The reaction of μ-η2:η2-peroxo- and bis(μ-oxo)dicopper complexes with flavonol

Article abstract of DOI:10.1002/ejic.200300605

The [Cu₂(μ-O)₂]²⁺ and [Cu ₂(μ-η²:η²-O)₂] ²⁺ motifs with coordinated N,N,N-tribenzyl-1,4,7-triazacyclononane and N,N,N-triisopropyl-1,4,7-triazacyclononane auxiliary li

Full text of DOI:10.1002/ejic.200300605

FULL PAPER
The Reaction of µ-η2:η2-Peroxo- and Bis(µ-oxo)dicopper Complexes
with Flavonol
[a]
[b]
[a]
[c]
´
´
´
´
´ ´ ´
Jozsef Kaizer, Jozsef Pap, Gabor Speier,* and Laszlo Parkanyi
Keywords: Quercetinase / Model compounds / Copper / Oxygen / Flavonol
The [Cu2(µ-O)2]2+ and [Cu2(µ-η2:η2-O)2]2+ motifs with coord- at elevated temperature, resulting in the enzyme mimicking
inated N,N,N-tribenzyl-1,4,7-triazacyclononane and N,N,N-
triisopropyl-1,4,7-triazacyclononane auxiliary ligands in their
reaction with flavonol do not lead to ring scission products
of the heterocycle, but the formation of the corresponding
(flavonolato)copper(II) complexes [Cu(fla)(Bz-TAC)]ClO4 and
[Cu(fla)(iPr-TAC)]ClO4. The subsequent oxygenolysis of the
coordinated flavonolate ligand leads to O-benzoylsalicylate
products [Cu(O-bs)(Bz-TAC)]ClO4, [Cu(O-bs)(iPr-TAC)]-
ClO4) as well as carbon monoxide. The X-ray structures
of [Cu(fla)(Bz-TAC)]ClO4, [Cu(O-bs)(Bz-TAC)]ClO4, and
[Cu(O-bs)(iPr-TAC)]ClO4) are presented.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
Biological oxygenations catalyzed by oxygenases are very
important processes in nature for the metabolism of various
organic substances.[1Ϫ5] To date, four prokaryotic dioxy-
genases are known, which catalyze an oxidative CϪC bond
cleavage with incorporation of two O-atoms into, and re-
lease of CO from the substrates quercetin (1) (flavonol 2,4-
dioxygenase),[6Ϫ13] 3-hydroxy-4-oxo-1H-quinaldine (3) (3-
hydroxy-4-oxo-1H-quinaldine 2,4-dioxygenase), 3-hydroxy-
4-oxo-1H-quinoline (4) (3-hydroxy-4-oxo-1H-quinoline 2,4-
dioxygenase),[14,15] and (S)-1,2-dihydroxy-3-oxo-5-(meth-
ylthio)pentene anion (5) [(S)-1,2-dihydroxy-3-oxo-5-(meth-
ylthio)pentene anion 1,3-dioxygenase].[16,17] Flavonol 2,4-
dioxygenase (‘‘quercetinase’’), which catalyzes the cleavage
of quercetin to carbon monoxide and phenolic carboxylic
acid ester was produced by the species Aspergillus flavus
and Pullularia (Scheme 1).[18]
Scheme 1
Quercetinase has been reported to contain two CuII cen-
ters per molecule.[19,20] Recent diffraction studies on single
crystals of quercetin 2,3-dioxygenase obtained from Asper-
˚
gillus japonicus, at a resolution of 1.8 A, showed that the
enzyme forms homodimers, which are stabilized by an N-
linked heptasaccharide at the dimer interface.[21] Each unit
is mononuclear, with a type 2 copper center displaying two
distinct geometries: a distorted tetrahedral coordination
with three histidine units and one water molecules, and a
distorted trigonal bipyramidal environment with an ad-
ditional carboxylate. Substrate docking studies hinted to
the eventual catalytic importance of the different geo-
metries. In general, the process of oxygenase catalyzed reac-
tions may be divided into three steps in an organic chemical
sense. The first step is the activation of molecular oxygen
and/or a substrate. The second step is the formation of a
reactive intermediate, which would be a peroxidic com-
pound in the case of dioxygenases,[22] and an oxygenated
compound such as an arene oxide in the case of monooxyg-
enases.[2,5,23] The third step involves the transformation of
such an intermediate into the final product. From our ear-
lier results obtained with redox[24Ϫ32] and non-redox[33,35]
metal-containing model systems we concluded, that the
oxygenolysis of the coordinated flavonolate ligand in ap-
rotic solvents takes place mainly via an endoperoxide inter-
