Para-Benzene disulfonic acid and its tetrachloro and tetrafluoro derivatives - Studies towards polyhalogenated metal-organic-frameworks with sulfo analogues of terephthalic acid

Article abstract of DOI:10.1039/c0dt01223h

We developed convenient synthetic routes for the preparation of para-benzene disulfonic acid (H₂BDS) and its tetrachloro (H ₂BDSCl₄) and tetrafluoro (H₂BDSF₄) derivatives. The reaction of these acids with zinc nitrate in DMF led to single crystals of [Zn(BDS)(DMF)₂] (triclinic, P1, Z = 2, a = 976.62(4), b = 986.85(4), c = 1014.40(4), α = 69.106(2)°, β = 68.746(2)°, γ = 86.295(2)°, wR₂ = 0.0627), [Zn(BDSCl ₄)(DMF)₄] (triclinic, P1, Z = 1, a = 831.5(1), b = 905.2(1), c = 989.6(1), α = 90.44(2)°, β = 91.41 (2)°, γ = 106.72(2)°, wR₂ = 0.0635), and [Zn(BDSF ₄)(DMF)₄] (monoclinic, P2₁/c, Z = 2, a = 889.01(3), b = 968.91(3), c = 1633.07(5) pm, β = 106.524(2)°, wR ₂ = 0.0948). While [Zn(BDS)(DMF)₂] exhibits a layer structure, the disulfonate linkers connect the zinc ions into chains in the crystal structures of [Zn(BDSCl₄)(DMF)₄] and [Zn(BDSF ₄)(DMF)₄]. Thermoanalytical investigations revealed that desolvation of the compounds occurs in a temperature range between 100 and 200 °C. The solvent free sulfonates show remarkably high stabilities, [Zn(BDS)(DMF)₂] is stable up to nearly 600 °C. The halogenated acids were also used to prepare copper salts from aqueous solutions and Cu ₂(OH)₂(CO₃) (malachite) as a copper source. The crystal structure of [Cu(H₂O)₆](BDSF₄) (triclinic, P1, Z = 1, a = 510.45(2), b = 744.68(3), c = 1077.77(4) pm, α = 85.627 (2)°, β = 77.449 (2)°, γ = 76.015 (2)°) exhibits complex cations and uncoordinated sulfonate anions, while in [Cu(BDSCl ₄)(H₂O)₄] (orthorhombic, Pnma, Z = 4, a = 721.27(2), b = 2147.81(6), c = 979.42(3) pm) the Cu²⁺ ions are linked to infinite chains in the crystal structure. The most interesting structural feature of [Cu(BDSCl₄)(H₂O)₄] is the significant deviation from planarity of the disulfonate dianion. Theoretical investigations revealed that a boat conformation is favoured due to steric hindrance in cases where a syn coordination of the sulfonate groups occurs. The thermal behaviour of the copper compounds was also investigated by DTA/TG measurements and X-ray powder diffraction.

Full text of DOI:10.1039/c0dt01223h

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PAPER
para-Benzene disulfonic acid and its tetrachloro and tetrafluoro
derivatives—studies towards polyhalogenated metal–organic-frameworks with
sulfo analogues of terephthalic acid†
Thomas W. T. Muesmann, Christina Zitzer, Andrea Mietrach, Thorsten Klu¨ner, Jens Christoffers* and
Mathias S. Wickleder*
Received 13th September 2010, Accepted 1st December 2010
DOI: 10.1039/c0dt01223h
We developed convenient synthetic routes for the preparation of para-benzene disulfonic acid (H2BDS)
and its tetrachloro (H2BDSCl4) and tetrafluoro (H2BDSF4) derivatives. The reaction of these acids with
¯
zinc nitrate in DMF led to single crystals of [Zn(BDS)(DMF)2] (triclinic, P1, Z = 2, a = 976.62(4), b =
986.85(4), c = 1014.40(4), a = 69.106(2)◦, b = 68.746(2)◦, g = 86.295(2)◦, wR2 = 0.0627),
◦
¯
[Zn(BDSCl4)(DMF)4] (triclinic, P1, Z = 1, a = 831.5(1), b = 905.2(1), c = 989.6(1), a = 90.44(2) , b =
91.41 (2)◦, g = 106.72(2)◦, wR2 = 0.0635), and [Zn(BDSF4)(DMF)4] (monoclinic, P21/c, Z = 2, a =
889.01(3), b = 968.91(3), c = 1633.07(5) pm, b = 106.524(2)◦, wR2 = 0.0948). While [Zn(BDS)(DMF)2]
exhibits a layer structure, the disulfonate linkers connect the zinc ions into chains in the crystal
structures of [Zn(BDSCl4)(DMF)4] and [Zn(BDSF4)(DMF)4]. Thermoanalytical investigations
revealed that desolvation of the compounds occurs in a temperature range between 100 and
200 ◦C. The solvent free sulfonates show remarkably high stabilities, [Zn(BDS)(DMF)2] is stable up to
nearly 600 ◦C. The halogenated acids were also used to prepare copper salts from aqueous solutions
and Cu2(OH)2(CO3) (malachite) as a copper source. The crystal structure of [Cu(H2O)6](BDSF4)
◦
◦
¯
(triclinic, P1, Z = 1, a = 510.45(2), b = 744.68(3), c = 1077.77(4) pm, a = 85.627 (2) , b = 77.449 (2) ,
g = 76.015 (2)◦) exhibits complex cations and uncoordinated sulfonate anions, while in
[Cu(BDSCl4)(H2O)4] (orthorhombic, Pnma, Z = 4, a = 721.27(2), b = 2147.81(6), c = 979.42(3) pm) the
Cu2+ ions are linked to infinite chains in the crystal structure. The most interesting structural feature of
[Cu(BDSCl4)(H2O)4] is the significant deviation from planarity of the disulfonate dianion. Theoretical
investigations revealed that a boat conformation is favoured due to steric hindrance in cases where a syn
coordination of the sulfonate groups occurs. The thermal behaviour of the copper compounds was also
investigated by DTA/TG measurements and X-ray powder diffraction.
properties of sulfonate groups compared to those of carboxylate
Introduction
groups, and on the other hand from the higher thermal stability
of sulfonates compared to carboxylates. Especially the latter point
is of utmost importance with respect to the application of such
compounds. For example, copper(II) terephthalate decomposes
Materials with open framework structures consisting of metal
centers as knots and organic linkers (so called metal–organic-
frameworks) have entered the focus of interest due to their
broad range of promising chemical and physical properties.1
Carboxylates define a privileged class of anions used as linkers
in MOFs, because they are readily available in a great variety at
relatively low costs. The respective sulfo analogues of these acids
are scarcely explored, even if their potential to act as suitable
linkers for building MOFs has been mentioned occasionally.2
This potential arises on one hand from the different coordination
◦
between 160–230 C,3 whereas copper(II) 1,4-benzenedisulfonate
is stable up to 400 ◦C.4 The main reason for our poor knowledge
of polysulfonates as linkers is the limited availability of the
respective acids. In particular, the analogues of those carboxylic
acids that have been used with great success so far, e.g. terephthalic
acid (1), trimesic acid (2), and pyromellitic acid (3), have no
convenient routes for their multigram preparation starting from
cheap materials (see Scheme 1 for structures). Providing effective
syntheses as a key issue for the implementation of polysulfonate
linkers in MOF chemistry was the driving force for us to initiate
a research program on new oligosulfonic acids. In the course
of these studies we have already developed scalable synthetic
routes to 1,4-benzene disulfonic acid (4, H2BDS),4 1,3,5-benzene
Institut fu¨r Reine und Angewandte Chemie, Carl von Ossietzky-Universita¨t
Oldenburg, D-26111, Oldenburg, Germany. E-mail: mathias.wickleder@
uni-oldenburg.de; Fax: +49 441 798 3873
† CCDC reference numbers 763637, 763638, 763639, 776934, 776935,
777578. For crystallographic data in CIF or other electronic format see
DOI: 10.1039/c0dt01223h
3128 | Dalton Trans., 2011, 40, 3128–3141
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in MOFs. In particular, perfluorination might lead to enhanced
hydrogen adsorption properties due to hydrophobation of internal
surfaces of such frameworks.6a
Results
Organic Syntheses
Perfluorinated disulfonic acid H2BDSF4 (7) has previously been
reported by Sartori and coworkers, who developed a three
step synthesis from pentafluorobenzene, which was first mono-
sulfonated in liquid SO3.8 The next step was a regioselective nucle-
ophilic substitution with KHS. Finally, oxidation was achieved
with chlorine in the presence of peracetic acid. In order to
avoid operations with SO3 and Cl2, we were seeking for a
preparative alternative for the introduction of sulfur groups at
an aromatic ring. One generally useful reaction could be the
intramolecular nucleophilic displacement of an C–O by an C–
S bond in an aryl-thiocarbamate (so called Newman–Kwart9 or
Scho¨nberg-rearrangement),10 which would transform a phenol-
into a thiophenol-derivative. Commercially available tetrafluoro-
hydroquinone 9 was therefore esterified with an excess of thiocar-
bamoylchloride to yield the O-diester 10, which was isolated in
73% yield after chromatography (Scheme 2). The rearrangement
reaction proceeded in Ph2O at 200 ◦C with 61% yield after chro-
matography of S-diester 11. Actually, saponification of compound
11 can be achieved, but gave tetrafluorobenzenedithiol only with
low yield (25%) and insufficient purity. However, thiocarbamate
11 can be oxidatively degraded with NCS in hydrochloric acid11
to give the bis-sulfonylchloride 12. Since the final product 7 was
difficult to purify, we took care on the purification of dichloride
12, which was first chromatographed and then recrystallized.
