating water mol­ecules are situated between the chains and are connected to the chains through an intricate network of medium-strength O—H⋯O hydrogen bonds.
doi:10.1107/S1600536814011799
PMCID: PMC4158548  PMID: 25249853
isotypism; sodium selenate; salt hydrates; crystal structure
13.  Nd2(WO4)3  
The title compound, dineodymium(III) tris­[tungstate(VI)], is a member of the Eu2(WO4)3 structure family and crystallizes isotypically with other rare earth tungstates and molybdates of this formula type. The structure is a derivative of the scheelite (CaWO4) structure and can be considered as an ordered defect variant with a threefold scheelite supercell and one rare earth (RE) site unoccupied. The Nd3+ cations are coordinated by eight O atoms in form of a distorted bicapped trigonal prism. The two unique W cations are tetra­hedrally surrounded by O atoms. One WO4 tetra­hedron has 2 symmetry and is relatively undistorted whereas the other tetra­hedron differs considerably from an ideal geometry. This is caused by an additional remote O atom at a distance of 2.149 (4) Å. The resulting WO4 + 1 polyhedra form W2O8 dimers through edge-sharing. Together with the WO4 and NdO8 units, the three-dimensional set-up is accomplished.
doi:10.1107/S1600536809018108
PMCID: PMC2969527  PMID: 21582980
14.  KNb1.75V0.25PS10  
The title compound, potassium diniobium vanadium phospho­rus deca­sulfide, KNb1.75V0.25PS10, was obtained by reaction of the elements with a eutectic mixture of KCl/LiCl. It is isostructural with the quaternary KNb2PS10, but the Nb sites are occupied by statistically disordered Nb (87.5%) and V (12.5%) atoms. The structure is composed of anionic ∞ 1[M 2PS10]− chains (M = Nb/V) separated from each other by K+ ions. The chain is composed of [MS8] distorted bicapped trigonal prisms and [PS4] tetra­hedra. There are no inter­chain bonding inter­actions. The crystal used for the X-ray analysis was a racemic twin.
doi:10.1107/S1600536811004430
PMCID: PMC3051977  PMID: 21522232
15.  Hafnium germanium telluride 
The title hafnium germanium telluride, HfGeTe4, has been synthesized by the use of a halide flux and structurally characterized by X-ray diffraction. HfGeTe4 is isostructural with stoichiometric ZrGeTe4 and the Hf site in this compound is also fully occupied. The crystal structure of HfGeTe4 adopts a two-dimensional layered structure, each layer being composed of two unique one-dimensional chains of face-sharing Hf-centered bicapped trigonal prisms and corner-sharing Ge-centered tetra­hedra. These layers stack on top of each other to complete the three-dimensional structure with undulating van der Waals gaps.
doi:10.1107/S1600536808011380
PMCID: PMC2961149  PMID: 21202163
16.  Lithio­marsturite, LiCa2Mn2Si5O14(OH) 
Lithio­marsturite, ideally LiCa2Mn2Si5O14(OH), is a member of the pectolite–pyroxene series of pyroxenoids (hydro­pyroxenoids) and belongs to the rhodonite group. A previous structure determination of this mineral based on triclinic symmetry in space group P by Peacor et al. [Am. Mineral. (1990), 75, 409–414] converged with R = 0.18 without reporting any information on atomic coordinates and displacement param­eters. The current study redetermines its structure from a natural specimen from the type locality (Foote mine, North Carolina) based on single-crystal X-ray diffraction data. The crystal structure of lithio­marsturite is characterized by ribbons of edge-sharing CaO6 and two types of MnO6 octa­hedra as well as chains of corner-sharing SiO4 tetra­hedra, both extending along [110]. The octa­hedral ribbons are inter­connected by the rather irregular CaO8 and LiO6 polyhedra through sharing corners and edges, forming layers parallel to (1), which are linked together by the silicate chains. Whereas the coordination environments of the Mn and Li cations can be compared to those of the corresponding cations in nambulite, the bonding situations of the Ca cations are more similar to those in babingtonite. In contrast to the hydrogen-bonding scheme in babingtonite, which has one O atom as the hydrogen-bond donor and a second O atom as the hydrogen-bond acceptor, our study shows that the situation is reversed in lithio­marsturite for the same two O atoms, as a consequence of the differences in the bonding environments around O atoms in the two minerals.
