Syntheses and crystal structures of copper and silver complexes with new imine ligands - Air-stable, photoluminescent CuIN4 chromophores

Article abstract of DOI:10.1002/ejic.200390129

A series of new imine ligands [1 [C₁₂H₁₂N₂S₂), 2 (C₁₂H₁₂N₂S₂), 3 (C₂₄H₁₈N₄S₂), and 5 (C₃₀H₂₇N₇) have been synthesized (1 and 2 are structural isomers). Cu^I and Ag^I complexes of the nonconjugated dithiophene-diimine ligands 1, 2 and the tripodal imine-amine ligand 5 have also been prepared and thoroughly characterized by spectroscopic techniques as well as by X-ray diffraction. In cyclic voltammetry at a glassy carbon milli electrode in anhydrous dichloromethane under dry N2, the corresponding Cu^I complexes [6(2C₁₂H₁₂N₂S₂ ·CuCLO₄), 7 (2C₁₂H₁₂N₂S₂ ·CuCLO₄), and 12 (C₃₀H₂₇N₇·CuCLO₄)] show quasi-reversible Cu^II/I couples with high redox potentials (1.001 V for 6, 0.958 V for 7, and 0.692 V for 12, vs. Ag/AgCl). This indicates that the π-acid ligands 1, 2, and 5 preferentially stabilize copper(I) over copper(II). The Cu^IN₄ chromophores in the complexes 6, 7, and 12 display photoluminescence in dichloromethane at room temperature. The related silver complexes of the same three ligands 10 (2C₁₂H₁₂N₂S₂ ·AgCLO₄), 11 (2C₁₂H₁₂N₂S₂ ·AgCLO₄), and 13 [C₃₀H₂₇N₇·Ag (CH₃CN)CLO₄] reveal similar structural features but lack specific photophysical properties, Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200390129

FULL PAPER
Syntheses and Crystal Structures of Copper and Silver Complexes with New
Imine Ligands ؊ Air-Stable, Photoluminescent CuIN4 Chromophores
Goutam Kumar Patra[a] and Israel Goldberg*[a]
Keywords: N ligands / Copper / Silver / Luminescence / Electrochemistry
A
series of new imine ligands [1 (C12H12N2S2),
2
7, and 0.692 V for 12, vs. Ag/AgCl). This indicates that the
(C12H12N2S2), 3 (C24H18N4S2), and 5 (C30H27N7)] have been
synthesized (1 and 2 are structural isomers). CuI and AgI
complexes of the nonconjugated dithiophene-diimine li-
π-acid ligands 1, 2, and 5 preferentially stabilize copper(I)
over copper(II). The CuIN4 chromophores in the complexes 6,
7, and 12 display photoluminescence in dichloromethane
gands 1, 2 and the tripodal imine-amine ligand 5 have also at room temperature. The related silver complexes of the
been prepared and thoroughly characterized by spectro- same three ligands 10 (2C12H12N2S2·AgClO4), 11
scopic techniques as well as by X-ray diffraction. In cyclic (2C12H12N2S2·AgClO4), and 13 [C30H27N7·Ag(CH3CN)ClO4]
voltammetry at a glassy carbon milli electrode in anhydrous
reveal similar structural features but lack specific photophys-
dichloromethane under dry N2, the corresponding CuI com- ical properties.
plexes [6 (2C12H12N2S2·CuClO4), 7 (2C12H12N2S2·CuClO4),
and 12 (C30H27N7·CuClO4)] show quasi-reversible CuII/I
couples with high redox potentials (1.001 V for 6, 0.958 V for
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
tripodal Schiff-base ligands, due to their diverse structural
and physical properties, as well as their possible application
as magnetic imaging agents and models of metalloenzymes
such as superoxide dismutases.[13,14] Correspondingly, CuI
and AgI complexes with the tripodal ligand 5 were prepared
and characterized. The CuI complex of 5 is also photolu-
minescent.
Metal complexes of N-donor ligands are of considerable
current interest because they catalyze many organic trans-
formations,[1] including the cyclization of 1,2-allene derivat-
ives,[2] the asymmetric cyclization reaction of isocyanoacetic
acid or isocyanomethyl toluenesulfonate with aldehydes,[3]
asymmetric intramolecular carbene CϪH insertion reac-
tions[4] and the enantioselective addition of allyltin reagents
to aldehydes.[5,6] Further interest is in photoluminescent
complexes of copper(). The photophysics of compounds
derived from 1,10-phenanthroline species, which contain
the CuIN4 chromophore, is well established.[7Ϫ9] However,
materials based on other ligands with N-donor atoms are
less abundant in the literature.[10Ϫ12] In this context we have
synthesized a series of new nonconjugated diimine and im-
ine-amine nitrogen donor ligands (1Ϫ5) and attempted the
formulation and thorough spectral and structural charac-
terization of their complexes with CuI, as well as with the
related AgI ion. The linear ligands 1Ϫ4 also contain peri-
pheral thiophene substituents, which may have some unique
effect on the photophysical properties of the anticipated
CuIN4 chromophores, depending on the proximity of the
sulfur atoms (although they are considered to be weak nu-
cleophiles) to the complexation site. Another variant of this
study involves transition metal complexes with tetradentate
Herein we report the detailed structures and preliminary
photophysical properties of three new CuIN4 chromophores
derived from ligands 1, 2, and 5; chemical spectral and
structural data are provided for the AgI complexes of these
ligands as well. The bulky ligand 3 does not form stable
complexes with these metal ions, while the asymmetric li-
gand 4 yields a stable structure only with divalent copper
ions.
