Influence of the reaction conditions on the self-assembly of lead(II) 5-sulfosalicylate coordination polymers with chelating amine ligands

Article abstract of DOI:10.1021/ic060871v

The synthesis and crystal structures of [Pb(Hssal)(2,2′-bipy)(DMF)] _n (1), [Pb(Hssal)(2,2′-bipy)(H₂O)]_n (2), [Pb(Hssal)-(phen)(DMF)]_n (3), and [Pb₃(ssal) ₂(phen)₃]_n (4) were reported, where Hssal ^2- and ssal^3- are doubly and fully deprotonated 5-sulfosalicylates, 2,2′-bipy is 2,2′-bipyridine, and phen is 1,10-phenanthroline. Compounds 1-4 were synthesized by the various reaction conditions, such as reaction temperature, molar ratio, and pH, and these structures are formed by infinite chains or layers where Pb^II ions are linked by Hssal^2- or ssal^3- bridges. Compound 1, which has a ladderlike chain, was formed in DMF/H₂O. Compound 2 with a H₂O molecule coordinated to Pb^II was prepared by a hydrothermal reaction. Compounds 3 and 4 were synthesized in a higher pH compared to compounds 1 and 2, containing the 2,2′-bipy ligand. In 1-3, 5-sulfosalicylates are doubly deprotonated, whereas in 4,5-sulfosalicylate is fully deprotonated. Coordination modes of Hssal^2- and ssal ^3- ligands in 1-4 are novel and are first reported in this presentation. Although compounds 1 and 3 have the same structural topology, their aromatic-aromatic interactions are significantly different. The coordination spheres of Pb^II ions in 1 and 3 are holodirected, whereas in 2 and 4, they feature somewhat hemidirected properties with small holes or gaps. Compound 4 exhibits some interesting features that (1) there is not any solvent in the structure, (2) there are extensively aromatic-aromatic stacking interactions among aromatic rings, and (3) there is also a weak interaction between Pb^II atoms in the trinuclear motif.

Full text of DOI:10.1021/ic060871v

Inorg. Chem. 2006, 45, 7935−7942
Influence of the Reaction Conditions on the Self-assembly of Lead(II)
5-Sulfosalicylate Coordination Polymers with Chelating Amine Ligands
Sai-Rong Fan and Long-Guan Zhu*
Department of Chemistry, Zhejiang UniVersity, Hangzhou 310027, People’s Republic of China
Received May 19, 2006
The synthesis and crystal structures of [Pb(Hssal)(2,2
′
-bipy)(DMF)]n (1), [Pb(Hssal)(2,2
′
-bipy)(H2O)]n (2), [Pb(Hssal)-
-
-
(phen)(DMF)]n (3), and [Pb3(ssal)2(phen)3]n (4) were reported, where Hssal2 and ssal3 are doubly and fully
deprotonated 5-sulfosalicylates, 2,2′-bipy is 2,2′-bipyridine, and phen is 1,10-phenanthroline. Compounds 1−4 were
synthesized by the various reaction conditions, such as reaction temperature, molar ratio, and pH, and these
structures are formed by infinite chains or layers where PbII ions are linked by Hssal2- or ssal3- bridges. Compound
1, which has a ladderlike chain, was formed in DMF/H2O. Compound 2 with a H2O molecule coordinated to PbII
was prepared by a hydrothermal reaction. Compounds 3 and 4 were synthesized in a higher pH compared to
compounds 1 and 2, containing the 2,2
′-bipy ligand. In 1−3, 5-sulfosalicylates are doubly deprotonated, whereas
-
-
in 4, 5-sulfosalicylate is fully deprotonated. Coordination modes of Hssal2 and ssal3 ligands in 1
−4 are novel and
are first reported in this presentation. Although compounds 1 and 3 have the same structural topology, their aromatic
−
aromatic interactions are significantly different. The coordination spheres of PbII ions in 1 and 3 are holodirected,
whereas in 2 and 4, they feature somewhat hemidirected properties with small holes or gaps. Compound 4 exhibits
some interesting features that (1) there is not any solvent in the structure, (2) there are extensively aromatic
−
aromatic stacking interactions among aromatic rings, and (3) there is also a weak interaction between PbII atoms
in the trinuclear motif.
Introduction
classified as a hemi- or holodirected configuration,9 which
is important in structural assembly, electron charge transfer,
and physical or chemical properties.9-12 Therefore, the
combination of PbII and 5-sulfosalicylate was used to study
the configuration activity of valence-shell electron lone pairs
and their diverse structural topologies. To the best of our
Recently, increasing attention has been devoted to the
coordination chemistry of 5-sulfosalicylic acid (H3ssal) in
both structural and biological interests.1,2 5-Sulfosalicylic acid
possesses three functional groups, -SO3H, -COOH, and
-OH, and can be partly (H2ssal- and Hssal2-) or fully
(ssal3-) deprotonated, which can perform a wide range of
coordination modes. Charts 1 and 2 demonstrate the coor-
dination modes of the doubly and fully deprotonated 5-
sulfosalicylates in recently reported metal complexes,
respectively.3,4 On the other hand, PbII complexes have been
increasingly studied owing to their interests in environmental
protection and as a stereochemically active lone pair of
electrons;5-8 the coordination sphere of the PbII ion can be
(3) (a) Li, J. F.; Zhao, Y. J.; Li, X. H.; Hu, M. L. Acta Crystallogr. 2004,
E60, m1210. (b) Hecht, E. Acta Crystallogr. 2004, E60, m1286. (c)
Chen, Z. F.; Shi, S. M.; Hu, R. X.; Zhang, M.; Liang, H.; Zhou, Z. Y.
Chin. J. Chem. 2003, 21, 1059. (d) Fan, S. R.; Xiao, H. P.; Zhu, L. G.
Acta Crystallogr. 2006, E62, m18. (e) Fan, S. R.; Zhu, L. G. Acta
Crystallogr. 2005, E61, m2480. (f) Fan, S. R.; Zhu, L. G.; Xiao, H.
