Ionic compound containing iron phthalocyanine (FeIPc) - anions and (C70-)2 dimers. Optical and magnetic properties of (FeIPc)- in the solid state

Article abstract of DOI:10.1039/c2dt31587d

Ionic compounds containing the anion of iron phthalocyanine (Fe ^IPc)^-, {(Fe^IPc)^-} ·(cryptand[2,2,2]·[Na⁺])·(C₆H ₄Cl₂) (1), and the fullerene C₇₀^-

Full text of DOI:10.1039/c2dt31587d

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PAPER
−
Ionic compound containing iron phthalocyanine (FeIPc)− anions and (C70 )2
dimers. Optical and magnetic properties of (FeIPc)− in the solid state†
Dmitri V. Konarev,*a Alexey V. Kuzmin,b Sergey V. Simonov,b Salavat S. Khasanov,b Akihiro Otsuka,c
Hideki Yamochi,c Gunzi Saitod and Rimma N. Lyubovskayaa
Received 17th July 2012, Accepted 10th September 2012
DOI: 10.1039/c2dt31587d
Ionic compounds containing the anion of iron phthalocyanine (FeIPc)−, {(FeIPc)−}·(cryptand[2,2,2]·
[Na+])·(C6H4Cl2) (1), and the fullerene C70− and FeIPc− anions, (C70−)2·{(FeIPc)−}6·(cryptand[2,2,2]·
[Na+])8·(C6H4Cl2)8.65·(C6H14)0.35 (2), were obtained as single crystals. Their crystal structures and optical
and magnetic properties were analyzed. Spectra of 1 and 2 manifest intense bands in visible-NIR range at
820, 690, 555, 528, 449, 400 and 316 nm attributed to (FeIPc)−. The four-coordinate (FeIPc)− anions
show an EPR signal with perpendicular and parallel components at g⊥ = 2.487 and g = 2.353 in 1 and
k
g⊥ = 2.328 and g = 2.230 in 2. According to magnetic measurements the (FeIPc)− anions have low spin
k
(S = 1/2) state indicating d7 configuration for the FeI atoms with the odd electron on the dz2 orbital.
Fullerene anions form singly bonded (C70−)2 dimers in 2, the shape of which efficiently fitted with the
−
large planar phthalocyanine anions to be surrounded completely by eight (FeIPc)− anions. The (C70
)
2
dimers are diamagnetic and EPR silent up to 350 K. Both complexes contain channels formed by four
(FeIPc)− planes in 1 or four (FeIPc)− planes and two (C70−)2 dimers in 2. The channels are occupied by
double chains of alternating cryptand[2,2,2]·[Na+] cations and solvent C6H4Cl2 molecules.
150 °C.7 As a result, phthalocyanine anions are air and moisture
Introduction
sensitive. Now, negatively charged solid phthalocyanines are
obtained mainly by doping with alkali metals in gas phase.8,9
This method does not allow the preparation of single crystals.
Therefore, the development of new methods for preparation of
anionic phthalocyanine compounds as single crystals by direct
synthesis in solution is important. We chose iron(II) phthalo-
cyanine since it is more easily reduced compared to other phthalo-
cyanines of first-row metals.7 Up to now only two salts of
(FeIPc)− with potassium cryptand or lithium crown ether were
obtained as crystals and structurally characterized.10 However,
optical and magnetic properties of the (FeIPc)− anions are
studied only in coordinating solvents like tetrahydrofuran (THF),
dimethyl sulfoxide (DMSO) and so on.11,12 Recently we have
obtained the first charge transfer complex {(FeIPc)−}·
(Cp*2Cr+)·(C6H4Cl2)4 containing (FeIPc)− by the reduction of
FeIIPc with a strong organometallic donor decamethylchromo-
cene (Cp*2Cr, E+/0 = −1.04 V vs. SCE).13 The resulting
complex contained stacks of alternating (FeIPc)− and Cp*2Cr+
ions and exhibits ferrimagnetic properties.14 In this work we
Fullerenes and phthalocyanines are promising components for
use in the design of conducting and magnetic assemblies.1–5
Fullerenes form such assemblies mainly in the radical anion
state, whereas phthalocyanines are generally used in the oxidized
state. For example, conducting compounds were obtained by oxi-
dation of phthalocyanines with iodine3 or by electrochemical
oxidation of the MIIIPc(CN)2 anions in the presence of organic
−
cations.4 Magnetic compounds were obtained by oxidation of
substituted manganese(II) naphthalocyanine by strong organic
π-acceptor tetracyanoethylene (TCNE).5 Similar to fullerenes,
phthalocyanines show multiple redox stages. Although reversible
reduction waves up to tetraanions are observed,6 phthalocyanine
