Syntheses and characterizations of metal-organic frameworks with unusual topologies derived from flexible dipyridyl ligands

Article abstract of DOI:10.1002/ejic.200400173

Two flexible exo-bidentate ligands, 2,2′-bis(3-pyridylmethyleneoxy)- 1,1′-biphenylene (3,3′-bpp) and 2,2′-bis(4-pyridyl- methyleneoxy)-1,1′-biphenylene (4,4′-bpp), were synthesized and employed for the preparation of coordination polymers. Seven metal-organic complexes, [Zn₂(3,3′-bpp)₂Cl₄] (1), [Zn₂(3,3′-bpp)₂Br₄] (2), [Zn(4,4′-bpp)Cl₂]_n (3), [Zn(4,4′-bpp)Br ₂]_n (4), [Co(4,4′-bpp)₂(SCN) ₂]_n (5), {[Cd(4,4′- bpp)₂(SCN) ₂]·2H₂O}_n (6) and [Cd(4,4′-bpp) (dca)₂]_n (7) (dca^- = dicyanamide), have been obtained through self-assembly reactions of 3,3′-bpp or 4,4′-bpp with the divalent metal ions Zn^II, Co^II and Cd ^II. Crystal structure analyses reveal that 1 and 2 are dinuclear metallomacrocycles, are isomorphous and possess a layer network built from metallomacrocycles through π-π interactions. In drastic contrast, 3 and 4 exhibit a three-dimensional structure consisting of one-dimensional polymeric chains held together through π-π interactions between adjacent pyridyl rings. The metal-organic frameworks of 5, 6, and 7 possess unusual topologies: Complex 5 is a two-dimensional polymer based on folded rectangular boxes and zigzag chains, whereas 6 is a polycatenated species consisting of inclined interpenetrating two-dimensional layers, and each layer is constructed by the alternating assembly of left-hand (M) and right-hand (P) cylindrical 2j helices. In 7, dca^- connects Cd^II centers forming a two-dimensional {Cd(dca)₂}_n layer, which is fused with (M)- and (P)-Cd-(4,4′-bpp) helical chains into a three-dimensional structure. The results suggest that the nature of organic ligands and the coordination preferences of transitional metal ions have a great influence on the structures of metal-organic complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejic.200400173

FULL PAPER
Syntheses and Characterizations of Metal-Organic Frameworks with Unusual
Topologies Derived from Flexible Dipyridyl Ligands
Ruihu Wang,[a] Lei Han,[a] Lijin Xu,[b] Yaqiong Gong,[a] Youfu Zhou,[a] Maochun Hong,*[a]
and Albert S. C. Chan[b]
Keywords: Bridging ligands / Cadmium / Coordination polymers / X-ray diffraction / Zinc
Two flexible exo-bidentate ligands, 2,2Ј-bis(3-pyridylmethy- ween adjacent pyridyl rings. The metal-organic frameworks
leneoxy)-1,1Ј-biphenylene (3,3Ј-bpp) and 2,2Ј-bis(4-pyridyl- of 5, 6, and 7 possess unusual topologies: Complex 5 is a two-
methyleneoxy)-1,1Ј-biphenylene (4,4Ј-bpp), were synthesi-
zed and employed for the preparation of coordination poly- zigzag chains, whereas 6 is a polycatenated species consi-
mers. Seven metal-organic complexes, [Zn2(3,3Ј-bpp)2Cl4] sting of inclined interpenetrating two-dimensional layers,
(1), [Zn2(3,3Ј-bpp)2Br4] (2), [Zn(4,4Ј-bpp)Cl2]n (3), [Zn(4,4Ј- and each layer is constructed by the alternating assembly of
dimensional polymer based on folded rectangular boxes and
bpp)Br2]n (4), [Co(4,4Ј-bpp)2(SCN)2]n (5), {[Cd(4,4Ј-
bpp)2(SCN)2]·2H2O}n (6) and [Cd(4,4Ј-bpp)(dca)2]n (7) (dca− =
dicyanamide), have been obtained through self-assembly re-
actions of 3,3Ј-bpp or 4,4Ј-bpp with the divalent metal ions
left-hand (M) and right-hand (P) cylindrical 21 helices. In 7,
dca− connects CdII centers forming
a
two-dimensional
{Cd(dca)2}n layer, which is fused with (M)- and (P)-Cd-(4,4Ј-
bpp) helical chains into a three-dimensional structure. The
ZnII, CoII and CdII. Crystal structure analyses reveal that 1 results suggest that the nature of organic ligands and the
and 2 are dinuclear metallomacrocycles, are isomorphous
and possess a layer network built from metallomacrocycles
through π−π interactions. In drastic contrast, 3 and 4 exhibit
coordination preferences of transitional metal ions have a
great influence on the structures of metal-organic complexes.
a three-dimensional structure consisting of one-dimensional ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
polymeric chains held together through π−π interactions bet-
Germany, 2004)
Introduction
nature of the metal ions,[9] counter anions,[10] the metal/li-
gand ratio,[11] and solvent system.[12] So far, of diverse el-
Metal-directed self-assembly of organic ligands and me- egant efforts to find the key factors in the course of the
tal ions, or organometallic moieties, to form well-defined construction of metal-based supramolecules, the dominant
structures has been a very attractive field in recent and most efficient synthetic strategy is the employment of
years.[1Ϫ6] The increasing interest in this field is justified not various organic ligands as molecular building blocks or tec-
only by the intellectual challenge in controlling and manip- tons. Among these organic ligands, one of the most fruitful
ulating the self-assembly process,[3,4] but also by their fasci- choices has been the use of neutral pyridyl-containing bi-
nating structural diversities and potential application in dentate or multidentate organic building blocks, owing to
functional materials, nanotechnology and biological recog- their simple bridging mode and strong coordination ability
nition.[5,6] In this context, novel supramolecular topologies to transition-metal ions. Rigid, rod-like, exo-bidentate li-
with various sizes and shapes of channels or cavities can be gands, such as 4,4Ј-bipyridine (4,4Ј-bipy),[13,14] are suitable
controlled and tuned through judiciously selecting as- examples of tectons that have been used often for the
sembly-influencing factors, such as structural character- rational design of solid-state architectures of coordination
istics of polydentate organic ligands,[7,8] the coordination polymers. Moreover, structures containing larger holes can
potentially be built by using longer rigid connectors be-
[a]
State Key Laboratory of Structural Chemistry, Fujian Institute tween the pyridyl rings. For example, Fujita et al. have re-
of the Research on the Structure of Matter, Chinese Academy
ported a series of two-dimensional square frameworks with
of Sciences,
different sizes upon increasing the number of phenyl rings
between the pyridyl rings.[15] Compared to rigid bridging
ligands, flexible bridging tectons can produce some unique
frameworks with beautiful aesthetics and useful properties
because of their flexibility and conformational freedom.[16]
However, owing to the difficulty in predicting the structures
of the products, the rational design of coordination poly-
Fuzhou, Fujian 350002, China
Fax: (internat.) ϩ 86-591-3714946
E-mail: hmc@ms.fjirsm.ac.cn
[b]
Open Laboratory of Chirotechnology, Department of Applied
Biology and Chemical Technology, The Hong Kong
Polytechnic University,
Hong Hum, Hong Kong, China
Fax: (internat.) ϩ 852-23649932
E-mail: bcachan@polyu.edu.hk
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DOI: 10.1002/ejic.200400173
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FULL PAPER
mers from flexible ligands is still a formidable challenge.[17] chloride hydrochloride or 4-picolyl chloride hydrochloride
In our previous studies we prepared a series of flexible in the presence of NaOH by a convenient method. The li-
organosulfur ligands by connecting (methylsulfanyl)pyridyl gands are soluble in most solvents, except for water. Treat-
or -pyrimidyl groups to aromatic ring spacers.[18Ϫ21] As- ment of 3,3Ј-bpp with ZnCl2 or ZnBr2 in a 1:1 molar ratio
sembly of such flexible tectons and metal ions resulted in in MeOH/H2O for several hours produced large amounts
several unique structural motifs, such as a metallosupramo- of white precipitates of 1 and 2, respectively, in quantitative
lecular cube,[18] a one-dimensional nanotube,[19] square yield. The elementary analysis results are consistent with
rings with guest molecules,[20] and two-dimensional crown- dinuclear metallomacrocycles of formula Zn2(3,3Ј-bpp)2Cl4
like structures.[20,21] Considering the geometric requirement and Zn2(3,3Ј-bpp)2Br4, respectively. Compounds 1 and 2
of symmetry and stereochemistry, and with the aim of in- are poorly soluble in common solvents except for DMF and
vestigating the effects of distortion of the connector in the DMSO. Hence, 1H NMR spectra were recorded in
dipyridyl ligands on the assembly process and products, we [D6]DMSO; the results confirmed the proposed formula,
have introduced a biphenyl connector into the reaction sys- displaying a symmetric pattern.
