Crystal structures of two- and three-dimensional polymeric complexes assembled by metal pseudohalides and 4-aminobenzoic acid via hydrogen bonds and covalent bonds

Article abstract of DOI:10.1016/S0020-1693(01)00791-5

Four polymeric complexes [M(SCN)₂(4-abaH)₂]_n [M = Co(II) (1) or Cd(II) (2), 4-abaH=4-aminobenzoic acid], [Zn(N₃)(4-aba)]_n (3) and [Cd(N₃)(4-aba)(H₂O)]_n (4) were prepared from the reactions of 4-abaH with M(SCN)₂ [M = Co(II) or Cd(II)] and M(N₃)₂ [M = Zn(II) or Cd(II)] at different pH values. Their crystal structures have been determined by single-crystal X-ray diffraction. Both 1 and 2 consist of one-dimensional chains [M(μ-1,3-SCN)₂(4-abaH)₂]_n, in which each pair of the lateral carboxylic groups form double hydrogen bonds to furnish infinite two-dimensional sheets. In 3, the Zn(II) atoms are bridged by μ-1,1-azide groups and μ₂-carboxylate-O,O′ groups into an infinite zigzag chain featuring six-membered (Zn-N-Zn-O-C-O-)_n rings, which are further connected by the 4-aba-N,O,O′ groups to generate a two-dimensional network. In 4, however, adjacent Cd(II) atoms are bridged by μ-1,1,3-azide groups to form an infinite chain with both four-membered Cd₂(μ-1,1-N₃)₂ and eight-membered Cd₂(μ-1,3-N₃)₂ rings. These chains are further connected by the 4-aba-N,O groups to generate a three-dimensional brickwall-like network. The results show significant effect of pH on the formation of the network structures.

Full text of DOI:10.1016/S0020-1693(01)00791-5

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Inorganica Chimica Acta 329 (2002) 13–21
Crystal structures of two- and three-dimensional polymeric
complexes assembled by metal pseudohalides and 4-aminobenzoic
acid via hydrogen bonds and covalent bonds
Hong-Ji Chen a,b, Xiao-Ming Chen a,*
a School of Chemistry and Chemical Engineering, Zhongshan Uni6ersity, Guangzhou 510275, People’s Republic of China
b Department of Chemistry, Jinan Uni6ersity, Guangzhou 510632, People’s Republic of China
Received 8 June 2001; accepted 12 October 2001
Abstract
Four polymeric complexes [M(SCN)2(4-abaH)2]n [M=Co(II) (1) or Cd(II) (2), 4-abaH=4-aminobenzoic acid], [Zn(N3)(4-
aba)]n (3) and [Cd(N3)(4-aba)(H2O)]n (4) were prepared from the reactions of 4-abaH with M(SCN)2 [M=Co(II) or Cd(II)] and
M(N3)2 [M=Zn(II) or Cd(II)] at different pH values. Their crystal structures have been determined by single-crystal X-ray
diffraction. Both 1 and 2 consist of one-dimensional chains [M(m-1,3-SCN)2(4-abaH)2]n, in which each pair of the lateral
carboxylic groups form double hydrogen bonds to furnish infinite two-dimensional sheets. In 3, the Zn(II) atoms are bridged by
m-1,1-azide groups and m2-carboxylate-O,O% groups into an infinite zigzag chain featuring six-membered (ZnꢀNꢀZnꢀOꢀCꢀOꢀ)n
rings, which are further connected by the 4-aba-N,O,O% groups to generate a two-dimensional network. In 4, however, adjacent
Cd(II) atoms are bridged by m-1,1,3-azide groups to form an infinite chain with both four-membered Cd2(m-1,1-N3)2 and
eight-membered Cd2(m-1,3-N3)2 rings. These chains are further connected by the 4-aba-N,O groups to generate a three-dimen-
sional brickwall-like network. The results show significant effect of pH on the formation of the network structures. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: 4-Aminobenzoic acid; Transition metal pseudohalides; Coordination polymers; Self-assembly; Hydrogen bonding
frameworks including helical [6,8], diamondoid and
honeycomb [2b], square [3c] or rectangular [2a] grid,
1. Introduction
T-shaped [3d], ladder [2a,4,7] and other uncommon
frameworks. Generally, the construction of frameworks
can been achieved by using either covalent bonds or
weaker intermolecular forces, e.g. hydrogen bonds,
aryl–aryl interactions, etc. [10].