[a]
School of Chemistry, Sackler Faculty of Exact Sciences, Tel
Aviv University
69978 Ramat Aviv, Tel Aviv, Israel
E-mail: goldberg@post.tau.ac.il
Eur. J. Inorg. Chem. 2003, 969Ϫ977  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0305Ϫ0969 $ 20.00ϩ.50/0
969

G. K. Patra, I. Goldberg
FULL PAPER
ion complexes of 3 could be obtained. The copper() deriv-
atives were prepared by treating ligands 1 and 2 with
[Cu(CH3CN)4]ClO4 in anhydrous methanol under argon in
a 1:2 metal/ligand ratio. The resulting bright orange-yellow
solids [Cu(1)2](ClO4) (6) and [Cu(2)2](ClO4) (7) are ex-
tremely stable in air both in the solid state and in solution
(CH3OH and CH2Cl2). The observed structures of the cat-
Results and Discussion
Synthesis and Structure
Compounds 1 and 2 were synthesized by condensing
ethylenediamine with 2-thiophenecarboxaldehyde or 3-thio-
phenecarboxaldehyde, respectively. These compounds are
flexible about the central CϪC bond. A 1:2 condensation
reaction of benzil dihydrazone with 2-thiophenecarboxal-
dehyde yields a bulkier ligand 3, which is considerably more
rigid. The molecular structures of 2 and 3 are shown in
Figure 1. Ligand 2 is located in the crystal on an axis of
twofold rotational symmetry, the torsion angle about the
central CϪC bond that connects the two equivalent parts
of the molecule being 70.6(3)°. The inner nitrogen atoms
are exposed to the surrounding species, and provide excel-
lent sites for metal ion binding. The NϪCϪCϪN torsion
angle about the central bond in 3 is 49.6(2)°. The nitrogen
atoms are involved in partly delocalized π-electron systems
Figure 2. Complexes of CuI with (a) ligand 1, and (b) ligand 2;
note in (a) the additional attractive interactions of the metal ion
with the inward turning sulfur sites (dotted lines); in this and the
following structural illustration the counterions and solvent moiet-
ies are omitted for clarity
ionic species in 6 and 7 are illustrated in Figure 2. The high
propensity of the copper ion to form tetrahedrally struc-
tured complexes determines the 1:2 stoichiometry of the
metal/ligand reaction. In 6 and 7 the CuϪN bond lengths
within the CuIN4 chromophore are in the range
˚
2.004Ϫ2.111(2) and 2.039Ϫ2.071(3) A, respectively. How-
ever, in 6 all the S-atom sites of the 2-thiophene substituents
are oriented towards, and weakly interact with, the central
metal ion; the corresponding Cu···S distances range from
Figure 1. Molecular structures of (a) ligand 2 (located on a twofold
symmetry axis), and (b) ligand 3; the heteroatoms are indicated by
darkened circles and are labeled; 50% probability thermal ellipsoids
at 110 K are shown
˚
3.24 to 3.60 A (Figure 2, a). Such interactions are not pos-
sible in the 3-thiophene derivative 7. As a result the thio-
(one part of the molecule is nearly planar; Figure 1), and phene rings in this structure (as well as in the related com-
therefore are less-effective donor sites for complex forma- plexes described below) tend to exhibit twofold orienta-
tion.
tional disorder about the CϪC bond through which they
In this work we have been able to synthesize and crystal- are connected to the central part of the ligand. The CuIN4
lize stable CuI and AgI complexes of 1 and 2, but no metal moieties are distorted tetrahedra with two NϪCuϪN
970
Eur. J. Inorg. Chem. 2003, 969Ϫ977

Copper and Silver Complexes with New Imine Ligands
FULL PAPER
angles near 85° (which involve nitrogen atoms from the
same ligand) and four NϪCuϪN angles greater than 115°
(for N atoms of the two different ligands).
The corresponding [Cu(1)2](ClO4)2 complex with divalent
copper, of a deep-green color, is stable in CH3OH or
CH3CN only for a few minutes, and could not be character-
ized. An alternative reaction of 1 with Cu(CF3SO3)2 yielded
a somewhat more stable product, [Cu(1)2](CF3SO3)2 (8),
which is stable in air, and in solution in CH3OH or CH3CN,
for about 2Ϫ3 h. However, upon slow recrystallization from
the solution mixture the ligand framework in 8 is partially
hydrolyzed, transforming after about 8 h to a different spe-
cies of composition [Cu(4)2](CF3SO3)2 (9) characterized by
a light pink color.[15] In situ partial hydrolysis of a diimine
ligand within the coordination sphere of copper is rare. No
stable complexes of ligand 2 with CuII ions could be ob-
tained under similar experimental conditions. The structure
of the [Cu(4)2]2ϩ cation in 9 is depicted in Figure 3. It
shows a nearly square-planar complex with the metal ion
located on a center of inversion, with CuϪN distances of
˚
1.997(2) and 2.038(2) A and NϪCuϪN bond angles be-
tween the cis-related nitrogen sites of 83.40(6)° within the
ligand and 96.60(6)° between the two ligands.
Figure 4. Structures of complexes of AgI with (a) ligand 1, and (b)
ligand 2; note in (a) the additional attractive interactions of the
metal ion with the inward turning sulfur sites (dotted lines), as in
the corresponding CuI complex shown in Figure 2a
Figure 3. Molecular structure of the square-planar complex 9 of
CuII, the metal ion being located in the crystal on a crystallographic
center of inversion
as a tetradentate ligand of adjustable conformation. Corres-
pondingly, in complexation reactions with CuI and AgI one
molecule of 5 should function as two molecules of 1 or 2.
The structures of the respective AgI complexes of 1 and The yellow-reddish CuI complex [Cu(5)](ClO4) (12) was ob-
2 {[Ag(1)2](ClO4) (10) and [Ag(2)2](ClO4) (11)} are shown tained by treating 5 with [Cu(CH3CN)4]ClO4 in equimolar
in Figure 4. They were prepared readily by treating the li- proportions in methanol under argon. Complex 12 is also
gands with Ag(ClO4) at room temperature. These two 1:2 fairly stable in air, both in the solid state and in solution. A
metal/ligand complexes are stable in the solid state for similar reaction of 5 with Ag(ClO4) in acetonitrile at room
about two weeks, and in solution (MeOH or MeCN) for temperature yielded [Ag(5)(CH3CN)](ClO4) (13). The mo-
at least 12 h. Their structures have a distorted tetrahedral lecular structures of the two complexes are illustrated in
geometry similar to that observed for the corresponding Figure 5.
copper() derivatives.
