Polymorphism of molecules and complex ions in oxygen compounds of silicon and phosphorus. Communication 4. Phase transitions and conformations of the octamethylcyclotetrasiloxane molecule [OSi(CH3)2]4

  • A. N. Lazarev
  • T. F. Tenisheva
Physical Chemistry


  1. 1.

    The phase transition in crystalline octamethylcyclotetrasiloxane is due to transition of the molecules from Ci to S4 symmetry. During melting, a further change in the structure of the molecule occurs; in the liquid phase it apparently possesses C4 symmetry, which is also preserved in the gas phase.

  2. 2.

    The transformations of the molecule [OSi(CH3)2]4 consist of a change in the conformation of ring and do not lead to any significant change in the bond lengths and valence angles in the ring. A vital role in the mechanism of the molecular rearrangement is played by the lability of the SiOSi angle-thermal excitation of the nonplanar deformational vibrations of the siloxane ring.



Oxygen Silicon Phosphorus Phase Transition Liquid Phase 
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Copyright information

© Consultants Bureau Enterprises, Inc. 1965

Authors and Affiliations

  • A. N. Lazarev
    • 1
  • T. F. Tenisheva
    • 1
  1. 1.I. V. Grebenshchikov Institute of Silicate ChemistryAcademy of Sciences USSRUSSR

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