P.; Ng, S. W. Acta Crystallogr. 2005, E61, m377. (g) Ma, W. X.;
Qian, B. H.; Gao, J.; Xu, X. Y.; Lu, L. D.; Yang, X. J.; Wang, X.;
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J.; Li, S. L.; Song, S. Y.; Zhang, H. J.; Wang, H. S.; Yang, K. Y.
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* To whom correspondence should be addressed. E-mail: chezlg@
zju.edu.cn. Fax: +86-571-87951895. Tel: +86-571-87963867.
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Inorg. Chem. Commun. 2003, 6, 581. (c) Marzotto, A.; Clemente, D.
A.; Gerola, T.; Valle, G. Polyhedron 2001, 20, 1079.
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Chem. 2003, 172, 45. (b) Zheng, S. L.; Tong, M. L.; Zhu, H. L.; Fang,
Y.; Chen, X. M. J. Chem. Soc., Dalton Trans. 2001, 2049.
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Crystallogr. 2005, E61, m174. (d) Wang, X. Q.; Zhang, J.; Li, Z. J.;
Wen, Y. H.; Cheng, J. K.; Yao, Y. G. Acta Crystallogr. 2004, C60,
m657. (e) Fan, S. R.; Cai, G. Q.; Zhu, L. G.; Xiao, H. P. Acta
Crystallogr. 2005, C61, m177. (f) Liu, B.; Wang, Z. J.; Huang, S. P.;
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10.1021/ic060871v CCC: $33.50
Published on Web 08/25/2006
© 2006 American Chemical Society
Inorganic Chemistry, Vol. 45, No. 19, 2006 7935

Fan and Zhu
Chart 1. Coordination Modes of Doubly Deprotonated 5-Sulfosalicylates in Recent Reports
Chart 2. Coordination Modes of Fully Deprotonated 5-Sulfosalicylates in Recent Reports
knowledge, only one PbII complex with the H3ssal ligand
was reported, [Pb(Hssal)(phen)(H2O)]2 (5).3a Hence, in the
past 3 years, we have paid our attention to the synthesis of
lead(II) 5-sulfosalicylate compounds with chelating aromatic
amine ligands [2,2′-bipyridine (2,2′-bipy) and 1,10-phen-
anthroline (phen)] but have compositional and structural
diversity. Herein, we present syntheses, structures, properties,
and weak interactions of four polymeric PbII complexes
synthesized by various reaction conditions, namely, [Pb-
(Hssal)(2,2′-bipy)(DMF)]n (1), [Pb(Hssal)(2,2′-bipy)(H2O)]n
(2), [Pb(Hssal)(phen)(DMF)]n (3), and [Pb3(ssal)2(phen)3]n
(4).
(5) (a) Shimoni-Livny, L.; Glusker, J. P.; Bock, C. W. Inorg. Chem. 1998,
37, 1853. (b) Parr, J. Polyhedron 1997, 16, 551.
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D. F.; Rous, B. W.; Payne, J. C.; Bridgewater, B. M.; Mijovilovich,
A.; Parkin, G.; Zaleski, J. M.; Penner-Hahn, J. E.; Godwin, H. A. J.
Am. Chem. Soc. 2005, 127, 9495. (c) Ambrosi, G.; Formica, M.; Fusi,
V.; Giorgi, L.; Guerri, A.; Micheloni, M.; Paoli, P.; Pontellini, R.;
Rossi, P. Inorg. Chim. Acta 2003, 356, 203. (d) Kurtaran, R.; Yildirim,
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44, 2573.
Experimental Section
Materials and Instruments. All chemicals were purchased from
Acros Organics and were used as received without purification.
Microanalyses (C, H, and N) were carried out on a Perkin-Elmer
analyzer model 1110. IR spectra were recorded as KBr pellets in
the 400-4000-cm-1 region using a Nicolet Nexus 470 spectro-
(9) Hancock, R. D.; Reibenspies, J. H.; Maumela, H. Inorg. Chem. 2004,
43, 2981.
(10) Nordell, K. J.; Schultz, K. N.; Higgins, K. A.; Smith, M. D. Polyhedron
2004, 23, 2161.
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F.; Platas-lglesias, C.; de Blas, A.; Rodriguez-Blas, T. Inorg. Chem.
2005, 44, 5428.
7936 Inorganic Chemistry, Vol. 45, No. 19, 2006

Self-assembly of Lead(II) 5-Sulfosalicylate
photometer. Thermogravimetric analyses (TGA) were studied by
a Delta Series TA-SDT Q600 in a N2 atmosphere in the temperature
range between room temperature and 500 °C (heating rate ) 10
°C‚min-1) using Al crucibles. The photoluminescence study was
carried out on a powdered sample in the solid state at room
temperature using a Hitachi 850 spectrometer.
Synthesis of [Pb(Hssal)(2,2′-bipy)(DMF)]n (1). A mixture of
Pb(CH3COO)2‚3H2O (0.097 g, 0.26 mmol), 5-sulfosalicylic acid
dihydrate (0.130 g, 0.51 mmol), and 2,2′-bipy (0.031 g, 0.20 mmol)
in a solution of water (10 mL) and dimethylformamide (DMF; 20
mL) was vigorously stirred for 4 h. The resulting solution (pH )
3.2) was filtered and allowed to slowly evaporate. After 1 week,
colorless block-shaped crystals were obtained. Yield: 69% based
on Pb salt. Anal. Calcd for C20H19N3O7PbS: C, 36.81; H, 2.93; N,
6.44. Found: C, 36.94; H, 3.01; N, 6.41. IR (KBr pellet, cm-1):
3405(m), 3065(w), 1632(m), 1590(s), 1574(s), 1490(m), 1478(m),
1439(s), 1388(m), 1316(w), 1212(s), 1178(s), 1127(m), 1084(m),
1035(s), 1010(m), 824(m), 773(s), 733(w), 676(s), 646(m), 602(s),
586(m), 406(w).
