Trifluoromethylated enaminones and their explorative coordination chemistry with Cu(ii): Synthesis, redox properties and structural characterization of the complexes

Article abstract of DOI:10.1039/b805071f

The syntheses of three original trifluoromethylated enaminones L1H-L3H, an unexplored type of ligand with possible multiple coordination centres, their redox properties and explorative coordination chemistry with copper(ii) are presented. The ability of these ligands to coordinate copper(ii) and then to form new mono- and dinuclear complexes is presented and discussed. The consequences of this metal coordination on redox properties are also explored.

Full text of DOI:10.1039/b805071f

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PAPER
www.rsc.org/dalton | Dalton Transactions
Trifluoromethylated enaminones and their explorative coordination chemistry
with Cu(II): synthesis, redox properties and structural characterization
of the complexes†
Guillaume Pilet,*a Jean-Bernard Tommasino,a Fabrice Fenain,b Rita Matrakb and Maurice Me´debielle*b
Received 26th March 2008, Accepted 8th July 2008
First published as an Advance Article on the web 28th August 2008
DOI: 10.1039/b805071f
The syntheses of three original trifluoromethylated enaminones L1H–L3H, an unexplored type of
ligand with possible multiple coordination centres, their redox properties and explorative coordination
chemistry with copper(II) are presented. The ability of these ligands to coordinate copper(II) and then
to form new mono- and dinuclear complexes is presented and discussed. The consequences of this
metal coordination on redox properties are also explored.
Introduction
The discovery just over twenty years ago that some metallic hybrid
inorganic–organic clusters may behave as single-molecule magnets
(SMMs)1 is currently stimulating abundant research in relation to
potential applications in information processing and storage.2 In
that context and relevant to the work presented here, one of us
recently reported several examples of molecular clusters exhibiting
interesting magnetic properties (like SMM ones) involving N,N,O
or O,N,O enaminoketone ligands (Fig. 1).3–7
It appeared that ligands coordinating the metal cation could
play an important role in the magnetic properties. With this in
mind, and as part of our work on polynuclear metal complexes,8 we
chose the trifluoromethylated enaminone ligand which may exhibit
interesting redox properties as a “noninnocent” ligand9 and which
could be a magnetic coupler for propagating interactions between
paramagnetic ions.
Trifluoromethylated b-aminovinyl ketones are known and have
been frequently used as valuable building blocks, to prepare
various trifluoromethylated aromatics and heterocycles.10 The
ability of enaminones to coordinate with a variety of transition
metals has been used with success to prepare a number of
metallomesogens with interesting liquid crystal properties,11–14
highly-active catalysts for olefin polymerization, including recently
fluorinated enaminones.15–17 However a detailed study of the redox
properties of fluorinated enaminones and their useful coordination
Fig. 1 [Dy3Cu6] single molecule magnet.
chemistry with broad applications in materials science has scarcely
been studied.18–22 Recently a series of fluorinated enaminones
bearing two independent coordination centers have been obtained
and the crystal structure of a Cu(II) complex was revealed.18
The crystal structure of a Mn(II) complex with a trifluoromethy-
lated enaminone derivative of 3-imidazoline nitroxide was also
published with a weak ferromagnetic property;19 in addition
crystal structures of Cu(II), Ni(II) and Pd(II) bischelates with a
trifluoromethylated enaminoketone derivative of 2-imidazoline
nitroxide were also known.20 As far as we know there are only
two reports of the electrochemistry of fluorinated enaminones
and their Cu(II) and Ni(II) complexes.21–22 These two studies
showed that the reduction of the ligands in dimethylformamide
were irreversible, giving unstable radical anions as reduction
products and that the corresponding Cu(II) and Ni(II) chelates
were characterized in most cases by a quasi-reversible one-electron
transfer; most of the enaminones presented in these two papers did
not feature possible mutliple coordination centers, and no further
extension with potential applications in materials science have
appeared in the literature.
