Complexes of trinuclear macrocyclic copper(I) and silver(I) 3,5-bis(trifluoromethyl)pyrazolates with ketones

Article abstract of DOI:10.1002/ejic.201200814

The interaction of the copper [{3,5-(CF₃)₂Pz}Cu] ₃ and silver [{3,5-(CF₃)₂Pz}Ag]₃ macrocycles {3,5-(CF₃)₂Pz = 3,5-bis(trifluoromethyl) pyrazole} with 2-butanone and benzophenone was investigated for the first time by IR and NMR spectroscopy and single-crystal X-ray diffraction. New, low-frequency IR bands for I(CO)^bond (in hexane) were observed and the composition (1:1) of all the complexes was determined. These data as well as the ¹³C NMR chemical shifts (in CD₂Cl₂) for the complexes of aliphatic and aromatic ketones evidence that the oxygen atom of the CO group is the sole coordination site in both complexes and that the Ph rings of benzophenone do not take part in complexation in solution. The thermodynamic parameters for the formation of the complexes increase on going from the copper to silver macrocycle and grow slightly from butanone to benzophenone. The same coordination site (CO group) was found in the crystal structure. However, the complexes with benzophenone are formulated as 1:2 complexes and feature a wedge-shaped sandwich structure, but [AgL]₃ also forms a 1:1 complex with triple coordination of the oxygen atom to each Ag atom. Analysis of the IR spectroscopic data for the complexes in crystal form and in solution revealed that in solution the [Ph₂CO][ML]₃ complexes also have triple coordination of the CO oxygen atom to the metals of both the Cu and Ag macrocycles. The structure of the 1:1 complex features no interaction between the Ph rings and the macrocycle in contrast to sandwiches (1:2) with shortened distances Ag...C (Ph). It was found that the sandwich complexes pack as infinite stacks, whereas the complex with triple coordination (1:1) forms only cofacial dimers. Copyright

Full text of DOI:10.1002/ejic.201200814

Job/Unit: I20814
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Date: 17-09-12 17:02:24
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FULL PAPER
DOI: 10.1002/ejic.201200814
Complexes of Trinuclear Macrocyclic Copper(I) and Silver(I) 3,5-
Bis(Trifluoromethyl)Pyrazolates with Ketones
Alexey A. Titov,[a] Oleg. A. Filippov,[a] Alexey N. Bilyachenko,[a] Alexander F. Smol’yakov,[a]
Fedor M. Dolgushin,[a] Vitaly K. Belsky,[b] Ivan A. Godovikov,[a] Lina M. Epstein,[a] and
Elena S. Shubina*[a]
Keywords: Copper / Silver / Macrocyclic ligands / Pi interactions / Metal–metal interactions
The interaction of the copper [{3,5-(CF3)2Pz}Cu]3 and silver
same coordination site (CO group) was found in the crystal
[{3,5-(CF3)2Pz}Ag]3 macrocycles {3,5-(CF3)2Pz = 3,5-bis(tri- structure. However, the complexes with benzophenone are
fluoromethyl)pyrazole} with 2-butanone and benzophenone
was investigated for the first time by IR and NMR spec-
troscopy and single-crystal X-ray diffraction. New, low-fre-
quency IR bands for ν(CO)bond (in hexane) were observed
and the composition (1:1) of all the complexes was deter-
mined. These data as well as the 13C NMR chemical shifts (in
CD2Cl2) for the complexes of aliphatic and aromatic ketones
evidence that the oxygen atom of the CO group is the sole
coordination site in both complexes and that the Ph rings of
benzophenone do not take part in complexation in solution.
The thermodynamic parameters for the formation of the com-
plexes increase on going from the copper to silver macro-
cycle and grow slightly from butanone to benzophenone. The
formulated as 1:2 complexes and feature a wedge-shaped
sandwich structure, but [AgL]3 also forms a 1:1 complex with
triple coordination of the oxygen atom to each Ag atom.
Analysis of the IR spectroscopic data for the complexes in
crystal form and in solution revealed that in solution the
[Ph2CO][ML]3 complexes also have triple coordination of the
CO oxygen atom to the metals of both the Cu and Ag macro-
cycles. The structure of the 1:1 complex features no interac-
tion between the Ph rings and the macrocycle in contrast to
sandwiches (1:2) with shortened distances Ag···C (Ph). It was
found that the sandwich complexes pack as infinite stacks,
whereas the complex with triple coordination (1:1) forms only
cofacial dimers.
