Synthesis and characterization of Co(II) and Ni(II) complexes of 2,5-diphenyl-3,4-bis(2-pyridyl)-cyclopentadienone (L). X-ray crystal structures of CoLCl2·0.5CH3CN and NiLBr2·CHCl3

Article abstract of DOI:10.1016/j.poly.2009.11.020

The preparation and properties of [M(chelate)X₂] complexes are reported, where M = Co(II) or Ni(II), chelate = 2,5-diphenyl-3,4-bis(2-pyridyl)cyclopentadienone and X = Cl or Br. These complexes have been characterized by elemental analyses and

Full text of DOI:10.1016/j.poly.2009.11.020

Polyhedron 29 (2010) 985–990
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and characterization of Co(II) and Ni(II) complexes of
2,5-diphenyl-3,4-bis(2-pyridyl)-cyclopentadienone (L). X-ray crystal structures
of CoLCl2ꢀ0.5CH3CN and NiLBr2ꢀCHCl3
b
a
a
a
Mehdi Amirnasr a, , Vratislav Langer , Ahmad Amiri , Shadpour Mallakpour , Farzaneh Afshar
*
a Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran
b Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 June 2009
Accepted 26 November 2009
Available online 1 December 2009
The preparation and properties of [M(chelate)X2] complexes are reported, where M = Co(II) or Ni(II), che-
late = 2,5-diphenyl-3,4-bis(2-pyridyl)cyclopentadienone and X = Cl or Br. These complexes have been
characterized by elemental analyses and spectroscopic methods. The crystal and molecular structures
of CoLCl2ꢀ0.5CH3CN (1) and NiLBr2ꢀCHCl3 (4) have been determined by X-ray crystallography. Compound
ꢀ
(1) crystallizes in the triclinic space group P1, different from that of CoLCl2 (monoclinic space group P21/c)
Keywords:
Chelates
Cobalt(II)
Nickel(II)
Pseudotetrahedral
Crystal structures
that we have reported previously. Compound (4) crystallizes in the monoclinic space group P21/n. Both
CoLCl2 and NiLBr2 complexes are pseudo-tetrahedral, and utilization is made of the electronic and vibra-
tional spectra in the structural diagnosis of CoLBr2 and NiLCl2.
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
thermal dehydration of its white diol precursor, LH2(OH)2, over sil-
ica gel as reported elsewhere [9]. Electronic spectra in solution
The formation and characterization of complexes of the type
MLX2, where M = Co(II), Ni(II), L = ligands formed by the linkage of
two pyridine residues, in the ortho position, by various groups such
as –CH2CH2–, –SS–, –N@N–, –NH–, etc., and X = Cl, Br, I, NCS, have
been the subject of considerable interest [1–8]. The ligands show
unusual adaptability to different environments and result in the for-
mation of structurally different complexes depending on their
modes of coordination and the conformations of the coordinated L
ligands. Steric effects and internal strain are expected to be different
in these complexes and, depending on the structures of 1,2-di(20-
pyridyl) ligands and the stability of their compounds, synthetic
conditions may vary from one group of complexes to another. In this
paper we report the synthesis and characterization of a series of new
MLX2 complexes with internal strain imparted by the structurally
rigid L ligand, Scheme 1. We also report the X-ray structural analysis
of CoLCl2ꢀ0.5CH3CN and NiLBr2ꢀCHCl3 complexes.
were recorded on a JASCO V-570 spectrophotometer. IR spectra
were recorded as KBr pellets on a FT-IR JASCO 680 PLUS instru-
ment. Elemental analyses were performed by using a Perkin–Elmer
2400II CHNS/O analyzer.
2.2. Synthesis of complexes
2.2.1. CoLCl2ꢀ0.5CH3CN (1)
A solution of the ligand L (0.193 g, 0.5 mmol) in chloroform
(40 mL) was added to a suspension of CoCl2 (0.091 g, 0.7 mmol)
in chloroform (10 mL). The reaction mixture was stirred at room
temperature for 3 h to give a cherry red solution. The unreacted
CoCl2 was removed by filtration and the filtrate was left in the
hood for two days to give dark red crystals of CoLCl2 in 95% yield
(based on the ligand L). The product was recrystallized from a mix-
ture of chloroform–acetonitrile (20:1 v/v) to give dark crystals of
X-ray quality which were washed and dried in air. Anal. Calc. for
C27H18Cl2CoN2Oꢀ0.5CH3CN: C, 62.65; H, 3.66; N, 6.52. Found: C,
2. Experimental
62.4; H, 3.60; N, 6.60%. IR (KBr pellets,
(C@N py) and (C@C aromatic) 1599, 1566, 1493, 1473,
1440(m); (C„N acetonitrile) 2250(w).