The yield of product 12 looks therefore low (33%), although the
conversion of 11 was quantitative. Finally, hydrolysis of compound
Scheme
metal–organic-frameworks.
1
Carboxylic and sulfonic acids as linker molecules for
trisulfonic acid (5, H3BTS),4 and 1,2,4,5-benzene tetrasulfonic acid
(6, H4B4S)5 as sulfo-analogues of terephthalic (1), trimesic (2),
and pyromellitic acid (3). We furthermore were able to isolate and
structurally characterize the copper(II) salts of all three sulfonic
acids 4–6. The most important result of these studies was—
as already mentioned above—the increased thermal stability of
such compounds compared to copper(II) carboxylates. We now
report on the extension of our efforts by developing synthetic
routes to the tetrafluoro- (7, H2BDSF4) and tetrachloro-derivatives
(8, H2BDSCl4) of 1,4-benzene disulfonic acid (4). This study
was clearly inspired by recent investigations of other groups on
tetrafluoro-6 and tetrachloroterephthalates7 as linker molecules
Scheme 2 Synthesis of perfluorinated disulfonic acid H2BDSF4 (7). Reagents and conditions: (a) 1. 4 eq. DABCO, 3 eq. Me2NCSCl, DMF, 0.5 h, 35 ◦C;
2. 2 h, 80 ◦C; 3. SiO2; (b) 1. Ph2O, 1 h, 200 ◦C; 2. SiO2; (c) 8 eq. NCS, HCl–H2O, MeCN, 1.5 h, 10–15 ◦C; 2. SiO2; 3. crystallization; (d) H2O, 16 h, 100 ◦C.
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12 with boiling water gave final product 7, which was isolated
after evaporation of all volatile materials as the dihydrate and in
quantitative yield.
Crystal structures
In the crystal structure of [Zn(BDS)(DMF)2] the two crystallo-
graphically independent zinc ions, Zn1 and Zn2, are located at the
Our synthesis of the perchlorodisulfonic acid 8 started with
tetrachlorobenzene 13, the nitration of which required rather
harsh conditions. Instead of handling concentrated nitric acid, we
generated it in situ from NaNO3 and boiling oleum12 (Scheme 3).
Nucleophilic displacement reactions of either one13 or both nitro
groups14 in this product 14 with Na2SO3 has been reported previ-
ously to proceed smoothly. In our hands, quantitative conversion
of compound 14 with Na2SO3 was achieved in 1,4-dioxane–H2O at
100 ◦C and the disodium salt 15 was obtained in good yield, which
was finally protonated in aqueous solution with a column of acidic
ion exchange resin. After evaporation of all volatile materials, the
free acid 8 was obtained as the trihydrate.
Wyckoff sites 1h (12 ;
;
12 , site symmetry -1) and 1e (21 ; 12 ; 0, site
1
2
¯
symmetry -1) of space group P1. Both ions are nearly undistorted
octahedrally coordinated by oxygen atoms. The oxygen atoms
belong to four monodentate disulfonate groups and two DMF
molecules and the distances Zn–O range from 204 to 211 pm
(Zn1) and 206 to 212 pm (Zn2), respectively. The centroids of
the two sulfonate groups are also located at special sites of
the triclinic cell (Wyckoff positions 1c and 1g) leading to -1
symmetry for the anions in this structure. The Zn2+ ions are
linked to infinite corrugated layers by the anions according to the
formulation 2•[Zn(BDS)4/4(DMF)2/1] (Fig. 1). Two oxygen atoms of
each [SO3] group are involved in the linkage, while the remaining
oxygen atoms are non-coordinating. Nevertheless, the distances
S–O show only slight differences with respect to each other and
show typical values between 145 and 147 pm. The coordination
spheres of the Zn2+ ions are completed by two DMF molecules
which are attached via their oxygen atoms. The intramolecular
bond distances and angles are in good agreement with previous
2
•
findings for DMF complexes. The [Zn(BDS)4/4(DMF)2/1] layers
are stacked in the [010] direction of the unit cell. The layers are
held together by weak hydrogen bonds with the CH3 groups of the
solvent molecules as donors and non-coordinating oxygen atoms
of the sulfonate groups as acceptors (Fig. 2). Such weak hydrogen
bonds have been generally accepted since the 1980s to influence
the structure of organic compounds in the solid state.15
The zinc salts of the tetrahalogen derivatives H2BDSF4 (7) and
H2BDSCl4 (8) crystallize with four DMF molecules. The higher
content of solvent molecules leads to a reduced connectivity
of the anions and only one-dimensional linkage is observed.
[Zn(BDSCl4)(DMF)4] crystallizes with triclinic symmetry and
1
2
1
2
contains the Zn2+ ions (Wyckoff position 1h,
;
;
12 ) with an
octahedral surrounding of oxygen atoms originating from two
Scheme 3 Synthesis of perchlorinated disulfonic acid H2BDSCl4 (8).
Reagents and conditions: (a) 6 eq. NaNO2, 24 eq. H2SO4 with 65% SO3,
14 h, 130 ◦C; (b) 5 eq. Na2SO3, H2O–1,4-dioxane, 6 h, 100 ◦C; (c) acidic
Amberlyst 15, H2O.
2-
monodentate BDSCl4
anions and four DMF molecules.
The distances Zn–O are comparable to those found for
[Zn(BDS)(DMF)2] (207–212 pm). Also in the crystal structure
Fig. 1 Linkage of Zn2+ and para-benzenedisulfonate ions to infinite layers in the crystal structure of [Zn(BDS)(DMF)2] (DMF molecules omitted for
clarity).
3130 | Dalton Trans., 2011, 40, 3128–3141
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Fig. 2 Stacking of the layers shown in Fig. 1. Connection of the layers occurs by weak hydrogen bonds (dashed lines) involving DMF molecules and
sulfonate groups.
of [Zn(BDSCl4)(DMF)4] the anions show inversion symmetry
The distances Cu–O are 195, 198, and 239 pm, indicating the
typical Jahn–Teller distortion. The centroid of the completely
planar BDSF42- dianion is also located at a position with inversion
symmetry (1f , 12 ; 0; 12 ). The observed distances within the anion
are comparable to those described for [Zn(BDSF4)(DMF)4] (cf.
Table 4). Between the water molecules of the complex cations and
the oxygenatoms ofthe anions medium strong hydrogen bonds can
be assumed with respect to the observed donor–acceptor distances.
