Crystal and molecular structure of hexadecamethylcyclooctasiloxane, [(CH3)2SiO]8

doi:10.1139/V83-094

Paper

Crystal and molecular structure of hexadecamethylcyclooctasiloxane, [(CH3)2SiO]8

Published Mar 1, 1983 · N. Paddock, S. Rettig, J. Trotter

Canadian Journal of Chemistry

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5

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0

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Abstract

Crystals of hexadecamethylcyclooctasiloxane are tetragonal, a = 13.9442(5), c = 8.5573(4) A, Z = 2, space group P4/nnc. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.034 and Rw = 0.042 for 730 reflections with I ≥ 3σ(I). The molecular structure closely resembles that of [(CH3)2PN]8. Its comparatively rigid conformation, in which the silicon atoms form a crown, is dependent on the efficient use of van der Waals interactions between two sets of four methyl groups. Important molecular dimensions (bond lengths corrected for libration) are: Si—O = 1.629(1) and 1.635(1), Si—C = 1.862(2) and 1.848(3) A, O—Si—O = 108.99(6), Si—O—Si = 157.8(1) and 148.8(2)°.

Study Snapshot

Key takeawayThe crystal structure of hexadecamethylcyclooctasiloxane, [(CH3)2SiO]8, reveals a rigid conformation with silicon atoms forming a crown, relying on efficient van der Waals interactions between four methyl groups.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Crystal and molecular structure of hexadecamethylcyclooctasiloxane, [(CH3)2SiO]8

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