mediate resulting in O-benzoylsalicylate as an enzyme-like
[a]
Research Group for Petrochemistry, Hungarian Academy of
Sciences,
´
8201 Veszprem, Hungary
[b]
[c]
´
Department of Organic Chemistry, University of Veszprem,
´
8201 Veszprem, Wartha V. u. 1, Hungary
Fax: (internat.) ϩ 36-88427492
E-mail: speier@almos.vein.hu
Hungarian Academy of Sciences, Institute of Chemistry,
Chemical Research Center,
1525 Budapest, Hungary
Eur. J. Inorg. Chem. 2004, 2253Ϫ2259
DOI: 10.1002/ejic.200300605
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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J. Kaizer, J. Pap, G. Speier, L. Parkanyi
FULL PAPER
product,[36] and to a lesser extent through a 1,2-dioxethane comparisons with previously reported examples, magnetic
intermediate.[37] Apart from these mechanisms, and despite properties, and X-ray crystallography. Tests for the con-
recent suggestions in the literature,[38] the oxygenation of comitant formation of H2O2 did not give convincing results
flavonol to enzyme-like products can also be postulated irrespective of whether there was a selectivity in terms
with the primary formation of copper-dioxygen species as of forming either H2O2 or H2O from the peroxo or oxo
the key reaction step. Earlier studies assumed coordination copper complexes.
of quercetin to the copper() site through its 3-OH and 4-
The IR spectra of the complexes [Cu(fla)(Bz-TAC)]ClO4
CϭO groups.[39Ϫ41] Model studies have reinforced this hy- and [Cu(fla)(iPr-TAC)]ClO4 show principal bands corre-
pothesis, and a fair number of copper complexes of flavon- sponding to coordinated flavonolate at 1545 and 1554
olate ligands have been isolated and structurally cmϪ1, respectively. Decreases of approximately 50 cmϪ1 in
characterized.[24,25,28Ϫ30,42] It has also been postulated, that the ν(CO) bands compared with that of flavonol [ν(CO) ϭ
monodentate coordination of quercetin may be responsible 1602 cmϪ1] are due to chelation and formation of stable
for the substrate activation.[21,38,43] Since we have found in five-membered rings.[48] The charge transfer region in the
our model studies, that the oxygenation of flavonolate coor- electronic spectra of the complexes [Cu(fla)(Bz-TAC)]ClO4
dinated either to copper() or copper() requires higher re- and [Cu(fla)(iPr-TAC)]ClO4 exhibit bands of the coordi-
action temperatures (around 100 °C) it cannot be excluded, nated flavonolate ligand at 432 and 434 nm. Bands at 615
that the first step in the catalytic cycle is the activation of and 653 nm are associated with d-d transitions of the com-
dioxygen. In order to gain experimental support for this plexes.
possibility we have directly evaluated the feasibility of this
The molecular structure together with selected bond
transformation by examining the reaction of flavonol with lengths and angles of [Cu(fla)(Bz-TAC)]ClO4 are shown in
(µ-η2:η2-peroxo)- and bis(µ-oxo)dicopper complexes.[44Ϫ47] Figure 1. The molecule is monomeric in the solid state. The
Herein we report that [Cu2(µ-O)2]2ϩ and [Cu2(µ-η2:η2- copper() center is in a distorted square-pyramidal environ-
O)2]2ϩ cores coordinated to N-trisubstituted triazacyclo- ment as judged by the method of Allison and co-workers
nonanes do not promote the ring cleavage reaction of the (τ ϭ 0.12)[49] with basal planes defined by two nitrogen
heterocycle but react with two equivalents of flavonol yield- atoms derived from the tridentate N,N,N-tribenzyl-1,4,7-
ing (flavonolato)copper() complexes. Subsequent oxygen- triazacyclononane ligand [CuϪN19, 2.040(3); CuϪN22,
˚
ation of the (flavonolato)copper() complexes by dioxygen 2.027(3) A], and two oxygen atoms of the flavonolate
˚
at elevated temperatures results in (O-benzoylsalicylato)c- [CuϪO1, 1.917(3); CuϪO8, 2.012(3) A]. The third nitrogen
opper() complexes and CO.
