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In situ uv photolysis of disulphur dichloride in argon and nitrogen matrices: infrared spectroscopic evidence for thiothionyl chloride
Journal of iUokcu&.n-Sticture, 48 (1978) 139-142 @Elsevier Scientific Publishing Compmy, Amsterdam -
Printed in The Netherlands
Short conxmmication
iN SITU UV PHOTOLYSIS OF DISULPHUR DICHLOEIDE IN AEGON ANC, NITR0GEN MATRICZS: INF’RAsRED SPECTROSCOPIC EVIDENCE FOR T~~T~~~ONYL
B. &Z. C~ADWHX,
CH~ORfIDE
J, M. GRZYBOWSKI”
School of Chemisfry, (Gf. Britain)
and I). A. LONG
University of Bradford, Bradford, West Yorkshire BD7 I.GP
(Received 9 November 19’77)
We have investigated the in situ photolysis, with an unfiltered medium pressure mercury arc, of S&l2 in argon (&I/s = 6,030-‘7,000 :I) and also in nitrogen (M/S = 5,000-lO,OOOA) matrices deposited at 12-20 K by pulsing [1,2], Infrared spectra of the photolysed matrices were obtained before and after annealing at variolis temperatures in the range 25-45 K. In argon, the most distinctive feature of the i&ared spectrum of the photolysed matrix is two sharp bands at 697.3 cm-f and 698.7 cm‘-’ which are attributed to the SS stretching modes of a monomeric product m an unstable and stable matrix site respe&uely hased on their intensity behaviour on annealing at 27 K. Two pairs of product bands observed around 400 cm-’ and also around 375 cm-’ exhibit unstable and stable matrix site behatiour together with 35C1,37CFisotopic zphtting. There are two likely identities for the product in argon: either the SSCl radical or the previously unknown molecule SSClz. The Eormer species is known to be produced in sufficient concentration to be detected by ESR spectroscopy by in situ UV photolysis at 4.2 K [3] _ We have investigated the assignment of the observed bands to both species and tested the p~aus~bi~tyof the assignments by normal coordinate calculations with approximate general valence force fields (Tables 1 and 2). The observed wavenumbers can only be fitted to the three uon-d~genera~ fundamentals of bent 32S32S35G2 and 32S3ZS37Cf with an ~a~cep~bly high bending force constant whether one, two or three interaction constants are employed; in addition, the quahty of fit of the isotopic data is poorer than for the analogous radicals, OOF 143, OOCl [5] and r*r’SCIf6] (Table I). On the other hand, the observed bands can be fitted to the three nondegenerate stretching fundamentals of pyramidal 32S32S35Cl, and 32S3aS35C1”7C1 --.... with plausible values of the principal force constants and no off-diagonal 5nteractionconstants (Table 2). The assumption r’(SCl),,, > G(SCl)antisym is based on the analogous fluoride, SSF, [?]. The non-observation of SCZ *Present address: Nationat Research CounciI of Canada, Ottawa, Ontario, Canada KlA
OR&
IS~3193SC]
1327.3 1327.3
1327.3 403.75 403.7 267.4 267.4 1327.3 400.5 400,7 265.0 265,2
I
,,,>
*Assumed wavenumbers for these species.
INJ’S37Cl
372
1441.9 407
1440.8
16~16()3lC~
373
1500.9 537,2 586,8 377.2 376,6
1502.1
l6()16()‘9F
406
699.2 4Q3,1a 406.4 377.1a 377.2 698.5 401.4a 398,7 376.0a 375.4
32,fj32S37C]
3zppsc1
698,7p 698.7a
Calc.
10.095
9.664
10.47
4.01
1.380
1.290
1.426
2.22
Obs.
Ohs,
Calc. Ohs.
(mdyn 8-,l
(mdyn a -,)
Cafe.
FBX
J’AB
u(BX) (cm-‘) 6 (ABX) (cm-‘)
u(AB) (cm-’ )
Normal coordinate analyses for ABX radicals (X = halogen)
TABLE 1
0.852
1.038
0.941
3,25
(mdyn a radez)
hii,x
-0.080
0.545
0.045
1.30
(mdyn rad-’ )
FBX-A fiX
0.105
0.70
-
-
A” )
(mdyn
FAX-BX
0.0087
-
-
-
(mdyn rad”)
I61
[51
r41
FAX__AGX Ref,
CI %
TABLE
2
Vibrational assignments (cm-’ ) for ClSSCl and its UV photolysis products in arg& and nitrogen matrices Species
ClSSCl
SSCl,
ssc1:
Vapour Ar matrix [ll, 131 (unstable site )
Ar matrix (stable site)
546
697.3
698.7
698.6b
I 466
402.1 400.4
403.1 401.4
403.2 401.2
ewsym lJ(scl);$-~ u(scl):q~
sxi,
v(SCl)$~
C
373.7 371.7 c
C
377.1 375.0 C’
SSCl,
SSCl,
N, matrix (unstable site)
N, matrix N, matrix (stable site)
694.8
696.0
1 398
1 403
I I 375
378
E&Cl(?) or s,---Cl,(?)
