Synthesis, characterization, and crystal structure of novel bulky phenyl-bridged α-diimine binucleating ligands

Article abstract of DOI:10.1002/hc.21424

A series of sterically and electronically modulated phenyl-bridged α-diimine ligands L1-L6 of the general formula Ar-N= C(Me)-C( Me)=N-C₆H₄- N= C(Me)-C( Me)=N-Ar have been synthesized (L1 : Ar = 2,6-iPr₂- C₆H

Full text of DOI:10.1002/hc.21424

Received: 24 September 2017
DOI: 10.1002/hc.21424
Revised: 19 May 2018
|
R E S E A R C H A R T I C L E
Synthesis, characterization, and crystal structure of novel bulky
phenyl-bridged α-diimine binucleating ligands
Ali Mechria
Moncef Msaddek
|
Laboratoire de Chimie Hétérocyclique,
Produits naturels et Réactivité:
L.C.H.P.N.R, Faculté des sciences de
Monastir, Monastir, Tunisia
Abstract
A series of sterically and electronically modulated phenyl-bridged α-diimine ligands
L1–L6 of the general formula Ar-N=C(Me)-C(Me)=N-C6H4-N=C(Me)-
C(Me)=N-Ar have been synthesized (L1
:
Ar = 2,6-iPr2-C6H3; L2:
Correspondence
Ali Mechria, Laboratoire de Chimie
Hétérocyclique, Produits naturels et
Réactivité : L.C.H.P.N.R, Faculté
des sciences de Monastir, Bd de
l’environnement, 5000 Monastir, Tunisia.
Email: ali.mechria@fsm.rnu.tn
Ar = 2,6-Me2-C6H3; L3: 4-Me-C6H4; L4: Ar = 4-Et-C6H4; L5: Ar = 2,4,6-Cl3-C6H2;
L6: Ar = 4-Cl-C6H4). All of which have been characterized by 1H NMR, 13C NMR,
IR, and elemental analysis. In addition, the effect of the electronic modification was
studied by UV–Vis spectroscopy, and the structure of a representative ligand was
confirmed by single-crystal X-ray diffraction. Moreover, a DFT electronic structure
of the same ligand has been determined.
bridged ligands by phenyl spacers introducing appended
imine functionalities with bulky aryl substituent’s on the N-
1
INTRODUCTION
|
Over the past two decades, a considerable interest was given
to alternative ligands to phosphines, for the development of
late transition metal catalysts. Examples of this include the
important development by Brookhart and co-workers of α-
diimine ligands for nickel and palladium catalysed olefin
polymerization and oligomerization.[1] Furthermore, interest
in these α-diimine systems-based complexes and various de-
rivatives thereof have arose extensively in both academic and
industrial research.[2–9] Recently, a range of sterically encum-
bered multidentate binucleating nitrogen-ligands, such as
organo-bridged iminopyridines, α-diimines, and iminophe-
nolates, were found to be efficient systems achieving active
dinickel,[10–18] dipalladium,[19] and diiron catalysts[17,20] for
alkene oligomerization/polymerization. The electronic inter-
actions found like some cooperative effects between neigh-
boring active metal centers are the reason of this catalytic
performance. The same electronic effects cannot be expected
in their mononuclear counterparts.[21–24] Considering the fact
that only limited works on modified α-diimine systems and
as a continuation of this type of study that allows us to take
advantage of spatial proximities of the binucleating ligands,
we have targeted a binucleating version, modulated sterically
and electronically, of these intensively studied α-diimine li-
gands as possible supports for bimetallic complexes. These
aryl moiety making them symmetrical. These new phenyl-
bridged α-diimine ligands retains all the essential features of
the α-diimine ligands and in addition provides an additional
adjacent compartment to accommodate another metal, mak-
ing them closely the bimetallic mimic of the originally devel-
oped and the most studied α-diimine based metal complexes.
The present paper provides a full account of our new meth-
odology for the synthesis, isolation, and characterization of a
series of novel phenyl-bridged α-diimine ligands.
2
RESULTS AND DISCUSSION
Synthesis and characterization of new
|
2.1
|
ligands
Novel ligands phenyl-bridged α-diimine L1–L6 have been
prepared in a facile and versatile one-pot 2-step manner
under mild conditions in two successive condensation re-
actions. First, the treatment of butane-2,3-dione with one
equivalent of aromatic primary amines leads to the corre-
sponding α-iminoketone without isolation of the product.