These pyrazolates also reveal interesting π-acid/base prop-
erties that are highly dependent on the substituents of the
pyrazole ring and on the metal atom.[7] For example, [{3,5-
(CF3)2Pz}Au]3 is a π-acid, whereas [{3,5-(CH3)2Pz}Au]3 is
a π-base.[8] Polymer complexes based on copper trimeric
pyrazolates with halide/pseudohalide interactions were de-
scribed in 2011.[9] The ability of trinuclear metal pyrazolates
to form interesting complexes with organic arenes as bases
was shown.[8] Recently, we reported the first example of the
interaction between copper and silver [ML]3 compounds
Introduction
The cyclic trinuclear fluoro-substituted pyrazolates of
group 11 metals (Cu, Ag, Au) have been under active inves-
tigation in recent years as compounds that possess signifi-
cant luminescent and π-acidic properties.[1] The complexes
of [{3,5-(CF3)2Pz}Cu]3 ([CuL]3) and [{3,5-(CF3)2Pz}Ag]3
([AgL]3) {L
= [3,5-(CF3)2Pz] [3,5-bis(trifluoromethyl)-
pyrazolate]} were synthesized[2] and their properties were
actively investigated recently.[1a,2,3] It was shown that fluo-
ride substituents usually improve the thermal properties
and oxidative stability of such compounds.[4] These metal
complexes and their structural analogues display significant
luminescent properties.[5] The emission colors of solid sam-
ples and frozen solutions of the trimeric complexes (e.g.,
[CuL]3) demonstrate significant sensitivities to temperature,
solvent, concentration, and excitation wavelengths.[1a,6]
2–
2–
with B10H10 and B12H12 anions in solution.[10] Examin-
ing the complexes of [ML]3 (M = Cu, Ag) and iron carbonyl
compounds with aromatic ligands (cyclooctatetraene), we
determined the sole site of coordination: the π-electron sys-
tem of the iron complex. There is no interaction of the
macrocycles with the metal carbonyl group of this (cot)-
Fe(CO)3 compound, nor was any complexation with
Fe(CO)5 found.[11] Thus, the question arises whether carb-
onyl groups of organic compounds could take part in coor-
dination with these macrocycles. This paper presents the
first study on the formation of complexes of copper(I) and
silver(I) trinuclear pyrazolates with two organic ketones –
2-butanone [MeC(O)Et] as an example of an aliphatic
ketone and benzophenone (Ph2CO) as a representative of
the aromatic series – in solution (hexane, CH2Cl2) through
[a] A. N. Nesmeyanov Institute of Organoelement Compounds,
Russian Academy of Sciences,
Vavilov st. 28, 119991 Moscow, Russia
Fax: +7-495-1355085
E-mail: shu@ineos.ac.ru
Homepage: http://www.ineos.ac.ru/en/119-lmh.html
[b] L.Ya. Karpov Institute of Physical Chemistry,
Vorontsovo Pole St. 10, 103064, Moscow, Russia
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200814.
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the combination of IR and NMR spectroscopy and in the
solid state by single-crystal X-ray diffraction.
Results and Discussion
We studied the interaction of copper(I) and silver(I) tri-
nuclear metallocycles of 3,5-bis(trifluoromethyl)pyrazolate
with 2-butanone and benzophenone in solvents of low-po-
larity (CH2Cl2, hexane) and in solid state. An aliphatic
ketone such as 2-butanone possesses a single site of coordi-
nation, the CO group, but an aromatic ketone possesses a
second potential coordination site, that is, the π-electron
system of the phenyl ring.
Figure 2. IR spectra in the ν(CO) range of benzophenone (0.005 m,
solid line) and in the presence of [AgL]3 with c = 0.0005 m (dash
line), c = 0.0025 m (dotted line), c = 0.005 m (dash-dotted line), c
= 0.01 m in hexane, T = 290 K, d = 0.22 cm.
IR Spectral Characteristics
Study of the IR spectra in the CO stretching vibrations
range [ν(CO)] is very efficient as a result of the high inten-
sities of the ν(CO) bands and their sensitivity to intermo-
lecular interactions. The ν(CO) band in the IR spectrum of
2-butanone (1) and benzophenone (2) was observed at 1727
and 1670 cm–1, respectively (in hexane). Addition of
[AgL]3 or [CuL]3 to a solution of 1 or 2 was accompanied
by a decrease in the intensity of the initial ν(CO)init band
similar for both macrocycles and only slightly larger for the
interaction with benzophenone than with the aliphatic
ketone.
