A Brief 100 Year History of Carbon

2017 ◽  
Vol 100 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Terence J. Kemp
Keyword(s):  
Elemental Carbon ◽  
Industrial Revolution ◽  
Materials Science ◽  
Molecular Structures ◽  
Carbon Fibres ◽  
X Ray ◽  
X Ray Crystallography ◽  
Recent Developments ◽  
History Of ◽  
Carbon Molecule

Elemental carbon has been known from time immemorial in its forms of diamond and graphite, while the Industrial Revolution was powered by coal. The molecular structures of diamond and graphite were established following the inception of X-ray crystallography while the complex natures of charcoal and coal have been investigated for 100 years. Recent developments in activated charcoal are described in an article in this issue of Science Progress. However, no-one could have guessed that carbon would have presented such structural surprises as those of C60 fullerene, carbon nanotubes, and graphene. Materials science has benefited from the discovery of carbon fibres, and our understanding of the spectroscopy and bonding in the simplest carbon molecule, C2, has reached new depths.

Synthesis, structural characterization and catalytic activity of chlororuthenium(II) complexes with substituted Schiff base/phosphine ancillary ligands

2020 ◽  
Vol 75 (9-10) ◽  
pp. 851-857
Author(s):  
Chong Chen ◽  
Fule Wu ◽  
Jiao Ji ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Structural Characterization ◽  
Room Temperature ◽  
Molecular Structures ◽  
Cationic Complex ◽  
Neutral Complex ◽  
Ancillary Ligands ◽  
X Ray ◽  
X Ray Crystallography

AbstractTreatment of [(η6-p-cymene)RuCl2]2 with one equivalent of chlorodiphenylphosphine in tetrahydrofuran at reflux afforded a neutral complex [(η6-p-cymene)RuCl2(κ1-P-PPh2OH)] (1). Similarly, the reaction of [Ru(bpy)2Cl2·2H2O] (bpy = 2,2′-bipyridine) and chlorodiphenylphosphine in methanol gave a cationic complex [Ru(bpy)2Cl(κ1-P-PPh2OCH3)](PF6) (2), while treatment of [RuCl2(PPh3)3] with [2-(C5H4N)CH=N(CH2)2N(CH3)2] (L1) in tetrahydrofuran at room temperature afforded a ruthenium(II) complex [Ru(PPh3)Cl2(κ3-N,N,N-L1)] (3). Interaction of the chloro-bridged complex [Ru(CO)2Cl2]n with one equivalent of [Ph2P(o-C6H4)CH=N(CH2)2N(CH3)2] (L2) led to the isolation of [Ru(CO)Cl2(κ3-P,N,N-L2)] (4). The molecular structures of the ruthenium(II) complexes 1–4 have been determined by single-crystal X-ray crystallography. The properties of the ruthenium(II) complex 4 as a hydrogenation catalyst for acetophenone were also tested.

Recent Developments In Monochromatic Microprobe X-Ray Fluorescence (MMXRF)

1998 ◽  
Vol 4 (S2) ◽  
pp. 378-379
Author(s):  
Z. W. Chen ◽  
D. B. Wittry
Keyword(s):  
Materials Science ◽  
High Vacuum ◽  
Three Dimensional ◽  
High Sensitivity ◽  
X Rays ◽  
Fluorescence Excitation ◽  
X Ray ◽  
Quantitative Microanalysis ◽  
Recent Developments ◽  
Fifth Order

A monochromatic x-ray microprobe based on a laboratory source has recently been developed in our laboratory and used for fluorescence excitation. This technique provides high sensitivity (ppm to ppb), nondestructive, quantitative microanalysis with minimum sample preparation and does not require a high vacuum specimen chamber. It is expected that this technique (MMXRF) will have important applications in materials science, geological sciences and biological science.Three-dimensional focusing of x-rays can be obtained by using diffraction from doubly curved crystals. In our MMXRF setup, a small x-ray source was produced by the bombardment of a selected target with a focused electron beam and a toroidal mica diffractor with Johann pointfocusing geometry was used to focus characteristic x-rays from the source. In the previous work ∼ 108 photons/s were obtained in a Cu Kα probe of 75 μm × 43 μm in the specimen plane using the fifth order reflection of the (002) planes of mica.

