Bernt Krebs

Bio: Bernt Krebs is an academic researcher from University of Münster. The author has contributed to research in topics: Crystal structure & Ligand. The author has an hindex of 56, co-authored 729 publications receiving 16336 citations. Previous affiliations of Bernt Krebs include Leiden University & Clariant.

Chalkogenohalogenogallate(III) und -indate(III): Eine neue Verbindungsklasse in der dritten Hauptgruppe. Synthese und Struktur von [Ph4P]2[In2SX6], [Et4N]3[In3E3Cl6] · MeCN und [Et4N]3[Ga3S3Cl6] · THF (X = Cl, Br; E = S, Se)†

Abstract: [In2SCl6]2−, [In2SBr6]2−, [In3S3Cl6]3−, [In3Se3Cl6]3− und [Ga3S3Cl6]3− wurden als erste bisher bekannte Chalkogenohalogenoanionen von Elementen der 3. Hauptgruppe dargestellt. [Ph4P]2[In2SCl6] (1) (P1; a = 10,876(4) A, b = 12,711(6) A, c = 19,634(7) A, α = 107,21(3)°, β = 96,80(3)°, γ = 109,78(3)°; Z = 2) und [Ph4P]2[In2SBr6] (2) (C2/c; a = 48,290(9) A, b = 11,974(4) A, c = 17,188(5) A, β = 93,57(3)°, Z = 8) werden durch Reaktion von InX3, (CH3)3SiSSi(CH3)3 und Ph4PX (X = Cl, Br) in Acetonitril gebildet. [Et4N]3[In3S3Cl6] · MeCN (3) (P21/c; a = 17,328(4) A, b = 12,694(3) A, c = 21,409(4) A, β = 112,18(1)°, Z = 4), [Et4N]3[In3Se3Cl6] · MeCN (4) (P21/c; a = 17,460(4) A, b = 12,816(2) A, c = 21,513(4) A, β = 112,16(2)°, Z = 4) und [Et4N]3[Ga3S3Cl6] · THF (5) (P21/n; a = 11,967(3) A, b = 23,404(9) A, c = 16,260(3) A, β = 90,75(2)°, Z = 4) konnen durch Umsetzung von MCl3 (M = Ga, In) mit Et4NSH (3), (5) bzw. Et4NSeH (4) in Acetonitril (3), (4) bzw. Tetrahydrofuran (5) erhalten werden. In den Kristallstrukturen der Titelverbindungen 1 bis 5 liegen isolierte Anionen und Kationen vor. Die [In2SCl6]2−- und [In2SBr6]2−-Anionen in 1 und 2 lassen sich als Anordnung zweier uber ein gemeinsames Schwefelatom eckenverknupfter InSCl3- bzw. InSBr3- Tetraeder beschreiben. Die anionischen Teilstrukturen in 3, 4 und 5 werden durch drei Metallatome, die uber μ2-E-Atome (E = Schwefel, Selen) zu einem Sechsring miteinander verbunden sind, aufgebaut, wobei zwei Chloratome an jedem Metallatom dessen verzerrt-tetraedrische Koordination vervollstandigen. Chalcogenohalogenogallates(III) and -indates(III): A New Class of Compounds for Elements of the Third Main Group. Preparation and Structure of [Ph4P]2[In2SX6], [Et4N]3[In3E3Cl6] · MeCN and [Et4N]3[Ga3S3Cl6] · THF (X = Cl, Br; E = S, Se) [In2SCl6]2−, [In2SBr6]2−, [In3S3Cl6]3−, [In3Se3Cl6]3−, and [Ga3S3Cl6]3− were synthesised as the first known chalcogenohalogeno anions of main group 3 elements. [Ph4P]2[In2SCl6] (1) (P1; a = 10.876(4) A, b = 12.711(6) A, c = 19.634(7) A, α = 107.21(3)°, β = 96.80(3)°, γ = 109.78(3)°; Z = 2) and [Ph4P]2[In2SBr6] (2) (C2/c; a = 48.290(9) A, b = 11.974(4) A, c = 17.188(5) A, β = 93.57(3)°, Z = 8) were prepared by reaction of InX3, (CH3)3SiSSi(CH3)3 and Ph4PX (X = Cl, Br) in acetonitrile. The reaction of MCl3 (M = Ga, In) with Et4NSH/Et4NSeH in acetonitrile gave [Et4N]3[In3S3Cl6] · MeCN (3) (P21/c; a = 17.328(4) A, b = 12.694(3) A, c = 21.409(4) A, β = 112.18(1)°, Z = 4), [Et4N]3[In3Se3Cl6] · MeCN (4) (P21/c; a = 17.460(4) A, b = 12.816(2) A, c = 21.513(4) A, β = 112.16(2)°, Z = 4), and [Et4N]3[Ga3S3Cl6] · THF (5) (P21/n; a = 11.967(3) A, b = 23.404(9) A, c = 16.260(3) A, β = 90.75(2)°, Z = 4). The [In2SX6]2− anions (X = Cl, Br) in 1 and 2 consist of two InSX3 tetrahedra sharing a common sulfur atom. The frameworks of 3, 4 and 5 each contain a six-membered ring of alternating metal and chalcogen atoms. Two terminal chlorine atoms complete a distorted tetrahedral coordination sphere around each metal atom.