m m(C@O) 1715(s);
/cmꢁ1):
2.1. Materials
m
m
m
Solvents and starting materials were obtained from Fluka and
Aldrich and used as received. The red ligand L was prepared by
2.2.2. CoLBr2 (2)
This complex was prepared as described for compound 1 except
that stoichiometric amounts of CoBr2 and L (0.5 mmol) were used
* Corresponding author. Tel.: +98 311 3912351; fax: +98 311 3912350.
E-mail address: amirnasr@cc.iut.ac.ir (M. Amirnasr).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.11.020

986
M. Amirnasr et al. / Polyhedron 29 (2010) 985–990
was obtained as a red purple powder in 70% yield (based on the li-
gand L). The complex was recrystallized from dichloromethane and
dried in air. Anal. Calc. for C27H18Cl2NiN2O (516.05): C, 62.84; H,
3.52; N, 5.43. Found: C, 62.70; H, 3.40; N, 5.32%. IR (KBr pellets,
O
m
/cmꢁ1):
m(C@O) 1717(s); m(C@N py) and m(C@C aromatic) 1599,
1567, 1494, 1473, 1442(m).
N
X
M
N
2.2.4. NiLBr2ꢀCHCl3 (4)
X
This complex was prepared as described for compound 1 except
that stoichiometric amounts of NiBr2 and L (0.5 mmol) were used
M
Co
X
Table 2
1
Cl
Br
Cl
Br
Electronic absorption spectral data for 1–4 and the red L, k/nm (
e
/L molꢁ1 cmꢁ1).
Red L
2
3
4
CoLCl2 (1)
CoLBr2 (2)
NiLCl2 (3)
NiLBr2 (4)
Ni
254 (24324)
287 (12622)
360 (3250)
510 (1488)
569 (1183)
610 (795)
650 (465)
985 (19)
255 (21830)
288 (12341)
360 (3162)
512 (1625)
594 (1112)
626 (895)
664 (626)
1020 (24)
1400 (112)
260 (17860)
292 (11800)
360 (2850)
521 (1504)
852 (10)
255 (18700)
296 (14000)
360 (2540)
526 (1700)
888 (26)
258(20090)
324(5012)
492(1167)
Scheme 1. Structural formulas of the complexes.
984 (44)
1007 (51)
and the reaction mixture was stirred for 12 h. Red purple needle
like crystals of CoLBr2 were obtained in 73% yield (based on the li-
gand L) from the final filtrate after two days. The product was
recrystallized from chloroform and dried in air. Anal. Calc. for
C27H18Br2CoN2O: C, 53.59; H, 3.00; N, 4.63. Found: C, 53.90; H,
1340 (73)
3.00; N, 4.40%. IR (KBr pellets,
m
/cmꢁ1): 3050
m(CH);
m
(C@O)1718(s); (C@N py) and (C@C aromatic) 1595, 1560,
m
m
1490, 1470, 1440(m).
2.2.3. NiLCl2 (3)
This complex was prepared as described for compound (1) ex-
cept that NiCl2 was used in excess (Ni/Lffi2, 1/0.5 mmol), and the
reaction mixture in chloroform was stirred for 60 h. The product
Table 1
Crystal and structure refinement data for CoLCl2ꢀ0.5CH3CN (1) and NiLBr2ꢀCHCl3 (4).
Compound
1
4
Empirical formula
Formula weight
T (K)
C56H39Cl4Co2N5O2 C28H19Br2Cl3NiN2O
1073.58
153(2)
724.33
153(2)
Crystal system
Crystal size (mm)
Space group
a (Å)
b (Å)
c (Å)
triclinic
monoclinic
0.94 Â 0.22 Â 0.08 0.68 Â 0.18 Â 0.17
ꢀ
Fig. 1. UV–Vis spectrum of CoLBr2 (400–200 nm, 7.1 Â 10ꢁ5 M; 800–400 nm,
8.0 Â 10ꢁ4 M; 1600–800 nm, 8.8 Â 10ꢁ3 M) in CH2Cl2.