The advancement of the reaction was checked by TLC. When
the majority of the reactants are consumed, a half equivalent
of para-phenyenediamine was added to the reaction vessel at
|
Heteroatom Chemistry. 2018;e21424.
https://doi.org/10.1002/hc.21424
wileyonlinelibrary.com/journal/hc
© 2018 Wiley Periodicals, Inc.
1 of 7

2 of 7
MECHRIA And MSAddEK
|
room temperature with vigorous stirring affording the desired
compounds after several hours (Scheme 1):
2.2
Crystal structure of ligand L1
|
The molecular structure for L1 has been determined by a sin-
gle crystal X-ray diffraction study at 293 K and is shown in
Figure 2. Crystallographic details are provided in Table 1,
and relevant geometrical parameters are listed in Tables 2
and 3. Crystals of ligand L1 suitable for structure determina-
tion were grown by slow evaporation of ethanolic solution
at room temperature. The molecular structure of ligand L1
shows an asymmetric unit formed by a half molecule of Ar-
N=C(Me)-C(Me)=N-C6H4-N=C(Me)-C(Me)=N-Ar (where
Ar = 2,6-iPr2-C6H3) while the corresponding molecular struc-
ture is generated by symmetry. In the solid state, the molecule
exists in the E (anti) configuration at both C=N double bonds,
while the conformation of the central C–C bond is s-trans as
indicated by the torsion angles N1–C13–C15–N2 and N1–
C13–C15–C16 of 170.4(2)° and −5.9(4)°, respectively. The
N-imine aryl rings lie perpendicular to the diimine backbone
plane as indicated by the torsion angles C6–C1–N1–C13 and
C13–N1–C1–C2 of 81.9(3) and −104.3(3)° respectively, likely
because of steric repulsion between the two bulky diisopro-
pylphenyl groups. Furthermore, the aryl ring spacer is almost
perpendicular to the bis(imino) backbone plane as revealed by
the dihedral angles C15–N2–C17–C19A and C15–N2–C17–
C18 of −74.9(3) and 110.4(3)°. The two imine distances C=N
(1.268(2) for N1–C13 and 1.269(3) Å for N2–C15) are identi-
cal and agree well with the values for double bond charac-
ter.[22–24] The N–Caryl simple bonds (1.429(3) for N1–C1 and
1.424(3) Å for N2–C17) agree with the expected range for this
type of bonds.[28] The C–C bond distances (1.37–1.39 Å) and
the C–C–C bond angles (117°–121°) of the phenyl rings are
in accordance with the values reported in the literature.[22–24]
These new phenyl-bridged α-diimine ligands L1–L6 were
isolated as pale yellow solids sparingly soluble in ethanol
and dichloromethane but almost insoluble in all other com-
mon solvants. H, 13C, NMR, IR spectroscopy and elemen-
1
tal analyses were consistent with the bis-(diimine) ligands
formulation. The formation of these bis-α-diimine ligands
is easily deduced from the study of their FTIR spectra. In
fact, the disappearance of the stong band of the carbonyl at
around 1,715 cm−1 and the appearance of a new characteris-
tic intense band at around 1,630 cm−1, which is attributed to
the imine function, confirms the creation of ligands L1–L6.
The examination of 1H and 13C NMR spectra of ligands L1–
L6, in CDCl3 at room temperature, supports their respective
structures and shows similar trends both in the aromatic and
aliphatic regions. Furthermore, the number of signals indi-
cates that all ligands are symmetrical. Detailed chemical shift
values for all the carbon and protons are given in Section 4.
1
The H NMR spectra of ligands show that the protons of
the two methyl groups of the diimine backbone occurs at
around δ 2.20 and 2 ppm which is slightly upfield from that
of 2,3-butanedione at δ 2.33 ppm.[25] In the aromatic region,
the protons of the phenyl spacer appear as a singlet at around
6.8 ppm. All others signals of the ligands L1–L6 are found
in the expected ranges. The 13C NMR spectra agreed very
well with the proposed structures of the binucleating ligands
L1–L6. The disappearance of the carbonyl signals at around
197 ppm and the appearance of two signals around 168 and
167 ppm, attributed to the two azomethine carbons, confirms
the identity of these bis-α-diimine ligands. All other signals
are in concordance with the structure of the ligands.