scholarly journals Silylated gallium and indium chalcogenide ring systems as potential precursors to ME (E=O, S) materials

2013 ◽  
Vol 11 (7) ◽  
pp. 1225-1238
Author(s):  
Iliana Medina-Ramírez ◽  
Cynthia Floyd ◽  
Joel Mague ◽  
Mark Fink
Keyword(s):  
Thermal Decomposition ◽  
Room Temperature ◽  
Membered Ring ◽  
Molecular Structures ◽  
Nmr Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
High Yields ◽  
Vt Nmr ◽  
State 1

AbstractThe reaction of R3M (M=Ga, In) with HESiR′3 (E=O, S; R′3=Ph3, iPr3, Et3, tBuMe2) leads to the formation of (Me2GaOSiPh3)2(1); (Me2GaOSitBuMe2)2(2); (Me2GaOSiEt3)2(3); (Me2InOSiPh3)2(4); (Me2InOSitBuMe2)2(5); (Me2InOSiEt3)2(6); (Me2GaSSiPh3)2(7); (Et2GaSSiPh3)2(8); (Me2GaSSiiPr3)2(9); (Et2GaSSiiPr3)2(10); (Me2InSSiPh3)3(11); (Me2InSSiiPr3)n(12), in high yields at room temperature. The compounds have been characterized by multinuclear NMR and in most cases by X-ray crystallography. The molecular structures of (1), (4), (7) and (8) have been determined. Compounds (3), (6) and (10) are liquids at room temperature. In the solid state, (1), (4), (7) and (9) are dimers with central core of the dimer being composed of a M2E2 four-membered ring. VT-NMR studies of (7) show facile redistribution between four- and six-membered rings in solution. The thermal decomposition of (1)–(12) was examined by TGA and range from 200 to 350°C. Bulk pyrolysis of (1) and (2) led to the formation of Ga2O3; (4) and (5) In metal; (7)–(10) GaS and (11)–(12) InS powders, respectively.

scholarly journals Recent developments and future of the GM/CA@APS X-ray crystallography user facility at the Advanced Photon Source

2018 ◽  
Vol 74 (a1) ◽  
pp. a324-a324
Author(s):  
Michael Becker ◽  
Stephen Corcoran ◽  
Dale Ferguson ◽  
Mark Hilgart ◽  
David J. Kissick ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Crystallography ◽  
Recent Developments ◽  
User Facility ◽  
Photon Source

Multipurpose diffractometer for in situ X-ray crystallography of functional materials

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Semën Gorfman ◽  
David Spirito ◽  
Netanela Cohen ◽  
Peter Siffalovic ◽  
Peter Nadazdy ◽  
...  
Keyword(s):  
Electric Field ◽  
Materials Science ◽  
Functional Materials ◽  
X Ray Diffraction ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
X Ray Crystallography ◽  
Area Detector ◽  
Characterization Of Materials

Laboratory X-ray diffractometers play a crucial role in X-ray crystallography and materials science. Such instruments still vastly outnumber synchrotron facilities and are responsible for most of the X-ray characterization of materials around the world. The efforts to enhance the design and performance of in-house X-ray diffraction instruments benefit a broad research community. Here, the realization of a custom-built multipurpose four-circle diffractometer in the laboratory for X-ray crystallography of functional materials at Tel Aviv University, Israel, is reported. The instrument is equipped with a microfocus Cu-based X-ray source, collimating X-ray optics, four-bounce monochromator, four-circle goniometer, large (PILATUS3 R 1M) pixel area detector, analyser crystal and scintillating counter. It is suitable for a broad range of tasks in X-ray crystallography/structure analysis and materials science. All the relevant X-ray beam parameters (total flux, flux density, beam divergence, monochromaticity) are reported and several applications such as determination of the crystal orientation matrix and high-resolution reciprocal-space mapping are demonstrated. The diffractometer is suitable for measuring X-ray diffraction in situ under an external electric field, as demonstrated by the measurement of electric-field-dependent rocking curves of a quartz single crystal. The diffractometer can be used as an independent research instrument, but also as a training platform and for preparation for synchrotron experiments.

