The nature of aryloxide and arylsulfide ligand bonding in dimethyltitanium complexes containing cyclopentadienyl ligation

A series of dimethyltitanium compounds [CpTi(EAr)Me2](E = O, S) ligated by one cyclopentadienyl (Cp) and one aryloxide (OAr) or arylsulfide (SAr) have been structurally characterized in order to gain a better understanding of aryloxide and arylsulfide bonding in these systems. Experimental structures were compared to those predicted by density functional theory (DFT). Bonding in the arylsulfide systems was found to be significantly different from bonding in the aryloxide systems. The aryloxide ligands exhibited wide Ti-O-Ar angles > or = 150 degrees) with the Ar group oriented proximal to the Cp group. DFT computations revealed two conformers for the arylsulfide systems. Arylsulfides with the Ar group proximal to the Cp group had a predicted Ti-S-Ar angle of approximately 120 degrees while those with the Ar group distal to the Cp group had a measured and predicted Ti-S-Ar angle of approximately 100 degrees. Molecular and natural bond orbital (NBO) analyses were employed to explain the nature of ligand bonding in these systems.     

Determination of nitrogen in organic compounds

Summary A simplified method is described for the electrolytic generation of oxygen for use in the micro-Dumas determination of nitrogen. A flowmeter with an adjustable range is also described.

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Zusammenfassung Eine vereinfachte Anordnung zur elektrolytischen Sauerstoffentwicklung für die Verbrennung stickstoffhältiger Substanzen nach dem MikroDumas-Verfahren in einer Kohlendioxyd-Sauerstoff-Atmosphäre wird angegeben. Außerdem wird ein justierbarer Strömungsmesser beschrieben.

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Résumé On décrit une méthode simplifiée pour la production électrolytique de l'oxygène utilisé dans le microdosage de l'azote suivantDumas. On décrit aussi un fluxmètre à échelle réglable.

     

Stereoisomeric effects on mass spectral fragmentations of chloronorbornanones

Stereoelectronic factors allow facile Cl˙ atom loss from the exo-6-chloro-2-norbornanone radical cation but not from the endo-6-epimer. The predominant primary reaction in the endo-6 and in the exo-5 and endo-5 compounds is HCl elimination. While CI˙ elimination occurs with skeletal reorganization, HCl loss, at least in part, does not. The 5-chloro isomers undergo a regiospecific McLafferty rearrangement which occurs relatively slowly in competition with Cl˙ and HCl loss. The use of energy-resolved forms of tandem mass spectrometry provides considerable detail regarding the unimolecular fragmentations of these gaseous ions.     

Particle induced visual phenomena in space

There have been a large number of laboratory experiments on particle induced visual sensations which have resulted in a variety of visual phenomena that are similar in appearance to the so-called “light flashes” described by astronauts on Apollo missions 11 through 17 and Skylab 4. Unfortunately, no direct comparison of the laboratory and space observations have been made by observers who have experienced both. More than one physical mechanism has been shown to be involved in the laboratory phenomena and presumably in the space observations also. A number of models for particle induced visual phenomena are described and a quantitative estimate of their contribution to the space observations is attempted.