Copper-mediated oxygenation of flavonolate in the presence of a tridentate N-ligand. Synthesis and crystal structures of [Cu(fla)(idpaH)]ClO4 and [Cu(idpaH)(O-bs)]ClO4, [fla = flavonolate, idpaH = 3,3'-iminobis(N,N-dimethylpropylamine), O-bs = O-benzoylsalicylate]

Article abstract of DOI:10.1016/S0020-1693(00)00071-2

The complexes [Cu(fla)(idpaH)]ClO₄ (4) and [Cu(idpaH)(O-bs)]ClO₄ (5) (fla = flavonolate, idpaH = 3,3'-iminobis(N,N-dimethylpropylamine), O-bs = O-benzoylsalicylate) have been synthesised and characterised. Complex 5 can be obtained also by the oxygenation of 4 and concomitant CO release. The structures of the compounds have been determined by X-ray diffraction. Complex 4 exhibits distorted trigonal-bipyramidal geometry around the copper(II) ion while complex 5 is distorted square-pyramidal. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(00)00071-2

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 304 (2000) 72–77
Copper-mediated oxygenation of flavonolate in the presence of a
tridentate N-ligand. Synthesis and crystal structures of
[Cu(fla)(idpaH)]ClO4 and [Cu(idpaH)(O-bs)]ClO4, [fla=flavonolate,
idpaH=3,3%-iminobis(N,N-dimethylpropylamine),
O-bs=O-benzoylsalicylate]
a
a,b
b,
c
´
Eva Balogh-Hergovich , Jo´zsef Kaizer , Ga´bor Speier *, Gottfried Huttner ,
La´szlo´ Zsolnai c
a Research Group for Petrochemistry of the Hungarian Academy of Sciences, 8201 Veszpre´m, Hungary
b Department of Organic Chemistry, Uni6ersity of Veszpre´m, 8201 Veszpre´m, Hungary
c Anorganisch-Chemisches Institut der Uni6ersita¨t Heidelberg, 69120 Heidelberg, Germany
Received 23 September 1999; accepted 21 January 2000
Abstract
The complexes [Cu(fla)(idpaH)]ClO4 (4) and [Cu(idpaH)(O-bs)]ClO4 (5) (fla=flavonolate, idpaH=3,3%-iminobis(N,N-dimethyl-
propylamine), O-bs=O-benzoylsalicylate) have been synthesised and characterised. Complex 5 can be obtained also by the
oxygenation of 4 and concomitant CO release. The structures of the compounds have been determined by X-ray diffraction.
Complex 4 exhibits distorted trigonal-bipyramidal geometry around the copper(II) ion while complex 5 is distorted square-pyra-
midal. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Crystal structures; Copper; Flavonolate complexes; Salicylate complexes
Only limited data on quercetinase are available in the
literature and the role of the copper ion at its active site
1. Introduction
is obscured. In the resting state of quercetinase, cop-
The oxidative degradation of various organic com-
per(II) ion has been found and the substrate quercetin
pounds proceeds with the help of dioxygen utilizing
is believed to coordinate to copper(II) through its 3-hy-
oxygenases [1]. One of these metalloenzymes, the cop-
droxy and 4-carbonyl groups [6–8]. Investigations how-
per-containing quercetin 2,3-dioxygenase, converts
ever, have been done on functional model systems on
quercetin (1a) to a depside (2a, carboxylic acid ester)
with loss of carbon monoxide (Eq. (1)) [2–5].
the parent compound flavonol (1b) [9–11] together with
autoxidation reactions [12,13]. Our interest in flavono-
lato copper complexes as possible functional models for
the active site of quercetinase has led us to synthesise a
number of compounds with 3-hydroxyflavones. Cop-
per(I) and copper(II) flavonolate (fla) complexes with
simple ligands were prepared and successfully used in
the oxygenation of flavonol [14–18]. These systems
provide the first copper-containing functional models
for quercetinase. As an extension of this work we
intended to work out copper(I) and copper(II) flavono-
late complexes with the tridentate ligand 3,3%-imino-
bis(N,N-dimethylpropylamine) (3, idpaH).
(1)
* Corresponding author. Tel. +36-88-422 022, ext. 4657; fax:
+36-88-427 492.
