HAL Id: jpa-00226249
https://hal.archives-ouvertes.fr/jpa-00226249
Submitted on 1 Jan 1987
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FT-IR SPECTRA OF VACUUM DEPOSITED
CLATHRATE HYDRATES OF OXIRANE, H2S, THF, ETHANE AND CYCLOPROPANE
H. Richardson, P. Wooldridge, J . P . Devlin
To cite this version:
H. Richardson, P. Wooldridge, J . P . Devlin. FT-IR SPECTRA OF VACUUM DEPOSITED CLATHRATE HYDRATES OF OXIRANE, H2S, THF, ETHANE AND CYCLOPROPANE. Journal de Physique Colloques, 1987, 48 (C1), pp.C1-685-C1-685. �10.1051/jphyscol:19871108�. �jpa-00226249�
JOURNAL DE PHYSIQUE
C o l l o q u e C1, s u p p l 6 m e n t a u n o 3 , Tome 48, m a r s 1987
FT-IR SPECTRA OF VACUUM DEPOSITED CLATHRATE HYDRATES OF OXIRANE, H,S, THF, ETHANE AND CYCLOPROPANE
H.H. RICHARDSON, P . J . WOOLDRIDGE a n d J . P . DEVLIN
D e p a r t m e n t of C h e m i s t r y , Oklahoma S t a t e U n i v e r s i t y , S t i l l w a t e r , OK 74078, U.S.A.
Abstract: An a b i l i t y t o prepare c l a t h r a t e hydrates using low temperature-high vacuum techniques, o r i g i n a l l y demonstrated f o r t h e hydrate of oxirane (Bertie and Devlin), has been extended t o include t h e s t r u c t u r e I hydrate of cyclopropane and H2S, mixed s t r u c t u r e I hydrate of oxirane and ethane a s w e l l a s t h e s t r u c t u r e I1 simple hydrate of THF and t h e double hydrates of THF with oxirane and cyclopropane.
The c r y s t a l l i n e c l a t h r a t e f i l m s (- 6 / 0 have been formed e i t h e r by annealing amrphous host-guest d e p o s i t s a t h, 130 K, e p i t a x i a l graklth a t 110 K (oxirane and mixed ethane-oxirane o r d i r e c t deposition a t 150 K (THF and its double c l a t h r a t e s ) .
U s e of t h e e p i t a x i a l approach a t 100 K has permitted the formation of t h e oxirane c l a t h r a t e hydrate containing i n t a c t i s o l a t e d D20 molecules. This has permitted the FT-IR observation of t h e v3-vl doublet i n t h e 0-D s t r e t c h i n g region (2455 cm-I and 2380 c m - l a t 100 K) w i t h t h e v a l u e s , a f t e r c o r r e c t i o n f o r Fermi resonance, sug e s t i n g a s p l i t t i n g from intramolecular co l i n g of -156 cn-l (2455 cm-I us. 2399 cmCm9), which -ares c l o s e l y with t h e 52 cm3 deduced f o r cubic ice. Spectra f o r t h e s t r u c t u r e I hydrates of oxirane and H2S contain adsorption bands produced by g u e s t molecules confined t o both s m a l l and l a r g e c l a t h r a t e cages. U s e of t h e s t r u c t u r e I1 double hydrates has permitted t h e firm i d e n t i f i c a t i o n of t h e s t r u c t u r e I infrared bands with oxirane and H2S molecules i n cages of one s i z e o r t h e other.
Thus, t h e weaker v j and ( v l l , v14) bands of oxirane a t 1281 and 1152 cm-l have been assigned to mlecules i n t h e small cages since only these oxirane f e a t u r e s remain i n t h e s t r u c t u r e I1 double hydrate with THF. I n t h i s c a s e the smaller oxirane molecules occupy t h e small cages while the THF molecules e n t e r the l a r g e r cages, exclusively.
I n a s i m i l a r manner, t h e H-S s t r e t c h i n g v i b r a t i o n s of H2S i n t h e s t r u c t u r e I small cages have been assigned to a band canplex near 2610 m-l, some 50 cm-I above t h e band system f o r H2S i n t h e l a r g e s t r u c t u r e I c l a t h r a t e cages.
Such a result suggests t h a t the n e t H2S perturbation, r e l a t i v e t o the g a s phase, is g r e a t e r for t h e l a r g e than f o r t h e small cages and may be i n t e r p r e t e d a s evidence f o r a "double w e l l " l a r g e cage p o t e n t i a l o r a s f u r t h e r evidence t h a t t h e cage model of Pimentel and Charles f o r guest molecule s t r e t c h i n g modes is valid.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19871108