tem and prepared two more flexible ligands, 2,2Ј-bis(3-pyri-
It is well known that the relative orientation of coordi-
dylmethyleneoxy)-1,1Ј-biphenylene (3,3Ј-bpp) and 2,2Ј- nation sites in organic ligands is also one of the most im-
bis(4-pyridylmethyleneoxy)-1,1Ј-biphenylene (4,4Ј-bpp), in portant factors for controlling the construction of supra-
which the distortion of the biphenyl connector can endow molecular architectures. Hence, it is expected that the rela-
the metal-organic frameworks with unique structural and tive different orientation of the nitrogen donors in the pyri-
functional properties.[22] Moreover, metal-organic com- dyl rings might lead to unusual building blocks, whose
plexes with a biphenyl connector can be used as simple pro- assembly with metal ions can produce unique structural
bes for the investigation of chiral complexes derived from frameworks. Indeed, assembly of 4,4Ј-bpp with ZnCl2 or
1,1Ј-bi-2-naphthol.[23,24] Herein, we wish to report the ZnBr2 in a 1:1 molar ratio generated the one-dimensional
syntheses and characterizations of two metallomacrocyclic polymeric chain complexes 3 and 4. The directed reaction
complexes based on 3,3Ј-bpp — [Zn2(3,3Ј-bpp)2Cl4] (1) and of 4,4Ј-bpp and ZnCl2 or ZnBr2 in MeOH/H2O afforded
[Zn2(3,3Ј-bpp)2Br4] (2) — and five novel coordination poly- precipitates that are not soluble in any solvents. The MeOH
mers based on 4,4Ј-bpp — [Zn(4,4Ј-bpp)Cl2]n (3), [Zn(4,4Ј- solution of 4,4Ј-bpp was layered on the top of an aqueous
bpp)Br2]n (4), [Co(4,4Ј-bpp)2(SCN)2]n (5), [{Cd(4,4Ј- solution of ZnCl2 or ZnBr2, affording crystals suitable for
bpp)2(SCN)2}·2H2O]n (6), and [Cd(4,4Ј-bpp)(dca)2]n (7) X-ray single-crystal diffraction. Compounds 3 and 4 are in-
(dcaϪ ϭ dicyanamide).
soluble in most common solvents. It is noteworthy that the
ZnII centers in 1Ϫ4 adopt a distorted tetrahedral coordi-
nation geometry, with two halide counteranions coordinat-
ing to a metal center as terminal ligands, preventing the
formation of extended frameworks. This prompted us to
choose either a metal ion with a high coordination number
or bridging counteranions. CoII and CdII are known to be
usually six-coordinate with an octahedral geometry in their
[25]
[26]
pyridyl-containing Co(SCN)2
and Cd(SCN)2
com-
plexes. Reactions of 3,3Ј-bpp with CoII and CdII with differ-
ent counteranions failed to generate desirable single crys-
tals, but we succeeded in the isolation of 5 and 6 by as-
sembly of 4,4Ј-bpp with Co(SCN)2 and Cd(SCN)2 under
the same reaction conditions. Interestingly, the metal cen-
ters demonstrate a similar coordination environment and
the ligands possess the same coordination mode, although
5 and 6 represent two distinctly different structural motifs.
Upon introducing the bridging dcaϪ ligand[27,28] into the
reaction system, the three-dimensional complex 7, con-
sisting of dcaϪCd layers and Cd-(4,4Ј-bpp) helical chains,
was successfully isolated.
