scholarly journals About the polymorphism of [Li(C4H8O)3]I: crystal structures of trigonal and tetragonal polymorphs

2014 ◽  
Vol 70 (12) ◽  
pp. 555-558
Author(s):  
Stefanie Gärtner ◽  
Tobias Gärtner ◽  
Ruth-Maria Gschwind ◽  
Nikolaus Korber
Keyword(s):  
Rotation Axis ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Intermolecular Forces ◽  
Ion Pair ◽  
Lithium Cation ◽  
Tetrahedral Coordination ◽  
Space Group ◽  
Trigonal Structure ◽  
Van Der Waals Contacts

Two new trigonal and tetragonal polymorphs of the title compound, iodidotris(tetrahydrofuran-κO)lithium, are presented, which both include the isolated ion pair Li(THF)3+·I−. One Li—I ion contact and three tetrahydrofuran (THF) molecules complete the tetrahedral coordination of the lithium cation. The three-dimensional arrangement in the two polymorphs differs notably. In the trigonal structure, the ion pair is located on a threefold rotation axis of space groupP-3 and only one THF molecule is present in the asymmetric unit. In the crystal, strands of ion pairs parallel to [001] are observed with an eclipsed conformation of the THF molecules relative to the Li...I axis of two adjacent ion pairs. In contrast, the tetragonal polymorph shows a much larger unit cell in which all atoms are located on general positions of the space groupI41cd. The resulting three-dimensional arrangement shows helical chains of ion pairs parallel to [001]. Apart from van der Waals contacts, no remarkable intermolecular forces are present between the isolated ion pairs in both structures.

Anionic pyrazolyl-bridged nickel nitrosyl complexes. Synthesis, structure, and reactivity

1979 ◽  
Vol 57 (23) ◽  
pp. 3099-3106 ◽  
Author(s):  
Kenneth S. Chong ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Ion Pair ◽  
Sodium Ion ◽  
Coordination Geometry ◽  
Tetrahedral Coordination ◽  
Space Group ◽  
Nitrosyl Complexes ◽  
Pyrazolyl Group ◽  
The Mean ◽  
Distorted Tetrahedral Coordination ◽  
Molecular Unit

A series of anionic pyrazolyl-bridged nickel nitrosyl complexes, M+[(ON)Ni(μ-L2)(μ-X)Ni(NO)]− (where L = pyrazolyl, N2C3H3, or 3,5-dimethylpyrazolyl, N2C5H7; X = Cl, Br, I, or N2C5H7; and M = Na, (CH3)4N, or (C2H5)4N) is described. Crystallographic analyses have been carried out on two of these complexes. Crystals of [(C2H5)4N]+[(ON)Ni(μ-I)(μ- N2C5H7)2Ni(NO)]− are orthorhombic, a = 19.910(1), b = 14.0330(7), c = 9.3195(9) Å, Z = 4, space group Pn21a and crystals of [(C4H8O)2Na][(ON)Ni(μ-N2C5 H7)3Ni(NO)] are orthorhombic, a = 19.897(2), b = 19.529(3), c = 15.894(2) Å, Z = 8, space group Pbca. Both structures were solved by Patterson and Fourier syntheses and were refined by full-matrix least-squares procedures to R = 0.027 and 0.057 for 2572 and 2168 reflections with I ≥ 3σ(I) respectively. The structure of [(C2H5)4N]+[(ON)Ni(μ-I)(μ-N2C5H7)2Ni(NO)]− consists of discrete cations and binuclear anions which have approximate C2v symmetry. The nickel atoms have distorted tetrahedral coordination geometry. Important mean molecular dimensions (distances corrected for libration) are: Ni—I—Ni, 73.67(2)°, Ni—I, 2.765(3), Ni—NO, 1.649(5), Ni—N(pyrazolyl), 1.980(14) Å, and Ni—N—O, 172.5(18)°. The structure of [(C4H8O)2Na][(ON)Ni(μ-N2C5 H7)3Ni(NO)] consists of discrete ion-pair units in which the two NiNO moieties are bridged by three N2C5H7 ligands, two of which are coordinated to the sodium ion via a novel η2(N,N) π-interaction (mean Na—N = 2.61(3) Å). The sodium is also coordinated to two tetrahydrofuran oxygen atoms to give a distorted tetrahedral coordination geometry about the sodium (Na—O = 2.301(6) and 2.266(5) Å). Except for disordered tetrahydrofuran carbon atoms, the molecular unit has approximate C2v symmetry. The nickel atoms have distorted tetrahedral coordination geometry, the mean distances being Ni—NO, 1.591(6), Ni—N(pyrazolyl), 1.985(2) for the unique pyrazolyl group and 2.016(5) Å for the pyrazolyl nitrogen atoms coordinated to Na. The mean Ni—N—O angle is 176.9(11)°.

