M. Tabatabaee et al. / Polyhedron 30 (2011) 1114–1119
1115
based on the Cr(III) ion and never on any other metal ions.
molecules, hydroxide ions, to the N2 and N6 atoms, and to the
amine group of 3-amino-1,2,4-triazole were found in difference
Fourier maps. The distance between the water or hydroxide oxy-
gen atoms and the corresponding hydrogen atoms was restrained
to the average value of 0.82 Å using SHELXL-97 DFIX instruction, while
the distance between the nitrogen atoms and the corresponding
hydrogen atoms was restrained to the average value of 0.86 Å
using the same instruction. The isotropic Uiso(H) values for all
hydrogen atoms were fixed at the same time (Uiso(H) = 1.2Ueq(O)
for hydrogen atoms belonging to O atoms and Uiso(H) = 1.2Ueq(N)
for those belonging to N atoms).
Furthermore, there are only two examples of complexes with
ꢁ
[
Cr(dipic)
2
]
anion which also contain co-crystallized neutral mol-
ecule (dipicolinic acid in both cases) [16,17]. Our compound 1 con-
tains a co-crystallized neutral complex [Cr(H O)(dipic)( -OH)]
25], rather than just an organic molecule, for the first time. Finally,
2
l
2
[
there are two different coordination environments (although both
octahedral) for Cr(III) ions in complex anion and in co-crystallized
neutral complex, which is amazing since both anionic and neutral
complex are based on the same ligand.
Calculations were performed with SHELXS-97 [29], SHELXL-97 [29]
and PLATON [30]. The molecular graphics were done with ORTEP-3
2
. Experimental
[
31] and MERCURY (Version 2.3) [32].The crystal parameters, data col-
2.1. Materials and instrumentation
lection and refinement results for 1 are summarized in Table 1.
All purchased chemicals were of reagent grade and used with-
3
. Results and discussion
out further purification. IR spectra were recorded using FTIR Spec-
ꢁ1
tra Bruker Tensor 27 spectrometer (KBr pellets, 4000–400 cm ).
Absorption spectra were recorded on a Shimadzu Model 160-A
UV–VIS spectrophotometer with a 1-cm quartz cell. TGA/DTA mea-
3.1. Crystal structure
ꢁ1
ORTEP-3 view of the molecular structure of 1 is depicted in Fig. 1.
surements were performed at heating rate of 10 °C min in the
ꢁ1
The crystal structure of 1 is shown in Fig. 2. Some selected bond
distances and angles are listed in Table 2, and the hydrogen bonds
geometry in Table 3.
temperature range of 25–800 °C, under argon flow of 20 mL min
on instrument Rheometrics STA 1500. Elemental analyses were
performed using a Costech ECS 4010 CHNS analyzer.
The compound 1 is built up of a complex [Ag(atr)
2
][Cr(dipic)
2
],
co-crystallized dinuclear complex [Cr(H O)(dipic)( -OH)]
2
l
2
and of
2
.2. Preparation of {[Ag(atr)
2
][Cr(dipic)
2
]}
2
ꢀ[Cr(H
2
O)(dipic)(l-
co-crystallized water molecules. The first complex consists of a
complex cation and anion, while the second is neutral. In the com-
plex cation (Fig. 1a), silver(I) ion is coordinated by two neutral
monodentate 3-amino-1,2,4-triazole molecules, bound via endocy-
clic N atoms, in a linear fashion [\N1–Ag1–N5, 175.2(1)°]. In the
complex anion (Fig. 1b), the chromium(III) ion is octahedrally coor-
dinated by two perpendicular O,N,O-tridentate dipicolinate ligands
OH)] O (1)
2
ꢀ4H
2
Pyridine-2,6-dicarboxylic acid (0.167 g, 1 mmol) and NaOH
0.08 g, 2 mmol) were dissolved in deionized water (15 mL) and
(
stirred for 30 min at room temperature. In a separate beaker
CrCl O (0.266 g, 1 mmol) was dissolved in water (10 ml) and
ꢀ6H
then AgNO (0.510 g, 3 mmol) was added. A precipitate of AgCl
was formed and filtered and then 3-amino-1H-1,2,4-triazole
0.084 g, 1 mmol) was added into the clear filtrate. This mixture
3
2
3
(
bound via pyridine N and two carboxylate O atoms), each forming
two five-membered chelate rings. Coordinated pyridine N atoms
are situated in trans position [\N11–Cr2–N10, 174.7(1)°]. In the
(
was added into the solution of pyridine-2,6-dicarboxylic acid and
NaOH. Reaction mixture was placed in a Parr-Teflon lined stainless
steel vessel, sealed and heated at 130 °C for 8 h. It was gradually
cooled to room temperature and then kept at 4 °C until the purple
crystals suitable for X-ray diffraction were obtained. Yield: 0.118 g
Table 1
Crystal data and details of the structure determination for 1.
