Synthesis, spectroscopic studies and crystal structures of ReI(CO)3(NN)Cl complexes with N,Nae-bis(substituted benzylidene)ethane-1,2-diamine Schiff base ligands

Article abstract of DOI:10.1007/s11243-009-9298-5

Four new Re(I) tricarbonyl-diimine complexes were prepared by reaction of Re(CO)₅Cl with N,Nae-bis(substituted benzylidene)ethane-1,2-diamine Schiff base ligands. These compounds were characterized by physico-chemical methods, and their crystal

Full text of DOI:10.1007/s11243-009-9298-5

Transition Met Chem (2010) 35:81–87
DOI 10.1007/s11243-009-9298-5
Synthesis, spectroscopic studies and crystal structures
of ReI(CO)3(NN)Cl complexes with N,N0-bis(substituted
benzylidene)ethane-1,2-diamine Schiff base ligands
•
Valiollah Mirkhani Reza Kia
•
•
Dalibor Milic Akbar Rostami Vartooni
•
´
Dubravka Matkovic-Calogovic
ˇ
´
´
Received: 16 August 2009 / Accepted: 20 October 2009 / Published online: 6 November 2009
Ó Springer Science+Business Media B.V. 2009
Abstract Four new Re(I) tricarbonyl-diimine complexes
were prepared by reaction of Re(CO)5Cl with N,N0-
bis(substituted benzylidene)ethane-1,2-diamine Schiff base
ligands. These compounds were characterized by physico-
chemical methods, and their crystal structures were estab-
lished by X-ray diffraction. The coordination geometry at
the Re atom is that of a distorted octahedron, with three
carbonyl ligands in the facial geometry.
of these complexes. The lowest energy excited state of these
complexes is generally long-lived metal-to-ligand charge
transfer (MLCT). Because of the powerful reductive and/or
oxidative properties in the MLCT state, such complexes can
be find application as photosensitizers, e.g., in solar cells
[6, 7]. Several [Re(CO)3(L)X]0/? complexes, where L is
a-diimine and X is a halide, bridging ligand or some other
monodentate ligand, have been used as electroluminescent
materials in OLED-type devices [8–10]. Modification in the
diimine or axial ligands of these complexes has been used to
tune their spectroscopic, photophysical, photochemical and
electrochemical properties [11, 12].
Introduction
The photochemistry and photophysics of diimine-Re(I)-tri-
carbonyl complexes are well established [1–3]. Their photo-
chemical properties have been utilized for the electrocatalytic
and photocatalytic CO2 reduction to CO [4, 5]. Control or
modulation of the absorption and/or emission energy can
provide a very important tool to modify the catalytic behavior
In this research, synthesis, characterization and crystal
structuresoffourtricarbonylrhenium(I)complexes, [Re(CO)3-
(4-mbzen)Cl], [Re(CO)3(2-mbzen)Cl], [Re(CO)3(4-m’bzen)-
Cl] and [Re(CO)3(3-bbzen)Cl] in which 4-mbzen = N,N0-
bis(4-methoxybenzylidene)ethane-1,2-diamine, 2-mbzen =
N,N0-bis(2-methoxybenzylidene)ethane-1,2-diamine, 4-m’bzen
= N,N0-bis(4-methylbenzylidene)ethane-1,2-diamine and 3-
bbzen = N,N0-bis(3-bromobenzylidene)ethane-1,2-diamine,
are reported.
Electronic supplementary material The online version of this
article (doi:10.1007/s11243-009-9298-5) contains supplementary
material, which is available to authorized users.
V. Mirkhani ꢀ A. R. Vartooni
Experimental
Department of Chemistry, University of Isfahan,
81746-73441 Isfahan, Iran
e-mail: mirkhani@sci.ui.ac.ir
Materials and methods
R. Kia
Organic reagents used for synthesis of the compounds were
obtained from Merck and used as received. The solvents
were dried before use with the appropriate drying reagents.