Reindarstellung und Kristallstruktur von Lithiumtrinitridbromid, Li10N3Br / Preparation and Crystal Structure of Lithium Trinitride Bromide Li10N3Br

1995 ◽  
Vol 50 (7) ◽  
pp. 1061-1066 ◽  
Author(s):  
Rupert Marx
Keyword(s):  
Three Dimensional ◽  
Tetrahedral Coordination ◽  
Powder Diffraction Data ◽  
Space Group ◽  
Neutron Powder Diffraction Data ◽  
Unknown Structure ◽  
Quasi Binary System ◽  
Distorted Tetrahedral Coordination ◽  
Trigonal Prismatic ◽  
Linear Coordination

Li10N3Br has been prepared by the reaction of Li3N and dry, OH-free LiBr. It is found to be the most nitride rich compound in the quasi-binary system Li3-2xN1-xBrx. The previously unknown structure of the title compound has been solved from neutron powder diffraction data recorded using the flat-cone and powder diffractometer E2 at the Berlin BER II reactor. Li10N3Br crystallizes in the hexagonal space group P6̄m2 (No. 187), a = 741.3(1) pm, c = 386.57(3) pm, with one formula unit per unit cell. The structure is closely related to Li3N (space group P6/m m m , a = 364.8(1) pm, c = 387.5(1) pm). It comprises roughly pentagonal bipyramidal Li7N units which share edges and vertices to give a three-dimensional Li10N 3 network. The Li atoms in axial positions are in an almost linear coordination with the central N atom. The Li atoms in the equatorial positions are surrounded either by N atoms in an ideal trigonal coordination or by N and Br atoms in a distorted tetrahedral coordination. The Br atoms are situated in the large trigonal prismatic holes formed by the Li atoms.

scholarly journals Crystal structure of bis(N,N,N′,N′-tetramethylguanidinium) tetrachloridocuprate(II)

2016 ◽  
Vol 72 (7) ◽  
pp. 1047-1049 ◽  
Author(s):  
Mamadou Ndiaye ◽  
Abdoulaye Samb ◽  
Libasse Diop ◽  
Thierry Maris
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Network Structure ◽  
Crystal Packing ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Tetrahedral Coordination ◽  
Coordination Environment ◽  
Dimensional Network

In the structure of the title salt, (C5H14N3)2[CuCl4], the CuIIatom in the anion lies on a twofold rotation axis. The tetrachloridocuprate(II) anion adopts a flattened tetrahedral coordination environment and interacts electrostatically with the tetramethylguanidinium cation. The crystal packing is additionally consolidated through N—H...Cl and C—H...Cl hydrogen bonds, resulting in a three-dimensional network structure.

The interpenetrated three-dimensional framework of a new mixed lithium/ammonium perchlorate grown in a gel medium

2013 ◽  
Vol 69 (4) ◽  
pp. 315-318 ◽  
Author(s):  
Siwar Walha ◽  
Mahmoud Bouchaala ◽  
Abdelhamid Ben Salah
Keyword(s):  
Ambient Temperature ◽  
Crystal Structures ◽  
Ammonium Perchlorate ◽  
Three Dimensional ◽  
Tetrahedral Coordination ◽  
Agar Gel ◽  
Space Group ◽  
Gel Diffusion

Mixed lithium/ammonium perchlorate, Li0.41(NH4)0.59ClO4, has been prepared by gel diffusion using agar agar gel as the medium of growth at ambient temperature. The Cl and mixed Li/N atoms are located on the 4a({1 \over 2}, {1 \over 2}, {1 \over 2}) and 4b({1 \over 2}, 0, {1 \over 4}) special positions, respectively, in the space groupI\overline 42d. The structure features a twofold interpenetrated three-dimensional entanglement architecture, in which single three-dimensional networks are constructed from tetrahedral coordination based on [–(ClO4)–(Li/NH4)–(ClO4)–]∞diamondoid arrays. A comparison of the crystal structures of Li0.41(NH4)0.59ClO4, LiClO4·3H2O, LiClO4and NH4ClO4is given.