aUniversite´ Claude Bernard Lyon 1 (UCBL), Laboratoire des Multi-
mate´riaux et Interfaces (LMI), UMR CNRS 5615, Groupe de Cristallogra-
phie et Inge´nierie Mole´culaire, Baˆtiment Raulin, 43 bd du 11 Novembre 1918,
Villeurbanne, France. E-mail: guillaume.pilet@univ-lyon1.fr; Fax: +33 472
431 160; Tel: +33 472 448 220
bUniversite´ Claude Bernard Lyon 1 (UCBL), Institut de Chimie et Biochimie
Mole´culaires et Supramole´culaires (ICBMS), UMR CNRS 5246, Labora-
toire de Synthe`se de Biomole´cules, Baˆtiment Chevreul, 43 bd du 11 Novembre
1918, Villeurbanne, France. E-mail: medebiel@univ-lyon1.fr; Tel: +33 472
431 989
† CCDC reference numbers 682201–682203 for [Cu(L1)2], [Cu2(L2)4] and
[Cu(L3)2] respectively. For crystallographic data in CIF or other electronic
format see DOI: 10.1039/b805071f
As part of our ongoing efforts in search of novel polynu-
clear metal complexes with potential involvement in catalysis,
magnetism and biology, we wish to report in this paper our
preliminary results with the synthesis of three trifluoromethylated
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enaminones (L1H–L3H) (Fig. 2) including their redox properties
and the synthesis, structural characterization and electrochemical
behavior of the resulting Cu(II) complexes.
methanolic solution of CuCl2·2H2O (1.0 equiv.) to a methanolic
solution of the ligand. After stirring at room temperature for
ten minutes, Et3N (in excess) was then added and the resulting
green solution stirred for an additional two hours. Single crystals
suitable for X-ray characterization were obtained after three days
of evaporation. The complex was obtained as green needles in a
43% isolated yield. Copper(II) complexes of L2H (green plates,
63%) and L3H (brown needles, 75%) were prepared in a similar
way.
Fig.
2
Structures of the trifluoromethylated enaminone ligands
L1H–L3H.
Single crystal X-ray diffraction studies
Data collection. The data were processed using the Kap-
paCCD analysis programs.25 The lattice constants were refined
by least-squares refinements. For all complexes, no absorption
correction was applied to the data sets. All the data collections
have been performed at 293 K.
Results and discussion
Syntheses of the ligands
The enaminone ligands L1H–L3H were prepared in good
yields in two straightforward steps: trifluoroacetylation of com-
mercially available ethyl vinyl ether [trifluoroacetic anhydride
(TFAA)/pyridine in anhydrous dichloromethane], followed by O–
N exchange reaction of the resulting crude (E)-4-ethoxy-1,1,1-
trifluorobut-3-en-2-one,23 with the corresponding amines (slight
excess) in anhydrous acetonitrile (Scheme 1).
Structure solution and refinement. [Cu(L1)2] and [Cu2(L2)4]
complexes crystallize in the monoclinic system. According to
the observed systematic extinctions, their structures have been
solved and refined in the P21/c, P21/n space groups respectively.
[Cu(L3)2] complex crystallizes in the triclinic system. Due to the
observed systematic extinctions, its structure has been solved and
¯
refined in the P1 space group.
All the structures have been solved by direct methods using the
SIR97 program26 combined with Fourier difference syntheses and
refined against F using the CRYSTALS program.27 The hydrogen
atoms have been either found by Fourier difference and located
theoretically based on the conformation and environment of the
supporting atom. Hydrogen atoms were introduced in calculated
positions and refined riding on their parents atoms. All the
atomic displacement parameters for non-hydrogen atoms have
been refined anisotropically.
Crystal structure descriptions†.
[Cu(L1)2]. The complex is built from one copper atom
surrounded by two L1 ligands (see Fig. 3a). No solvent molecules
or counter-ions have been found in the structure during the
refinement. The complex entity appears then to be neutral with one
Cu(II) and two (L1)- deprotonated ligands. The metal is located
in an almost perfect square planar environment with Cu–O and
Scheme 1 General access to the ligands L1H–L3H.
