Ionic and neutral C60 complexes with coordination assemblies of metal tetraphenylporphyrins, MIITPP2·DMP (M = Mn, Zn). Coexistence of (C60-)2 dimers bonded by one and two single bonds in the same compound

Article abstract of DOI:10.1021/ic061628z

Coordination assemblies of metal tetraphenylporphyrins, M ^IITPP₂·DMP (M = Mn, Zn) were shown to form ionic multicomponent and neutral complexes with fullerene, {(Mn^IITPP) ₂·DMP}·(C₆₀^-)₂· (DMETEP⁺)₂·(C₆H₄Cl ₂)₅ (1) and {(ZnTPP)₂·DMP} ·(C₆₀)2·(C₆H₅Cl)₄ (2), where DMP = N,N′-dimethylpiperazine and DMETEP⁺ = the cation of N,N′-dimethyl-N′-ethylthioethylpiperazine. The crystal structure of 1 contains zigzag chains of the (Cof )2 dimers alternating with the DMETEP⁺ cations in the channels formed by the (Mn^IITPP) ₂·DMP units, whereas in 2 zigzag chains of the C₆₀ molecules are separated by the (ZnTPP)₂·DMP units and C ₆H₅Cl molecules. The (M^IITPP) ₂·DMP assemblies (M = Mn, Zn) have axial M-N(DMP) bonds of 2.315(2) and 2.250(2) A length, average equatorial M-N(DMP) bonds elongated to 2.141(3) and 2.077(2) A, and M^II atoms displaced from the porphyrin plane toward the ligand by 0.677 and 0.485 A, respectively. The single-bonded σ-(C₆₀^-)₂ dimer coexists in 1 with the (C₆₀^-)₂ dimer bonded by two single bonds with 86/14 occupancy factors. The σ-(C ₆₀^-)₂ dimers are unusually stable and begin to dissociate only above a temperature of 320-330 K that results in the increase of the magnetic moment of 1 from 8.33 μ_B (320 K) to 8.66 μ_B (360 K). The electron paramagnetic resonance (EPR) signal of the dimeric phase (T < 320 K) with the features spread over the range of 0-0.7 T was attributed to the interacting Mn²⁺ centers in the (Mn^IITPP)₂·DMP units. The dissociation of the σ-(C₆₀^-)₂ dimers to the EPR-active C ₆₀^?- radical anions manifests a new broad Lorenz signal above 320 K with g = 2.0179 and ΔH = 65.5 mT. This signal can appear due to the exchange coupling between paramagnetic (Mn^IITPP) ₂·DMP and C₆₀^?- species. The vis-NIR spectrum of the σ-(C₆₀^-)₂ dimers is discussed.

Full text of DOI:10.1021/ic061628z

Inorg. Chem. 2007, 46, 7601−7609
Ionic and Neutral C60 Complexes with Coordination Assemblies of Metal
Tetraphenylporphyrins, MIITPP2
(C60 )2 Dimers Bonded by One and Two Single Bonds in the Same
Compound
‚
DMP (M
)
Mn, Zn). Coexistence of
-
Dmitri V. Konarev,*,†,‡ Salavat S. Khasanov,†,§ Gunzi Saito,*,† Akihiro Otsuka,| and
Rimma N. Lyubovskaya‡
DiVision of Chemistry, Graduate School of Science, Kyoto UniVersity, Sakyo-ku, Kyoto 606-8502,
Japan, Institute of Problems of Chemical Physics RAS, ChernogoloVka, Moscow region 142432,
Russia, Institute of Solid State Physics RAS, ChernogoloVka, Moscow region 142432, Russia,
and Research Center for Low Temperature and Materials Sciences, Kyoto UniVersity,
Sakyo-ku, Kyoto 606-8502, Japan
Received August 29, 2006
Coordination assemblies of metal tetraphenylporphyrins, MIITPP2
multicomponent and neutral complexes with fullerene,
(MnIITPP)2
(ZnTPP)2 DMP}‚(C60)2 (C6H5Cl)4 (2), where DMP N,N
-dimethylpiperazine and DMETEP+
dimethyl-N
-ethylthioethylpiperazine. The crystal structure of 1 contains zigzag chains of the (C60-)2 dimers alternating
with the DMETEP+ cations in the channels formed by the (MnIITPP)2
DMP units, whereas in 2 zigzag chains of the
C60 molecules are separated by the (ZnTPP)2 DMP assemblies
DMP units and C6H5Cl molecules. The (MIITPP)2
(M Mn, Zn) have axial M N(DMP) bonds of 2.315(2) and 2.250(2) Å length, average equatorial M N(DMP)
bonds elongated to 2.141(3) and 2.077(2) Å, and MII atoms displaced from the porphyrin plane toward the ligand
by 0.677 and 0.485 Å, respectively. The single-bonded
-(C60-)2 dimer coexists in 1 with the (C60-)2 dimer bonded
by two single bonds with 86/14 occupancy factors. The
-(C60-)2 dimers are unusually stable and begin to dissociate
only above a temperature of 320 330 K that results in the increase of the magnetic moment of 1 from 8.33 µB
‚
DMP (M
) Mn, Zn) were shown to form ionic
-
{
‚DMP}‚(C60
)
‚
2
(DMETEP+)2
‚
(C6H4Cl2)5 (1) and
{
‚
‚
)
′
)
the cation of N,N′-
′
‚
‚
‚
)
−
−
σ
σ
−
(320 K) to 8.66 µB (360 K). The electron paramagnetic resonance (EPR) signal of the dimeric phase (T < 320 K)
+
with the features spread over the range of 0
(MnIITPP)2
DMP units. The dissociation of the
a new broad Lorenz signal above 320 K with g
−
0.7 T was attributed to the interacting Mn2 centers in the
-
•-
‚
σ
-(C60 ) dimers to the EPR-active C60 radical anions manifests
2
)
2.0179 and
‚
∆
H
)
65.5 mT. This signal can appear due to the
exchange coupling between paramagnetic (MnIITPP)2
dimers is discussed.
DMP and C60•- species. The vis
−
NIR spectrum of the
σ-(C60
)
2
-
Introduction
interactions.2 The dimerization of fullerene radical anions
reversibly affects the magnetic properties of the complexes
and is accompanied by paramagnetic-diamagnetic transitions
or the decrease of the magnetic moment of the complexes.3
Now, dimerization has been found in several ionic complexes
and salts of C60. Those are metastable M‚C60 phases (M )
Ionic fullerene compounds are interesting by their physical
properties1 and a large variety of dimeric and polymeric
structures of negatively charged fullerenes, some of which
show metallic conductivity and strong antiferromagnetic
* To whom correspondence should be addressed. E-mail: konarev@
icp.ac.ru (D.V.K), saito@kuchem.kyoto-u.ac.jp (G.S.). Fax: +007-496-522-
18-52 (D.V.K.), +81-75-753-40-35 (G.S.).
(1) (a) Rosseinsky, M. J. J. Mater. Chem. 1995, 5, 1497. (b) Gotschy, B.