4,6-Diaminopyrimidine-2(1H)-thione hemihydrate: a three-dimensional hydrogen-bonded framework

2012 ◽  
Vol 68 (10) ◽  
pp. o377-o380 ◽  
Author(s):  
Zhenfeng Zhang ◽  
Dong Xian ◽  
Christopher Glidewell
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Title Compound ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Space Group ◽  
Compound C ◽  
Axis Parallel ◽  
Molecular Components

In the title compound, C4H6N4S·0.5H2O, there are two independent pyrimidinethione units, both of which lie across mirror planes in the space groupCmca. Hence, the H atoms bonded to the ring N atoms in each molecule are disordered over two symmetry-related sites, each having an occupancy of 0.5. The water molecule lies across a twofold rotation axis parallel to [010]. The molecular components of (I) are linked by seven independent hydrogen bonds, of N—H...N, N—H...S, N—H...O and O—H...S types. A combination of disordered N—H...N hydrogen bonds and ordered N—H...S hydrogen bonds links the pyrimidinethione units into a continuous tubular structure. The water molecule acts as both a double donor of hydrogen bonds and a double acceptor, forming hydrogen bonds with components of four distinct pyrimidinethione tubes, thus linking these tubes into a three-dimensional structure.

The Preparation and Crystal Structure of [I2]+[Sb2F11]−

1974 ◽  
Vol 52 (11) ◽  
pp. 2048-2052 ◽  
Author(s):  
C. G. Davies ◽  
R. J. Gillespie ◽  
P. R. Ireland ◽  
Joy M. Sowa
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Compound I ◽  
Space Group ◽  
X Ray ◽  
R Factor ◽  
Bridge Length ◽  
Counter Data

The crystal structure of the compound I2+Sb2F11− has been determined from three-dimensional X-ray counter data. Crystals are monoclinic with a = 13.283(5), b = 8.314(3), c = 5.571(2) Å; β = 103.75(2)°; V = 579.5 Å3;Z = 2 and Dc = 3.92 g cm−3. The structure has been refined in the space group C2 with a final conventional R factor of 0.055 for 365 independent reflections with I ≥ 3σ(1). The structure consists of discrete I2+ cations and Sb2F11− anions, each with a crystallographic two-fold rotation axis through the center. The I—I bond length is 2.557(4) Å while the Sb—F bridge length is 2.00(1) Å with a bridge angle of 166(3)° in the symmetric anion.

Stereospecific 1,3-H Transfer of Indenols Proceeds via Persistent Ion-Pairs Anchored By NH···Pi Interactions

2018 ◽  
Author(s):  
David Ascough ◽  
Fernanda Duarte ◽  
Robert Paton
Keyword(s):  
Computational Analysis ◽  
Ion Pairs ◽  
Ion Pair ◽  
Hydrogen Atom Transfer ◽  
Polar Solvents ◽  
Chirality Transfer ◽  
Activation Barriers ◽  
Sense And Avoid ◽  
Phase Dynamics ◽  
Pi Interactions

The base-catalyzed rearrangement of arylindenols is a rare example of a suprafacial [1,3]-hydrogen atom transfer. The mechanism has been proposed to proceed via sequential [1,5]-sigmatropic shifts, which occur in a selective sense and avoid an achiral intermediate. A computational analysis using quantum chemistry casts serious doubt on these suggestions: these pathways have enormous activation barriers and in constrast to what is observed experimentally, they overwhelmingly favor a racemic product. Instead we propose that a suprafacial [1,3]-prototopic shift occurs in a two-step deprotonation/reprotonation sequence. This mechanism is favored by 15 kcal mol<sup>-1</sup> over that previously proposed. Most importantly, this is also consistent with stereospecificity since reprotonation occurs rapidly on the same p-face. We have used explicitly-solvated molecular dynamics studies to study the persistence and condensed-phase dynamics of the intermediate ion-pair formed in this reaction. Chirality transfer is the result of a particularly resilient contact ion-pair, held together by electrostatic attraction and a critical NH···p interaction which ensures that this species has an appreciable lifetime even in polar solvents such as DMSO and MeOH.

scholarly journals 2-Amino-5-chloropyridinium cis-diaquadioxalatochromate(III) sesquihydrate

