= Solution
\b[Successive Si–O links have the same local bonding role], unlike the unequal links selected by an alternating <phosphazene> <conformation>. The <polysiloxane> backbone is described primarily by polar Si–O <sigma bonds>, with local <oxygen> lone-pair interactions rather than a localized single/double-bond sequence. There is therefore no alternating Si–O bond-order pattern that requires two characteristic distances. Equal chemical environments give equal bond lengths in the ideal repeating structure; local strain or packing can perturb individual distances.
Back to article page
