Solvothermal syntheses, crystal structures, and luminescent properties of two novel silver(I) coordination polymers containing 5-aryl-substituted tetrazolate ligands

Article abstract of DOI:10.1016/j.molstruc.2007.05.007

The solvothermal reactions of AgNO₃, NaN₃, with benzonitrile or 4-cyanopyridine in methanol/water yield two novel metal-organic coordination polymers, [Ag(μ₃-phtta)]_n (1) (phtta = 5-phenyltetrazolate) and {Ag[μ₄-(4-pytta)]}_n (2) [4-pytta = 5-(4-pyridyl)tetrazolate], respectively. The two reactions were involved in the in situ formation of 5-aryl-substituted tetrazolate ligands (phtta and pytta) through [2 + 3] cycloaddition reactions of azide anion with benzonitrile or 4-cyanopyridine. Compounds 1 and 2 were characterized by elemental analysis, IR spectra, and single-crystal X-ray crystallography. Compound 1 has a one-dimensional double-chain structure in which centrosymmetric dimeric [Ag(phtta)]₂ units are interconnected by four Ag-N bonds. These double-chains are further stacked into a 2D layer network through π-π interactions between tetrazolyl rings and interactions between Ag⁺ and phenyl group or tetrazolyl ring. Compound 2 has an intriguing 3D non-interpenetrated supramolecular structure in which a 2D layer network with (4.8²)_Ag(4.8²)_pytta topology holds the adjacent layers together via interactions of Ag⁺ ions in one layer with 4-N atoms of pytta ligands in the other. Photoluminescence studies revealed that solids 1 and 2 exhibit strong blue fluorescent emissions at λ_max = 422 and 390 nm (λ_ex = 345 nm), respectively, at ambient temperature.

Full text of DOI:10.1016/j.molstruc.2007.05.007

Available online at www.sciencedirect.com
Journal of Molecular Structure 875 (2008) 339–345
www.elsevier.com/locate/molstruc
Solvothermal syntheses, crystal structures, and luminescent
properties of two novel silver(I) coordination polymers containing
5-aryl-substituted tetrazolate ligands
a
a
a
a
a
Yang Chen , Zhi-Gang Ren , Hong-Xi Li , Xiao-Yan Tang , Wen-Hua Zhang ,
a
a,b,
*
Yong Zhang , Jian-Ping Lang
a
School of Chemistry and Chemical Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s Republic of China
State Key Laboratory of Coordination Chemistry, Nanjiang University, Nanjing 210093, Jiangsu, People’s Republic of China
b
Received 3 March 2007; received in revised form 4 May 2007; accepted 8 May 2007
Available online 13 May 2007
Abstract
The solvothermal reactions of AgNO3, NaN3, with benzonitrile or 4-cyanopyridine in methanol/water yield two novel metal–organic
coordination polymers, [Ag(l3-phtta)]n (1) (phtta = 5-phenyltetrazolate) and {Ag[l4-(4-pytta)]}n (2) [4-pytta = 5-(4-pyridyl)tetrazolate],
respectively. The two reactions were involved in the in situ formation of 5-aryl-substituted tetrazolate ligands (phtta and pytta) through
[2 + 3] cycloaddition reactions of azide anion with benzonitrile or 4-cyanopyridine. Compounds 1 and 2 were characterized by elemental
analysis, IR spectra, and single-crystal X-ray crystallography. Compound 1 has a one-dimensional double-chain structure in which cen-
trosymmetric dimeric [Ag(phtta)]2 units are interconnected by four Ag–N bonds. These double-chains are further stacked into a 2D layer
network through p–p interactions between tetrazolyl rings and interactions between Ag+ and phenyl group or tetrazolyl ring. Compound
2 has an intriguing 3D non-interpenetrated supramolecular structure in which a 2D layer network with (4.82)Ag(4.82)pytta topology holds
the adjacent layers together via interactions of Ag+ ions in one layer with 4-N atoms of pytta ligands in the other. Photoluminescence
studies revealed that solids 1 and 2 exhibit strong blue fluorescent emissions at kmax = 422 and 390 nm (kex = 345 nm), respectively, at
ambient temperature.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Silver(I); Coordination polymer; Tetrazolate ligands; Solvothermal synthesis; Crystal structures; Luminescence properties
1. Introduction
hydro(solvo)thermal reactions of silver(I) salts with
organic components [7–9,21–35]. In later reactions, various
N-containing ligands were found to be generated in situ
from inorganic and/or organic components under the pres-
ence of metal ions. For example, some tetrazolate ligands
could be prepared in situ through so-called Demko-Sharp-
less [2 + 3] cycloaddition reactions of organic nitriles with
The construction of supramolecular complexes from sil-
ver(I) salts and multi-topic N-containing ligands has
recently attracted much attention due to their intriguing
topology structures [1–8], and their potential applications
in fluorescence [9–13], electrochemical properties [14–16],
electrical conductivity [17], materials science [18], and anti-
microbial properties [19]. These compounds are mainly
prepared from routine solution reactions [1–6,10–20] or
azide anion in the presence of metal ions such as Zn2+
,
Cd2+, Ag+, and Cu+ [22–35]. In the case of silver/tetrazo-
late complexes, only six examples have been reported up to
now and they were all prepared from this unique cycload-
dition reaction. The tetrazolate ligands in these structures
are mainly 5-alkyl-substituted tetrazolates [7,8] and only
one is 5-aryl-substituted tetrazolate [8]. Being aware of
the fact that the chemistry of silver complexes with
*
Corresponding author. Address: School of Chemistry and Chemical
Engineering, Suzhou University, Suzhou 215123, Jiangsu, People’s
Republic of China. Tel.: +86 512 6588 2865; fax: +86 512 6588 0089.
