Disulfuryl Dichloride ClSO2OSO2Cl: A Conformation and Polymorphism Chameleon

Article abstract of DOI:10.1002/chem.201800817

Disulfuryl dichloride ClSO₂OSO₂Cl was characterized by vibrational spectroscopy in the gaseous and liquid phase as well as in the Ar-matrix. By varying the temperature, certain bands could be assigned to several conformers. Gas-phase electron diffraction revealed a dominance of the anti-conformer at ambient temperature. The same conformation was found in the solid state. Via the in situ technique for crystallization, not less than four different modifications were identified. Among these different modifications, the structural parameters of the molecules remain relatively constant, but the aggregation pattern changes. Although the molecules aggregate by chlorine???oxygen contacts in each modification, the geometrical parameters of these interaction show significant differences and were evaluated and are in part inconsistent with the halogen bonding concept.

Full text of DOI:10.1002/chem.201800817

A Journal of
Accepted Article
Title: Disulfuryl dichloride ClSO2OSO2Cl - a conformation and
polymorphism chameleon
Authors: Norbert Werner Mitzel, Jan Schwabedissen, Angélica Moreno
Betancourt, Rosana M. Romano, Carlos O. Della Védova,
Helmut Beckers, Helge Willner, and Hans-Georg Stammler
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To be cited as: Chem. Eur. J. 10.1002/chem.201800817
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Disulfuryl dichloride ClSO2OSO2Cl – a conformation and
polymorphism chameleon
Angélica Moreno Betancourt,a Jan Schwabedissen,b Rosana M. Romano,a* Carlos O. Della Védova,a
Helmut Beckers,c Helge Willner,d Hans-Georg Stammlerb and Norbert W. Mitzelb*
Abstract: Disulfuryl dichloride ClSO2OSO2Cl was characterized by
vibrational spectroscopy in the gaseous and liquid phase as well as
in the Ar-matrix. By varying the temperature, certain bands could be
assigned to several conformers. Gas-phase electron diffraction
revealed a dominance of the anti-conformer at ambient temperature.
The same conformation was found in the solid state. Via the in situ
technique for crystallization, not less than four different modifications
were identified. Among these different modifications, the structural
parameters of the molecules remain relatively constant, but the
aggregation pattern changes. Although the molecules aggregate by
chlorine···oxygen contacts in each modification, the geometrical
parameters of these interaction show significant differences and
were evaluated and are in part inconsistent with the halogen bonding
concept.
res was undertaken. Contrary to that, the corresponding
disulfuryl difluoride, FSO2OSO2F, has been characterized
spectroscopically[1,6] and structurally – first in the gas phase[7]
and later also in the solid state.[8] In the gas phase the difluoride
solely consists of an anti-conformer with a torsional angle
ϕ(FS⋯SF) of 119.1(6)°, whereas in the solid state this torsional
angle measures 144.9(1)° while no pronounced individual
interactions amongst the molecules can be identified.
Herein, we report for disulfuryl dichloride, ClSO2OSO2Cl, the
spectroscopic properties in the liquid, the gas phase and in Ar-
matrix isolation as well as the structures determined in the solid
state by X-ray diffraction on in situ grown crystals and in the gas
phase by electron diffraction of free molecules.
Introduction
Disulfuryl dichloride, ClSO2OSO2Cl, can be synthesized in a
photochemical reaction of Cl2 and O2 with SO2.[1] Thus, this
reaction can take place in the Venusian atmosphere, where high
concentrations of chlorine gas are found.[2] A photochemical
reaction yielding the peroxo-bridged disulfuryl dichloride,
ClSO2OOSO2Cl, confirms this[3] and provides an explanation of
the relatively low concentration of oxygen in Venus’ atmosphere.
A previous study on the photochemical properties of disulfuryl
dichloride[4] revealed its high thermal and photochemical stability.
Although the title compound is known for more than a century[5]
no complete elucidation of its spectroscopic or structural featu-
Figure 1. Potential energy surface for the rotations about the S1–
O1 and S2–O1 axes by independently varying the two dihedral
angles ϕ(Cl1-S1-O1-S2) and ϕ(Cl2-S2-O1-S1). Atom numbering is
presented in Figure 2.
[a]
A. Moreno Betancourt, Prof. Dr. R. M. Romano, Prof. Dr. C. O. Della
Védova
CEQUINOR (UNLP−CONICET, CCT La Plata),
Departamento de Química, Facultad de Ciencias Exactas,
Universidad Nacional de La Plata,
Results and Discussion
La Plata CP 1900, Argentina
E-mail:
For the determination of possible conformers in the gas phase
a potential-energy scan was performed on the O3LYP[9] level
of density-functional theory with the correlation consistent cc-
pVTZ[10] basis set (Figure 1). On this fourfold symmetric
energysurface, three distinguishable conformers were located.
The lowest-energy anti-conformer is of C2 symmetry and has
both dihedral angles ϕ(Cl1-S1-O1-S2) and ϕ(Cl2-S2-O1-S1) of
about 80° and a dihedral angle along the S···S vector,
ϕ(Cl-S⋯S-Cl), of 152°. The syn-conformer is the next lowest in
energy; its dihedral angles ϕ(Cl1-S1-O1-S2) and ϕ(Cl2-S2- O1-
S1) measure 70° and 250° (equivalent to 110°). This
conformer adopts a torsional angle ϕ(Cl-S⋯S-Cl) of 37°. The
highest-energy minimum corresponds to the gauche-conforma-
[b]
Dr. J. Schwabedissen, Dr. H.-G. Stammler, Prof. Dr. N. W. Mitzel
Fakultät für Chemie, Lehrstuhl für Anorganische Chemie und
Strukturchemie, Centrum für molekulare Materialien CM2,
Universität Bielefeld, Universitätsstr. 25,
33615 Bielefeld, Germany
E-mail: mitzel@uni-bielefeld.de
Dr. H Beckers
Institut für Chemie und Biochemie, Anorganische Chemie, Freie
Universität Berlin, Fabeckstraße 34 – 36,
14195 Berlin, Germany
Prof. Dr. H. Willner
FB C – Anorganische Chemie, Bergische Universität Wuppertal,
Gaußstraße 20
42097 Wuppertal, Germany
Supporting information for this article is given via a link at the end of
the document.
[c]
[d]
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tion with dihedral angles ϕ(Cl1-S1-O1-S2) and ϕ(Cl2-S2-O1-S1)
of 90° and 190°(equivalent to 170°), and ϕ(Cl-S⋯S-Cl) of 83°. All
conformers are depicted in Figure 3 and the calculated structural
parameters are listed in Table 1.
Figure 2. Raman spectrum of the liquid (left) and infrared spectrum of the gas (right) of ClSO2OSO2Cl. The upper traces (blue) show
experimental and the lower show the spectra of the different conformers are weighted according to the equilibrium abundance at 20°C
according to the B3P86/6-31G(d) level of theory.
nearly in-plane with the S-O1-S unit than to the other SO2Cl
fragment (1.648 Å). The smallest S1-O1-S2 angle (119.4°) is
also observed in the gauche-conformer.
