Synthesis, crystallographic and spectroscopic studies of dimeric Cui complexes with Schiff-base-containing triazole ligands

Article abstract of DOI:10.1002/ejic.200390202

New Cu^I complexes of the Schiff-base-containing triazole ligands N-[(E)-(4-chlorophenyl)methylidene]-4H-1,2,4-triazol-4-amine (C1Phtrz) and N-[(E)-phenylmethylidene]-4H-1,2,4-triazol-4-amine (Phtrz) have been synthesised and characterised. Depe

Full text of DOI:10.1002/ejic.200390202

FULL PAPER
Synthesis, Crystallographic and Spectroscopic Studies of Dimeric CuI
Complexes with Schiff-Base-Containing Triazole Ligands
Krzysztof Drabent,*[a] Zbigniew Ciunik,[a] and Piotr J. Chmielewski[a]
Keywords: Copper / Schiff bases / N ligands / Dimers / Self-assembly
New CuI complexes of the Schiff-base-containing triazole li-
of the CuI ions is formed by two monodentate and two bi-
gands N-[(E)-(4-chlorophenyl)methylidene]-4H-1,2,4-triazol- dentate (bridging) Phtrz ligands. Complexes 1−3 are unstable
4-amine (ClPhtrz) and N-[(E)-phenylmethylidene]-4H-1,2,4-
triazol-4-amine (Phtrz) have been synthesised and charac- lecules giving 4 (from 1 and 2) and 5 (from 3). On the basis
terised. Depending on the reaction conditions ClPhtrz forms
of ESI MS and 1H NMR and UV/Vis spectroscopy, it was
two different dimeric complexes 1 and 2. X-ray crystallo- shown that dimeric complexes 1−5 do not survive upon dis-
and easily lose coordinating and/or solvating acetonitrile mo-
graphy revealed that each copper centre exhibits a planar
trigonal coordination in 1, while the tetrahedral coordination
sphere of the copper centre in 2 is completed by a solvent
molecule. In dimeric complex 3 the tetrahedral coordination
solution and dissociate rapidly forming mainly a 1:2 mono-
meric complex, along with a minor 1:1 complex.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
are always connected to two adjacent copper() ions in an
N1,N2-bridging mode.
Similar coordination properties could be expected for N4-
substituted 1,2,4-triazole as a ligand. In fact, a number of
coordination compounds with this group of ligands coordi-
nated to transition metal ions have been reported.[2] How-
ever, to the best of our knowledge, CuI complexes of N4-
substituted 1,2,4-triazoles are unknown. A limited number
of structurally characterised systems based on copper() and
deprotonated 1,2,4-triazolates have been reported.[13,14] In
these systems the nitrogen atoms of the triazolate anion are
coordinated to three different CuI ions, forming polynuclear
species; copper() complexes with a 1,2,4-triazole moiety as
a part of an organic ligand have also been reported.[15Ϫ18]
In this work we describe the synthesis of dimeric cop-
per() complexes with Schiff-base-containing triazole li-
gands (Scheme 1). The complexes were characterised by X-
ray crystallography. The results are compared with those
reported for pyrazole-bridged CuI dimers. We also report
the results of our study on the behaviour of these systems
upon dissolution in acetonitrile.
Binuclear and multinuclear transition metal complexes
containing two or more metal centres bridged by multiden-
tate ligands have been the subject of great interest in coordi-
nation chemistry.[1] Particular interest has been focused on
five-membered aromatic nitrogen heterocycles (azoles) as li-
gands because of their ability to form complexes in which
two metal centres are bridged by one, two or three azole
groups.[1,2] The most studied bridging ligand of this type
is the pyrazolate anion.[3,4] Recently, copper() complexes
containing pyrazolate ligands have been extensively studied
due to their ability to act as selective catalysts in the oxi-
dation of organic substrates such as aliphatic and aromatic
amines.[5,6] Different pyrazoles modified by introducing
substituents on the heterocyclic ring have been involved in
these studies.[5Ϫ7] Depending on the ring substituent cop-
per() forms a large series of derivatives: neutral 1-D poly-
mers [Cu(pz)]ϱ for unsubstituted pyrazole,[8] cyclic trimers
[Cu(pzЈ)]3 [pzЈ ϭ 3,5-dimethyl-4-nitropyrazole (Hdmnpz),[6]
3,5-dimethylpyrazole (Hdmpz),[9] 3,5-diphenylpyrazole
(Hdppz),[10] 3,4,5-trimethylpyrazole (tmpzH)[11]] and cyclic
[5]
neutral [Cu(dppz)]4
and anionic tetramers [Cu4-
Results and Discussion
(dmnpz)6]Ϫ2 [6]
.
