Five-Coordinate Complexes [FeX(depe)2]BPh4, X = Cl, Br: Electronic Structure and Spin-Forbidden Reaction with N2
The bonding of N(2) to the five-coordinate complexes [FeX(depe)(2)](+), X = Cl (1a) and Br (1b), has been investigated with the help of X-ray crystallography, spectroscopy, and quantum-chemical calculations. Complexes 1a and 1b are found to have an XP(4) coordination that is intermediate between square-pyramidal and trigonal-bipyramidal. Mössbauer and optical absorption spectroscopy coupled with angular overlap model (AOM) calculations reveal that 1a and 1b have (3)B(1) ground states deriving from a (xz)(1)(z(2))(1) configuration. The zero-field splitting for this state is found to be 30-35 cm(-1). In contrast, the analogous dinitrogen complexes [FeX(N(2))(depe)(2)](+), X = Cl (2a) and Br (…
Synthesis, Structure, and Electrical Properties of Ta 4 FeTe 4
Ta4FeTe4 has been synthesized and its structure determined by single-crystal X-ray methods. It crystallizes in the ortho-rhombic space group Pbam with Z = 4 and a = 10.514(5), b = 18.275(7), and c = 4.815(1) A. Ta4FeTe4 has a chain structure built up by Fe-centered Ta8-square antiprisms sharing common square faces. The resistivity of Ta4FeTe4 has been measured by a two-point method. Ta4FeTe4 shows metallic behavior. The structure of Ta4FeTe4 is discussed in relation to other early transition metal cluster compounds. A rational approach to the synthesis of related compounds is proposed.
A comparison between the chemical behaviour of lead-gold and lead-bismuth eutectics towards 316L stainless steel
Radiochimica acta, 101 (10)
ChemInform Abstract: NbNi2.38Te3, a New Metal-Rich Niobium Telluride with a “Stuffed” TaFe1+ xTe3 Structure.
The authors report the synthesis, structure, and electrical properties of NbNi{sub 2.38}Te{sub 3}. The structure of the compound was determined by X-ray crystallography and the electric conductivity of the compound was measured.
TaNi 2 .05Te 3 , eine Verbindung mit “aufgefüllter” TaFe 1+ x Te 3 ‐Struktur
TaNi2.05Te3, a Novel Telluride with “Stuffed” TaFe1+xTe3 Structure The novel metal-rich layer compound TaNi2.05Te3 was synthesized from the elements. Its structure contains TaNi2Te3 layers which are interconnected by Ni atoms on partially occupied tetragonal-pyramidal sites located between the layers. The title compound and the related telluride TaFe1.14Te3 form a pair of compounds differing only in the occupation or nonoccupation of one 3d-material atom site. Therefore, the structure of TaNi2.05Te3, which is stabilized by interstial Ni atoms, can be regarded as a “stuffed” TaFe1.14Te3 type. Pairs of compounds with a similar structural relationship seem to be of general importance in early …
NbxRu6-xTe8, New Chevrel-Type Clusters Containing Niobium and Ruthenium,
Phases of composition Nb(x)()Ru(6)(-)(x)()Te(8) were prepared by reacting stoichiometric mixtures of the elements at high temperature in evacuated silica ampules. The structure of Nb(3.33)Ru(2.67)Te(8) was refined from X-ray powder data using the Rietveld method. Nb(3.33)Ru(2.67)Te(8) crystallizes isotypic with Mo(6)Q(8) (Q = S, Se, Te) in the rhombohedral space group Rthremacr; with the hexagonal lattice parameters a = 10.34106(5) Å, c = 11.47953(7) Å, and Z = 3. Its structure consists of M(6)Te(8) mixed-metal clusters (M = Nb, Ru) which are connected by intercluster M-Te bonds to form a three-dimensional network. Metal-metal bonding in these phases is analyzed in terms of Pauling bond ord…
ChemInform Abstract: Ta1.09Fe2.39Te4, a New Non-Stoichiometric Ternary Tantalum Telluride.
Abstract Ta1.09Fe2.39Te4 was prepared by chemical transport from the elements in sealed silica tubes in a temperature gradient from 700 to 600 °C. It crystallizes in the monoclinic space group P2/m with a = 6.162(2) A , b = 7.852(3) A , c = 7.250(3) A , β = 95.32(3)° and Z = 2 . Its structure can be derived from a hexagonal close packing of tellurium atoms with tantalum and iron atoms in octahedral voids and additional iron atoms in tetrahedral voids. The structure is closely related to the structures of MM'Te2 (MNb, Ta; M′Fe, Co, Ni) and MxFeγTe2 (MNb, x = 0.89, γ = 0.93; MTa, x = 0.77, γ = 0.90).
ChemInform Abstract: TaNi2.05Te3, a Novel Telluride with “Stuffed” TaFe1+xTe3 Structure.
Scanning Probe Microscopy Study of the Metal-Rich Layered Chalcogenides TaM2Te2 (M = Co, Ni)
The compounds TaNi2Te2 and TaCo2Te2 have been examined by scanning tunneling and atomic force microscopy. The title phases crystallize in layered structures with metal slabs sandwiched by tellurium atoms. Scanning probe microscope images of the surfaces of these materials arise from the surface tellurium atoms anddepending on the experimental conditionscan show very different features. The images have been simulated through surface charge densities calculated within the Extended Huckel and LMTO frameworks.
ChemInform Abstract: NbxRu6-xTe8, New Chevrel-Type Clusters Containing Niobium and Ruthenium.
Lead–gold eutectic: An alternative liquid target material candidate for high power spallation neutron sources
Abstract One of the main technical concerns of Megawatt-class spallation neutron sources is the removal of the heat deposited in the target station. A way to overcome it is to use targets consisting of flowing liquid metals, but the already tested materials – mercury and lead–bismuth eutectic (LBE) – are not unproblematic. We show here that another eutectic alloy containing lead and gold (LGE) could be a suitable alternative. Besides a chemical toxicity lower than mercury, this low melting-point alloy has the advantage of being solid at RT. Moreover, it combines a neutron production similar to mercury and LBE with smaller amounts of alpha-emitting nuclides, relieving safety and environmenta…