A metallopolymer, [Cu(abt)]∞ (abt, 2-aminobenzenethiol) with novel structural patterns resembling black phosphorus

Article abstract of DOI:10.1016/j.ica.2010.03.008

A copper(I) complex of 2-aminobenzenethiol, [Cu(abt)]_∞ (1), has been synthesized and characterized. The crystal structure determination indicates a two-dimensional metallopolymeric network formed by edge and corner sharing [Cu(μ₃-S)N] coordination tetrahedra wherein the copper(I) centers are coordinated to three bridging thiolate donors and the amino group of 2-aminobenzenethiolate. The copper, the sulfur and the nitrogen atoms form sub-lattices that reveal independently striking similarities to the double-layers present in black phosphorus.

Full text of DOI:10.1016/j.ica.2010.03.008

Inorganica Chimica Acta 363 (2010) 2144–2148
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
A metallopolymer, [Cu(abt)] (abt, 2-aminobenzenethiol) with novel structural
1
patterns resembling black phosphorus
b
b,
**
M.S. Ameerunisha Begum a,b, , Ulrich Flörke , Gerald Henkel
*
a Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
b Department of Chemistry, University of Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 May 2009
Received in revised form 25 February 2010
Accepted 3 March 2010
Available online 7 March 2010
A copper(I) complex of 2-aminobenzenethiol, [Cu(abt)] (1), has been synthesized and characterized. The
crystal structure determination indicates a two-dimensional metallopolymeric network formed by edge
and corner sharing [Cu(l3-S)N] coordination tetrahedra wherein the copper(I) centers are coordinated to
three bridging thiolate donors and the amino group of 2-aminobenzenethiolate. The copper, the sulfur
and the nitrogen atoms form sub-lattices that reveal independently striking similarities to the double-
layers present in black phosphorus.
1
Dedicated to Prof. Gerd Meyer on the
occasion of his 60th birthday.
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
N/S ligands
Copper
X-ray diffraction
Crystal structures
Metallopolymers
Cu–N–S complexes
1. Introduction
to iron as o-aminothiophenolate(1ꢀ) forming (
l
-{S,S})[FeII(abt)2]2
radical
or in addition as iminothionebenzosemiquinonate(1ꢀ)
p
Copper complexes of N, S ligands are of interest as models for
the CuA center of cytochrome-c-oxidase (CcO), which is involved
in the final step of cell respiration catalysing reduction of molecu-
lar oxygen to water [1–5]. 2-Aminobenzenethiol (abt) belongs to
the group of aryl N, S donor ligands, which are capable of forming
in its oxidized form, (iibs)ꢀ, forming [FeII(abt)2(iibs)]ꢀ. A complex
formulated as {CuI(abt)} has been synthesized earlier but structural
information is yet not known [24–29]. To investigate complexes
with [Cu(lx-S)xN]n cores of varying nuclearities we synthesised
the copper(I) complex of abt, [Cu(abt)] (1). Herein we report
1
[Cu(
cently we reported a N,S ligand, iso-abt, which forms tetranuclear
and dodecanuclear copper(I) complexes with trigonal [Cu(
S)2N]4 butterfly or tetrahedral [Cu( 3-S)3N]12 double wheel
l
x-S)xN]n cyclic frameworks of varying nuclearities [6–16]. Re-
the synthesis and describe a novel structural pattern associated
with copper complexes derived from bifunctional N/S donor
ligands.
l-
l
architectures [6]. The known complexes contain N-substituted
N,S ligands, which are derived from abt, and this ligand is an exam-
ple that can stabilise both copper(I) and copper(II) centers. The
coordination chemistry of abt has been investigated for the cases
of vanadium and iron, and the ligand is viable to the formation
of radicals and it is redox non-innocent towards iron [17–23]. It
formed the complex anion [V(SNH2C6H4)2(SNHC6H4)]ꢀ wherein
three abt ligands are bound to vanadium(III), and it can coordinate
2. Experimental
2.1. Synthesis of [Cu(abt)] (1)
1
The reaction was carried out under a dinitrogen atmosphere
using Schlenk technique.
2-Aminobenzenethiol (125 mg, 1 mmol) was treated with tri-
ethylamine (0.100 mL, 1 mmol) in DMF (60 mL) under N2 atmo-
sphere and after stirring for 20 min, CuI (180 mg, 1 mmol) was
added. Stirring was continued for 2 h at 24 °C followed by diffusion
of diethylether vapours into the reaction mixture for 19 h. The
vapour diffusion of diethyl ether was then discontinued and the
reaction flask was tightly closed under N2 atmosphere and left in
* Corresponding author at: Department of Chemistry, Indian Institute of Tech-
nology Kanpur, Kanpur 208016, India.
