Crystal structure, spectroscopic characterization and computational studies of a Re(I) tricarbonyl-diimine complex with the N,N′-bis(2- methylbenzaldehyde)-1,2-diiminoethane Schiff base

Article abstract of DOI:10.1016/j.poly.2014.03.042

The synthesis, structure and spectroscopic properties of a tricarbonylrhenium(I) complex with the N,N′-bis(2-methylbenzaldehyde)-1,2- diiminoethane Schiff base ligand have been investigated. This complex was characterized by FT-IR, NMR, UV-Vis spectroscopy and X-ray crystallography. Optimized geometric parameters and electronic properties of the synthesized compound and some similar Re(I) tricarbonyl complexes were obtained. The low lying electronic transition energies of the complexes have been determined with the time dependent density functional theory method. The calculations showed that in the complexes the HOMOs cover the Re atom, carbonyl groups and chlorine p orbitals, while the LUMOs are mainly localized on the diimine ligand as a π^* orbital.

Full text of DOI:10.1016/j.poly.2014.03.042

Polyhedron 76 (2014) 22–28
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Crystal structure, spectroscopic characterization and computational
studies of a Re(I) tricarbonyl-diimine complex with the
N,N0-bis(2-methylbenzaldehyde)-1,2-diiminoethane Schiff base
b
b
b
Akbar Rostami-Vartooni a, , Valiollah Mirkhani , Hadi Amiri Rudbari , Ahmad Jamali Moghadam
⇑
a Department of Chemistry, Faculty of Science, University of Qom, Qom 37185-359, Iran
b Faculty of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis, structure and spectroscopic properties of a tricarbonylrhenium(I) complex with the
N,N0-bis(2-methylbenzaldehyde)-1,2-diiminoethane Schiff base ligand have been investigated. This
complex was characterized by FT-IR, NMR, UV–Vis spectroscopy and X-ray crystallography. Optimized
geometric parameters and electronic properties of the synthesized compound and some similar Re(I)
tricarbonyl complexes were obtained. The low lying electronic transition energies of the complexes have
been determined with the time dependent density functional theory method. The calculations showed
that in the complexes the HOMOs cover the Re atom, carbonyl groups and chlorine p orbitals, while
the LUMOs are mainly localized on the diimine ligand as a p⁄ orbital.
Received 10 February 2014
Accepted 21 March 2014
Available online 2 April 2014
Keywords:
Tricarbonylrhenium(I) complexes
Diimine ligands
X-ray crystallography
TD-DFT
Ó 2014 Elsevier Ltd. All rights reserved.
Electronic transition
1. Introduction
and spectroscopic properties of [Re(CO)3(2-m0bzen)Cl] (1), where
2-m0bzen is N,N0-bis(2-methylbenzaldehyde)-1,2-diiminoethane.
Rhenium complexes containing the fac-[Re(CO)3]+ moiety and
derived from bifunctional Schiff base ligands show interesting
photophysical and physicochemical properties [1,2], as well as
being used as photosensitizers in solar cells [3,4], luminescence
probes [5,6] and molecular parts of supramolecules [7]. The unique
properties of Re(I) tricarbonyl-diimine complexes are closely con-
nected to the existence of energetically low-lying charge transfer
excited states with a large electron density shift from the metal
to the diimine ligand (MLCT state) [8,9].
Also, the optimized geometric parameters and electronic proper-
ties of the synthesized complex and similar compounds,
[Re(CO)3(4-nbzen)Cl] (2), [Re(CO)3(4-bbzen)Cl] (3), [Re(CO)3(3-
bbzen)Cl] (4) and [Re(CO)3(3-mbzen)Cl] (5) (see Scheme 1) that
we have already investigated [19–21], were compared.
2. Experimental
2.1. General
New advances in theoretical methods provide a convenient
opportunity for the theoretical study of several important proper-
ties of organic and inorganic molecules. Recently, computational
methods such as Density Functional Theory (DFT) and Time-
Dependent Density Functional Theory (TD-DFT) have been used
for the investigation of Molecular Orbitals (MOs), spectra and
excited state structures of complexes [10–14]. Comprehensive
studies on the ability of different DFT methods for rhenium com-
plexes in geometry optimization and calculation of spectral prop-
erties have been reported in recent years [15,16].
