Structural Studies of Some Compounds Containing C2 Fragments Attached to Various Metal-Ligand End-Groups

2011 ◽  
Vol 637 (9) ◽  
pp. 1207-1212 ◽  
Author(s):  
Michael I. Bruce ◽  
Maryka Gaudio ◽  
Benjamin C. Hall ◽  
Brian K. Nicholson ◽  
Gary J. Perkins ◽  
...  
Keyword(s):  
Structural Studies ◽  
End Groups ◽  
Metal Ligand

Structural studies of oligosilanes produced by catalytic dehydrogenative coupling of primary organosilanes

1987 ◽  
Vol 65 (8) ◽  
pp. 1804-1809 ◽  
Author(s):  
C. Aitken ◽  
J. F. Harrod ◽  
U. S. Gill
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Gel Permeation Chromatography ◽  
Structural Studies ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Dehydrogenative Coupling ◽  
Weight Distributions ◽  
Gel Permeation ◽  
End Groups

The structures of some poly(organosilylenes), [Formula: see text] (R = Ph, p-tolyl, n-hexyl, and benzyl), produced by catalytic dehydrogenative coupling of primary silanes have been studied by infrared, nuclear magnetic resonance, and mass spectroscopies. These results, combined with data on molecular weights and molecular weight distributions from vapour pressure osmometry and gel permeation chromatography, lead to the conclusion that the polymers are linear and have SiH2R end groups. The polymers all have degrees of polymerization of ca. 10 and very narrow molecular weight dipersions. Some possible features of the mechanism that gives rise to this behaviour are discussed.

THE POLYSACCHARIDES OF CRYPTOCOCCUS LAURENTII (NRRL Y-1401): PART I

1960 ◽  
Vol 38 (9) ◽  
pp. 1617-1624 ◽  
Author(s):  
M. J. Abercrombie ◽  
J. K. N. Jones ◽  
M. V. Lock ◽  
M. B. Perry ◽  
R. J. Stoodley
Keyword(s):  
Glucuronic Acid ◽  
Extracellular Polysaccharides ◽  
Cryptococcus Laurentii ◽  
Structural Studies ◽  
Acidic Polysaccharide ◽  
End Groups

The extracellular polysaccharides produced by Cryptococcuslaurentii have been isolated and shown to consist of (A) an acidic polysaccharide containing D-mannose, D-xylose, and D-glucuronic acid; (B) a neutral polysaccharide containing D-glucose only.Preliminary structural studies on the acidic material suggest that it consists of a mannose-containing backbone with xylose and glucuronic acid as end groups, while the glucan contains 1 → 3, 1 → 4, 1 → 2, and (or) 1 → 6 linked residues.

Lewis-Base Adducts of Lead(II) Compounds. XVIII. Synthetic and Structural Studies of Some 1:1 and 2:1 Adducts of 2,4,6-Tris (2-pyridyl)-1,3,5-triazine With Lead(II) Nitrate

1996 ◽  
Vol 49 (10) ◽  
pp. 1147 ◽  
Author(s):  
JM Harrowfield ◽  
DL Kepert ◽  
H Miyamae ◽  
BW Skelton ◽  
AA Soudi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polymer Chain ◽  
Room Temperature ◽  
Lewis Base ◽  
Lead Atom ◽  
Structural Studies ◽  
Complex Species ◽  
X Ray ◽  
The Third ◽  
Metal Ligand

