Ladders, rings and cubes as structural motifs in three new zinc(II) azide complexes: Synthesis, spectral and structural characterization

Article abstract of DOI:10.1016/j.poly.2008.01.007

Three new zinc(II) azide complexes, namely {[Zn₂(N₃)₄(py-tetrazole)₂](py-tetrazole)}_n (1), {[Zn₂(N₃)₄(3-OHpy)] · 2H₂O}_n (2) and [Zn(N₃)₂(pym)]_n (3), where py-tetrazole = tetrazolo[1,5-a]pyridine, 3-OHpy = 3-hydroxypyridine and pym = pyrimidine, have been synthesized by the hydrothermal methods and structurally characterized. The ligand py-tetrazole was obtained through the interaction of 2-chloropyridine with the azide ion under hydrothermal condition. The structure of 1 consists of a ladder-like arrangement of 1D double chain zinc(II) azide. In the coordination chain, each zinc atom binds di-EO azide bridges connecting another zinc atom in opposite chain, and two EO bridges, one on each side, and the fifth position is occupied by a N atom of py-tetrazole ligand. The structure of 2 features 2D sheets composed of tetranuclear zinc(II) ring and octanuclear zinc(II) ring interconnected by EO azide bridges. The 2D carrying into 3D supramolecular network by the help of several hydrogen bonding interactions. The 3-OHpy molecule acts in the tautomeric keto-form as O,O-bidentate bridging ligand. Complex 3 features distorted octahedral geometry around each zinc center, N,N′-bidentate pyrimidine ligand and EE azido bridges leading to 3D network structure. The IR spectra are measured and discussed. Complex 2 only exhibits photoluminescence properties whereas the other two complexes do not luminesce at room temperature.

Full text of DOI:10.1016/j.poly.2008.01.007

Available online at www.sciencedirect.com
Polyhedron 27 (2008) 1423–1431
www.elsevier.com/locate/poly
Ladders, rings and cubes as structural motifs in three new zinc(II)
azide complexes: Synthesis, spectral and structural characterization
a
b
b
b
Mohamed A.S. Goher , Beate Sodin , Brigitte Bitschnau , Elmar C. Fuchs ,
b,
*
Franz A. Mautner
a
Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, 21321 Alexandria, Egypt
b
Institut f u¨ r Physikalische und Theoretische Chemie, Technische Universit a¨ t Graz, A-8010 Graz, Austria
Received 24 November 2007; accepted 11 January 2008
Available online 4 March 2008
Abstract
Three new zinc(II) azide complexes, namely {[Zn
2
(N
3
)
4
(py-tetrazole)
2
](py-tetrazole)}
n
(1), {[Zn
2
(N
3
)
4
(3-OHpy)] ꢀ 2H
2 n
O} (2) and
[
Zn(N ) (pym)] (3), where py-tetrazole = tetrazolo[1,5-a]pyridine, 3-OHpy = 3-hydroxypyridine and pym = pyrimidine, have been syn-
3
2
n
thesized by the hydrothermal methods and structurally characterized. The ligand py-tetrazole was obtained through the interaction of 2-
chloropyridine with the azide ion under hydrothermal condition. The structure of 1 consists of a ladder-like arrangement of 1D double
chain zinc(II) azide. In the coordination chain, each zinc atom binds di-EO azide bridges connecting another zinc atom in opposite chain,
and two EO bridges, one on each side, and the fifth position is occupied by a N atom of py-tetrazole ligand. The structure of 2 features
2
3
D sheets composed of tetranuclear zinc(II) ring and octanuclear zinc(II) ring interconnected by EO azide bridges. The 2D carrying into
D supramolecular network by the help of several hydrogen bonding interactions. The 3-OHpy molecule acts in the tautomeric keto-
0
form as O,O-bidentate bridging ligand. Complex 3 features distorted octahedral geometry around each zinc center, N,N -bidentate
pyrimidine ligand and EE azido bridges leading to 3D network structure. The IR spectra are measured and discussed. Complex 2 only
exhibits photoluminescence properties whereas the other two complexes do not luminesce at room temperature.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Azide; Zinc(II); Pyridine derivative complexes; Pyrimidine complexes; Synthesis; Spectra; Crystal structures
1
. Introduction
anions [9], etc., are used to synthesize interesting one-,
two-, or three-dimensional polymers with variable cavities
or channels [4]. Among the anionic ligands, the azide ion
is a versatile ligand and exhibits a variety of bridging abili-
ties including bi-dentate end-on (l-1,1-EO) or end-to-end
(l-1,3-EE) [10–12] bridging fashion, and tri-l-1,1,3 mode
[13] and others [14]. These modes can exist simultaneously
in the same compound affording a variety of nuclearities
and interesting physical properties [10–14]. In this context,
The use of the principles of crystal engineering in the
preparation of supramolecular coordination polymers anal-
ogous to important material such as zeolites has received a
considerable interest during the last decade [1,2]. The crys-
tal engineering of coordination polymers is usually achieved
by using bi-, or multi-dentate ligands to connect the metal
centers. Two types of coordinating ligands: (i) neutral
0
10
organic e.g. pyrazine, 4,4 -bipyridine [3–5], etc., and (ii)
zinc is well suited [15] due to its d configuration which per-
anionic, e.g. azide, thiocyanate [6–8], polyaromatic acid
mits a wide variety of symmetries and coordination num-
bers. Also the photoluminescence of zinc(II) complexes
has received a considerable interest in the last few years
[16,17]. To explore the combination effects of potentially
bi-dentate organic ligands (Scheme 1) and anionic azide
*
Corresponding author. Tel.: +43 316 873 8234; fax: +43 316 873 8225.
E-mail address: mautner@ptc.tu-graz.ac.at (F.A. Mautner).
0
277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.01.007

1424
M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
2. Experimental
2.1. Materials and instrumentation
Elemental analyses were carried out using a Perkin–
Elmer analyzer and infrared spectra were recorded on a Per-
kin–Elmer FTIR Series 1600 spectrophotometer as KBr
pellets [18]. Luminescence spectra were recorded on a Yobin
Yvon SPEX Fluoromax 2 instrument. Starting ligands have
been purchased from Aldrich Company, other chemicals
were of analytical grade quality and used without further
purification. Aqueous hydrazoic acid is obtained with a
Scheme 1.
we synthesized coordination polymers of Zn(II) containing
these ligands. The ligand (L1) in the scheme in fact was pre-
pared through the reaction between 2-chloropyridine and
azide ion, forming tetrazolo[1,5-a]pyridine (abbreviated as
py-tetrazole). This ligand is a potentially multi-dentate
ligand, however, it acts in the synthesized complex
modified Kipp’s generator by decomposition of NaN in
3
H SO /H O (1:3, v:v) and subsequent transfer of HN into
2
4
2
3
[
Zn (N ) (py-tetrazolate) ](py-tetrazole) (1) as a monoden-
H O with aid of an inert gas stream. Stock solutions of
2
2
3 4
2
tate and links zinc center not through the pyridinic nitrogen
but through a nitrogen atom of the other three tetrazole
nitrogens. This complex crystallizes with uncoordinated
py-tetrazole molecule. The second ligand L2 in the scheme:
aqueous ZnN (0.89 mmol Zn/mL H O) are obtained in a
6
2
similar manner by the reaction of HN with a suspension
3
of basic zinc carbonate (0.10 g/mL) H O [19].
