Singly and Doubly Oxidized Phthalocyanine (pc) Rings: [Cu(pc)(ReO4)] and [Cu(pc)(ReO4)2]

Full text of DOI:10.1002/1521-3773(20010105)40:1<244::AID-ANIE244>3.0.CO;2-G

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approach, Deschenaux et al. were able to obtain an enantio-
tropic smectic A mesophase by functionalizing [60]fullerene
with 12 alkyl chains each terminated by a cyanobiphenyl
[6] J. H. Forsberg in Gmelin Handbook of Inorganic Chemistry: Sc, Y,
La ± Lu Rare Earth Elements (System No. 39, D3), Springer, Berlin,
1
981, pp. 65 ± 251,and references therein.
7] A. M. Giroud-Godquin, A. Rassat, C. R. Acad. Sci. Ser. 2 1982, 294,
41.
[8] H. X. Zheng, T. M. Swager, J. Am. Chem. Soc. 1994, 116, 761.
9] T. M. Swager, H. X. Zheng, Mol. Cryst. Liq. Cryst. 1995, 260, 301.
[
[
12]
group. It is therefore amazing to observe liquid crystallinity
2
in [Ln(dbm) ] complexes functionalized by only four alkyl
3
[
chains.
[
[
[
10] B. Gündogan, K. Binnemans, Liq. Cryst. 2000, 6, 851.
11] T. Chuard, R. Deschenaux, Helv. Chim. Acta 1996, 79, 736.
12] T. Chuard, R. Deschenaux, A. Hirsch, H. Schönberger, Chem.
Commun. 1999, 2103.
In conclusion, we obtained lanthanide-containing liquid
crystals by forming a bisadduct between tris(b-diketonato)-
lanthanide(iii) complexes and a salicylaldimine Schiff base.
Our method is a new approach to the design of lanthanide-
containing metallomesogens. This approach is versatile,
because the b-diketone ligand, the addend ligand, and the
lanthanide ion can be varied.
[13] R. G. Charles, A. Perrotto, J. Inorg. Nucl. Chem. 1964, 26, 373.
Experimental Section
Singly and Doubly Oxidized
Phthalocyanine (pc) Rings:
1H NMR spectra were obtained on a Bruker WM-250 spectrometer
(
250 MHz) using CDCl
FTIR spectrometer IFS66 (KBr pellet technique). Elemental analyses
CHN) were obtained on a CE-Instrument EA-1110 elemental analyzer.
3
as solvent. IR spectra were recorded on a Bruker
[
Cu(pc)(ReO )] and [Cu(pc)(ReO ) ]**
4
4 2
(
Anna S. Gardberg, Peter E. Doan, Brian M. Hoffman,*
and James A. Ibers*
Optical textures of the mesophases were observed with an Olympus BX60
polarizing microscope equipped with a LINKAM THMS600 hot stage and
a LINKAM TMS93 programmable temperature controller. DSC traces
were recorded with a Mettler± Toledo DSC821e module.
Numerous molecular conductors and semiconductors are
known that are based on partially oxidized macrocycles,[
1±4]
Synthesis of [Ln(dbm)
tion of the corresponding mono- and dihydrates in vacuo (10 mbar).
solution of [La(dbm) ] (3 mmol, 2.42 g) in absolute ethanol was added
3 2 3
L ]: [La(dbm) ] was obtained by careful dehydra-
�
3
[13]
A
and several singly oxidized metal phthalocyanine complexes
3
have been isolated.[
5, 6]
Doubly oxidized complexes are more
dropwise to a solution of 2-hydroxy-N-octadecyl-4-tetradecyloxybenzaldi-
mine (L) (3 mmol, 1.76 g) in absolute ethanol at 508C. The adduct
precipitated immediately. After the mixture had been stirred overnight at
room temperature, the precipitate was filtered off, washed with ethanol and
dried in vacuo. The compound is obtained as a pale yellow powder. Yield:
intriguing, with the most widely known example being
ªCompound Iº, which results from the double oxidation of
[7]
ferrihemes. This oxidation occurs by the loss of one electron
from the metal ion (giving formally iron(iv)) and one from the
�
1
2
.72 g (91%). IR (KBr): nÄ ˆ 1654 (CˆN, s), 1552 (CˆO, s) cm . Elemental
analysis calcd (%) for C123 10 (1980.6): C 74.57, H 8.91, N 1.42;
found: C 74.74, H 8.97, N 1.30.
ring. There are examples of crystalline doubly oxidized metal
H
2
175LaN O
phthalocyanine complexes[
8±11]
where both oxidations are
metal centered, but there are only a few reports of doubly
Received: August 21, 2000 [Z15664]
ring-oxidized metallophthalocyanine complexes, and these
only for solutions.[
12±14]
As far as we know there have been no
[
1] a) A. M. Giroud-Godquin, P. M. Maitlis, Angew. Chem. 1991, 103, 370;
Angew. Chem. Int. Ed. Engl. 1991, 30, 375; b) S. A. Hudson, P. M.