Fullerene Sci. Technol. 1996, 4, 677. (c) Konarev, D. V.; Lyubovskaya,
R. N. Russ. Chem. ReV. 1999, 68, 19.
(2) Prassides, K. The Physics of Fullerenes-Based and Fullerene-Related
Materials; W. Andreoni, Ed.; Kluwer Academic Publishers: The
Netherlands, 2000; p 175.
† Division of Chemistry, Graduate School of Science, Kyoto University.
‡ Institute of Problems of Chemical Physics RAS.
§ Institute of Solid State Physics RAS.
| Research Center for Low Temperature and Materials Sciences, Kyoto
University.
10.1021/ic061628z CCC: $37.00
Published on Web 08/08/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 18, 2007 7601

Konarev et al.
-
K, Rb, Cs);4 Cr(C6H5Me)2‚C60 (Cr(C6H5Me)2 ) bis(toluene)-
chromium) at 250 K;5 Cp*2Cr‚C60‚(C6H4Cl2)2 (Cp*2Cr )
decamethylchromocene) at 220-200 K;6 Cr(C6H6)2‚C60‚
C6H4Cl2 and Cr(C6H6)2‚C60‚C6H5CN (Cr(C6H6)2 ) bis-
(benzene)chromium)at160-240andabove250K,respectively;6b,7
Cp2Co‚C60‚C6H4Cl2 (Cp2Co ) cobaltocene) at 250-350 K;6b
Cr(C6H5-C6H5)2‚C60 (Cr(C6H5-C6H5)2 ) bis(diphenyl)-
chromium);8 multicomponent (Cs)2‚(C60)2‚CTV‚(DMF)6 (CTV
) cyclotriveratrylene) at 140-220 K;3 and Cr(C6H6)2‚C60‚
[Pd(dbdtc)2]0.5 (Pd(dbdtc)2 ) palladium(II) dibenzyldithio-
carbamate) at 130-150 K.9 The temperatures of the begin-
ning of dissociation of the dimers are within 130-250 K.3
Most probably, the dimerization temperature is defined by
the initial distance between the C60•- radical anions and their
environment from the countercations and solvent mol-
ecules.3,7 Even in the same compound, the initial structural
which define the formation of negatively charged (C60
)
2
dimers bonded by one or two single bonds in the ionic
complexes, are not clear.
In this work, we present new ionic and neutral complexes
of C60 with coordination MIITPP2‚DMP assemblies (M )
Mn (1) and Zn (2); TPP ) tetraphenylporphyrin; DMP )
N,N′-dimethylpiperazine). Their crystal structures and optical
and magnetic properties were studied. It was shown that
negatively charged σ-(C60-)2 dimers formed in 1 have the
highest stability among the ionic complexes of C60 studied
-
to date. Moreover, the σ-(C60
) dimers coexist in this
2
complex with the (C60-)2 dimers bonded by two single bonds.
That allows one to understand the conditions, at which the
formation of the (C60-)2 dimers bonded by two single bonds
is more preferable than that of the σ-(C60-)2 dimers. The
magnetic transition associated with the dissociation of the
σ-(C60-)2 dimers and their vis-IR spectra is discussed in
detail. Molecular structures of new coordination MIITPP2‚
DMP assemblies (M ) Mn, Zn) are also presented for the
first time.
•-
differentiation of the C60 pairs, in which the dimerization
is realized, can noticeably shift the dimerization tempera-
tures.7 The least-stable (C60-)2 dimers were observed in
Cr(C6H6)2‚C60‚[Pd(dbdtc)2]0.5.9 Such dimerization is ac-
companied by a relatively large hysteresis between the
cooling and heating curves (∼20 K). As a result, at a fast
cooling rate, the dimerization temperature decreases to 60
K.9 The dimers with highest stability were found in Cr(C6H5-
Me)2‚C60, Cr(C6H6)2‚C60‚C6H5CN, and Cp2Co‚C60‚C6H4-
Cl2.5,6b However, due to the fact that the dimers already begin
to dissociate above 250 K, their observation is impossible
at room temperature (RT). On the contrary, single-bonded
(C70-)2 dimers are essentially more stable and begin to
dissociate only above RT. Due to that, their IR and vis-
NIR spectra can be analyzed.10 Recently, a negatively
charged (C60-)2 dimer bonded by two single bonds has been
found in {CoIITMPP‚(MDABCO+)}2‚(C60-)2‚(C6H4Cl2)2.5‚
(C6H5CN)1.5 (MDABCO+ ) the cation of N-methyldiazabi-
cyclooctane; TMPP ) tetrakis(4-methoxyphenyl)porphy-
rin).11 This dimer differs in electronic state from the
diamagnetic σ-(C60-)2 dimer3,6-8 and manifests approximately
two spins per dimer at 300 K. Up to now, there has been
only one example of the formation of such (C60-)2 dimers,
and the conditions,
Experimental Section
Materials. Zinc(II) tetraphenylporphyrin (ZnTPP), manga-
nese(III) tetraphenylporphyrin chloride (MnIIITPPCl), sodium boro-
hydride (NaBH4), diazabicyclooctane (DABCO), sodium ethanethi-
olate (CH3CH2SNa), N,N′-dimethylpiperazine (DMP), and methyl
iodide (CH3I) were purchased from Aldrich. MnIITPP was obtained
by the reduction of MnIIITPPCl by NaBH4 in ethanol.12 C60 of
99.98% purity was used from MTR, Ltd. The solvents were purified
in an argon atmosphere. Chlorobenzene (C6H5Cl) and o-dichlo-
robenzene (C6H4Cl2) were distilled over CaH2 under reduced
pressure, benzonitrile (C6H5CN) was distilled over Na under reduced
pressure, and hexane was distilled over Na/benzophenone. The
solvents were degassed and stored in a glovebox. All manipulations
for the synthesis of air-sensitive 1 were carried out in a MBraun
150B-G glove box with a controlled atmosphere and the concentra-
tions of H2O and O2 less than 1 ppm. The crystals were stored in
a glovebox and sealed in 2 mm quartz tubes for electron
paramagnetic resonance (EPR) and superconducting quantum
interference device (SQUID) measurements under 10-5 Torr of
pressure. KBr pellets for IR and UV-vis-NIR measurements were
prepared in a glovebox.
Synthesis. N,N′-dimethyldiazabicyclooctane diiodide (DMDABCO‚
I2) was obtained by the dropwise addition of an excess of CH3I (5
mL, 0.08 mol) to DABCO (2 g, 0.0178 mol) dissolved in 30 mL
of acetonitrile at the stirring. After 2 h of stirring, a white crystalline
precipitate of DMDABCO‚I2 was formed. It was filtered off, washed
with two portions of 10 mL of acetonitrile, and dried in a vacuum
during a 8 h period. A mass of 4.94 g of DMDABCO‚I2 was
obtained with 70% yield. Elemental analysis (Calcd, I ) 64.2%;
Found, I ) 63.8%).