Übergangsmetallkomplexe mit Schwefelliganden, LXXIII. Diastereospezifische Dichlormethylierung schwefelreicher [RuII(SRR′)(PPh3)′S4]-Komplexe (SRR′ = einzähniger Thioether- oder Thiol-Ligand; ′S4′2- = 1,2-Bis(2-mercaptophenylthio)ethan(2-)) / Transition Metal Complexes with Sulfur Ligands, LXXIII. Diastereospecific Dichloromethylation of Sulfur Rich [RuII(SRR′)(PPh3)′S4] Complexes (SRR′ = Monodentate Thioether or Thiol Ligand;′S4′2- = 1,2-Bis(2-mercaptophenylthio)ethane(2-))

1991 ◽  
Vol 46 (12) ◽  
pp. 1585-1592 ◽  
Author(s):  
Dieter Sellmann ◽  
Peter Lechner ◽  
Falk Knoch ◽  
Matthias Moll
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Molecular Structures ◽  
X Ray ◽  
X Ray Crystallography ◽  
Thiol Ligand

Under exclusion of air the thioether and thiol complexes [Ru(SRR′)(PPh3)′S4′] (′S4′2- = 1,2-bis(2-mercaptophenylthio)ethane (2—)) easily react with CHCl3 yielding [Ru(Cl)(PPh3)(′S4′—CHCl2)] in which one thiolato atom of the ′S4′ ligand is diastereospecifically dichloromethylated. In the presence of air, however, [RuIII(Cl)(PPh3)′S4′] is formed.The molecular structures of [Ru(Cl)(PPh3)(′S4′-CHCl2)] · 2CHCl3 and [RuIII(Cl)(PPh3)′buS4′] have been determined by X-ray crystallography. ′buS4′2- (= 1,2-bis(3,5-di(t-butyl)-2-mercaptophenylthio)ethane(2-)) is the t-butyl derivative of the ′S4′ ligand. Reasons for observed diastereospecifity of alkylation are discussed.

The Time of Pioneers

1999 ◽  
Vol 5 (S2) ◽  
pp. 542-543
Author(s):  
J. Philibert
Keyword(s):  
Electron Probe ◽  
Materials Science ◽  
Doctoral Degree ◽  
Quartz Crystals ◽  
X Ray ◽  
Physical Problems ◽  
Main Column ◽  
Continuous Background ◽  
History Of ◽  
Electron Microscopes

This paper will cover the history of the first steps of electron probe microanalysis. I was not personally involved with the electron microprobe at the very beginning, although I have been fully involved in the field from 1955. Nevertheless I have interesting information about the heroic times - when, just after the World War, Raimond Castaing was preparing for his doctoral degree.In January 1947, R. Castaing, graduate in physics, joined the Institute for Aeronautical Research (ONERA), recently created by the French government. In the Materials Science Department, he was very lucky to be endowed with two electron microscopes, very exceptional equipment - a real luxury in 1948. The first one, an American RCA instrument was devoted to metallurgical studies. The second one, build by a French company, was cannibalized by Castaing to produce a fine electron beam to perform point chemical analysis. The idea was suggested to him by Andre Guinier, a famous x-ray crystallographer (Guinier-Preston zones, discovered in 1939) as the best way to solve identification problems in metallography. Castaing was not so enthusiastic about this proposal; the story seemed to him too simple, so simple, he thought, that it was quite surprising that nobody had done it before; but he soon had to face many physical problems that made him understand why many people probably failed, especially lens aberrations that had to be corrected to produce the intense, fine beam of electrons. Another question soon arose about x-ray detection. It was easy to detect the continuous background, but not very informative. Finally Guinier lent Castaing one of his precious quartz crystals (specially cut and ground, of the Johanson type); it was adjusted on a small spectrograph that fitted the outside of the main column (safety rules were in their infancy!). In the first days of 1949, he was able to measure characteristic x-ray emission from a l-μm, 4 nA electron probe. Considering the poor conditions in France after the terrible war, the rapidity with which this result was obtained is quite remarkable.