Vibrational Spectroscopy
Intensive studies on the vibrational properties of molecules
containing the S-O-S moiety have been carried out in the
1960s.[1,6,12] In here, infrared spectroscopy of the gas and
Raman spectroscopy of the liquid phase of disulfuryl dichloride
along with matrix isolation infrared spectroscopy were used to
determine the conformational behavior in the different phases.
Therefore, experimental spectra are compared to theoretical
ones at the B3P86/6−31G(d)[13,14] level of theory. Figure 3 shows
the FTIR and FT Raman spectra at 20 °C in comparison with the
computed ones for the different conformers; Table S4 contains a
detailed listing of the vibrational frequencies with a new
assignment as well as the one of previous investigations.
As the recorded spectra show less bands than for the preceding
investigations,[15] the bands were assigned de novo.[5] The
smaller number of bands indicates a higher purity of the sample
used here. Despite the additional bands present in the reported
vibrational spectra, there is a good agreement between the
present spectra and the reported ones.[15] The authors report a
single band for νas(SO2) at 1470 cm−1 and both symmetric
stretching modes of the SO2 unit to appear at 1225 and 1201
cm−1. In the Raman spectrum some bands differ slightly from the
bands assigned by Gillespie.[1] E.g. the antisymmetric stretching
modes of the SO2 group are now found at 1455 and 1438 cm−1;
they were earlier assigned to 1462 and 1442 cm−1. In the sym-
Figure 3. Calculated structures of the different conformers of
ClSO2OSO2Cl .
Table 1. Structural parameters of the different conformers calculated at the
MP2[11]/cc-pVTZ level of theory.
Parameter
anti
syn
gauche
r(O1–S1)
r(O1–S2)
r(S1–Cl1)
r(S2–Cl2)
∡(S1-O1-S2)
∡(O1-S1-Cl1)
∡(O1-S2-Cl2)
ϕ(Cl1-S1-O1-S2)
ϕ(Cl2-S2-O1-S1)
1.654
1.654
2.027
2.027
122.2
98.8
98.8
78.8
78.8
1.654 1.648
1.652 1.665
2.019 2.015
2.020 2.012
124.2 119.4
100.4 99.6
97.7
66.2
93.9
86.5
108.2 163.9
ϕ(Cl2-S2···S1-Cl1) 151.9
Abundance,% 70.4
38.4
16.3
78.7
13.3
Distances r in Å, angles ∡ and dihedrals ϕ in degrees.
Corresponding structure parameters of the three conformers
depend on their torsional angles as well as on their central S-
O1-S angle. For example, in the gauche-conformer the S–O1
bond to the SO2Cl is longer at 1.665 Å group with the S–Cl
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metric stretching mode region only one band at 1214 cm−1 is ob-
served in the present Raman spectrum while in the previous
work two bands, at 1209 cm−1 and 1189 cm−1, were assigned to
these modes. However, for a more thorough investigation of the
conformational composition we recorded matrix infrared spectra
of isolated species at cryogenic temperatures (15 K) for different
inlet temperatures. Some representative spectra are shown in
Figure 5.
The effect of heating is not only the increase of the relative
intensity of the bands of the less abundant conformers but also
decomposition of the compound under investigation. This is
observed in form of the peaks at about 1350 cm−1 which are the
characteristic bands of sulfur dioxide and trioxide.[17] Figure 4
shows enlargements of two different regions of the matrix IR
spectra.
Figure 4. Different regions (right: 1180 – 1240 cm−1; left: 1440 – 1475 cm−1) of the IR spectra of isolated molecules of ClSO2OSO2Cl in an
argon matrix at 15 K. The mixture of the inert gas and the sample was heated prior to ablation to the shown temperatures.
gauche-conformers, respectively, as the computed values of the
absorption coefficients are much larger for these conformers
than for the anti-conformer, to which the band at 1222 cm−1 was
assigned. At 1192 cm−1 an overtone of the deformation vibration
of the SO2 group of the anti-conformer is observed, which is
intensified due to Fermi resonance with the νs(SO2) fundamental
mode. Other bands in the spectra were analyzed in a similar
way based on the computed frequencies and the intensities
changing at different temperatures. Table S4 summarizes the
assignments of the vibrational bands to the different conformers.
Gas-phase structure
The structure of free molecules of disulfuryl dichloride was
determined by means of gas electron diffraction (GED). Details
of the procedure are described in the Experimental Section (vide
infra). In the refinement, all three different conformers were
initially included and their contributions weighted according to
the differences in energy at the MP2/cc-pVTZ level of theory.
For the conformer being lowest in energy (anti) C2 symmetry
was assumed while the other two possible conformers were
described in C1 symmetry. During the refinement, the amounts
of conformers were varied without any restrictions. Initially, the
bonded distances were refined successively in three individual
groups. As a next parameter the ∡(S-O1-S) angle was included
in the refinement followed by two groups of ∡(Ot-S-Ot) angles,
one with higher and the other one with lower values.
Subsequently the angles ∡(O1-S-Cl) were refined in a group and
all ∡(Cl-S-Ot) angles were grouped together. The dihedral ang-
les ϕ(S-O1-S-Cl) were refined separately for each conformer
and in the conformers of C1 symmetry the dihedral angles were
Figure 5. FTIR spectra of ClSO2OSO2Cl isolated in an argon matrix. The
samples were heated to the shown temperatures directly prior to deposition on
the cold window.
The region between 1475 and 1440 cm−1 shows the asymmetric
stretching vibrations of the SO2 unit (νas(SO2)). Bands are
assigned according to the relative changes upon heating. The
symmetric stretching modes are observed in the interval
between 1240 and 1180 cm−1. As expected the relative
intensities of the bands belonging to the lowest-energy
conformer, anti, decrease when the mixture is heated. In the left
part of Figure 5 this behavior is seen for the band at 1465 cm−1;
thus this belongs to the anti-conformer. The band at 1449 cm−1
corresponds to the gauche-conformer as it is becoming more
intense upon heating relative to bands of the anti-conformer.
The bands at 1227 and 1224 cm−1 are assigned to the syn- and
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refined individually with restraints to their computational values.
Altogether, this resulted in three groups of bonded distances,
five groups of angles, five groups of dihedral angles and nine
groups of amplitudes, which were refined independently.
Table 3. Characteristic structural parameters of symmetrically substituted disulfuryl compounds and sufuryl chloride in the gas phase.
parameter
X
F
C
r(O1–S)
1.611(5) 1.525(5) 123.6(5)
1.623(5) 1.848(6) 128.1(14) 99.1(14)
r(S–X)
ϕ(S-O-S-X)
Ref
7
18
∡(S-O-S)
∡(O1-S-X) ∡(Ot-S-Ot)
FSO2OSO2F
CF3SO2OSO2CF3 ra
rg
102.4(18)
128.5(14)
128.0(21)
123.5(2)
125.1(2)
73.7(24)
99.1(14)
a
SO2Cl2
rg Cl
2.012(4)
100.3(2)
98.7(3)
19
ClSO2OSO2Cl
rg Cl 1.626(1) 1.992(1) 127.2(2)
80.5(4)
here
Distances r in Å, angles ∡ and dihedral angles ϕ in deg.a The angle ∡(O1-S-X) refers to the ∡(Cl-S-Cl).
values and the refinement resulted in a disagreement factor of
more than Rf = 5.0%. The presence of other conformers, as was
proven by spectroscopy (see above) could neither be confirmed
nor excluded by GED on the level of significance. Thus, we
decided to use a one-conformer model to describe the experi-
mental scattering data. Such a model for the anti-conformer
gave a satisfactory agreement with the experimental electron
diffraction data with an Rf = 3.39%. The gas-phase structural
parameters are listed in Table 2.
