Macrocyclic amines as structure-directing agents for the synthesis of three-dimensional antimony-sulfide frameworks

Article abstract of DOI:10.1021/ic060263f

A new family of antimony sulfides, incorporating the macrocyclic tetramine 1,4,8,11-tetraazacyclotetradecane (cyclam), has been prepared by a hydrothermal method. [C₁₀N₄H₂₆][Sb₄S₇] (1), [Ni(C₁₀N₄H₂₄)][Sb₄S ₇] (2), and [Co(C₁₀N₄H₂₄)] _x[C₁₀N₄H₂₆]_1-x[Sb ₄S₇] (0.08 ≤ x ≤ 0.74) (3) have been characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetry, and analytical electron microscopy. All three materials possess the same novel three-dimensional Sb₄S₇^2- framework, constructed from layers of parallel arrays of Sb₄S₈ ^4- chains stacked at 90° to one another. In 1, doubly protonated macrocyclic cations reside in the channel structure of the antimony-sulfide framework. In 2 and 3, the cyclam acts as a ligand, chelating the divalent transition-metal cation. Analytical and X-ray diffraction data indicate that the level of metal incorporation in 2 is effectively complete, whereas in 3, both metalated and nonmetalated forms of the macrocycle coexist within the structure.

Full text of DOI:10.1021/ic060263f

Inorg. Chem. 2006, 45, 4261−4267
Macrocyclic Amines as Structure-Directing Agents for the Synthesis of
Three-Dimensional Antimony-Sulfide Frameworks
Anthony V. Powell,*,† Rachel J. E. Lees,† and Ann M. Chippindale‡
Department of Chemistry, Heriot-Watt UniVersity, Edinburgh EH14 4AS, U.K., and School of
Chemistry, The UniVersity of Reading, Whiteknights, Reading RG6 6AD, U.K.
Received February 15, 2006
A new family of antimony sulfides, incorporating the macrocyclic tetramine 1,4,8,11-tetraazacyclotetradecane (cyclam),
has been prepared by
Co(C10
a
[Sb
hydrothermal method. [C10
4 4 7 4 4 7
N H26][Sb S ] (1), [Ni(C10N H24)][Sb S ] (2), and
[
N
4
H
24)]
x
[C10
N
4
H
26
]
1-x
4 7
S
] (0.08 0.74) (3) have been characterized by single-crystal X-ray diffraction,
e x e
elemental analysis, thermogravimetry, and analytical electron microscopy. All three materials possess the same
2-
4-
novel three-dimensional Sb
S
4 7
framework, constructed from layers of parallel arrays of Sb
4
S
8
chains stacked
at 90 to one another. In 1, doubly protonated macrocyclic cations reside in the channel structure of the antimony-
°
sulfide framework. In 2 and 3, the cyclam acts as a ligand, chelating the divalent transition-metal cation. Analytical
and X-ray diffraction data indicate that the level of metal incorporation in 2 is effectively complete, whereas in 3,
both metalated and nonmetalated forms of the macrocycle coexist within the structure.
Introduction
Synthesis of these materials is generally performed in the
presence of organic amines as structure-directing agents. The
principal types of organic species used are linear and
branched long-chain aliphatic amines and polyamines and
alicyclic amines. Long-chain polyamines, in particular, are
Template-directed synthesis of chalcogenides is of increas-
ing interest in the search for new materials with novel
1
2
architectures. The report by Bedard and co-workers that
solvothermal methods adapted from those used in oxide and,
particularly, zeolite chemistry could be used to effect the
synthesis of tin and germanium sulfides led to a tremendous
growth in template-directed synthesis of main-group chal-
cogenides. Much attention has subsequently focused on the
sulfides of germanium, indium, and antimony, which exhibit
a range of interesting structural features, including low-
14
frequently unstable at elevated temperatures. For example,
under solvothermal conditions they can undergo side-
3
,15
16
reactions such as cyclization
and cleavage, thereby
introducing further geometric diversity into the structure-
directing agent. The products of such reactions consist of
complex anionic metal-sulfide frameworks with protonated
amines fulfilling the charge-balancing role.
The introduction of transition-metal cations into the
reaction mixture usually leads to chelation and the in situ
formation of a transition-metal-amino complex. Such com-
plexes can themselves serve as structure-directing agents for
the growth of anionic main-group sulfide frameworks. For
example, tris(ethylenediamine) complexes of iron, cobalt, and
nickel serve as charge-balancing counterions for anionic
3,4,5,6,7,8
9,10
dimensionality,
adamantoid building units, supertet-
1
1,12
13
rahedra,
and zeolitic-like structures.
*
To whom correspondence should be addressed. Fax: +44 (0)131 451
3
180. E-mail: a.v.powell@hw.ac.uk.
†
Heriot-Watt University.
The University of Reading.
‡
(
(
1) Feng, P.; Bu, X.; Zheng, N. Acc. Chem. Res. 2005, 38, 293.