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(00)00071-2

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E. Balogh-Hergo6ich et al. / Inorganica Chimica Acta 304 (2000) 72–77
73
crystals of 5 (0.24 g, 80%). M.p. 195°C. Anal. Calc. for
C24H33N3O8CuCl: C, 48.73; H, 5.79; N,7.10. Found: C,
46.90; H, 5.47; N, 6.83%. IR (Nujol): 3198 w(NH), 1717
w(CO), 1572 and 1375 w(CO2), 1079, 1032, 655 w(ClO4)
cm−1. UV–Vis (lmax DMF): 276 (log m/dm3 mol−1
cm−1 3.979), 716 (2.445) nm. vB=1.80. gÞ=2.05,
gꢀ=2.22.
Here we report the preparation and the crystal struc-
ture of a Cu(II) flavonolate complex with the ligand
idpaH. Furthermore the oxygenation of the flavonolato
copper(II) complex to the copper(II) complex of the
corresponding depside (O-benzoylsalicylic acid, O-bsH)
and CO. The X-ray structure of the latter is also
reported.
2.3. Oxygenation of [Cu( fla)(idpaH)]ClO4 in DMF
Complex 4 was dissolved in DMF under N2 atmo-
sphere in a thermostated reaction vessel with an inlet
for taking samples. The solution was then heated to
100°C, and N2 was replaced with dioxygen. The reac-
tion was followed by electronic spectra in the range
200–500 nm. The consumption of [Cu(fla)(idpaH)]ClO4
was analyzed periodically (about every 10 min) at
426.5 nm. In order to isolate 5, 294 mg (0.5 mmol)
of [Cu(fla)(idpaH)]ClO4 was stirred in 50 cm3 of
DMF for 8 h, the solution was cooled to r.t. and
diethyl ether was layered to afford blue powder of 5
(183 mg, 62%).
2. Experimental
All preparations were carried out using standard
Schlenck techniques [19]. Solvents used for the reac-
tions were purified by literature methods and stored
under argon. Flavonol [9], O-benzoylsalicylic acid [20],
and tetrakis(acetonitrile)copper(I) perchlorate [21] were
prepared by literature methods. The compounds 3,3%-
iminobis(N,N-dimethylpropylamine) and Cu(ClO4)2·
6H2O were obtained from Aldrich and used without
further purification.
2.4. Physical measurements
Electronic spectra were recorded on a Shimadzu UV-
160 (Carl Zeiss) spectrometer. IR spectra were taken as
Nujol mulls using a Specord IR-75 (Carl Zeiss) spec-
trophotometer. Magnetic susceptibilities were deter-
mined at r.t. with a Bruker B-E 10B8 magnetic balance.
EPR spectra were obtained with a Jeol JES-FE3X
spectrometer. Microanalysis were carried out by Micro-
analytical Service of the University of Veszpre´m.
2.1. Preparation of [Cu( fla)(idpaH)]ClO4 (4)
Cu(ClO4)2·6H2O (0.370 g, 1 mmol) and 3,3%-imino-
bis(N,N-dimethylpropylamine) (0.187 g, 1 mmol) in
methanol (20 cm3) were stirred under an atmosphere of
N2 for 1 h. The solution was then treated with flavonol
(0.238 g, 1 mmol) and piperidine (0.085 g, 1 mmol) and
the mixture stirred at room temperature (r.t.) under an
atmosphere of N2 for 2 h. A green solid which de-
posited was then filtered off and recrystallised from
acetonitrile to give 4 as green crystals (0.53 g, 90%).
M.p. 267°C. Anal. Calc. for C25H34N3O7CuCl: C, 51.10;
H, 5.83; N, 7.10. Found: C, 50.32; H, 5.43; N, 7.02%.
IR (Nujol): 3228 w(NH), 1559 w(CO), 1095, 1055, 631
w(ClO4) cm−1. UV–Vis (umax DMF): 262 (log m/dm3
mol−1 cm−1 4.271), 426.5 (4.287), 690 (2.232) nm.
vB=1.85.
2.5. X-ray crystallography
Suitable crystals of 4 were obtained from acetonitrile
solution upon standing at r.t. for a few days. Suitable
crystals of 5 were grown by slow diffusion of diethyl
ether into acetonitrile solution of the complex at −
20°C. Data for both compounds were measured on a
Siemens (Nicolet Syntex) R3m/V diffractometer with
Mo Ka radiation using ꢀ-scans. The data were cor-
rected for Lorentz polarisation factors and experimen-
tal absorption (based on „-scans D„=10°) corrections
were applied.