(3) Konarev, D. V.; Khasanov, S. S.; Saito, G.; Lyubovskaya, R. N. Recent
Res. DeVel. Chem. 2004, 2, 105.
(4) (a) Zhu, Q.; Cox, D. E.; Fischer, J. E. Phys. ReV. B: Condens. Matter
Mater. Phys. 1995, 51, 3966. (b) Oszla´nyi, G.; Bortel, G.; Faigel, G.;
Tegze, M.; Gra´ra´sy, L.; Pekker, S.; Stephens, P. W.; Bendele, G.;
Dinnebier, R.; Miha´ly, G.; Ja´nossy, A.; Chauvet, O.; Forro´, L. Phys.
ReV. B: Condens. Matter Mater. Phys. 1995, 51, 12228. (c) Kosaka,
M.; Tanigaki, K.; Tanaka, T.; Atake, T.; Lappas, A.; Prassides, T.
Phys. ReV. B: Condens. Matter Mater. Phys. 1995, 51, 12018.
(5) Ho¨nnerscheid, A.; Wu¨llen, L.; Jansen, M.; Rahmer J.; Mehring, M. J.
Chem. Phys. 2001, 115, 7161.
(6) (a) Konarev, D. V.; Khasanov, S. S.; Otsuka, A.; Saito, G. J. Am.
Chem. Soc. 2002, 124, 8520. (b) Konarev, D. V.; Khasanov, S. S.;
Saito, G.; Otsuka, A.; Yoshida, Y.; Lyubovskaya, R. N. J. Am. Chem.
Soc. 2003, 125, 10074.
(7) Konarev, D. V.; Khasanov, S. S.; Kovalevsky, A. Y.; Saito, G.; Otsuka,
A.; Lyubovskaya, R. N. Dalton Trans. 2006, 3716.
(8) Ketkov, S. Yu.; Domrachev, G. A.; Ob’edkov, A. M.; Vasil’kov, A.
Yu.; Yur’eva, L. P.; Mehner, C. P. Russ. Chem. Bull. 2004, 53, 1932.
(9) Konarev, D. V.; Kovalevsky, A. Y.; Otsuka, A.; Saito.; G.;
Lyubovskaya, R. N. Inorg. Chem. 2005, 44, 9547.
The crystals of {(MnIITPP)2‚DMP}‚(C60)2‚(DMETEP)2‚(C6H4-
Cl2)5 (1) (DMETEP ) N,N′-dimethyl-N′-ethylthioethylpiperazine)
were obtained by the following procedure. C60 (25 mg, 0.035
mmol), a 10-fold molar excess of CH3CH2SNa (30 mg, 0.36 mmol),
and a 4-fold molar excess of DMDABCO‚I2 (44.5 mg, 0.175 mmol)
were stirred in 20 mL of the C6H4Cl2/C6H5CN (19:1) mixture for
(10) Konarev, D. V.; Khasanov, S. S.; Vorontsov, I. I.; Saito, G.; Antipin,
Yu. A.; Otsuka, A.; Lyubovskaya, R. N. Chem. Commun. 2002, 2548.
(11) Konarev, D. V.; Khasanov, S. S.; Otsuka, A.; Saito, G.; Lyubovskaya,
R. N. J. Am. Chem. Soc. 2006, 128, 9292.
(12) (a) Wayland, B. B.; Olson, L. W.; Siddiqui, Z. U. J. Am. Chem. Soc.
1970, 92, 4235. (b) Kobayashi, H.; Yanagawa, Y. Bull. Chem. Soc.
Jpn. 1972, 45, 450.
7602 Inorganic Chemistry, Vol. 46, No. 18, 2007

Ionic and Neutral C60 Complexes
Table 1. X-ray Diffraction Data for 1 and 2
compound
1 h at 60 °C. C6H5CN was added to increase the solubility of
CH3CH2SNa and DMDABCO‚I2, which are poorly soluble in pure
C6H4Cl2. During stirring, the color of the solution changed from
violet (characteristic of neutral C60) to red-brown. After the cooling
of the solution down to room temperature and filtering, the NIR
spectrum was measured to indicate the selective reduction of C60
to the -1 charged state. MnIITPP (24 mg, 0.035 mmol) was
dissolved in the obtained solutions at 60 °C for 1 h, and the solution
was cooled, filtered in a 50 mL glass tube of 1.8 cm diameter with
a ground-glass plug, and 25 mL of hexane was layered over the
solution. The diffusion was carried out during 2 months to give
crystals of 1 on the wall of the tube. The solvent was decanted
from the crystals, and they were washed with hexane (yield 50%).
The crystals were black prisms with characteristic blue luster and
up to 1 × 1 × 0.2 mm3 in size. The composition of the complex
was determined from X-ray structural analysis on a single crystal.
Several crystals selected from the synthesis had similar unit-cell
parameters.
The crystals of {(ZnTPP)2‚DMP}‚(C60)2‚(C6H5Cl)4 (2) were
obtained by the slow evaporation of chlorobenzene solution (15
mL) containing C60 (25 mg, 0.035 mmol), ZnTPP (23 mg, 0.035
mmol), and a large excess of DMP (1 mL). After 1 week, the
crystals of 2 were formed, and they were washed with hexane (yield
70%). The crystals were rhomboids with characteristic blue luster
and up to 2 × 1 × 0.4 mm3 in size. The composition of 2 was
determined from X-ray structural analysis.
General Procedures. UV-vis-NIR spectra were measured in
KBr pellets on a Shimadzu-3100 spectrometer in the 240-2600
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 4 up to 360 K with a JEOL JES-TE
200 X-band ESR spectrometer equipped with a JEOL ES-CT470
cryostat. A Quantum Design MPMS-XL SQUID magnetometer was
used to measure the static susceptibilities of polycrystalline 1
between 1.9 and 360 K at 100 mT static magnetic field. A sample-
holder contribution and core-temperature-independent diamagnetic
susceptibility (ø0) were subtracted from the experimental values.
The values of Θ and ø0 were calculated using experimental data in
the 40-300 K range with the appropriate formula: øM ) C/(T -
Θ) + ø0.
