Low-dimensional compounds containing cyanido groups. XXI. Crystal structure, spectroscopic, thermal and magnetic properties of two polymorphous modifications of [Cu(men)2Pt(CN)4]n complex (men = N-methyl-1,2-diaminoethane)

Article abstract of DOI:10.1016/j.poly.2010.10.009

Violet (1) and blue (2) polymorphous modifications of [Cu(men) ₂Pt(CN)₄]_n (men = N-methyl-1,2-diaminoethane) have been prepared and investigated by IR and UV-vis spectroscopy, thermal analysis, measurement of magnetic data and X-ray structural analysis. Both modifications are formed by similar but differently packed zigzag chains, which consist of [Cu(men)₂]²⁺ moieties bridged by two trans arranged cyanido groups of [Pt(CN)₄]^2- units. The Cu(II) atoms in both structures are hexacoordinated by four nitrogen atoms in the equatorial plane from two molecules of bidentate men ligands with the average Cu-N(Me) and Cu-N(H₂) bond lengths of 2.046(8) and 2.008(8) , respectively, and by two nitrogen atoms from bridging cyanido groups in the axial positions at average distance of 2.50(7) . Broad nearly symmetric bands observed in the UV-vis spectra of 1 and 2 of ²B_1g → ²E_g transitions are consistent with a deformed octahedral coordination of the CuN₆ chromophoric groups. One and two ν(CN) absorption bands observed in the IR spectra of 1 and 2, respectively, are in agreement with different local symmetries of [Pt(CN)₄]^2- units and different Cu-N(cyanido) bond lengths in these polymorphs and are subject of discussion on the spectral-structural correlations in 1D compounds. The complexes are stable up to 238 °C when their two-stage thermal decompositions start and ending up with a mixture of CuO and metallic Pt as the most probable final thermal decomposition products. The temperature dependence of the magnetic susceptibility suggests the presence of a weak antiferromagnetic exchange coupling between Cu(II) atoms in 1, J/hc = -0.17 cm^-1 and in 2, J/hc = -1.3 cm^-1.

Full text of DOI:10.1016/j.poly.2010.10.009

Polyhedron 30 (2011) 269–278
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Low-dimensional compounds containing cyanido groups. XXI. Crystal structure,
spectroscopic, thermal and magnetic properties of two polymorphous
modifications of [Cu(men)2Pt(CN)4]n complex (men = N-methyl-1,2-diaminoethane)
a
b
b
c
d
Martin Vavra a, , Ivan Potocnák , Erik Cizmár , Marcela Kajnaková , Michal Dušek , Harry Schmidt ,
⇑
ˇ
e
ˇ ˇ
ˇ
ˇ
e
g
ˇ f
ˇ
Mykhaylo Ozerov , Sergei A. Zvyagin , L’ubor Dlhán , Roman Boca
a Department of Inorganic Chemistry, Institute of Chemistry, P.J. Šafárik University, Moyzesova 11, SK-04154 Košice, Slovakia
b Centre of Low Temperature Physics, Faculty of Science, P.J. Šafárik University and IEP SAS, Park Angelinum 9, SK-04154 Košice, Slovakia
c Institute of Physics, Na Slovance 2, CZ-182 21 Praha 8, Czech Republic
d Institute of Inorganic Chemistry, Martin-Luther-University, Halle-Wittenberg, Kurt-Mothes-Str. 2, D-06120 Halle, Germany
e Dresden High Magnetic Field Laboratory (HLD), Research Center Dresden-Rossendorf (FZD), 01314 Dresden, Germany
f Institute of Inorganic Chemistry, Technology and Materials, FCHPT, Slovak University of Technology, Radlinského 9, SK-81237 Bratislava, Slovakia
g Department of Chemistry (FPV), University of SS Cyril and Methodius, SK-91701 Trnava, Slovakia
a r t i c l e i n f o
a b s t r a c t
Article history:
Violet (1) and blue (2) polymorphous modifications of [Cu(men)2Pt(CN)4]n (men = N-methyl-1,2-diami-
noethane) have been prepared and investigated by IR and UV–vis spectroscopy, thermal analysis, mea-
surement of magnetic data and X-ray structural analysis. Both modifications are formed by similar but
differently packed zigzag chains, which consist of [Cu(men)2]2+ moieties bridged by two trans arranged
cyanido groups of [Pt(CN)4]2ꢀ units. The Cu(II) atoms in both structures are hexacoordinated by four
nitrogen atoms in the equatorial plane from two molecules of bidentate men ligands with the average
Cu–N(Me) and Cu–N(H2) bond lengths of 2.046(8) and 2.008(8) Å, respectively, and by two nitrogen
atoms from bridging cyanido groups in the axial positions at average distance of 2.50(7) Å. Broad nearly
Received 14 July 2010
Accepted 19 October 2010
Available online 26 October 2010
Keywords:
1D crystal structure
Polymorphous modifications
N-methyl-1,2-diaminoethane
Tetracyanidoplatinate(II)
Infrared spectroscopy
symmetric bands observed in the UV–vis spectra of 1 and 2 of 2B1g
?
2Eg transitions are consistent with a
(C„N) absorption
deformed octahedral coordination of the CuN6 chromophoric groups. One and two
m
bands observed in the IR spectra of 1 and 2, respectively, are in agreement with different local symme-
tries of [Pt(CN)4]2ꢀ units and different Cu–N(cyanido) bond lengths in these polymorphs and are subject
of discussion on the spectral–structural correlations in 1D compounds. The complexes are stable up to
238 °C when their two-stage thermal decompositions start and ending up with a mixture of CuO and
metallic Pt as the most probable final thermal decomposition products. The temperature dependence
of the magnetic susceptibility suggests the presence of a weak antiferromagnetic exchange coupling
Spectral–structural correlations
Antiferromagnetic exchange
between Cu(II) atoms in 1, J/hc = ꢀ0.17 cmꢀ1 and in 2, J/hc = ꢀ1.3 cmꢀ1
.
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
In our previous studies on the role of hydrogen bonds as possi-
ble exchange paths for magnetic interactions in low-dimensional
compounds we have prepared and characterized compounds of
general formula [Cu(L)2Pt(CN)4]n, where L are bidentate N-donor li-
gands: 1,2-diaminoethane (en), its N,N0- (bmen) and N,N-dimethyl
(dmen) derivatives, and 2,20-bipyridine (bpy). Crystal structure
analysis has revealed that their structures are formed by 1D zigzag
chains stabilized by hydrogen bonds [5–7]. Within this studies we
have also investigated a correlation between the number of differ-
The cyanide moiety C„N can act as a terminal or bridging li-
gand. In most compounds with bridging cyanide, polymeric one-
(1D), two- (2D) or three-dimensional (3D) networks are observed
in the solid state. As has been reviewed, interest has been drawn
to cyanide-containing systems such as the Prussian blue com-
pounds [1], the Hofmann clathrates [2], or low-dimensional com-
pounds [3], largely because of their potentially useful physical or
chemical properties. However, in spite of all the research done in
this field, it is still difficult to predict the structure or even the
dimensionality of a new compound of this class [4].
ent cyanido groups in the structures and the number of m(C„N)
vibrations in the IR spectra to predict the dimensionality of the
prepared compounds, as well as correlation between the Cu–
N(cyanido) bond lengths and the wavenumbers of
tions. We have found that the longer Cu–N(cyanido) bond lengths,
the lower wavenumbers of (C„N) vibrations, sometimes even
m(C„N) vibra-
⇑
Corresponding author. Tel.: +421 55 234 2346; fax: +421 55 62 221 24.
