Bidentate and tetradentate β-aminovinyl trifluoromethylated ketones and their copper(II) complexes: Synthesis, characterization and redox chemistry

Article abstract of DOI:10.1002/ejic.201101385

New polyfunctional bidentate and tetradentate trifluoromethylated enaminone ligands that bear redox-active and photosensitive moieties were synthesized in moderate to good yields and their coordination chemistry with copper(II) was examined. The crystal s

Full text of DOI:10.1002/ejic.201101385

FULL PAPER
DOI: 10.1002/ejic.201101385
Bidentate and Tetradentate β-Aminovinyl Trifluoromethylated Ketones and
Their Copper(II) Complexes: Synthesis, Characterization and Redox Chemistry
Nicolas Chopin,[a] Maurice Médebielle,*[a] and Guillaume Pilet*[b]
Keywords: Electrochemistry / UV/Vis spectroscopy / Copper / Fluorine
New polyfunctional bidentate and tetradentate trifluoro-
methylated enaminone ligands that bear redox-active and
photosensitive moieties were synthesized in moderate to
good yields and their coordination chemistry with copper(II)
was examined. The crystal structures revealed the formation
of mononuclear CuII complexes with all ligands, where the
metal ion is located in almost perfect to distorted square
planar environments. The deviation from an ideal square
plane influences the redox potentials of the metal centre
within the complex as demonstrated by cyclic voltammetry.
For all the complexes, a stable CuI species was evidenced by
a quasireversible reduction step at potentials from –0.48 to
–1.08 V (potential standards E0), but the most stable CuI spe-
cies originated from the CuII complex with the tetradentate
ligand. UV/Vis absorption spectra revealed no major differ-
ences between the ligands and their CuII complexes.
aminone derivative of 3-imidazoline nitroxide has also been
published, and the presence of weak ferromagnetic interac-
tions between the metal centres has been evidenced.[22] In
addition, the crystal structures of CuII, NiII and PdII
bischelates with a trifluoromethylated enamino ketone de-
rivative of 2-imidazoline nitroxide are also known.[23] In
parallel, the redox chemistry of fluorinated enaminones and
their metal complexes has been studied,[24] which showed
that the reduction of the ligands in N,N-dimethylformamide
(DMF) was irreversible and gave unstable radical anions as
reduction products, and the corresponding CuII and NiII
chelates were characterized in most cases by a quasirevers-
ible one-electron transfer. Most of the enaminones pre-
sented in that study did not feature possible multiple coor-
dination sites, and no extension with potential applications
in materials science, catalysis or as potential new metallo-
drugs has appeared in the literature.
Introduction
Trifluoromethylated β-aminovinyl ketones have been fre-
quently used as building blocks to prepare various tri-
fluoromethylated aromatic and heterocycle molecules.[1]
The ability of enaminones to coordinate to a variety of
transition metals has led to the preparation of a number of
metallomesogens with interesting liquid crystal proper-
ties[2–5] and highly active catalysts for olefin polymerization,
which include fluorinated enaminones.[6–8] β-Aminovinyl
ketones with a fluoroalkyl moiety are interesting organic
precursors that can be decorated in a number of useful syn-
thetic sequences to produce diverse molecular entities with
specific applications.[1,9–21] Their potentially broad coordi-
nation chemistry[21–29] combined with appropriate organic
functionalities make them attractive for the design of a new
generation of original materials with potential in catalysis,
molecular magnetism and therapeutic applications. A series
of fluorinated enaminones that bear two independent coor-
dination centres have been obtained, and the crystal struc-
ture of a CuII complex has been reported.[21] The crystal
structure of a MnII complex with a trifluoromethylated en-
We have recently launched a research program dedicated
to the development of efficient and mild synthetic ap-
proaches for the synthesis of polyfunctional enaminones
that bear a fluoroalkyl moiety with the aim to deliver useful
enaminone building blocks, which offer the potential to
generate molecular diversity (Figure 1).
[a] Université de Lyon and Université Claude Bernard Lyon 1,
Institut de Chimie et Biochimie Moléculaires et Supramolécul-
aires (ICBMS), UMR CNRS-UCBL-INSA Lyon 5246, Equipe
“Synthèse de Molécules d’Intérêt Thérapeutique (SMITH)”,
Bât. Curien, 43 boulevard du 11 novembre 1918,
69622 Villeurbanne cedex, France
E-mail: maurice.medebielle@univ-lyon1.fr
[b] Université de Lyon and Université Claude Bernard Lyon 1,
Laboratoire des multiMatériaux et Interfaces, UMR CNRS-
UCBL,
5615, Bât. Chevreul, 43 boulevard du 11 novembre 1918, 69622
Villeurbanne cedex, France
E-mail: guillaume.pilet@univ-lyon1.fr
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201101385.
Figure 1. Fluoroalkylated enaminone.
Eur. J. Inorg. Chem. 2012, 1093–1103
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Nicolas Chopin, M. Médebielle, G. Pilet
FULL PAPER
These organic substrates can be structurally modified at fluoroalkylated enaminone ligands were not broad (R1 and
different sites (R1, R2, R3 and R4), by variation of the R2 in Figure 1), few crystal structures and no electrochemi-
amine (R1), the substitution on the C=C bond (R2 and R3) cal data have been reported. Significant attention has fo-
and at the fluoroalkyl moiety (R4).[14–20] In principle, or- cused on the influence of tetrahedral distortion in four-co-
ganic functionalities with specific properties can be at- ordinate copper complexes on their redox potentials in or-
tached at the four positions of the enaminone from readily der to understand and mimic functions of different families
available starting materials using different synthetic strate- of copper proteins.[38–40]
gies. The fluorine atoms are significant as they may induce
specific interactions in the solid state such as F···H, F···F,
F···O=C, F···N and F···S contacts; these properties have
been used with success in materials science and crystal engi-
neering,[30–31] in medicinal chemistry in order to design
more active drug candidates and have been exemplified by
cocrystallized structures of potent therapeutic agents with
target enzymes.[32–34] Fluorine is also a useful probe in 19F
NMR spectroscopy with potential implications in bio-
logy.[35] In addition, the electron-withdrawing effect of
fluorine should alter the redox properties of the ligands and
metal complexes and could help cocrystallization due to the
enhanced volatility of the latter.[27]
In continuation of our recent studies on the design of
new polyfunctional enaminone-based ligands and their
metal complexes, which can be used as new materials and
are potential therapeutic agents, we wish to present the syn-
theses of a series of bidentate (NO) and tetradentate (N2O2)
enaminone-based ligands (Figures 2 and 3). In the study
presented herein, the explorative coordination chemistry of
these original ligands with CuII will be presented as well as
their structures, which are tentatively correlated to their re-
dox chemistry in solution. Bidentate enaminones with a
fluoroalkyl moiety are known to some extent, whereas
tetradentate ligands and their metal complexes are less
studied.[36,37] The structural variations of the reported
Figure 3. Tetradentate ligands L8H2–L13H2.
In this work, as our long-term goal is to study the inter-
action of a defined entity with a specific property with the
redox metal centre, R1 or R2 were first modified with
photosensitive (and redox active) entities (azobenzene,
anthracene) and a redox-active unit (tetrathiafulvalene).
Results and Discussion
Ligand Syntheses
The structures of the trifluoromethylated β-aminovinyl
ketones (enaminones) are presented in Figures 2 and 3.