2) Bedard, R. L.; Wilson, S. T.; Vail, L. D.; Bennett, J. M.; Flanigen, E.
M. In Zeolites: Facts, Figures, Future; Jacobs, P., van Santen, R.
A., Eds.; Elsevier: Amsterdam, 1989.
(
(
(
(
(
(
3) Parise, J. B.; Ko, Y. Chem. Mater. 1992, 4, 1446.
(12) Li, H.; Kim, J.; O’Keeffe, M.; Yaghi, O. M. Angew. Chem., Int. Ed.
2003, 42, 1819.
(13) Vaqueiro, P.; Chippindale, A. M.; Powell, A. V. Inorg Chem. 2004,
43, 7963.
(14) Hutchinson, W. M.; Collett, A. R.; Lazzell, C. L. J. Am. Chem. Soc.
1945, 67, 1966.
(15) Powell, A. V.; Paniagua, R.; Vaqueiro, P.; Chippindale, A. M. Chem.
Mater. 2002, 14, 1220.
4) Bensch, W.; Schur, M. Z. Naturforschung. 1997, 52b, 405.
5) Stephan, H.-O.; Kanatzidis, M. G. Inorg. Chem. 1997, 36, 6050.
6) Tan, K.; Ko, Y.; Parise, J. Acta Crystallogr. 1994, C50, 1439.
7) Wang, X. Eur. J. Solid State Inorg. Chem. 1995, 32, 303.
8) Tan, K.; Ko, Y.; Parise, J. B.; Park, J. B.; Darovsky, A. Chem. Mater.
1996, 8, 206.
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(
(
10) MacLachlan, M.; Coombs, N.; Ozin, G. A. Nature 1999, 397, 681.
11) Cahill, C. L.; Younghee, K.; Parise, J. B. Chem. Mater. 1998, 10, 19.
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2005, C61, m516.
1
0.1021/ic060263f CCC: $33.50
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 10, 2006 4261
Published on Web 04/22/2006

Powell et al.
-
2-
SbS
M(en)
2
and Sb
][Sb
4
S
7
5
infinite chains in [M(en)
3
2+
][Sb
ions reside
2
S
4
] and
Crystals of 2 and 3 were prepared under analogous conditions
and reagent concentrations. Transition-metal salts (for 2, NiSO
O (0.505 g, 1.8 mmol), and for 3, Co(O CCH (0.409 g, 1.65
mmol)) were mixed with the cyclam and deionized water, prior to
the addition of Sb and S. After the mixture had reacted for 4
days at 438 K and cooled at 20 K h , the solid product was isolated
as above. The product of the reaction containing NiSO ‚7H
4
‚
[
3
4
S
7
], respectively, while Co(en)
3
7
H
2
2
3 2
)
in one-dimensional channels and balance the charge of the
2
-
13
anionic Sb12
diethylenetriamine) complexes of iron and nickel fulfill a
6 10
similar role for the layered anions in [Fe(C ]Sb S ‚
S
19
3
framework in [Co(en) ][Sb12S19]. Bis-
2 3
S
(
-1
4
H
13
3
N )
2
4
2
O
17
18
0.5H
2
O, [Ni(C
4
13
H N
3
)
2
]Sb22
S
42‚0.5H
2
O, and [Ni(C
] and [Ni(C
anions and charge-balancing Ni-
4
H
4
H
13
N
3
)
2
]-
consisted of dark-yellow blocks of 2 as the major phase, together
with a small amount of black powder, identified by powder X-ray
diffraction as unreacted Sb S . Combustion analysis for the crystals
2 3
19
20
4
Sb S
7
‚H
2
O. In [Ni(C
4
H
13
N
3
)
2
]
2
4
[Sb S
8
13
N
3
)
2
]
3
-
2
1
z-
[
(
Sb
3
S
6
]
N
2
,
the Sb
x
S
y
2+
C
4
H
13
3
)
2
cations are isolated and held together by
of (2) gave C ) 12.12, H ) 2.32, and N ) 5.62% (calcd for formula
[Ni(C N H )][Sb S ]: C ) 12.38, H ) 2.49, and N ) 5.77%).
relatively weak secondary interactions, giving the materials
saltlike characteristics. Clearly in all such cases, the presence
of the transition-metal cation is an essential prerequisite for
the templating agent to exist, and formation of the corre-
sponding nonmetalated phase is impossible.
In this work, a macrocyclic tetramine has, for the first time,
been used as a structure-directing agent. Remarkably, we
have succeeded in preparing new three-dimensional antimony
sulfides containing 1,4,8,11-tetraazacyclotetradecane (cy-
clam) both as the protonated uncoordinated macrocycle in
10
4
24
4 7
The product from the reaction to which Co(O
2 3 2
CH ) was added
consisted of yellow blocks of 3 as the majority phase, together with
6
red blocks of [C
powder. The last was identified as a mixture of CoS
Sb by powder X-ray diffraction of the bulk product. Combustion
2
H
10
2
N ][Sb
8
S13] and a small amount of black
2
and unreacted
2 3
S
analysis of 3 was not performed because of the variation in Co
content between crystals that was established by analytical electron
microscopy (vide infra).