E-mail address: martin.vavra@upjs.sk (M. Vavra).
m
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.10.009

270
M. Vavra et al. / Polyhedron 30 (2011) 269–278
leading to the smaller number of observed
m
(C„N) vibrations than
w, 2882 w;
d(CH3) = 1471 s, 1450 m, 1435 w, 1416 w;
(NH2) = 1066 s;
m
(C„N) = 2130 vs; d(NH2) = 1588 s; d(CH2) and
(CH2) = 1281 m;
(CꢀC) = 957 s; (PtꢀC) =
expected. To confirm these observations we tried to prepare other
1D compounds of [Cu(L)2Pt(CN)4]n composition with bidentate N-
donor ligands 1,10-phenanthroline, 1,2- and 1,3-diaminopropane,
nevertheless the corresponding syntheses resulted in products of
unexpected compositions with oligonuclear particles or 2D struc-
tures [8,9]. Therefore we have decided to prepare the desired 1D
compound using another derivative of en, N-methyl-1,2-diaminoe-
thane (men). As a results of our efforts, two polymorphous modifi-
cations of [Cu(men)2Pt(CN)4]n were prepared. In this paper we
present their preparation, crystal structures, spectral, thermal
and magnetic properties and we discuss the above mentioned
spectral–structural correlations as well.
s
s
m(CꢀN) = 1019 m;
m
m
497 m, 452 w, 406 m. UV–vis (solid state): kmax = 545 nm
(2B1g ? 2Eg transition). Elemental Anal. Calc. for C10H20CuN8Pt: C,
23.51; H, 3.95; N, 21.93. Found: C, 23.63; H, 4.45; N, 21.46%.
Complex 2: IR: (4000–400 cmꢀ1, KBr pellets):
m
(NꢀH) = 3279 s,
(CꢀH) = 2976 w, 2933 m, 2916 m, 2881 w;
(C„N) = 2129 vs, 2119 s; d(NH2) = 1603 m; d(CH2) and d(CH3) =
1477 w, 1448 m, 1439 m; (CH2) = 1279 w; (NH2) = 1093 s;
3240 m, 3163 m;
m
m
s
s
m
(CꢀN) = 1049 m, 1030 m;
m
(CꢀC) = 970 s;
m
(PtꢀC) = 455 w,
415 m. UV–vis (solid state): kmax = 580 nm (2B1g ? 2Eg transition).
Elemental Anal. Calc. for C10H20CuN8Pt: C, 23.51; H, 3.95; N,
21.93. Found: C, 23.27; H, 3.87; N, 21.76%.
2. Experimental
2.4. X-ray data collection and structure refinement
2.1. Materials
A summary of crystal and structure refinement data for 1 and 2
is presented in Table 1. Both crystal structures were determined
using an Oxford Diffraction Xcalibur2 diffractometer equipped
with a Sapphire2 CCD detector. Crysalis CCD was used for data col-
lection while Crysalis RED was used for the cell refinement, data
reduction and absorption correction [12]. The structure of 1 was
solved by the direct method with SHELXS97 and subsequent Fourier
syntheses using SHELXL97 [13] while the structure of 2 was solved
by JANA2006 [14] first and then redetermined using SHELXL97. The
anisotropic displacement parameters were refined for all non-H
atoms. The H atoms were placed in calculated positions and refined
riding on their parent C or N atoms with C–H distances of 0.97 and
0.96 Å for methylene and methyl H atoms, respectively, and with
N–H distances of 0.90 Å and 0.91 Å for primary and secondary ami-
no H atoms, respectively, and Uiso(H) = 1.2Ueq (C or N). An analysis
of bond distances and angles was performed using SHELXL97 [13],
DIAMOND [15] was used for molecular graphics.
Copper chloride dihydrate (CuCl2ꢁ2H2O), copper sulfate penta-
hydrate (CuSO4ꢁ5H2O) and men (C3H10N2) were of Aldrich quality
and used as received. K2[Pt(CN)4]ꢁ3H2O was prepared according
to the literature [10].
2.2. Physical measurements
Elemental analyses for C, H and N were carried out using a LECO
CHNS-932. IR spectra were recorded on an Avatar 330 FT-IR spec-
trometer by the method of KBr pellets in the range from 4000 to
400 cmꢀ1. UV–vis spectra in Nujol suspensions were measured
with a Specord 250 in the range from 300 to 1100 nm. The thermal
investigations were performed using NETZSCH STA 409 PC/PG
thermal analyzer under air conditions with a heating rate of 9 °C/
min to 900 °C. EPR data were collected at low temperatures in an
X-band Bruker ELEXSYS E500 spectrometer. Measurement of the
magnetic susceptibility was carried out using a commercial SQUID
magnetometer (Quantum Design) in the temperature range be-
tween 2 and 300 K. The correction for an underlying diamagne-
3. Results and discussions
tism, estimated using Pascal’s constants [11]
(vDIA = ꢀ2.75 ꢂ
3.1. Preparation of the title complexes
10ꢀ9 m3 molꢀ1), was applied.
The title complex 1 has been prepared in a relatively simple
way within our studies on the role of hydrogen bonds as possible
exchange paths for magnetic interactions in low-dimensional com-
pounds and within our studies on the effect of Cu–N(cyanido) bond
2.3. Synthesis and characterization
[Cu(men)2Pt(CN)4]n violet (1) and blue (2). Into stirring water–
methanol solution (1:1) of CuCl2 (0.085 g CuCl2ꢁ2H2O, 0.5 mmol),
men (0.18 ml, 2 mmol) was added in one portion and after
30 min of stirring, aqueous solution of K2[Pt(CN)4] (0.216
g K2[Pt(CN)4]ꢁ3H2O, 0.5 mmol) (1:4:1 molar ratio) was added in
one portion, too. After a few days, violet crystals of 1, with a quality
not suitable for X-ray single crystal analysis, were filtrated off and
dried on air and their IR spectrum was measured. Yield 0.197 g
(77%). The crystals suitable for X-ray analysis have been prepared
by a different procedure using CuSO4ꢁ5H2O (0.125 g, 0.5 mmol);
men (0.09 ml, 1.0 mmol) and K2[Pt(CN)4]ꢁ3H2O (0.216 g, 0.5 mmol)
(1:2:1) dissolved in 6 ml of water under hydrothermal conditions
in autoclave in a programmable heater at 100 °C for 80 h. After
cooling down to the room temperature during 13 h, blue crystals
of 2 were isolated from a blue powder of 2. In order to prepare vio-
let crystals of 1 suitable for X-ray analysis we used hydrothermal
synthesis once again using the same conditions, but with an excess
of men (0.14 ml, 1.5 mmol) (1:3:1). After cooling down to the room
temperature, violet crystals of 1 were filtrated off and dried on air.
