The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

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The chemistry of graphene oxide

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

The transition metal dichalcogenides are about 60 in number. Two-thirds of these assume layer structures. Crystals of such materials can be cleaved down to less than 1000 A and are then transparent in the region of direct band-to-band transitions. The transmission spectra of the family have been correlated group by group with the wide range of electrical and structural data available to yield useful working band models that are in accord with a molecular orbital approach. Several special topics have arisen; these include exciton screening, d-band formation, and the metal/insulator transition; also magnetism and superconductivity in such compounds. High pressure work seems to offer the possibility for testing the recent theory of excitonic insulators.

The transition metal dichalcogenides discussion and interpretation of the observed optical, electrical and structural properties

Copper is an essential trace element in living systems, present in the parts per million concentration range. It is a key cofactor in a diverse array of biological oxidation-reduction reactions. These involve either outer-sphere electron transfer, as in the blue copper proteins and the Cu{sub A} site of cytochrome oxidase and nitrous oxide redutase, or inner-sphere electron transfer in the binding, activation, and reduction of dioxygen, superoxide, nitrite, and nitrous oxide. Copper sites have historically been divided into three classes based on their spectroscopic features, which reflect the geometric and electronic structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centers. 428 refs.

Multicopper Oxidases and Oxygenases

Die Synthesen zweier neuer Heteropolyanionen mit Vanadium als Heteroatom werden vorgestellt. Sie wurden vollstandig durch Rontgenstrukturanalysen sowie IR- und Ramanspektroskopie charakterisiert. Die Verbindung ((CH3)4N)6Na4[(VO(H2O)2)2(WO2)2(BiW9O33)2]·18H2O (1) kristallisiert im triklinen Kristallsystem (P1¯) mit a = 13, 299(3)A, b = 13, 554(3)A, c = 18, 620(4)A und α = 90, 22(3)°, β = 91, 99(3)°, γ = 119, 16(3)°. Na5, 4K6, 6[(VO)3(AsW9O33)2]·29H2O (2) kristallisiert in der hexagonalen Raumgruppe P63/mmc mit den Zellkonstanten a = 15, 124(3)A und c = 24, 209(5)A.



Das Polyanion in 1 ist isostrukturell zu Anionen des sogenannten M2X2W20-Typs mit anderen Heteroatomen. Sie sind aus zwei β-B-[XW9O33]-Fragmenten aufgebaut, die sich von Defektstrukturen des Keggin-Anions ableiten lassen. Diese Untereinheiten sind uber zwei WO2-Gruppen zwei weitere M(H2O)3-Gruppen (M = Ubergangsmetall)verknupft und bilden so den M2X2W20-Typ aus. Das Anion in 2 ist ein neuer Vertreter des M3X2W18-Typs, in dem zwei α-B-[XW9O33]-Einheiten uber einen Ring aus drei Ubergangsmetallatomen verknuft sind.



New Heteropolyanions of Tungsten with Vanadium(IV) as a Heteroatom



The syntheses of two new heteropolyanions with vanadium as heteroatom are presented. They are characterized by X-ray structure analysis and vibrational spectra. ((CH3)4N)6Na4[(VO(H2O)2)2(WO2)2(BiW9O33)2]·18H2O (1) crystallises in the triclinic crystal system (P1¯) with a = 13.299(3)A, b = 13.554(3)A, c = 18.620(4)A and α = 90.22(3)°, β = 91.99(3)°, γ = 119.16(3)°. Na5.4K6.6[(VO)3(AsW9O33)2]·29H2O (2) crystallises in the hexagonal space group P63/mmc with a = 15.124(3)A and c = 24.209(5)A.



The polyanion in 1 is isostructural to anions of the M2X2W20-typ with other heteroatoms. They are built up by two β-B-[SbW9O33] fragments, which are derived from defect structures of the Keggin anion. These subunits are connected by two formal WO2 groups with further stabilisation by addition of two M(H2O)3 groups leading to the M2X2W20-type heteropolytungstates. The anion in 2 is a new example of the M3X2W18-type, which contains two α-B-[XW9O33]-units connected via a belt of three transition metal atoms.