Re(CO)5Cl (from Aldrich) and other starting materials were
reagent grade and were used as received. The solvents were dried
before use with the appropriate drying reagents. IR spectra were
recorded on an IRPrestige-21 Shimadzu FT-IR instrument in KBr
pellets. NMR spectra were obtained on
a Brucker Avance
500 MHz spectrometer. Electronic spectra were recorded on a Shi-
madzu UV-160 spectrophotometer.
2.2. Synthesis of N,N0-bis(2-methylbenzaldehyde)-1,2-diiminoethane
(2-m0bzen)
In continuation of our recent works on amines and coordination
chemistry [17,18], we have investigated the synthesis, structural
This ligand was prepared according to the literature [22,23].
Ethylendiamine (0.2 mL, 3 mmol) was added to a stirred solution
of 2-methylbenzaldehyde (0.72 g, 6 mmol) in CH2Cl2 (15 mL). After
⇑
Corresponding author. Tel.: +98 25 32103096; fax: +98 25 32850953.
E-mail address: a.rostami127@yahoo.com (A. Rostami-Vartooni).
http://dx.doi.org/10.1016/j.poly.2014.03.042
0277-5387/Ó 2014 Elsevier Ltd. All rights reserved.

A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
23
Table 1
Crystal data and details of the structure determination of complex 1.
Cl
R1
N
N
R1
Complex
1
Empirical formula
Formula mass
Colour
Crystal system
Space group
hmax(°)
a (Å)
b (Å)
c (Å)
C
21H22ClN2O3Re
Re
CO
572.02
R2
R2
colourless
monoclinic
C2/c
CO
OC
25.5
R3
R3
34.106(3)
10.9929(8)
19.5366(17)
90
119.567(6)
90
6370.9(10)
12
1.789
R1 = CH3, R2 = R3 = H (1)
R1 = R2 = H, R3 = NO2 (2)
3
4
R1 = R2 = H, R3 = Br ( )
R1 = R3 = H, R2 = Br ( )
a
(°)
R1 = R3 = H, R2 = OCH3 (5)
b (°)
c
(°)
V (Å3)
Scheme 1.
Z
Dcalc (Mg/m3)
l
(mmꢀ1
)
5.871
3336
stirring at room temperature for 3 h, the solution was filtered and
the resulting solid was recrystallized from ethanol. Yield: 91%. FT-
F (000)
Index ranges
ꢀ41 6 h 6 39
ꢀ13 6 k 6 13
ꢀ23 6 l 6 23
13335
5088/0.086
4260
383
1.08
0.0632
0.1620
IR (KBr, cmꢀ1
) mmax: 1638 (C@N).
No. of measured reflections
No. of independent reflections/Rint
2.3. Synthesis of [Re(CO)3(2-m0bzen)Cl]
No. of observed reflections I > 2
Number of parameters
Goodness-of-fit (GOF)
R1 (observed data)
r(I)
A mixture of Re(CO)5Cl (0.2 g, 0.55 mmol) and 2-m0bzen (0.14 g,
0.55 mmol) in degassed CH2Cl2/toluene (30 mL, 1:2 V/V) was
heated at reflux for 3 h. The solution was then concentrated to half
volume and n-hexane was added to precipitate the crude material.
The product was recrystallized from CH2Cl2/toluene to give pure
crystals. Yield: 88%. Anal. Calc. for C21H22ClN2O3Re: C, 44.24; H,
3.71; N, 4.96. Found: C, 44.09; H, 3.88; N, 4.89%. FT-IR (KBr,
wR2 (all data)a
Largest difference in peak and hole (e Åꢀ3
)
2.85 and ꢀ2.68
w = 1/[r
2(Fo2) + (0.0996P)2 + 39.1940P], where P = (Fo2 + 2Fc2)/3.
a
cmꢀ1 max: 2019, 1902, 1867 (CO); 1620 (C@N). 1H NMR (d6-
) m
TD-DFT using the B3LYP (Becke, three-parameter, Lee–Yang–Parr)
functional was applied to compute the vertical electronic transi-
tion energies and the oscillator strengths of the complexes. The
geometries from the X-ray structural data of the selected com-
plexes were used as the initial geometries in the optimization
calculations.