atom of the N,N,N-tribenzyl-1,4,7-triazacyclononane ligand
˚
[CuϪN25, 2.231(3) A] is in the apical position. The CuϪO8
˚
bond is 0.095 A longer than the CuϪO1 bond. The C2ϪO1
Results and Discussion
distance is shorter while the C7ϪO8 distance is longer than
those in the uncoordinated flavonol [1.357(3) and 1.232(3)
[50]
˚
Addition of two equivalents of flavonol (2; flaH) to a
solution of [{Cu(Bz-TAC)}2(µ-O)2](ClO4)2 or [{Cu(iPr-
TAC)}2(µ-η2:η2-O)2](ClO4)2 in CH2Cl2 at Ϫ80 °C caused
bleaching of their respective optical absorption features
(Bz-TAC ϭ N,N,N-tribenzyl-1,4,7-triazacyclononane, iPr-
TAC ϭ N,N,N-triisopropyl-1,4,7-triazacyclononane). Upon
subsequent warming and workup, the green complexes
[Cu(fla)(Bz-TAC)]ClO4 (9) or [Cu(fla)(iPr-TAC)]ClO4 (10)
(fla ϭ flavonolate) were isolated as crystalline solids in
yields of 95 and 90%, respectively (Scheme 2). The reaction
products were identified on the basis of spectroscopic
A]. Due to coordination to the copper ion there are also
Figure 1. View showing the structure of [Cu(fla)(Bz-TAC)]ClO4 (9);
˚
selected bond lengths (A) and angles (deg): CuϪO1 1.917(3),
CuϪO8 2.012(3), CuϪN22 2.027(3), CuϪN19 2.040(3), CuϪN25
2.231(3), O1ϪC2 1.339(4), O8ϪC7 1.273(4), C2ϪC3, 1.381(5),
C2ϪC7 1.401(5); O1ϪCuϪN22 177.60(12), O8ϪCuϪN19
170.25(12), N19ϪCuϪN25 85.94(12), C2ϪO1ϪCu 111.5(2),
C7ϪO8ϪCu 109.9(2)
Scheme 2
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Reaction of µ-η2:η2-Peroxo- and Bis(µ-oxo)dicopper Complexes with Flavonol
FULL PAPER
changes in the bond lengths of the pyranone ring. The
˚
˚
O4ϪC3 [1.362(4) A] and C5ϪC6 [1.381(5) A] bond lengths
˚
become longer, and the C2ϪC7 bond length [1.401(5) A] is
somewhat shorter, which may be assigned to delocalization
of the π-system over the whole molecule. Similar reactions
of peroxo- and bis(µ-oxo)dicopper complexes bearing the
N,N,N-trisubstituted 1,4,7-triazacyclononane ligands with
catechols resulted in the corresponding copper() semiqui-
none complexes.[51] Since the amine macrocyclic ligands are
hard, and prefer copper(), the copper ion remained in this
oxidation state. It was not specified, however, whether H2O
or H2O2 was formed as the reduction product from O2.
Treatment of the (flavonolato)copper complexes [Cu-
(fla)(Bz-TAC)]ClO4 or [Cu(fla)(iPr-TAC)]ClO4 with dioxy-
gen in DMF solution at elevated temperatures leads to the
corresponding (O-benzoylsalicylato)copper complexes
[Cu(O-bs)(Bz-TAC)]ClO4 (11) and [Cu(O-bs)(iPr-TAC)]-
ClO4 (12) (Scheme 3). The IR spectra of the complexes
[Cu(O-bs)(Bz-TAC)]ClO4 and [Cu(O-bs)(iPr-TAC)]ClO4
show principal bands corresponding to ν(CO) at 1741 and
1747 cmϪ1, respectively. Bands corresponding to ν(CO2) for
the two complexes appear at 1586 and 1432, and 1584 and
1428 cmϪ1, respectively.
