Ionic multi-component complexes containing TDAE·+ and C60·- radical ions and neutral D1 molecules: D1·TDAE·C60

Article abstract of DOI:10.1039/b306074h

New ionic complexes containing TDAE^·+ and C₆₀^·- radical ions and neutral molecules: (TBPDA)₂·TDAE·C₆₀ (1); CTV·TDAE·C₆₀ (2); and Co^IITPP·TDAE·C₆₀ (3) (TDAE: tetrakis(dimethylamino)ethylene; TBPDA: N,N,N′,N′-tetrabenzyl-p-phenylenediamine; CTV: cyclotriveratrylene and Co^IITPP: tetraphenylporphyrinate cobalt (II)) were obtained as single crystals. The presence of TDAE^·+, C₆₀^·- and neutral donors in 1-3 was proved by optical absorption spectra in the IR and UV-vis-NIR ranges. In the crystal structure of 1 studied by single crystal X-ray diffraction, TDAE^·+ and C₆₀^·- are spatially separated by bulky TBPDA molecules. Magnetic susceptibilities of 1 and 2 follow the Curie-Weiss law with the negative Weiss temperatures (-2.3 and -2.0 K) and their magnetic moments decrease below 60 and 15 K, respectively. The EPR signals from 1 and 2 at the same temperatures are split into two components, which shift in the opposite directions to lower and higher fields with the temperature decrease. This phenomenon is explained by the formation of field-induced short-range magnetically ordered clusters. Co^IITPP and C₆₀^·- form diamagnetic σ-bonded (Co^IITPP·C₆₀^-) anions in 3 in the 1.9-190 K range. This allows one to observe the EPR signal from the isolated TDAE^·+ radical cations (g = 2.0031 and halfwidth = ΔH = 3.22 mT at 4 K). Above 190 K the magnetic moment of 3 increases and the EPR signal is essentially broadened and shifted to a lager g-factor (g = 2.0194, ΔH = 24.2 mT at 290 K). This is attributed to the dissociation of the σ-bonded diamagnetic (Co^IITPP·C₆₀^-) anions to non-bonded paramagnetic Co^IITPP and C₆₀^·- components.

Full text of DOI:10.1039/b306074h

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؉
؊
ؒ
ؒ
Ionic multi-component complexes containing TDAE and C60
radical ions and neutral D1 molecules: D1ؒTDAEؒC60 †
Dmitri V. Konarev,*a,b Ivan S. Neretin,c Gunzi Saito,*a Yury L. Slovokhotov,c Akihiro Otsukaa,d
and Rimma N. Lyubovskayab
a Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku,
Kyoto 606-8502, Japan. E-mail: saito@kuchem.kyoto-u.ac.jp; Fax: ϩ81-75-753-40-35
b Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region 142432,
Russia. E-mail: konarev@icp.ac.ru; Fax: ϩ007-096-515-54-20
c Institute of Organoelement Compounds RAS, 28 Vavilov St., 119991, Moscow, Russia
d Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku,
Kyoto 606-8502, Japan
Received 29th May 2003, Accepted 8th August 2003
First published as an Advance Article on the web 3rd September 2003
New ionic complexes containing TDAE ϩ and C60 Ϫ radical ions and neutral molecules: (TBPDA)2ؒTDAEؒC60 (1);
CTVؒTDAEؒC60 (2); and CoIITPPؒTDAEؒC60 (3) (TDAE: tetrakis(dimethylamino)ethylene; TBPDA: N,N,NЈ,
NЈ-tetrabenzyl-p-phenylenediamine; CTV: cyclotriveratrylene and CoIITPP: tetraphenylporphyrinate cobalt ())
ؒ
ؒ
were obtained as single crystals. The presence of TDAE ϩ, C60 Ϫ and neutral donors in 1–3 was proved by optical
absorption spectra in the IR and UV-vis-NIR ranges. In the crystal structure of 1 studied by single crystal X-ray
ؒ
ؒ
diffraction, TDAE ϩ and C60 Ϫ are spatially separated by bulky TBPDA molecules. Magnetic susceptibilities of 1 and
2 follow the Curie–Weiss law with the negative Weiss temperatures (Ϫ2.3 and Ϫ2.0 K) and their magnetic moments
decrease below 60 and 15 K, respectively. The EPR signals from 1 and 2 at the same temperatures are split into two
components, which shift in the opposite directions to lower and higher fields with the temperature decrease. This
phenomenon is explained by the formation of field-induced short-range magnetically ordered clusters. CoIITPP and
ؒ
ؒ
C60 Ϫ form diamagnetic σ-bonded (CoIITPPؒC60Ϫ) anions in 3 in the 1.9–190 K range. This allows one to observe the
ؒ
EPR signal from the isolated TDAE ϩ radical cations (g = 2.0031 and halfwidth = ∆H = 3.22 mT at 4 K). Above 190
ؒ
K the magnetic moment of 3 increases and the EPR signal is essentially broadened and shifted to a lager g-factor
(g = 2.0194, ∆H = 24.2 mT at 290 K). This is attributed to the dissociation of the σ-bonded diamagnetic
(CoIITPPؒC60Ϫ) anions to non-bonded paramagnetic CoIITPP and C60 Ϫ components.