anions are poorly characterized especially in the solid state. One
of the reasons is rather negative first reduction potentials of
phthalocyanines (FeIIPc, NiIIPc, ZnIIPc) which are −0.70 to
−0.78 V vs. SCE in non-coordinating 1-methylnaphthalene at
aInstitute of Problems of Chemical Physics RAS, Chernogolovka,
Moscow region, 142432, Russia. E-mail: konarev@icp.ac.ru
bInstitute of Solid State Physics RAS, Chernogolovka, Moscow region,
142432, Russia
obtained
crystals
of
{(FeIPc)−}·(cryptand[2,2,2]·[Na+])·
(C6H4Cl2) (1) to characterize the optical and magnetic properties
of four-coordinate (FeIPc)− anions in the solid state. The combi-
nation of negatively charged phthalocyanines and fullerenes in
the same compound is also a very promising task. Compounds
obtained this way can combine advanced conducting, magnetic
and optical properties of both components. Phthalocyanines are
large planar molecules which do not correspond well to the
quasi-spherical or ellipsoidal shape of fullerenes. Nevertheless,
cResearch Center for Low Temperature and Materials Sciences,
Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan
dResearch Institute, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku,
Nagoya 468-8502, Japan
†Electronic supplementary information (ESI) available: IR-spectra of 1,
2 and starting compounds. CCDC 888196 and 888197 for 1 and 2,
respectively. For ESI and crystallographic data in CIF or other electronic
format see DOI: 10.1039/c2dt31587d
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ionic compounds containing negatively charged fullerenes and
metal phthalocyanines have recently been obtained as crystals of
composition (C60−)·(MIIPc·L−)·(D+)2, where MII = Mn, Zn and
Mg.15,16 These compounds contain metal(II) phthalocyanines,
which coordinate negatively charged ligands such as L− = I−,
CH3CH2S− or OH−, and the metal(II) phthalocyanine molecules
remain uncharged in them. In this work we for the first time
obtained the ionic compound (C70−)2·{(FeIPc)−}6·(cryptand
[2,2,2]·[Na+])8·(C6H4Cl2)8.65(C6H14)0.35 (2) containing fullerene
−
C70 and FeIPc− anions. It has been shown that fullerene and
phthalocyanine anions can coexist in one compound and are
efficiently packed in ionic crystals in spite of their different
shapes. The crystal structure, optical and magnetic properties of
2 are described.
Fig. 1 Spectra of starting FeIIPc and compounds 1 and 2 in the UV-
visible and NIR ranges in KBr pellets. Bands in the spectrum of 2 attrib-
uted to the (C70−)2 dimers are shown by arrows.
Results and discussion
a. Synthesis
We used strong reductant sodium fluorenone17 in the presence of
a stoichiometric amount of cryptand[2,2,2] to generate the
(FeIPc)− anions in o-dichlorobenzene solution. Slow diffusion of
hexane into the obtained solution produces qualitative single
crystals of {(FeIPc)−}·(cryptand[2,2,2]·[Na+])·(C6H4Cl2) (1) as
rhombic plates with a copper-coloured lustre.
manifests relatively weak bands in the NIR range at 980 and
1220 nm (Fig. 1) attributed to the (C70−)2 dimers. Similar bands
were observed in the spectra of all complexes containing the
(C70−)2 dimers.18–20
The IR spectrum of FeIIPc remains almost unchanged at the
formation of the (FeIPc)− anions in 1 and 2 (see ESI†). Most
probably, the geometry of the phthalocyanine macrocycle is
retained to a great extent since the negative charge of (FeIPc)− is
localized mainly on the iron metal. Changes in the spectrum of
FeIIPc on formation of 1 and 2 are observed for two bands only.
The band at 779 cm−1 is shifted to 771 cm−1, whereas the band
at 1288 cm−1 is split in the spectra of both compounds into two
We also carried out the reduction of stoichiometric mixtures of
iron(II) phthalocyanine and fullerenes C60 or C70 by 2.2 equi-
valents of sodium fluorenone in the presence of two equivalents
of cryptand[2,2,2]. Slow diffusion of hexane into the obtained
solution in the case of C60 precipitates crystals of (C60˙−)·
(cryptand[2,2,2]·[Na+])·C6H4Cl2, the crystal structure and prop-
erties of which will be described elsewhere. In the presence of
bands located at 1267 (for 1), 1265 (for 2) and 1298 cm−1
.
