Crystal structure and magnetic properties of [C6H4(CH2NH3)2] [CuCl3(H2O)]Cl·H2O

Article abstract of DOI:10.1016/S0020-1693(01)00392-9

The preparation, crystal structure and magnetic properties of the title compound, (1,3-xylylenediammonium)auqatrichlorocuprate(II) chloride hydrate, have been determined. It is monoclinic, space group P2₁/c, with a = 12.711(2), b = 6.122(1), c = 19.175(5)? and β = 96.72(2)° with V = 1481.6(5)?³ for Z = 4. The structure contains several architectural features of significance. The compound contains planar CuCl₃(H₂O)^- anions with Cu-Cl distances ranging from 2.2590(8) to 2.3239(6)? and a Cu-O distance of 1.991(2)?. The anions form stacks through the formation of long (3.06?, average) semi-coordinate Cu···Cl bonds. Hydrogen bonding involving the coordinated and lattice water molecules ties the stacks together into two-dimensional arrays. The diammonium cations form organic layers interleaved between the inorganic arrays. The cations are anchored to the inorganic arrays by an efficient -NH₃···Cl hydrogen-bonding network. Magnetic measurements indicate that weak antiferromagnetic interactions (2J/k = -3.06K) exist in the system, which is attributed to exchange coupling mediated by the semi-coordinate Cu···Cl bonds.

Full text of DOI:10.1016/S0020-1693(01)00392-9

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 316 (2001) 94–98
Crystal structure and magnetic properties of
[C6H4(CH2NH3)2][CuCl3(H2O)]Cl·H2O
Salim F. Haddad a, Roger D. Willett b,*, Christopher P. Landee c
a Department of Chemistry, Uni6ersity of Jordan, Amman, Jordan
b Department of Chemistry, Washington State Uni6ersity, Pullman, WA 99164, USA
c Department of Physics, Clark Uni6ersity, Worcester, MA 01610, USA
Received 15 November 2000; accepted 14 February 2001
Abstract
The preparation, crystal structure and magnetic properties of the title compound, (1,3-xylylenediammo-
nium)auqatrichlorocuprate(II) chloride hydrate, have been determined. It is monoclinic, space group P21/c, with a=12.711(2),
3
,
,
b=6.122(1), c=19.175(5) A and i=96.72(2)° with V=1481.6(5) A for Z=4. The structure contains several architectural
features of significance. The compound contains planar CuCl3(H2O)− anions with CuꢀCl distances ranging from 2.2590(8) to
,
,
,
2.3239(6) A and a CuꢀO distance of 1.991(2) A. The anions form stacks through the formation of long (3.06 A, average)
semi-coordinate Cu···Cl bonds. Hydrogen bonding involving the coordinated and lattice water molecules ties the stacks together
into two-dimensional arrays. The diammonium cations form organic layers interleaved between the inorganic arrays. The cations
are anchored to the inorganic arrays by an efficient ꢀNH3···Cl hydrogen-bonding network. Magnetic measurements indicate that
weak antiferromagnetic interactions (2J/k= −3.06 K) exist in the system, which is attributed to exchange coupling mediated by
the semi-coordinate Cu···Cl bonds. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Crystal structure; Magnetism; Copper complexes; Halide complexes
(e.g. see Ref. [4]). In the latter, the Cu(II) coordination
sphere always shows, to a greater or lesser extent, a
tendency for distortion towards trigonal-bipyramidal
geometry.
For monomeric copper(II) halide complexes, the
dominant species found are either the CuX42− anions
[5] or the neutral CuX2L2 species (e.g. see Ref. [6]).
Very few CuX3L− anions are known [7], but these
include three salts with L=H2O [7d,e]. In this paper,
we report the structure, thermal and magnetic proper-
ties of a compound containing stacks of CuCl3(H2O)−
anions.