Kraftkonstanten des Trithiocarbonat-lons

Abstract: Mit der FG-Matrixmethode von WILSON wurden Kraftkonstanten des allgemeinen Valenzkraftsystems für das CS32-Ion berechnet. Es ergaben sich folgende Werte: fr=3,712·105, frr=0,688· 105, fα-fαα = 0,384.105, frα—f′rα =0,254·105, fγ= 0,533·105 dyn/cm Nach der Regel von BADGER wurde aus fr ein CS-Bindungsabstand von 1,68 Å ermittelt und nach der Produktregel von SIEBERT der CS-Bindungsgrad im CS32- abgeschätzt. Die Werte werden diskutiert.

Manganiferous polyoxometalates, synthesis and use thereof

Abstract: Manganiferous catalytically active polyoxometalates of formula (1) (Q)q (MnpAaXxYyMmOdZz(H2O)b) c H2O and the process for the manufacture thereof. In formula (I), Q, A, X, Y, M, Z, q, p, a, x, y, m, z, d, b and c have the following meaning: Q represents one or more cations selected from the group H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PR?1R2R3R4 and NR1R2R3R4 with R1, R2, R3 et R4? representing H or C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript q falls in a range of 1 to 60, more especially in a range of 1 to 40 and, in the case of a single-value counter-cation, also describes the charge on the anionic unit; Mn is manganese; subscript p falls in a range of 0.1 to 10, A is a heterometal and represents one or more transitional metals of the 2?nd to 8th? subsidiary groups except for Zn, especially Ru, V, Ti, Zr, Cr, Fe, Co, Cu, Sn, Ni, Re or Os; subscript a falls in a range of 0 to 10; X represents one or more elements selected from the group Ga, B, P, Si, Ge, As, F, Cl, Br and J; subscript x falls in the range of 0 to 10; Y represents Sb, S, Se, Te or Bi; subscript y falls in the range of 0.1 to 10; M represents one or more transition metals selected from the group Mo, W, Nb, Ta and V; subscript m falls in the range of 0.5 to 60; Z represents one or more anions selected from the group OH?-, F-, Cl-, Br-, I-, N?3-, NO3-, ClO4-, NCS-, SCN-, PF?6?-, RSO3-, RSO4-, CF3SO3-, BR4-, BF4-, OAc- with R = H, C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript z falls in the range 0 to 10; subscript d represents the number of oxygen atoms necessary to balance the charge and b and c are numbers in the range 0 to 50. The oxidisation catalysts described are particularly good for activating peroxide compounds and oxygen.

The chemistry of graphene oxide

Abstract: 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)

Phd by thesis

Abstract: 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

The hydrogen bond in the solid state.

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

Abstract: 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.

Multicopper Oxidases and Oxygenases

Abstract: 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.