Crystal Structure Determination. X-ray diffraction data for 1
and 2 are listed in Table 1. The intensity data for the structural
analysis of 1 were collected at 100(2) K on a MAC Science DIP-
2020K oscillator type X-ray imaging plate diffractometer with
graphite-monochromated Mo KR radiation at low temperatures
using an Oxford Cryostream cooling system. Raw data reduction
to F2 was carried out using the DENZO program.13 X-ray diffraction
data for 2 were collected at 100(2) using a Bruker Nonius X8 Apex
diffractometer with CCD area detector (Mo KR radiation, λ )
0.71073 Å) equipped with an Oxford Cryosystems nitrogen gas-
flow apparatus. The data were collected by æ and ω-scans with
0.3° frame-width and 30 s exposure time per frame. The data were
integrated, scaled, sorted, and averaged using the Bruker AXS
software package.14 The structures of 1 and 2 were solved by direct
method and refined by the full-matrix least-squares method against
F2 using SHELX-97.14 Non-hydrogen atoms were refined in the
anisotropic approximation. Positions of hydrogen atoms were
calculated geometrically. Subsequently, the positions of H atoms
1
2
structural formula
empirical formula
{(MnIITPP)2‚DMP}‚(C60)2‚ {(ZnTPP)2‚DMP}‚
(DMETEP)2‚(C6H4Cl2)5
C264H136Cl10Mn2N14S2
4032.37
(C60)2‚(C6H5Cl)4
C238H90Cl4Zn2N10
3361.74
black
Mr (g‚mol-1
)
cryst color
black
size (mm × mm × mm) 0.5 × 0.5 × 0.2
0.4 × 0.3 × 0.2
monoclinic
P21/n
14.042(1)
30.700(2)
18.186(1)
90
105.794(2)
90
7545.8(8)
2
cryst syst
space group
a (Å)
triclinic
P1h
14.2060(5)
15.2780(5)
21.8810(7)
90.668(2)
108.425(2)
94.286(2)
4489.9(3)
1
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
F
calc (g/cm3)
1.491
1.480
0.462
3432
µ (mm-1
F(000)
)
0.385
2070
abs correction
min/max transmission
T (K)
empirical
multiscan
0.91
0.93
100(2)
100(2)
max 2Θ (deg)
reflns mesd
unique reflns
params, restraints
reflns [Fo > 2σFo]
R1 [Fo > 2σFo]
WR2 (all data)a
a
54.8
56.70
43 727
18 697
1708, 10 003
12 800
0.0597
0.1871
0.1134
0
34 675
18 906
1698, 13 692
16 912
0.0588
0.1632
0.0858
7.6043
1.019
b
GOF
1.087
restr GOF
0.982
0.901
CCDC nos
617720
617721
a w ) 1/[σ2(Fo ) + (aP)2 + bP], P ) [max(Fo , 0) + 2Fc ]/3.
2
2
2
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.
Molecular Disordering in 1 and 2. The crystal structure of 1
contains ordered DMETEP+ cations (Figure 1 d). One of the phenyl
rings of MnIITPP porphyrin in the (MnIITPP)2‚DMP units (Figure
1a) is disordered between two positions with the 85/15% occupan-
cies. The position of the (C60-)2 dimers is shared by the dimers of
two types. The σ-(C60-)2 dimer bonded by one single bond (Figure
1c) is disordered between two orientations with 73/13% occupancies
(total occupancy is 86%). The (C60-)2 dimer bonded by two single
bonds has only 14% occupancy (Figure 1b). There are three
positions of solvent C6H4Cl2 molecules in 1. These molecules are
ordered in one position, whereas they are disordered between two
orientations near the inversion center in the second position and
between three orientations with the 84/9/7% occupancies in the third
position. To calculate intermolecular distances and present the
figures for 1 in the case of disordered units, we used only the major
occupied orientation of the σ-(C60-)2 dimer and one major occupied
orientation of the phenyl rings of MnIITPP. In the crystal structure
of 2, the C60 molecules are disordered between three orientations
with 34/33/33% occupancies. One of the phenyl rings of ZnTPP
porphyrin in the (ZnTPP)2‚DMP unit is disordered between two
positions with 71/29% occupancies. Solvent C6H5Cl molecules are
ordered in one position, whereas they are disordered between four
orientations with 39/22/20/19% occupancies in the second position.
To calculate intermolecular distances and present the figures for 2
in the case of disordered units, we used only one 34% occupied
orientation of the C60 molecules and one major occupied orientation
of the phenyl rings of ZnTPP.
(13) (a) Otwinowski, Z. Minor, W. In Processing of X-ray Diffraction Data
Collection in Oscillation Mode; Methods in Enzymology; Carter, C.
W., Sweet, R. M., Eds.; Academic Press, 1997; p 276. (b) Sheldrick,
G. M. SHELX-97; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(14) Bruker Analytical X-ray Systems; Madison, WI, 1999.
Inorganic Chemistry, Vol. 46, No. 18, 2007 7603

Konarev et al.
Figure 1. Molecular structures of the components of 1: (a) (MnIITPP)‚DMP assembly; (b) (C60-)2 dimer bonded by two single bonds; (c) single-bonded
(C60-)2 dimer; and (d) N,N′-dimethyl-N′-ethylthioethylpiperazinium (DMETEP+) cation.
Scheme 1
Results and Discussion
1. Synthesis. Complex 1 was obtained by the method
developed for the synthesis of ionic multicomponent
complexes containing metalloporphyrins, fullerene anions,
and organic cations such as the cation of N-methyldiazabi-
cyclooctane: {MII-porphyrin‚(MDABCO+)x}‚(C60-)x‚solvent
(M ) Co, Zn, Mn, Fe; x ) 1 or 2).11,15 In this work, we
used another cation obtained by the reaction of an excess of
CH3I with DABCO. According to the elemental analysis,
the obtained salt has the DMDABCO‚I2 composition and,
therefore, contains DMDABCO2+ dications. C60 was reduced
Figure 2. Projection of the crystal structure of 1 along the a axis and the
by a large excess of CH3CH2SNa in the presence of an excess
of DMDABCO‚I2. In contrast to previously used MDABCO‚
zigzag chains formed by the alternating (C60-)2 dimers and the DMETEP+
cations.
I, which was stable in the presence of CH3CH2SNa,
DMDABCO‚I2 was found to be unstable. Most probably,
the reaction is realized through a nucleophilic attack of
preparation of the ionic multicomponent complex {(MnII-
TPP)2‚DMP}‚(C60-)2‚(DMETEP+)2‚(C6H4Cl2)2 (1), in which
(C60-)‚(DMETEP+) salt cocrystallizes with the neutral (MnII-
TPP)2‚DMP units. The crystals of {(ZnTPP)2‚DMP}‚C60‚
C6H5Cl (2) were obtained by the slow evaporation of the
chlorobenzene solution containing C60, ZnTPP, and an excess
of DMP.
2. Crystal Structures. The crystal structure of 1 was
solved at 100(2) K. The main structural motif of 1 is the
channels formed by four (MnIITPP)2‚DMP units (Figure 2),
which are occupied by zigzag chains from the (C60-)2 dimers
alternating with the DMETEP+ cations (the fragment of this
chain is shown in Figure 3). These types of channels
are characteristic of the ionic multicomponent complexes
of metalloporphyrins with fullerene anions and were pre-
viously observed in (TMP+)‚{CoIIOEP‚(C60-)}‚(C6H5CN)x‚
(C6H4Cl2)1-x (TMP ) tetramethylposphonium; OEP )
octaethylporphyrin; x = 0.75) and {(MDABCO+)‚CoIIOEP‚
CH3CH2S- to one of the positively charged nitrogen atoms
of DMDABCO2+; one C-N+ bond is opened, one new C-S
bond is formed, and the DMDABCO2+ dication transforms
to the DMETEP+ cation (eq 1 of Scheme 1). Namely,
DMETEP+ cations were found in 1 and other complexes
obtained by this method starting from DMDABCO‚I2.
