Order and disorder of vanadyl chains: crystal structures of vanadyl dihydrogen arsenate (VO(H2AsO4)2) and the lithium derivative Li4VO(AsO4)2

Miguel A. G. Aranda; J. Paul Attfield; Sebastian Bruque; Maria Martinez-Lara

doi:10.1021/ic00032a023

SiF-NH-Funktionelle Cyclodisilazane – Synthese und Reaktivität / SiF-NH-Functional Cyclodisilazane – Synthesis and Reactivity

Zeitschrift für Naturforschung B ◽

10.1515/znb-2003-1002 ◽

2003 ◽

Vol 58 (10) ◽

pp. 939-949 ◽

Cited By ~ 1

Author(s):

Clemens Reiche ◽

Uwe Klingebiel ◽

Mathias Noltemeyer

Keyword(s):

Crystal Structures ◽

Liquid Ammonia ◽

Lithium Derivative ◽

Derivatives Of

Dichlorosilanes with bulky substituents R(Me3C)SiCl2 react with liquid ammonia to give geminal silyldiamines [R(Me3C)Si(NH2)2, 1: R = CH2 Me, 2: R = CHMe2]. In the reaction of the monolithium derivatives of these compounds with halosilanes 1-amino-1.3-disilazanes are obtained [(NH2)(Me3C)RSi-NH-SiR1R2R3; 3: R = CMe3, R1 = R2 = R3 = Me; 4: R = R1 = CMe3, R2 = R3 = Me; 5: R = R1 = R2 = CMe3, R3 = H; 6: R = R1 = CMe3, R2 = Me, R3 = F; 7: R = CHMe2, R1 = R2 = R3 = Me]. If monolithiated diamines are treated with trifluorosilanes cyclisation occurs to give (NH-Si(CMe3)2-NH-SiFR)cyclodisilazanes [R = N(SiMe3)(CMe3) (8); R = N(SiMe2CMe3)2 (9)]. 50% of the educts are recovered. The spirocyclic compound 10 is isolated from the reaction of the dilithiated 1-amino-1.3-disilazane 3 with F3SiN(SiMe2CMe3)2. NH-SiF-Functional cyclodisilazanes can be obtained in the reaction of the dilithium derivative of compound 4 with trifluorosilanes [(N(SiMe2CMe3)-Si(CMe3)2-NH-SiFR), R = Ph (11); R = CMe3 (12)]. The lithium derivative of 12 crystallises with TMEDA as adduct 13. In the reaction of the lithiated compound 12 with Me3SiCl, LiCl elimination and substitution of the N-atom is observed (14). The treatment of 13 with PhCHO leads to a 1.3-diaza-5-oxa-2.4-disila-cyclohexane (15 a, b). Starting from lithiated 12 the methoxysubstituted cyclodisiloxane 16 is accessible in the reaction with MeOH. As result of its reactivity towards Me2SiF2 the fluorosilyl-substituted cyclodisilazane 17 is obtained. Crystal structures of 9-11 and 13 have been determined.

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Cyclische Silylhydrazine - Kristallstrukturen isomerer fünf- und sechsgliedriger Ringe / Cyclic Silylhydrazines - Crystal Structures of Isomeric Five- and Six-Membered Rings

Zeitschrift für Naturforschung B ◽

10.1515/znb-2000-0611 ◽

2000 ◽

Vol 55 (6) ◽

pp. 504-510

Author(s):

Eike Gellermann ◽

Uwe Klingebiel ◽

Henning Witte-Abel ◽

Martina Schäfer

Keyword(s):

Crystal Structures ◽

Ring System ◽

Membered Ring ◽

Analogous Reaction ◽

Tert Butyl ◽

Lithium Derivative ◽

System 2 ◽

System 1

The lithium derivative of di(isopropyl)aminofluorosilylhydrazine cyclizes with formation of a five-membered silylhydrazine ring system (1). The analogous reaction of di(tert-butyl)- fluorosilylhydrazine gives the six-membered silylhydrazine ring system (2 ). 1 isomerizes thermally to the six-membered cyclic silylhydrazine 3. LiF-elimination from lithiated (Me3C)2- SiFNHNHSiF(CHMe2)2 leads to the formation of the six-membered cyclic silylhydrazine 4, [(Me2HC)2Si-NH-NSiF(CMe3)2]2. Symmetrical six-membered tetra(fluoro)silylhydrazine rings, (F2SiNRNR)2 (5: R = SiMe3, 6: R = SiMe2CMe3) are obtained in the reaction of bis(trifluorosilyl)hydrazines with dilithium-bis(silyl)hydrazides, whereas a five-membered unsymmetrical silylhydrazine (7: (RNSiF2)2N-NR'2, R = SiMe2CMe3, R′ = SiMe3) is formed in the reaction of R(SiF3)N-N(SiF3)R and R'(Li)N-N(Li)R'. In the reaction of the same fluorosilylhydrazine with dilithiated N,N'-diphenylhydrazide the unsymmetrical six-membered ring 8 is obtained. The crystal structures of 1, 2 and 3 are reported.