As part of our investigation on rational design and
preparation of functional coordination frameworks, we
have recently reported a number of transition metal
coordination polymers with the organic spacers such as
imidazole, 4,4%-bipyridine and 4,4%-oxydianiline [11]. We
found that besides the linear pyridyl-like ligands, ani-
line-like ones are also effective organic spacers to con-
struct coordination supramolecular frameworks even
though they are weaker in coordination ability than the
pyridyl ones [11c,12]. We now extend our work to
include another bifunctional organic ligand 4-
aminobenzoic acid (4-abaH), and report herewith two
Crystal engineering of metal-organic framework ma-
terials has evolved rather rapidly in recent years be-
cause this kind of materials may have interesting
physicochemical properties and potential applications
such as adsorption, ion exchange, shape-selective catal-
ysis, non-linear optical and magnetic materials [1]. A
number of organic spacers (such as pyrazine [2], 4,4%-
bipyridine [2b,3], 1,4-bis(4-pyridyl)benzene [4], 1,4-
bis(imidazol-1-yl-methyl)benzene [5], 3,6-di(4-pyridyl)-
1,2,4,5-tetrazine [6], 1,4-bis(4-pyridyl)butadiyne [7], 1,3-
bis(4-pyridyl)propane [8], 1,2-bis(4-pyridyl)ethane [9],
etc.) have been used to produce a large number of
metal-organic materials exhibiting interesting topolo-
gies, including infinite one-, two- or three-dimensional
* Corresponding author. Fax: +86-20-8411 2245.
E-mail address: cescxm@zsu.edu.cn (X.-M. Chen).
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00791-5

14
H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
layer networks, namely [M(SCN)2(4-abaH)2]n [M=
Co(II) (1) or Cd(II) (2)], assembled simultaneously by
covalent bonds and hydrogen-bonded carboxylic
dimers as the supramolecular synthons [10a,b,g], as well
as two new polymeric covalent networks [ZnN3(4-aba)]n
(3) and [CdN3(4-aba)(H2O)]n (4) featuring mixed bridg-
ing azide and carboxylate groups.
4-abaH (1.00 mmol). After mixing for 5 min, an
aqueous solution (2 cm3) of NaN3 (1.02 mmol) was
slowly added and the pH of the reaction mixture was
adjusted to approximately 7. The resulting mixture was
stirred for 10 min at r.t. and was then allowed to
evaporate at r.t. Colourless crystals of 3 suitable for
X-ray diffraction were deposited in a week (56% yield).
Calc. for C7H6N4O2Zn: C, 34.52, H, 2.48, N, 23.01.
Found: C, 34.48, H, 2.50, N, 23.04%. IR data (cm−1):
3373w, 3327m, 3261m, 3160w, 2093vs, 1607vs, 1550vs,
1399vs, 1300m, 1227w, 1176w, 1060s, 851m, 783m,
695m, 627m, 566w, 518w.
2. Experimental
2.1. Materials and instrumentation
2.2.4. [CdN3(4-aba)(H2O)]n (4)
All the reagents were commercially available and
used as received. The C, H, N microanalyses were
carried out with a Perkin–Elmer 240 elemental analy-
ser. The IR spectra were recorded from KBr pellets in
the range 4000–400 cm−1 on a Nicolet Impact 420
FT-IR spectrometer.
Caution! Metal azide complexes are potentially explo-
sive. Only a small amount of material should be pre-
pared and should be handled with caution.
Complex 4 was prepared in the same way as for 3
using Cd(NO3)2·4H2O instead of Zn(NO3)2·6H2O. Pale
yellow crystals of 4 suitable for X-ray diffraction were
obtained in a week (66% yield). Calc. for C7H8CdN4O3:
C, 27.25, H, 2.61, N, 18.16. Found: C, 27.38, H, 2.59,
N, 18.17%. IR data (cm−1): 3385m, 3271m, 3159m,
2063vs, 1612vs, 1529vs, 1503vs, 1385s, 1253m, 1294m,
1289s, 1182m, 1143w, 1037s, 856m, 783m, 699m, 636m,
575w, 513w.
2.2. Synthesis
2.3. Crystallography
2.2.1. [Co(SCN)2(4-abaH)2]n (1)
The collections of crystallographic data for the four
complexes were carried out on a Siemens R3m diffrac-
tometer using graphite-monochromated Mo Ka (u
A hot aqueous solution (10 cm3) of Co(NO3)2·6H2O
(1.06 mmol) and NH4SCN (2.03 mmol) was added
slowly to a hot ethanol solution (10 cm3) of 4-abaH
(1.02 mmol). After vigorous stirring, the pH of the
resulting solution was adjusted to 4.5 by addition of
dilute HNO3 solution. The mixture was then allowed to
evaporate at room temperature (r.t.). Violet crystals of
1 suitable for X-ray diffraction were deposited in a
week (78% yield). Calc. for C16H14CoN4O4S2: C, 42.76,
H, 3.14, N, 12.47, S, 14.27. Found: C, 42.69, H, 3.21,
N, 12.49, S, 14.28%. IR data (cm−1): 3355m, 3274m,
3071w, 2981w, 2116vs, 1681vs, 1606vs, 1514w, 1418m,
1317s, 1289s, 1247s, 1178m, 1010w, 929s, 835m, 691w,
615m, 551m, 506w.
,
0.71073 A) radiation at 293(2) K; the determinations of
the crystal class, orientation matrix, and cell dimensions
were performed according to the established proce-
dures. The intensity data were collected using the ꢀ-
scan mode. Absorption corrections were applied by
fitting a pseudoellipsoid to the „-scan data of selected
strong reflections over a range of 2q angles [13]. The
structure solutions and full-matrix least-squares refine-
ments based on F2 were performed with the SHELXS-97
and SHELXL-97 program packages, respectively [14,15].
