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 use of conductivity measurements in organic solvents for the characterisation of coordination compounds

For present purposes, a protein-bound metal site consists of one or more metal ions and all protein side chain and exogenous bridging and terminal ligands that define the first coordination sphere of each metal ion. Such sites can be classified into five basic types with the indicated functions: (1) structural -- configuration (in part) of protein tertiary and/or quaternary structure; (2) storage -- uptake, binding, and release of metals in soluble form: (3) electron transfer -- uptake, release, and storage of electrons; (4) dioxygen binding -- metal-O{sub 2} coordination and decoordination; and (5) catalytic -- substrate binding, activation, and turnover. The authors present here a classification and structure/function analysis of native metal sites based on these functions, where 5 is an extensive class subdivided by the type of reaction catalyzed. Within this purview, coverage of the various site types is extensive, but not exhaustive. The purpose of this exposition is to present examples of all types of sites and to relate, insofar as is currently feasible, the structure and function of selected types. The authors largely confine their considerations to the sites themselves, with due recognition that these site features are coupled to protein structure at all levels. In themore » next section, the coordination chemistry of metalloprotein sites and the unique properties of a protein as a ligand are briefly summarized. Structure/function relationships are systematically explored and tabulations of structurally defined sites presented. Finally, future directions in bioinorganic research in the context of metal site chemistry are considered. 620 refs.« less

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Structural and Functional Aspects of Metal Sites in Biology

Great attention is currently paid to the synthesis of polynuclear transition metal complexes and the study of their photochemical, photophysical, and electrochemical properties. This interest is stimulated, in particular, by attempts to design and construct multicomponent systems (often called supramolecular species) capable of performing useful lightand/or redox-induced functions.1-16 A great deal of investigations on mononuclear transition metal complexes had previously shown that several families of these compounds are very interesting from the electrochemical, photochemical, and photophysical viewpoints.17-22 The metalligand interaction, in fact, is often (i) weak enough to allow the manifestation of intrinsic properties of metal and ligands (e.g., ligand-centered and metalcentered absorption bands and redox waves) and, at the same time, (ii) strong enough to cause the appearance of new properties, characteristic of the whole compound (e.g., metal-to-ligand or ligand-tometal charge-transfer bands). On passing from mononuclear to polynuclear transition metal complexes, the situation becomes even more interesting because in the latter (supramolecular) compounds one can find, besides properties related to each metal-based component, properties related to the structure and composition of the whole array. A suitable choice of the mononuclear building blocks and bridging ligands and an appropriate design of the (supramolecular) structure can in fact allow the occurrence of very interesting and potentially useful processes such as energy transfer along predetermined pathways, photoinduced charge separation, multielectron exchange at a predetermined potential, etc. The knowledge on the luminescence and redox properties of polynuclear transition metal complexes is rapidly accumulating, but it is disperse in a great number of journals. We have made an attempt to collect the available results, and we present them together with some fundamental introductory concepts and a few comments. One of the main problems, of course, was to delimit the field of this review. Using personal criteria which are related to our own research interests, we decided to consider only polynuclear transition metal complexes that can be defined as supramolecular species (section 2.2) and that are reported to exhibit luminescence. For such compounds only, the electrochemical properties have also been reviewed. Furthermore, we decided to include only classical (Werner-type) polynuclear transition metal compounds where the number of metal-based units is exactly known and the connection between the metal centers is provided only by bridging ligands. Thus, a number of interesting systems such as polymer-appended metal † In memoriam of Mauro Ciano. 759 Chem. Rev. 1996, 96, 759−833

Luminescent and Redox-Active Polynuclear Transition Metal Complexes.

Photophysics, photochemistry and solar energy conversion with tris(bipyridyl)ruthenium(II) and its analogues

Publisher Summary This review is concerned with the neglected class of inorganic compounds, which contain ions of the same element in two different formal states of oxidation. Although the number of references cited in our review show that many individual examples of this class have been studied, yet they have very rarely been treated as a class, and there has never before, to our knowledge, been a systematic attempt to classify their properties in terms of their electronic and molecular structures. In the past, systems containing an element in two different states of oxidation have gone by various names, the terms “mixed valence,” nonintegral valence,” “mixed oxidation,” “oscillating valency,” and “controlled valency” being used interchangeably. Actually, none of these is completely accurate or all-embracing, but in our hope to avoid the introduction of yet another definition, we have somewhat arbitrarily adopted the phrase “mixed valence” for the description of these systems. The concept of resonance among various valence bond structures is one of the cornerstones of modern organic chemistry.