DMSO, dppm): 2.33 (s, 6H, 2 (–CH3); 4.09–4.11, 4.34–4.38 (two sets
of multiplets, 4H, –CH2–CH2–); 7.18–7.56 (m, 8H, aromatic hydro-
gens); 9.29 (s, 2H, iminic hydrogens).
2.4. Crystal structure determination
Single crystals, suitable for X-ray diffraction analysis, were
grown by slow evaporation of a solution of the complex dissolved
in CH2Cl2 and toluene (2:1). The crystallographic data and refine-
ment parameters of the complexes are listed in Table 1. The X-
ray single crystal data were collected at 296(1) K on a STOE IPDS
3. Results and discussions
3.1. General characterization
2T diffractometer (Mo Ka = 0.71073 Å). Cell parameters were
The obtained complex is stable in air, either as a solid or in solu-
tion, and was characterized by the usual spectroscopic techniques.
Coordination of the ligand is indicated by the shifts of m(C@N) from
retrieved using X-AREA [24] software and refined using X-AREA on all
observed reflections. Data reduction and correction for Lp (Lor-
entz-polarization) and decay were performed using X-AREA software.
Absorption corrections were applied using MULABS [25] in PLATON
[26]. All structures were solved by direct methods and refined by
full-matrix least squares on F2 for all data using SHELXTL [27] soft-
1638 cmꢀ1 in the free ligand to 1620 cmꢀ1 in the related complex.
The IR spectrum of the complex shows three lower energy and
sharp intense bands in the carbonyl range 1865–2023 cmꢀ1
[32,33]. The 1H NMR spectrum of the complex shows the –CH2–
CH2– groups as two sets of multiplets, indicating that these pro-
tons are not equivalent. The electronic absorption spectroscopic
data of the 2-m0bzen ligand and the related Re complex in CH2Cl2
are included in Table 2. In tricarbonylrhenium(I) complexes, the
ware. All calculations were performed by PLATON
.
2.5. Computational details
bands observed at 230–300 nm may be due to
p ?
p⁄ transitions
Ab initio calculations have been performed with the TURBOMOLE
program package [28,29], making use of the resolution-of-the-
identity (RI) approximation for the evaluation of the electron-
repulsion integrals. The equilibrium geometries at the ground
electronic states (S0) have been determined at the Möller–Plesset
second order perturbation theory (MP2) level. The calculations
were performed with a few basis sets, the effective core potential
(ECP, based on the TURBOMOLE 6.2 program default) was used
for rhenium (Re) and the correlation-consistent polarized valence
double-zeta (cc-pVDZ) [30] basis sets were used for all the other
atoms, i.e. except Re. The charge distribution calculations were
performed based on the Natural Population Analysis algorithm
(NPA) implemented in the TURBOMOLE program package [31].
and the long wavelength absorption bands (above 350 nm) are
assigned to MLCT transitions from Re(I) to p⁄ (ligand) [34,35].
Table 2
Electronic absorption spectral data of the 2-m0bzen ligand and complex 1 in CH2Cl2.
Compound
Concentration (M)
kmax/nm (
e )
/Mꢀ1cmꢀ1
2-m0bzen
[Re(CO)3(2-m0bzen)Cl]
8 ꢁ 10ꢀ5
250 [21850]
231 [16600], 261 [18350],
359 [1632]a
4 ꢁ 10ꢀ5
a
1 ꢁ 10ꢀ3 M.

24
A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
3.2. Molecular structure
also disordered over two positions around the crystallographic
twofold rotation axis, with a half site occupancy factor in each
position. As shown in Table 3, no significant influence of the differ-
ent substituents is seen on the bonds and angles in this complex
and in similar compounds investigated previously [19–21]. The
values of the diimine bite angles [77.4(3)° and 77.9(5)°] slightly
A perspective drawing and the crystal packing of complex 1 are
shown in Figs. 1 and 2. The metal center has an almost ideal octa-
hedral coordination sphere with a facial arrangement of three car-
bonyl groups. The axially disposed chloro and carbonyl ligands are
Fig. 1. The molecular structure of complex 1, showing 50% probability displacement ellipsoids and the atomic numbering.
Fig. 2. The crystal packing of complex 1, showing the linkage of molecules by intermolecular interactions.