Table 1. Position of the ν(CO) bands of free ketones, ν(CO)init, and
in their complexes with [AgL]3. or [CuL]3, ν(CO)bond, in hexane at
290 K.
Ketone ν(CO)init [cm–1]
ν(CO)bond (Δν[a]) [cm–1]
R1C(O)R2/[AgL]3 R1C(O)R2/[CuL]
and the appearance of
a new low-frequency band
ν(CO)bond as illustrated in Figures 1 and 2. Further ad-
dition of the [AgL]3 or [CuL]3 macrocycle to the solution
of the ketone led to a decrease in the intensity of the initial
ν(CO)init band and an increase in the intensity of the new
ν(CO)bond band.
1
2
1727
1670
1695 (–32)
1634 (–36)
1694 (–33)
1632 (–38)
[a] Band shift Δν = ν(CO)bond – ν(CO)init
.
The equilibrium for the formation of the complex is
shifted to the right at low temperatures for each pair (Fig-
ures 3 and 4). The formation of the complex is reversible:
the intensity of the free ν(CO) bands decrease at low tem-
peratures and then increase again with an increase in the
temperature.
Figure 1. IR spectra in the ν(CO) range of 2-butanone (0.01 m, so-
lid line) and in the presence of [CuL]3 with c = 0.005 m (dash line),
c = 0.01 m (dotted line), c = 0.02 m (dash-dotted line) in hexane, T
= 290 K, d = 0.12 cm.
As is known, coordination of Brønsted acids to CO
groups entails the appearance of new, low-frequency bands
of bonded CO group in the ν(CO) range.[12] Therefore, the
appearance of low-frequency bands indicates that the CO
groups of both ketones take part in the formation of the
complex with macrocyclic Lewis acids. The position of the
ν(CO) band of the initial uncoordinated carbonyl group
and that of the carbonyl group coordinated to [ML]3, as
well as low-frequency shifts (Δν), are presented in Table 1.
Figure 3. IR spectra of 2-butanone (0.01 m, 230 K, solid line) in
the ν(CO) range and in the presence of [CuL]3 (0.01 m) in hexane
at different temperatures: 270 K (dash line), 250 K (dotted line),
230 K (dash-dotted line), d = 0.12 cm.
NMR Spectroscopic Study
1
The variable-temperature H NMR and 13C NMR spec-
The Δν values are in the range from 32 to 38 cm–1 and are tra of a R1C(O)R2/[AgL]3 mixture in CD2Cl2 were mea-
2
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Complexes of Macrocyclic CuI and AgI 3,5-Bis(Trifluoromethyl)Pyrazolates
Figure 4. IR spectra of benzophenone (0.005 m, 230 K, solid line)
in the ν(CO) range and in the presence of [AgL]3 (0.005 m) in hex-
ane at different temperatures: 270 K (dash line), 250 K (dotted
Figure 5. Job’s plot: dependence of the intensity of the ν(CO)bond
band of {1·[ML]3} (1694 cm–1) on the composition of the isomolar
solution of 1 and [AgL]3 {c(1) + c = 0.005 m}.
line), 230 K (dash-dotted line), d = 0.12 cm.
([ML]3)
sured to confirm that the CO group is the site of coordina-
tion. In the 13C NMR spectrum, the peak for the carbon
atom of the CO group in 1 and 2 undergoes a low-field shift
by 0.25–0.36 ppm upon addition of an equimolar amount
of the macrocycle at room temperature; the value of this
shift increases to 0.67–0.76 ppm upon cooling to 213 K.
The shifts are larger at low temperatures due to higher for-
mation constants at 213 K than at 293 K. At the same time,
small shifts of other peaks in the 13C NMR spectrum are
observed (Δδ Յ 0.15 ppm, 213 K; Table 2).
Table 2. 13C NMR chemical shifts of the (CO) signals in 1 and 2:
δ(CO)init and in the presence of [AgL]3, δ(CO)bond, as well as the
shifts, Δδ[a], in parentheses, in ppm.
Figure 6. Saturation plot: dependence of the intensity of the
Ketone
297 K
213 K
ν(CO)init band of 2 (1670 cm–1) on the amount of [AgL]3.
δ(CO)init δ(CO)bond (Δδ) δ(CO)init δ(CO)bond (Δδ)
1
2
209.62
196.37
209.87 (+0.25)
196.73 (+0.36)
210.27
196.88
211.03 (+0.76)
197.55 (+0.67)
Quantitative analysis of the IR spectra allowed the
thermodynamic parameters to be calculated. The enthalpy
and entropy values were obtained from the temperature de-
pendence of the formation constants [Equation (1),
Table 3].