The benzylic substrate L1H24 was obtained in a 81% isolated
yield through the dropwise addition of the benzyl amine to a
cooled (0 ◦C) anhydrous acetonitrile solution containing the crude
(E)-4-ethoxy-1,1,1-trifluorobut-3-en-2-one, followed by warming
the reaction mixture to room temperature for one hour (TLC
monitoring). The aromatic L2H and heterocyclic L3H substrates
were also obtained in very good yields (84% for L2H and 75% for
L3H) under refluxing conditions for one hour (TLC monitoring).
All the enaminone ligands were obtained as Z isomers, as
˚
Cu–N bond lengths which are equal to 1.913(3) and 1.994(4) A
respectively. N–Cu–N and O–Cu–O angles, due to the inversion
center located on the metal position, are equal to 180◦. N–Cu–
O range from 88.9(1) to 91.1(1)◦. The structural packing can
be viewed as columns of complexes running along the a axis
1
determined by H NMR (small coupling constant of the olefinic
protons of 7–8 Hz and a deshielded peak of the amino proton
dH > 10.0 ppm) due to hydrogen bonding between NH and
=
C O. The three enaminones were obtained as solids; L1H was
purified by silica gel chromatography whereas L2H and L3H were
recrystallized from the crude product.
Syntheses of the Cu(II) complexes
L1H was first chosen as a model ligand and the corresponding
copper(II) complex was prepared through dropwise addition of a
Fig. 3 (a) [Cu(L1)2] entity; (b) structural packing of the structure along
the b axis of the unit cell (hydrogen atoms have been omitted for clarity).
5622 | Dalton Trans., 2008, 5621–5626
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of the unit cell (see Fig. 3b). As no hydrogen bond has been
found, the structural cohesion inside the columns is assumed
by p–p interactions between phenyl rings which stack perfectly
˚
(distance between two consecutive phenyl rings is equal to 3.8 A).
The structural cohesion between two neighbouring columms is
assumed by van der Waals interactions.
[Cu2(L2)4]. The asymmetric unit of this structure is built
from one copper atom surrounded by two (L2)- ligands. One
of these L2 ligands has an asymmetric unit with its CN moiety
connected to a neighbouring and crystallographically equivalent
copper atom, forming then the dimer, whereas the second L2
ligand stays free. The final entity can be then described as a
copper(II) dimer with the following refined formula: [Cu2(L2)4] (see
Fig. 4a). The copper atom exhibits a distorted square pyramidal
environment. The square base of this is composed by two nitrogen
atoms and two oxygen atoms belonging to the two L2 ligands of
the {Cu(L2)2} unit (half of the dimer). The Cu–O bond lengths
Fig. 5 (a) [Cu(L3)2] entity; (b) structural packing of the structure along
the a axis of the unit cell (hydrogen atoms have been omitted for clarity).
The structural packing can be viewed as independent clusters
(see Fig. 5b). As no hydrogen bonds has been found in the
structure, the structural cohesion is assumed by van der Waals
interactions.
˚
˚
(1.914 A and 1.919 A) are a bit shorter than the Cu–N bond
Electrochemical studies
˚
˚
lengths (1.981 (3) A and 1.986 (3) A) but in good agreement with
those previously reported in the literature.5 O–Cu–N angles range
from 88.7 (1)◦ to 92.6 (1)◦ and from 164.5 (1)◦ to 170.1 (1)◦.
Ligands L1H–L3H. The redox properties of ligands L1H–
L3H were explored by cyclic voltammetry (see Experimental for
details). The three ligands were found to be irreversibly reduced
in a single step at potentials between -1.52 and -1.89 V in
dichloromethane and between -1.36 V and -1.89 V in DMF
(Table 1). In both solvents the reduction step remains irreversible
up to 3 V s-1 demonstrating that the radical anion is quite
unstable.29 L1H was found to be the most difficult to reduce in the
series. Only L1H was found to be irreversibly oxidized at a rather
high oxidation potential close to 2.10 V in dichloromethane. No
clear oxidation steps could be detected for L2H and L3H.
˚
Inside a dimer, the Cu–Cu distance is equal to 6.727(1) A. This
distance appears to be too long to expect any interesting magnetic
properties for this complex. As no hydrogens and counter-ions
have been found in the structure, the structural cohesion is
assumed by van der Waals interactions. The structural packing
can be considered as columns of dimers running along the a axis
of the unit cell.