The IR spectra of violet crystals of 1 prepared by above mentioned
different ways were identical.
length on the wavenumber of corresponding m(C„N) vibration. To
prepare the desired complex, we have used the same procedure
and the same Cu(II), men and [Pt(CN)4]2ꢀ molar ratios as were used
in the preparation of the previous chain-like [Cu(L)2Pt(CN)4]n com-
plexes (L = en, dmen, bmen and bpy) [5–7]. Nevertheless, prepared
violet crystals of 1 were of a poor quality and therefore hydrother-
mal reaction conditions were used. During our successful attempts
to prepare crystals of 1 suitable for X-ray analysis, blue crystals of 2
were accidentally prepared, too. Although the IR and UV–vis spec-
tra of 1 and 2 were different, the results of the elemental analysis
of both complexes are in good agreement with an expected [Cu(-
men)2Pt(CN)4]n composition, thus indicating two polymorphous
modifications of the same compound. This was definitely con-
firmed by the X-ray analysis which revealed that compounds 1
and
2 have similar chain-like structure with the [Cu(men)2
Pt(CN)4]n formula but their symmetry differs.
3.2. X-ray crystallography
X-ray analysis has revealed that crystal structures of 1 and 2 are
similar and are formed by 1D zigzag chains which consist of [Cu(-
men)2]2+ moieties bridged by two trans arranged cyanido groups
Complex 1: IR (4000–400 cmꢀ1, KBr pellets):
3259 vs, 3160 m;
(CꢀH) = 2998 w, 2982 m, 2970 m, 2957 m, 2907
m
(NꢀH) = 3316 vs,
m

M. Vavra et al. / Polyhedron 30 (2011) 269–278
271
Table 1
Crystal data and structure refinement of 1 and 2.
1
2
Empirical formula
Formula weight
T (K)
C
10H20CuN8Pt
C10H20CuN8Pt
510.97
293(2)
0.71073
tetragonal
P42/m
510.97
293(2)
0.71073
triclinic
k (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
ꢀ
P1
7.3529(3)
7.4376(3)
7.7496(3)
10.18372(14)
10.18372(14)
7.55607(19)
a
(°)
101.207(4)
b (°)
97.866(4)
c
(°)
102.927(4)
V (Å3)
397.92(3)
783.63(2)
Z; Dcalc
1; 2.132 g cmꢀ3
10.119
2; 2.165 g cmꢀ3
10.276
Absorption coefficient (mmꢀ1
F(0 0 0)
)
243
486
Crystal shape, color
Crystal size (mm3)
h range for data collection (°)
Index ranges
Absorption correction
Max. and min. transmission
Reflections collected/unique (Rint
Completeness to hmax (%)
Refinement method
plate, violet
prism, blue
0.28 ꢂ 0.10 ꢂ 0.07
2.83–27.00
0.27 ꢂ 0.19 ꢂ 0.08
2.73–26.58
ꢀ9 6 h 6 9, ꢀ9 6 k 6 9, ꢀ9 6 l 6 9
analytical [16]
0.553 and 0.174
6953/1667 (0.0311)
100.0
ꢀ12 6 h 6 13, ꢀ13 6 k 6 13, ꢀ9 6 l 6 9
analytical [16]
0.598 and 0.188
)
15591/918 (0.0487)
99.8
full-matrix least-squares on F2
1667/0/95
1.007
full-matrix least-squares on F2
918/0/79
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
0.953
Final R factors [I > 2
r
(I)]
R1 = 0.0148, wR2 = 0.0341
R1 = 0.0148, wR2 = 0.0341
0.400 and ꢀ0.619
R1 = 0.0130, wR2 = 0.0288
R1 = 0.0220, wR2 = 0.0302
1.132 and ꢀ0.309
R factors (all data)
Largest difference in peak and hole (e Åꢀ3
)
of [Pt(CN)4]2ꢀ units. A DIAMOND view with the atomic numbering
scheme of these compounds is depicted in Figs. 1 and 2, respec-
tively, and selected bond lengths and bond angles for both
compounds are given in Table 2. These complexes represent struc-
tural analogs of the [Cu(L)2M(CN)4]n complexes mentioned in Sec-
tion 1. The Cu(II) atoms in both structures are six-coordinate,
complexed with the four nitrogen atoms of two men ligands in
the equatorial planes and two nitrogen atoms from bridging cyan-
ido groups in the axial positions.
The Cu–N bond distances in the equatorial planes of both com-
plexes are not of the same length and the effect of steric repulsion
of methyl groups bonded to N3 atoms is clear; whereas the average
value of Cu1–N3(Me) bonds is 2.046(8) Å, the average value of
Cu1–N4(H2) bonds is only 2.008(8) Å. If we compare these values
with the respective values found in other [Cu(L)2Pt(CN)4]n com-
plexes we can see that for L = en [5], where only Cu–N(H2) bonds
are present (2.022(7) Å on average), the Cu1–N3(Me) and Cu1–
N4(H2) bonds in 1 and 2 are about 0.02 Å longer and shorter,
respectively. For L = bmen [6], where only Cu–N(Me) bonds are
present (2.043(18) Å on average), these bonds are of the same
length as the Cu1–N3(Me) bonds in 1 and 2. Finally, the effect of
bulky methyl groups on the Cu–N bond lengths is remarkable for
L = dmen [5], where both Cu–N(Me2) and Cu–N(H2) bonds are
present (2.115(4) and 1.984(4) Å, respectively). Similar trends in
Cu–N bond lengths have been observed in other [Cu(L)2M(CN)4]n
complexes containing a bulky group substituting one amino
hydrogen atom; e.g. [Cu(eten)2M(CN)4]n (eten = N-ethyl-1,
2-diaminoethane; M = Ni, Pd and Pt) with Cu–N(Et) = 2.056(2),
2.050(2) and 2.054(2) Å, respectively, and Cu–N(H2) = 2.008(2),
2.007(2) and 2.010(2) Å, respectively [17,18], [Cu(hydeten)2
Pt(CN)4]n (hydeten = N-(2-hydroxyethyl-1,2-diaminoethane) with
Cu–N(EtOH) = 2.070(4) Å and Cu–N(H2) = 2.029(4) Å [19] or in
a
c
N4
b
N1
C1
N2
N3i
C2
Cu1
N3
N2i
Pt1
C2ii
N4i
C1ii
Fig. 1. Structure of 1 with displacement ellipsoids (25% probability) and labeling of selected atoms. Symmetry operations: (i) 1 ꢀ x, 1 ꢀ y, ꢀ1 ꢀ z and (ii) ꢀx, ꢀy, ꢀ2 ꢀ z.