Figure 2. View showing the structure of [Cu(O-bs)(Bz-TAC)]ClO4
˚
(11); selected bond lengths (A) and angles (deg): CuϪO1A
1.9772(17), CuϪO2A 2.0685(19), CuϪN1 2.000(2), CuϪN4
2.010(2), CuϪN7 2.182(2) O1AϪC3A, 1.273(3) O2AϪC3A,
1.256(3); O1AϪCuϪN1 171.19(8), O1AϪCuϪO2A 64.87(7),
N4ϪCuϪO2A 161.55(8), N4ϪO1ϪN7 86.94(8)
Scheme 3
The molecular structure together with selected bond
lengths and angles of [Cu(O-bs)(Bz-TAC)]ClO4 are shown
in Figure 2. The copper() center is in a distorted square
pyramidal environment (τ ϭ 0.16)[49] with basal planes de-
fined by two nitrogen atoms derived from the tridentate
N,N,N-tribenzyl-1,4,7-triazacyclononane ligand, and two
oxygen atoms of the bidentate carboxylate group. The api-
Figure 3. View showing the structure of [Cu(O-bs)(iPr-TAC]ClO4
˚
(12); selected bond lengths (A) and angles (deg): Cu1ϪO1 1.981(6),
Cu1ϪO2 2.020(7), Cu1ϪN19 2.020(7), Cu1ϪN22 2.033(6),
Cu1ϪN25 2.208(7), O1ϪC3 1.261(10), O2ϪC3 1.268(10);
O1ϪCu1ϪN22 159.8(3), O1ϪCu1ϪO2 64.8(2), N19ϪCu1ϪO2
165.6(2), N22ϪCu1ϪN25 87.7(3)
cal position is occupied by the other nitrogen atom of the nonane ligand, and two oxygen atoms of the bidentate car-
N,N,N-tribenzyl-1,4,7-triazacyclononane ligand. The boxylate group. The apical position is occupied by the other
copperϪnitrogen bond lengths [CuϪN1 2.000(2), CuϪN4 nitrogen atom of the N,N,N- triisopropyl-1,4,7-triazacyclo-
˚
2.010(2), and CuϪN7 2.182(2) A] are similar to values ob- nonane ligand. A view of the coordination geometry as well
tained for [Cu(fla)(Bz-TAC)]ClO4. The CuϪO bond lengths as selected bond lengths and angles are given in Figure 2.
are shorter than those in [Cu(O-bs)(idpaH)]ClO4 [1.995(5) The copperϪnitrogen bond lengths [Cu1ϪN19 2.020(7),
[30]
˚
˚
and 2.344(6) A].
Cu1ϪN22 2.033(6), Cu1ϪN25,ϭ 2.208(7) A] are similar to
Crystallographic characterization has shown that in values obtained for [Cu(O-bs)(Bz-TAC)]ClO4. The value of
˚
[Cu(O-bs)(iPr-TAC)]ClO4 (12, Figure 3), the copper() ion (Cu1ϪO2) Ϫ (Cu1ϪO1) (0.039 A) is somewhat shorter
has a distorted square pyramidal arrangement (τ ϭ 0.10)[49] than that found in the complex [Cu(O-bs)(Bz-TAC)]ClO4
˚
with basal planes defined by two nitrogen atoms derived (0.0913 A), which may be assigned to the higher degree of
from the tridentate N,N,N-triisopropyl-1,4,7-triazacyclo- delocalization in the carboxylate group.
Eur. J. Inorg. Chem. 2004, 2253Ϫ2259
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FULL PAPER
Oxygenation reactions of [Cu(fla)(Bz-TAC)]ClO4 and in flavonol under mild reaction conditions. Instead, the cor-
[Cu(fla)(iPr-TAC)]ClO4 complexes were followed by UV- responding (flavonolato)copper() complexes are formed.
Vis spectroscopy. Plots of log[Cu(fla)(Bz-TAC)]ClO4 and The latter complexes, however, undergo ring scission in
log[Cu(fla)(iPr-TAC)]ClO4 versus time showed linear de- their reaction with dioxygen under more forcing conditions
pendences under pseudo-first-order conditions (constant resulting in the (O-benzoylsalicylato)copper() complexes
dioxygen pressure) in agreement with a rate equation of and carbon monoxide. These results enable us to conclude,
first-order dependence with respect to [Cu(fla)(Bz-TAC)]- that in the enzyme catalyzed reaction, the activation of the
ClO4 and [Cu(fla)(iPr-TAC)]ClO4, respectively. Experi- substrate flavonol through its coordination to the copper()
ments performed at different dioxygen concentrations center probably takes place, and its oxygenation and sub-
showed that both of the reactions are also first order with sequent reaction of the copper-dioxygen species with fla-
respect to dioxygen concentration. According to the kinetic vonol is the real catalytic situation.