However, the most frequently observed
structure is a dimer [Cu2(pzЈЈ)2Xn] [where pzЈЈ ϭ dmpz,
dcmpz, dppz, dmnpz (Hdcmpz ϭ 3,5-dicarbomethoxy
pyrazole); X ϭ isocyanide, pyridine, PPh3].[5Ϫ8,12] The com-
mon feature of all these compounds is that pyrazole ligands
Depending on the experimental conditions two products
were obtained from the reaction between [Cu(CH3CN)4]-
(ClO4) and N-[(E)-(4-chlorophenyl)methylidene]-4H-1,2,4-
triazol-4-amine (ClPhtrz) in acetonitrile. Colourless, needle-
shaped crystals of [Cu2(ClPhtrz)4](ClO4)2·2CH3CN (1) were
grown overnight from a concentrated solution. When the
crystallisation was carried on from a very dilute solution
light-yellow, prismatic crystals of [Cu2(ClPhtrz)4-
[a]
Faculty of Chemistry, University of Wrocław,
F. Joliot-Curie 14, 50-383 Wrocław, Poland
Fax: (internat.) ϩ 48-71/328-2348
E-mail: drab@wchuwr.chem.uni.wroc.pl
1548  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0408Ϫ1548 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2003, 1548Ϫ1554

Dimeric CuI Complexes with Schiff-Base-Containing Triazole Ligands
FULL PAPER
groups in the 3,5-positions of the ligand and the cyclohexyl
isocyanide groups attached to the copper ions.
Scheme 1
(CH3CN)2](ClO4)2·CH3CN (2) were formed after a much
longer time (about 1 month).
The main difference between dimers 1 and 2 is the coor-
dination mode around each copper atom: in 1 the metal
ion is coordinated by three triazole ligands whereas in 2
additional coordination of an acetonitrile molecule gives a
tetrahedral environment for the copper() ion.
The procedure described above is valid for a 1:2 metal-
to-ligand ratio or with an excess of ligand in solution. When
an excess of metal ion is used only 2 is formed. In the case
Figure 1. Molecular structure of the dimeric compound 1; selected
˚
bond lengths [A] and angles [°]: Cu1···Cu1a 3.508(1), Cu1ϪN11
of [Cu2(Phtrz)6](ClO4)2·2CH3CN (3) the complex is formed
in any metal-to-ligand molar ratio. When crystals of 1Ϫ3
are removed from acetonitrile solution they rapidly lose
acetonitrile molecules (within a few minutes; see Exp. Sect.).
In this way crystals of 1 and 2 give [Cu2(ClPhtrz)4](ClO4)2
(4), whereas 3 gives [Cu2(Phtrz)6](ClO4)2 (5). Crystals of
1Ϫ3 were characterised crystallographically, while com-
plexes 4 and 5 were studied by spectroscopic methods (UV,
1H NMR, ESI-MS).
1.948(3),
Cu1ϪN21
1.937(3),
Cu1ϪN12a
2.012(3);
N21ϪCu1ϪN11
131.57(13),
N21ϪCu1ϪN12
113.12(13),
N11ϪCu1ϪN12 114.89(12), Cu1ϪN11ϪN12ϪCu1 13.8(4)
Because all the ClPhtrz ligands are coordinated in an al-
most planar E configuration the resulting binuclear unit can
be described as an X-shaped dimer. These X-shaped dimers
strongly influence the packing of the discrete units in the
crystal (Figure 2). The dimers form sheets with an average
˚
distance of 3.04 A between the planes. The chlorine atoms
Structural Studies
of the ligands (see Scheme 1) are located above and below
˚
each copper() ion [Cu···Cl ϭ 3.129(1) and 3.242(1) A,
X-ray Structure of 1
respectively; Cl···Cu···Cl ϭ 158.44(3)°] and are believed to
The molecular structure of 1 is shown in Figure 1. It con- stabilise the packing. As a result rhomboidal channels, de-
sists of a discrete binuclear copper() centre bridged by two fined by the separation of the centre of Cu-[N-N]2-Cu frag-
N1,N2-coordinated ClPhtrz ligands. Surprisingly, an ad- ments, are observed parallel to the crystallographic [100]
ditional triazole ligand is bound to the CuI ion in a monod- direction with a cross-section of about 15 ϫ 15 A. The
˚
Ϫ
entate fashion. This unprecedented coordination mode re- ClO4 anions and solvent (acetonitrile) molecules are posi-
sults in almost planar tricoordinate, trigonal coordination tioned in these channels (see Figure 2). Location of the non-
˚
environment with a small deviation [0.073(2) A] of the me- coordinating solvent molecules in the channels makes them
tal centre from the plane defined by the N11, N12A and potentially labile and easy to remove from the crystals. The
N21 atoms. The non-bonding Cu···Cu distance is equal to free-pore volume of the unit cell was estimated to be 696
3
(25.2% of the total) with the PLATON[19] program
˚
˚
3.508(1) A. A slight deviation from planarity toward a
A
chair-like configuration is observed due to the asymmetric (squeeze).