The hand-picked single crystals of 1, 2, and 3 were further
characterized by analytical electron microscopy and, for 1 and 2,
thermogravimetric analysis. Analytical electron microscopy was
carried out using a Philips XL30 scanning microscope equipped
with an EDAX “Phoenix” detection system. The Sb:S ratios of
[C
10
N
4
H
26][Sb
transition-metal cations in [Ni(C10
over, the third phase reported, [Co(C10
Sb ] (3), contains both metalated and nonmetalated forms.
4
S
7
] (1) and as a chelating complex with
24)][Sb ] (2). More-
24)]
4
N H
4 7
S
4
N H
x 4 26 1-x
[C10N H ] -
0
.59(3), 0.61(2), and 0.59(3) obtained for 1, 2, and 3, respectively,
[
4 7
S
are in good agreement with the value of 0.57 for the crystallographic
formulas determined below. For 2, all crystallites examined
contained Ni with an average Ni:S ratio of 0.14(1), corresponding
to a nickel site occupancy of 0.98(7). This is consistent, within
experimental error, with each cyclam macrocyclic ring containing
a nickel cation. However, for 3, a considerably larger variation in
the Co:S ratio was observed (ca. 0.01-0.1), indicative of partial
occupancy by cobalt of the site at the center of the macrocyclic
ring, over the range of 0.08-0.74. Although a number of additional
syntheses were carried out with varying reactant stoichiometries,
similar variations in cobalt content were observed in the products
of all reactions, which produced single crystals of 3. Thermogravi-
metric analysis was carried out using a Dupont Instruments 951
Thermal Analyzer. Approximately 4-5 mg of finely ground crystals
This work suggests that macrocycles, which do not show
any selectivity toward the complexation of transition-metal
ions in aqueous solution, may, when used as structure-
directing agents in framework-sulfide synthesis, provide a
means of combining the selectivity inherent in porous
structures with the narrow and tunable band gap of chalco-
1
genides, leading to multifunctional materials.
Experimental Section
Single crystals of [C10
2), and [Co(C10
under hydrothermal conditions. For 1, cyclam (0.300 g, 1.5 mmol),
Sb (0.679 g, 2 mmol), and S (0.160 g, 5 mmol) were stirred
N H26][Sb
4
4 7
S ] (1), [Ni(C10
4 4 7
N H24)][Sb S ]
(
N H24)]
4
x
[C10
N H
4 26
]
1-x[Sb ] (3) were prepared
4 7
S
2 3
S
with 3 mL of deionized water in a 23 mL Teflon-lined stainless
steel autoclave to give a mixture with an approximate molar
composition ratio for Sb:S:cyclam of 4:11:1.5. The mixture was
heated at 438 K for 4 days and cooled to room temperature at 20
of 1 and 2 were heated under a flow of dry nitrogen over the
-1
temperature range of 298-673 K at a heating rate of 15 K min
.
A single weight loss of 22.00% was observed for 1 (onset 558 K),
which compares very well with the value of 22.14% calculated for
the complete loss of the organic component. For 2, a single weight
loss of 18.67% occurs at T ) 606 K. The discrepancy between
this and the value of 20.64% expected for loss of the organic
component is accounted for by the observation that the product of
thermogravimetric analysis contained residual organic material
-
1
K h . The solid product was filtered, washed in deionized water
and acetone, and dried in air at room temperature. The product
contained yellow blocks of 1 as the major phase, a number of red
blocks, and a few orange blocks, together with a small amount of
black powder, that was identified by powder X-ray diffraction as
unreacted Sb
orange blocks as the new phase [C10
blocks as the previously reported [C
2 3
S . Single-crystal X-ray diffraction identified the
(2.98%), giving a total organic content of 20.65%. The powder
22
N
4
H
N
26][Sb
6
S
10
]
and the red
X-ray diffraction patterns of the thermal decomposition products
indicate that they are amorphous.
Crystal Structure Determination. X-ray intensity data
6
2
H
10
2
][Sb S13]. Combustion
8
analysis of a hand-picked sample of 1 found C ) 13.03, H ) 2.58,
and N ) 6.10%, in excellent agreement with values of C ) 13.14,
for [C10
Co(C10
N
4
H
26][Sb
4
S
N
7
]
(1), [Ni(C10
1-x[Sb
4 4 7
N H24)][Sb S ] (2), and
] (x ≈ 1/3) (3) were collected
H ) 2.87, and N ) 6.13%, calculated for the formula [C10
Sb ].