−
the C70 anions a completely different phase is formed contain-
ing both fullerene C70− and (FeIPc)− anions as large prisms with
a copper-coloured lustre. X-ray diffraction analysis of several
single crystals shows that one phase of the (C70−)2·{(FeIPc)−}6·
(cryptand[2,2,2]·[Na+])8·(C6H4Cl2)8.65(C6H14)0.35 (2) compo-
sition is formed. Only prisms were found in the sample of 2 to
which the contamination of 1 is ruled out judging from the
crystal habit.
c. Crystal structures of 1 and 2
Compound 1 has a triclinic lattice with well-ordered com-
ponents: two halves of crystallographically independent (FeIPc)−
anions, one cryptand[2,2,2]·[Na+] cation and one solvent
C6H4Cl2 molecules. Compound 2 having a monoclinic lattice is
a rare example of ionic compound containing well-ordered
(C70−)2 dimers. It contains two and two halves of crystallogra-
phically independent (FeIPc)− anions, one C70− anion, four cryp-
tand[2,2,2]·[Na+] cations and four solvent C6H4Cl2 molecules.
One additional position of solvent molecules is shared by both
hexane and C6H4Cl2 molecules at a 0.35 : 0.65 ratio resulting in
the non-integer content of solvent molecules in 2. Only two of
eight solvent C6H4Cl2 molecules and alkyl chains in one of four
cryptand[2,2,2]·[Na+] cations are disordered in 2 (see Experi-
mental section).
b. Optical properties of 1 and 2
The spectra of 1 and 2 show intense bands in the whole visible
range which can be attributed to the (FeIPc)− anions (Fig. 1).
The bands are observed at about 820, 690, 555, 528, 449, 400
and 316 nm. Previously the spectrum of {(FeIPc)−}·Py was
measured in pyridine (Py) solution. The position of the bands in
this spectrum at 801, 710, 661, 595, 515 and 326 nm11 is notice-
ably shifted relative to those in the solid state spectra of 1 and 2.
The spectra of (FeIPc)− in THF and demethoxyethane (DME)
solutions also show the shift of the bands12 relative to the solid
state spectra, probably due to the coordination of THF or DME
to (FeIPc)−. The spectrum of (FeIPc)− is noticeably different
from that of neutral FeIIPc having only one broad band in the
visible range with the maximum at 662 nm (Fig. 1). It is seen
also that bands of (FeIPc)− in the spectra of 1 and 2 are notice-
ably narrower than those in the spectrum of FeIIPc. That indi-
cates isolated (FeIPc)− in 1 and 2. The spectrum of 2 also
Both complexes contain channels formed by four (FeIPc)−
planes in 1 and by four (FeIPc)− planes and two (C70−)2 dimers
in 2 (Fig. 2 and 3). The channels are occupied by double chains
of alternating cryptand[2,2,2]·[Na+] cations and solvent C6H4Cl2
molecules. The size of the channels defined by distances
between phthalocyanine planes is slightly different for 1 and 2
(11.95 Å × 19.30 Å and 11.67 Å × 19.80 Å, respectively). The
cryptand[2,2,2]·[Na+] cations form van der Waals contacts
mainly with the (FeIPc)− anions (the C and H(cryptand[2,2,2]·
13842 | Dalton Trans., 2012, 41, 13841–13847
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[Na+])⋯C{(FeIPc)−} contacts are in the 3.30–3.39 and
2.72–2.90 Å ranges, respectively).
surrounded by eight phthalocyanines. Four of them are shown in
Fig. 3b. The other four phthalocyanines are arranged similarly
but located perpendicular to the planes of four phthalocyanines
(shown in Fig. 3b). It is seen that C70 is inserted between two
phenylene groups of phthalocyanine. The elongated shape of C70
in the dimer fits well to the size and shape of phthalocyanine. It
is interesting that nearly spherical C60 molecules of smaller size
cannot form such complexes. The (C70−)2 dimers form several
C((C70−)2)⋯H and C(FeIPc−) contacts of 2.63–2.87 and 3.33 Å,
The most interesting peculiarity of 2 is cocrystallization of the
−
(C70
) dimers consisting of ellipsoidal molecules with large
2
planar phthalocyanine anions. Each (C70−)2 dimer is completely
respectively. The intermolecular contacts (18 H⋯C and 2 C⋯C
−
contacts) are regarded as preventing the disorder of the (C70
)
2
dimer in 2. The (C70−)2 dimers form continuous chains along the
c-axis in which they are separated by one solvent C6H4Cl2 mol-
ecule only.
