New octahedral, head-tail iron(II) complexes with spin crossover properties

Article abstract of DOI:10.1002/ejic.201101096

The synthesis and characterisation of four new Schiff base-like ligands with long alkyl chains in the outer periphery and their iron(II) complexes with methanol and pyridine as axial ligands is reported. Two of the methanol complexes crystallise in a lipi

Full text of DOI:10.1002/ejic.201101096

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FULL PAPER
DOI: 10.1002/ejic.201101096
New Octahedral, Head–Tail Iron(II) Complexes with Spin Crossover Properties
Stephan Schlamp,[a] Peter Thoma,[a] and Birgit Weber*[a]
Keywords: Iron / Magnetic properties / Schiff bases / Spin crossover / Layered compounds
The synthesis and characterisation of four new Schiff base-
like ligands with long alkyl chains in the outer periphery and
their iron(II) complexes with methanol and pyridine as axial
ligands is reported. Two of the methanol complexes crystal-
lise in a lipid layer-like arrangement with the alkyl chain
(tail) packed in the middle and the iron centres (head) in the
outer sites. The pyridine complexes show varying types of
spin transition (step wise, incomplete, with hysteresis), which
depends on the alkyl chain length and substituents in the
outer periphery of the ligand. Investigations in solution using
1H NMR spectroscopy demonstrate that the differences in the
spin transition behaviour are due to packing effects as the
same transition curve is obtained independently of the alkyl
chain length.
tors.[4] In order to realise application it is important to ex-
plore different possibilities for the nanostructuration of
Introduction
Iron(II) spin crossover (SCO) complexes are a fascinating SCO materials[5] and to investigate if additional properties
class of molecules that can be switched on the molecular can be combined (e.g. liquid crystal behaviour,[6] magnetic
level between the paramagnetic high-spin (HS, S = 2) and exchange interactions)[7] to result in multifunctional SCO
the diamagnetic low-spin (LS, S = 0) state by external per- materials.[3] To this end, we have modified Schiff base-like
turbations such as temperature, pressure or light.[1–3] This ligands used for the synthesis of SCO complexes[2,8] by add-
switching progress is associated with a colour change that ing long alkyl chains to the outer periphery. Such an ap-
results in an interest in this substance class as pressure and/ proach can induce new possibilities for the self-assembly of
or temperature sensors with a simple optical readout or as the complexes in solution or the solid state.[9] Using this
cold channel control units in the food and medical sec- approach, we have succeeded with the synthesis of an
Scheme 1. General procedure for the synthesis of the new ligands and their iron complexes with the abbreviations.
[a] Inorganic Chemistry II, Universität Bayreuth,
iron(II) complex that crystallises in a lipid layer-like struc-
Universitätsstr. 30, 95440 Bayreuth, Germany
ture and shows a cooperative spin transition (ST) with an
Fax: +49-921-552157
E-mail: weber@uni-bayreuth.de
up to 50 K wide hysteresis loop.[10] In order to investigate
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S. Schlamp, P. Thoma, B. Weber
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this interesting new class of iron complexes in more detail Fe–Oax 170° for 2(MeOH) and 167° for 5(MeOH)]. The
we have prepared a series of ligands with varying chain equatorial ligand, with exception of the alkyl chains, is ne-
lengths (n = 7, 11, 15) and varying substituents R1 for n = arly planar for both complexes. In 2(MeOH), one CH3
11 (Scheme 1). The structural and magnetic properties of group (C16) of the ester group is bent out of this plane by
the corresponding iron(II) complexes with methanol and nearly 90°. The plane spanned by the alkyl chains is folded
pyridine as axial ligands are reported here together with the with respect to the plane of the remaining ligand by 23° in
results of temperature (T)-dependent NMR spectroscopy in 2(MeOH) and 19° in 5(MeOH). A further difference be-
solution for selected examples. The influence of the dif- tween the two complexes is the relative orientation of the
ferent alkyl chain lengths and substituents on the crystal alkyl chains. In the case of 2(MeOH) with the slightly larger
packing and ST behaviour is discussed.
R1 substituents, they point outwards with nearly planar C5–
C6–O7–C21 and C8–C7–O8–C33 torsion angles, respec-
tively, and a C21···C33 distance of 5.3 Å. In 5(MeOH), the
alkyl chain starting with C21 is oriented similarly with a
nearly planar C5–C6–O9–C21 torsion angle. However, the
second alkyl chain is bent towards the first chain, which
results in a significantly shorter C21···C33 distance of 4.2 Å
Results and Discussion
Synthesis and General Characterisation
The general procedure for the synthesis of the new li-
gands and their iron complexes and the abbreviations used
are given in Scheme 1. The preparation of the desired octa-
hedral complexes with pyridine as the axial ligands followed
an eight-step synthesis, which started with the conversion
of pyrocatechol with an alkyl bromide according to a modi-
fication of a literature procedure.[11] Nitration,[12,13] subse-
quent reduction to the diaminoproduct[13] and reaction
with different ketoenol ethers[14,15] led to the free ligands
L1–5, which were reacted with iron(II) acetate[16] to give the
iron(II) complexes with methanol as the axial ligands. In
the last step, methanol was replaced by pyridine.
The intermediate products were characterised by elemen-
tal analysis, NMR spectroscopy and mass spectrometry. In
addition, the iron complexes were characterised by T-de-
pendent magnetic susceptibility measurements. For the
methanol complexes 2(MeOH) and 5(MeOH) the struc-
tural details were explored by X-ray structure analysis. For
complexes 1–3(py), T-dependent paramagnetic 1H NMR
measurements were performed in a pyridine/toluene solu-
tion.
Figure 1. ORTEP drawing of the asymmetric unit of 2(MeOH)
with atom labels (anisotropic displacement ellipsoids drawn at 50%
probability level). H atoms omitted for clarity.
Description of the X-ray Structures
Crystallisation of 2(MeOH) and 5(MeOH) succeeded,
and their molecular structures were elucidated. The asym-
metric units of the two complexes are displayed in Figures 1
and 2. The crystallographic data are summarised in Table 4,
and in Table 1 selected bond lengths and angles within the
first coordination sphere are given. Both complexes crystal-
¯
lise in the triclinic space group P1, and the unit cells each
contain two formula units. The cell dimensions of the two
complexes are very similar, in 5(MeOH) the a, c and α, β, δ
values are slightly smaller as is the cell volume. The iron(II)
centres are in the plane of the Schiff base-like equatorial
ligand with bond lengths of about 2.0 Å to the two equato-
rial O atoms and 2.1 Å to the two N atoms. This and the
Oeq–Fe–Oeq angle of 109° clearly indicates the high spin
state of the complexes,[8,15,17] which is confirmed by mag-
netic measurements. The Fe–O distances to the axially co-
ordinating methanol molecules are about 2.2 Å, and the
Figure 2. ORTEP drawing of the asymmetric unit of 5(MeOH)
with atom labels (anisotropic displacement ellipsoids drawn at 50%
Oax–Fe–Oax angles deviate slightly from the ideal 180° [Oax– probability level). H atoms omitted for clarity.