All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms of organic ligands were generated
,
geometrically (CꢀH 0.96 A); all the hydrogen atoms
2.2.2. [Cd(SCN)2(4-abaH)2]n (2)
were assigned isotropic thermal parameters and in-
cluded in the structure–factor calculations. Analytical
expression of neutral-atom scattering factors was em-
ployed and anomalous dispersion corrections incorpo-
rated [16]. Drawings were produced with SHELXTL [17].
The crystal data are given in Table 1, and the selected
bond distances and bond angles are listed in Table 2.
Complex 2 was prepared in the same way as for 1
using Cd(NO3)2·4H2O in place of Co(NO3)2·6H2O, and
the resulting clear solution was then allowed to evapo-
rate at r.t. Pale yellow crystals of 2 suitable for X-ray
diffraction were deposited in a week (75% yield). Calc.
for C16H14CdN4O4S2: C, 38.22, H, 2.81, N, 11.14, S,
12.75. Found: C, 38.26, H, 2.79, N, 11.19, S, 12.71%.
IR data (cm−1): 3353m, 3273m, 3072w, 2979w, 2116vs,
1680vs, 1606vs, 1513w, 1419m, 1317s, 1289s, 1248s,
1177m, 1013w, 928s, 836m, 692w, 616m, 552m, 506w.
3. Results and discussion
3.1. Structural descriptions
2.2.3. [ZnN3(4-aba)]n (3)
An aqueous solution (5 cm3) of Zn(NO3)2·6H2O (1.00
mmol) was added to an ethanol solution (8 cm3) of
3.1.1. [Co(SCN)2(4-abaH)2]n (1)
A fragment of the crystal structure of 1 is shown in

H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
15
3.1.2. [Cd(SCN)2(4-abaH)2]n (2)
Fig. 1. The structure of 1 consist of [M(SCN)2]n chains
running along the a-axis. The Co(II) atom, being lo-
cated at an inversion centre, is hexa-coordinated in a
trans fashion by a pair of sulphur atoms from two
The coordination geometry and three-dimensional
structure of 2 are very similar to those of 1, as shown in
Figs. 2 and 3. Due to the larger ionic radius of Cd(II)
as compared to that of Co(II), the metal–ligand bonds
in 2 are significantly longer than the corresponding
ones in 1. Different from that of 1, the inversion centre
is located between the Cd(II) atoms rather than on the
Cd(II) atoms. Consequently, the lengths of each pair of
the trans-related metal–ligand bonds are slightly differ-
ent as compared in Table 2. The non-bonded Cd···Cd
separations are also different with Cd(1)···Cd(1a) and
Cd(1)···Cd(1b) at 5.822(1) and 5.961(1) A, respectively.
Similar to those of 1, the hydrogen-bonded dicarboxylic
supramolecular synthons [O···O, 2.664(6) A; OꢀH···O,
172.4(4)°] extend the chains into infinite two-dimen-
sional networks (with the 18.1×5.8 A internal dimen-
sions) in the solid of 2.
SCN− groups [Co(1)ꢀS(1) 2.552(1) A], a pair of nitro-
,
gen atoms from another two SCN− groups
,
[Co(1)ꢀN(1a) 2.035(2) A], and a pair of nitrogen atoms
,
from two 4-abaH ligands [Co(1)ꢀN(2) 2.206(2) A] in an
octahedral geometry with the most distorted bond an-
gle being 92.6(1)°. Each pair of adjacent metal atoms
are alternately bridged by a pair of SCN− groups
through both ends, resulting in a chain-like structure
with eight-membered (ꢀNꢀCꢀSꢀM)2 rings in a chair
conformation. As expected, each pair of the carboxylic
groups from adjacent chains form a pair of hydrogen
bonds with each other to generate a hydrogen-bonded
,
,
,
,
layer with 17.9×5.7 A internal dimensions, as shown
in Fig. 2. The doubly hydrogen-bonded carboxylic
groups may be regarded as the supramolecular syn-
thons which have a graph set [18,19] of R22(8) [O···O,
3.1.3. [ZnN3(4-aba)]n (3)
The crystal structure of 3 is different from those of 1
and 2, featuring covalent bridges of the deprotonated
4-aba groups which interconnect the polymeric [ZnN3]n
chains. In 3, the Zn(II) atom is penta-coordinated in a
distorted trigonal-bipyramidal environment with two
,
2.635(3) A; OꢀH···O, 156.5(4)°]. Similar supramolecular
synthons of doubly hydrogen-bonded carboxylic groups
have been documented in
a few previous work
[10a,b,g]. There is no significant aryl–aryl interac-
tions between neighbouring layers in 1, similar to
those reported previously [10a,b]. On the other
hand, each 4-aba amine group donates a weak hydro-
gen bond to the thiocyanate sulphur atoms (N···S
,
carboxylic oxygen atoms (ZnꢀO 2.042(2), 2.089(2) A)
from two deprotonated 4-aba groups at the apical
positions and three nitrogen atoms (ZnꢀN 2.063(2)–
,
2.112(2) A) from two azide groups and one from a
,
3.604(3) A), and these hydrogen bonds extend the
4-aba group at the equatorial plane (Fig. 4(a)). The
adjacent Zn(II) atoms are interconnected through m-
1,1-bound-azide groups (ZnꢀNꢀZn 118.0(1)°) and m2-
two-dimensional layers into the three-dimensional
solid-state structure.