E-mail address: jplang@suda.edu.cn (J.-P. Lang).
0022-2860/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2007.05.007

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Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
5-aryl-substituted tetrazolates are less unexplored, we
chose benzonitrile and 4-cyanopyridine and carried out
their reactions with sodium azide at solvothermal condi-
tions and two [Ag(l3-phtta)]n (1) (phtta = 5-phenyltetrazo-
late) and {Ag[l4-(4-pytta)]}n (2) [4-pytta = 5-(4-
pyridyl)tetrazolate] were isolated therefrom. Herein, we
report their syntheses, crystal structures, and luminescent
properties.
4-cyanopyridine into 1,3,5-triazine derivatives at reaction
conditions [36–38]. Solids 1 and 2 are stable towards air
and moisture and insoluble in common organic solvents
such as DMFÆDMSO, MeCN, toluene, MeOH, and
CH2Cl2. The elemental analyses of 1 and 2 are consistent
with their chemical formula. The identities of 1 and 2 were
finally confirmed by X-ray crystallography.
2.2. Molecular structure of 1
2. Results and discussion
Compound 1 crystallizes in the monoclinic space group
P21/n and the asymmetric unit consists of an Ag+ ion and a
phtta anion. Compound 1 has a one-dimensional double-
chain structure (extending along the c axis) in which two
parallel [Ag(phtta)]n chains are alternatively arranged so
that the Ag1 atom in one chain further interacts with the
N2 of the phtta ligand of the other chain (Fig. 1). Alterna-
tively, the 1D double-chain structure of 1 may be viewed as
being built of centrosymmetric dimeric [Ag(phtta)]2 units
linked by four Ag–N bonds (e.g. Ag1–N3B, Ag1A–N3C,
Ag1C–N3A, Ag1E–N3). In the structure of 1, each phtta
ligand coordinates to three Ag+ ions and serves as a l3-
1,2,3-tetrazolyl coordination mode, which was previously
observed only in [Zn(mtta)2]3(H2O) (mtta = 5-methyltet-
razolate) [29]. The Ag1 center is coordinated by N1,
N2A, and N3B, forming an approximate trigonal coordi-
2.1. Preparation and characterization of 1 and 2
The reaction of AgNO3 with equimolar sodium azide
and 2.5 equiv. of benzonitrile in H2O/MeOH (v/
v = 1:2.5) under solvothermal conditions at 150 ꢁC for
67 h gave rise to 1 as brown plates in 68.3% yield. On the
other hand, analogous reactions of 1:1:2.5 AgNO3/NaN3/
4-cyanopyridine at similar conditions produced colorless
prismatic crystals of 2 in a relatively low yield (24.2%). For-
mation of 1 and 2 was confirmed by their elemental analy-
ses and IR spectra. The absence of the cyano group in the
range of 2200 cmꢀ1 and the appearance of a new stretching
vibration of tetrazolate anion at ca. 1400 cmꢀ1 in the IR
spectrum are line with the in situ formation of tetrazolate
ligand generated by a [2 + 3] cycloaddition reaction of ben-
zonitrile or 4-cyanopyridine with azide anion [24,30,31].