−
The C70 anions in the (C70−)2 dimers have trans-orientation;
the intercage C–C bond length is 1.582(3) Å and the distance
−
between the center of mass of two C70 is 10.524 Å. The inter-
cage C–C bond length in previously studied (C70−)2 dimers is in
the 1.583(2)–1.586(3) Å range, whereas distances between the
centers of mass of two C70− are 10.47–10.51 Å.18–22
The geometry of FeIIPc is sensitive to the charge state of
phthalocyanine and spin state of the central metal atom
(Table 1). The longest Fe–N(Pc) bonds are observed in FeIIPc
(Table 1) with intermediate (S = 1) spin state. These bonds are
shortened in low-spin FeIIPc·(Py)2 (S = 0) (Table 1) and even
more shortened at the formation of (FeIPc)− in {(FeIPc)−}·(cryp-
tand[2,2,2]·[K+]), 1 and 2 (Table 1). In 1 and 2, the Fe–N(Pc)
bond lengths are in the 1.9141(14)–1.9188(14) and 1.9074(14)–
1.9231(14) Å ranges, respectively. The formation of the (FeIPc)2−
dianions in {(FeIPc)2−}·(18-crown-6·[Li+])2·THF does not
noticeably affect the length of Fe–N(Pc) bonds,10 since the
second electron is accommodated in the phthalocyanine macro-
cycle (Table 1). The difference between the Fe–N distances
(marked by numbers 3 and 4 in Fig. 4) is a measure of expansion
of the phthalocyanine core. It is seen that this difference is rather
Fig. 2 (a) Main structural motif of compound 1. View along continu-
ous channels formed by the (FeIPc)− anions and occupied by alternating
cryptand[2,2,2]·[Na+] cations and solvent C6H4Cl2 molecules (not
shown in this figure).
Fig. 3 (a) View of the unit cell of 2 along the c axis and continuous channels occupied by alternating cryptand[2,2,2]·[Na+] cations and solvent
−
C6H4Cl2 molecules (not shown in this figure). (b) Intermolecular contacts shorter than the sum of van der Waals radii among (FeIPc)− and the (C70
)
2
dimers (green dashed lines). Each fullerene dimer is surrounded by eight (FeIPc)−.
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Table 1 Fe–N(Pc) distances for FePc in different charged states
Lengths of Fe and pyrrollic
Distances between Fe and imine
Spin state Independent N atoms of Pc (bonds 1 and 2 N atoms of Pc (distances 3 and 4
Compound
Charge of Fe
FePc
in Fig. 4), Å
in Fig. 4) and their difference, Å Ref.
FeIIPc
0
0
−1
S = 1
S = 0
S = 1/2
1/2
1/2
1/2
1/2
1/2
1/2
1
1.953(2), 1.950(2)
1.939(2), 1.938(2)
3.391, 3.418, 0.019
3.378, 3.374, 0.004
3.372, 3.375, 0.003
3.363, 3.382, 0.019
3.376, 3.374, 0.002
3.391, 3.369, 0.022
3.381, 3.380, 3.378
3.375, max, 0.006
3.381, 3.380, 3.376
3.375, max, 0.006
3.375, 3.370, 0.005
3.359, 3.366, 0.007
3.378, 3.374, 0.004
3.387, 3.381, 0.006
23
24
FeIIPc·(Py)2
{(FeIPc)−}·(cryptand[2,2,2]·[Na+])·
C6H4Cl2 (1)
1.9182(14), 1.9188(14)
1.9141(14), 1.9143(15)
1.9115(13), 1.9248(13)
1.9154(14), 1.9252(13)
1.9115(14), 1.9201(14)
1.9157(14), 1.9231(14)
1.9207(14), 1.9176(14)
1.9227(14), 1.9154(14)
1.921(3), 1.891(3)
This work
(C70−)2·{(FeIPc)−}6·(cryptand[2,2,2]· −1
S = 1/2
This work
[Na+])8·(C6H4Cl2)8.65·(C6H14 0.35
(2)
)
1
{(FeIPc)−}·(cryptand[2,2,2]·[K+])
−1
−2
—
—
1/2
1/2
1/2
1/2
10
10
1.910(3), 1.913(3)
1.908(2), 1.906(2)
1.911(2), 1.917(2)
{(FeIPc)2−}·(18-crown-6·
[Li+])2·THF
spectra of five-coordinate (FeIPc)− species are known. For
example, the spectrum of (FeIPc)− in THF manifests a relatively
intense component close to g⊥ = 2.13 and a less prominent com-
ponent at g = 1.96.12 The g-factors of the perpendicular and par-
k
allel components are shifted in the 2.077–2.112 and 1.953–1.961
ranges depending on coordinating ligand. Such spectra were
assigned to the (dxy)2(dxz, dyz)2(dz2)1 electronic configuration of
iron(I) in (FeIPc)−.11,12