ؒ
TDAE also forms ionic complexes with C70.13,14 Magnetic
susceptibilities of these complexes follow the Curie–Weiss law.
Introduction
Ionic compounds of fullerenes show intriguing physical proper-
ties including soft ferromagnetism in the C60 salt with tetra-
kis(dimethylamino)ethylene (TDAE) with Tc = 16.1 K1 and the
salt of chemically modified C60 with cobaltocene with Tc = 19
K.2 The transition temperature in TDAEؒC60 is the highest
among those for all known nonpolymeric purely organic
ferromagnets. To understand the origin of ferromagnetism in
TDAEؒC60 numerous magnetic, optical and structural investi-
Ϫ
ؒ
It was shown that there was no superexchange between C70
13
across the TDAE methyl groups in TDAEؒC70 and the
diamagnetic (C70Ϫ)2 dimers were formed in TDAEؒC70ؒC6H5Me
(C6H5Me: toluene).14 This could explain the absence of long-
range magnetic ordering in C70 complexes with TDAE.
Up to now, TDAEؒC60 has been considered to be the only
ionic complex of fullerene that shows ferromagnetism. To
design magnetic systems based on ionic complexes of fuller-
enes, chemically modified C60 may also be promising.2 We
developed a multi-component approach to the synthesis of
gations were carried out.3,4 The transfer of one electron from
TDAE to C60 followed by the formation of TDAE ϩ and C60
Ϫ
ؒ
ؒ
radical ions was proved by IR and Raman measurements on
single crystals.5,6 Magnetism in TDAEؒC60 is attributed mainly
ionic complexes of fullerenes with general composition
ϩ
ؒ
ؒ
to C60 Ϫ since the g-factor of the EPR signal at 2.00037 is close
ؒ
(D1)(D2 )(fullerene Ϫ), where D1 is a large neutral molecule
that forms a supramolecular packing pattern and D2 is a donor
molecule of a small size potentially able to reduce fullerene
moiety. This approach afforded exotic fulleride compounds
with the unusual diamagnetic σ-bonded (CoIITPPؒfullereneϪ)
anions in CoIITPPؒ[CrI(C6H6)2]ؒ(fullerene)ؒC6H4Cl2 (Cr(C6H6)2:
Ϫ
ؒ
8
ϩ
ؒ
to that of C60 (1.9991). The EPR signal from TDAE was
not observed probably due to spin pairing.9 The g = 2.0003 can
also be considered as an intermediate value between those for
TDAE ϩ at 2.003510 and C60 Ϫ at 1.99918 due to the existence of
ؒ
ؒ
ϩ
Ϫ 11
ؒ
ؒ
strong exchange coupling between TDAE and C60
or the
overlap of the EPR lines of TDAE and C60 Ϫ.3 In this case
ϩ
ؒ
ؒ
bis(benzene)chromium; fullerenes: C60, C70, and C60(CN)2;
Ϫ
)
ϩ
ؒ
C6H4Cl2: o-dichlorobenzene)15,16 and the diamagnetic (C70
2
TDAE can also contribute to magnetism of this salt. The
EPR study of TDAEؒC60 single crystals showed antiferro-
magnetic exchange along the shortest crystallographic c-axis
and spin canting in the orthogonal plane, which causes weak
ferromagnetism along the a-axis below Tc.12 This explanation is
based on the Dzyaloshinsky–Moriya mechanism of long-range
ferromagnetic ordering.12 †
dimers in CTVؒ(Cs)2ؒ(C70)2ؒ(DMF)7ؒ(C6H6)0.75 (CTV: cyclo-
triveratrylene; DMF: N,N Ј-dimethylformamide).17 This
method allows the investigation of the effect of incorpor-
ation of the neutral D1 component (of different size, shape and
electronic state) into ionic complexes on their magnetic and
conductive properties.
In this study we used a strong organic donor TDAE as a D2
ϩ
ؒ
component to obtain the complex containing TDAE and
† Electronic supplementary information (ESI) available: The data of
IR, UV-vis-NIR and EPR measurements of the starting compounds
and complexes 1–3 (Tables S1–S3 and Fig. S1). See http://www.rsc.org/
suppdata/dt/b3/b306074h/
Ϫ
ؒ
C60 radical ions together with neutral D1 molecules. Three
new ionic multi-component complexes (TBPDA)2ؒTDAEؒC60
(1), CTVؒTDAEؒC60 (2) and CoIITPPؒTDAEؒC60 (3) (TBPDA:
D a l t o n T r a n s . , 2 0 0 3 , 3 8 8 6 – 3 8 9 1
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
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Table 1 The data for crystals of the complexes 1–3
Elemental analysis, found/calc.