In the IR spectra of complexes 1Ϫ7, the absorption
bands of the skeletal vibrations of the aromatic rings appear
in the 1420Ϫ1630 cmϪ1 region. The CϵN stretching vi-
bration of the thiocyanate group in 5 and 6 appears as a
single and very strong peak at 2075 and 2030 cmϪ1, respec-
tively, similar to those found in thiocyanate-N coordi-
nation.[24,25] The IR spectrum in complex 7 displays strong
Result and Discussion
Synthesis and Characterization
The ligands 3,3Ј-bpp and 4,4Ј-bpp are readily prepared absorption bands in the 2170Ϫ1305 cmϪ1 region, indicating
from commercially available 2,2Ј-biphenol and 3-picolyl the presence of CϵN of dcaϪ.[27,28]
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Metal-Organic Frameworks with Unusual Topologies
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Figure 1. Molecular structure of complex 1 with the thermal ellipsoids at 30% probability level
Structural Description
macrocycle are completely parallel, with the distance be-
˚
tween their centroids being 3.922 A, further producing a
[Zn2(3,3Ј-bpp)2Cl4] (1)
layered network formed by stacked macrocycles.[32]
The single-crystal X-ray diffraction analysis of 1 shows a
neutral, dinuclear, metallacyclic structural motif with the
ZnII having a distorted tetrahedral geometry. As shown in
Figure 1, each ZnII is coordinated by two nitrogen atoms
from different 3,3Ј-bpp and two terminal ClϪ ions. The
˚
ZnϪN bond lengths are in the range 2.061(4)Ϫ2.070(5) A,
which are typical values for ZnIIϪNpy coordination dis-
tances.[29] The Cl(1)ϪZnϪCl(2) bond angle [123.52(7)°] is
larger than the N(1)ϪZnϪN(2A) bond angle [99.53(18)°],
probably in order to minimize Cl···Cl interactions. The di-
hedral angle between the two pyridyl rings attached to ZnII
is 83.2°, which means that they are approximately perpen-
dicular; 3,3Ј-bpp acts as an exo-bidentate ligand, where the
pyridyl rings are slightly twisted with respect to the corre-
sponding linking phenyl rings, with the dihedral angles be-
tween them being 24.7° and 26.5°, respectively. The two
phenyl rings about the central bond have a drastic twisting,
with the dihedral angle between them being 130.5°. The
Figure 2. View of packing structure along a axis in 1 showing that
there are no other interactions between adjacent macrocycles
[Zn2(3,3Ј-bpp)2Br4] (2)
Compounds 1 and 2 are isomorphous, which suggests
combination of these twistings allows 3,3Ј-bpp to link that the BrϪ and ClϪ counteranions have no effect on the
ZnCl2 units into a dinuclear metallacycle. The Zn···Zn sep- formation of the metallomacrocycle. As shown in Figure 3,
aration in the cycle is 14.015 A, which is longer than in ZnII is coordinated by two nitrogen atoms from different
˚
known zinc macrocycles.[29] Owing to the high distortion 3,3Ј-bpp ligands and two terminal BrϪ ligands in a dis-
and flexibility of 3,3Ј-bpp, no enclathration of guest mol- torted tetrahedral geometry. The ZnϪN bond lengths and
˚
ecules is observed in 1. There are no other noteworthy weak the NϪZnϪN bond angle are 2.068(8)Ϫ2.085(9) A and
interactions between the adjacent macrocycles. Interest- 98.6(3)°, respectively, similar to those in 1. The dihedral an-
ingly, every macrocycle has significant πϪπ interactions gle of the two pyridyl rings coordinated to ZnII is 81.0°. In
with its four closet neighbors. As shown in Figure 2, one the exo-bidentate 3,3Ј-bpp ligand, the dihedral angles be-
phenyl ring of 3,3Ј-bpp and one pyridyl ring from the adjac- tween the two phenyl rings as well as between the phenyl
ent macrocycle are approximately parallel, with the dihedral rings and their corresponding linking pyridyl rings are
angle between them being 24.7° and the distance between 130.2, 28.5 and 26.1°, respectively. Thus, 3,3Ј-bpp connects
[31]
˚
their centroids being 4.155 A, resulting in the formation ZnBr2 units forming a dinuclear metallomacrocycle with a
˚
of one-dimensional stacked macrocycles; the other phenyl Zn···Zn separation of 14.113 A. Similar to 1, πϪπ interac-
ring of 3,3Ј-bpp and one phenyl ring from another adjacent tions between every macrocycle and its four adjacent
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Figure 3. Molecular structure of complex 2 with the thermal ellipsoids at 30% probability level
macrocycles further stack it into a layered network struc-
ture.
[Zn(4,4Ј-bpp)Cl2]n (3)
The single-crystal X-ray structural analysis reveals that 3
is a one-dimensional zigzag chain formed through intercon-
nection of ZnCl2 units and 4,4Ј-bpp ligands. As shown in
Figure 4, each ZnII is coordinated by two nitrogen atoms
from different 4,4Ј-bpp and two terminal ClϪ ligands in a
distorted tetrahedral coordination environment. The ZnϪN
˚
bond lengths are 2.041(5) and 2.057(4) A, slightly shorter
than those in 1. However, the N(1)ϪZnϪN(2A) bond angle
of 102.93(19)° is larger than that in 1. All the 4,4Ј-bpp li-
gands behave in an exo-bidentate mode and lie on the same
side of the polymer chain. The pyridyl rings are twisted with
respcet to their corresponding linking phenyl rings, with the
dihedral angles between them being 20.8 and 44.6°, respec-
tively. The twisting angle of 76.2° between two phenyl rings
about the central bond is smaller than those in 1 and 2,
Figure 5. View of πϪπ interactions between the adjacent chains
along the c axis in 3
which means that 4,4Ј-bpp connects the ZnCl2 units into a equivalent pyridyl rings from another chain (Figure 5); they
one-dimensional polymeric chain instead of a macrocycle. are approximately parallel, with the dihedral angle between
The adjacent Zn···Zn separation bridged by 4,4Ј-bpp is them being 12.9° and the distance between their centroids
[30]
˚
˚
11.580 A. It should be emphasized that there are significant being 3.817 A (Figure 6). There are no other noteworthy
πϪπ interactions between a pyridyl ring and the adjacent weak interactions between the adjacent chains.
Figure 4. View of the one-dimensional polymeric chain in 3 with the thermal ellipsoids at 30% probability level
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Metal-Organic Frameworks with Unusual Topologies
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Figure 6. View of the packing structure along the b axis in com-
plex 3
Figure 8. View of the folded rectangular box in 5 with the thermal
ellipsoids at 30% probability level
[Zn(4,4Ј-bpp)Br2]n (4)
Compounds 3 and 4 are isomorphous. ZnII is coordi-
nated by two nitrogen atoms from different 4,4Ј-bpp and
two terminal BrϪ ligands in a distorted tetrahedral geo-
metry. The ZnϪN bond lengths and the NϪZnϪN bond
atoms at the axial positions. The four pyridyl units associ-
ated with CoII are arranged in a propeller fashion. The CoII
is approximately coplanar with the mean plane of four
equatorial pyridyl nitrogen atoms, with a deviation of
˚
angles are 2.052(7)Ϫ2.069(7) A and 101.5(1)°, respectively,
similar to those in 3. The ZnϪBr bond lengths of
˚
0.0116 A towards the axial donor atoms. The CoϪNpy
˚
2.3512(15)Ϫ2.3560(13) A and the Br(1)ϪZnϪBr(2) bond
˚
bond lengths range from 2.162(5) to 2.239(5) A [av. 2.201(5)
angle of 119.90(6)° are slightly smaller than their counter-
parts in 2. An exo-bidentate 4,4Ј-bpp ligand bridges a pair
of adjacent ZnII centers on the same side forming a one-
dimensional zigzag chain. The Zn···Zn separation bridged
˚
A], which are longer than the CoϪNNCS bond lengths of
Ϫ
˚
˚
2.062(5) and 2.080(6) A [av. 2.071(6) A]. The SCN groups
are
almost
linear,
with
N(1)ϪC(1)ϪS(1)
and
N(2)ϪC(2)ϪS(2) bond angles of 179.7(6) and 178.6(7)°,
respectively. The connections between CoII and SCNϪ
groups are slightly bent, with C(1)ϪN(1)ϪCo and
C(2)ϪN(2)ϪCo bond angles of 170.1(6) and 174.7(5)°,
respectively, suggesting that the two SCNϪ ligands are not
perpendicular to the equatorial plane. Interestingly, there
are two independent 4,4Ј-bpp ligands in this complex, one
˚
by 4,4Ј-bpp is 11.688 A; πϪπ interaction between the
pyridyl ring and an adjacent pyridyl ring from another
chain stacks the polymeric chains into a network architec-
ture (Figure 7).