The EPR spectrum of (FeIPc)− in the solid state is noticeably
different from the solution spectra. No ligands are coordinated to
(FeIPc)− in 1 and 2. Therefore, the FeI atoms are four-coordi-
nated in these complexes. Both compounds show an asymmetric
EPR signal with g-factor anisotropy. The signal can be fitted
well by perpendicular and parallel components of the EPR spec-
trum (Fig. 5a and b). g-Factors of both components are shifted to
higher values relative to these in the solution spectra: g⊥ = 2.487
(the linewidth ΔH is 9.5 mT) and g = 2.353 (ΔH = 16.2 mT) in
k
Fig. 4 Numbers for the Fe–N(Pc) distances in FePcn− (n = 0, −1, −2;
Table 1).
1 (Fig. 5a) and g⊥ = 2.328 (ΔH = 40 mT) and g = 2.230 (ΔH =
k
13.8 mT) in 2 (Fig. 5b). The iron(I) atoms in (FeIPc)− have the
same low-spin d7 electronic configuration as the cobalt(II) atoms
in CoIITPP. The latter porphyrin has been well studied by EPR
in solid state. CoIITPP shows a two-component spectrum in dia-
small in differently charged iron phthalocyanines since the iron
atoms are in low or intermediate spin states. Stronger expansion
of the porphyrin core is observed only in a few porphyrinates
with metals in high spin state (FeII, S = 2, MnII, S = 5/2).22,25–27
Compound 2 contains four crystallographically independent
(FeIPc)− anions. In all of them, the Fe–N(Pc) bond lengths are
close but conformation of the phthalocyanine macrocycle is
noticeably different. Two phthalocyanines are planar and the FeI
atoms are exactly in the phthalocyanine plane. The other two
macrocycles are noticeably distorted. As a result, the FeI atoms
deviate by 0.019 and 0.022 Å out of the 24-atom phthalocyanine
plane. The distortion of phthalocyanine macrocycles in 2 is most
probably due to packing factors since planar (FeIPc)− anions are
surrounded by the bulky cryptand[2,2,2]·[Na+] cations and the
(C70−)2 dimers. Compound 1 contains planar FeIPc− anions with
the FeI atoms in the phthalocyanine plane.
magnetic matrix with g⊥ = 3.322, A = 395 × 10−4 cm−1, g =
k
1.798, B = 197 × 10−4 cm−1 28
.
However, the spectra of CoIITPP
in molecular complexes with fullerenes C60 and C70 are similar
to that of (FeIPc)− in 1 and 2. They also show asymmetric
signals with perpendicular and parallel components with
g-factors of 2.51–2.57 and 2.28–2.42, respectively.29,30
We also found that 1 is very air sensitive even in the solid state.
A short exposure of 1 to air produces a new signal with high
g-factor of 4.20 and effective magnetic moment of 1 increases
relative to μeff = 1.73 μB expected for low-spin (FeIPc)− (S = 1/2).
Since FeIIPc shows no EPR signal in the X-band EPR, we can
suppose that oxidation of (FeIPc)− yields oxygen-containing pro-
ducts with FeIIIPc+ in intermediate (S = 3/2) spin state. Namely
these species manifest EPR signals with g-factor close to 4.31
A strongly asymmetric narrow and weak signal is also
observed in the EPR spectrum of 2 (Fig. 5c). The intensity of
this signal corresponds to the contribution of only 0.4% of spins
from total amount of fullerene C70 and this signal can be attri-
buted to impurities. Impurities can appear due to oxidation of
d. Magnetic properties of 1 and 2
EPR spectra of FeIPc− were intensely studied in coordinating
solvents like THF, DME, Py, DMSO, etc.11,12 Therefore, EPR
13844 | Dalton Trans., 2012, 41, 13841–13847
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Fig. 5 Upper black curves show: the experimentally observed EPR spectrum of 1 at 150 K (a); the broad EPR signal of 2 attributed to (FeIPc)− at
−
30 K (the narrow signal at about g = 2.0023 is not shown) (b); the narrow signal of 2 at RT attributed to impurities due to the C70 oxidation (c).