Indeed, complex 12 has a tripodal structure with the CuI
The coordination parameters are: (a) in 10, AgϪN bond cation trapped inside the ligand by internal coordination
˚
lengths of 2.293Ϫ2.298(3) A, NϪAgϪN bond angles within to the four N-donor sites. The CuϪN(imino) distances are
˚
the same ligand of nearly 76°, and involving two different within the range 2.000Ϫ2.008(2) A, while the
˚
ligands greater than 120°; (b) in 11, the corresponding CuϪN(amino) bond length is 2.206(2) A. The geometry of
values are 2.273Ϫ2.353(3) A, 76Ϫ77° and greater than the CuIN4 moiety in this structure resembles a trigonal pyr-
˚
118°, respectively. In 10, the silver ions are also approached, amid with the amino nitrogen atom at its apex. The CuIN4
in a convergent manner, by the four thiophene S-sites at chromophore with a trigonal-pyramidal geometry around
common.[16]
The
˚
an Ag···S distance range of 3.22Ϫ3.37 A. The latter may the
metal
ion
is
not
represent additional weakly attractive interactions between N(imino)ϪCuϪN(amino) bond angles are constrained by
the metal ion and the ligand species. the proximity of the two nitrogen sites to low values within
Ligand 5 is a 1:3 condensate of tris(2-aminoethyl)amine the range 84.6Ϫ85.3(1)°, while the geometrically less con-
(tren) and 4-cyanobenzaldehyde. It contains an amino ni- strained N(imino)ϪCuϪN(imino) bond angles in the base
trogen atom, as well as three imino N-donors, and may act of the pyramid are characterized by larger values of be-
Eur. J. Inorg. Chem. 2003, 969Ϫ977
971

G. K. Patra, I. Goldberg
FULL PAPER
For the ligand 5 and its CuI and AgI complexes, 12 and 13,
this ν(CϭN) stretching vibration appears at 1642, 1635, and
1633 cmϪ1, respectively, and the ν(CϵN) stretching vibra-
tions appear at 2221, 2228, and 2226 cmϪ1, respectively.
Complexes 6, 7, 10, 11, 12, and 13 give characteristic well-
resolved bands around 1088, 1080, 1085, 1081, 1090, and
Ϫ
1091 cmϪ1, respectively, for the noncoordinated ν(ClO4
)
vibrations.[17]
The H and 13C NMR spectra of the ligands 1, 2, and 5
in CDCl3 consist of sharp and well-resolved signals for each
of the organic groupings present. The CuI and AgI com-
plexes 6, 7 and 10, 11 show almost the same pattern as the
ligand in their 1H NMR spectra in (CD3)2SO. While the 1H
NMR spectrum of 13 shows the same pattern as that of the
1
1
ligand, the H NMR spectrum of 12 shows different chem-
ical shifts. In case of the ligand 5 and its AgI complex 13
all the phenylic protons appear at the same position (δ ϭ
7.67 ppm for ligand 5 and δ ϭ 7.93 ppm for the AgI com-
plex 13) but for the CuI complex 12 they appear at two
different positions (δ ϭ 8.07 and 7.46 ppm). In the EI mass
spectra ligands 1 and 2 show exactly the same type of frag-
mentation pattern.
Electrochemistry
The redox behavior of the CuI complexes 6, 7, and 12
has been examined by cyclic voltammetry in dichlorome-
thane at a glassy carbon working electrode under dry N2
(Figure 6). Quasi-reversible oxidative voltammograms at-
tributed to the CuII/I couple were observed with half-wave
potential (E1/2) values of 1.001, 0.958 and 0.692 V vs. Ag/
AgCl, 1  KCl for 6, 7, and 12, respectively. The couple is
more reversible in the case of 6 and 7 than for 12. The peak-
to-peak (∆Ep) separation values for this couple are 190,
205, and 310 mV for 6, 7, and 12, respectively, at a scan
rate of 50 mV·sϪ1 and these values increase when the scan
rate is increased. The higher potential of this couple in 6
and 7 than in 12 indicates that the CuI complexes 6 and 7
are more stable than 12; this has been observed experiment-
ally: a dichloromethane solution of 6 or 7 is stable in air
Figure 5. Structures of the tripodal complexes of ligand 5 with (a)
CuI and (b) AgI; the CuIN4 moiety in (a) is characterized by a
trigonal-pyramidal geometry; the coordination geometry around
the silver ion in (b) is affected by the additional coordinated ace-
tonitrile ligand
tween 116.6 and 121.4(1)°. The geometry of the corres-
ponding silver complex 13 is disrupted by coordination of
one acetonitrile ligand which coordinates to the metal ion
˚
with an AgϪN distance of 2.211(3) A. The latter also co-
ordinates strongly to three N-atom donor sites of the ligand
˚
at 2.315Ϫ2.461(2) A, and more weakly to the fourth (imino)
˚
nitrogen at 2.763(2) A.
IR and NMR Characterization
Ligands 1 and 2 exhibit strong IR absorption bands at
1635 and 1641 cmϪ1, respectively, for the ν(CϭN) stretch-
ing vibration. On coordination with CuI this band shifts
to much lower energies (1611 and 1614 cmϪ1 for 6 and 7,
respectively). In case of the AgI complexes 10 and 11, how-
Figure 6. Cyclic voltammograms of 6 (broken line) and 12 (full
line) [approximately 10Ϫ3  in dichloromethane, 0.2  Bu4NClO4]
ever, this band appears at 1631 and 1640 cmϪ1, respectively. at a glassy carbon electrode, scan rate 50 mV·sϪ1
972
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Copper and Silver Complexes with New Imine Ligands
FULL PAPER
for at least 10 d, whereas a solution of 12 is stable only for
about 3Ϫ4 d. The CuII/I potential in the CuIN4 chromo-
phore increases with the π-acidity of the ligand and the ex-
tent of tetrahedral distortion in the corresponding cop-
per() species.[18] The π-acidity of ligands 1 and 2 is larger
than that of 5. In this context, it should be mentioned that,
to the best of our knowledge, the highest potential for the
CuII/I couple so far reported in a CuIN4 chromophore is
1.55 V vs. SCE.[8]
UV/Vis and Photophysical Data
There is a difference in the absorption spectra of the li-
gands 1 and 2 in dichloromethane. While ligand 1 shows
two charge-transfer bands at 284 and 261 nm with intensit-
ies (ε) of 24975 and 28160 Ϫ1cmϪ1, respectively, ligand 2
shows only one charge-transfer band at 250 nm (ε ϭ 31
945). These intra-ligand charge-transfer bands appear at
282 and 266 nm for the CuI complex 6 and at 254 nm for
7. In addition to these bands, 6 shows two metal-to-ligand
charge-transfer (MLCT) bands at 415 (ε ϭ 2480) and
345 nm (ε ϭ 8785). These two MLCT bands appear at 410
(ε ϭ 2405) and 347 nm (ε ϭ 7250) for complex 7. The deep
green color of copper() complexes of the ligand 1 and pale
pink color of the copper() complex of ligand 4 are due to
the d-d transition band at 613 nm (ε ϭ 215) and 587 nm
(ε ϭ 150), respectively. Ligand 5 shows an intra-ligand
charge-transfer band at 255 nm (ε ϭ 38 120) in dichlorome-
thane. This band appears at 251 nm (ε ϭ 30 730) for its
copper() complex 12 and at 248 nm (ε ϭ 26 500, in
CH3CN) for its silver() complex 13. The copper() complex
shows an MLCT band at 379 nm (ε ϭ 2526).