P21/n
P1
8.7243(4)
16.6040(8)
17.7740(9)
77.328(1)
84.773(1)
77.157(1)
2446.7(2)
2, 1.457
7.0124(14)
21.595(4)
18.916(4)
90
96.041(4)
90
2848.7(10)
4, 1.689
3.793
a
(°)
b (°)
c
(°)
V (Å3)
Z, Dcalc (g cmꢁ3
l
)
(mmꢁ1
)
0.945
F(0 0 0)
1096
1432
h Range for data collection (°)
Index ranges
2.35–33.08
ꢁ13 6 h 6 13
ꢁ25 6 k 6 25
ꢁ27 6 l 6 26
44678
2.17–28.67
ꢁ9 6 h 6 9
ꢁ29 6 k 6 29
ꢁ25 6 l 6 25
39897
Reflections collected
Independent reflections
Rint
17336
0.0226
7291
0.0524
Completeness to h (°)
Maximum and minimum
transmission
31.00, 99.5%
0.9282, 0.7153
28.67, 99.3%
0.5648, 0.1983
Data/parameters
17336/623
1.002
7291/334
1.008
Good-of-fit on F2
R1/wR2 for observed reflection
0.0315/0.0822
0.0401/0.0945
[I > 2r(I)]
R1/wR2 for all data
0.0419/0.0873
0.0623/0.1074
Largest resolution peak/
0.566/ꢁ0.272
1.037/ꢁ0.692
Fig. 2. UV–Vis spectrum of NiLBr2 (700–200 nm, 1.5 Â 10ꢁ4 M; 1600–700 nm,
2.45 Â 10ꢁ2 M) in CH2Cl2.
hole(e Åꢁ3
)

M. Amirnasr et al. / Polyhedron 29 (2010) 985–990
987
and the reaction mixture was stirred for 12 h. Red purple needle
like crystals of NiLBr2 were obtained in 73% yield (based on the li-
gand L) from the final filtrate after two days. The product was
recrystallized from chloroform and dried in air. Anal. Calc. for
C27H18Br2NiN2OꢀCHCl3: C, 46.43; H, 2.64; N, 3.87. Found: C,
46.90; H, 2.60; N, 3.80%. IR (KBr pellets,
m
/cmꢁ1):
m
(C@O)
1717(s); m(C@N py) and m(C@C aromatic) 1599, 1567, 1493, 1473,
1442(m).
2.3. X-ray crystallography
Data were collected on a Siemens SMART CCD diffractometer
equipped with LT-2A low temperature device, using graphite-
monochromated Mo K
reciprocal lattice was scanned by 0.3° steps in
a
(k = 0.71073 Å) radiation. A full sphere of
with
x
a
crystal-to-detector distance of 3.97 cm. Preliminary orientation
matrices were obtained from the first frames using SMART [10].
The frames were integrated using the preliminary orientation
matrices which were updated every 100 frames. Final cell param-
eters were obtained by the refinement on the positions of 7108 and
Fig. 3A. Numbering of molecule 1A together with atomic displacement ellipsoids
drawn at 50% probability level.
6109 (for 1 and 4, respectively) reflections with I > 2r(I), after inte-
gration of all the frames using SAINT [10]. The data were empirically
corrected for absorption and other effects using SADABS [11]. The
structures were solved by direct methods and refined by the full-
matrix least-squares method on F2 data using the SHELXTL [12]. All
non-H atoms were refined anisotropically. The H atoms were con-
strained to idealized geometries and refined isotropically. The crys-
tallographic and refinement data are summarized in Table 1.
3. Results and discussion
3.1. Synthesis of complexes
The MLX2 complexes were prepared by the reaction of the
appropriate metal halide with the bidentate ligand L (Scheme 1).
The synthesis of CoLX2 and NiLX2 complexes were carried out in
chloroform. The procedure reported in the literature for the syn-
thesis of related cobalt and nickel complexes in ethanol [1] proved
to be unsuccessful for the preparation of CoLX2 and NiLX2. This is
due to the steric factors imposed by the more rigid structure of
the ligand L as compared to the related ligands in Ref. [1]. From
a structural point of view the N–N bite of the chelating ligands is
controlled by the linkage between the two pyridine rings. Further-
more, the kinetic chelate strain effect [13] which arises from the
Fig. 3B. Numbering of molecule 1B together with atomic displacement ellipsoids
drawn at 50% probability level.
Table 3
0
Selected bond distances (AÅ), bond and torsion angles (°) in 1 and 4.
