Syntheses, structures, and characterizations of four new lead(II) 5-sulfosalicylate complexes with both chelating and bridging neutral ligands

Article abstract of DOI:10.1021/ic700611e

Four structurally diverse complexes, {[Pb(Hssal)(2,2′-bipy)](4, 4′-bipy)_0.5}_n (1), [Pb₂(Hssal) ₂(2,2′-bipy)₂(4,4′-bipy)(H₂O) ₂] (2), [Pb(Hssal)(phen)(4,4′-bipy)_0.5]_n (3), and [Pb(Hssal)(2,2′-bipy)(bpe)_0.5]_n (4), have been synthesized and characterized by elemental analyses, IR, thermogravimetric analyses, fluorescent spectra, and single-crystal X-ray analyses, where Hssal^2- is doubly deprotonated 5-sulfosalicylate, 2,2′-bipy is 2,2′-bipyridine, phen is 1,10-phenanthroline, 4,4′-bipy is 4,4′-bipyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene. The structure of complex 1 possesses a one-dimensional ladderlike chain with guest 4,4′-bipy molecules, while the molecular structure of complex 2 is a dimeric species with a coordinating 4,4′-bipy ligand. Complex 3 consists of a one-dimensional ladderlike chain with monodentate 4,4′-bipyridine but somewhat different from that of complex 1. Complex 4 is a two-dimensional layer structure. In 1-4, all 5-sulfosalicylates are doubly deprotonated, and all carboxylate groups of Hssal^2- chelate to Pb^II ions; however, the coordination modes of sulfonyl groups are different: syn-syn bridging in 1, noncoordinating in 2, syn-skew bridging in 3, and one-atom bridging in 4. The noncoordinating mode of sulfonate in Pb^II complexes containing 5-sulfosalicylate is first reported in this presentation. The 4,4′-bipy ligands act as guest molecules in 1, dimeric linkers in 2, and monodentates in 3. The π-π stacking interactions can be observed in complexes 1-3, whereas there is no such interaction in complex 4. The coordination spheres of Pb^II ions in 1-4 are controlled by three factors: the activity of a lone pair of electrons, weak Pb-O interactions, and π-π stacking interactions. The Pb^II lone pair in 4 is inactive, whereas in 1-3, they are stereochemically active. The thermal stability and fluorescent property of complexes 1-4 are different from those of Pb ^II complexes only containing chelating ligands, [Pb(Hssal)(2, 2′-bipy)(DMF)]_n (5), and [Pb(Hssal)(2,2′-bipy)(H ₂O)]_n (6), and [Pb(Hssal)(phen)(DMF)]_n (7).

Full text of DOI:10.1021/ic700611e

Inorg. Chem. 2007, 46, 6785−6793
Syntheses, Structures, and Characterizations of Four New Lead(II)
5-Sulfosalicylate Complexes with Both Chelating and Bridging Neutral
Ligands
Sai-Rong Fan and Long-Guan Zhu*
Department of Chemistry, Zhejiang UniVersity, Hangzhou 310027, People’s Republic of China
Received March 30, 2007
Four structurally diverse complexes,
{
[Pb(Hssal)(2,2 -bipy)2(4,4
′
-bipy)](4,4
′
-bipy)0.5
}
(1), [Pb2(Hssal)2(2,2
′
′-bipy)-
n
(H2O)2] (2), [Pb(Hssal)(phen)(4,4 -bipy)0.5 n
′
]
(3), and [Pb(Hssal)(2,2′-bipy)(bpe)0.5]n (4), have been synthesized and
characterized by elemental analyses, IR, thermogravimetric analyses, fluorescent spectra, and single-crystal X-ray
-
analyses, where Hssal2 is doubly deprotonated 5-sulfosalicylate, 2,2
′
-bipy is 2,2
-bipyridine, and bpe is trans-1,2-bis(4-pyridyl)ethylene. The structure of complex 1
possesses a one-dimensional ladderlike chain with guest 4,4 -bipy molecules, while the molecular structure of
complex 2 is a dimeric species with a coordinating 4,4 -bipy ligand. Complex 3 consists of a one-dimensional
ladderlike chain with monodentate 4,4 -bipyridine but somewhat different from that of complex 1. Complex 4 is a
4, all 5-sulfosalicylates are doubly deprotonated, and all carboxylate groups
syn bridging
′-bipyridine, phen is 1,10-
phenanthroline, 4,4′-bipy is 4,4′
′
′
′
two-dimensional layer structure. In 1
of Hssal2 chelate to PbII ions; however, the coordination modes of sulfonyl groups are different: syn
−
-
−
in 1, noncoordinating in 2, syn-skew bridging in 3, and one-atom bridging in 4. The noncoordinating mode of
sulfonate in PbII complexes containing 5-sulfosalicylate is first reported in this presentation. The 4,4
-bipy ligands
act as guest molecules in 1, dimeric linkers in 2, and monodentates in 3. The π−π stacking interactions can be
observed in complexes 1
3, whereas there is no such interaction in complex 4. The coordination spheres of PbII
ions in 1 4 are controlled by three factors: the activity of a lone pair of electrons, weak Pb O interactions, and
π−π stacking interactions. The PbII lone pair in 4 is inactive, whereas in 1
3, they are stereochemically active.
The thermal stability and fluorescent property of complexes 1
4 are different from those of PbII complexes only
-bipy)(DMF)]n (5), and [Pb(Hssal)(2,2 -bipy)(H2O)]n (6), and [Pb(Hssal)-
′
−
−
−
−
−
containing chelating ligands, [Pb(Hssal)(2,2
′
′
(phen)(DMF)]n (7).
Introduction
investigations the PbII coordination chemistry, such as the
lone pair of electrons, coordination number, and coordination
geometry, plays an important role in the elucidation of
interactions of PbII with zinc-binding domains. In addition,
the study of PbII model complexes in biological systems2
and removal of lead by chelating agents through coordination
have been of crucial importance.3
On the other hand, the lead can exhibit a variable
coordination number and geometry with or without a
stereochemically active lone pair; therefore, structural di-
versities in lead complexes will inevitably occur. Coordina-
tion bonds and noncovalent interactions (such as hydrogen-
Lead is a heavy toxic metal found in critical life cycles as
a result of its widespread use in the industry. The molecular
mechanisms of lead toxicity are probably associated with
several different types of proteins. Therefore, the mechanisms
of PbII binding to zinc-binding domains have been
extensively studied by using various techniques,1 in these
* To whom correspondence should be addressed. E-mail: chezlg@
zju.edu.cn. Tel: +86-571-87963867. Fax: +86-571-87951895.