Table 1
Crystal data and structure refinement parameters for complexes 1–4
Complexes
1
2
3
4
Empirical formula
Formula weight
Crystal system
Space group
C
449.36
triclinic
P1
16H14CoN4O4S2
C16H14CdN4O4S2
502.83
triclinic
C7H6N4O2Zn
243.54
monoclinic
P21/c
C7H8CdN4O3
308.57
monoclinic
P21/n
(
(
P1
Unit cell dimensions
,
a (A)
5.653(3)
6.273(4)
12.932(9)
82.630(3)
89.300(4)
86.100(1)
453.7(5)
1
6.389(3)
11.698(7)
12.758(8)
88.790(4)
84.710(6)
87.030(1)
948.0(9)
2
9.279(2)
6.281(1)
14.343(3)
90
93.53(3)
90
834.3(3)
4
1.939
6.541(2)
20.180(9)
7.204(2)
90
97.18(2)
90
943.5(6)
4
2.172
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Dc (g cm−3
)
1.645
1.207
229
1.761
1.402
500
v (Mo Ka) (mm−1
F(000)
)
2.919
488
2.307
600
q range (°)
3.2–29.0
1.052
0.0428, 0.1109
0.0518, 0.1170
2.4–26.0
1.051
0.0472, 0.1071
0.0725, 0.1176
4.1–30.0
1.035
0.0457, 0.1273
0.0518, 0.1325
3.0–28.0
1.039
0.0251, 0.0705
0.0283, 0.0722
Goodness-of-fit on F2
R1, wR2 [I\2|(I)] a
R1, wR2 (all data) a
a R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ, wR2=[ꢀw(ꢁFoꢁ−ꢁFcꢁ)2/ꢀwꢁFoꢁ2]1/2, w=[|2(Fo)2+(0.1(max(0,Fo2)+2Fc2)/3)2]−1
.

16
H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
Table 2
exhibits a tridentate (m3-N,O,O%) coordination mode to
,
Selected bond lengths (A) and bond angles (°) for complexes 1–4
,
bridge three metal centres (Zn···Zn 3.5×9.3 A) and
extends the chains into a two-dimensional network, as
illustrated in Fig. 4(b).
Complex 1
Co(1)ꢀN(1a)
Co(1)ꢀN(2)
2.035(2)
2.206(2)
Co(1)ꢀS(1)
2.552(1)
3.1.4. [CdN3(4-aba)(H2O)]n (4)
N(1a)ꢀCo(1)ꢀN(2)
N(1b)ꢀCo(1)ꢀN(2)
N(1a)ꢀCo(1)ꢀS(1)
N(1b)ꢀCo(1)ꢀS(1)
N(2)ꢀCo(1)ꢀS(1)
87.5(1)
92.5(1)
87.9(1)
92.1(1)
92.7(1)
N(1)ꢀC(1)ꢀS(1)
C(6)ꢀN(2)ꢀCo(1)
C(1)ꢀS(1)ꢀCo(1)
179.6(2)
121.6(2)
102.0(1)
Similar to that of 3, the crystal structure of 4 is also
constructed from covalent bridges of the deprotonated
4-aba groups which interconnect the polymeric [CdN3]n
chains. In 4, each Cd(II) atom is coordinated in a
distorted octahedral environment by three azide nitro-
C(1)ꢀN(1)ꢀCo(1a) 165.8(2)
O(1)···O(2c)
2.635(3)
O(1)ꢀH(1)···O(2c)
156.5(4)
,
gen atoms (CdꢀN 2.404(3)–2.474(3) A), one aqua lig-
Complex 2
Cd(1)ꢀN(4a)
Cd(1)ꢀN(3b)
Cd(1)ꢀN(1)
2.278(5)
2.305(4)
2.440(5)
Cd(1)ꢀN(2)
Cd(1)ꢀS(1)
Cd(1)ꢀS(2)
2.448(5)
2.682(4)
2.693(4)
,
and (CdꢀO 2.270(3) A), one carboxy oxygen atom
,
(CdꢀO 2.271(3) A) of a 4-aba ligand, and one amine
nitrogen atom (CdꢀN 2.368(3) A) of another 4-aba
,
N(4a)ꢀCd(1)ꢀN(3b) 177.5(2)
N(3b)ꢀCd(1)ꢀS(2)
N(1)ꢀCd(1)ꢀS(2)
N(1)ꢀCd(1)ꢀN(2)
N(1)ꢀCd(1)ꢀS(1)
N(2)ꢀCd(1)ꢀS(1)
N(2)ꢀCd(1)ꢀS(2)
S(1)ꢀCd(1)ꢀS(2)
85.9(1)
94.0(1)
174.2(1)
85.6(1)
92.9(1)
87.3(1)
177.8(1)
ligand (Fig. 5(a)). The bond lengths and bond angles at
the metal centre are typical for azide and 4-aba coordi-
nation. Each azide ligand acts in a m-1,1,3-briding mode
to link three Cd(II) atoms, generating an infinite one-
dimensional staircase-like chain, which is constructed
by alternate interconnection of four-membered Cd2(m-
1,1-N3)2 and eight-membered Cd2(m-1,3-N3)2 rings (Fig.