[Co(4,4Ј-bpp)2(SCN)2]n (5)
The single-crystal X-ray diffraction analysis reveals that bridges two CoII centers forming a folded rectangular box
5 is a two-dimensional polymer consisting of folded rect- of two planes.[24] The Co···Co separation within the box is
˚
angular boxes (Figure 8) and zigzag chains (Figure 9) 11.446 A. This type of box is similar to that constructed by
bridged by CoII. As shown in Figure 8, each CoII has a dipyridyl ligands with a 1,1Ј-bi-2-naphthol connector and
compressed octahedral coordination environment with four [Pt(dppp)(OSO2CF3)2][24] [dppp ϭ 1,3-bis(diphenylphos-
pyridyl nitrogen atoms from different 4,4Ј-bpp situated in phanyl)propane] and very different from the common rect-
the equatorial plane and two trans-thiocyanato nitrogen angular boxes derived from other exo-bidentate pyridyl-
Figure 7. View of the one-dimensional polymeric chain in 4 with the thermal ellipsoids at 30% probability level
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R. Wang, L. Han, L. Xu, Y. Gong, Y. Zhou, M. Hong, A. S. C. Chan
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Figure 9. View of the zigzag chains in 5
containing ligands.[31] In the 4,4Ј-bpp ligand the dihedral distortion of the biphenyl connector has a great effect on
angle between the two phenyl rings is 65.6°. The dihedral the construction of novel structural motifs (Figure 11).
angle of 50.8° between the two phenyl rings in the other
independent 4,4Ј-bpp unit is smaller than that in the former
and those in complexes 3 and 4, which results in 4,4Ј-bpp
linking two adjacent CoII into a one-dimensional zigzag
chain. Different from 3 and 4, the 4,4Ј-bpp ligands lie on
different sides of the zigzag chain. The closest Co···Co sep-
˚
aration in the zigzag chain is 8.032 A, which is much shorter
than those in the zigzag chains of 3 and 4. The most in-
triguing feature in 5 is that rectangular boxes and zigzag
chains are fused into a two-dimensional polymer through
Co(NCS)2 units (Figure 10). To the best of our knowledge,
this type of complex containing folded rectangular boxes
and zigzag chains is unprecedented, which suggests that the
Figure 11. The packing structure along the b axis in 5 showing the
linkage of the folded rectangular boxes and zigzag chains
[{Cd(4,4Ј-bpp)2(SCN)2}·2H2O]n (6)
Complex 6 is a polycatenated species[6] whose structure is
made up of inclined interpenetrated two-dimensional layers.
Each layer is composed of an alternating assembly of left-
hand (M) and right-hand (P) cylindrical 21 helices along the
b axis.[32] As shown in Figure 12, the coordination sphere of
CdII is defined by four pyridyl nitrogen atoms from differ-
ent 4,4Ј-bpp ligands situated in the equatorial plane and
two trans-thiocyanato nitrogen atoms at the axial positions,
resulting in a compressed octahedral coordination environ-
ment. The CdII is displaced 0.0240 A out of the equatorial
˚
plane. The CdϪNpy and CdϪNSCN bond lengths are in the
˚
˚
range 2.379(5)Ϫ2.405(5)
A
[av. 2.390(5) A] and
˚
˚
2.308(7)Ϫ2.329(6) A [av. 2.319(7) A], respectively. The
SCNϪ groups are almost linear, with N(1)ϪC(1)ϪS(1) and
N(2)ϪC(2)ϪS(2) bond angles of 177.9(9) and 174.0(8)°,
respectively. The two SCNϪ groups are not perpendicular
to the equatorial plane and the C(1)ϪN(1)ϪCd and
C(2)ϪN(2)ϪCd bond angles are 135.3(6) and 139.6(6)°,
Figure 10. The two-dimensional structure formed by the folded
rectangular boxes and zigzag chains in 5
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Metal-Organic Frameworks with Unusual Topologies
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Figure 12. View of the coordination environment of CdII in 6 with the thermal ellipsoids at 30% probability level
respectively. These values are similar to those in complex 5. angles between phenyl rings and their corresponding link-
It should be emphasized that there are two independent ing pyridyl rings are 23.3 and 6.0°, respectively. A drastic
4,4Ј-bpp ligands in this complex, one of which bridges six- twisting is observed between two phenyl rings, with a di-
coordinate CdII forming an (M) helical column (Figure 13). hedral angle of 116.9°, which is much larger than those in
˚
The repeating period in the helical column is 17.050 A, 3Ϫ5 and leads to the formation of the helical column. Inter-
which is slightly longer than the Cd···Cd distance bridged estingly, the other cis ligand coordinates to CdII and forms
˚
by 4,4Ј-bpp (16.590 A). In the 4,4Ј-bpp ligand the dihedral a (P) helical column (Figure 13). The distance of the helical
pitch and Cd···Cd separation bridged by 4,4Ј-bpp are
˚
17.050 and 16.668 A, respectively. In the 4,4Ј-bpp ligand
the dihedral angles between the two phenyl rings as well as
between the phenyl rings and their corresponding linking
pyridyl rings are 118.1, 32.9 and 10.9°, respectively, which
are slightly different from the other 4,4Ј-bpp ligand These
two types of cylindrical columns are alternatively connec-
ted, with the Cd(SCN)2 units functioning as hinges, for-
ming a unique two-dimensional layer structure (Figures 14
and 15). It should be emphasized that the longer helical
pitch and the 4,4Ј-bpp ligands result in the formation of
larger void cavities in the two-dimensional network, which
greatly exceeds that required to accommodate the guest
molecules in the reaction system. Thus, instead of forming
an open, microporous structure, the potential voids are
filled by mutually inclined interpenetration of identical two-
dimensional frameworks (Figure 16). Uncoordinated water
molecules act as guest molecules and further fill in its space.
Figure 13. View of the left-hand and right-hand cylindrical 21
helices in 6 with uncoordinated water molecules omitted for clarity
Figure 14. View of the two-dimensional layer along the b axis in 6 with uncoordinated water molecules omitted for clarity
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3757

R. Wang, L. Han, L. Xu, Y. Gong, Y. Zhou, M. Hong, A. S. C. Chan
FULL PAPER
[Cd(4,4Ј-bpp)(dca)2]n (7)
Complex 7 consists of two-dimensional Cd(dca)2 layers
bridged by 4,4Ј-bpp ligands. As shown in Figure 17, CdII is
coordinated by six nitrogen atoms in a distorted octahedral
geometry, in which four nitrogen atoms from different dcaϪ
ligands form the equatorial plane, and two pyridyl nitrogen
atoms from different 4,4Ј-bpp occupy the apical positions.