b
N
Complex
C (%)
H (%)
N (%)
Colour and shape
1
2
3
(TBPDA)2TDAEؒC60
86.10
87.70
82.15
83.05
83.02
84.31
4.54
4.66
3.26
3.84
3.47
3.20
5.61
5.94
4.04
3.99
6.53
6.89
3.75
Black prisms
Black needles
Black prisms
a
CTVؒTDAEؒC60
10.55
6.96
CoIITPPؒTDAEؒC60
a
a According to IR data, 2 and 3 contain C6H6 solvent molecules. The elemental analysis indicates a small content of C6H6 and the compounds 2 and 3
were presented as CTVؒTDAEؒC60 and CoIITPPؒTDAEؒC60. b 100% Ϫ (C, H, N)%.
N,N,NЈ,NЈ-tetrabenzyl-p-phenylenediamine; CTV: cyclotrivera-
trylene; CoIITPP: tetraphenylporphyrinate cobalt ()) were
obtained (Scheme 1). The complexes were characterized by
elemental analysis, IR, UV-vis-NIR spectra, EPR and SQUID
measurements. The crystal structure of 1 was determined by a
single crystal X-ray diffraction. The antiferromagnetic coupling
in 1 and 2, and the unusual transition from diamagnetic
shifted by up to 10 cmϪ1 relative to parent ones. Starting C60 has
four IR-active bands at 526, 576, 1182, 1429 cmϪ1 (the F1u(1–4)
modes, respectively). The F1u(4) mode is shifted in 1 and 2 to
1389 and 1390 cmϪ1, respectively, and the intensity of F1u(2)
mode is essentially higher than that of the F1u(1) mode. These
Ϫ 21
ؒ
changes are characteristic of C60
.
Ϫ
ؒ
The presence of C60 was supported by the characteristic
absorption bands22 at 10.7–10.8 (926–939 nm) and 9.2–9.3 ×
103 cmϪ1 (1075–1087 nm) in the NIR spectra of 1 and 2 in KBr
matrix. The additional bands in the IR and UV-vis-NIR
ranges, which point to dimerization or polymerization of
σ-bonded (CoIITPPؒC60Ϫ) anions to paramagnetic non-bonded
Ϫ
CoIITPP and C60 components in 3 upon the increase of
ؒ
temperature are discussed. The properties of complexes 1–3
were compared with those of TDAEؒC60.
Ϫ 23
ؒ
C60
,
were not observed indicating the monomeric state of
C60 Ϫ in both complexes at room temperature (RT = 290 K).
Complex 1 crystallizes in a tetragonal system. The disordered
C60 and TDAE molecules occupy 4/m symmetry, whereas the
ordered TBPDA molecules are in 2/m positions. Fullerene
anions are isolated from one another by the TBPDA molecules
and packed in loose square layers parallel to the ab-plane
(Fig. 1). The shortest distance between the centers of fullerene
anions in the layer is equal to the unit cell parameters, a = b =
13.626(2) Å, which is 3.5 Å larger than the C60–C60 intercenter
separation corresponding to van der Waals contacts between
fullerenes.24 Each TBPDA molecule contacts with hexagons of
two C60 moieties by central phenylene fragments (indicating
π-interaction) with C(C60) ؒ ؒ ؒ C(TBPDA) distances in the
usual van der Waals range (3.43–3.68 Å). Disordered TDAE
moieties are located within the layer in the voids formed by
eight benzyl substituents of TBPDA (the shortest C(TBP-
DA) ؒ ؒ ؒ C(TDAE) contacts are 3.63 Å). These voids alternate
with fullerenes in a staggered order. The shortest distance
between the centers of fullerenes and the midpoint of the cen-
ؒ
Scheme 1 Molecular components of the complexes.
tral C᎐C bond of TDAE in the ab-plane is 9.63 Å. All inter-
᎐
molecular distances from C60 to C or N atoms of TDAE are
Results and discussion
Synthesis
The complexes obtained are listed in Table 1. The common
procedure for their preparation as single crystals is a slow diffu-
sion of hexane into benzene/benzonitrile solution containing
ionic TDAEؒC60 in the presence of a neutral D1 component.
The important criterion for choosing the D1 components is
their ability to form stable (D1ؒC60) complexes with neutral ful-
lerene.16,18–20 In several cases multi-component D1ؒTDAEؒC60
crystallizes instead of two-component TDAEؒC60. The shift of
equilibrium from the two-component to the multi-component
complex can be realized by using an excess of the D1 compon-
ent. The crystals of multi-component complexes, primarily
identified by IR spectroscopy, were then studied by a whole set
of physical methods mentioned above.