The conformation of gaseous disulfuryl dichloride is defined by
the torsional angle ϕ(Cl-S···S-Cl). Its value of 155.2(9)° agrees
well with the calculated parameter (151.9°). The difference re-
garding the structures in the solid state, in particular deviation
from C2 symmetry in the solid state, is due to the formation of
asymmetric halogen bonds (vide infra). Regarding the confor-
mation the characteristic parameters in the gas phase are within
the range found in the solid state of the different polymorphs and
in good accordance with the averaged values of structure:
ϕ(Cl-S···S-Cl)
148.0(1)° to 162.0(1)° and ϕ(S-O-S-Cl)
(gas/solidaverage/range)
=
155.2(9)°/153.8°/
80.5(4)°/80.7°/,
=
77.1(2)° to 86.0(1)°. Comparing the thermally averaged bonded
distances S–O1 in the gas phase (1.626(1) Å) to the analogous
ones in the solid state (average 1.627 Å ranging from 1.620(1) Å
to 1.634(2) Å) this is in good agreement. On the other hand, the
S–Cl distance in the solid state (average 1.973 Å) is by 0.02 Å
shorter than the corresponding one in the gas phase. The
central angle at oxygen ∡(S-O-S) deviates with 127.2(2)° from
an ideal angle at a twofold substituted. This deviation can be
attributed to the higher steric demand of the chlorosulfuryl group
or to a conjugation effect resulting in some double bond
character of the S–O1 bond. In the solid state, the angle ∡(S-O-
S) is about three degrees narrower (average: 124.4°).
In Table 3 parameters of gas-phase structures of comparable
molecules are listed. For of all three symmetrically substituted
disulfuryl compounds a one-conformer model was used to de-
scribe the gas-phase composition. Regarding the conformational
behavior the two examples in the literature, FSO2OSO2F[7] and
CF3SO2OSO2CF3[18], and the here examined ClSO2OSO2Cl show
anti-conformations regarding the positions of the halogen atoms
or the trifluoromethyl group relatively to the S···S vector. The
largest dihedral angle ϕ(S-O-S-X) is found in the trifluoromethyl
compound (99.1(14)°), followed by the dichloride (80.5(4)°) and
the difluoride (73.7(24)°). The same trend is observed for the
central angle ∡(S-O-S) which rises from the difluoride
(123.6(5)°) to the dichloride and the trifluoromethyl species
Figure 6. Radial distribution curve of the GED structure refinement of
ClSO2OSO2Cl: experimental values (circles), model (solid line) and difference
curve (lower trace, experimental minus modelled). Vertical sticks represent
interatomic distances (selected are labelled).
Table 2. Structural parameters of the gas-phase structure of ClSO2OSO2Cl.
parameters
r(S–Cl)
r(S=O1)
r(S=O2)
r(S–O1)
∡(O1-S-Cl)
∡(O=S=O)
∡(S–O–S)
ϕ(S-O-S-Cl)
ϕ(Cl-S…S-Cl)
rg
l
re, ∡e
1.985(1)1
1.408(1)2
1.412(1)2
1.617(1)3
98.7(3)4
125.1(2)5
127.2(2)6
80.5(4)7
155.2(9)a
1.992(1)
1.413(1)
1.417(1)
1.626(1)
0.05048
0.04009
0.03999
0.047510
Distances r in Å, angles ∡ and dihedral angles ϕ in deg, Numbers as
a
superscript indicate the groups the parameters were refined in. Dependent
parameter. re distance between equilibrium nuclear positions, rg thermal
averaged internuclear distance, l amplitude of vibration.
The refinement using a three-conformer model resulted in large
correlations among the different types of parameters, e.g. ampli-
tudes and amounts of the conformers in the gas phase. This led
some refined parameters to adopt chemically unreasonable
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(127.2(2)° and 128.1(14)°, respectively), which are the same
within the error limits. Both angles reflect the steric demand of
the substituents, which rises from fluorine over chlorine to CF3.
The bond to the central oxygen atom elongates along the series
FSO2OSO2F, CF3SO2OSO2CF3 and ClSO2OSO2Cl, whereas the
latter two are the same within the error limits. This structural
feature reflects the decreasing double bond character in the
central sulfur–oxygen bond along this series. The gas-phase
structure of sulfuryl chloride[19] shows a slightly longer S–Cl bond
and a shorter angle regarding the terminal oxygen atoms
(123.5(2)°) compared to the disulfuryl dichloride (125.1(2)°).
pattern to the next molecules differs significantly as can be seen
in Figure 9.
As the result the aggregation motif of both modifications shows
four dimers forming a 22-membered ring via O···Cl contacts b
& b, by involving alternatingly one dimer with a molecular unit
site and one with an aggregated site, but differing in the
orientation of the dimers to each other as shown in Figure 10
and 11. The layers shown in Figure 11 are further interconnec-
ted by weaker Cl···O contacts longer than 3.2 Å.
Structures in the solid state
Suitable crystals of disulfuryl dichloride were grown in situ in a
flame sealed capillary directly on the diffractometer. The capilla-
ry was heated and cooled several times applying different tem-
perature programs (see Experimental section). In this way, we
obtained not less than four different modifications from the
identical sealed sample of the title compound and determined
the crystals structure of each of these modifications plus
additionally a crystal structure of oxonium perchlorate. For crys-
tallographic details see Table 9. All four modifications exhibit
approximately the same intramolecular structural parameters; a
full listing is given in Table 4; Figure 7 depicts the molecular
structures of modification
1 and 2. The molecules of
ClSO2OSO2Cl aggregate via O···Cl interactions of the sigma-
hole type (see below for detailed discussion), the structural
parameters of these non-covalent interactions below the sum of
VdW-radii of 3.32 Å are listed in Table 5 and are depicted in a
graphic way in Figure 15. The aggregation of the four
modifications is shown in Figures 8 – 14.
Figure 8. Dimers of (a) modification 1 and (b) modification 2 of ClSO2OSO2Cl.
Figure 7 Molecular structure showing atom labelling in modifications 1 (left)
and 2 (right) of ClSO2OSO2Cl.