The CdϪNdca and CdϪNpy bond lengths are in the range
˚
˚
2.317(6)Ϫ2.475(7) A [av. 2.367(7) A] and 2.321(6)Ϫ2.352(7)
Ϫ
˚
˚
A [av. 2.337(7) A], respectively; dca has two distinctly dif-
ferent bridging modes: one adopts a usual end-to-end µ-1,5
bridging mode,[27] and the other acts as a rare µ-1,3 bridge
through a terminal nitrile nitrogen atom and the middle
nitrogen atom.[28] These two types of dcaϪ bridge CdII to
form a neutral two-dimensional layer structure (Figure 18).
The Cd···Cd separations bridged by µ-1,5- and µ-1,3-dcaϪ
˚
are 7.725 and 6.050 A, respectively. The 4,4Ј-bpp ligand acts
as an exo-bidentate ligand; the dihedral angle between two
phenyl rings is 131.6°. However, the dihedral angles be-
tween the phenyl rings and their corresponding linking pyr-
idyl rings are 10.1 and 19.1°, respectively. As a result, the
4,4Ј-bpp ligands are situated at two sides of the layers to
saturate the six-coordinate CdII center and connect the
CdϪdca layers into a three-dimensional network. It is note-
Figure 15. Packing structure along the c axis in 6 with uncoordi-
nated water molecules omitted for clarity
Although there have been many helical coordination poly-
mers reported, to the best our knowledge this type of helix-
assembled polycatenated motif is unprecedented.
Figure 18. The two-dimensional layer formed by dcaϪ and CdII
along the c axis in 7
Figure 16. Packing structure of the inclined interpenetrating two-
dimensional layers in 6 with partial atoms omitted for clarity
Figure 17. View of the coordination environment of CdII in 7 with the thermal ellipsoids at 30% probability level
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Eur. J. Inorg. Chem. 2004, 3751Ϫ3763

Metal-Organic Frameworks with Unusual Topologies
FULL PAPER
Figure 19. (M)- (light) and (P)-Cd-(4,4Ј-bpp) (dark) helical chains bridged by µ-1,3-dca in 7
worthy that the 4,4Ј-bpp ligands bridge CdII to form (M) 4,4Ј-bpp are responsible for the formation of the structural
and (P) helical chains (Figure 19). Different from 6, the ad- motifs. Owing to the steric hindrance from the relative
jacent (M) and (P) helical chains are connected by µ-1,3- orientation of the coordination sites in the pyridyl rings,
dca ligands instead of metal centers. The distance of the 3,3Ј-bpp and 4,4Ј-bpp bridge ZnCl2 or ZnBr2 units generat-
helical pitch and Cd···Cd distance bridged by 4,4Ј-bpp are ing metallomacrocycles and one-dimensional zigzag chains
˚
29.629 and 15.697 A, respectively. Hence, complex 7 can be with 4,4Ј-bpp at the same sides, respectively. The distortion
regarded as the fusion of two-dimensional Cd(dca)2 layers angles of the biphenyl connector in 3,3Ј-bpp (130.5° for 1
with (M)- and (P)-Cd-(4,4Ј-bpp) helical chains through and 130.2° for 2) are much larger than those in 4,4Ј-bpp
CdII centers (Figure 20).
(76.2° for 3 and 79.6° for 4); however, the distortion angles
of the biphenyl connector of 50.8 and 65.6° in 4,4Ј-bpp in
5, which are smaller than those in the polymeric chains of
3 and 4, lead to the formation of a one-dimensional zigzag
chain with 4,4Ј-bpp at two sides and a folded rectangular
box, respectively. When the distortion angles of the biphe-
nyl connector in 4,4Ј-bpp increase to 116.9 and 118.1°, cyl-
indrical 21 helical structures are generated. The largest dis-
tortion angle of the biphenyl connector in 4,4Ј-bpp (131.6°)
results in a one-dimensional helical chain in complex 7.
Correspondingly, the dihedral angles between the phenyl
rings and linking pyridyl rings are different in each type of
structural motif. In the zigzag chain with 4,4Ј-bpp at two
sides, the smallest twisting angle of the biphenyl connector
in 4,4Ј-bpp (50.8°) results in the shortest distance between
˚
the metal centers bridged by 4,4Ј-bpp (8.032 A) in 5; the
Figure 20. Packing structure along the a axis in 7 showing the
linkage of the helical chains and the two-dimensional layer
longest distance is found in the right-handed cylindrical 21
˚
helix (16.668 A) of complex 6. It should be emphasized that
It should be interesting and essential to compare the re-
lated structural data of 3,3Ј-bpp and 4,4Ј-bpp in complexes
1Ϫ7. As suggested in Table 1, the twisting angles of the bi-
phenyl connector about the central bond in 3,3Ј-bpp and
the two phenyl rings in free 4,4Ј-bpp can rotate freely about
the central bond, but the rotation is restricted in metal-or-
ganic complexes because of pyridyl-N coordination; conse-
quently, this restricted rotation gives rise to two confor-
Table 1. Comparison of the structural data from 3,3Ј-bpp or 4,4Ј-bpp in 1Ϫ7
Compound
Ligand
Dihedral angles [°]
Distance between metal
centers bridged by ligand [A]
Structure
˚
[a]
[b]
[c]
1
2
3
4
5
3,3Ј-bpp
3,3Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
4,4Ј-bpp
130.5
130.2
76.2
79.6
65.6
24.7 and 26.5
26.1 and 28.5
20.8 and 44.6
15.1 and 42.8
21.6 and 45.3
24.1 and 49.5
23.3 and 6.0
32.9 and 10.9
10.1 and 19.1
83.2
81.0
76.0
77.7
74.9
77.4
80.8
89.3
18.6
14.015
14.113
11.580
11.688
11.446
8.032
16.590
16.668
15.697
dimetallomacrocycle
dimetallomacrocycle
1D polymeric chain
1D polymeric chain
folded rectangular box
1D zigzag chain
(M) cylindrical 21 helix
(P) cylindrical 21 helix
1D helical chain
50.8
6
116.9
118.1
131.6
7
[a]
[b]
[c]
Biphenyl connector in the ligand. Between the phenyl ring and the corresponding linking pyridyl ring. Between two pyridyl rings
at the metal center.
Eur. J. Inorg. Chem. 2004, 3751Ϫ3763
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R. Wang, L. Han, L. Xu, Y. Gong, Y. Zhou, M. Hong, A. S. C. Chan
FULL PAPER
mations [(M) and (P)] in complexes 6 and 7.[22] Therefore,
the flexibility of ligands, the coordination propensity of me-
tal ions and the secondary ligands play important roles in
the formation of the final networks, meaning that the struc-
tural topologies of complexes 5, 6, and 7 are unusual.
a Fisons VG platform. The IR spectra as KBr disks were recorded
with a Magna 750 FT-IR spectrophotometer. C, H and N elemen-
tal analyses were determined with an Elementary Vario ELIII el-
emental analyzer.
