Gas-phase generation and electronic structure investigation of chlorosulfanyl thiocyanate, ClSSCN

Article abstract of DOI:10.1021/ic060513s

The chlorosulfanyl thiocyanate molecule, ClSSCN, was generated in the gas phase through heterogeneous reaction of SCl₂ on the surface of finely powdered AgSCN for the first time. The reaction products were detected and characterized in situ by ultraviolet photoelectron and photoionization mass spectrometry. The molecular geometry and electronic structures of ClSSCN were investigated by a combination of PES experiment and theoretical calculations with the density functional theory and ab initio methods. It was found that the outermost electrons of ClSSCN reside in the Cl-S antibonding π orbital, predominantly localized on the sulfur atom, and the experimental first vertical ionization potential of ClSSCN is 10.20 eV. The dominant fragment SSCN ⁺ in the mass spectrum indicates that the ClSSCN cation prefers the dissociation of the Cl-S bond.

Full text of DOI:10.1021/ic060513s

Inorg. Chem. 2006, 45, 5971−5975
Gas-Phase Generation and Electronic Structure Investigation of
Chlorosulfanyl Thiocyanate, ClSSCN
Li Yao,†,‡ Maofa Ge,*,† Weigang Wang,†,‡ Xiaoqing Zeng,†,‡ Zheng Sun,† and Dianxun Wang†
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese
Academy of Sciences, Beijing, 100080, China, and Graduate UniVersity of Chinese Academy of
Sciences, Beijing, 100039, China
Received March 27, 2006
The chlorosulfanyl thiocyanate molecule, ClSSCN, was generated in the gas phase through heterogeneous reaction
of SCl2 on the surface of finely powdered AgSCN for the first time. The reaction products were detected and
characterized in situ by ultraviolet photoelectron and photoionization mass spectrometry. The molecular geometry
and electronic structures of ClSSCN were investigated by a combination of PES experiment and theoretical calculations
with the density functional theory and ab initio methods. It was found that the outermost electrons of ClSSCN
reside in the Cl
−S antibonding π orbital, predominantly localized on the sulfur atom, and the experimental first
vertical ionization potential of ClSSCN is 10.20 eV. The dominant fragment SSCN+ in the mass spectrum indicates
that the ClSSCN cation prefers the dissociation of the Cl
−S bond.
1. Introduction
S-S bond, NCSSCN, was synthesized by So¨derba¨ck in
1918.5 Various polysulfides NCSnCN (n < 9) have been
studied by Raman spectroscopy.6 Thiazyl thiocyanide NS-
SCN was generated by an on-line process using NSCl passed
over heated AgSCN and studied by gas-phase FTIR spec-
troscopy.7
We have a long-standing interest in the generation,
spectroscopy, and electronic structure of small stable and
unstable species. In this work, we present the generation of
chlorosulfanyl thiocyanate ClSSCN and its subsequent detec-
tion and characterization by ultraviolet photoelectron and
photoionization mass spectrometry with the help of density
functional theory (DFT) and ab initio calculations. The joint
spectroscopic and theoretical study provided useful informa-
tion about the molecular structures, stability, ionization,
reaction, and dissociation properties of the interesting
unstable ClSSCN molecule.
The sulfur-sulfur bond is a structural feature of wide-
spread occurrence in both organic and inorganic sulfur
chemistry. Because of the frequency of disulfide bridges in
the structure of many proteins, enzymes, and antibiotics, it
plays an important role in stabilizing the structure and in
determining the biological activity of the molecules.1-3
Recently, considerable attention has been paid to the structure
and conformational preferences of simple disulfides. Geo-
metric gas-phase structures of noncyclic disulfides XSSX
are characterized by a gauche conformation around the S-S
bond. Structural studies of nonsymmetrically substituted
disulfides of the type XSSY are less common. Recently,
experimental studies on the structure of FC(O)SSCF3, FC-
(O)SSCH3, and FC(O)SSC(O)CF3 have been performed in
the gas phase.4
Thiocyanates with a SCN group attached directly to sulfur,
XSSCN, which possess a sulfur-sulfur bond, have long been
known. The first unstable thiocyanate containing a single
2. Experimental Section
2.1. Generation. Silver thiocyanate was found to be an ideal
precursor for the preparation of thiocyanates.8,9 In this work,
* To whom correspondence should be addressed. Phone: 86-10-
62554518. Fax: 86-10-62559373. E-mail: gemaofa@iccas.ac.cn.
† Beijing National Laboratory for Molecular Sciences, Chinese Academy
of Sciences.