Synthesis of [Pb(Hssal)(2,2′-bipy)(H2O)]n (2). A mixture of
Pb(CH3COO)2‚3H2O (0.077 g, 0.20 mmol), 5-sulfosalicylic acid
dihydrate (0.051 g, 0.20 mmol), 2,2′-bipy (0.031 g, 0.20 mmol),
and water (10 mL) was placed in a 25-mL Teflon-lined reaction
vessel (pH ) 3.7) and heated under autogenous pressure at 413 K
for 3 days. The vessel was then slowly cooled to room temperature.
Several hours later needle crystals were grown from the resulting
pink solution. Yield: 87% based on Pb salt. Anal. Calcd for
C17H14N2O7PbS: C, 34.17; H, 2.36; N, 4.69. Found: C, 34.31; H,
2.56; N, 4.78. IR (KBr pellet, cm-1): 3399(m), 3103(m), 1619(m),
1590(s), 1478(m), 1438(s), 1374(w), 1350(w), 1321(m), 1246(m),
1211(s), 1197(s), 1179(m), 1160(s), 1127(s), 1077(m), 1031(s),
1009(m), 895(w), 847(w), 818(w), 764(m), 734(m), 672(s), 643(w),
596(s), 569(w), 451(w), 407(m).
Synthesis of [Pb(Hssal)(phen)(DMF)]n (3). Pb(CH3COO)2‚
3H2O (0.181 g, 0.48 mmol) and 1,10-phenanthroline monohydrate
(0.101 g, 0.51 mmol) were dissolved in DMF (20 mL), and
5-sulfosalicylic acid dihydrate (0.126 g, 0.50 mmol) and NaOH
(0.021 g, 0.53 mmol) were dissolved in water (10 mL). Then the
solutions with pH ) 5.9 were mixed and allowed to evaporate.
After 5 days, colorless block crystals were obtained. Yield: 75%
based on Pb salt. Anal. Calcd for C22H19N3O7PbS: C, 39.05; H,
2.83; N, 6.21. Found: C, 39.07; H, 2.77; N, 6.20. IR (KBr pellet,
cm-1): 3448(w), 3059(w), 2926(w), 1661(s), 1620(m), 1577(s),
1571(w), 1476(m), 1446(s), 1432(m), 1387(w), 1375(w), 1338(m),
1298(w), 1257(m), 1233(m), 1207(w), 1159(s), 1120(m), 1097(m),
1074(m), 1035(m), 1018(s), 895(w), 855(m), 820(w), 730(m),
668(m), 596(s), 567(w), 405(w).
with graphite-monochromatized Mo KR radiation (λ ) 0.710 73
Å). The data were integrated by use of the SAINT program,13 and
this program also did the intensities corrected for Lorentz and
polarization effects. The absorption was done by the SADABS
program.14 The structures were solved by the heavy-atom method
and successive Fourier syntheses. Once the heavy-atom peak had
been located in the Patterson map, a Fourier synthesis was
performed to locate the other non-H atoms. Full-matrix least-squares
refinements on F2 were carried out using the SHELXL-97 package.15
All non-H atoms were anisotropically refined. In compound 2, the
atom O5 is disordered and was refined using a separate partial
model. H atoms on C atoms were placed in idealized positions and
refined as riding atoms, with C-H ) 0.93 Å and Uiso(H) )
1.2Ueq(C). H atoms bound to O atoms were located in difference
Fourier maps and refined with distance restraints of O-H ) 0.85(1)
Å and a fixed isotropic displacement parameter of Uiso(H) ) 0.08
Å2. The drawings of the molecules were realized with the help of
ORTEP-3 for Windows. All of the programs used are included in
the WinGX Suite with version 1.70.16 Information concerning the
crystallographic data collection and structure refinements is sum-
marized in Table 1.
Results and Discussion
Reaction Chemistry. Initially, compound 1, which as-
sociates with the coordination of the DMF molecule, was
synthesized in DMF/H2O by a typical solution-mixed
method. Self-assembled frameworks largely depend on the
synthesis conditions, such as starting materials, solvents,
reaction temperature, pH, and molar ratio.17-19 Therefore,
we tried to replace DMF in 1 by other solvents to produce
new frameworks, such as methanol, while in the mixed
solvents of MeOH/H2O used in the Pb2+/2,2′-bipy/H3ssal
system, there are no suitable crystals precipitated, and only
poor-quality crystals or cotton-like solids formed, which are
different from compound 1 and subsequent compound 2
(confirmed by IR). Then hydrothermal synthesis was intro-
duced into the Pb2+/2,2′-bipy/H3ssal system, resulting in the
formation of compound 2. Following the successful synthesis
of compounds 1 and 2, many tries for the Pb2+/phen/H3ssal
system in DMF/H2O or MeOH/H2O at room temperature
only formed the previously reported dimeric compound
(confirmed by IR and single-crystal X-ray analysis) 5,3a and
further investigations on this system using dimethyl sulfox-
ide, methanol, ethanol, or their combination by a typical
mixed solution method or (solvo)hydrothermal reaction
yielded nothing but the dimeric compound 5 (confirmed by
IR). Therefore, a new idea, largely changing the solution
pH, was employed in the synthesis of new compounds based
Synthesis of [Pb3(ssal)2(phen)3]n (4). A mixture of Pb(CH3-
COO)2‚3H2O (0.077 g, 0.20 mmol), 5-sulfosalicylic acid dihydrate
(0.050 g, 0.20 mmol), 1,10-phenanthroline monohydrate (0.041 g,
0.021 mmol), NaOH (0.025 g, 0.63 mmol), and water (10 mL) was
heated in a 25-mL Teflon-lined reaction vessel (pH ) 6.1) at 433
K for 3 days. The vessel was then slowly cooled to room
temperature. Yellow block crystals were isolated by filtration.