5(b)) with the intra-ring Cd···Cd distances of 3.892(1)
N(4a)ꢀCd(1)ꢀN(1)
N(4a)ꢀCd(1)ꢀS(1)
N(4a)ꢀCd(1)ꢀN(2)
N(4a)ꢀCd(1)ꢀS(2)
N(3b)ꢀCd(1)ꢀN(1)
N(3b)ꢀCd(1)ꢀN(2)
N(3b)ꢀCd(1)ꢀS(1)
94.3(2)
90.4(1)
91.3(2)
91.8(1)
86.5(2)
87.9(2)
91.9(1)
O(3)···O(1d)
O(2)···O(4c)
2.629(6)
2.664(6)
O(3)ꢀH(3)···O(1d)
O(2)ꢀH(4b)···O(4c) 172.4(4)
167.6(7)
,
and 5.073(1) A, respectively. As the carboxylate group
Complex 3
Zn(1)ꢀO(1)
Zn(1)ꢀN(2)
Zn(1)ꢀN(1b)
Zn(1)ꢀO(2a)
of the 4-aba ligand acting in a monodentate mode, both
ends of the organic ligand participates in the coordina-
tion to the metal atoms in a m2-N,O mode, the azido-
bridged chains are further interlinked through the
organic spacers into a new three-dimensional, irregular
brickwall-like network (see Fig. 6).
2.089(2)
2.064(3)
2.112(2)
2.042(2)
Zn(1)ꢀN(2a)
N(2)ꢀN(3)
N(3)ꢀN(4)
2.063(2)
1.213(3)
1.140(4)
O(2a)ꢀZn(1)ꢀO(1)
O(2a)ꢀZn(1)ꢀN(2a)
O(2a)ꢀZn(1)ꢀN(2)
O(2a)ꢀZn(1)ꢀN(1b)
N(2a)ꢀZn(1)ꢀN(2)
N(2a)ꢀZn(1)ꢀN(1b) 113.7(1)
N(2a)ꢀZn(1)ꢀO(1)
175.7(1)
87.0(1)
88.0(1)
91.4(1)
129.4(1)
N(2)ꢀZn(1)ꢀO(1)
94.7(1)
N(2)ꢀZn(1)ꢀN(1b) 116.8(1)
O(1)ꢀZn(1)ꢀN(1b) 90.4(1)
Zn(1c)ꢀN(2)ꢀZn(1) 118.0(1)
N(4)ꢀN(3)ꢀN(2)
N(3)ꢀN(2)ꢀZn(1)
3.2. Discussions
177.9(4)
120.1(2)
A few one-dimensional polymers of cadmium thio-
cyanates [Cd(SCN)2L2]n (L=benzylamine, dibenzy-
lamine, tri-m-tolyphosphine or 1H-1,2,4-triazole) have
been reported in the past decades [20]. All of these
complexes exhibit chain structures, where each pair of
adjacent Cd(II) atoms are bridged by two inversely
related m2-SCN-N,S ligands and the remaining coordi-
nation sites are occupied by the monodentate organic
ligands. We have recently found that imidazole and
nicotinic derivatives can extend the [Cd(SCN)2]n chains
into two-dimensional networks through hydrogen
bonding [10g,12]. Therefore, we may conclude that the
[M(m2-SCN-N,S)2]n chain structure is quite stable and
introduction of organic ligands capable of both proton
donation and acceptance may extend the chains into
higher dimensional structures, as demonstrated by 1
and 2. An acidic reaction solution is essential for the
formation of the hydrogen-bonded carboxylic dimer.