Mixed Valence Chemistry-A Survey and Classification

The synthesis and physical characterization of a complex of BEDT-TTF [bis(ethylenedithio)tetrathiafulvalenium] with Cu II Cl 4 2- are reported. The structure of (BEDT-TTF) 3 CuCl 4 .H 2 O (I) (crystal data: triclinic, space group P1, a=16.634 A, b=16.225 A, c=8.980 A, c=90.72 o , β=93.24 o , γ=96.76°, V=2402 A 3 , Z=2) consists of alternating layers of organic cations and inorganic anions.

Structure and properties of tris[bis(ethylenedithio)tetrathiafulvalenium]tetrachlorocopper(II) hydrate, (BEDT-TTF)3CuCl4.H2O: first evidence for coexistence of localized and conduction electrons in a metallic charge-transfer salt

Magnetotransport measurements have been carried out on the organic superconductor kappa -(BEDT-TTF)2Cu(NCS)2 at temperatures down to 500 mK and in hydrostatic pressures up to 16.3 kbar. The observation of Shubnikov-de Haas and magnetic breakdown oscillations has allowed the pressure dependences of the area of the closed pocket of the Fermi surface and the carrier effective masses to be deduced and compared with simultaneous measurements of the superconducting critical temperature Tc. The effective mass measured by the temperature dependence of the Shubnikov-de Haas oscillations is found to fall rapidly with increasing pressure up to a critical pressure Pc approximately=5 kbar. Above Pc a much weaker pressure dependence is observed; Tc also falls rapidly with pressure from 10.4 K at ambient pressure to zero at around Pc. This strongly suggests that the enhanced effective mass and the superconducting behaviour are directly connected in this organic superconductor. A simplified model of the band structure of kappa -(BEDT-TTF)2Cu(NCS)2 has been used to derive the bare band masses of the electrons from optical data. Comparisons of these parameters with cyclotron resonance data and the effective masses measured in the present experiments indicate that the greater part of the enhancement of the effective mass necessary for superconductivity in this material is due to quasiparticle interactions, with the electron-phonon interactions playing a secondary role. The dependence of Tc on the effective mass may be fitted satisfactorily to a suitably parametrized weak-coupling BCS expression, although this cannot be taken as a definitive proof of the nature of superconductivity in organic conductors.

https://iopscience.iop.org/article/10.1088/0953-8984/6/15/013/pdf

Magnetotransport studies of the organic superconductor kappa -(BEDT-TTF)2Cu(NCS)2 under pressure: the relationship between carrier effective mass and critical temperature

In contrast with intercalation compounds, which can exist both with and without organic molecules between the planes of inorganic material, ‘molecular composite’ compounds have organic groups covalently or ionically bound to inorganic layers. In such crystals the aim is to combine magnetic or optical properties characteristic of the inorganic solid state, like magnetism and luminescence, with properties found in the organic solid state like mesomorphism or polymerization. This contribution surveys experiments from our laboratory on the structural, physical and chemical properties of one series of ‘molecular composites’, the layer perovskite halide salts (RNH 3 ) 2 MX 4 (R = organic group; M = Cr, Mn, Cd; X = Cl, Br). When R is an n -alkyl group these compounds undergo structural phase transitions triggered by variations in the hydrogen-bonding of the −NH 3 to the inorganic layer. Optical microscopy is used to follow the phase transitions and map ferroelastic domains. Compounds with M = Cr are ferromagnets with strongly temperature-dependent visible absorption spectra, whose intensity correlates with the degree of magnetic order. In Mn and Cd salts more elaborate functional groups can be inserted in the organic sidechains with the aim of making topochemical polymerizations in the solid state.

Organic-inorganic layer compounds: physical properties and chemical reactions

(1981). Mixed Valency Chemistry: A Survey of 10 Years Progress. International Reviews in Physical Chemistry: Vol. 1, No. 2, pp. 149-193.

Peter Day

Papers

Mixed Valence Chemistry-A Survey and Classification

Structure and properties of tris[bis(ethylenedithio)tetrathiafulvalenium]tetrachlorocopper(II) hydrate, (BEDT-TTF)3CuCl4.H2O: first evidence for coexistence of localized and conduction electrons in a metallic charge-transfer salt

Magnetotransport studies of the organic superconductor kappa -(BEDT-TTF)2Cu(NCS)2 under pressure: the relationship between carrier effective mass and critical temperature

Organic-inorganic layer compounds: physical properties and chemical reactions

Mixed Valency Chemistry: A Survey of 10 Years Progress