[a] Δδ = δ(CO)bond – δ(CO)init
.
The resonance of the Ph2CO protons in the presence of
an equimolar amount of [AgL]3 undergoes a small highfield
shift (Δδ Յ 0.10 ppm at 213 K; Δδ Յ 0.04 ppm at 293 K);
upon formation of the complex, the resonance of the
MeC(O)Et protons at 213 K underwent a negligible low-
field shift Ͻ0.02 ppm. Thus, the results of IR and NMR
spectroscopic analysis indicate that the oxygen atom of the
CO group is the sole coordination site for the complexes of
both aromatic and aliphatic ketones with the macrocycles.
(1)
Table 3. The thermodynamic parameters of the complexes
{1·[AgL]3}, {1·[CuL]3}, {2·[AgL]3}, and {2·[CuL]3} in hexane.
Complex
ΔH° [kcalmol–1]
ΔS° [calmol–1 K–1]
Composition and Thermodynamic Characteristics of the
Complexes in Solution
{1·[AgL]3}
{1·[CuL]3}
{2·[AgL]3}
{2·[CuL]3}
–5.8Ϯ0.2
–4.7Ϯ0.2
–5.2Ϯ0.1
–4.7Ϯ0.1
–11Ϯ1
–10Ϯ1
–7.7Ϯ0.2
–6.4Ϯ0.3
The composition of the complexes was determined by
saturation and continuous variation (Job’s) methods by an-
alyzing the IR spectra in the ν(CO) range (Figures 5 and
The thermodynamic characteristics indicate that the in-
6).[17] It was shown that complexes of only one type are teraction of [AgL3] with ketones is energetically more pref-
formed in solution. Formation of the complexes containing erable than that of the copper macrocycle. This is in con-
one molecule of the ketone per one molecule of the macro- trast to complexes of the macrocycles with a π-electron sys-
cycle occurs at R1C(O)R2/[ML]3 molar ratios from 10:1 to tem and polyhedral boron hydride anions.[11] Moreover, the
1:7. So they can be formulated as {[R1C(O)R2]·[ML]3}.
benzophenone complex (ΔH° = –5.8 kcalmol–1) with AgL3
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as a Lewis acid is slightly stronger than that with an alkyl cycle are also observed. The dihedral angle between the pla-
ketone (ΔH° = –5.2 kcalmol–1), in correlation with the ba- nes of the phenyl substituent C(17)C(18)C(19)C(20)C(21)-
sicity of the ketones in hydrogen bonding with Brønsted C(22) and the N(5)N(6)C(7)C(8)C(9) cycle of the pyrazol-
acids (Ej = 0.95 and 0.83 for 2 and 1, respectively).[13]
ate ligand is 3.4°, the distance from the pyrazole plane to
the center of the phenyl fragment is 3.27 Å. The shortest
interatomic distances are shown in Table 4. There are no
shortened contacts between neighboring sandwich com-
plexes, and all intermolecular distances corresponds to the
normal van der Waals contacts [the shortest distance is
Cu(1)···Cu(3)1.5–x, 0.5–y, 1–z 4.388(1) Å].
X-ray Study
Complexes between the macrocycles ([AgL]3 and
[CuL]3) and benzophenone can form crystals of different
compositions and structures. In case of the interaction of
copper pyrazolate with benzophenone, only one type of
complex is observed in the solid state. According to the sin-
gle-crystal X-ray diffraction data, the composition of the
complex is 1:2 (Figure 7). The complex contains two mole-
cules of macrocycle per one molecule of ketone; it can be
formulated as [(Ph2CO)·{(CuL)3}2] (3). Complex 3 has a
wedge-shaped sandwich structure [dihedral angle between
the Cu(1)Cu(2)Cu(3) and Cu(1A)Cu(2A)Cu(3A) planes is
39.0°] formed by coordination of the oxygen atom of the
CO group to only one copper atom in both macrocycles
[Cu···O 2.879(4) Å].[14] Complex 3 in the crystal occupies a
special position on the twofold axis passing through the
C(16)–O(1) bond. Coordination of the oxygen atom to cop-
per does not lead to visible lengthening of the C(16)–O(1)
bond [1.221(6) Å], as compared to non-coordinated benzo-
phenone (1.222 Å).[15] The range of intratrimeric Cu···Cu
distances is 3.183(1)–3.238(1) Å. Along with Cu···O, short-
ened contacts are found for the copper atom and the phenyl
substituents of benzophenone in the sandwich complex
(Cu···π interaction, Table 4). Stacking interactions between
the aromatic fragments of benzophenone and the macro-
Table 4. Selected bond lengths [Å] in the {[Ph2CO]·[(ML)3]2} com-
plexes.