272
M. Vavra et al. / Polyhedron 30 (2011) 269–278
c
a
b
N3
N1
N2
N4i
Cu1
C2
C1
N2iii
Pt1
N4
C2ii
N3i
C1ii
Fig. 2. Structure of 2 with displacement ellipsoids (25% probability) and labeling of selected atoms. Symmetry operations: (i) ꢀx, 1 ꢀ y, ꢀz; (ii) 1 ꢀ x, 1ꢀy, z; and (iii) ꢀx, 1 ꢀ y,
z.
Table 2
sisting in different bond parameters, in different arrangement of
methyl groups of men ligands, in different packing of the chains
Selected bond lengths (Å) and bond angles (°) of 1 and 2.
and in different hydrogen bonds (HBs). The most remarkable dif-
ferences in bond parameters are the Cu1–N2 bonds and the Cu1–
N2„C2 angles, mentioned above, as well as other angles given in
the Table 2. Different arrangement of methyl groups of men ligands
in 1 and 2 can be recognized in Figs. 1 and 2, respectively, and is
evidenced by different values of C–C–N3–Me torsion angles within
men molecules in 1 and 2, which are 89.7 and 179.9°, respectively.
Thus, the methyl groups are coordinated to the planes of Cu–men
metallocycles in 1 and 2 in nearly perpendicular and parallel fash-
ions, respectively. Moreover, while all atoms of the men ligand in 1
are fully occupied (their site occupation factors, SOFs, are equal to
1), the men ligands in 2 are disordered over two positions with
SOFs equal to 0.5. Disordered men ligands in 2 are shown in
Fig. 3. The most striking difference in the structures of 1 and 2 is
a different packing of the chains. Whereas all chains in 1 run along
the [1 1 1] direction being thus mutually parallel (Fig. 4), the chains
in 2 are extended along both the a and b axes. Thus two sets of par-
allel chains which are perpendicularly crossed, exist in 2 (Fig. 5).
Due to the different packing of the chains, both structures are sta-
bilized by different N–Hꢁ ꢁ ꢁN HBs systems which involve nitrogen
atoms of terminal cyanido and of amino groups as acceptors and
donors, respectively, and which connect individual chains into
2D sheets (Fig. 6, Table 3) and 3D network (Fig. 7, Table 4), respec-
tively. The HBs system in 1 is formed by one intrachain HB medi-
ated by N4–H4Bꢁ ꢁ ꢁN1ii atoms and by two interchain HBs
mediated by N4–H4Aꢁ ꢁ ꢁN1i and N3–H3ꢁ ꢁ ꢁN1iii atoms. On the other
hand, HBs system in 2 is formed only by two interchain HBs med-
iated by N4–H4Aꢁ ꢁ ꢁN1i and N4–H4Bꢁ ꢁ ꢁN1ii atoms.
1
2
Cu1–N2
Cu1–N3
Cu1–N4
Pt1–C1
Pt1–C2
C1–N1
C2–N2
C1–Pt1–C2
Cu–N2–C2
N1–C1–Pt1
N2–C2–Pt1
N3–Cu1–N2
N4–Cu1–N2
N4–Cu1–N3
2.552(3)
2.040(2)
2.003(2)
1.987(3)
1.981(3)
1.143(4)
1.146(4)
92.09(11)
133.6(2)
176.8(3)
175.6(3)
96.07(10)
85.41(9)
85.61(10)
2.450(3)
2.051(4)
2.013(4)
1.986(4)
1.977(4)
1.146(5)
1.150(5)
88.23(14)
131.7(3)
179.0(3)
179.7(3)
91.79(14)
88.33(13)
84.18(18)
analogous [Cu(men)2Ni(CN)4]n complex [20] (Cu–N(Me) = 2.037(3)
and Cu–N(H2) = 1.996(2) Å) where these distances are slightly
shorter than in 1 and 2. The Cu-men metallocycles in both coordi-
nation polyhedra are in a dk conformation, exhibiting usual values
of bond distances and angles within the men molecules.
The axial positions of the distorted octahedral coordination
sphere are occupied by the N2 atoms of the bridging cyanido
groups and their symmetrically related partners at significantly
longer Cu1–N2 distances of 2.552(3) and 2.450(3) Å for 1 and 2,
respectively, due to Jahn–Teller effect which is characteristic for
d9 systems. The Cu1–N2 bonds are tilted from the normals to the
CuN4 equatorial planes by 7.93° and 2.60° for 1 and 2, respectively,
forming slightly distorted and tetragonally elongated 4 + 2 octahe-
dral geometries The corresponding tetragonality T factors [21] for 1
and 2 are 0.792 and 0.829, respectively.
It should be also noted that different packing probably caused
by different orientation of methyls leads to remarkably different
Square planar [Pt(CN)4]2ꢀ moieties, as parts of the zigzag chains,
connect Cu(II) atoms by two trans-arranged symmetrically related
bridging cyanido groups forming thus a 2,2-TT chain [3]. Despite
the different character of the cyanido groups the average Pt–C
and C„N bond distances as well as Pt–C„N angles for bridging
and terminal cyanido groups in 1 and 2 are very similar and in ex-
pected ranges (Table 2). On the other hand, the cyanido groups
coordinate to the copper(II) atoms in a significantly bent way as
evidenced from the Cu1–N2„C2 angles of 133.6(2)° and
131.7(3)° for 1 and 2, respectively. Nevertheless, such values are
not unusual and indicate a contribution of the ionic character to
the Cu–N bond [5,6,8,17,22–24].
N4i
N4iii
N2
N3ii
N3
Cu1
N3iii
N3i
N2ii
N4ii
N4
Although the structures of 1 and 2 are formed by very similar
zigzag chains, still there are some differences between them con-
Fig. 3. Disordered men molecules in 2. Symmetry operations: (i) ꢀx, 1 ꢀ y, ꢀz; (ii)
ꢀx, 1ꢀy, z; and (iii) x, y, ꢀz.

M. Vavra et al. / Polyhedron 30 (2011) 269–278
273
b
a
c
Pt
Cu
C
N
Fig. 4. Packing of the structure in 1, showing the chains running along the [1 1 1] direction.
580 nm are observed in the spectra of 1 and 2, respectively. These
could be assigned to 2B1g ? 2Eg transition confirming a deformed
octahedral coordination geometry of the CuN6 chromophoric
groups.
The IR spectra of 1 and 2 comprise bands corroborating the
presence of all characteristic functional groups in the prepared
complexes. Individual bands listed above in the experimental part
were assigned according to the literature [25,26]. Special attention
b
a
c
is paid to the m(C„N) stretching vibrations proving the presence of
[Pt(CN)4]2ꢀ units in the prepared compounds. Their positions are
an important tool to distinguish between terminal and bridging
character of cyanido groups. This position is observed at
2080 cmꢀ1 in ionic KCN as a single absorption band [26]. Upon
Pt
C
N
Cu
coordination to a metal, the
quencies and the range of
m
(C„N) vibration shifts to higher fre-
m(C„N) for tetracyanidoplatinates(II)
with terminal cyanido ligands extends from 2120 to 2140 cmꢀ1
.