1A
1B
4
Bond distances
Co1A–N21A
Co1A–N31A
Co1A–Cl1A
2.0270(11)
2.0297(10)
2.2328(4)
2.2166(3)
Co1B–N21B
Co1B–N31B
Co1B–Cl1B
Co1B–Cl2B
2.0483(10)
2.0330(10)
2.2223(4)
2.2248(4)
Ni–N21
Ni–N31
Ni–Br1
Ni–Br2
2.008(2)
2.018(3)
2.3745(6)
2.3546(6)
Co1A–Cl2A
Bond angles
N21A–Co1A–N31A
N21A–Co1A–Cl2A
N31A–Co1A–Cl2A
N21A–Co1A–Cl1A
N31A–Co1A–Cl1A
Cl2A–Co1A–Cl1A
93.71(4)
N21B–Co1B–N31B
N21B–Co1B–Cl2B
N31B–Co1B–Cl2B
N21B–Co1B–Cl1B
N31B–Co1B–Cl1B
Cl2B–Co1B–Cl1B
93.93(4)
N21–Ni–N31
N21–Ni–Br2
N31–Ni–Br2
N21–Ni–Br1
N31–Ni–Br1
Br2–Ni–Br1
94.84(9)
112.64(3)
114.14(3)
108.92(3)
109.51(3)
115.726(15)
112.64(3)
114.26(3)
109.57(3)
111.10(3)
113.682(15)
110.58(7)
111.28(7)
104.50(7)
106.19(7)
125.08(2)
Torsion angles
Co1A–N21A–C22A–C3A
Co1A–N31A–C32A–C4A
N21A–C22A–C3A–C4A
N31A–C32A–C4A–C3A
C22A–C3A–C4A–C32A
ꢁ3.80(15)
8.98(14)
55.83(16)
ꢁ59.51(15)
0.71(17)
Co1B–N21B–C22B–C3B
Co1B–N31B–C32B–C4B
N21B–C22B–C3B–C4B
N31B–C32B–C4B–C3B
C22B–C3B–C4B–C32B
ꢁ9.23(14)
9.71(14)
61.54(15)
ꢁ59.51(15)
ꢁ2.10(17)
Ni–N21–C22–C3
Ni–N31–C32–C4
N21–C22–C3–C4
N31–C32–C4–C3
C22–C3–C4–C32
ꢁ6.1(3)
1.3(3)
55.5(4)
ꢁ53.6(4)
1.3(4)

988
M. Amirnasr et al. / Polyhedron 29 (2010) 985–990
increase in M–N bond distance and the solvent interaction with
metal ions are both operative in the process of complex formation.
In ethanol (as well as in other polar and coordinating solvents), it is
likely that the cobalt and nickel complexes exist in multiple equi-
libria with strongly solvated species that compete with MLX2 for-
mation. The solubility and higher stability of these complexes in
chloroform, make it ideal to run the reactions in this solvent.
3.2. Spectral characterization
The IR spectra of the complexes containing pyridine residues
have been studied and used by other researchers to determine
the coordination mode for the pyridine rings [14]. The MLX2 com-
plexes have been divided into three series according to their infra-
red spectra. The infrared spectra of the series I in which the
bidentate ligand has a cis conformation is more simple than others.
This is indicative of the presence of a ligand having both pyridine
residues coordinated to the metal in such a form that the pyridine
groups are chemically equivalent.
The solid-state IR spectra of the cobalt and nickel complexes
display several features that are supportive of a common coordina-
tion mode for the ligand L. The ketone C@O stretching mode ob-
served at 1715 cmꢁ1 in the free ligand L, is observed as a single
sharp band at about 1717 cmꢁ1 in all four complexes. The pyridine
C@N and aromatic C@C stretching modes are shifted to higher fre-
quencies by 5–15 cmꢁ1 in the complexes relative to the free ligand.
Additional shifts are expected for the ring breathing mode which
occurs at 990 cmꢁ1 in the free ligand and appears at 1020–
1025 cmꢁ1 in the IR spectra of the complexes.
Fig. 4. Numbering scheme of molecule 4 with atomic displacement ellipsoids
drawn at 50% probability level.
