CuII complexes of isomeric ligands derived from 2-pyridine-carboxaldehyde and m- or p-xylylenediamine: An intermolecularly- stacked dinuclear species and a trinuclear circular helicate that encapsulates a chloride ion

Article abstract of DOI:10.1071/CH12368

Di- and trinuclear Cu^II complexes [Cu₂L ¹(2,2′-bipyridine)₂Cl₂]Cl ₂·11H₂O and [Cu₃(L²) ₃Cl₃]Cl₃·1.25MeOH·4H ₂O i

Full text of DOI:10.1071/CH12368

RESEARCH FRONT
CSIRO PUBLISHING
Aust. J. Chem. 2012, 65, 1587–1593
Full Paper
http://dx.doi.org/10.1071/CH12368
CuII Complexes of Isomeric Ligands Derived from
2-Pyridine-carboxaldehyde and m- or p-Xylylenediamine:
An Intermolecularly p-Stacked Dinuclear Species
and a Trinuclear Circular Helicate that Encapsulates
a Chloride Ion
A
A
A
A
Young Hoon Lee, Arim Woo, Mi Seon Won, Jeong Hwan Cho,
B
C
D
E
Jack K. Clegg, Shinya Hayami, Pierre Thue´ry, Leonard F. Lindoy,
A F
,
and Yang Kim
A
Department of Chemistry & Advanced Materials, Kosin University, 194,
Wachi-Ro, Yeongdo-gu, Busan 606-701, South Korea.
B
School of Chemistry and Molecular Biosciences, The University of Queensland,
St Lucia, Brisbane, Qld 4072, Australia.
C
Department of Chemistry, Graduate School of Science and Technology,
Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
D
CEA, IRAMIS, UMR 3299 CEA/CNRS, SIS2M, LCCEf, Baˆt.125,
91191 Gif-sur-Yvette, France.
E
School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.
Corresponding author. Email: ykim@kosin.ac.kr
F
Di- and trinuclear CuII complexes [Cu2L1(2,20-bipyridine)2Cl2]Cl2ꢀ11H2O and [Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O
incorporating the isomeric Schiff base ligands 1,10-(1,4-phenylene)bis(N-(pyridin-2-ylmethylene)methanamine) (L1)
and 1,10-(1,4-phenylene)bis(N-(pyridin-2-ylmethylene)methanamine) (L2), each incorporating two separated a-diimine
coordination domains, have been synthesised and their X-ray crystal structures and variable temperature magnetic
properties determined. The X-ray crystal structure of [Cu2L1(2,20-bipyridine)2Cl2]Cl2ꢀ11H2O shows that each CuII centre
is bound to two nitrogen atoms from L1, two from a bipyridine ligand, and a chloride anion. Intramolecular p-stacking
interactions are present between the central phenyl ring of L1 and both rings of each bipyridine ligand. The structure of
[Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O shows an unusual trinuclear circular helicate arrangement with approximate
C3-symmetry. A chloride anion is encapsulated in the structure being bound by six non-classical hydrogen bond
interactions. Variable temperature magnetic susceptibility measurements indicated the presence of weak antiferro-
magnetic behaviour for [Cu2L1(2,20-bipyridine)2Cl2]Cl2ꢀ11H2O and weak ferromagnetic behaviour for [Cu3(L2)3Cl3]Cl3ꢀ
1.25MeOHꢀ4H2O.
Manuscript received: 4 August 2012.
Manuscript accepted: 7 September 2012.
Published online: 31 October 2012.
often unusual metallosupramolecular architectures.[9] As
expected, such ligand species act as bis-bidentate ligands that
favour the formation of di-, oligo-, or polynuclear species. The
structures and magnetic properties of transition metal com-
plexes of the above ligand types continue to be of significant
interest, in part motivated by the desire to obtain new functional
materials.[10]
Isolated metal complex studies involving the isomeric
bis-bidentate ligands L1 and L2 (Chart 1), differing only in the
substitution positions on the central xylylene bridge, have
previously resulted in complexes exhibiting a range of
topologies.[11–14] However no reports of the interaction of
either ligand with CuII have appeared, although an investigation
Introduction
Ligands incorporating a-diimine coordination domains,
including such classical ligands as 1,10-phenanthroline, 2,20-
bipyridine, and their derivatives,[1] have long been known to be
versatile coordinating agents that form robust complexes with a
wide range of transition and post-transition metal ions. Also
representative of this ligand category are unsymmetrical
a-diimine derivatives of type 1, and, for example, 1 (R ¼ CH3)
(Chart 1) has been shown to form stable complexes with FeII,[2]
CoII,[3] NiII,[3–5] ZnII,[6] RuII,[7] and PtII.[8] Over recent years
extended ligands incorporating two such a-diimine coordination
domains separated by spacer groups have received increasing
attention for use as building blocks in the assembly of a range of
Journal compilation Ó CSIRO 2012
www.publish.csiro.au/journals/ajc