1. Introduction
The crystal chemistry of copper(II) halides is exceed-
ingly complex due to the interplay of the Jahn–Teller
effect on the coordination geometry of the Cu(II) ion,
the bridging capabilities of the halide ions and the
electrostatic effects of the organic counterions. Never-
theless, certain structural motifs are found to recur
frequently. For square-planar species, aggregation typi-
cally occurs through the formation of so-called semi-co-
ordinate Cu···X bonds between oligomers [1]. These are
,
typically more than 0.5 A longer than the primary
CuꢀX bonds. Three dominant structural types are
found for copper(II) halide monomers with square-pla-
nar coordination. These are the two-dimensional layer
perovskite structural class (see Ref. [2] for a review),
stacked one-dimensional chains [3] and discrete dimers
2. Experimental
2.1. Synthesis
10 mmol m-xylylenediamine 99% (Aldrich) was
added to 20 mmol CuCl2·2H2O in 20 ml 6 M HCl. The
light green solution was brought to a boil, then allowed
* Corresponding author. Tel. +1-509-3351516; fax: +1-509-
3358867.
E-mail address: willett@mail.wsu.edu (R.D. Willett).
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00392-9

S.F. Haddad et al. / Inorganica Chimica Acta 316 (2001) 94–98
95
to cool to room temperature (r.t.). Crystals started
appearing on the surface in contact with the walls of
the beaker in 2 h. A bulk of transparent light green
crystals was found at the bottom of the beaker in 8 h.
Crystals were removed by suction filtration and washed
by two 5 ml portions of acetone. A crystal fragment of
approximate dimension 0.45×0.40×0.30 mm3, cut
from a larger needle crystal, was mounted for X-ray
diffraction.
2.2. Thermogra6imetric analysis (TGA)
Data were obtained using a Perkin–Elmer TGA 7
thermogravimetric analyzer on both powdered and
crystalline samples with a scan rate of 10°C min−1. All
runs showed a gradual weight loss starting at 68°C and
practically leveling off by 103°C. The mass loss in that
temperature range was 9.04%, corresponding to the loss
of 1.91 mol of H2O from the formula unit
C8H14N2CuCl4·2H2O (FW 379.6). The remaining
0.09 mol of H2O came out in the temperature range
103–150°C.
Table 1
Crystal data and structure refinement for (xylylenediammo-
nium)[CuCl3(H2O)]Cl(H2O)
Formula
Formula weight
T (K)
C8H18Cl4CuN2O2
375.55
293
,
Wavelength (A)
Crystal system
Space group
0.71073
monoclinic
P21/c
2.3. X-ray diffraction
,
a (A)
12.7107(18)
6.1219(10)
19.172(5)
96.72(2)
1481.6(5)
4
1.684
2.186
9133
3582 (Rint=0.0297)
1.041
0.0304
0.0744
0.0400
Data were collected at room temperature on a
Siemens SMART 1000 three-circle platform diffrac-
tometer equipped with a CCD detector maintained near
−54°C and the x-axis fixed at 54.74°. The frame data
were acquired with the SMART [8] software at 295 K
,
b (A)
,
c (A)
i (°)
V (A )
3
,
Z
zcalc (Mg m−3
)
v (mm−1
)
,
using Mo Ka radiation (u=0.710 73 A). A complete
Reflections collected
Unique reflections
Goodness-of-fit on F2
R1 [I\2|(I)] a
hemisphere of data is scanned on ꢀ (0.3°) with a run
time of 10 s per frame at the detector resolution of
512×512 pixels. The frames were then processed with
the SAINT software [9] to give the hkl file corrected for
Lp/decay. The absorption correction was performed
using the SADABS [10] program. The structures were
solved by the direct method using the SHELX-90 [11]
program and refined by the least-squares method on F2,
SHELXL-93 [12], incorporated in SHELXTL V 5.03 [13].
The crystals used for the diffraction study showed no
appreciable decomposition during data collection.
The structure solution was pursued in the space
group P21/c utilizing the direct methods subroutine
TREF in the XS routine in the SHELXTL program
package. The resultant E-map revealed the position of
the heavy atoms and most of the C, N and O atoms.