A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
25
deviate from the expected ideal 90° for an octahedron. Hydrogen
bonding interactions for the synthesized complex are summarized
in Table 4. An interesting feature of the crystal packing is the inter-
molecular C–Hꢂ ꢂ ꢂO interactions in which the oxygen atom is a
bifurcated acceptor (Fig. 2).
Cl
N1
C1
N2
O2
3.3. Geometries, electronic structures and electronic spectra
O1
C2
C3
The optimized geometry of complex 1 and several of the highest
occupied (HOMOꢀ5 to HOMO) and the lowest unoccupied (LUMO
to LUMO+5) orbitals of complex 5 are presented in Figs. 3 and 4. A
comparison of the energy level and configuration of the HOMOs
and LUMOs of complexes 1–5 are shown in Fig. 5. Also, more infor-
mation about the geometries and energetic diagrams of the fron-
tier orbitals of complexes 1–5 are presented in the electronic
Supplementary information file (ESI) (see Figs. SM1–SM9). As
shown in these figures, the highest three occupied molecular orbi-
tals in the complexes are predominately located on the Re atom,
which correspond to the (5dxy)2(5dyz)2(5dxz)2 occupation of the
central ion.
O3
Fig. 3. Optimized geometry structure of complex 1, at the MP2/cc-pVDZ level of
theory.
The HOMO and HOMOꢀ1 orbitals of complexes 1, 2 and 3 are of
the d type with some contribution from p chloride and the p-anti-
p
bonding orbital of the CO ligands. In complex 5, the HOMO is
located on the benzene ring, while the dRe orbitals take a main part
in the HOMOꢀ1 to HOMOꢀ4 orbitals. The low-lying virtual orbi-
tals mainly correspond to p⁄diimine orbitals (pC⁄@C p⁄C@N or p⁄N@O in
,
the case of the nitro subs⁄tituted complex). The energy of p⁄diimine is
lower than that of the pCO orbitals and the HOMO–LUMO energy
gap is 10.39, 9.36, 10.0, 10.05 and 10.10 eV for complexes 1–5,
respectively.
The experimental and optimized geometric parameters of com-
plexes 2–5 are presented in Table 5. As shown in Tables 3 and 5,
the MP2 calculated values using the cc-pVDZ basis set for selected
bond lengths and bond angles in the Re complexes are well
comparable with the X-ray experimental data. Therefore the
MP2/cc-pVDZ level of calculation is convenient to obtain geometric
parameters for such inorganic compounds. Due to the
p-donor
character of the chloride ligand, the Re–C(3) (see Fig. 3) bond
length in the complexes is slightly shorter than the Re–C(1) and
Re–C(2) bond lengths, which are relatively consistent with the
Table 3
Selected experimental and optimized bond lengths (Å) and bond angles (°) of complex
1. The theoretical values are in brackets.
Bond lengths
Bond angles
Re(1)–Cl(1)
Re(2)–Cl(2)
Re(1)–N(1)
Re(2)–N(2)
Re(2)–N(3)
Re(1)–C(1)
Re(1)–C(11)
Re(2)–C(32)
Re(2)–C(31)
Re(2)–C(30)
N(1)–C(3)
2.500(10)
2.490(3) [2.497]
2.214(10)
2.189(8) [2.216]
2.196(9) [2.216]
1.79(3)
N(1)–Re(1)–N(1A)
N(2)–Re(2)–N(3)
N(1)–Re(1)–C(11)
N(2)–Re(2)–C(30)
N(3)–Re(2)–C(31)
C(1)–Re(1)–Cl(1A)
C(1)–Re(1)–C(1A)
C(32)–Re(2)–Cl(2)
Cl(1)–Re(1)–N(1)
Cl(1)–Re(1)–N(1A)
Cl(2)–Re(2)–N(2)
Cl(2)–Re(2)–N(3)
77.9(5)
77.4(3) [75.9]
97.5(5)
100.7(4) [98.3]
97.2(5) [101.9]
177.0(9)
175.4(19)
175.3(4) [173.0]
82.4(3)
89.9(3)
81.6(2) [87.0]
86.5(3) [79.6]
1.949(12)
1.902(13) [1.890]
1.946(11) [1.918]
1.932(12) [1.917]
1.273(15)
1.266(14) [1.300]
1.284(15) [1.296]
N(2)–C(22)
N(3)–C(14)
Table 4
Parameters of the hydrogen bonding interactions in complex 1.