1588
Y. H. Lee et al.
of the interaction of CuI, AgI, CuII, and NiII with the analogue
of L2 derived from 6-methylpyridine-2-carboxaldehyde and
m-xylylenediamineamine has appeared.[15] As an extension
of these studies we now report the results of an investigation
of the interaction of L1 and L2 with CuII. A motivation for
this study was to probe the possibility of generating new
low-dimensional CuII supramolecular architectures and,
where possible, to probe their structure–function relation-
ships with the aid of X-ray and variable temperature magnetic
studies.
Results and Discussion
In an initial study, reaction of CuII chloride with L1 in THF in a
1 : 1 ratio resulted in a pale green powder whose microanalysis
and mass spectrum were in accord with a stoichiometry of
Cu2L1Cl4ꢀ0.5THF for this product. However, several attempts to
obtain suitable crystals of this complex for X-ray analysis by
slow recrystallisation from methanol/water or THF/water were
unsuccessful and hence no detailed structure of this complex
was obtained. A structure in which a CuII ion is bound to each
diimine domain seems likely with square planar coordination
being achieved by chloro ligands occupying the remaining
positions on each copper centre. However, the presence of
bridging chloro groups to give each copper centre a five or six
coordinate geometry cannot be ruled out.
R
N
N
In an attempt to obtain suitable crystals of a related mixed-
ligand complex derivative, the reaction was repeated in the
presence of a 1 : 1 molar ratio of Cu to 2,20-bipyridine.[16] Under
these conditions a greenish blue precipitate readily formed. The
microanalysis and electrospray ionisation mass spectrometry
(ESI-MS) data for this product were in accord with the forma-
tion of a complex of type [Cu2L1(bipyridine)2Cl2]Cl2ꢀ3H2O and
recrystallisation of this product from water yielded blue crystals
of [Cu2L1(bipyridine)2Cl2]Cl2ꢀ11H2O that were suitable for
X-ray structure determination.
The asymmetric unit in the structure of [Cu2L1(bipyridine)2
Cl2]Cl2ꢀ11H2O (Fig. 1) contains one dinuclear dicationic com-
plex, the charge being balanced by two uncomplexed chloride
ions. Each CuII ion is bound to two nitrogen atoms from the
ligand L1, two from the bipyridine ligand, and a chloride
anion. All of the bond lengths are typical.[17] The two chelating
ligands around each copper are not far from being orientated
1
N
N
N
N
2 (L1)
N
N
N
N
3 (L2)
Chart 1.
N(1)
Cl(1)
N(2)
Cu(1)
N(5)
N(6)
N(7)
Cl(2)
N(8)
Cu(2)
N(3)
N(4)
Fig. 1. View of the cation in [Cu2L1(bipyridine)2Cl2]Cl2ꢀ11H2O. Displacement ellipsoids are drawn at the 50 %
˚
probability level. Selected bond lengths (A) and angles (deg.): Cu(1)–N(1) 1.990(7); Cu(1)–N(2) 2.150(7); Cu(1)–N(5)
2.047(7); Cu(1)–N(6) 1.988(7); Cu(1)–Cl(1) 2.311(3); Cu(2)–N(3) 2.096(8); Cu(2)–N(4) 2.012(7); Cu(2)–N(7)
2.089(7); Cu(2)–N(8) 1.959(7); Cu(2)–Cl(2) 2.316(3); N(1)–Cu(1)–N(2) 80.3(3) N(5)–Cu(1)–N(6) 80.3(3);
N(1)–Cu(1)–N(5) 92.6(3); N(1)–Cu(1)–N(6) 172.9(3); N(2)–Cu(1)–N(5) 102.4(3); N(2)–Cu(1)–N(6) 102.4(3);
N(1)–Cu(1)–Cl(1) 91.8(2); N(2)–Cu(1)–Cl(1) 105.1(2); N(5)–Cu(1)–Cl(1) 152.5(2); N(6)–Cu(1)–Cl(1) 93.8(2);
N(3)–Cu(2)–N(4) 79.9(3); N(7)–Cu(2)–N(8) 80.5(3); N(3)–Cu(2)–N(7) 111.5(3); N(3)–Cu(2)–N(8) 96.8(3);
N(4)–Cu(2)–N(7) 99.5(3); N(4)–Cu(2)–N(8) 176.5(3); N(3)–Cu(2)–Cl(2) 129.0(2); N(4)–Cu(2)–Cl(2) 91.9(2);
N(7)–Cu(2)–Cl(2) 119.6(2); N(8)–Cu(2)–Cl(2) 91.2(2).