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Octahedral Iron(II) Complexes with Spin Crossover Properties
Table 1. Selected bond lengths [Å] and angles [°] of 2(MeOH) and 5(MeOH) within the first coordination spheres.
Complex
Fe–Neq
Fe–Oeq
Fe–Oax
O1–Fe–O2
Lax–Fe–Lax
2(MeOH)
5(MeOH)
2.093(2), 2.095(2)
2.088(2), 2.094(2)
2.009(1), 2.030(1)
2.007(2), 2.021(2)
2.203(1), 2.230(2)
2.201(2), 2.233(2)
108.93(5)
109.37(8)
169.72(5)
166.73(7)
and a C8–C7–O10–C33 torsion angle of 121°. At the end
of the alkyl chains the C32···C44 distance of 4.0 Å is nearly nected by a hydrogen bond between the hydrogen atom of
identical for both complexes. the methanol OH group of the axial ligand [H9 and H45
Two opposed heads of two neighbouring layers are con-
The molecular packing of the complexes reveals a lipid for 2(MeOH) and 5(MeOH), respectively] and the oxygen
layer-like arrangement as illustrated in Figures 3 and 4 for atom of the carbonyl group coordinated to the iron centre
2(MeOH) and 5(MeOH), respectively. Such an arrange- [O1 and O2 for 2(MeOH) and 5(MeOH), respectively].
ment was recently observed for a very similar pyridine com-
A further hydrogen bond is observed between the heads
plex of the same ligand type.[10] The layers run along the ab within a layer that involves the hydrogen atom of the second
plane and, within one layer, the alkyl chains of the Schiff coordinated methanol molecule and one of the carbonyl
base-like ligand (tail) are packed in the middle and the iron oxygen atoms of the ester group of the ligand [H47···O3 for
centres (heads) are on the outer sides.
2(MeOH) and H7···O5 for 5(MeOH)], which connects the
Figure 3. Packing of the molecules of 2(MeOH) in the crystal projected along [0 1 0]. Hydrogen atoms not involved in the H-bond
network are omitted for clarity.
Figure 4. Packing of the molecules of 5(MeOH) in the crystal projected along [0 1 0]. Hydrogen atoms not involved in the H-bond
network are omitted for clarity.
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S. Schlamp, P. Thoma, B. Weber
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iron centres into infinite chains that run along [1 0 0] in
both complexes. Details of the hydrogen bonds are given in
Tables 2 and 3.
Table 2. Distances [Å] and angles [°] of the hydrogen bonds in
2(MeOH).
2(MeOH)
D–H
H···A
A···D
D–H···A
O9–H9···O1[a]
0.79
0.79
2.04
1.95
2.82
2.72
174
166
O10–H47···O3[b]
[a] –x, –y, 1 – z. [b] –1 + x, y, z.
Table 3. Distances [Å] and angles [°] of the hydrogen bonds in
5(MeOH).
5(MeOH)
D–H
H···A
A···D
D–H···A
O7–H7···O5[a]
0.95
0.95
2.08
2.11
2.7098
2.7402
123
123
O8–H45···O2[b]
[a] 1 + x, y, z. [b] 3 – x, –y, 1 – z.
Magnetic Properties
Magnetic susceptibility measurements were performed
from 300–10 K for all iron(II) complexes with a Quantum
Design MPMSR-2 SQUID magnetometer. The methanol
complexes were HS in the entire temperature range with an
average room temperature magnetic moment of
3.2 cm3 Kmol–1.
Replacement of methanol by pyridine shifts the overall
ligand field strength into a region where the observation of
T-induced ST is possible. Accordingly, all pyridine com-
plexes of L1–5 show SCO behaviour, with different kinds
of ST. The ST properties of 3(py) (hysteresis) have been
published previously.[10] The thermal dependence of the
χMT product (χM = molar susceptibility) for 1(py), 4(py)
and 5(py) is given in Figure 5.
Figure 5. Plots of χMT product vs. T for 1(py) at 0.05 T (a), 4(py)
at 0.05 T (b) and 5(py) at 0.2 T (c).
Complexes 1–3(py) with the same R1 but different chain
lengths are all in the HS state at room temperature. Com- amounts of water molecules are observed in the crystal
plex 1(py) with n = 7 shows a complete and abrupt ST with packing. However, as no X-ray structures are available, no
χMT(300 K)
=
3.41 cm3 Kmol–1 and χMT(50 K)
=
conclusions can be drawn with regard to the possible exis-
0.20 cm3 Kmol–1. The transition temperature (T1/2) is 182 K tence of a hydrogen-bond network.
in the cooling mode and 186 K in the heating mode and
The complexes with different substituents but the same
reveals a 4 K wide hysteresis loop. In contrast to this, 2(py) chain length of n = 11 also display considerable differences
with n = 11 shows a gradual, stepwise and incomplete SCO. in ST behaviour, here also with temperature. For 4(py) the
At room temperature the χMT product is 2.67 cm3 Kmol–1 ST is still stepwise and incomplete but with a higher T1/2
almost completely in the HS state. The T1/2 values are for both steps. At room temperature, χMT
=
168 K and 98 K for the first and second step, respectively. 3.34 cm3 Kmol–1 and the complex is completely in the HS
The χMT product at 50 K with 0.98 cm3 Kmol–1 indicates state. At 50 K, χMT = 1.52 cm3 Kmol–1 and the spin transi-
that about a third of the iron centres are still in the HS tion stops at a plateau with a HS mol fraction (γHS) of ca.