triazole ligands forming a six-membered Cu-[N-N]2-Cu
ring. The copper atoms are located only 0.202(6) A off the 1 is rare for dinuclear compounds, but not unknown, and
A trigonal environment of CuI such as that observed in
˚
mean plane defined by four triazole nitrogens, well below has been reported previously for complexes with pyrazole
bridges.[5Ϫ7,12,20] However, in all those systems at least one
I
[5]
˚
the value reported for the Cu -pyrazole system (0.62 A).
Furthermore, the Cu-N-N-Cu dihedral angle of 13.8(4)° is other ligand coordinates to the copper ion. Three-coordi-
considerably smaller than that observed (41.7°) for the nate copper() has also been detected in polymeric systems
pyrazole-containing complex [Cu(dppz)(RNC)]2 with the with different ligands.[14,21,22] The dimers derived from tris-
same conformation.[5] In the latter compound it has been (pyrazolyl)borate[23] and tris(imidazole)methoxymethane[24]
suggested that the large value of the dihedral angle is due are rare examples of tricoordinate CuI complexes without
to the presence of steric interactions between the phenyl bridges between the metals.
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554
1549

K. Drabent, Z. Ciunik, P. J. Chmielewski
FULL PAPER
fined by two copper and the four nitrogen atoms of bridg-
ing ligands. The observed chair-like conformation in 2 is
more pronounced than in 1 and the Cu-N-N-Cu torsion
˚
angle is 34.2(3)°. The copper atoms are located 0.516(5) A
out of the plane defined by the four nitrogens of the bridg-
ing triazole ligands. Each metal ion is moved towards the
coordinated acetonitrile molecules. The observed CuϪN
˚
distances [1.990(3) to 2.083(3) A] lie well within the range
for tetracoordinate copper() complexes[6,25] and are about
˚
0.1 A longer than the CuϪN bond lengths observed in 1
and other tricoordinate CuI structures.[5Ϫ8,12] The non-
˚
bonding Cu···Cu distance increases from 3.508(1) A in 1 to
˚
3.685(1) A in 2. The same tendency was reported previously
for tri- and tetracoordinate pyrazole-containing dimers of
CuI.[6]
X-ray Structure of 3
Another tetracoordinate complex 3 was obtained when
the 4-chlorophenyl group in the triazole ligand was replaced
by a phenyl substituent. A view of the molecule is shown
in Figure 4. Compound 3 is a dinuclear CuI complex con-
taining two bridging triazole groups as in the case of 1 and
2. Surprisingly two additional triazole ligands are coordi-
nated to each copper() ion in a monodentate fashion to
give a coordination number of four, with all four coordi-
nation sites being occupied by triazole ligands. The more-
regular tetrahedral surrounding of the CuI centres causes a
less-pronounced chair-like configuration of the Cu-[N-N]2-
Cu ring and, in fact, the copper atoms are located only
Figure 2. View of 1 along the crystallographic axis a illustrating
the channels; the disordered acetonitrile molecules have been omit-
ted for clarity
X-ray Structure of 2
When a dilute solution of [Cu(CH3CN)4](ClO4) and
ClPhtrz ligand in acetonitrile was allowed to stand for a
long time (about one month) light-yellow crystals of 2 were
formed. The molecular structure of 2 is shown in Figure 3.