Figure 7. Emission spectra of (a) 6, (b) 7, and (c) 12 at room tem-
perature in dichloromethane; excitation wavelength is 350 nm for 6
and 7, 380 nm for 12; absorbances for 6, 7, and 12 are 0.68, 0.73,
and 0.80, respectively
example of a photoluminescent CuIN4 chromophore where
the nitrogen donor atoms are of the imino as well as the
amino type, and come from the same ligand. The only
photoluminescent CuIN4 chromophore of this type known
so far has been reported recently.[12]
Conclusions
In a search for new metal ion complexes with interesting
features, we have synthesized a series of copper() and sil-
ver() compounds with targeted diimine and tripodal li-
gands, and examined their structural, photophysical, and
electrochemical properties. The copper() complexes are of
particular interest here, as they reveal a more unique photo-
physical behavior. The emission quantum yield (ϕ) of com-
plex 6 at room temperature in dichloromethane was found
to be four to five times larger than that of complexes 7 and
12. The CuII/I redox potential values of all three compounds
are rather high, indicating that the copper() state is much
more stable than the corresponding copper() state.
Ligands 1, 2, and 5 are not photoluminescent in dichloro-
methane. Upon excitation at 350 nm (MLCT envelope) in
dichloromethane at room temperature both complexes 6
and 7 yield a single, structureless, broad emission band with
maxima at 445 and 456 nm, respectively, with quantum
yields (ϕ) of 2.9·10Ϫ4 and 7.2·10Ϫ5 (against quinine sulf-
ate[19] in 0.1  H2SO4; Figure 7), respectively. In complex 6
all the four S-atoms are directed towards the metal ion, so
the metal coordination sphere is sterically more hindered.
This may be the reason for the larger quantum yield (ϕ) of
6 than 7. The chemical nature, the size and the position of
the substituents in the ligand can affect the geometry of the
excited state, which influences the emission properties.[9] It
has been found for 2,9-disubstituted phenanthroline deriv-
atives that the CuI geometry is stabilized by enforcing a
tetrahedral geometry that inhibits the flattened square-
Experimental Section
General Procedures: The complex [Cu(CH3CN)4]ClO4 was synthe-
sized by a reported procedure.[21] All other reagents were procured
commercially. Copper was estimated gravimetrically as CuSCN.
Microanalyses were performed with PerkinϪElmer 2400II ele-
planar coordination geometry in the CuII state formed mental analyzer and CE instruments. Melting points were deter-
upon excitation.[20]
mined by an electrothermal IA9000 series digital melting point ap-
paratus and are uncorrected. IR spectra (KBr disc) were recorded
On excitation at 380 nm (MLCT band), complex 12 ex-
with a Nicolet Magna-IR spectrophotometer (Series II), UV/Vis
hibits a single structureless broad emission band with a
spectra with a Shimadzu UV-160A spectrophotometer, 1H and 13
C
maximum at 505 nm and a quantum yield (ϕ) of 5.8·10Ϫ5
(against quinine sulfate[19] in 0.1  H2SO4; Figure 7). The
photophysical properties of the CuIN4 chromophore have
been analysed mainly for complexes of CuI with derivatives
of 1,10-phenanthroline.[9] These complexes are of the bis-
type in which all the nitrogen donor atoms are essentially
NMR spectra with a Bruker DPX200 spectrometer and EI (elec-
tron impact) mass spectra with a VG Autospec M-250 instrument.
Cyclic voltammetry was performed at room temperature at a planar
glassy carbon milli electrode using µ-Autolab II with GPES soft-
ware, version 4.8.5 (EcoChemie, The Netherlands) in purified and
anhydrous dichloromethane under dry nitrogen with a conven-
of the same type. Complex 12 is only the second known tional three-electrode configuration. Under the experimental condi-
Eur. J. Inorg. Chem. 2003, 969Ϫ977 973

G. K. Patra, I. Goldberg
FULL PAPER
tions employed here, the ferrocene/ferrocenium couple appears at
0.42 V vs. Ag/AgCl in 1  KCl with a ∆Ep of 110 mV at a scan
rate of 50 mV·sϪ1 (Figure 6). The photophysical studies were per-
formed in air with a Shimadzu RF-540 spectrofluorophotometer.
conditions. An orange-yellow compound precipitated. This was fil-
tered off, washed with 2 mL of methanol and dried in vacuo over
fused CaCl2. Yield: 0.18 g (55%). Single crystals were grown by
diffusion of n-hexane into a concentrated dichloromethane solution
of the complex. C24H24ClCuN4O4S4 (659.70): calcd. C 43.67, H
3.67, Cu 9.63, N 8.49, S 19.45; found C 43.62, H 3.73, Cu 9.69, N
8.46, S 19.49. FTIR (KBr): ν˜ ϭ 625 (m), 641 (w), 722 (m, split),
853 (w), 1088 (vs), 1108 (vs), 1187 (m), 1234 (s), 1288 (s), 1321 (m),
Ligand 1: Distilled ethylenediamine (1 mL, 15 mmol) and freshly
distilled 2-thiophenecarboxaldehyde (2.80 mL, 30 mmol) were re-
fluxed in 60 mL of anhydrous methanol for 6 h. On evaporating
the solvent a light yellow solid was obtained, which on recrystal-
lization from n-hexane gave colorless needles suitable for X-ray
analysis. Yield: 2.98 g (80%); m.p. 91Ϫ93 °C. C12H12N2S2 (248.36):
calcd. C 58.01, H 4.87, N 11.28, S 25.83; found C 58.05, H 4.83,
N 11.32, S 25.87. EI-MS: m/z (%) ϭ 248.1 (20) [Mϩ], 124 (55) [Mϩ/
2]. FTIR (KBr): ν˜ ϭ 507 (m), 577 (m), 648 (w), 715 (vs), 792 (vs),
1
1435 (s), 1611 (vs), 2850 (wb), 2910 (m), 3099 (s) cmϪ1. H NMR
[200 MHz, (CD3)2SO, TMS]: δ ϭ 8.68 (s, 4 H), 7.52 (d, J ϭ 4 Hz,
4 H), 7.27 (d, J ϭ 4 Hz, 4 H), 7.05 (dd, J ϭ 2 and 4 Hz, 4 H), 4.17
(s, methylene, 8 H) ppm. UV/Vis (CH2Cl2): λmax (ε) ϭ 415 sh
(2480), 345 sh (8785), 282 (22080), 266 nm (31250 Ϫ1·cmϪ1).