Electronic spectra of ligands L1–L6 recorded in dichloro-
methane over the scan range of 200–800 nm show identical
trends. All ligands present in their absorption spectra a strong
band at around 240 nm which can be ascribed to π → π* tran-
sition and another weak band at around 360 nm correspond-
ing to n → π* transitions[26,27] (Figure 1):
2.3
Density functional theory (DFT)
|
calculations
Geometry optimization reported in this article was done
with the Gaussian09[29] program package supported by
R1
R1
R1
MeOH/AcOH
+
R2
NH2
R2
N
O
48 h
stir, RT,
O
O
R1
R1
+
1/2 H2N
NH2
N
R2
12
12
11
7
R1
N
N
R1
9
3
5
2
8
MeOH
stir, RT,
1
4
24 h
R2
N
:
L1
10
R1
R1
R1
R1
R1
R1
R
R
H
=
=
=
=
=
=
=
iPr,
Me,
H,
H,
R
2
:
:
:
:
:
L2
L3
L4
L5
H
6 R1
=
Me
2
R
=
R2 Et
SCHEME 1 Synthetic route for
the synthesis of pheny-bridged α-diimine
ligands L1–L6
=
2
Cl
2
=
2 R
L
6
Cl
=
H,

MECHRIA And MSAddEK
3 of 7
|
GaussView 5.0.8. The DFT[30,31] calculations has been per-
formed with the popular hybrid-GGA functional B3LYP
(Becke, three-parameter combined with Lee–Yang–Parr
correlation functional).[32–35] In this study, we chose the
double-zeta Pople-type basis set 6-31++G(d,p)[36–38] for
all atoms. The initial geometry has been taken from crystal
structure. The geometry of L1 in the gas phase has been
optimized using tight convergence criteria ignoring sym-
metry and using S = 0 spin state. Optimized structure ob-
tained from unrestricted B3LYP method was confirmed to
be local minima by performing analytical vibrational fre-
quency analysis at the same level of theory (no imaginary
frequency observed). Experimental and theoretical geomet-
ric parameters are summarized in Table 2 and 3. It can be
seen that the X-ray solid state and the electronic structures
are similar. The ligand L1 adopt an s-trans conformation as
shown in Figure 3. Furthermore, the differences between
experimental and theoretical bond distances are within the
standard uncertainties (0.01 Å). So, the B3LYP functional
predicted reasonably accurate geometry.
FIGURE 1 UV–Vis spectra of ligands L1–L6 in dichloromethane
FIGURE 2 ORTEP representation of the molecular structure of ligand L1 with atom labeling scheme and anisotropic displacement ellipsoid
depicted at 40% probability. Hydrogen atoms are omitted for clarity

4 of 7
MECHRIA And MSAddEK
|
TABLE 1 Crystal data and structure refinement for ligand L1
TABLE 3 Experimental and theoretical bond angles of L1
Chemical formula
C38 H50 N4
Bond angles (°)
Experimental
Theoretical
Crystal size (mm3)
Formula weight
Crystal system
Space group
a (Å)
0.09 × 0.06 × 0.04
562.82
Monoclinic
P21/c
12.677(5)
8.791(5)
16.274(5)
99.524(5)
1788.6(14)
2
C13–N1–C1
C15–N2–C17
C6–C1–N1
120.6(2)
121.5(2)
118.4(2)
119.4(2)
117.3(2)
126.2(2)
116.4(2)
126.1(2)
115.7(2)
118.1(2)
123.19
124.13
118.65
119.91
116.44
126.00
117.54
126.69
115.67
117.63
C2–C1–N1
N1–C13–C15
N1–C13–C14
C15–C13–C14
N2–C15–C16
N2–C15–C13
C16–C15–C13
b (Å)
c (Å)
β (°)
V (Å3)
Z
T (K)
ρ
293(2)
calc (g/cm3)
1.045
on a Bruker AMX 300 spectrometer. H and C chemical
shifts were given in ppm and referenced to the residual sol-
vent resonance relative to TMS. IR spectra were recorded
on a Perkin-Elmer Spectrum two FT-IR instrument with
the Universal ATR Sampling Accessory over the range of
4,000–400 cm−1. The electronic spectra were measured on
an UviLine 9400, SECOMAM spectrophotometer over the
range of 200–800 nm. Melting Points were recorded using
a Kofler hot stage apparatus and are uncorrected. Elemental
analyses were performed on a Perkin-Elmer 2400 series II
CHNS/O analyzer.