2
Caution: Azide compounds and hydrazoic acid (HN3)
are potentially explosive! Only a small amount of material
should be prepared and handled with care.
3
-hydroxypyridine (3-OHpy), behaves as O,O-bridging, i.e.
in the tautomeric keto-form (pyridone) in the prepared zin-
c(II) complex, [Zn (N ) (3-OHpy)] ꢀ 2H O (2) which crys-
2
3 4
2
tallizes with two lattice water molecules. L3 is pyrimidine
2.2. Synthesis
(
pym) which is potentially bidentate and has the ability to
bridge metal centers, afforded [Zn(N ) (pym)] (3). The
2.2.1. {[Zn (N ) (py-tetrazole) ](py-tetrazole)} (1)
2
3
2
3 4
2
n
structural motifs of these complexes are variable from lad-
Complex 1 was prepared by mixing an aqueous solution
der (1D), to rings (2D) and cubes (3D). Complexes 1 and
of ZnN saturated with hydrazoic acid (10 mL, 8.9 mmol
6
2
are unprecedented in all known metal azide complexes.
Zn) with 2-chloropyridine (0.50 g, 4.4 mmol) in MeOH
(10 mL). The mixture was heated to 95 °C for 30 min with
subsequent step-wise cooling to 4 °C. Needle-shaped color-
less crystals of the complex were deposited after approx.12
weeks. Yield: approx. 55%. Anal. Calc. for C H N Zn :
These three new complexes are studied by spectroscopic
methods and X-ray crystal diffraction. The room tempera-
ture photoluminescence of complex 2 is measured. The
results of this study are reported here.
1
5
12 24
2
Table 1
Crystallographic data and processing parameters
Compound
1
2
3
Empirical formula
Formula mass
System
C
15
H
12
N
24Zn
2
C
5
H
9
N
13
O
3
Zn
2
C
229.54
4
H
4 8
N Zn
659.27
monoclinic
P2 /c
12.909(3)
6.740(2)
28.312(9)
90
94.43(2)
90
2456.0(12)
4
430.03
monoclinic
P2 /c
11.635(2)
10.743(2)
11.999(2)
90
104.40(3)
90
1452.7(5)
4
monoclinic
I2/m
7.508(2)
12.083(3)
8.500(3)
90
91.67(2)
90
770.8(4)
4
Space group
1
1
˚
a (A)
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
˚
3
V (A )
Z
T (K)
l (Mo Ka) (mm
293(2)
2.015
1.783
100(2)
3.341
1.966
99(2)
3.148
1.978
ꢁ1
)
3
Dcalc (Mg/m )
Crystal size (mm)
h Range (°)
Reflections collected
Independent reflections (Rint
Parameters
0.35 ꢂ 0.22 ꢂ 0.16
3.11–26.00
5586
4786(0.0328)
370
0.38 ꢂ 0.30 ꢂ 0.20
1.81–25.49
10251
2700(0.1071)
220
0.30 ꢂ 0.20 ꢂ 0.12
2.93–29.99
1494
1178(0.0283)
65
)
2
Goodness-of-fit on F
1.122
1.097
1.255
R
1
/wR
Residual extrema (eA )
2
0.0407/0.0999
0.509, ꢁ0.524
0.0608/0.1433
1.189, ꢁ1.089
0.0361/0.0982
0.499, ꢁ0.668
˚
3

M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
1425
C, 27.3; H, 1.8; N, 51.0. Found: C, 27.1; H, 1.9; N, 50.8%.
Table 2
ꢁ
1
Selected bond lengths ( A˚ ) and angles (°) for 1
IR, KBr (cm ): (v, very; s, strong; m, medium; w, weak;
br, broad): 3134 w, 3107 w, 3086 w, 3037 w, 2118 s, 2098
vs, 1630 m, 1492 m, 1431 w, 1302 w, 1285 m, 1266 w,
Zn(1)–N(41)
Zn(1)–N(21)
Zn(1)–N(1)
Zn(2)–N(41B)
Zn(2)–N(11)
N(11)–N(12)
N(21)–N(22)
N(31)–N(32)
N(41)–N(42)
N(1)–C(5)
2.047(3)
2.085(3)
2.252(3)
2.050(3)
2.120(3)
1.208(4)
1.206(4)
1.226(4)
1.224(4)
1.337(5)
1.297(4)
1.353(5)
1.337(5)
1.297(5)
1.345(5)
1.311(6)
1.337(6)
1.359(7)
Zn(1)–N(31)
Zn(1)–N(11)
Zn(2)–N(31A)
Zn(2)–N(21)
Zn(2)–N(5)
N(12)–N(13)
N(22)–N(23)
N(32)–N(33)
N(42)–N(43)
N(1)–N(2)
2.063(3)
2.087(3)
2.038(3)
2.059(3)
2.253(3)
1.139(4)
1.149(4)
1.131(4)
1.140(4)
1.347(4)
1.358(5)
1.375(5)
1.356(4)
1.367(5)
1.370(5)
1.387(10)
1.398(6)
1.211(9)
3.5929(13)
1
5
139 m, 1093 m, 1021 w, 771 m, 749 m, 691 w, 674 w,
99 w, 556 w, 428 w.