(1) (a) Payne, J. C.; Horst, M. A.; Godwin, H. A. J. Am. Chem. Soc.
1999, 121, 6850. (b) Magyar, J. S.; Weng, T. C.; Stern, C. M.; Dye,
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) Ghering, A. B.; Jenkins, L. M.
M.; Schenck, B. L.; Deo, S.; Mayer, R. A.; Pikaart, M. J.; Omichinski,
J. G.; Godwin, H. A. J. Am. Chem. Soc. 2005, 127, 3751. (d) Claudio,
E. S.; Horst, M. A.; Forde, C. E.; Stern, C. L.; Zart, M. K.; Godwin,
H. A. Inorg. Chem. 2000, 39, 1391.
(2) Andersen, R. J.; Targiani, R. C.; Hancock, R. D.; Stern, C. L.;
Goldberg, D. P.; Godwin, H. A. Inorg. Chem. 2006, 45, 6574.
(3) (a) Pellissier, A.; Bretonniere, Y.; Chatterton, N.; Pecaut, J.; Delangle,
P.; Mazzanti, M. Inorg. Chem. 2007, 46, 3714. (b) Claudio, E. S.;
Godwin, H. A.; Magyar, J. S. Prog. Inorg. Chem. 2003, 51, 1.
10.1021/ic700611e CCC: $37.00
Published on Web 06/30/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 16, 2007 6785

Fan and Zhu
Chart 1. Structures of Complexes 5-8
bonding and π-π stacking interactions), the metal-to-ligand
molar ratio, the coordinative function of the ligands, the type
of metal ions, the presence of solvent molecules, counterions,
or organic guest molecules, and interactive information stored
in the ligands should be taken into account in the process of
the rational design and synthesis of metal coordination
polymers.4-6 Therefore, careful selection of suitable poly-
functional organic ligands is helpful for constructing novel
metal coordination polymers.7-9 To understand the PbII
chemistry with polyfunctional chelating ligands, the 5-sul-
fosalicylic acid (H3ssal) has been selected for synthesizing
novel coordination polymers in our laboratory and other
groups and five complexes based on the PbII/H3ssal/2,2′-
bipyridine (2,2′-bipy) or 1,10-phenanthroline (phen) systems,
namely, [Pb(Hssal)(2,2′-bipy)(DMF)]n (5), [Pb(Hssal)(2,2′-
bipy)(H2O)]n (6), [Pb(Hssal)(phen)(DMF)]n (7), [Pb(Hssal)-
(phen)(H2O)]2 (8), and [Pb3(ssal)2(phen)3]n (9),10,11 have been
synthesized (Chart 1), in which all contain neutral amine
chelating ligands, i.e., 2,2′-bipy or phen. It is obvious that
only one of these five complexes, 9, has no solvent molecule,
while each of the other four complexes has one solvent
molecule (water or N,N′-dimethylformamide, DMF) occupy-
ing the coordination site. It can be predicted that if these
sites were replaced by other neutral ligands, such as bridging
ligands, resulting complexes will contain both chelating and
bridging ligands and then the new architectures can be tuned
or significantly changed by such strategies. Although a lot
of transition-metal complexes with both chelating and
(4) (a) Burkill, H. A.; Vilar, R.; White, A. J. P. Inorg. Chim. Acta 2006,
359, 3709. (b) Ambrosi, G.; Dapporto, P.; Formica, M.; Fusi, V.;
Giorgi, L.; Guerri, A.; Micheloni, M.; Paoli, P.; Pontellini, R.; Rossi,
P. Inorg. Chem. 2006, 45, 304.
(5) (a) Kondo, M.; Irie, Y.; Shimizu, Y.; Miyazawa, M.; Kawaguchi, H.;
Nakamura, A.; Naito, T.; Maeda, K.; Uchida, F. Inorg. Chem. 2004,
43, 6139. (b) Gandara, F.; Fortes-Revilla, C.; Snejko, N.; Gutierrez-
Puebla, E.; Iglesias, M.; Monge, M. A. Inorg. Chem. 2006, 45, 9680.
(c) 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.; Hung, C.
H.; Lu, K. L. Inorg. Chem. 2006, 45, 2430. (d) Diaz, P.; Benet-
Buchholz, J.; Vilar, R.; White, A. J. P. Inorg. Chem. 2006, 45, 1617.
(6) (a) Go, Y. B.; Wang, X. Q.; Anokhina, E. V.; Jacobson, A. J. Inorg.
Chem. 2005, 44, 8265. (b) Go, Y. B.; Wang, X. Q.; Anokhina, E. V.;
Jacobson, A. J. Inorg. Chem. 2004, 43, 5360.
(8) Holmes, K. E.; Kelly, P. F.; Elsegood, M. R. J. Dalton Trans. 2004,
3488.
(9) Roesky, H. W.; Andruh, M. Coord. Chem. ReV. 2003, 236, 91.
(10) Fan, S. R.; Zhu, L. G. Inorg. Chem. 2006, 45, 7935.
(11) Li, J. F.; Zhao, Y. J.; Li, X. H.; Hu, M. L. Acta Crystallogr. 2004,
E60, m1210.
(7) Ghosh, A. K.; Ghoshal, D.; Zangrando, E.; Ribas, J.; Chaudhuri, N.
R. Dalton Trans. 2006, 1554.
6786 Inorganic Chemistry, Vol. 46, No. 16, 2007

Four New Lead(II) 5-Sulfosalicylate Complexes
PbII salt. Anal. Calcd (found): C, 42.29 (42.29); H, 2.37 (2.34);
N, 6.16 (6.16). IR (KBr pellet, cm-1): 1619(m), 1577(s), 1518-
(m), 1474(m), 1445(s), 1430(m), 1412(w), 1372(w), 1336(m), 1297-
(m), 1256(s), 1238(s), 1155(s), 1136(s), 1119(m), 1102(m), 1072-
(m), 1035(w), 1016(s), 895(w), 855(m), 831(w), 819(m), 803(w),
783(w), 724(s), 669(s), 640(w), 617(w), 596(s), 586(m), 567(w),
534(w), 459(w), 418(w), 405(m).