** Corresponding author. Fax: +49 5251 60 3423.
E-mail addresses: begum@iitk.ac.in (M.S.A. Begum), biohenkel@uni-paderborn.de
(G. Henkel).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.03.008

M.S.A. Begum et al. / Inorganica Chimica Acta 363 (2010) 2144–2148
2145
the refrigerator for a period of 3 days, which led to the formation of
extremely air sensitive white single crystals of 1. Data for 1: Yield,
43%; C, H, N analysis (%), Anal. Calc. for C6H6CuNS: C, 38.35; H, 3.19;
N, 7.45. Found: C, 38.16; H, 2.89; N, 7.69%. IR (KBr):
m )
(cmꢀ1
3328(w), 3211(w), 1579(s), 1544(s), 1468(s), 1437(s), 1280(m),
929(s), 809(s), 746(s) (s, strong; m, medium; w, weak). 1H NMR
(500 MHz, DMSO-d6, 298 K): d (ppm) 7.10 (t, 1H), 7.01 (d, 1H),
6.73 (d, 1H), 6.43 (t, 1H), 5.43 (s, 2H).
2.2. X-ray structure analysis
The X-ray intensities were collected on a Bruker AXS Smart
APEX CCD diffractometer with graphite monochromated Mo K
a
radiation (k = 0.71073 Å). The structure was solved by direct and
conventional Fourier methods and refined on F2 by full-matrix
least-squares techniques [30]. All non-hydrogen atoms were re-
fined anisotropically, H atoms at idealized positions in riding
mode. Selected crystallographic data of compound 1 are given in
Table 1.
Chart 1. Structural subunit of the polymeric complex 1 with the characteristic
{Cu(l3-S)N} core highlighted by thick lines.
DMSO-d6. The 1H NMR in DMSO-d6 indicated signals (two triplets
and two doublets) corresponding to the protons of 2-
aminobenzenethiolate.
2.3. Other physical measurements
Spectra were recorded using the following spectrometers: NMR,
Bruker WMX 500; IR, Nicolet P510. The elemental analyses were
performed on a Perkin Elmer Analysator Model 240.
3.1. Structure of 1
The X-ray structure determination of 1 indicates that the com-
plex is polymeric with 1:1 metal to ligand composition. The struc-
ture consists of sheets expanding infinitely along two directions via
the copper(I) center, coordinated nitrogen and sulfur donors of the
ligand. The nitrogen and sulfur atoms of an abt ligand are coordi-
nated to two different copper(I) centers. A fragment of the poly-
meric structure of 1 is shown in Fig. 1, and the bond lengths and
valence angles are given in Table 2. The structure can be primarily
considered as a network of dinuclear {Cu(abt)}2 cores with tetra-
coordinated copper(I) centers. The links between these cores are
3. Results and discussion
The polymeric complex 1 is shown in part in Chart 1. The com-
plex was prepared by the reaction of 2-aminobenzenethiol and CuI
in DMF. White single crystals of [Cu(abt)] composition formed
1
over a period of three days after vapour diffusion of diethyl ether.
Complex 1 was characterized by IR, elemental analysis, 1H NMR
and X-ray crystallography. The IR spectrum (KBr disc) of 1 showed
NH2 peaks at
m
(cmꢀ1), 3328 and 3211. The polymeric complex is
insoluble in all common solvents and sparingly soluble in
formed by the
center is coordinated in a pseudo-tetrahedral fashion by a terminal
nitrogen and three 3-bridging thiolates. The three Cu–S bond
l3-bridging thiolate donors wherein each copper(I)
Table 1
l
Crystal data for [Cu(abt)] (1).
1
Empirical formula
Formula weight
T (K)
C6H6CuNS
187.72
120(2)
Wavelength Mo K
Crystal system
Space group
a
(Å)
0.71073
monoclinic
P21/c
Unit cell dimensions
a (Å)
13.786(1)
b (Å)
7.081(1)
c (Å)
6.173(1)
b (°)
96.2(2)
599.14
Volume (Å3)
Z
4
Density (Mg/m3)
2.081
3.875
376
Absorption coefficient (mmꢀ1
F(0 0 0)
)
Crystal size (mm)
h Range for data collection
Index ranges
0.40 ꢁ 0.20 ꢁ 0.03
1.49–28.26°
ꢀ16 < h < 18, ꢀ9 < k < 9,
ꢀ8 < l < 8
Reflections collected
7277
Independent reflections
Completeness to h = 28.26°
Absorption correction
Refinement method
1483 [Rint = 0.0312]
99.8%
semi-empirical from equivalents
full-matrix least-squares on F2
1483/1/90
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
1.118
Fig. 1. Structure of a fraction of polymeric 1 with the thiolate-bridged copper(I)
site. The ligand spheres around copper(I) viz., Cu(1A), Cu(1C), Cu(1D), Cu(1E),
Cu(1F), Cu(1G) and the S-donors S(1A), S(1C), S(1AC) and S(1AA) are incomplete and
terminated for clarity.