841 (s), 860 (s), 955 (s), 1051 (s, split), 1192 (m), 1235 (vs), 1284 [Cu(2)2]ClO4 (7): This complex was prepared similarly by treating
(s), 1326 (m), 1430 (s), 1635(vs), 2848 (wb), 2908 (wb), 3099 (s)
[Cu(CH3CN)4]ClO4 (0.165 g, 0.5 mmol) with 2 (0.25 g, 1 mmol) in
50 mL of anhydrous methanol under argon. Yield: 0.16 g (48%).
1
cmϪ1. H NMR (200 MHz, CDCl3, TMS): δ ϭ 8.35 (s, 2 H), 7.35
(d, J ϭ 4 Hz, 2 H), 7.27 (d, J ϭ 4 Hz, 2 H), 7.04 (dd, J ϭ 2 and Single crystals were grown by direct diffusion of n-hexane into a
4 Hz, 2 H), 3.91 (s, methylene, 4 H) ppm. 13C NMR (200 MHz, dichloromethane solution of the complex. C24H24ClCuN4O4S4
CDCl3, TMS): δ ϭ 155.96, 142.27 (quaternary), 130.46, 128.70,
127.27, 60.92 ppm. UV/Vis (CH2Cl2): λmax (ε) ϭ 284 (24975),
261 nm (28160 Ϫ1·cmϪ1).
(659.70): calcd. C 43.67, H 3.67, Cu 9.63, N 8.49, S 19.45; found
C 43.69, H 3.74, Cu 9.74, N 8.44, S 19.47. FTIR (KBr): ν˜ ϭ 628
(m), 722 (m, split), 787 (m), 832 (s), 910 (w), 1080 (vs), 1105 (vs),
1161 (m), 1236 (m), 1326 (w), 1371 (w), 1462 (s), 1614 (vs), 3096
(s) cmϪ1. 1H NMR [200 MHz, (CD3)2SO, TMS]: δ ϭ 8.42 (s, 4 H),
7.76 (br., 4 H), 7.55 (br., 4 H), 7.05 (br. 4 H), 4.08 (s, methylene, 8
H) ppm. UV/Vis (CH3OH): λmax (ε) ϭ 410 sh (2405), 347 sh (7250),
254 nm (34320 Ϫ1·cmϪ1).
Ligand 2: This compound was prepared by following a similar pro-
cedure starting with distilled ethylenediamine (1 mL, 15 mmol) and
freshly distilled 3-thiophenecarboxaldehyde (2.63 mL 30 mmol) to
obtain shiny white crystals, suitable for X-ray analysis. Yield: 2.66 g
(71%); m.p. 97 °C. C12H12N2S2 (248.36): calcd. C 58.01, H 4.87, N
11.28, S 25.83; found C 58.08, H 4.91, N 11.27, S 25.90. EI-MS:
[Cu(1)2](CF3SO3)2 (8): Ligand 1 (0.25 g, 1 mmol) was dissolved in
m/z (%) ϭ 248.1 [Mϩ] (20), 124 [Mϩ/2] (55). FTIR (KBr): ν˜ ϭ 575 20 mL of acetonitrile. To this colorless solution 5 mL of an aceton-
(m), 625 (s), 717 (m), 789 (vs), 828 (s), 878 (m), 902 (m), 1021 (vs), itrile solution of Cu(CF3SO3)2 (0.18 g, 0.5 mmol) was added drop-
1070 (m), 1160 (s, split), 1240 (vs), 1291 (s), 1346 (w), 1354 (m),
wise with constant stirring. The solution turned bottle green. Di-
1426 (m), 1458 (s), 1641 (vs), 2844 (wb), 3049 (m, split), 3091 (s) ethyl ether was then added dropwise to this solution until precipita-
1
cmϪ1. H NMR (200 MHz, CDCl3, TMS): δ ϭ 8.28 (s, 2 H), 7.57
tion occurred. The reaction mixture was kept in a refrigerator for
(d, J ϭ 4 Hz, 2 H), 7.51 (d, J ϭ 4 Hz, 2 H), 7.30 (dd, J ϭ 2 and 10 min. The green precipitate was then filtered off, washed with
4 Hz, 2 H), 3.90 (s, methylene, 4 H) ppm. 13C NMR (200 MHz, diethyl ether, and dried in air. Yield: 0.44 g (51%).
CDCl3, TMS): δ ϭ 156.98, 140.32 (quaternary), 128.44, 126.30,
C26H24CuF6N4O6S6 (858.12): calcd. C 36.36, H 2.82, Cu 7.40, N
125.66, 61.57 ppm. UV/Vis (CH2Cl2): λmax (ε) ϭ 250 nm (31945 6.53, S 22.42; found C 36.41, H 2.85, Cu 7.47, N 6.49, S 22.48.

Ϫ1·cmϪ1).
FTIR (KBr): ν˜ ϭ 528 (w), 535 (m), 641 (s), 736 (s), 867 (m), 1118
(m), 1211 (m), 1268 (vs, split), 1338 (m), 1418 (s), 1621 (vs), 2912
(wb), 3095 (m) cmϪ1. UV/Vis (CH3CN): λmax (ε) ϭ 613 (215), 287
(34225), 264 nm (35075 Ϫ1·cmϪ1).