CuII Complexes of Isomeric Ligands
1589
orthogonally, with dihedral angles of 80.7(2)8 and 70.1(2)8
between the bipyridine molecule and the terminal parts of the
L1 ligand. The coordination environment around Cu(1) is
approximately square pyramidal (t ¼ 0.34),[18] with N(2) in
The reaction of L2 with copper(II) chloride in methanol give
a greenish-blue precipitate of composition [Cu3(L2)3Cl3]
Cl3ꢀ9H2O. Slow diffusion of diethyl ether in a methanol
solution of this product yielded crystals of [Cu3(L2)3Cl3]
Cl3ꢀ1.25MeOHꢀ4H2O suitable for diffraction studies. The
resulting structure (Fig. 2) reveals that the complex takes the
form of an unusual trinuclear circular helicate with approxi-
mate C3-symmetry. Each complex is thus chiral with both
enantiomers present in the crystal lattice. The three CuII
centres are arranged in an almost equilateral triangle (Cu–Cu
the axial position, while that around Cu(2) is closer to trigonal
[18]
bipyramidal (t ¼ 0.79);
where t ¼ 0 for a fully tetragonal
geometry and t ¼ 1 for a fully trigonal bipyramidal geometry.
Several intermolecular p-stacking interactions are present
between adjacent bipyridine groups and adjacent pyridyl rings
˚
with centroidꢀꢀꢀcentroid distances as short as 3.56 A. Also
˚
present are a series of strong offset face-to-face intramolecular
interactions between the comparatively electron-rich central
phenyl ring of L1 and the comparatively electron poor bipyridine
groups, with carbon-1 and carbon-10 of the bipyridine groups to
distances are 8.31, 8.37, and 8.46 A) and are bridged by three
L2 ligands. The remaining charge is balanced by three
uncoordinated chloride ions and there are several disordered
water and methanol molecules in the lattice. Like [Cu2L1
(bipyridine)2Cl2]Cl2ꢀ11H2O, each copper centre is also bound
to a chloride anion resulting in five-coordinate geometries and
an N4Cl coordination sphere with unremarkable bond lengths.
Cu(1) and Cu(2) are close to trigonal bipyramidal (t ¼ 0.60
˚
the phenyl centroid distances in the range 3.25–3.55 A and
bipyridine–phenylene dihedral angles in the range 4.78–7.28.
These interactions likely contribute to the stability of the
observed structure.
CI(2)
N(4)
N(6)
Cu(2)
N(3)
N(5)
CI(3)
N(12)
N(7)
Cu(3)
N(8)
N(11)
N(10)
N(2)
N(9)
Cu(1)
Cl(1)
N(1)
Fig. 2. View of the cation in [Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O. Displacement ellipsoids are drawn at the 50 %
˚
probability level. Selected bond lengths (A) and angles (deg.): N(1)–Cu(1) 1.990(3); N(2)–Cu(1) 2.085(2); N(3)–
Cu(2) 2.142(2); N(4)–Cu(2) 1.985(2); N(5)–Cu(2) 1.994(2); N(6)–Cu(2) 2.110(2); N(7)–Cu(3) 2.201(2); N(8)–
Cu(3) 2.005(2); N(9)–Cu(1) 1.989(2); N(10)–Cu(1) 2.155(3); N(11)–Cu(3) 2.072(2); N(12)–Cu(3) 1.994(2);
Cl(1)–Cu(1) 2.2899(8); Cl(2)–Cu(2) 2.2850(7); Cl(3)–Cu(3) 2.2402(8); N(9)–Cu(1)–N(1) 176.59(11); N(9)–
Cu(1)–N(2) 96.81(10); N(1)–Cu(1)–N(2) 79.79(10); N(9)–Cu(1)–N(10) 79.54(10); N(1)–Cu(1)–N(10) 100.96
(10); N(2)–Cu(1)–N(10) 104.91(9); N(9)–Cu(1)–Cl(1) 90.67(7); N(1)–Cu(1)–Cl(1) 92.05(7); N(2)–Cu(1)–Cl(1)