state. The ST properties of 3(py) with n = 15 have already 0.5, which is frequently observed for 1D chain compounds
been reported. A wide hysteresis loop is observed with with this ligand type.[18,19] The T1/2 values of 262 K and
T
1/2ȇ = 222 K and T1/2Ȇ = 245 K.[10] The differences in 113 K are significantly higher than those of 2(py). At
the curve progression can be explained by the different 250 K, 5(py) is in the LS state with a χMT value of about
number of carbon atoms in the chains as the different space 0.50 cm3 Kmol–1. Upon heating, the χMT value continu-
required by the alkyl chains influences the molecular pack- ously increases to 2.21 cm3 Kmol–1 at 350 K, which indi-
ing. The influence of the alkyl chains (and the resulting cates a gradual spin transition that takes place at around
packing effects) on T1/2 appears to be less pronounced. As room temperature (T1/2 ≈ 325). Unfortunately, further heat-
for the already published example of 3(py), different ing led to decomposition, so the pure HS state could not
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Octahedral Iron(II) Complexes with Spin Crossover Properties
be reached. The different R1 substituents influence both for the solution NMR experiments.[20] Both parts of the
T1/2 and the curve progression. Investigations in solution complexes (head and tail) are soluble in this solvent mix-
on similar pyridine complexes without the alkyl chains indi- ture, and no indication of self-assembly in solution was ob-
cate that variations in R1 have a marginal influence on served. Sealed samples were measured in from 360–185 K
T1/2 in solution.[20] Thus the differences in the ST behaviour every 5 K beginning at high temperature. The assignment of
are mainly related to packing effects.
the resonances was accomplished by comparison to known
results for complexes without alkyl chains[20] or with hy-
droxy groups.[25] The assignment of the three iron(II) com-
plexes at room temperature is displayed in Figure 6. The
shifts of the CH2 group b and the CH3 groups a and c are
clearly visible and distinguishable from all the other alkyl
and solvent signals. Integration of the signals gave the ex-
pected values of 2:3:3 for the ethyl group at the ester unit
and the methyl group on the carbonyl unit directly attached
to the iron(II) centre. It can be assumed that no pentacoor-
dinate species are present due to the high excess of pyridine
in the solution. All other signals of the complex were not
assigned because of overlap in the alkyl region and/or bad
resolution in a region away from the main spectra (olefinic
HC–N protons).[20]
1
Paramagnetic H NMR Spectroscopy
In order to more clearly evaluate the influence of packing
effects on the SCO properties, 1(py), 2(py) and 3(py) (n =
7, 11 and 15, respectively) were investigated by paramag-
netic 1H NMR measurements in solution. Evans method[21]
is a powerful technique to determine the spin state of a
complex in solution, however, it has some disadvantages,
e.g. relatively high error,[22] which depends on the concen-
tration of the sample. We have shown[18,20,23–25] that the
SCO of iron(II) complexes can be investigated in solution
using the isotropic shift, which is an extraordinary improve-
ment as the same results can be obtained with minor labo-
ratory complexity.
Complexes 1–3(py) were dissolved in a pyridine/toluene
mixture (1:1) to ensure the formation of octahedral com-
plexes due to the excess of pyridine. Toluene was used as a
noncoordinating solvent to realise a wide temperature range
Figure 7. Temperature dependence of the chemical shifts of the sig-
nals a–c of 2(py). Signals are marked with a diamond (a), star (b)
and filled circle (c) to illustrate the temperature-dependent shift of
the signals. One paramagnetic impurity is marked with an arrow. S
denotes the solvent pyridine/toluene.
Figure 6. Assignment of the NMR resonances for a) 1(py), b) 2(py)
and c) 3(py) at room temp. S denotes the solvent pyridine/toluene.
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The T-dependent 1H spectra of 2(py) are displayed in not influence the ST properties in solution (T1/2 ≈ 225 K in
Figure 7. The roaming of the monitored signals is clearly all cases). Thus all the differences observed in the solid state
visible. Correction of these shifts by the diamagnetic shifts are due to packing effects.
of the free ligand signals gives the paramagnetic (or iso-
tropic) shift that can be plotted vs. inverse T as shown in
Figure 8 (a) for 1(py) for the three ligand signals. As shown
Conclusions
before,[18,20,23–25] the isotropic shift moves starting at high
We have reported the synthesis and characterisation of
temperatures towards the more paramagnetic region and
shows the Curie behaviour expected for an iron(II) HS com-
five new Schiff base-like ligands and their iron(II) com-
plexes with pyridine or methanol as axial ligands. A special
feature of the ligands is the introduction of long alkyl
chains in the outer sphere that results in the head–tail char-
plex. This behaviour changes below T = 255 K (1/T =
3.9ϫ103 K–1). Upon further cooling, the paramagnetic
shifts move to zero, which is the value expected for a pure
acter of the complexes. For three complexes of these li-
LS complex.
gands, we have been able to obtain single crystals of a high
enough quality to perform X-ray structure analysis.[10] The
structure bearing motif is in all cases a lipid layer-like ar-
rangement of the molecules where the alkyl chains (tails)
are packed in the middle and the iron centres (heads) are
on the outer sides. In all cases, a network of hydrogen bonds
is observed between the layers. Further investigations are
needed to verify if this motif is always obtained or if certain
structural preconditions are necessary (certain ratio of
length of alkyl chain/size of head). At the moment, the later
possibility is more likely as with larger pyridine as the axial
ligands the complex with n = 15 crystallised, whereas with
smaller methanol two complexes with n = 11 crystallised.
Of the complexes with pyridine, the SCO properties are
strongly influenced by the different alkyl chain lengths in
the solid state, whereas in solution the same transition curve
is obtained independent of n. Because of the lack of struc-
tural information for all those complexes, no structure–
function relationships have been identified. However, the in-
crease in the alkyl chain length does not necessarily lead
to a decrease of cooperative interactions during the spin
transition. A network of hydrogen bonds between the lipid
layers appears to be enough for the transmission of cooper-
ative effects.[10]
Experimental Section
General: The synthesis of the iron complexes was carried out under
an argon atmosphere using Schlenk techniques. The solvents were
purified as described in the literature[26] and distilled under an at-
Figure 8. a) Isotropic shift of 1(py) plotted vs. 1/T for the three
mosphere of argon. When argon is used for the synthesis of the
monitored ligand signals, b) γHS for the three monitored ligand sig-
intermediate products, it is described in the text. Alkylbromides
nals of 1(py) plotted vs. T and c) γHS of 1–3(py) plotted vs. T.
were commercial products (Sigma–Aldrich) and used as received.
The synthesis of 3(py) and its precursers,[10] ethoxymethylene-
ethylacetoacetate (D),[27] ethoxymethyleneacetylacetone (E),[27]
Multiplying the isotropic shift with T and normalizing
methoxymethylenemethylacetoacetate (F)[15] and iron(II) acetate[16]
the values to one gave γHS as shown in part b of Figure 8
are described in the literature.
plotted vs. T. The observed ST behaviour of the three moni-
tored signals is nearly identical, and for further comparison
the average of the three signals was used. Comparison of
1,2-Dioctyloxybenzene (A1): In a three neck round-bottomed flask
(1 L) fitted with a condenser and a dropping funnel, catechol (25 g,
227.0 mmol, 1 equiv.) and K2CO3 (78.45 g, 567.7 mmol, 2.5 equiv.)
