Spectroscopy disilenes, stable

In 1981, West et al. synthesized the first stable disilene 1 via the dimerization of the corresponding silylene generated by the photolysis of a trisilane and characterized the structure by conventional spectroscopies [Eq. (2)].5 Availability of 1 and other stable disilenes has stimulated theoretical and experimental studies of various aspects of disilenes such as their bonding and structure, spectroscopic properties, reactivities, applications to the synthesis of novel types of organosilicon compounds, etc. 

The reaction between K2Fe(CO)4 and a tetrachlorotetrasilane resulted in the formation of an iron complex with a disilene ligand (Equation (33)). Both the (E)- and (Z)-isomers were formed. The reaction, when monitored by H NMR spectroscopy, indicated the initial formation of the (Z)-isomer with isomerization to the more stable ( )-isomer over time. Kinetic studies were also performed, and suggested that the ( )-isomer is >3kcalmol more stable than the (Z)-isomer. Theoretical calculations for similar molecules with varying R groups indicated that the stability of the molecule is dependent on the bulkiness of the R group. 

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