2.2. Preparation of [Cu(idpaH)(O-bs)]ClO4 (5)
The crystal structures were solved by direct methods
and refined by the full-matrix least-squares on F2. The
[Cu(CH3CN)4]ClO4 (0.164 g, 0.5 mmol) and O-ben-
zoylsalicylic acid (0.242 g, 1 mmol) were dissolved in 30
cm3 of acetonitrile and stirred under an atmosphere of
O2 for 2 h, then 3,3%-iminobis(N,N-dimethylpropy-
lamine) (0.093 g, 0.5 mmol) was added and the solution
refluxed for 5 h. Diethyl ether was layered on the
solution and left at −20°C for 5 days to afford blue
weighting scheme was
w
−1=s2(Fo2)+(aP)2 where
3P=(Fo2+2Fc2) and a=0.0618 for 4 and 0.0828 for 5.
Form factors were taken from the usual sources [22].
Computations were carried out using SHELXL-93 [23]
and SHELXS-86 [24] programs. Further details are given
in Table 1.

´
74
E. Balogh-Hergo6ich et al. / Inorganica Chimica Acta 304 (2000) 72–77
Table 1
3. Results and discussion
Crystal data and details of data collection and structure refinement
for complexes 4 and 5
3.1. Characterisation of the complex
[Cu( fla)(idpaH)]ClO4 (4)
4
5
Formula
Molecular
weight
Crystal system
Temperature
(K)
Wavelength (A) 0.71073
Monochromator graphite
Space group
Unit cell dimen-
sions
C25H34N3O7CuCl
587.54
C
590.52
24H33N3O8CuCl
Complex 4 was isolated as a green solid by the
reaction of Cu(ClO4)2·6H2O, flavonol and 3,3%-imino-
bis(N,N-dimethylpropylamine) in the presence of pipe-
ridine at r.t. in methanol under an atmosphere of N2, as
summarised in Eq. (2):
monoclinic
200
triclinic
200
,
0.71073
graphite
P1
Cu(ClO4)2·6H2O+flaH+idaH
N , MeOH
2
(
P21/n
ꢀꢀꢀꢀꢀꢀꢀꢀꢁ [Cu(fla)(idpaH)]ClO4 (2)
piperidine
4
The IR spectrum of complex 4 shows the principal
band corresponding to the coordinated flavonolate at
1559 cm−1. The decrease of approximately 40 cm−1 of
the w(CO) band compared to that of flavonol (w(CO)
1602 cm−1) is due to chelation and formation of a
stable five-membered ring [25]. The absorption bands at
1095, 1055 and 631 cm−1 can be assigned to the
perchlorate anion. The weak band at 3228 cm−1 can be
rendered to the w(NH) of the 3,3%-iminobis(N,N-
dimethylpropylamine) ligand. The charge transfer re-
gion of the electronic spectrum of the complex exhibits
band of the coordinated flavonolate ligand at 426.5 nm.
The band at 690 nm is associated with the d-d transi-
tion of the complex. R.t. magnetic measurements
yielded a value of vB=1.85 for 4 consistent with a
copper(II) ion.
,
a (A)
10.248(2)
18.273(2)
14.264(2)
90.0
98.59(1)
90.0
2641.1(7)
4
0.30×0.30×0.25
7.880(3)
12.721(3)
14.390(4)
71.01(2)
77.84(2)
75.42(2)
1306.9(7)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
Volume (A )
Z
3
,
Crystal size
(mm)
0.20×0.25×0.20
Colour
green
1.478
1228
0.977
4.5–48.0
blue
1.501
616
0.991
3.9–50.1
Dcalc (g cm−3
F(000)
)
v (mm−1
)
2q Range (°)
Index ranges
−115h5−14, −165 −95h5−14, −165
k511, 205l516
k59, 145l517
4939
Reflections col- 4395
lected
Independent
reflections
4142
4567
3.2. Oxygenation of complex [Cu( fla)(idpaH)]ClO4
Observed data
[I\2|(I)]
Final R1, wR2
[I\2|(I)]
(all data)
Goodness-of-fit 1.115
3252
2658
Treatment of the flavonolato copper complex 4 with
dioxygen in DMF solution at elevated temperature
leads to the corresponding O-benzoylsalicylato copper
complex, [Cu(idpaH)(O-bs)]ClO4, 5. The oxygenation
of 4 was followed by UV–Vis spectroscopy. The time
course of the variation of [Cu(fla)(idpaH)]ClO4 in DMF
solution at 100°C is shown in Fig. 1. Plots of
log[Cu(fla)(idpaH)]ClO4 versus time showed a linear
dependence under pseudo-first-order conditions (con-
stant dioxygen pressure) in agreement with a rate equa-
tion of first-order dependence with respect to the
complex 4. The pseudo-first-order rate constant k was
found to be 6.1390.16×10−3 mol−1 dm3 s−1 at
100°C.