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0219, wR2 = 0.0570
R1 = 0.0229, wR2 = 0.0576
0.528 and ꢀ0.317
Largest difference in peak and hole (e Åꢀ3
)

2146
M.S.A. Begum et al. / Inorganica Chimica Acta 363 (2010) 2144–2148
Table 2
The structure of 1 viewed down the x-axis followed by the re-
Selected distances [Å] and angles [°] for [Cu(abt)] (1).
1
moval of carbon and hydrogen atoms presents an inspiring poly-
meric design incorporating both 10-membered {CuSCCNCuSCCN}
and 4-membered {CuSCuS} rings. The crystal packing of 1 seen
along the z-axis presents isolated sheets with distances being
2.583 Å for nearest intermolecular HꢂꢂꢂH contacts. The metallopoly-
mer 1 shows close structural resemblance to black phosphorus,
which is a two-dimensional double-layer lattice. The structure of
black phosphorus is composed of puckered layers with 6-mem-
bered rings, and each phosphorus is bound to three nearest neigh-
bours [31]. Similarly the structure of 1 contains interpenetrating
double-layers formed by the (Cu–S)1 network wherein the copper
and sulfur atoms are oriented in a zig-zag fashion as shown in
Fig. 2.
As such the overall structure of 1 is composed of three double-
layered sub-lattices viz., the copper sub-lattice, the sulfur sub-lat-
tice and the nitrogen sub-lattice, which are each composed of
sheared 6-membered rings in the chair conformation. The nitrogen
sub-lattice is the replica of the black phosphorus structure whereas
the Cu and S sub-lattices are more distorted compared with the
black phosphorus structure due to shear imposed on the 6-mem-
bered basic building blocks. The copper, sulfur and nitrogen sub-
lattices extracted from the structure of 1 along with the structure
of the black phosphorus are displayed in Fig. 3. The copper and
the sulfur sub-lattices are nearly identical but differently
orientated in space; their 6-membered rings are both in compara-
ble dimensions in contrast to that of the nitrogens, which are
Bond lengths
Bond angles
Bond lengths
Bond angles
Cu(1)–N(1)
Cu(1)–S(1)#1
Cu(1)–S(1)#2
Cu(1)–S(1)
S(1)–C(1)
S(1)–Cu(1)#3
S(1)–Cu(1)#2
N(1)–C(2)#4
C(1)–C(6)
C(1)–C(2)
C(6)–C(5)
C(2)–C(3)
C(2)–N(1)#4
C(3)–C(4)
2.1749(14)
2.2713(4)
2.3327(4)
2.4002(4)
1.7805(16)
2.2713(4)
2.3327(4)
1.423(2)
1.399(2)
1.401(2)
1.386(2)
1.390(2)
1.423(2)
1.393(2)
1.387(2)
N(1)–Cu(1)–S(1)#1
N(1)–Cu(1)–S(1)#2
S(1)#1–Cu(1)–S(1)#2
N(1)–Cu(1)–S(1)
S(1)#1–Cu(1)–S(1)
S(1)#2–Cu(1)–S(1)
C(1)–S(1)–Cu(1)#3
C(1)–S(1)–Cu(1)#2
Cu(1)#3–S(1)–Cu(1)#2
C(1)–S(1)–Cu(1)
112.47(4)
114.58(4)
114.982(15)
92.19(4)
132.207(13)
87.470(15)
99.88(5)
115.88(5)
103.387(16)
127.77(5)
115.721(16)
92.530(15)
123.83(10)
118.89(14)
119.78(12)
Cu(1)#3–S(1)–Cu(1)
Cu(1)#2–S(1)–Cu(1)
C(2)#4–N(1)–Cu(1)
C(6)–C(1)–C(2)
C(5)–C(4)
C(6)–C(1)–S(1)
Symmetry transformations used to generate equivalent atoms: #1 ꢀx, y ꢀ 1/2, ꢀz + 1/
2; #2 ꢀx, ꢀy + 2, ꢀz; #3 ꢀx, y + 1/2, ꢀz + 1/2; #4 ꢀx, ꢀy + 2, ꢀz + 1.
lengths are different and range from 2.271(3) via 2.333(1) to
2.400 Å, the shortest one being exocyclic with respect to the
Cu2S2 core portion. The short contacts existing throughout the lat-
tice between the N- or S-donors and the neighbouring copper(I)
ions are covalent bonds, which lead to the formation of a two-
dimensional coordination polymer.