(TBPDA)2ؒTDAEؒC60 (1), and CTVؒTDAEؒC60 (2)
The IR spectra of 1 and 2 in KBr matrix are a superposition of
5
ϩ
Ϫ
ؒ
ؒ
those of TDAEؒC60 containing TDAE and C60 radical
Fig. 1 View of the crystal structure of (TBPDA)2ؒTDAEؒC60 (1) along
the c-axis. Only one of two orientations of TDAE is shown.
ions, and neutral TBPDA and CTV molecules whose bands are
D a l t o n T r a n s . , 2 0 0 3 , 3 8 8 6 – 3 8 9 1
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longer than 5.5 Å (the sum of the van der Waals radii of two
carbons or carbon and nitrogen atoms is 3.42 and 3.25 Å25).
The similar C(TDAE) ؒ ؒ ؒ C(C60) contacts in TDAEؒC60 are
3.40–3.48 Å.26 The interlayer space is filled with the benzyl
groups of TBPDA (Fig. 2).
TBPDA molecule in 1 (70Њ) are slightly different from those of
pristine TBPDA (85–87Њ)27 probably due to packing forces.
The magnetic susceptibility of 1 at 60–300 K follows the
Curie–Weiss law with the negative Weiss temperature (Ϫ2.3 K).
The magnetic moment was estimated to be 1.97 µB at 300 K.
This value is slightly larger than the calculated one for non-
interacting S = 1/2 system (1.73 µB) and the magnetic moment
of TDAEؒC60.7 Below 60 K the magnetic moment of 1
decreases down to 1.5 µB at 1.9 K (Fig. 4) indicating the anti-
ferromagnetic interaction of spins. Annealing the sample at
100 ЊC for 2 h does not change the magnetic behavior of 1.
Fig.
4
The temperature dependence of magnetic moment of
polycrystalline (TBPDA)2ؒTDAEؒC60 (1) between 1.9 and 300 K.
Fig. 2 View of the crystal structure of (TBPDA)2ؒTDAEؒC60 (1) along
the a-axis.
The EPR spectrum of 1 contains a single Lorentzian line
with the g-factor of 2.0009 and the line half-width (∆H ) of 2.93
mT at RT. This g-factor is close to that of TDAEؒC60 (the single
line with the g-factor of 2.0003 and ∆H of 2.2 mT at RT7) and
The crystal structure of 1 viewed along the a-axis (Fig. 2)
ϩ
ؒ
shows one-dimensional chains of alternating TDAE and
Ϫ
C60 ions in the c-direction, separated from the neighboring
has a value between those for TDAE ϩ of 2.003510 and C60 Ϫ of
ؒ
ؒ
ؒ
8
1.9991. Since strong exchange coupling between TDAE Ϫ and
ؒ
ones by the TBPDA molecules. The distances between the
C60 Ϫ is not possible due to large space separation of these ions,
ؒ
centers of fullerenes and the midpoint of the central C᎐C bond
᎐
ϩ
ؒ
Ϫ
ؒ
of TDAE in this direction is 12.33 Å. Thus, the formation of 1
the overlapping of the EPR lines of TDAE and C60 is pos-
sible. Indeed, the peak to peak separation between EPR lines of
ϩ
Ϫ
ؒ
ؒ
results in essential space separation of the TDAE and C60
ϩ
Ϫ
ؒ
ؒ
radical ions by the neutral TBPDA molecules in all three
directions.
TDAE and C60 of about 0.7 mT is substantially smaller
than ∆H of the EPR signal of 1 (about 3 mT).
The disorder of the TDAE molecule between two orien-
tations does not allow one to discuss its bond distances and
bond angles, which reflect a charged state of TDAE. The
observed disorder pattern could result either from the over-
lapping of two planar ethylene moieties or from the overlapping
The temperature dependences of the parameters of 1 are
shown in Fig. 5. The g-factor of the signal remains almost
of two moieties twisted by 90Њ about the C᎐C bond (Fig. 3).
᎐
However, a planar conformation of TDAE leads to forbid-
dingly short Me ؒ ؒ ؒ Me intramolecular contacts (down to 1.74
Å), so the TDAE moiety has a twisted conformation, which is
characteristic of the TDAE cations.5 The ordered TBPDA
molecule retains its usual geometry27 showing no participation
in charge transfer. Torsion angles of the phenyl rings of the
Fig. 5 The temperature dependence of g-factor (above) and ∆H
(below) for the EPR signal of polycrystalline (TBPDA)2ؒTDAEؒC60 (1)
between 4 and 290 K.
Fig. 3 Two orientations of disordered TDAE in (TBPDA)2ؒTDAEؒ
C60 (1).