Because cyanido nitrogen lone pair resides in a mostly C„N anti-
bonding orbital, an increase of (C„N) in bridging cyanides is
m
found and for bridged tetracyanidoplatinates(II) it ranges from
2150 to 2210 cmꢀ1 [27]. Moreover, structurally different cyanido
groups usually give rise to different
m(C„N) vibrations and thus
from the number of (C„N) bands in the IR spectrum the number
m
of different cyanido groups might be deduced. Hence there is a
chance to predict the structural type of the corresponding tetrac-
Fig. 5. Packing of the structure in 2, showing the arrangement of chains along the a
and b axes.
yanidoplatinate(II) complex. Thus, one observed m(C„N) band in
the IR spectrum usually corresponds with only one kind of cyanido
group in the structure of the respective, usually ionic, tetracyani-
doplatinate(II) complex. However in some cases, discussed later,
absorption bands of terminal and bridging cyanido groups might
be overlapped and as a result only one absorption band is observed
in the IR spectrum of 1D tetracyanidoplatinate(II) complex, too.
crystal symmetry: while 1 is a triclinic structure 2 is highly sym-
metrical tetragonal structure.
Parallel packing of the zizgzag chains has been also observed in
other 1D [Cu(L)2Pt(CN)4]n compounds where L is en, dmen and
bmen [5,6]. If we compare the HBs systems in these compounds
with that of 1, we can summarize that bonding of only one methyl
group to the N3 atoms of men ligands does not affect the HBs sys-
tem, as one intrachain and two interchain HBs were observed in en
complex with no methyl group, too. On the other hand, two methyl
groups reduce the extent of HBs to one intrachain and one inter-
chain HBs in the bmen-complex, and to only one interchain HB in
dmen-complex. Thus, reduction of HBs system to two interchain
HBs in 2 is obviously caused by different packing of the chains.
Two m(C„N) absorption bands strongly indicate two identical ter-
minal and two identical bridging cyanido groups in the 1D tetrac-
yanidoplatinate(II) complex. Surprisingly, although there are two
bridging and two terminal cyanido groups both in 1 and 2, differ-
ent number of
m(C„N) absorption bands was recorded in their IR
spectra (one band in 1 and two bands in 2). Two
m
(C„N) vibrations
have also been observed in [Cu(men)2Ni(CN)4]n [20] and [Cu(e-
ten)2Pd(CN)4]n complexes [18] or in complexes of type [Cu(b-
men)2M(CN)4]n (M = Ni, Pd and Pt) [28,29,6]. On the other hand,
in the spectra of [Cu(en)2M(CN)4]n (M = Ni, Pd and Pt) [22,23,5]
and [Cu(dmen)2M(CN)4]n (M = Ni, Pd and Pt) [28,30,5] or [Cu(e-
3.3. Spectral properties and spectral–structural correlations
ten)2M(CN)4]n compounds (M = Ni and Pt) [17] only one
absorption band has been observed. The discrepancy in the num-
m(C„N)
The UV–vis spectra of the complexes were taken as described
earlier. Broad, almost symmetric bands with maxima at 545 and

274
M. Vavra et al. / Polyhedron 30 (2011) 269–278
N1i
a
c
H4A
N1ii
N4
H4B
N3
H3
N1iii
Fig. 6. HB system in 1. The intrachain HBs are represented by empty dashed lines and the HBs connecting chains into sheets are represented by black dashed lines. Only
hydrogen atoms of amino groups are shown because of clarity. Symmetry operations: (i) 1 ꢀ x, ꢀy, ꢀ2 ꢀ z; (ii) 1 + x, 1 + y, 1 + z; and (iii) x, 1 + y, 1 + z.
Table 3
Hydrogen bonds of 1 (Å and °).
terminal cyanido group, whereas HBs system in 2 is formed only
by two interchain HBs. Because the strength of the two interchain
HBs, evaluated on the base of their bonding characteristics (see
bond lengths and angles in Tables 3 and 4), should be comparable
we can expect larger increase of the wavenumber of the corre-
sponding vibration in 1 and eventually it may be overlapped by
the vibration of bridging cyanido groups. Therefore, only one
D–Hꢁ ꢁ ꢁA
d(D–H)
d(Hꢁ ꢁ ꢁA)
2.33
2.36
2.36
d(Dꢁ ꢁ ꢁA)
3.156(4)
3.209(3)
3.158(4)
<(D–Hꢁ ꢁ ꢁA)
153.3
156.7
146.6
N4–H4Aꢁ ꢁ ꢁN1i
N4–H4Bꢁ ꢁ ꢁN1ii
N3–H3ꢁ ꢁ ꢁN1iii
0.90
0.90
0.91
Symmetry operations: (i) 1 ꢀ x, ꢀy, ꢀ2 ꢀ z; (ii) 1 + x, 1 + y, 1 + z; and (iii) x, 1 + y,
1 + z.
m(C„N) absorption band in their IR spectra has been observed.
According to these facts, the absorption band in the IR spectrum
of 1 at 2130 cmꢀ1 is assigned to the vibrations of all four cyanido
groups as the two Cu1–N2(cyanido) bonds are rather long
(2.552(3) Å) and thus the bridging cyanido groups behave spectro-
scopically as terminal ones. On the other hand, as the two Cu1–
N2(cyanido) bonds in 2 are shorter (2.450(3) Å), absorption bands
for terminal and bridging cyanido groups are separated at 2119
and 2129 cmꢀ1, respectively.
Based on the results of this and our previous work we believe
that the Cu–N(cyanido) bond distance in the square-planar cop-
per(II) tetracyanidometallates can be estimated from the number
and wavenumbers of m(C„N) vibrations in the IR spectra of the
corresponding complexes. There is depicted in Fig. 8 the depen-
ber of observed vibrations may be explained by the different local
symmetry of [Pt(CN)4]2ꢀ units in the discussed compounds.
