CI calculation of Spin Densities in π-radicals and ions using Hückel orbitals as a basis

Spin Densities have been calculated for a series of Conjugated Organic Radicals and Radical Ions using Hückel one-electron basis orbitals to generate all those singly excited configurations which interact with the ground state to produce first order changes in Spin Densities. The effect of variations of the different integral values is discussed, and the results compare well with both experiment and more elegant SCF calculations.

---

Zusammenfassung Für eine Reihe von konjugierten organischen Radikalen und ionischen Radikalen werden Spindichten berechnet. Aus einer Basis von Hückel'schen Einelektronenorbitalen werden alle die einfach angeregten Konfigurationen berechnet, die durch Wechselwirkung mit dem Grundzustand die Spindichte in 1. Näherung ändern. Der Einfluß der Variation verschiedener Integralwerte wird diskutiert. Die Ergebnisse zeigen gute Übereinstimmung sowohl mit dem Experiment wie mit ausführlicheren SCF-Rechnungen.

---

Résumé Les densités de spin ont été calculées pour une série de radicaux organiques et d'ions radicaux conjugués en utilisant une base d'orbitales de Hückel pour engendrer toutes les configurations monoexcitées qui interagissent avec l'état fondamental en produisant des variations du premier ordre des densités de spin. L'effet des variations des différentes valeurs d'intégrales est discuté; les résultats sont bien comparables tant aux données expérimentales qu'aux calculs SCF plus élégants.

     

Distribution of some elements in a solid - aqueous system: Mineral phosphate in contact with groundwater

The distribution of U, Th, Am, Eu, Cs, Sr and Ra in a solid-aqueous system, natural phosphate in contact with groundwater was investigated using g- and a-spectroscopy. The effect of contact time, pH, particle size of the solid phase, and the concentration of a concurrent element Ca, were studied. The results show that more than 98% of the actinide elements and europium are adsorbed by the solid phase under all conditions. The fission products Cs and Sr have different behaviors, depending on the experiment conditions. The behavior of Ra is closer to the actinides than to the fission products. There are small differences between the behaviors of the actinide elements, which can be interpreted by migration mechanism from the aqueous to the solid phase, i.e., adsorption or precipitation.     

(2-Vinyloxyethyl)hydrazines

Reaction of hydrazine hydrate with 2-chloroethyl vinyl ether afforded (2-vinyloxyethyl)hydrazine and 1,1-bis(2-vinyloxyethyl)hydrazine in 20-38% yield.     

Synthesis of 1, 2-diazabicyclo [4.4.0] decane and its derivatives

A new heterocyclic system, 1, 2-diazabicyclo [4.4.0] decane is synthesized, starting from-(piperidyl-2) propionic acid. The latter is converted to-(1-nitrosopiperidyl-2)-propionic acid, and thence, via-(1-aminopiperidyl-2) propionic acid, to 3-keto-1, 2-diazabicyclo [4.4.0] decane. Derivatives of 1, 2-diazabicyclo [4.4.0] decane with a substituent at position 2 are prepared.     

Electron screening in low energy scattering of muonic hydrogen on hydrogen atoms

Electron screening corrections to the cross sections for low energy scattering of muonic hydrogen on hydrogen atoms are calculated. It is shown that the presence of the electron influences considerably the elastic cross sections at collision energies below 1 eV. This influence is relatively small for the spin-flip and isotopic exchange processes.     

Separation and determination of arsenic(V) and arsenic(III) in sea-water by solvent extraction and atomic-absorption spectrophotometry by the hydride-generation technique

Arsenic(V) and arsenic(III) in sea-water have been separated by complexing the arsenic(III) with ammonium pyrrolidinedithiocarbamate (APDC) in the range 4.0-4.5 and extracting the complex with chloroform. The organic phase is then wet-ashed with a 1:1 mixture of concentrated nitric acid and perchloric acid to get rid of all organics, and the arsenic(III) is determined by hydride generation and atomic-absorption spectrophotometry. Total arsenic is determined by first reducing arsenic(V) to arsenic(III) with potassium iodide and then applying the method used for arsenic(III). The arsenic(V) content is determined by difference. The low detection limit of 0.031 ng ml and the high sensitivity and precision make the method suitable for analysis of open ocean waters.     

Nitration of pentaerythritol by HNO3-H2SO4-H2O system

Conclusions It was shown experimentally that the nitrating agent in the O-nitration of pentaerythritol by HNO₃-H₂SO₄-H₂O nitrating mixtures is not the nitronium cation but evidently the free unionized nitric acid molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 134–140, January, 1970.     

Hydroformylation and hydrocarbethoxylation of 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine

The unsaturated compounds 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine 1 and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine 2 have been hydroformylated and hydrocarbethoxylated in the presence of some well known cobalt, rhodium, palladium and platinum catalysts. The hydroformylation reaction can be tuned by a suitable choice of the catalyst precursor and reaction conditions, thus allowing the synthesis with high selectivity of one of the two possible isomeric aldehydes. The carbonylation reaction is less synthetically useful, since it shows low activity and unsatisfactory chemo- and regio-selectivity. However, the ester 1,2,4-tricarbethoxyhexahydropyridazine 10 can be prepared in good yield from olefin 1 by using the complex [PdCl₂(PPh₃)₂] as the catalyst precursor.     

Interaction of heavy metal ions with ammonium humates

Sorption properties of ammonium humates with respect to Fe(III), Cu(II), Al(III), Ni(II), Pb(II), and Zn(II) are studied. The effect of the metal ion concentration on the ammonium humate consumption is examined and the corresponding dependences are analyzed using regression equations. The IR spectra of brown coal humic acids, ammonium humates, as well as Fe, Cu, Ni, Zn, Pb, and Al humates are presented.