All non-hydrogen atoms are refined anisotropically.
Hydrogen atom positions were located from a differ-
ence Fourier map and were refined isotropically. Table
1 summarizes the most important structural and refine-
ment parameters. Atomic coordinates are given in
Table 2 and a list of important distances and angles is
given in Table 3. Fig. 1 illustrates the contents of the
asymmetric unit.
wR2 [I\2|(I)] b
R1 (all data) a
wR2 (all data) b
0.0787
a R1=S ꢀꢀFoꢀ−ꢀFcꢀꢀ/S ꢀFoꢀ.
b wR2=S wꢀꢀFoꢀ −ꢀFcꢀ ꢀ/S wꢀFoꢀ .
2
2
2
Table 2
Atomic coordinates (×104) and equivalent isotropic displacement
parameters (A ×10 ) for (xylylenediammonium)[CuCl3(H2O)]-
2
3
,
Cl(H2O)
a
Atom
x
y
z
Ueq
Cu
4834(1)
3021(1)
6592(1)
5140(1)
7327(1)
4523(1)
6050(1)
7596(1)
12 825(1)
9414(1)
10 240(2)
10 891(1)
10 704(2)
9881(2)
7559(1)
7698(1)
7491(1)
7391(1)
9545(1)
7771(2)
5336(3)
7201(3)
7459(3)
6328(3)
7568(3)
6811(3)
4738(3)
3490(3)
4271(3)
7235(4)
8279(4)
529(1)
217(1)
943(1)
25(1)
26(1)
26(1)
28(1)
39(1)
29(1)
42(1)
27(1)
29(1)
28(1)
29(1)
27(1)
30(1)
30(1)
30(1)
38(1)
36(1)
Cl(2)
Cl(3)
Cl(4)
Cl(5)
O(3)
O(4)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
−607(1)
−2007(1)
1521(1)
−2560(1)
−543(1)
−1531(1)
−812(1)
−1009(1)
−1491(1)
−1774(1)
−1579(1)
−1102(1)
−284(1)
−1721(1)
2.4. Magnetic measurements
9237(2)
8737(2)
11 740(2)
The magnetization and susceptibility studies were
done on a powdered sample using a Quantum Design
SQUID magnetometer. The magnetization of the sam-
ple was determined as a function of field at 4.5 K and
found to be linear up to 3 T. No hysteresis was de-
a Ueq is defined as one-third of the trace of the orthogonalized Uij
tensor.

96
S.F. Haddad et al. / Inorganica Chimica Acta 316 (2001) 94–98
Table 3
the temperature-independent magnetization of the
Cu(II) ion (60×10−6 emu mol−1) and the diamagnetic
contributions calculated from Pascal’s constants
(−210×10−6 emu mol−1).
,
Bond lengths (A) and angles (°) for (xylylenediammonium)-
[CuCl3(H2O)]Cl(H2O)
Atoms
Distances
Atoms
Angles
CuꢀCl(2)
CuꢀCl(3)
CuꢀCl(4)
CuꢀO(3)
CuꢀCl(4
2.3133(6)
2.2830(6)
2.2590(8)
1.991(2)
3.034(1)
3.095(1)
Cl(2)ꢀCuꢀCl(3)
Cl(2)ꢀCuꢀCl(4)
Cl(3)ꢀCuꢀCl(4)
O(3)ꢀCuꢀCl(2)
O(3)ꢀCuꢀCl(3)
O(3)ꢀCuꢀCl(4)
CuꢀCl(4)ꢀCu a
CuꢀCl(4)ꢀCu b
174.615(19)
91.79(3)
93.53(3)
86.65(6)
88.02(6)
178.09(5)
90.0(1)
3. Discussion
The structure consists of planar CuCl3(H2O)− an-
ions, diprotonated m-xylylene cations, lattice Cl− ions
and lattice H2O molecules. The CuꢀCl distances in the
anions average 2.285 A (range 2.2590(8) to 2.3133(6) A)
and the CuꢀO distance is 1.991(2) A. The average
CuꢀCl distances are somewhat longer than in the previ-
ous three anions studied, whereas the CuꢀO distance is
intermediate in length [7d,e]. The dominant structural
architectural features involved in building the three-di-
mensional crystal structure include all of the following:
semi-coordinate Cu···Cl bond formation to expand the
copper(II) coordination sphere; hydrogen bonding of
the water molecules to stabilize the lattice chloride ions
and water molecules; dispersion interactions between
the phenyl rings to promote aggregation of the organic
cations; hydrogen bonding of the ꢀNH+3 groups to tie
the organic and inorganic substructures together.