Whereas the C„N bonds in 1, [Cu(en)2M(CN)4]n, [Cu(d-
men)2M(CN)4]n and [Cu(eten)2M(CN)4]n compounds differ only by
0.003 Å, corresponding difference in 2 and [Cu(bmen)2M(CN)4]n
compounds is somewhat larger. Thus, the local symmetry of
[M(CN)4]2ꢀ units in 1, [Cu(en)2M(CN)4]n, [Cu(dmen)2M(CN)4]n and
[Cu(eten)2M(CN)4]n compounds is D4h with only one Eu IR active
vibration while the local symmetry of [M(CN)4]2ꢀ units in 2 and
[Cu(bmen)2M(CN)4]n compounds is D2h with B2u and B3u IR active
vibrations. The different local symmetry is also reflected by the dif-
ferent Cu–N(cyanido) bond lengths in 2 and [Cu(bmen)2M(CN)4]n
compounds on the one hand, and 1, [Cu(en)2M(CN)4]n, [Cu(d-
men)2M(CN)4]n and [Cu(eten)2M(CN)4]n compounds on the other
hand. The corresponding Cu–N(cyanido) bond lengths in 2 and
[Cu(bmen)2M(CN)4]n compounds are less than 2.490(4) Å. How-
ever, these distances in 1, [Cu(en)2M(CN)4]n, [Cu(dmen)2M(CN)4]n
and [Cu(eten)2M(CN)4]n compounds are within the range of
2.537(1)–2.600(5) Å and, therefore, the bridging cyanido groups
adopt partially ionic character and their behavior is rather close
to the terminal ones. In accordance, the wavenumbers of the corre-
sponding vibrations decrease and eventually may be overlapped by
the vibrations of terminal cyanido groups. Finally, the superposi-
tion of bands might be caused by the slight increase of the position
of the terminal group absorption band because of its involvement
in HBs. As mentioned above, the HBs system in 1 is formed by one
intrachain and two interchain HBs involving the N1 atom of the
dence of the difference between the wavenumbers for bridging
and terminal cyanido groups
(
D
m
(C„N) =
m
(C„N)bridging
ꢀ
m
(C„N)terminal on the Cu–N(cyanido) bond distances for 1D
)
[Cu(L)2M(CN)4]n complexes where L is en and its derivatives with
aliphatic groups substituting amino hydrogen atoms, namely:
L = en and M = Ni, Pd and Pt [22,23,5], L = bmen and M = Ni, Pd
and Pt [28,29,6], L = dmen and M = Ni, Pd and Pt [28,30,5], L = eten
and M = Ni, Pd and Pt [17,18], L = men and M = Ni [20], and 1 and
2. As can be seen from this graph, with an increase of the Cu–
N(cyanido) bond length, the
Dm(C„N) is decreasing, what is also
in agreement with the Scott’s and Holm’s work [31]. One can also
see that there exists a critical Cu–N(cyanido) bond length (about
2.5 Å), above which the
in overlapping of the two bands and in observing only one
(C„N) absorption band.
Dm(C„N) is equal to zero, what results
m

M. Vavra et al. / Polyhedron 30 (2011) 269–278
275
N1ii
H4B
N4
H4A
N1i
b
a
c
Fig. 7. HB system in 2. The HBs connecting chains into sheets are represented by black dashed lines. Only hydrogen atoms of amino group are shown because of clarity.
Symmetry operations: (i): x, ꢀy, ꢀ1/2 + z and (ii) 1 ꢀ x, y, ꢀ1/2 ꢀ z.
Table 4
Hydrogen bonds of 2 (Å and °).
D–Hꢁ ꢁ ꢁA
d(D–H)
d(Hꢁ ꢁ ꢁA)
2.29
2.24
d(Dꢁ ꢁ ꢁA)
3.173(5)
3.120(5)
<D–Hꢁ ꢁ ꢁA
168.6
167.4
1
0
N4–H4Aꢁ ꢁ ꢁN1i
0.90
0.90
N4–H4Bꢁ ꢁ ꢁN1ii
Symmetry operations: (i) x, ꢀy, ꢀ1/2 + z and (ii) 1 ꢀ x, y, ꢀ1/2 ꢀ z.
-1
-2
-3
15
10
5
complex 1
experimental data
fit
200
250
300
350
400
450
Magnetic Field (mT)
Fig. 9. The EPR spectrum of
1 (circles) measured at 9.4 GHz. The solid line
represents a fit of a model including anisotropic g-factor ([gx, gy, gz] = [2.058, 2.056,
0
2.222]) and anisotropic linewidth broadening ([
22.10] mT) to the experimental data.
DBx, DBy, DBz] = [7.85, 3.20,
2.40
2.45
2.50
2.55
2.60
2.65
d(Cu–N(cyanido)) (Å)
lowed by separated decomposition of cyanido groups in one step
[5,6]. Both complexes are stable up to 238 °C. In the first step, com-
mon for both complexes, in the 238–300 °C temperature range a
weight loss of 13.3% and 13.7%, respectively corresponding to the
release of one men molecule (calculated 14.5%) is observed during
a slightly exothermic effect. The decomposition continuously pro-
ceeds with the next two overlapped steps which differ slightly for
both complexes, thus the data for 2 are given in the brackets. In the
300–410 °C and 410–517 °C [300–454 °C and 454–648 °C] temper-
ature ranges a weight loss of 33.3% [33.0%] is observed, which cor-
responds to the release of the second men molecule and
Fig. 8.
Dm(C„N) dependence on d(Cu–N(cyanido)) for 2,2 chain-like [Cu(L)2-
M(CN)4]n complexes (L = en and its derivatives with aliphatic groups substituting
amino hydrogen atoms; M = Ni, Pd and Pt).
3.4. Thermal analysis
Thermal decompositions of 1 and 2 are multistage processes
similar to the thermal decompositions of other [Cu(L)2Pt(CN)4]n
complexes which involve deamination in one or several stages fol-

276
M. Vavra et al. / Polyhedron 30 (2011) 269–278
We can conclude that the highest difference between the ther-
mal decompositions of 1 and 2 is the temperature when cyanido
groups are released, i.e. the temperature when the thermal decom-
positions are over. This difference might be explained by the differ-
ences in the structures of 1 and 2.
1
0
3.5. Magnetic properties
The EPR spectra of 1 and 2 obtained at 2.25 K on powdered sam-
ples (Figs. 9 and 10) have been analyzed using the EPR spectra sim-
ulation package EasySpin [32]. The best agreement with the
experimental data has been obtained for the following principal
values of the g-tensor: gx = 2.058, gy = 2.056, gz = 2.222 for complex
1 and gx = 2.065, gy = 2.085, gz = 2.157 for complex 2. The experi-
mental spectra were not possible to describe using a single line-
width, therefore anisotropic broadening of the resonance line
-1
-2
complex 2
experimental data
fit
200
250
300
350
400
450
Magnetic Field (mT)
D
B = [
D
Bx,
Bx,
D
By,
By,
D
Bz] = [7.85, 3.20, 22.10] mT for complex 1 and
Fig. 10. The EPR spectrum of 2 (circles) measured at 9.4 GHz. The solid line
represents a fit of a model including anisotropic g-factor ([gx, gy, gz] = [2.065, 2.085,
D
B = [
D
D
DBz] = [4.65, 20.50, 13.40] mT for complex 2 was
included (full width at half height). Such anisotropic linewidth
broadening can reflect the low-dimensional character of the mag-
netic subsystem in both complexes. In addition, the unresolved
hyperfine structure expected for Cu(II) atoms due to the existence
of exchange couplings between magnetic centers [33] results in
anisotropic broadening of the resonance line. The anisotropic g-
factors are consistent with the axial type of anisotropy due to the
Jahn–Teller effect typical for spin S = 1/2 Cu(II) atoms including
the influence of a weak rhombic distortion of the coordination
octahedron. The results confirm that the electronic ground state
of the Cu(II) ion is described by a wave function of dz2 symmetry
and the exchange paths will propagate along the directions deter-
2.157]) and anisotropic linewidth broadening ([
13.40] mT) to the experimental data.