IR spectra in KBr pellets were recorded on an IR Prestige-21
Department of Chemistry, Science and Research Campus,
Islamic Azad University, Poonak, Tehran, Iran
e-mail: zsrkk@yahoo.com
ˇ
1
´
´
´
D. Milic (&) ꢀ D. Matkovic-Calogovic
Shimadzu FTIR instrument. H NMR spectra were per-
Laboratory of General and Inorganic Chemistry, Department
of Chemistry, Faculty of Science, University of Zagreb,
Horvatovac 102a, HR-10000 Zagreb, Croatia
e-mail: dmilic@chem.pmf.hr
formed on a Bruker Avance DRX500 (500 MHz) spec-
trometer using DMSO-d6 and CDCl3 as solvent and TMS as
the internal reference. UV–Vis spectra were measured on a
123

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Transition Met Chem (2010) 35:81–87
Shimadzu UV-160 spectrophotometer in dichloromethane
solution. Cyclic voltammograms were recorded on a three-
electrode cell containing Ag/AgNO3 (in CH3CN) reference
electrode, a Pt wire counter electrode and a glassy carbon
–CH2–CH2–); 7.04–7.69 (m, 8H, aromatic hydrogens);
8.01 (s, 2H, iminic hydrogens).
[Re(CO)3(4-mbzen)Cl] (1)
working electrode. The complexes were at 2 9 10-4
M
concentration in deaerated CH2Cl2 containing 0.2 M
Bu4NClO4 (TBAP) as a supporting electrolyte. The scans
were recorded at 100 mV/s.
A mixture of Re(CO)5Cl (0.2 g, 0.55 mmol) and 4-mbzen
(0.16 g) in degassed CH2Cl2/toluene (30 mL, 1:2 V/V) was
heated at reflux for 3 h. The solution was concentrated to half
volume, and n-hexane was added to precipitate a yellow
crude material of complex 1. The product was recrystallized
from CH2Cl2/toluene to give pale yellow crystals. FTIR
Synthesis of the Schiff bases and complexes
N,N0-bis(4-methoxybenzylidene)ethane-1,2-diamine
(4-mbzen)
1
(cm-1): mmax 2,016, 1,884 (broad) (CO); 1,630 (C=N). H
NMR (DMSO-d6, d/ppm): 3.84 (s, 6H, 2-(OCH3)); 4.04–
4.07 and 4.16–4.20 (two sets of multiples, 4H, –CH2–CH2–);
7.09–7.11 (d, 4H, aromatic hydrogens); 7.98–8.00 (d, 4H,
aromatic hydrogens); 9.06 (s, 2H, iminic hydrogens).
Ethylendiamine (0.2 mL, 3 mmol) was added to a stirred
solution of 4-methoxybenzaldehyde (6 mmol, 0.75 mL) in
CH2Cl2 (15 mL). The mixture was stirred for 3 h at room
temperature, then the precipitate was filtered off, and the
yellow solid was recrystallized from ethanol. FTIR (KBr,
[Re(CO)3(2-mbzen)Cl] (2)
1
cm-1): mmax 1,639 (C=N). H NMR (CDCl3, d/ppm): 3.62
This complex was synthesized by a procedure similar to 1
using 2-mbzen (0.16 g). FTIR (cm-1): mmax 2,013, 1,902
and 1,889 (CO); 1,630 (C=N). 1H NMR (DMSO-d6, d/ppm):
3.89 (s, 6H, 2-(OCH3)); 4.06–4.10 and 4.26–4.30 (two sets
of multiples, 4H, –CH2–CH2–); 7.06–7.09 (t, 2H, aromatic
hydrogens); 7.15–7.16 (d, 2H, aromatic hydrogens);
7.52–7.56 (m, 2H, aromatic hydrogens); 7.99–8.00 (d, 2H,
aromatic hydrogens); 9.10 (s, 2H, iminic hydrogens).
(s, 6H, 2-(OCH3)); 3.72 (s, 4H, –CH2–CH2–); 6.69–6.71 (d,
4H, aromatic hydrogens); 7.43–7.45 (d, 4H, aromatic
hydrogens); 8.01 (s, 2H, iminic hydrogens).
N,N0-bis(2-methoxybenzylidene)ethane-1,2-diamine
(2-mbzen)
This Schiff base was prepared by a procedure similar to 4-
mbzen using 2-methoxybenzaldehyde (0.82 g). The yellow
solid was recrystallized from ethanol.