Also some fluorine atoms may contribute to the hydrogen bonds
(Table 5).15
1
(centroid at Wyckoff position 1e,
;
12 ; 0). While the bond
2
distances and angles within the [SO3] entity are pretty much
the same as found in [Zn(BDS)(DMF)2], the distance S–C is
remarkably enlarged (183 vs. 177 pm) which might be attributed
to the inductive effect of the chlorine substituents. The linkage
of Zn2+ ions and BDSCl4 anions leads to chains according
2-
to 1 [Zn(BDSCl4)2/2(DMF)4/1] that are oriented along the [001]
•
direction (Fig. 3) and connected by weak hydrogen bonds (cf.
Table 5).
The structural characteristics of [Zn(BDSF4)(DMF)4] are nearly
the same as described for the chlorine derivative, although the
symmetry is found to be monoclinic here (space group P21/c). The
two lattices are strongly related with the c axis being doubled in the
fluorine compound (cf. Table 1). The connectivity can be described
accordingly as •1 [Zn(BDSF4)2/2(DMF)4/1] (Fig. 4). Again the Zn2+
ions and the anions are situated on positions bearing inversion
In contrast to the findings for [Cu(H2O)6](BDSF4), the or-
thorhombic crystal structure of [Cu(BDSCl4)(H2O)4] exhibits a
one-dimensional structure with the Cu2+ ions linked by BDSCl4
2-
ligands according to •1 [Cu(BDSCl4)2/2(H2O)4/1] (Fig. 6). The coor-
dination sphere of the copper ions, which are located on the special
sites 4a (0; 0; 0, site symmetry -1), is completed by four water
molecules and the coordination polyhedron is again Jahn–Teller
distorted. The water molecules show distances of 194 and 196 pm,
respectively. The distances Cu–O to the oxygen atoms of the
sulfonate ligands are 244 pm. The two coordinating oxgen atoms
are in relative syn-conformation at the benzene ring. The chains
1•[Cu(BDSCl4)2/2(H2O)4/1] are zigzag shaped and running along the
[001] direction of the unit cell. Connection between the chains is
achieved by hydrogen bonds which involve the water molecules as
donors and both non-coordinating oxygen atoms of the sulfonate
groups and even chlorine atoms of the substituted benzene ring as
acceptors. The latter type of hydrogen bonds has been described in
some cases and the observed donor–acceptor distances hint at only
weak interactions (Table 5).16 The orientation of the infinite chains
with respect to each other leads to a stacking of hydrophobic
and hydrophilic domains along the [010] direction (cf. Fig. 6).
2-
symmetry (2b and 2d, respectively). For the BDSF4 anion there
is also a longer bond S–C observed (180 pm) when compared to the
unsubstituted anion. The differences between the crystal structures
of [Zn(BDSCl4)(DMF)4] and [Zn(BDSF4)(DMF)4] might arise
from the different size of the chloro and fluoro substituents as
indicated by the strongly different distances C–X (X = Cl: 172 pm,
X = F: 134 pm). In order to emphasize the structural similarities
of [Zn(BDSF4)(DMF)4] and [Zn(BDSCl4)(DMF)4] the latter was
¯
described in an unconventional setting of space group P1 in
Table 1. Table 3 compares the imported structural parameters
of the zinc sulfonates.
In the triclinic crystal structure of [Cu(H2O)6](BDSF4) the Cu2+
ions are located at the Wyckoff position 1e (12 ; 21 ; 0) and coordinated
by three crystallographically different water molecules (Fig. 5).
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Fig. 3 Crystal structure [Zn(BDSCl4)(DMF)4]. The BDSCl4 anions connect the Zn2+ ions to chains that are held together by hydrogen bonds.
2-
Fig. 4 Arrangement of the chains •1 [Zn(BDSF4)2/2(DMF)4/1] in the crystal structure of [Zn(BDSF4)(DMF)4].
3132 | Dalton Trans., 2011, 40, 3128–3141 This journal is The Royal Society of Chemistry 2011
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Table 1 Crystallographic data of [Zn(BDS)(DMF)2], [Zn(BDSCl4)(DMF)4], and [Zn(BDSF4)(DMF)4] and their determination
[Zn(BDS)(DMF)2]
[Zn(BDSCl4)(DMF)4]
[Zn(BDSF4)(DMF)4]
chemical formula
chemical formula weight
lattice parameters
C12H18N2O8S2Zn
447.77
C18H28Cl4N4O10S2Zn
731.73
C18H28F4N4O10S2Zn
665.93
a = 889.01(3) pm
b = 968.91(3) pm
c = 1633.07(5) pm
a = 976.62(4) pm
b = 986.85(4) pm
c = 1014.40(4) pm
a = 69.106◦(2)
b = 68.746◦(2)
g = 86.295◦(2)
a = 905.2(1) pm
b = 989.6(1) pm
c = 831.5(1) pm
a = 91.41◦(2)
b = 106.72◦(2)
g = 90.44◦(2)
b = 106.524◦(2)
density (calculated, g cm-3)
cell volume
1.752
848.89(6) A
1.704
713.0(2) A
1.731
1348.58(7) A
3
3
3
˚
˚
˚
no. of formula units
cryst. syst.
space group
measuring device
radiation
2
1
2
triclinic
P1 (No. 2)
Bruker APEX II
triclinic
P1 (No. 2)
monoclinic
P21/c (No. 14)
Bruker APEX II
Mo-Ka (graphite
¯
¯
Stoe IPDS I
Mo-Ka (graphite
monochromatized, l = 71.07 pm)
153 K
Mo-Ka (graphite
monochromatized, l = 71.07 pm)
monochromatized, l = 71.07 pm)
temperature
q range
rotation angle, j-increment
index range
153 K
153 K
4.62◦ < 2q < 70◦
5.86◦ < 2q < 56.56◦
0.0◦ < j < 320◦; 2.0◦
-12 £ h £ 12
-13 £ k £ 13
-11 £ l £ 11
4.94◦ < 2q < 70.38◦
—
—
-15 £ h £ 14
-14 £ h £ 14
-15 £ k £ 15
-8 £ k £ 15
-16 £ l £ 16
-24 £ l £ 26
no. of exposures
exposure time
—
—
160
1.5 min
—
—
detector distance
absorption correction
m
—
60 mm
—
numerical
numerical
numerical
17.37 cm-1
14.40 cm-1
20.17 cm-1
measured reflections
unique reflections
with I0 > 2s(I0)
30921
7458
4895
11246
3226
2699
25846
5836
3269
R
int; Rs
0.0389; 0.0351
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
0.873
0.0428; 0.0329
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
0.995
0.0616; 0.0984
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
0.880
structure determination
scattering factors
GOF
R1; wR2 (I0 > 2s(I0))
R1; wR2 (all data)
max./min. electron density
CCDC number
0.0233; 0.0582
0.0423; 0.0627
0.635/-0.474 e A
763637
0.0252; 0.0628
0.0317; 0.0647
0.460/-0.462 e A
763638
0.0348; 0.0679
0.0884; 0.0948
0.499/-0.803 e A
763639
-3
-3
-3
˚
˚
˚
Fig. 5 Crystal structure of [Cu(H2O)6](BDSF4) with complex [Cu(H2O)6]2+ cations and non-coordinating sulfonate anions.