1(py), 2(py) and 3(py) in Figure 8 (c) shows the same trend
were stirred at room temperature in N,N-dimethylformamide
for all of the complexes. For 3(py), the complete data are
not shown due to its low solubility at low temperatures. For
the other two complexes, the complete ST can be followed
using this method. The curve progression is nearly identical,
(DMF, 350 mL) for 1 h under a nitrogen atmosphere. 1-Bromo-
octane (109.62 g, 567.7 mmol, 2.5 equiv.) was added dropwise to
the turquoise suspension, and the mixture was heated to 80 °C for
12 h. The suspension was poured into a separatory funnel and H2O
which demonstrates that the length of the alkyl chain does (250 mL) and ethyl ether (400 mL) were added. The solid was re-
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Octahedral Iron(II) Complexes with Spin Crossover Properties
moved, the DMF/H2O phase was separated from the ether phase
and washed twice with ether (ca. 150 mL). The combined ether
phases were washed twice with H2O (150 mL) and the solvent was
removed in vacuo. Distillation gave A1 at about 2.0ϫ10–4 bar and
160 °C as a colourless liquid; yield 71.3 g (94%). C22H38O2
(334.54): calcd. C 78.99, H 11.45; found C 79.29, H 12.39. 1H
NMR (399.81 MHz, CDCl3, 296 K): δ = 0.87 (t, J = 7.0 Hz, 6 H,
H 9.76, N 5.22; found C 66.92, H 9.87, N 5.34. MS (DEI+): m/z
(%) = 537 (100) [M]+. 1H NMR (399.81 MHz, CDCl3, 296 K): δ =
0.86 (t, J = 7.0 Hz, 6 H, CH3), 1.14–1.39 (m, 32 H, CH2), 1.39–
1.50 (m, 4 H, CH2), 1.78–1.90 (m, 4 H, CH2), 4.07 (t, J = 6.6 Hz,
4 H, CH2-O), 7.27 (s, 2 H, Har) ppm. 13C (100.53 MHz, CDCl3,
296 K): 14.1 (CH3), 22.7 (CH2), 25.8 (CH2), 28.7 (CH2), 29.2
(CH2), 29.4 (CH2), 29.5 (CH2), 29.6 (2 CH2), 29.7 (CH2), 31.9
CH3), 1.22–1.39 (m, 16 H, CH2), 1.41–1.51 (m, 4 H, CH2), 1.75– (CH2), 70.2 (CH2, CH2O), 107.8 (CH, Car), 136.4 (Cq, Car–NO2),
1.85 (m, 4 H, CH2), 3.98 (t, J = 6.7 Hz, 4 H, CH2O), 6.87 (s, 4 H, 151.8 (Cq, Car–O). 1H NMR (399.81 MHz, C6D6, 296 K): δ = 1.32
Har) ppm. 13C NMR (100.53 MHz, CDCl3, 296 K): δ = 14.1 (CH3), (t, J = 6.8 Hz, 6 H, CH3), 1.58–1.78 (m, 36 H, CH2), 1.83–1.92 (m,
22.7 (CH2), 26.0 (CH2), 29.3 (2 CH2), 29.4 (CH2), 31.8 (CH2), 69.2
(CH2, CH2O), 114.1 (CH, Car), 121.0 (CH, Car), 149.2 (Cq, Car–O)
ppm.
4 H, CH2), 3.62 (t, J = 5.8 Hz, 4 H, CH2O), 7.54 (s, 2 H, Har) ppm.
13C NMR (100.53 MHz, C6D6, 296 K): δ = 14.3 (CH3), 23.1 (CH2),
26.2 (CH2), 28.9 (CH2), 29.6 (CH2), 29.8 (CH2), 30.0 (CH2), 30.1
(2 CH2), 30.2 (CH2), 32.3 (CH2), 69.5 (CH2, CH2-O), 107.6 (CH,
Car), 136.8 (Cq, Car–NO2), 151.7 (Cq, Car–O) ppm.
1,2-Didodecyloxybenzene (A2): In a three neck round-bottomed
flask (1 L) fitted with a condenser and a dropping funnel, catechol
(25 g, 227.0 mmol, 1 equiv.) and K2CO3 (62.75 g, 454.0 mmol,
2 equiv.) were stirred at room temperature in DMF (600 mL) for
50 min under a nitrogen atmosphere. 1-Bromododecane (113.14 g,
454.0 mmol, 2 equiv.) was added dropwise to the turquoise suspen-
sion. After stirring for 20 min at room temperature, the mixture
was heated to 80 °C for 7 h and stored at –25 °C. The white precipi-
tate was collected by filtration and washed with plenty of water.
A2 was recrystallised from ethanol (500 mL), collected by filtration,
1,2-Diamino-4,5-dioctyloxybenzene (C1): Under an argon atmo-
sphere, B1 (17.7 g, 41.7 mmol) and Pd on activated charcoal (2.6 g,
10%) were suspended in ethanol (250 mL) for 10 min. Hydrazine
monohydrate (62.6 g, 1250.0 mmol, 30 equiv.) was added dropwise
over 30 min. The mixture was heated to reflux for 2 h, and the
colour turned from purple to yellow. Slightly warm, the mixture
was filtered through Celite® 545 coarse and stored at 5 °C over-
night. After the resulting yellow solid was collected by filtration, it
washed with methanol and dried in vacuo; yield 79.0 g (78%). was hydrated again by the same procedure with hydrazine monohy-
C30H54O2 (446.75): calcd. C 80.65, H 12.18; found C 80.53, H drate (31 g) and Pd on activated charcoal (1.3 g) in ethanol
11.55. MS (DEI+): m/z (%) = 447 (100) [M]+, 278 (10), 110 (55). (200 mL) to obtain C1 as a white powder; yield 8.2 g (59%).
1H NMR (399.81 MHz, CDCl3, 296 K): δ = 0.87 (t, J = 6.9 Hz, 6
H, CH3), 1.18–1.38 (m, 32 H, CH2), 1.39–1.50 (m, 4 H, CH2), 1.74–
C22H40N2O2 (364.57): calcd. C 72.48, H 11.06, N 7.68; found
C 72.72, H 10.67, N 7.54. H NMR (399.81 MHz, CDCl3, 296 K):
1
1.84 (m, 4 H, CH2), 3.97 (t, J = 6.7 Hz, 4 H, CH2O), 6.87 (s, 4 H, δ = 0.86 (t, J = 7.1 Hz, 6 H, CH3), 1.16–1.36 (m, 16 H, CH2), 1.36–
Har) ppm. 13C NMR (100.53 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 1.46 (m, 4 H, CH2), 1.64–1.77 (m, 4 H, CH2), 3.15 (br, 4 H, NH2),
22.7 (CH2), 26.1 (CH2), 29.3 (CH2), 29.4 (CH2), 29.5 (CH2), 29.6/ 3.86 (t, J = 6.7 Hz, 4 H, CH2-O), 6.35 (s, 2 H, Har) ppm. 13C NMR
29.6 (2 CH2), 29.7/29.7 (2 CH2), 31.9 (CH2), 69.3 (CH2, CH2-O),
114.1 (CH, Car), 121.0 (CH, Car), 149.2 (Cq, Car–O) ppm.