The crystals of 2 contain discrete dimeric complexes of CuI
bridged by two ClPhtrz ligands. Another triazole ligand is
bonded in a monodentate fashion to each copper atom, as
was observed for 1. A molecule of acetonitrile completes
the distorted tetrahedral coordination geometry. The in-
creased steric crowding around the metal atoms consider-
ably disturbs the planarity of the six-membered cycle de-
˚
0.152(3) A out of the plane defined by the bridging triazole
nitrogens. It is worth noting that this value matches well
Figure 3. Molecular structure of the dimeric compound 2; selected
Figure 4. Molecular structure of the dimeric compound 3; selected
˚
˚
bond lengths [A] and angles [°]: Cu1···Cu1a 3.685(1), Cu1ϪN11
bond lengths [A] and angles [°]: Cu1···Cu1a 3.6606(5), Cu1ϪN11
2.082(3), Cu1ϪN21 1.991(3), Cu1ϪN12a 2.028(3), Cu1ϪN1 2.0737(15), Cu1ϪN21 2.0376(16), Cu1ϪN31 2.0220(16),
2.013(3); N21ϪCu1ϪN1 116.02(11), N21ϪCu1ϪN12 120.68(10),
Cu1ϪN12 1.9923(15); N12ϪCu1ϪN31 119.72(6), N12ϪCu1ϪN21
106.58(10), 113.46(6), N31ϪCu1ϪN21 107.02(6), N12ϪCu1ϪN11 112.01(6),
109.16(10), N31ϪCu1ϪN11 102.58(6), N21ϪCu1ϪN11 99.71(6),
Cu1ϪN11ϪN12ϪCu1 Ϫ10.3(2)
N1ϪCu1ϪN12
N1ϪCu1ϪN11
102.33(10),
100.12(10),
N21ϪCu1ϪN11
N12ϪCu1ϪN11
Cu1ϪN11ϪN12ϪCu1 34.2(3)
1550
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554

Dimeric CuI Complexes with Schiff-Base-Containing Triazole Ligands
FULL PAPER
with the value observed in the tricoordinate compound 1, causes the complete substitution of Phtrz or ClPhtrz by
˚
although the CuϪN bond lengths [1.992(2) to 2.074(2) A] CH3CN in the first coordination sphere of the copper()
˚
and the nonbonding Cu···Cu distance [3.6606(5) A] are ion.
closer to those observed in 2.
Solution Studies
Mass Spectrometry
Formation of monomeric 1:2 and 1:1 complexes from the
dimer has been observed by ESI mass spectrometry upon
dissolution of original samples of 1, 2 or 4. Peaks at m/z
(%) ϭ 475.3 (100), 309.9 (70), 206.6 (10) and 144.5 (10) are
observed in the ESI mass spectra independently of the
sample used (see above). The isotopic peaks are separated
by 1.0 amu, revealing a charge state of ϩ1 for the corre-
sponding ions. Therefore, the peaks at 475.3 and 309.9
correspond to [Cu(ClPhtrz)2]ϩ and [Cu(ClPhtrz)-
(CH3CN)]ϩ species, respectively. No peaks characteristic of
the dimer entities could be detected in the ESI-MS spectra.
The formation of the 1:2 and 1:1 complexes from the pure
Figure 5. Electronic spectra of acetonitrile solutions of 4 (solid
dimeric complexes should be accompanied by the release of
both free ligand and free CuI cation. Indeed, weak peaks at
206.6 (for [ClPhtrz]ϩ) and at 144.5 (for [Cu(CH3CN)2]ϩ)
are observed during the ESI-MS analysis.
line), ClPhtrz (dashed line), and [Cu(CH3CN)4]ClO4 (dotted line)
1
The H NMR spectra of saturated solutions of the com-
plexes in CD3CN are consistent with the labile character of
the complexes and also reveal the dissociation of the dimers
upon dissolution in acetonitrile. The number of signals indi-
cates the degeneracy of the respective resonances, i.e. there
is only one peak for the azomethine group (NϭCH), the
triazole (trz) ring and each type of aryl ring proton (Fig-
ure 6). Differentiation of the chemical shifts is expected par-
ticularly for these protons that are in the vicinity of the
coordination sites if the solid-state structure of the complex
is retained in solution. Although the number of peaks is the
same for both the complex and for the appropriate free li-
gand, the positions of the peaks differ considerably [5
(Phtrz): δ ϭ 8.869 (8.844) ppm (NϭCH), 8.864 (8.791)
(trz); 4 (ClPhtrz): δ ϭ 8.845 (8.825) (NϭCH), 8.838 (8.777)
(trz) ppm; CD3CN, 233 K]. This suggests an equilibrium
between coordinated and free ligand in solution. Such an
equilibrium, which is fast on the NMR timescale, causes an
averaging of the chemical shifts. The considerable broaden-
ing of the triazole signal of the complex at low temperature
is also consistent with the presence of a fast chemical ex-
change between coordinated and uncoordinated ligand. Ti-
tration of the complex solution with free ligand does not
result in the appearance of any additional signals. Instead,
it gradually shifts the position of all the peaks to those of
the free ligand (Figure 6).