Copper(II) complexes in dichloromethane. First, we can note
that, for each complex, no reduction peak corresponding to the
free ligand in solution was detected. The cyclic voltammetry of
the Cu(L1)2 and the Cu2(L2)4 in CH2Cl2 exhibited an irreversible
reduction wave around -1.0 V (Table 2). The formation of an
irreversible anodic wave is observed around 0.3 V for the two
complexes and they are connected to the reduction process.
The exhaustive electrolysis at -1.4 V gave a consumption of
2 F mol-1 for complex Cu(L1)2 and 4 F mol-1 for complex
Cu2(L2)4. The cyclic voltammetry recorded after the exhaustive
electrolysis showed only the reduction peak of the free ligand. The
working electrode when removed from the electrolytic solution
was characterized by the formation of a Cu mirror. From these
observations, the reduction mechanism for these two complexes
can be summarized as follows:
Fig. 4 (a) [Cu2(L2)4] entity; (b) structural packing of the structure along
the a axis of the unit cell (hydrogen atoms have been omitted for clarity).
[Cu(L3)2]. The structure contains three complexes per unit
cell. This complex is formed from one copper(II) cation surrounded
by two deprotonated L3 ligands forming then a neutral mononu-
clear entity as no counter-ion has been found in the structure
(see Fig. 5a). The metal is located in a distorted octahedral
environment and is connected to four nitrogen atoms (two per
ligand) and two oxygen atoms (one per ligand). Cu–N and Cu–O
Cu(L1)2 + 2e → Cu0 + 2L1-
Cu2(L2)4 + 4e → Cu0 + 4L2-
Table 1 Electrochemical dataa for the reduction of the ligands L1H–L3H
˚
bond lengths range from 1.945(7) to 2.221(6) A and from 2.058(6)
˚
to 2.258(6) A respectively. The Cu–L3 bond lengths (three nitrogen
Compound
Epcb/V
atoms and one oxygen atom) in the square plane of the bipyramid
-1.89 (-1.89c)
-1.52 (-1.36c)
-1.53 (-1.53c)
˚
˚
L1H
L2H
L3H
range from 1.945(7) A to 2.089(7) A. Cu–L3 bond lengths in the
equatorial direction are longer than those in the square plane and
˚
˚
are equal to 2.221(6) A and 2.258(6) A. X–Cu–Y (with X and
Y = N or O) range from 78.1(3)◦ to 97.8(3)◦ and from 167.2(2)
to 175.5(3)◦ illustrating that the octahedral metal environment is
distorted (Addison parameter equal to 0.08, 0.12 and 0.10 for the
three complexes of the unit cell).28
a Peak potential recorded in dichloromethane at 293 K with a glassy
carbon electrode, with 0.1 M n-Bu4NPF6 as supporting electrolyte; all
potentials are versus SCE, scan rate 0.1 V s-1. b Cathodic peak potential.
c In dimethylformamide with 0.1 M n-Bu4NPF6 as supporting electrolyte.
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Table 2 Electrochemical dataa for the copper(II) complexes in
a same intensity could be the copper(0) formation (Table 3). For
the dimer Cu2(L2)4, the redox process seems more complicated.
Although the cyclic voltammetry behavior was similar to the
previous complexes, the coulometry at the first reduction step was
not clear to determine the electron number exchange in this redox
process. In addition other reduction steps were observed at more
negative potentials for all the complexes (Table 3). The elucidation
of the redox mechanism is in progress in our laboratories.
dichloromethane
Complex
Epcb/V
Epac/V
Cu(L1)2
Cu2(L2)4
Cu(L3)2
-1.00
0.35
0.40
-0.10
-0.80
-0.73/-0.96
a Peak potential recorded at 293 K with a glassy carbon electrode, with
0.1 M n-Bu4NPF6 as supporting electrolyte; all potentials are versus SCE,
scan rate 0.1 V s-1. b Cathodic peak potential. c Anodic peak potential only
appears after scanning through the first reduction step.