2
.2.2. {[Zn (N ) (3-OHpy)] ꢀ 2H O} (2)
2
3 4
2
n
This complex was prepared by dissolving 3-hydroxypyr-
idine (0.358 g, 3.76 mmol) in an aqueous solution of ZnN6
saturated with hydrazoic acid (10 mL, 8.9 mmol Zn). The
N(2)–N(3)
N(4)–C(5)
N(5)–C(10)
N(6)–N(7)
N(3)–N(4)
N(4)–C(1)
N(5)–N(6)
N(7)–N(8)
clear solution was stored at 4 °C to separate colorless and
transparent crystals of the complex after 7 days. Yield:
approx. 55%. Anal. Calc. for C H N O Zn : C, 14.0; H,
5
9
13
3
2
N(8)–C(10)
N(18)–C(17)
C(17)–N(16)
N(16)–N(20)
Zn(1)ꢀ ꢀ ꢀZn(2)
Zn(1)ꢀ ꢀ ꢀZn(2A)
N(41)–Zn(1)–N(31)
N(31)–Zn(1)–N(21)
N(31)–Zn(1)–N(11)
N(41)–Zn(1)–N(1)
N(21)–Zn(1)–N(1)
N(31A)–Zn(2)–
N(41B)
N(8)–C(6)
2
.1; N, 42.3. Found: C, 14.2; H, 1.9; N, 42.6%. IR, KBr
N(18)–N(19)
C(21)–N(16)
N(20)–N(19)
ꢁ1
(
cm ): 3599 mbr, 3468 br, 3115 w, 2121 vs, 2091 vs,
603 m, 1549 m, 1471 m, 1357 m, 1305 m, 1260 m, 1179
vw, 1109 vw, 1046 vw, 1002 vw, 853 m, 805 m, 697 w,
1
3.2256(11) Zn(1)ꢀ ꢀ ꢀZn(2B)
3.6003(13)
6
74 m, 619 w, 580 w, 525 w.
115.20(12)
132.04(13)
96.60(12)
94.60(11)
86.00(11)
117.56(12)
N(41)–Zn(1)–N(21) 112.70(13)
N(41)–Zn(1)–N(11)
N(21)–Zn(1)–N(11)
N(31)–Zn(1)–N(1)
N(11)–Zn(1)–N(1)
N(31A)–Zn(2)–
N(21)
98.67(12)
78.30(11)
88.04(12)
162.43(12)
112.10(13)
2
.2.3. [Zn(N ) (pym)] (3)
n
3
2
This complex was prepared by mixing an aqueous solu-
tion of ZnN6 saturated with hydrazoic acid (15 mL,
.9 mmol Zn) with pyrimidine (83.9 mg, 1.27 mmol). The
8
mixture was heated to 80 °C to obtain a clear solution. Col-
orless crystals of the complex were deposited after 2 days at
room temperature. Yield: approx. 80%. Anal. Calc. for
C H N Zn: C, 20.9; H, 1.8; N, 48.8. Found: C, 48.5; H,
N(41B)–Zn(2)–N(21) 130.34(13)
N(31A)–Zn(2)–
N(11)
N(21)–Zn(2)–N(11)
N(41B)–Zn(2)–N(5)
N(11)–Zn(2)–N(5)
N(12)–N(11)–Zn(2) 126.4(3)
N(13)–N(12)–N(11) 178.8(4)
N(22)–N(21)–Zn(1) 127.4(3)
N(23)–N(22)–N(21) 178.5(4)
N(32)–N(31)–Zn(1) 116.3(2)
N(33)–N(32)–N(31) 179.7(4)
97.80(12)
N(41B)–Zn(2)–N(11)
N(31A)–Zn(2)–N(5)
N(21)–Zn(2)–N(5)
N(12)–N(11)–Zn(1)
Zn(1)–N(11)–Zn(2)
N(22)–N(21)–Zn(2)
Zn(2)–N(21)–Zn(1)
94.81(12)
94.14(12)
88.14(12)
125.2(3)
100.14(12)
130.1(3)
78.12(12)
88.47(12)
164.42(12)
4
4
8
ꢁ
1
1
3
.7; N, 20.8%. IR, KBr (cm ): 3422 w, 3393 w, 3105 w,
087 w, 2078 vs, 1594 s, 1563 m, 1463 m, 1420 m, 1286
w, 1219 w, 1175 m, 1136 w, 1075 m, 1021w, 957 w, 819
m, 704 s, 685 m, 649 m, 656 s 616 m.
102.23(12)
N(32)–N(31)–Zn(2B) 118.2(3)
Zn(2B)–N(31)–Zn(1) 122.34(14)
2
.3. X-ray crystallography
N(42)–N(41)–Zn(1)
118.6(2)
N(42)–N(41)–
Zn(2A)
117.3(2)
Zn(1)–N(41)–Zn(2A) 122.98(14)
N(43)–N(42)–N(41) 178.3(4)
Single crystal X-ray data for complexes 1 and 3 were
C(5)–N(1)–N(2)
N(2)–N(1)–Zn(1)
N(2)–N(3)–N(4)
N(3)–N(4)–C(1)
C(10)–N(5)–N(6)
N(6)–N(5)–Zn(2)
N(6)–N(7)–N(8)
N(7)–N(8)–C(6)
C(17)–N(18)–N(19)
C(17)–N(16)–N(20)
N(19)–N(20)–N(16)
106.6(3)
114.3(2)
105.2(3)
126.2(4)
106.2(3)
117.0(3)
105.3(3)
126.2(4)
104.7(6)
108.4(5)
106.9(7)
C(5)–N(1)–Zn(1)
N(3)–N(2)–N(1)
C(5)–N(4)–N(3)
N(1)–C(5)–N(4)
C(10)–N(5)–Zn(2)
N(7)–N(6)–N(5)
C(10)–N(8)–N(7)
N(5)–C(10)–N(8)
133.7(3)
111.9(3)
109.6(3)
106.6(3)
128.8(3)
111.8(3)
109.3(3)
107.5(3)
measured on a modified STOE four circle diffractometer,
and for 2 on a Bruker-AXS SMART APEX CCD diffrac-
tometer using graphite crystal-monochromatized Mo Ka;
˚
radiation (k = 0.7107 A). The intensities were corrected
for Lorentz-polarisation effects and for absorption. Crys-
tallographic data and processing parameters are given in
Table 1. The structures were solved by direct methods
and subsequent Fourier analyses. Anisotropic displace-
ment parameters were applied to non-hydrogen atoms in
N(18)–C(17)–N(16) 107.5(5)
N(20)–N(16)–C(21) 129.7(6)
N(20)–N(19)–N(18) 112.5(6)
2
full-matrix least-squares refinements based on F . The
Symmetry codes: (A) ꢁx + 1, y ꢁ 1/2, ꢁz + 1/2. (B) ꢁx + 1, y + 1/2,
z + 1/2.
ꢁ
hydrogen atoms were assigned with isotropic displacement
factors and included in the final refinement cycles by use of
geometrical restraints. Analytical expressions of neutral-
atom scattering factors were employed, and anomalous dis-
persion corrections were incorporated. The programs
DIFABS, SADABS and SHELXTL/PC program package [20] were
used for computations. Selected bond distances and bond
angles are given in Tables 2, 4 and 6, for complexes 1–3,
respectively. Hydrogen bonds of complex 2 are summa-
rized in Table 5.