Total reflections
Unique reflections
R(int)
3515
1292
0.0305
53.35
0.71073
0.061
612
1.091
0.0567
0.1024
2θmax (°)
λ (Å)
μ (mm−1
F(000)
)
Goodness-of-fit
R1 (I > 2σ(I))
wR2
3.2
Synthesis of ligands L1–L6
General procedure
|
TABLE 2 Experimental and theoretical bond distances of L1
3.2.1
|
Bond lengths
Experimental
Theoretical
A 50 mL round bottom flask was charged with methanol
(30 mL), primary arylamines (20 mmol), butane-2,3-dione
(1.72 g, 20 mmol), and glacial acetic acid (0.4 g, 6.7 mmol).
The yellow solution was stirred at room temperature for
24 hours. The progress of the reaction was monitored by
TLC by the consumption of reactants. When the reaction was
complete, p-phenylenediamine (1.08 g, 10 mmol) was added
and the reaction mixture was stirred for 2 days at room tem-
perature. The resulting yellow precipitate was isolated by fil-
tration, washed with methanol (3 × 10 mL), and dried under
vacuum for 12 hours affording the ligands L1–L6 in good to
moderate yields. All ligands were obtained as a pale yellow
powder.
N1–C1
1.429(3)
1.268(2)
1.269(3)
1.424(3)
1.400(3)
1.396(3)
1.501(3)
1.500(3)
1.496(3)
1.42
1.28
1.28
1.40
1.41
1.41
1.51
1.50
1.51
N1–C13
N2–C15
N2–C17
C1–C2
C1–C6
C13–C14
C13–C15
C15–C16
3
EXPERIMENTAL
General methods and materials
2,6-diisopropylaniline, 2,6-dimethylaniline and 4-ethylani
line were distilled under vacuum from potassium hydrox-
ide prior to use. p-Toluidine and p-phenylenediamine
were purified by sublimation in vacuo. Butane-2,3-dione,
4-chloroaniline and 2,4,6-trichloroaniline were used as re-
ceived from Sigma-Aldrich. NMR spectra were recorded
|
3.1
3.2.2
Synthesis of ligand L1
|
|
L1 was obtained from 2,6-diisopropylaniline (3.56 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial ace-
tic acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
10 mmol). Yield: 3.7 g (67%). Crystals suitable for structure
determination were grown by slow evaporation of ethanolic
solution at room temperature. m.p. 161°C. IR [ν cm−1]: 1634

MECHRIA And MSAddEK
5 of 7
|
FIGURE 3 DFT optimized structure of ligand L1 using the same atom labeling scheme as ORTEP representation. Hydrogen atoms are
omitted for clarity
(νC=N). Anal. Calc. for C38H50N4 (562.83): C, 81.09; H,
8.95; N, 9.95. Found: C, 80.58; H, 9.12; N, 10.30. 1H-NMR
(300 MHz, CDCl3): 1.13 (dd, 24H, CH(CH3)2); 1.94 (s, 6H,
C10H3); 2.18 (s, 6H, C7H3); 2.65 (sept, 4H, J = 6.6 Hz,
CH(CH3)2); 6.82 (s, 4H, H12); 7.04 (m, 6H, H3,4,5). 13C-
NMR (75.47 MHz, CDCl3): 15.22 (C10); 16.17 (C7); 22.58,
23.12 (CH3-iPr); 28.40 (CH-iPr); 120.01 (C12); 122.89 (C3,5);
123.55 (C4); 135.06 (C2,6); 143.15 (C11); 147.08 (C1); 168.14,
168.30 (C8, C9). λmax (nm): 240, 357.
10 mmol). Yield: 2.21 g (52%). m.p. 154°C. IR [ν cm−1]:
1632 (νC=N). Anal. Calc. for C28H30N4 (422.56): C, 79.59; H,
7.16; N, 13.26. Found: C, 80.23; H, 7.95; N, 12.84. 1H-NMR
(300 MHz, CDCl3): 2.04 (s, 6H, C10H3); 2.16 (s, 6H, C7H3);
2.24 (s, 6H, p-CH3); 6.71 (d, 4H, J = 7.2 Hz, H2,6); 6.87 (s, 4H,
H12); 6.98 (d, 4H, J = 7.5 Hz, H3,5). 13C-NMR (75.47 MHz,
CDCl3): 13.88 (C10); 15.30 (C7); 20.86 (p-CH3); 115.32 (C12);
118.93 (C2,6); 129.52 (C3,5); 133.26 (C4); 142.87 (C11); 147.08
(C1); 168.01, 168.17 (C8, C9). λmax (nm): 243, 360.