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Silylfurane und Bis(silyl)butadiine -Synthese, Lithiumderivate, Kristallstrukturen/ Silylfurans and Bis(silyl)butadiynes - Synthesis, Lithium Derivatives, Crystal Structures

Zeitschrift für Naturforschung B ◽

10.1515/znb-2000-1005 ◽

2000 ◽

Vol 55 (10) ◽

pp. 913-923 ◽

Cited By ~ 6

Author(s):

Peter Neugebauer ◽

Uwe Klingebiel ◽

Mathias Noltemeyer

Keyword(s):

Crystal Structures ◽

Membered Ring ◽

Molar Ratio ◽

Lithium Derivative ◽

F 14

AbstractFuran reacts with BuLi and halosilanes to give mono- (1, 5, 7), bis- (2, 6), tris- (3), and tetrakis(2-furanyl)silanes (4); (Fu-R; R = SiMe2Cl (1), SiisoPr2F (5), SitBu2F (7); Fu-R-Fu; R = SiMe2 (2), SiisoPr2 (6); Fu3SitBu (3), Fu4Si (4)), 2,5-Bis(silyl)furans (8, 9) are obtained in the reaction of dilithiated furan and fluorosilanes in a molar ratio 1:2 (R-Fu-R; R = SiisoPr2F (8), SitBu2F (9), 1,4-Bis(di-tert-butylfluorosilyl)butadiyne (10) is formed from furan four equivalents of BuLi, and two equivalents of F2SitBu2. 10 reacts with KOH to give tBu2(OH )Si-C =C -C =C-SitBu2OH (11). Substitution of the fluorine atoms of 5 and 7 by a NH2 group occurs with MNH2 (M = Li, Na). 12 and 13 are obtained. The reaction of 13 with BuLi and tBu2SiF2 leads to the formation of FuSitBu2NHSitBu2F (14) and tBu2Si(NH-SitBu2Fu)2 (15). The lithium derivative of 14 crystallizes as monomer from THF as FuSitBu2N(LiTHF2)SitBu2F and as a dimer containing a four-membered ring (16) from n-hexane (FuSitBu2NSitBu2LiF)2 (17). The crystal structures of 4, 10, 16,17 have been determined.

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Pollutant Identification by Selected Area Electron Diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052675 ◽

1974 ◽

Vol 32 ◽

pp. 532-533

Author(s):

R. E. Ferrell ◽

G. G. Paulson ◽

C. W. Walker

Keyword(s):

Thermal Treatment ◽

Electron Diffraction ◽

Sample Preparation ◽

Crystal Structures ◽

Water Samples ◽

Environmental Samples ◽

Short Review ◽

Selected Area Electron Diffraction ◽

Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

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The Imaging of Crystal Structures and Crystal Defects

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069995 ◽

1978 ◽

Vol 36 (3) ◽

pp. 207-217

Author(s):

J.M. Cowley

Keyword(s):

Electron Microscope ◽

Crystal Structures ◽

Phase Contrast ◽

Crystal Defects ◽

Atom Density ◽

Lack Of Information ◽

Spatial Frequencies

The problem of "understandinq" electron microscope imaqes becomes more acute as the resolution is improved. The naive interpretation of an imaqe as representinq the projection of an atom density becomes less and less appropriate. We are increasinqly forced to face the complexities of coherent imaqinq of what are essentially phase objects. Most electron microscopists are now aware that, for very thin weakly scatterinq objects such as thin unstained bioloqical specimens, hiqh resolution imaqes are best obtained near the optimum defocus, as prescribed by Scherzer, where the phase contrast imaqe qives a qood representation of the projected potential, apart from a lack of information on the lower spatial frequencies. But phase contrast imaqinq is never simple except in idealized limitinq cases.

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Transmission electron microscope studies in special ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108489 ◽

1978 ◽

Vol 36 (1) ◽

pp. 268-269

Author(s):

A. Zangvil ◽

L.J. Gauckler ◽

G. Schneider ◽

M. Rühle

Keyword(s):

Phase Diagrams ◽

Crystal Structures ◽

Thin Foil ◽

Limited Extent ◽

Complex Materials ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Electron Microscopes ◽

Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

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Advancing the use of Voronoi–Dirichlet polyhedra to describe interactions in organic molecular crystal structures by the example of galunisertib polymorphs

CrystEngComm ◽

10.1039/d0ce01535k ◽

2021 ◽

Author(s):

Viktor N. Serezhkin ◽

Anton V. Savchenkov

Keyword(s):

Crystal Structures ◽

Molecular Crystal ◽

Noncovalent Interactions ◽

Organic Molecular Crystal ◽

Universal Approach ◽

Structure Properties

The universal approach for studying structure/properties relationships shows that every polymorph of galunisertib is characterized with unique noncovalent interactions.

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Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1

Biochemical Journal ◽

10.1042/bcj20190289 ◽

2019 ◽

Vol 476 (21) ◽

pp. 3227-3240 ◽

Cited By ~ 1

Author(s):

Shanshan Wang ◽

Yanxiang Zhao ◽

Long Yi ◽

Minghe Shen ◽

Chao Wang ◽

...

Keyword(s):

Crystal Structures ◽

Conformational Changes ◽

Magnaporthe Oryzae ◽

Structural Information ◽

Complex Structure ◽

Critical Role ◽

Catalytic Process ◽

Structural Basis ◽

Salt Bridges ◽

Terminal Domain

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.

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