4
N H26]-
[
4
N H
24)] [C10
x
4
H
26
]
4
S
7
[
4 7
S
at 100 K, after rapid cooling from room temperature, using a
Bruker-AXS X8 Apex CCD diffractometer with graphite-mono-
chromated Mo KR radiation (λ ) 0.71073Å). Data were processed
(
(
(
17) St a¨ hler, R.; N a¨ ther, C.; Bensch, W. Eur. J. Inorg. Chem. 2001, 1835.
18) St a¨ hler, R.; Bensch, W. Z. Anorg. Allg. Chem. 2002, 628, 1657.
19) St a¨ hler, R.; N a¨ ther, C.; Bensch, W. J. Solid State Chem. 2003, 174,
23
using the manufacturer’s standard routines. Full crystallographic
264.
details are given in Table 1.
(
(
20) Bensch, W.; N a¨ ther, C.; St a¨ hler, R. Chem Commun. 2001, 477.
21) Kiebach, R.; Studt, F.; N a¨ ther, C.; Bensch, W. Eur. J. Inorg. Chem.
2
004, 2553.
22) Lattice parameters for [C10N4H26][Sb6S10] at 100 K: P21/c, a ) 9.4872-
9) Å, b ) 15.447(1) Å, c ) 10.7567(9) Å, and â ) 105.878(4)°.
(23) APEX-2, version 1.27; Bruker AXS Inc.: Madison, WI, 2005.
(24) Altomare, A.; Cascarano, G.; Giacovazzo, G.; Guagliardi, A.; Burla,
M. C.; Polidori, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27, 435.
(
(
4262 Inorganic Chemistry, Vol. 45, No. 10, 2006

Synthesis of 3D Antimony Sulfide Frameworks
Figure 1. Local coordination of (a) nontemplate atoms and (b) the carbon-nitrogen ring of the template in [C10N4H26][Sb4S7] (1), showing the atom
labeling scheme and ellipsoids at 50% probability.
Table 1. Crystallographic Data for [C10N4H26][Sb4S7] (1), [Ni(C10N4H24)][Sb4S7] (2), and [Co(C10N4H24)]x[C10N4H26]1-x[Sb4S7] (3)
1
2
3
formula
[C10H26N4][Sb4S7]
[Ni(C10N4H24)][Sb4S7]
[Co(C10N4H24)]x[C10N4H26]1-x
[
Sb4S7] (x ≈ 1/3)
Mr
913.88
970.55
933.51
crystal system
crystal habit
crystal dimensions (mm)
space group
T (K)
monoclinic
monoclinic
monoclinic
yellow block
C0 . 21 /2c × 0.12 × 0.05
dark yellow block
C0 . 21 /6c × 0.16 × 0.08
dark yellow block
C0 . 22 /0c × 0.16 × 0.04
100
100
100
a (Å)
b (Å)
c (Å)
13.7125 (5)
11.8863 (4)
15.4368 (6)
102.712 (2)
2454.39 (16)
4
4.957
2.473
32 291
3729
13.7781 (5)
11.8694 (5)
15.3855 (7)
102.772 (2)
2453.86 (18)
4
5.702
2.627
25 506
3733
13.6001(7)
11.9193(6)
15.4311(8)
102.557(3)
2441.6(2)
4
5.205
2.540
40 082
3704
2033
â (deg)
3
V (Å )
Z
µ (mm-1)
Fcalc (Mg m-3)
measured data
unique data
obsd data
2658
1879
(
I g 3σ(I))
Rint
0.031
0.052
0.047
residual electron
density (min, max) (e Å-3)
params refined
R(F)
-0.64, 1.20
-1.19, 0.95
-0.89, 0.79
114
0.0193
0.0199
120
0.0289
0.0324
121
0.0232
0.0257
Rw(F)
Table 2. Selected Bond Lengths (Å), Angles (deg), and Bond Valences
(
The structures were solved using the direct methods program
v.u.) for [C10N4H26][Sb4S7] (1)b
SIR92,24 and all non-hydrogen atoms were located. The CRYS-
TALS suite of programs25 was used for subsequent refinements
νa
i
i
i
against F. All the hydrogen atoms in 1 could be located in difference
Fourier maps but were placed geometrically during refinement.
Geometric placement was used from the start for the hydrogen
atoms in 2 and 3.
Sb(1)-S(2)
Sb(1)-S(1)
Sb(1)-S(1)
Sb(1)-S(4)
2.4883 (7) 0.893 S(2) -Sb(1)-S(1)
83.61 (2)
96.70 (2)
84.25 (2)
89.74 (2)
172.31(2)
i
i
3.0697 (7) 0.162 S(2) -Sb(1)-S(1)
i
2.4100 (7) 1.125 S(1) -Sb(1)-S(1)
i
2.5390 (6) 0.770 S(2) -Sb(1)-S(4)
i
∑
2.950 S(1) -Sb(1)-S(4)
In the final cycles of refinement, anisotropic thermal parameters
were refined for all non-hydrogen atoms. In 2 and 3, site-occupancy
factors of the transition metal were treated as refinable parameters
yielding final refined values of 0.953(6) and 0.339(5), respectively,
which are in good agreement with the conclusions reached from
the analytical electron microscopy.