data obtained, the oxygenation reactions obey an overall
second-order rate equation, from which the mean values of
the kinetic constants kobs of 3.31 Ϯ 0.01 ϫ 10Ϫ3 ([Cu-
(fla)(Bz-TAC)]ClO4) and 1.51 Ϯ 0.01 ϫ 10Ϫ3 molϪ1·dm3
sϪ1 ([Cu(fla)(iPr-TAC)]ClO4) at 120 °C were obtained. The
calculated rate constant is, in the case of [Cu(fla)(Bz-TAC)]-
ClO4, almost two times larger than that for [Cu(fla)(iPr-
TAC)]ClO4. Oxidative cleavage of the C2ϪC3 double bond
of the pyranone ring of the coordinated flavonolato ligand
in both cases takes place in a similar fashion as in the enzy-
matic reaction. Stoichiometric oxygenation reactions can be
interpreted as shown in Scheme 4. We are inclined to as-
sume a redox role for the copper(). Due to the valence
isomerism of the copper() flavonolate complexes, copper()
flavonoxy radical species are also formed, as suggested ear-
lier.[37] Similar electromeric effects between metal cat-
echolate and metal semiquinone complexes have been dem-
onstrated.[52,53] They have two redoxactive sites, the fla-
vonoxy radical ligand and the CuI center, which can react
with dioxygen in a slow step to form the endoperoxide in-
termediates. These then break down rapidly to the corre-
sponding (O-benzoylsalicylato)copper() complexes and
CO.
Experimental Section
General Remarks: All reagents and solvents were purchased from
commercial sources and were of reagent quality unless otherwise
stated. All air-sensitive compounds were handled under argon
using standard Schlenk techniques.[54]
Caution! Perchlorate salts of metal complexes with organic ligands
are potentially explosive. Only small amounts of material should be
prepared, and these should be handled with great care.
Synthesis of [Cu(fla)(Bz-TAC)]ClO4 (9): A solution of [{Cu(Bz-
TAC)}2(µ-O)2](ClO4)2 in CH2Cl2 (15 mL) at Ϫ80 °C was prepared
as described previously (0.164 g, 0.5 mmol scale of CuI precur-
sor).[46,47] After removal of excess dioxygen by purging with argon
at Ϫ80 °C for 10 min, a solution of flavonol (0.119 g, 0.5 mmol) in
CH2Cl2 (5 mL) was added, resulting in an instantaneous color
change from red-brown to intense green. The reaction mixture was
stirred at Ϫ80 °C for 1 h, and then warmed to room temperature.
After concentrating the solution by evaporation under vacuum,
Et2O was added to induce precipitation of a green solid which was
collected by filtration, washed with Et2O, and air-dried (95%, m.p.
224Ϫ226 °C). The crude product was recrystallized from CH3CN.
C42H42ClCuN3O7 (799.80): calcd. C 63.1, H 5.3, N 5.3; found C
62.9, H 5.5, N 5.5. UV-Vis (DMF): λmax. (log ε) ϭ 269 (4.23) 432
(2.23), 615 (2.90), 1040 (1.73) nm. IR (KBr, cmϪ1): ν˜ ϭ 1097 (vs,
νClO4Ϫ), 634 (s, νClO4Ϫ), 1545 (s, νCO). EPR (MeCN): g ϭ 2.115,
A ϭ 66.0 G. µeff ϭ 1.93 BM.
Synthesis of [Cu(fla)(iPr-TAC)]ClO4 (10): This compound was pre-
pared analogously to [Cu(fla)(Bz-TAC)]ClO4 but by treating
[44]
[{Cu(iPr-TPA)}2(µ-η2:η2-O)2](ClO4)2
with flavonol (90%, m.p.
235Ϫ237 °C). The crude product was recrystallized from CH3CN.
C30H42ClCuN3O7 (655.7): calcd. C 55.0, H 6.5, N 6.4; found C
54.8, H 6.3, N 6.5. UV-Vis (DMF): λmax. (log ε) ϭ 274 (3.54) 434
(3.52), 653 (2.15), 1065 (1.89) nm. IR (KBr, cmϪ1): ν˜ ϭ 1097 (vs,
νClO4Ϫ), 628 (s, νClO4Ϫ), 1554 (s, νCO). EPR (MeCN): g ϭ 2.116,
A ϭ 66.4 G. µeff ϭ 1.89 BM.