0.0498, 0.1212
0.0698, 0.1308
0.0795, 0.1657
0.1534, 0.2139
1.311
Fig. 1. Time course of the oxygenation of 4. {[Cu(fla)-
(idpaH)]ClO4}0=10×10−4 M, [O2]=6.1×10−3 M, 50 cm3 DMF,
120°C.

´
E. Balogh-Hergo6ich et al. / Inorganica Chimica Acta 304 (2000) 72–77
75
The infrared (IR) spectrum of the complex shows
bands corresponding to the coordinated O-benzoylsali-
cylate at 1717 w(CO), 1572 and 1375 w(CO2) cm−1
.
Absorption bands at 1079, 1032 and 655 cm−1 may be
assigned to the perchlorate anion. The electronic spec-
trum of the complex 5 shows an absorption band at 716
nm due to d–d transition. A higher energy band at 276
nm is associated with charge transfer transition. R.t.
magnetic measurements yielded a value of vB=1.80 for
the complex consistent with a copper(II) ion. The solid
state EPR spectrum of 5 is typical of a square pyrami-
dal Cu(II) ion exhibiting an axial spectrum with gÞ=
2.05 and gꢀ=2.22.
3.4. X-ray crystal structures of complexes 4 and 5
Fig. 2. Molecular structure of [Cu(fla)(idpaH)]ClO4 (4).
The molecular structure and atom numbering scheme
for the crystalline complex 4 is shown in Fig. 2, and
selected bond distances and angles are listed in Table 2.
The geometry around the copper ion is distorted trigo-
nal bipyramidal with ~=0.61. For perfect square pyra-
midal and trigonal bipyramidal geometries the values of
~ are zero and unity respectively, ~ being an index of
the degree of trigonality within the structural contin-
uum between square pyramidal and trigonal bipyrami-
dal geometries [26]. Two nitrogen atoms of the
tridentate ligand idpaH (Cu(1)–N(1) 2.137(3), Cu(1)–
Table 2
,
Selected bond lengths (A) and bond angles (°) for [Cu(fla)-
(idpaH)]ClO4
Cu(1)–O(2)
Cu(1)–N(2)
Cu(1)–N(3)
Cu(1)–N(1)
Cu(1)–O(1)
O(1)–C(1)
O(2)–C(9)
O(3)–C(7)
O(3)–C(8)
C(1)–C(9)
C(2)–C(7)
1.918(3)
2.006(4)
2.112(4)
2.137(3)
2.210(3)
1.260(5)
1.320(5)
1.365(5)
1.369(5)
1.436(6)
1.378(6)
N(1)–C(22)
N(1)–C(16)
N(1)–C(23)
N(2)–C(18)
N(2)–C(19)
N(3)–C(24)
N(3)–C(25)
N(3)–C(21)
N(2)–H(2)
C(1)–C(2)
1.482(6)
1.489(6)
1.491(6)
1.474(5)
1.487(5)
1.443(6)
1.454(6)
1.501(6)
0.75(6)
,
N(3) 2.112(4) A), and one oxygen atom of the flavono-
,
late ligand (Cu(1)–O(1) 2.210(3) A) occupy basal
1.449(5)
1.386(5)
positions. The other oxygen atom of the flavonolate
C(8)–C(9)
,
(Cu(1)–O(2) 1.918(3) A), and one nitrogen of the 3,3%-
O(2)–Cu(1)–N(2) 169.14(13)
O(2)–Cu(1)–N(3) 92.61(13)
N(2)–Cu(1)–N(3) 92.78(14)
O(2)–Cu(1)–N(1) 91.41(13)
N(2)–Cu(1)–N(1) 91.90(13)
N(3)–Cu(1)–N(1) 132.41(14)
O(2)–Cu(1)–O(1) 80.18(11)
N(2)–Cu(1)–O(1) 89.14(12)
N(3)–Cu(1)–O(1) 109.38(12)
N(1)–Cu(1)–O(1) 118.02(12)
Cu(1)–N(2)–H(2) 104.00(5)
C(1)–O(1)–Cu(1)
C(9)–O(2)–Cu(1)
C(22)–N(1)–Cu(1)
C(16)–N(1)–Cu(1)
C(23)–N(1)–Cu(1)
C(18)–N(2)–Cu(1)
C(19)–N(2)–Cu(1)
C(24)–N(3)–Cu(1)
C(25)–N(3)–Cu(1)
C(21)–N(3)–Cu(1)
107.3(2)
115.3(2)
108.3(3)
112.1(3)
113.0(3)
110.6(3)
111.6(3)
110.3(3)
112.2(3)
109.6(3)
iminobis(N,N-dimethylpropylamine) ligand (Cu(1)–
,
N(2) 2.006(4) A) are in apical positions. The Cu–O
bond distances are comparable with those of the
,
[Cu(fla)(ind)] (1.942(5), 2.206(5) A) [27]. They are how-
ever longer than those in [Cu(fla)2] (1.901(2), 1.944(3)
,
,
A) [15]. The Cu–O(1) bond length is 0.29 A longer than
the Cu–O(2) bond. The C(9)–O(2) distance is shorter
while the C(1)–O(1) distance is longer than those in the
,
uncoordinated flavonol (1.357(3) and 1.232(3) A) [28].