[Re(CO)3(4-m’bzen)Cl] (3)
FTIR (KBr, cm-1): mmax 1,634 (C=N). 1H NMR (CDCl3,
d/ppm): 3.61 (s, 6H, 2-(OCH3)); 3.77 (s, 4H, –CH2–CH2–);
6.67–7.74 (m, 8H, aromatic hydrogens); 8.52 (s, 2H, iminic
hydrogens).
This complex was synthesized by a procedure similar to 1
using 4-m’bzen (0.15 g). FTIR (cm-1): mmax 2,019, 1,915
and 1,865 (CO); 1,632 (C=N). 1H NMR (DMSO-d6, d/ppm):
4.05–4.09 and 4.21–4.25 (two sets of multiples, 4H, –CH2–
CH2–); 7.35–7.36 (d, 4H, aromatic hydrogens); 7.83–7.84
(d, 4H, aromatic hydrogens); 9.13 (s, 2H, iminic
hydrogens).
N,N0-bis(4-methylbenzylidene)ethane-1,2-diamine
(4-m’bzen)
This Schiff base was synthesized according to the proce-
dure for 4-mbzen using 4-methylbenzaldehyde (0.7 mL).
The yellow solid was recrystallized from ethanol. FTIR
(KBr, cm-1): mmax 1,639 (C=N). 1H NMR (CDCl3, d/ppm):
2.17 (s, 6H, 2-(CH3)); 3.75 (s, 4H, –CH2–CH2–); 6.98–7.00
(d, 4H, aromatic hydrogens); 7.38–7.40 (d, 4H, aromatic
hydrogens); 8.05 (s, 2H, iminic hydrogens).
[Re(CO)3(3-bbzen)Cl] (4)
The procedure was similar to that for 1, except that 3-bbzen
(0.22 g) was used. FTIR (cm-1): mmax 2,023 and 1,894
(broad) (CO); 1,634 (C=N). H NMR (DMSO-d6, d/ppm):
4.09–4.13 and 4.24–4.28 (two sets of multiples, 4H, –CH2–
CH2–); 7.49–7.52 (t, 2H, aromatic hydrogens); 7.75–7.79
(m, 4H, aromatic hydrogens); 8.18 (s, 2H, aromatic
hydrogens); 9.18 (s, 2H, iminic hydrogens).
1
N,N0-bis(3-bromobenzylidene)ethane-1,2-diamine
(3-bbzen)
Crystal structure determinations
The procedure was similar to that for 4-mbzen, except that
3-bromobenzaldehyde (0.7 mL) was used. The yellow
solid was recrystallized from ethanol. FTIR (KBr, cm-1):
Crystals suitable for X-ray crystallography were grown by
slow evaporation of complexes dissolved in CH2Cl2 and
1
mmax 1,643 (C=N). H NMR (CDCl3, d/ppm): 3.76 (s, 4H,
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Transition Met Chem (2010) 35:81–87
83
Table 1 Crystal data and structure refinement parameters for complexes 1–4
Complex
1
2
3
4
Empirical formula
Formula mass
Crystal size (mm3)
Color
C21H20ClN2O5Re
602.04
C21H20ClN2O5Re
602.04
C21H20ClN2O3Re
570.04
C19H14Br2ClN2O3Re
699.79
0.54 9 0.28 9 0.05
Pale yellow
Triclinic
0.44 9 0.15 9 0.08
Pale yellow
Orthorombic
Pnma
0.50 9 0.28 9 0.06
Pale yellow
Monoclinic
P21/n
0.38 9 0.35 9 0.07
Yellow
Crystal system
Space group
hmax (°)
Monoclinic
P21
ꢀ
P 1
32.2
32.1
30.0
32.1
˚
a (A)
˚
b (A)
7.1355(1)
9.6395(2)
16.6392(4)
106.759(2)
93.201(2)
95.755(2)
1,086.03(4)
2
14.5786(13)
165,115(13)
9.21652(18)
90
10.985(2)
10.551(2)
17.802(2)
90
7.2544(1)
13.9627(2)
11.0109(2)
90
˚
c (A)
a (°)
b (°)
c (°)
90
94.194(5)
90
104.938(2)
90
90
3
˚
V (A )
2,218.6(3)
4
2,057.8(6)
4
1,056.78(3)
2
Z
Dcalc (Mg/m3)
1.841
1.803
1.840
2.199
l (mm-1
)
5.75
5.652
6.07
9.68
F(000)
584
1,168
1,104
656
Index ranges
-10 B h B 10
-14 B k B 14
-24 B l B 24
31,371
-21 B h B 18
-24 B k B 24
-13 B l B 13
16,090
-15 B h B 15
-14 B k B 14
-25 B l B 24
26,513
-10 B h B 10
-20 B k B 20
-16 B l B 16
15,296
No. of measured reflections
No. of independent reflections/Rint