Fig. 5. Projection of the structure of 1 along the a-axis. Coordination tetrahedra of Co atoms are shown in blue. (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)

M. Amirnasr et al. / Polyhedron 29 (2010) 985–990
989
The electronic absorption spectral data of the ligand L and its
metal complexes are listed in Table 2. The ligand is a deep red solid
and its solution in acetonitrile has a strong absorption at 492 nm
(e
= 1167) assigned to a n ?
p* transition arising from the interac-
tion of the ketone oxygen lone pairs with the
p
system of the mol-
ecule. This transition is slightly red shifted when the pyridines are
protonated (512 nm) or coordinated to the metal ions (510–
526 nm). The absorption at wavelengths less than 400 nm in the li-
gand are assigned to
p ? p* transitions of the rings. Additional CT
transitions are expected for the metal complexes which appear be-
low 400 nm. The ligand field transitions for CoLCl2 (1) and CoLBr2
(2) complexes (Fig. 1) include the intense multicomponent bands
in the near-infrared region (6000–11000 cmꢁ1) and in the visible
region (14500–22000 cmꢁ1) as expected for a pseudotetrahedral
stereochemistry [15].
The electronic spectra of nickel complexes, NiLCl2 (3) and NiL-
Br2 (4), (Table 2) is consistent with a pseudotetrahedral structure
(Fig. 2). The broad absorption bands near 7000 cmꢁ1 (components
of 3T2) and 10000 cmꢁ1 (3A2) and the shoulder at 17000 cmꢁ1
(components of 3T1(P)) which overlaps with the n ?
p* of the li-
gand are in accord with a C2v symmetry of these complexes [15].
On the basis of the striking similarity of the spectroscopic proper-
ties of CoLBr2 (2) and NiLCl2 (3) complexes with those of CoLCl2 (1)
and NiLBr2 (4) for which the X-ray structures have been deter-
mined (vide infra) a similar structure can also be inferred for (2)
and (3) complexes.
3.3. Crystal and molecular structures of (1) and (4)
The crystallographic and refinement data are summarized in
Table 1 and the selected bond distances, bond and torsion angles
are given in Table 3. The molecular structures of (1) and (4) are
illustrated in Figs. 3A, 3B and 4, respectively with metal atoms
coordinated by the bidentate bis(2-pyridyl) ligand and two halo-
gen atoms.
Fig. 6. Projection of the structure of 4 along the a-axis. Coordination tetrahedra of
Ni atoms are shown in green. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
membered ring is highly puckered with endocyclic torsion angles
given in Table 3.
The structure of CoLCl2ꢀ0.5CH3CN (1) consists of two, chemically
identical but conformationally different molecules in the asym-
metric unit. A highly puckered seven-membered chelation ring is
formed with endocyclic torsion angles presented in Table 3. The
The packing of both compounds in the crystals is very different
and it is shown in Fig. 5 and 6. In crystal structure of (1), there is
apart from weak hydrogen bond of C–Hꢀ ꢀ ꢀCl, C–Hꢀ ꢀ ꢀN and C–
0
0
average Co–N [2.034(10) ÅA] and Co–Cl [2.224(7) AÅ] bond distances
and the N–Co–N [93.82(16)°] and Cl–Co–Cl [114.7(14)°] bond
angles conform to those reported for the related complex [di-
chloro(2,5-diphenyl-3,4-di-2-pyridyl-1H-pyrrole-N,N0)cobalt(II)] [2].
The structural parameters such as the crystal system, space group,
unit cell dimensions, and the crystal packing of compound (1) (tri-
Hꢀ ꢀ ꢀO types a quite strong
p–p interaction present between the
aromatic phenyl rings C41Aꢀ ꢀ ꢀC46A and C41Bꢀ ꢀ ꢀC46B (symmetry
operation: 2 ꢁ x, 1 ꢁ y, 1 ꢁ z) with a centroid–centroid distance
of 3.7185(8) Å. In crystal structure of (2), there are weak H-bond
interactions of type C–Hꢀ ꢀ ꢀBr present, but no
p–p interaction was
interaction between the chloro-
observed there. Instead, a C–Hꢀ ꢀ ꢀ
p
ꢀ
clinic, space group P1 and Z = 2) are different from those of CoLCl2
form molecule and the phenyl ring C41ꢀ ꢀ ꢀC26, with hydrogen atom
distance to the centroid of this ring being 2.83 Å, has been
recognized.
(monoclinic, space group P21/c, Z = 4), that we have reported previ-
ously [16]. Compound (1) involves solvent molecules in its unit
cell, which is apparently the source of these structural differences.
It is interesting to compare the structure of CoLCl2 (1) with that
of the unchelated analogue, Co(3-pic)2Cl2 [17]. The two structures
are similar, with pseudotetrahedral cobalt coordination. However,
the N–Co–N angle is 104.19(8)° in the unchelated complex
whereas it is 93.71(4)° and 93.93(4)° in the chelate CoLCl2. This
large deviation is presumably the source of some strain in the
structure of the complex, leading to the release of the L ligand in
strongly coordinating solvents.