Due to coordination to the copper ion there are
changes in the bond lengths of the pyranone ring too.
,
,
The O(3)–C(8) (1.369(5) A), C(7)–C(2) (1.378(6) A)
bond distances become longer, and the C(1)–C(9) bond
,
An oxidative cleavage of the C2–C3 double bond of
the pyranone ring of the coordinated flavonolato ligand
takes place in a similar fashion as in the enzymatic
reaction.
distance (1.436(6) A) is somewhat shorter which may be
assigned to delocalisation of the p-system over the
whole molecule. There is a weak N–H···O hydrogen
bonding between the O(8) of the perchlorate anion and
the N(2) of the idpaH ligand.
3.3. Characterisation of the complex
[Cu(idpaH)(O-bs)]ClO4 (5)
The molecular structure and atom numbering scheme
for the crystalline complex 5 is shown in Fig. 3, and
selected bond distances and angles are listed in Table 3.
The molecule is monomeric in the solid state. The
copper(II) centre is in distorted square-pyramidal envi-
ronment (~=0.16) with basal planes defined by three
nitrogen atoms derived from the tridentate 3,3%-imino-
The O-benzoylsalicylato complex was also prepared
by the reaction of [Cu(CH3CN)4]ClO4, O-benzoylsali-
cylic acid and 3,3%-iminobis(N,N-dimethylpropylamine)
in acetonitrile under an atmosphere of O2 at r.t.

´
E. Balogh-Hergo6ich et al. / Inorganica Chimica Acta 304 (2000) 72–77
76
data can be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements
We thank the Hungarian Research Fund (OTKA
T-7443, T-16285 and T-030400) and COST (ER-
BCIPECT926093, 12160) for financial support. We also
thank Dr. A. Rockenbauer (Budapest) for the ESR
spectra.
References
Fig. 3. Molecular structure of [Cu(idpaH)(O-bs)]ClO4 (5).
Table 3
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D.W.S. Westlake, Biochem. Biophys. Res.Commun. 2 (1959)
621.
,
Selected bond lengths (A) and bond angles (°) for [Cu(idpaH)(O-
bs)]ClO4
Cu(1)–O(1)
Cu(1)–N(2)
Cu(1)–N(1)
Cu(1)–N(3)
Cu(1)–O(2)
O(1)–C(11)
O(2)–C(11)
1.995(5)
1.996(7)
2.036(7)
2.044(7)
2.344(6)
1.308(9)
1.236(9)
N(1)–C(7)
N(1)–C(8)
N(2)–C(4)
N(2)–C(3)
N(3)–C(6)
N(3)–C(10)
N(3)–C(9)
1.477(10)
1.497(10)
1.481(10)
1.497(11)
1.466(10)
1.476(11)
1.480(11)
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[4] H. Sakamoto, Seikagu (J. Jpn. Biochem. Soc.) 35 (1963) 633.
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16 (1977) 493.
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1640.
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Soc., Perkin Trans. I (1979) 2511.
