Structure diffraction

Engel T and Rieder K H 1982 Structural studies of surfaces with atomic and molecular beam diffraction Structural Studies of Surfaces With Atomic and Molecular Beam Scattering (Springer Tracts in Modern Physics vol 91) (Berlin Springer) pp 55-180... 

Molecular dynamics simulations of proteins often begin with a known structure (such as an X-ray diffraction structure) that you want to maintain during equilibration. Since the solvent may contain high energy hot spots, equilibration of the protein and solvent at the same time can change the protein conformation. To avoid this, select only the water molecules and run a molecular dynamics equilibration. This relaxes the water while fixing the protein structure. Then deselect the water and equilibrate the whole system. 

Figure 8.26 Schematic formula (a) molecular single crystal X-ray diffraction structure (b), and solid state packing (c) ofthe cationic gold complex [Au bimy(Ci6H33) 2]Br H20. (Reproduced from Ref [52] by permission.)...

Until recently, an erroneous structure for SOCI2 has been widely used in the literature according to which ClSCl 114° and OSCl 106°. These angles originated from an early (1938) electron diffraction work in which values smaller than 114° were simply not tested for ClSCl. Modern techniques of electron diffraction structure analysis are more reliable in avoiding such artifacts. 

Bond length differences between HS and LS isomers have been determined for a number of iron(II), iron(III) and cobalt(II) complexes on the basis of multiple temperature X-ray diffraction structure studies [6]. The available results have been collected in Table 17. Average values for the bond length changes characteristic for a particular transition-metal ion have been extracted from these data and are obtained as AR 0.17 A for iron(II) complexes, AR 0.13 A for iron(III) complexes, and AR = 0.06 A for cobalt(II) complexes. These values may be compared with the differences of ionic radii between the HS and LS forms of iron(II), iron(III) and cobalt(II) which were estimated some time ago [184] as 0.16, 0.095, and 0.085 A, respectively. 

Substantial effort has been invested in understanding how the linker(s) affect the metal-metal (M-M) distances, since the capacity of a cofacial porphyrin to accommodate a bridging diatomic molecule is often thought to be critical for achieving high catalytic activity. As of May 2007, 38 X-ray diffraction structures of cofacial porphyrins in Fig. 18.13 had been reported, with the DPA, DPB, DPD, and DPX... 

P212121 Z = 4 Dn = 1.540 R = 0.032 for 1,051 neutron intensities at 123 K. This was an experiment similar to that of the partially deuterated / -L-arabinopyranose already described. The results here were also negative. The room-temperature, neutron-diffraction structure of the un-deuterated compound had been determined previously.11... 

IR and Raman spectroscopy have been commonly used and, for example, the effects of pressure on the Raman spectrum of a zinc compound with a N2C12 coordination sphere around the metal, have been investigated.28 IR spectroscopy has been utilized in studies of the hydration of zinc in aqueous solution and in the hydrated perchlorate salt.29 Gas phase chemistry of zinc complexes has been studied with some gas phase electron diffraction structures including amide and dithiocarbamate compounds.30-32... 

The most well-characterized metalla-/3-diketone is 10 in that both X-ray and neutron diffraction structures have been determined (11 and 12) (26). 

Fig. 14 Single X-ray diffraction structure of ligand 1.59 (left) and its Pd(Me)Cl complex (1.61b) (right)...

Fu, Y. Bryan, N. 2002. One-step transfer of diffractive structure from a designed pattern to a replica by use of a hybrid solgel film. Optics Express 10 436 142. 

According to X-ray and neutron diffraction structures [3, 4] the binding of CO to the heme leads to a bent FeCO unit. The Fe-C-O angle is, however, found to be linear in synthetic models of the protein (hiomimetic molecules). Because of this, it was originally thought that the FeCO distortion was responsible for the well known discrimination of the protein against CO - the affinity ratio C0/02 is lower in the protein than in biomimetic systems [1]. In... 

Water on Vermiculite. For low water contents (that is, one or two water layers), the evidence for highly structured water in the interlayer spaces of smectites and vermiculites is most easily seen in X-ray diffraction structure determinations of ordered hydrate structures such as the two-water layer hydrate of Ca-vermiculite (14. 15) and Na-vermiculite (15., 16). 

X-ray Diffraction Structures of several clusters such as AU13, [17] Au55, [18] AU25, [19] and Au102 [21] have been determined. As an example, we describe below the crystal structure of phenylethanethiol capped Au25 clusters.[19] This cluster has an icosahedral Au13 core as shown in Fig. 2a. It is capped by an exterior shell... 

Concerned with the electron diffraction structure, the rotation of the cyclopentadienyl rings appears even faster than in ferrocene, hence their mutual disposition is difficult to establish. An X-ray diffraction study at 101 K has however shown that at this temperature the conformation is staggered.94 The increment in the Ni-C distance (2.18 A) compared to the Co-C distance (2.10 A) in cobaltocene reflects once again the increased population of the antibonding e" orbital (nickelocene has 20 valence electrons and a terminal electronic configuration e a e"2). 

Figure 49 (a) Electron diffraction structure of [Ni(r 5-CSH5)2]. Average Ni-C... 

This observation (coupled to NMR data) seemed to support the thesis that the complex was a non-classical hydride. (Unfortunately) the neutron diffraction structure of a few related complexes such as... 

Figure 56 Neutron diffraction structure of [ReH7(P p-MeC6H4 s)2]...

Key words electron diffraction, structure determination, low-dose CBED, protein strueture... 

Abstract Electron diffraction Structure Analysis is generally used to study thin films... 

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