3. Results and discussion
3.1. Crystal structures
3.1.1. Crystal structure of {[Zn (N ) (py-tetrazole) ](py-
2
3 4
2
tetrazole)} (1)
n
The X-ray structure determination for complex 1
revealed that the five coordinate Zn(II) atoms are bridged

1426
M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
Fig. 1. (a) Perspective view with atom labeling scheme of 1. Symmetry codes according Table 2. (b) Part of the ‘‘ladder-like” arrangement of Zn(II) azide
double chains of 1. (c) Packing view of 1 along the a-axis of unit cell. (d) Packing view of 1 along the b-axis of unit cell.
by four azido bridges in the EO fashion with a ladder-like
arrangement of the 1D zinc(II) azide double chain. A draw-
ing of the asymmetric unit with atom labeling scheme is
shown in Figs. 1a–d, show the ladder-like arrangement of
the double chain propagated along the crystallographic b-
axis, and packing plots of the unit cell. Selected bond
lengths and bond angles are collected in Table 2. In the
coordination chain each zinc(II) ion is coordinated to di-
EO azido bridges [Zn(1)–N(11) = 2.087(3), Zn(1)–
and N(5) and N(11) are the axial atoms. As seen from
Fig. 1c and d, 4 Zn atoms are interlinked through EO
bridging azides giving tetranuclear Zn(II) rings or eight-
membered ring and these rings are connected successively
to form a ladder of 1D double chain along the b-axis.
The Znꢀ ꢀ ꢀZn distances within the four-membered Zn N
2
2
˚
cyclic units are Zn(1)–Zn(2) = 3.2256(11) A, whereas the
Zn–Zn distances within the eight-membered rings Zn N
4
4
˚
are Zn(1)–Zn(2A) = 3.6003(13) A and Zn(1)–Zn(2B) =
˚
˚
N(21) = 2.085(3) A] connecting other Zn(II) ion in the
3.5929(13) A. In the channels between parallel ladders the
opposite chain forming four-membered Zn N cyclic unit
py-tetrazole molecules are located Fig. 1c and d. The four
bridging azido ligands are asymmetric and almost linear
with N–N–N angles from 178.3(4)° to 179.7(4)°, whereas
the N(1)–N(2)–N(3) and N(2)–N(3)–N(4) angles of the
bonded py-tetrazolate molecule are 111.9(3)° and
105.2(3)°, respectively. The four azido groups show pro-
nounced deviations from linearity in the connection with
Zn(II) [Zn–N–N angles from 102.23(12)° to 130.1(3)°].
p–p ring–ring interactions are observed between the five-
and six-membered rings of adjacent bicyclic C H N
4
2
2
˚
[
maximum deviation = 0.075(3) A] crossing the double
chain, and two EO bridging azides each on one side of
the Zn(II) center [Zn(1)–N(31) = 2.063(3), Zn(1)–
˚
N(41). = 2.047(3) A]. The fifth position is occupied by the
˚
nitrogen atom N(1) [Zn(1)–N(1) = 2.252(3) A] of the tetra-
zole ring, leading to the formation of a ZnN chromo-
5
phore. The stereochemistry around Zn(1) center is
intermediate between SP and TBP (s-value = 0.51),
whereas Zn(2) is in a TBP environment (s-value = 0.56)
with N(21), N(31A) and N(41B) in the equatorial positions
5
14
molecules (Table 3).

M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
1427
Table 3
present complex and bridges two Zn(II) atoms, thus behav-
ing as an O,O-bidentate bridging ligand, leading to a 2D
system, further carrying into a 3D supramolecular network
with the help of several hydrogen bonding interactions.
Fig. 2b and c, show the 2D system extented along the b-
and c-axes, and a view of the 2D sheet along the b-axis
of the unit cell. In the coordination chain each Zn(II) cen-
ter links another Zn(II) center through a bridging EO azide
Possible ring interactions for 1
a
Symmetry of ring(B) Cg(A)ꢀ ꢀ ꢀCg(B) ( A˚ ) Angle (°)
b
Cg(A)ꢀ ꢀ ꢀCg(B)
Cg(2)ꢀ ꢀ ꢀCg(4)
Cg(2)ꢀ ꢀ ꢀCg(7)
Cg(3)ꢀ ꢀ ꢀCg(4)
Cg(3)ꢀ ꢀ ꢀCg(7)
Cg(4)ꢀ ꢀ ꢀCg(5)
Cg(4)ꢀ ꢀ ꢀCg(6)
Cg(5)ꢀ ꢀ ꢀCg(7)
x, 1/2 ꢁ y, ꢁ1/2 + z 4.609(3)
x, 1/2 ꢁ y, ꢁ1/2 + z 3.687(3)
4.046(4)
14.7
13.8
32.4
32.6
15.5
31.2
14.6
4.531(3)
x, 1/2 ꢁ y, 1/2 + z
4.381(4)
4.127(4)
x, 1/2 ꢁ y, ꢁ1/2 + z 3.737(3)
group and O atom of an O,O-pyridone bridge giving rise to
˚
a
a four-membered Zn NO ring [Zn(1)–N(11) = 1.996(5) A
Cg = center of gravity of ring; ring (2): N(1)–N(4), C(5); ring (3): N(5)–
2
˚
N(8), C(10); ring (4): N(16)–N(19), C(17); ring (5): N(4); C(4)–C(5); ring
and Zn(1)–O(1) = 2.107(4) A], and links a second Zn cen-
(
6): N(8), C(6)–C(10); ring (7): N(16), C(17)–C(21).
Dihedral angle between planes of rings (A) and (B).
ter via di-EO bridging azides [Zn(1)–N(21) = 2.054(5) A]
˚
b
forming a four membered Zn N unit [Zn(1)–Zn(2) =
2
2
˚
3
.2097(11) A] and finally connects a third Zn(II) atom
through an EO azide group. Thus, the zinc center is in a
3
(
.1.2. Crystal structure of {[Zn (N ) (3-OHpy)] ꢀ 2H O}
five coordinated environment with a ZnN O chromophore.
2
3 4
2
n
4
2)
The principle structure features for complex 2 are illus-
The four-membered ring Zn NO deviates from planarity
2
˚
with a max. deviation = 0.063(6) A for [Zn(1)/O(1)/
˚
trated in Fig. 2a, along with a labeling scheme, and selected
bond lengths and bond angles are collected in Table 4. The
X-ray structure determination of 2 revealed that the Zn(II)
atoms are linked by four azido groups all behave in the l-
Zn(2)/N(11)] and a maximum deviation = 0.090(6) A for
[Zn(1)/O(1)/Zn(2D)/N(11)]. The stereochemistry of both
Zn centers can be best described as distorted TBP with s-
values of 0.67 and 0.61 for Zn(1) and Zn(2), respectively.