3
4
Cu(2)···O(1)
2.879(4)
Cu(2A)···O(1) 2.879(4)
Ag(1)···O(1)
Ag(5)···O(1)
Ag(2)···C(37)
Ag(3)···C(33)
Ag(4)···C(39)
Ag(6)···C(41)
N(12)···C(40)
N(10)···C(42)
N(11)···C(40)
N(4)···C(35)
N(4)···C(34)
N(9)···C(43)
C(1)···C(43)
C(6)···C(35)
C(21)···C(42)
2.908(5)
3.524(5)
3.229(6)
3.245(6)
3.420(6)
3.325(7)
3.297(8)
3.305(8)
3.309(8)
3.360(9)
3.404(8)
3.456(8)
3.374(8)
3.419(9)
3.490(9)
Cu(1)···C(17)
Cu(1)···C(22)
Cu(3)···C(18)
Cu(3)···C(19)
N(5)···C(19)
N(5)···C(20)
N(6)···C(21)
N(6)···C(22)
C(7)···C(20)
C(9)···C(21)
3.480(2)
3.289(2)
3.195(2)
3.359(3)
3.546(3)
3.388(3)
3.315(3)
3.380(3)
3.476(3)
3.491(3)
According to the single-crystal X-ray diffraction data,
benzophenone forms two types of complexes with [AgL]3,
which is in contrast to the single type of complex described
above for the interaction of benzophenone with [CuL3] in
complex 3 (Figure 7). The first one ({[Ph2CO]·[(AgL)3]2},
4) has a 1:2 composition. It also has the wedge-shaped
sandwich structure containing two molecules of the macro-
cycle per one molecule of benzophenone (Figure 8), but it
differs notably in its structure and crystal packing in com-
parison to the copper analogue. Complex 4 stands in a ge-
neral position in the crystal but the oxygen atom of benzo-
phenone is coordinated to only one silver atom in one
macrocycle Ag(1)···O(1) 2.908(5) Å (Figure 8). The shortest
contact of the oxygen atom to the silver atom in the second
macrocycle is 3.524(5) Å [Ag(5)···O(1)] and cannot be con-
sidered a contact. The dihedral angle between the Ag(1)-
Ag(2)Ag(3) and Ag(4)Ag(5)Ag(6) planes is 36.6°, which is
slightly less than that in 3, and the range of intratrimeric
distances Ag···Ag is 3.352(1)–3.544(1) Å. There are also
shortened contacts between the phenyl groups of benzophe-
none and both macrocycles, as in sandwich complex 3
(Ag···π and π···π interactions, Table 4).
The second type of complex ({[Ph2CO]·[(AgL)3]}, 5) has
a 1:1 composition (Figure 9) containing one molecule of
ketone per one molecule of macrocycle, as in solution. The
coordination of benzophenone with the macrocycle in 5 is
completely different from that observed in 3 and 4. The
oxygen atom is coordinated to all silver atoms in the macro-
cycle [Ag···O 2.768(3)–2.952(4) Å, Figure 9]. The Ag···Ag
distances in the macrocycle are in the 3.402(1)–3.437(1) Å
Figure 7. Molecular structure of the complex {[Ph2CO]·[(CuL)3]2}
(3); thermal ellipsoids are drawn at the 30% probability level. Hy-
drogen atoms are omitted for clarity.
4
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Complexes of Macrocyclic CuI and AgI 3,5-Bis(Trifluoromethyl)Pyrazolates
Ag(2)–Ag(1A)1–x, 1–y, –z 3.6886(6) Å; Figure 10]. In the case
of free [AgL]3, dimers are also formed through shortened
Ag···Ag contacts, but they are significantly shorter
(3.204 Å) than in complex 5. This correlates with an in-
crease in the Ag···Ag contact lengths due to the existence of
stronger Ag···O bonds. Note that the packing of sandwich
complex 4 is formed by shortened Ag···C{Ph} and
Ag···C{Pz} contacts as well as by shortened Ag···Ag
[Ag(3)···Ag(6) 3.295(2) Å, Ag(1)···Ag(4) 3.457(1) Å,
Ag(2)···Ag(5) 3.648(1) Å] and Ag···N [Ag(4)···N(6)
3.115(6), Ag(5)···N(3) 3.218(5) Å] contacts, which generate
infinite stacks (Figure 11).