O(1)–Cu(1)–N(2) 159.5(3)
N(3)–Cu(1)–O(2)
C(1)–N(1)–Cu(1)
C(7)–N(1)–Cu(1)
C(8)–N(1)–Cu(1)
C(4)–N(2)–Cu(1)
C(3)–N(2)–Cu(1)
C(6)–N(3)–Cu(1)
C(10)–N(3)–Cu(1)
C(9)–N(3)–Cu(1)
101.9(2)
111.2(5)
115.3(5)
104.7(5)
107.6(6)
105.2(5)
110.6(5)
102.7(5)
116.3(5)
O(1)–Cu(1)–N(1)
N(2)–Cu(1)–N(1)
O(1)–Cu(1)–N(3)
N(2)–Cu(1)–N(3)
91.1(3)
94.9(3)
90.1(3)
94.4(3)
N(1)–Cu(1)–N(3) 149.9(3)
O(1)–Cu(1)–O(2)
N(2)–Cu(1)–O(2)
60.3(2)
99.2(2)
N(1)–Cu(1)–O(2) 104.7(2)
[10] V. Rajananda, S.B. Brown, Tetrahedron Lett. 22 (1981) 4331.
[11] T. Matsuura, H. Matsushima, R. Nakashima, Tetrahedron 26
(1970) 435.
[12] A. Nishinaga, T. Kuwashige, T. Tsutsui, T. Mashino, K.
Maruyama, J. Chem. Soc., Dalton Trans. (1994) 805.
[13] M. Utaka, A. Takeda, J. Chem. Soc., Chem. Commun. (1985)
1824.
bis(N,N-dimethylpropylamine) ligand and one oxygen
atom of the bidentate carboxylate group (Cu(1)–O(1)
,
1.995(5) A). The apical position is occupied by the
other oxygen atom of the O-benzoylsalicylate (Cu(1)–
,
O(2) 2.344(6) A). The copper–nitrogen bond distances
[14] G. Speier, V. Fu¨lo¨p, L. Pa´rka´nyi, J. Chem. Soc., Chem. Com-
mun. (1990) 512.
(Cu(1)–N(1) 2.036(7), Cu(1)–N(2) 1.996(7), Cu(1)–
,
N(3) 2.044(7) A), are similar to values obtained for 4.
´
[15] E. Balogh-Hergovich, G. Speier, Gy. Argay, J. Chem. Soc.,
,
The Cu–O distance in the basal plane is 0.349 A
Chem. Commun. (1991) 551.
´
shorter than the distance of Cu to apical O. The
Cu–O(1) distance is shorter while the Cu–O(2) length
is longer than those in [Cu(O-bs)(PPh3)2] (2.148(2) and
[16] E. Balogh-Hergovich, J. Kaizer, G. Speier, Inorg. Chim. Acta
256 (1997) 9.
[17] I. Lippai, G. Speier, G. Huttner, L. Zsolnai, Chem. Commun.
(1997) 741.
,
2.280(2) A) [29].
[18] I. Lippai, G. Speier, J. Mol. Catal. 130 (1998) 139.
[19] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air-Sensi-
tive Compounds, Wiley, New York, 1986.
[20] A. Einhorn, L. Rothlauf, R. Seuffert, Chem. Ber. 44 (1911)
3309.
4. Supplementary material
[21] B.J. Hathaway, D.G. Holah, J.D. Postlethwaite, J. Chem. Soc.
(1961) 3215.
[22] International Tables for X-ray Crystallography, vol. 4, Kynoch
Press, Birmingham, 1974.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 142157, 142158. Copies of the

´
E. Balogh-Hergo6ich et al. / Inorganica Chimica Acta 304 (2000) 72–77
77
[23] G.M. Sheldrick, SHELXL-93, Program for Crystal Structure shoor, J. Chem. Soc., Dalton Trans. (1984) 1349.
´
Refinement, University of Go¨ttingen, Germany, 1993.
[24] G.M. Sheldrick, SHELXS-86, Program for Crystal Structure Solu-
tion, University of Go¨ttingen, Germany, 1990.
[25] L.M. Bellamy, Ultrarot-Spektrum und chemische Konstitution,
Dr. Dietrich Steinkopff Verlag, Darmstadt, 1966, p. 12.
[26] A.W. Addison, T.N. Rao, J. Reedijk, J. van Rijn, G.C. Ver-
[27] E. Balogh-Hergovich, J. Kaizer, G. Speier, G. Huttner, L.
Zsolnai, A. Jacobi, submitted for publication.
[28] M.C. Etter, Z. Urbanczyk-Lipkowska, S. Baer, P.F. Barbara, J.
Mol. Struct. 144 (1986) 155.
´
[29] E. Balogh-Hergovich, J. Kaizer, G. Speier, V. Fu¨lo¨p, L.
Pa´rka´nyi, Inorg. Chem. 38 (1999) 3787.
.