Preparation of [Pb(Hssal)(2,2′-bipy)(bpe)0.5]n (4). A mixture
of Pb(CH3COO)2‚3H2O (0.190 g, 0.50 mmol), 5-sulfosalicylic acid
dihydrate (0.128 g, 0.50 mmol), 2,2′-bipy (0.077 g, 0.49 mmol),
and trans-1,2-bis(4-pyridyl)ethylene (0.091 g, 0.50 mmol) in a
water/ethanol/DMF (3:1:1) solution (25 mL) was refluxed for 2 h
and filtered. The resulting solution was set aside for evaporation
for 3 days, and pale-yellow needle crystals of 4 were obtained.
Yield: 84% based on a PbII salt. Anal.Calcd (found): C, 41.19
(41.19); H, 2.55 (2.47); N, 6.27 (6.25). IR (KBr pellet, cm-1): 1604-
(s), 1560(m), 1496(w), 1474(m), 1439(s), 1421(m), 1369(w), 1358-
(w), 1337(m), 1319(w), 1301(m), 1256(s), 1236(s), 1151(s),
1117(m), 1072(m), 1036(w), 1010(s), 979(w), 959(w), 897(w), 858-
(w), 821(m), 774(s), 732(w), 671(m), 646(w), 628(w), 596(m), 559-
(w), 544(w), 462(w), 420(w), 405(w).
X-ray Structure Determination. Data collection for complexes
1-4 was carried out by a Bruker SMART diffractometer equipped
with a CCD area detector. The data were integrated by use of the
SAINT program,13 and the intensities were corrected for Lorentz
factor polarization and absorption. The four structures were solved
by the Patterson method and successive Fourier syntheses. Full-
matrix least-squares refinements on F 2 were carried out using the
SHELXL-97 package.14 All H atoms bonded to C atoms were placed
in calculated positions and refined as riding, with C-H ) 0.93 Å
and Uiso(H) ) 1.2Ueq(C). In 3, the 4,4′-bipy ligand is heavily
disordered, and the atoms were only isotropically refined. All of
the programs used are included in the WinGX Suite with version
1.70.15 Detailed crystal data and structure refinements for 1-4 are
listed in Table 1.
bridging neutral ligands have been reported, only one PbII
complex with two such ligands was published in our
laboratory, [Pb2(NO3)4(2,2′-bipy)2(µ-4,4′-bipy)] (10; 4,4′-bipy
) 4,4′-bipyridine).12 Therefore, further exploration for the
PbII/H3ssal/2,2′-bipy, phen/4,4′-bipy, or trans-1,2-bis(4-py-
ridyl)ethylene (bpe) systems will provide abundant diverse
structural complexes. Herein, we present syntheses, struc-
tures, properties, and weak interactions of four polymeric
complexes, namely, {[Pb(Hssal)(2,2′-bipy)](4,4′-bipy)0.5}n
(1), [Pb2(Hssal)2(2,2′-bipy)2(4,4′-bipy)(H2O)2] (2), [Pb(H-
ssal)(phen)(4,4′-bipy)0.5]n (3), and [Pb(Hssal)(2,2′-bipy)-
(bpe)0.5]n (4).
Experimental Section
Materials and Physical Measurements. All starting materials
were obtained from commercial sources and were of reagent grade.
C, H, and N elemental analyses were carried out on a Perkin-Elmer
analyzer model 1110. The IR spectra were taken on a Nicolet Nexus
470 IR spectrophotometer as KBr pellets in the 400-4000 cm-1
region. Thermogravimetric analyses were studied by a NETZSCH
STA 409 in a N2 atmosphere in the temperature range between
room temperature and 800 °C at a heating rate of 10 °C min-1
using Al2O3 crucibles. The photoluminescence study was carried
out on a powdered sample in the solid state at room temperature
using a Hitachi 850 spectrometer.
Preparation of {[Pb(Hssal)(2,2′-bipy)](4,4′-bipy)0.5
} (1). A
n
mixture of Pb(CH3COO)2‚3H2O (0.191 g, 0.50 mmol), 5-sulfosali-
cylic acid dihydrate (0.127 g, 0.50 mmol), 2,2′-bipy (0.078 g, 0.50
mmol), and 4,4′-bipy (0.076 g, 0.49 mmol) in a water/ethanol (3:
1) solution (20 mL) was refluxed for 2 h and then filtered. A
cottonlike solid was quickly precipitated without further filtration.
One week later colorless block-shaped crystals of 1 started to form
and a cottonlike solid gradually disappeared within 2 weeks.
Yield: 71% based on a PbII salt. Anal. Calcd (found): C, 40.18
(40.20); H, 2.45 (2.29); N, 6.39 (6.41). IR (KBr pellet, cm-1): 1630-
(m), 1589(s), 1572(s), 1489(m), 1475(w), 1448(m), 1438(s), 1387-
(w), 1375(w), 1315(w), 1306(w), 1212(s), 1173(s), 1126(m),
1083(w), 1034(s), 1010(m), 895(w), 823(m), 773(s), 758(w), 733-
(w), 675(m), 645(w), 601(m), 585(m), 540(w), 451(w), 420(w),
407(w).
Preparation of [Pb2(Hssal)2(2,2′-bipy)2(4,4′-bipy)(H2O)2] (2).
A mixture of Pb(CH3COO)2‚3H2O (0.191 g, 0.50 mmol), 5-sul-
fosalicylic acid dihydrate (0.127 g, 0.50 mmol), 2,2′-bipy (0.031
g, 0.20 mmol), and 4,4′-bipy (0.154 g, 0.99 mmol) in a water/
ethanol/N,N′-dimethylformamide (DMF) (3:1:1) solution (20 mL)
was refluxed for 2 h and then filtered. Colorless block-shaped
crystals of 2 were obtained after 1 day. Yield: 75% based on a
PbII salt. Anal. Calcd (found): C, 38.01 (38.09); H, 2.73 (2.60);
N, 6.33 (6.07). IR (KBr pellet, cm-1): 3318(s), 1603(s), 1592(s),
1557(s), 1474(m), 1442(s), 1377(m), 1356(w), 1315(w), 1292(m),
1254(m), 1211(s), 1181(s), 1156(m), 1122(m), 1075(m), 1024(s),
1015(m), 895(w), 840(w), 820(w), 796(w), 771(m), 733(w), 671-
(w), 648(w), 621(w), 586(m), 567(w), 413(w).
