Synthesis and Crystal Structures of Lithium Salts of New Iminophosphide/Phosphinoamide Anions

1997 ◽  
Vol 36 (18) ◽  
pp. 4087-4093 ◽  
Author(s):  
Norbert Poetschke ◽  
Martin Nieger ◽  
Masood A. Khan ◽  
Edgar Niecke ◽  
Michael T. Ashby
Keyword(s):  
Crystal Structures ◽  
Lithium Salts

Von Fluorsilylamiden zu Element-Silylamiden und Iminosilanen

2003 ◽  
Vol 58 (4) ◽  
pp. 246-256
Author(s):  
Michael Jendras ◽  
Uwe Klingebiel ◽  
Mathias Noltemeyer
Keyword(s):  
Crystal Structures ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
Molar Ratio ◽  
Lithium Salts ◽  
Analogous Reaction ◽  
Tert Butyl

Ethyltrifluorosilane reacts with tert-butyllithium in a molar ratio 1:2 to give Et(CMe3)2SiF (1), which forms the aminosilane, Et(CMe3)2SiNH2 (2) in the reaction with NaNH2. The lithium salt of 2 and (Me3C)2SiF2 gives (Me3C)2SiF-NHSi(CMe3)2Et (3). 3 reacts with BuLi to give the lithium salt, (Me3C)2 SiF-NLi-Si(CMe3)2Et (4). tert-Butyl-(di-tert-butylfluoro)-silylaminoalanes (Me3C)2SiF-NCMe3-AlR2, R = Me (5), Et (6) are formed in the reaction of (Me3C)2SiF-NLi CMe3 (I) and ClAlR2. The lithium salt (Me3C)2SiF-NLi-Si(CMe3)2Me (III) reacts with BF3 under formation of the bis(silyl)aminodifluoroborane (Me3C)2SiF-N(BF2) Si(CMe3)2Me (7). In the reaction of I with F3SiPh rotamers of (Me3C)2SiF-NCMe3 SiF2Ph (8) are obtained. Stannyl-silylamines are prepared in reactions of the lithium salts (Me3C)2SiF-NLiR, R = CMe3 (I), SiF(CMe3)2 (II); Si(CMe3)2Me (III) and the chlorostannanes ClSnMe3 (9,10,11) and Cl2SnPh2 (12), (Me3C)2SiF-NSnMe3-Si(CMe3)2R (9: R = F, 10: R = Me), (Me3C)2SiF-NSnMe3CMe3 (11), (Me3C)2SiF-NCMe3SnClPh2 (12). The NMR spectra of 9 and 10 prove the existence of rotamers. The reaction of III with Me3SiOSO2 CF3 in n-hexane leads to the formation of the tris(silyl)amine 13, (Me3C)SiF-NSiMe3)2Si(CMe3)2Me. However, the analogous reaction of III and 4 with Me3SiOSO2CF3 in thf leads to the formation of the stable iminosilanes 14 and 15, (Me3C)2Si==N- Si(CMe3)R, R = Me (14), Et (15) crystal structures of 7 and 12 are presented.

Synthesis of the hexaphenoxotungstate(V) ion; The x-ray crystal structures of the tetraethylammonium and lithium salts

Polyhedron ◽  
1982 ◽  
Vol 1 (7-8) ◽  
pp. 641-646 ◽  
Author(s):  
J.Iwan Davies ◽  
John F. Gibson ◽  
Andrzej C. Skapski ◽  
Geoffrey Wilkinson ◽  
Wong Wai-Kwok
Keyword(s):  
Crystal Structures ◽  
Lithium Salts ◽  
X Ray

Pollutant Identification by Selected Area Electron Diffraction

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.

The Imaging of Crystal Structures and Crystal Defects

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.

Transmission electron microscope studies in special ceramics

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.

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

CrystEngComm ◽  
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.

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

2019 ◽  
Vol 476 (21) ◽  
pp. 3227-3240 ◽  
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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