Modifications 1 – 3 are monoclinic, space group P21/c, the fourth
̅
is triclinic, space group P1. The four different modifications can
be subdivided into two pairs regarding the number of molecules
contained in the asymmetric unit. Modifications 1 and 2 contain
one molecule per asymmetric unit; modifications 3 and 4 contain
three crystallographically independent molecules The packing in
modification 1 is more dense, it has the highest density
(2.234 g cm–3) of all four modifications, while the other three
have lower, but very similar ones (modifications 2 – 4: 2.211,
2.212, 2.211 g cm–3). Additionally modifications 3 and 4 show
two very similar unit cell axis: 7.619 Å resp. 7.612 Å and 9.441
resp. 9.447 Å. There are thus in total eight independently struc-
turally characterized molecules of ClSO2OSO2Cl.
Modifications 1 and 2 contain primarily dimeric aggregates of
inversion symmetry, by two intermolecular, symmetrically
identical O···Cl interactions (a & a) resulting in ten-
membered rings, which are nearly congruent for both
modifications as can be seen in Figure 8. The aggregation
Figure 9. Aggregation of dimers of ClSO2OSO2Cl in (a) modification 1 and (b)
modification 2.
In modifications 3 and 4 inversion symmetric tetramers are for-
med by two symmetrically unique Cl···O contacts (a & c and
a & c) forming 18 membered rings, see Figure 11. These
tetramers are formed by each monomer contributing one O and
one Cl atom for interactions, however, alternatingly so that one
monomer uses O and Cl atoms of the same SO2Cl group and
the other monomer contributes with the either the O or Cl atom
from each of its two SO2Cl moiety in the other crystallographic
unique monomer. The angles of both unique Cl···O connecting
vectors of a and c as well as of a and c are 113.8(1)° in
both modifications. These tetramers are connected to other
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tetramers by two crystallographically equivalent monomers of
ClSO2OSO2Cl contributing with both their chlorine atoms (Cl···O
contacts: b & d and b & d) forming a 28-membered ring
involving eight ClSO2OSO2Cl molecules in the same way for
both modifications building a rope-ladder like motif, see Figure
12.
The difference between both modifications 3 and 4 is not obvi-
ous without considering the arrangement of these ladders
relative to each other. The weaker O···Cl interactions, i.e. e
and f or e and f, interconnect the rope ladders in different
ways. No additional O···Cl interactions below 3.32 Å can be
found. For better visibility a plane defined by the four σ-hole-
bonded chlorine atoms of the tetramers was sketched in Figure
13. These planes must be all parallel in triclinic modification 4,
whereas monoclinic modification 3 shows an angle of 15.0(1)°
between the planes of two different rope ladders.
Concerning the molecular structures, the central S–O bonds
vary between 1.620(1) and 1.634(2) Å. The range for the S–Cl
bonds is 1.966(1) to 1.979(1) Å. The central S1-O1-S2 angle
varies from 123.9(1)° to 125.0(1)°. The dihedral angles
ϕ(Cl1-S1-O1-S2) and ϕ(Cl2-S2-O1-S1) adopt values between
86.0(1)° and 77.2(1)°. The mean value is in good agreement
with the calculated minimum structure adopting a dihedral angle
of 78.8° at the MP2/cc-pVTZ level of theory. In comparison to
the gas-phase structure of ClSO2OSO2Cl the dihedral angle
(80.5(4)°) lies within the range of the solid-state parameter. Note
that the related disulfuryl difluoride, FSO2OSO2F ,[8] adopts C2
symmetry in the solid state. Its central S–O bonds at 1.610(1) Å
are shorter by about 0.01 Å than in the shortest measured here
in the chlorine analogue. This might be due to higher group
electronegativity of the fluorosulfuryl group. However, the varia-
tion of crystallographic parameters for ClSO2OSO2Cl by more
than 0.01 Å for the different molecules show, that such a
difference should not be over-interpreted, as for FSO2OSO2F
only one modification is known, and we do not know if the
structural values would also vary in a similar range for other
possible modifications. Similarly, the central S-O-S angle in the
difluoride at 123.4(1)° is 1° smaller than the average angle of the
value among the four modifications (123.9(1)°). The only clear
difference is the Cl-S···S-Cl dihedral angle along the S···S
connecting vector; this is by 15° smaller in the difluoride
(144.9(1)°) than in the dichloride – on average – which is likely
due to the higher steric demand of the chlorine atoms.
No directed interactions of the molecules among each other are
reported for FSO2OSO2F. By contrast, the related disulfuric acid
HOSO2OSO2OH,[20] is composed of three crystallographically
independent molecules in the asymmetric unit of its crystals, of
which two possess molecular C2 symmetry. The averaged
central S–O bond length at 1.617 Å is between those of the
difluoride and the dichloride. Comparing the central S-O-S angle
the acid exhibits the smallest one with 122.1° (averaged). Its
extended structure in the solid state is aggregated due to
hydrogen bonds. Four molecules form a 24-membered ring of C2
symmetry. Thus, the dichloride shows similarities with both
related compounds, the free acid and the fluoride, regarding the
asymmetric unit.
Table 4. Structural parameters of ClSO2OSO2Cl in the different modifications.
Modification
Molecule
1
2
3
2
4
2
1
3
1
3
r(O1–S1)
r(O1–S2)
r(S1–O2)
r(S1–O3)
r(S1–Cl1)
r(S2–O4)
r(S2–O5)
r(S2–Cl2)
∡(S1-O1-S2)
∡(O1-S1-Cl1)
∡(O1-S2-Cl2)
ϕ(S1-O1-S2-Cl2)
ϕ(S2-O1-S1-Cl1)
ϕ(Cl2-S2…S1-Cl1)
1.630(1)
1.628(1)
1.413(1)
1.412(1)
1.972(1)
1.412(1)
1.412(3)
1.971(1)
124.4(1)
100.0(1)
100.1(1)
85.5(1)
1.625(1)
1.633(1)
1.411(1)
1.410(1)
1.973(1)
1.410(1)
1.412(1)
1.966(1)
124.7(1)
100.5(1)
100.2(1)
86.0(1)
1.624(1)
1.629(1)
1.411(1)
1.409(1)
1.971(1)
1.411(1)
1.409(1)
1.976(1)
124.0(1)
100.7(1)
101.1(1)
77.6(1)
81.0(1)
151.0(1)
1.620(1)
1.633(1)
1.412(1)
1.410(1)
1.979(1)
1.411(1)
1.411(1)
1.967(1)
124.5(1)
101.3(1)
101.4(1)
77.2(1)
78.4(1)
148.0(1)
1.626(1)
1.624(1)
1.411(1)
1.413(1)
1.972(1)
1.410(1)
1.412(1)
1.975(1)
125.0(1)
101.3(1)
101.0(1)
82.7(1)
81.2(1)
155.4(1)
1.626(2)
1.625(2)
1.413(2)
1.405(2)
1.973(1)
1.412(2)
1.406(2)
1.977(1)
124.1(1)
100.7(1)
101.0(1)
77.9(2)
80.6(2)
150.9(1)
1.634(2)
1.626(2)
1.411(2)
1.405(2)
1.969(1)
1.413(2)
1.412(2)
1.977(1)
124.1(1)
101.4(1)
101.3(1)
78.6(2)
77.1(2)
148.1(1)
1.628(2)
1.624(2)
1.409(2)
1.410(2)
1.972(1)
1.416(2)
1.408(2)
1.975(1)
124.9(1)
101.2(1)
101.1(1)
82.4(2)
81.4(2)
155.4(1)
84.8(1)
162.0(1)
82.0(1)
159.8(1)
Distances r in Å, angles ∡ and dihedral angles ϕ in degree.