No. of observed reflections with I [ 2r(I)
No. of parameters
7,132/0.020
6,128
3,773/0.031
2,275
5,989/0.033
4,650
6,675/0.023
5,327
273
162
265
253
Goodness-of-fit (GOF)
R1 (observed data)
1.10
0.86
1.08
0.89
0.0230
0.0258
0.0299
0.0261
wR2 (all data)a
0.0503
0.0531
0.0859
0.0499
a
w = 1/[r2(F2o) ? (0.0266P)2] for 1, w = 1/[r2(F2o) ? (0.0264P)2] for 2, w = 1/[r2(Fo2) ? (0.0408P)2 ? 2.4507P] for 3 and w = 1/[r2(F2o) ?
(0.027P)2] for 4, where P = (Fo2 ? 2F2c)/3
toluene (2:1). Crystallographic data are summarized in
Table 1. X-ray intensity data were collected on an Oxford
Diffraction Xcalibur 3 CCD diffractometer with graphite
Results and discussion
General characterization
˚
monochromated Mo Ka radiation (k = 0.71073 A) at tem-
perature of 295(2) K. The data reduction, including the
analytical numeric absorption correction [13], was performed
using the CrysAlis software package [14]. The structures
were solved by direct methods (SHELXS-97) [15] and
refined by full-matrix least-squares method on F2 (SHELXL-
97) [15]. The non-hydrogen atoms were refined anisotropi-
cally. In complexes 2 and 3, the restraints on geometrical and
displacement parameters were applied for the disordered
structural fragments. All of the hydrogen atoms were posi-
tioned geometrically and refined with the riding model
approximation, with Uiso(H) = 1.2 or 1.5 Ueq(C). All cal-
culations were carried out using the WinGX package of the
crystallographic programs [16] and PLATON [17]. For the
molecular graphics, the program ORTEP-3 [18] was used.
The complexes 1–4 were prepared by a substitution reac-
tion between equimolar amounts of the diimine ligand and
Re(CO)5Cl, as shown in Scheme 1. The obtained com-
plexes are stable in air, either as solid or in solution, and
were characterized by the usual spectroscopic techniques.
The metal centers have an almost ideal octahedral coor-
dination sphere with a facial arrangement of three carbonyl
groups. The typical fac-tricarbonyl unit in these complexes
is evidenced by the CO stretching frequencies as detected
in the IR spectra and is confirmed by the X-ray crystal
structures. The IR spectra of the complexes show two or
one (broad) lower energy and sharp intense bands in the
carbonyl range of 1,865–2,023 cm-1 [19, 20]. The electron
donor substituents shift the CO and CN stretching bands to
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Transition Met Chem (2010) 35:81–87
Cl
R1
N
R1
R1
N
R1
N
N
Toluene/CH2Cl2
Reflux
Re
+ Re(CO)5Cl
R2
R2
R2
R2
OC
CO
CO
R3
R3
R3
R3
4-mbzen: R1=H, R2=H, R3=OCH3
2-mbzen: R1=OCH3, R2=H, R3=H
4-m'bzen: R1=H, R2=H, R3=CH3
3-bbzen: R1=H, R2=Br, R3=H
[Re(CO)3(4-mbzen)Cl] (1)
[Re(CO)3(2-mbzen)Cl] (2)
[Re(CO)3(4-m'bzen)Cl] (3)
[Re(CO)3(3-bbzen)Cl] (4)
Scheme 1 Preparation of the characterized Re(I) tricarbonyl-diimine complexes
3.8
lower frequencies. The p-donor character of the chlorine
atom increases the Re–CO back-bonding, which decreases
the energy of m(CO) [20]. The NMR spectra and peak
assignments are presented in the experimental section. The
