The use of solvatochromic mixed copper(II) chelates with N,N,N′,N′-tetramethylethylenediamine and tropolonato or hinokitiolato ligands, [Cu(trop/hino)(tmen)]B(C6H5) 4, as indicator for Lewis basicity of solvents and low-coordinating anions

Article abstract of DOI:10.1016/j.ica.2004.08.021

Mixed copper(II) chelates, [Cu(trop/hino)(tmen)]B(C₆H ₅)₄, were prepared with a tropolonato or hinokitiolato ligands (trop/hino) and N,N,N′,N′-tetramethylethylenediamine (tmen). These chelates turned out to be excellent Lewis basicity indicators in solution because their d-d bands continuously shift to red in wider ranges with increasing DN (donor number) of solvent, visualizing the competition between solvent molecule and anion for coordination to metal center. Mixed copper(II) chelates, [Cu(trop/hino)(tmen)]B(C₆H₅)₄, were prepared with a tropolonato or hinokitiolato ligands (trop/hino) and N,N,N′,N′-tetramethylethylenediamine (tmen). These chelates were, as expected, quite similar to the corresponding acetylacetonato analog [Cu(acac)(tmen)]B(C₆H₅)₄, being fairly soluble in a large number of solvents and remarkably solvatochromic in them. They were also useful as excellent Lewis basicity indicators in solution because their d-d bands continuously shift to red in wider ranges with increasing DN (donor number) of solvent. The examination on addition of various anions to these solvatochromic systems led to a quantitative view of the competition between solvent molecule and anion for coordination to metal center.

Full text of DOI:10.1016/j.ica.2004.08.021

Inorganica Chimica Acta 358 (2005) 409–414
www.elsevier.com/locate/ica
Note
The use of solvatochromic mixed copper(II) chelates with
N,N,N0,N0-tetramethylethylenediamine and tropolonato or
hinokitiolato ligands, [Cu(trop/hino)(tmen)]B(C6H5)4, as indicator
for Lewis basicity of solvents and low-coordinating anions
a
Aurore Camard , Yoshinori Ihara , Fumiko Murata , Kurt Mereiter ,
b
c
d
c
Yutaka Fukuda , Wolfgang Linert
a,
*
a
Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Getreidemarkt 9/163-AC, A-1060-Vienna, Austria
b
Department of Chemistry, Faculty of Education, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan
Department of Chemistry, Faculty of Science, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
c
d
Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Getreidemarkt 9/164, A-1060-Vienna, Austria
Received 8 April 2004; accepted 20 August 2004
Available online 8 October 2004
Abstract
Mixed copper(II) chelates, [Cu(trop/hino)(tmen)]B(C6H5)4, were prepared with a tropolonato or hinokitiolato ligands (trop/hino)
and N,N,N0,N0-tetramethylethylenediamine (tmen). These chelates were, as expected, quite similar to the corresponding acetylaceto-
nato analog [Cu(acac)(tmen)]B(C6H5)4, being fairly soluble in a large number of solvents and remarkably solvatochromic in them.
They were also useful as excellent Lewis basicity indicators in solution because their d–d bands continuously shift to red in wider
ranges with increasing DN (donor number) of solvent. The examination on addition of various anions to these solvatochromic sys-
tems led to a quantitative view of the competition between solvent molecule and anion for coordination to metal center.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Solvatochromism; Lewis basicity indicators; Anion coordination; Solvent effects
1. Introduction
Solvatochromism of metal complexes can be divided
into two types [2–4]; the first type comprises the case
where the color changes are brought about by the direct
attachment of solvent molecules onto metal center, and
the second type is due to the attachment of solvent mol-
ecules onto ligands. Among the former whose color
changes are due to those of d–d transitions, copper(II)
complexes with a strong Jahn–Teller effect can be antic-
ipated to show simple and regular changes in their elec-
tronic spectra according to the strength of interactions
with solvent molecules at the axial sites.
A number of empirical scales for solvent polarity,
mainly based upon effects of selected solvation process,
have been proposed in order to systematize and corre-
late observed solvation effects, although only a few have
gained widespread use [1]. The methods using solvato-
chromic behavior of transition metal complexes will also
serve as visualized models of solute–solvent interactions.
We have indicated that [Cu(acac)(tmen)]B(C6H5)4
(acac = acetylacetone, tmen = N,N,N0,N0-tetramethyle-
thylenediamine), well-known to be one of the
*
Corresponding author. Tel.: +4315880115350; fax: +43158801
16299.