doi:10.1107/S1600536811047581
PMCID: PMC3238580  PMID: 22199471
17.  Redetermination of MoPt3Si4 from single-crystal data 
The crystal structure of molybdenum triplatinum tetrasilicide, MoPt3Si4, determined previously from powder diffraction data [Joubert et al. (2010 ▶). J. Solid State Chem. 183, 173–179], has been redetermined using a single crystal synthesized from the elements by high-frequency melting. The redetermination provides more precise geometrical data and also anisotropic displacement parameters. The crystal structure can be considered to be derived from the PtSi structure type with an ordered substitution of Pt by Mo atoms, but leading to a very distorted Si network compared to the parent structure. Mo and Pt exhibit different coordination polyhedra. These are based on bicapped-square anti­prisms, but with two additional vertices in cis positions for Mo, whereas they are in trans positions for Pt (as in PtSi). The coordination polyhedra for three of the Si atoms can be considered as highly deformed square anti­prisms (as in PtSi), while the fourth Si atom has a bicapped trigonal–prismatic coordination geometry.
doi:10.1107/S1600536810054425
PMCID: PMC3051478  PMID: 21522816
18.  Penta­potassium praseodymium(III) dilithium deca­fluoride, K5PrLi2F10  
The crystal structure of K5PrLi2F10 is isotypic with those of other K5 RELi2F10 compounds (RE = Eu, Nd). The lanthanoid ions are isolated in K5PrLi2F10, with a mean separation between the Pr ions of 7.356 Å. It classifies this crystal as a so-called self-activated material containing lanthanoid ions within the matrix. Except for two K+ and two F− ions, all atoms are located on sites with m symmetry. In the structure, distorted PrF8 dodeca­hedra and two different LiF4 tetra­hedra share F atoms, forming sheets parallel to (100). The isolated PrF8 dodeca­hedra exhibit a mean Pr—F distance of 2.406 Å. The K+ cations are located within and between these sheets, leading to highly irregular KFx polyhedra with coordination numbers of eight and nine for the alkali metal cations.
doi:10.1107/S1600536809044043
PMCID: PMC2971201  PMID: 21578038
19.  Thallium(I) copper(I) thorium(IV) tris­elenide, TlCuThSe3  
Thallium(I) copper(I) thorium(IV) tris­elenide, TlCuThSe3, crystallizes with four formula units in the space group Cmcm in the KCuZrS3 structure type. There is one crystallographic­ally independent Th, Tl, and Cu atom at a site of symmetry 2/m.., m2m, and m2m, respectively. There are two crystallographically independent Se atoms at sites of symmetry m.. and m2m. The structure consists of sheets of edge-sharing ThSe6 octa­hedra and CuSe4 tetra­hedra stacked parallel to the (010) face, separated by layers filled with chains of Tl running parallel to [100]. Each Tl is coordinated by a trigonal prism of Se atoms.
doi:10.1107/S1600536812026669
PMCID: PMC3393138  PMID: 22807695
20.  Penta­potassium europium(III) dilithium deca­fluoride, K5EuLi2F10  
The title compound, K5EuLi2F10, belongs to so-called self-activated materials containing lanthanoid ions within the matrix. A common feature of these systems is a large separation between the closest lanthanoid ions, which is one of the crucial factors governing the self-quenching of luminescence. The crystal structure of K5EuLi2F10 is isotypic with other K5 RELi2F10 compounds (RE = Nd, Pr). As expected from the lanthanoid contraction, the unit-cell volume for crystal with Eu3+ ions is the smallest of the three structures. Accordingly, the corresponding inter­atomic RE—RE distances are shorter. In the structure, distorted EuF8 dodeca­hedra and two different LiF4 tetra­hedra, all with m symmetry, are present, forming sheets parallel to (100). The isolated EuF8 dodeca­hedra exhibit a mean Eu—F distance of 2.356 Å. The K+ cations are located within and between the sheets, leading to highly irregular KFx polyhedra (x = 8–9) around the alkali metal cations.
doi:10.1107/S1600536809044055
PMCID: PMC2971037  PMID: 21578039
21.  Redetermination of the low-temperature polymorph of Li2MnSiO4 from single-crystal X-ray data 
Crystals of dilithium manganese(II) silicate were grown under high-temperature hydro­thermal conditions in the system LiOH—MnO2—SiO2. The title compound crystallizes in the βII-Li3PO4 structure type. The coordination polyhedra of all cations are slightly distorted tetra­hedra (m symmetry for MnO4 and SiO4), which are linked by corner-sharing to each other. The vertices of the tetra­hedra point to the same direction perpendicular to the distorted hexa­gonal close-packed (hcp) array of O atoms within which half of the tetra­hedral voids are occupied by cations. In comparison with the previous refinement from powder X-ray data [Dominko et al. (2006 ▶). Electrochem. Commun. 8, 217–222], the present reinvestigation from single-crystal X-ray data allows a more precise determination of the distribution of the Li+ and Mn2+ cations, giving a perfectly site-ordered structure model for both Li+ and Mn2+.