3.2.3
Synthesis of ligand L2
3.2.5
Synthesis of ligand L4
|
|
Ligand L2 was obtained from 2,6-dimethylaniline (2.42 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial ace-
tic acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
10 mmol). Yield: 2.67 g (59%). m.p. 158°C. IR [ν cm−1]:
1632 (νC=N). Anal. Calc. for C30H34N4 (450.62): C, 79.96; H,
7.61; N, 12.43. Found: C, 80.17; H, 8.09; N, 11.74. 1H-NMR
(300 MHz, CDCl3): 2.19 (s, 12H, o,o’-CH3); 2.25 (s, 6H,
C10H3); 2.39 (s, 6H, C7H3); 6.87 (s, 4H, H12); 7.06 (m, 6H,
H3,4,5). 13C-NMR (75.47 MHz, CDCl3): 15.74 (C10); 17.48
(C7); 17.67 (o,o’-CH3); 120.01 (C12); 123.21 (C3,5); 124.63
(C4), 127.91 (C2,6); 142.00 (C11); 147.08 (C1); 167.84, 168.10
(C8, C9). λmax (nm): 241, 367.
Ligand L4 was obtained from 4-ethylaniline (2.93 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial ace-
tic acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
10 mmol). Yield: 2.21 g (65%). m.p. 156°C. IR [ν cm−1]:
1633 (νC=N). Anal. Calc. for C30H34N4 (450.62): C, 79.96; H,
7.61; N, 12.43. Found: C, 80.23; H, 7.35; N, 12.42. 1H-NMR
(300 MHz, CDCl3): 1.27 (t, 6H, J = 6.9 Hz, CH3-CH2); 2.17
(s, 12H, C10H3+C7H3); 2.66 (q, 4H, J = 6.9 Hz, CH3-CH2);
6.71 (d, 4H, J = 7.2 Hz, H2,6); 6.84 (s, 4H, H12); 7.19 (d, 4H,
J = 6.6 Hz, H3,5). 13C-NMR (75.47 MHz, CDCl3): 13.81
(C10); 15.22 (C7); 15.74 (CH3-Et); 28.28 (CH2-Et); 115.27
(C12), 118.91 (C2,6); 128.23 (C3,5); 134.46 (C4); 144.06 (C11);
147.34 (C1); 168.23, 168.39 (C8, C9). λmax (nm): 244, 357.
3.2.4
Synthesis of ligand L3
|
3.2.6
Synthesis of ligand L5
|
Ligand L3 was obtained from 4-methylaniline (2.14 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial ace-
tic acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
Ligand L5 was obtained from 2,4,6-trichloroaniline (3.93 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial acetic

6 of 7
MECHRIA And MSAddEK
|
acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
10 mmol). Yield: 5.17 g (43%). m.p. 156°C. IR [ν cm−1]:
1629 (νC=N). Anal. Calc. for C26H20Cl6N4 (601.17): C, 51.95;
H, 3.35; N, 9.32. Found: C, 52.38; H, 4.07; N, 8.96. 1H-NMR
(300 MHz, CDCl3): 2.04 (s, 6H, CH3); 2.18 (s, 6H, CH3);
6.97 (s, 4H, H12); 7.19 (s, 4H, H3,5). 13C-NMR (75.47 MHz,
CDCl3): 16.19 (C10); 17.38 (C7); 121.74 (C12); 127.89 (C3,5);
130.17 (C2,6); 134.78 (C4); 143.15 (C11); 147.08 (C1); 167.14,
167.87 (C8, C9). λmax (nm): 242, 361.
a half equivalent of para-phenyenediamine yielded the bis-
α-diimine ligands. These ligands have been characterized
by spectroscopic and eventually elemental analysis. The
representative ligand L1 was studied by single crystal X-ray
analysis. As continuation for this work, the coordination of
these ligands with nickel(II) and palladium(II) metal centers
was progressed.