(4) (a) Hermann, A.; Ulic, S. E.; Della Ve´dova, C. O.; Mack, H.-G.;
Oberhammer, H. J. Fluorine Chem. 2001, 112, 297-305. (b) Fantoni,
A. C.; Della Ve´dova, C. O. J. Mol. Spectrosc. 1992, 154, 240-245.
(c) Erben, M. F.; Della Ve´dova, C. O.; Willner, H.; Trautner, F.;
Oberhammer, H.; Boese, R. Inorg. Chem. 2005, 44, 7070-7077.
(5) So¨derba¨ck, E. Liebigs Ann. Chem. 1919, 419, 217-223.
(6) Fehe´r, F.; Weber, H. Chem. Ber. 1958, 91, 642-650.
(7) Ajji, Z.; Naima, D. Y.; Odeh, M. N.; Allaf, A. W. Spectrochim. Acta,
Part A 1999, 55, 1753-1756.
‡ Graduate University of Chinese Academy of Sciences.
(1) Wedemeyer, W. J.; Welker, E.; Narayan, M.; Scheraga, H. A.
Biochemistry 2000, 39, 4207-4216.
(2) Kadokura, H.; Katzen, F.; Beckwith, J. Annu. ReV. Biochem. 2003,
72, 111-135.
(3) Rietsch, A.; Beckwith, J. Annu. ReV. Genet. 1998, 32, 163-184.
10.1021/ic060513s CCC: $33.50
Published on Web 06/24/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 15, 2006 5971

Yao et al.
Table 1. Total Molecular Energy (au) and Geometric Constants (Å,
deg) for the Equilibrium Structure of ClSSCN at Different Theoretical
Levels
ClSSCN was generated by passing SCl2 vapor over finely powdered
AgSCN at 40 °C, and in situ photoelectron and mass spectra were
recorded. The precursor SCl2 was prepared according to a previous
report,10 and its PE spectrum is identical to that recorded previ-
ously.11 AgSCN was purchased from the ACROS Company, and
its purity was better than 99%. Before reaction, silver thiocyanate
was dried in a vacuum (1 × 10-4 Torr) for 2 h at 60 °C.
B3LYP/
6-311+G*
B3LYP/
6-311+G(3df)
MP2/
6-311+G*
MP2/
6-311+G(3df)
E
-1349.498367 -1349.536166 -1347.560489 -1347.777085
Cl-S
2.102
2.080
1.709
1.158
106.2
103.1
175.7
2.062
2.039
1.702
1.155
106.4
103.9
176.5
86.92
178.8
2.064
2.056
1.701
1.181
104.7
101.0
175.2
85.05
176.3
2.030
2.018
1.697
1.176
104.9
102.1
177.2
84.60
172.7
S-S
S-C
2.2. Instrumentation. The experimental apparatus used in this
work has been described previously.12,13 Briefly, the photoelectron
and photoionization mass spectrometer consists of two parts; one
part is the double-chamber UPS-II machine,14 the other is a time-
of-flight mass spectrometer. The photoelectron (PE) spectrum was
recorded on the double-chamber UPS-II machine14 which was built
specifically to detect transient species at a resolution of about 30
meV as indicated by the Ar+(2P3/2) photoelectron band. Experi-
mental vertical ionization energies are calibrated by the simulta-
neous addition of a small amount of argon and methyl iodide to
the sample. Mass analysis of ions is achieved with the time-of-
flight mass analyzer mounted directly to the photoionization point.
The relatively soft ionization is provided by single-wavelength HeI
radiation. The PE and PIMS spectra can be recorded within seconds
of each other under identical conditions.
C-N
Cl-S-S
S-S-C
S-C-N
Cl-S-S-C 87.37
S-S-C-N 179.7
3. Results and Discussion
3.1. Molecular Structure. Geometry optimizations were
performed for ClSSCN using the DFT and ab initio methods.
2.3. Computation. Electronic structure calculations were carried
out using the Gaussian series of programs.15 The geometries of the
ClSSCN molecule were optimized with B3LYP and MP2 methods
at the 6-311+G* and 6-311+G(3df) basis set levels. To assign the
PE spectrum of ClSSCN molecule, we applied the outer-valence
Green’s function (OVGF) calculations with a 6-311+G* basis set,
which include sophisticated correlation effects of the self-energy,
to the molecules to give accurate results of the vertical ionization
energies.16 The adiabatic ionization energy was calculated by taking
the difference between the energy of the neutral molecule and the
ion at the CBS-QB3 level of theory.17 Three-dimensional MO plots
were obtained with the GaussView program. Each orbital displayed
with the 0.08 isodensity value was oriented in a way that allowed
for the best view.