D a l t o n T r a n s . , 2 0 0 3 , 3 8 8 6 – 3 8 9 1
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unchanged down to 60 K, whereas the line strongly narrows
with the temperature decrease (∆H = 0.5 mT at 60 K). A similar
behavior of ∆H was observed in other solid ionic compounds
of C60.22 The strong temperature dependence of ∆H seems to be
This band can be attributed to charge transfer between CoIITPP
and C60Ϫ in one σ-bonded (CoIITPPؒC60Ϫ) unit.16
The magnetic susceptibility of 3 follows the Curie–Weiss law
with the Weiss temperature close to zero (0.2 K). Complex 3
an intrinsic property of C60 Ϫ. Below 60 K the EPR signal
formally contains three paramagnetic species with spin S = 1/2
ؒ
II
(Co TPP, TDAE ϩ and C60 Ϫ), so the magnetic moment of 3 µB
was expected. However, the observed magnetic moment is only
1.45 µB) in the 1.9–190 K range (Fig. 7). This value is even
smaller than 1.73 µB calculated for S = 1/2 non-interacting sys-
tem and corresponds to ∼0.85 S = 1/2 spin per formula unit.
ؒ
ؒ
becomes asymmetric and splits into two components, which
shift symmetrically in opposite directions to higher and lower
magnetic fields with the temperature decrease (g = 2.0068 and
1.9966 at 4 K, Fig. 5). The shifts are accompanied by a broaden-
ing of both components (∆H = 2.05 and 0.76 mT at 4 K). The
temperatures of the line splitting and the decrease of magnetic
moment coincide indicating that splitting of the EPR signal
originates from the antiferromagnetic interaction of spins. Such
a behavior of 1 can be interpreted as a field-induced formation
of short range magnetic clusters. It is interesting to note that the
formation of these clusters was also observed both in C60 and
C70 complexes with TDAE below 60 and 50 K.28,13 In contrast
to TDAEؒC60(70), a direct magnetic interaction between C60 Ϫ or
ؒ
Ϫ
ϩ
ؒ
ؒ
C60 and TDAE is not possible in 1 so their magnetic inter-
action probably occurs by an exchange mechanism through
TBPDA molecules.
The magnetic behavior of 2 is qualitatively similar to that of
1. Magnetic susceptibility follows the Curie–Weiss law with the
Ϫ2.0 K Weiss temperature. The magnetic moment at RT is 1.78
µB and decreases below 15 K indicating an antiferromagnetic
interaction of spins. The EPR signal from 2 is a single Lorentz-
ian line with g = 2.0012 and ∆H = 1.76 mT at RT. The signal
splits below 15 K into two components, shifted in opposite dir-
ections to higher and lower fields with the temperature decrease.
As in 1, the formation of field-induced short-range magnetic
clusters is supposed in 2 below 15 K.
Fig. 7 The temperature dependence of the magnetic moment of
polycrystalline CoIITPPؒTDAEؒC60 (3) between 1.9 and 300 K.
The EPR spectrum of 3 in the 4–190 K range is a single
Lorentzian line with g = 2.0030–2.0050 and nearly constant ∆H
of 3.2 mT (Fig. 8). This signal can be attributed to TDAE ϩ (g =
ؒ
2.003510). Thus, ∼0.85 spin per formula unit is localized mainly
CoIITPPؒTDAEؒC60 (3)
ϩ
Ϫ
on TDAE and the formation of diamagnetic (CoIITPPؒC60
)
ؒ
Cr0(C6H6)2 was used earlier as a D2 component to obtain the
anions in the 4–190 K range can be suggested. The presence of
less than 1 spin per formula unit of 3 is probably due to the
actual TDAE : C60 ratio also being less than 1: CoIITPPؒ
(TDAE)xؒC60 (x < 1). However, the data of elemental analysis
do not allow the exact determination of “x”. Similarly in (CoII-
TPP)2ؒ[CrI(C6H6)2]1.7ؒ(C60)2ؒ(C6H4Cl2)3.3, the CrI(C6H6)2 : C60
ratio determined by X-ray diffraction on a single crystal was
0.85.16
II
I
ionic multi-component complexes Co TPPؒ[Cr (C6H6)2 ϩ]ؒ
(fullereneϪ)ؒC6H4Cl2 (fullerene: C60, C70, C60(CN)2) containing
unusual diamagnetic σ-bonded (CoIITPPؒfullereneϪ) anions
with short Co(CoIITPP) ؒ ؒ ؒ C (fullerene) distances of 2.28–
2.32 Å (Fig. 6).15,16 The use of TDAE instead of Cr0(C6H6)2
results in the formation of CoIITPPؒTDAEؒC60 (3).
ؒ
Fig. 6 View of the σ-bonded (CoIITPPؒC60Ϫ) anion in (CoIITPP)2ؒ
16
[CrI(C6H6)2]1.7ؒ(C60)2ؒ(C6H4Cl2)3.3
.
The IR spectrum of 3 is a superposition of patterns from the
TDAE ϩ and C60 Ϫ radical ions and neutral CoIITPP. The NIR
ؒ
ؒ
spectrum of solid 3 contains a band of C60 at 9.2 × 103 cmϪ1
Ϫ
(1075 nm) together with an additional low-energy intense band
at 7.7 × 103 cmϪ1 (1300 nm). The latter one was also observed
upon the formation of (CoIITPP)2ؒ[CrI(C6H6)2]1.7ؒ(C60)2ؒ
(C6H4Cl2)3.3 containing the σ-bonded (CoIITPPؒC60Ϫ) anions.16
Fig. 8 The temperature dependence of the g-factor (above) and ∆H
(below) for the EPR signal of polycrystalline CoIITPPؒTDAEؒC60 (3)
between 4 and 290 K.