Fitting of observed signals by two or three Lorentzian lines (blue, green and brown curves) and the sum of Lorentzian lines (red curves) are shown
below.
(FeIPc)− and their magnetic isolation by diamagnetic com-
ponents (cryptand[Na+] cations, solvent molecules and the
(C70−)2 dimers).
Conclusion
Synthesis of an ionic compound containing negatively charged
iron
phthalocyanine
as
crystals
{(FeIPc)−}·(cryptand
[2,2,2]·[Na+])·(C6H4Cl2) (1) allows one to characterize the
optical and magnetic properties of the (FeIPc)− anions in the
solid state. Four-coordinate (FeIPc)− shows intense bands in
the visible-NIR range at 820, 690, 555, 528, 449, 400 and
316 nm and manifest an EPR signal with g⊥ = 2.487 and g =
k
2.353, indicating a low spin d7 configuration for the FeI atoms.
We also succeeded in synthesizing the first compound (C70−)2·
{(FeIPc)−}6·(cryptand[2,2,2]·[Na+])8·(C6H4Cl2)8.65(C6H14)0.35 (2)
Fig. 6 Temperature dependence of effective magnetic moment of poly-
crystalline 2 in the 300–1.9 K range.
−
containing the fullerene C70 and (FeIPc)− anions. Fullerene
anions form diamagnetic singly bonded (C70−)2 dimers in 2. As
a result, the compound 2 shows only paramagnetic behavior. It
−
C70 or the formation of the C140O dimers at C70 storage in air
−
(reduction of the C140O dimer to C140O˙− can produce a new
has been shown that ellipsoidal C70 anions are efficiently
−
packed with large planar phthalocyanine anions which comple-
narrow EPR signal). The (C70
) dimers are diamagnetic in
2
−
agreement with previous observations.18–20 New signals are not
observed upon heating 2 up to 350 K. Thus, the (C70−)2 dimers
are stable at least up to this temperature. The signal in 2 can be
fitted well by three components with g1 = 2.0021 (ΔH =
0.24 mT), g2 = 2.0033 (ΔH = 0.14 mT) and g3 = 2.0037 (ΔH =
1.24 mT). Previously asymmetric signal from impurities was
observed in (Cs+)2·(C70−)2·CTV·(DMF)7·(C6H6)0.75 (CTV =
hexamethoxycyclotriveratrylene) also containing diamagnetic
(C70−)2 dimers with g1 = 2.0042 (ΔH = 0.8 mT), g2 = 2.0024
(ΔH = 0.2 mT), and g3 = 1.9923 (ΔH = 2.0 mT).18 It is interest-
ing that ionic compounds of C60 generally manifest an impurity
EPR signal as a single narrow Lorentzian line.32,33
tely surround the (C70
)
dimers. According to magnetic
2
measurements, four-coordinate (FeIPc)− anions in 2 are also in a
low spin (S = 1/2) state and manifest an EPR signal with g⊥
=
2.328 and g = 2.230. Both complexes have similar structural
k
motifs containing channels formed by four (FeIPc)− planes in 1
and by four (FeIPc)− planes and two (C70−)2 dimers in 2 occu-
pied by double chains of alternating cryptand[2,2,2]·[Na+]
cations and solvent C6H4Cl2 molecules. This new strategy opens
a way to prepare ionic compounds containing fullerene and
phthalocyanine anions. We can suppose that preparation of com-
pounds of this type, even with monomeric fullerene anions, for
example with C60˙−, can provide materials with interesting mag-
netic, conducting and optical properties.
The temperature dependence of the effective magnetic
moment of 2 is shown in Fig. 6. The magnetic moment is 4.37
μB per formula unit at 300 K. The expected magnetic moment
for a system containing six non-interacting (S = 1/2) spins is
4.24 μB, justifying the low spin state of (FeIPc)− in 2 (S = 1/2).