Results and Discussion
Synthesis. In the our previously reported system of PbII/
H3ssal/2,2′-bipy, we have prepared two complexes with
different topologies, 5 and 6.10 Because the PbII ion has a
versatile coordination number and varied coordination ge-
ometry, we introduced the bridging ligands such as 4,4′-bipy
and bpe into the system of PbII/H3ssal/2,2′-bipy, with two
aims: one is to construct novel coordination polymers, and
the other is to explore the effect of the neutral ligands on
the network assembly. The 4,4′-bipy ligand in most of the
metal complexes acts as a spacer ligand and forms one-, two-,
or three-dimensional coordination polymers, whereas the 2,2′-
bipy ligand only acts as a terminal chelating function. The
reaction of 4,4′-bipy, Pb(CH3COO)2, H3ssal, 2,2′-bipy,
ethanol, and water under reflux led to the formation of
complex 1, in which 4,4′-bipy is a guest molecule. In order
to obtain a coordinating 4,4′-bipy complex, we changed the
molar ratio of PbII/H3ssal/2,2′-bipy/4,4′-bipy from 1:1:1:1 to
5:5:2:10 in a water/ethanol solution, but only cottonlike solids
Preparation of [Pb(Hssal)(phen)(4,4′-bipy)0.5]n (3). A mixture
of Pb(CH3COO)2‚3H2O (0.191 g, 0.50 mmol), 5-sulfosalicylic acid
dihydrate (0.127 g, 0.50 mmol), phen (0.020 g, 0.10 mmol), and
4,4′-bipy (0.154 g, 0.99 mmol) in a water/DMF (3:1) solution (20
mL) was refluxed for 2 h and filtered. Colorless block-shaped
crystals of 3 were obtained after 1 day. Yield: 68% based on a
(13) Sheldrick, G. M. SADABS, Program for Bruker Area Detector
Absorption Correction; University of Go¨ttingen: Go¨ttingen, Germany,
1997.
(14) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(15) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(12) Soudi, A. K.; Marandi, F.; Morsali, A.; Zhu, L. G. Inorg. Chem.
Commun. 2005, 8, 773.
Inorganic Chemistry, Vol. 46, No. 16, 2007 6787

Fan and Zhu
Table 1. Crystallographic Data and Refinement Parameters for Complexes 1-4
complex
empirical formula
Mr
1
2
3
4
C22H16N3O6PbS
657.6
0.11×0.22×0.27
triclinic
P1h
10.0888(5)
10.3628(5)
10.7442(6)
88.834(1)
88.418(1)
67.372(1)
1036.37(9)
2
2.107
8.288
1.9-25.5
3820
3605
301
630
C42H36N6O14Pb2S2
1351.3
0.20×0.22×0.30
monoclinic
P21/c
14.1956(8)
10.9841(7)
15.5903(9)
90.00
116.482(2)
90.00
2175.9(2)
2
2.063
7.902
2.4-26.0
4261
C24H17N3O6PbS
682.66
0.10×0.14×0.23
monoclinic
P21/n
11.3325(11)
15.0546(15)
12.6712(13)
90.00
91.369(1)
90.00
2161.17(4)
4
2.098
7.954
2.3-25.1
3711
C23H17N3O6PbS
670.65
0.11×0.12×0.32
monoclinic
P21/n
11.6713(7)
15.5691(10)
11.8091(8)
90.00
96.122(1)
90.00
2133.61(3)
4
2.088
8.054
2.2-25.5
3963
cryst size (mm3)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
Dc (Mg‚m-3
)
µ (mm-1
θ range
)
unique reflns
obsd reflns
no. of param
F(000)
3798
316
1300
2693
307
1312
3476
310
1288
T (K)
295(2)
295(2)
295(2)
295(2)
R1, wR2 [I > 2σ(I)]
R1, wR2 [all data]
GOF
0.034, 0.070
0.032, 0.069
1.111
0.028, 0.064
0.024, 0.062
1.081
0.064, 0.155
0.042, 0.130
0.997
0.038, 0.067
0.031, 0.064
1.021
were formed. However, in the mixed solvents of water/
ethanol/DMF, the dimeric species with the coordinating 4,4′-
bipy, complex 2, was obtained. In the PbII/H3ssal/phen/4,4′-
bipy system, a change of the molar ratio of phen/4,4′-bipy
from 1:1 to 1:10 gave the unique product, complex 3. In the
PbII/H3ssal/2,2′-bipy/bpe system refluxed in ethanol/DMF/
water, complex 4 was produced in a molar ratio of 1:1:1:0.5
or 5:5:2:10, indicating that the molar ratio of the reactants
is not a key factor in the formation of complex 4.
The syntheses of complexes 2-4 were achieved by adding
the solvent DMF. However, the volume of DMF should be
less than the volume of water used in the syntheses;
otherwise, only complex 5 or 7 was obtained, indicating that
the existence and volume control of DMF are the important
factors for the formation of complexes with both chelating
and bridging ligands.
Complexes 1, 3, and 4 are solvent-free species, while all
of complexes 5-8 incorporate a coordinating water or DMF,
indicating that the bridging ligands can replace the sites
occupied by solvents and then influence the assembly of the
molecular structures.
Structure of 1. Single-crystal X-ray diffraction reveals
that complex 1 consists of a one-dimensional ladderlike
chain, constructed from PbII ions and 2,2′-bipy and Hssal2-
ligands, while the 4,4′-bipy ligand only acts as a guest
molecule in the crystal packing. As shown in Figure 1, each
PbII ion is eight-coordinated by two N atoms from one 2,2′-
bipy ligand and six O atoms: two from a carboxylate group
and four from two sulfonyl groups of two different Hssal2-
ligands (Table 2), in which six bond lengths are relatively
shorter and two longer (dashed lines in Figure 1), termed as
“primary” and “secondary” bonds, respectively.1b Secondary
bonds are always overlooked (for example, reexamination
4-
of [Pb(i-mnt)2]2 results in a new picture of the molecular
structure),1b while recently such bonds have been accepted
as bonding.16
All bond distances of Pb-O(COO-) in 1 are in the typical
range of 2.489(4)-2.516 (4) Å. However, the bond lengths
Pb1-O6 ) 3.144(4) Å and Pb1-O6ii ) 3.128(4) Å are
longer than the sum of the ionic radii but significantly shorter
than the sum of the van der Waals radii (3.54 Å),17 which
can be explained by the presence of an active lone pair in
the proximity of the sulfonate O atoms.