699.0
399.1 377.0 375.4 373.7
for FSS = 4.38 mdyn A-‘, FSCI= 1.35 mdyn A-‘, F&c, = 1.00 mdyn ii rad-‘, 0.80 mdyn iI_radm2and Fscl_scl E 0.24 mdyn A-’ assuming r(SS) = 1.90 a, r(SC1) = 2.04 JI, a(CISC1) = 100” and a(SSCl) = 108”. bIrrespective of Cl isotopes. =Not observed_ %
C&Z.
Fs&
VdUeS
=
stretching vibrations due to 32S32S37Cl,and SS stretching vibrations due to 34S’2S35C1,is hardly surprising as the corresponding vibrations are not convincingly observed in the isomeric parent molecule, ClSSCl [S]. It appears, then, that in UV photolyzed Ar/ClSSCl matrices IR spectroscopy detects the major diamagnetic product and ESR spectroscopy a minor paramagnetic product just as in the Ar/ICN system where INC and CN are detected respectively [ 9, lo] . The SS stretching waven-umbersfor the proposed SSCl, are ca. 150 cm-’ higher than for the corresponding vibrations in the gaseous [ ll] or matrixisolated [8,12] parent isomer, ClSSCl; the wavenumber shift in the analogous fluorides [II] is apparently either ca. 100 cm-’ or ca. 150 cm-‘. The SC1 stretching wavenumbers are about 70 cm-’ lower than in the gaseous [ll, 133 or matrix-isolated [S, 123 parent isomer, CISSCI, in contrast to the analogous fluorides [7]. The
spectra
of the photolyzed
N,/ClSSCl
matrices
differ
from
those
of
Ar/ClSSCl in three respects I they indicate a substantially lower concentration of SSCl,; no isotopic splitting of the SC1 stretching modes is observed ; and ir, the SS stretching region a third sharp band is found at 699.0 cm-‘. The photolytic product responsible for this extra band cannot be deduced with any confideme. The baud could be the SS stretching vibration of &Cl with more Cl atoms leaving the N, matrix cage than the Ar matrix cage. Alternatively, it could be the SS stretching vibration of an S2 radical perturbed by an adjacent Cl* molecule; the SS stretching vibration of the S2 radical isolated in an argon matrix has been assigned [ 141 at 716 cm-’ from the Raman spectrum.
ACKNOWLEDGEMENTS We are grateful to the Leverhulme Trust for the award of a Commonwealth/ American Visiting Fellowship to one of us (J. M. G.) and to Mr. D. A. M. Marcus-Hanks for computing assistance. REFERENCES 1 M. M. Rochkind, Spectrochim. Acta Part A, 27 (1971) 547. 2 R. N. Perutz and J_ J. Turner, J. Chem. Sot. Faraday Trans. 2,69 (1973) 452. 3 F. G. Herring, C_ A. A&Dowel! and J. C. Tait, J. Chem. Phys., 57 (1972) 4564. 4 R. D. Spratley, J. J. Turner and G. C. Pimentel, J. Chem. Phys., 44 (1966) 2063. 5 A. ArkelI and I_ Schwager, J. Am. Chem. Sot., 89 (1967) 5999. 6 S. C. Peake and A. J. Downs, J. Chem. Sot. Dalton Trans., (1974) 859. 7 R. D. Brown and G. P. Pez, Spectrochim. Acta Part A, 26 (1970) 1375. 8 B. M. Chadwick, J. M. Grzybowski and D. A. Long, unpublished results. 9 B. R. Carr, B. M. Chadwick, D. G. CobboId and D. A. Long, uxrpublished results. 197. 10 W. C. Easley and W. Welner, Jun., J. Chem. Phys., 52 (1970) 11 S. G. Frankiss, J. MoI. Struct., 2 (1968) 271. 12 P. N. NobIe and L. Mei, J. Chem. Phys., 61 (1974) 541. 13 S. G. Frankiss and D. S. Harrison, Spectrochim. Acta Part A, 31 (1975) 161. 14 R. E. Barletta, H. H. CIaasen and R. L. McBeth, J. Chem. Phys., 55 (1971) 5409.