2012 ◽  
Vol 68 (6) ◽  
pp. m824-m825 ◽  
Author(s):  
Ichraf Chérif ◽  
Jawher Abdelhak ◽  
Mohamed Faouzi Zid ◽  
Ahmed Driss
Keyword(s):  
Rotation Axis ◽  
Three Dimensional ◽  
Octahedral Geometry ◽  
Distorted Octahedral Geometry ◽  
Water Molecules ◽  
Lattice Water ◽  
Compound C ◽  
Hydrogen Bonding Interactions ◽  
Distorted Octahedral ◽  
Independent Lattice

In the crystal structure of the title compound, (C5H6ClN2)[Cr(C2O4)2(H2O)2]·1.5H2O, the CrIII atom adopts a distorted octahedral geometry being coordinated by two O atoms of two cis water molecules and four O atoms from two chelating oxalate dianions. The cis-diaquadioxalatochromate(III) anions, 2-amino-5-chloropyridinium cations and uncoordinated water molecules are linked into a three-dimensional supramolecular array by O—H...O and N—H...O hydrogen-bonding interactions. One of the two independent lattice water molecules is situated on a twofold rotation axis.

scholarly journals Tripodal, Squaramide-Based Ion Pair Receptor for Effective Extraction of Sulfate Salt

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2751
Author(s):  
Damian Jagleniec ◽  
Marcin Wilczek ◽  
Jan Romański
Keyword(s):  
Ion Pairs ◽  
Binding Mode ◽  
Selective Extraction ◽  
Ion Pair ◽  
Hofmeister Series ◽  
Sulfate Salt ◽  
Lower Affinity ◽  
High Affinity ◽  
Binding Domains ◽  
Hydrated Sulfate

Combining three features—the high affinity of squaramides toward anions, cooperation in ion pair binding and preorganization of the binding domains in the tripodal platform—led to the effective receptor 2. The lack of at least one of these key elements in the structures of reference receptors 3 and 4 caused a lower affinity towards ion pairs. Receptor 2 was found to form an intramolecular network in wet chloroform, which changed into inorganic–organic associates after contact with ions and allowed salts to be extracted from an aqueous to an organic phase. The disparity in the binding mode of 2 with sulfates and with other monovalent anions led to the selective extraction of extremely hydrated sulfate anions in the presence of more lipophilic salts, thus overcoming the Hofmeister series.

Intergrowth polytypoids as modulated structures: a superspace description of the Sr n (Nb,Ti) n O3n + 2 compound series

2001 ◽  
Vol 57 (4) ◽  
pp. 471-484 ◽  
Author(s):  
L. Elcoro ◽  
J. M. Perez-Mato ◽  
R. L. Withers
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Separation Distance ◽  
Space Group ◽  
Space Groups ◽  
Cell Parameters ◽  
Average Structure ◽  
Layer Stacking ◽  
Compound Series ◽  
Three Dimensional Space

A new, unified superspace approach to the structural characterization of the perovskite-related Sr n (Nb,Ti) n O3n + 2 compound series, strontium niobium/titanium oxide, is presented. To a first approximation, the structure of any member of this compound series can be described in terms of the stacking of (110)-bounded perovskite slabs, the number of atomic layers in a single perovskite slab varying systematically with composition. The various composition-dependent layer-stacking sequences can be interpreted in terms of the structural modulation of a common underlying average structure. The average interlayer separation distance is directly related to the average structure periodicity along the layer stacking direction, while an inherent modulation thereof is produced by the presence of different types of layers (particularly vacant layers) along this stacking direction. The fundamental atomic modulation is therefore occupational and can be described by means of crenel (step-like) functions which define occupational atomic domains in the superspace, similarly to what occurs for quasicrystals. While in a standard crystallographic approach, one must describe each structure (in particular the space group and cell parameters) separately for each composition, the proposed superspace model is essentially common to the whole compound series. The superspace symmetry group is unique, while the primary modulation wavevector and the width of some occupation domains vary linearly with composition. For each rational composition, the corresponding conventional three-dimensional space group can be derived from the common superspace group. The resultant possible three-dimensional space groups are in agreement with all the symmetries reported for members of the series. The symmetry-breaking phase transitions with temperature observed in many compounds can be explained in terms of a change in superspace group, again in common for the whole compound series. Inclusion of the incommensurate phases, present in many compounds of the series, lifts the analysis into a five-dimensional superspace. The various four-dimensional superspace groups reported for this incommensurate phase at different compositions are shown to be predictable from a proposed five-dimensional superspace group apparently common to the whole compound series. A comparison with the scarce number of refined structures in this system and the homologous (Nb,Ca)6Ti6O20 compound demonstrates the suitability of the proposed formalism.

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