Loss Of Ethylene Research Articles

Preparation and reactions of some ionic organoplatinum(II) complexes

The ionic complexes [Pt(diphos)(PEt3)R]Cl (R = Me, Et, or Ph; diphos = Ph2P·CH2·CH2·PPh2) have been prepared by the reaction of diphos with [Pt(Et3P)2RCl]. The complexes undergo a thermal reaction leading to [Pt(diphos)RCI] and Et3P (R = Me or Ph); for R = Et, ethylene loss is the main reaction. The complex [Pt(diphos)(GeMe3)Cl] has been prepared similarly from [Pt(diphos)(PEt3)GeMe3]Cl. Metathetical (Nal or NaBPh4) and Pt–C bond cleavage (I2 or HCl) reactions are discussed. Thus iodine and [Pt(diphos)(PEt3)Me]I rapidly give [Pt(diphos)I2] and [Et3PMe]I, whilst HCl and [Pt(diphos)(PEt3)R]Cl (R = Me or Et) give RH and [Pt(diphos)(PEt3)CI]CI only slowly. The n.m.r. spectra of the complexes are discussed.

Mass spectrometry in structural and stereochemical problems CLII. Electron impact promoted fragmentation of some substituted germacyclopentanes and germacyclopentenes

The mass spectra of substituted germacyclopentanes and germacyclopentenes have been measured. Deuterium labeling, supported by low voltage measurements, has enabled plausible mechanistic rationalizations to be presented for the origin of the principal ions in these spectra. The nearly ubiquitous loss of ethylene in germacyclopentanes was found to involve only C-2 and C-3.

A mass spectrometric study of some dialkylphosphinic acids and their alkyl esters

The fragmentation patterns of dialkylphosphinates show predominance of species corresponding to phosphinate molecular ions and phosphacylium ions. A preferred path of fragmentation appears to be alkylP → alkene + HP, with alkyl groups larger than Me. For example, in the spectrum of diethylphosphinic acid, the base peak corresponds to HPO2H+ presumably produced from the initially formed parent ion by loss of Et radical and ethylene. It thus appears possible to predict the modes of fragmentation of alkyl-P(V) compounds enabling mass spectrometry to be of considerable utility in structural analysis. The predominant species and pathways of fragmentation provide some interesting chemistry of energetic species.

Hydrogen rearrangements in some unsaturated ions

Some deuterated hydrocarbons have been prepared and their mass spectra determined. The results indicate that the rearrangements of hydrogen atoms in unsaturated ions are predominantly of the 1–2 type. The loss of ethylene from the parent ion of pent-1-ene does not occur by the mechanism involving a six-membered cyclic transition state as has been suggested. The fragmentations of cyclopentane are shown to occur from the open chain form of the ion rather than from the cyclic form.