Yield: 81% based on Pb salt. Anal. Calcd for C50H30N6O12Pb3S:
C, 37.71; H, 1.90; N, 5.28. Found: C, 37.72; H, 1.74; N, 5.33. IR
(KBr pellet, cm-1): 3456(m), 3053(m), 1588(s), 1561(s), 1538(s),
1512(s), 1458(s), 1424(s), 1375(m), 1313(s), 1247(s), 1149(s), 1117-
(s), 1097(m), 1078(m), 1015(s), 998(s), 906(w), 850(m), 840(m),
816(w), 803(w), 724(s), 661(m), 636(w), 596(s), 576(m), 415(w).
Single-Crystal Structure Determination. Crystals directly
grown from the reaction medium with suitable sizes of 1-4 were
selected for data collection by a Bruker Smart CCD area detector
(13) SAINT, version 6.02a; Bruker AXS Inc.: Madison, WI, 2002.
(14) Sheldrick, G. M. SADABS, Program for Bruker Area Detector
Absorption Correction; University of Go¨ttingen: Go¨ttingen, Germany,
1997.
(15) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(16) Farrugia, L. J. Appl. Crystallogr. 1999, 32, 837.
(17) (a) Go, Y. B.; Wang, X. Q.; Anokhina, E. A.; Jacobson, A. J. Inorg.
Chem. 2005, 44, 8265. (b) Go, Y. B.; Wang, X. Q.; Anokihina, E. V.;
Jacobson, A. J. Inorg. Chem. 2004, 43, 5360.
(18) Diaz, P.; Benet-Buchholz, J.; Vilar, R.; White, A. J. P. Inorg. Chem.
2006, 45, 1617.
(19) Lu, Y. L.; Wu, J. Y.; Chan, M. C.; Huang, S. M.; Lin, C. S.; Chiu, T.
W.; Liu, Y. H.; Wen, Y. S.; Ueng, C. H.; Chin, T. M.; Huang, C. H.;
Lu, K. L. Inorg. Chem. 2006, 45, 2430.
Inorganic Chemistry, Vol. 45, No. 19, 2006 7937

Fan and Zhu
Table 1. Crystallographic Data and Refinement Parameters for Compounds 1-4
compound
1
2
3
4
empirical formula
Mr
C20H19N3O7PbS
652.63
0.15 × 0.26 × 0.28
monoclinic
P2(1)/n
11.4282(7)
16.1696(9)
11.5471(7)
90.00
91.530(1)
90.00
2133.02(2)
4
2.03
8.056
2.2-26.1
4227
C17H14N2O7PbS
597.55
0.11 × 0.14 × 0.37
monoclinic
P2(1)/c
12.487(1)
7.7435(6)
18.6162(15)
90.00
99.537(1)
90.00
1775.18(4)
4
2.24
9.667
2.8-25.6
3332
C22H19N3O7PbS
676.65
0.17 × 0.18 × 0.49
monoclinic
P2(1)/n
11.4005(5)
15.2010(7)
12.6626(6)
90.00
94.627(1)
90.00
2187.26(2)
4
2.05
7.861
2.1-25.5
4057
C50H30N6O12Pb3S2
1592.49
0.23 × 0.26 × 0.39
monoclinic
P2(1)/c
11.7889(7)
21.5596(12)
18.6853(10)
90.00
106.247(1)
90.00
4559.47(15)
4
cryst size (mm3)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (A3)
Z
Dc (g‚m-3
)
2.32
11.216
1.5-25.5
8455
µ (mm-1
θ range
)
unique reflns
obsd reflns
3713
3005
3632
7085
no. of param
F(100)
292
1256
280
1136
310
1304
658
2983
T (K)
293 ( 2
0.024, 0.056
0.029, 0.058
1.037
293 ( 2
0.022, 0.053
0.026, 0.054
1.057
293 ( 2
0.022, 0.055
0.026, 0.056
1.080
293 ( 2
0.031, 0.073
0.040, 0.077
1.063
R1, wR2 [I > 2σ(I)]
R1, wR2 [all data]
GOF
largest peak and hole (e‚Å-3
)
0.753, -0.683
0.737, -0.627
0.970, -0.393
0.794, -1.288
band around 3400 cm-1 indicates the presence of a coordi-
nated H2O molecule. The IR spectra of 1-3 and 5 show
typical asymmetric and symmetric carboxylate stretching
bands at 1574 and 1388 cm-1 for 1, at 1590 and 1321 cm-1
for 2, at 1577 and 1387 cm-1 for 3, and at 1574 and 1347
cm-1 for 5, respectively. Unexpectedly, asymmetric and
symmetric carboxylate stretching bands in 4 occur at 1561
and 1538 cm-1 and at 1424 and 1375 cm-1, indicating that
the carboxylates act as chelating-bridging coordination
Scheme 1
-
modes. The characteristic vibrations of SO3 in 1-5 are at
1212, 1178, and 1127 cm-1 in 1, at 1211, 1179, and 1127
cm-1 in 2, at 1233, 1159, and 1120 cm-1 in 3, at 1247, 1149,
and 1117 cm-1 in 4, and at 1211, 1179, and 1127 cm-1 in 5
for νas(SO3), respectively, whereas they are at 1035 cm-1 in
1, at 1031 cm-1 in 2, at 1035 cm-1 in 3, at 1015 and 998
cm-1 in 4, and at 1034 cm-1 in 5 for νas(SO3), respectively.
Description of the Molecular Structures. Single-crystal
X-ray analyses revealed that compounds 1 and 3 are
isostructural. These two crystal structures demonstrate them
to be 1-D ladderlike polymers. In 1 and 3, each PbII atom is
heptacoordinated by two N donors from one aromatic amine
ligand (2,2′-bipy in 1 and phen in 3), four O atoms from
three Hssal2- ligands, and one DMF molecule (Figures 1
and 2). The selected bond distances and angles for 1 and 3
are listed in Table 2. The average distances of Pb-N in 1
and 3 are 2.494(3) and 2.507(3) Å, respectively, which are
in good agreement with the reported values.20-25 The
carboxyl group of each Hssal2- ligand chelates to the Pb
on the Pb2+/phen/H3ssal system. As expected, compounds 3
and 4 under the addition of NaOH were obtained by a typical
solution-mixed method and hydrothermal reaction, respec-
tively. These compounds are insoluble in water and common
organic solvents, such as methanol, ethanol, acetone, and
DMF. Therefore, crystals used for data collection were
directly grown from the reaction medium. The pH values in
the syntheses of compounds 1-4 need not be very precise,
but the procedures reported in this presentation are suitable
for the formation of good-quality crystals. The formation
pathway of compounds 1-5 is shown in Scheme 1.