Short reaction time (<10 h) or low reaction temperature
(<100 ꢁC) or low molar ratio of reagents (e.g. AgNO3/
NaN3/benzonitrile (or 4-cyanopyridine) = 1:1:1) for these
reactions always resulted in a mixture of a small amount
of 1 or 2 coupled with a large amount of unreacted starting
materials. The IR spectrum of the mixture revealed the
presence of the strong stretching vibrations of azide group
(2050 cmꢀ1) and cyano groups (2200 cmꢀ1) of benzonitrile
or 4-cyanopyridine. In addition, prolonged reaction time
(>100 h) and high reaction temperature (>180 ꢁC) for these
reactions afforded 1 in a very low yield (<1%). The reason
for this may be due to the trimerization of benzonitrile or
nation geometry (Table 1). The Ag1ꢁ ꢁ ꢁAg1A separation
˚
within the dimeric unit is 3.689(6)
A
while the
Ag1Eꢁ ꢁ ꢁAg1A and Ag1ꢁ ꢁ ꢁAg1C contacts between the
˚
dimeric units are 4.009(6) A. The former value is close to
the sum of the van der Walls radii of two Ag atoms, sug-
gesting weak Agꢁ ꢁ ꢁAg interactions. The mean Ag–N bond
˚
length of 2.272(4) A is slightly longer than those containing
˚
trigonally-coordinated Ag such as [Ag(mtta)]n (2.238(6) A
˚
[7] and 2.219(12) A [8]). It is interesting to note that in
the crystal of 1, each 1D double-chain further binds to
adjacent chains through p–p interactions between tetrazol-
yl rings and interactions between Ag+ and phenyl group or
tetrazolyl ring to form a 2D layer structure (Fig. 2). The
Fig. 1. Perspective view of a section of the double-chain structure (extending along the cs axis) of 1 with labeling scheme and 50% thermal ellipsoid.
Symmetry codes: A: ꢀx + 2, ꢀy, ꢀz + 2; B: x, y, z + 1; C: ꢀx + 2, ꢀy, ꢀz + 1; E: x, y, z ꢀ 1.

Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
341
˚
Table 1
Selected bond lengths (A) and angles (ꢁ) for [Ag(l3-phtta)]n (1)
is noted that the Ag1–N4B distance (2.530(2) A) is longer
˚
˚
than the other three (2.253(2)–2.352(2) A). As a whole,
Ag(1)–N(1)
Ag(1)–N(2A)
N(2)–N(3)
C(1)–N(4)
2.263(4)
2.304(5)
1.311(6)
1.341(7)
Ag(1)–N(3B)
N(1)–N(2)
N(3)–N(4)
C(1)–N(1)
2.248(5)
1.345(6)
1.351(7)
1.342(7)
each pytta in 2 serves as a tetradentate ligand. In the struc-
ture of 2, the 1-N, 2-N, and 4-N atoms of the tetrazolate of
each pytta ligand bind to three Ag+ ions, respectively,
forming a l3-1,2,4-tetrazolyl coordination mode that was
observed in [Ag(mtta)]n [7,8]. If the longer Ag1–N4 bond
is neglected, the structure shows a 2D three-connected
(4,8) layer with a Schafli symbol (4.82)Ag(4.82)pytta in which
Ag1 and the tetrazolate work as 3-connecting nodes
(Fig. 4). Interestingly, the resulting wavy 2D layer further
holds the adjacent layers together via interactions of Ag+
ions in one layer with 4-N atoms of pytta ligands in the
other, forming a unique 3D non-interpenetrated supramo-
lecular structure (Fig. 5). The Agꢁ ꢁ ꢁAg contacts within the
N(1)–Ag(1)–N(3B)
N(1)–Ag(1)–N(2A)
N(2)–N(1)–Ag(1)
N(2)–N(3)–Ag(1E)
C(1)–N(1)–Ag(1)
N(4)–C(1)–N(1)
133.95(17)
117.67(16)
115.7(3)
127.2(4)
137.4(4)
111.6(5)
109.4(4)
N(2A)–Ag(1)–N(3B)
N(1)–N(2)–Ag(1A)
N(3)–N(2)–Ag(1A)
N(4)–N(3)–Ag(1E)
N(2)–N(3)–N(4)
107.29(16)
125.2(3)
125.4(4)
122.6(3)
109.9(4)
104.8(4)
104.2(4)
C(1)–N(1)–N(2)
C(1)–N(4)–N(3)
N(3)–N(2)–N(1)
shortest centroid–centroid distance between tetrazolyl rings
is 3.380(7) A, while that between Ag ion and phenyl group
or tetrazolyl ring is 3.502(8) A or 3.682(8) A. The phenyl
group and the tetrazolyl ring of the phtta ligand in 1 are
not co-planar with their dihedral angle of 11ꢁ, which is
probably due to those weak interactions.