L1H–L7H are bidentate, and L8H2–L13H2 were designed
to be tetradentate. L1H–L4H were prepared in good to ex-
cellent yields (72–98%) in two straightforward steps: tri-
fluoroacetylation of commercially available ethyl vinyl ether
[trifluoroacetic anhydride (TFAA)/pyridine in anhydrous
Figure 2. Bidentate ligands L1H–L7H.
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dichloromethane], followed by an O–N exchange reaction
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Eur. J. Inorg. Chem. 2012, 1093–1103

CuII Complexes of Bi- and Tetradentate Ketones
of the crude (E)-4-ethoxy-1,1,1-trifluorobut-3-en-2-one (1)
[41]
with the appropriate amines (commercially available) in
anhydrous acetonitrile (Scheme 1).
Scheme 1. Synthesis of L1H–L4H. Reagents and conditions:
a) TFAA (1.0 equiv.), pyridine (1.0 equiv.), dichloromethane, room
temp.; 18 h; b) amine R1–NH2 (1.0 equiv.), acetonitrile, room
temp.; 5 h. L1H Ͼ 95%, L2H Ͼ 95%, L3H 94%, L4H 72%.
L1H and L2H were prepared in quantitative yields ac-
cording to known procedures.[42,43] L5H, which bears a
tetrathiafulvalene (TTF) moiety, was prepared in 25% yield
from a Stille reaction between the stannylated-TTF 2[44] and
L2H (Scheme 2). This procedure was found to be more
practical (no chromatographic purification) than the cou-
pling reaction of the crude 1 with the precursor amine due
to solubility problems and tedious purification of the inter-
mediates.
Scheme 3. Synthesis of L6H–L13H2. Reagents and conditions:
a) (EtO)3CH (1.5 equiv.), p-CH3C6H4SO3H (0.7 mol-%), MeOH,
60 °C, 24 h; 5 Ͼ 95%, 6 Ͼ 95%; b) TFAA (2.0 equiv.), pyridine
(4.0 equiv.), dichloromethane, 45 °C; 8–72 h; 7 84%, 8 60%; c) R2–
NH2 (1.0 equiv.), 8 (1.0 equiv.), acetonitrile, room temp.; 5 h; L6H
68%, L7H 60%; d) diamine (0.5 equiv.), 7 or 8 (1.0 equiv.), acetoni-
trile, room temp.; 4 h; L8H2 54%, L9H2 50%, L10H2 60%, L11H2
42%, L12H2 48%, L13H2 63%.
Syntheses of CuII Complexes
The corresponding CuII complexes were generally pre-
pared in good yields (Ͼ 70%) through dropwise addition of
a methanolic solution of CuCl2·2H2O (0.75 equiv. for bi-
dentate ligands and 1.50 equiv. for the tetradentate ligands)
to a dichloromethane solution of the ligand that contained
Et3N (4 equiv.). The resulting green or brown solution was
stirred for two hours at room temperature and concentrated
to give a precipitate, which was washed with cold methanol
or purified by filtration through silica gel (elution with
dichloromethane) to give the desired complexes as green or
brown powders. Slow evaporation of a dichloromethane/
methanol (1:1) solution {with a small amount of toluene
for [Cu(L4)2]} gave single crystals suitable for single-crystal
XRD. The copper complexes of L1H, L3H, L6H and
L12H2 were obtained by following this procedure systemati-
cally.
Scheme 2. Synthesis of L5H. Reagents and conditions: a) TTF
(1.0 equiv.), nBuLi (1.0 equiv.), Bu3SnCl (1.0 equiv.), tetra-
hydrofuran (THF), –78 °C to room temp.; 1 h; 2 Ͼ 95%; b) L2H
(1.0 equiv.), Pd(PPh3)4 (5 mol-%), toluene, reflux, 48 h. L5H 25%.
L6H–L7H and L8H2–L13H2 were prepared in moderate
unoptimized yields in three straithforward steps: acetaliza-
tion of suitable ketones 3 and 4, trifluoroacetylation of di-
methyl acetals 5 and 6 using a combination of TFAA
(2 equiv.) and pyridine (4 equiv.) in anhydrous dichloro-
methane and an O–N exchange reaction of the resulting
methoxyvinyl trifluoromethyl ketones 7 and 8 with the cor-
responding amines and diamines in anhydrous acetonitrile
(Scheme 3). The ketone that bears the azobenzene unit 3 is
mentioned in the literature[45] without full spectroscopic
data; it was prepared in 71% isolated yield from p-amino-
acetophenone and nitrosobenzene (both commercially
available) in acetic acid at 90 °C overnight. Ketone 4 was
commercially available.
Crystal Structure Description
All the ligands were obtained as Z isomers, as deter-
The formulas obtained from the single-crystal XRD
mined by 1H NMR spectroscopy, which showed a de- characterization of the complexes are [Cu(L1)2] (A),
shielded peak of the amino proton at Ͼ 10.0 ppm due to [Cu(L3)2] (B), [Cu(L6)2] (C) and [Cu(L12)]·0.5(MeOH)·
hydrogen bonding between NH and C=O. The ligands were 0.5(AcOEt) (D). Details of structural refinement can be
isolated as solids and were generally purified by silica gel found in Table 2. The crystal structures of L4H, L10H2 and
chromatography.
[Cu(L8)2] (E) can be found in the Supporting Information.
Eur. J. Inorg. Chem. 2012, 1093–1103
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Nicolas Chopin, M. Médebielle, G. Pilet
FULL PAPER
All of the neutral CuII-based complexes are mononuclear half of the value of the mean trans ligand–metal–ligand an-
and the metal ion is located in a more or less distorted gle, which is 90° for square planar geometry (D4h) and 54.7°
square planar N2O2 environment (Figure 4).
for tetrahedral geometry (Td). A new parameter, τ4,[46] has
been introduced in order to index four-coordinate com-
plexes, which corresponds to the sum of angles α and β, the
two largest angles in the four-coordinate species, subtracted
from 360° and divided by 141°. The value of τ4 ranges from
0.00 to 1.00 for perfect square planar and perfect tetrahe-
dral geometries, respectively. All these parameters for A, B,
C and D are summarized in Table 1.[39]
Figure 5. Illustration of planes between which the deviation from
an ideal square plane can be evaluated (ω parameter).
Table 1. Correlation between CuII/CuI redox potentials and param-
eters that evaluate the deviation from an ideal square planar metal
environment for A, B, C and D.
Complex Substitu-
tion
Coordination
mode
E0 [a] [V]/β [°]/ω [°]/τ4
A
B
C
phenyl
bidentate
–0.57/72.6/47.9/0.49
–0.48/90/6.7/0.0
–0.69/90/0.0/0.0
Figure 4. Structures of A, B, C and D.
azobenzene bidentate
azobenzene bidentate
anthracene
anthracene
–
[a] Potential standard E0 = (Epc + Epa)/2.