The pioneering works on the PbII lone pair have produced
valuable knowledge.18,19 A stereochemically active PbII lone
pairs of electrons has important effects on the property and
(16) Dale, S. H.; Elsegood, M. R. J.; Kainth, S. Acta Crystallogr. 2004,
C60, m76.
(17) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(18) (a) Shimoni-Livny, L.; Glusker, J. P.; Bock, C. W. Inorg. Chem. 1998,
37, 1853. (b) Parr, J. Polyhedron 1998, 16, 551. (c) Gourlaouen, C.;
Parisel, O. Angew. Chem., Int. Ed. 2007, 46, 553.
(19) Hancock, R. D.; Reibenspies, J. H.; Maumela, H. Inorg. Chem. 2004,
43, 2981.
Figure 1. ORTEP view (40% probability ellipsoids) of the asymmetric
unit of complex 1 with the numbering scheme.
6788 Inorganic Chemistry, Vol. 46, No. 16, 2007

Four New Lead(II) 5-Sulfosalicylate Complexes
Table 2. Selected Bond Lengths (Å) and Angles (deg) for Complexes
1-4a
Complex 1
Pb1-O1i
Pb1-O4
Pb1-O6
Pb1-N1
2.516(4)
2.687(4)
3.144(4)
2.496(5)
Pb1-O2i
Pb1-O5ii
Pb1-O6ii
Pb1-N2
2.489(4)
2.915(5)
3.128(4)
2.591(5)
O1i-Pb1-O2i
O1i-Pb1-O5ii
O1i-Pb1-N1
O2i-Pb1-O4
O2i-Pb1-O6ii
O2i-Pb1-N2
O4-Pb1-O6ii
O4-Pb1-N2
O5ii-Pb1-N1
O6ii-Pb1-N1
N1-Pb1-N2
52.39(12)
126.69(12)
76.15(14)
141.16(13)
136.43(12)
82.56(14)
81.76(12)
117.53(14)
147.31(14)
120.26(13)
63.54(15)
O1i-Pb1-O4
O1i-Pb1-O6ii
O1i-Pb1-N2
O2i-Pb1-O5ii
O2i-Pb1-N1
O4-Pb1-O5ii
O4-Pb1-N1
O5ii-Pb1-O6ii
O5ii-Pb1-N2
O6ii-Pb1-N2
89.58(13)
158.30(13)
121.09(14)
91.59(13)
86.10(15)
121.76(13)
75.91(14)
46.96(10)
83.81(14)
80.41(13)
Figure 2. ORTEP diagram of the asymmetric unit of complex 2. The
thermal ellipsoids are drawn at 40% probability.
Complex 2
Pb1-O1
Pb1-O7
Pb1-N2
2.503(3)
2.560(3)
2.536(3)
Pb1-O2
Pb1-N1
Pb1-N3
2.714(3)
2.451(3)
2.627(3)
holodirected,18 all of the Pb-L bonds likely have similar
lengths. In addition, the presence of an active lone pair leads
to very long Pb-L bonds at the site occupied by the lone
pair, a shortening of the Pb-L bond lengths opposite to the
position of the lone pair, and a lengthening of those adjacent
to this site.19
It has been observed that Pb-N bond lengths fall in the
range of 2.62-2.88 Å for complexes with an inactive lone
pair.20 The Pb-N distances in 1 are shorter and locate in
the site opposite to the lone pair. In addition, these Pb-N
distances fall well within the ranges usually observed in PbII
complexes containing a 2,2′-bipy ligand with an active lone
pair.21 Therefore, the presence of an active lone pair is further
confirmed.
Moreover, the weak interactions between PbII ions and N
atoms of 4,4′-bipy may be accepted because the distance of
Pb-N4,4′-bipy is 3.555(6) Å, which is similar to the sum of
the van der Waals radii (3.57 Å).17 If the 4,4′-bipy ligand
were accepted as a weak bridging linker, the one-dimensional
ladderlike chain of 1 should be extended into the two-
dimensional network, in which the connection of Pb‚‚‚4,4′-
bipy‚‚‚Pb is not linear with the Pb‚‚‚Pb distance of 12.304
Å, which is slightly longer than that of 10 but similar to
that of complex 2.