136.93(7); N(10)–Cu(1)–Cl(1) 118.16(7); N(4)–Cu(2)–N(5) 176.96(9); N(4)–Cu(2)–N(6) 97.48(9); N(5)–Cu(2)–
N(6) 80.13(9); N(4)–Cu(2)–N(3) 79.96(9); N(5)–Cu(2)–N(3) 98.53(9); N(6)–Cu(2)–N(3) 100.07(8); N(4)–Cu(2)–
Cl(2) 91.21(7); N(5)–Cu(2)–Cl(2) 91.80(7); N(6)–Cu(2)–Cl(2) 132.77(6); N(3)–Cu(2)–Cl(2) 127.16(6); N(12)–
Cu(3)–N(8) 175.63(10); N(12)–Cu(3)–N(11) 80.38(10); N(8)–Cu(3)–N(11) 95.39(9); N(12)–Cu(3)–N(7)
100.63(9); N(8)–Cu(3)–N(7) 78.90(9); N(11)–Cu(3)–N(7) 99.71(9); N(12)–Cu(3)–Cl(3) 94.56(7); N(8)–Cu(3)–
Cl(3) 89.63(7); N(11)–Cu(3)–Cl(3) 148.51(7); N(7)–Cu(3)–Cl(3) 111.75(7).

1590
Y. H. Lee et al.
2.0
1.5
1.0
0.5
0
0
100
200
300
Temperature [K]
Fig. 4. The xmT versus temperature curves for [Cu2L1(2,20-
bipyridine)2Cl2]Cl2ꢀ3H2O (bottom) and [Cu3(L2)3Cl3]Cl3ꢀ9H2O (top).
Fig. 3. Schematic representation of the crystal structure of [Cu3(L2)3Cl3]
Cl3ꢀ1.25MeOHꢀ4H2O. Dashed lines indicate CHꢀꢀꢀClꢁ interactions.
In contrast to [Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O, in this
complex the structure remains relatively flat and resembles
a triangular disk.
and 0.74, respectively) while Cu(3) is closer to square based
pyramidal (t ¼ 0.46).
Magnetic Studies
The ligands are arranged such that there is a central cavity
present in the circular helicate structure resulting in a bowl-
shaped arrangement, in part stabilised by p–p interactions. The
p–p interactions include weak offset face-to-face pyridyl–
phenyl stacking (indicated by centroid–centroid distances of
The temperature dependences (2–300 K) of the magnetic sus-
ceptibilities of the microcrystalline samples of [Cu2L1(2,20-
bipyridine)2Cl2]Cl2ꢀ3H2O and [Cu3(L2)3Cl3]Cl3ꢀ9H2O were
measured at 5000 Oe, and the data are expressed by xmT versus
T plots in Fig. 4, where xm is the molar magnetic susceptibility
and T is the temperature. The xmT value of the former dinuclear
complex at 300 K is 0.894 cm3 K molꢁ1; the value is close to the
theoretical value of 0.75 cm3 K molꢁ1 for a two-spin system. On
cooling, the xmT value decreases and reaches 0.850 cm3 K molꢁ1
at 10 K. On further cooling, the xmT value drops dramatically
to 0.669 cm3 K molꢁ1 at 2 K, with the decrease of the xmT
value below 10 K being assigned to zero-field splitting. The
data xm versus T were fitted to the Bleaney–Bowers Equation
˚
4.1–4.2 A) and stronger imine–phenyl interactions (indicated by
˚
imine–phenyl centroid separations of 3.4–3.5 A). The central
cavity is lined with inward facing hydrogen atoms. Located in
the cavity is a chloride anion, which is stabilised by six strong
non-classical hydrogen bonding interactions (Fig. 3) indicateꢁd
by CHphenylene–Clꢁ distances of 2.75–2.88 A and CH2–Cl
˚
˚
distances of 2.77–2.90 A. Thus the complex could be described
as [Cl ꢂ {Cu3(L2)3Cl3}]2þ. The encapsulated chloride is further
stabilised by three anion–electron deficient p (coordinated
pyridyl) contacts with pyridyl centroid–Clꢁ distances of 3.8–
(Eqn 1) (H ¼ ꢁ2JS1ꢀS2)[20] (Fig. 4).