IR Spectra. In the spectra of compounds 1-5, both
COOH and SO3H characteristic peaks near 1680 cm-1 are
absent, indicating that these functional groups are deproto-
nated. In the region where ν(O-H) phenoxo deformation
occurs, two absorption bands are observed at 1478 and 1439
cm-1 for 1, at 1478 and 1438 cm-1 for 2, at 1476 and 1446
cm-1 for 3, and at 1487 and 1447 cm-1 for 5, respectively.
Compound 4 lacks such similar peaks. In a recent reference,3c
a peak near 1627 cm-1, which also occurs at 1632 cm-1 in
1, at 1619 cm-1 in 2, at 1620 cm-1 in 3, and at 1629 cm-1
in 5, was attributed to the ν(C-C) vibration, but this peak
is absent in compound 4; therefore, such a peak may be
attributed to the vibration of O-H (Hssal2-). In the IR spectra
of 2 and 5, the ν(O-H) stretching frequency of the broad
(20) Shi, Y. J.; Li, L. H.; Li, Y. Z.; Chen, X. T.; Xue, Z. L.; You, X. Z.
Polyhedron 2003, 22, 917.
(21) Soudi, A. A.; Marandi, F.; Morsali, A.; Zhu, L. G. Inorg. Chem.
Commun. 2005, 8, 773.
(22) Tandon, S. S.; Mckee, V. J. Chem. Soc., Dalton Trans. 1989, 19.
(23) Bazzicalupi, C.; Benicini, A.; Fusi, V.; Giorgi, C.; Paoletti, P.;
Valtancoli, B. J. Chem. Soc., Dalton Trans. 1999, 393.
(24) Tei, L.; Blake, A. J.; Bencini, A.; Valtancoli, B.; Wilson, C.; Schroder,
M. Inorg. Chim. Acta 2002, 337, 59.
7938 Inorganic Chemistry, Vol. 45, No. 19, 2006

Self-assembly of Lead(II) 5-Sulfosalicylate
Table 2. Selected Bond Lengths (Å) and Angles (deg) for Compounds
1-4a
Compound 1
Pb1-O1
Pb1-O4i
Pb1-O7
Pb1-N2
2.493(3)
2.616(3)
2.692(3)
2.465(3)
Pb1-O2
Pb1-O5ii
Pb1-N1
2.766(3)
2.929(3)
2.523(3)
O1-Pb1-O2
O1-Pb1-O5ii
O1-Pb1-N1
O4i-Pb1-O2
O7-Pb1-O2
N2-Pb1-O2
O4i-Pb1-O7
N2-Pb1-O4i
N1-Pb1-O5ii
N1-Pb1-O7
N2-Pb1-N1
49.32(8)
O1-Pb1-O4i
O1-Pb1-O7
N2-Pb1-O1
O2-Pb1-O5ii
N1-Pb1-O2
O4i-Pb1-O5ii
N1-Pb1-O4i
O7-Pb1-O5ii
N2-Pb1-O5ii
N2-Pb1-O7
146.56(9)
126.79(10)
91.08(11)
117.98(9)
105.28(11)
94.55(9)
74.02(10)
124.76(10)
149.18(9)
84.66(11)
78.60(10)
72.74(10)
147.39(9)
79.29(10)
72.57(10)
84.08(10)
78.14(10)
84.12(9)
145.39(11)
65.06(10)
Compound 2
Pb1-O1
Pb1-O4i
Pb1-O7
Pb1-N2
2.495(3)
2.798(4)
2.588(4)
2.616(3)
Pb1-O2
Pb1-O6ii
Pb1-N1
2.731(3)
2.909(4)
2.610(3)
Figure 1. ORTEP plot (40% probability ellipsoids) of the asymmetric
unit of compound 1 with the numbering scheme.
O1-Pb1-O2
O1-Pb1-O6ii
O1-Pb1-N1
O2-Pb1-O4i
O7-Pb1-O2
N2-Pb1-O2
O7-Pb1-O4i
N2-Pb1-O4i
N1-Pb1-O6ii
O7-Pb1-N1
N1-Pb1-N2
49.78(9)
O1-Pb1-O4i
O1-Pb1-O7
O1-Pb1-N2
O2-Pb1-O6ii
N1-Pb1-O2
O4i-Pb1-O6ii
N1-Pb1-O4i
O7-Pb1-O6ii
N2-Pb1-O6ii
O7-Pb1-N2
153.75(13)
79.27(11)
90.38(11)
80.94(10)
113.61(11)
94.69(11)
74.98(12)
87.91(11)
130.93(11)
141.09(11)
105.33(10)
81.66(11)
153.18(13)
121.22(10)
74.67(11)
84.78(13)
89.07(12)
164.29(11)
79.49(11)
61.85(11)
Compound 3
Pb1-O1
Pb1-O4i
Pb1-O7
Pb1-N2
2.655(3)
2.645(3)
2.690(4)
2.536(3)
Pb1-O2
Pb1-O5ii
Pb1-N1
2.550(3)
2.901(3)
2.478(3)
O2-Pb1-O1
O1-Pb1-O5ii
N1-Pb1-O1
O2-Pb1-O4i
O2-Pb1-O7
N2-Pb1-O2
O4i-Pb1-O7
N2-Pb1-O4i
N1-Pb1-O5ii
O7-Pb1-N1
N1-Pb1-N2
50.10(8)
O4i-Pb1-O1
O1-Pb1-O7
N2-Pb1-O1
O2-Pb1-O5ii
N1-Pb1-O2
O4i-Pb1-O5ii
N1-Pb1-O4i
O7-Pb1-O5ii
N2-Pb1-O5ii
O7-Pb1-N2
145.01(9)
78.50(10)
109.55(9)
78.56(9)
86.21(10)
99.14(9)
75.78(9)
133.63(11)
78.73(9)
115.85(9)
75.12(10)
145.23(9)
128.59(10)
70.41(9)
77.89(11)
75.10(9)
144.50(9)
80.43(12)
65.94(10)
Figure 2. ORTEP representation of the asymmetric unit of compound 3.