Unexpected ESI-MS spectra were obtained for complexes
3 and 5. Despite the different metal to triazole ligand ratio
in dimer 3 (2:6) than in dimers 1 and 2 (2:4) the fragmen-
tation led to the same pattern in the mass spectrum, i.e. a
monomeric 1:2 species at 406.9 (attributed to [Cu(Phtrz)2]ϩ)
and
a
1:1
species
at
276.2
(attributed
to
[Cu(Phtrz)(CH3CN)]ϩ). Dissociation of the parent dimer
results in two additional peaks at 172.2 and 144.1 corre-
sponding to free ligand [Phtrz]ϩ and solvated copper() cat-
ion [Cu(CH3CN)2]ϩ, respectively
On the basis of the electrospray mass spectrometry re-
sults it can be concluded that the dimeric complexes
[Cu2(ClPhtrz)4]ϩ2
,
[Cu2(ClPhtrz)4(CH3CN)2]ϩ2
,
and
[Cu2(Phtrz)6]ϩ2 do not survive upon dissolution and dis-
sociate rapidly to mainly form a 1:2 monomeric complex,
along with a minor 1:1 complex. Similar phenomena have
been observed for other CuI dimers.[23,24,26]
Spectroscopic Studies
The competitive equilibria related with dissociation of
the complexes can also be observed by UV/Vis and 1H
NMR spectroscopy. The UV spectra of 4 or 5 in acetonitrile
consist of two major bands: one centred at 210 nm and the
other at 283 nm. Both bands contain several shoulders.
Comparison of the spectrum obtained for the complex with
that of the free ligand reveals a close similarity of the lower
energy bands for each of the systems under study. In fact,
these spectra are superimposable in this region after nor-
malisation of the absorbance. The band at 210 nm can be
Conclusion
The results discussed here demonstrate that reaction be-
reproduced by a superposition of the spectra of an appro- tween [Cu(CH3CN)4](ClO4) and Schiff-base-containing
priate free ligand and that of [Cu(CH3CN)4]ϩ (Figure 5). triazole ligands in acetonitrile gives various dimeric cop-
Evidently, at the concentration level of electronic spec- per() complexes. The composition and geometry of these
troscopy the overwhelming excess of acetonitrile ligand complexes depend on the reaction conditions (compounds
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554
1551

K. Drabent, Z. Ciunik, P. J. Chmielewski
FULL PAPER
methylidene]-4H-1,2,4-triazol-4-amine (ClPhtrz)[29] were prepared
according to literature procedures. All reactions with CuI were car-
ried out under a dry nitrogen atmosphere using standard Schlenk
techniques.
Caution. Perchlorate salts of metal complexes with organic ligands
are potentially explosive. Only small quantities of the compound
should be prepared and handled with much care!
N-[(E)-(phenyl)methylidene]-4H-1,2,4-triazol-4-amine (Phtrz): An
ethanolic solution (20 mL) of benzaldehyde (2.12 g, 20 m) was ad-
ded to a warm ethanolic solution (25 mL) of 4-amino-1,2,4-triazole
(1.69 g, 20 m) and the resulting solution was refluxed for four
hours. The reaction mixture was then cooled to room temperature.
The solution was evaporated to dryness under reduced pressure,
and the crude product was recrystallised from ethanol/diethyl ether.
The resultant white solid was filtered off, washed with diethyl ether
and dried under vacuum. Yield 2.55 g, 74%; M.p. 144 °C (subl.).
C9H8N4 (172.2): calcd. C 62.78, H 4.68, N 32.54; found C 62.71,
H 4.66, N 32.54. MS: m/z ϭ 173 [MH]ϩ. 1H NMR (500 MHz,
CD3CN, 298 K): δ ϭ 8.84 (s, 1 H, NϭCH) 8.74 (s, 2 H, triazole)
7.92 (m, 2 H, ortho) 7.64 (m, 1 H, para) 7.59 (m, 2 H, meta) ppm.
{[Cu2(ClPhtrz)4](ClO4)2}·2CH3CN (1): A solution of [Cu(CH3CN)4]-
(ClO4) (164 mg, 0.5 mmol) in acetonitrile (5 mL) was added drop-
wise to an acetonitrile solution (15 mL) of ClPhtrz (207 mg,
1 mmol). The colourless solution was stirred for 15 min, then the
volume of the solution was reduced by half over 4 hours in a stream
of N2. The resultant solution was allowed to stand overnight at
room temperature, affording colourless, needle-shaped crystals of 1
which were collected by filtration, washed with acetonitrile and di-
ethyl ether. The crystal used in the X-ray structure determination
was selected from this sample. The molecular formula for 1 was
established on the basis of X-ray crystallographic measurement (see
Table 1). Elemental analysis data: vide infra.
1
Figure 6. H NMR spectra (500 MHz, CD3CN, 233 K) of a satu-
rated solution of 5 (A), mixtures of 5 and Phtrz (B and C) and
Phtrz (D); assignments: NϭCH Ϫ azomethine proton, trz Ϫ
triazole protons, o, m, p Ϫ ortho, meta, para protons of phenyl
substituent
{[Cu2(ClPhtrz)4(CH3CN)2](ClO4)2}·CH3CN (2). Method A: The
compound was obtained as described for 1, but no reduction of
solvent volume was done. The colourless solution was allowed to
stand at room temperature for about one month. During this time
light-yellow, prismatic crystals of 2 were formed.
