Organo-Silicon Compounds

Abstract

Infra-red absorption bands arising from linkages involving silicon atoms are about five times more intense than the bands from the corresponding carbon linkages. The reasons for this have been discussed by Wright and Hunter [1]. This fact is of considerable help in analytical work, and infra-red absorption spectra have been very extensively employed in the development and characterisation of organo-silicon polymers and related materials. Many of the basic correlations in this area were identified as a result of the early studies of Wright and Hunter [1], Young, Servais, Currie and Hunter [2], Richards and Thompson [3], and Clark, Gordon, Young and Hunter [4] and their results have been fully confirmed and extended by later workers. The frequencies of bonds involving silicon appear to be largely unaffected by the physical state, except where hydrogen bonding occurs. Simon and McMahon [18] have confirmed this by a comparison of the spectra of some alkyl silanes and siloxanes in the gaseous, liquid and solid phases. The correlations listed have been supported by a considerable number of fundamental studies on single molecules, or related groups, such as silane [6, 7], tetramethyl silane [8, 9], and methyl [19, 23, 24] and halogenated silanes [10, 11, 20, 21, 23]. Frequencies which have been suggested as being characteristic for specific groupings including silicon, are listed in Table 20, and the evidence on which they are based is discussed in the text.