ˆ
ˆ
"
#
˚
4.4 A. A solvent water molecule also acts as a hydrogen
bond donor to the encapsulated chloride further stabilising
Nb2g2
kT
2
wm
¼
þ Na
ð1Þ
2J
kT
3 þ expðꢁ
Þ
˚
the arrangement (O(1W)ꢀꢀꢀCl(4) ¼ 3.141(3) A, 179(4)8). This
almost spherical array of stabilising interactions is reminiscent
of those observed in other anion-binding circular helicate
structures;[9a,19] however, unlike the latter, the present structure
has the chloride ion positioned just out of the plane defined by
the metal centres.
In Eqn 1, 2J is the singlet–triplet splitting and Na is the
temperature-independent paramagnetism. The parameters giv-
ing the best fit were obtained using a non-linear regression
analysis with g, J, and b as variables and Na fixed at 60 ꢃ
10ꢁ6 cm3 molꢁ1. The solid line in Fig. 4 represents the best-fit
situation with g ¼ 2.09 and 2J ¼ ꢁ1.2 cmꢁ1; in accord with a
weak antiferromagnetic interaction operating intramolecularly.
With respect to the above it is noted that a related trinuclear
CuII complex of type [Cu3(L)3(OAc)3][PF6]3, where L is the
Schiff base analogue of L2 derived from condensation of
6-methylpyridine-2-carboxaldehyde and m-xylylenediamineamine
in a 2 : 1 molar ratio, has been reported.[15] The copper centres
˚
The CuꢀꢀꢀCu distance is 8.7 A, and usually there is no magnetic
interaction between CuII ions for such a distance. However, in
this case, we considered the possibility of magnetic interaction
because of the strong intramolecular p–p interactions present.
˚
form a triangle and are separated by 8.89 A, with each copper
centre adopting a distorted square pyramidal geometry. Each
CuII ion is bound to two bidentate pyridyl–imine sites with the
remaining coordination site filled by a monodentate acetato
ligand. The Schiff base ligands are ‘wrapped around’ the
CuꢀꢀꢀCu vectors to yield a circular helicate arrangement.
˚
As mentioned above, these p–p interactions (3.25 A) occur
between the phenyl ring in L1 and the 2,20-bipyridine fragments;
our results are in accord with the observed (weak) interaction
occurring through this p–p stacking.

CuII Complexes of Isomeric Ligands
1591
The xmT value for the trinuclear complex [Cu3(L2)3Cl3]
Cl3ꢀ9H2O at 300 K is equal to 0.969 cm3 K molꢁ1 and this value
is close to the theoretical value of 1.125 cm3 K molꢁ1 for a three-
spin system (Fig. 4). On cooling, the xmT value decreases and
reaches 1.273 cm3 K molꢁ1 at 10 K. On further cooling, the xmT
value again drops rapidly to 0.997 cm3 K molꢁ1 at 2 K, with the
decrease in the xmT value below 10 K again being assigned to
zero-field splitting. The CuꢀꢀꢀCu distances for this trinuclear
overnight. The off-white precipitate that formed was filtered
off, washed sparingly with methanol, and then dried in air; yield,
8.9 g (57 %). Anal. Calc. for C20H18N4: C 76.41, H 5.77,
N 17.82. Found: C 76.20, H 5.80, N 18.0 %. m/z (ESI, positive
ion mode, MeCN) 315.16 ([M þ H]þ), 337.14 ([M þ Na]þ).
L2 was prepared by a similar procedure to that reported
previously.[12] 2-Pyridine-carboxaldehyde (1.6 g, 2 equiv.) in
hot methanol (5 mL) was added to m-xylylenediamine
(1.0 g, 1 equiv.) in hot methanol (15) mL and the mixture was
heated at reflux for 30 min. The volume was reduced to 15 mL
and the solution placed in a refrigerator to yield an off-white
product. Yield, 1.30 g (56 %). The product was recrystallised
from a dichloromethane/hexane mixture. Anal. Calc. for
C20H18N4: C 76.41, H 5.77, N 17.82. Found: C 76.30, H 5.66,
N 17.90 %. m/z (ESI, positive ion mode, MeCN) 315.16
([M þ H]þ), 337.33 ([M þ Na]þ).
˚
complex are 8.31, 8.37, and 8.46 A, and, as mentioned for the
previous complex, usually such extended distances do not give
rise to magnetic interactions between adjacent CuII centres.