Oxygenation of [Cu(fla)(R-TAC)]ClO4 (R ؍ Bz, iPr): [Cu(fla)(Bz-
TAC)]ClO4 or [Cu(fla)(iPr-TAC)]ClO4) (0.25 mmol) was dissolved
in DMF (5 mL) and stirred at 120 °C under dioxygen for 12 h. The
formation of [Cu(O-bs)(Bz-TAC)]ClO4 or [Cu(O-bs)(iPr-TAC)]-
ClO4 from [Cu(fla)(Bz-TAC)]ClO4 or [Cu(fla)(iPr-TAC)]ClO4 re-
quires dioxygen but no apparent uptake was observed because the
absorption of dioxygen, and the liberation of carbon monoxide
compensate each other. Dilute NH3 solution (0.5 mL) was added
to a portion of the reaction mixture (1 mL) at room temperature,
and the organic phase was extracted with diethyl ether. Diazometh-
ane solution (1 mL) was then added and the conversion to the
Scheme 4
Conclusion
In conclusion, we have found that Cu2III(µ-O)2 and
Cu2II(µ-η2:η2-O)2 complexes with triazacyclononane auxili-
ary ligands are not able to cleave the C2ϪC3 double bond coordinated flavonolate (78 and 57%) was determined by GC.
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Reaction of µ-η2:η2-Peroxo- and Bis(µ-oxo)dicopper Complexes with Flavonol
Synthesis of [Cu(O-bs)(Bz-TAC)]ClO4 (11): To a solution of 6.2, N 6.6. UV-Vis (DMF): λmax. (log ε) ϭ 278 (3.23), 670 (1.43),
FULL PAPER
[Cu(CH3CN)4]ClO4 (0.119 g, 0.5 mmol) and Bz-TAC (0.13 g, 1060 (1.73) nm. IR (KBr, cmϪ1): ν˜ ϭ 1095 (vs, νClO4Ϫ), 627 (s,
0.5 mmol) in CH3CN (10 mL) was added O-benzoylsalycilic acid
(0.121 g, 0.5 mmol) in CH3CN (10 mL), and the solution was
heated to reflux for 5 h under O2. After concentrating the solution
by evaporation under vacuum, Et2O was added to induce precipi-
tation of a blue solid, which was collected by filtration, washed
with Et2O, and air-dried (92%, m.p. 198Ϫ200 °C). X-ray quality
crystals were obtained by slow evaporation of a CH3CN solution.
C41H42ClCuN3O8 (803.8): calcd. C 61.3, H 5.3, N 5.2; found C
60.8, H 5.1, N 5.0. UV-Vis (DMF): λmax. (log ε) ϭ 276 (3.81), 650
(1.96), 1035 (1.62) nm. IR (KBr, cmϪ1): ν˜ ϭ 1097 (vs, νClO4Ϫ), 628
(s, νClO4Ϫ), 1741 (s, νCO), 1586 (s, νasCO2). 1432 (s, νsCO2). EPR
(MeCN): g ϭ 2.120, A ϭ 62.0 G. µeff ϭ 1.99 BM.
νClO4Ϫ), 1747 (s, νCO), 1584 (s, νasCO2). 1428 (s, νsCO2). EPR
(MeCN): g ϭ 2.121, A ϭ 60.3 G. µeff ϭ 1.97 BM.
Kinetic Measurements: Reactions of [Cu(fla)(Bz-TAC)]ClO4 and
[Cu(fla)(iPr-TAC)]ClO4 with dioxygen were performed in DMF
solutions. In a typical experiment [Cu(fla)(Bz-TAC)]ClO4 or [Cu-
(fla)(iPr-TAC)]ClO4 was dissolved under argon in a thermo-
statically controlled reaction vessel with an inlet for taking samples
with a syringe, and connected to a mercury manometer to maintain
a constant pressure. The solution was then heated to the appropri-
ate temperature. A sample was then taken by syringe and the initial
concentration of [Cu(fla)(Bz-TAC)]ClO4 or [Cu(fla)(iPr-TAC)]-
ClO4 was determined by UV-Vis spectroscopy measuring the ab-
sorbance of the reaction mixture at 432 nm or 434 nm {λmax. of a
typical band of [Cu(fla)(Bz-TAC)]ClO4 or [Cu(fla)(iPr-
Synthesis of [Cu(O-bs)(iPr-TAC)]ClO4 (12): This compound was
prepared analogously to [Cu(O-bs)(Bz-TAC)]ClO4 but using the
iPr-TAC ligand instead (90%, m.p. 235Ϫ237 °C). X-ray quality TAC)]ClO4]}, respectively. The argon was then replaced by dioxy-
crystals were obtained by slow evaporation of a CH3CN solution.