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Figure 10. Tetrameric arrangement of the dimers of ClSO2OSO2Cl in (a)
modification 1 and (b) modification 2.
Figure 11. Layer structure of (a) modification 1 and (b) modification 2 of
ClSO2OSO2Cl.
The above described aggregation by non-covalent interactions
in disulfuryl dichloride occur all by O···Cl contacts. These con-
tacts can be characterized as halogen bonding[21] involving
chlorine as acceptor and oxygen as donor. Characteristic for
halogen bonds is the distance between the interacting atoms,
the angle ∡(S-Cl···O) at the acceptor-halogen atom which
should be ideally 180° for a σ-hole-type interaction,[22] and the
angle at the donor-atom, oxygen ∡(S-O···Cl), which is expected
to be bent to represent the position of electron density accumu-
lation at oxygen.
A full listing of the structural parameters of all Cl···O distances
below the sum of their van der Waals-radii can be found in Table
5. The relation among the individual geometrical parameters is
depicted in Figure 15. A distinction between the shortest con-
tacts of each chlorine atom to an oxygen atom and longer ones
nevertheless being lower than the sum of the van der Waals-
radii (3.32 Å) allows a classification into primary and secondary
contacts, respectively. The majority of the primary contacts show
distances of about 3 Å, ∡(S-Cl···O) angles varying at about 140°
and ∡(S-O···Cl) between 160° and 180°. Thus, the high directio-
nal character of the halogen bond is proven in this case as well.
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The shortest contacts are observed at a Cl···O contact donated
by the third molecule in the asymmetric unit of modifications 3
and 4. These links amount to 2.893(1) Å (c) and 2.887(1) Å
(c) with angles of indistinguishable angles at the oxygen atom
of 174.9(1)°. The ∡(S-Cl···O) exhibits the same value in both
modification within the error ranges, 164.7(1)° and 164.8(1)° for
modifications 3 and 4, respectively.
Figure 13. Rope ladder motif of (a) modification 3 and (b) modification 4 of
ClSO2OSO2Cl.
Table 5. Full listing of the O···Cl interactions below 3.32 Å in the solid state of
ClSO2OSO2Cl. Distances r in Å and angles in degree.
Number
a
b
c
d
a
b
c
d
a
b
c
d
e
f
r(Cl···O)
2.974(1)
2.937(1)
3.244(1)
3.292(1)
2.997(1)
3.006(1)
3.291(1)
3.256(1)
2.997(1)
2.947(1)
2.893(1)
3.031(1)
3.133(1)
3.183(1)
3.243(1)
3.203(1)
3.218(1)
3.288(1)
2.990(2)
2.957(2)
2.887(2)
3.008(2)
3.149(2)
3.164(2)
3.214(2)
3.240(2)
3.236(2)
3.292(2)
3.289(2)
∡(SCl···O)
165.5(1)
177.7(1)
99.6(1)
∡(SO···Cl)
141.6(1)
144.5(1)
135.8(1)
154.8(1)
144.3(1)
146.8(1)
127.5(1)
154.6(1)
135.3(1)
145.0(1)
174.9(1)
149.4(1)
164.9(1)
156.8(1)
146.0(1)
133.8(1)
120.6(1)
155.5(1)
135.7(1)
144.5(1)
174.9(1)
150.0(1)
158.1(1)
163.5(1)
120.4(1)
132.7(1)
147.2(1)
135.8(1)
154.5(1)
r(S−Cl)
1.972(1)
1.971(1)
1.972(1)
1.972(1)
1.966(1)
1.973(1)
1.973(1)
1.966(1)
1.971(1)
1.972(1)
1.967(1)
1.975(1)
1.972(1)
1.975(1)
1.967(1)
1.976(1)
1.976(1)
1.979(1)
1.973(1)
1.972(1)
1.969(1)
1.975(1)
1.972(1)
1.975(1)
1.977(1)
1.977(1)
1.969(1)
1.969(1)
1.977(1)
105.8(1)
164.2(1)
171.6(1)
101.8(1)
104.2(1)
173.1(1)
167.8(1)
164.7(1)
172.5(1)
101.8(1)
100.6(1)
103.7(1)
156.3(1)
137.3(1)
97.7(1)
Figure 12. Inversion symmetric tetramers in the extended solid-state structure
of modification 3 (left) and modification 4 (right) of ClSO2OSO2Cl.For reasons
of clarity the third molecule in the asymmetric unit is wire framed.
The S−Cl bond lengths belonging to these contacts are the
second and third shortest found in this study measuring
1.967(1) Å and 1.969(1) Å in modifications 3 and 4, respectively.
However, primary contacts with Cl···O distances longer than
3.2 Å can be found as well. Three of these four (h, j, i;
fourth: g) show a systematic correlation between the Cl···O
distance and the angles concerning the halogen bond. Along
with the increasing of the Cl···O distance, the ∡(SCl···O) angle
decreases form 156.3(1)° (h) to 97.7(1)° (j) whereas the
∡(SO···Cl) angle increases from 133.8(1)° in h to 155.5(1)° in
j. This is a tendency observed for halogen bonding: a lower
angle at the halogen atom is related to a shorter distance of the
contact. Concerning the effect of the halogen bond on the S−Cl
bond an increase of the bond length by a longer Cl···O contact
can be derived from Figure 15. This is a contradicting fact to the
concept of halogen bonding as in such cases an elongation of
the covalent bond to a halogen atom is observed when the
Lewis base is draw closer to the halogen atom.[22]
g
h
i
j
a
b
c
d
e
f
173.2(1)
168.5(1)
164.9(1)
171.8(1)
102.8(1)
99.9(1)
g
h
i
137.5(1)
155.9(1)
103.1(1)
100.7(1)
98.5(1)
j
k
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Figure 15. Depiction of the parameters concerning the halogen bonds Cl···O
of ClSO2OSO2Cl. Angles ∡(S-O···Cl) and ∡(S-Cl···O) in °, distances r(Cl···O)
and r(S–Cl) in Å. Black dots stand for the shortest contact of each chlorine
atom (primary) whereas the red triangles indicate Cl···O with a longer distance
than the shortest one but less than the sum of the Waals-radii (secondary).
The secondary contacts (red triangles in Figure 15) show all
distances above 3.1 Å. The ∡(S-Cl···O) angles are mostly found
to be about 100° but in no other chart of Figure 15 common
features are recognized as the parameters are spread very
strongly.
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Figure 14. Arrangement of the rope ladders (a,c) in modification 3 and (b, d) modification 4 looking (a, b) roughly at the planes and (c, d) along the 9.44 Å axis
and (e, f) along the a-axes with ca. 7.6 Å of ClSO2OSO2Cl. The weaker contacts, i.e. 3e und f resp. 4 e and f, are shown as small dotted lines.