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Table 2 Crystallographic data of [Cu(H2O)6](BDSF4), [Cu(BDSCl4)(H2O)4], and Na2BDSCl4·2H2O and their determination
[Cu(H2O)6](BDSF4)
[Cu(BDSCl4)(H2O)4]
Na2BDSCl4·2H2O
chemical formula
chemical formula weight
lattice parameters
C6H12CuF4O12S2
479.82
C6H8Cl4CuO10S2
509.58
a = 721.27(2) pm
b = 2147.81(6) pm
c = 979.42(3) pm
C6H4Cl4Na2O8S2
455.68
a = 1156.7(2) pm
b = 558.47(5) pm
c = 1072.3(2) pm
a = 510.45(2) pm
b = 744.68(3) pm
c = 1077.77(4) pm
a = 85.627(2)◦
b = 77.449(2)◦
g = 76.015(2)◦
b = 91.49(2)◦
density (calculated) [g cm-3]
cell volume
2.054
387.92(3) A
2.231
1517.27(8) A
2.187
692.5(2) A
3
3
3
˚
˚
˚
no. of formula units
cryst. syst.
space group
measuring device
radiation
1
4
4
triclinic
P1 (No. 2)
orthorhombic
Pnma (No. 62)
Bruker APEX II
Mo-Ka (graphite
monochromatized, l = 71.07 pm)
153 K
monoclinic
P21/c
STOE IPDS I
Mo-Ka (graphite
¯
Bruker APEX II
Mo-Ka (graphite
monochromatized, l = 71.07 pm)
153 K
monochromatized, l = 71.07 pm)
153 K
temperature
q range
rotation angle, j-increment
index range
5.64◦ < 2q < 80.60◦
—
7.02◦ < 2q < 70.14◦
—
7.04◦ < 2q < 56.56◦
0.0◦ < j < 300◦; 2.0
-15 £ l £ 15
-9 £ l £ 9
-9 £ l £ 11
-12 £ l £ 13
-34 £ l £ 34
-15 £ l £ 15
numerical
-6 £ l £ 6
-19 £ l £ 19
-14 £ l £ 14
absorption correction
m
numerical
numerical
17.83 cm-1
24.66 cm-1
12.56 cm-1
measured reflections
unique reflections
with I0 > 2s(I0)
20526
4896
4069
26926
3403
3046
9049
1588
1389
0.0234
R
int; Rs
0.0362; 0.0276
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
1.059
0.0244; 0.0140
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
1.032
structure determination
scattering factors
GOF
SHELXS97 and SHELXL97
Intern. Tables, Vol. C
1.018
R1; wR2 (I0 > 2s(I0))
R1; wR2 (all data)
max./min. electron density
CCDC number
0.0265; 0.0746
0.0336; 0.0770
1.166/-0.815 e A
777578
0.0266; 0.0707
0.0308; 0.0736
2.004/-1.370 e A
776934
0.0195/0.0511
0.0234/0.0523
0.418/-0.257 e A
776935
-3
-3
-3
˚
˚
˚
The most remarkable structural feature of [Cu(BDSCl4)(H2O)4]
is however the non-planarity of the benzene ring, which adopts
a boat conformation (Fig. 7a). Neither the chlorine atoms nor
the carbon atoms in the 1- and 4-position of the ring (as well
as the sulfur atoms of the sulfonate groups) are within the plane
defined by the four remaining carbon atoms of the benzene ring.
The deviation from the plane is 8.5◦ (distance from the plane:
29.7 pm) for the carbon atoms, and 9◦ (23.7 and 24.4 pm) the
chlorine atoms. Small distortion from planarity is a very seldom
seen effect for benzene derivatives.17 However, it is the general case
for benzene rings with multiple donor and acceptor substituents.18
In order to elucidate, whether this is an intrinsic effect of the
between both sulfur atoms, while their arrangement is staggered
in the case of the sodium compound (Fig. 9). A deeper insight
into the non-planarity phenomenon of the BDSCl4 anion in the
copper compound was achieved by ab intio calculations reported
in the next subsection.
2-
Computational results
Calculations were performed for H2BDSF4, H2BDSCl4, and the
anion BDSCl42-. Furthermore, the tetrabromo and tetraiodo
derivatives H2BDSBr4 and H2BDSI4 were included for compar-
ison. First of all, a full geometry optimization of H2BDSF4 did
not reveal any significant distortion of the planar ring geometry.
By starting from the experimental value of the out-of-plane angle
for H2BDSCl4, the final H2BDSF4 geometry resulted in a deviation
of the plane of only 0.8◦. This is in agreement with experiment and
in contrast to the corresponding calculations of H2BDSCl4. Here,
a pronounced boat geometry is found for the syn conformation
where the OH-moieties of sulfonate groups are located on the
same side of the aromatic ring. Starting from a planar initial
geometry, the out-of-plane angle was found to be 6.7◦. However,
this structure was found to be a local minimum only. In the anti
conformation the OH-moieties of the sulfonate groups are located
on different sides of the aromatic ring which results in a slightly
more stable conformation, although the energetic difference of
0.03 eV is very small. In this conformation the out of plane angle
2-
BDSCl4 anion, we investigated single crystals of the disodium
salt Na2BDSCl4·2H2O (Table 2). In the monoclinic structure the
anions are located of the Wyckoff position 2c (0; 0; 12 ) and
stacked along the [001] axis of the unit cell. Charge balance
is achieved by Na+ ions that are five-fold coordinated by three
oxygen atoms of sulfonate groups and two H2O molecules (Fig. 8).
Interestingly in this compound the benzene ring is completely
planar (Fig. 7b), so that a steric effect within the aromatic ring
can be ruled out as the mechanism for non-planarity of the anion
in [Cu(BDSCl4)(OH2)4]. The main difference between the anions
in the two crystal structures is the orientation of the sulfo groups
with respect to the benzene ring. In the copper compound they
are in a relative syn conformation, i.e. the sulfonate oxygen atoms
are arranged ecliptic when viewed along a virtual connecting line
3134 | Dalton Trans., 2011, 40, 3128–3141
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Table 3 Selected distances (pm) and angles (deg.) for the zinc compounds
[Zn(BDS)(DMF)2] [Zn(BDSCl4)(DMF)4]
[Zn(BDSF4)(DMF)4]
[ZnO6] Zn1
-O1
-O11
-O21
204.06(7)
211.87(7)
211.46(7)
Zn1
-O1
-O2
205.7(1)
211.3(1)
Zn1 -O1
-O2
207.2(1)
209.2(1)
-O11 211.2(1)
-O11 211.5(1)
Zn2
-O2
-O12
-O22
206.39(7)
211.92(7)
208.49(7)
O1-
O1-
O21-
Zn1
Zn1
Zn1
-O11
-O21
-O11
86.05(3)
87.71(3)
89.37(3)
O1-
O1-
O2-
Zn1
Zn1
Zn1
-O2
-O11
-O11
89.77(5)
89.04(5)
88.31(5)
O1-
O1-
O2-
Zn1
Zn1
Zn1
-O2
-O11
-O11
89.79(5)
86.95(5)
89.54(5)
O2-
O2-
O22-
Zn2
Zn2
Zn2
-O12
-O22
-O12
87.69(3)
85.15(3)
89.01(3)
[SO3]
S1
-O11
-O12
-O13
-C11
145.41(8)
147.07(7)
144.64(8)
177.1(1)
S1
-O11 146.3(1)
-O12 143.8(1)
-O13 144.4(1)
-C11 182.8(2)
S1
-O11 145.9(1)
-O12 144.3(1)
-O13 143.5(1)
-C11 180.5(2)
S2
-O21
-O22
-O23
-C21
146.56(7)
145.84(8)
144.82(8)
177.1(1)
O11-
O11-
O12-
O11-
O12-
O13-
S1
S1
S1
S1
S1
S1
-O12
-O13
-O13
-C11
-C11
-C11
112.53(5)
114.20(5)
111.38(5)
105.53(5)
106.43(4)
106.05(5)
O11- S1
O11- S1
O12- S1
O11- S1
O12- S1
O13- S1
-O12
-O13
-O13
-C11
-C11
-C11
112.49(8)
111.89(7)
115.12(8)
104.44(7)
108.48(7)
103.36(7)
O11- S1
O11- S1
O12- S1
O11- S1
O12- S1
O13- S1
-O12
-O13
-O13
-C11
-C11
-C11
111.68(8)
114.14(8)
115.19(9)
103.98(8)
104.15(8)
106.35(8)
O21-
O21-
O22-
O21-
O22-
O23-
O11-
S2
S2
S2
S2
S2
S2
S1
-O22
-O23
-O23
-C21
-C21
-C21
-O12
112.43(5)
111.96(5)
114.00(5)
106.56(4)
104.62(5)
106.51(5)
112.53(5)
Table 4 Selected distances (pm) and angles (deg.) for the copper
compounds
is found only for the Cu(II)-salt, in which coordination also occurs
on the same side of the ring. In the sodium salt, BDSCl4 can be
2-
regarded as a “free” dianionic species, in which syn coordination
[Cu(H2O)6](BDSF4)
[CuO6] Cu1 -O1
[Cu(BDSCl4)(H2O)4]
197.68(8) Cu1 -O1
does not occur, resulting in a planar aromatic system. This is
194.0(1)
195.8(1)
244.8(1)
2-
-O2
-O3
237.86(9)
194.58(8)
-O2
-O11
corroborated by our geometry optimization of free BDSCl4 in
which a planar conformation is obtained.