E-mail address: wlinert@mail.zserv.tuwien.ac.at (W. Linert).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.08.021

410
A. Camard et al. / Inorganica Chimica Acta 358 (2005) 409–414
representative solvatochromic chelates, could be used
as an excellent Lewis basicity indicator in solution
due to its continuous shift of the absorption maxima
while varying the Lewis basicity of the solvent [5,6].
In a continuation of this study, we show here that
the new chelates containing tropolone(trop) or hinoki-
tiol(hino) instead of acac, [Cu(trop/hino)(tmen)]-
B(C6H5)4, are more sensitive to changes in the donor
properties of solvents than the acac analog, and be-
come good models for estimating a quantitative view
of competition between solvent molecule and anion
for coordination to Cu(II) ion, when various anions
were added in their solvatochromic systems.
2.3. X-ray crystallography
Single crystals of [Cu(trop)(tmen)(dce)]B(C6H5)4
(dce = 1,2-dichloroethane) and [Cu(trop)(tmen)(ac)]B-
(C6H5)4 (ac = acetone) were obtained by slow diffusion
of diethyl ether in 1,2-dichloroethane and acetone solu-
tions of [Cu(trop)(tmen)]B(C6H5)4. X-ray data were col-
lected with
a Bruker AXS Smart APEX CCD
diffractometer and graphite monochromatized Mo Ka
˚
radiation; k = 0.71073A. Corrections for absorption were
carried out with multi-scan method and SADABS pro-
gram, structure solution with direct methods, structure
refinement on F2 with anisotropic displacement parame-
ters for non-hydrogen atoms; hydrogen atoms were in-
cluded in idealized positions (Bruker AXS, 2001:
programs SMART, version 5.626; SAINT, version 6.36A;
SADABS version 2.05; XPREP, version 6.12; SHELXTL, ver-
sion 6.10. Bruker AXS Inc., Madison, WI, USA).
2. Experimental
2.1. Materials
Crystal data for [Cu(trop)(tmen)(dce)]B(C6H5)4:
C39H45BCl2CuN2O2, M = 719.02, monoclinic, space
group P21/n, a = 18.597(3), b = 9.241(2), c = 21.650(4)
The mixed copper(II) chelates were prepared as fol-
lows. Copper(II) chloride dihydrate (2 mmol) is dis-
solved in methanol (5 cm3), and a methanolic solution
(5 cm3) containing N,N,N0,N0-tetramethylethylenediam-
ine (tmen) and tropolone (trop) or hinokitiol (hino) is
added with stirring. Then, sodium carbonate (1 mmol)
is added to the solution, which is gently heated for 1 h
and then filtered. The crude crystals obtained upon
addition of sodium tetraphenylborate (3 mmol) to the
filtrate are recrystallized from 1,2-dichloroethane. The
brown-violet crystals obtained are kept over phospho-
rus(V) oxide overnight to dry up. Elemental analyses
of the chelates gave the following data. Anal. Calc. for
[Cu(trop)(tmen)]B(C6H5)4: C, 68.8; H, 6.7; N, 4.5.
Found: C, 69.1; H, 6.4; N, 4.3%. Anal. Calc. for [Cu(hi-
no)(tmen)]B(C6H5)4: C, 72.6; H, 7.2; N, 4.2. Found: C,
72.5; H, 7.0; N, 4.2%.
3
˚
˚
A, b = 98.318(4)ꢁ, V = 3681.4(12) A , Z = 4, Dcalcd
=
1.297 g/cm3, T = 123(2) K, l = 0.774 mmꢀ1, F(000) =
1508, violet prism (0.65 · 0.28 · 0.20 mm), total/unique
reflections 26783/10374, Rint = 0.022, hmax = 30ꢁ; final
refinement: data/restraints/parameters 10374/0/425,
GOF = 1.02, R1(wR2) = 0.032 (0.079) (I>2r(I)).
Crystal data for [Cu(trop)(tmen)(ac)]B(C6H5)4:
C40H47BCuN2O3, M = 678.15, monoclinic, space group
˚
P21/n, a = 10.0011(17), b = 21.466(4), c = 17.074(3) A,
3
˚
b = 94.590(3)ꢁ, V = 3653.8(11) A , Z = 4, Dcalcd = 1.233
g/cm3, T = 297(2) K, l = 0.636 mmꢀ1, F(000) = 1436,
violet prism (0.75 · 0.28 · 0.27 mm), total/unique reflec-
tions 43191/7934, Rint = 0.029, hmax = 27ꢁ; final refine-
ment: data/restraints/parameters 7934/0/431, GOF =
1.03, R1(wR2) = 0.041 (0.106) (I>2r(I)).