This conclusion is also supported by the fact that
hydrogen-bonded carboxylic dimers do not formed at
higher pH (ca. 7); instead, the carboxylic groups are
deprotonated and participate in coordination to the
metal atoms, as shown in both 3 and 4. On the other
88.7(1)
Complex 4
Cd(1)ꢀN(1)
Cd(1)ꢀN(2)
Cd(1)ꢀN(2c)
Cd(1)ꢀN(4b)
2.368(3)
2.474(3)
2.469(3)
2.404(3)
Cd(1)ꢀO(2a)
Cd(1)ꢀO(1w)
N(3)ꢀN(2)
2.271(3)
2.270(3)
1.191(4)
1.158(4)
N(3)ꢀN(4)
O(1w)ꢀCd(1)ꢀN(1)
O(1w)ꢀCd(1)ꢀN(2)
O(1w)ꢀCd(1)ꢀN(2c)
O(1w)ꢀCd(1)ꢀN(4b)
O(1w)ꢀCd(1)ꢀO(2a)
102.5(1)
165.6(1)
89.5(1)
83.4(1)
92.5(1)
N(1)ꢀCd(1)ꢀN(2)
N(1)ꢀCd(1)ꢀN(4b)
N(1)ꢀCd(1)ꢀN(2c)
N(4b)ꢀCd(1)ꢀN(2c) 158.3(1)
N(4b)ꢀCd(1)ꢀN(2) 110.3(1)
N(2c)ꢀCd(1)ꢀN(2)
Cd(1c)ꢀN(2)ꢀCd(1) 103.9(1)
76.6(1)
79.7(1)
81.9(1)
O(2a)ꢀCd(1)ꢀN(4b) 117.7(1)
76.1(1)
O(2a)ꢀCd(1)ꢀN(2)
O(2a)ꢀCd(1)ꢀN(1)
O(2a)ꢀCd(1)ꢀN(2c)
85.2(1)
158.7(1)
83.0(1)
N(3)ꢀN(2)ꢀCd(1)
N(4)ꢀN(3)ꢀN(2)
121.8(2)
179.4(3)
Symmetry codes for: 1 (a) −x, −y, −z; (b) −x−1, −y, −z; (c)
−x−2, −y−1, −z+1. 2 (a) −x, −y, −z+1; (b) −x, −y+1,
−z+1; (c) x−1, y−1, z+1; (d) x+1, y+1, z−1. 3 (a) −x+2,
y+1/2, −z+1/2; (b) x−1, y, z. 4 (a) −x, −y+2, −z+1; (b)
−x+1, −y+2, −z+1; (c) −x+1/2, y+1/2, −z+3/2.
carboxylate-O,O% groups in a trans fashion to generate
an infinite zigzag chain with the (ZnꢀNꢀZnꢀOꢀCꢀOꢀ)n
six-membered rings. Each deprotonated 4-aba group

H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
17
Fig. 1. Perspective view of the one-dimensional chains showing the coordination environment in 1.
Fig. 2. Perspective views of the layer formed by the hydrogen-bonded [M(SCN)2(4-abaH)2]n chains in 1 or 2.
Fig. 3. Perspective view of the one-dimensional chains showing the coordination environment in 2.

18
H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
Fig. 4. Perspective views of the coordination environment of the Zn(II) atom (a) and the two-dimensional framework (b) in [ZnN3(4-aba)]n (3).
hand, our attempt to assemble the M(SCN)2 with 4-aba
through covalent bonds and manganese(II)/nickel(II)
thiocyanates with 4-aba through supramolecular syn-
thon did not success.
as the study of ferro- or antiferromagnetic materials
[23]. In contrast, the m-1,1,3-bound mode, as well as the
accompanying infinite one-dimensional staircase-like
chain [MN3]n found in 4 has not been documented in
the literature. The IR spectrum of 3 shows a sharp
band at 2093(vs) cm−1, which agrees with the m-1,1-
azide group [23a–c]. However, the IR spectrum of 4
shows a sharp band at 2063 cm−1, which is located
between 2056 cm−1 for m-1,3-azide and 2094 cm−1 for
m-1,1-azide [23d]. This absorption should be ascribed to
the occurrence of m-1,1,3-azide group. A few two-di-
mensional brickwall-like sheets (Scheme 2) or their
triple interpenetrating sheets have been reported, in
which the metal centres are T-shaped [3b,24]. In order
to extent the two-dimensional brickwall-like sheets into
a three-dimensional brickwall network, a neutral biden-
tate ligand must be introduced and the metal atoms
should exhibit a penta-coordination fashion. At neutral
It has been found that SCN− group can exhibit two
types of terminal coordination modes, S-coordinated
and N-coordinated, as well as 13 bridging modes with
the metal ions [21]. The m2-SCN-N,S coordination
mode for Cd(II) atoms is one of the usual fashion since
Cd(II) atom is between hard base and soft base accord-
ing to the hard–soft acid–base concept [22]. On the
other hand, such m2-SCN-N,S coordination mode for
the Co(II) atoms in 1 is less common [22], since Co(II)
ion is a hard acid and expected to exhibit N-
coordination.
Azide group is a versatile bridging ligand in coordi-
nation to transition metal centres in the m-1,3 or m-1,1
fashions (Scheme 1), which has been widely investigated

H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
19
Fig. 5. Perspective views of the coordination environment of the Cd(II) atom (a) and staircase-like chain constructed by m-1,1,3-azide ligands with
Cd(II) atoms (b) in [CdN3(4-aba)(H2O)]n (4).