The thermal ellipsoids are drawn at 40% probability.
atom with bond distances of 2.493(3) and 2.766(3) Å in 1
and 2.550(3) and 2.655(3) Å in 3, respectively. Each DMF
molecule is monodentally coordinated to the PbII atom with
the Pb-O distances of 2.692(3) and 2.690(4) Å in 1 and 3,
respectively, and these values are much longer than that in
[Pb(bipy)(DMF)(B10H9OH)]‚DMF26 but similar to that in
(Pr3N-C2H4-NPr3)[Pb(DMF)6][Pb5I14]‚DMF.27 There are
two different types of Pb-O(sulfonyl) bond distances in 1
and 3. The shorter bond distances are 2.616(3) Å in 1 and
2.645(3) Å in 3, whereas the longer bond distances are 2.929-
(3) Å in 1 and 2.901(3) Å in 3, respectively. As discussed
in refs 21 and 28,21,28 a search of the bond distances for
140.92(12)
Compound 4
Pb1-O1
Pb1-O5i
Pb1-N1
Pb2-O1
Pb2-O7
Pb2-O10iv
Pb2-N3
Pb3-O3ii
Pb3-O7
Pb3-O10iv
Pb3-N6
2.347(4)
2.866(5)
2.519(5)
2.582(4)
2.443(4)
2.997(5)
2.664(5)
2.868(4)
2.695(4)
2.751(4)
2.578(5)
Pb1-O3
Pb1-O9
Pb1-N2
Pb2-O2
Pb2-O9
Pb2-O11ii
Pb2-N4
Pb3-O5iii
Pb3-O8
Pb3-N5
2.414(4)
2.806(4)
2.603(5)
2.775(4)
2.429(4)
2.903(4)
2.609(5)
2.574(4)
2.395(4)
2.579(5)
a Symmetry codes for 1: i, x, y, -1 + z; ii, 1 - x, -y, -1 - z. Symmetry
(25) Datta, B.; Adhikary, B.; Bag, P.; Florke, U.; Nag, K. J. Chem. Soc.,
Dalton Trans. 2002, 2760.
(26) Zhizhin, K. Y.; Vovk, O. O.; Malinina, E. A.; Mustyatsa, V. N.; Goeva,
L. V.; Polyakova, N.; Kuznetsov, N. T. Russ. J. Coord. Chem. 2001,
27, 613.
(27) Krautscheid, H.; Vielsack, F.; Klaassen, N. Z. Anorg. Allg. Chem. 1998,
624, 807.
(28) Foreman, M. R. J.; Gelbrich, T.; Hursthouse, M. B.; Plater, M. J. Inorg.
Chem. Commun. 2000, 3, 234.
1
1
codes for 2: i, x, -y + /2, -1/2 + z; ii, -x, -1/2 + y, /2 - z. Symmetry
codes for 3: i, 1 + x, y, z; ii, 1 - x, -y, -z. Symmetry codes for 4: i, x,
1
1
1
1
-y + /2, -1/2 + z; ii, -1 + x, y, z; iii, -1 + x, /2 - y, /2 + z; iv, x, /2
1
- y, /2 + z.
Pb-O up to 3.07 or 3.10 Å is reasonable and usually can
find a nearly ideal value assumed for oxidation state II on
Inorganic Chemistry, Vol. 45, No. 19, 2006 7939

Fan and Zhu
Figure 3. ORTEP diagram of the asymmetric unit of compound 2. The
thermal ellipsoids are drawn at 40% probability.
Figure 4. ORTEP view of the asymmetric unit of compound 4. The
thermal ellipsoids are drawn at 30% probability. H atoms are omitted for
clarity.
the PbII atom. Therefore, longer bond distances in 1 and 3
can be acceptable and are considered as weak bonding. Such
comparable longer Pb-O bond distances can be easily found
in recent references, for example, 3.058 Å in [Pb2(2,2′-bipy)2-
(µ-4,4′-bipy)(NO3)4]18 and 3.072 Å in [Pb3(BTC)2].25
Each Hssal2- ligand performs a µ3-coordination mode in
1 and 3; therefore, ladderlike chains were formed in which
the separations of Pb‚‚‚Pb by sulfonates are 5.0943(4) Å for
1 and 4.9807(3) Å for 3, respectively. Moreover, the
separations of Pb‚‚‚Pb by Hssal2- ligands in the ladderlike
chains are 8.5681(5) and 11.5471(7) Å for 1 and 8.2893(4)
and 11.4005(5) Å for 3, respectively, which are longer than
those in the dimer 5.3a
Chart 3
Determination of the structure of 2 by X-ray crystal-
lography shows compound 2 in the solid state to be a 2-D
double-sheet network. As shown in Figure 3, the PbII ion is
chelated by two N atoms of one 2,2′-bipy ligand, four O
atoms from three Hssal2- ligands, and one O atom from one
H2O molecule. The Pb-N bond distances in 2 are much
longer than those of 1, while the Pb-O7(water) bond
distance is similar to that in 5.3a The carboxyl group chelates
to the Pb atom with similar values found in compounds 1
and 3. The coordination number in 2 is 7 with a PbN2O5
chromophore. The distances of Pb‚‚‚Pb separated by the
Hssal2- ligand are 9.4066(7) and 10.0091(6) Å, while the
Pb‚‚‚Pb separation by sulfonate is 5.3279(4) Å. The two rings
of the 2,2′-bipy ligand in 2 are nearly coplanar with a dihedral
angle of 2.1(2)°, which is similar to that in compound 1 [3.0-
(1)°]. Each Hssal2- ligand acts as a chelating-bridging mode
in the µ3 form, but such a mode is very different from those
in 1 and 3. In contrast to the syn-bridging mode of each
sulfonate group in 1 and 3, each sulfonate in 2 is antibridging.