Synthesis of 3,3Ј-bpp: A mixture of 2,2Ј-biphenol (1.86 g, 10 mmol),
3-picolyl chloride hydrochloride (3.61 g, 22 mmol) and NaOH
(1.76 g, 44 mmol) in acetone (50 mL) was stirred at reflux under
nitrogen for 3 d. After cooling to room temperature, the inorganic
salt was removed by filtration and washed with acetone several
times. The combined solutions were concentrated under reduced
pressure and the red residue was dissolved in ethyl acetate and then
washed twice with water and once with brine. The organic layer
was dried with anhydrous Na2SO4 and filtered. After removal of
the solvent under reduced pressure, the residue was purified by
chromatography on silica gel to afford a colorless solid. Yield:
3.24 g (88% based on 2,2Ј-biphenol). 1H NMR (500 MHz, CDCl3):
δ ϭ 8.44 (d, J ϭ 3.0 Hz, 2 H, H2), 8.38 (s, 2 H, H1), 7.40 (d, J ϭ
7.5 Hz, 2 H, H4), 7.30Ϫ7.34 (m, 2 H, H3), 7.29 (d, J ϭ 1.5 Hz, 2
Conclusions
Seven novel metal-organic complexes containing the flex-
ible dipyridyl ligands 2,2Ј-bis(3-pyridylmethyleneoxy)-1,1Ј-
biphenylene (3,3Ј-bpp) and 2,2Ј-bis(4-pyridylmethy-
leneoxy)-1,1Ј-biphenylene (4,4Ј-bpp) have been prepared
and structurally characterized. In complexes 1Ϫ4, exo-bi-
dentate 3,3Ј-bpp and 4,4Ј-bpp ligands link ZnX2 (X ϭ ClϪ
and BrϪ) units into dinuclear metallomacrocycles and one-
dimensional zigzag chains, respectively, in which the metal
centers adopt a distorted tetrahedral geometry. This reveals H, H9), 7.04Ϫ7.11 (m, 4 H, H7, H8), 7.00 (d, J ϭ 8.5 Hz, 2 H, H6),
4.96 (s, 4 H, H5) ppm. 13C NMR (CDCl3, 125 MHz): δ ϭ 155.6
that the relative orientation of the nitrogen donors in the
(C7), 148.7 (C1), 148.0 (C2), 134.4 (C4), 132.7 (C5), 131.4(C12),
pyridyl rings has a great influence on the construction of
128.7(C9, C11), 123.1 (C3), 121.2 (C10), 112.9 (C8), 67.9 (C6) ppm.
the supramolecular architectures. The metal centers in both
ES-MS: m/z ϭ 368 [Mϩ ϩ 1]. HRMS: calcd for C24H20N2O2 [Mϩ
5 and 6 all have a compressed octahedral geometry, al-
though Co(SCN)2 and Cd(SCN)2 hinges fuse one-dimen-
ϩ 1]: m/z ϭ 368.4342; found 368.4345.
sional zigzag chains and folded rectangular boxes as well as
left-handed and right-handed cylindrical 21 helices into two of 3,3Ј-bpp except that 4-picolyl chloride hydrochloride was used
Synthesis of 4,4Ј-bpp: The procedure was similar to the synthesis
instead of 3-picolyl chloride hydrochloride. Yield: 2.75 g (75%
based on 2,2Ј-biphenol). 1H NMR (500 MHz, CDCl3): δ ϭ 8.37
(d, J ϭ 6.0 Hz, 4 H, H1), 7.27 (d, J ϭ 7.5 Hz, 4 H, H2), 7.04 (d,
J ϭ 7.0 Hz, 2 H, H9), 6.97 (d, J ϭ 5.5 Hz, 4 H, H6 and H8), 6.88
(d, J ϭ 7.5 Hz, 2 H, H7), 4.92 (s, 4 H, H5) ppm. 13C NMR (CDCl3,
125 MHz): δ ϭ 155.7 (C5), 149.8 (C1), 146.6 (C3), 131.7 (C7), 129.0
(C10), 128.5 (C9), 121.5 (C8), 121.0 (C2), 112.6 (C6), 68.5 (C4) ppm.
ES-MS: m/z ϭ 368 [Mϩ ϩ 1]. HRMS: calcd for C24H20N2O2 [Mϩ
ϩ 1]: m/z ϭ 368.4342; found 368.4349.
distinctly different two-dimensional networks. The topo-
logical differences in complexes 3Ϫ6 are attributed to the
different geometric requirement of the metal ions. The re-
sults of structural analyses of 3Ϫ6 containing 4,4Ј-bpp re-
veal that their structures mainly depend on the geometric
requirement of the metal ions and are not influenced greatly
by the counteranions, which only act as terminal ligands.
The introduction of bridging dcaϪ counteranions into the
reaction system produces a three-dimensional complex 7, in
which 4,4Ј-bpp functions as a bridge between the adjacent
CdϪdca layers. Such differences in 1Ϫ7 are realized
through the distortion of the biphenyl connector in 3,3Ј-
bpp and 4,4Ј-bpp. In summary, this research shows that as-
sembly of dipyridyl ligands with a biphenyl connector and
metal ions can generate unique structural motifs, which
cannot be obtained using normal rigid or flexible exo-bi-
Synthesis of [Zn2(3,3Ј-bpp)2Cl4] (1): A solution of ZnCl2 (0.034 g,
0.25 mmol) in H2O (10 mL) was slowly added to a stirring solution
of 4,4Ј-bpp (0.092 g, 0.25 mmol) in MeOH (10 mL) to give a white
precipitate. The reaction mixture was heated to 60 °C and DMF
was added dropwise (about 1 mL) until the precipitate dissolved.
The resulting solution was filtered and kept in air at room tempera-
ture for two weeks. Colorless crystals of 1 suitable for X-ray diffrac-
tion were obtained. Yield: 0.08 g (63%). C24H20Cl2N2O2Zn
dentate organic ligands, such as 4,4Ј-bipy and related or- (504.69): calcd. C 57.11, H 3.96, N 5.55; found C 57.09, H 4.98, N
5.57. 1H NMR (500 MHz, CDCl3): δ ϭ 8.44 (s, 4 H), 8.42 (s, 4 H),
7.58 (d, J ϭ 7.5 Hz, 4 H), 7.33 (t, J ϭ 7.5 Hz, 15 Hz, 4 H),
7.27Ϫ7.29 (m, 4 H), 7.23 (dd, J ϭ 2.0, 7.5 Hz, 4 H), 7.16 (d, J ϭ
ganic ligands. In this regard, we are currently using these
results as probes for axial chiral ligands derived from 1,1Ј-
bi-2-naphthol and extending our research to prepare chiral
supramolecular species.