Structure of 2. Determination of the structure of 2 by
X-ray crystallography showed the complex in the solid state
to be a dimeric species, similar to 10. As shown in Figure
2, each PbII ion is chelated by two N atoms of one 2,2′-bipy
ligand with Pb-N bond distances of 2.451(3) and 2.536(3)
Å, one N atom of the 4,4′-bipy ligand with a Pb-N distance
of 2.627(3) Å, which is much shorter than that of 10, two O
atoms from one carboxyl group of the Hssal2- ligand with
Pb-O distances of 2.503(3) and 2.714(3) Å, and one O atom
from the water molecule with a Pb-O distance of 2.560(3)
Å (Table 2), slightly shorter than that in 6, resulting in a
six-coordination geometry with a PbN3O3 chromophore. The
two pyridyl rings of the 4,4′-bipy ligand are completely
O1-Pb1-O2
O1-Pb1-N1
O1-Pb1-N3
O2-Pb1-N1
O2-Pb1-N3
O7-Pb1-N2
N1-Pb1-N2
N2-Pb1-N3
49.85(9)
77.46(10)
74.87(10)
86.39(10)
124.61(9)
78.01(10)
65.59(9)
O1-Pb1-O7
O1-Pb1-N2
O2-Pb1-O7
O2-Pb1-N2
O7-Pb1-N1
O7-Pb1-N3
N1-Pb1-N3
140.63(11)
114.67(10)
151.74(9)
75.01(9)
74.85(10)
75.21(11)
84.70(9)
144.24(10)
Complex 3
Pb1-O1
Pb1-O4i
Pb1-O5iii
Pb1-N2
2.657(8)
2.688(7)
3.384(9)
2.449(9)
Pb1-O2
Pb1-O5ii
Pb1-N1
Pb1-N3
2.474(8)
2.803(8)
2.506(8)
2.821(16)
O1-Pb1-O2
O1-Pb1-O5ii
O1-Pb1-N2
O2-Pb1-O4i
O2-Pb1-N1
O2-Pb1-N3
O4i-Pb1-N1
O4i-Pb1-N3
O5ii-Pb1-N2
N1-Pb1-N2
N2-Pb1-N3
50.2(2)
112.3(3)
76.2(3)
147.4(2)
75.4(3)
131.3(4)
72.4(3)
74.3(4)
145.1(3)
65.9(3)
83.2(4)
O1-Pb1-O4i
O1-Pb1-N1
O1-Pb1-N3
O2-Pb1-O5ii
O2-Pb1-N2
O4i-Pb1-O5ii
O4i-Pb1-N2
O5ii-Pb1-N1
O5ii-Pb1-N3
N1-Pb1-N3
144.1(3)
114.3(3)
81.1(4)
75.8(3)
87.0(3)
103.6(3)
75.3(2)
80.3(3)
130.8(4)
139.1(4)
Complex 4
Pb1-O1
Pb1-O5i
Pb1-N1
Pb1-N3
2.432(4)
2.967(4)
2.520(4)
2.773(5)
Pb1-O2
Pb1-O5ii
Pb1-N2
2.610(4)
2.917(4)
2.444(4)
O1-Pb1-O2
O1-Pb1-O5ii
O1-Pb1-N2
O2-Pb1-O5i
O2-Pb1-N1
O2-Pb1-N3
O5i-Pb1-N1
O5i-Pb1-N3
O5ii-Pb1-N2
N1-Pb1-N2
N2-Pb1-N3
51.65(12)
152.13(12)
86.78(14)
115.39(11)
115.49(13)
77.92(13)
85.69(13)
126.90(13)
88.39(13)
65.65(14)
80.24(14)
O1-Pb1-O5i
O1-Pb1-N1
O1-Pb1-N3
O2-Pb1-O5ii
O2-Pb1-N2
O5i-Pb1-O5ii
O5i-Pb1-N2
O5ii-Pb1-N1
O5ii-Pb1-N3
N1-Pb1-N3
82.12(13)
75.17(13)
129.56(13)
151.98(12)
76.53(13)
89.11(11)
151.10(13)
77.84(13)
76.31(13)
137.34(14)
a Symmetry codes for 1: i, 1 - x, 1 - y, 2 - z; ii, 1 - x, 1 - y, 1 -
z. Symmetry codes for 3: i, -1 + x, y, z; ii, 1 - x, -y, 1 - z; iii, -x, 1
- y, 1 - z. Symmetry codes for 4: i, -x, -y, 2 - z; ii, 1 + x, y, z; iii, 1
- x, 1 - y, 2 - z.
(20) Hancock, R. D.; Shaikjee, M. S.; Dobson, S. M.; Boeyens, J. C. A.
Inorg. Chim. Acta 1988, 154, 229.
(21) (a) Shi, Y. J.; Li, L. H.; Li, Y. Z.; Chen, X. T.; Xue, Z. L.; You, X.
Z. Polyhedron 2003, 22, 917. (b) Zhu, L. G.; Xiao, H. P. Acta
Crystallogr. 2005, E61, m2283.
structure of its complexes. If the PbII lone pair has no steric
effects, which was termed as an inactive lone pair or
Inorganic Chemistry, Vol. 46, No. 16, 2007 6789

Fan and Zhu
Figure 4. ORTEP view of the asymmetric unit of complex 4. The thermal
ellipsoids are drawn at 40% probability.
the sulfonate group is bidentately coordinated to the PbII ion
through two O atoms with bond distances of 2.688(7) and
2.803(8) Å.
The arrangement of the phen, 4,4′-bipy, and Hssal2-
ligands suggests a gap or hole in the coordination geometry
around the PbII ion [O4i-Pb1-O5ii 103.6(3)°], occupied
possibly by a configurationally active lone pair of electrons
on the PbII ion. In addition, analysis of the coordination
geometry around the PbII ion indicates that there is a
secondary bond, Pb-O5iii (x - 1, y, z) (dashed lines in Figure
3) with a bond distance of 3.384(9) Å, which is close to the
sum of the van der Waals radii.
Figure 3. ORTEP view of the asymmetric unit of complex 3. The thermal
ellipsoids are drawn at 30% probability.
coplanar because one of the two pyridyl rings is imposed
by symmetry. In complex 2, the 4,4′-bipy ligand bridges two
PbII ions rather than noncoordinating in 1, with a separation
of Pb‚‚‚Pb ) 12.2977(6) Å, similar to that in [PbCl2(4,4′-
bipy)]n (12.303 Å)22 but shorter than that in 10(12.631 Å).
The lone pair of electrons likely leaves space for the donor
atoms of ligands around the PbII ion in 2. The secondary
bond of Pb-O3ii (-x + 1, -y, -z + 1) with a distance of
3.508(3) Å (dashed lines in Figure 2) and shorter Pb-
Structure of 4. Single-crystal X-ray diffraction analysis
reveals that the PbII ion in 4 is coordinated by four O (O1,
O2, O5i, and O5ii) atoms from three symmetrical Hssal2-
groups, two N (N1 and N2) atoms from one 2,2′-bipy liagnd,
and the other N (N3) atom from bridging bpe ligand,
resulting in a seven-coordinate complex with a PbN3O4
chromophore, as shown in Figure 4. The complex crystallizes
in the monoclinic space group P21/n and consists of PbII ions
bridged by both bpe and Hssal2- ligands, thus forming a two-
dimensional infinite framework. Each Hssal2- anion contacts
three PbII ions through carboxyl and sulfonyl groups. The
carboxyl group chelates to the PbII ion with a typical Pb-O
distance range, 2.432(4)-2.610(4) Å (Table 2). The sulfonyl
group is coordinated to two PbII ions through one O atom
with bond distances of 2.917(4) and 2.967(4) Å, leading to
the formation of the ladderlike chain by [Pb(Hssal)] units.