D–Hꢂ ꢂ ꢂA
Hꢂ ꢂ ꢂA (Å)
2.65
2.63
Dꢂ ꢂ ꢂA (Å)
3.33(3)
3.50(3)
D–Hꢂ ꢂ ꢂA (°)
127.1
149.4
C(12)–H(12A)ꢂ ꢂ ꢂO(1)i
C(22)–H(22B)ꢂ ꢂ ꢂO(1)i
Fig. 4. The highest six occupied (HOMOꢀ5 to HOMO) and the lowest six
unoccupied (LUMO to LUMO+5) orbitals of complex 5. The configuration and
energy level (in eV) of the orbitals are in brackets.
Symmetrycode: (i) x,ꢀ1 + y,z.

26
A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
Complex
HOMO
LUMO
1
dxz, π*CO and πCl (-8.30)
π*bzen (2.09)
2
dxz, π*CO and πCl (-8.96)
dxz, π*CO and πCl (-8.54)
dxz, π*CO and πCl (-8.51)
π*bzen (0.41)
π*bzen (1.46)
π*bzen (1.54)
3
4
5
πbzen (-8.05)
π*bzen (1.60)
Fig. 5. A comparison of the energy levels (in eV) and configurations of the HOMOs and LUMOs of complexes 1–5.
Table 5
Selected experimental and optimized bond lengths (Å) and bond angles (°) of complexes 2–5. The theoretical values are in brackets and X-ray data taken from the literatures are
presented out of the brackets.
Complex
2a
3b
4c
5b
Bond lengths
Re–Cl
2.4814(9) [2.515]
2.212(2) [2.220]
2.217(3) [2.221]
1.916(4) [1.915]
1.921(4) [1.916]
1.911(5) [1.893]
2.4929(7) [2.517]
2.225(2) [2.223]
2. 188(3) [2.223]
1.913(3) [1.917]
1.937(3) [1.914]
1.918(3) [1.891]
2.4884(11) [2.515]
2.206(4) [2.222]
2.208(3) [2.223]
1.897(4) [1.915]
1.909(5) [1.917]
1.899(5) [1.891]
2.4835(10) [2.517]
2.195(3) [2.225]
2.199(3) [2.237]
1.929(4) [1.911]
1.912(4) [1.915]
1.913(4) [1.889]
Re–N(1)
Re–N(2)
Re–C(1)
Re–C(2)
Re–C(3)
Bond angles
N(1)–Re–N(2)
N(1)–Re–C(1)
N(2)–Re–C(2)
C(1)–Re–C(3)
C(2)–Re–C(3)
C(3)–Re–Cl
77.01(10) [76.2]
98.16(13) [100.0]
98.93(14) [99.1]
89.78 (16) [86.8]
88.37(16) [89.0]
176.90(12) [174.4]
78.15(8) [76.3]
98.14(11) [98.7]
98.62(10) [100.3]
86.86(12) [89.0]
92.08(11) [86.7]
173.53(9) [174.8]
77.28(13) [76.2]
101.14(17) [100.4]
97.66(16) [98.7]
88.43(19) [86.6]
91.5(2) [89.0]
77.73(11) [76.7]
97.17(15) [99.6]
99.48(15) [99.5]
90.87(18) [86.0]
86.58(18) [89.3]
175.83(13) [175.1]
175.40(16) [174.7]
a
b
c
The experimental values were taken from Reference 19.
The experimental values were taken from Reference 20.
The experimental values were taken from Reference 21.
experimental results. The reason can be related to the presence of
extended -bonding between the orbital of ligand in the trans
Table 6 shows a summary of the charge distribution calcula-
tions for each complex. The charge values on the rhenium atom
in the complexes are significantly lower than the formal charge
of +1, which corresponds to a d6 configuration of the central ion.
p
p
position to the Re–C(3) bond and the Re d orbital, which weakens
p
the Re ? C(3) back bonding [16].

A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
27
Table 6
geometries (see Table 7). The discrepancy between the experimen-
tal and theoretical results in Table 7 originates from two sources.
The theoretical results are vertical transitions, not adiabatic, and
obviously they will be far from either the adiabatic or the experi-
mental transitions. Another source will be related to solvent
effects, which were not considered in the calculations. The broad
low-energy absorption band at about 370–390 nm is attributed
to Metal–Ligand Charge Transfer transitions (MLCT), occurring
from the rhenium center to the p⁄ diimine orbitals (d ? p⁄). The
Selected atomic charge distribution, calculated based on the Natural Population
Analysis algorithm (NPA). The complex numbering is performed based on Fig. 3.