Therefore, in 1 and 3 the extended frameworks are 1-D
ladderlike chains, whereas in 2, the extended network is 2-D
double-layer architecture. In these compounds 1-3, the
hydroxyl groups of Hssal all are nonbonding and all
sulfonates are coordinated to PbII atoms through two O
atoms. The coordination modes of Hssal2- in 1-3 are shown
in Chart 3, in which the torsion angles of Pb2-O4-S1-C6
and Pb3-O5-S1-C6 are -126.7(2)° and +18.3(2)° for 1
and -117.9(2)° and +14.5(2)° for 3, respectively, while the
torsion angles of Pb3-O6-S1-C6 and Pb2-O4-S1-C6
in 2 are -103.7(2)° and -140.2(2)°, respectively.
In 1-3, each Hssal2- is doubly deprotonated, while in 4,
each ssal3- is fully deprotonated. Single-crystal X-ray
analysis reveals that compound 4 possesses a 2-D polymeric
structure where there are three types of PbII ions in an
asymmetric unit with coordination numbers 6 for Pb1, 8 for
Pb2, and 7 for Pb3. As shown in Figure 4, Pb1 is coordinated
by two N atoms of one phen ligand and four O atoms (O1,
O3, O9, and O5i) from three ssal3- ligands. Pb2 is coordi-
nated by two N atoms of one phen ligand and six O atoms
(O1, O2, O7, O9, O10iv, and O11iv) from four ssal3- ligands.
Pb3 is coordinated by two N atoms from one phen ligand
and five O atoms (O3ii, O5iii, O7, O8, and O10iv) from four
ssal3- ligands. Pb-N bond distances except Pb1-N1 and
Pb2-N2 in 4 are similar and can be found in [Pb(phen)2-
(CH3COO)](ClO3)29 but are longer than those of 3. All bond
distances of Pb-O(COO-) in 4 are in the typical range of
2.347(4)-2.775(4) Å.
The fully deprotonated 5-sulfosalicylates in 4 perform two
novel coordination modes (Chart 4), which are not reported
(29) Morsali, A.; Mahjoub, A. R.; Darzi, S. J.; Soltanian, M. J. Z. Anorg.
Allg. Chem. 2003, 629, 2596.
7940 Inorganic Chemistry, Vol. 45, No. 19, 2006

Self-assembly of Lead(II) 5-Sulfosalicylate
Chart 4
Table 3. H-Bonding Geometry Parameters (Å and deg) for Compounds
1-3a
D-H‚‚‚A
D-H
H‚‚‚A
D‚‚‚A
D-H‚‚‚A
Compound 1
O3-H3A‚‚‚O1
0.847(10)
1.71(2)
2.508(4)
157(5)
Compound 2
O3-H3A‚‚‚O1
O7-H7A‚‚‚O5i
O7-H7B‚‚‚O6ii
O7-H7B‚‚‚O3iii
0.848(10)
0.85(1)
0.848(10)
0.848(10)
1.81(4)
2.02(4)
2.35(4)
2.42(2)
2.553(4)
2.697(17)
2.911(6)
3.216(5)
145(6)
136(5)
124(4)
156(4)
Chart 5. Projection of the Coordination Spheres of PbII Ions in
Compounds 1-4
Compound 3
O3-H3‚‚‚O2
0.82
1.80
2.526(4)
146.9
3
1
1
1
a Symmetry codes in 2: i, x, -y + /2, z - /2; ii, x, -y + /2, z - /2;
iii, -x, -y + 1, -z.
Table 4. Aromatic-Aromatic Interactions in Compound 4a
centroid-to-centroid
no.
two rings
distance (Å)
symmetry code
1
2
3
4
5
6
7
1, 7
2, 4
2, 8
3, 9
4, 7
5, 8
6, 9
3.712(4)
3.685(5)
3.613(5)
3.550(5)
3.628(4)
3.612(5)
3.664(4)
2 - x, 1/2 + y, 1/2 - z
x, y, z
x, y, z
x, y, z
1 - x, 1/2 + y, 1/2 - z
1 - x, -1/2 + y, 1/2 - z
2 - x, -1/2 + y, 1/2 - z
a Ring 1: N1, C8-C11, C19. Ring 2: N2, C14-C18. Ring 3: N3, C27-
C30, C38. Ring 4: N4, C33-C37. Ring 5: N5, C39-C42, C50. Ring 6:
N6, C45-C49. Ring 7: C42-C45, C49-C50. Ring 8: C30-C33, C37-
C38. Ring 9: C11-C14, C18-C19.
in the references. Each carboxyl group acts as chelating and
bridging modes (totally tridentate) where the two O atoms
coordinate to a PbII ion and one of them is also involved in
a bridge to an adjacent PbII ion. The phenolate and sulfonate
groups act as one-atom bridging or monodentate modes,
respectively. Therefore, the extended framework of 4 is a
2-D architecture.