Ligand 3: Benzil dihydrazone (1.87 g, 7.85 mmol), synthesized by a
reported procedure,[22] was dissolved in 50 mL of anhydrous meth-
anol. To this solution, freshly distilled 2-thiophenecarboxaldehyde
(1.47 mL, 15.70 mmol) was added. The resulting yellowish mixture
was refluxed for 6 h, maintaining dry conditions. Then it was slowly
cooled to room temperature to yield a yellowish crystalline solid,
which was filtered off and dried in air. Crystals suitable for X-
ray analysis were obtained by slow concentration of an acetonitrile
[Cu(4)2](CF3SO3)2 (9): Complex 8 (0.43 g, 0.5 mmol) was dissolved
in 15 mL of acetonitrile. To this solution 10 mL of diethyl ether
was added. This green solution was kept in the refrigerator for 8 h.
Light pink colored crystals, suitable for X-ray analysis were depos-
ited. These were filtered and dried in vacuo over fused CaCl2.
solution. Yield 2.15 g (64%); m.p. 159Ϫ160 °C. C24H18N4S2 Yield: 0.095 g (28%). C16H20CuF6N4O6S4 (670.14): calcd. C 28.66,
(426.54): calcd. C 67.56, H 4.26, N 13.14, S 15.05; found C 67.58, H 3.01, Cu 9.48, N 8.36, S 19.14; found C 28.72, H 2.95, Cu 9.43,
H 4.29, N 13.19, S 14.99. FTIR (KBr): ν˜ ϭ 525(m), 596 (m), 610 N 8.42, S 19.18. FTIR (KBr): ν˜ ϭ 515 (m), 576 (m), 635 (s), 755
(m), 685 (vs), 712 (vs), 764 (vs, split), 835 (w), 919 (m), 1050 (s),
(m), 1042 (vs, split), 1112 (m), 1170 (vs), 1265 (vs, split), 1486 (m),
1074 (m), 1175 (m), 1212 (s), 1237 (m, split), 1299 (w), 1326 (m), 1625 (vs), 2895 (w), 3305 (vb) cmϪ1. UV/Vis (CH3CN): λmax (ε) ϭ
1424 (vs), 1445 (s), 1490 (s), 1605 (vs), 2840 (wb), 2917 (w), 3105(s) 587 (150), 281 (28470), 269 nm (28750 Ϫ1·cmϪ1).
cmϪ1 1H NMR (200 MHz, CDCl3, TMS): δ ϭ 8.65 (s, 2 H),
.
[Ag(1)2](ClO4) (10): Ligand 1 (0.25 g, 1 mmol) was dissolved in
15 mL of methanol. To this solution 5 mL of a methanol solution
of AgClO4 (0.105 g, 0.5 mmol) was added dropwise with constant
stirring, causing an off-white solid to precipitate. It was kept in air
for 1 h, then filtered off, washed with 2 mL of methanol and dried
in vacuo over fused CaCl2. Yield: 0.19 g (54%). Single crystals suit-
able for X-ray analysis were grown by slow concentration of an
8.05Ϫ7.99 (m, 6 H), 7.97Ϫ7.90 (m, 6 H), 7.30 (d, 2 H), 7.10 (d, 2
H), 6.96 (dd, 2 H) ppm. 13C NMR (200 MHz, CDCl3, TMS): δ ϭ
164.86 (quaternary), 162.40 (quaternary), 155.65, 148.31, 139.22
(quaternary), 134.19, 133.50, 131.75, 128.80, 127.22 ppm. UV/Vis
(CH2Cl2): λmax (ε) ϭ 328 (35 600), 276 (28 690), 257 nm (26845

Ϫ1·cmϪ1). EI-MS: m/z (%) ϭ 426.1 [Mϩ] (15).
[Cu(1)2]ClO4 (6): Solid [Cu(CH3CN)4]ClO4 (0.165 g, 0.5 mmol) was acetonitrile solution. The compound crystallizes with half a molec-
added to 30 mL of an anhydrous, degassed methanol solution of 1
(0.25 g, 1 mmol) under argon, and stirred for 1 h maintaining dry
ule of the acetonitrile solvent. C24H24AgClN4O4S4 (704.03): calcd.
C 40.92, H 3.44, N 7.96, S 18.22; found C 40.95, H 3.39, N 10.89,
974
Eur. J. Inorg. Chem. 2003, 969Ϫ977

Copper and Silver Complexes with New Imine Ligands
FULL PAPER
S 18.26. FTIR (KBr): ν˜ ϭ 505 (m), 581 (w), 623 (s), 715 (vs), 842
grown by slow evaporation of the methanol solution of the com-
plex. C24H24AgClN4O4S4 (704.03): calcd. C 40.92, H 3.44, N 7.96,
(s), 951 (m), 1085 (vs, split), 1217 (m), 1285 (m), 1326 (w), 1430
(s), 1459 (m), 1631 (vs), 2861 (wb), 3100 (m) cmϪ1 1H NMR S 18.22; found C 40.97, H 3.48, N 7.91, S 18.28. FTIR (KBr): ν˜ ϭ
.
[200 MHz, (CD3)2SO, TMS]: δ ϭ 8.83 (s, 4 H), 7.74 (d, J ϭ 4 Hz, 579 (w), 625 (vs), 715 (w), 790 (vs), 867 (m, split), 951 (m), 1081
4 H), 7.61 (d, J ϭ 4 Hz, 4 H), 7.14 (dd, J ϭ 2 and 4 Hz, 4 H), 4.06 (vs, split), 1237 (m), 1291 (s), 1346 (m), 1407 (m), 1457 (s), 1522
(s, methylene, 8 H) ppm. UV/Vis (CH3CN): λmax (ε) ϭ 281 (28385), (m), 1640 (vs), 2843 (wb), 2904 (w), 3098 (m) cmϪ1 1H NMR
.
260 nm (32155 Ϫ1·cmϪ1).
[200 MHz, (CD3)2SO, TMS]: δ ϭ 8.68 (s, 4 H), 8.15 (d, J ϭ 4 Hz,
4 H), 7.73 (d, J ϭ 4 Hz, 4 H), 7.63 (dd, J ϭ 2 and 4 Hz, 4 H), 3.94
(s, methylene, 8 H) ppm. UV/Vis (CH3CN): λmax (ε) ϭ 248 nm
(37535 Ϫ1·cmϪ1).