Complex
1
2
3
4
5
Re
ꢀ0.132
ꢀ0.6
ꢀ0.15
ꢀ0.587
ꢀ0.575
ꢀ0.649
0.767
ꢀ0.144
ꢀ0.585
ꢀ0.601
ꢀ0.653
0.786
ꢀ0.145
ꢀ0.596
ꢀ0.582
ꢀ0.649
0.767
ꢀ0.125
ꢀ0.613
ꢀ0.603
ꢀ0.649
0.763
N(1)
N(2)
Cl
C(1)
C(2)
C(3)
O(1)
O(2)
O(3)
ꢀ0.582
ꢀ0.661
0.771
0.776
0.713
0.786
0.71
0.767
0.71
0.787
0.71
0.784
0.708
mixed dRe
+
p⁄CO
/
pCl character of the HOMO and HOMOꢀ1 orbitals
ꢀ0.596
ꢀ0.596
ꢀ0.636
ꢀ0.592
ꢀ0.589
ꢀ0.626
ꢀ0.589
ꢀ0.595
ꢀ0.632
ꢀ0.594
ꢀ0.589
ꢀ0.634
ꢀ0.599
ꢀ0.592
ꢀ0.637
implies that the transitions can be seen as mixed Re ? bzen (MLCT)
and Cl ? bzen (LLCT), or a delocalized MLLCT (metal-ligand-to-
ligand CT) description can be used. The lowest-lying absorptions,
which arise from the HOMO ? LUMO excitation configuration, are
red-shifted in the order 2 < 4 < 3 < 5 < 1, when the electron-with-
drawing substituents are introduced into the benzene ring. The
energy levels of the LUMO for complexes 1–5 are 2.09, 0.41, 1.46,
1.54 and 1.60 eV, respectively. Obviously, the LUMO is more stabi-
lized with the electron-withdrawing substituent in the complex 2.
This is quite in agreement with previously reported results on the
stabilization of p⁄ orbitals of aromatic molecules by an electron-
withdrawing group [37,38].
A significant charge donation from the ligands to the Re atom is the
reason for such a low charge being located on the central Re atom
[36]. The oxygen atom which is exactly in front of the chloride ion
has the highest negative charge, as a result of the
ter of the chloride ligand.
Typically, the vertical electronic transition energies accompa-
nied with their oscillator strengths for complexes 1–5 have been
obtained at the TD-DFT/cc-PVDZ level of theory on the optimized
p-donor charac-
Table 7
The lowest lying transition energies and oscillator strengths of complexes 1–5, calculated at the TD-DFT/cc-pVDZ level of theory.
k (nm)
E(eV)
Oscillator Strength
The most important orbital excitations
Character
Experimental k (nm)a
1
404.3
387.5
375
359
354.5
3.07
3.2
3.31
3.45
3.5
0.0294
0.0091
0.0102
0.026
H ? L (91.4%)
dxz
dyz
dxz
dyz
dxy
+
+
+
+
p⁄CO
pCl
/
pCl
?
p⁄(bzen)
391b
261
Hꢀ1 ? L (82.2%)
H ? L+1 (82.4%)
Hꢀ1 ? L+1 (94.2)
Hꢀ2 ? L+1 (93.9)
?
p⁄(bzen)
p⁄CO
pCl
/
?
pCl
?
p⁄(bzen)
p⁄(bzen)
0.0028
?
p⁄(bzen)
2
489.6
468.1
2.53
2.65
0.0181
0.0187
H ? L (90.8%)
dxz
dyz
dxz
dxz
dyz
dyz
dxy
+
+
+
+
+
+
p⁄CO
/
pCl
?
p⁄(bzen)
p⁄(bzen)
391b
261
Hꢀ1 ? L (62.1%)
H ? L+1 (32.6%)
H ? L+1 (60.2%)
Hꢀ1 ? L (30.0%)
Hꢀ1 ? L+1 (94.1%)
Hꢀ2 ? L (95.6%)
pCl
p⁄CO
p⁄CO
pCl
pCl
?
/
/
?