As far as the origin of a local minimum of syn H2BDSCl4 is
concerned, steric effects play a significant role. We substituted –
Cl by –Br and –I and found even larger out-of-plane angles of
12.6◦ and 17.5◦, respectively. A steric mechanism seems further
conclusive since the substitution of both sulfonate groups by tert-
butyl moieties rules out electronic effects and results in an out-of-
plane angle of 18.6◦.
O1- Cu1 -O2 87.01(3) O1- Cu1 -O2 88.30(4)
O1- Cu1 -O3 86.48(3) O1- Cu1 -O11 88.84(4)
O2- Cu1 -O3 86.41(3) O2- Cu1 -O11 88.50(4)
[SO3] S1
-O11
-O12
-O13
-C11
144.00(8) S1
146.20(8)
145.40(8)
178.7(1)
-O11
-O12
-O13
-C11
144.3(1)
146.3(1)
146.2(1)
180.9(2)
O11- S1
-O12 113.31(5) O11- S1
-O13 113.52(5) O11- S1
-O13 112.50(5) O12- S1
-C11 106.12(5) O11- S1
-C11 104.15(4) O12- S1
-C11 106.30(5) O13- S1
-O12 115.04(6)
-O13 111.91(6)
-O13 111.43(6)
-C11 106.34(6)
-C11 104.95(6)
-C11 106.40(6)
Thermal analysis
O11- S1
O12- S1
O11- S1
O12- S1
O13- S1
The desolvation of [Zn(BDS)(DMF)2] takes place in the tempera-
ture range between 55 and 210 ◦C and three steps can be identified
in the DTG curve (Fig. 10). The desolvation is complete according
to the observed mass loss of 34.7% (calcd. 32.6%). The solvent-free
compound [Zn(BDS)] is thermally stable up to nearly 600 ◦C. At
this temperature a hitherto unknown intermediate is formed that
decomposes further leading to ZnS in the wurtzite type of
was found to be only 0.2◦. These results are in good agreement
with experiment since the boat conformation of the aromatic ring
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Table 5 Selected hydrogen bonds
D–H
d(D–H)/pm d(H . . . A)/pm ∠ DHA/◦ d(D . . . A)/pm A
[Zn(BDSCl4)(DMF)4]
C2–H22 90(2)
C3–H32 95(2)
C5–H53 99(2)
C5–H52 91(2)
261(3)
285(3)
244(2)
297(3)
148(1)
106(1)
168(2)
159(2)
341.4(2)
343.3(2)
342.0(2)
384.2(3)
O12
Cl1
O13
Cl1
[Zn(BDSF4)(DMF)4]
C3–H33 103(2)
C3–H31 96(2)
C5–H52 96(2)
C5–H51 96(2)
260(2)
270(2)
248(2)
267(3)
130(2)
152(2)
165(1)
115(2)
331.1(2)
358.4(3)
341.2(2)
320.0(2)
O12
F1
O12
F2
[Cu(H2O)6](BDSF4)
O1-H11 78(2)
O1-H12 76(2)
O2-H21 73(2)
O2-H22 76(2)
O2-H22 76(2)
O3-H32 79(2)
O3-H31 79(2)
196(2)
207(3)
201(2)
212(2)
245(2)
195(2)
189(2)
179(2)
167(2)
168(1)
145(2)
143(1)
176(2)
173(2)
274.1(2)
282.2(3)
273.4(2)
277.0(2)
309.1(3)
272.8(2)
266.9(2)
O12
O13
O11
O13
F1
O12
O2
[Cu(BDSCl4)(H2O)4]
O1–H11 79(2)
O1–H11 79(2)
O1–H12 76(2)
O2–H21 78(2)
O2–H22 76(2)
Fig.
7
The p-BDSCl4 anion in [Cu(BDSCl4)(H2O)4] (a) and
192(2)
296(3)
193(2)
198(2)
203(2)
171(2)
118(1)
174(2)
174(2)
177(2)
270.0(2)
340.2(3)
268.6(2)
275.2(2)
278.8(3)
O13
Cl2
O13
O12
O12
Na2BDSCl4·2H2O (b). In the copper compound a remarkable deviation
of the benzene ring towards a boat conformation is observed while the
sodium compound exhibits the planar anion.
Fig. 8 Crystal structure of Na2BDSCl4·2H2O. The structure shows a close
relation to the structure of [Cu(BDSCl4)(H2O)4] (cf. Fig. 6).
structure according to the observed XRD powder pattern. The
thermal decomposition of [Zn(BDSF4)(DMF)4] starts also with
the release of the solvent molecules. Two steps can be clearly
identified (Fig. 10) and a small shoulder for one of the peaks
indicated that there might be a third step. Desolvation is completed
at 220 ◦C (mass loss: 40.3%, calcd. 41.6%) and the decomposition
Fig. 6 Chain structure of [Cu(BDSCl4)(H2O)4]. The coordination sphere
of the copper ions is completed by water molecules.
3136 | Dalton Trans., 2011, 40, 3128–3141
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Fig. 9 Comparison of the p-BDSCl4 conformation in [Cu(BDSCl4)-
(H2O)4] (a) and Na2BDSCl4·2H2O (b). The anions are shown along a
virtual line connecting the sulfur atoms of the [SO3] moieties.
of the remaining [Zn(BDSF4)] occurs in the temperature range
between 470 and 560 ◦C. After that temperature a continuing
weight loss can be seen in the TG curve. According to XRD
measurements the residue is hexagonal zinc oxide. For the chlorine
derivative [Zn(BDSCl4)(DMF)4] the loss of solvent molecules
is completed at 190 ◦C (Fig. 10). The desolvated compound
decomposes in a two step process starting at 330 ◦C leading to an
unknown intermediate that was degraded further at about 750 ◦C,
again yielding ZnO.
The thermal decomposition of the copper disulfonates
[Cu(H2O)6](BDSF4) and [Cu(BDSCl4)(H2O)4] starts with dehydra-
tion of the compounds (Fig. 11). For the hexahydr◦ate three steps
can be identified and the dehydration ends at 245 C (mass loss:
22.8% obsd., 22.6% calcd.). The anhydrous compound decom-
poses between 300 and 460 ◦C with CuO as the residue as identified
by XRD. The tetrahydrate of the chlorine derivative loses the water
molecules in two steps and the dehydration is complete at 280 ◦C
(mass loss: 14.0% obsd., 14.1% calcd.). The anhydrous compound
[Cu(BDSCl4)(H2O)4] decomposes to an unknown intermediate at
405 ◦C. The latter is finally transformed to elemental copper in a
broad temperature range between 500 and 650 ◦C. As can be seen
from the XRD pattern of [Cu(BDSCl4)(H2O)4] after dehydration
at 300 ◦C the anhydrous compound still shows a good crystallinity
(Fig. 12).
Fig. 10 TG/DTG diagrams for [Zn(BDS)(DMF)2] (top), [Zn(BDSF4)-
(DMF)4] (middle) [Zn(BDSCl4)(DMF)4] (bottom).
by electrophilic substitution of benzene is not a good option
because the sulfonate group is deactivating and meta-directing.