Compound
Formula
1
(
14%, based on AgCl). Anal. Calc. for C50
H
48Ag
2
Cr
4
N
22
O
32: C, 31.70;
~,
cm ): 3394, 3157 (b), 1681 (s), 1648 (s), 1633 (s), 1437 (m),
C
50 2 4 22 32
H48Ag Cr N O
H, 2.53; N, 16.27. Found: C, 32.4; H, 2.34; N, 16.59%.IR (KBr) (
t
M
r
1892.84
ꢁ1
Color and habit
Crystal system, space group
Crystal dimensions (mm )
a (Å)
b (Å)
c (Å)
purple, prism
triclinic, P1
ꢀ
1
7
3
388 (s), 1370 (m), 1336 (s), 1273 (m), 1088 (m), 944 (s), 755 (s),
18, 536 (m), 429 (s). UV–Vis (aqueous solution) (k, nm): 225,
04, 551.
3
0.49 ꢂ 0.23 ꢂ 0.20
7.7636(2)
13.1739(5)
17.5441(5)
110.858(3)
90.595(2)
98.101(2)
1656.47(9)
1
a
(°)
b (°)
(°)
2
.3. Single-crystal structure determination
c
Suitable single crystal of 1 was selected and mounted in air onto
3
V (Å )
thin glass fibre. The data collection for 1 was carried out by Oxford
Diffraction Xcalibur four-circle kappa geometry diffractometer
with Xcalibur Sapphire 3 CCD detector, using a graphite monochro-
Z
D
l
calc (g cmꢁ3)
1.897
1.323
ꢁ
1
(mm
)
h Range for data collection (°)
h, k, l range
Scan type
3.74–27.00
mated Mo K
a (k = 0.71073 Å) radiation, and by applying the CRYSALIS
ꢁ9:9, ꢁ16:16, ꢁ22:22
Software system, Version 171.32.29 [28] at room temperature
x
(
296 K). Data reduction has been done by the same program [28].
The X-ray diffraction data have been corrected for Lorentz-
Number of measured reflections
Number of independent reflections (Rint
Number of observed reflections, I P 2r(I)
36152
7176 (0.05)
5013
)
polarization factor and scaled for absorption effects by multi-scan.
The structure was solved by direct methods. Refinement procedure
by full-matrix least squares methods based on F values against all
reflections has been performed including anisotropic displacement
parameters for all non-H atoms.
Number of refined parameters
535
a
b
R , wR [I P 2
R, wR [all data]
Goodness of fit on F , S
Maximum, minimum electron density (e Åꢁ3)
r
(I)]
0.0345, 0.0750
0.0593, 0.0799
0.898
1.08, ꢁ0.47
2
2
c
The position of hydrogen atoms belonging to the carbon atoms
a
b
c
R =
wR = [
S = [w(F
R
||F
R
o
| ꢁ |F
c
||/
R
) /
|F
R
o
|.
w(F 2) ]1/2.
o
Csp2 was geometrically optimized applying the riding model
(
2
2
2
2
(F
o
ꢁ F
c
2
2 2
) /(Nobs ꢁ Nparam)]1/2
R
o
ꢁ F
c
.
0.93 Å; Uiso(H) = 1.2Ueq(C)). Hydrogen atoms belonging to water