Fig. 6. Perspective view of the brickwall-like three-dimensional framework of 4. The aqua ligands are omitted for clarity.
condition, the polymeric [CdN3]n chains are intercon-
nected by the deprotonated 4-aba spacers to produce a
three-dimensional brickwall network (Scheme 2). At-
tempt to assemble the M(N3)2 with 4-abaH through
Scheme 2. Schematic diagram of the three-dimensional brickwall
network.
Scheme 1.

20
H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
[4] M. Fujita, Y.J. Kwon, O. Sasaki, K. Yamaguchi, K. Ogura, J.
Am. Chem. Soc. 117 (1995) 7287.
[5] (a) B.F. Hoskins, R. Robson, D.A. Slizys, J. Am. Chem. Soc.
119 (1997) 2952;
hydrogen bonds did not success as NaN3 decomposes
in an acidic solution.
(b) B.F. Hoskins, R. Robson, D.A. Slizys, Angew. Chem., Int.
Ed. Engl. 36 (1997) 2336.
4. Supplementary material
[6] (a) M.A. Withersby, A.J. Blake, N.R. Champness, P. Hubber-
stey, W.-S. Li, M. Schro¨der, Angew. Chem. 109 (1997) 2421;
(b) M.A. Withersby, A.J. Blake, N.R. Champness, P. Hubber-
stey, W.-S. Li, M. Schro¨der, Angew. Chem., Int. Ed. Engl. 36
(1997) 2327.
[7] A.J. Blake, N.R. Champness, A. Khlobystov, D.A. Lemenovskii,
W.-S. Li, M. Schro¨der, Chem. Commun. (1997) 2027.
[8] L. Carlucci, G. Ciani, D.M.V. Gudenberg, D.M. Proserpio, A.
Sironi, Inorg. Chem. 36 (1997) 3812.
[9] (a) T.L. Hennigar, D.C. MacQuarie, P. Losier, R.D. Rogers,
M.J. Zaworotko, Angew. Chem. 109 (1997) 1044;
(b) T.L. Hennigar, D.C. MacQuarie, P. Losier, R.D. Rogers,
M.J. Zaworotko, Angew. Chem., Int. Ed. Engl. 36 (1997) 972;
(c) M. Fujita, Y.J. Kwon, M. Miyazawa, K. Ogura, J. Chem.
Soc., Chem. Commun. (1994) 1977.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 156833–156836 for com-
pounds 1–4. Copies of this information may be ob-
tained free of charge from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ, UK (fax: +44-
1223-336-033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
[10] (a) C.B. Aakero¨y, A.M. Beatty, D.S. Leinen, K.R. Lorimer,
Chem. Commun. (2000) 935;
This work was supported by the National Natural
Science Foundation of China (No. 29971033) and
Foundation for University Key Teachers by the Min-
istry of Education of China. We thank the Chemistry
Department of the Chinese University of Hong Kong
for donation of the diffractometer.
(b) C.B. Aakero¨y, A.M. Beatty, K.R. Lorimer, J. Chem. Soc.,
Dalton Trans. (2000) 3869;
(c) O.M. Yaghi, H. Li, T.L. Groy, J. Am. Chem. Soc. 118 (1996)
9096;
(d) C.B. Aakero¨y, A.M. Beatty, D.S. Leinen, Angew. Chem.,
Int. Ed. Engl. 38 (1999) 1815;
(e) C.B. Aakero¨y, A.M. Beatty, B.A. Helfrich, J. Chem. Soc.,
Dalton Trans. (1998) 1943;
(f) A.D. Burrows, D.M.P. Mingos, A.J.P. White, D.J. Williams,
Chem. Commun. (1996) 97;
References
(g) G. Yang, H.-G. Zhu, B.-H. Liang, X.-M. Chen, J. Chem.
Soc., Dalton Trans. (2001) 580.
[11] (a) H.-J. Chen, L.-Z. Zhang, Z.-G. Cai, G. Yang, X.-M. Chen,
J. Chem. Soc., Dalton Trans. (2000) 2463;
[1] (a) B.F. Hoskins, R. Robson, J. Am. Chem. Soc. 112 (1990)
1564;
(b) A. Stein, S.W. Keller, T.E. Mallouk, Science 259 (1993) 1558;
(c) M. Fujita, Y.J. Kwon, S. Washizu, K. Ogurs, J. Am. Chem.
Soc. 116 (1994) 1151;
(d) S.R. Batten, R. Robson, Angew. Chem., Int. Ed. Engl. 37
(1998) 1460;
(b) M.-L. Tong, H.-J. Chen, X.-M. Chen, Inorg. Chem. 39
(2000) 2235;
(c) H.-J. Chen, X.-M. Chen, D.-Y. Zhou, Y.-C. Zhou, Supramol.
Chem. (2002), in press;
(d) H.-J. Chen, G. Yang, X.-M. Chen, Acta Crystallogr., Sect. C
55 (1999) 2012.
(e) O.M. Yaghi, G. Li, Angew. Chem., Int. Ed. Engl. 34 (1995)
207;
(f) G.R. Desiraju, Angew. Chem., Int. Ed. Engl. 34 (1995) 2311;
(g) O.M. Yaghi, J. Li, J. Am. Chem. Soc. 117 (1995) 10401;
(h) O.M. Yaghi, H. Li, J. Am. Chem. Soc. 118 (1996) 295;
(i) P.J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem., Int.