[Ag(2)2](ClO4) (11): Silver perchlorate (0.105 g, 0.5 mmol) was ad-
ded to a solution of 2 (0.25 g, 1 mmol) in 20 mL of methanol. The
reaction mixture was stirred at room temperature for 1 h. A light
yellow compound precipitated. This was filtered off, washed with
a few drops of methanol and dried in vacuo over fused CaCl2.
Yield: 0.16 g (46%). Single crystals suitable for X-ray analysis were
Ligand 5: 4-Cyanobenzaldehyde (3.93 g, 30 mmol) was dissolved in
150 mL of anhydrous methanol. To this solution distilled tris(2-
aminoethyl)amine (1.5 mL, 10 mmol) was added dropwise. The re-
Table 1. Crystal and experimental data related to the structural analyses
Compound
2[a]
3
6[b]
7[b]
9[c]
Empirical formula
Formula mass
Crystallization solvent
Crystal system
C12H12N2S2
248.36
Ϫ
monoclinic
C2/c
22.0020(9)
5.4920(3)
10.3350(4)
90
100.836(3)
90
1226.6(1)
4
0.41
110
1.345
C24H18N4S2
426.54
Ϫ
monoclinic
P21/c
11.2690(3)
7.5640(2)
24.4540(8)
90
91.429(1)
90
2083.7(1)
4
0.27
110
1.360
2C12H12N2S2·CuClO4 2C12H12N2S2·CuClO4
2C7H10N2S·Cu(CF3SO3)2
670.14
Ϫ
monoclinic
P21/c
13.0240(2)
10.2440(2)
10.1090(4)
90
111.150(1)
90
1257.9(1)
2
1.29
110
659.70
Ϫ
659.70
Ϫ
monoclinic
P21/c
23.3760(2)
14.1940(2)
17.7390(4)
90
monoclinic
P21/n
17.7670(2)
17.3330(1)
17.8660(2)
90
Space group
˚
a [A]
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
111.005(5)
90
91.412(4)
90
3
˚
V [A ]
5494.7(2)
8
1.23
5500.3(1)
8
1.23
Z
µ(Mo-Kα) [mmϪ1
T [K]
]
110
1.595
55.8
110
1.593
55.8
Dc [g·cmϪ3
2θmax [°]
No. unique reflections
]
1.769
56.4
2985
56.5
1457
55.0
4703
2733
12630
8664
12868
9930
No. reflections (I Ͼ 2σ) 1192
2524
No. refined parameters
R1 (I Ͼ 2σ)
R1 (all data)
73
271
0.053
0.116
0.142
685
918
169
0.037
0.049
0.101
0.36
0.042
0.082
0.103
0.57
0.049
0.070
0.145
1.08
0.030
0.040
0.079
0.41
wR2 (all data)
Ϫ3
˚
|∆ρ|max [e·A
]
0.39
Compound
10[b]
11[b]
12
13
Empirical formula
Formula mass
Crystallization solvent
Crystal system
2C12H12N2S2·AgClO4 2C12H12N2S2·AgClO4 C30H27N7·CuClO4
C30H27N7·Ag(C2H3N)ClO4
724.56
1/2C2H3N
monoclinic
P21
12.9450(1)
14.5890(2)
16.9380(2)
90
110.281(1)
90
3000.5(1)
4
704.03
726.69
754.49
1/2C2H3N
monoclinic
C2/c
15.3070(2)
20.0510(3)
22.6490(5)
90
104.893(1)
90
6717.9(2)
8
0.73
110
1.492
56.5
8032
5668
C2H3Nϩ1/2C4H10
triclinic
O
monoclinic
P21/c
23.0490(2)
14.3170(2)
18.2170(2)
90
107.011(1)
90
5748.5(1)
8
¯
Space group
P1
˚
a [A]
12.1820(2)
12.4590(2)
12.6410(4)
84.618(1)
78.889(1)
65.524(1)
1713.2(1)
2
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
3
˚
V [A ]
Z
µ(Mo-Kα) [mmϪ1
T [K]
]
1.08
110
1.12
110
0.77
110
Dc [g·cmϪ3
2θmax [°]
No. unique reflections
]
1.60
55.9
1.627
55.8
1.409
55.0
7283
13665
9261
7581
5405
No. reflections (I Ͼ 2σ) 6780
No. refined parameters
R1 (I Ͼ 2σ)
R1 (all data)
721
685
0.051
0.097
0.114
443
0.051
0.084
0.137
439
0.041
0.075
0.107
0.031
0.036
0.072
0.77
wR2 (all data)
Ϫ3
˚
|∆ρ|max [e·A
]
0.86
0.71
0.76
[a]
[b]
Molecules are located on symmetry axes of twofold rotation.
The crystallographic asymmetric unit contains two independent
[c]
moieties of the complex. The metal complex is located on centers of inversion.
Eur. J. Inorg. Chem. 2003, 969Ϫ977
975

G. K. Patra, I. Goldberg
FULL PAPER
action mixture was refluxed for 8 h maintaining dry conditions.
Then, it was transferred into a beaker and left in the air overnight.
A yellowish solid precipitated. This was filtered off, washed with
5 mL of methanol, dried in the air, and then recrystallized from
ized in Table 1. The structures were solved by direct (SHELXS-86,
SIR-92, SIR-97)[23,24] and Patterson methods (DIRDIF-96),[25] and
refined by full-matrix least squares on F2 (SHELXL-97).[26] Intens-
ity data of the silver-containing structures were corrected for ab-
acetonitrile. Yield: 3.2 g (66%); m.p. 135Ϫ137 °C. C30H27N7 sorption effects. All non-hydrogen atoms were refined aniso-
(485.27): calcd. C 74.19, H 5.61, N 20.20; found C 74.26, H 5.66,
tropically. The hydrogen atoms were located in idealized positions,
N 20.14. EI-MS: m/z (%) ϭ 486.2 [MHϩ] (30). FTIR (KBr): ν˜ ϭ and were refined using a riding model with fixed thermal para-
553 (s), 646 (m), 834 (vs), 927 (m), 1023 (m), 1067 (vs), 1158 (w), meters [Uij ϭ 1.2·Uij(eq.) of the atom to which they are bonded].
