G O G G I N et al. 3 have studied the infrared and R A M A N
spectra of the SOF4 molecule. Of the three models
suggested for the structure of this molecule, they have
concluded that the structure is derived from a trigonal
bipyramidal arrangement similar to that of SF4 with
the oxygen atom in the equatorial position and the
point group C%v. It has twelve fundamental frequencies
falling under four species. The normal coordinate treatment has been carried out and the potential constants
have been evaluated using W I L S O N ' S F — G matrix method by R A D H A K R I S H N A N .
Thermodynamic Properties of SF4 and SOF4
By
M.
RADHAKRISHNAN
Department of Physics, Annamalai University,
Annamalainagar, South India
( Z . Naturforschg. 18 a, 103—104 [1963] ; eingeg. am 10. September 1962)
The R A M A N and infrared spectra of SF4 molecule
have been investigated by D O D D et al. 1. They have concluded that this molecule belongs to the point group
C2V having nine fundamental frequencies falling under
four species. The potential constants of this molecule
have been calculated by V E N K A T E S W A R L U and P I L L A I
by the W I L S O N ' S group theoretical considerations.
4
Molecular
parameters
2
Molecular
parameters
Principal
moments of
inertia amu A 2
S - F = 1.58 Ä
^FI-S-F4 =
F i - S - F 2 = 90°
Ixx=
78.1901
Iyy = 142.3021
Izz = 125.6228
Type
S—Fx = S—F3
= 1.56 A
<F3-S-F4
=
^F3-S-0
= 120°
<Fx-S-0
—
Fi—S-F4
= 90°
Observed
frequencies
889 c m - 1
235
557
715
645
532
867
463
728
AI
A2
BI
B2
_
100° K
200
273.16
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
EDIT
8.2139
9.5186
10.8611
11.3732
13.1504
14.8010
16.0342
16.9356
17.7776
18.4862
19.0810
19.5849
20.0203
20.4146
20.7546
21.0561
-
(F0
Type
Observed
frequencies
Ixx =
124.8238
Iyy =
147.9430
741
=
161.8344
589
309
189
933
643
555
933
479
272
Izz
Ai
1367 c m " 1
797
A 2
B2
Table 2. Molecular parameters, principal moments of inertia
and the observed frequencies of S O F 4 .
Table 1. Molecular parameters, principal moments of inertia
and the observed frequencies of SF 4 .
Temp.
Principal
moments o f
inertia amu Ä 2
-
S°
EDIT
47.6541
53.6946
56.8530
57.9001
61.4179
64.6483
67.4328
69.8466
72.1598
74.2993
76.2786
78.0917
79.8278
81.4643
82.9994
84.4326
55.8679
63.2130
67.7141
69.2733
74.5683
79.4493
83.4670
86.7822
89.9374
92.7855
95.3596
97.6766
99.8481
101.8789
103.7540
105.4887
9.0175
12.9439
16.0352
17.0159
19.7803
21.6528
22.7621
23.4141
23.9321
24.3053
24.5784
24.7864
24.8987
25.0738
25.1765
25.2594
Table 3. Heat content, free energy, entropy and heat capacity for SF 4 molecule for the ideal gaseous state at one atmospheric
pressure.
The valuss are in cal. d e g . - 1 m o l e - 1 and £ „ ' is the energy of one mole of perfect gas at absolute zero temperature.
1
R . E . DODD, L . A . WOODWARD
2
day Soc. 52, 1052 [1956].
K . VENKATESWARLU and K .
11, 26 [1961].
and
PILLAI,
Trans. Fara-
3
Optics and Spectroscopy
4
H . L . ROBERTS,
H . L . ROBERTS and L . A . WOODWARD,
Faraday Soc. 57, 1877 [1961].
M. RADHAKRISHNAN, J . Mol. Spectroscopy, in press.
P . L . GOGGIN,
Trans,
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Temp.
100°K
200
273.16
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
- E°0)/T
8.6152
10.7658
12.7857
13.1548
15.3264
17.1753
18.7139
19.9764
21.0533
21.9543
22.7066
23.3763
23.9425
24.4743
24.9271
25.2884
-
-
S°
EDIT
57.5639
66.3114
72.3127
73.5177
79.7789
85.2640
90.0829
94.2849
98.1227
101.5628
104.6422
107.5006
110.1018
112.6662
114.9792
116.9840
48.9487
55.5456
59.5270
60.3629
64.4525
68.0888
71.3690
74.3085
77.0694
79.6085
81.9356
84.1243
86.1593
88.1914
90.0521
91.6956
10.3549
15.5303
19.1679
20.1112
23.3785
25.5849
27.0862
28.1263
28.8749
29.4204
29.8236
30.1439
30.3868
30.5918
30.7536
30.8718
Table 4. Heat content, free energy, entropy and heat capacity for SOF4 molecule for the ideal gaseous state at one atmospheric
pressure.
The values are in cal. d e g . - 1 m o l e - 1 and E„* is the energy of one mole of perfect gas at absolute temperature.
In the present investigation the thermodynamic properties such as heat content, free energy, entropy and
heat capacity, of these molecules have been calculated
using the fundamental frequencies reported by the earlier authors. The calculation is for the ideal gas at one
atmospheric pressure assuming a rigid-rotator harmonic
oscillator model. The influence of nuclear spin and
anharmonicity has been omitted. The molecular parameters, observed frequencies and calculated principal
moments of inertia are given in Tables 1 and 2. The
symmetry number used for this calculation for both
molecules is 2. The values obtained for the thermodynamic properties of SF 4 and SOF 4 molecules are
presented in Tables 3 and 4.
The author wishes to express his grateful thanks to
Dr.
K.
VENKATESWARLU
for
the
encouragement
and
to
the Ministry of Education, Government of India for the
award of a Senior Research Scholarship.
Nachdruck — auch auszugsweise — nur mit schriftlicher Genehmigung des Verlags gestattet
Verantwortlich für den Inhalt: A . KLEMM
Gesamtherstellung: Konrad Triltsch, Würzburg
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Unauthenticated
Download Date | 6/18/17 7:03 PM