+
˚
˚
layer are 4.1137(11) A while those between the layers are
˚
˚
˚
6.2754(10) A. Both contacts are too long to include any
metal–metal interaction. Like the phtta ligand in 1, the pyr-
idyl group of the pytta in 2 is also not co-planar with its tet-
razolate ring, and the dihedral angel between them is
37.09(6)ꢁ.
2.3. Molecular structure of 2
Compound 2 crystallizes in the monoclinic space group
P21/c and the asymmetric unit contains an Ag+ ion and a
pytta anion. As shown in Fig. 3, the Ag1 atom is bound
to one N5C from one pyridyl group and three N atoms
(N1, N2A, N4B) from three tetrazolyl groups of four differ-
ent pytta ligands, forming a rare trigonal pyramidal one. It
2.4. Luminescent properties
It is well known that complexes containing silver(I) ions
and nitrogen-containing ligands have been investigated for
luminescence properties [9–13,39,40]. As shown in Fig. 6,
compounds 1 and 2 showed strong luminescent properties
Fig. 2. Cell packing diagram of 1 looking along the c axis. The dashed lines represent the p–p interactions between tetrazolyl rings and those between Ag+
and phenyl group or tetrazolyl ring.

342
Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
Fig. 3. Perspective view of the coordination environment around the silver(I) center of 2 with labeling scheme and 50% thermal ellipsoid. All hydrogen
atoms are omitted for charity. Symmetry codes: A: ꢀx + 2, ꢀy + 1, ꢀz; B: x, ꢀy + 3/2, z + 1/2; C: ꢀx + 1, y ꢀ 1/2, ꢀz + 1/2; D: ꢀx + 2, y ꢀ 1/2, ꢀz ꢀ 1/
2; E: x + 1, ꢀy + 3/2, z ꢀ 1/2.
in the solid state at ambient temperature. When excited at
ex = 345 nm, the luminescent spectra of 1 and 2 exhibited
3. Conclusions
k
maximal emission peaks at 422 nm (1) and 390 nm (2),
respectively. The possible origin of these peaks is tenta-
tively attributed to ligand-to-ligand transitions from the
phtta ligands in 1 or the pytta ligands in 2, which are in
agreement with silver(I) coordination polymers of N-con-
taining multi-topic ligands reported by others [13,40]. In
addition, the relatively efficient p–p interactions between
tetrazolyl rings in 1 may account for the red shift of the
emission peak in the spectrum of 1 relative to that of 2.
In this paper, we demonstrated the successful syntheses
of two new silver(I) coordination polymers (1 and 2) con-
taining phtta and pytta ligands from reactions of AgNO3,
NaN3 and benzonitrile or 4-cyanopyridine at solvothermal
conditions. The two reactions are involved in the in situ
generation of two new tetrazolate ligands (phtta and pytta)
from the [2 + 3] cycloaddition reaction of organonitriles
and azide anion. X-ray analysis revealed that 1 contains
a 1D double-chain structure and each chain in the crystal
Fig. 4. The 2D network in 2 extending along the bc plane. All the Ag1–N4 bonds and the hydrogen atoms are omitted for clarity.

Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
343
Fig. 5. Cell packing diagram of 2 looking along the a axis.
to display strong blue fluorescence emissions at room tem-
perature, which suggested that they might be good blue-
light-emitted materials. The successful isolation of 1 and
2 suggests that more interesting silver(I) coordination poly-
mers of tetrazolate derivatives can be prepared through
[2 + 3] cycloaddition reactions of other aryl-nitriles with
azide at solvothermal conditions. Studies in this respect
are under way in our laboratory.
4. Experimental
4.1. General
All the chemicals were obtained from commercial
sources and used as received. The IR spectra were recorded
on a Varian 1000 FT-IR (Scimitar Series) spectrometer as
KBr disks (4000–400 cmꢀ1). The elemental analyses for
C, H, and N were performed on a Carlo-Erba EA1110
CHNO-S microanalyzer. All manipulations were carried
out in air. Emission and Excitation spectra were performed
on a Perkin-Elmer LS55 spectrofluorometer with a red-sen-
sitive R928 photomultiplier.