?
p⁄(bzen)
pCl
pCl
?
?
464
2.67
0.0028
p⁄(bzen)
p⁄(bzen)
p⁄(bzen)
443.2
404
2.8
3.07
0.016
0.0014
?
p⁄(bzen)
3
429.5
412.6
2.89
3.01
0.0298
0.0066
H ? L (93.5%)
dxz
dyz
dxz
dxz
dyz
dyz
dxy
+
+
+
+
+
+
p⁄CO
/
pCl
?
p⁄(bzen)
p⁄(bzen)
370b
261
233
Hꢀ1 ? L (58.0%)
H ? L+1 (40.3%)
H ? L+1 (54.1%)
Hꢀ1 ? L (37.7%)
Hꢀ1 ? L+1 (96.5%)
Hꢀ2 ? L (95.0%)
pCl
p⁄CO
p⁄CO
pCl
pCl
?
/
/
?
?
p⁄(bzen)
pCl
pCl
?
?
404.3
3.07
0.0116
p⁄(bzen)
p⁄(bzen)
p⁄(bzen)
390.1
365.5
3.18
3.39
0.0371
0.0002
?
p⁄(bzen)
4
432.5
415.3
2.87
2.99
0.0202
0.0063
H ? L (94.8%)
dxz
dyz
dxz
dxz
dyz
dyz
dxy
+
+
+
+
+
+
+
p⁄CO
/
pCl
?
p⁄(bzen)
p⁄(bzen)
374b
254
Hꢀ1 ? L (57.2%)
H ? L+1 (40.9%)
H ? L+1(53.3%)
Hꢀ1 ? L (39%)
Hꢀ1 ? L+1 (95.6%)
Hꢀ2 ? L (95.6%)
pCl
?
/
/
p⁄(bzen)
p⁄CO
p⁄CO
pCl
pCl
pCl
?
?
406.5
3.05
0.0106
p⁄(bzen)
?
p⁄(bzen)
392.9
367.8
3.16
3.37
0.0319
0.0004
pCl
?
p⁄(bzen)
p
(bzen)/pBr
?
p⁄(bzen)
5
411.3
395.6
3.01
3.13
0.0164
0.005
H ? L (98.6%)
p
p
dxz
(bzen) ? p⁄(bzen)
(bzen) ? p⁄(bzen)
369b
258
238
H ? L+1 (51.1%)
Hꢀ1 ? L (47.4%)
Hꢀ1 ? L (49.6%)
H ? L+1 (47.6%)
Hꢀ1 ? L+1(96.3%)
Hꢀ2 ? L (53.3%)
Hꢀ4 ? L (24.2%)
+
p⁄CO
p⁄CO
/
pCl
?
p⁄(bzen)
?
p⁄(bzen)
387.6
3.2
0.0065
dxz
+
/
pCl
p
(bzen) ? p⁄(bzen)
377.3
357
3.29
3.47
0.0452
0.0635
dxz
dyz
dxy
+
+
?
p⁄CO p⁄(bzen)
/pCl ?
p
(bzen)/pCl
?
p⁄(bzen)
p⁄(bzen)
H represents the highest occupied orbital (HOMO) and L represents to the lowest unoccupied orbital (LUMO).
a
Solvent = dichlorometane.
b
C = 1 ꢁ 10ꢀ3 M.

28
A. Rostami-Vartooni et al. / Polyhedron 76 (2014) 22–28
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In this work, we report the synthesis, structural, spectroscopic
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with
the
N,N0-bis(2-methylbenzaldehyde)-1,2-diiminoethane
Schiff base ligand. The ground state optimized geometry parame-
ters of the synthesized compound and four similar complexes at
the MP2/cc-pVDZ level of theory are in good agreement with the
X-ray experimental data. The molecular orbital diagrams of the
complexes, with the several highest occupied and lowest unoccu-
pied molecular orbital contours, showed that the highest occupied
MOs are of the d type with some contributions from p chloride
p
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This work was supported by the University of Qom and the
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Appendix A. Supplementary data
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A Development of the University of Karlsruhe and
Forschungazentrum Karlsruhe GmbH, 1989–2007, Turbomole, GmbH, since
2007. Available from: <http://www.turbomole.com>.
CCDC 978385 contains the supplementary crystallographic data
for complex 1. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/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.
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