These preparative difficulties are the main reason that reports on
polysulfonates are very limited although it has been mentioned
several times that they seem worthwhile to be investigated. Thus,
the key step of our research program was to develop synthetic
strategies that allow the production of multigram amounts of
polysulfonic acids using cheap chemicals. A simple and effective
route to para-benzene disulfonic acid H2BDS (4) as analogue of
terephthalic acid (1) has been reported previously by us. In the
present paper we present convenient routes to the tetrahalogen
derivatives H2BDSF4 (7) and H2BDSCl4 (8) from readily available
starting materials. The tetrafluoro-congener 7 is prepared in
Discussion and conclusion
The enhancement of both structural diversity and thermal sta-
bility of metal–organic-frameworks requires new types of linker
molecules. The majority of linkers that are actually used for
building MOFs are carboxylates. They are easily accessible
but their thermal stability is limited. Switching to sulfonates
promises increased thermal stability but on the other hand the
synthesis of polysulfonic acids is tedious. Simple sulfonation
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Table 6 Characteristics of the compounds investigated
Dim. of Temp. range of Temp. range of
Compound
linkage
desolvation/◦C decomposition/◦C
[Cu(H2O)6](BDSF4)
[Cu(BDSCl4)(H2O)4]
[Zn(BDSF4)(DMF)4]
[Zn(BDSCl4)(DMF)4]
[Zn(BDS)(DMF)2]
0
1
1
1
2
40–245
95–280
100–220
35–190
55–210
300–460
360–440
470–560
330–470
552–625
The second step of our research program was to attempt the
building of MOFs based on the new polysulfonic acids and to
explore the properties of the compounds obtained (Table 6). The
zinc compounds were obtained from DMF solutions. In all of
the compounds solvent molecules act as ligands for the Zn2+ ions,
so that no three-dimensional linkage occurs. The same is true
for the copper sulfonates where strong coordination of the solvent
water molecules is observed. This is a typical finding for sulfonates
of harder cations.19 Even if other preparative conditions may
lead to solvent-free compounds, the simplest way to these phases
is thermal desolvation. With respect to our thermoanalytical
investigations the presented sulfonates show a large temperature
range between complete desolvation and decomposition of the
ligands. The thermal stability is remarkably high compared to the
respective carboxylates. Typical temperatures for the decomposi-
◦
tion of copper carboxylates are reported to lie at about 250 C,
◦
the respective zinc compounds decompose at about 375 C.20
Fluorine and chlorine derivatives of these carboxylates decompose
at even lower temperature.6a,21 As has been demonstrated for
[Cu(BDSCl4)(H2O)4], the dehydration at 300 ◦C leads to a
crystalline anhydrous compound (Fig. 12). It can be assumed
that this compound shows a three-dimensional network, but only
a structure determination can reveal the connectivity and the
porosity of the compound. These structure elucidations have
also to be done for the other desolvated phases to prove the
thermoanalytical results. Moreover it would be of utmost interest
Fig. 11 TG/DTG diagrams for [Cu(H2O)6](BDSF4) (top) and
[Cu(BDSCl4)(H2O)4] (bottom).
four steps from tetrafluorohydroquinone (9) with 15% overall
yield. The three-step synthesis of H2BDSCl4 (8) starts from
tetrachlorobenzene (50% overall yield).
2-
to investigate the conformation of the BDSCl4 anion in the
Fig. 12 XRD patterns for [Cu(BDSCl4)(H2O)4] and the dehydrated phase [Cu(BDSCl4)].
3138 | Dalton Trans., 2011, 40, 3128–3141 This journal is The Royal Society of Chemistry 2011
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anhydrous phase. We assume that the deviation from planarity
is correlated to the arrangement of the [SO3] groups with respect
to each other and thus occurs as a result of steric hindrance. This
hypothesis is further corroborated by the larger extent of distortion
in cases where larger moieties such as bromine, iodine or tert-butyl
were used as substituents.
In conclusion we are convinced that we have provided facile
routes to polysulfonic acids and that their availability will have a
remarkable impact in MOF chemistry.
ing dianion BDSCl42- were performed using the Gaussian03 quan-
tum chemistry program package.22 Using a correlation consistent
basis set of cc-pVDZ quality, we report conventional ab initio
calculations at the Møller–Plesset 2nd order perturbation theory
(MP2) level. Unconstrained geometry optimizations of H2BDSF4,
H2BDSCl4 and its dianion were performed. In general, two
conformations should be distinguished. The first conformation
corresponds to a “staggered” conformation of the sulfonate
groups, in which the –OH moieties are located in an anti position.
The second conformation can be characterized by a geometry in
which the sulfonate groups are oriented “eclipsed” with the –OH
moieties in syn position on the same side of the aromatic ring. The
structural and energetic differences are analyzed.
Experimental Section
General methods. Preparative column chromatography was
carried out using Merck SiO2 (0.035–0.070 mm, type 60 A) with
hexane, tert-butylmethylether (MTBE) and CH2Cl2 as eluents.
TLC was performed on Merck SiO2 F254 plates on aluminium
sheets. 1H-, 13C- and 19F-NMR spectra were recorded on a Bruker
Avance DRX 500 spectrometer. Multiplicities were determined
with DEPT experiments. IR spectra were recorded on a Bruker
Tensor 27 spectrometer equipped with a “GoldenGate” diamond-
ATR unit. EI-MS and HRMS spectra were obtained with a
Finnigan MAT 95 spectrometer, ESI-MS (HRMS) spectra with a
Waters Q-TOF Premier. Elemental analyses were measured with
a Euro EA-CHNS from HEKAtech.
DTA/TG measurements were performed with the help of a
thermal analyzer (TGA/SDTA 851E, METTLER-TOLEDO).
For that purpose about 10 mg of the substance was inserted
into a corundum container and heated with a constant rate of
10 K min-1 under flowing nitrogen. The thermal decomposition
was monitored from 30 ◦C up to 600 ◦C. Characteristic points
like onset and end temperatures of the thermal effects were
taken from the differentiated DTA curve following common
procedures using the software delivered with the analyzer. Data
for X-ray single crystal structure determination were collected
either on a Bruker Apex II CCD diffractometer or with the help
of an image plate diffractometer (Stoe IPDS I). Details of the
data collections were summarized in the Tables 1 and 2. The
structures were solved using direct methods (SHELXS-97) and
refined by full-matrix least-squares methods (SHELXL-97). All
non-hydrogen atoms were refined with anisotropic displacement
parameters. The positions of the hydrogen atoms were located
from the Fourier difference map at the final stage of the refinement.
They were refined in a riding model with the relative isotropic
parameters of the heavy atoms to which they are attached.
Crystallographic data were deposited with the Cambridge Crys-
tallographic Data Centre (CCDC) and can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing
data_request@ccdc.cam.ac.uk, or by contacting The Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB2
1EZ, UK; fax: +44 1223 336033.
1,4-Bis(dimethylaminothiocarbonyloxy)-2,3,5,6-tetrafluoroben-
zene (10). N,N-Dimethylthiocarbamoylchloride (10.2 g,
82.4 mmol, 3.00 eq.) was added to a suspension of tetrafluoro-
hydroquinone (9) (5.00 g, 27.5 mmol, 1.00 eq.) and DABCO
(12.3 g, 110 mmol, 4.00 eq.) in DMF (72 ml). The resulting mixture
was stirred for 0.5 h at 35 ◦C and then for 2 h at 80 ◦C. After
cooling to ambient temperature, H2O (80 ml) was added. The
precipitate was filtered off, washed with H2O, dried in vacuum
and purified by column chromatography on SiO2 [gradient elution
from hexane/MTBE 1 : 1 → MTBE, Rf(MTBE) = 0.55] to yield
the title compound ◦10 (7.41 g, 9.79 mmol, 76%) as a colorless
1
solid, mp. 184–185 C. H-NMR (500 MHz, CDCl3): d = 3.39
1
(s, 6 H), 3.47 (s, 6 H) ppm. 13C{ H}-NMR (125 MHz, CDCl3):
d = 39.1 (CH3), 44.1 (CH3), 129.8–130.1 (m; C–O), 141.4 (dm,
1
1J = 249 Hz; C–F), 184.6 (C–O) ppm. 19F{ H}-NMR (470 MHz,
CDCl3): d = -153.87 ppm. IR (ATR): nu(tilde) = 2949 (w), 1549
(m), 1504 (s), 1397 (s), 1261 (s), 1171 (m), 1090 (br, s), 987 (s),
910 (m), 721 (m) cm-1. MS (EI, 70 eV), m/z (%) = 356 (23) [M+],
88 (100). HRMS: calcd. 356.0276 (for C12H12F4N2O2S2), found
356.0285 [M+]. C12H12F4N2O2S2 (356.36 g mol-1).