D a l t o n T r a n s . , 2 0 0 3 , 3 8 8 6 – 3 8 9 1
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The formation of diamagnetic and EPR silent σ-bonded
(CoIITPPؒC60Ϫ) anions in 3 allow one to observe a separate
TDAEؒC60 (2) the short range antiferromagnetic ordering is
observed below 15 K.
ϩ
ؒ
ϩ
(2) In crystalline CoIITPPؒTDAEؒC60 (3), isolated TDAE
ؒ
EPR signal from TDAE in contrast to the EPR spectra of 1
and 2. Similarly, polymerization of C60 Ϫ in TDAEؒC60 under 10
radical cations and diamagnetic (CoIITPPؒC60Ϫ) anions coexist
below 190 K. The magnetic susceptibility of 3 shows para-
magnetic behavior due to large spatial separation of TDAE
ؒ
kbar pressure29 or the formation of diamagnetic (C70Ϫ)2 dimers
in TDAEؒC70ؒC6H5Me14 result in the manifestation of EPR
ϩ
ؒ
ϩ
signal from TDAE .
radical cations. It is shown that the EPR signal from TDAE ϩ in
ؒ
ؒ
Above 190 K the magnetic moment of 3 increases with tem-
perature up to 1.85 µB at 300 K (Fig. 7) probably due to a
contribution from the emerging paramagnetic CoIITPP and
3 and related complexes may be revealed only in the presence of
diamagnetic and EPR silent species like (CoIITPPؒC60Ϫ). The
Ϫ
contribution from non-bonded CoIITPP and C60 appears
ؒ
Ϫ
ؒ
C60 components (both have S = 1/2 ground state) into the
total magnetic susceptibility of 3. The increase of magnetic
moment by 0.4 µB in the 190–300 K range corresponds to the
above 190 K probably due to dissociation of σ-bonded dia-
magnetic (CoIITPPؒC60Ϫ) anions to non-bonded paramagnetic
CoIITPP and C60 Ϫ components.
ؒ
Ϫ
contribution of 20% of total CoIITPP and C60
.
ؒ
The appearance of a contribution from the paramagnetic
Ϫ
CoIITPP and C60 components is supported by EPR data.
ؒ
Experimental
Above 190 K the signal essentially broadens and shifts to larger
g-factors (g = 2.0194 and ∆H = 24.2 mT at RT) (Fig. 8). It is
known that CoIITPP in complexes with neutral C60 and C70
shows a broad EPR signal with g ≅ 2.4 and ∆H = 50–60 mT at
RT.24 Therefore, substantial broadening and a shift to larger g
values of the EPR signal of 3 can be associated with the
appearance of paramagnetic CoIITPP at higher temperatures.
The presence of only one EPR signal instead of two or three in
this sample indicates possible strong magnetic coupling
between the paramagnetic species in 3.
Materials
CoIITPP and TDAE were purchased from Aldrich, TBPDA
from Lancaster, CTV from Acros and C60 of 99.98% purity
from MTR Ltd.. Benzene (C6H6), hexane and benzonitrile
(C6H5CN) (under reduced pressure) were distilled over Na/ben-
zophenone in argon atmosphere. The solvents were degassed
and stored in a glove box. All manipulations with 1–3 were
carried out in a MBraun 150B-G glove box with controlled
atmosphere and the content of H2O and O2 less than 1 ppm.
The samples were stored in the glove box and were sealed in 2
mm quartz tubes for EPR and SQUID measurements under
10Ϫ5 Torr. KBr pellets for IR- and UV-vis-NIR measurements
were prepared in the glove box.