Fig. 2. Fraction of the double-layered zig-zag (Cu–S) network in the structure of 1.
1
Fig. 3. (a) The copper sub-lattice; (b) the sulfur sub-lattice, (c) the nitrogen sub-lattice extracted from the structure of 1 and (d) structure of black phosphorus.

M.S.A. Begum et al. / Inorganica Chimica Acta 363 (2010) 2144–2148
2147
Fig. 4. Polyhedral representation of the {Cu(l3-S)N}1 (1), {Cu(l3-S)N}12 (2) and {Cu(l-S)N}4 (3) cores.
significantly different. The intra-layer distances in the copper, sul-
fur and nitrogen sub-lattices are 1.660, 2.187 and 3.812 Å, respec-
tively. By superposition of the three individual sub-lattices, the
Acknowledgements
M.S.A.B. thanks the Alexander von Humboldt foundation (AvH),
Germany and the University of Paderborn, Germany for the award
of the renewed research fellowship (2009), the Council of Scientific
and Industrial Research, (CSIR), India for the award of the Senior
Research Associateship (2006–2009) under the Scientists’ Pool
scheme and the Department of Science and Technology (DST), In-
dia for the award of Fast track scheme for young scientists.
overall {Cu(l3-S)N} core in 1 is obtained.
The formation of the polymeric network of 1 is a result of the
less commonly observed tetrahedral connectivity of CuI. Each
{Cu(l3-S)3N} coordination tetrahedron is connected to five other
ones, to the first one by an edge-sharing interaction and to the
remaining ones by vertex-sharing modes (Fig. 4, 1). Since the cor-
ner defined by N is not shared, a two-dimensional polymeric struc-
ture is formed rather than a three dimensional one. In the cyclic
Appendix A. Supplementary material
{Cu2S2} units the
l3-bridging sulfur donors are located within
the sum of their van der Waals radii (SꢂꢂꢂS 3.272 Å) and the CuIꢂꢂꢂCuI
intermetallic separation within the rhomb is 3.420 Å. The copper(I)
complex of N-methylated ligand, N,N0-dimethylaminobenzenethiol
CCDC 730041 contains the supplementary crystallographic data
for 1. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.ica.2010.03.008.
is neutral and trinuclear with l2-bridging thiolate donors and the
geometry around the CuI centers is trigonal planar [10]. On the
other hand, the CuI complexes of the imino derivatives of 2-amino-
benzenethiol are tetranuclear with trigonal geometry or octanucle-
ar or dodecanuclear with pseudo-tetrahedral geometries around
the CuI centers (Fig. 4, 2 and 3).
References
The trigonal butterfly-type architecture (Fig. 4, 3) is formed by
[1] G. Henkel, B. Krebs, Chem. Rev. 104 (2004) 801.
[2] G. Henkel, A. Müller, S. Weissgräber, G. Buse, T. Soulimane, G.C.M. Steffens, H.-
F. Nolting, Angew. Chem. 107 (1995) 1615.
[3] G. Henkel, A. Müller, S. Weissgräber, G. Buse, T. Soulimane, G.C.M. Steffens, H.-
F. Nolting, Angew. Chem., Int. Ed. Engl. 34 (1995) 1488.
[4] B. Krebs, G. Henkel, Angew. Chem. 103 (1991) 785.
[5] B. Krebs, G. Henkel, Angew. Chem., Int. Ed. Engl. 30 (1991) 769.
[6] M.S.A. Begum, O. Seewald, U. Flörke, G. Henkel, Inorg. Chim. Acta 361 (2008)
1868.
[7] J. Schneider, M. Köckerling, R. Kopitzky, G. Henkel, Eur. J. Inorg. Chem. (2003)
1727.
[8] K. Tatsuya, N. Masato, M. Nishijima, N. Koichi, I.-K. Asako, K. Takumi, Chem.
Eur. J. 14 (2008) 9842.