Conclusions
The synthesis of three trifluoromethylated enaminone ligands,
their redox behaviors and their coordination chemistry with cop-
per(II) was presented. The copper(II) complexes were characterized
by X-Ray single crystal structure analysis and cyclic voltammetry;
two of these complexes were found to be monomeric species and
one is a dimeric species. The redox behavior of these complexes
were found to be different in dichloromethane and in N,N-
dimethylformamide; in the former solvent for all the complexes
copper(II) was directly reduced to copper(0), but in the latter
solvent copper(I) species seem to be more stabilized since the two
redox transitions copper(II)/copper(I) and copper(I)/copper(0)
could be detected. These preliminary studies on the coordination
potential of these new enaminones ligands will give an access to
other heteromultinuclear complexes. Following a precise strategy,
it will be then possible to associate ligand redox properties to
magnetic properties of these future complexes in order to obtain
molecular electro-magnetic switches.
In contrast, the Cu(L3)2 complex gave two irreversible waves
with the same intensity at -0.73 V and -0.96 V. However as
observed for the previous two complexes, exhaustive electrolysis
at a potential corresponding to the second reduction step gave a
Cu mirror on the surface of the glassy carbon electrode with a
concommitant anodic peak close to -0.1 V. It appears reasonable
to propose that the two reduction steps do correspond to two
monoelectronic transfers, with the first one corresponding to the
formation of the copper(I) complex and the second transfer to the
further reduction into copper(0).
Copper(II) complexes in N,N-dimethylformamide. The reduc-
tion of our complexes is found to occur at more positive potentials
than their corresponding ligands, and the reduction processes were
found to be irreversible. We can note that our results are different
from the literature,22 as it was observed (although with different
enaminoketone ligands and corresponding complexes) that the
reduction processes were monoelectronic and quasi-reversible for
copper and nickel complexes indicating some stability with the
copper(I) and nickel(I).
Experimental
General comments
With our systems we have obtained for each complex a first
monoelectronic irreversible wave with a more complicated redox
pathway. This first reduction step is located at potentials between
-0.38 V and -0.78 V, with the dimer Cu2(L2)4 the easier to
reduce. In addition the first reduction is connected to a quasi-
reversible [Cu(L3)2] or irreversible oxidation [Cu(L1)2] wave at
-0.25 and +0.12 V (Table 3). The exhaustive electroysis at a
potential corresponding to the first reduction step gave 1 F mol-1
for Cu(L1)2 and Cu(L3)2 complexes. From these observations,
it seems consistent to propose that the first reduction generates
a copper(I) species stabilized by N,N-dimethylformamide as
opposed to dichloromethane. The second reduction wave with
All operations and manipulations were performed under inert
atmosphere. Solvents were distilled before use. Reagents were
obtained commercially and used without further purification
except for benzylamine which was distilled. 1H, 19F and 13C NMR
spectra were recorded with a Bruker Avance 300 spectrometer
in CDCl3 at 300 MHz, 282 MHz and 75 MHz respectively.
Chemical shifts are given in ppm relative to residual peak of
solvent (dH = 7.26 ppm for CHCl3, dC = 77.0 ppm for CDCl3)
or CFCl3 (19F). Coupling constants are given in Hertz. Silica gel
chromatography was performed on Macherey-Nagel Silica gel
60M (0.04–0.063 mm). Solvents for chromatography are: ethyl
acetate (EA), and petroleum ether (PE) (bp 30–60 ◦C). Mass
spectra were recorded using a FINIGAN MAT 95 (EI). Melting
points (uncorrected) were determined in capillary tubes on a
Buchi 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, platinum wire auxiliary electrode and SCE
(saturated calomel electrode) as the reference electrode; CH2Cl2
or DMF solutions of the compound under the study were 1.0 mM
and 0.1 M in the supporting electrolyte n-Bu4NPF6 with the
voltage scan rate of 0.1 V s-1. Under these experimental conditions
the ferrocene/ferricinium couple, used as internal reference for
potential measurements, was located at E1/2 = 0.421 V in CH2Cl2
and 0.445 V in DMF. (E)-4-Ethoxy-1,1,1-trifluorobut-3-en-2-one
was prepared according to literature.23
Table 3 Electrochemical dataa for the copper(II) complexes in N,N-
dimethylformamide
Complex
Epcb/V
Epaf/V
Cu(L1)2
Cu2(L2)4
Cu(L3)2
-0.65/-1.92c
-0.38/-1.85d
-0.78/-1.10e
0.12
0.06
-0.25
a Peak potential recorded at 293 K with a glassy carbon electrode, with
0.1 M n-Bu4NPF6 as supporting electrolyte; all potentials are versus SCE,
scan rate 0.1 V s-1. b Cathodic peak potential. c An additional reduction
step is observed at -2.7 V (irreversible). d Two additional reduction steps are
observed at -2.4 V (irreversible) and -2.7 V (reversible). e Four additional
reduction steps are observed at -1.9 V (irreversible), -2.1 V (irreversible),
-2.3 V (irreversible) and -2.7 V (irreversible). f Anodic peak potential only
appears after scanning through the first reduction step.