A, B and C are built from two monodeprotonated biden-
tate ligands (L1–, L3– and L6–, respectively), whereas D is
constructed from one doubly deprotonated tetradentate li-
gand (L122–). The metal ion is then coordinated to the en-
aminone pincer part. Cu–O,N bond lengths within the four
D
tetradentate
–1.08/88.3/14.5/0.05
In conclusion, the CuII environment within B and C is
complexes are similar: 1.910(3) and 1.941(3) Å for A, almost perfectly square planar, whereas the environment de-
1.897(3) and 2.008(4) Å for B, 1.897(4) and 2.018(4) Å for viates from ideal for D and A. The potential standards of
C and from 1.897(6) to 1.958(6) Å for D, which are in good the first CuII/CuI step should be affected by (i) the degree
agreement with literature values.[27,28]
of tetrahedral distortion in four-coordinate complexes, (ii)
A study of the N,O–Cu–N,O bond angles illustrates the the presence of different kinds of substituents on the ligand
distortion of the CuII square planar environment. In B and (steric and geometric effects, see below) and (iii) the nature
C, these angles are close to the theoretical values of 90 and of the solvent (coordinating vs. noncoordinating). Our X-
180° [88.6(1)–91.4(1)° and 180° for B and 88.9(2)–91.1(2)° ray data (Table 2) combined with our preliminary electro-
and 180° for C], whereas in A and D, the deviation from the chemical data recorded in a coordinating solvent (DMF)
expected values is greater [94.6(1)–95.4(1)° and 140.4(2)– seem to indicate that the closer the environment is to tetra-
150.1(2)° for A and 83.5(1)–95.1(1)° and 175.4–177.9° for hedral as in A (which is the preferred environment for a CuI
D].
ion), the more easily the metal will be reduced (compared
A second way to evaluate the distortion from an ideal with C and D). In addition, the fact that the CuII/CuI step
square planar environment is to measure the angle, the ω in the tetradentate complex was found to be fully reversible
parameter, between the planes formed by the enaminone may be due to some stabilization from the solvent and delo-
moiety of two ligands (A, B and C) with the central metal calization. Lastly, in the structures of A, B, C and D, each
atom or of one ligand (D) with the CuII ion (Figure 5). An- mononuclear complex is isolated from its neighbor, and the
other parameter, β, which is used to evaluate the distortion structural cohesion is maintained by F···H bonds, which
of the local geometry of the metal centre, is defined as a form a dense network.
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Eur. J. Inorg. Chem. 2012, 1093–1103

CuII Complexes of Bi- and Tetradentate Ketones
Table 2. Structural refinement for A, B, C and D.
A
B
C
D
Formula
C20H14CuF6N2O2
491.88
monoclinic
C2/c
C32H22CuF6N6O2
700.09
C60H38CuF6N6O2
1052.53
monoclinic
C2/c
C44.5H30CuF6N2O3.5
826.26
monoclinic
P21/c
FW (gmol–1)
Crystal system
Space group
triclinic
¯
P1
a [Å]
b [Å]
c [Å]
α [°]
22.776(7)
8.497(1)
12.287(4)
90
119.67(4)
90
6.989(1)
8.500(1)
13.420(2)
80.09(1)
76.34(1)
81.45(1)
758.3(2)
1
33.676(3)
5.9851(4)
31.178(3)
90
120.19(1)
90
22.895(3)
22.866(2)
14.306(2)
90
100.06(1)
90
β [°]
γ [°]
V [Å3]
2066.0(13)
4
5432(1)
4
7374(1)
8
Z
T [K]
293
1.581
0.439
293
1.533
0.798
293
1.285
0.469
100
1.495
0.673
D [gcm–3]
μ [mm–1]
Independent reflections
Rint
2332
0.041
0.0540
0.1123
0.96
3557
0.057
0.0584
0.1067
0.93
5343
0.060
0.0830
0.1729
0.89
17487
0.100
0.0783
0.1697
1.00
R (F2)
Rw (F2)
S
Number of reflections
Number of parameters
Δρmax [e– Å–3]
Δρmin [e– Å–3]
Absorption correction
2327
142
0.65
–0.55
3556
215
0.88
–1.36
5340
340
1.45
–1.12
17487
1028
2.11
–2.18
analytical
analytical
analytical
analytical
Electrochemistry of the Ligands
dation (ca. + 1.65 V) at potentials between +1.11 and
+1.25 V (peak potential at 0.2 Vs–1) with L3H and L12H2
the easiest to be oxidized. The irreversible nature of these
steps corresponds to the formation of an unstable radical
cation of the enaminone moiety[47] and the anthracenyl
moiety for L6H and L12H2.[48] All the ligands exhibited a
first one-electron irreversible reduction step at –2.02, –1.56,
–1.46 and –1.58 V (peak potentials at 0.2 Vs–1) for L1H,
L3H, L6H and L12H2, respectively, which correspond to
the formation of unstable radical anions, with L6H the easi-
est to be reduced; the irreversible nature of these steps indi-
As a preliminary exploration, the redox behaviour of
L1H, L3H, L6H and L12H2 was examined in anhydrous
DMF that contained nBu4NPF6 as the supporting electro-
lyte. The data are collected in Table 3, and typical cyclic
voltammograms of L1H and L3H are presented in Fig-
ures 6 and 7, respectively (see Supporting Information for
the cyclic voltammograms of L6H and L12H2). All ligands
were oxidized irreversibly before the limit of solvent oxi-
Table 3. Electrochemical data for the reduction of L1H, L3H, L6H cates that a chemical reaction follows the initial electron
and L12H.
transfer and gives rise to the formation of a new product
and not the dianion.[49] For L1H, a second reversible re-
duction step was observed at –2.44 V (peak potential at
0.2 Vs–1; potential standard E0 = –2.38 V, peak separation
close to 0.12 V), which may be attributed to the reduction
of the product that was formed after the initial electron
transfer.[49] The other ligands gave additional reduction
steps due to the redox-active azobenzene and anthracenyl
moieties. For example, for the azobenzene-derived ligand
L3H, three reduction steps were observed at –1.78, –1.91
and –2.56 V (peak potentials at 0.2 Vs–1). The reduction
step at –1.78 V may be attributed to the reduction of the
product that resulted from the initial uptake of one elec-
tron, whereas the reduction step at –1.91 V is attributed to
the one-electron reversible reduction of the –N=N– of the
azobenzene moiety or from the product that resulted from
[a]
[b]
Epc [V]
Epa [V]
E0[c] [V]
–2.38 (E0 )
L1H
L3H
–2.02 (Epc1
–2.44 (Epc2
)
)
–2.32 (Epa2
+0.13 (Epa3
+1.24 (Epa4
–1.78 (Epa3
–2.30 (Epa4
–0.24 (Epa5
)
)
)
)
)
)
)
)
)
)
2
–1.56 (Epc1
–1.78 (Epc2
–1.91 (Epc3
–2.56 (Epc4
–1.46 (Epc1
–1.75 (Epc2
–1.94 (Epc3
–2.50 (Epc4
–2.90 (Epc5
–1.58 (Epc1
–1.82 (Epc2
–2.49 (Epc3
–2.94 (Epc4
–3.20 (Epc5
)
)
)
)
)
)
)
)
)
)
)
)
)
)
–1.84 (E0 )
3
–2.43 (E0 )
4
+1.11 (Epa6
L6H
–1.77 (Epa3
+0.23 (Epa6
+1.25 (Epa7
–1.85 (E0 )
3
L12H
–1.05 (Epa6
–0.70 (Epa7
–0.17 (Epa8
+0.25 (Epa9
+1.12 (Epa10
)
)
)
)
)
the initial electron transfer (potential standard E0
=
[a] Cathodic peak potential in DMF at 293 K with a glassy carbon
electrode and 0.1 m nBu4NPF6 as the supporting electrolyte; all po-
tentials are vs. Ag/Ag+ in acetonitrile, scan rate = 0.2 Vs–1. [b] An-
odic peak potential. [c] Potential standard E0 = (Epc + Epa)/2.