Sb(2)-S(3)ii
Sb(2)-S(1)
Sb(2)-S(2)
Sb(2)-S(3)
2.7119 (8) 0.463 S(1)-Sb(1)-S(4)
92.72 (2)
ii
2.7520 (7) 0.411 S(3) -Sb(2)-S(1) 175.80 (2)
ii
2.4556 (7) 0.984 S(3) -Sb(2)-S(2)
88.19 (2)
91.32 (2)
86.94 (2)
89.09 (2)
102.30 (3)
2.3839 (7) 1.215 S(1)-Sb(2)-S(2)
ii
∑
3.073 S(3) -Sb(2)-S(3)
S(1)-Sb(2)-S(3)
S(2)-Sb(2)-S(3)
Results and Discussion
a
Bond valences and their sums calculated using parameters from ref
0. b Symmetry codes: (i) 2 - x, -y, 1 - z; (ii) 5/2 - x, 1/2 - y, 1 - z;
3
(
Figure 1 shows the local coordination of the framework
atoms of 1, and selected bond lengths and angles are
iii) 3/2 - x, 1/2 - y, 1 - z; (iv) 2 - x, y, 3/2 - z.
presented in Table 2. One of the two crystallographically
distinct antimony atoms in the asymmetric unit, Sb(1),
exhibits trigonal pyramidal coordination by sulfur with
(
25) Watkin, D. J.; Prout, C. K.; Carruthers, J. R.; Betteridge, P. W.; Cooper,
R. I. CRYSTALS, issue 11; Chemical Crystallography Laboratory,
University of Oxford: Oxford, U.K., 2001.
Inorganic Chemistry, Vol. 45, No. 10, 2006 4263

Powell et al.
Figure 2. Single Sb4S84- chain formed from the linkage of Sb4S108- units
through a common edge of the Sb(2)S4 polyhedra: antimony, large black
circles; sulfur, large open circles.
Sb(1)-S bond lengths in the range of 2.4100(7)-2.5390(6)
Å. In addition, in common with the majority of other
solvothermally prepared antimony sulfides, there is a further
Sb-S interaction at the longer distance of 3.0697(7) Å, which
is significantly less than the sum of the van der Waals' radii
26
of Sb and S. The coordination number of Sb(2) is however
four, with two short (2.3839(7) and 2.4556(7) Å) and two
longer (2.7119(8)-2.7520(7) Å) Sb-S bonds. Four-coordi-
nate Sb(III) atoms, with a similar combination of two short
and two somewhat longer Sb-S separations, have been
Figure 3. Linkage of Sb4S84- chains directed along [110] and [1-10]
2-
through S(4) in 1 to form a three-dimensional Sb4S7 network that defines
a system of mutually perpendicular channels in which diprotonated
macrocyclic cyclam cations reside: antimony, magenta; sulfur, yellow;
carbon, black; nitrogen, blue.
previously observed in a number of solvothermally synthe-
sized antimony sulfides.2
7,28,29
Bond-valence sums for Sb(1)
and Sb(2), calculated using the procedure of Brese and
O’Keeffe,30 are 2.95 and 3.07 v.u. respectively, consistent
Table 3. Selected Bond Lengths (Å), Angles (deg), and Bond Valences
(
[
v.u.) for [Ni(C10N4H24)][Sb4S7] (2) and
with the presence of Sb(III) in the framework.
Co(C10N4H24)]1/3[C10N4H26]2/3[Sb4S7] (3)b
3-
5-
Alternating vertex-linked Sb(1)S
3
and Sb(2)S
10 clusters, containing Sb rings. Adjacent
clusters are linked by sharing the two exocyclic sulfur atoms
4
units
(2)
(3)
8
-
generate Sb
4
S
4 4
S
νa
νa
Sb(1)-S(1)i
Sb(1)-S(1)
Sb(1)-S(4)
Sb(1)-S(2)
3.1091(17)
2.4127(16)
2.5155(15)
2.5002(17)
0.144
1.116
0.825
0.863
2.947
3.1018(12)
0.172
1.109
0.812
0.893
2.814
4-
attached to Sb(2) to form Sb
S
4 8
chains (Figure 2). The
2.4116(12)
2.5269(11)
2.4920(12)
S(4) atoms along the chain serve to link two sets of mutually
4
-
perpendicular Sb
S
4 8
chains into a three-dimensional struc-
2-
∑
∑
ture of stoichiometry Sb
4
S
7
(Figure 3). Along the crystal-
chains directed along [110] and
1-10] alternate and form a three-dimensional framework,
4-
lographic c axis, Sb
4
S
8
Sb(2)-S(1)i
Sb(2)-S(3)
Sb(2)-S(2)
Sb(2)-S(3)
2.7324(16)
2.7350(17)
2.4487(18)
2.3802(18)
0.436
0.432
1.004
1.228
3.100
2.7780(13)
2.6914(13)
2.4514(12)
2.3888(13)
0.412
0.521
0.996
1.182
3.112
ii
[
which defines a network of three mutually perpendicular
elliptical channels with approximate dimensions, measured
from S(1) to S(1)′ and S(2) to S(2)′, of 2.4 × 9.2 Å, when
the van der Waals’ radius of S is taken into account.
