A. A. Azizov

Intramolecular rearrangements in tris(trimethylsilyl)cyclopentadiene

Abstract Clear-cut temperature dependences of line shapes and line intensities in NMR spectra recorded for tris(trimethylsilyl)cyclopentadiene (I) and for the deuterated analogue (II) demonstrate that metallotropic and prototropic intramolecular rearrangements occur in these compounds. Four possible migration routes for metallotropic rearrangements in compounds I and II have been considered. It has been shown that temperature dependences of PMR and 13 C—{ 1 H} NMR spectra for I and II and a Diels—Alder reaction of I with acetylenedicarboxylic ester may be explained only in terms of four successive 1,2 shifts of the metal. A detailed description of dynamic processes in tris(trimethylsilyl)cyclopentadiene has been made on the basis of total line shape studies carried out for 1 H—{ 2 H} NMR spectra of II under exchange conditions. These spectra avoid complications from spin—coupling effects. The effect of introduction of organometallic groups in the cyclopentadienyl ring on the metallotropic rearrangement is discussed. An attempt is made to extend the concept of relative migratory ability of metals so as to include cyclopentadienyl ligands.

Mass spectra of monohapto-cyclopentadienyl derivatives of group IVB elements

Abstract Dissociative ionisation of organometallic cyclopentadiene derivatives containing one, two or three M(CH 3 ) 3 groups (M  Si, Ge, Sn) has been studied. Among the monometallated compounds, C 5 H 5 Si(CH 3 ) 2 Cl, C 5 H 5 Si(CH 3 ) 2 OCH 3 and (C 5 H 5 ) 4 Sb have also been investigated. To verify fragmentation patterns, the spectra of deuterated compounds such as C 5 D 5 Si(CH 3 ) 3 , C 5 D 5 Sn(CH 3 ) 3 , C 5 D 4 Si 2 (CH 3 ) 6 and C 5 D 3 Si 3 ) 9 have been measured. Dissociative ionisation of h 1 -cyclopentadienyl derivatives has been shown to differ essentially from that of h 5 -compounds.

Mass spectra of ethyldichloro- and trichlorogermylcyclopentadiene

1. A study was made of the dissociative ionization of ethyldichloro- and trichlorogermylcyclopentadiene, and schemes were proposed for their decomposition under electron impact. 2. The studied compounds can be differentiated from compounds of type h5-C5H5MX3 via mass spectrometry.