2.2. Spectral measurements
3. Results and discussion
Electronic spectra of the chelates were recorded at
room temperature with either a one-cell WPI Fiber
optic UV–Vis spectrophotometer or a two-cell Varian
Cary 17D UV–Vis spectrophotometer within the range
of 250–780 nm using 1,2-dichloroethane as reference.
The sample solutions were prepared by mixing 2 ml
of 1,2-dichloroethane solution of the chelate (5 mM)
and 1 ml of donor solvent; the measurements were
carried out in such mixed solvent systems. In the case
of the measurements in the presence of anions, the
sample solutions were prepared by mixing 1 ml of
1,2-dichloroethane solution of the chelate(5 mM), 0.5
ml of 1,2-dichloroethane solution containing the anion
Aꢀ (5 mM), and 0.5 ml of donor solvent. Recrystal-
lized tetrabutylammonium salts were used as a source
of anion supply, except for the acetate and carbonate
for which ammonium salts were used.
3.1. Solvatochromism of the mixed chelates
As in the case of the [Cu(acac)(tmen)]B(C6H5)4- type
chelates [5,7], the trop and hino chelates prepared are all
soluble in a large number of organic solvents, forming
violet solutions in solvents of low DN (GutmanÕs donor
number) [8] and changing through blue to green as the
solvent DN increases.
The observed mmax values of the d–d bands of the
chelates in various solvents are summarized in Table
1 and plotted versus the DN of the respective solvents
in Fig. 1. The mmax values decrease nearly linearly with
the increasing DNs of solvents. This originates in var-
iation of the Lewis acid–base interaction between the
chelate ion and the respective solvent molecule; since
the dxy, dyz and dzx orbitals of the Cu(II) ion will

A. Camard et al. / Inorganica Chimica Acta 358 (2005) 409–414
411
Table 1
The mmax (·103cmꢀ1) values of d–d transition bands of [Cu(trop/hino)(tmen)]B(C6H5)4 in various solventsa
Solvent
DN
[Cu(trop)(tmen)]B(C6H5)4
[Cu(hino)(tmen)]B(C6H5)4
[Cu(acac)(tmen)]B(C6H5)4
19.98
1,2-Dichloroethane
Nitromethane
Nitrobenzene
1,4-Dioxane
0
2.7
20.33 (18.23)
19.80 (18.69)
19.42
20.28 (18.38)
19.69 (18.52)
19.23
4.4
10.8
14.1
16.1
17.0
18.5
19.1
20.0
22.0
26.6
27.8
29.8
33.1
38.8
19.23
17.09 (16.98)
17.04
18.69 (16.53)
17.09 (17.04)
16.98
18.90
17.51
Acetonitrile
Propionitrile
Acetone
Ethanol
17.30 (17.27)
16.67 (16.63)
16.75 (16.67)
17.76
17.24 (17.33)
16.72 (16.72)
16.72 (16.72)
17.24
17.71
17.09
17.06
17.33
Methanol
Tetrahydrofurane
1-n-Butanol
16.72
16.58 (16.34)
16.21
16.81
16.53 (16.31)
16.29
N,N-dimethylformamide
N,N-dimethylacetamide
Dimethylsulfoxide
Pyridine
16.61
16.54
16.33
16.58
15.68
16.31 (15.95)
14.45 (14.94)
14.18
16.26 (16.03)
14.49 (14.97)
13.99
Hexamethylphosphorous triamide
a
The results of [Cu(acac)(tmen)]B(C6H5)4 are also given for comparison. The mmax (·103 cmꢀ1) values of the corresponding perchlorates are in
parentheses. The measurements of perchlorates were carried out in single solvent.
21
same anomaly was formerly found in the case of the
[Cu(acac)(tmen)]ClO4-type chelates [10] and was
shown to be due to remarkable ion-pair formation
in the former solvent. If the coordinating ability of
anion becomes stronger, the anion will be bound more
tightly to Cu(II) ion instead of solvent molecule.
