Spectroscopic Study of π-Acceptor Effects in Compounds of Silicon Subgroup Elements

The general state of research into the π-acceptor properties of silicon subgroup elements (E) by spectroscopic methods is examined and the data obtained are surveyed. It is shown that the π-acceptor properties are weakened with increase of the atomic number of the element E, and the analogy between these properties and the conjugation effect in unsaturated carbon compounds is traced. The widespread interpretation of π-acceptor properties of these elements as a manifestation of the effect of the d_π–p_π interaction is justified.
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