5624 | Dalton Trans., 2008, 5621–5626
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Syntheses
EI: m/z = 267 (M∑+), 198 ([M - CF3]∑+). HRMS for C13H9F3N2O
[M+] calc., 267.0745; found, 267.0743.
General procedure for the synthesis of the enaminone ligands.
To a stirred solution of (E)-4-ethoxy-1,1,1-trifluorobut-3-en-2-one
(1.81 g, 9.8 mmol) in anhydrous acetonitrile (30 mL) was added
dropwise the appropriate amine (10.8 mmol) at 0 ◦C. The solution
turned red or pink and was stirred at room temperature (L1H) or
heated at reflux for 1 h (L2H and L3H). The solvent was removed
under reduced pressure and the residue was purified by silica gel
chromatography (L1H) or recrystallization (L2H and L3H).
General procedure for the syntheses of the Cu(II) complexes
A methanolic solution (5 mL) of CuCl2·2H2O (28.2 mg,
0.21 mmol) was added dropwise to a methanolic solution (15 mL)
of the ligand (0.21 mmol) at room temperature. After 10 min of
stirring, 0.2 mL of Et3N was added and the resulting dark green
(for L1H and L2H) or brown solution (for L3H) was stirred for
an additional 2 h. Single crystals for X-ray characterization were
obtained by slow evaporation of the solvent (3 d).
(Z)-4-Benzylamino-1,1,1-trifluorobut-3-en-2-one L1H24.
Crystallography
Structure refinement results for [Cu(L1)2]. C22H18Cu1F6N2O2,
-1
˚
˚
M = 519.9 g mol , monoclinic, a = 4.9303(3) A, b = 9.2242(4) A,
◦
3
˚
˚
c = 23.976(1) A, b = 92.432(2) , U = 1089.4(1) A , T = 293 K,
space group P21/c (no. 14), Z = 2, 5070 reflections measured, 2581
unique (Rint = 0.051), R(F, I/s(I) > 3) = 0.0382, wR (F, I/s(I) >
Pale pinkish crystals, yield 81%, mp 48 ◦C. 13C NMR (CDCl3,
75 MHz) d (ppm): 178.3 (q, J = 33.5, C-2), 157.9 (C-4), 136.1
(C-6), 129.2 (C-9), 128.4 (C-8), 127.5 (C-7), 117.5 (q, J = 288.7,
-
-3
-3
˚
˚
3) = 0.0444, S = 1.18, Drmax = 0.32 e A , Drmin = -0.25 e A ,
1
C-1), 87.6 (q, J = 1.5, C-3), 53.3 (C-5). H NMR (CDCl3, 300
1108 reflections used to refine 180 parameters.
MHz) d (ppm): 10.52 (1H, br s, NH), 7.44–7.25 (4H, m, H-7, H-8
and H-9), 7.23 (1H, dd, J = 13.4, 7.2, H-4), 5.42 (1H, d, J = 7.2,
H-3), 4.50 (2H, d, J = 6.0, H-5). 19F NMR (CDCl3, 282 MHz) d
(ppm): -77.2 (s). MS EI: m/z = 229 (M∑+), 160 ([M - CF3]∑+), 138
Structure refinement results for [Cu2(L2)4]. C44H24Cu2F12N8-
-1
˚
O42, M = 1083.8 g mol , monoclinic, a = 10.2689(4) A, b =
◦
3
˚
˚
˚
10.2371(4) A, c = 21.489(1) A, b = 92.757(2) , U = 2256.4(2) A ,
T = 293 K, space group P21/n (no. 14), Z = 2, 8447 reflections
measured, 5027 unique (Rint = 0.044), R(F, I/s(I) > 3) = 0.0402,
∑
([M - C7H7]∑+), 91 (C7H7 +). HRMS for C11H10F3NO [M+] calc.,
229.0714; found, 229.0711.