It is interesting that there is a weak Pb‚‚‚Pb interaction
[4.0711(4) Å] between Pb1 and Pb3 in 4, which can be
compared to the reported values.30,31 In the trinuclear motif,
several separations of Pb‚‚‚Pb can be found; i.e., Pb1 and
Pb2 are bridged by a carboxyl O atom with a Pb‚‚‚Pb
distance of 4.5183(4) Å. The distance between Pb2 and Pb3
separated by the ssal3- ligand is 8.0902(6) Å. Pb2 and Pb3
are also bridged by two O atoms of the phenolate and
sulfonate groups, forming a Pb2O2 unit with a Pb‚‚‚Pb
distance of 4.277(4) Å.
dihedral angles are 1.69(4)°, 1.7(4)°, and 4.29(14)°, respec-
tively; interestingly, carboxyl groups in these compounds are
localized. In contrast, the dihedral angles between the
benzene ring and the carboxyl group in compound 4 are
significantly large, with values of 16.5(8)° and 26.8(4)°,
indicating novel structural features in the solid-state as-
sembly.
In general, PbII complexes are solvent-poor species and
compounds 1-4 also exhibit such a property. Therefore,
these four compounds only feature a few H-bonding interac-
tions. There is no H bonding in compound 4, and H bonds
in compounds 1-3 only occur within the chains or layers
(Table 3).
The weak π-π interactions occur between rings of
symmetry-related 2,2′-bipy ligands from adjacent chains in
1, with a centroid distance of 3.958(3) Å (symmetry code:
2 - x, -y, -z). In compound 2, π-π stack interactions exist
between rings of symmetry-related 2,2′-bipy ligands from
adjacent layers, with the centroid distances of 3.605(3) and
3.758(3) Å (symmetry codes: 1 - x, -y, -z; 1 - x, 1 - y,
-z). Compounds 1 and 3 share the same topological
ladderlike chain, but in compound 3, the strong π-π stacks
can be observed between rings of symmetry-related phen
ligands with a centroid distance of 3.439(2) Å (symmetry
code: 2 - x, -y, 1 - z) because the phen ligand is sterically
rigid with three rings compared to the 2,2′-bipy ligand. In
contrast to compounds 1-3, in compound 4 there are
extensively π-π stacking interactions between benzoates or
phen ligands that are within or between layers (Table 4).
Removal of Solvated Molecules. Differential thermal
analyses (DTA)-TGA for compounds 1-3 were performed
under a flow of N2 gas. For 1, the first-step weight loss of
The stereochemical activity of the lone pair of electrons
is an interesting issue, which is always discussed. Shimoni-
Livny and co-workers classify PbII complex geometries as
holo- and hemidirected.5 Holodirected refers to PbII com-
plexes in which the bonds to ligand atoms are placed
throughout the surface of the encompassing globe, while
hemidirected refers to those cases in which the bonds to
ligand atoms are directed throughout only part of an
encompassing globe. In compounds 1 and 3, the lone pairs
of electrons are clearly inactive; thus, the coordination
spheres of PbII ions are holodirected. In contrast to 1 and 3,
the coordination spheres of PbII ions in 2 and 4 feature small
holes or gaps; therefore, these coordination spheres can be
considered as somewhat hemidirected (Chart 5).
In compounds 1-3, the carboxyl groups with their attached
benzene rings have nearly coplanar arrangements, and their
(30) Xiao, H. P.; Morsali, A. HelV. Chim. Acta 2005, 88, 2543.
(31) Morsali, A.; Mahjoub, A. R. HelV. Chim. Acta 2004, 87, 2717.
Inorganic Chemistry, Vol. 45, No. 19, 2006 7941

Fan and Zhu
10.96% (calcd 11.20%) from 190 to 220 °C accompanied
by an endothermic peak corresponds to the removal of one
DMF molecule per formula unit. Compound 1 decomposes
at 311 °C. Compound 2 releases the coordinated H2O
molecule from 150 to 200 °C with a weight loss of 3.25%
(calcd 3.01%). Compound 2 decomposes at 293 °C. TGA
for compound 3 show that one DMF molecule was lost in
the temperature range 150-220 °C (calcd 10.80%; obsd
9.41%) and this compound decomposes at 339 °C.
Photoluminescence. The solid-state photoluminescent
spectra of compounds 1-4 at room temperature upon
excitation at 220 nm have been measured. The maximum
emission occurs at 408 nm for 1 and 407 nm for 3,
corresponding to the S0 f S1 absorption, but such an
emission is not found in 2 and 4, which may be attributed
to the enhancing influence of the coordinated DMF molecule
on emission. Moreover, there is a strong emission at 470
nm in all four compounds (for compounds 2 and 4, this
emission is a maximum one), which is red-shifted about 20
nm compared to that of free H3ssal ligand (450 nm).
Obviously, this strong emission comes from the 5-sulfosali-
cylate ligand, and the large red-shifted effect may be
attributed to the coordination or an excited state of a metal-
perturbing intraligand.
four compounds largely depend on the solvents, solution pH,
and synthetic methods. Structural analyses and characteriza-
tions of these four compounds give us some valuable
information. First, assemblies of four compounds generate
three types of diverse frameworks: a 1-D ladderlike chain,
a 2-D double-layer architecture, and a 2-D layer network.
Second, Hssal2- and ssal3- ligands perform novel coordina-
tion modes, which are not reported before. In 1-3, Hssal2-
ligands act as chelating-bridging modes, while in contrast
to the syn bridging mode of sulfonates in 1 and 3, sulfonates
in 2 serve as antibridging. Third, compounds in 1-4 are
solvent-poor, containing, therefore, no H bonding in 4, and
only intrachain or intralayer H bonds can be observed in
compounds 1-3. Fourth, aromatic-aromatic stacking inter-
actions in 1-3 can only be observed between rings of
heterocyclic amine ligands. However, there are extensively
π-π interactions in compound 4. Finally, weak Pb‚‚‚Pb
interactions can be observed in compound 4, which is sparse
in PbII complexes.
Acknowledgment. The authors thank the National Natu-
ral Science Foundation of China (Grant 50073019) and the
Analytical and Measurement Fund of Zhejiang Province.
Supporting Information Available: X-ray crystallographic data
in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
Conclusion
We have synthesized four lead(II) 5-sulfosalicylate com-
pounds. Assemblies and diverse structural topologies of these
IC060871V
7942 Inorganic Chemistry, Vol. 45, No. 19, 2006