DBx, DBy, DBz] = [4.65, 20.50,
decomposition of all four cyanido groups (calculated 34.9%). Their
decomposition includes oxidation of cyanido groups to form two
cyanogen molecules during the reduction of one Pt(II) to Pt atom
and formation of one copper(II) oxide by the reaction with oxygen
from air atmosphere. This process is accompanied by a strong exo-
thermic effect as a consequence of the formation of cyanogen mol-
ecules as evidenced by maximum in the DTA curve at 472 °C
[475 °C]. The final thermal decomposition products of both com-
plexes are mixtures of CuO and metallic Pt (solid residue 54.5%
[52.8%]; calculated 53.8%); the presence of copper(II) oxide has
mined by the lobes of the dx2
orbital. The difference in the line-
ꢀy2
width anisotropy for complex 1 and 2 can be explained by different
strength and orientation of exchange paths due to the differences
in HB network between the chains.
The magnetic susceptibility taken at B = 0.1 T has been con-
verted to the effective magnetic moment, as displayed in Figs. 11
been confirmed by the m(Cu–O) vibrations observed in the IR spec-
tra at 555 and 559 cmꢀ1, respectively. The most probable thermal
decomposition schemes for 1 and 2 are:
ꢄ
238—300
300—517 ꢄC
ꢀꢀꢀꢀꢀ!
1 : ½CuðmenÞ2PtðCNÞ4ꢃ
2 : ½CuðmenÞ2PtðCNÞ4ꢃ
C CuðmenÞPtðCNÞ
C CuðmenÞPtðCNÞ
CuO þ Pt
CuO þ Pt
ꢀꢀꢀꢀꢀ!
4
4
ꢀmen
ꢀmenꢀ2ðCNÞ2þ1=2O2
and 12. Its room temperature value amounts to
leff = 1.84 lB in
ꢄ
238—300
300—648 ꢄC
ꢀꢀꢀꢀꢀ!
ꢀꢀꢀꢀꢀ!
both complexes and this value stays almost constant down to 7 K
for 1 and 22 K for 2 when it turns down. Such a behavior is typical
ꢀmen
ꢀmenꢀ2ðCNÞ2þ1=2O2
Fig. 11. Left: effective magnetic moment of 1 per formula unit. Inset: temperature dependence of the magnetic susceptibility. Open circles – experimental data, lines – fitted.
Right: magnetization of 1 per formula unit (lines are guide for eyes).

M. Vavra et al. / Polyhedron 30 (2011) 269–278
277
Fig. 12. Left: effective magnetic moment of 2 per formula unit. Inset: temperature dependence of the magnetic susceptibility. Open circles – experimental data, lines – fitted.
Right: magnetization of 2 per formula unit (lines are guide for eyes).
for a regular s = 1/2 chain exhibiting antiferromagnetic exchange.
In order to fit the susceptibility data several methods have been
proposed [34–39] of which the Bonner–Fischer formula belongs
to the most popular [40,41]. The original formula has been rescaled
2 are stable up to 238 °C when their two-stage thermal decompo-
sitions start towards a mixture of CuO and metallic Pt as the most
probable final thermal decomposition products. The temperature
dependence of the inverse susceptibility suggests the presence of
a weak antiferromagnetic exchange coupling between Cu(II) atoms
in 1 and 2.
by Kahn [11] in order to accommodate the HA;Aþ1 ¼ ꢀJðSA ꢁ SAþ1Þꢀhꢀ2
notation for the exchange coupling constant. The fitting procedure
gave J/hc = ꢀ0.17 cmꢀ1, g = 2.11 and the uncompensated tempera-
b
~ ~
ture-independent magnetism of
v
TIM = +0.23 ꢂ 10ꢀ9 m3 molꢀ1
Acknowledgments
(discrepancy factor R(v) = 0.007) for 1, while for 2 yielded J/
hc = ꢀ1.3 cmꢀ1, g = 2.09 and
v
TIM = +0.73 ꢂ 10ꢀ9 m3 molꢀ1. Such a
This work was supported by the grants of the Slovak Grant
Agency VEGA 1/0079/08, 1/0213/08, and 1/0078/09, by Slovak Re-
search and Development Agency under the Contract Nos. APVV-
VVCE-0058-07, APVV-VVCE-0004-07 and APVV-0006-07, by the
Institutional Research Plan No. AVOZ10100521 of the Institute of
Physics and the Project Praemium Academiae of the Academy of
Sciences of the Czech Republic. M.V. thanks DAAD for financial
small value of the coupling constant causes that the expected max-
imum on the susceptibility curve lies below the temperature limit
of set-up (1.8 K). Since the HBs create shorter exchange paths (see
Figs. 6 and 7) between the Cu(II) centers in the direction of mag-
netic orbitals in complex 2, the coupling constant is stronger than
in complex 1. A weak antiferromagnetic exchange coupling is sim-
ilar to that of other compounds from our previous studies [5,6].
ˇ
support and hospitality of Martin-Luther-University. E.C., S.A.Z.
and M.O. would like to acknowledge the support by the Deutsche
Forschungsgemeinschaft and EuroMagNET (EU Contract No.
4. Conclusion
ˇ
228043). The authors are very grateful to Dr. Vladimír Zelenák
from P.J. Šafárik University in Košice for the thermal analysis
measurements.
Violet (1) and blue crystalline (2) polymorphous modifications
of [Cu(men)2Pt(CN)4]n complex, suitable for X-ray structural analy-
sis have been prepared by hydrothermal syntheses. Both modifica-
tions are formed by very similar 2,2-TT zigzag chains in which
[Cu(men)2]2+ moieties are connected by [Pt(CN)4]2ꢀ units. Cu(II)
atoms in both modifications are coordinated by four N atoms of
two bidentate men ligands in the equatorial plane whereas the ax-
ial positions are occupied by two N atoms of bridging cyanido
groups at substantially longer distances due to Jahn–Teller effect.
The structures differ in bond parameters, in arrangement of methyl
groups of men ligands, in packing of the chains and in hydrogen
bonds system in 1 and 2. Different bond lengths within [Pt(CN)4]2ꢀ
units in 1 and 2 induce a different local symmetry of these units
Appendix A. Supplementary data
CCDC 784112 and 784113 contain the supplementary crystallo-
graphic data for complexes 1 and 2. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033;
or e-mail: deposit@ccdc.cam.ac.uk.