4. Conclusion
The present study revealed tetrahedral geometry around Co(II)
and Ni(II), where the metal atoms are coordinated by the bidentate
bis(2-pyridyl) ligand and two halogen atoms. These complexes
proved to be unstable in strongly coordinating solvents, presum-
ably due to the strain imparted by the structurally rigid L ligand.
A convenient method of synthesis for the preparation of these
complexes in chloroform was concluded.
The NiLBr2 complex (4) also adopts a pseudotetrahedral struc-
ture where the tetrahedron is somewhat distorted by a small N–
Ni–N angle being 94.84(9)°. The Br–Ni–Br angle has opened up to
125.08(2)°. The Ni–N distances ranging from 2.008(2) to
Supplementary data
0
2.018(3) ÅA are considered normal and comparable to those for (1)
and relate0d complexes [2,16]. The average Ni–Br distance of
2.365(14) ÅA agrees well with normal Ni–Br bond distances in the
related complex, Ni(Phca2en)Br2 [18]. As in CoLCl2 (1), the seven
CCDC 661283 and 661284 contain the supplementary crystallo-
graphic data for 1 and 4. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the

990
M. Amirnasr et al. / Polyhedron 29 (2010) 985–990
[5] W.M. Teles, M.V. Marinho, M.I. Yoshida, N.L. Speziali, K. Krambrock, C.B.
Pinheiro, N.M. Pinhal, A.A. Leitãoa, F.C. Machado, Inorg. Chim. Acta 359 (2006)
4613.
[6] S. Delgado, A. Barrilero, A. Molina-Ontoria, M.E. Medina, C.J. Pastor, Reyes
Jiménez-Aparicio, J.L. Priego, Eur. J. Inorg. Chem. (2006) 2746.
[7] M. Wriedt, I. Jess, C. Näther, Acta Crystallogr., Sect. E 64 (2008) m83.
[8] C. Zhang, L. Yuan, J.-Y. Liu, W. Xu, Acta Crystallogr., Sect. E 65 (2009) o1213.
[9] M. Amirnasr, A. Gorji, Thermochim. Acta 354 (2000) 31.
[10] SMART and SAINT: Area Detector Control and Integration Software, Bruker AXS
Inc., Madison, WI, USA, 2003.
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@
ccdc.cam.ac.uk.
Acknowledgement
Partial support of this work by the Isfahan University of Tech-
nology Research Council is gratefully appreciated.
[11] G.M. Sheldrick, SADABS: Program for Empirical Absorption Correction for Area
Detectors, Version 2.10, University of Göttingen, Germany, 2003.
[12] G.M. Sheldrick, SHELXTL: Structure Determination Programs (Version 6.14), Acta
Crystallogr., Sect. A 64 (2008) 112.
References
[13] T.S. Turan, D.B. Rorabacher, Inorg. Chem. 11 (1972) 288.
[14] D.A. Baldwin, A.B.P. Lever, R.V. Parish, Inorg. Chem. 8 (1969) 107.
[15] A.B.P. Lever, Inorganic Electronic Spectroscopy, second ed., Elsevier, The
Netherlands, 1984. p. 497 and 531.
[16] A.D. Khalaji, M. Amirnasr, J.-C. Daran, Acta Crystallogr., Sect. E 62 (2006) m687.
[17] D. Wyrzykowski, E. Styczen´ , Z. Warnke, Transition Met. Chem. 31 (2006) 860.
[18] M. Amirnasr, A.H. Mahmoudkhani, A. Gorji, S. Dehghanpour, H.R. Bijanzadeh,
Polyhedron 21 (2002) 2733.
[1] M. Keeton, A.B. Lever, Inorg. Chem. 10 (1971) 47.
[2] B. Viossat, N.-H. Dung, J. Lehuede, J.M. Vierfond, Acta Crystallogr., Sect. C 50
(1994) 211.
[3] Y.-Z. Zhu, Z.-P. Li, J.-A. Ma, F.-Y. Tang, L. Kang, Q.-L. Zhou, A.S.C. Chan,
Tetrahedron: Asymmetry 13 (2002) 161.
[4] A. Panunzi, V. De Felice, N. Fraldi, G. Roviello, F. Ruffo, Inorg. Chem. Commun. 8
(2005) 1049.