1H NMR spectra of the free Schiff bases show the –CH2–
CH2– groups as singlets, but these signals appear as two
sets of multiplets in the complexes indicating that these
protons are not equivalent. All signals in the 1H NMR
spectra of the complexes are shifted to the low-field region
with respect to the free ligands as a result of ligand coor-
dination. The electronic absorption spectroscopic data of
the ligands and complexes in CH2Cl2 are included in
Table 2. In general, the electronic absorption spectra of
rhenium(I) diimine complexes show intense high-energy
absorption bands at ca. 230–300 nm and low-energy
absorption bands at above 350 nm [21, 22]. The high-
energy absorption bands, which are also found in the free
diimine ligands, are assigned as p ? p* transitions of
diimine ligands, while the low-energy absorption bands are
tentatively assigned as the dp (Re) ? p* (diimine) metal-
to-ligand charge transfer (MLCT) transitions. The MLCT
transitions of the complexes in DMSO solution (1 9 10-3
M) appear at 368, 361, 363 and 361 nm for 1, 2, 3 and 4,
respectively. Thus, with increase in polarity of the solvent,
negative solvatochromism (blue shift) is observed. This
hypsochromic shift of the MLCT absorption bands is
explained by assuming that the transfer of the charge in the
MLCT excited state occurs anti-parallel to the ground state
dipole moment [23] (the excited state has a lower dipole
moment than the ground state). The higher transition
energy in more polar solvent (DMSO) may thus be
attributed to the ground state stabilization prevailing with
respect to the excited state stabilization during the transi-
tion [24]. The electrochemical behavior of the prepared
complexes was examined by means of cyclic voltammetry
in CH2Cl2 (Fig. 1). The electrochemical waves are quasi-
reversible couples with Ea values of 1.11, 1.12, 1.10 and
1.2 V versus Ag/AgNO3 (in CH3CN), for complexes 1, 2, 3
and 4, respectively. These couples can be attributed to
oxidation of the rhenium center, commonly observed in the
3.3
2.8
2.3
1.8
1.3
0.8
0.3
-0.2
a
b
c
d
0.78
0.88
0.98
1.08
1.18
1.28
1.38
E/V
Fig. 1 Cyclic voltammograms of [Re(CO)3(2-mbzen)Cl] (a), [Re(CO)3-
(4-mbzen)Cl] (b), [Re(CO)3(3-bbzen)Cl] (c) and [Re(CO)3(4-m’bzen)Cl]
(d) in CH2Cl2 at 298 K (scan rate = 100 mV/s, c = 2 9 10-4 M)
electrochemical studies of other related rhenium-contain-
ing complexes [11]. The nature of the diimine ligand
affects the oxidation potential values. The electron-with-
drawing substituent on the ligand leads to a stabilization of
the Re(I) center. Hence, the abstraction of the electron from
the metal center occurs at more positive potentials for
complex 4 when compared with the other complexes. In
the cyclic voltammetry scans, peak to peak separation
(DEp) of 93, 101 and 85 mV was observed for complexes
1, 2 and 3, respectively.
X-ray structural study of the complexes
The metal center has an almost ideal octahedral coordi-
nation sphere with a facial arrangement of three carbonyl
groups in the synthesized complexes 1–4 (Figs. 2, 3, 4, 5).