Around Zn(1) and Zn(2) the equatorial atoms are N(11),
N(31), N(21) and N(11), N(21B), N(41A) and the axial
atoms are O(1), N(41) and O(1), N(31A), respectively. As
1
,1-EO mode and an oxygen atom from the 3-OH-py
ligand which means that this hydroxypyridine molecule
acts in the tautomeric keto-form, i.e. as pyridone, in the
Fig. 2. (a) Perspective view with atom labeling scheme of 2. Symmetry codes according Table 4. Hydrogen bonds are indicated by broken bonds. (b) 2D
system with tetra- and octa-nuclear rings of Zn(II) centers formed by EO-bridging azido and O,O’-bridging pyridones. The 2D system is extented along the
b- and c-axis of the unit cell. (c) View along the b-axis of unit cell into a 2D sheet of 2.

1428
M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
Table 4
Selected bond lengths (A) and angles (°) for 2
179.3(7)°], and all of them deviate from linearity in connec-
˚
tion with Zn atoms [Zn–N–N angles from 116.1(4)° to
131.6(4)°]. Hydrogen bonds of different types: [O–Hꢀ ꢀ ꢀN]
between O atom of a lattice water molecule and the end
nitrogen atom of an EO azide, or between an oxygen atom
of a lattice water and the nitrogen atom of pyridone ligand
[N–Hꢀ ꢀ ꢀO], and O–Hꢀ ꢀ ꢀO between oxygen atoms of lattice
water molecules are formed (Table 5). These hydrogen
bonds consolidate the structure and lead to the formation
of 3D supramolecular network.
Zn(1)–N(11)
Zn(1)–N(21)
Zn(1)–N(41)
Zn(2)–N(21B)
Zn(2)–O(1)
N(11)–N(12)
N(21)–N(22)
N(31)–N(32)
N(41)–N(42)
O(1)–C(1)
1.996(5)
2.054(5)
2.234(5)
2.034(5)
2.106(4)
1.249(8)
1.249(8)
1.195(7)
1.214(7)
1.337(8)
Zn(1)–N(31)
Zn(1)–O(1)
2.030(5)
2.107(4)
2.028(5)
2.044(5)
2.215(5)
1.150(8)
1.149(8)
1.142(8)
1.143(8)
2.688(8)
3.2799(11)
6.6202(16)
Zn(2)–N(11)
Zn(2)–N(41A)
Zn(2)–N(31A)
N(12)–N(13)
N(22)–N(23)
N(32)–N(33)
N(42)–N(43)
N(1)ꢀ ꢀ ꢀO(2C)
Zn(1)ꢀ ꢀ ꢀZn(2)
3.2097(11) Zn(1)ꢀ ꢀ ꢀZn(2D)
Zn(1)ꢀ ꢀ ꢀZn(2B)
3.6318(12) Zn(1)ꢀ ꢀ ꢀZn(2C)
N(11)–Zn(1)–N(31)
N(31)–Zn(1)–N(21)
N(31)–Zn(1)–O(1)
N(11)–Zn(1)–N(41)
N(21)–Zn(1)–N(41)
128.6(2)
N(11)–Zn(1)–N(21)
N(11)–Zn(1)–O(1)
N(21)–Zn(1)–O(1)
N(31)–Zn(1)–N(41)
O(1)–Zn(1)–N(41)
118.1(2)
113.2(2)
99.5(2)
95.1(2)
94.3(2)
77.3(2)
96.7(2)
78.5(2)
168.7(2)
N(11)–Zn(2)–N(21B) 115.2(2)
N(11)–Zn(2)–N(41A) 125.0(2)
N(21B)–Zn(2)–
N(41A)
119.8(2)
N(11)–Zn(2)–O(1)
76.7(2)
N(21B)–Zn(2)–O(1)
N(11)–Zn(2)–N(31A) 92.9(2)
100.4(2)
N(41A)–Zn(2)–O(1)
N(21B)–Zn(2)–
N(31A)
94.8(2)
97.6(2)
N(41A)–Zn(2)–
N(31A)
78.7(2)
O(1)–Zn(2)–N(31A) 161.7(2)
N(12)–N(11)–Zn(1)
Zn(1)–N(11)–Zn(2)
N(22)–N(21)–Zn(2B) 116.1(4)
Zn(2B)–N(21)–Zn(1) 125.4(2)
127.3(4)
105.8(2)
N(12)–N(11)–Zn(2)
N(13)–N(12)–N(11) 178.1(7)
N(22)–N(21)–Zn(1) 114.6(4)
N(23)–N(22)–N(21) 179.3(7)
N(32)–N(31)–Zn(2D) 127.2(4)
N(33)–N(32)–N(31) 178.9(6)
124.8(4)
N(32)–N(31)–Zn(1)
131.6(4)
Zn(1)–N(31)–Zn(2D) 101.1(2)
N(42)–N(41)–Zn(2D) 123.3(4)
Zn(2D)–N(41)–Zn(1) 100.0(2)
C(1)–O(1)–Zn(2)
Zn(2)–O(1)–Zn(1)
N(42)–N(41)–Zn(1)
N(43)–N(42)–N(41) 178.3(7)
C(1)–O(1)–Zn(1) 130.4(4)
122.6(4)
130.3(4)
99.3(2)
Symmetry codes: (A) 1 ꢁ x, ꢁ1/2 + y, 3/2 ꢁ z. (B) 1 ꢁ x, ꢁy, 2 ꢁ z. (C) x,
1
1
/2 ꢁ y, 1/2 + z. (D) 1 ꢁ x, 1/2 + y, 3/2 ꢁ z. (E) x, 1/2 ꢁ y, ꢁ1/ 2 + z. (F)
+ x, 1/2 ꢁ y, 1/2 + z.
can be seen from Fig. 2b, four zinc(II) centers are intercon-
nected by EO azides to afford a tetranuclear ring and eight
zinc centers are interconnected to form an octanuclear ring.
These two types of rings are the bases for the formation of
the 2D sheet. The Znꢀ ꢀ ꢀZn distances within the tetranu-
˚
clear zinc(II) rings are: 3.2097(11) and 3.6318(12) A; the
Znꢀ ꢀ ꢀZn separations between opposite pairs of metal cen-
ters within the octanuclear zinc(II) rings are in the range
˚
from 7.625(2) to 9.714(3) A. The azide groups are asym-
metric and linear [N–N–N angles are from 178.1(7)° to
Table 5
Hydrogen bonding system for 2
a
Dꢀ ꢀ ꢀA ( A˚ ) D–Hꢀ ꢀ ꢀA (°)
D–Hꢀ ꢀ ꢀA
Symmetry of A
N(1)–H(1)ꢀ ꢀ ꢀO(2)
O(2)–H(21)ꢀ ꢀ ꢀO(3)
O(2)–H(22)ꢀ ꢀ ꢀO(3)
x, ꢁ1/2 ꢁ y,1/2 + z
1 ꢁ x, ꢁy,1 ꢁ z
1 + x, y, z
2.688(8)
2.899(8)
2.799(9)
171.6
156.0
175.7
140.3
151.9
O(3)–H(31)ꢀ ꢀ ꢀN(43) x, 1/2 ꢁ y, ꢁ1/2 + z 2.937(9)
Fig. 3. (a) Perspective view with atom labeling scheme of 3. Symmetry
codes according Table 6. (b) Packing plot of 3 along the a-axis of the unit
cell.