The (C70−)2 dimers are diamagnetic and do not contribute to the
magnetic moment of the complex. The Weiss temperature is only
0.1 K in the 10–300 K range showing nearly paramagnetic be-
havior. The reasons of that could be the long distances between
Experimental
Materials
Iron(II) phthalocyanine (FeIIPc) and cryptand[2,2,2] were pur-
chased from Aldrich. Fullerene C70 of 99.0% purity was used.
Sodium fluorenone was obtained as previously described.17
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Solvents were purified in an argon atmosphere. o-Dichloroben-
zene (C6H4Cl2) was distilled over CaH2 under reduced pressure
and hexane was distilled over Na/benzophenone. The solvents
were degassed and stored in a glove box. All manipulations for
the synthesis of air-sensitive 1 and 2 were carried out in a
MBraun 150B-G glove box with controlled atmosphere (O2,
H2O < 1 ppm). The crystals were stored in the glove box and
sealed in 2 mm quartz tubes for EPR and SQUID measurements
under 10−3 Torr. KBr pellets for IR and UV-visible-NIR
measurements were prepared in the glove box.
JES-TE 200 X-band ESR spectrometer. A Quantum Design
MPMS-XL SQUID magnetometer was used to measure static
magnetic susceptibility (χM) of 2 with a 100 mT magnetic field
in cooling and heating conditions from 300 K down to 1.9 K
and back from 1.9 K up to 300 K. Cooling and heating rates
were 10 K per minute. The temperature-independent contribution
(χ0) including core diamagnetic susceptibility was estimated in
the 10–300 K range by the extrapolation of the data in the high-
temperature range. A sample holder contribution and χ0 were
subtracted from the experimental values. Effective magnetic
moment (μeff) was calculated with an appropriate formula: μeff
=
(8χMT)1/2
.
Synthesis
Reduction of FeIIPc (24 mg, 0.042 mmol) by slight excess of
sodium fluorenone (10.5 mg, 0.052 mmol) in the presence of a
stoichiometric amount of cryptand[2,2,2] (15.8 mg,
0.042 mmol) by stirring in 15 mL of o-dichlorobenzene at 60 °C
for 4 hours produced a dark violet solution of the (FeIPc)− salt
with sodium cryptand cations. The solution was cooled and
filtered into a 50 mL glass tube 1.8 cm in diameter with a
ground glass plug. 25 mL of hexane was layered over the
obtained solution. Slow mixing of solvents over 6 weeks yielded
the crystals of {(FeIPc)−}·(cryptand[2,2,2]·[Na+])·(C6H4Cl2) (1)
on the walls of the tube. The solvent was decanted from the crys-
tals which were then washed with hexane (yield 56%). The crys-
tals were black rhombic plates up to 0.8 mm × 0.5 mm ×
0.2 mm in size with a characteristic copper-coloured luster. The
composition of the complexes was determined by X-ray struc-
tural analysis on a single crystal. Several crystals tested from the
synthesis had the same unit cell parameters.
X-ray crystal structure determination
X-ray diffraction data for 1 and 2 were collected at 130(1) K on
an Oxford diffraction “Gemini-R” CCD diffractometer with
graphite monochromated MoKα radiation using an Oxford
Instrument Cryojet system. Raw data reduction to F2 was carried
out using CrysAlisPro, Oxford Diffraction Ltd. The structures
were solved by direct method and refined by the full-matrix
least-squares method against F2 using SHELX-97.34 Non-hydro-
gen atoms were refined in the anisotropic approximation.
Positions of hydrogen atoms were calculated geometrically. Sub-
sequently, the positions of H atoms were refined by the “riding”
model with Uiso = 1.2Ueq of the connected non-hydrogen atom
or as ideal CH3 groups with Uiso = 1.5Ueq. For crystallographic
data in CIF or other electronic format see DOI:
10.1039/c2dt31587d
Reduction of FeIIPc (20 mg, 0.035 mmol) and C70 (29 mg,
0.035 mmol) by a slight excess of sodium fluorenone (20 mg,
0.098 mmol) in the presence of stoichiometric amount of cryp-
tand[2,2,2] (26.3 mg, 0.070 mmol) by stirring in 16 mL of
o-dichlorobenzene at 60 °C for 4 hours produced a dark violet-
Crystal data for 1. C56H56Cl2FeN10NaO6, Mr = 1114.85 g
mol−1, black plate, triclinic, P1, a = 12.5032(5), b = 12.5968(7),
ˉ
c = 19.1276(8) Å, α = 80.989(4), β = 72.451(4), γ = 64.593(5)°,
V = 2593.3(2) Å3, Z = 2, dcalc = 1.428 g cm−3, μ = 0.465 mm−1
,
F(000) = 1162, 2θmax = 62.42°, reflections measured 54 473,
unique reflections 14 989, reflections with I > 2σ(I) = 11790,
parameters refined 688, restraints 0, R1 = 0.0480, wR2 = 0.1068,
G.O.F. = 1.026.
red solution containing the (FeIPc)− and C70 salts with sodium
−
cryptand cations. The solution was cooled and filtered into a
50 mL glass tube 1.8 cm in diameter with a ground glass plug.