1221 (w), 1287 (m), 1375 (s), 1440 (m), 1503 (m), 1642 (vs), 2221 CCDC-188495 to -188503 for compounds 2, 3, 6, 7, 9, 10, 11, 12,
(vs), 2841 (wb), 3428 (vb) cmϪ1
TMS): δ ϭ 8.19 (s, 3 H), 7.67 (m, 12 H), 3.74 (t, methylene, 6 H),
2.97 (t, methylene, 6 H) ppm. 13C NMR (200 MHz, CDCl3, TMS): www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
δ ϭ 159.73, 139.86 (quaternary), 132.31, 128.26, 118.30 (quatern- Crystallographic Data Center, 12 Union Road, Cambridge
44-1223/336033; E-mail:
.
1H NMR (200 MHz, CDCl3, and 13, respectively, contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge at
ary), 113.79 (quaternary), 60.08, 55.20 ppm. UV/Vis (CH2Cl2): CB2 1EZ, UK; Fax: (internat.)
ϩ
λmax (ε) ϭ 255 nm (38120 Ϫ1·cmϪ1).
deposit@ccdc.cam.ac.uk].
[Cu(5)]ClO4 (12): Complex 5 (0.243 g, 0.5 mmol) was dissolved in
35 mL of anhydrous methanol by warming. Argon was purged
through the solution and it was then cooled to room temperature.
After 15 min, solid [Cu(CH3CN)4]ClO4 (0.165 g, 0.50 mmol) was
added to the degassed methanol solution. The reaction mixture was
stirred at room temperature under argon for 1 h, maintaining dry
conditions. A reddish yellow compound precipitated. This was fil-
tered off, washed with 2 mL of methanol, and dried in vacuo over
fused CaCl2. Yield: 0.148 g (46%). Single crystals were grown by
direct diffusion of diethyl ether into a concentrated acetonitrile so-
lution of the complex. The compound crystallizes with one molec-
Acknowledgments
The authors thank the Israeli Science Foundation for support of
this work.
[1]
C. E. Housecroft, Coord. Chem. Rev. 1994, 131, 1Ϫ43.
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J. A. Marshall, K. G. Pinney, J. Org. Chem. 1993, 58,
[2b]
ule of acetonitrile and half
a molecule of diethyl ether.
7180Ϫ7184.
J. A. Marshall, C. A. Sehon, J. Org. Chem.
[2c]
C30H27ClCuN7O4 (648.58): calcd. C 55.53, H 4.20, Cu 9.80, N
15.11; found C 55.61, H 4.25, Cu 9.91, N 15.08. FTIR (KBr): ν˜ ϭ
556 (s), 624 (s), 829 (s), 890 (m), 1090 (vs, split), 1286 (m), 1390
1995, 60, 5966Ϫ5968.
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1
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H), 7.46 (d, 6 H), 3.88 (s, methylene, 6 H), 3.12 (s, methylene, 6 H)
ppm. UV/Vis (CH2Cl2): λmax (ε) ϭ 379 (2526), 251 nm (30730
55, 5935Ϫ5936.
[4]
[5]
[6]
[7]
[8]
K. Burgess, H.-J. Lim, A. M. Porte, G. A. Sulikowski, Angew.
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
Ϫ1·cmϪ1).
[Ag(5)(CH3CN)]ClO4 (13): Silver perchlorate (0.105 g, 0.5 mmol)
was added to a solution of 5 (0.243 g, 0.5 mmol) in 25 mL of ace-
tonitrile. The reaction mixture was stirred at room temperature for
1 h and was then kept in a refrigerator for 24 h. Large colorless
blocks, which were suitable for X-ray analysis, separated. They were
filtered off, washed with a few drops of methanol, and dried in
vacuo over fused CaCl2. Yield 0.155 g (42%). One molecule of the
acetonitrile solvent was found coordinated to the silver ion (an-
other noncoordinated acetonitrile was found included in the lattice
with partial occupancy). C32H30AgClN8O4 (733.79): calcd. C 52.34
H 4.12, N 15.27; found C 52.60, H 4.10, N 15.32. FTIR (KBr):
ν˜ ϭ 552 (s), 623 (s), 833 (s), 927 (m), 972 (w), 1091 (vs, split), 1220
(w), 1288 (m), 1374 (m), 1505 (m), 1563 (w), 1633 (vs), 2226 (vs),
2842 (wb), 3442 (vb) cmϪ1. 1H NMR [200 MHz, (CD3)2SO, TMS]:
δ ϭ 8.61 (s, 3 H), 7.93 (m, 12 H), 3.81 (br., methylene, 6 H), 2.98
(br., methylene, 6 H), 2.07 (s, 3 H) ppm. UV/Vis (CH3CN): λmax
(ε) ϭ 248 nm (26500 Ϫ1·cmϪ1). Caution: Perchlorates are poten-
tially explosive and should not be prepared and stored in large
amounts.
[9]
[10]
[11]
[12]
[13] [13a]
A. Deroche, I. Morgensteen-Badarau, M. Cesario, J. Gu-
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[13b]
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[13c]
P. G. Sim, E. Sinn, J.
Am. Chem. Soc. 1981, 103, 241Ϫ243.
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1998, 275Ϫ276, 234Ϫ241.
Ligand 4 is a 1:1 condensate of 2-thiophenecarboxaldehyde
and ethylenediamine. If it is allowed to stand in solution for
more than 48 h, however, we obtain only the bis(ethylenediami-
ne)CuII complex [Cu(en)2](CF3SO3)2.
V. Vrabel, J. Garaj, J. Sivy, D. Oktavec, Acta Crystallogr., Sect.
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Crystallography: The diffraction measurements were carried out
with a Nonius KappaCCD diffractometer, using graphite-mono-
˚
chromated Mo-Kα radiation (λ ϭ 0.7107 A). Crystalline samples of
the analyzed compounds were covered with a thin layer of light oil
and freeze-cooled to 110 K in order to minimize solvent escape (if
present), structural disorder (particularly of the anions) and ther-
mal motion effects, and to increase the precision of the results. The
crystal and experimental data for all the compounds are summar-
[16]
[17]
976
Eur. J. Inorg. Chem. 2003, 969Ϫ977

Copper and Silver Complexes with New Imine Ligands
FULL PAPER
M. Cascarano, C. Giacovazzo, A. Guagliardi, G. Polidori, J.
Appl. Crystallogr. 1994, 27, 435Ϫ436.
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