Macrocyclic cations, doubly protonated to balance the
charge of the antimony-sulfide framework, are located within
these channels and are oriented with their molecular plane
parallel to the channel direction. The location of hydrogen
atoms in the difference Fourier maps revealed that the double
protonation occurs at the two N(1) atoms of the macrocycle.
N‚‚‚S distances between the organic cation and sulfur atoms
of the framework lie in the range 3.324(3)-3.884(3) Å. This
is consistent with the presence of hydrogen bonding between
the organic and inorganic components.
∑
∑
i
S(1) -Sb(1)-S(1)
84.01 (5)
84.87(4)
i
S(1) -Sb(1)-S(4)
171.68 (3)
92.76 (5)
82.69 (5)
95.90 (6)
90.04 (5)
176.11 (5)
92.04 (5)
88.33 (6)
89.46 (5)
86.68 (6)
173.51(3)
93.06(4)
83.75(4)
96.41(4)
90.38(4)
175.28(4)
91.77(4)
88.35(4)
88.43(4)
86.93(4)
S(1)-Sb(1)-S(4)
i
S(1) -Sb(1)-S(2)
S(1)-Sb(1)-S(2)
S(4)-Sb(1)-S(2)
i
ii
S(1) -Sb(2)-S(3)
i
S(1) -Sb(2)-S(2)
ii
S(3) -Sb(2)-S(2)
i
S(1) -Sb(2)-S(3)
ii
S(3) -Sb(2)-S(3)
a
Bond valences and their sums calculated using parameters from ref
30. b Symmetry codes: (i) 2 - x, -y, -z; (ii) 3/2 - x, 1/2 - y, -z; (iii)
/2 - x, -1/2 - y, -z; (iv) 2 - x, y, 1/2 - z.
3
Reactions in the presence of transition-metal salts generate
essentially the same antimony-sulfide frameworks in 2 and
3
as described above for 1. Significant bond lengths and
angles are presented in Table 3.
In an analogous fashion to that of 1, the macrocyclic
cations in 2 and 3 are located in the channels created by the
(
(
(
26) Bondi, A. J. Phys. Chem. 1964, 68, 441.
27) Engelke, L.; N a¨ ther, C.; Bensch, W. Eur. J. Inorg. Chem. 2002, 2936.
28) Volk, K.; Bickert, P.; Kolmer, R.; Sch a¨ fer, H. Z. Naturforsch, Teil. B
4
-
intersecting Sb
S
4 8
chains and are also oriented with their
1979, 34, 380.
molecular planes approximately parallel to [1-10] (Figure
4). Both analytical electron microscopy and crystallographic
(29) Wang, X.; Liebau, F. J. Solid State Chem. 1994, 111, 385.
30) Brese, N. E.; O’Keeffe, M. Acta Crystallogr. 1991, B47, 192.
(
4264 Inorganic Chemistry, Vol. 45, No. 10, 2006

Synthesis of 3D Antimony Sulfide Frameworks
here had a cobalt occupancy of 0.339(5). Again the transition-
metal cation is four coordinate (Co-N ) 2.010(5) and
2
.0234(4) Å) with the nearest sulfur neighbors at 3.349(4)
Å. The partial occupancy of this site (0.339(5)) leads to
ambiguity in determining the oxidation state of the cobalt.
At this level of cobalt incorporation, neither Co2 nor Co
+
3+
would be sufficient to balance the negative charge of the
antimony-sulfide framework, and some degree of protona-
tion of the uncomplexed amine present is necessary.
Attempts to distinguish between the two possible oxidation
states using magnetic susceptibility measurements on hand-
picked single crystals were rendered ineffective by the
discovery of a magnetic-ordering transition at 113 K, which
3
2
2 c
was assigned to CoS (T ) 110 K). This trace ferromag-
netic impurity, which is present as a fine coating on the
crystals and therefore cannot be removed, dominates the
magnetic response making it impossible to distinguish by
2+
magnetic measurements between square-planar Co (S )
3
+
1
/2) and Co (S ) 0). In situ oxidation in the hydrothermal
3+
reaction would be required to generate a Co(cyclam)
2 3 2
complex from the Co(O CCH ) reactant. Indeed, examina-
tion of the literature indicates that in situ aerial oxidation is
required for the preparation of mononuclear cyclam com-
plexes of Co(III) from Co(II) reactants. Given the reducing
Figure 4. Space-filling representation of the Sb4S72- framework of [Ni-
(
C10N4H24)][Sb4S7] (2) illustrating one set of channels (parallel to [1-10])
2+
33
and showing the location of the Ni -chelate complex: antimony, magenta;
sulfur, yellow; carbon, black; nitrogen, blue; nickel, green.
environment resulting from the production of H
2
S as the
reaction proceeds, oxidation therefore appears to be unlikely
analysis are consistent with each macrocycle in 2 containing
2+
and hence we believe that the cobalt is present as Co , the
remaining positive charge being provided by protonation of
the noncoordinated ligand.