25 mL of hexane was layered over the obtained solution. Slow
mixing of solvents over 6 weeks yielded the crystals of (C70−)2·
{(FeIPc)−}6·(cryptand[2,2,2]·[Na+])8·(C6H4Cl2)8.65(C6H14)0.35 (2)
on the walls of the tube. The solvent was decanted from the crys-
tals which were then washed with hexane (yield 72%). The
crystals were black prisms up to 1 mm × 1 mm × 0.8 mm in
size with characteristic copper-coloured luster. The composition
of the complexes was determined by the X-ray structural
analysis on a single crystal. Several crystals tested from the
synthesis had the same unit cell parameters. Only prisms were
found in the sample of 2, which therefore did not contain an
admixture of 1.
Crystal data for 2. C530H423.50Cl17.50Fe6N64Na8O48, Mr
=
9596.22 g mol−1, black prism, monoclinic, P21/n, a = 23.4456
(5), b = 38.8603(6), c = 25.4496(5) Å, β = 109.079(2)°, V =
21913.5(7) Å3, Z = 2, dcalc = 1.454 g cm−3, μ = 0.392 mm−1
,
F(000) = 9954, 2θmax = 56.56°, reflections measured 267 369,
unique reflections 54 291, reflections with I > 2σ(I) = 43 617,
parameters refined 3199, restraints 321, R1 = 0.0435, wR2
=
0.1188, G.O.F. = 1.044.
Molecular disorder in 1 and 2
Occupancies of solvent molecules in disordered parts were
refined as free variables following SHELX-97 concepts. Two of
eight solvent C6H4Cl2 molecules are disordered between two
orientations with the 0.898(2)/0.102(2) and 0.550(2)/0.0450(2)
occupancies. One position of solvent molecules is shared by
both hexane and C6H4Cl2 molecules at a 0.346 : 0.654 ratio with
0.003 error. Alkyl chains in one of four cryptand[2,2,2]·[Na+]
cations are statistically disordered between two orientations.
General
UV-visible-NIR spectra were measured in KBr pellets on a
Perkin Elmer Lambda 1050 spectrometer in the 250–2500 nm
range. FT-IR spectra were measured in KBr pellets with a
Perkin-Elmer 1000 Series spectrometer (400–7800 cm−1). EPR
spectra were recorded from 293 down to 4 K with a JEOL
13846 | Dalton Trans., 2012, 41, 13841–13847
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16 D. V. Konarev, L. V. Zorina, S. S. Khasanov and R. N. Lyubovskaya,
Dalton Trans., 2012, 41, 9170.
Acknowledgements
17 D. V. Konarev, S. S. Khasanov, E. I. Yudanova and R. N. Lyubovskaya,
Eur. J. Inorg. Chem., 2011, 816.
The work was supported by RFBR-JSPS grant No 12-03-92107
(Japan–Russia Research Cooperative Program) and Grant-in-Aid
Scientific Research from JSPS, Japan (23225005) and MEXT,
Japan (20110006).
18 D. V. Konarev, S. S. Khasanov, I. I. Vorontsov, G. Saito, Y. A. Antipin,
A. Otsuka and R. N. Lyubovskaya, Chem. Commun., 2002, 2548.
19 D. V. Konarev, S. S. Khasanov, G. Saito, A. Otsuka, Y. Yoshida and
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20 D. V. Konarev, S. S. Khasanov and R. N. Lyubovskaya, Russ. Chem.
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21 D. V. Konarev, S. S. Khasanov, A. Otsuka, G. Saito and
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22 D. V. Konarev, S. S. Khasanov, S. V. Simonov, E. I. Yudanova and
R. N. Lyubovskaya, CrystEngComm, 2010, 12, 3542.
23 A. Hoshino, Y. Takenaka and H. Miyaji, Acta Crystallogr., Sect. B:
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