Printed in The Netherlands
Short conxmmication
iN SITU UV PHOTOLYSIS OF DISULPHUR DICHLOEIDE IN AEGON ANC, NITR0GEN MATRICZS: INF’RAsRED SPECTROSCOPIC EVIDENCE FOR T~~T~~~ONYL
B. &Z. C~ADWHX,
CH~ORfIDE
J, M. GRZYBOWSKI”
School of Chemisfry, (Gf. Britain)
and I). A. LONG
University of Bradford, Bradford, West Yorkshire BD7 I.GP
(Received 9 November 19’77)
We have investigated the in situ photolysis, with an unfiltered medium pressure mercury arc, of S&l2 in argon (&I/s = 6,030-‘7,000 :I) and also in nitrogen (M/S = 5,000-lO,OOOA) matrices deposited at 12-20 K by pulsing [1,2], Infrared spectra of the photolysed matrices were obtained before and after annealing at variolis temperatures in the range 25-45 K. In argon, the most distinctive feature of the i&ared spectrum of the photolysed matrix is two sharp bands at 697.3 cm-f and 698.7 cm‘-’ which are attributed to the SS stretching modes of a monomeric product m an unstable and stable matrix site respe&uely hased on their intensity behaviour on annealing at 27 K. Two pairs of product bands observed around 400 cm-’ and also around 375 cm-’ exhibit unstable and stable matrix site behatiour together with 35C1,37CFisotopic zphtting. There are two likely identities for the product in argon: either the SSCl radical or the previously unknown molecule SSClz. The Eormer species is known to be produced in sufficient concentration to be detected by ESR spectroscopy by in situ UV photolysis at 4.2 K [3] _ We have investigated the assignment of the observed bands to both species and tested the p~aus~bi~tyof the assignments by normal coordinate calculations with approximate general valence force fields (Tables 1 and 2). The observed wavenumbers can only be fitted to the three uon-d~genera~ fundamentals of bent 32S32S35G2 and 32S3ZS37Cf with an ~a~cep~bly high bending force constant whether one, two or three interaction constants are employed; in addition, the quahty of fit of the isotopic data is poorer than for the analogous radicals, OOF 143, OOCl [5] and r*r’SCIf6] (Table I). On the other hand, the observed bands can be fitted to the three nondegenerate stretching fundamentals of pyramidal 32S32S35Cl, and 32S3aS35C1”7C1 --.... with plausible values of the principal force constants and no off-diagonal 5nteractionconstants (Table 2). The assumption r’(SCl),,, > G(SCl)antisym is based on the analogous fluoride, SSF, [?]. The non-observation of SCZ *Present address: Nationat Research CounciI of Canada, Ottawa, Ontario, Canada KlA
OR&
IS~3193SC]
1327.3 1327.3
1327.3 403.75 403.7 267.4 267.4 1327.3 400.5 400,7 265.0 265,2
I
,,,>
*Assumed wavenumbers for these species.
INJ’S37Cl
372
1441.9 407
1440.8
16~16()3lC~
373
1500.9 537,2 586,8 377.2 376,6
1502.1
l6()16()‘9F
406
699.2 4Q3,1a 406.4 377.1a 377.2 698.5 401.4a 398,7 376.0a 375.4
32,fj32S37C]
3zppsc1
698,7p 698.7a
Calc.
10.095
9.664
10.47
4.01
1.380
1.290
1.426
2.22
Obs.
Ohs,
Calc. Ohs.
(mdyn 8-,l
(mdyn a -,)
Cafe.
FBX
J’AB
u(BX) (cm-‘) 6 (ABX) (cm-‘)
u(AB) (cm-’ )
Normal coordinate analyses for ABX radicals (X = halogen)
TABLE 1
0.852
1.038
0.941
3,25
(mdyn a radez)
hii,x
-0.080
0.545
0.045
1.30
(mdyn rad-’ )
FBX-A fiX
0.105
0.70
-
-
A” )
(mdyn
FAX-BX
0.0087
-
-
-
(mdyn rad”)
I61
[51
r41
FAX__AGX Ref,
CI %
TABLE
2
Vibrational assignments (cm-’ ) for ClSSCl and its UV photolysis products in arg& and nitrogen matrices Species
ClSSCl
SSCl,
ssc1:
Vapour Ar matrix [ll, 131 (unstable site )
Ar matrix (stable site)
546
697.3
698.7
698.6b
I 466
402.1 400.4
403.1 401.4
403.2 401.2
ewsym lJ(scl);$-~ u(scl):q~
sxi,
v(SCl)$~
C
373.7 371.7 c
C
377.1 375.0 C’
SSCl,
SSCl,
N, matrix (unstable site)
N, matrix N, matrix (stable site)
694.8
696.0
1 398
1 403
I I 375
378
E&Cl(?) or s,---Cl,(?)