Method B: The compound was obtained as described in method A,
but ClPhtrz (104 mg, 0.5 mmol) and [Cu(CH3CN)4](ClO4)
(164 mg, 0.5 mmol) were used. After standing overnight at room
temp. light-yellow, prismatic crystals were formed. The measured
lattice parameters for the crystals obtained by method B were ident-
ical to those detected for 2 obtained by method A. The molecular
formula for 2 was established on the basis of X-ray crystallographic
measurement (see Table 1). Elemental analysis data: vide infra.
1 and 2) and/or type of ligand used (3), as confirmed by
single-crystal X-ray diffraction. Our studies show that
Schiff-base-containing triazole ligands coordinate simul-
taneously in the monodentate and bidentate mode. The lat-
ter results in them bridging two metal centres. This is in
contrast with pyrazolylcopper() complexes, in which a
pyrazole molecule acts solely as a bridging ligand. All stud-
ied crystals are unstable and lose acetonitrile molecules (co-
ordinated and solvated) forming 4 (from 1 and 2) and 5
(from 3). Regardless of the stoichiometry, the complexes
dissociate rapidly to form monomeric species upon dissol-
ution, unlike the pyrazole-bridged dimers, which retain
their dimeric structure in solution.
{[Cu2(Phtrz)6](ClO4)2}·2CH3CN (3): A solution of [Cu(CH3CN)4]-
(ClO4) (164 mg, 0.5 mmol) in acetonitrile (10 mL) was added to
an acetonitrile solution (10 mL) of Phtrz (172 mg, 1 mmol). The
resultant light-yellow solution was stirred for 15 min, then about
4 mL of solvent was removed under a stream of dinitrogen. After
4 hours light-yellow crystals of 3 had formed. The crystals were
filtered off, washed with acetonitrile and diethyl ether. The molecu-
lar formula for 3 was established on the basis of X-ray crystallo-
graphic measurement (see Table 1). Elemental analysis data: vide
infra.
Experimental Section
General Remarks: ESI MS were performed on a Finnigan Mat type
1
TSQ700 mass spectrometer. H NMR spectra were recorded on a
Bruker AM500 spectrometer in CD3CN. UV spectra were recorded
on a Hewlett Packard 8453 diode array spectrophotometer. El-
emental analyses were carried out at the Microanalytical Labora-
tory of this University.
During the storage of the complexes even in a sealed vial under a
dinitrogen atmosphere cracking of the crystals of 1 and 3 was de-
tected, whereas crystals of 2 undergo complete powdering and be-
come white. The analysis of the resulting products 4 and 5 indicated
Starting Materials: Commercially available solvents, hydrazine
monohydrate, formic acid, 4-chlorobenzaldehyde and benzaldehyde
(Fluka) were used without further purification. [Cu(CH3CN)4]- the loss of acetonitrile molecules, either independently solvated (1
(ClO4),[27] 4-amino-1,2,4-triazole,[28] and N-[(E)-(4-chlorophenyl)- and 3) or coordinated (2).[30] For 4: C36H28N16Cl6Cu2O8 (1152.5):
1552
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554

Dimeric CuI Complexes with Schiff-Base-Containing Triazole Ligands
Table 1. Crystal data and structure refinement
FULL PAPER
Compound
1
2
3
Empirical formula
Molecular weight
T (K)
C36H28N16O8Cl6Cu2·2H3CCN
C40H34N18O8Cl6Cu2·H3CCN
1275.68
100(2)
C54H48N24O8Cl2Cu2·2H3CCN
1441.25
100(2)
1234.63
100(2)
0.71073
Monoclinic
P21/c
7.0205(8)
17.9760(14)
22.0379(17)
90
96.995(8)
90
2760.5(4)
2
1.485
1.125
1248
˚
λ (A)
0.71073
Triclinic
0.71073
Triclinic
Crystal system
Space group
¯
¯
P1
P1
˚
a (A)
9.3882(12)
11.0484(17)
13.5942(19)
76.384(13)
71.686(12)
84.439(12)
1300.6(3)
1
11.1666(10)
12.3458(11)
12.6112(11)
68.604(8)
88.132(7)
80.316(8)
1594.9(2)
1
1.501