–1.84 V). The last reduction step at –2.56 V corresponds to
the quasireversible formation of the azobenzene di-
anion[50,51] (potential standard E0 = –2.43 V). Both ligands
Eur. J. Inorg. Chem. 2012, 1093–1103
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1097

Nicolas Chopin, M. Médebielle, G. Pilet
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also gave rise to irreversible oxidation steps at +0.13 V lected in Table 4, and typical cyclic voltammograms of
(L1H) and ca. –0.24 V (L3H), which were only observed [Cu(L1)2] and [Cu(L3)2] are presented in Figures 8 and 9,
after scanning the potential in the reductive direction and respectively {see Supporting Information for the cyclic vol-
correspond to the oxidation of the products formed after tammograms of [Cu(L6)2] and [Cu(L12)]}. All the com-
the initial one-electron transfer.[49]
Table 4. Electrochemical data for the reduction of [Cu(L1)2],
[Cu(L3)2], [Cu(L6)2] and [Cu(L12)].
E0[c] [V]
[a]
[b]
Epc [V]
Epa [V]
[Cu(L1)2]
[Cu(L3)2]
–0.85 (Epc1
–2.02 (Epc2
–2.63 (Epc3
–0.55 (Epc5
–0.80 (Epc6
–0.64 (Epc1
–1.72 (Epc2
–1.93 (Epc3
–2.53 (Epc4
–0.60 (Epc5
–0.75 (Epc6
–0.96 (Epc1
–1.79 (Epc2
–1.96 (Epc3
–2.31 (Epc4
–2.49 (Epc5
–2.93 (Epc6
–0.55 (Epc8
–0.70 (Epc9
–1.17 (Epc1
–2.17 (Epc2
–2.53 (Epc3
–2.99 (Epc4
–3.21 (Epc5
–0.60 (Epc9
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
)
–0.29 (Epa1
+0.18 (Epa4
+1.08 (Epa5
)
–0.57 (E0 )
1
)
)
+0.26 (E0 )[d]
5
–0.52 (E0 )[d]
6
[d]
[d]
[d]
–0.24 (Epa6
)
–0.32 (Epa1
–1.78 (Epa3
–2.31 (Epa4
)
)
)
–0.48 (E0 )
1
–1.85 (E0 )
3
–2.42 (E0 )
4
+1.17 (Epa5
)
+0.28 (E0 )[d]
5
–0.50 (E0 )[d]
[d]
[d]
6
[Cu(L6)2]
[Cu(L12)]
–0.43 (Epa1
–1.82 (Epa3
+0.18 (Epa7
+1.17 (Epa8
)
)
–0.69 (E0 )
1
–1.89 (E0 )
3
)
)
+0.31(E0 )[d]
8
–0.43 (E0 )[d]
9
[d]
–0.17 (Epa9
)
Figure 6. Cyclic voltammetry of L1H in anhydrous DMF + 0.1 m
nBu4NPF6, glassy carbon electrode, scan rate = 0.2 Vs–1, T =
293 K. (a) scanning potential from 0.0 to –3.0 V, –3.0 to +1.4 V
and +1.4 to 0.0 V; (b) Inset: scanning potential from 0.0 to –2.3 V
and –2.3 to 0.0 V; (c) Inset: scanning potential from 0.0 to +1.4 V
and +1.4 to 0.0 V.
[d]
[d]
–0.99 (Epa1
–0.63 (Epa6
–0.09 (Epa7
+0.29 (Epa8
+1.12 (Epa9
)
)
)
)
)
–1.08 (E0 )
1
+0.26(E0 )[d]
9
–1.13 (E0
)
[d]
10
[d]
[d]
–0.27 (Epa10
)
[d]
–0.86 (Epc10
)
[a] Cathodic peak potential in DMF at 293 K with a glassy carbon
electrode and 0.1 m nBu4NPF6 as the supporting electrolyte; all po-
tentials are vs. Ag/Ag+ in acetonitrile, scan rate: 0.2 Vs–1. [b] An-
odic peak potential. [c] Potential standard E0 = (Epc + Epa)/2. [d]
Appears only after scanning from 0.0 to +1.4 V and scanning back
to –1.0 V.
Figure 7. Cyclic voltammetry of L3H in anhydrous DMF + 0.1 m
nBu4NPF6, glassy carbon electrode, scan rate = 0.2 Vs–1, T =
293 K. (a) scanning potential from 0.0 to –3.0 V, –3.0 to +1.3 V
and +1.3 to 0.0 V; (b) Inset: scanning potential from 0.0 to –1.7 V
and –1.7 to 0.0 V; (c) Inset: scanning potential from 0.0 to +1.3 V
and +1.3 to 0.0 V.
Electrochemistry of the CuII Complexes
Figure 8. Cyclic voltammetry of [Cu(L1)2] in anhydrous DMF +
0.1 m nBu4NPF6, glassy carbon electrode, scan rate = 0.2 Vs–1, T
= 293 K. (a) scanning potential from 0.0 to –3.2 V, –3.2 to +1.4 V
and +1.4 to 0.0 V; (b) Inset: scanning potential from 0.0 to –1.5 V
and –1.5 to 0.0 V; (c) Inset: scanning potential from 0.0 to +1.4 V,
For comparison and in order to study the influence of
the metal ion coordination to the ligand, the redox chemis-
try of the CuII complexes of L1H, L3H, L6H and L12H2
was also examined in anhydrous DMF that contained
nBu4NPF6 as the supporting electrolyte. The data are col- +1.4 to –1.0 V and –1.0 to 0.0 V.
1098 Eur. J. Inorg. Chem. 2012, 1093–1103
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

CuII Complexes of Bi- and Tetradentate Ketones
plexes gave rise to a one-electron quasireversible reduction ciated with the π–π* transition of the azobenzene moiety.
step, which corresponds to a CuII/CuI process, at –0.57 V Usually this type of transition is accompanied by isomeriza-
(potential standard E0) for [Cu(L1)2], –0.48 V (potential tion of the –N=N– unit and the conversion from E to Z
standard E0) for [Cu(L3)2], –0.69 V (potential standard E0) configuration. For L6H and [Cu(L6)2], a superposition of
for [Cu(L6)2] and –1.08 V (potential standard E0) for the characteristic profile of the fine structure of anthracene
[Cu(L12)]. Additional reduction steps were generally ob- between 230 and 360 nm is observed with an absorption
served at more negative reduction potentials, which corre- maximum at 251 nm in both cases and with the π–π* transi-
spond to the reduction of the ligand. The CuI species was tion of the azobenzene at 386 and 382 nm, respectively. Fi-
the most stable for [Cu(L12)] with the tetradentate ligand nally, the different π–π* transitions of the anthracene moi-
as evidenced by the smallest peak separation (ΔEp = Epc1
–
ety for L12H and [Cu(L12)] are also present with a lower
E
pa1 = 0.18 V) and the smallest ipc1/ipa1 ratio (ipc1 = cathodic band intensity for [Cu(L12)], probably due to a difference
current at Epc1, ipa1 = anodic current at Epa1). The com- in geometry between the free ligand and the complex. Re-
plexes gave rise to an irreversible oxidation step generally garding the spectra of the complexes, the forbidden d–d
located at potentials (peak potentials at 0.2 Vs–1) roughly transitions are too weak compared to the photosensitive
equal to the oxidation step observed in the corresponding moieties to be clearly observed at this concentration.
ligands (Table 3). On scanning back to the negative poten-
Table 5. UV/Vis absorptions of the ligands and complexes.
tials, this oxidation led to the appearance of two additional
[a]
λ [nm]
ε
[Lmol–1 cm–1]
reduction steps (between 0.0 and –1.0 V) with a typical re-
dissolution peak for Cu0 (close to –0.2 V). As such a redis-
solution peak was not observed with the ligands when
scanned only in the reductive direction, it is possible that
the oxidation of the CuII complexes gave rise to CuIII spe-
cies that are further reduced in two stepwise reduction steps,
which correspond to the CuIII/CuII and CuII/Cu0 transi-
tions.