Moreover, most probably, the DMETEP+ cations are also
not so stable for the further nucleophilic attack of CH3CH2S-
to the positively charged nitrogen atom of the DMETEP+
cation, and one of the reaction products can be neutral DMP
(N,N′-dimethylpiperazine) (eq 2 of Scheme 1). DMP forms
coordination dimers with two MnIITPP units that allow the
(15) (a) Konarev, D. V.; Khasanov, S. S.; Otsuka, A.; Saito, G.;
Lyubovskaya, R. N. Chem.sEur. J. 2006, 12, 5225. (b) Konarev, D.
V.; Khasanov, S. S.; Otsuka, A.; Saito, G.; Lyubovskaya. R. N. Inorg.
Chem. 2007, 46, 2261.
7604 Inorganic Chemistry, Vol. 46, No. 18, 2007

Ionic and Neutral C60 Complexes
Figure 3. View of the zigzag chains of the alternating (C60-)2 dimers and
DMETEP+ cations in the ac plane.
(C60-)}‚(C6H5CN)x‚(C6H4Cl2)1-x (x = 0.67).15a However, in
contrast to the CoIIOEP complexes, in which the walls of
the channels are built by the porphyrin planes of four CoII-
OEP units,15a the walls of the channels in 1 are built by two
MnIITPP porphyrin planes and phenyl substituents of two
other (MnIITPP)2‚DMP units (Figure 2). The C60- anions are
arranged in the chains in such a way that they are surrounded
Figure 4. View of the crystal structure of 2 along the a axis.
ture.17 The formation of coordination dimers strongly deforms
the MnIITPP macrocycle to make MnII atoms five-coordi-
nated. The averaged length of the Mn-N equatorial bonds
in 1 is equal to 2.141(3) Å, and the displacement of the MnII
atom from the porphyrin plane is 0.677 Å. Corresponding
values for four-coordinated MnIITPP are 2.084(2) and ∼0.177
Å,18 and five-coordinated MnIITPP‚MeIm units (MeIm )
N-methylimidazole) are 2.128(2) and 0.57 Å.19 The length
of the axial Mn-N bond of 2.315(2) Å is noticeably longer
in 1 than in the MnIITPP‚MeIm units of 2.192(2) Å.19
Therefore, the stronger distortion of the MnIITPP macrocycle
is attained in 1 at the longer axial Mn-N bond. The shortest
distance between two MnII atoms bonded by the DMP ligand
is 6.282 Å.
only by the phenyl substituents of the (MnIITPP)2‚DMP units
-
with the van der Waals (vdW) C‚‚‚C(C60-) and H‚‚‚C(C60
)
contacts in the 3.348-3.382 and 2.645-2.899 Å ranges. The
DMETEP+ cations are located exactly above the concave
MnIITPP porphyrin planes (rms is 0.156/0.203 Å).16 In such
a packing, there is no interaction between MnIITPP porphyrin
-
planes and C60 anions and the Mn‚‚‚C(C60-) contacts are
large (>6.9 Å).
The zigzag chains from the (C60-)2 dimers pass along the
a axis (Figure 3). The positions of the (C60-)2 dimer are
occupied by the major occupied σ-(C60-)2 dimers (86%
occupancy) and minor occupied (C60-)2 dimers bonded by
two single bonds (14% occupancy). The interfullerene center-
to-center distance for the σ-(C60-)2 dimer is 9.251 Å, and
the length of a single interfullerene C-C bond is 1.587(4)
Å (Figure 1c), as in other studied σ-(C60-)2 dimers.6-8 The
(C60-)2 dimer (Figure 1b) linked by two single bonds of
1.626(21) Å length has the interfullerene center-to-center
distance of 9.054 Å (in previously described dimers of such
type, these values were 1.581(3) and 9.070 Å).11 In the
chains, each σ-(C60-)2 dimer forms two shortened vdW C-C
contacts of 3.288 Å length by the 6-6 bonds with two
neighboring σ-(C60-)2 dimers (four such contacts are formed
in total). The shortest interfullerene center-to-center distance
The (ZnTPP)2‚DMP units form a neutral complex with
fullerene, 2. The crystal structure of 2 was studied at 100(2)
K (Figure 4). The main building block of 2 is the C60-
(ZnTPP)2‚DMP-C60 unit, in which each (ZnTPP)2‚DMP
assembly forms vdW contacts with two C60 molecules
arranged exactly above the concave ZnTPP macrocycle (rms
is 0.188/0.207 Å,16 Figure 4). The shortest Zn‚‚‚C(C60)
distance of 3.235-3.268 Å and the vdW N‚‚‚C(C60) and C‚
‚‚C(C60) contacts of 3.012-3.196 and 3.227-3.389 Å are
typical for the C60 complexes with (ZnTPP)x‚L coordination
units (x ) 1, 2, and 4).20a,b The C60-(ZnTPP)2‚DMP-C60
units are arranged in such a way that zigzag chains from the
C60 molecules can be outlined along the c axis. Each C60
molecule has two neighbors in the chain with the equal
interfullerene center-to-center distance of 10.226 Å and only
one vdW interfullerene C-C contact of 3.371 Å. The C60
chains are separated by the (ZnTPP)2‚DMP units along the
b axis with the shortest interfullerene center-to-center
distance of 14.183 Å and by the C6H5Cl molecules along
the a axis with the shortest interfullerene center-to-center
distance of 13.134 Å.
-
-
between the C60 anions from the neighboring σ-(C60
)
2
dimers is 10.039 Å. The DMETEP+ cations (Figure 1d)
arrange in the zigzag chains of the C60 anions to form the
-
vdW C‚‚‚C(C60-) and H‚‚‚C(C60-) contacts of 3.338 and
2.761-2.887 Å in length. The C6H4Cl2 molecules mainly
occupy cavities between the porphyrin planes in the
(MnIITPP)2‚DMP units.
The molecular structure of the (ZnTPP)2‚DMP assembly
is similar to that of the (MnIITPP)2‚DMP assembly (Figure
1a). The averaged lengths of the equatorial Zn‚‚‚N bonds of
2.077(2) Å and the axial Zn-N(DMP) bond of 2.250(2) Å
are noticeably shorter than the lengths of these bonds in the
corresponding (MnIITPP)2‚DMP dimer. The displacement of
The molecular structure of the (MnIITPP)2‚DMP unit is
shown in Figure 1a. This is a rare example of a coordination
dimer of MnIITPP, whereas mainly coordination dimers and
polymers containing MnIIITPP+ are described in the litera-
(16) Root-mean-square deviations (rms) were calculated for the porphyrin
macrocycle excluding the metal atom (first value) and including the
metal atom (second value).