a
)
CuꢀCl(4 b)
84.9(1)
,
,
,
a Atom coordinates transformed by 1−x, 1−y, −z.
b Atom coordinates transformed by 1−x, 2−y, −z.
The role of the semi-coordinate bond formation is to
develop stacks of the CuCl3(H2O)− anions running
parallel to the crystallographic b axis, as shown in Fig.
2. Adjacent anions in the stack are related by centers of
inversion, yielding semi-coordinate Cu···Cl distances of
Fig. 1. Illustration of asymmetric unit for (xylylenediammonium)-
[CuCl3(H2O)]Cl(H2O). Thermal ellipsoids shown at 50% probability.
,
3.034 and 3.095 A. The stacking pattern is one of
several different basic types found for the stacking of
planar copper(II) halide [14] oligomers and is specified
by the Geiser notation 1(1/2, 1/2, 180°)(−1/2,
−1/2, 180°).
The hydrogen-bonding interactions of the water
molecules tie these stacks together into two-dimensional
sheets lying parallel to the bc plane, as illustrated in
Fig. 3. The primary hydrogen bonding involves the
water molecules of the anions with the lattice water
molecules. Each anion water molecule hydrogen bonds
,
to a lattice water molecule at a distance of 2.723 A,
,
while the lattice water molecule forms a 2.908 A hydro-
gen bond to an anion water molecule in the adjacent
stack. This defines a spiral hydrogen bonding network
about the 21 screw axes at (1/2, y, 1/4) and (1/2, y, 3/4).
The lattice chloride ions are appended to this network
by hydrogen bonds from the lattice water molecule
Fig. 2. Illustration of the aggregation of the [CuCl3(H2O)]− anions to
form a one-dimensional stack.
(O(4)ꢀCl(5)=3.161 A) and from the anion water
,
,
molecule (O(3)ꢀCl(5)=3.099 A).
The organic cations also aggregate in layers lying
parallel to the bc plane. As can also be seen also in Fig.
3, the phenyl rings form stacks parallel to be b axis.
Adjacent molecules are related by centers of inversion,
and the perpendicular distance between phenyl rings is
tected. All further magnetic measurements were con-
ducted in a field of 1 T. The molar susceptibility 
,
mol
defined as molꢀlimB“0(Mmol/B), was collected as a
function of temperature between 2.0 and 100 K. Cor-
rections to the molar susceptibility have been made for
,
3.556 A. In this manner, all of the hydrophilic moieties

S.F. Haddad et al. / Inorganica Chimica Acta 316 (2001) 94–98
97
Fig. 3. Illustration of the hydrogen-bonding network that develops the laminar organic/inorganic layer structure.
in the structure lie in planes at x=1/2 and the hydro-
phobic portions lie at x=0. The two ꢀCH2NH3+ arms
of each organic cation extend on either side of these
hydrophilic layers.
can displace the coordinated water molecules. In this
manner, both types of water molecule can be removed
expeditiously.
Magnetic measurements were made to investigate the
The three-dimensional structure is now built up
through the formation of ꢀNH3···Cl hydrogen bonds
between the organic layer and the inorganic layers. In
this manner, an interleaved structure is developed with
alternating organic and inorganic layers. The hydrogen
bonding between the two layers is extremely efficient.