L1H
[Cu(L1)2]
L3H
355 (λmax
356 (λmax
381 (λmax
≈ 300
)
)
)
19175
24656
26020
≈ 245
[Cu(L3)2]
376 (λmax
)
41959
≈ 296
386
354
L6H
334
251 (λmax
382
)
67154
[Cu(L6)2]
354
334
251 (λmax
≈ 353
331
245 (λmax
≈ 353
336
)
)
)
121510
179521
116680
L12H2
[Cu(L12)]
257 (λmax
[a] The molar extinction coefficient ε is calculated for λmax
.
Figure 9. Cyclic voltammetry of [Cu(L3)2] in anhydrous DMF +
0.1 m nBu4NPF6, glassy carbon electrode, scan rate = 0.2 Vs–1, T
= 293 K. (a) scanning potential from 0.0 to –3.0 V, –3.0 to +1.3 V
and +1.3 to 0.0 V; (b) Inset: scanning potential from 0.0 to –1.0 V
and –1.0 to 0.0 V; (c) Inset: scanning potential from 0.0 to +1.3 V,
+1.3 to –1.0 V and –1.0 to 0.0 V.
Spectroscopic Properties
UV/Vis absorption spectra indicate similar profiles be-
tween the different ligands and their corresponding copper
complexes (Table 5). For L1H, an intense band is observed
at 355 nm, and one at 356 nm is observed for [Cu(L1)2].
This absorption is typical of the different π–π* transitions
of the phenyl ring and the enaminone moiety. For L3H and
Figure 10. UV/Vis spectra of L3H (black line) and [Cu(L3)2]
(dashed line) in dichloromethane.
In summary, the UV/Vis absorption measurements show
[Cu(L3)2] (Figure 10), absorption maxima at 381 and that the properties of the different ligands are retained in
376 nm were measured, respectively. These bands are asso- the corresponding copper complexes.
Eur. J. Inorg. Chem. 2012, 1093–1103
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1099

Nicolas Chopin, M. Médebielle, G. Pilet
FULL PAPER
cipitate was washed with cold acetonitrile, filtered and the filtrate
concentrated and purified by silica gel chromatography (PE/AcOEt
Conclusions
The synthesis, structural, UV/Vis and electrochemical = 8:2 for L1H, L3H, PE/DCM = 1:1 for L2H and DCM for L4H).
characterization of a series of original multidentate ligands
(Z)-1,1,1-Trifluoro-4-[4-{(E)-phenyldiazenyl}phenylamino]but-3-en-
and their CuII complexes were achieved. The redox chemis-
2-one (L3H): Yield 94 %; yellow solid; m.p. 187 °C. 1H NMR
try of the enaminone electroactive ligands was investigated
(300 MHz, CDCl3): δ = 11.86 (br. d, J = 12.3 Hz, 1 H), 7.99 (d, J
= 8.7 Hz, 2 H), 7.91 (dd, J = 8.4, 1.8 Hz, 2 H), 7.71 (dd, J = 12.9,
as well as the electrochemical behaviour of the correspond-
ing CuII complexes. All the complexes exhibited a quasire-
7.5 Hz, 1 H), 7.51 (m, 3 H), 7.26 (d, J = 9.0 Hz, 2 H), 5.73 (d, J =
7.5 Hz, 1 H) ppm. 19F NMR (282 MHz, CDCl3): δ = –77.6 (s) ppm.
versible or reversible redox process in DMF, which corre-
sponds to the formation of a stable CuI species with a low HRMS (ESI): calcd. for C16H11F3N3O [M – H]– 318.08597; found
318.0861. C16H12F3N3O (319.28): calcd. C 60.19, H 3.79, N 13.16;
found C 60.42, H 3.64, N 13.18.
reduction potential, the most stable of which had a tetra-
dentate ligand. The UV/Vis spectra show that the properties
of the different ligands are retained in the corresponding
copper complexes, which means that metal coordination
does not have a dramatic impact.
(Z)-4-(Anthracen-2-ylamino)-1,1,1-trifluorobut-3-en-2-one (L4H):
Yield 72%; green-yellow solid; m.p. Ͼ 220 °C. 1H NMR (300 MHz,
CDCl3): δ = 12.06 (br. d, J = 12.3 Hz, 1 H), 8.41–8.36 (m, 2 H),
8.11–7.99 (m, 3 H), 7.90–7.84 (m, 2 H), 7.68 (s, 1 H), 7.50–7.48 (m,
Work is underway to extend current chemical methodol-
ogies to more elaborate ligands that bear new specific enti- 2 H), 5.74 (d, J = 7.2 Hz, 1 H) ppm. 19F NMR (282 MHz, CDCl3):
δ = –77.5 (s) ppm. HRMS (ESI): calcd. for C18H13F3NO
[M + H]+ 316.09438; found 316.0941. C18H12F3NO (315.29): calcd.
C 68.57, H 3.84, N 4.44; found C 68.61, H 4.01, N 4.66.
ties as well as to study the possible coordination chemistry
with metals other than copper. The identification of the re-
duction and oxidation products and a proposed detailed
mechanism for the redox chemistry of the ligands and com-
plexes in solvents with different coordinating abilities will
be performed in due course. The application of the copper
(3Z)-4-[(4-{2-(1,3-Dithiol-2-ylidene)-1,3-dithiol-4-yl}phenyl)amino]-
1,1,1-trifluorobut-3-en-2-one (L5H): To a solution of tetrathiaful-
valene (400 mg, 1.96 mmol) in anhydrous THF (15 mL) was added
complexes in catalysis and as potent metallodrugs are our dropwise nBuLi (1.6 m in hexane, 1.22 mL, 1.96 mmol) at –78 °C
over 20 min. The mixture was stirred at this temperature for
30 min. Bu3SnCl (1.96 mmol) was added dropwise and the mixture
was slowly warmed and stirred at room temperature for 1 h. The
solution was poured into a phosphate buffer solution pH 7 (7 mL),
the organic layer separated, extracted with AcOEt (2ϫ10 mL) and
washed (2ϫ10 mL) with a brine. The combined organic layers were
dried with sodium sulfate, filtered and the solvent was removed
under reduced pressure. To a solution of this crude oil in anhydrous
toluene (8 mL) was added L2H (578 mg, 1.96 mmol) and Pd-
(PPh3)4 (113 mg, 0.1 mmol). The mixture was heated to reflux un-
der argon for 48 h. After cooling to room temperature, the black
solution was evaporated to dryness, and the crude product was
washed several times with acetonitrile and dichloromethane to give
L5H. Yield 25 %; red solid; m.p. 215 °C. 1H NMR (300 MHz,
CDCl3): δ = 11.81 (br. d, J = 14.4 Hz, 1 H), 7.68–7.61 (m, 1 H),
7.43 (d, J = 8.4 Hz, 2 H), 7.12 (d, J = 8.4 Hz, 2 H), 6.50 (s, 1 H),
6.34 (s, 2 H), 5.69 (d, J = 7.2 Hz, 1 H) ppm. 19F NMR (282 MHz,
CDCl3): δ = –77.5 (s) ppm. HRMS (ESI): calcd. for C16H9F3NOS4
[M – H]– 415.95245; found 415.9508. C16H10F3NOS4 (417.51):
calcd. C 46.03, H 2.41, N 3.35; found C 46.23, H 2.49, N 3.16.
future goals.
