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
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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.
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.
KeywordsOxygen Silicon Phosphorus Phase Transition Liquid Phase
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- 1.A. N. Lazarev, Izv. AN SSSR. Ser. Khim.,1964, 235.Google Scholar
- 2.A. N. Lazarev and T. F. Tenisheva, Izv. AN SSSR. Ser. Khim.,1964, 242.Google Scholar
- 3.A. N. Lazarev and T. F. Tenisheva, Izv. AN SSSR. Ser. Khim.,1964, 403.Google Scholar
- 4.E. G. Rochow and H. G. Clair, J. Inorgan. Nucl. Chem.,1, 92 (1955).Google Scholar
- 5.J. D. Hoffman, J. Amer. Chem. Soc.75, 6361 (1935).Google Scholar
- 6.H. Steinfink, B. Post and I. Fankuchen, Acta crystallogr,8, 420 (1955).Google Scholar
- 7.H. Kriegsmann, Z. anorgan. und allgem. chem.,298, 232 (1959).Google Scholar
- 8.G. Herzberg, Vibrational and Rotational Spectra of Polyatomic Molecules [Russian translation], Foreign Literature Press, Moscow (1949).Google Scholar
- 9.A. S. Mayants, Theory and Calculation of Molecular Vibrations [in Russian], Academy of Sciences USSR Press, Moscow (1960).Google Scholar
- 10.J. R. Aronson, R. C. Lord and D. W. Robinson, J. Chem. Phys.,33, 1004 (1960).Google Scholar
- 11.W. R. Thorson and I. Nadagawa, J. Chem. Phys.33, 994 (1960).Google Scholar