Figure 8. Molecular structure of the complex {[Ph2CO]·[(AgL)3]2}
(4); thermal ellipsoids are drawn at the 30% probability level. Hy-
drogen atoms are omitted for clarity.
range. The dihedral angle between the plane of the ketone
[C(16)O(1)C(17)C(23)] and that of the macrocycle [Ag(1)-
Ag(2)Ag(3)] is 69.7°. Notably, the phenyl substituents of
benzophenone do not take part in coordination to the
macrocycle. It should be noted that multicenter coordina-
tion of the CO group in carbonyl compounds is typical for
complexes of mercury-containing macrocycles (HgC6F4)3
with various organic molecules such as ethyl acetate, di-
methylacetamide, dimethylformamide, acetone, and benzo-
phenone.[16]
Figure 10. Cofacial dimer in the crystal of 5. Hydrogen atoms are
omitted for clarity.
Figure 9. Molecular structure of 1:1 complex 5 in the crystal; ther-
mal ellipsoids are drawn at the 30% probability level. Hydrogen
atoms are omitted for clarity.
Complex 5 forms dimers in the crystal through shortened
Figure 11. The infinite stacks in the crystal structure of 4. Hydro-
Ag···Ag contacts [Ag(1)···Ag(1A)1–x,
3.4336(7) Å, gen atoms are omitted for clarity.
1–y, –z
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The IR spectra of 4 and 5 in the solid state (Figure 12) ferior site of coordination in comparison with the C–CO
show only bonded low-frequency ν(CO) bands (1641 and group, cannot win in the competition with the π-aromatic
1630 cm–1, respectively). This demonstrates the interaction system. The [ML]3 complex with the CO group of benzo-
of the carbonyl group of benzophenone with the macro- phenone as a single site of coordination in solution is the
cycle, which is in agreement with the X-ray data and the first case of successful competition between the π-system
spectral changes in solution. Moreover, the cooperative tri- and any other site.
ple coordination in 5 results in a larger ν(CO)bond shift in
The composition of the complexes in the solid state and
comparison to that observed for complex 4, which features the types of their packing are very interesting and diverse.
single coordination. Notably, the ν(CO)bond position for The single-crystal X-ray diffraction data show the wedge-
complex 5 is closer to that in solution for 4. Partial dissoci- shaped sandwich structures of 2:1 composition formed
ation is observed when both complexes are dissolved in hex- through CO···M coordination, and additional shortened
ane, leading to the appearance of the ν(CO)init bands of contacts with the Ph rings are common for complexes with
benzophenone; at that point the intensity ratio between free Cu and Ag macrocycles. The [AgL]3·[Ph2CO] complex of
and bonded bands for 5 is in accord with the formation the second type has 1:1 composition (as in solution), and
constant values.
triple coordination of the carbonyl oxygen atom to each Ag
atom although [AgL3] interactions with the Ph rings is ab-
sent. The IR spectral behavior of the latter complex in the
crystalline solid state and upon dissolving in solution al-
lowed us to suggest that only one structure is common for
all complexes studied in solution. The driving force of com-
plexation is multicentral interactions between the oxygen
atom of the CO group in ketones and the Lewis centers in
the macrocycles. Supramolecular packing arises due to
M···π or M···M interactions.
Experimental Section
General Methods: The [{3,5-(CF3)2Pz}Ag]3 and [{3,5-(CF3)2Pz}Cu]3
macrocycles were synthesized according to published procedures.[2]
The solvents, CH2Cl2 and hexane, were dried prior to use by heat-
ing at reflux with CaH2, followed by distillation under an argon
atmosphere.
Figure 12. IR spectra of benzophenone (solid line), [AgL]3 (dotted
line), complex 4 (dashed line), and complex 5 (dash-dotted line) in
the solid state, KBr pellet.
Thus, among the various structures revealed by single-
crystal X-ray analysis, the 1:1 complex [AgL3]·[Ph2CO] fea-
turing multicenter coordination of the CO group with all
Ag atoms was found in solution.