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comparable to the sulfur dioxide than to the sulfate ion judged
Electron-density topology
on the electron density at the critical points of the S–O bonds.
An experimental determination of the charge density distribution
ρ(r) is possible using high-angle X-ray diffraction data obtained
at low temperature.[24] The topological analysis based on
Bader´s quantum theory of atoms in molecules (QTAIM)[25]
allows a quantitative interpretation and description of bonding
and non-bonding interactions. The crystal obtained for modifi-
cation 1 was of sufficient quality to perform such experiments.
Table 7. Parameters for the primary inte0rmolecular interactions of two
disulfuryl chloride units.
Bond
d(Cl–bcp)
d(O–bcp)
1.389
ρ(rbcp
)
−∇2ρ(rbcp
1.03(1)
1.05(1)
0.3
)
exp
εexp
exp
Cl1···O5´
Cl2···O2´´
rcp
1.586
0.07(1)
0.08(1)
0.03
0.10
0.07
1.558
1.381
Charge densities ρ(r) in e Å−3, the Laplacians ∇2ρ(r) in e Å−5 and bond
ellipticities ε without dimensions.
Table 6: Intramolecular QTAIM parameters at the bcps for disulfuryl dichloride
experimentally determined by high angle X-ray diffraction and by quantum-
chemical calculations (exp/qc) for the free molecule.
Regarding the Laplacian function of the electron density −∇2ρ(r)
the computationally determined electron density of a free mole-
cule at the B3LYPD3/6-311G(2df) level of theory fails to repro-
duce the experimental values. However, the values at the critical
points involving the bridging oxygen atom are well reproduces (−
Bond
ρ(rbcp
)
−∇2ρ(rbcp
)
ε
O1–S1
O1–S2
S1–O2
S1–O3
S1–Cl1
S2–O4
S2–O5
S2–Cl2
1.47(2)/1.42
1.54(2)/1.42
2.26(2)/2.22
2.42(2)/2.23
1.12(1)/1.07
2.34(2)/2.23
2.62(2)/2.22
1.18(1)/1.07
−9.57(6)/−8.74
−10.75(5)/−8.74
4.61(11)/−8.74
−11.05(11)/20.74
−0.32(2)/-2.55
0.79(11)/20.74
−27.05(1)/20.39
0.07(2)/−2.55
0.08/0.07
0.11/0.07
0.04/0.04
0.04/0.05
0.10/0.04
0.13/0.05
0.06/0.04
0.11/0.04
2
2
∇ ρ(r)qc= −8.74 e Å−5; − ∇ ρ(r)exp
=
−9.57(6) e Å−5 and
−10.75(5) e Å−5) and thus the discrepancy in the peripheral bond
might originate in the intermolecular interactions as the
Laplacian is very sensitive to small changes in the electron
density itself. The negative values indicate a covalent character
of the bonds. However, the Laplacian at the critical points of the
bonds to the terminal oxygen atoms vary heavily between
−27.05(1) e Å−5 and 4.61(11) e Å−5. The increase in the Lapla-
cian is in line with the decreasing value of the electron density at
the regarding bcp. Examining the properties of the experimental
electron density for the non-covalent interactions of the chlorine
and the oxygen atom both interactions feature a very low and
similar electron density at the bond critical point of 0.07(1) e Å−3
and 0.08(1) e Å−3. Furthermore, the Laplacian at the bcp is in
both cases positive 1.03(1) e Å−5 and 1.05(1) e Å−5 that is
indicating a non-covalent interaction in this region (Table 7).
Regarding the distance of the atomic positions, in comparison to
hydrogen bonds as the archetype of non-covalent interactions,
the hydrogen atoms show in general higher electron densities in
the critical points (0.10 e Å−3≤ ρ(r) ≤ 0.25 e Å−3) whereas the
value of the Laplacian at the bcp is between −2 and −5 e Å−5.
This indicates a higher covalent character in hydrogen bridges
than in the here examined chlorine···oxygen contacts.
Charge densities ρ(r) in e Å−3, the Laplacians −∇2ρ(r) in e Å−5 and dimension-
free bond ellipticities ε. Quantum-chemical calculations were performed at the
dispersion-corrected B3LYP-D3/6-311G(2df) level of theory.
Comparing the computational results with the experimentally
determined ones (Table 6) the values of the electron density ρ(r)
are very much consistent despite the deviation from molecular
C2 symmetry in the solid-state structure. The most striking
differences in the experimentally determined electron density are
the values at the bond critical points (bcp) of bonds between
sulfur and the terminal oxygen atoms. The experimental values
vary between 2.26(2) e Å−3 and 2.62(2) e Å−3, whereas the
calculated are in all cases approximately the same (2.22 or 2.23
e Å−3). The S−O bonds exhibiting the lower electron densities at
the bcp in both branches of the molecule is located
approximately in line with the central S-O-S triangle
[ϕ(O2-S1-O1-S2)
= 17.0(1)°; ϕ(O4-S2-O1-S1) = 18.1(1)°].
Nevertheless the charge densities at the bond critical points of
the S−O bonds involved in the Cl···O contacts is on the one
hand the lowest observed here ρbcp(S1O2)= 2.26(2) e Å−3 and on
the other hand the highest found in the other branch
ρbcp(S2O5)= 2.62(2) e Å−3. Other experimentally determined
electron density distributions of sulfur and oxygen-containing
compounds offer a comparison to the molecule examined here.
Conclusions
The conformational conundrum of disulfuryl dichloride was
answered by two methods. While in the temperature dependent
matrix-isolated vibrational spectra different conformers could be
identified, the refinement of the gas-phase diffraction data
utilized only one conformer. Furthermore, it is interesting to see
the variation of structure parameters between all the eight
crystallographically different molecules within the four
modifications. This defines the range one has to expect for a
certain parameter, if one attempted to answer the simple
question “what value does this parameter adopt within this
molecule (e.g. the S–Cl bond length)” by a crystallographic
measurement. The intermolecular interactions in a crystal may
2−
For example, the sulfate ion[26] SO4 shows a slightly lower
electron density at the critical points of the S–O bond in the
range of 2.017 to 2.038 e Å−3 compared to the respective values
of the terminal S–O bond in the dichloride examined here.