The Pb-Nbpe bond distance [Pb1-N3 ) 2.773(5) Å] is much
N
2,2′-bipy opposite to the O3ii indicate the presence of an active
lone pair. In addition, the [Pb2(2,2′-bipy)2(4,4′-bipy)(Hssal)2-
(H2O)2] complex contains water molecules coordinated to
the PbII centers. The water O atoms form O-H‚‚‚O hydrogen
bonds with sulfonyl O atoms of the Hssal2- ligands and
extend the structure of 2 into a three-dimensional hydrogen-
bonding architecture, which can enhance the solid stability
of the crystal packing.
Structure of 3. Determination of the structure of 3 by
X-ray crystallography showed the complex in the solid state
to be a one-dimensional ladderlike chain, constructed from
PbII ions and phen, 4,4′-bipy, and Hssal2- ligands. As shown
in Figure 3, each PbII ion adopts a seven-coordinate
geometry, involving two N atoms from one phen ligand, one
N atom from one 4,4′-bipy ligand, and four O atoms [two
from a carboxylate group and two from two sulfonyl groups]
(Table 2). The average distance of Pb-Nphen in 3 is 2.478-
(9) Å, much shorter than those of PbII complexes containing
phen.23 The 4,4′-bipy ligand is monodentate to the PbII ion
with a Pb-N4,4′-bipy bond distance of 2.821(16) Å, which is
much longer than that in 2 but similar to that in 10. The
carboxyl group of each Hssal2- ligand chelates to the PbII
ion with bond distances of 2.474(8) and 2.657(8) Å, while
24
longer than that of {[Pb(µ-OAc)(µ-bpe)](ClO4)}n but
shorter than that of [Pb(µ-SCN)2(µ-bpe)1.5]n.24
In complex 4, the arrangement of 2,2′-bipy, bpe, and
Hssal2- ligands does not suggest a gap or hole in the
coordination geometry around the PbII ion, indicating that
the lone pair of electrons on PbII is probably inactive in this
complex.
Coordination Modes of 5-Sulfosalicylates in Complexes
1-4. The H3ssal ligands in complexes 1-4 only lose two H
atoms for carboxyl and sulfonyl groups, while the H atom
of the phenolic hydroxyl remains. The coordination modes
of Hssal2- ligands in 1-4 are illustrated in Chart 2.
(22) Nordell, K. J.; Schultz, K. N.; Higgins, K. A.; Smith, M. D. Polyhedron
2004, 23, 2161.
(23) (a) Zhang, L. P.; Zhu, L. G.; Xiao, H. P. Acta Crystallogr. 2005, E61,
m860. (b) Li, X. H.; Yang, S. Z. Acta Crystallogr. 2004, C60, m423.
(C) Xiao, H. P.; Morsali, A. HelV. Chim. Acta 2005, 88, 2543.
(24) Morsali, A.; Yilmaz, V. T.; Zhu, L. G. HelV. Chim. Acta 2005, 88,
2513.
6790 Inorganic Chemistry, Vol. 46, No. 16, 2007

Four New Lead(II) 5-Sulfosalicylate Complexes
Chart 2
In complex 1, a ladderlike chain was formed where the
separation of Pb‚‚‚Pb by sulfonate is 5.1235(5) Å, which is
slightly longer than those in 5 and 6. Moreover, the
separations of Pb‚‚‚Pb by Hssal2- ligands in the ladderlike
chain are 8.2685(6) and 10.7442(6) Å, which are much
shorter than those in 5 and 6. In 2, the carboxylate group
also chelates to one metal ion, while the sulfonate group is
noncoordinating. To the best of our knowledge, in PbII
complexes the sulfonate groups usually coordinate to the
metal. In complex 3, each Hssal2- ligand performs a
chelating-bridging coordination mode; therefore, a ladder-
like chain was formed in which the separation of Pb‚‚‚Pb
by sulfonate is 4.7828(8) Å and is slightly shorter than that
in 5. Moreover, the separations of Pb‚‚‚Pb by Hssal2- ligands
in the ladderlike chain are 8.5136(10) and 11.3325(11) Å,
similar to those in 5. In complexes 1 and 3, each Hssal2-
ligand chelates to one PbII ion and bridges two PbII ions,
but in 1 the sulfonate is a syn-syn bridging mode while in
3 the sulfonate acts as a syn-skew mode. In 4, the Hssal2-
ligand is in a chelating and one-atom-bridging coordination
mode: the carboxylate group chelates to one metal ion, and
the sulfonate group coordinates to two metal atoms only
using one O atom, which is rare in PbII complexes containing
sulfonate groups. The Pb‚‚‚Pb separation by sulfonates in
the Pb2O4 planar unit is 4.1930(4) Å, while the Pb‚‚‚Pb
distances separated by Hssal2- ligands are 8.6784(6) and
11.6713(7) Å. The individual polymeric chains of [Pb(Hssal)]
units are almost parallel to each other and further bridged
by bidentate bridging bpe ligands, resulting in a two-
dimensional framework in which the Pb‚‚‚Pb distance
separated by bpe is 14.7303(10) Å.
indicating that neutral bridging ligands can regulate the
assembly of frameworks.
Weak Interactions in Complexes 1-4. There are strong
π-π interactions occurring between rings of symmetry-
related 2,2′-bipy ligands from adjacent chains in 1, with
centroid-to-centroid distances of 3.662(4) Å for rings N1/
C8-C12 and N2i/C13i-C17i (symmetry code i: 1 - x, -y,
1 - z) and 3.645(11) Å for rings N2/C20-C24 and N3ii/
C30ii-C34ii (symmetry code ii: x, -1 + y, z). In complex
2, the weak π-π stack interactions exist between rings of
the 4,4′-bipy and Hssal2- ligands, with a centroid-to-centroid
distance of 3.920(2) Å, and the dihedral angle between the
two rings is 2.7(2)°. There are very strong π-π interactions
occurring between rings of symmetry-related phen ligands
from adjacent chains in 3, with a centroid-to-centroid distance
of 3.4452(8) Å for rings C11-C14/C18,C19 and C11iii-
C14iii/C18iii,C19iii (symmetry code iii: -x, -y, -z). How-
ever, there is no π-π stacking interactions in 4 because of
the too long spacer of bpe for the formation of the π-π
interactions.