Experimental Section
General: Commercially available reagents were used as supplied,
unless stated otherwise, and stored according to the manufacturer’s
recommendations.
(E)-4-Ethoxy-1,1,1-trifluorobut-3-en-2-one
(1),[41] L1H[42] and L2H[43] were prepared according to the litera-
1
ture. H, 19F and 13C NMR spectra were recorded with a Bruker
Avance 300 spectrometer (in CDCl3) at 300, 282 and 75 MHz
respectively. Chemical shifts are given in ppm relative to the resid-
ual solvent peak (δH = 7.26 ppm for CHCl3, δC = 77.0 ppm for
CDCl3) or CFCl3 (19F). The following abbreviations are used: sing-
let (s), doublet (d), triplet (t), quartet (q), multiplet (m) and broad
(br.). TLC was performed on Merck silica Gel 60 F254 plates with
detection by UV light. Column chromatography was performed on
Macherey–Nagel Silica gel 60 m (0.04–0.063 mm). Solvents for
chromatography and work up are: dichloromethane (DCM), ethyl
acetate (AcOEt), methanol (MeOH) and petroleum ether (PE).
Mass spectra were recorded using a FINIGAN MAT 95 (EI and
ESI) instrument, and UV/Vis spectra were recorded with a Lambda
35 spectrophotometer. Melting points were determined in capillary
tubes with a Büchi apparatus. Electrochemical measurements were
performed using an EG & G-Princeton Applied Research 263A all-
in-one potentiostat, using a standard three-electrode setup with a
glassy carbon electrode (working electrode), platinum wire auxil-
iary electrode and a nonaqueous Ag/Ag+ system in acetonitrile as
the reference electrode. DMF solutions of the compounds with
0.1 m supporting electrolyte nBu4NPF6 were measured with the
voltage scan rate of 0.2 Vs–1. Under these experimental conditions
the ferrocene/ferricinium couple, used as internal reference for po-
tential measurements, was located at E1/2 = +0.05 V in DMF.
(E)-1-[4-(Phenyldiazenyl)phenyl]ethanone (3): Nitrosobenzene
(161 mg, 1.5 mmol) was dissolved in glacial acetic acid (6 mL). To
this stirred solution was added p-aminoacetophenone (135 mg,
1 mmol) and the mixture was stirred at 90 °C overnight. The solu-
tion was cooled to room temperature and poured into water
(7 mL), and the aqueous layer was extracted with dichloromethane
(5ϫ10 mL). The combined organic layers were dried with sodium
sulfate and filtered, and the solvents were removed under reduced
pressure. Silica gel chromatography of the crude product (DCM)
yielded 3. Yield 71 %; orange solid; m.p. 115 °C. 1H NMR
(300 MHz, CDCl3): δ = 8.11 (d, J = 8.7 Hz, 2 H), 7.98 (d, J =
8.7 Hz, 2 H), 7.95 (m, 2 H), 7.53 (m, 3 H), 2.67 (s, 3 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 197.2, 154.8, 152.4, 138.2, 131.6,
129.2, 129.1, 123.1, 122.8, 26.7 ppm. HRMS (EI): calcd. for
C14H12N2O [M]+· 224.09496; found 224.09491. C14H12N2O
(224.26): calcd. C 74.98, H 5.39, N 12.49; found C 74.86, H 5.10,
N 12.54.
General Procedure for the Synthesis of L1H–L4H: To a solution of
1 (1.5 g, 8.92 mmol) in acetonitrile (20 mL) was added a solution
of the amine (8.92 mmol) in acetonitrile (10 mL). The mixture was
stirred at room temperature under argon for 5 h. The resulting pre-
1100
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Eur. J. Inorg. Chem. 2012, 1093–1103

CuII Complexes of Bi- and Tetradentate Ketones
1
General Procedure for Acetalization: Trimethylorthoformate
(1.5 mmol) and p-toluenesulfonic acid (0.007 mmol) were dissolved
in anhydrous methanol (9 mL) and the resulting solution was
added to a round-bottomed flask that contained the ketone
(1 mmol). The mixture was heated to 60 °C for 24 h under argon.
Sodium carbonate was added for neutralization, and the mixture
was filtered. The solvent was removed from the filtrate under re-
duced pressure, and the crude product was pure enough for the
next step.
158 °C. H NMR (300 MHz, CDCl3): δ = 12.68 (br. s, 1 H), 8.47
(s, 1 H), 8.40 (s, 1 H), 8.23 (s, 1 H), 8.05–8.01 (m, 2 H), 7.93–7.86
(m, 3 H), 7.74 (d, J = 8.4 Hz, 2 H), 7.57–7.48 (m, 5 H), 7.24 (d, J
= 8.7 Hz, 1 H), 7.02 (d, J = 8.7 Hz, 2 H), 6.01 (s, 1 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 178.3, 165.4, 152.4, 149.7, 140.3,
132.8, 132.1, 131.3, 131.1, 130.7, 130.4, 129.5, 129.0, 128.2, 128.1,
127.8, 126.5, 126.4, 126.2, 123.8, 123.7, 123.6, 122.8, 117.0 (q, J =
286.8 Hz), 93.9 ppm. 19F NMR (282 MHz, CDCl3): δ = –77.9 (s)
ppm. HRMS (ESI): calcd. for C30H21F3N3O [M + H]+ 496.16312;
found 496.1624. C30H20F3N3O (495.49): calcd. C 72.72, H 4.07, N
8.48; found C 72.83, H 4.23, N 8.12.
(E)-1-[4-(1,1-Dimethoxyethyl)phenyl]-2-phenyldiazene (5): Yield
1
99%; orange oil; H NMR (300 MHz, CDCl3): δ = 7.93 (m, 4 H),
7.68 (d, J = 8.4 Hz, 2 H), 7.50 (m, 3 H), 3.24 (s, 6 H), 1.60 (s, 3 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 152.5, 151.9, 145.7, 130.8,
128.9, 127.0, 122.7, 122.5, 101.3, 48.8, 25.8 ppm. C16H18N2O2
(270.33): calcd. C 71.09, H 6.71, N 10.36; found C 70.88, H 6.65,
N 10.23.