Diamagnetism observed for the (CoIITPPؒC60Ϫ) anions below
190 K can be due to a direct participation of the HOMO of the
Ϫ
C60 anions and dz of CoIITPP in σ-bonding.16 As was
2
shown,15,16 the σ-bond in the (CoIITPPؒC60Ϫ) anions is rather
weak (the Co ؒ ؒ ؒ C bond length is 2.28–2.32 Å) as compared
with the strong Co–C bond in alkylcobaltoamines (1.99–
2.03 Å)30 or the Co–N bond in CoTPPؒNO (1.964 Å).31,32
Because of this, dissociation of (CoIITPPؒC60Ϫ) anions result-
ing in an additional contribution of their components to
Synthesis
Diffusion was carried out in a glass tube of 1.5 cm diameter
and 40 mL volume with a ground glass plug for 1 month. The
solvent was decanted and the crystals were washed with
hexane and dried. The composition of 1 was determined from
the X-ray diffraction on a single crystal and that of 1–3 by
elemental analysis (Table 1). The difference in element content
(100% Ϫ (C, H, N)%) for air-sensitive 1–3 indicates the addition
of oxygen to the complex in the course of analysis (calc. one O2
molecule per formula unit). The calculated C, H, and N (%)
contents were corrected for this extrinsic oxygenation. Pre-
viously the addition of O2 to ionic complexes of C60 during the
elemental analysis was reported.1,35
magnetic and spin susceptibility, is possible above 190 K. Such
Ϫ
a transition is similar to dissociation of diamagnetic (C70
)
2
Ϫ
Ϫ
ؒ
and (C60Ϫ)2 dimers to paramagnetic C70 and C60 radical
ؒ
anions.17,33,34
The crystals of 1 were obtained by a slow diffusion of hexane
(20 mL) in the 20 mL of C6H6/C6H5CN mixture (4:1) contain-
ing C60 (25 mg, 0.035 mmol), TDAE (0.05 mL) and TBPDA
(160 mg, 0.34 mmol). The starting solution was prepared by
dissolving C60 and TDAE in 4 ml of C6H5CN and stirring at
60 ЊC for 4 h, 16 ml of benzene was added, TBPDA was dissol-
ved by stirring overnight at 60 ЊC, then the obtained solu-
tion was cooled down to the room temperature and filtered.
After 1 month two types of crystals were formed, viz.
large (up to 3 × 3 × 0.5 mm3 size) black shiny prisms of 1 (70%
yield) and small (up to 0.5 × 0.5 × 0.3 mm3 size) brown crystals
of 1 (20% yield), separated under a microscope. 1 is a ferro-
magnetic phase of TDAEؒC60 according to IR and SQUID
measurements.
The crystals of 2 were prepared similarly to 1. C60
(25 mg, 0.035 mmol), TDAE (0.05 mL) and CTV (30 mg, 0.066
mmol) were used as starting reagents. The crystals of 2 grew
as black thin needles (50% yield) with no admixture of
TDAEؒC60.
The crystals of 3 were obtained by the same procedure.
C60 (25 mg, 0.035 mmol), TDAE (0.05 mL) and CoIITPP
(20 mg, 0.030 mmol) were used as starting reagents. The crystals
of 3 were obtained as black prisms with characteristic blue
luster (70% yield). TDAEؒC60 was not formed in the synthesis
of 3.
It is interesting to note that the small increase in the magnetic
moments and the broadening of the EPR signals above 200 K
were also observed in previously studied (CoIITPP)2ؒ[CrI-
(C6H6)2]1.7ؒ(C60)2ؒ(C6H4Cl2)3.3 and CoIITPPؒ[CrI(C6H6)2]2ؒ[C60-
(CN)2]2ؒ(C6H4Cl2)3.15,16 These can also be attributed to the
appearance of small contribution from non-bonded CoIITPP
Ϫ
and C60 or C60(CN)2 Ϫ. However, these effects are weaker in
ؒ
ؒ
CrI(C6H6)2 complexes than in 3 at RT.
Conclusion
New ionic complexes based on TDAE ϩ and C60 Ϫ radical ions
and neutral TBPDA, CTV, and CoIITPP molecules belonging
to two different multi-component systems, have been obtained.
(1) The incorporation of two neutral and diamagnetic
TBPDA molecules per ionic TDAEؒC60 unit in (TBPDA)2ؒ
ؒ
ؒ
ϩ
Ϫ
ؒ
ؒ
TDAEؒC60 (1) spatially separates TDAE and C60 radical
ions and yields a magnetically dilute system. This complex does
not show ferromagnetic ordering of spins in contrast to TDAEؒ
C60 but manifests the field-induced short-range antiferro-
magnetic ordering below 60 K, similar to pure TDAEؒC60.28
However, unlike TDAEؒC60 where direct magnetic exchange
between TDAE ϩ and C60 Ϫ is possible, magnetic exchange in 1
is probably mediated by the TBPDA molecules. In CTVؒ
ؒ
ؒ
D a l t o n T r a n s . , 2 0 0 3 , 3 8 8 6 – 3 8 9 1
3890

View Article Online
5 K. Pokhodnia, J. Papavassiliou, P. Umek, A. Omerzu and
D. Mihailovic, J. Phys. Chem., 1999, 110, 3606.
General
UV-vis-NIR spectra were measured on a Shimadzu-3100 spec-
trometer in the 240–2600 nm range. FT-IR spectra were meas-
ured in KBr pellets with a Perkin-Elmer 1000 Series spectro-
meter (400–7800 cmϪ1). A Quantum Design MPMS-XL
SQUID magnetometer was used to measure static suscepti-
bilities between 300 and 1.9 K. A sample holder contribution
and core temperature independent diamagnetic susceptibility
(χ0) were subtracted from the experimental values. The values
of χ0 were calculated for 1–3 from the high temperature range
using the appropriate formula: χM = C/(T Ϫ Θ;) ϩ χ0. EPR
spectra were recorded down to 4 K with a JEOL JES-TE 200
X-band ESR spectrometer equipped with a JEOL ES-CT470
cryostat.