Characterizations
IR Spectroscopy. In the spectra of complexes 1-4, 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 1475 and 1438
cm-1 for 1, 1474 and 1442 cm-1 for 2, 1474 and 1445 cm-1
for 3, and 1474 and 1439 cm-1 for 4. Therefore, these four
complexes contain the Hssal2- ligands, i.e., doubly depro-
tonated 5-sulfosalicylate. The IR spectra of 1-4 show typical
asymmetric and symmetric carboxylate stretching bands at
1572 and 1387 cm-1 for 1, 1557 and 1377 cm-1 for 2, 1577
and 1372 cm-1 for 3, and 1560 and 1369 cm-1 for 4. The
Extended Frameworks of the [Pb(Hssal)] Building
Blocks in Complexes 1-8. In these four new complexes,
together with our previously reported four, 1-8, all contain
[Pb(Hssal)] building blocks. Because of the different coor-
dination modes of Hssal2-, these eight [Pb(Hssal)]n units
display variable frameworks depicted in Figure 5. Units of
[Pb(Hssal)] in 1, 3-5, and 7 consist of one-dimensional
frameworks, in which the frameworks of 3, 5, and 7 are
similar. The motif of [Pb(Hssal)] in 2 is a monomer. Blocks
of [Pb(Hssal)] in 6 consist of a two-dimensional framework,
while in 8 [Pb(Hssal)] components afford a dimeric species.
Therefore, the building blocks of [Pb(Hssal)] in 1-8 exhibit
six frameworks, i.e., one monomer, one dimer, three one-
dimensional chains, and one two-dimensional layer, clearly
-
characteristic vibrations of νas(SO3 ) in 1-4 are at 1212,
1173, and 1126 cm-1 in 1, 1211, 1181, and 1122 cm-1 in 2,
1238, 1155, and 1136 cm-1 in 3, and 1236, 1151, and 1117
cm-1 in 4, whereas the νs(SO3) absorptions are at 1034 cm-1
in 1, 1024 in 2, 1016 cm-1 in 3, and 1010 cm-1 in 4.
Thermal Stability Behavior. Thermal analysis of complex
1 shows that weight loss starts at 168 °C, and in the range
168-208 °C, the total loss of 12.6% corresponds to the
release of 4,4′-bipy (calculated 11.9%). Complex 2 is stable
up to 169 °C, and in the temperature range 169-238 °C,
the total weight loss is 13.3%, corresponding to the release
Inorganic Chemistry, Vol. 46, No. 16, 2007 6791

Fan and Zhu
Figure 5. Eight frameworks constructed from [Pb(Hssal)] blocks in complexes 1-8.
of water and 4,4′-bipy (calculated 14.2%). Complex 3 starts
Upon comparison to compounds 1-4, we found that
to lose weight at 272 °C, and in the temperature range 272-
402 °C, the total weight loss is 41.5% (two-step departure
of ligands without a clear platform), corresponding to the
release of 4,4′-bipy and phen (calculated 37.8%). Complex
4 starts to lose weight at 270 °C, and in the temperature
range 270-314 °C, the total weight loss is 42.3% (one-step
departure of ligands), which corresponds to the release of
bpe and 2,2′-bipy (calculated 36.9%).
compounds 3 and 4 are more stable than compounds 1
and 2 because the latter contain guest 4,4′-bipy and
water molecules, respectively. Compared to compounds
5-7 (without considering the release of solvent
molecules), compounds 1-4 are systematically less stable,
indicating that the bonds of Pb-N formed by bridging
ligands are weaker than those of Pb-N formed by chelating
ligands.
6792 Inorganic Chemistry, Vol. 46, No. 16, 2007

Four New Lead(II) 5-Sulfosalicylate Complexes
Fluorescence. The solid-state fluorescent spectra of
complexes 1-4 at room temperature (λex ) 220 nm) show
similar properties. The emission spectra are at 422, 440, 452,
and 470 nm for 1, at 412, 429, 453, and 470 nm for 2, at
416, 439, 454, and 470 nm for 3, and at 410, 423, 453, and
470 nm for 4. The maximum emissions occur at 470 nm for
complexes 1-4, which are red-shifted about 20 nm compared
to those of the free H3ssal ligand (450 nm). Such large red
shifts may likely be caused by the coordination of Hssal2-
or an interaction between ligands perturbed by PbII. The
complexes 1-4 exhibit multiple peaks due to three ligands
(one H2ssal- and two neutral ligands) contained in the
complexes. Complexes 5-7 only with chelating ligands
exhibit the strongest peaks at 408, 470, and 407 nm,
respectively, indicating that bridging ligands and solvents
largely influence the positions and strengths of peaks.
Moreover, the coexistence of chelating and bridging ligands
in complexes 1-4 leads to the ligand-to-ligand charge
transfer.25
spacer lengths of the bridging ligands. (2) All coordination
modes of the Hssal2- ligands in 1-4 are different. The 4,4′-
bipy ligands in 1-3 act as noncoordinating guests in 1,
dimeric bridges in 2, and monodentates in 3. The bpe ligand
in 4 acts as a polymeric linker. (3) The coordination spheres
of PbII ions in 1-4 are controlled by three factors: the
activity of a lone pair of electrons, weak Pb-O interactions
and π-π stacking interactions. The PbII lone pairs in 1-3
are stereochemically active, whereas in 4, the lone pair is
inactive. The aromatic-aromatic interactions can be found
in complexes 1-3, while no such interaction occurs in
complex 4. (4) Diverse structures of complexes 1-4 with
both chelating and bridging neutral ligands lead to less
thermal stability than those of PbII complexes only containing
chelating ligands previously reported in our laboratory.
Moreover, their fluorescent properties are also different from
those of complexes 5-7. Hence, the diverse product slate
clearly illustrates that different novel structures can be
designed and prepared by the combination of reactants,
solvents, molar ratios, and neutral ligands (chelating and
bridging), and the diverse structures lead to different
functional properties, which is of great benefit for the design
and control of the assembled frameworks for specific usage.
Conclusion
In summary, four novel PbII complexes have been syn-
thesized by the self-assembly of PbII ions and H3ssal and
chelating and bridging neutral ligands. (1) Assemblies of four
complexes generate four types of diverse frameworks: two
one-dimensional chains, a dimeric species, and a two-
dimensional layer network. These diverse structures are
largely controlled by the coordination modes of the Hssal2-
ligands, solvents, chelating ligands, coordination modes, and
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 files
in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
(25) Vogler, A.; Kunkely, H. Coord. Chem. ReV. 2007, 251, 577.
IC700611E
Inorganic Chemistry, Vol. 46, No. 16, 2007 6793