1,4-Bis(dimethylaminocarbonylthio)-2,3,5,6-tetrafluorobenzene
(11). A suspension of thiocarbamate 10 (7.40 g, 20.8 mmol) in
◦
Ph2O (14 ml) was stirred for 1 h at 200 C (pre-heated oil bath).
After cooling to ambient temperature, the precipitate was filtered
off, washed with MeOH (10 ml) and dried in vacuum. The crude
product was purified by chromatography on SiO2 [gradient elution
hexane/MTBE 1 : 1 → MTBE → CH2Cl2, Rf(hexane/MTBE 1:
1) = 0.17] to yield the title compound 11 (4.52 g, 12.7 mmol,
◦
1
61%) as a colorless solid, mp. 232–233 C. H-NMR (500 MHz,
1
CDCl3): d = 3.04 (br, s, 6H), 3.16 (br, s, 6H) ppm. 13C{ H}-NMR
(125 MHz, CDCl3): d = 37.2 (CH3), 111.4–111.8 (m, C–S), 147.3
1
1
(dm, JC–F = 250 Hz, C–F), 161.8 (C O) ppm. 19F{ H}-NMR
(470 MHz, CDCl3): d = -131.17 ppm. IR (ATR): nu(tilde) = 2943
(w), 1679 (s), 1468 (s), 1361 (m), 1257 (m), 1247 (m), 1101 (m), 957
(s), 901 (m), 813 (m), 689 (s) cm-1. MS (EI, 70 eV), m/z (%) = 356
(15) [M+], 72 (100). HRMS: calcd. 356.0276 (for C12H12F4N2O2S2),
found 356.0282 [M+]. Anal. calcd. for C12H12F4N2O2S2 (356.36 g
mol-1): C 40.44, H 3.39, N 7.86, S 18.00; found: C 40.41, H 3.35,
N 7.69, S 17.93.
X-Ray powder diffraction investigations were performed with
the help of the powder diffractometer STADI P (STOE) using
Cu-Ka1 radiation a flat sample holder or thin walled glass
capillaries. The same diffractometer was used for high temperature
measurements. For that purpose it was equipped with a capillary
furnace and silica capillaries were used for sample preparation.
2,3,5,6-Tetrafluoro-1,4-benzenedisulfonic acid dichloride (12).
NCS (2.73 g, 20.5 mmol, 8.10 eq.) and hydrochloric acid
(2 mol dm-3, 1.4 ml, 2.8 mmol, 1.1 eq.) were added to a cooled (ice-
water bath) suspension of thiocarbamate 11 (900 mg, 2.53 mmol,
1.00 eq.) in MeCN (7.1 ml). The mixture was further stirred at
Computational methods. All calculations concerning the struc-
ture and energetics of H2BDSF4, H2BDSCl4 and the correspond-
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Dalton Trans., 2011, 40, 3128–3141 | 3139
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10–15 ◦C. After 1.5 h a clear solution should have formed;
if not, conc. hydrochloric acid (0.45 ml) was added and the
mixture further stirred at 10 ◦C, until a clear solution had formed.
Subsequently, the solution was warmed to ambient temperature
and stirred, until again a cloudy precipitation appears (10–15
min). The resulting suspension was further stirred for 0.5 h at
23 ◦C, then H2O (20 ml) and MTBE (20 ml) were added. The
layers were separated and the aqueous layer was extracted twice
with MTBE (2 ¥ 30 ml). The combined organic layers were
washed with H2O (30 ml) and dried (MgSO4). After filtration, the
solvent was evaporated and the residue chromatographed [SiO2,
CH2Cl2, Rf(MTBE) = 0.72] to give a material (379 mg), which
was further purified by recrystallization from CHCl3 to yield the
title com◦pound 12 (292 mg, 0.84 mmol, 33%) as a colorless solid,
16 h. After cooling to ambient temperature, the solvents were
evaporated in vacuum. The solid residue was extracted with H2O
(60 ml) and after filtration again washed with H2O (30 ml) und
finally dried in high vacuum to yield the monohydrate of the title
compound 15 (4.7 g, 11 mmol, 83%) as a colorless solid, mp.
◦
132 C (dec). 13C{ H}-NMR (125 MHz, D2O): d = 133.3 (C-2),
142.4 (C-1) ppm. IR (ATR): nu(tilde) = 3470 (m, br), 1644 (m),
1302 (s), 1251 (m), 1219 (s), 1115 (s), 1045 (s), 701 (m), 665 (m),
626 (s) cm-1. MS (ESI, negative mode): m/z = 395 [M - Na+],
186 [M - 2Na+]. HR-MS (ESI, negative mode): calcd. 394.7788
(for C6Cl4NaO6S2), found 394.7798 [M - Na+]. Anal. calcd. for
C6H2Cl4Na2O7S2 (437.99): C 16.45, H 0.46, S 14.64; found C 16.58,
H 0.31, S 14.90 (Na2BDSCl4·H2O).
1
2,3,5,6-Tetrachloro-1,4-benzene disulfonic acid trihydrate (8)
(H2BDSCl4·3H2O). A solution of sodium salt 15 (1.5 g, 3.4
mmol) in H2O (100 ml) was submitted through a column (5 cm ¥
1
mp. 155 C. 13C{ H}-NMR (125 MHz, CDCl3): d = 128.2–128.3
1
1
(m, C–S), 144.0 (dm, JC–F = 273 Hz, C–F) ppm. 19F{ H}-NMR
(470 MHz, CDCl3): d = -129.79 ppm. IR (ATR): nu(tilde) =
1479 (s), 1395 (s), 1266 (s), 1246 (m), 1174 (s), 989 (s), 796 (w),
636 (s) cm-1. MS (EI, 70 eV), m/z (%) = 346 (18) [M+], 311
(70), 247 (36), 148 (100), 117 (38). HRMS: calcd. 345.8551 (for
C6Cl2F4O4S2), found 345.8558 [M+]. Anal. calcd. for C6Cl2F4O4S2
(347.09 g mol-1): C 20.76, S 18.48; found C 20.79, S 18.80.
R
9 cm) of freshly activated, acidic Amberlystꢀ-15 ion exchange
resin (50 g). The eluent (H2O 300 ml) was collected until pH was
neutral. The solvent was evaporated in vacuum and the residue
redissolved in H2O (30 ml). After centrifugation and filtration, the
filtrate was again evaporated in vacuum to give the title compou◦nd
8 (1.1 g, 2.6 mmol, 75%) as a light yellow solid, mp. 197–199 C
1
(decomp.). 13C{ H}-NMR (125 MHz, D2O): d = 133.2 (C-2), 142.3
2,3,5,6-Tetrafluoro-1,4-benzenedisulfonic acid dihydrate (7)
(H2BDSF4·2H2O). A suspension bissulfonylchloride 12 (65 mg,
0.19 mmol, 1.00 eq.) in H2O (6.5 ml) was heated to reflux for
16 h. After filtration, all volatile materials were evaporated from
the filtrate in vacuum to yield the dihydrate of the title compound
7 (66 mg, 0.19 mmol, 100%) as a colorless solid, mp. 169 ◦C.
(C-1) ppm. IR (ATR): nu(tilde) = 3124 (s, br), 1667 (s, br), 1306
(s), 1243 (m), 1163 (s), 1101 (s), 1010 (s, br), 703 (m), 664 (m), 646
(m) cm-1. MS (ESI, negative mode): m/z = 373 [M - H+], 186 [M
- 2H+]. C6H2Cl4S2O6·3H2O (430.06 g mol-1).