Ed. Engl. 38 (1999) 2638.
[12] X.-Y. Huang, Q. Ye, Q.-J. Meng, X.-Z. You, Acta Crystallogr.,
Sect. C 51 (1995) 2285.
[13] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr.,
Sect. A 24 (1968) 351.
[14] G.M. Sheldrick, SHELXS-97, Program for X-ray Crystal Struc-
ture Determination, Go¨ttingen University, Go¨ttingen, Germany,
1997.
[15] G.M. Sheldrick, SHELXL-97, Program for X-ray Crystal Struc-
ture Refinement, Go¨ttingen University, Go¨ttingen, Germany,
1997.
[16] International Tables for Crystallography, Kluwer, Dordrecht,
Vol. C, Tables 4.2.6.8 and 6.1.1.4, 1992.
[17] G.M. Sheldrick, SHELXTL, Version V, Siemens Analytical X-ray
Instrument Inc., Madison, WI, USA, 1998.
[18] J. Bernstein, R.E. Davis, L. Shimoni, N.-L. Chang, Angew.
Chem., Int. Ed. Engl. 34 (1995) 1555.
[19] G.R. Desiraju, Angew. Chem., Int. Ed. Engl. 34 (1995) 2311.
[20] (a) M. Taniguchi, M. Shimoi, A. Ouchi, Bull. Chem. Soc. Jpn.
59 (1986) 2299;
[2] (a) L.R. MacGillivray, S. Subramamian, M.J. Zaworotko, J.
Chem. Soc., Chem. Commun. (1994) 1325;
(b) M.-L. Tong, X.-L. Yu, X.-M. Chen, J. Chem. Soc., Dalton
Trans. (1998) 5;
(c) L. Carlucci, G. Ciani, D.M. Proserpio, A. Sironi, Inorg.
Chem. 34 (1995) 5698;
(d) L. Carlucci, G. Ciani, D.M. Proserpio, A. Sironi, Angew.
Chem., Int. Ed. Engl. 34 (1995) 1895.
[3] (a) O.M. Yaghi, H. Li, T.L. Groy, Inorg. Chem. 36 (1997) 4292;
(b) F. Robinson, M.J. Zaworotko, J. Chem. Soc., Chem. Com-
mun. (1995) 2413;
(c) M. Fujita, Y.J. Kwon, S. Washizu, K. Ogura, J. Am. Chem.
Soc. 116 (1994) 1151;
(d) M.-L. Tong, B.-H. Ye, J.-W. Cai, X.-M. Chen, Inorg. Chem.
37 (1998) 2645;
(b) M. Taniguchi, A. Ouchi, Bull. Chem. Soc. Jpn. 60 (1987)
4172;
(c) M. Taniguchi, A. Ouchi, Bull. Chem. Soc. Jpn. 60 (1987)
1192;
(e) M.-L. Tong, H.-K. Lee, X.-M. Chen, R.-B. Huang, T.C.W.
Mak, J. Chem. Soc., Dalton Trans. (1999) 3657;
(f) A.S. Batsanov, M.J. Begley, P. Hubberstey, J. Stroud, J.
Chem. Soc., Dalton Trans. (1996) 1947.

H.-J. Chen, X.-M. Chen / Inorganica Chimica Acta 329 (2002) 13–21
21
(d) R.G. Goel, W.P. Henry, M.J. Olivier, A.L. Beauchamp,
Inorg. Chem. 20 (1981) 3924;
[23] (a) J.L. Manson, A.M. Arlf, J.S. Miller, Chem. Commun. (1999)
1479;
(e) J.G. Haasnoot, G.C.M. de Keyzer, G.C. Verschoor, Acta
Crystallogr., Sect. C 39 (1983) 1207.
(b) X. Hao, Y. Wei, S.-W. Zhang, Chem. Commun. (2000)
2271;
[21] H. Zhang, X.-M. Wang, K.-C. Zhong, B.K. Teo, Coord. Chem.
Rev. 183 (1999) 157.
(c) J. Ribas, M. Monfort, B.K. Ghosh, X. Solans, Angew.
Chem., Int. Ed. Engl. (1994) 2087;
[22] (a) R.G. Pearson, J. Am. Chem. Soc. 85 (1963) 3533;
(b) R.G. Pearson, Adv. Inorg. Chem. Radiochem. 8 (1966) 177;
(c) F. Basolo, Coord. Chem. Rev. 3 (1968) 213;
(d) J.L. Burmeister, Chem. Rev. 3 (1968) 225.
(d) Z. Shen, J.-L. Zuo, S. Gao, Y. Song, C.-M. Che, H.-K. Fun,
X.-Z. You, Angew. Chem., Int. Ed. Engl. 39 (2000) 3633.
[24] F. Robinson, M.J. Zaworotko, J. Chem. Soc., Chem. Commun.
(1995) 2413.