-3
˚
wR (F, I/s(I) > 3) = 0.0457, S = 1.14, Drmax = 0.26 e A , Drmin
=
(Z)-2-(4,4,4-Trifluoro-3-oxobut-1-enylamino)benzonitrile L2H.
-3
˚
-0.42 e A , 2283 reflections used to refine 316 parameters.
Structure refinement results for [Cu(L3)2]. C26H16Cu1F6N4O2,
-1
˚
˚
M = 594.0 g mol , triclinic, a = 12.0582(7) A, b = 16.326(1) A,
◦
◦
◦
˚
c = 20.279(1) A, a = 68.198(4) , b = 80.075(3) , g = 78.876(4) ,
3
¯
˚
U = 3614.7(4) A , T = 293 K, space group P1 (no. 2), Z = 6,
22 876 reflections measured, 13 648 unique (Rint = 0.092), R(F,
I/s(I) > 1) = 0.0683, wR (F, I/s(I) > 1) = 0.0556, S = 1.15,
Pale yellow crystals (CH2Cl2), yield 84%, mp 126 ◦C. 13C NMR
(CDCl3, 75 MHz) d (ppm): 180.7 (q, J = 33.5, C-2), 148.2 (C-4),
141.8 (C-5), 134.7 (C-7), 133.6 (C-9), 125.1 (C-8), 116.6 (q, J =
-3
-3
˚
˚
Drmax = 0.49 e A , Drmin = -0.50 e A , 5871 reflections used to
1
288.9, C-1), 115.7 (C-6), 102.5 (C-10), 92.5 (m, C-3). H NMR
refine 1054 parameters.
(CDCl3, 300 MHz) d (ppm): 12.02 (1H, br s, NH), 7.73 (1H, dd,
J = 12.4, 7.7, H-4), 7.68–7.55 (2H, m, H-7 and H-9), 7.36 (1H, d,
J = 8.1, H-6), 7.27–7.21 (1H, m, H-8), 5.80 (1H, d, J = 7.7, H-3).
19F NMR (CDCl3, 282 MHz) d (ppm): d -77.8 (s). MS EI: m/z =
240 (M∑+), 171 ([M - CF3]∑+). HRMS for C11H7F3N2O [M+] calc.,
240.0510; found, 240.0507.
Acknowledgements
We would like to thank the CNRS for financial support. Fabrice
Fenain is supported by a PhD fellowship from the French
Ministry of Education, Research and Technology (MENRT).
Denis Bouchu from the Centre de Spectroscopie de Masse of
Universite´ Lyon 1 is sincerely thanked for recording the mass
spectra. We gratefully acknowledge helpful comments from Prof.
Etsuji Okada (Kobe University, Kobe, Japan), Prof. Dominique
Luneau (University of Lyon 1), as well as Dr Guillaume Chastanet
(ENS Lyon) at the early stage of the project.
(Z)-1,1,1-Trifluoro-4-(quinolin-8-ylamino)but-3-en-2-one L3H.
Ochre crystals (CH2Cl2–hexane), yield 75%, mp 124 ◦C. 13C
NMR (CDCl3, 75 MHz) d (ppm): 179.6 (q, J = 33.8, C-2), 149.8
(C-4), 146.8 (C-12), 138.5 (C-9), 136.0 (C-10), 135.5 (C-5), 128.7
(C-13), 126.6 (C-8), 123.5 (C-7), 122.5 (C-11), 117.1 (q, J = 287.7,
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5626 | Dalton Trans., 2008, 5621–5626
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The Royal Society of Chemistry 2008
©