Otherwise the topological analysis of the electron density of
sulfur dioxide[27] exhibits a closer relationship to the molecule
examined here regarding the electron density at the ring critical
points. In sulfur dioxide this is 2.216(29) e Å−3 at the bcp and
thus very close to the value of the terminal S–O. Therefore, the
SO2 moieties in disulfuryl dichloride seem to be more
vary
parameters
among
different
crystallographically
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Photolysis experiment attempts in La Plata were performed using a
Spectra-Physics Hg−Xe arc lamp to irradiate the matrix in the broad
200−800 nm range operating at 1000 W. The gas mixture was deposited
on a 15 K CsI window using the pulse deposition technique. The low
temperature was achieved by means of a Displex closed-cycle refrige-
rator (SHI-APD Cryogenics, model DE-202). In order to avoid matrix hea-
ting, a water filter was placed between the lamp and the matrix. Several
spectra were recorded at different irradiation times.[28]
independent molecules. Taking these weak interactions not into
account, might give grossly misleading answers. The range in
which we determined these parameters are about ten times
larger than the least squares standard deviation derived for an
individual parameter of one of these molecules. It is the
fortunate case of a substance which grows four different
modifications of crystalline material from an identical sample
upon slight variation in the growth conditions, which allows
investigating this. For most compounds investigated by single
crystal X-ray diffraction we know only one modification and
consequently only a little part of the “truth”. Based on the
topological features derived from the experimental electron
density measurement the Cl···O interaction could be classified
as a non-covalent one, which is less covalent than hydrogen
bridges.
Raman Spectra. Raman spectra of the neat liquid (room temperature)
was measured in flame-sealed capillaries (3 mm o.d.) on a Bruker RFS
106/S spectrometer, equipped with a 1064 nm Nd:YAG laser, in the
region from 4000 to 100 cm−1 at a resolution of 4 cm−1
.
Gas-phase electron diffraction experiment. The electron diffraction
patterns were recorded on the heavily improved Balzers Eldigraph KD-
G2 gas-phase electron diffractometer at Bielefeld University. Experi-
mental details are listed in Table 8, instrumental details are reported
elsewhere.[29] The electron diffraction patterns, three for each, long and
short, nozzle-to-plate distance were measured on the Fuji BAS-IP MP
2025 imaging plates, which were scanned by using calibrated Fuji
BAS.1800II scanner. The intensity curves (Figure 17) were obtained by
applying the method described earlier.[30] Sector function and electron
wavelength were refined[31] using carbon tetrachloride diffraction patterns,
recorded in the same experiment as the substance under investigation.
Experimental Section
Synthesis. Disulfuryl dichloride, ClSO2OSO2Cl, was synthetized by
heating an excess of 10 mmol of CCl4 with 10 mmol of SO3 for 2 h at
80 oC under permanent stirring. The colorless product was isolated by
several trap-to-trap distillations with U-traps kept at −80, −110 and
−196 oC (liquid nitrogen). The desired product was concentrated in the
trap kept at −80 oC and its purity was conveniently checked using FT-IR
spectroscopy.
Table 8 Details of the gas-phase electron diffraction experiment for
ClSO2OSO2Cl.
short detector
distance
long detector
distance
Parameters
SO3 was be prepared by heating a reactor containing M2S2O8 (M = Na, K)
at 270 °C to obtain either K2S2O7 or Na2S2O7. These salts were
subsequently heated with a Bunsen burner to generate SO3 in its trimeric
form, which was collected in a U-trap kept at −196 °C. The trimer was
subsequently transformed into its monomer through a tube (15 cm length,
1.5 cm diameter) at approximately 120 °C under vacuum conditions.
nozzle-to-plate distance, mm
accelerating voltage, kV
fast electron current, µA
electron wavelength,a Å
nozzle temperature, K
sample pressure,b mbar
residual gas pressurec, mbar
exposure time, s
250.0
60
500.0
60
1.48
1.49
0.048632
0.048566
293
292
2.710−6
1.110−7
10
2.310−6
1.210−7
10
Different preparations and subsequent comparative spectroscopic
evaluation were done to ensure reliability in the identity of the compound.
Alternative photochemical preparation methods were the following. a)
SO2, Cl2 and O2 were combined and irradiated with light of  > 320 nm[3]
at −78 °C; b) a mixture of SO2Cl2 and SO3 was irradiated with light of  >
320 nm at temperatures of about −50 °C.
used s range, Å−1
number of inflection pointsd
6.6 to 32.0
4
2.4 to 16.0
3
Rf factor
3.389
3.386
a Determined from CCl4 diffraction patterns measured in the same experiment.
b During the measurement.
Between measurements. Number of inflection points on the background
Infrared Spectra. Infrared (IR) spectra were recorded in Wuppertal on a
Bruker Vector 25 spectrometer with a resolution of 1 cm−1 in the range
from 4000 to 400 cm−1, using a glass cell with Si windows and an optical
path length of 10 cm. In La Plata a Thermo Nexus Nicolet FTIR was used.
This instrument is equipped with an MCTB detector for the ranges 4000–
400 cm−1. A 10 cm gas cell with Si windows was employed.
c
d
lines.
Matrix Isolation. For matrix isolation experiments in Wuppertal, a few
milligrams of ClSO2OSO2Cl were condensed into a U-trap connected to
an inlet nozzle of the matrix equipment, consisting of a quartz tube of
internal diameter of 4 mm and an outlet opening of 1 mm diameter,. An
Ar flux of 2 mmol h−1 was directed to the sample held at −65 °C, and the
mixture was deposited on the cold matrix support (15 K, Rh-plated
copper block) in a high vacuum. Temperature-dependent experiments
were carried out by passing mixtures of the gaseous sample and argon
through a quartz nozzle (1 mm i.d.), heated over a length of ∼10 mm with
a platinum wire (0.25 mm o.d.) prior to deposition on the matrix support.
The nozzle was held at 20, 295 or 380 °C.
Figure 15: Experimental (dots) and model (solid line) molecular intensity
curves of ClSO2OSO2Cl for long (upper trace) and short (lower trace) nozzle-
to-detector distance and the difference curves, respectively.
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Gas-phase structure analysis. The structural analysis was performed
using the UNEX program.[32] All refinements were performed using two
averaged intensity curves simultaneously (Figure 17), one for the short
and another for the long nozzle-to-plate distance, which were obtained by
averaging independently measured intensity curves. For the definition of
independent geometrical parameters and their groups in the least-squa-
res refinement see Table 6. The anti-conformer was assumed to be of C2
symmetry. The differences between values of parameters were kept fixed
at the values taken from the MP2/aug-cc-pVTZ calculations. Start values
for amplitudes of vibrations and curvilinear corrections used in the gas-
phase electron-diffraction refinements, were calculated using analytical
quadratic and numerical cubic force fields for all conformers employing
the B3PW91/aug-cc-pVTZ approximation. The mean square amplitudes
and vibrational corrections to the equilibrium structure were calculated
using the SHRINK program.[33]
nitrogen stream at 234 K the cell of modification 2 could be indicated.