Fig. 6. Emission spectra of 1 (dashed line) and 2 (solid line) in the solid
state at ambient temperature (kex = 345 nm).
further stacks with its neighboring chains into a 2D net-
work through the p–p interactions between tetrazolyl rings
and between Ag+ and phenyl group or tetrazolyl ring.
Compound 2 has an intriguing 3D non-interpenetrated
supramolecular structure in which a 2D layer with a
(4.82)Ag(4.82)pytta topology combines with its adjacent lay-
ers via interactions of Ag+ ions in one layer with the 4-N
atoms of the pytta ligands in the other. The tetrazolate
ligands in 1 and 2 show l3-1,2,3-tetrazolyl and l3-1,2,4-tet-
razolyl mode, respectively and the Ag(I) center in the struc-
ture of 2 adopts a rare trigonal pyramidal coordination
geometry. In addition, solids 1 and 2 were demonstrated
4.2. Synthesis
Caution. Metal azides may be explosive. At all times,
great care must be taken when handling these materials.
4.2.1. Preparation of 1
A mixture of AgNO3 (0.1699 g, 1.0 mmol), NaN3
(0.065 g, 1.0 mmol), benzonitrile (0.2578 g, 2.5 mmol),

344
Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
Table 2
water (2.0 ml) and methanol (5 ml) was stirred for five min-
utes in air and then transferred into a 15 ml Teflon-lined
reactor and then sealed. The reactor was heated in an oven
to 150 ꢁC for 67 h and then cooled to room temperature at
a rate of 5 ꢁC hꢀ1. The brown plate crystals were elutriated
with methanol several times and dried in air. Yield:
0.1729 g (68.3%). Anal. Calcd. for C7H5AgN4: C, 33.23;
H, 1.99; N, 22.14. Found: C, 33.64; H, 1.97; N, 22.05%.
IR (KBr disk, cmꢀ1): 3399 (w), 3064 (w), 3044 (w), 1443
(vs), 1364 (s), 1280 (m), 1138 (m), 1072 (m), 1010 (m),
927 (w), 789 (m), 726 (vs), 688 (vs), 504 (w), 458 (w).
˚
Selected bond lengths (A) and bond angles (ꢁ) for {Ag[l4-(4-pytta)]}n (2)
Ag(1)–N(1)
Ag(1)–N(2A)
C(1)–N(1)
N(1)–N(2)
N(3)–N(4)
2.253(2)
2.352(2)
1.341(3)
1.353(3)
1.345(3)
Ag(1)–N(5C)
Ag(1)–N(4B)
C(1)–N(4)
2.288(2)
2.530(2)
1.342(3)
1.313(3)
N(2)–N(3)
N(1)–Ag(1)–N(5C)
N(5C)–Ag(1)–N(2A)
N(5C)–Ag(1)–N(4B)
C(1)–N(1)–Ag(1)
N(3)–N(2)–Ag(1A)
C(1B)–N(4B)–Ag(1)
C(5C)–N(5C)–Ag(1)
N(1)–C(1)–N(4)
142.83(8)
101.91(8)
97.94(8)
130.11(18)
121.18(17)
125.85(17)
124.81(18)
111.2(2)
N(1)–Ag(1)–N(2A)
N(1)–Ag(1)–N(4B)
N(2A)–Ag(1)–N(4B)
N(2)–N(1)–Ag(1)
N(1)–N(2)–Ag(1A)
N(3B)–N(4B)–Ag(1)
C(4C)–N(5C)–Ag(1)
C(1)–N(1)–N(2)
105.80(8)
88.20(8)
121.66(8)
123.28(16)
129.20(16)
111.47(16)
117.84(18)
104.7(2)
4.2.2. Preparation of 2
Compound 2 was prepared as above starting from
AgNO3 (0.1699 g, 1.0 mmol), NaN3 (0.065 g, 1.0 mmol),
4-cyanopyridine (0.2603 g, 2.5 mmol), water (2.0 ml) and
methanol (5 ml). Yield: 0.0614 g (24.2%) of colorless pris-
matic crystals. Anal. Calcd for C6H4AgN5: C, 28.37; H,
1.59; N 27.57. Found: C, 28.22; H, 1.58; N 27.61%. IR
(KBr disk, cmꢀ1): 3384 (w), 3082 (w), 3031 (w), 1685 (w),
1618 (vs), 1554 (m), 1454 (s), 1418 (s), 1377 (s), 1320 (m),
1225 (s), 1138 (s), 1070 (w), 1005 (s), 843 (vs), 761 (s),
735 (m), 709 (vs), 550 (m), 450 (m).