The octahedral coordination is completed by a Cl atom and
two N atoms from the diimine Schiff base ligands. Selected
bond lengths and angles of the four complexes are sum-
marized in Table 3. In the crystal structures of 1, 3 and 4,
there is one complex molecule in the asymmetric unit,
whereas in 2, there is only half since it lies on the
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Transition Met Chem (2010) 35:81–87
85
Table 2 Electronic absorption
spectral data of the ligands and
complexes 1–4 in CH2Cl2
Compound
Concentration (M)
kmax (nm) [e] (M-1 cm-1
)
4-mbzen
8 9 10-5
8 9 10-5
8 9 10-5
8 9 10-5
4 9 10-5
4 9 10-5
4 9 10-5
4 9 10-5
256 [23,737]
2-mbzen
246 [20,425], 303 [12,750]
246 [23,087]
4-m’bzen
3-bbzen
244 [21,137], 289 [3,950]
235 [17,875], 286 [29,550], 377 [1,926]a
235 [19,225], 261 [24,250], 293 [17,150], 368 [1,793]a
236 [15,175], 263 [29,250], 371 [1,832]a
Complex 1
Complex 2
Complex 3
Complex 4
237 [19,975], 254 [25,550], 374 [1,858]a
c = 1 9 10-3
M
a
Fig. 2 The molecular structure of complex 1, showing 30% proba-
bility displacement ellipsoids and the atomic numbering
Fig. 5 The molecular structure of complex 4, showing 30% proba-
bility displacement ellipsoids and the atomic numbering
crystallographic mirror plane. The methylene groups in 2
are disordered over two positions with a site occupancy
factor fixed at 50% (due to the crystallographic symmetry;
Fig. 3). The axially disposed chloro and carbonyl ligands
are also disordered over two positions (denoted by A and B
for the major and minor components, respectively; Fig. 3)
with the refined site occupancy factors of 0.778(7) and
0.222(7). Similarly, the axially disposed chloro and car-
bonyl ligands in complex 3 are disordered over two posi-
tions (denoted by A and B for the major and minor
components, respectively; Fig. 4) with a refined site
occupancy ratio of 0.803(4)/0.197(4). In the presence of
sufficient anomalous scattering effect, it was possible to
determine the absolute structure of complex 4 [Flack
parameter = -0.024(6)] [25].
Fig. 3 The molecular structure of complex 2, showing 20% proba-
bility displacement ellipsoids and the atomic numbering. The
methylene groups, as well as the axially disposed carbonyl and
chloro ligands are disordered over two sites (see text for details).
Symmetry code: (i) x, 1/2 - y, z
˚
The Re–C bond distances [1.897(4)–1.937(3) A] are
similar to those in the related complexes [26, 27]. Due to
the p-donor character induced by the coordinated chloride
ligand, the Re–C linkages trans to the Re–Cl linkages are
slightly longer than those trans to the Re–N linkages. The
C=N bond distance values in the complexes are slightly
longer than those observed in free Schiff base ligands [28–
30]. As commonly observed in previously characterized
Re(I)-tricarbonyl diimine systems [31–33], the N–Re–N
bond angles are found to be less than 90° as required by
the steric requirements of chelating ligands. As can be
seen in Table 3, the trans angles at the Re(I) site show a
slight deviation from an ideal octahedral arrangement. No
Fig. 4 The molecular structure of complex 3, showing 30% proba-
bility displacement ellipsoids and the atomic numbering. The axially
disposed carbonyl and chloro ligands are disordered over two sites
