A reversible skeletal rearrangement in a metal cluster complex; the formation and characterisation by i.r. spectroscopy and X-ray crystallography of Ru5C(CO)15.MeCN

1982 ◽  
pp. 289 ◽  
Author(s):  
Brian F. G. Johnson ◽  
Jack Lewis ◽  
J. Nicola Nicholls ◽  
Ian A. Oxton ◽  
Paul R. Raithby ◽  
...  
Keyword(s):  
Metal Cluster ◽  
Cluster Complex ◽  
Skeletal Rearrangement ◽  
X Ray ◽  
X Ray Crystallography

Triangular complexes of molybdenum and tungsten containing a ?2-Se2 ligand: X-ray examination of W2(?3-Se)(?2-Se2)3(dtc)4, the first M3Se7 metal cluster complex

1991 ◽  
Vol 40 (5) ◽  
pp. 1110-1110
Author(s):  
A. V. Virovets ◽  
N. V. Podberezskaya ◽  
V. P. Fedin ◽  
M. N. Sokolov ◽  
O. A. Geras'ko ◽  
...  
Keyword(s):  
Metal Cluster ◽  
Cluster Complex ◽  
X Ray ◽  
And Tungsten

The synthesis and x-ray crystal structure of the hexanuclear metal cluster complex [Ir3Pt3(μ-CO)3(CO)3(η-C5Me5)3]

Polyhedron ◽  
1984 ◽  
Vol 3 (9-10) ◽  
pp. 1093-1097 ◽  
Author(s):  
Mark J. Freeman ◽  
Anthony D. Miles ◽  
Martin Murray ◽  
A. Guy Orpen ◽  
F.Gordon A. Stone
Keyword(s):  
Crystal Structure ◽  
Metal Cluster ◽  
Cluster Complex ◽  
X Ray

scholarly journals Rearrangements during deamination of 4-amino-4-des(oxymethylene)anhydro-lycoctonam

1981 ◽  
Vol 59 (21) ◽  
pp. 3039-3043 ◽  
Author(s):  
O. E. Edwards
Keyword(s):  
Nitrous Acid ◽  
Skeletal Rearrangement ◽  
Diterpenoid Alkaloid ◽  
X Ray ◽  
X Ray Crystallography

The diterpenoid alkaloid lycoctonine was transformed into 4-amino-4-des(oxymethylene)anhydrolycoctonam. Nitrous acid deamination of this led to two unexpected products, an aldehydo-lactam acid and a hydroxy-keto lactam, both involving skeletal rearrangement. The origin of these products is discussed on the basis of structures determined by X-ray crystallography.

Photosystem II: an enzyme of global significance

2006 ◽  
Vol 34 (5) ◽  
pp. 619-631 ◽  
Author(s):  
J. Barber
Keyword(s):  
Photosystem Ii ◽  
Water Splitting ◽  
Organic Molecules ◽  
Metal Cluster ◽  
Thylakoid Membranes ◽  
Chemical System ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structural Details ◽  
Lipid Environment

Photosystem II (PSII) is a multisubunit enzyme embedded in the lipid environment of the thylakoid membranes of plants, algae and cyanobacteria. Powered by light, this enzyme catalyses the chemically and thermodynamically demanding reaction of water splitting. In so doing, it releases dioxygen into the atmosphere and provides the reducing equivalents required for the conversion of CO2 into the organic molecules of life. Recently, a fully refined structure of a 700 kDa cyanobacterial dimeric PSII complex was elucidated by X-ray crystallography which gave organizational and structural details of the 19 subunits (16 intrinsic and three extrinsic) which make up each monomer and provided information about the position and protein environments of 57 different cofactors. The water-splitting site was revealed as a cluster of four Mn ions and a Ca2+ ion surrounded by amino acid side chains, of which six or seven form direct ligands to the metals. The metal cluster was modelled as a cubane-like structure composed of three Mn ions and the Ca2+ linked by oxo-bonds with the fourth Mn attached to the cubane via one of its oxygens. The overall structure of the catalytic site is providing a framework to develop a mechanistic scheme for the water-splitting process, knowledge which could have significant implications for mimicking the reaction in an artificial chemical system.

scholarly journals Synthesis and Crystal Structure of a Novel Octahedral Fe4Cr2 Transition Metal Cluster Complex Cp2Cr2Fe4(CO)12(μ6-O)

1999 ◽  
Vol 23 (6) ◽  
pp. 388-389
Author(s):  
Li-Cheng Song ◽  
Wen-Qi Gao ◽  
Xiao-Ying Huang
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Diffraction Analysis ◽  
Metal Cluster ◽  
Cluster Complex ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Transition Metal Cluster

Reaction of Cp(OC)2Cr=S = Cr(CO)2Cp with Fe3(CO)12 affords an encapsulated μ6-O octahedral Fe4Cr2 cluster complex Cp2Cr2Fe4(CO)12(μ6-O), whose crystal structure is determined by X-ray diffraction analysis.

Skeletal Rearrangement in the Ritter Reaction of Turpentine: A Novel Synthesis of P-menthane Diamides

2017 ◽  
Vol 41 (2) ◽  
pp. 124-127 ◽  
Author(s):  
Shi-Chao Xu ◽  
Shou-Ji Zhu ◽  
Yu-Xiang Chen ◽  
Jing Wang ◽  
Liang-Wu Bi ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Ritter Reaction ◽  
Skeletal Rearrangement ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Novel Synthesis ◽  
Probable Reaction Mechanism ◽  
Probable Reaction ◽  
The Ritter Reaction

A novel skeletal rearrangement in the Ritter reaction was examined which conveniently generated p-menthane diamides from turpentine. A probable reaction mechanism was proposed based on employing thermodynamic analysis. All the products were purified and characterised by 1H NMR, IR, X-ray crystallography and ESI+-MS.

Difference Fourier Analysis of Glucose Embedded and Frozen Hydrated Purple Membrane

1982 ◽  
Vol 40 ◽  
pp. 74-75
Author(s):  
Jules S. Jaffe ◽  
Robert M. Glaeser
Keyword(s):  
Purple Membrane ◽  
Data Set ◽  
High Resolution Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fourier Techniques ◽  
Versus Protein ◽  
The Difference ◽  
Difference Fourier ◽  
Ideal Method

Although difference Fourier techniques are standard in X-ray crystallography it has only been very recently that electron crystallographers have been able to take advantage of this method. We have combined a high resolution data set for frozen glucose embedded Purple Membrane (PM) with a data set collected from PM prepared in the frozen hydrated state in order to visualize any differences in structure due to the different methods of preparation. The increased contrast between protein-ice versus protein-glucose may prove to be an advantage of the frozen hydrated technique for visualizing those parts of bacteriorhodopsin that are embedded in glucose. In addition, surface groups of the protein may be disordered in glucose and ordered in the frozen state. The sensitivity of the difference Fourier technique to small changes in structure provides an ideal method for testing this hypothesis.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

Sign in / Sign up

Export Citation Format

Share Document