8.0 Hz, 4 H), 7.02 (t, J ϭ 7.0 Hz, 14 Hz, 4 H), 5.10 (s, 8 H) ppm.
IR (KBr pellet): ν˜ ϭ 3121 cmϪ1 (vw), 3047 (w), 2913 (vw), 2858
(w), 1614 (m), 1593 (m), 1564 (w), 1504 (w), 1482 (s), 1456 (m),
1436 (s), 1431 (s), 1387 (m), 1335 (w), 1265 (s), 1234 (s), 1194 (m),
Experimental Section
1163 (w), 1125 (s), 1057 (m), 1032 (s), 1002 (m), 933 (vw), 867 (w),
814 (w), 796 (m), 766 (s), 697 (m), 658 (m), 642 (w), 613 (vw), 540
(vw), 486 (vw), 453 (vw).
General: 2,2Ј-Biphenol, 3-picolyl chloride hydrochloride and 4-pic-
olyl chloride hydrochloride were purchased from Acros. All other
chemicals are commercially available and were used as purchased
Synthesis of [Zn2(3,3Ј-bpp)2Br4] (2): The procedure was similar to
without further purification. The NMR spectra were recorded with the synthesis of complex 1 except that ZnBr2 (0.056 g, 0.25 mmol)
a Varian Inova-500 spectrophotometer at room temperature and
the chemical shifts are quoted in δ (ppm) relative to the deuterated
solvent used. The mass spectra were recorded in the Mass Spec-
trometry Laboratory of the Department of Applied Biology and
was used instead of ZnCl2. Yield: 0.10 g (67%). C24H20Br2N2O2Zn
(593.61): calcd. C 48.56, H 3.37, N 4.72; found C 48.52, H 3.40, N
4.70. 1H NMR (500 MHz, CDCl3): δ ϭ 8.44 (s, 4 H), 8.43 (s, 4 H),
7.58 (d, J ϭ 7.0 Hz, 4 H), 7.33 (t, J ϭ 8.5 Hz, 17 Hz, 4 H),
Chemical Technology, The Hong Kong Polytechnic University with 7.28Ϫ7.31 (m, 4 H), 7.23 (d, J ϭ 6.0 Hz, 4 H), 7.16 (d, J ϭ 7.0 Hz,
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Eur. J. Inorg. Chem. 2004, 3751Ϫ3763

Metal-Organic Frameworks with Unusual Topologies
FULL PAPER
4 H), 7.02 (t, J ϭ 7.0 Hz, 14 Hz, 4 H), 5.10 (s, 8 H) ppm. IR (KBr X-ray Crystallographic Study: Intensity data for complexes 1Ϫ7
pellet): ν˜ ϭ 3121 cmϪ1 (vw), 3045 (w), 2910 (w), 2858 (w), 1614 were measured with a Siemens Smart CCD diffractometer with
(m), 1595 (m), 1563 (vw), 1504 (w), 1483 (s), 1458 (m), 1437 (s),
1385 (m), 1335 (w), 1284 (w), 1263 (s), 1232 (s), 1194 (m), 1165
(w), 1124 (s), 1057 (m), 1034 (s), 1020 (m), 1001 (m), 933 (vw), 912
[a]
˚
Table 2. Selected bond lengths [A] and angles [°] for 1Ϫ7
(vw), 866 (w), 793 (m), 764 (s), 698 (s), 658 (m), 615 (vw), 544 (vw),
486 (vw), 454 (vw).
Complex 1
ZnϪN(1)
ZnϪCl(1)
2.061(4) ZnϪN(2A)
2.2245(17) ZnϪCl(2)
99.53(18) N(1)ϪZnϪCl(2)
2.070(5)
2.2150(16)
108.83(14)
103.74(14)
Synthesis of [Zn(4,4Ј-bpp)Cl2]n (3): A solution of 4,4Ј-bpp (0.037 g,
0.1 mmol) in MeOH (5 mL) was carefully layered on top of a solu-
tion of ZnCl2 (0.014 g, 0.1 mmol) in H2O (5 mL). Diffusion be-
tween the two phases over a period of two weeks produced colorless
crystals. Yield: 0.04 g (79%). C24H20Cl2N2O2Zn (504.69): calcd. C
57.11, H 3.96, N 5.55; found C 57.07, H 4.02, N 5.53. IR (KBr
pellet): ν˜ ϭ 3121 cmϪ1 (vw), 3052 (w), 2916 (w), 2852 (w), 1624
(s), 1593(m), 1563 (w), 1504 (m), 1481 (m), 1450 (s), 1436 (s), 1390
(m), 1329 (vw), 1306 (m), 1265 (s), 1234 (s), 1163 (vw), 1121 (m),
1057 (m), 1032 (s), 1005 (w), 933 (vw), 866 (w), 814 (s), 786 (m),
752 (s), 642 (w), 613 (vw), 486 (w), 453 (vw).
N(1)ϪZnϪN(2A)
N(2A)ϪZnϪCl(2) 105.96(14) N(1)ϪZnϪCl(1)
N(2A)ϪZnϪCl(1) 112.60(14) Cl(2)ϪZnϪCl(1) 123.52(7)
Complex 2
ZnϪN(1)
ZnϪBr(1)
N(1)ϪZnϪN(2A)
N(2A)ϪZnϪBr(1) 106.9(2)
N(2A)ϪZnϪBr(2) 113.0(2)
2.068(8) ZnϪN(2A)
2.3614(16) ZnϪBr(2)
2.085(9)
2.3674(16)
108.7(2)
105.1(2)
98.6(3)
N(1)ϪZnϪBr(1)
N(1)ϪZnϪBr(2)
Br(1)ϪZnϪBr(2) 121.92(6)
Synthesis of [Zn(4,4Ј-bpp)Br2]n (4): The procedure was similar to
the synthesis of complex 3 except that ZnBr2 (0.023 g, 0.1 mmol)
was used instead of ZnCl2. Yield: 0.05 g (84%). C24H20Br2N2O2Zn
(593.61): calcd. C 48.56, H 3.37, N 4.72; found C 48.51, H 3.39, N
4.68. IR (KBr pellet): ν˜ ϭ 3121 cmϪ1 (vw), 3062 (w), 2910 (w),
2856 (w), 1624 (s), 1593 (m), 1563 (w), 1504 (s), 1481 (s), 1440 (s),
1431 (s), 1387 (s), 1328 (w), 1284 (s), 1267 (s), 1234 (s), 1158 (w),
1121 (s), 1056 (s), 1030 (s), 1005 (m), 933 (vw), 912 (vw), 864 (w),
829 (w), 810 (s), 770 (s), 750 (s), 717 (w), 641 (m), 613 (vw), 544
(vw), 513 (vw), 486 (w), 454 (w).