ACKNOWLEDGMENTS
The authors thank USCR, D-RX service at the faculty of sci-
ences of Sfax, Sfax University, for the realization of single
crystal DRX analysis.
3.2.7
Synthesis of ligand L6
|
Ligand L6 was obtained from 4-chloroaniline (2.55 g,
20 mmol), butane-2,3-dione (1.72 g, 20 mmol), glacial ace-
tic acid (0.4 g, 6.7 mmol), and p-phenylenediamine (1.08 g,
10 mmol). Yield: 4.45 g (48%). m.p. 156°C. IR [ν cm-1]:
1625 (νC=N). Anal. Calc. for C26H20Cl6N4 (601.17): C,
51.95; H, 3.35; N, 9.32. Found: C, 52.73; H, 4.06; N, 9.16.
1H-NMR (300 MHz, CDCl3): 1.97 (s, 6H, CH3); 2.11 (s, 6H,
CH3); 7.03 (d, 4H, J = 7.4 Hz, H2,6); 7.14 (s, 4H, H12); 7.39
(d, 4H, J = 6.8 Hz, H3,5). 13C-NMR (75.47 MHz, CDCl3):
16.19 (C10); 16.84 (C7); 121.63 (C12); 123.67 (C2,6); 128.39
(C3,5); 132.35 (C4); 145.03 (C11); 148.08 (C1); 168.20, 168.61
(C8, C9). λmax (nm): 241, 353.
ORCID
Ali Mechria
http://orcid.org/0000-0003-3203-1357
REFERENCES
[1] S. D. Ittel, L. K. Johnson, M. Brookhart, Chem. Rev. 2000, 100,
1169.
[2] Z. Wang, Q. Liu, G. A. Solan, W.-H. Sun, Coord. Chem. Rev.
2017, 350, 68.
[3] W. Zhang, W.-H. Sun, C. Redshaw, Dalton Trans. 2013, 42, 8988.
[4] R. Gao, W.-H. Sun, C. Redshaw, Catal. Sci. Technol. 2013, 3,
1172.
3.2.8
Solid state structure determination
|
[5] S. Budagumpi, S. Endud, Organometallics 2013, 32, 1537.
[6] F. Speiser, P. Braustein, L. Saussine, Acc. Chem. Res. 2005, 38,
784.
[7] S. Mecking, Angew. Chem. Int. Ed. 2001, 40, 534.
[8] W. Zhang, W.-H. Sun, Prog. Chem. 2005, 17, 310.
[9] V. C. Gibson, S. K. Spitzmesser, Chem. Rev. 2003, 103, 283.
[10] T. Hu, L. M. Tang, X. F. Li, Y. S. Li, N. H. Hu, Organometallics
2005, 24, 2628.
X-ray quality crystals of L1 were grown from an ethanolic
solution upon standing at ambient temperature. Intensity
data were collected at ambient temperature on a Bruker AXS
Kappa-CCD Apex II diffractometer equipped with graphite
monochromated MoKα radiation.
Reflection data were corrected for Lorentz-polarization
effects but not for absorption. The structure was solved by
direct methods and subsequent difference Fourier techniques
(SIR-92)[39] and refined with SHELXL-2013.[40] Non-
hydrogen atoms were refined with anisotropic thermal pa-
rameters. C-bound hydrogen atoms were located as residual
electron density peaks and refined isotropically without any
restraints or placed in idealized positions on parent atoms in
the final refinement. Details of the crystal parameters, data
collection, and structure refinement are given in Table 1.
[11] D. Zhang, G. X. Jin, Organometallics 2003, 22, 2851.
[12] S. Jie, D. Zhang, T. Zhang, W. H. Sun, J. Chen, Q. Ren, D. Liu, G.
Zheng, W. Chen, J. Organomet. Chem. 2005a, 690, 1739.
[13] J. P. Taquet, O. Siri, P. Braunstein, Inorg. Chem. 2006, 45, 4668.
[14] C. Bianchini, L. Gonsalvi, W. Oberhauser, D. Semeril, P.
Bruggeller, R. Gutmann, J. Chem. Soc., Dalton Trans. 2003, 20,
3869.
[15] A. Tomov, K. Kurtev, J. Mol. Catal. A: Chem. 1995, 103, 95.
[16] G. Noël, J. C. Röder, S. Dechert, H. Pritzkow, L. Bolk, S.