The structural parameters are depicted in Table 1 (for
further geometric constraints, see the Supporting Informa-
tion). It is well-known that the B3LYP method and the MP2
approximation with small or intermediate basis sets predict
S-S, S-Cl, S-F, S-O, etc., bonds longer than they actually
are. As demonstrated in test calculations for S2Cl2, the values
derived with the MP2 method using a large basis set are
expected to be close to the experimental values. Comparing
the predicted Cl-S bond with the experimentally determined
bond length of some similar molecules, we can see that the
predicted Cl-S bond length of ClSSCN is close to that of
the SCl2 (2.015 ( 0.002 Å) and S2Cl2 (2.057 ( 0.002
Å) molecules. In several molecules containing triatomic
pseudohalide groups, e.g., SCN, NCO, NNN, etc., it has been
established that the atoms are not collinear.20,21 When
combining with ClS, the SCN angle shows about 5° deviation
from linearity, which is similar to those of XSCN (X ) CN,22
SCN,8 Cl23). The calculated S-C and C-N bond lengths
are also close to the previous reported values. Particularly
important parameters are the S-S bond length and Cl-S-
S-C dihedral angle as the joint between the ClS and SCN
moieties. Comparison of the S-S bond length in S2X2 (X
) Cl,24 H,25 CSN326) shows that the S-S bond in ClSSCN
is a typical SII-SII bond (2.04-2.06 Å). The dihedral angle
Cl-S-S-C that determines the molecular symmetry is in
18
19
(8) Frost, D. C.; Kirby, C.; Lau, W. M.; MacDonald, C. B.; McDowell,
C. A.; Westwood, N. P. C. Chem. Phys. Lett. 1980, 69, 1-5.
(9) Yimin, L.; Zhimin, Q.; Qiao, S.; Jincai, Z.; Haiyang, L.; Dianxun, W.
Inorg. Chem. 2003, 42, 8446-8448.
(10) Brauer, G., Eds.; Handbook of PreparatiVe Inorganic Chemistry, 2nd
ed.; Academic Press: New York, 1963; pp 186-187.
(11) Solouki, B.; Rosmus, P.; Bock, H. Chem. Phys. Lett. 1974, 26, 20-
24.
(12) Yao, L.; Zeng, X. Q.; Ge, M. F.; Wang, W. G.; Sun, Z.; Du, L.; Wang,
D. X. Eur. J. Inorg. Chem. 2006, 12, 2469-2475.
(13) Yao, L.; Wang, W. G.; Zeng, X. Q.; Ge, M. F.; Du, L.; Sun, Z.; Wang,
D. X.; Liang, F.; Qu, H. B.; Li, H. Y. Anal. Instrum. 2006, 1, 5-9.
(14) Zhu, X. J.; Ge, M. F.; Wang, J.; Sun, Z.; Wang, D. X.; Angew. Chem.,
Int. Ed. 2000, 112, 2016-2019.
(15) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T.; Kudin, K.
N.; Burant, J. C.; Millam, J. M.; Iyengar, S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa,
J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene,
M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A.
J.; Cammi, R.; Pomelli, C.; Ochterski, J.; Ayala, P. Y.; Morokuma,
K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.;
Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O¨ .; Malick, D.
K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.;
Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.;
Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox,
D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M.
W.; Andres, J. L.; Gonzalez, C.; Replogle, E. S.; Pople, J. A. Gaussian
03, revision B.04; Gaussian, Inc.: Pittsburgh, PA, 2003.
(17) Montgomery, J. A.; Frisch, M. J.; Ochterski, J. W.; Petersson, G. A.
J. Chem. Phys. 1999, 110, 2822-2827.
(18) Davis, R. W.; Gerry, M. C. L. J. Mol. Spectrosc. 1977, 65, 455-473.
(19) (a) Beagley, B.; Echersley, G. H.; Brown, D. P.; Tomlinson, D. Trans.
Faraday Soc. 1969, 65, 2300-2307. (b) Marsden, C. J.; Brown, R.