N(3)–N(2)–N(1)
C(1)–N(4)–N(3)
109.5(2)
105.1(2)
N(2)–N(3)–N(4)
C(5)–N(5)–C(4)
109.5(2)
116.7(2)
Table 3
Crystallographic data for [Ag(l3-phtta)]n (1) and {Ag[l4-(4-pytta)]}n (2)
1
2
Empirical formula
Formula weight
Crystal system
Space group
C7H5N4Ag
253.02
Monoclinic
P21/n
C6H4N5Ag
254.01
Monoclinic
P21/c
4.3. X-ray crystallography
˚
a (A)
6.1015(12)
20.065(4)
6.2962(13)
108.14(3)
732.5(3)
4
7.2691(15)
11.092(2)
8.4619(17)
98.54(3)
674.7(2)
4
˚
b (A)
˚
c (A)
All measurements were performed on a Rigaku Mercury
CCD X-ray diffractometer (3KV, sealed tube) at 153 K,
using graphite monochromated Mo-Ka (k = 0.71070 A).
b (ꢁ)
3
˚
V (A )
˚
Z
A
brown
plate
of
1
with
dimensions
T (K)
153
2.294
488
2.688
7081
1344
153
2.501
488
2.922
6244
1234
1178
109
0.03 · 0.10 · 0.25 mm3 and a colorless prism of 2 with
dimensions 0.17 · 0.28 · 0.40 mm3 were mounted on glass
fibers with grease. Diffraction data were collected at x
mode with a detector distance of 35 mm to the crystal.
Indexing was performed from 6 images, each of which
was exposed for 4 s (for 1) and 2 s (for 2). A total of 720
oscillation images for each were collected in the range
6.09ꢁ < 2h < 50.70ꢁ for 1 and 6.10ꢁ < 2h < 50.68ꢁ for 2.
The collected data were reduced by using the program
CrystalClear (Rigaku and MSC, Ver. 1.3, 2001), and an
absorption correction (multi-scan) was applied, which
resulted in transmission factors ranging from 0.732 to
0.917 for 1 and 0.380 to 0.609 for 2. The reflection data
were also corrected for Lorentz and polarization effects
Table 2.
Dcalc (g cmꢀ3
F (000)
)
l (Mo-Ka, cmꢀ1
Total no. of reflections
No. of unique reflections
)
No. of observed reflections [I > 2.00r (I)] 1175
No. of variables
109
Ra
0.0419
0.0869
1.045
0.0199
0.0472
1.149
wRb
GOFc
3
˚
Largest residual peaks and holes (e/A )
1.311, ꢀ0.620 0.73, ꢀ0.523
Where n = number of reflections and p = total numbers of parameters
refined.
P
P
a
b
c
R ¼ jjF oj ꢀ jF cjj= jF oj.
P
P
2
2 1=2
wR ¼ f wðF 2o ꢀ F c2Þ = wðF 2oÞ g
.
P
2
1=2
GOF ¼ f ½wððF 2o ꢀ F 2c Þ Þ=ðn ꢀ pÞg
.
The crystal structures of 1 and 2 were solved by direct
methods [41], and expanded using Fourier techniques
[42]. All non-hydrogen atoms were refined anisotropically,
and all other hydrogen atoms were placed in geometrically
idealized positions (C–H = 0.97 A for phenyl groups)
and constrained to ride on their parent atoms with
Acknowledgements
This work was financially supported by the NNSF (No.
20525101), the NSF of Jiangsu Province (No. BK2004205),
the Specialized Research Fund for the Doctoral Program
of Higher Education (No. 20050285004), and the State
Key Laboratory of Coordination Chemistry of Nanjing
University and the Qin-Lan Project of Jiangsu Province
in China. The authors also thank Prof. Zhong-Ni Chen
of FJIRSM for his assistance in the measurement of lumi-
nescent properties of the title compounds.
˚
Uiso(H) = 1.2Ueq(C). All the calculations were performed
on
a
Dell workstation using the CrystalStructure
crystallographic software package (Rigaku/MSC, Ver.
3.60, 2004). Important crystal data and collection sand
refinement parameters for 1 and 2 are summarized in
Table 3.

Y. Chen et al. / Journal of Molecular Structure 875 (2008) 339–345
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