O(3)–H(32)ꢀ ꢀ ꢀN(13)
2.970(9)
a
D = donor, A = acceptor.

M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
1429
3
.1.3. Crystal structure of [Zn(N ) (pym)] (3)
3 2 n
The principle structural features of complex 3 are shown
in Fig. 3a, along with a labeling scheme, and selected bond
lengths and bond angles are collected in Table 6. The struc-
ture features six coordinate Zn(II) atoms, EE bridging
0
azido ligands and N,N -bidentate bridging pym ligand
forming a 3D network. In the asymmetric unit, each Zn(II)
center is surrounded by four EE azide bridges [Zn(1)–
˚
˚
N(2) = 2.151(3) A, Zn(1)–N(4) = 2.148(3) A], and two
0
nitrogen atoms from bidentate N,N -pyrimidine bridging
ligands [Zn(1)–N(1) = 2.188(3) A] to adopt ZnN chromo-
˚
6
phore. The 3D system can be seen as zinc-pym chains
placed in parallel planes, zinc atoms lie on inversion cen-
ters, pym ligands lie across mirror planes and azido ligands
lie about 2-fold axes. The four EE azido bridges link each
zinc center to two similar chains placed in the upper plane
and two similar chains placed in the lower plane. The Zn–
N–N bond angles lie around 122.5°. The azido ligands are
symmetric [N(2)–N(3) = 1.176(2), N(3)–N(2B) = 1.176(2)
˚
˚
A and N(4)–N(5) = 1.179(2), N(5)–N(4C) = 1.179(2) A]
and linear [N–N–N angles = 178.1(4)° and 179.2(5)°]
(
Fig. 3b).
3
.2. IR and luminescence spectra
Fig. 4. Luminescence spectrum of 2.
The IR spectra of the title complexes in the solid state
exhibit the following very strong band associated with the
The photoluminescence properties of the solid zinc(II)
complexes have been studied at room temperature. Com-
plexes 1 and 3 do not flouresce, whereas complex 2 exhibits
photoluminescence. 3-Hydroxypyridine shows photolumi-
nescence at room temperature with an emission maximum
at ca. 390 nm upon excitation at 300 nm. The zinc complex
derived from 3-OHpy, 2 exhibits also a strong emission at
390 nm (FWHM: 22 nm) upon excitation at 300 nm
(Fig. 4). As Zn(II), Cd(II) and Hg(II) are not easily oxidize
or reduce due to their electronic d configuration, no emis-
sion originated from metal centers excited states are
expected in case of such cations. Thus the flourescence
observed in case of complex 2 is assigned to the intra-ligand
flourescence [23,24]. The complexation of the ligands may
also increase the rigidity and reduces the loss of energy
by thermal vibrational decay. However, 3-OHpy from
which complex 2 is derived, in the solid state exist in the
keto and enol tautomers, and its flourescence is due to both
tautomeric forms. In complex 2, the 3-OHpy exists only in
the keto form, in which the pair of electron remain as in the
free ligand. This may explain why both 3-OHpy and its
Zn(II) azide complex fluoresce almost at the same wave-
length maximum, except that the intensity of the floures-
cence of the complex is more than twice the intensity of
the free 3-OHpy ligand.
ꢁ
1
m (N ) vibration mode: 2012, 2098 cm ; 2121, 2091
as
3
ꢁ
1
ꢁ1
cm , and 2078 cm , for complexes 1, 2, and 3, respec-
tively. The positions of these bands for 1 and 2 with EO
azide bridges only are higher than expected [around 2090,
ꢁ
1
ꢁ1
2
070 cm , and 2100, 2065 cm for 1 and 2, respectively]
if the relationship m (N ) versus Dd [Dd the difference
as
3
between the two N–N distances in an azide group] reported
earlier [21,22] is valid. The existence of hydrogen bonded
lattice water in complex 2 is confirmed by the appearance
1
0
ꢁ
1
of broad bands in the range of 3600–2500 cm
.
Table 6
˚
Selected bond lengths (A) and angles (°) for 3
Zn(1)–N(4A)
Zn(1)–N(2)
Zn(1)–N(1A)
N(2)–N(3)
2.148(2)
2.151(3)
2.188(3)
1.176(2)
1.179(2)
6.042(2)
5.588(2)
Zn(1)–N(4)
Zn(1)–N(2A)
Zn(1)–N(1)
N(3)–N(2B)
N(5)–N(4C)
Zn(1)ꢀ ꢀ ꢀZn(1B)
2.148(2)
2.151(3)
2.188(3)
1.176(2)
1.179(2)
5.752(2)
N(4)–N(5)
Zn(1)ꢀ ꢀ ꢀZn(1D)
Zn(1)ꢀ ꢀ ꢀZn(1C)
N(4A)–Zn(1)–N(4)
N(4)–Zn(1)–N(2)
N(4)–Zn(1)–N(2A)
N(4A)–Zn(1)–N(1A)
N(2)–Zn(1)–N(1A)
N(4A)–Zn(1)–N(1)
N(2)–Zn(1)–N(1)
N(1A)–Zn(1)–N(1)
N(2)–N(3)–N(2B)
N(4)–N(5)–N(4C)
180.0
N(4A)–Zn(1)–N(2)
92.16(10)
87.84(10)
180.0
90.21(10)
92.46(10)
89.79(10)
87.54(10)
122.5(2)
123.6(2)
87.84(10)
92.16(10)
89.79(10)
87.54(10)
90.21(10)
92.46(10)
180.0
N(4A)–Zn(1)–N(2A)
N(2)–Zn(1)–N(2A)
N(4)–Zn(1)–N(1A)
N(2A)–Zn(1)–N(1A)
N(4)–Zn(1)–N(1)
N(2A)–Zn(1)–N(1)
N(3)–N(2)–Zn(1)
N(5)–N(4)–Zn(1)
4. Discussion
179.2(5)
178.1(4)
Three zinc(II) azido complexes of three different ligands
Symmetry codes: (A) ꢁx + 1/2, ꢁy + 1/2, ꢁz + 3/2. (B) ꢁx, y, ꢁz + 2. (C)
x, y, ꢁz + 1. (D) x, ꢁy, z.