6 K. Pokhodnia, J. Demsar, A. Omerzu, D. Mihailovic and
H. Kuzmany, Phys. Rev. B, 1997, 55, 3762.
7 K. Tanaka, A. A. Zakhidov, K. Yoshizawa, K. Okahara, T. Yamabe,
K. Yakushi, K. Kikuchi, S. Suzuku, L. Ikemoto and Y. Achiba,
Phys. Rev. B, 1993, 47, 7554.
8 P.-M. Allemand, G. Srdanov, A. Koch, K. Khemani, F. Wudl,
Y. Rubin, F. Diederich, M. M. Alvarez, S. J. Anz and R. L. Whetten,
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D. Mihailovic, P. Venturini, L. Golic, Z. Trontelj, J. Luznik, Z.
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Lyubovskaya and G. Saito, Chem. Eur. J., 2003, 9, 3837.
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X-Ray crystal structure determination
Crystal data of 1: C138H88N8, M =1858.29, black prisms, tetra-
gonal, space group I4/m. The unit cell parameters are: a = b =
13.626(2), c = 24.662(5) Å, V = 4579.3(1) Å3, Z = 2, Dc =1.348 g
cmϪ3, F(000) = 1944.0.
X-Ray diffraction data were collected at 110 K on a Bruker
SMART CCD diffractometer with an area detector (sealed
tube, Mo Kα radiation, λ = 0.71073 Å, µ = 0.08 mmϪ1). A series
of three ω scans with a 0.3Њ frame width were collected. Reflec-
tion intensities were integrated using the SAINT program. In
total, Ntot = 13250 reflections were measured up to 2Θmax = 60Њ,
2094 of them were independent. The structure was solved by
direct methods using the SHELXTL program package36 and
refined by full-matrix least squares on F 2. The ordered non-
hydrogen atoms were refined anisotropically. Hydrogen atoms
were placed in calculated positions and refined within the
‘riding atom’ model. Fullerene molecules are disordered into
two equally occupied positions related by the rotation about a
two-fold crystallographic axis passing through the midpoints of
two oppositely located 6–6 bonds. The TDAE molecule is also
disordered between two orientations with equal occupancy.
The least-square refinement on F 2 was done to R1 = 0.1002
for 1150 observed reflections with F > 4σ(F), wR2 = 0.330
(213 parameters), final GoF = 1.040.
18 D. V. Konarev, A. Yu. Kovalevsky, A. L. Litvinov, N. V. Drichko,
B. P. Tarasov, P. Coppens and R. N. Lyubovskaya, J Solid State
Chem., 2002, 168, 474.
19 J. L. Atwood, M. J. Barnes, M. G. Gardiner and C. L. Raston,
Chem. Commun., 1996, 1449.
20 D. V. Konarev and R. N. Lyubovskaya, Russ. Chem. Rev., 1999, 68,
19.
21 T. Picher, R. Winkler and H. Kuzmany, Phys. Rev. B, 1994, 49,
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22 C. A. Reed and R. D. Bolskar, Chem. Rev., 2000, 100, 1075.
23 M. S. Dresselhaus and G. Dresselhaus, in Fullerene Polymers and
Fullerene Polymer Composites, ed. P. C. Eklund and A. M. Rao,
Springer-Verlag, Berlin, 1999, pp. 1–58.
24 D. V. Konarev, I. S. Neretin, Yu. L. Slovokhotov, E. I. Yudanova,
N. V. Drichko, Yu. M. Shul’ga, B. P. Tarasov, L. L. Gumanov, A. S.
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25 Yu. V. Zefirov and P. M. Zorkii, Russ. Chem. Rev., 1995, 64, 415.
26 B. Narymbetov, H. Kobayashi, M. Tokumoto, A. Omerzu and
D. Mihailovic, Chem. Commun., 1999, 1511.
CCDC reference number 211611.
See http://www.rsc.org/suppdata/dt/b3/b306074h/ for crystal-
lographic data in CIF or other electronic format.
27 C. Rickert, M. Pirotta and T. Muller, Acta Crystallogr., Sect. C,
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29 K. Mizoguchi, M. Machino, H. Sakamoto, M. Tokumoto,
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30 M. Rossi, J. P. Glusker, L. Randaccio, M. F. Summers, P. J. Toscano
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31 B. B. Wayland, J. V. Minkiewicz and M. E. Abd-Elmageed, J. Am.
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Acknowledgements
The work was supported by the COE Research on Elements
Science 12CE2005, JSPS, and the RFBR grants N 03-03-
32699a and 02-03-33225a.
32 W. R. Scheidt and J. L. Hoard, J. Am. Chem. Soc., 1973, 95, 8281.
33 D. V. Konarev, S. S. Khasanov, A. Otsuka and G. Saito, J. Am.
Chem. Soc., 2002, 124, 8520.
34 A. Hönnerscheid, L. Wüllen, M. Jansen, J. Rahmer and
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