(100.53 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 22.7 (CH2), 26.1
(CH2), 29.3 (CH2), 29.4 (CH2), 29.6 (CH2), 31.8 (CH2), 70.7 (CH2,
CH2O), 106.7 (CH, Car), 128.4 (Cq, Car–NH2), 143.4 (Cq, Car–O)
ppm.
1,2-Dinitro-4,5-dioctyloxybenzene (B1): A1 (34.15 g, 102.0 mmol)
was dissolved in acetic acid (130 mL) and nitric acid (50 mL, 65%)
was added dropwise over 45 min. The solution became yellow and
solidified, and the temperature was increased to 45 °C. Fuming ni-
tric acid (115 mL) was added dropwise over 45 min, whereby the
reaction mixture became liquid again, and the temperature was in-
creased to 65 °C. After 2 h stirring, the solution was poured into
iced water (750 mL), and the resulting yellow solid was collected
by filtration and washed with water until neutral. B1 was recrystal-
lised from ethanol (450 mL), filtered, washed with methanol and
dried in vacuo; yield 29.0 g (67%). C22H36N2O6 (424.53): calcd. C
1,2-Diamino-4,5-didodecyloxybenzene (C2): Under an argon atmo-
sphere, B2 (41.6 g, 77.5 mmol) was stirred at room temperature
with Pd on activated charcoal (7.5 g) in ethanol (1.1 L) for 10 min.
Hydrazine monohydrate (147.7 g, 7392.8 mmol, 37 equiv.) was
added dropwise over 1 h, and the mixture was heated to reflux for
2 h until the colour turned to white. The mixture was filtered hot
through Celite® 545 coarse and stored at 5 °C overnight. C2, a
white solid, was collected by filtration and dried in vacuo; yield
33.1 g (90%). C30H56N2O2 (476.78): calcd. C 75.57, H 11.84, N
62.24, H 8.55, N 6.60; found C 62.22, H 9.33, N 6.69. 1H NMR 5.88; found C 75.41, H 11.75, N 5.95. MS (DEI+): m/z (%) = 477
(399.81 MHz, CDCl3, 296 K): δ = 0.87 (t, J = 7.0 Hz, 6 H, CH3), (100) [M]+, 139 (50). H NMR (399.81 MHz, CDCl3, 296 K): δ =
1
1.07–1.39 (m, 16 H, CH2), 1.39–1.51 (m, 4 H, CH2), 1.78–1.90 (m,
0.86 (t, J = 7.0 Hz, 6 H, CH3), 1.14–1.35 (m, 32 H, CH2), 1.36–
4 H, CH2), 4.08 (t, J = 6.5 Hz, 4 H, CH2O), 7.27 (s, 2 H, Har) 1.46 (m, 4 H, CH2), 1.66–1.77 (m, 4 H, CH2), 3.15 (br, 4 H, NH2),
ppm. 13C NMR (100.53 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 22.6 3.86 (t, J = 6.6 Hz, 4 H, CH2-O), 6.35 (s, 2 H, Har) ppm. 13C NMR
(CH2), 25.8 (CH2), 28.7 (CH2), 29.2 (2 CH2), 31.7 (CH2), 70.2 (100.53 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 22.7 (CH2), 26.1
(CH2, CH2O), 107.9 (CH, Car), 136.5 (Cq, Car–NO2), 151.8 (Cq, (CH2), 29.4 (CH2), 29.5 (CH2), 29.4 (CH2), 29.6 (CH2), 29.7 (3
Car–O) ppm.
CH2), 31.9 (CH2), 70.7 (CH2, CH2O), 106.8 (CH, Car), 138.3 (Cq,
Car–NH2), 143.4 (Cq, Car–O) ppm.
4,5-Didodecyloxy-1,2-dinitrobenzene (B2): A2 (45.6 g, 102 mmol)
was dissolved in acetic acid (480 mL) over several hours. Nitric acid
(25 mL, 65%) and then fuming nitric acid (300 mL) were added
dropwise. Slight warming at times was necessary to ensure that
continuous stirring was possible. The reaction mixture was stirred
for 20 h at room temperature and poured slowly with vigorous stir-
ring into iced water (2 L). The yellow solid was collected by fil-
tration, washed with water until neutral and dried overnight.
Recrystallisation from ethanol (700 mL) gave B2 as a bright yellow
powder; yield 41.6 g (76%). C30H52N2O6 (536.74): calcd. C 67.13,
Diethyl (2E,2ЈE)-2,2Ј-{[4,5-Bis(octyloxy)-1,2-phenylene]bis[imino-
(E)-methylylidene]}bis(3-oxobutanoate) (L1): Under an argon atmo-
sphere, C1 (2.76 g, 7.6 mmol) was diluted in ethanol (40 mL) and
D (3.1 g, 16.7 mmol, 2.2 equiv.) was added. The yellow mixture was
heated to reflux for 1.5 h and stored at –30 °C. The yellow solid
was collected by filtration and recrystallised twice from ethanol
(25 mL); yield 2.53 g (52%). C36H56N2O8 (644.84): calcd. C 67.05,
H 8.75, N 4.34; found C 67.00, H 9.07, N 4.52. 1H NMR
(399.81 MHz, CDCl3, 296 K): δ = 0.86 (t, J = 6.5 Hz, 6 H, CH3),
Eur. J. Inorg. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
7

Job/Unit: A11096
/KAP1
Date: 07-12-11 16:36:29
Pages: 11
S. Schlamp, P. Thoma, B. Weber
FULL PAPER
1.20–1.34 (m, 16 H, CH2), 1.29 [t, J = 7.5 Hz, 6 H, CH3(Et)], 1.38– (CH2), 31.0 (CH3), 31.9 (CH2), 51.2 (CH3), 70.0 (CH2, CH2O),
1.52 (m, 4 H, CH2), 1.73–1.86 (m, 4 H, CH2), 2.51 (s, 6 H, CH3), 103.4 (Cq), 106.4 (CH, Car), 124.8 (Cq, Car–N), 148.5 (Cq, Car–O),
3.98 (t, J = 6.3 Hz, 4 H, CH2O), 4.22 [q, J = 7.5 Hz, 4 H, CH2(Et)], 154.1 (CH), 167.2 (O–C=O), 200.1 (C=O) ppm.