C29H42ClCuN3O8: calcd. C 52.8, H 6.4, N 6.4; found C 52.4, H
gen and consumption of the latter was periodically monitored. The
rate of oxygenation was independent of the stirring rate, excluding
Table 1. Crystal data, data collection, and structural refinement details
9
12
11
Empirical formula
Molecular mass
Temperature
Radiation and wavelength
Crystal system
C84H84Cl2Cu2N6O14
1599.55
293(2) K
C29H42ClCuN3O8
659.65
C41H42ClCuN3O8
803.77
˚
Mo-Kα, λ ϭ 0.71073 A
triclinic
triclinic
monoclinic
P21/c
¯
¯
Space group
P1
P1
Unit cell dimensions
˚
a (A)
9.831(3)
12.065(2)
16.512(3)
87.33(2)
83.26(1)
76.07(2)
1887.4(7)
1
10.756(1)
12.589(1)
12.787(2)
79.47(1)
73.31(1)
75.13(1)
1591.8(3)
2
19.373(3)
11.683(3)
19.355(2)
90
117.82(1)
90
3874.4(12)
4
1.38
˚
b (A)
˚
c (A)
α (°)
β (°)
γ (°)
3
˚
Volume (A )
Z
Density (calcd.) (Mg·mϪ3
Absorption coeff., µ (mmϪ1
F(000)
)
1.41
0.71
834
1.38
0.82
694
)
0.69
1676
Crystal color
grayish green
plate
0.60 ϫ 0.15 ϫ 0.05
psi-scan
dark green
block
0.40 ϫ 0.35 ϫ 0.25
bluish green
plate
0.50 ϫ 0.30 ϫ 0.25
Crystal description
Crystal size (mm)
Absorption correction
Transmission, max. and min.
θ Range [°]
0.9811 and 0.8005
2.42 Յ θ Յ 26.97
Ϫ12 Յ h Յ 12
Ϫ17 Յ k Յ 17
Ϫ17 Յ l Յ 17
17820
0.992
3
0%
0.9854 and 0.7605
2.28 Յ θ Յ 29.96
Ϫ15 Յ h Յ 15
0 Յ k Յ 15
0 Յ l Յ 25
19419
0.9817 and 0.9781
2.38 Յ θ Յ 27.97
Ϫ25 Յ h Յ 22
Index ranges
Ϫ15 Յ k Յ 15
Ϫ21 Յ l Յ 21
Reflections collected
Completeness to 2θ
Number of standard reflections
Decay
9786
0.994
0.986
1%
4%
Independent reflections
Reflections IϾ2σ(I)
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices IϾ2σ(I)
R indices (all data)
Max. and mean shift/esd.
8152 [R(int) ϭ 0.0422]
3692
9112 [R(int) ϭ 0.0265]
5140
9280 [R(int) ϭ 0.0142]
4537
full-matrix least-squares on F2
8152 /47/497
0.856
9112 /34 /463
0.902
R1 ϭ 0.0559, wR2 ϭ 0.1446
R1 ϭ 0.1026, wR2 ϭ 0.1621
0.067; 0.002
9280 /93 /530
0.867
R1 ϭ 0.0427, wR2 ϭ 0.0970
R1 ϭ 0.1171, wR2 ϭ 0.1098
2.637; 0.112
R1 ϭ 0.0544, wR2 ϭ 0.1257
R1 ϭ 0.1411, wR2 ϭ 0.1478
0.001; 0.000
Ϫ3
˚
Largest diff. peak and hole (e·A
)
0.749 and Ϫ0.456
1.000 and Ϫ0.689
0.363 and Ϫ0.312
Eur. J. Inorg. Chem. 2004, 2253Ϫ2259
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2257

´
´
J. Kaizer, J. Pap, G. Speier, L. Parkanyi
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Received August 26, 2003
Early View Article
Published Online April 7, 2004
Eur. J. Inorg. Chem. 2004, 2253Ϫ2259
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2259