with occupancies of 0.803(4) and 0.197(4) (denoted by A and B,
respectively)
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Transition Met Chem (2010) 35:81–87
˚
Table 3 Selected bond distances (A) and angles (°) for complexes 1–
Table 4 Parameters of hydrogen bonding interactions in complexes
1–4
4
Complex 1
D–HꢀꢀꢀA
HꢀꢀꢀA DꢀꢀꢀA
D–HꢀꢀꢀA
(°)
˚
(A)
˚
(A)
Re(1)–Cl(1)
Re(1)–N(1)
Re(1)–N(2)
Re(1)–C(1)
Re(1)–C(2)
Re(1)–C(3)
Complex 2
2.4769(6)
2.192(2)
2.233(2)
1.937(3)
1.901(3)
1.922(2)
N(1)–Re(1)–N(2)
N(1)–Re(1)–C(2)
N(2)–Re(1)–C(3)
C(1)–Re(1)–C(2)
C(1)–Re(1)–C(3)
C(1)–Re(1)–Cl(1)
78.11(8)
97.94(9)
Complex 1 C(12)–H(12)ꢀꢀꢀCl(1)
C(17)–H(17)ꢀꢀꢀCl(1)a
2.71
2.71
2.56
3.590(3) 157
3.594(2) 160
3.363(4) 142
3.597(8) 164
3.625(6) 157
3.587(4) 161
3.546(5) 167
100.32(10)
87.25(12)
90.42(11)
175.58(8)
C(19)–H(19B)ꢀꢀꢀO(4)b
Complex 2 C(18B)–H(18C)ꢀꢀꢀO(2)c 2.45
Complex 3 C(16)–H(16)ꢀꢀꢀCl(1A)
Complex 4 C(22)–H(22)ꢀꢀꢀCl(1)
C(27)–H(27)ꢀꢀꢀCl(1)a
2.75
2.70
2.63
Re(1)–Cl(1A) 2.4412(19) N(1)–Re(1)–N(1A)
77.12(9)
99.55(11)
89.7(3)
Re(1)–Cl(1B)
Re(1)–N(1)
Re(1)–C(1A)
Re(1)–C(1B)
Re(1)–C(2)
2.412(10) N(1)–Re(1)–C(2)
Symmetry codes: (a) 1 ? x, y, z (b) 2 - x, 3 - y, 2 - z (c) 1/2 ? x,
y, 3/2 - z
2.209(2)
1.921(5)
1.933(6)
1.898(3)
C(1A)–Re(1)–C(2)
C(1B)–Re(1)–C(2)
C(1A)–Re(1)–Cl(1A)
C(1B)–Re(1)–Cl(1B)
91.3(4)
174.2(4)
177.1(9)
Conclusion
Complex 3
In this work, we report the synthesis, characterization and
crystal structures of four Re(I)-tricarbonyl diimine com-
plexes with the N,N0-bis(substituted benzylidene)ethane-
1,2-diamine Schiff bases. All four complexes have been
Re(1)–Cl(1A) 2.4634(18) N(1)–Re(1)–N(2)
77.41(13)
97.52(17)
98.56(19)
87.9(2)
Re(1)–Cl(1B)
Re(1)–N(1)
Re(1)–N(2)
Re(1)–C(1A)
Re(1)–C(1B)
Re(1)–C(2)
Re(1)–C(3)
2.449(10) N(1)–Re(1)–C(2)
2.218(3)
2.222(4)
1.935(7)
1.98(2)
N(2)–Re(1)–C(3)
C(1A)–Re(1)–C(2)
C(1A)–Re(1)–C(3)
C(1B)–Re(1)–C(2)
C(1B)–Re(1)–C(3)
C(1A)–Re(1)–Cl(1A)
C(1B)–Re(1)–Cl(1B)
1
fully characterized by FTIR, H NMR, UV–Vis spectros-
88.3(3)
copy and X-ray diffraction analysis. Electrochemical
behavior of the investigated complexes has been studied
using cyclic voltammetry. Due to the chelating effect of the
diimine ligands, the coordination geometries of Re in the
prepared complexes are distorted octahedral.
90.4(9)
1.909(5)
1.918(5)
86.0(9)
177.6(2)
175.8(9)
Complex 4
Re(1)–Cl(1)
Re(1)–N(1)
Re(1)–N(2)
Re(1)–C(1)
Re(1)–C(2)
Re(1)–C(3)
2.4884(11) N(1)–Re(1)–N(2)
77.28(13)
97.66(16)
101.14(17)
91.5(2)
2.208(3)
2.206(4)
1.899(5)
1.909(5)
1.897(4)
N(1)–Re(1)–C(2)
N(2)–Re(1)–C(3)
C(1)–Re(1)–C(2)
C(1)–Re(1)–Cl(3)
C(1)–Re(1)–Cl(1)
Supplementary materials
The on-line electronic supplementary material contains Fig.
S1. Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC Nos. 738421–738424. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
88.43(19)
175.40(16)
significant influence of the different substituents is seen on
the bonds and angles in the complexes. Their influence,
however, is great on the molecular geometry (Supple-
mental Fig. S1) and also on the crystal packing.
Acknowledgments We are grateful to the University of Isfahan
and the Ministry of Science, Education and Sports of the Republic
of Croatia (Grant No. 119-1193079-1084) for the financial and
other supports of this research. The authors would like to thank
Dr. E. Shams for the CV recording.