6.72 (s, 2 H, Har), 8.23 (d, J = 12.5 Hz, 2 H, CH=), 12.83 (d, NH,
L1-Iron(II)·2MeOH [1(MeOH)]: L1 (3.48 g, 5.4 mmol) was reacted
J = 12.5 Hz, 2 H) ppm. 13C NMR (100.53 MHz, CDCl3, 296 K):
with Fe(OAc)2 (2.0 g, 11.5 mmol, 2.1 equiv.) in methanol (100 mL)
δ = 14.0 (CH3), 14.4 (CH3), 22.7 (CH2), 26.0 (CH2), 29.2 (2 CH2),
under reflux conditions for 1 h. After cooling to room temperature,
29.3 (CH2), 31.1 (CH3), 31.8 (CH2), 60.0 [CH2, CH2(Et)], 70.0
black needles were isolated, washed twice with methanol (10 mL)
(CH2, CH2-O), 103.7 (Cq), 106.5 (CH, Car), 124.8 (Cq, Car–N),
and dried under vacuum; yield 3.14 g (76%). C38H62FeN2O10
148.4 (Cq, Car–O), 154.1 (CH), 166.8 (O–C=O), 200.1 (C=O) ppm.
(762.75): calcd. C 59.84, H 8.19, N 3.67; found C 60.05, H 7.70,
N 3.97.
Diethyl (2E,2ЈE)-2,2Ј-{[4,5-Bis(dodecyloxy)-1,2-phenylene]bis[imino-
(E)-methylylidene]}bis(3-oxobutanoate) (L2): Under an argon atmo-
sphere, C2 (5.0 g, 10.5 mmol) was diluted in ethanol (90 mL) and
D (4.3 g, 23.1 mmol, 2.2 equiv.) was added. The yellow mixture was
heated to reflux for 1.5 h and stored at –30 °C. The yellow solid
was collected by filtration, washed with ethanol and recrystallised
from ethanol (60 mL); yield 6.9 g (87%). C44H72N2O8 (757.05):
calcd. C 69.81, H 9.59, N 3.70; found C 69.67, H 9.43, N 3.60. MS
(DEI+): m/z (%) = 757 (100) [M]+, 711 (22), 627 (20), 285 (17). 1H
NMR (299.83 MHz, CDCl3, 296 K): δ = 0.85 (t, J = 6.8 Hz, 6 H,
CH3), 1.17–1.36 (m, 32 H, CH2), 1.29 [t, J = 7.1 Hz, 6 H, CH3(Et)],
1.38–1.51 (m, 4 H, CH2), 1.73–1.86 (m, 4 H, CH2), 2.51 (s, 6 H,
CH3), 3.98 (t, J = 6.6 Hz, 4 H, CH2O), 4.22 [q, J = 7.1 Hz, 4 H,
CH2(Et)], 6.72 (s, 2 H, Har), 8.24 (d, J = 12.5 Hz, 2 H, CH=), 12.83
(d, NH, J = 12.5 Hz, 2 H) ppm. 13C NMR (75.39 MHz, CDCl3,
296 K): δ = 14.1 (CH3), 14.4 (CH3), 22.6 (CH2), 26.0 (CH2), 29.2
(CH2), 29.3 (2 CH2), 29.6 (3 CH2), 29.7 (CH2), 31.1 (CH3), 31.9
(CH2), 60.0 [CH2, CH2(Et)], 70.0 (CH2, CH2O), 103.7 (Cq), 106.5
(CH, Car), 124.8 (Cq, Car–N), 148.4 (Cq, Car–O), 154.1 (CH), 166.8
(O–C=O), 200.1 (C=O) ppm.
L2-Iron(II)·2MeOH [2(MeOH)]: L2 (0.72 g, 1.0 mmol) was reacted
with Fe(OAc)2 (0.40 g, 2.3 mmol, 2.4 equiv.) in methanol (80 mL)
under reflux conditions for 1 h. After cooling to room temperature,
black crystals were isolated, which were collected by filtration,
washed twice with methanol (10 mL) and dried under vacuum;
yield 0.68 g (78%). C46H78FeN2O10 (874.96): calcd. C 63.14,
H 8.99, N 3.20; found C 62.72, H 8.72, N 3.20. MS (DEI+): m/z
(%) = 811 (100) [M – 2 MeOH]+. Crystals suitable for X-ray struc-
ture analysis were obtained.
L4-Iron(II) (4): L4 (0.49 g, 0.7 mmol) was reacted with Fe(OAc)
(0.21 g, 1.2 mmol, 1.7 equiv.) in methanol (60 mL) under reflux
2
conditions for 70 min. After cooling, a brown solid precipitated,
which was collected by filtration, washed twice with methanol
(15 mL) and dried in vacuo; yield 0.36 g (69%). C42H66FeN2O6
(750.83): calcd. C 67.19, H 8.86, N 3.73; found C 67.13, H 9.13,
N 3.85. MS (DEI+): m/z (%) = 750 (100) [M]+.
L5-Iron(II)·2MeOH [5(MeOH)]: L5 (3 g, 4.1 mmol) was reacted
with Fe(OAc)2 (1.35 g, 7.0 mmol, 1.7 equiv.) in methanol (80 mL)
under reflux conditions for 90 min. After cooling to room tempera-
ture, black needles precipitated, which were collected by filtration,
washed twice with methanol (10 mL) and dried under reduced pres-
sure; yield 3.1 g (89%). C44H74FeN2O10 (846.91): calcd. C 62.40,
H 8.81, N 3.31; found C 62.15, H 9.03, N 3.37. Crystals suitable for
X-ray structure analysis were obtained.
3,3Ј-{[4,5-Bis(octyloxy)-1,2-phenylene]bis(iminomethylylidene)}di-
pentane-2,4-dione (L4): Under an argon atmosphere, C2 (1.45 g,
3.0 mmol) was diluted in ethanol (180 mL) and E (1.0 g, 6.6 mmol,
2.2 equiv.) was added. The mixture was heated to reflux for 1 h and
stored at –30 °C. The yellow solid was collected by filtration,
washed with ethanol and recrystallised from ethanol (100 mL);
yield 0.86 g (41%). C42H68N2O6 (697.00): calcd. C 72.37, H 9.83,
N 4.02; found C 72.27, H 9.90, N 4.06. MS (DEI+): m/z (%) = 687
L1-Iron(II)·2py [1(py)]: Compound 1(MeOH) (0.3 g, 0.4 mmol) was
dissolved in pyridine (7 mL) and heated to reflux for 1 h. After
cooling to room temperature, water (1 mL) was added. The ob-
tained precipitate was collected by filtration and drying in vacuo
gave the product as
C46H64FeN4O8·H2O (874.88): calcd. C 63.15, H 7.60, N 6.40; found
1
(100) [M]+. H NMR (299.83 MHz, CDCl3, 296 K): δ = 0.85 (t, J
= 6.6 Hz, 6 H, CH3), 1.16–1.39 (m, 32 H, CH2), 1.39–1.52 (m, 4
H, CH2), 1.74–1.87 (m, 4 H, CH2), 2.31 (s, 6 H, CH3), 2.51 (s, 6
H, CH3), 3.99 (t, J = 6.6 Hz, 4 H, CH2-O), 6.71 (s, 2 H, Har), 7.98
(d, J = 12.2 Hz, 2 H, CH=), 12.82 (d, NH, J = 12.2 Hz, 2 H) ppm.