However, once again in this complex there are strong intra-
molecular p–p interactions present between phenyl rings,
pyridine rings, and the Schiff-base imines which could provide
an interaction pathway between metal centres. As mentioned
earlier, the trinuclear structure of [Cu3(L2)3Cl3]Cl3ꢀ9H2O is
close to regular triangular and, for a such a system consisting
of three spins, xm is given by Eqn 2.
Cu2L1Cl4ꢀ0.5THF
CuCl2ꢀ2H2O (0.11 g) in warm THF (10 mL) was added to a
warm stirred solution of L1 (0.10 g) in THF (10 mL) and on
standing a green precipitate formed which was separated by
filtration and dried in air. Yield 0.15 g. Anal. Calc. for
C20H18N4Cu2Cl4ꢀ0.5C4H8O: C 42.66, H 3.58, N 9.05. Found:
"
#
Nb2g2
kT
3J
1 þ 5expð Þ
kT
wm
¼
þ Na
ð2Þ
3J
1 þ expðꢁ
Þ
kT
The solid line in Fig. 4 represents the best-fit situation with
g ¼ 2.10 and 2J ¼ þ1.5 cmꢁ1 thus being in accord with a weak
intramolecular ferromagnetic interaction being present between
the CuII centres.
C 42.70, H 3.83, N 9.11 %. lmax (H2O/nm) (e/Mꢁ1 cmꢁ1
)
720 (42). ESI-MS m/z (ESI, positive ion mode, MeCN) 412.05
([Cu þ L1 þ Cl]þ). Attempts to grow suitable crystals of this
product from water/methanol and water/THF for an X-ray
structure determination were unsuccessful.
Conclusion
[Cu2L1(bipyridine)2Cl2]Cl2ꢀ3H2O
The X-ray structures of two CuII complexes of the isomeric bis-
a-diimine ligands derived from 2-pyridine-carboxaldehyde and
m- or p-xylylenediamine are reported along with their variable
temperature magnetic behaviour. The dinuclear complex is
weakly antiferromagnetic in contrast to the trinuclear complex
which is weakly ferromagnetic. Both structures show unusual
features. [Cu2L1(2,20-bipyridine)2Cl2]Cl2ꢀ11H2O is an inter-
molecularly (triple) p-stacked dinuclear species while
[Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O is a rare trinuclear circular
helicate that encapsulates a chloride ion within its supra-
molecular structure.
CuCl2ꢀ2H2O (0.17 g) in warm THF (10 mL) was added to a
solution of L1 (0.16 g) and 2,20-bipyridine (0.16 g)) in warm
stirred THF (10 mL). The solution was allowed to cool and on
standing a greenish-blue precipitate formed which was isolated
and dried under vacuum; yield 0.16 g. Anal. Calc. for
C40H40Cl4Cu2N8O3: C 50.59, H 4.25, N 11.80. Found: C 50.80,
H 4.42, N11.80 %. lmax (H2O/nm)(e/Mꢁ1 cmꢁ1) 475sh(16), 725
(99). m/z (ESI, positive ion mode, MeCN) 412.05 ([Cu þ L1 þ
Cl]þ), 568.00 ([Cu þ L1 þ bipyridine þ Cl]þ), 726.00 ([Cu þ
2L1 þ Cl]þ).
The product was dissolved in water (10 mL) and the resulting
solution was allowed to evaporate slowly to yield blue crystals
that proved suitable for X-ray structure determination.
Experimental
All reagents were purchased from Aldrich and used as received.
Electronic absorption spectra were measured with a SCINCO
S-2100 diode array spectrophotometer. Elemental analysis was
performed at the Korea Basic Science Institute (Busan) and the
University of Queensland. The ESI mass spectra were obtained
on a Thermo Scientific LCQ Fleet spectrometer. Crystals used
for X-ray diffraction were stored under the corresponding
reaction solution before mounting on the diffractometer.
Magnetic susceptibilities of ground samples were measured on a
superconducting quantum interference device (SQUID) mag-
netometer (Quantum Design MPMS-5S) under an external field
of 5000 Oe.
[Cu3(L2)3Cl3]Cl3ꢀ9H2O
CuCl2ꢀ2H2O (0.14 g) in methanol (10 mL) was added dropwise
to a solution of L2 (0.25 g) in methanol (10 mL). The mixture
was stirred for 2 h and allowed to cool to give a greenish-blue
precipitate which was removed by filtration and dried in air;
yield 0.26 g. Anal. Calc. for C60H72Cl6Cu3N12O9: C 47.89,
H 4.82, N 11.18. Found: C 47.71, H 5.19, N 11.10 %. lmax (H2O/
nm) (e/Mꢁ1 cmꢁ1) 485 (73), 700 (128). Crystals suitable for
X-ray studies were grown by the slow diffusion of diethyl ether
into a methanol solution of the above product.