have been synthesized. In fact the ligand tetrazolo[1,5-
a]pyridine (py-tetrazole) was prepared through the interac-
ꢁ

1430
M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
Although we started with 2-chloropyridine which interacts
with the azide ion forming py-tetrazole ligand and the iso-
lated complex found to be {[Zn(N ) (py-tetrazole) ](py-tet-
3
4
2
razole)}n (1) which links the zinc ion not through the
pyridine nitrogen atom but via a nitrogen atom from the
tetrazole part. The ladder-like structure of this complex
contains tetranuclear zinc(II) rings. This structure is
unprecedented. In complex 2, the 3-Ohpy, starting reactant
found to behave in the tautomeric keto-form and ligated
zinc atoms as O,O-bidentate bridging ligand, in addition
to the existence of tetranuclear zinc(II) and octanuclear
zinc(II) rings fused together to generate 2D sheets which
carrying into 3D supramolecular network with the help
of hydrogen bonding. This complex exhibits photolumines-
cence at room temperature, and is unprecedented too in the
metal azide complexes. Complex 3 consists of three-dimen-
sional network. These results prompted us to explore the
synthesis of zinc and other metal complexes with 2-, and
Fig. 5. Simplified representation of the structural motifs observed in
complexes 1 (ladder, 1D), 2 (rings, 2D) and 3 (cubes, 3D).
ꢁ
tion of 2-chloropyridine with azide N3 ion under hydro-
thermal conditions, as given in Scheme 1; the py-tetrazole
then interacts with zinc(II) azide affording complex 1. In
the case of complex 2, we started with 3-hydroxypyridine,
under reaction condition this ligand seems to prefer to be
in the tautomeric keto-form, and we obtained a complex
containing the pyridone which behaves as an O,O-biden-
tate bridging ligand. As we have seen the structure of com-
plex 1 consists of a ladder-like arrangement in which four
zinc centers interconnect through EO bridging azide form-
ing tetranuclear rings and the uncoordinated py-tetrazole
molecules are located in the channels between the parallel
ladders. This structure is unprecedented in metal azido
complexes. The structure of complex 2, on the other hand,
consists of tetranuclear zinc(II) rings fused with octanucle-
ar zinc(II) rings forming 2D sheets, which is carrying into
4-hydroxypyridines as well as other 2-X-pyridines in pres-
ence of azide ion and to explore the photoluminescence
of the isolated complexes. Such reactions are under current
investigation.
Supplementary data
CCDC 660643, 660644 and 660645 contain the supple-
mentary crystallographic data for compounds 1, 2 and 3.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/const/retrieving.html or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-
mail: deposit@ccdc.cam.ac.uk.
3
D network through the hydrogen bonding interaction.
This structure too is unprecedented in known metal azido
Acknowledgements
complexes (Fig. 5). In both complexes 1 and 2 with EO
azide bridges only, the Zn–Zn distances within the Zn N
cyclic units fall well within the range of 3.03–3.31 A found
for other zinc(II) azido complexes containing such units
2
2
F.A.M. thanks Profs. F. Belaj and C. Kratky (Univ.
Graz) and Dr. J. Baumgatrner (TU Graz) for assistance.
˚
[
25]. All EO bridging azides in both complexes are asym-
References
metric [the two N–N lengths within the azide group are dif-
ferent] and linear as reported earlier [26]. Complex 3
contains only EE bridging azido ligands which are symmet-
rical and linear as usual [26], and its structure resembles
that of manganese(II) azide with pyrimidine [27]. In terms
of network analysis [28] the topology of 2 may be described
[1] (a) S.-L. Zheng, M.-L. Tong, H.-L. Zhu, Y. Fang, X.-M. Chen, J.
Chem. Soc., Dalton Trans. (2001) 2049;
(
(
b) S. Banerjee, M.G.B. Drew, A. Ghosh, Polyhedron 22 (2003) 2933;
c) J.M. Lehn, Supramolecular Chemistry – Concepts and Perspec-
tives, VCH, Weinheim, 1995 (Chapter 9).
[
[
[
2] (a) R. Robson, B.F. Abrahams, S.R. Batten, R.W. Gable, B.F.
Hoskins, J. Liu, Supramolecular Architecture, ACS, Washington,
DC, 1992, p. 256.;
(b) G.R. Desiraju, Angew. Chem., Int. Ed. Engl. 34 (1995) 2311.
3] (a) P. Lightfoot, A. Snedden, J. Chem. Soc., Dalton Trans. (1999)
2
as a distorted ‘‘4.8 ” 2D net [the lengths of the edges within
˚
the tetranuclear rings are 3.210 and 3.632 A, respectively,
˚
and additionally 3.280 A in the octanuclear rings (Fig. 5,
bottom left)]; the topology of 3 as distorted ‘‘a-Po” 3D
3
549;
net [the lengths of the edges of the cubes are 5.588, 5.752
(
b) M.-L. Tong, X.-M. Chen, X.-L. Yu, T.C.W. Mak, J. Chem. Soc.,
˚
and 6.042 A, respectively (Fig. 5, bottom right)].
Dalton Trans. (1998) 5.
4] (a) L.R. MacGillivray, R.H. Groeneman, J.L. Atwood, J. Am. Chem.
Soc. 120 (1998) 2676;
5
. Conclusions
(
4
(
b) X.-M. Chen, M.-L. Tong, Y.-J. Luo, Z.-N. Chen, Aust. J. Chem.
9 (1996) 853;
c) M.-L. Tong, X.-M. Chen, S.W. Ng, Inorg. Chem. Commun. 3
(2000) 436.
We isolated three zinc(II) azide complexes with some
pyridines and pyrimidine by hydrothermal technique.

M.A.S. Goher et al. / Polyhedron 27 (2008) 1423–1431
1431
[
[
5] (a) M.-L. Tong, X.-M. Chen, B.-H. Ye, L.-N. Ji, Angew. Chem., Int.
Ed. Engl. 38 (1999) 2237;
[15] (a)F.A. Cotton, G. Wilkinson, C.A. Morillo, M. Bochmann, Advanced
Inorganic Chemistry, 6th ed., Wiley, New York, 1999, p. 589.;
(b) K.-Y. Ho, W.-Y. Yu, K.-K. Cheung, C.-M. Che, Chem. Commun.
(1998) 2101.
[16] (a) D. Bose, S.H. Rahaman, G. Mostafa, R.D.B. Walsh, M.J.
Zaworotko, B.K. Ghosh, Polyhedron 23 (2004) 545;
(b) H.C. Pan, F.P. Liang, C.J. Mao, J.J. Zhu, J. Phys. Chem. B 111
(2007) 5700.