13C NMR (79.39 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 22.7 (CH2),
26.0 (CH2), 27.5 (CH3), 29.2 (CH2), 29.3 (CH2), 29.4 (CH2), 29.6
(3 CH2), 29.7 (CH2), 31.9 (CH3), 70.1 (CH2, CH2-O), 106.9 (CH,
Car), 114.2 (Cq), 125.0 (Cq, Car–N), 148.7 (Cq, Car–O), 154.1 (CH),
194.6 (C=O), 201.2 (C=O) ppm.
a black solid; yield 0.29 g (83%).
C 62.92, H 7.11, N 6.42.
L2-Iron(II)·2py [2(py)]: Compound 2(MeOH) (0.48 g, 0.6 mmol)
was treated with pyridine (9 mL) for 45 min under reflux condi-
tions. After cooling, water (2.3 mL) was added, and the mixture
heated again to reflux for 2 min. Within 2 d of storage at 4 °C,
black crystals were formed. The product was collected by filtration
and dried in vacuo; yield 0.28 g (53%). C54H80FeN4O8·0.5H2O
(978.09): calcd. C 66.31, H 8.35, N 5.73; found C 66.27, H 8.87,
N 5.53.
Dimethyl
(2E,2ЈE)-2,2Ј-{[4,5-Bis(dodecyloxy)-1,2-phenylene]bis-
[imino-(E)-methylylidene]}bis(3-oxobutanoate) (L5): Under an ar-
gon atmosphere, C2 (5.0 g, 10.5 mmol) was diluted in ethanol
(90 mL) and F (4.0 g, 23.2 mmol, 2.2 equiv.) was added. The yellow
mixture was heated to reflux for 1.5 h and stored at –30 °C. The
yellow solid was collected by filtration, washed with ethanol and
recrystallised from ethanol (60 mL); yield 7.0 g (91%). C42H68N2O8
(729.00): calcd. C 69.20, H 9.40, N 3.84; found C 69.03, H 9.35,
N 3.87. 1H NMR (299.83 MHz, CDCl3, 296 K): δ = 0.85 (t, J =
6.7 Hz, 6 H, CH3), 1.15–1.39 (m, 32 H, CH2), 1.39–1.52 (m, 4 H,
CH2), 1.73–1.87 (m, 4 H, CH2), 2.52 (s, 6 H, CH3), 3.75 (s, 6 H,
L4-Iron(II)·2py [4(py)]: Compound 4 (0.3 g, 0.4 mmol) was treated
with pyridine (7 mL) for 45 min under reflux conditions. After
cooling to room temperature, water (1 mL) was added. The ob-
tained precipitate was collected by filtration and drying in vacuo
gave the product as
C52H76FeN4O6 (909.03): calcd. C 68.71, H 8.43, N 6.16; found
C 68.53, H 8.31, N 6.48.
a black solid; yield 0.26 g (72%).
CH3), 3.98 (t, J = 6.3 Hz, 4 H, CH2O), 6.72 (s, 2 H, Har), 8.23 (d, L5-Iron(II)·2py [5(py)]: Compound 5(MeOH) (0.44 g, 0.5 mmol)
J = 12.3 Hz, 2 H, CH=), 12.87 (d, NH, J = 12.3 Hz, 2 H) ppm.
was treated with pyridine (10 mL) for 1 h under reflux conditions.
13C NMR (75.39 MHz, CDCl3, 296 K): δ = 14.1 (CH3), 22.7 (CH2), After cooling, water (2.4 mL) was added, and the mixture heated
26.0 (CH2), 29.2 (CH2), 29.3 (CH2), 29.4 (CH2), 29.6 (3 CH2), 29.7 again to reflux for 2 min. A red-brown fine crystalline powder was
8
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: A11096
/KAP1
Date: 07-12-11 16:36:29
Pages: 11
Octahedral Iron(II) Complexes with Spin Crossover Properties
formed at 4 °C, which was collected by filtration and dried in
vacuo; yield 0.28 g (67%). C52H76FeN4O8·0.5H2O (950.04): calcd.
C 65.74, H 8.17, N 5.90; found C 65.67, H 8.22, N 5.87.
rected for Lorentz and polarisation effects. The structure was
solved by direct methods (Sir 97)[28] and refined by full-matrix le-
ast-square techniques against F0 (SHELXL-97).[29] The hydrogen
2
atoms were included at calculated positions with fixed displacement
parameters. All non-hydrogen atoms were refined anisotropically.
ORTEP-III[30] was used for the structure representation, Schakal-
99[31] and Mercury[32] for the representation of the molecule pack-
ing.
NMR Spectroscopy: [D8]toluene (D, 99.50%), [D5]pyridine (D,
99.50%), [D6]benzene (D, 99.50%) and CDCl3 (D, 99.80%) were
purchased from Euriso-top. Solvents for organic compounds (C6D6
and CDCl3) were degassed and stored over molecular sieves. Sam-
ples were prepared using 5 mm tubes and Schlenk techniques (con-
centration ca. 5–10%). The solvent for the paramagnetic 1H NMR
investigations was a [D8]toluene/[D5]pyridine mixture (50:50, v/v),
which was degassed using at least seven pump–freeze cycles and
stored under argon. The NMR samples of the iron(II) complexes
(ca. 15 mg in 0.6 mL of solvent) were prepared in 5 mm tubes under
argon using Schlenk techniques and degassed using pump–freeze
cycles prior to sealing with a butane gas burner. The NMR spectra
were recorded with Varian Inova 300 and 400 spectrometers at
23 °C (organic compounds) or variable temperatures [–93 °C to
+87 °C, iron(II) complexes]. Chemical shifts are given relative to
Me4Si, δ1H(CHCl3) = 7.24, δ1H(C6D5H) = 7.15, δ1H(C6D5CD2H)
= 2.03; Me4Si, δ1H(CDCl3) = 77.0, δ1H(C6D6) = 128.0 ppm.