699.0
399.1 377.0 375.4 373.7
for FSS = 4.38 mdyn A-‘, FSCI= 1.35 mdyn A-‘, F&c, = 1.00 mdyn ii rad-‘, 0.80 mdyn iI_radm2and Fscl_scl E 0.24 mdyn A-’ assuming r(SS) = 1.90 a, r(SC1) = 2.04 JI, a(CISC1) = 100” and a(SSCl) = 108”. bIrrespective of Cl isotopes. =Not observed_ %
C&Z.
Fs&
VdUeS
=
stretching vibrations due to 32S32S37Cl,and SS stretching vibrations due to 34S’2S35C1,is hardly surprising as the corresponding vibrations are not convincingly observed in the isomeric parent molecule, ClSSCl [S]. It appears, then, that in UV photolyzed Ar/ClSSCl matrices IR spectroscopy detects the major diamagnetic product and ESR spectroscopy a minor paramagnetic product just as in the Ar/ICN system where INC and CN are detected respectively [ 9, lo] . The SS stretching waven-umbersfor the proposed SSCl, are ca. 150 cm-’ higher than for the corresponding vibrations in the gaseous [ ll] or matrixisolated [8,12] parent isomer, ClSSCl; the wavenumber shift in the analogous fluorides [II] is apparently either ca. 100 cm-’ or ca. 150 cm-‘. The SC1 stretching wavenumbers are about 70 cm-’ lower than in the gaseous [ll, 133 or matrix-isolated [S, 123 parent isomer, CISSCI, in contrast to the analogous fluorides [7]. The
spectra
of the photolyzed
N,/ClSSCl
matrices
differ
from
those
of
Ar/ClSSCl in three respects I they indicate a substantially lower concentration of SSCl,; no isotopic splitting of the SC1 stretching modes is observed ; and ir, the SS stretching region a third sharp band is found at 699.0 cm-‘. The photolytic product responsible for this extra band cannot be deduced with any confideme. The baud could be the SS stretching vibration of &Cl with more Cl atoms leaving the N, matrix cage than the Ar matrix cage. Alternatively, it could be the SS stretching vibration of an S2 radical perturbed by an adjacent Cl* molecule; the SS stretching vibration of the S2 radical isolated in an argon matrix has been assigned [ 141 at 716 cm-’ from the Raman spectrum.
ACKNOWLEDGEMENTS We are grateful to the Leverhulme Trust for the award of a Commonwealth/ American Visiting Fellowship to one of us (J. M. G.) and to Mr. D. A. M. Marcus-Hanks for computing assistance. REFERENCES 1 M. M. Rochkind, Spectrochim. Acta Part A, 27 (1971) 547. 2 R. N. Perutz and J_ J. Turner, J. Chem. Sot. Faraday Trans. 2,69 (1973) 452. 3 F. G. Herring, C_ A. A&Dowel! and J. C. Tait, J. Chem. Phys., 57 (1972) 4564. 4 R. D. Spratley, J. J. Turner and G. C. Pimentel, J. Chem. Phys., 44 (1966) 2063. 5 A. ArkelI and I_ Schwager, J. Am. Chem. Sot., 89 (1967) 5999. 6 S. C. Peake and A. J. Downs, J. Chem. Sot. Dalton Trans., (1974) 859. 7 R. D. Brown and G. P. Pez, Spectrochim. Acta Part A, 26 (1970) 1375. 8 B. M. Chadwick, J. M. Grzybowski and D. A. Long, unpublished results. 9 B. R. Carr, B. M. Chadwick, D. G. CobboId and D. A. Long, uxrpublished results. 197. 10 W. C. Easley and W. Welner, Jun., J. Chem. Phys., 52 (1970) 11 S. G. Frankiss, J. MoI. Struct., 2 (1968) 271. 12 P. N. NobIe and L. Mei, J. Chem. Phys., 61 (1974) 541. 13 S. G. Frankiss and D. S. Harrison, Spectrochim. Acta Part A, 31 (1975) 161. 14 R. E. Barletta, H. H. CIaasen and R. L. McBeth, J. Chem. Phys., 55 (1971) 5409.