D.; Godfrey, P. D. J. Chem. Soc., Chem. Commun. 1979, 9, 399-
401.
(20) Schulz, A.; Tornieporth-Oetting, I. C.; Klapo¨tke, T. M. Inorg. Chem.
1995, 34, 4343-4346.
(21) Klapo¨tke, T. M.; Schulz, A. Inorg. Chem. 1997, 36, 1929-1933.
(22) Rosmus, P.; Stafast, H.; Bock, H. Chem. Phys. Lett. 1975, 34, 275-
280.
(23) Frost, D. C.; MacDonald, C. B.; McDowell, C. A.; Westwood, N. P.
C. J. Am. Chem. Soc. 1981, 103, 4423-4427.
(16) Ortiz, J. V. J. Chem. Phys. 1988, 89, 6348-6352.
5972 Inorganic Chemistry, Vol. 45, No. 15, 2006

Gas-Phase Generation and Electronic Structure of ClSSCN
Figure 2. HeI photoelectron spectrum of ClSSCN.
Table 2. Experimental and Calculated Ionization Energiesa and MO
Characters for ClSSCNa
band
expb
calcd
MO
character
1
2
3
4
10.20(V) 9.86(A)c 10.19(V)d 10.24(V)e 31 πnb(ClS)
10.83
11.91
13.01
10.84
11.93
12.92
13.07
13.66
14.05
14.60
10.86
11.88
12.97
12.99
13.68
14.03
14.56
30 πnb(SCN)
29 πnb(ClS)+ πnb(SCN)
28 nCl, πb (CN)
27 nCl, πb (CN)
26 πb(ClS)
Figure 1. Photoionization mass spectra of (a) ClSSCN and (b) the gaseous
products of the reaction at 70 °C.
5
6
7
13.65
14.07
14.76
25 πb(ClS) + πb (SCN)
24 σCN
close agreement with the experimental values of 84.8-85.2°,
83.5 ( 1.1°, 90.6 ( 0.5° found for S2Cl2,19 S2Br2,27 and S2H2,
respectively.28
a All energies are in eV units; (V) ) vertical ionization energy; (A) )
adiabatic ionization energy; if no symbol is listed the vertical ionization
energy is implied. b (0.01 eV. c CBS-QB3. d ROVGF from the geometries
of MP2/6-311+G*. e ROVGF from the geometries of B3LYP/6-311+G*.
3.2. Photoionization Mass Spectrometry. The reaction
process for generating ClSSCN was monitored by photo-
ionization mass spectrometry. The ultraviolet photoionization
mass spectra of the reaction products of gaseous SCl2 and
AgSCN at different temperatures are shown in Figure 1.
Figure 1a depicts the mass spectrum of the reaction at 40
°C, which shows a typical fragmentation distribution of
ClSSCN cation. The peaks in the spectrum are SCN+, SCl+,
SSCN+, S2Cl+, and ClSSCN+, respectively, with the domi-
nant features being the SSCN+ and parent ClSSCN+ peaks.
The appearance of the ClSSCN molecular ion confirms its
generation and identification. Normally, HeI photoionization
produces a fragmentation distribution that is very similar to
the distribution observed using electron-impact ionization.
This may be rationalized by a similar energy deposition
mechanism for the two methods, because the interaction
energies (approximately tens of electronvolts) are compa-
rable. As the strongest peak in the HeI PIMS of ClSSCN,
the SX+ (X ) SCN) fragment is analogous to that of the
electron-impact spectra of other ClSX molecules (X ) Cl,
SCl, and CH2CH3),29 which mostly result from the direct
dissociation of the Cl-S bond in the ClSX+ parent ions.
Figure 1b illustrates the photoionization mass spectrum
of the gaseous products of the reaction at 70 °C, which
+
were made to maximize the intensities of S(SCN)2 by
raising the reaction temperature, but they all failed until CS2
appeared, the product of pyrolysis for AgSCN. A possible
reaction route is illustrated by the following sequence
In a word, by analyzing the results of ultraviolet photo-
ionization mass spectrometry, we confirmed the generation
of ClSSCN under our experimental conditions. And the
dominant fragment SSCN+ found in the mass spectrum
indicates that the ClSSCN cation prefers the dissociation of
Cl-S bond.