CCDC-847611 [for 2(MeOH)] and -847612 [for 5(MeOH)] contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Elemental Analysis: Elemental analysis was performed with a
VarioEL III CHN instrument using tin boats purchased from Ele-
mentar and Acetanilid (Merck) as a standard.
Mass Spectrometry: Mass spectra were recorded with a Varian
MAT CH7 instrument (direct inlet system, electron impact ioni-
sation 70 eV) or a Jeol MS-700 instrument.
Magnetic Susceptibilities: Data for 1–5(py) were collected with a
Quantum Design MPMSR2 SQUID magnetometer under an ap-
plied field of 0.05, 0.1 and 0.2 T over 10–400 K in the sweep mode.
All samples were placed in gelatine capsules held within plastic
straws. The data were corrected for the diamagnetic magnetisation
of the ligands, which were estimated using Pascal’s constants, and
the sample holder.
Acknowledgments
Support from the University of Bayreuth, the Deutsche For-
schungsgemeinschaft (DFG) (WE 3546_4-1) and the Fonds der
Chemischen Industrie is gratefully acknowledged. We thank P.
Mayer (University of Munich) for collection of the X-ray data of
2(MeOH).
X-ray Diffraction: The intensity data of 2(MeOH) were collected
with a Nonius Kappa CCD diffractometer using graphite-mono-
chromated Mo-Kα radiation (Table 4). The intensity data of
5(MeOH) were collected with a Stoe IPDS II diffractometer using
graphite-monochromated Mo-Kα radiation. The data were cor-
[1] a) P. Gütlich, A. Hauser, H. Spiering, Angew. Chem. 1994, 106,
2109; Angew. Chem. Int. Ed. Engl. 1994, 33, 2024–2054; b) Spin
Crossover in Transition Metal Compounds I–III (Eds.: P.
Gütlich, H. Goodwin), Springer, Berlin/Heidelberg, 2004; c) J.-
F. Letard, J. Mater. Chem. 2006, 16, 2550–2559; d) O. Sato, J.
Tao, Y.-Z. Zhang, Angew. Chem. 2007, 119, 2200; Angew.
Chem. Int. Ed. 2007, 46, 2152–2187; e) J. A. Kitchen, S.
Brooker, Coord. Chem. Rev. 2008, 252, 2072–2092; f) M. A.
Halcrow, Coord. Chem. Rev. 2009, 253, 2493–2514; g) K. S.
Murray, Aust. J. Chem. 2009, 62, 1081; h) S. Brooker, J. A.
Kitchen, Dalton Trans. 2009, 7331–7340; i) A. B. Koudriavtsev,
W. Linert, J. Struct. Chem. 2010, 51, 335–365; j) M. A.
Halcrow, Chem. Soc. Rev. 2011, 40, 000–000.
[2] B. Weber, Coord. Chem. Rev. 2009, 253, 2432–2449.
[3] A. Gaspar, M. Seredyuk, P. Gütlich, J. Mol. Struct. 2009, 924–
926, 9–19.
[4] a) J.-F. Létard, P. Guionneau, L. Goux-Capes, in: Spin Cross-
over in Transition Metal Compounds I–III, Topics in Current
Chemistry, 233–235 (Eds.: P. Gütlich, H. Goodwin), Springer,
Berlin/Heidelberg, 2004, pp. 221–249; b) Y. Garcia, V. Kseno-
fontov, S. Mentior, M. M. Dîrtu, C. Gieck, A. Bhatthacharjee,
P. Gütlich, Chem. Eur. J. 2008, 14, 3745–3758.
[5] a) I. Boldog, A. B. Gaspar, V. Martínez, P. Pardo-Ibañez, V.
Ksenofontov, A. Bhattacharjee, P. Gütlich, J. A. Real, Angew.
Chem. 2008, 120, 6533; Angew. Chem. Int. Ed. 2008, 47, 6433–
6437; b) S. Cobo, G. Molnár, J. A. Real, A. Bousseksou, An-
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5786–5789; c) G. Molnár, S. Cobo, J. A. Real, F. Carcenac, E.
Daran, C. Vieu, A. Bousseksou, Adv. Mater. 2007, 19, 2163–
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Small 2010, 6, 2842–2846.
Table 4. Crystallographic data for 2(MeOH) and 5(MeOH).
2(MeOH)
5(MeOH)
Empirical formula
Formula weight
Temperature [K]
Crystal size [mm]
Crystal system
Space group
λ
a [Å]
b [Å]
c [Å]
α [°]
C46H78FeN2O10
874.95
200
C44H74FeN2O10
846.90
133
0.23ϫ0.12ϫ0.03
triclinic
0.28ϫ0.25ϫ0.17
triclinic
¯
¯
P1
P1
Mo-Kα, 0.71073
8.1996(1)
10.7339(1)
28.4255(4)
82.4756(9)
88.8122(8)
75.9810(8)
2406.26(5)
2
Mo-Kα, 0.71069
8.0145(4)
11.3292(6)
26.7290(15)
78.299(4)
86.789(4)
70.243(4)
2236.4(2)
2
β [°]
δ [°]
V [Å3]
Z
ρcalcd. [g/cm3]
μ [mm–1]
F(000)
1.208
0.368
948
1.258
0.394
916
Θ range [°]
Index ranges
3.3–25.4
–9/ 9
–12/12
1.6–25.7
–9/ 9
–13/13
–34/34
16749
8776
–32/32
30421
8436
Reflections collected
Reflections unique
Data/restraints/parameters 8776/0/546
8436/0/522
0.0517
0.1235
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R1 (all)
wR2
0.0402
0.1016
1.04
GooF
0.87
Eur. J. Inorg. Chem. 0000, 0–0
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Job/Unit: A11096
/KAP1
Date: 07-12-11 16:36:29
Pages: 11
S. Schlamp, P. Thoma, B. Weber
FULL PAPER
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Received: October 11, 2011
Published Online: ᭿
10
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Job/Unit: A11096
/KAP1
Date: 07-12-11 16:36:29
Pages: 11
Octahedral Iron(II) Complexes with Spin Crossover Properties
Head–Tail SCO Complexes
S. Schlamp, P. Thoma,
B. Weber* ....................................... 1–11
New Octahedral, Head–Tail Iron(II) Com-
plexes with Spin Crossover Properties
Keywords: Iron / Magnetic properties /
Schiff bases / Spin crossover / Layered com-
pounds
A series of iron(II) complexes with head–
tail character have been investigated. Lipid
layer-like structures have been observed,
and the complexes with pyridine show spin
crossover behaviour.
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