Weak intermolecular interactions influence the crystal
packing in the reported crystal structures. Along with the
van der Waals and C–Hꢀꢀꢀp interactions, hydrogen bonds of
the type C–HꢀꢀꢀO and C–HꢀꢀꢀCl are observed. Details of
these hydrogen bonding interactions are presented in
Table 4. Surprisingly, the pꢀꢀꢀp stacking interactions exist
only in the crystal structure of 1; viz. between the two
parallel and centro-symmetrically (2 - x, 2 - y, 2 - z)
related aryl C(11)–C(16) rings [the corresponding inter-
References
1. Striplin DR, Crosby GA (2001) Coord Chem Rev 211:163
2. Lee AJ (1987) Chem Rev 87:711
ˇ
3. Vlcek A, Busby M (2006) Coord Chem Rev 250:1755
˚
planar spacing is 3.5002(11) A, giving the centroid–cen-
˚
troid separation of 3.6229(16) A and the ring offset of
˚
ca. 0.94 A].
4. Rossenaar BR, Hartl F, Stufkens DJ (1996) Inorg Chem 35:6194
5. Collin JP, Sauvage JP (1989) Chem Rev 93:245
¨
6. Kalyanasundaram K, Gratzel M (1998) Coord Chem Rev 177:347
123

Transition Met Chem (2010) 35:81–87
87
¨
7. Gratzel M (ed) (1983) Energy resources through photochemistry
and catalysis. Academic Press, New York
23. Reichardt C (2003) Solvents and solvent effects in organic
chemistry. Wiley-VCH, Weinheim
8. Jurisson SS, Lydon JD (1999) Chem Rev 99:2205
9. Volkert WA, Hoffman TJ (1999) Chem Rev 99:2235
24. Rodriguez L, Ferrer M, Rossell O, Duarte FJS, Santos AG,
Lima JC (2009) J Photochem Photobiol A204:174
25. Flack HD (1983) Acta Crystallogr A39:876
ˇ
10. Stufkensm DJ, Vlcek A (1998) Coord Chem Rev 177:127
11. Yam VWW, Wong KMC, Chong SHF, Lau VCY, Lam SCF,
Zhang L, Cheung KK (2003) J Organomet Chem 670:205
26. Herrick RS, Wrona I, McMicken N, Jones G, Ziegler CJ, Shaw J
(2004) J Organomet Chem 689:4848
¨
12. Knor G, Leirer M, Vogler A (2000) J Organomet Chem 610:16
27. Tshentu ZR, Gerber TIA, Walmsley R, Mayer
Polyhedron 27:406
28. Fun HK, Mirkhani V, Kia R, Vartooni AR (2008a) Acta
Crystallogr E64:o1803
29. Fun HK, Mirkhani V, Kia R, Vartooni AR (2008b) Acta
Crystallogr E64:o1471
P (2008)
13. Clark RC, Reid JS (1995) Acta Crystallogr A51:887
14. Oxford Diffraction (2007) CrysAlis software system. Versions
1.171.32. Oxford Diffraction Ltd, Abingdon, England
15. Sheldrick GM (2008) Acta Crystallogr A64:112
16. Farrugia LJ (1999) J Appl Crystallogr 32:837
17. Spek AL (2003) J Appl Crystallogr 36:7
18. Farrugia LJ (1997) J Appl Crystallogr 30:565
30. Fun HK, Mirkhani V, Kia R, Vartooni AR (2008c) Acta
Crystallogr E64:o1374
´ ´
31. Kia R, Mirkhani V, Kalman A, Deak A (2007a) Polyhedron
´
19. Wolcan E, Torchia G, Tocho J, Piro OE, Juliarena P, Ruiz G,
Feliz MR (2002) J Chem Soc Dalton Trans 2194
20. Klein A, Vogler C, Kaim W (1996) Organometallics 15:236
26:2906
32. Kia R, Mirkhani V, Kalman A, Deak A (2007b) Polyhedron
´
´
´
ˇ
21. Busby M, Matousek P, Towrie M, Vlcek A (2007) Inorg Chim
Acta 360:885
22. Itokazu MK, Polo AS, Faria DLAd, Bignozzi CA, Iha NYM
(2001) Inorg Chim Acta 313:149
26:1711
33. Mirkhani V, Kia R, Vartooni AR, Milic D (2009) Transition Met
Chem 34:225
123