IR Spectroscopy: IR spectra of CH2Cl2 and hexane solutions were
measured with a Nicolet 6700 FTIR spectrometer in CaF2 cells (d
= 0.4–0.04 cm) by using a home-modified cryostat (Carl Zeiss Jena)
for variable-temperature measurements. The accuracy of the tem-
perature adjustment was Ϯ1 K. IR studies in the ν(CO) region
(1730–1630 cm–1) were carried out at various concentrations (10–4–
10–2 m) and ratios of the reagents. The composition of the com-
plexes in solution was determined by the saturation and the con-
tinuous variation (Job) methods.[17] The ν(CN) bands of the pyra-
Conclusions
In interaction with Lewis acids, ketones possess different
sites of coordination: the carbonyl group is the only pos-
sible site of coordination in the case of aliphatic ketones,
zolate heterocycle appear at 1642 cm–1 for [CuL]3 and at 1632 cm–1
[18]
but aromatic ketones have a second coordination site, that for [AgL]3
overlapping with the ν(CO)bond band of the com-
is, the phenyl ring. The new, low-frequency ν(CO)bond
bands in the complexes with 2-butanone and benzophe-
none, the close values of Δν(CO) in their IR spectra, and
the similar shifts that are observed in the 13C NMR spectra
for these ketones in the presence of the macrocycles, as well
as the common composition (1:1) indicate that the CO
group is the only coordination site in solution. A possible
cause for the lack of interaction with the aromatic system
of benzophenone is the decrease of the π-electron density
on the Ph groups as a result of the strong electron-with-
drawing effects of the CO substituent. This coordination
pattern is different from that observed previously by us for
the complexes between these macrocycles and (cyclooctate-
traene)iron tricarbonyl where the aromatic system is a single
plexes of Ph2CO with [ML]3. The values of the molar extinction
coefficients in hexane {Ph2CO ε(CO) = 730 l/(molcm); [AgL]3
ε(CN) = 43 l/(molcm); [CuL]3 ε(CN) = 44 l/(molcm)} mean that
the impact of the ν(CN) bands is significant only in the presence
of a large excess of the macrocycle. The intensity and position of
the ν(CN) bands of the macrocycles do not significantly change
upon complexation (Supporting Information, Figure S22). Thus, at
every given [ML]3 concentration, the intensity of the ν(CN) band
of the free macrocycle at this concentration was subtracted from
the spectra of the complex when the Job’s method was used.
NMR: Room- and low-temperature NMR measurements were car-
ried out with a Bruker Avance 600 spectrometer operating at
600.22 MHz (1H) and 150.93 MHz (13C{1H}). The temperature
was controlled by using a Bruker BVT-3000 accessory; the accuracy
and stability was Ϯ1 K. The spectra were calibrated with the resid-
site of coordination.[11] Thus, the M–CO group, as the in- ual solvent resonance relative to TMS (1H, 13C).
6
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Complexes of Macrocyclic CuI and AgI 3,5-Bis(Trifluoromethyl)Pyrazolates
Table 5. Crystal data, data collection, and structure refinement parameters for {[Ph2CO]·[(CuL)3]2} (3), {[Ph2(CO)]·[(AgL)3]2} (4),
{[Ph2(CO)]·[(AgL)3]} (5).
3
4
5
Molecular formula
Formula weight
C43H16F36N12OCu6
890.96
C43H16F36N12OAg6
2047.9
C28H13F18N6OAg3
1115.05
Dimension [mm]
Crystal system
Space group
0.18ϫ0.14ϫ0.08
monoclinic
C2/c
0.22ϫ0.16ϫ0.06
monoclinic
P21/n
0.31ϫ0.16ϫ0.03
triclinic
P1
¯
a [Å]
b [Å]
c [Å]
α [°]
13.1119(5)
19.7902(7)
21.7349(8)
90
100.025(1)
90
5553.8(4)
4
2.131
12.771(2)
19.505(3)
22.355(4)
90
91.128(3)
90
5567.5(15)
4
2.443
11.573(2)
13.310(2)
13.436(2)
64.208(2)
82.314(3)
64.517(2)
1678.6(4)
2
2.206
18.69
0.697/0.955
58
β [°]
γ [°]
V [Å3]
Z
ρcalcd. [gcm–3]
Linear absorption (μ) [cm–1]
Tmin/Tmax
24.28
0.709/0.830
58
22.41
0.638/0.877
56
2θmax [°]
No. unique refl. (Rint
)
7302 (0.0333)
5611
443
0.032
0.0685
13444 (0.1042)
8725
883
0.0482
0.1036
8901 (0.0454)
6997
541
0.0418
0.1052
No. observed refl. [IϾ2σ(I)]
No. parameters
R1 (on F for observed refl.)[a]
wR2 (on F2 for all refl.)[b]
GOOF
0.996
0.999
1.065
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = {Σ[w(Fo – Fc ) ]/Σw(Fo ) }1/2
.