The extent of the solvatochromic spectral change
may now be expressed by the difference between mmax
values in two solvents of widely different DNs, e.g.,
19
17
D = (mmax dce
)
ꢀ (mmax)py, where dce and py mean 1,2-
dichloroethane and pyridine, respectively. The D values
of [Cu(trop)(tmen)]B(C6H5)4 and [Cu(hino)(tmen)]
B(C6H5)4 are 5.87 and 5.79, respectively, which are lar-
ger than that of the acac chelate. In addition, the mmax
values themselves for both trop and hino chelates are
mostly smaller in weak donor solvents but larger in
stronger donor solvents than those for the acac chelate.
It is found, from the linear relationship of the mmax val-
ues with DN, the larger D values and the poorer donor
ability of B(C6H5)4ꢀ ion, that the trop and hino chelates
can be used as excellent Lewis basicity indicators in
solution.
15
13
0
10
20
30
40
DN
Fig. 1. Relationship between the mmax values of the d–d transition
bands of [Cu(trop)(tmen)]B(C6H5)4 (—, s) and [Cu(hino)-
(tmen)]B(C6H5)4 (---, n) in various solvents and the donor number
of the respective solvents. The results of the corresponding acac
analog, [Cu(acac)(tmen)]B(C6H5)4, (ꢁ ꢁ ꢁ, h) are given in comparison.
3.2. Effects of various anions
Table 2(a) and (b) summarize the mmax values of [Cu
(trop)(tmen)]B(C6H5)4 and [Cu(hino)(tmen)]B(C6H5)4
in various solvents and in the presence of various ani-
ons. In Fig. 2(a) and (b), they are also plotted for each
donor solvent versus the mmax values in 1,2-dichloro-
ethane (mmax(dce)), namely the mmax values of the column
of left-end in the respective tables on the abscissa; for
example, a coordinate of (20.00, 16.89) is given for [Cu-
(trop)(tmen)]B(C6H5)4 in acetonitrile in the presence of
all be lifted up by its interaction with polar solvent
molecules approaching from above and below the che-
late plane, the broad d–d transition band will be
shifted to lower energy region. The exceptions to this
rule are found in the case of 1,2-dichloroethane for
the perchlorates [9], as shown in Table 1. The mmax
values in 1,2-dichloroethane (DN = 0) are notably
lower than those in nitromethane (DN = 2.7). The
ꢀ
BF4 ion. The addition of anions results in a similar
effect on the spectra of both chelates. In high donor

412
A. Camard et al. / Inorganica Chimica Acta 358 (2005) 409–414
Table 2
The mmax (103 cmꢀ1) values of d–d transition bands of [Cu(trop)(tmen)]B(C6H5)4 (a) and [Cu(hino)(tmen)]B(C6H5)4 (b) in various solvents in the
presence of various anionsa
dce
nm
an
ac
etoh
thf
dmf
dmso
(a) [Cu(trop)(tmen)]B(C6H5)4
BðC6H5Þ ꢀ
20.33
20.00
19.76
18.98
17.95
16.64
14.88
14.71
19.80
19.84
19.84
19.78
18.02
16.37
14.71
14.29
17.09
16.89
16.69
16.67
17.08
16.53
14.45
14.29
17.67
17.67
17.67
17.67
17.79
17.18
14.45
14.35
16.39
16.42
16.37
16.31
16.37
16.37
16.34
16.18
17.76
17.70
17.70
17.70
17.67
16.98
14.51
14.45
16.10
16.10
16.10
16.10
16.10
16.10
14.71
14.43
16.13
16.13
16.13
16.13
16.13
15.67
16.13
16.10
4
ꢀ
BF4
ClO4
ꢀ
2ꢀ
CO3
CF3SO3
ꢀ
CH3COOꢀ
Brꢀ
Clꢀ
(b) [Cu(hino)(tmen)]B(C6H5)4
BðC6H5Þ ꢀ
20.62
20.16
19.92
18.32
17.79
16.56
14.25
14.14
19.69
19.69
19.65
18.32
17.86
16.50
14.37
14.22
17.67
17.57
17.57
17.64
17.36
16.81
14.53
14.10
17.89
18.02
17.73
17.95
17.64
16.69
14.39
14.14
16.53
16.47
16.47
16.47
16.47
16.47
16.10
16.00
17.79
17.79
17.79
17.70
17.64
16.75
14.35
14.14
16.23
16.23
16.23
16.18
16.23
16.00
14.35
14.14
16.26
15.92
15.95
15.95
16.05
16.00
14.35
14.14
4
ꢀ
BF4
ClO4
ꢀ
2ꢀ
CO3
CF3SO3
ꢀ
CH3COOꢀ
Brꢀ
Clꢀ
a
Abbreviations of solvents are as follows: dce, 1,2-dichloroethane; nm, nitromethane; an, acetonitrile; ac, acetone; etoh, ethanol; thf, tetra-
hydrofurane; dmf, N,N-dimethylformamide; dmso, dimethylsulfoxide.