Mecking, F. Meyer, Adv. Synth. Catal. 2006, 348, 887.
[17] J. D. A. Pelletier, Y. D. M. Champouret, J. Cadarso, L. Clowes,
M. Gañete, K. Singh, V. Thanarajasingham, G. A. Solan, J.
Organomet. Chem. 2006, 691, 4114.
4
CONCLUSION
|
[18] S. Zhang, W. H. Sun, X. Kuang, I. Vystorop, J. Yi, J. Organomet.
Chem. 2007a, 692, 5307.
A series of novel pheny-bridged α-diimine ligands, namely
N,N′-Bis(3-(arylimino)butan-2-ylidene)benzene-1,4-
diamine L1–L6, have been prepared in a facile and versatile
one-pot 2-step manner under mild conditions in two succes-
sive condensation reactions. The mono-condensation of dia-
cetyl with one equivalent of substituted anilines led to the
corresponding iminoketone, which upon condensation with
[19] R. Chen, J. Bacsa, S. F. Mapolie, Polyhedron 2003, 22, 2855.
[20] S. Zhang, I. Vystorop, Z. Tang, W. H. Sun, Organometallics
2007b, 26, 2456.
[21] B. K. Bahuleyan, G. W. Son, D. W. Park, C. S. Ha, I. Kim, J.
Polym. Sci. A 1066, 2008, 46.
[22] B. K. Bahuleyan, U. K. Lee, C. S. Ha, I. Kim, Appl. Catal. A Gen.
2008, 351, 36.

MECHRIA And MSAddEK
7 of 7
|
[23] J. Kovach, M. Peralta, W. W. Brennessel, W. D. Jones, J. Mol.
Struct. 2011, 33, 992.
[30] P. Hohenberg, W. Kohn, Phys. Rev. 1964, 136, B864.
[31] W. Kohn, L. J. Sham, Phys. Rev. 1965, 140, A1133.
[32] A. D. Becke, J. Chem. Phys. 1993, 98, 5648.
[24] S. Jie, D. Zhang, T. Zhang, W.-H. Sun, J. Chen, Q. Ren, D. Liu, G.
Zheng, W. Chen, J. Organomet. Chem. 2005b, 691, 1739.
[25] E. Zadok, S. Rubinraut, F. Frolow, Y. Mazur, J. Org. Chem. 1985,
50, 2647.
[33] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785.
[34] S. H. Vosko, L. Wilk, M. Nusair, Can. J. Phys. 1980, 58, 1200.
[35] P. J. Stephens, F. J. Devlin, C. F. Chabalowski, M. J. Frisch, J.
Phys. Chem. 1994, 98, 11623.
[26] D. X. West, A. A. Nassar, F. A. ElSaied, M. I. Ayad, Transit. Met.
Chem. 1998, 23, 423.
[36] W. Ko, P. C. Hariharan, J. A. Pople, Theoret. Chimica Acta 1973,
28, 213.
[27] A.B.P. Lever (ed.), Inorganic electronic spectroscopy, Elsevier,
Amsterdam, The Netherlands 1968.
[37] M. M. Francl, W. J. Petro, W. J. Hehre, J. S. Binkley, M. S. Gordon,
D. J. DeFrees, J. A. Pople, J. Chem. Phys. 1982, 77, 3654.
[38] T. Clark, J. Chandrasekhar, G. W. Spitznagel, P. V. R. Schleyer, J.
Comp. Chem. 1983, 4, 294.
[28] H. Allen, Acta Cryst. B 2002, 58, 380.
[29] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.
A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A.
F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M.
Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima,
Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery Jr.,
J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers,
K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K.
Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi,
M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross,
V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. Ochterski, R. L.
Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, GAUSSIAN 09
(Revision A.02), Gaussian, Inc., Wallingford, CT 2009.
[39] A. Altomare, M. C. Burla, G. Camalli, G. Cascarano, C.
Giacovazzo, A. Gualiardi, G. Polidori, J. Appl. Cryst. 1994, 27,
435.
[40] G. M. Sheldrick, Acta Cryst. 2008, A64, 112.
How to cite this article: Mechria A, Msaddek M.
Synthesis, characterization, and crystal structure of
novel bulky phenyl-bridged α-diimine binucleating
ligands. Heteroatom Chem. 2018;e21424.
https://doi.org/10.1002/hc.21424