[Cu(l-S)2N] corner sharing triangles whereas the double wheel
architecture is formed by the [Cu(
l3-S)3N] adjacent edge-sharing
tetrahedra (Fig. 4, 2) [6]. In all of the reported examples, the Cu–
S–Cu bridging angles (ca. 64°–74°) are acute and the CuIꢂꢂꢂCuI dis-
tances are short (ca. 2.67 Å). But in the complex 1, these angles
are around 92°, and the intermetallic separations are significantly
longer (ca. 3.420 Å). The structural features of [Cu(abt)]1 prove
that the geometry of the [Cu(l3-S)3N] core is governed by the type
of polyhedral connectivity, which in turn depends upon the steric
demands of the ligand. Thus the N-substituted compounds form
oligomers whereas the unsubstituted abt forms a polymer with un-
ique tetrahedral connectivity.
[9] A.F. Stange, K.W. Klinkhammer, W. Kaim, Inorg. Chem. 35 (1996) 4087.
[10] M.D. Janssen, J.G. Donkervoort, S.B. van Berlekom, A.L. Spek, D.M. Grove, G. van
Koten, Inorg. Chem. 35 (1996) 4752.
[11] E.C. Brown, N.W. Aboelella, A.M. Reynolds, G. Aullon, A. Alvarez, W.B. Tolman,
Inorg. Chem. 43 (2004) 3335.
[12] L.J. Ashfield, A.R. Cowley, J.R. Dilworth, P.S. Donnelly, Inorg. Chem. 43 (2004)
4121.
[13] T. Kawamoto, N. Ohkoshi, I. Nagasawy, H. Kuma, Y. Kushi, Chem. Lett. (1997)
553.
4. Conclusions
[14] E.S. Raper, J.R. Crighton, W. Clegg, Inorg. Chim. Acta 237 (1995) 87.
[15] I.G. Dance, Polyhedron 5 (1986) 1037.
The metallopolymer [Cu(abt)] (1) described hitherto has been
1
[16] P.J. Blower, J.R. Dilworth, Coord. Chem. Rev. 76 (1987) 121.
[17] G. Henkel, B. Krebs, W. Schmidt, Angew. Chem. 104 (1992) 1380.
[18] G. Henkel, B. Krebs, W. Schmidt, Angew. Chem., Int. Ed. Engl. 31 (1992) 1366.
[19] P. Ghosh, A. Begum, E. Bill, T. Weyhermüller, K. Wieghardt, Inorg. Chem. 42
(2003) 3208.
[20] D. Sellmann, S. Emig, F.W. Heinemann, F. Knoch, Angew. Chem. 109 (1997)
1250.
[21] D. Sellmann, S. Emig, F.W. Heinemann, F. Knoch, Angew. Chem., Int. Ed. Engl.
36 (1997) 1201.
synthesized and its structure has been determined, which indicates
the formation of a two-dimensional polymeric structure. Further-
more, three interpenetrating double-layered sub-lattices, formed
by Cu, S and N, respectively, can be identified, which show close
structural relationships with similar double-layers present in black
phosphorus. The structure of 1 with its unique tetrahedral connec-
tivity is a novel addition to the class of copper(I) oligomeric com-
plexes of N/S ligands, which form complexes of varying
nuclearities.
[22] D. Sellmann, S. Emig, F.W. Heinemann, Angew. Chem. 109 (1997) 1808.
[23] D. Sellmann, S. Emig, F.W. Heinemann, Angew. Chem., Int. Ed. Engl. 36 (1997)
1734.

2148
M.S.A. Begum et al. / Inorganica Chimica Acta 363 (2010) 2144–2148
[24] L.F. Larkworthy, J.M. Murphy, D.J. Phillips, Inorg. Chem. 7 (1968) 1436.
[25] A.C. Braithwaite, C.E.F. Rickard, T.N. Waters, Transition Met. Chem. 1 (1975) 5.
[26] E.D. Dickens Jr., US Patent 3963163, 1976.
[27] Y. Teppei, K. Hiroshi, Jpn. Kokai Tokkyo Koho, JP Patent 2007149436, 2007.
[28] U. Hisashi, K. Tetsuo, O. Seiichi, S. Etsuichi, M. Toshio, S. Hideo, Jpn. Kokai
Tokkyo Koho, JP Patent 07157657, 1995.
[29] S. Shotaro, U. Haruo, S. Tsuneo, I. Seiji, Jpn. Tokkyo Koho, JP Patent 46038571,
1971.
[30] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
[31] A. Brown, S. Rundqvist, Acta Crystallogr. 19 (1965) 684.