(
b) M.-L. Tong, H.-K. Lee, X.-M. Chen, R.-B. Huang, T.C.W. Mak,
J. Chem. Soc., Dalton Trans. (1999) 3657;
c) B.D. Wagner, G.J. McManus, B. Moulton, Mu. J. Zaworotko,
(
Chem. Commun. (2002) 2176.
6] (a) N. Mondal, M.K. Saha, S. Mitra, V. Gramlich, J. Chem. Soc.,
Dalton Trans. (2000) 3218;
(
b) J. Ribas, A. Escuer, M. Monfort, R. Vicente, R. Cortes, L.
Lezama, T. Rojo, Coord. Chem. Rev. 193–195 (1999) 1027;
c) G.S. Papaefstathiou, S.P. Perlepes, A. Escuer, R. Vicente, M.
Font-Bardia, X. Solans, Angew. Chem., Int. Ed. Engl. 40 (2001)
84.
[17] (a) B. Xu, B. Yan, Spectrosc. Lett. 39 (2006) 237;
(b) L.-Y. Zhang, G.-F. Liu, S.-L. Zheng, B.-H. Ye, X.-M. Zhang, X.-
M. Chen, Eur. J. Inorg. Chem. (2003) 2965.
[18] M.A.S. Goher, F.A. Mautner, K. Gatterer, M.A.M. Abu-Youssef,
A.M.A. Badr, B. Sodin, C. Gspan, J. Mol. Struct., in press,
doi:10.1016/j.molstruc.2007.06.020.
(
8
[
7] (a) S.A. Barnett, A.J. Blake, N.R. Champness, C. Wilson, Chem.
Commun. (2002) 1640;
[19] (a) B. Bitschnau, A. Egger, A. Escuer, F.A. Mautner, B. Sodin, R.
Vicente, Inorg. Chem. 45 (2006) 868;
(b) A. Escuer, J. Cano, M.A.S. Goher, Y. Journaux, F. Lloret, F.A.
Mautner, R. Vicente, Inorg. Chem. 39 (2000) 4688.
8] B. Zurowska, J. Mrozinski, M. Julve, F. Lloret, A. Maslejova, W.
Sawka-Dobrowolska, Inorg. Chem. 41 (2002) 1771.
(b) H.D. Fair, R.F. Walker (Eds.), Energetic Materials, vol. 1,
Plenum Press, New York, 1977 (Chapter 1).
[20] (a) N. Walker, D. Stuart, Acta Crystallogr., Sect. A 39 (1983) 158;
(b) R.H. Blessing, Acta Crystallogr., Sect. A 51 (1995) 33, SADABS,
Bruker AXS, 1998.;
[
[
9] (a) F. Wiesbrock, H. Schmidbaur, J. Chem. Soc., Dalton Trans.
(
(
2002) 3201;
b) O.R. Evans, W. Lin, Inorg. Chem. 39 (2000) 1771.
(c) SHELXTL 5.03 (PC-Version) Program Library for the Solution and
Molecular Graphics, Siemens Analytical Instruments Division, Mad-
ison, WI, 1995.
[
[
10] (a) M.A.S. Goher, T.C.W. Mak, Inorg. Chim. Acta 85 (1984) 117;
(
(
(
b) M.A.S. Goher, T.C.W. Mak, Inorg. Chim. Acta 89 (1984) 119;
c) M.A.S. Goher, F.A. Mautner, Croat. Chim. Acta 63 (1990) 559;
d) A. Escuer, R. Vicente, M.A.S. Goher, F.A. Mautner, Inorg.
[21] I. Agrell, Acta Chem. Scand. 25 (1971) 2965.
[22] M.A.S. Goher, Acta Chim. Hung. 127 (1990) 213.
[23] H.F. Zhu, L. Li, T. Okamura, W. Zhao, W.Y. Skn, N. Ueyama, Bull.
Chem. Soc. Jpn. 76 (2003) 761.
Chem. 35 (1996) 6386.
11] (a) M.A.S. Goher, N.A. Al-Salem, F.A. Mautner, J. Coord. Chem. 44
(
(
1998) 119;
[24] X.H. Be, H. Liu, M. Du, K.M.C. Wong, V.W.W.W. Yam, Inorg.
Chim. Acta 333 (2002) 32.
b) M.A.S. Goher, A. Escuer, F.A. Mautner, N.A. Al-Salem,
Polyhedron 20 (2001) 2971;
c) H.-Y. Shen, D.-Z. Liau, Z.-H. Jiang, S.-P. Yan, G.-L. Wang, X.-
K. Yao, H.-G. Wang, Chem. Lett. (1998) 469.
12] (a) E.-Q. Gao, S.-Q. Bai, C.-F. Wang, Y.-F. Yue, C.-H. Yan, Inorg.
Chem. 42 (2003) 8456;
[25] e.g. F.A. Mautner, H. Krischner, Monatsh. Chem. 123 (1992) 325.
[26] (a) e.g. Z. Dori, R.F. Ziolo, Chem. Rev. 73 (1973) 248;
(b) M.A.S. Goher, F.A. Mautner, Polyhedron 18 (1999) 1805;
(c) A. Escuer, M.A.S. Goher, F.A. Mautner, R. Vicente, Inorg.
Chem. 39 (2000) 2107.
(
[
(
1
b) E.-Q. Gao, Y.-F. Yue, S.-Q. Bai, Z. He, C.-H. Yan, Chem. Mater.
6 (2004) 1590.
13] e.g. M.A.S. Goher, R.J. Wang, T.C.W. Mak, J. Mol. Struct. 243
1991) 179.
[27] A. Escuer, R. Vicente, F.A. Mautner, M.A.S. Goher, M.A.M. Abu-
Youssef, Chem. Commun. (2002) 64.
¨
[
[
[28] (a) L. Ohrstr o¨ m, K. Larsson, Molecule-Based Materials: The
(
Structural Network Approach, Elsevier, Amsterdam, 2005;
(b) A.F. Wells, Three-dimensional Nets and Polyhedra, Wiley, New
York, 1977;
14] (a) Z. Shen, J.-L. Zuo, Z. Yu, Y. Zhang, J.-F. Bai, C.-M. Che, H.-K.
Fun, J.J. Vittal, X.-Z. You, Dalton Trans. (1999) 3393;
(
b) A. Escuer, R. Vicente, M.A.S. Goher, F.A. Mautner, Dalton
(c) M. O’Keeffe, M. Eddaoudi, H.L. Li, T. Reineke, O.M. Yaghi, J.
Solid State Chem. 152 (2000) 3;
Trans. (1997) 4431;
(
(
c) S.S. Tandon, L.K. Thompson, D.O. Miller, Chem. Commun.
1995) 1907.
(d) O.V. Dolomanov, A.J. Blake, N.R. Champness, M. Schroder, J.
Appl. Crystallogr. 36 (2003) 1283.