(Z)-4-(Anthracen-2-yl)-4-[4-({E}-{4-(dimethylamino)phenyl}di-
azenyl)phenylamino]-1,1,1-trifluorobut-3-en-2-one (L7H): Yield
60%; red solid; m.p. Ͼ 220 °C. H NMR (300 MHz, CDCl3): δ =
1
12.69 (br. s, 1 H), 8.45 (s, 1 H), 8.38 (s, 1 H), 8.21 (s, 1 H), 8.02–
8.00 (m, 2 H), 7.87 (d, J = 8.7 Hz, 1 H), 7.80 (d, J = 9.3 Hz, 2 H),
7.64 (d, J = 8.4 Hz, 2 H), 7.54–7.50 (m, 2 H), 7.22 (d, J = 8.7 Hz,
1 H), 6.98 (d, J = 8.7 Hz, 2 H), 6.70 (d, J = 9.0 Hz, 2 H), 5.95 (s,
1 H), 3.05 (s, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 177.7
(q, J = 33.2 Hz), 165.6, 152.5, 150.6, 143.5, 138.6, 132.8, 132.1,
131.3, 130.9, 130.5, 129.5, 128.9, 128.1, 127.8, 126.5, 126.4, 126.1,
125.0, 124.0, 123.8, 123.0, 122.9, 117.0 (q, J = 286.8 Hz), 111.4,
93.4, 40.2 ppm. 19F NMR (282 MHz, CDCl3): δ = –76.9 (s) ppm.
HRMS (ESI): calcd. for C32H26F3N4O [M + H]+ 539.20532; found
539.2053. C32H25F3N4O (538.56): calcd. C 71.36, H 4.68, N 10.40;
found C 71.34, H 4.93, N 10.37.
2-(1,1-Dimethoxyethyl)anthracene (6): Yield 99%; yellow solid; m.p.
80 °C. 1H NMR (300 MHz, CDCl3): δ = 8.52 (s, 1 H), 8.42 (s, 1
H), 8.36 (s, 1 H), 8.07–8.01 (m, 3 H), 7.69 (dd, J = 9.0, 1.5 Hz, 1
H), 7.52 (m, 2 H), 3.41 (s, 6 H), 1.80 (s, 3 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 139.4, 131.7, 131.2, 131.0, 128.1, 128.0,
127.9, 126.7, 125.7, 125.5, 125.1, 123.9, 101.6, 48.9, 25.5 ppm.
C18H18O2 (266.33): calcd. C 81.17, H 6.81; found C 81.36, H 7.02.
General Procedure for the Trifluoroacetylation of Ketone Dimethyl
Acetals: To a solution of ketone dimethyl acetal (1 mmol) and pyr-
idine (4 mmol) in anhydrous dichloromethane (2 mL) at 0 °C was
added dropwise TFAA (2 mmol). The mixture was slowly warmed
to room temperature and heated to reflux for 72 h for 7 and 24 h
for 8. The mixture was washed with an aqueous solution of 0.1 m
HCl (10 mL), a 10% aqueous solution of Na2CO3 (5 mL) and
water (2ϫ10 mL). The combined organic layers were dried with
sodium sulfate, filtered and the solvent was removed under reduced
pressure. The crude oil was purified by silica gel chromatography
(PE/DCM = 1:1).
General Procedure for the Synthesis of L8H2–L13H2: To a solution
of 7 or 8 (0.66 mmol) in acetonitrile (3 mL) was added dropwise a
solution of the diamine (0.33 mmol) in acetonitrile (3 mL) over 3 h.
The mixture was then stirred at room temperature for 1 h. The
precipitate formed was washed with cold acetonitrile, the filtrate
evaporated to dryness, and the crude product was purified by silica
gel chromatography (DCM for L8H2 and L11H2, PE/DCM = 1:1
for L9H2, L10H2, L12H2 and L13H2).
(Z)-1,1,1-Trifluoro-4-methoxy-4-[4-{(E)-phenyldiazenyl}phenyl]but-
3-en-2-one (7): Yield 84%; orange-red solid; m.p. 61 °C. H NMR
(3Z,3ЈZ)-4,4Ј-[Ethane-1,2-diylbis(azanediyl)]bis[1,1,1-trifluoro-4-(4-
{(E) phenyldiazenyl}phenyl)but-3-en-2-one] (L8H2): Yield 54 %;
orange solid; m.p. Ͼ 220 °C. 1H NMR (300 MHz, CDCl3): δ =
12.95 (br. s, 2 H), 7.97–7.93 (m, 8 H), 7.57–7.53 (m, 6 H), 7.35 (d,
J = 8.4 Hz, 4 H), 5.50 (s, 2 H), 3.51 (t, J = 3.0 Hz, 4 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 177.4 (q, J = 32.9 Hz), 169.9, 153.6,
152.4, 134.9, 131.8, 129.2, 128.4, 123.4, 123.2, 91.3, 45.1 ppm. 19F
NMR (282 MHz, CDCl3): δ = –77.1 (s) ppm. HRMS (ESI): calcd.
for C34H27F6N6O2 [M + H]+ 665.20942; found 665.2104.
C34H26F6N6O2 (664.60): calcd. C 61.45, H 3.94, N 12.65; found C
61.23, H 3.93, N 12.41.
1
(300 MHz, CDCl3): δ = 7.98–7.95 (m, 4 H), 7.65 (d, J = 8.4 Hz, 2
H), 7.52–7.50 (m, 3 H), 5.89 (s, 1 H), 3.95 (s, 3 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 177.1 (q, J = 35.1 Hz), 177.0, 153.7, 152.4,
135.6, 131.4, 129.9, 129.1, 123.2, 123.0, 116.7 (q, J = 290.0 Hz),
92.2, 57.4 ppm. 19F NMR (282 MHz, CDCl3): δ = –78.6 (s) ppm.
HRMS (ESI): calcd. for C17H13F3N2NaO2 [M + Na]+ 357.0827;
found 357.0822. C17H13F3N2O2 (334.29): calcd. C 61.08, H 3.92,
N 8.38; found C 61.42, H 4.20, N 8.36.
(Z)-4-(Anthracen-2-yl)-1,1,1-trifluoro-4-methoxybut-3-en-2-one (8):
Yield 60%; yellow solid; m.p. 149 °C. 1H NMR (300 MHz, CDCl3):
δ = 8.45 (s, 1 H), 8.37 (s, 1 H), 8.27 (s, 1 H), 7.98–7.96 (m, 3 H),
7.54–7.46 (m, 3 H), 5.97 (s, 1 H), 3.97 (s, 3 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 177.9, 177.3 (q, J = 34.0 Hz), 132.7, 131.9,
131.8, 130.5, 130.3, 130.2, 128.2, 128.1, 128.0, 127.7, 126.2, 126.1,
125.6, 124.6, 116.9 (q, J = 290.0 Hz), 92.0, 57.3 ppm. 19F NMR
(282 MHz, CDCl3): δ = –78.4 (s) ppm. HRMS (ESI): calcd. for
C19H14F3O2 [M + H]+ 331.0940; found 331.0951. C19H13F3O2
(330.30): calcd. C 69.09, H 3.97; found C 68.87, H 4.03.
(3Z,3ЈZ)-4,4Ј-[1,2-Phenylenebis(azanediyl)]bis[1,1,1-trifluoro-4-(4-
{(E)-phenyldiazenyl}phenyl)but-3-en-2-one] (L9H2): Yield 50%; yel-
low solid; m.p. 210 °C. 1H NMR (300 MHz, CDCl3): δ = 12.16 (br.
s, 2 H), 7.78–7.74 (m, 4 H), 7.69 (d, J = 8.4 Hz, 4 H), 7.39–7.37
(m, 6 H), 7.15 (d, J = 8.4 Hz, 4 H), 6.87–6.84 (m, 2 H), 6.71–6.68
(m, 2 H), 5.78 (s, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 178.7
(q, J = 31.2 Hz), 165.5, 153.7, 152.4, 135.3, 132.3, 131.7, 129.1,
128.9, 126.9, 126.5, 123.1, 123.0, 117.1 (q, J = 286.9 Hz), 93.9 ppm.