solvents such as dimethylsulfoxide and dimethylforma-
mide, no variation or only a weak shift of the mmax(solv)
values is observed; the plot approximately follows an
horizontal line. In the lowest donor solvent (1,2-
dichloroethane), a continuous linearly ascending plot
is obtained. The spectra in solvents of intermediate
donor strength give discontinuous plots composed of a
plateau at larger mmax(dce) values and an ascending part
at lower ones with an inclination similar to that
observed for 1,2-dichloroethane solutions.
The interactions of both chelates with the anions
added depend upon the donor and acceptor properties
of the solvents; when the donor strength of the solvent
is higher than that of the anion, the solvent molecule
preferably coordinates to Cu(II) ion, while a solvent
exhibiting strong acceptor properties will preferentially
solvate the anion, preventing coordination of the anion
to Cu(II) ion. The mmax(solv) values remain constant in
the region of the anions with weaker donor strength.
In such ‘‘the solvent-governed’’ region, the constant
to metal. On the basis of the many mmax values published
to describe solvatochromism, the solution behaviors of
Lewis basicity indicators introduced in the present study
and the consideration of the donor and acceptor num-
bers of the solvents and the donor numbers of anions
[11], it is possible to predict the coordination mode of
the chelate. The coordination of any anion Aꢀ is possi-
ble within a space room defined by DN(anion) >
DN(solvent) and AN(solvent) < 40. Outside the room
space permitting the coordination of anion, both chelate
and anion will be solvated.
3.3. Molecular structures of the trop chelates
Instead of naked unsolvated [Cu(trop)(tmen)]-
B(C6H5)4, single crystals of the solvated species
[Cu(trop)(tmen)(dce)]B(C6H5)4 and [Cu(trop)(tmen)
(ac)]B(C6H5)4 were obtained, where dce is 1,2-dichloro-
ethane and ac is acetone. The existence of the solvated
species was the evidence of weak ligand field strength
of the mixed chelates, and then the studied chelates were
more sensitive as the color indicator for Lewis basicities
of solvent and anion. Both solvated chelates crystallize
in the monoclinic space group P21/n, but differ signifi-
cantly in their lattice architectures. Their crystallo-
graphic data are given in Section 2; selected bond
lengths and angles are presented in Table 3, and struc-
tural views are shown in Fig. 4. Copper(II) ion exhibits
in both compounds slightly twisted square planar coor-
dinations by two tropolone oxygen atoms and two
diamine nitrogen atoms with bond lengths and bond an-
gles comparable to [Cu(trop)2], [Cu(en)(1,3-diketo-
nates)](en = 1,2-ethanediamine) and related complexes
m
max(solv) values refer to the spectra of solvated [Cu
(trop/hino)(tmen)]+ and thus reflect the donor number
of the solvent. Enhancing the donor properties of the
anions leads to a point where the anions coordinate sig-
nificantly to [Cu(trop/hino)(tmen)]+, so that further
enhancement in the donor strength of the anions leads
to decreasing ‘‘anion-governed’’ shift of mmax(solv) as
same as the shifts observed for 1,2-dichloroethane solu-
tions. The donor properties of the solvent and those of
the anion become equal at the intersection point of the
‘‘solvent-governed’’ and ‘‘anion-governed’’ regions.
Fig. 3 offers a quantitative view of the competition
between solvent molecule and anion for coordination

A. Camard et al. / Inorganica Chimica Acta 358 (2005) 409–414
413
(a)
20
18
S
+
+
100
90
N
O
+
-
[A ]
Cu
S
O
N
80
70
60
50
40
S
+
ANSolv
A
N
O
Cu
S
30
20
10
O
100
N
N
O
90
80
70
60
50
40
30
20
10
Cu
O
N
+
-
[A ]
16
14
0
DNSolv
90
80
70
60
50
40
30
20
0
10
DNX-,Solv
0
14
16
18
(dce)/103 cm-1
20
Fig. 3. A view of competition between solvent molecule and anion for
coordination to metal.