Both ꢀNH3 groups form five hydrogen bonds to chlo-
ride ions (four from the anion and one to the lattice
chloride). For N(1), the NꢀCl distances range from 3.1
strength of the exchange coupling along the chain. The
−1
data are presented in Fig. 4 as (
)
mol
versus tempera-
ture. The higher-temperature data (T\5 K) are well
represented by the Curie–Weiss equation with a small
negative temperature intercept. The Curie–Weiss
parameters C and q are C=0.40(1) emu K mol−1 (g=
2.06(5)) and q= −1.6(1) K. The small Curie–Weiss
temperatures indicate the presence of a weak antiferro-
magnetic interaction. The prediction for the best-fit
parameters is shown as the dashed line in Fig. 4.
The molar susceptibility is also shown in Fig. 4. It
increases steadily with decreasing temperature and does
not show a maximum down to the lowest temperature
,
to 3.3 A. The N(2) atom, in addition, forms a short
NꢀH···O hydrogen bond to the lattice water molecule
,
of 2.960 A. Consequently, its NꢀH···Cl distances are
,
somewhat longer (3.25–3.35 A).
From the TGA results, the gradual smooth drop in
mass in the temperature range 68–103°C indicates that
both of the water molecules (the lattice H2O and the
Cu(II)-coordinated H2O) are rather weakly held in the
structure. This is somewhat surprising, since the coordi-
nate CuꢀOH2 bond is certainly stronger than hydrogen
bond interactions. In contrast, dehydration of the two
CuCl3(H2O)− anions studied previously [7d] did not go
to completion until 140°C. Neither of these contained
additional lattice water molecules. Thus, the presence of
the lattice chloride ion, coupled with the extensive
hydrogen-bonding network described above, may lead
to a cooperative mechanism for the loss of water
molecules upon heating. In this scenario, as the lattice
water molecules are lost from the lattice, the hydrogen-
bonding network is weakened, and the chloride ions
−1
Fig. 4. Plot of (
T.
)
(open circles) and 
(open squares) versus
mol
mol

98
S.F. Haddad et al. / Inorganica Chimica Acta 316 (2001) 94–98
(2 K) measured. Considering the linear chain crystal
structure and the isotropic nature of the cupric ion, the
data have been compared with the theoretical predic-
tions for the susceptibilities of a one-dimensional
S=1/2 Heisenberg antiferromagnet [16]. Both the ex-
change parameter J and the Lande´ g-factor were al-
lowed to vary independently, with best-fit parameters
2J/k= −3.06(5) K and g=2.07(1). The predicted
curve appears as the solid curve in Fig. 4; agreement
between data and the theoretical curve is excellent.
These magnetic results can be compared with the
magnetic properties of other copper(II) chloride com-
plexes with similar types of linear chain arrangement.
For the analogous 2-aminopyrimidinium salt [7d], J/k
was observed to be −3.1 K. Hatfield and others exam-
ined a series of asymmetric bibridged chain compounds,
and found J/k values ranging from −0.8 to −12.2 K
[6c,7a,15]. A large number of asymmetric bibridged
dimers have been investigated both experimentally and
theoretically [17]. The exchange constants observed
tend to cluster about values of J/k in the range 95 K.
The values of J/k have been roughly correlated with the
parameter h/R, where R is the semi-coordinate CuꢀCl
bond distance and h is the CuꢀClꢀCu bond angle. This
correlation predicts weak ferromagnetic coupling for
University of Connecticut for the use of the SQUID
magnetometer. We also thank Matt Woodward for his
help with the data collection and analysis. Partial sup-
port from ACS-PRF-34770AC5 is also acknowledged.
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Acknowledgements
The use of the Single Crystal X-Ray Diffraction
Laboratory of the University Research Office at the
University of Idaho is greatly appreciated. The work at
Clark University was supported by the NSF through
grant 9803813. We thank Professor Joe Budnick of the
.