Adducts of lead(II) nitrate with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (' trz ') have been synthesized and structurally characterized by room-temperature single-crystal X-ray studies, for 1:1 and 1:2 stoichiometry. Crystals of [( trz ) Pb (NO3)2](∞|∞) are monoclinic, P 21/c, a 10.531 (1), b 12.856(2), c 16.874(3) Ǻ, β 102.83(1)°, Z = 4 f.u .; R was 0.027 for No = 2773 'observed' (I > 3σ(I)) reflections. The complex is an infinite polymer; the plane of the tridentate trz ligand lies normal to the polymer axis ( Pb -N(central; distal) 2.523(5); 2.594(5), 2.568(5) Ǻ) with unsymmetrically bidentate nitrate groups to either side ( Pb -O 2.598(6), 2.928(7); 2.556(6), 2.911(7) Ǻ). The third oxygen of each nitrate group bridges to the next lead atom in the polymer chain ( Pb -O 3.008(5), 3.083(6)Ǻ). [( trz )2Pb(NO3)2] is monoclinic, C 2/c, a 15.723(5), b 10.034(2), c 24.379(15) Ǻ, β 106.84(4)°, Z = 4 f.u .; R was 0.038 for No 3030. The compound is a methanol monosolvate. The complex species is mononuclear, with the lead atom located on a crystallographic 2 axis and 10-coordinated by pairs of symmetry-related tridentate trz ( Pb -N(central; distal) 2.779(4); 2.800(5), 2.818(5) Ǻ) and bidentate nitrate ligands ( Pb -O 2.796(6), 2.689(5)Ǻ). A hexahydrate has also been obtained (triclinic, Pī a 23.580(9), b 10.147(4), c 9.762(4)Ǻ, α 113.14(3), β 92.11(3), γ 101.60(3)°, Z = 2 f.u ; R 0.041 for No 5633); although metal-ligand distances are similar to those found in the methanol solvate, and quasi-2 symmetry is retained, a very different stereochemistry is evident in respect of the relative dispositions of the ligands about the (quasi)-2 axis, involving a substantial twist of the two nitrate ligands relative to the triazines, and a flattening of the latter. The coordination polyhedron is different in the two 1:2 adducts. In the methanol solvate the stereochemistry is pentagonal antiprismatic whereas in the hexahydrate it is bicapped square antiprismatic.

Structural Studies of Vacuum-Deposited Thin Film of Permethyloligosilanes with Phenyl End Groups

2000 ◽  
Vol 39 (Part 2, No. 10A) ◽  
pp. L1002-L1005 ◽  
Author(s):  
Yoshiro Ichino ◽  
Tetsuo Yatabe ◽  
Nobutsugu Minami
Keyword(s):  
Thin Film ◽  
Structural Studies ◽  
End Groups

scholarly journals Structural studies of metal ligand complexes by ion mobility-mass spectrometry

2013 ◽  
Vol 16 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Victoria E. Wright ◽  
Fernando Castro-Gómez ◽  
Ewa Jurneczko ◽  
James C. Reynolds ◽  
Andrew Poulton ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ion Mobility ◽  
Ion Mobility Mass Spectrometry ◽  
Structural Studies ◽  
Metal Ligand

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Structural Studies on Mitotic Spindle Fibres

1978 ◽  
Vol 36 (3) ◽  
pp. 615-626
Author(s):  
J.R. Mcintosh
Keyword(s):  
Chemical Composition ◽  
Mitotic Spindle ◽  
Structural Studies ◽  
Mitotic Apparatus ◽  
Chemical Studies ◽  
Medical Interest ◽  
Spindle Fibres

The mitotic apparatus is a structure of obvious biological and medical interest, but it has proved to be a difficult cellular machine to understand. The chemical composition of the spindle is only slightly elucidated, largely because of the difficulties in preparing useful isolates of the structure. Chemical studies of the mitotic spindle have been reviewed elsewhere (Mcintosh, 1977), and will not be discussed further here. One would think that structural studies on the mitotic apparatus (MA) in situ would be straightforward, but even with this approach there is some disagreement in the results obtained with various methods and by different investigators. In this paper I will review briefly the approaches which have been used in structural studies of the MA, pointing out the strengths and problems of each approach. I will summarize the principal findings of the different methods, and identify what seem to be fruitful avenues for further work.

Image registration with a computer driven S.T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 98-99
Author(s):  
A.M.H. Schepman ◽  
J.A.P. van der Voort ◽  
J.E. Mellema
Keyword(s):  
Spot Size ◽  
Scanning Transmission Electron Microscope ◽  
Small Computer ◽  
Structural Studies ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Specimen Area ◽  
On Line ◽  
Minimum Distances

A Scanning Transmission Electron Microscope (STEM) was coupled to a small computer. The system (see Fig. 1) has been built using a Philips EM400, equipped with a scanning attachment and a DEC PDP11/34 computer with 34K memory. The gun (Fig. 2) consists of a continuously renewed tip of radius 0.2 to 0.4 μm of a tungsten wire heated just below its melting point by a focussed laser beam (1). On-line operation procedures were developped aiming at the reduction of the amount of radiation of the specimen area of interest, while selecting the various imaging parameters and upon registration of the information content. Whereas the theoretical limiting spot size is 0.75 nm (2), routine resolution checks showed minimum distances in the order 1.2 to 1.5 nm between corresponding intensity maxima in successive scans. This value is sufficient for structural studies of regular biological material to test the performance of STEM over high resolution CTEM.

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