3.3. Photoelectron Spectroscopy. The HeI photoelectron
spectrum of ClSSCN is shown in Figure 2 (for that of the
gaseous products of the reaction between SCl2 and AgSCN,
see the Supporting Information). It exhibits seven ionization
bands in the low-energy region. We attempted to obtain the
PE spectrum of S(SCN)2, of which the crystal structure has
been determined by X-ray methods,30 but found that gaseous
S(SCN)2 is highly unstable and very easily decomposes into
(SCN)2 and S. The PE spectrum of the gaseous products of
the reaction at 70 °C, corresponding to the mass spectrum
in Figure 1b, shows the typical bands of (SCN)2.8
+
+
reveals features for SCN+, SSCN+, (SCN)2 , and S(SCN)2 ,
respectively. Other fragments came from the dissociation of
+
+
molecular ions (SCN)2 and S(SCN)2 . Several attempts
(24) Palmer, K. J. J. Am. Chem. Soc. 1938, 60, 2360-2369.
(25) Stevenson, D. P.; Beach, J. Y. J. Am. Chem. Soc. 1938, 60, 2872-
2876.
(26) Crawford, M.-J.; Klapo¨tke, T. M.; Klu¨fers, P.; Mayer, P.; White, P.
S. J. Am. Chem. Soc. 2000, 122, 9052-9053.
(27) Hirota, E. Bull. Chem. Soc. Jpn. 1958, 31, 130-138.
(28) Winnewisser, G. J. Mol. Spectrosc. 1972, 41, 534-547.
(29) NIST Chemistry WebBook; Linstrom, P. J., Mallard, W. G., Eds.;
National Institute of Standards and Technology: Gaithersburg, MD,
2001.
The experimental and calculated ionization energies as well
as the molecular orbital character of ClSSCN are listed in
Table 2. It is noted that the ROVGF results are in good
(30) Fehe´r, F.; Linke, K.-H. Z. Anorg. Allg. Chem. 1964, 327, 151-158.
Inorganic Chemistry, Vol. 45, No. 15, 2006 5973

Yao et al.
agreement with the experimental data.31,32 Considering the
33
PE spectra of S2Cl2 and (SCN)2,8 we can characterize the
chlorosulfanyl thiocyanate by its bands that are attributed to
the π systems of the ClS and SCN moieties, the nonbonding
orbitals of chlorine atom, and the C-N bond. Therefore, the
study of these bands may reflect the extent and character of
the intramolecular interactions. The MO calculation predicts
that the first three transitions for ClSSCN belong to an
antibonding electron from the ClS and SCN π systems.
The first band, at 10.20 eV with an ionization onset of
9.88 eV, corresponds to the ionization process of ClSSCN
(X1A) f ClSSCN+ (X2A). The experimental result is in good
agreement with the calculated vertical IPs. The first band is
due to ionization of an electron from the π type of Cl-S
antibonding orbital, predominantly localized on the sulfur
atom. It is similar to the first ionization band of the analogous
molecule SCl2, ClSCN.23,33 Because there is more S 3p
involvement in the first orbital of ClSSCN, its first IP is
lower than that of ClSCN (10.52 eV).
Figure 3. Characters of the first eight highest occupied molecular orbitals
for ClSSCN.
ejection from orbitals containing considerable amounts of
chlorine 3p character. The ionization of nonbonding electrons
should raise a typical sharp intense band. However, the
unusually large width of the fourth band suggests the
possibility that this band is actually a composite of two
overlapping transitions. And the calculated IPs of orbitals
28 and 27 indicate that both transitions are too close to being
resolved. Because of the extensive incorporation of the SCN
group, both have primary MO characters that are a mixture
of nonbonding orbitals of the chlorine atom and bonding πCN.
The remaining chlorine orbitals form MO 26, which is
strongly S-Cl bonding. It raises a typical band at 13.65 eV
for ionization of electrons from bonding orbitals.
The bands at higher energy 14.07 and 14.76 eV are due
to the ionization of bonding orbitals, corresponding to a
combination of πSCl and πSCN bonding and a σCN bonding,
respectively (Figure 3).
In a word, the outer molecular orbital structure of ClSSCN
was studied through photoelectron spectroscopy and quantum
chemical calculations for the first time. The outermost
electrons reside in the Cl-S antibonding π orbital, predomi-
nantly localized on the sulfur atom. The halogen nonbonding
electrons are more tightly bound than the antibonding
electrons from the ClS and SCN π systems.