(18) Kirner, J. F.; Reed, C. A.; Scheidt, W. R. J. Am. Chem. Soc. 1977,
(17) (a) Diskin-Posner, Y.; Kumar Patra, G.; Goldberg, I. J. Chem. Soc.,
Dalton Trans. 2001, 2775. (b) Kumar, R. K.; Goldberg, I. Angew.
Chem., Int. Ed. Engl. 1998, 37, 2027.
99, 1093.
(19) Kirner, J. F.; Reed, C. A.; Scheidt, W. R. J. Am. Chem. Soc. 1977,
99, 2557.
Inorganic Chemistry, Vol. 46, No. 18, 2007 7605

Konarev et al.
Figure 5. Temperature dependence of the magnetic moment of polycrys-
talline 1 in the 1.9-360 K range.
Figure 6. Changes in the EPR spectrum of polycrystalline 1 at the
dissociation of the σ-(C60-)2 dimers in the 320-360 K range.
Zn atom from the porphyrin plane is 0.485 Å. The shortest
distance between two Zn atoms bonded by the DMP ligand
is 6.263 Å. The geometric parameters of the five-coordinated
ZnTPP‚Py units in (ZnTPP‚Py)2‚C60‚Cp2Fe‚C7H8 (Py )
pyridine; Cp2Fe ) ferrocene)20a are close to those of the
(ZnTPP)2‚DMP units in 2. The averaged length of the
equatorial Zn-N bonds is 2.072(2) Å, the length of the axial
Zn-N(Py) bond is 2.151(4) Å, and the displacements of the
the spectrum spread almost over the full range of electro-
magnetivity (0-0.7 T) with the separation between the
components from 90 to 130 mT (Figure 6). Since the
σ-(C60-)2 dimers are EPR silent and the contribution of
(C60-)2 dimers bonded by two single bonds is negligible,
the signal can be attributed mainly to the (MnIITPP)2‚
DMP units. Generally, four-coordinated MnIITPP, five-
coordinated MnIITPP‚(N-MeIm), and six-coordinated
MnIITPP‚(MDABCO+)2 units manifest asymmetric signals
with g = 6.0 and g = 2.0 and hyperfine splitting from
55Mn.21,15b The appearance of a different spectrum in 1 can
be explained by zero-field splitting (ZFS) due to a strongly
distorted environment of the MnII centers22 or noticeable
magnetic-exchange interaction between two MnII centers in
the (MnIITPP)2‚DMP units. In the latter case, the spectrum
of 1 can be more characteristic of the binuclear MnII
complexes.23 Indeed, a similar EPR spectrum with the
features spread over the 0-0.5 T range was shown by
manganese(II) diethyldithiocarbamate dimers, {Mn(Et2-
dtc)2}2, in the complex with C7023a and binuclear manganese-
(II) complexes bridged, for example, by chlorine atoms.23c
Zn atom from the porphyrin plane is 0.435 Å.20a
-
3. Magnetic Properties of 1 and the Effect of the (C60
)
2
Dissociation on the Magnetic Properties. The magnetic
moment of 1 at 300 K is equal to 8.33 µB per formula unit
(Figure 5) and is close to the calculated value for two high-
spin MnII centers (S ) 5/2 + 5/2, µeff ) 8.37 µB). There is no
contribution from the C60•- radical anions with S ) 1/2 spin
state due to the dimerization. Therefore, σ-(C60-)2 dimers
are stable in 1 even at 300 K. Such high stability has for the
first time been observed for the σ-(C60-)2 dimers. Previously,
the highest temperature for the beginning of dissociation of
the dimers was found to be 250 K.5,6a The contribution from
the paramagnetic (C60-)2 dimers bonded by two single bonds
to magnetic susceptibility should be small as that compared
with high-spin MnII due to the small occupancy factors for
these dimers. The magnetic moment is nearly constant down
to 40 K, below which it begins to decrease due to antifer-
romagnetic interaction of spins. The magnetic susceptibility
follows the Curie-Weiss law in the 300-40 K range with
the Weiss constant of -0.5 K. The absence of noticeable
magnetic interactions is associated with the formation of the
diamagnetic σ-(C60-)2 dimers, which magnetically dilute the
paramagnetic species in 1. The shortest distance between the
MnII centers is in the (MnIITPP)2‚DMP dimer and most
probably weak antiferromagnetic exchange interaction
between the MnII centers is realized through the DMP ligand.
The magnetic moment of 1 begins to increase above 320-
330 K (Figure 5) up to 8.66 µB at 360 K. This value is close
to that calculated for the system of four noninteracting spins
(S ) 5/2 + 5/2 + 1/2 + 1/2, µeff ) 8.72 µB). Therefore, at 360
K most parts of the diamagnetic σ-(C60-)2 dimers dissociate
to paramagnetic C60•- radical anions. The EPR spectrum of
1 also strongly changes above 330 K. An EPR signal
attributed to the (MnIITPP)2‚DMP units decreases in intensity
with the temperature increase, and a new broad Lorenz signal
with g ) 2.0179 and ∆H ) 65.5 mT grows (Figure 6). The
temperatures for the increase of the magnetic moment and
Complex 1 demonstrates an unusual EPR spectrum at RT,
which it qualitatively retains down to 4 K. The features of
(21) Reed, C. A.; Kouba, J. K.; Grimes, C. J.; Cheung, S. K. Inorg. Chem.
1978, 17, 2666.
(22) Goodgame, D. M. L.; El Mkami, H.; Smith, G. M.; Zhao, J. P.;
McInnes, E. J. L. Dalton Trans. 2003, 34.
(20) (a) Konarev, D. V.; Kovalevsky, A. Y.; Li, X.; Neretin, I. S.; Litvinov,
A. L.; Drichko, N. V.; Slovokhotov, Y. L.; Coppens, P.; Lyubovskaya,
R. N. Inorg. Chem. 2002, 41, 3638. (b) Litvinov, A. L.; Konarev, D.
V.; Kovalevsky, A. Y.; Coppens, P.; Lyubovskaya, R. N. Cryst.
Growth Des. 2005, 5, 1807. (c) Hosseini, A.; Taylor, S.; Accorsi, G.;
Armaroli, N.; Reed, C. A.; Boyd, P. D. W. J. Am. Chem. Soc. 2006,
128, 15903.
(23) (a) Konarev, D. V.; Kovalevsky, A. Y.; Khasanov, S. S.; Saito, G.;
Lopatin, D. V.; Umrikhin, A. V.; Otsuka, A.; Lyubovskaya, R. N.
Eur. J. Inorg. Chem. 2006, 1881. (b) Khangulov, S. V.; Pessiki, P. J.;
Barynin, V. V.; Ash, D. E.; Dismukes, G. C. Biochemistry 1995, 34,
2015. (c) Romero, I.; Collomb, M.-N.; Deronyier, A.; Llobet, A.;
Perret, E.; Pe`kaut, J.; Le Pare, L.; Latour, J.-M. Eur. J. Inorg. Chem.
2001, 69.