Complex 3
ZnϪN(1)
ZnϪCl(1)
2.041(5) ZnϪN(2A)
2.2155(17) ZnϪCl(2)
2.057(4)
2.2153(16)
108.90(14)
108.01(14)
N(1)ϪZnϪN(2A) 102.93(19) N(1)ϪZnϪCl(2)
N(2A)ϪZnϪCl(2) 108.58(14) N(1)ϪZnϪCl(1)
N(2A)ϪZnϪCl(1) 106.27(14) Cl(2)ϪZnϪCl(1) 120.71(7)
Complex 4
ZnϪN(1)
ZnϪBr(1)
2.052(7) ZnϪN(2A)
2.3512(15) ZnϪBr(2)
2.069(7)
2.3560(13)
Synthesis of [Co(4,4Ј-bpp)2(SCN)2]n (5): The procedure was similar
to the synthesis of complex 3 except that Co(NO3)2·6H2O (0.029 g,
0.1 mmol) and NH4SCN (0.015 g, 0.2 mmol) were used instead of
ZnCl2. Yield: 0.04 g (88% based on 4,4Ј-bpp). C50H40CoN6O4S2
(911.93): calcd. C 65.85, H 4.39, N 9.21; found C 65.82, H 4.42, N
9.18. IR (KBr pellet): ν˜ ϭ 3423 cmϪ1 (w), 3064 (w), 2914 (w), 2854
(w), 2075 (vs), 1618 (s), 1595 (m), 1564 (w), 1504 (m), 1483 (m),
1441 (s), 1421 (s), 1385 (m), 1325 (w), 1271 (s), 1225 (s), 1163 (vw),
1113 (m), 1057 (m), 1016 (m), 939 (vw), 810 (m), 762 (s), 634 (w),
618 (vw), 494 (w).
N(1)ϪZnϪN(2A) 101.8(3)
N(2A)ϪZnϪBr(1) 107.9(2)
N(2A)ϪZnϪBr(2) 108.1(2)
N(1)ϪZnϪBr(1)
N(1)ϪZnϪBr(2)
Br(1)ϪZnϪBr(2) 119.90(6)
108.1(2)
109.5(2)
Complex 5
CoϪN(1)
CoϪN(5)
CoϪN(3)
N(1)ϪCoϪN(2)
N(2)ϪCoϪN(5)
2.062(5) CoϪN(2)
2.162(5) CoϪN(6A)
2.222(5) CoϪN(4B)
176.6(2) N(1)ϪCoϪN(5)
2.080(6)
2.181(5)
2.239(5)
87.1(2)
92.15(19) N(1)ϪCoϪN(6A) 93.8(2)
N(2)ϪCoϪN(6A) 89.53(19) N(5)ϪCoϪN(6A) 91.94(18)
Synthesis of [{Cd(4,4Ј-bpp)2(SCN)2}·2H2O]n (6): The procedure was
similar to the synthesis of complex 3 except that Cd(NO3)2·6H2O
(0.031 g, 0.1 mmol) and NH4SCN (0.015 g, 0.2 mmol) were used
instead of ZnCl2. Yield: 0.04 g (80% based on 4,4Ј-bpp).
C50H44CdN6O6S2 (1001.4): calcd. C 59.96, H 4.39, N 8.39; found
C 59.91, H 4.37, N 8.32%. IR (KBr pellet): ν˜ ϭ 3435 cmϪ1 (w),
3120 (w), 2914 (w), 2852 (w), 2033 (vs), 1615 (s), 1596 (m), 1562
(w), 1504 (w), 1479 (m), 1436 (s), 1423 (s), 1399 (m), 1324 (vw),
1269 (m), 1231 (s), 1161 (vw), 1126 (m), 1062 (m), 1013 (m), 939
(vw), 814 (m), 751 (m), 635 (w), 619 (vw), 486 (w).
N(1)ϪCoϪN(3)
N(5)ϪCoϪN(3)
N(1)ϪCoϪN(4B)
89.0(2)
95.59(18) N(6A)ϪCoϪN(3) 172.08(18)
89.1(2) N(2)ϪCoϪN(4B) 91.78(19)
N(2)ϪCoϪN(3)
87.73(19)
N(5)ϪCoϪN(4B) 175.97(19) N(6A)ϪCoϪN(4B) 87.20(19)
N(3)ϪCoϪN(4B)
C(2)ϪN(2)ϪCo
85.45(19) C(1)ϪN(1)ϪCo
174.7(5) N(1)ϪC(1)ϪS(1) 179.7(6)
170.1(6)
N(2)ϪC(2)ϪS(2) 178.6(7)
Complex 6
CdϪN(1)
2.329(6) CdϪN(2)
2.308(7)
CdϪN(3)
CdϪN(5)
2.405(5)
2.379(5)
Synthesis of [Cd(4,4Ј-bpp)(dca)2]n (7): The procedure was similar to
the synthesis of complex 3 except that Cd(NO3)2·4H2O (0.031 g,
0.1 mmol) and Na(dca)2 (0.018 g, 0.2 mmol) were used instead of
ZnCl2. Yield: 0.05 g (82%). C28H20CdN8O2 (612.92): calcd. C
54.87, H 3.26, N 18.27; found C 54.85, H 3.29, N 18.25. IR (KBr
pellet): ν˜ ϭ 3529 cmϪ1 (w), 3061 (w), 2916 (w), 2891 (w), 2845 (w),
2305 (s), 2258 (s), 2229 (vs), 2170 (vs), 1618 (m), 1597 (w), 1562
(w), 1504 (w), 1479 (m), 1425 (s), 1369 (m), 1327 (w), 1306 (m),
1263 (s), 1252 (s), 1227 (s), 1161 (vw), 1124 (m), 1061 (m), 1018
(m), 933 (w), 816 (s), 802 (m), 756 (s), 638 (w), 613 (vw), 510 (w),
490 (m), 467 (vw).
N(2)ϪCdϪN(1)
N(1)ϪCdϪN(3)
N(1)ϪCdϪN(4B)
N(2)ϪCdϪN(5)
N(2)ϪCdϪN(4B)
N(3)ϪCdϪN(4B)
N(6A)ϪCdϪN(4B) 91.37(17) N(6A)ϪCdϪN(3) 178.39(17)
N(6A)ϪCdϪN(5) 88.19(17) C(1)ϪN(1)ϪCd 135.3(6)
C(2)ϪN(2)ϪCd 139.6(6) N(1)ϪC(1)ϪS(1) 177.9(9)
N(2)ϪC(2)ϪS(2) 174.0(8)
88.5(2)
89.22(19)
90.26(17)
Eur. J. Inorg. Chem. 2004, 3751Ϫ3763
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3761

R. Wang, L. Han, L. Xu, Y. Gong, Y. Zhou, M. Hong, A. S. C. Chan
FULL PAPER
Table 2. (continued)
Complex 7
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2.318(8) CdϪN(11)
2.324(10) CdϪN(3)
2.359(9) CdϪN(5C)
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93.2(3)
92.9(4)
86.2(3)
92.1(3)
N(4)ϪCdϪN(1A)
N(4)ϪCdϪN(3)
N(1A)ϪCdϪN(3)
N(11)ϪCdϪN(12B) 169.0(3)
N(3)ϪCdϪN(12B) 88.9(3)
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[8b]
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N(1A)ϪCdϪN(5C) 178.7(3)
N(12B)ϪCdϪN(5C) 82.5(3)
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