19F NMR (282 MHz, CDCl3): δ = –77.1 (s) ppm. HRMS (ESI):
calcd. for C38H27F6N6O2 [M + H]+ 713.20942; found 713.2083.
C38H26F6N6O2 (712.64): calcd. C 64.04, H 3.68, N 11.79; found C
63.72, H 3.44, N 11.58.
General Procedure for the Synthesis of L6H and L7H: To a solution
of 8 (300 mg, 0.91 mmol) in acetonitrile (4 mL) was added a solu-
tion of the primary amine (0.91 mmol) in acetonitrile (4 mL). The
mixture was stirred at room temperature for 5 h. The solvent was
removed under reduced pressure and the crude product was puri-
fied by silica gel chromatography (PE/DCM = 1:1).
(3Z,3ЈZ)-4,4Ј-(4,5-Dimethyl-1,2-phenylene)bis(azanediyl)bis[1,1,1-
tri-fluoro-4-(4-{(E)-phenyldiazenyl}phenyl)but-3-en-2-one] (L10H2):
Yield 60 %; yellow solid; m.p. Ͼ 220 °C. 1H NMR (300 MHz,
CDCl3): δ = 12.09 (br. s, 2 H), 7.88–7.86 (m, 4 H), 7.78 (d, J =
8.4 Hz, 4 H), 7.50–7.49 (m, 6 H), 7.23 (d, J = 8.4 Hz, 4 H), 6.62
(Z)-4-(Anthracen-2-yl)-1,1,1-trifluoro-4-[4-{(E)-phenyldiazenyl}-
phenylamino]but-3-en-2-one (L6H): Yield 68%; orange solid; m.p.
Eur. J. Inorg. Chem. 2012, 1093–1103
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1101

Nicolas Chopin, M. Médebielle, G. Pilet
FULL PAPER
(s, 2 H), 5.82 (s, 2 H), 2.02 (s, 6 H) ppm. 13C NMR (75 MHz,
program.[54] In Table 1, R(F2) and Rw(F2) are indicated for
CDCl3): δ = 178.5 (q, J = 33.6 Hz), 165.7, 153.5, 152.4, 136.3, IϾ2σ(I). In each structure, all atomic displacements for non-hy-
135.5, 131.7, 129.8, 129.1, 128.8, 127.5, 123.1, 117.2 (q, J =
286.7 Hz), 93.1, 19.3 ppm. 19F NMR (282 MHz, CDCl3): δ = –77.1
(s) ppm. HRMS (ESI): calcd. for C40H30F6N6NaO2 [M + Na]+
763.22266; found 763.2199. C40H30F6N6O2 (740.70): calcd. C
64.86, H 4.08, N 11.35; found C 65.06, H 4.02, N 11.54.
drogen atoms were refined anisotropically. Hydrogen atoms on car-
bon atoms were located theoretically and the others (on oxygen
atoms of noncoordinated solvent molecules) by Fourier difference,
all were refined using a riding method.
CCDC-850706 (for A), -850707 (for B), -850708 (for C) and
-850709 (for D) contain the supplementary crystallographic data
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
(3Z,3ЈZ)-4,4Ј-[Ethane-1,2-diylbis(azanediyl)]bis[4-(anthracen-2-yl)-
1,1,1-trifluorobut-3-en-2-one] (L11H2): Yield 42 %; yellow solid;
m.p. Ͼ 220 °C. 1H NMR (300 MHz, CDCl3): δ = 11.07 (br. s, 2
H), 8.39 (s, 2 H), 8.16 (s, 2 H), 8.04 (d, J = 7.5 Hz, 2 H), 7.93–7.88
(m, 4 H), 7.65 (s, 2 H), 7.55 (m, 4 H), 7.15 (d, J = 8.4 Hz, 2 H),
5.56 (s, 2 H), 3.55 (t, J = 1.8 Hz, 4 H) ppm. 19F NMR (282 MHz,
CDCl3): δ = –77.0 (s) ppm. HRMS (ESI): calcd. for C38H27F6N2O2
[M + H]+ 657.19712; found 657.1947. C38H26F6N2O2 (656.62):
calcd. C 69.51, H 3.99, N 4.27; found C 69.48, H 4.25, N 4.12.
Supporting Information (see footnote on the first page of this arti-
cle): crystal structures of L4H, L10H2 and [Cu(L8)2] (E), cyclic
voltammograms of L6H, L12H2, [Cu(L6)2] and [Cu(L12)].
(3Z,3ЈZ)-4,4Ј-[1,2-Phenylenebis(azanediyl)]bis[4-(anthracen-2-yl)-
1,1,1-trifluorobut-3-en-2-one] (L12H2): Yield 48 %; yellow solid;
m.p. Ͼ 220 °C. 1H NMR (300 MHz, CDCl3): δ = 12.40 (br. s, 2
H), 8.28 (s, 2 H), 7.92 (d, J = 8.4 Hz, 2 H), 7.86 (s, 2 H), 7.77 (d,
J = 8.7 Hz, 2 H), 7.67 (d, J = 7.5 Hz, 2 H), 7.60 (s, 2 H), 7.51–7.43
(m, 4 H), 7.06 (d, J = 8.7 Hz, 2 H), 6.84–6.83 (m, 4 H), 5.96 (s, 2
H) ppm. 13C NMR (75 MHz, CDCl3): δ = 170.8 (m), 166.4, 132.8,
132.6, 132.1, 131.3, 130.2, 130.1, 129.2, 129.1, 128.2, 128.1, 127.7,
126.6, 126.5, 126.4, 126.3, 126.1, 123.4, 117.3 (q, J = 287.2 Hz),
93.9 ppm. 19F NMR (282 MHz, CDCl3): δ = –77.1 (s) ppm. HRMS
(ESI): calcd. for C42H27F6N2O2 [M + H]+ 705.19712; found
705.1972. C42H26F6N2O2 (704.66): calcd. C 71.59, H 3.72, N 3.98;
found C 71.65, H 3.47, N 4.14.
Acknowledgments
We would like to thank the Centre National de la Recherche Sci-
entifique (CNRS), Université Claude Bernard Lyon 1 and the
Région Rhône-Alpes (CIBLE project “ENAMBRIMOLE”) for fi-
nancial support. N. C. is grateful to the Région Rhône-Alpes for
a PhD fellowship. G. P. thanks the Centre de Diffraction Henri
Longchambon for access to the single-crystal X-ray diffraction dif-
fractometers. We would like to thank A. T. Bui and C. Morcel for
help with some of the syntheses.
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(3Z,3ЈZ)-4,4Ј-(4,5-Dimethyl-1,2-phenylene)bis(azanediyl)bis[4-
(anthracen-2-yl)-1,1,1-trifluorobut-3-en-2-one] (L13H2): Yield 63%;
yellow solid; m.p. Ͼ 220 °C. 1H NMR (300 MHz, CDCl3): δ =
12.27 (br. s, 2 H), 8.27 (s, 2 H), 7.90 (s, 4 H), 7.73 (s, 4 H), 7.61 (s,
2 H), 7.47 (s, 4 H), 7.03 (d, J = 8.7 Hz, 2 H), 6.60 (s, 2 H), 5.91 (s,
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Received: December 13, 2011
Published Online: January 27, 2012
Eur. J. Inorg. Chem. 2012, 1093–1103
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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