2
2 2
2 2
[{Ph2(CO)}({{3,5-(CF3)2Pz}Cu}3)2]: The macrocycle [{3,5-(CF3)2-
Pz}Cu]3 (5 mg, 0.006 mmol) was added to a solution of Ph2CO
(1.1 mg, 0.00625 mmol) in hexane. Slow solvent evaporation at 5 °C
gave colorless crystals. C43H16Cu6F36N12O (1781.88): calcd. C
28.98, H 0.91, N 9.43; found C 28.90, H 0.85, N 9.51.
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supporting Information (see footnote on the first page of this arti-
cle): Copies of the 1H NMR and 13C NMR spectra, van ’t Hoff
plots, IR spectra, and metal–metal distances in complexes 3–5.
[{Ph2(CO)}({{3,5-(CF3)2Pz}Ag}3)2]: The macrocycle [{3,5-(CF3)2-
Pz}Ag]3 (5.6 mg, 0.006 mmol) was added to solution of Ph2(CO)
(1.1 mg, 0.006 mmol) in hexane. Slow solvent evaporation at 5 °C
gave colorless crystals. C43H16Ag6F36N12O (2047.82): calcd. C
Acknowledgments
This work was supported by the Russian Foundation for Basic Re-
search (Project 12-03-00872), Russian Federation President Grant
(Grant MK-874.2011.3), and the Division of Chemistry and Mate-
rial Sciences of Russian Academy of Sciences.
25.22, H 0.79, N 8.21; found C 25.15, H 0.71, N 8.19. IR (KBr): ν
˜
= 3144 (CH [AgL]3), 1641 (CObond), 1595, 1573, 1534, 1503 cm–1.
[{Ph2(CO)}({{3,5-(CF3)2Pz}Ag}3)]: The macrocycle [{3,5-(CF3)2-
Pz}Ag]3 (6.2 mg, 0.0066 mmol) was added to solution of Ph2(CO)
(0.6 mg, 0.0033 mmol) in hexane. Slow solvent evaporation at 5 °C
gave colorless crystals. C43H16Ag6F36N12O (2047.82): calcd. C
[1] a) H. V. R. Dias, H. V. K. Diyabalanage, M. A. Rawashdeh-
Omary, M. A. Franzman, M. A. Omary, J. Am. Chem. Soc.
2003, 125, 12072–12073; b) G. Mezei, C. M. Zaleski, V. L. Pe-
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Inorg. Chem. 2009, 4913–4925.
25.22, H 0.79, N 8.21; found C 25.15, H 0.71, N 8.19. IR (KBr): ν
˜
= 3143 (CH [AgL]3), 1630 (CObond), 1603, 1594, 1575, 1527,
1501 cm–1.
X-ray Studies: Single-crystal X-ray diffraction studies were carried
out with a Bruker SMART APEX II diffractometer (graphite mo-
nochromated Mo-Kα radiation, λ = 0.71073 Å, ω-scan technique,
T = 100 K). The APEX II software was used for collecting frames
of data, indexing reflections, determination of lattice constants, in-
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were solved by direct methods and refined by the full-matrix least-
squares technique against F2 with the anisotropic thermal param-
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metrically and included in the structure factors calculation in the
riding motion approximation. The principal experimental and crys-
tallographic parameters are presented in Table 5.
[2] H. V. R. Dias, S. A. Polach, Z. J. Wang, J. Fluorine Chem. 2000,
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CCDC-891872 (for 3), -891873 (for 4), and -891874 (for 5) contain
the supplementary crystallographic data for this paper. These data
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Eur. J. Inorg. Chem. 0000, 0–0
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Published Online: ᭿
8
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Date: 17-09-12 17:02:24
Pages: 9
Complexes of Macrocyclic CuI and AgI 3,5-Bis(Trifluoromethyl)Pyrazolates
Cu/Ag Macrocyclic Interactions
Copper(I) and silver(I) macrocycles form
strong complexes with the carbonyl groups
of ketones. The oxygen atom of the CO
group is the sole site of coordination in
solution and the main site of coordination
in the solid state for benzophenone com-
plexes.
A. A. Titov, O. A. Filippov,
A. N. Bilyachenko, A. F. Smol’yakov,
F. M. Dolgushin, V. K. Belsky,
I. A. Godovikov, L. M. Epstein,
E. S. Shubina* ................................... 1–9
Complexes of Trinuclear Macrocyclic Cop-
per(I) and Silver(I) 3,5-Bis(Trifluorome-
thyl)Pyrazolates with Ketones
Keywords: Copper / Silver / Macrocyclic
ligands / Pi interactions / Metal–metal
interactions
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