Zinc(II)(1,4-benzenedisulfonate)bis(dimethylformamide)
[Zn-
1
13C{ H}-NMR (125 MHz, D2O): d = 123.9–124.0 (m, C–S), 143.5
(BDS)(DMF)2]. A mixture of 19 mg Zn(OH)2 (0.191 mmol),
17 mg H2BDS·2H2O (4) (0.062 mmol) and 3 ml DMF were
sealed in a glass ampoule. The ampoule was placed in a resistance
furnace and heated up to 105 ◦C within 6 h. After 24 h the furnace
was slowly cooled to room temperature within 96 h. The product
was obtained as transparent single crystals which were separated
from the supernatant liquid by decantation.
1
(dm, 1J = 253 Hz, C–F) ppm. 19F{ H}-NMR (470 MHz, D2O): d =
-138.5 ppm. IR (ATR): nu(tilde) = 3190 (br, m), 1688 (br, m), 1464
(s), 1403 (w), 1262 (s), 1179 (br, s), 1035 (s), 973 (s), 624 (s) cm-1.
ESI-MS (negative mode), m/z = 309 [M - H+], 154 [M - 2H+].
HR-MS (ESI, negative mode): calcd. 308.9151 (for C6HF4O6S2),
found 308.9147 [M - H+]. C6H2F4O6S2·2H2O (346.23 g mol-1).
1,4-Dinitro-2,3,5,6-tetrachlorobenzene (14). Oleum (H2SO4
with 65% SO3, 143 g, 72.0 ml, 554 mmol, 24.0 eq.) was added
at 0 ◦C to a mixture of 1,2,4,5-tetrachlorobenzene (13) (5.0 g,
23 mmol, 1.0 eq.) and NaNO3 (12.0 g, 139 mmol, 6.0 eq.). The
resulting mixture was heated to reflux for 14 h, and then cooled
with an ice-bath. Water (100 ml) was carefully added and the
mixture poured on ice (500 g). The precipitate was collected by
filtration, washed with water (30 ml), dried in vacuum and finally
recrystallized from MeOH–CHCl3 (2: 3, 160 ml) to yield the title
com◦pound 14 (5.6 g, 19 mmol, 80%) as colorless needles, mp.
Zinc(II)(2,3,5,6-tetrafluorobenzene-1,4-disulfonate)tetrakis(di-
methylformamide) [Zn(BDSF4)(DMF)4]. A mixture of 18 mg
Zn(OH)2 (0.181 mmol), 20 mg H2BDSF4·2H2O (7) (0.062 mmol)
and 3 ml DMF were sealed in a glass ampoule. The ampoule
was placed in a resistance furnace and heated up to 105 ◦C
within 6 h. After 24 h the furnace was slowly cooled to room
temperature within 96 h. The product was obtained as transparent
single crystals which were separated from the supernatant liquid
by decantation.
1
228 C. 13C{ H}-NMR (125 MHz, CDCl3): d = 126.1 (C-2), 149.3
Zinc(II)(2,3,5,6-tetrachlorobenzene-1,4-disulfonate)tetrakis(di-
methylformamide) [Zn(BDSCl4)(DMF)4]. To a solution of 0.05 g
H2BDSCl4·2H2O (8) (0.12 mmol) in 3.5 ml DMF 39 mg
Zn(NO3)2·6H2O (0,13 mmol) were added. The reaction mixture
was kept at 50 ◦C for 24 h. When the solution was reduced to 2/3
of its initial volume, the crystallization of colorless crystals starts.
After evaporation of further solvent the crystals were collected by
suction.
(C-1) ppm. IR (ATR): nu(tilde) = 1544 (s), 1393 (m), 1335 (s), 1241
(s), 1241 (m), 1134 (m), 1037 (w), 862 (m), 784 (s), 631 (s) cm-1.
MS (EI, 70 eV): m/z (%) = 304 (100) [M+], 212 (60), 177 (40),
142 (65). HR-MS (EI, 70 eV): calcd. 303.8612 (for C6Cl4N2O4),
found 303.8610 [M+]. Anal. calcd. for C6Cl4N2O4 (305.89 g mol-1):
C 23.56, N 9.16; found C 23.47, N 9.11.
Disodium 2,3,5,6-tetrachloro-1,4-benzenedisulfonate monohy-
drate (15) (Na2BDSCl4·H2O). A solution of Na2SO3 (8.2 g,
65 mmol, 5.0 eq.) in H2O (65 ml) was added to a suspension
of dinitrotetrachlorobenzene (14) (4.0 g, 13 mmol, 1.0 eq.) in 1,4-
dioxane (35 ml). The resulting mixture was heated to reflux for
Copper(II)(2,3,5,6-tetrafluorobenzene-1,4-disulfonate) hexahy-
drate [Cu(H2O)6](BDSF4). Cu2(OH)2(CO3) (33.2 mg, 0.15 mmol)
was added at 50 ◦C in three portions over 2 h to a solution of
H2BDSF4·2H2O (7) (106 mg, 0.30 mmol) in H2O (5 ml). The
3140 | Dalton Trans., 2011, 40, 3128–3141
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resulting blue solution was stirred for 16 h at 50 ◦C, then filtered
and cooled to ambient temperature. After a few days in air at
room temperature blue crystals grew from the solution. They were
collected by suction and dried under ambient conditions.
9 (a) J. N. Harvey, J. Jover, G. C. Lloyd-Jones, J. D. Moseley, P. Murray and
J. S. Renny, Angew. Chem., 2009, 121, 7748–7751; J. N. Harvey, J. Jover,
G. C. Lloyd-Jones, J. D. Moseley, P. Murray and J. S. Renny, Angew.
Chem., Int. Ed., 2009, 48, 7612–7615; (b) J. S. Albert, D. Aharony, D.
Andisik, H. Barthlow, P. R. Bernstein, R. A. Bialecki, R. Dedinas,
B. T. Dembofsky, D. Hill, K. Kirkland, G. M. Koether, B. J. Kosmider,
C. Ohnmacht, W. Palmer, W. Potts, W. Rumsey, L. Shen, A. Shenvi,
S. Sherwood, P. J. Warwick and K. Russell, J. Med. Chem., 2002, 45,
3972–3983; (c) M. S. Raasch, J. Org. Chem., 1979, 44, 2629–2632.
10 (a) M. S. Newman and H. A. Karnes, J. Org. Chem., 1966, 31, 3980–
3984; (b) H. Kwart and E. R. Evans, J. Org. Chem., 1966, 31, 413–419.
11 (a) M. Treskow, J. Neudo¨rfl and R. Giernoth, Eur. J. Org. Chem.,
2009, 3693–3697. See also: (b) M. Barbero, S. Bazzi, S. Cadamuro,
S. Dughera, C. Magistris and P. Venturello, Synlett, 2010, 1803–
1806; (c) A. Nishiguchi, K. Maeda and S. Miki, Synthesis, 2006, 4131–
4134; (d) D.-W. Kim, Y. K. Ko and S. H. Kim, Synthesis, 1992, 1203–
1204.
Copper(II)(2,3,5,6-tetrachlorobenzene-1,4-disulfonate) tetrahy-
drate [Cu(BDSCl4)(H2O)4]. Cu2(OH)2(CO3) (134 mg, 0.60
mmol) was added at 50 ◦C in three portions over 2 h to a solution
of H2BDSCl4 (8) (100 mg, 0.26 mmol) in H2O (10 ml). The
resulting blue suspension was stirred for 24 h at 50 ◦C, then diluted
◦
with 50 ml H2O and kept at 50 C for 10 min. Excess malachite
was removed by filtration and the filtrate was cooled to ambient
temperature. After a few days in air at room temperature blue
crystals grew from the solution. They were collected by suction
and dried under ambient conditions.
12 C. L. Diedrich, D. Haase and J. Christoffers, Synthesis, 2008, 2199–
2210.
13 G. Deacon, J. M. Miller and B. S. F. Taylor, Aust. J. Chem., 1975, 28,
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Acknowledgements
14 N. S. Dokunikhin, L. A. Gaeva and G. A. Mezentseva, Dokl. Akad.
Nauk. SSSR, 1972, 206, 624–626.
We are grateful to Mr Wolfgang Saak for the collection of X-ray
data.
15 G. R. Desiraju, Chem. Commun., 2005, 2995–3001; G. A. Jeffrey, An
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The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 3128–3141 | 3141
©