0.827
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
3
˚
V (A )
Z
Dc (Mg·mϪ3
)
1.629
1.197
646
µ (mmϪ1
F(000)
)
740
Crystal size (mm)
θ range for data collection (°)
Ranges of h,k,l
0.15 ϫ 0.12 ϫ 0.12
3.17Ϫ28.51
Ϫ9Ǟ6, Ϫ24Ǟ23, Ϫ29Ǟ29
18818
6492 (0.0406)
6492/320
0.17 ϫ 0.15 ϫ 0.13
3.35Ϫ28.36
Ϫ12Ǟ11, Ϫ14Ǟ8, Ϫ18Ǟ18
9065
5716 (0.0305)
5716/414
1.021
0.52 ϫ 0.35 ϫ 0.33
3.64Ϫ28.37
Ϫ14Ǟ8, Ϫ16Ǟ16, Ϫ16Ǟ16
10983
7019 (0.0200)
7019/562
Reflections collected
Independent reflections
Data/parameters
GOF(F2)
1.099
1.047
Final R1/wR2 indices [I Ͼ 2σ(I)]
Min/max. transmission factor
Extinction coefficient
0.0579/0.1526
---
---
0.0456/0.1077
---
---
0.0346/0.0812
0.6731/0.7720
0.0021(5)
Ϫ3
˚
Largest diff. peak/hole (e·A
)
1.162/Ϫ0.462
1.416/Ϫ0.983
0.448/Ϫ0.500
calcd. C 37.52, H 2.45, N 19.44; (obtained from 1) C 37.74, H were included from the geometry of the molecules and ∆ρ maps.
2.45, N 19.39; (obtained from 2) C 37.38, H 2.47, N 19.43. For 5:
During refinement their parameters were fixed.
C54H48Cl2Cu2N24O8 (1359.1): calcd. C47.72, H 3.56, N 24.73;
CCDC-198765Ϫ198767 (1Ϫ3) contain the supplementary crystal-
found C47.63, H 3.66, N 24.41. The elemental analytical data for lographic data for this paper. These data can be obtained free of
1 and 2 were analogous to that obtained for 4, while elemental
analysis showed that dried 3 and 5 were the same species.
charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK; fax: (internat.) ϩ44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
X-ray Crystallographic Study: Crystal data of 1؊3 are given in
Table 1, together with refinement details. All measurements of crys-
tals were performed at low temperature using an Oxford Cryosys-
tem device on a Kuma KM4CCD κ-axis diffractometer with graph-
ite-monochromated Mo-Kα radiation. The crystals were positioned
65 mm from the CCD camera. 612 frames were measured at 0.75°
intervals with a counting time in the range 10Ϫ20 sec. Accurate
cell parameters were determined and refined by least-squares fit of
1900 to 3100 of the strongest reflections. Data reduction and analy-
sis were carried out with the Oxford Diffraction (Poland) (formerly
Kuma Diffraction Wrocław, Poland) programs. The data were cor-
rected for Lorentz and polarisation effects. An analytical absorp-
tion correction was also applied for 3. Data reduction and analysis
were carried out with the Oxford Diffraction (Poland) Sp. z o. o.
(formerly Kuma Diffraction Wrocław, Poland) programs. The
Acknowledgments
The Authors thank the MENiS for financial support.
[1]
P. J. Steel, Coord. Chem. Rev. 1990, 106, 227Ϫ265.
[2]
J. G. Haasnoot, Coord. Chem. Rev. 2000, 200Ϫ202, 131Ϫ185.
[3]
S. Trofimenko, Prog. Inorg. Chem. 1986, 34, 115Ϫ210.
[4]
G. La Monica, G. A. Ardizzoia, Prog. Inorg. Chem. 1997, 46,
151Ϫ238.
[5]
G. A. Ardizzoia, S. Cenini, G. La Monica, N. Masciocchi, M.
Moret, Inorg. Chem. 1994, 33, 1458Ϫ1463.
G. A. Ardizzoia, S. Cenini, G. La Monica, N. Masciocchi, A.
[6]
Maspero, M. Moret, Inorg. Chem. 1998, 37, 4284Ϫ4292.
G. A. Ardizzoia, E. M. Beccalli, G. La Monica, N. Masciocchi,
structures were solved by direct methods (program SHELXS-97[31]
)
[7]
and refined by the full-matrix least-squares method on all F2 data
using the SHELXL-97[32] programs. In the studied crystals the
acetonitrile solvent molecules are disordered, with occupancy par-
ameters of 0.25 in 1, and 0.5 in 2, whereas in 3 one molecule has
M. Moret, Inorg. Chem. 1992, 31, 2706Ϫ2711.
N. Masciocchi, M. Moret, P. Cairati, A. Sironi, G. A. Ardiz-
[8]
zoia, G. La Monica, J. Am. Chem. Soc. 1994, 116, 7668Ϫ7676.