7606 Inorganic Chemistry, Vol. 46, No. 18, 2007

Ionic and Neutral C60 Complexes
Figure 7. UV-vis-NIR spectra of 1 (a) and 2 (b). The spectra of starting MnIITPP (a) and ZnTPP (b) are shown below by dashed lines.
the appearance of a new signal coincide. Therefore, the
changes in the EPR spectrum can be unambiguously at-
tributed to the formation of the EPR-active C60 radical
are observed in the spectrum of the (C60-)2 dimers bonded
by two single bonds.11 The spectrum of 2 is simpler and
indicates the neutral ground state of the complex (Supporting
Information). The F1u(4) mode of C60 is split into three bands
centered at 1419, 1424, and 1428 cm-1. Such splitting
justifies the freezing of the C60 molecules’ rotation, even at
RT.25
The UV-vis-NIR spectrum of 1 in KBr pellet shows
characteristic bands of MnIITPP at 448, 575, and 614 nm
and negatively charged C60 at 342, 954, 1073, and 1356 nm
(Figure 7a). The bands of MnIITPP (443, 572, and 611 nm)
remain unchanged qualitatively and are shifted only by 3-5
nm at the formation of the (MnIITPP)2‚DMP units. However,
parent MnIITPP can contain coordinated ethanol since it was
obtained in ethanol.21 In this case, the Soret band of starting
MnIITPP is additionally shifted to the red side and the real
shift of the Soret band at the formation of 1 can be larger
than 5 nm. Previously, it was shown that the Soret band at
434 nm in the spectrum of MnIITPP‚(C6H5Me)2 in THF was
shifted to 440 nm in the spectrum of MnIITPP‚(N-MeIm)‚
(THF)0.8.21
•-
anions. Most probably, the new signal appears due to
exchange coupling between paramagnetic (MnIITPP)2‚DMP
•-
and C60 species, and it should have a g-factor value
intermediate between those characteristic of the (MnIITPP)2‚
•-
DMP and C60 species (1.9996-2.0000).24 As a rule,
exchange interaction leads to the disappearance of any
individual features of the signals (such as ZFS splitting and
the asymmetry of the signal) and provides the pure Lorenz
shape of the resulting single line. The changes in the EPR
spectra were always observed at the dissociation of the
σ-(C60-)2 dimers. Asymmetric EPR signals characteristic of
individual cations in the dimeric phase are transformed in
the monomeric phase to the Lorenz signals, with g-factor
values intermediate between those characteristic of the
•-
cations and the C60 species.3,6a,7,9
The (C60-)2 dimers bonded by two single bonds show the
EPR signal.11 On the background of a very intense EPR
signal from MnII, the EPR spectrum of these dimers is not
resolved, probably due to a small content of the dimers as
well as the fact these dimers can give one signal together
with some part of the (MnIITPP)2‚DMP units due to exchange
coupling between them. There is only one weak signal with
g ) 1.9915 and ∆H ) 4.98 mT at RT that can be attributed
to negatively charged fullerene species (Figure 6, arrow 1).
However, most probably it arises from a small fraction
(e1%) of nondimerized C60•-radical anions, which were
previously observed in the dimeric phases of ionic fullerene
complexes (up to 3.5% from total amount of C60 molecules).6b
This signal strongly narrows with the temperature decrease
and shows a paramagnetic dependence of intensity at low
temperatures.
The UV-vis-NIR spectrum of 2 in KBr pellet manifests
bands of ZnTPP at 440, 562, and 600 nm and a broad intense
band with the maximum at 780 nm, which can be ascribed
to charge transfer from the (ZnIITPP)2‚DMP units to C60
(Figure 7b). The appearance of this band is associated with
a relatively good overlapping of the π orbitals of concave
ZnTPP porphyrin macrocycles and spherical C60 molecules.20b,c
Starting ZnTPP has the bands at 431, 553, and 623 nm.
Therefore, at the formation of the coordination dimers in 2,
the Soret band is noticeably shifted up to 9 nm, and the
positions and relative intensities of the Q bands are changed.
Similar charge-transfer bands with close positions of the
maxima at 760-820 nm and the shifts of the Soret and Q
bands of ZnTPP were observed at the formation of other
C60 complexes with the (ZnTPP)x‚L coordination units (x )
4. IR and UV-vis-NIR Spectra. Since the IR spectrum
of the DMETEP+ cations is unknown, the analysis of the
spectrum of 1 is hampered. Nevertheless, in addition to the
absorption bands characteristic of the MnIITPP, DMP, and
solvent molecules, there are many additional absorption
bands (Supporting Information), which should be not only
from the DMETEP+ cations but also due to the fact that
dimerization breaks the symmetry in C60 and manifests IR
silent modes. Similarly, additional weak absorption bands
•-
1, 2, and 4).20b The absence of the absorption bands of C60
in the NIR spectrum of 2 indicates the neutral ground state
of the complex.
5. Comparison of the Optical Spectra of Negatively
Charged (C60-)2 Dimers and C60•-. The vis-NIR spectrum
of the σ-(C60-)2 dimers in 1 was compared with those of the
(25) Semkin, V. N.; Drichko, N. V.; Kimzerov, Yu, A.; Konarev, D. V.;
(24) Reed, C. A.; Bolskar, R. D. Chem. ReV. 2000, 100, 1075.
Lyubovskaya, R. N.; Graja, A. Chem. Phys. Lett. 1998, 295, 266.
Inorganic Chemistry, Vol. 46, No. 18, 2007 7607

Konarev et al.
reduced forms of C120O and C120OS dimers in solution.27
They manifest NIR bands at 940 and 1020 nm, respectively,
which are also essentially broadened in comparison with
these bands of monomeric C60•-. So, this broadening can
reflect the derivative nature of the dimers. Both reduced
C120O and C120OS dimers also display additional broad low-
energy bands associated with the intradimer CT transitions.27
Conclusion
In this work, we showed that coordination assemblies of
metal tetraphenylporphyrins, (MIITPP)2‚DMP (M ) Mn, Zn;
DMP ) N,N′-dimethylpiperazine) can be successfully used
as building blocks for the preparation of ionic multicompo-
nent and neutral complexes with fullerenes (1 and 2). The
effective packing of the coordination assemblies with the
C60 anions and molecules is promoted by the presence of
flexible phenyl substituents in the MnIITPP2‚DMP units (1)
and the concave shape of the ZnTPP macrocycles in the
ZnTPP2‚DMP units (2). The C60•- radical anions are dimer-
ized in 1 to form two types of dimers: major occupied single-
bonded (C60-)2 dimer and minor occupied (C60-)2 dimer
bonded by two single bonds. This is the first example of an
ionic complex in which both types of negatively charged
(C60-)2 dimers are formed. The diamagnetic single-bonded
σ-(C60-)2 dimers begin to dissociate in 1 only above 320-
330 K. These dimers have the highest stability among all
σ-(C60-)2 dimers studied to date. The dissociation of the
(C60-)2 dimers noticeably expands the space occupied by two
C60- anions and rearranges all components of the complex.