doi:10.1107/S1600536812035040
PMCID: PMC3435565  PMID: 22969438
22.  Redetermination of Ba2CdTe3 from single-crystal X-ray data 
The previous structure determination of the title compound, dibarium tritelluridocadmate, was based on powder X-ray diffraction data [Wang & DiSalvo (1999 ▶). J. Solid State Chem. 148, 464–467]. In the current redetermination from single-crystal X-ray data, all atoms were refined with anisotropic displacement parameters. The previous structure report is generally confirmed, but with some differences in bond lengths. Ba2CdTe3 is isotypic with Ba2 MX 3 (M = Mn, Cd; X = S, Se) and features 1 ∞[CdTe2/2Te2/1]4− chains of corner-sharing CdTe4 tetra­hedra running parallel [010]. The two Ba2+ cations are located between the chains, both within distorted monocapped trigonal–prismatic coordination polyhedra. All atoms in the structure are located on a mirror plane.
doi:10.1107/S1600536812038974
PMCID: PMC3470123  PMID: 23125567
23.  The solid solution (Fe0.81Al0.19)(H2PO4)3 with a strong hydrogen bond 
A sample of synthetic (Fe0.81Al0.19)(H2PO4)3 was prepared by hydro­thermal methods in order to determine the crystal structure. The compound is a new monoclinic variety (γ-form) and the structure is based on a two-dimensional framework of distorted corner-sharing MO6 (M = Fe, Al) polyhedra sharing corners with PO4 tetra­hedra.
Single crystals of the solid solution iron aluminium tris(dihydrogenphosphate), (Fe0.81Al0.19)(H2PO4)3, have been pre­pared under hydro­thermal conditions. The compound is a new monoclinic variety (γ-form) of iron aluminium phosphate (Fe,Al)(H2PO4)3. The structure is based on a two-dimensional framework of distorted corner-sharing MO6 (M = Fe, Al) polyhedra sharing corners with PO4 tetra­hedra. Strong hydrogen bonds between the OH groups of the H2PO4 tetra­hedra and the O atoms help to consolidate the crystal structure.
doi:10.1107/S0108270110001344
PMCID: PMC2855575  PMID: 20203392
24.  Tetra-μ3-iodido-tetra­kis­[(tri-n-butyl­phosphane-κP)copper(I)] 
The title complex, [Cu4I4(C12H27P)4], crystallizes with six mol­ecules in the unit cell and with three independent one-third mol­ecule fragments, completed by application of the relevant symmetry operators, in the asymmetric unit. The tetranuclear copper core shows a tetrahedral geometry (site symmetry 3..). The I atoms also form a tetra­hedron, with I⋯I distances of 4.471 (1) Å. Both tetra­hedra show an orientation similar to that of a pair of self-dual platonic bodies. The edges of the I-tetra­hedral structure are capped to the face centers of the Cu-tetra­hedron and vice versa. The Cuface⋯I distances are 2.18 Å (averaged) and the Iface⋯Cu distances are 0.78 Å (averaged). As a geometric consequence of these properties there are eight distorted trigonal–bipyramidal polyhedra evident, wherein each trigonal face builds up the equatorial site and the opposite Cu⋯I positions form the axial site. As expected, the n-butyl moieties are highly flexible, resulting in large elongations of their anisotropic displacement parameters. Some C atoms of the n-butyl groups were needed to fix alternative discrete disordered positions.
doi:10.1107/S1600536814003390
PMCID: PMC3998569  PMID: 24826086
25.  Barium dierbium(III) tetra­sulfide 
Barium dierbium(III) tetra­sulfide, BaEr2S4, crystallizes with four formula units in the ortho­rhom­bic space group Pnma in the CaFe2O4 structure type. The asymmetric unit contains two Er, one Ba, and four S atoms, each with .m. site symmetry. The structure consists of channels formed by corner- and edge-sharing ErS6 octa­hedra in which Ba atoms reside. The resultant coordination of Ba is that of a bicapped trigonal prism.
doi:10.1107/S1600536813003541
PMCID: PMC3588518  PMID: 23476480

Results 1-25 (476673)