M. K. Ehlert, S. J. Rettig, A. Storr, R. C. Thompson, J. Trotter,
[9]
Can. J. Chem. 1990, 68, 1444Ϫ1449.
Ϫ
two different orientations in an 0.84:0.16 ratio. The ClO4 ion in
[10]
R. G. Raptis, J. P. Fackler, Jr., Inorg. Chem. 1988, 27,
3 is also slightly disordered, with two distinct orientations approxi-
mately in a 0.93:0.07 ratio. Non-hydrogen atoms were refined with
anisotropic displacement parameters except for the disordered sol-
vent molecules in 1 and 2 and the minor components of the dis-
ordered acetonitrile molecule and perchlorate ion. Hydrogen atoms
4179Ϫ4182.
[11]
M. K. Ehlert, S. J. Rettig, A. Storr, R. C. Thompson, J. Trotter,
Can. J. Chem. 1992, 70, 2161Ϫ2173.
G. A. Ardizzoia, M. A. Angaroni, G. La Monica, N. Mascioc-
[12]
chi, M. Moret, J. Chem. Soc., Dalton Trans. 1990, 2277Ϫ2281.
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554
1553

K. Drabent, Z. Ciunik, P. J. Chmielewski
FULL PAPER
[13]
[22]
[23]
M. G. B. Drew, P. C. Yates, J. Trocha-Grimshaw, K. P. McKil-
lop, S. M. Nelson, J. Chem. Soc., Chem. Commun. 1985,
S. Lopez, S. W. Keller, Inorg. Chem. 1999, 38, 1883Ϫ1888.
C. Maelli, C. S. Arcus, J. L. Wilkinson, T. J. Marks, J. A. Ibers,
J. Am. Chem. Soc. 1976, 98, 711Ϫ718.
T. N. Sorrell, A. S. Borovik, J. Am. Chem. Soc. 1987, 109,
4255Ϫ4260.
262Ϫ263.
[14]
[24]
[25]
[26]
D. J. Chesnut, A. Kusnetzow, R. Birge, J. Zubieta, Inorg. Chem.
1999, 38, 5484Ϫ5494.
J. G. Haasnoot, T. L. F. Favre, W. Hinrichs, J. Reedijk, Angew.
[15]
G. K. Patra, I. Goldberg, J. Chem. Soc., Dalton Trans. 2002,
Chem. Int. Ed. Engl. 1988, 27, 856Ϫ858; Angew. Chem. 1988,
1051Ϫ1057.
100, 884.
A. Ion, M. Buda, J.-C. Moutet, E. Saint-Aman, G. Royal, I.
Gautier-Luneau, M. Bonin, R. Zissel, Eur. J. Inorg. Chem.
2002, 1357Ϫ1366.
[16]
E. Müller, G. Bernardinelli, J. Reedijk, Inorg. Chem. 1996, 35,
1952Ϫ1957.
[17]
[27]
[28]
[29]
[30]
R-X. Yuan, R-G. Xiong, B. F. Abrahams, G-H. Lee, S-M.
G. J. Kubas, Inorg. Synth. 1979, 19, 90Ϫ92.
R. M. Herbst, J. A. Garrison, J. Org. Chem. 1953, 18, 872Ϫ882.
Z. Ciunik, K. Drabent, Polish J. Chem. 2001, 75, 1475Ϫ1482.
Peng, C-M. Che, X-Z. You, J. Chem. Soc., Dalton Trans.
2001, 2071Ϫ2073.
G. Gioia Lobbia, M. Pellei, C. Pettinari, C. Santini, B. W. Skel-
[18]
Ϫ
Because of experimental problems (ClO4 counteranion) a
ton, N. Somers, A. H. White, J. Chem. Soc., Dalton Trans.
2002, 2333Ϫ2340.
thermogravimetric analysis of the 1, 2 and 3 could not be per-
formed.
[19]
[31]
[32]
A. L. Spek, PLATON, Acta Crystallogr., Sect. A 1990, 46, C-
G. M. Sheldrick, SHELXS-97, program for solution of crystal
structures, University of Göttingen, 1997.
G. M. Sheldrick, SHELXL-97, program for crystal structure
refinement, University of Göttingen, 1997.
Received November 29, 2002
34.
[20]
R. R. Gagne, R. P. Kreh, J. A. Dodge, J. Am. Chem. Soc. 1979,
101, 6917.
S. Kitagawa, M. Munakata, T. Tanimura, Inorg. Chem. 1992,
31, 1714Ϫ1717.
[21]
[I02662]
1554
Eur. J. Inorg. Chem. 2003, 1548Ϫ1554