2
+
a Ni ion, which therefore balances the charge of the
framework, without the need for the macrocycle to be
protonated. The nickel cations are coordinated by the four
nitrogen atoms of the macrocycle with Ni-N distances of
To test this hypothesis further, [Co(cyclam)Cl
pared by a literature route involving aerial oxidation of an
2
]Cl, pre-
3
3
1.947(6) and 1.952(6) Å, slightly shorter than those in
acidified methanolic solution of CoCl O, was used as a
2
‚6H
2
discrete mononuclear complexes such as [Ni(cyclam)(O-
replacement (1.5 mmol) for Co(O CCH ) and cyclam in a
2
3 2
31
COR) ], (2.062(2)-2.074(2) Å). The nearest sulfur neigh-
2
solvothermal reaction analogous to that used for the prepara-
tion of 3. The solid product of this reaction contained crystals
bors are the two S(1) atoms of the framework above and
below the plane of the complex at the rather long distance
of 3.058(2) Å. This suggests that the Ni‚‚‚S interaction is
extremely weak (0.06 v.u.) and that the transition-metal
complex is therefore essentially square planar. This conclu-
sion is supported by room-temperature magnetic susceptibil-
ity measurements, which show the material to be diamagnetic
4 x 4 26 4 7
of [Co(C10N H24)] [C10N H ]1-x[Sb S ] (x ) 0.014(3) and
0
.011(3) from two single-crystal structure determinations),
while analytical electron microscopy revealed a significantly
lower cobalt content than that determined for 3: the average
Co:S ratio being only 0.02(2). UV-vis spectra (Figure 5)
of the liquid phase of the reaction mixture, recorded on a
Heλios Spectronic Unicam spectrometer, were measured
prior to and immediately following the reaction and com-
pared with a spectrum obtained from an aqueous solution
-
5
3
-1
(
(
ø
dia ≈ -4 × 10 cm mol ). The N‚‚‚S distances
3.424(6)-3.848(6) Å) are comparable with those in 1,
implying similar hydrogen bonding interactions between the
macrocyclic species and the antimony-sulfide framework.
The X-ray diffraction study of 3 produced a refined site-
occupancy factor for the cobalt ion that signifies that the
occupation of the site at the center of the macrocyclic ligand
is incomplete. The average cobalt content, taken over
crystallites in which the presence of cobalt was detected by
analytical electron microscopy, is 0.4(2). Crystal structure
analysis on five crystals selected from the same reaction
product yielded cobalt site-occupancy factors in the range
2
of Co(cyclam)Cl , also prepared using established proce-
dures. The Co(cyclam)3+ complex in the initial reaction
mixture is characterized by bands at 650 and 450 nm. After
the reaction, these bands disappear completely. Although no
peak is discernible in the post-reaction mother liquor,
differential analysis of the spectrum identifies a feature at
34
5
38 nm, which compares favorably with the broad absorption
2
+
at 533 nm in the spectrum of the Co(cyclam) complex in
aqueous solution. We believe that the spectroscopic evidence
0.213(4)-0.385(3), consistent with the presence of both
metalated and nonmetalated forms of the macrocyclic species
in the same crystal. The crystal for which details are reported
(32) Goodenough, J. B. Magnetism and the Chemical Bond; Wiley: New
York, 1963.
(
33) Bosnich, B.; Poon, C. K.; Tobe, M. L. Inorg. Chem. 1965, 4, 1102.
(
31) Zakaria, C. M.; Ferguson, G.; Lough, A. J.; Glidewell, C. Acta
Crystallogr. 2002, B58, 78.
(34) Prakash, R.; Kandoi, S.; Srivastava, R. Trans. Met. Chem. 2002, 27,
598.
Inorganic Chemistry, Vol. 45, No. 10, 2006 4265

Powell et al.
mixtures. No evidence for the formation of nickel-sulfide
phases was observed in the powder X-ray patterns of the
products containing 2. However, the heterogeneous mixture
that constitutes a solvothermal reaction inevitably entails a
complex series of equilibria, as shown by the fact that using
a salt of the transition-metal macrocycle complex as the
source of transition metal and cyclam in the solvothermal
reaction does not generally lead to products in which the
degree of metal occupancy is complete. We are currently
seeking to optimize reactions involving transition-metal ions
other than cobalt and nickel in an effort to generate phases
with higher levels of metal incorporation, a narrower spread
of values, or both and will report on these in due course.