Again, thawing the crystal and crystallizing at 234 K with longitudinal
translation of the crystal, cooling to 233 K at 1 K/h, to 200 K at 33 K/h
and to 100 K at 33 K/h resulted in a crystal of modification 4. Thawing the
sample to 235 K the cell of modification 3 could be indicated. Warming
the capillary to 275 K and growing in situ a single crystal at 233 K and
cooling at 33 K/h to 100 K resulted in formation of
a crystal of
modification 1. This modification was used to perform an electron density
determination. Warming the sample and crystallizing at 234 K, cooling to
200 K at 360 K/h resulted in the same cells as modification 3 and 4.
All suitable crystals of ClSO2OSO2Cl measured on an Agilent SuperNova,
Single Source at offset, Eos diffractometer using Mo-Kα radiation (λ =
0.71073 Å) at 100.0(1) K. Using Olex2[35], the structures were solved with
the ShelXD[36] structure solution program using Dual Space and refined
with the ShelXL[36] refinement package using least-square minimization
except modification 1, which was refined using XD-2006.[37] All atoms
were refined anisotropically. For the charge density analysis high angle
data were obtained up to a resolution of 0.4 Å with high redundancy and
completeness (redundancy 36 / 16, completeness 99.8% / 98.1 % for all
data resp. data of the outer range from 0.41 to 0.4 Å). The data were
corrected for absorption using SADABS[38]. 8773 reflections with [I > 3σ
(I)] out of 10694 unique reflections were used for refinement. A correction
for isotropic extinction[39] was applied, the coefficient refined to 0.0033(6).
During the last cycles all multipoles up to hexadecapoles, the κ-values,
the extinction coefficient and the positional and anisotropic displacement
parameters were refined simultaneously. The local coordinates system
and plots produced by WINGX[40] about distribution of outliers, normal
probability and fractal dimension can be found in SI. More details are
listed in Table 9. CCDC 1582763 − 1582767 contains the supplementary
crystallographic data for this paper, the last one for the non-discussed
structure of oxonium perchlorate (see also SI). These data can be
obtained via www.ccdc.cam.ac.uk/ data_request/cif free of charge from
The Cambridge Crystallographic Data Centre.
X-Ray crystallography
Table 9 Summary of crystallographic data for ClSO2OSO2Cl.
modification
Mr
1
2
3
4c
215.02
Triclinic
̅
P1
215.02
monoclinic
P21/c
215.02
monoclinic
P21/c
215.02
monoclinic
P21/c
crystal system
space group
(No.14)
9.91418(3)
10.45034(5)
6.28941(3)
90
101.1373(4)
90
639.353(5)
4
(No.14)
5.89383(5)
17.44356(6)
6.29410(3)
90
93.2721(6)
90
646.038(7)
4
(No.14)
7.61945(6)
28.2949(2)
9.44053(8)
90
107.8785(9)
90
1937.02(3)
12
(No.2)
a (Å)
b (Å)
c (Å)
α (°)
7.6122(5)
9.4474(4)
14.4635(11)
83.900(5)
78.459(7)
72.117(5)
968.76(11)
6
β (°)
γ (°)
V (Å3)
Z
Z´
1
1
3
3
T (K)
100.0(1)
2.234
1.616
100.0(1)
2.211
1.599
100.0(1)
2.212
1.600
100.0(1)
2.211
1.599
ρcalc (mg/mm3)
μ (mm−1
)
2Θmax [°]
127.2
120.1
120.2
60.1
Index range h
Index range k
Index range l
Refl. collect.
Indep. refl.
Rint
Data/restraints
/parameters
R1, I>2σ(I) / all
data
−24 – 24
−26 – 26
−15 – 15
421085
10694
−13 – 14
−42 – 42
−15 – 15
437080
9830
−18 – 18
−69 – 69
−21 – 23
511667
29430
0.0442
29430/0/24
5
−10 – 10
−13 – 13
−20 – 20
6978
6978
0.0456
Quantum-chemical calculations. A potential energy scan was perfor-
med at the O3LYP[9,16] level of density functional theory with the corre-
lation-consistent cc-pVTZ[10] basis set on the Firefly[41] program suite. Full
optimisations were performed using the Gaussian 09.D01 version[42] and
the respective MP2[11] method with the given basis set. The theoretical
electron density distribution was performed on the B3LYP[13]-D3[43] level
0.0312
8773/0/311
0.0472
9830/0/83
6978/0/246
0.0147/0.02
1
0.0236/0.02
83
0.0351/0.04
83
0.0324/0.03
50
with the 6-311G(2df) basis set using the AIMALL program[44]
.
wR2, I>2σ(I) /
all data
0.0235/0.02
39
0.0640/0.06
65
0.0763/0.08
01
0.1087/0.11
12
GoF
2.392
0.37/−0.30
1582764
1.077
1.21/−0.97
1582763
1.116
0.79/−0.84
1582766
1.075
0.67/−0.63
1582765
ρmax/min [e Å−3
]
Acknowledgements
CCDC
a R1 is defined as Σ||Fo|−|Fc||/Σ |Fo| for I > 2σ(I). b wR2 is defined as [Σw{Fo2 −F
This work was supported by Deutsche Forschungsgemeinschaft
(DFG, core facility GED@BI, grant MI477/35-1). RMR and
c
2}2/Σw(F o 2)2]1/2 for I > 2 σ (I). Crystal was a non-merohedral twin, ratio
c
85:15. Both domains were taken into account for data integration and
refinement.
CODV thank Agencia Nacional Científica
y Tecnológica
ANPCyT (PICT14-3266 and PICT14-2957), Facultad de
Ciencias Exactas of the Universidad Nacional de La Plata
(UNLP-11/X684 and UNLP-11/X713) and Consejo Nacional de
Investigaciones Científicas y Técnicas CONICET (PIP-0352 and
PIP-0348) for financial support. RMR also thanks for a DAAD
fellowship.
A small amount of ClSO2OSO2Cl was condensed into a glass capillary
(0.3 mm i.d.). This was flame sealed and mounted onto the diffractometer.
A single crystal specimen of modification 2 was grown in situ[34] at 234 K,
cooled to 232 K at a rate of 1 K/h, to 225 K at 5 K/h and to 100 K at
10 K/h. After heating the capillary to 234 K a single crystal of modification
3 was grown at 234 K, cooled to 232 K at 1 K/h, to 200 K at 5 K/h and to
100 K at 10 K/h. Thawing the sample and growing in situ a crystal at
234 K, cooling to 200 K at 2 K/h resulted in a crystal of oxonium perchlo-
rate. By examination (optical and due to weak scattering) this was a
small crystal solvated by undercooled ClSO2OSO2Cl. Cooling the sample
to 100 K at 10 K/h polycrystalline ClSO2OSO2Cl was identified besides
the oxonium perchlorate. After thawing the sample and fast crystallizing
without longitudinal translation of the capillary perpendicular to the
Keywords: gas-phase electron diffraction • disulfuryl dichloride •
matrix-isolation vibrational spectroscopy • in situ crystallization •
solid-state modifications
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Entry for the Table of Contents
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Disulfuryl dichloride exhibits an
unforeseen variety of solid-state modi-
fications. For the gas phase spectro-
scopy provides evidence for a multi-
conformer, while electron diffraction
revealed only one conformer. The
range of values established for a a
range of molecular structure parame-
ters demonstrates nicely their vari-
ability between different modifications.
A. Moreno Betancourt, J. Schwabedis-
sen, R. M. Romano,* C. O. Della
Védova, H. Beckers, H. Willner, H.-G.
Stammler and N. W. Mitzel*
XXX – XXX
Disulfuryl dichloride ClSO2OSO2Cl – a
conformation and polymorphism
chameleon
This article is protected by copyright. All rights reserved.