Quantitative Extraktion von Blei und Zink als Verbindungen der Diphenylarsins?ure

Zusammenfassung Es wird über die Möglichkeit berichtet, die Metalle Blei und Zink mit Hilfe von Diphenylarsinsäure als Reagens und Chloroform als Lösungsmittel aus wäßriger Lösung zu extrahieren. Trennungen sind nur von den Erdalkalien möglich, bei Zinkextraktion auch von Cadmium, wenn eine doppelte Extraktion angewendet wird. Belegwerte werden beigebracht.

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Summary Lead and zinc may be separated from alkaline earth metals by extraction from aqueous solution using diphenylarsinic acid as reagent and chloroform as solvent. Zinc can also be separated from cadmium when a double extraction is employed. Results are presented.

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Herrn Prof. Dr. A. Musil, Vorstand des Instituts für anorganische und analytische Chemie der Universität Graz, zum 65. Geburtstag gewidmet.     

PhPMe2 ligand substitution in the tetracobalt cluster Co4(CO)10(μ4-PPh)2: X-ray diffraction structure of Co4(CO)8(PPhMe2)2(μ4-PPh)2

The thermal substitution chemistry of the tetracobalt cluster Co₄(CO)₁₀(₄-PPh)₂ with the phosphine ligand PhPMe₂ (2.5 equiv) has been explored and found to afford the bis(phosphine)-substituted cluster Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ as the major reaction product. The regiochemistry and stereoselectivity exhibited by the two phosphine ligands in Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ have been unambiguously established by X-diffraction analysis as having a 1,3-cis orientation. Co₄(CO)₈(PPhMe₂)₂(₄-PPh)₂ crystallizes in the monoclinic space group P2₁/n,a=10.314(1) Å,b=18.051(3) Å,c=21.313(2) Å, =90.10(1)°,V=3968.0(8) ų,Z=4,d _calc=1.590 g cm^–3;R=0.051,R _w=0.042 for 4987 observed reflections withI>3(I). Generalizations concerning the stereochemical disposition of two P-ligands about the Co₄(CO)₈P₂(₄-PPh)₂ (where P=phosphine or phosphite) polyhedron are discussed with respect to the cone angle of the P-ligand and its steric interactions with the capping phenylphosphinidene group.     

N‐(o‐Chloro­phenyl)‐2,5‐di­methyl­pyrrole‐3‐carb­aldehyde

Crystal structure analysis of the title compound, C₁₃H₁₂ClNO, reveals three crystallographically independent mol­ecules in the asymmetric unit. The main conformational difference between these mol­ecules is the orientation of the phenyl rings with respect to the pyrrole rings. The coplanar arrangement of the aldehyde groups attached to the pyrrole rings influences the pyrrole‐ring geometry. The C2—C3 and N1—C5 bonds are noticeably longer than the C4—C5 and N1—C2 bonds. Two independent mol­ecules of the title compound form dimers via intermolecular C—H⃛O hydrogen bonds [D⃛A = 3.400 (3) Å and D—H⃛A = 157°]. The perpendicular orientation of the phenyl and pyrrole rings of one independent mol­ecule and its symmetry‐related mol­ecule allows C—H⃛π interactions, with an H⃛centroid distance of 2.85 Å and a C—H⃛π angle of 155°. The distances between the H atom and the pyrrole‐ring atoms indicate that the C—H bond points towards one of the bonds in the pyrrole ring.     

The bilinear assignment problem: complexity and polynomially solvable special cases

Mathematical Programming - In this paper we study the bilinear assignment problem (BAP) with size parameters m and n, $$m\le n$$ . BAP is a generalization of the well known quadratic assignment...     

Refraction effects in the generation of helical surface waves on a cylindrical obstacle

We investigate the scattering of compressional waves from an infinite, circular-cylindrical obstacle, and the excitation during the scattering process of surface waves that propagate along helical paths over the cylinder surface. For the case of a rigid or soft obstacle, the surface waves are external, and are obtained via the use of a Watson transformation. For the case of a penetrable cylinder, additional internal, resonant surface waves are generated for which the phase and group velocity dispersion curves can be obtained from the Resonance Scattering Theory. We perform a detailed study of certain refraction effects which take place upon the generation of the surface waves by the incident plane wave.     

A solution-processable electron acceptor based on diketopyrrolopyrrole and naphthalenediimide motifs for organic solar cells

A novel, solution-processable small molecular electron acceptor (HP1) based on diketopyrrolopyrrole and naphthalenediimide fragments was designed and synthesized via a Stille coupling reaction, characterized by spectroscopic means, and exhibited excellent solubility and thermal stability. HP1 exerted strong and very broad absorption tailing into the near infra-red region, with appropriate energy levels matching with the archetypal electron donor, poly(3-hexylthiophene) (P3HT), and afforded 1.02% power conversion efficiency with a high open-circuit voltage (1.05 V) when tested in solution-processable bulk-heterojunction devices.