ν
max
p-stacked with their trop residues in Ci-related antipar-
allel pairs, thus mutually blocking the access to CuO2N2
moiety on one side, whereas on the opposite side, i.e., in
(b)
20
18
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) for (a) [Cu(trop)(tmen)-
(dce)]B(C6H5)4 and (b) [Cu(trop)(tmen)(ac)]B(C6H5)4
(a)
(b)
Cu–O(2)
Cu–O(1)
Cu–N(1)
Cu–N(2)
[Cu–Cl(1)
Cu–O(3)
1.925(1)
1.931(1)
2.007(1)
2.017(1)
3.580(1)]
1.918(2)
1.930(2)
2.004(2)
2.004(2)
16
14
2.502(2)
O(1)–Cu–O(2)
O(1)–Cu–N(1)
O(1)–Cu–N(2)
O(2)–Cu–N(1)
O(2)–Cu–N(2)
N(1)–Cu–N(2)
84.01(4)
94.16(4)
171.94(5)
174.43(5)
95.04(4)
87.50(5)
83.16(7)
95.12(8)
170.70(9)
175.21(8)
93.74(7)
87.27(9)
14
16
18
20
ν
(dce)/103 cm-1
max
Fig. 2. (a) The mmax values of [Cu(trop)(tmen)]B(C6H5)4 in 1,2-
dichloroethane containing various anions dissolved in various donor
solvents; dichloroethane ( ), nitromethane (s), acetonitrile (m),
acetone (n), ethanol ( ), tetrahydrofurane (h), dimethylformamide
ꢃ
men)]B(C6H5)4 in 1,2-dichloroethane containing various anions dis-
O(1)–C(1)
O(2)–C(7)
C(1)–C(2)
C(1)–C(7)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
C(8)–C(9)
N(1)–C(8)
N(1)–C(10)
N(1)–C(11)
N(2)–C(9)
N(2)–C(12)
N(2)–C(13)
Cl(1)–C(38)
C(38)–C(39)
Cl(2)–C(39)
O(3)–C(14)
C(14)–C(15)
C(14)–C(16)
1.305(2)
1.300(2)
1.405(2)
1.474(2)
1.395(2)
1.392(2)
1.394(2)
1.392(2)
1.409(2)
1.510(2)
1.503(2)
1.483(2)
1.484(4)
1.488(2)
1.495(2)
1.490(2)
1.805(2)
1.499(3)
1.788(2)
1.279(3)
1.288(3)
1.399(3)
1.457(3)
1.370(4)
1.368(4)
1.369(4)
1.391(4)
1.392(3)
1.343(5)
1.435(4)
1.455(5)
1.448(4)
1.481(4)
1.463(4)
1.480(4)
n
(e) and dimethylsulfoxide (¤). (b) The mmax values of [Cu(hino)(t-
solved in various donor solvents; dichloroethane ( ), nitromethane
ꢃ
(s), acetonitrile (m), acetone (n), ethanol ( ), tetrahydrofurane (h),
n
dimethylformamide (e) and dimethylsulfoxide (¤).
[12–16]. In [Cu(trop)(tmen)(dce)]B(C6H5)4, which has
the stronger twisted CuO2N2 coordination figure
˚
˚
(r.m.s. aplanarity 0.101 A, Cu 0.020 A off l.s. plane),
there is one very weak axial interaction with Cl(1) of a
˚
dce molecule, Cu–Cl(1) = 3.580 A, whereas the opposite
side of the CuO2N2 moiety is shielded by a remote
˚
B(C6H5)4 phenyl ring. This Cu–Cl interaction is ꢂ1 A
longer than cases with a clear-cut axial Cu–Cl bond as
encountered in compounds reported [17,18]. A distinctly
different situation is encountered in [Cu(trop)(tmen)-
(ac)]B(C6H5)4: here two [Cu(trop)(tmen)(ac)] units are
1.186(4)
1.463(6)
1.489(5)

414
A. Camard et al. / Inorganica Chimica Acta 358 (2005) 409–414
4. Supplementary material
(a)
CCDC-187873 and 187874 contain the supplemen-
tary crystallographic data for this paper. These data
can be obtained free of charge via www.ccdc.cam.
ac.uk/data_request/cif, by emailing data_request@ccdc.
cam.ac.uk, or by contacting The Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge
CB2 1EZ, UK; fax: +44 1223 336033.
Acknowledgments
Thanks for financial support are due to the ’’Fonds zur
¨
Fo¨rderung der Wissenschaftlichen Forschung in Osterre-
ich’’ (Project 15874-N03) and to the ‘‘Jubila¨umsfonds’’ of
the Austrian National Bank (Project 10668) as well as to
the JSPS supporting the stay of W.L. in Japan.
(b)
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˚
˚
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