The second band is localized at 10.83 eV, which is in
agreement with the ROVGF results. It can be described as
a πSCN antibonding orbital primarily residing on the sulfur
atom. This orbital can also be regarded as being the
antisymmetric combination of the sulfur lone-pair and πCN
orbital. In most cases, the spectra of pseudohalides are
somewhat more complicated. The electronic structure of the
SCN group can be explained in two ways. One can assume
a single S-C bond and a triple CtN bond. In this case, the
appearance of two new bands resulting from the CtN π
bonds is expected in the low-energy region of the spectrum.
Another interpretation is that the SCN unit is considered to
be two perpendicular four-electron, three-center π systems.
Consistent with analogous XSCN (X ) CN,23 SCN8)
molecules, there are ionization events from two πCN orbitals
following the first band in ClSSCN (Figure 3). Corresponding
to the second πCN orbitals, the third PE band at 11.91 eV is
the ionization result of the combination of πClS and πSCN
antibonding character.
The 3p nonbonding orbitals of the chlorine atoms are
expected to locate in the energy range 11-14 eV. The first
ionization potential (IP) of the Cl atom is 12.97 eV,34 and
that of chlorine-containing molecules exhibits an IP very
close to this value (e.g., Cl2 ) 11.59,35 HCl ) 12.75,35 ClF
) 12.77 eV36). On this basis, the fourth and fifth bands at
13.01 and 13.65 eV are expected to be the results of electron
4. Conclusions
The novel transient species ClSSCN was generated in the
gas phase for the first time through in situ heterogeneous
reaction of gaseous SCl2 with AgSCN. The gaseous reaction
products were detected and characterized by ultraviolet
photoelectron and photoionization mass spectrometry. The
geometric and electronic structures of ClSSCN were inves-
tigated by a combination of PES experimental and theoretical
studies with the help of DFT and ab initio calculations. The
assignment of the PES bands is reasonably supported by
previous studies on analogous molecules, as well as the
ROVGF and CBS-QB3 calculations. Both the spectroscopic
and theoretical investigations have proved the formation of
the chlorosulfanyl thiocyanate molecule and suggest that the
outermost electrons reside in the Cl-S antibonding π orbital,
(31) Zeng, X. Q.; Ge, M. F.; Sun, Z.; Wang, D. X. Inorg. Chem. 2005, 44,
9283-9287.
(32) Zeng, X. Q.; Liu, F. Y.; Sun, Q.; Ge, M. F.; Zhang, J. P.; Ai, X. C.;
Meng, L. P.; Zheng, S. J.; Wang, D. X. Inorg. Chem. 2004, 43, 4799-
4801.
(33) Colton, R. J.; Rabalais, J. W. J. Electron Spectrosc. Relat. Phenom.
1974, 3, 345-357.
(34) Kimura, K.; Yamazaki, T.; Achiba, Y. Chem. Phys. Lett. 1978, 58,
104-107.
(35) Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S.
Ionization Energies, Ab initio Assignments, and Valence Electronic
Structure for 200 molecules in the Handbook of HeI Photoelectron
Spectra of Fundamental Organic Compounds; Japan Scientific Society
Press: Tokyo, 1981.
(36) Dyke, J. M.; Josland, G. D.; Snijders, J. G.; Boerrigter, P. M. Chem.
Phys. 1984, 91, 419-424.
5974 Inorganic Chemistry, Vol. 45, No. 15, 2006

Gas-Phase Generation and Electronic Structure of ClSSCN
predominantly localized on the sulfur atom. The halogen
nonbonding electrons are more tightly bound than the
antibonding electrons from the ClS and SCN π systems. The
dominant fragment SSCN+ in the mass spectrum indicates
that the ClSSCN cation prefers the dissociation of the Cl-S
bond.
and X.Z. thank the Chinese Academy of Sciences for receipt
of scholarships during the period of this work.
Supporting Information Available: HeI photoelectron spec-
trum of the gaseous products (SCN)2 of the reaction between
gaseous SCl2 and AgSCN at 70 °C; calculated geometric constants
for the equilibrium structure of the neutral molecule and cation;
orbital energies with the first eight highest occupied molecular
orbitals; and energies of the dissociated fragment of ClSSCN+. This
material is available free of charge via the Internet at http://
pubs.acs.org.
Acknowledgment. This project was supported by the
Chinese Academy of Sciences (Hundred Talents Fund) and
the National Natural Science Foundation of China (Contract
20577052, 20473094, 50372071, 20503035). L.Y., W.W.,
IC060513S
Inorganic Chemistry, Vol. 45, No. 15, 2006 5975