Crystallography
Ligand Synthesis
The data for [Cu2L1(bipyridine)2Cl2]Cl2ꢀ11H2O were collected
L1 was prepared by a similar procedure to that described pre-
viously.[12] 2-Pyridine-carboxaldehyde (10.7 g) was slowly
added to p-xylylenediamine (6.8 g) suspended in hot ethanol
(100 mL) and the mixture was stirred overnight and then heated
at ,508C for 2 h. The hot solution was filtered and the filtrate
concentrated to a small volume and placed in a refrigerator
at 171(2) K on a Bruker APEX2 area detector diffractometer[21]
˚
using graphite-monochromated MoKa radiation (l 0.71073 A).
Data for [Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O were collected
using an Oxford Gemini Ultra employing graphite mono-
chromated MoKa radiation generated from a sealed tube

1592
Y. H. Lee et al.
(l 0.71073 A) with v scans at 150(2) K.[22] Absorption effects
were corrected empirically using the programs SADABS[23] or
CryAlisPro.[22] The structures were solved by direct methods
with SHELXS-97[24] or SIR-97,[25] expanded by subsequent
Fourier-difference synthesis, and refined by full-matrix least-
squares on F2 with SHELXL-97.[24] In general non-hydrogen
atoms with occupancies greater than or equal to 0.5 were refined
anisotropically. Carbon-bound hydrogen atoms were included
in idealised positions and refined using a riding model. Oxygen-
bound hydrogen atoms were first located in the difference
Fourier map before refinement with bond length and angle
restraints as required to facilitate realistic modelling, where they
could not be located they were not included in the model.
Crystal data for [Cu2L1(bipyridine)2Cl2]Cl2ꢀ11H2O: Formula
C40H56Cl4Cu2N8O11, M 1093.81, monoclinic, space group
[4] S. Daniele, M. Martelli, G. Bontempelli, Inorg. Chim. Acta 1991, 179,
105. doi:10.1016/S0020-1693(00)85380-3
[5] M. A. Robinson, J. D. Curry, D. H. Busch, Inorg. Chem. 1963, 2, 1178.
doi:10.1021/IC50010A021
[6] M. Schulz, M. Klopfleisch, H. Goerls, M. Kahnes, M. Westerhausen,
Inorg. Chim. Acta 2009, 362, 4706. doi:10.1016/J.ICA.2009.06.044
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doi:10.1021/IC00116A015
[8] V. G. Albano, D. Braga, V. De Felice, A. Panunzi, A. Vitagliano,
Organometallics 1987, 6, 517. doi:10.1021/OM00146A014
[9] (a) See, for example: J.-F. Ayme, J. E. Beves, D. A. Leigh, R. T.
McBurney, K. Rissanen, D. Schultz, Nat. Chem. 2012, 4, 15.
doi:10.1038/NCHEM.1193
˚
(b) W. Meng, B. Breiner, K. Rissanen, J. D. Thoburn, J. K. Clegg, J. R.
Nitschke, Angew. Chem. Int. Ed. 2011, 50, 3479. doi:10.1002/ANIE.
201100193
(c) C. R. K. Glasson, G. V. Meehan, C. A. Motti, J. K. Clegg, P. Turner,
P. Jensen, L. F. Lindoy, Dalton Trans. 2011, 40, 12153 and refs
therein. doi:10.1039/C1DT10820D
(d) R. J. Archer, C. S. Hawes, G. N. L. Jameson, V. McKee,
B. Moubaraki, N. F. Chilton, K. S. Murray, W. Schmitt, P. E. Kruger,
Dalton Trans. 2011, 40, 12368. doi:10.1039/C1DT11381J
(e) C. R. K. Glasson, J. C. McMurtrie, G. V. Meehan, J. K. Clegg,
L. F. Lindoy, C. A. Motti, B. Moubaraki, K. S. Murray, J. D. Cashion,
Chem. Sci. 2011, 2, 540 and refs therein. doi:10.1039/C0SC00523A
(f) H. B. T. Jeazet, K. Gloe, T. Doert, O. N. Kataeva, A. Jager,
G. Geipel, G. Bernhard, B. Buchner, Chem. Commun. 2010, 46, 2373.
doi:10.1039/B925469B
(g) D. Pelleteret, R. Cle´rac, C. Mathonie`re, E. Harte´, W. Schmitt, P. E.