A striking feature of the three products reported here is
the formation of a genuine three-dimensional structure,
through the linkage of one-dimensional chains. Antimony
sulfides typically exhibit a wide range of Sb-S distances
(
2.38-3.7 Å). Primary antimony-sulfur bonding distances
3-
are quite well defined: Sb-S distances in SbS
units are typically <2.5 Å, while those in SbS
3
building
5
-
4
units
containing two long and two short bonds, may extend to 2.8
Å. Longer secondary interactions in the range of 3.0-3.7 Å
have also been invoked to link together higher structural
units, although it should be noted that the contribution to
the valence sum falls dramatically from 1.1 for an Sb-S
bond of 2.4 Å to 0.4 at 2.8 Å and 0.1 at 3.2 Å. Thus
consideration of only Sb-S distances < 2.8 Å leads to the
identification of a wide range of chainlike structural motifs
among solvothermally prepared antimony sulfides, especially
Figure 5. UV-vis spectra of Co(cyclam)3 (a) before and (b) after
solvothermal reaction with Sb2S3 and S for 24 h and (c) the UV-vis
spectrum of an aqueous solution of Co(cyclam)Cl2.
+
demonstrates that the Co(III)-cyclam complex is not stable
under the conditions of the reaction and therefore oxidation
2
+
3+
of Co to Co does not occur. Final evidence for the
presence of Co(II) is provided by analytical electron mi-
croscopy data which reveal the presence of crystallites with
Co:S ratios as high as 0.105. This corresponds to a site
occupancy of 0.74, which for Co(III) would result in an
excess of positive charge. Hence, 3 is formulated as Co(II)-
3
-
36
those consisting of vertex-linked SbS
3
pyramidal units.
Structures of higher dimensionality generally only result from
z-
the interlocking of Sb
S
x y
units by considering weaker (>2.8
7,19,29
Å) secondary Sb-S interactions.
The three-dimensional
framework defined by antimony-sulfur bonds of <2.8 Å,
as found in the materials reported here, is therefore highly
unusual and represents only the second example, after [Co-
4 x 4 26 4 7
containing [Co(C10N H24)] [C10N H ]1-x[Sb S ] (0.08 e x
e 0.74) with the charge balance being achieved through
double protonation of the noncomplexed macrocycle.
Measured stability constants for transition-metal cyclam
1
3
(
3
en) ][Sb12S19], of what we believe to be a truly three-
dimensional system.
2
+
complexes, M(cyclam) are very high (log K ) 11.3 to
7.2),35 suggesting that differences in the stability of the
In summary, we have prepared the first members of a new
series of macrocycle-templated antimony sulfides that adopt
three-dimensional framework structures. This family repre-
sents a unique situation in antimony-sulfide chemistry, in
which a structure-directing agent can generate both metalated
and nonmetalated forms of the cationic species within
identical anionic antimony-sulfide frameworks. The persis-
tence of the framework into the metalated form suggests that
this class of material may have applications as selective
absorbents. In particular, the fact that access to the macro-
cycle in the noncomplexed form is restricted by the channel
structure of the framework, may overcome the practical
difficulties in using macrocyclic polyamines as selective
metal-chelating agents because of the high stabilities of their
complexes with most metal cations.
2
transition-metal cyclam complexes do not play a significant
role in determining the degree of metal incorporation in the
phases reported here. This is further supported by our
2 2 3
observations that introduction of FeCl into the Sb S /S/
cyclam reaction mixture produces single crystals of the same
framework structure, with a lower metal content than for
the cobalt-containing phase (among the 25% of examined
crystals that contain iron, the maximum Fe:S ratio corre-
sponds to an iron site occupancy of ca. 0.20), while the
‚2H O leads to copper oc-
2
cupancies that vary over the wide range from 0.2 to 1.0,
despite the stability constant for Cu(cyclam)2+ being among
analogous reaction with CuCl
2
the highest reported. Therefore, we believe that the lower
level of cobalt incorporation in 3 compared to that of nickel
in 2 is related to the ease of formation of the pyrite phase,
Acknowledgment. The authors thank the U.K. EPSRC
for grants in support of a single-crystal CCD diffractometer
2
CoS , which effectively removes cobalt from the reaction
(
35) Martell, A. E.; Hancock, R. D.; Motekaitis, R. J. Coord. Chem. ReV.
1994, 133, 39.
(36) Sheldrick, W. S. J. Chem. Soc., Dalton Trans. 2000, 3041.
4266 Inorganic Chemistry, Vol. 45, No. 10, 2006

Synthesis of 3D Antimony Sulfide Frameworks
and a studentship for R.J.E.L. A.M.C. thanks The Lever-
hulme Trust for a Research Fellowship.
coordinates, bond distances and angles, and anisotropic thermal
parameters for 1, 2, and 3. This material is available free of charge
via the Internet at http://pubs.acs.org.
Supporting Information Available: Thermogravimetric data
for 1 and 2, and CIFs and listings of crystallographic data, atomic
IC060263F
Inorganic Chemistry, Vol. 45, No. 10, 2006 4267