As a result, the environment formed by donors, counterca-
tions and solvent molecules and the mutual vdW and ionic
bonding between them affects dimer stability and their
dissociation temperatures. This effect can be compared with
“pressure”, which stabilizes the dimers, preventing their
•-
Figure 8. NIR spectra of (a) monomeric C60 radical anions in
{MnIITPP‚(MDABCO+)2}‚(C60•-)2‚(C6H4Cl2)4.2‚(C6H5CN)1.8 15b (b) single-
;
bonded σ-(C60-)2 dimer in 1; and (c) (C60-)2 dimer bonded by two single
bonds in {CoIITMPP‚(MDABCO+)}2‚(C60-)2‚(C6H4Cl2)2.5‚(C6H5CN)1.5
.
11
(C60-)2 dimer bonded by two single bonds and monomeric
C60 radical anions (Figure 8). The (C60-)2 dimers bonded
by two single bonds are probably admixed to the σ-(C60
dimers in 1 at RT. However, the content of this dimer is too
•-
-
)
2
•-
low to qualitatively change the spectrum. The C60 radical
anions have characteristic bands in the NIR range at 1083
and 937 nm, which allow an unambiguous identification of
the -1 charged state of C60 in ionic complexes. Two similar
bands are observed in the NIR spectra of the fullerene dimers
with the shifts of both bands to 954 (17 nm) and 1072 nm
(11 nm) for the dimer bonded by one single bond and 905
(32 nm) and 1064 nm (19 nm) for the dimer bonded by two
single bonds. Noticeable broadening of both bands is also
•-
observed in comparison with the bands of monomeric C60
(Figure 8). The NIR spectra of the dimers are different from
•-
that of C60 by the appearance of weak additional low-
energy bands at 1356 nm (the σ-(C60-)2 dimers) and 1330
nm (the (C60-)2 dimer bonded by two single bonds). Most
probably these bands are associated with charge transfer
dissociation. Most probably this pressure is the highest in 1
-
-
between two C60 anions in the dimer. The appearance of
as compared with other ionic complexes, in which σ-(C60
)
2
additional bands in the NIR range accompanies the formation
of all σ-bonded structures with negatively charged fullerenes.
For example, the σ-bonded (CoIITPP‚C60-) anions manifest
dimers are formed. In this context, the appearance of the
(C60-)2 dimers bonded by two single bonds in 1 is expected.
The interfullerene center-to-center distance of 9.054 Å in
these dimers is noticeably shorter than the distance of 9.251
Å in σ-(C60-)2 dimers. In this case the pressure should
stabilize the more compact (C60-)2 dimers bonded by two
single bonds rather than σ-(C60-)2 dimers, increasing their
relative content. In the limiting case, a pure phase with the
(C60-)2 dimers bonded by two single bonds is formed, as in
{CoIITMPP‚(MDABCO+)}2‚(C60-)2‚(C6H4Cl2)2.5‚(C6H5CN)1.5,
in which the dimers are located in the porphyrin cell held
together by the vdW forces.11
-
bands at 1092 and 1288 nm;26 (CoIITPP‚C60(CN)2 ) anions
-
at 1071 and ∼1210 nm;26a and σ-bonded (CoIIOEP‚C60
)
anions at 1086 and 1277 nm.15a The position of the first band
is close to that of the band of the intramolecular transitions
in the corresponding fullerene anions, whereas the broad low-
energy bands can also be attributed to charge transfer
between the fullerene anion and CoIIporphyrin in the
σ-bonded units. The attribution is more complicated for the
single-bonded (C70-)2 dimer showing two bands at 880 and
1240 nm.10,6a Since nonbonded C70•- radical anions manifest
one band at 1363-1386 nm,24 which correspondingly shifts
at the dimerization, it is difficult to correctly assign the bands
The dissociation of the single-bonded (C60-)2 dimers above
320-330 K results in the increase of the magnetic moment
1
of 1 in accordance with the formation of two new /2 spins
of the (C70-)2 dimer in the NIR range at present.
The spectral features of the negatively charged (C60
from C60•-. The EPR signal of the dimeric phase was
attributed to the (MnIITPP)2‚DMP units. The dissociation of
the σ-(C60-)2 dimers manifests a new broad Lorenz signal
with g ) 2.0179 and ∆H ) 65.5 mT, which most probably
-
)
2
dimers are similar to those observed for the electrochemically
(26) (a) Konarev, D. V.; Khasanov, S. S.; Otsuka, A.; Yoshida, Y.; Saito,
G. J. Am. Chem. Soc. 2002, 124, 7648. (b) Konarev, D. V.; Khasanov,
S. S.; Otsuka, A.; Yoshida, Y.; Lyubovskaya, R. N.; Saito, G. Chem.s
Eur. J. 2003, 9, 3837.
(27) Dunsch, L.; Rapta, P.; Gromov, A.; Stasˇko, A. J. Electroanal. Chem.
2003, 547, 35.
7608 Inorganic Chemistry, Vol. 46, No. 18, 2007

Ionic and Neutral C60 Complexes
appears due to exchange coupling between paramagnetic
be used in the design of new coordination assemblies with
metalloporphyrins.
•-
(MnIITPP)2‚DMP and C60 species.
The vis-NIR spectrum of the σ-(C60-)2 dimers shows
bands similar to those observed in the spectrum of C60•- (with
a shift of 11-17 nm) and a new band at 1356 nm, which
can be attributed to charge transfer between two C60- anions
in the dimer. Similar additional low-energy bands were
observed in the spectra of the (C60-)2 dimer bonded by two
single bonds11 and σ-bonded units formed by CoIIporphyrins
Acknowledgment. The work was partly supported by
Grant-in-Aid Scientific Research from the Ministry of
Education, Culture, Sports, Science and Technology, Japan
(152005019, COE programs) and the Russian Science
Support Foundation, INTAS YSF 05-109-4653 and RFBR
Grant N 06-03-32824 and RFBR-JSPS grant N 06-03-91361.
-
and C60 anions.15a,26b
Supporting Information Available: Crystallographic data for
1 and 2 in CIF format; IR spectra data for starting compounds and
1 and 2 (Tables S1 and S2); geometry of TPP macrocycles (selected
bond distances and bond angles in MIITPP (M ) Mn, Zn); and
shortest metal-ligand (M‚‚‚N), porphyrin-fullerene, and fullerene-
fullerene contacts (Table S3). This material is available via the
Internet at http://pubs.acs.org
Molecular structures of the coordination (MIITPP)2‚DMP
assemblies (M ) Mn, Zn) were studied for the first time.
Their formation elongates the equatorial M-N(DMP) bonds
and displaces the MII atom from the porphyrin plane toward
the ligand. Such changes are greater at the formation of the
(MnIITPP)2‚DMP units in 1 as compared with the (ZnTPP)2‚
DMP units in 2 and five-coordinated MnIITPP‚MeIm units.19
The data obtained show that the bidentant DMP ligand can
IC061628Z
Inorganic Chemistry, Vol. 46, No. 18, 2007 7609