Neue Heteropolyanionen des Wolframs mit Vanadium(IV) als Heteroatom

(NH4)2[(S2)2Mo(S2)2Mo(S2)2].2H2O, a novel sulfur-rich coordination compound with two nonequivalent complex anions having the same point group but different structures: crystal and molecular structures

Three novel dinuclear palladium(II) complexes with the chelating ligand bis(1-methylimidazol-2-yl) ketone (bmik) as well as pyridine-2-thiolate (pyt), pyrimidine-2-thiolate (pymt), and 1-methylimidazole-2-thiolate (meimt) as bridging secondary ligands were prepared by reactions of diaqua[bis(1-methylimidazol-2-yl) ketone]palladium(II) nitrate with the ligands in aqueous solution. The thiolates bridge the two metal atoms in the μ-N,S mode. The structures of the following compounds were analyzed by single crystal X-ray diffraction: Bis(μ-pyridine-2-thiolato-N,S)-bis{[bis(1-methyl-imidazol-2-yl) ketone]palladium(II)}nitrate [Pd2(bmik)2-(pyt)2](NO3)2 · 5 H2O (1), bis(μ-pyrimidine-2-thiolato-N1,S)- bis{[bis(1-methylimidazol-2-yl) ketone]palladium(II)} nitrate [Pd2(bmik)2(pymt)2](NO3)2 · 5 H2O (2), and bis(μ-1-methyl-imidazole-2-thiolato-N3,S)-bis{[bis(1-methylimidazol-2-yl) ketone]palladium(II)} nitrate [Pd2(bmik)2(meimt)2](NO3)2 · 4.5 H2O (3). In the cases of 1 and 3 the bridging thiolate ligands show head-to-head orientation. For complex 2 a head-to-tail orientation of the pyrimidine-2-thiolates was found. The metal-metal distances vary from 2.963 A in complex 3 and 2.915 A in 1 to the shortest of 2.886 A in 2. In addition to the X-ray crystallography the three compounds were characterized by 1H-NMR and IR spectroscopy.

Novel dinuclear palladium(II) complexes with the chelating ligand bis(1‐methylimidazol‐2‐yl) ketone (bmik) and pyridine‐2‐thiolate, pyrimidine‐2‐thiolate, and 1‐methylimidazole‐2‐thiolate as bridging secondary ligands

Organic Syntheses via Transition Metal Complexes, 51. – 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into MC and CC Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively



1-Metalla-1,3,5-trienes LnMC(NEt2)–C(Me)C(OEt)–CHCHPh (3,4) and LnMC(OEt)– CHC(NEt2) – C(Me)=CHPh [5, LnMCr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnMC(OEt) – CHCHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N–C C – Me (2) into the MC and the CC bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnMC(NEt2) – C(Me)=C(OEt) – C CPh [9, 10, LnMCr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the MC bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.

Organische Synthesen mit übergangsmetall‐Komplexen, 51. 1‐Metalla‐1,3,5‐triene und 1‐Metalla‐1,3‐dien‐5‐ine von Chrom und Wolfram durch Insertion von Alkinen in MC‐ bzw. CC‐Bindungen von 1‐Metalla‐1,3‐dienen bzw. 1‐Metalla‐1‐en‐2‐inen

Bernt Krebs

Papers

Neue Heteropolyanionen des Wolframs mit Vanadium(IV) als Heteroatom

(NH4)2[(S2)2Mo(S2)2Mo(S2)2].2H2O, a novel sulfur-rich coordination compound with two nonequivalent complex anions having the same point group but different structures: crystal and molecular structures

Novel dinuclear palladium(II) complexes with the chelating ligand bis(1‐methylimidazol‐2‐yl) ketone (bmik) and pyridine‐2‐thiolate, pyrimidine‐2‐thiolate, and 1‐methylimidazole‐2‐thiolate as bridging secondary ligands

Organische Synthesen mit übergangsmetall‐Komplexen, 51. 1‐Metalla‐1,3,5‐triene und 1‐Metalla‐1,3‐dien‐5‐ine von Chrom und Wolfram durch Insertion von Alkinen in MC‐ bzw. CC‐Bindungen von 1‐Metalla‐1,3‐dienen bzw. 1‐Metalla‐1‐en‐2‐inen

Cover Picture: Pentanuclear Platinum(II) Macrocycles with Nucleobases (Angew. Chem. Int. Ed. 10/2004)