Polarised IR and Raman spectra of monoglycine dihydrogenphosphate single crystal

Polarised Raman, IR and FIR spectra of the monoglycine dihydrogenphosphate (glycinium dihydrogenphosphate) single crystal samples are presented and discussed with respect to the crystal structure on the basis of oriented gas model approximation. The IR and FIR spectra were measured by specular reflection method and spectra of an imaginary part of the refractive indices were computed by the Kramers-Kronig transformation. The polarisation properties of the internal vibrations of the glycinium cation, H₂PO₄¹⁻ anion and hydrogen bonds are predicted and compared to the experimentally determined.     

Possible gas-phase ion pairs in amine-HCl complexes. An ab initio theoretical study

Ab initio MO calculations were performed for complexes between HCl and NH₃, CH₃NH₂, (CH₃)₂NH and (CH₃) ₃N. SCF geometry optimization for the latter three complexes gives double-minimum potential surfaces, which become single- minimum surfaces when electron correlation is considered. It is proposed that (CH₃)₃NHCl may be an ion pair in the gas phase.     

The dispersity of γ-alumina supported rhenium from hydrogen pulse chemisorption

The applicability of hydrogen chemisorption in a pulse chromatographic system for determining the dispersity of -alumina supported rhenium catalysts (10.4 wt.% and 1.04 wt.%) preheated in hydrogen at 550–800 °C is shown.

---

, - (10,4 .% 1,04 .%), 550–800°C.

     

CNDO/2 study on lithium bonding in lithium methoxide—Amine systems

A systematic CNDO/2 study has been carried out on the lithium-bonded model systems, CH₃OLi–NR ₃, formed between lithium methoxide and aliphatic amines. Significant correlations between calculated molecular properties of the complexes and the ionization potentials of the amines have been found, and these are discussed on the basis ofMulliken's charge transfer theory. Similarities and differencies between the lithium bond and the hydrogen bond are discussed.

---

CNDO/2 Untersuchungen der Lithium-Bindung in Lithiummethoxid—Amin-Systemen

Zusammenfassung Es wurde für das Modellsystem CH₃OLi–NR ₃ eine systematische CNDO/2 Studie durchgeführt um die Lithium-Bindung zwischen Lithiummethoxid und einer Reihe von aliphatischen Aminen zu untersuchen. Es wurde eine signifikante Korrelation zwischen den berechneten Eigenschaften der Komplexe und den Ionisierungspotentialen der Amine gefunden; das wird auf Basis der Elektronen-Donor-Acceptor Theorie nachMulliken diskutiert. Lithium-und Wasserstoff-Brücken-Bindung werden gegenübergestellt und Analogien bzw. Unterschiede herausgearbeitet.

     

Diastereomeric Oxathia[n](1,1′)ferrocenophanes

Zusammenfassung Neue Oxathiaferrocenophane wurden durch Umsetzung von 1,1-Bis(hydroxymethyl)ferrocen mit Dithiolen dargestellt, welche Sauerstoff in den Alkylketten enthalten. Die Reaktion von 1,1-Bis(-hydroxyethyl)ferrocenen mit Dithiolen führte zu Mischungen von Diastereomeren, aus welchen reine Stereoisomere isoliert und charakterisiert wurden. Einige Aspekte des stereochemischen Verlaufes dieser Reaktionen werden diskutiert.

---

Diastereomere oxathia[n](1,1)ferrocenophane

Novel oxathiaferrocenophanes have been synthesized by the reaction of 1,1-bis(hydroxymethyl)ferrocene with dithiols bearing oxygen in chains. The reactions of 1,1-bis(-hydroxyethyl)ferrocenes with dithiols afforded mixtures of diastereomeric products from which pure stereoisomers were isolated and characterized. Some aspects concerning a stereochemical course of the reactions described are discussed.

     

Five-membered heterocycles. Part III. Aromaticity of 1,3-imidazole in 5+n hetero-bicyclic molecules

The aromaticity (in the form of HOMA index) of 1,3-imidazole ring and its bicyclic derivatives was studied on the basis of statistical data from Cambridge Structural Database and X-ray investigations performed by authors. As a starting point, aromaticity of the 1,3-imidazoles with exocyclic X substituent at C2 (XN, O or S) was calculated. Subsequently, the HOMA index was calculated for various 5+n bicyclic skeletons with N, O, and S as endocyclic heteroatoms in the second ring. For the isolated 1,3-imidazole ring, aromaticity depends on exocyclic substituent at C2 and decreases in sequence N, S, O. For bicyclic derivatives it was found that both rings are aromatic and coplanar in very few molecules (17% of investigated ones), and positive charge—located on endocyclic heteroatom—increases the aromaticity. For remaining compounds, presence of sp³ carbons excludes possibility of aromatic ring existence.     

A kinetic study of the aqueous phase oxidation of di-μ-oxo-bis(L-cysteine)-oxomolybdenum(V) by molecular oxygen

The molecular oxygen-mediated decomposition of the binuclear complex, prepared from oxomolybdate(V) and L-(+)-cysteine, was studied spectrophotometrically at pH 3.5–5.6. The formation of MoVI was detected. The effects of pH and [O2] on the decomposition kinetics are given by the equation:

Connecting Ruthenium Photocatalysis to 1,2-Dioxetane-Mediated Chemiluminescence: a Versatile Combination for Optical Detection and Read-Out

Optical storage and photon quantification systems based on sensitive photoreactions have numerous applications. Herein, we report a highly efficient photocatalytic reaction, in which ruthenium photoredox catalysis is combined with a 1,2-dioxetane from which chemiluminescence can be triggered. In this system, blue light irradiation as optical input enables a defined inverse correlation with base-triggered, blue light emission as optical output. Comparison of readout by ¹H NMR and chemiluminescence, relative to previous optical input, underlines the reliability and usefulness of the ruthenium-dioxetane system for optical storage, sensing and ruthenium detection.     

2α-Hydroxy-3α-[N-alkyl(aryl)]pinanoamines. Part I. Preparation and nature of some Schiff bases of 2α-hydroxypinan-3-one. Crystal and molecular structure of α-hydroxy-2,6,6-trimethylbicyclo[3.1.1]hepta-3-ylidenaminobenzene

Some Schiff bases of 2-hydroxypinan-3-one, being precursors of 2-hydroxy3-[N-alkyl(aryl)]pinanoamines, were obtained. The crystal structure of racemic 2-hydroxy-2,6,6-trimethylbicyclo-[3.1. 1]hept-3-ylidenaminobenzene was determined. The Schiff bases were obtained in two forms: solid form (racemate) and liquid form (optically pure). As it appeared from crystallographic studies of the racemic form, in the solid state there are intramolecular-H-bonded dimers.