3(5),4-Dimethyl- and 3,4,5-trimethylpyrazole at 200 K. X-ray crystallography and quantum-chemical analysis

1999 ◽  
Vol 55 (3) ◽  
pp. 441-447 ◽  
Author(s):  
Lourdes Infantes ◽  
Concepción Foces-Foces ◽  
Jose Elguero
Keyword(s):  
Quantum Chemical ◽  
Molecular Structures ◽  
Asymmetric Unit ◽  
Quantum Chemical Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Crystal And Molecular Structures ◽  
Unit Form ◽  
Proton Disorder ◽  
Independent Molecules

The crystal and molecular structures of 3(5),4-dimethylpyrazole, C5H8N2, (I), and of 3,4,5-trimethylpyrazole, C6H10N2, (II), have been determined at 200 K. In (I) the 4,5-dimethylpyrazole tautomer is present in the solid state and the six independent molecules in the asymmetric unit form trimers via NH...N hydrogen bonds related by a pseudo centre of symmetry. The asymmetric unit of (II) contains one and a half molecules: these exhibit NH proton disorder and are hydrogen bonded to each other via their respective NH groups to form chains. Ab initio calculations at HF and B3LYP/6-31G** levels indicate that the 3,4-dimethylpyrazole tautomer is more stable than the 4,5-dimethylpyrazole tautomer by only approximately 0.5  kcal  mol−1 (1 kcal mol−1 = 4.184 kJ mol−1).

New homodinuclear tris(3-alkylpyrazolyl)borate complexes of CoIIand NiIIwith a tetraacetylethane dianion as a bridging ligand

2016 ◽  
Vol 72 (11) ◽  
pp. 777-785
Author(s):  
Elena A. Mikhalyova ◽  
Swiatoslaw Trofimenko ◽  
Matthias Zeller ◽  
Anthony W. Addison ◽  
Vitaly V. Pavlishchuk
Keyword(s):  
Metal Ions ◽  
Coordination Polymers ◽  
Metal Ion ◽  
Molecular Structures ◽  
Polynuclear Complexes ◽  
X Ray ◽  
X Ray Crystallography ◽  
Coordination Sites ◽  
Borate Complexes ◽  
Capping Ligands

Polynuclear complexes and coordination polymers of 3dmetals have attracted significant interest evoked by a number of their unique properties. One of the most common approaches to the directed synthesis of coordination polymers is the linking of pre-prepared discrete coordination units by polydentate ligands. The formation of polynuclear complexes is usually a spontaneous process and precise prediction of the products of such reactions is virtually impossible in most cases. Tris(pyrazolyl)borates (Tp) act as tripodal `capping' ligands which form stable complexes with 3dmetal ions. In such 1:1 compounds, three metal-ion coordination sites are occupied by N atoms from a Tp anion. This limits the number of remaining coordination sites, and thus the number of additional ligands which may coordinate, and opens an attractive approach for the directed design of desirable structures by exploiting ligands with appropriate composition and topology. In the present study, Tp anions with neopentyl [TpNp, tris(3-neopentylpyrazolyl)borate] and cyclohexyl [TpCy, tris(3-cyclohexylpyrazolyl)borate] substituents were used as `capping' ligands and the dianion of tetraacetylethane (3,4-diacetylhexa-2,4-diene-2,5-diolate, tae2−) was employed as a bridge. The dinuclear complexes (μ-3,4-diacetylhexa-2,4-diene-2,5-diolato-κ4O2,O3:O4,O5)bis{[tris(3-cyclohexyl-1H-pyrazol-1-yl-κN2)borato]cobalt(II)} acetonitrile disolvate, [Co2(C27H40BN6)2(C10H12O4)]·2CH3CN, (I)·2CH3CN, and (μ-3,4-diacetylhexa-2,4-diene-2,5-diolato-κ4O2,O3:O4,O5)bis{[tris(3-neopentyl-1H-pyrazol-1-yl-κN2)borato]nickel(II)}, [Ni2(C24H40BN6)2(C10H12O4)], (II), were synthesized by the reaction of the mononuclear complexes TpCyCoCl or TpNpNiCl with H2tae (3,4-diacetylhexane-2,5-dione or tetraacetylethane) in the presence of NEt3as base. Compounds (I) and (II) were characterized by mass spectrometry, elemental analysis, and X-ray crystallography. They possess similar molecular structures, X-ray diffraction revealing them to be dinuclear in nature and composed of discrete Tp–Munits in which two metal ions are linked by a tae2−dianion. Each metal ion possesses a five-coordinate square-pyramidal environment. The interplanar angles between the acetylacetonate fragments are significantly smaller than the near-90° values commonly observed.

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