References
and this manifests itself by different number of m(C„N) vibrations
[1] M. Pilkington, S. Decurtins, in: A. McCleverty, T.J. Meyer (Eds.), Comprehensive
Coordination Chemistry II, vol. 7, Elsevier, Amsterdam, 2004.
in the IR spectra. Wavenumbers of these vibrations are correlated
with Cu–N(cyanido) bond length. Broad, almost symmetric bands
observed in the electronic spectra of 1 and 2, which could be as-
signed to 2B1g ? 2Eg transition confirm a deformed octahedral
coordination of the CuN6 chromophoric groups. Complexes 1 and
[2] K.R. Dunbar, R.A. Heintz, Prog. Inorg. Chem. 45 (1997) 283.
ˇ
ˇ
ˇ ˇ
ˇ
ˇ
[3] J. Cernák, M. Orendác, I. Potocnák, J. Chomic, A. Orendácová, J. Skoršepa, A.
Feher, Coord. Chem. Rev. 224 (2002) 51.
[4] H. Vahrenkamp, A. Geib, G.N. Richardson, J. Chem. Soc., Dalton Trans. (1997)
3643.

278
M. Vavra et al. / Polyhedron 30 (2011) 269–278
ˇ
ˇ ˇ
ˇ
ˇ
[5] I. Potocnák, M. Vavra, E. Cizmár, K. Tibenská, A. Orendácová, D. Steinborn, C.
[24] T. Akitsu, Y. Einaga, Inorg. Chem. 45 (2006) 9826.
[25] Z. Gabelica, Spectrochim. Acta 32A (2) (1976) 337.
[26] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination
Compounds, Part B: Applications in Coordination, Organometallic and
Bioinorganic Chemistry, Wiley, New York, 1997.
}
ˇ
Wagner, M. Dušek, K. Fejfarová, H. Schmidt, T. Muller, M. Orendác, A. Feher, J.
Solid State Chem. 179 (2006) 1965.
ˇ
ˇ ˇ
ˇ
ˇ
[6] I. Potocnák, M. Vavra, E. Cizmár, M. Kajnaková, A. Radváková, D. Steinborn, S.A.
Zvyagin, J. Wosnitza, A. Feher, J. Solid State Chem. 182 (2009) 196.
ˇ ˇ
[7] M. Vavra, I. Potocnák, D. Steinborn, C. Wagner, Acta Cryst. E 62 (2006) m1895.
[27] A.M. Golub, H. Köhler, V.V. Skopenko, Chemistry of Pseudohalides, Elsevier,
Amsterdam, 1986.
ˇ
ˇ ˇ
ˇ
[8] I. Potocnák, M. Vavra, E. Cizmár, M. Dušek, T. Müller, D. Steinborn, Inorg. Chim.
Acta 362 (2009) 4152.
[9] I. Potocnák, M. Vavra, J. Chem. Cryst. 40 (2010) 993.
[10] G.B. Kaufmann, Inorg. Synth. 9 (1967) 182.
[11] O. Kahn, Molecular Magnetism, VCH, New York, 1993.
[12] Oxford Diffraction, Crysalis CCD and Crysalis RED, Oxford Diffraction Ltd.,
Oxford, UK, 2004.
[13] G.M. Sheldrick, SHELXS97 and SHELXL97, University of Gottingen, Gottingen,
Germany, 1997.
ˇ
ˇ
ˇ
[28] J. Kuchár, J. Cernák, Z. Mayerová, P. Kubácek, Z. Zák, Solid State Phenom. 90
(2003) 323.
ˇ ˇ
ˇ
ˇ
ˇ
ˇ
[29] J. Hanko, M. Orendác, J. Kuchár, Z. Zák, J. Cernák, A. Orendácová, A. Feher, Solid
State Commun. 142 (2007) 128.
ˇ
[30] J. Kuchár, J. Cernák, K.A. Abboud, Acta Cryst. C 60 (2004) m492.
[31] M.J. Scott, R.H. Holm, J. Am. Chem. Soc. 116 (1994) 11357.
[32] S. Stoll, A. Schweiger, J. Magn. Reson. 178 (2006) 42.
[33] D. Gatteschi, A. Bencini, Electron Paramagnetic Resonance of Exchange
Coupled Systems, Springer, Berlin, 1990.
}
}
ˇ ˇ
[14] V. Petrícek, M. Dušek, L. Palatinus, JANA2006. The Crystallographic Computing
System, Institute of Physics, Praha, Czech Republic.
[15] K. Brandenburg, DIAMOND, Release 2.1e, Crystal Impact GbR, Bonn, Germany,
2000.
[34] G.A. Baker Jr., G.S. Rushbrooke, H.E. Gilbert, Phys. Rev. 135 (1964) A1272.
[35] A. Meyer, A. Gleizes, J.J. Girend, M. Verdaguer, O. Kahn, Inorg. Chem. 21 (1982)
1729.
[16] R.C. Clark, J.S. Reid, Acta Cryst. A 51 (1995) 887.
[17] T. Akitsu, Y. Einaga, Inorg. Chim. Acta 360 (2007) 497.
[18] T. Akitsu, Y. Endo, Acta Cryst. E 65 (2009) m406.
[19] A. Karadag, A. Senocak, I. Önal, Y. Yerli, E. Sahin, A. Cemil Basaran, Inorg. Chim.
Acta 362 (2009) 2299.
[20] J. Kuchár, J. Cernák, Z. Zák, W. Massa, Progress in Coordination and
Bioinorganic Chemistry, STU Press, Bratislava, 2003. p. 127.
[21] A.B.P. Lever, Inorganic Electronic Spectroscopy, Elsevier, Amsterdam, 1984.
[36] W. Hiller, J. Strähle, A. Datz, M. Hanach, W.E. Hatfield, J. Am. Chem. Soc. 106
(1984) 329.
[37] C.H. Weng, PhD. Thesis, Carnegie-Mellon University, Pittsburgh, PA, 1968.
[38] R. Feyerherm, S. Abens, D. Günther, T. Ishida, M. Meissner, M. Meschke, T.
Nogami, M. Steiner, J. Phys. Condens. Matter 12 (2000) 8495.
ˇ
ˇ
ˇ
[39] D.C. Johnston, R.K. Kremer, M. Troyer, W. Wang, A. Klümper, S.L. Budko, A.F.
Panchula, P.C. Canfield, Phys. Rev. B 61 (2000) 9558.
[40] J.C. Bonner, M.E. Fischer, Phys. Rev. 135 (1964) A640.
[41] W.E. Estes, D.P. Gavel, W.E. Hatfield, D.J. Hodgson, Inorg. Chem. 17 (1978)
1415.
[22] K. Seitz, S. Peschel, D. Babel, Z. Anorg, Allg. Chem. 627 (2001) 929.
ˇ
ˇ
ˇ
[23] J. Cernák, J. Skoršepa, K.A. Abboud, M.W. Meisel, M. Orendác, A. Orendácová, A.
Feher, Inorg. Chim. Acta 326 (2001) 3.