Kruger, Chem. Commun. 2009, 221. doi:10.1039/B816196H
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1697. doi:10.1126/SCIENCE.1175313
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2008, 252, 940. doi:10.1016/J.CCR.2007.10.013
(j) M. Boiocchi, B. Colasson, L. Fabbrizzi, E. Monti, Inorg. Chim. Acta
2007, 360, 1163. doi:10.1016/J.ICA.2006.08.057
(k) K. S. Chichak, S. J. Cantrill, A. R. Pease, S.-H. Chiu, G. W. V.
Cave, J. L. Atwood, J. F. Stoddart, Science 2004, 304, 1308.
doi:10.1126/SCIENCE.1096914
(l) M. J. Hannon, L. J. Childs, Supramol. Chem. 2004, 16, 7 and refs
therein. doi:10.1080/10610270310001632386
˚
P21/c(#14), a 10.0461(2), b 20.9546(4), c 24.1712(5) A,
3
b 98.1366(14)8, V 5037.10(17) A , Dc 1.442 g cmꢁ3, Z 4, crystal
˚
size 0.20 ꢃ 0.18 ꢃ 0.11 mm3, colour blue, habit block, tempera-
ture 171(2) K, l(MoKa) 0.71073 A, m(MoKa) 1.118 mmꢁ1
,
˚
T(SADABS)min,max 0.667, 0.746, 2ymax 51.36, hkl range
ꢁ12 10, ꢁ25 25, ꢁ29 29, N 48888, Nind 9544(Rmerge 0.1288),
Nobs 4440 (I . 2s(I)), Nvar 604, residuals R1(F) 0.0873, wR2(F2)
ꢁ
ꢁ3
.
˚
0.2856, GoF(all) 1.007, Drmin,max ꢁ0.928, 1.516 e A
Crystal data for [Cu3(L2)3Cl3]Cl3ꢀ1.25MeOHꢀ4H2O:
Formula C61.25H67Cl6Cu3N12O5.25, M 1458.59, monoclinic,
space group P21/c(#14), a 21.6463(3), b 12.16246(16),
3
˚
˚
c 25.9717(5) A, b 104.7157(16)8, V 6613.34(17) A , Dc
1.465 g cmꢁ3, Z 4, crystal size 0.5 ꢃ 0.4 ꢃ 0.3 mm3, colour
˚
green, habit block, temperature 150(2) K, l(MoKa) 0.71073 A,
m(MoKa) 1.256 mmꢁ1, T(CryAlisPro)min,max 0.96750, 1.00000,
2ymax 61.72, hkl range ꢁ29 31, ꢁ17 17, ꢁ36 36, N 72085, Nind
18927(Rmerge 0.0351), Nobs 14925 (I . 2s(I)), Nvar 829,
residuals R1(F) 0.0549, wRꢁ2(3F2) 0.1487, GoF(all) 1.053,
Drmin,max ꢁ0.635, 1.583 eꢁ
A
.
˚
Full crystallographic data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif under CCDC numbers 889527
and 891405.
(m) M. Schmittel, H. Ammon, V. Kalsani, A. Wiegrefe, C. Michel,
Chem. Commun. 2002, 2566. doi:10.1039/B207801E
(n) R. A. Bilbeisi, J. K. Clegg, N. Elgrishi, X. D. Hatten, M. Devillard,
B. Breiner, P. Mal, J. R. Nitschke, J. Am. Chem. Soc. 2012, 134, 5110
and refs therein. doi:10.1021/JA2092272
Acknowledgement
This research was supported by Basic Science Research Program through
the National Research Foundation of Korea (NRF) funded by the Ministry
of Education, Science and Technology (2012-0001573) (YK) and the
Australian Research Council (LFL).
[10] (a) Y.-Q. Zheng, D. -Y. Cheng, B.-B. Liu, W.-X. Huang, Dalton Trans.
2011, 40, 277. doi:10.1039/B916719F
(b) A. Woo, Y. H. Lee, S. Hayami, L. F. Lindoy, P. Thue´ry, Y. Kim, J.
Incl. Phenom. Macrocycl. Chem. 2011, 71, 409. doi:10.1007/S10847-
011-0030-7
(c) C. Nunez, R. Bastida, L. Lezama, A. Macias, P. Perez-Lourido,
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