Maitlis, Chem. Rev. 1993, 93, 861; c) Metallomesogens, Synthesis,
Properties and Applications (Ed.: J. L. Serrano), Wiley-VCH, Wein-
heim, 1996; d) D. W. Bruce in Inorganic Materials (Eds.: D. W. Bruce,
D. OꢁHare), 2nd ed., Wiley, Chichester, 1996, Chap. 8, p. 429; e) B.
Donnio, D. W. Bruce, Struct. Bonding 1999, 95, 193; f) S. R. Collinson,
D. W. Bruce in Transition Metals in Supramolecular Chemistry (Ed.:
J. P. Sauvage), Wiley, New York, 1999, Chap. 7, p. 285.
reports of isolated compounds in which the phthalocyanine
(pc) ring is doubly oxidized.
We describe here the syntheses of the singly and doubly
oxidized compounds [Cu(pc)(ReO )] (1) and [Cu(pc)-
4
(
ReO ) ] (2), together with their characterization by means
4 2
of single-crystal X-ray diffraction (Figure1) and electron
paramagnetic resonance (EPR) methods. The structures of
these compounds differ from those of porphyrinic conduc-
[
[
2] D. W. Bruce, Adv. Mater. 1994, 6, 699.
3] R. Deschenaux, J. L. Marendaz, J. Chem. Soc. Chem. Commun. 1991,
[15]
[16]
tors and other singly oxidized derivatives in that they
contain isolated, rather than stacked, macrocycles. We show
909.
[
[
4] D. W. Bruce, X. H. Liu, J. Chem. Soc. Chem. Commun. 1994, 729.
5] a) K. Binnemans, Yu. G. Galyametdinov, S. R. Collinson, D. W. Bruce,
J. Mater. Chem. 1998, 8, 1551; b) K. Binnemans, R. Van Deun, D. W.
Bruce, Yu. G. Galyametdinov, Chem. Phys. Lett. 1999, 300, 6470;
c) Yu. G. Galyametdinov, G. I. Ivanova, I. V. Ovchinnikov, K. Binne-
mans, D. W. Bruce, Russ. Chem. Bull. 1999, 48, 385; d) K. Binnemans,
D. W. Bruce, S. R. Collinson, R. Van Deun, Yu. G. Galyametdinov, F.
Martin, Philos. Trans. R. Soc. London A 1999, 357, 3063; e) K.
Binnemans, Yu. G. Galyametdinov, R. Van Deun, D. W. Bruce, S. R.
Collinson, A. P. Polishchuk, I. Bikchantaev, W. Haase, A. V. Prosvirin,
L. Tinchurina, I. Litvinov, A. Gubajdullin, A. Rakhmatullin, K.
Uytterhoeven, L. Van Meervelt, J. Am. Chem. Soc. 2000, 122, 4335;
f) H. Nozary, C. Piguet, P. Tissot, G. Bernardinelli, J.-C. G. Bünzli, R.
Deschenaux, D. Guillon, J. Am. Chem. Soc. 1998, 120, 12274; g) J.
Boyaval, C. Li, M. Warenghem, P. Carette, Mol. Cryst. Liq. Cryst.
II
that these both are compounds of Cu , essentially unpertur-
bed by the oxidation. In 1 the pc ring is singly oxidized to pc
.
�
;
[
*] Prof. B. M. Hoffman, Prof. J. A. Ibers, A. S. Gardberg, Dr. P. E. Doan
Department of Chemistry and Materials Research Center
Northwestern University, 2145 Sheridan Road
Evanston, IL, USA 60208-3113 (USA)
Fax : (‡ 1)847-491-2976
E-mail: bmh@northwestern.edu
ibers@chem.northwestern.edu
[**] This work was supported by the MRSEC program of the National
Science Foundation (DMR-9632472) at the Materials Research
Center of Northwestern University and by the National Science
Foundation (CHE9727590, DMR9523228, BMH). We thank Syaulan
Yang and Thomas Carrell for their help.
1999, 330, 143 ± 150; h) F. Martin, S. R. Collinson, D. W. Bruce, Liq.
Cryst. 2000, 27, 859.
244
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0
in 2 the pc ring is doubly oxidized to pc . Compound 2 is the
To obtain information about the nature of the oxidation the
electronic structure of each compound was investigated by
EPR spectroscopy. Crystals of 1 were ground in KBr to
produce an isotropic sample for powder EPR analysis. A
spectrum taken at 35 GHz (Q-band) and 77 K showed a broad
peak, centered at g ˆ 3.7. We assign this resonance to the
0
first compound containing a pc ring to be isolated.
The galvanostatic oxidation of [Cu(pc)] in a 1-chloronaph-
thalene solution of [N(C H ) ][ReO ] yielded crystals of 1 and
. The structure of 1 is shown in Figure 1A. There are two
4
9
4
4
2
independent molecules in the asymmetric unit. They closely
ªhalf-fieldº transition (or Dm ˆÆ 2) of an S ˆ 1 spin system
s
with zero-field splitting (ZFS) that is large compared with the
‡
X-band microwave quantum. This implies that the [Cu(pc)]
moieties in the crystal exhibit a triplet state formed by the
9
II
exchange coupling of a d Cu center and a pc p radical
formed by the oxidation of the pc2 ring to pc . Such an S ˆ 1
�
�
II
state has been observed in frozen solutions of Cu porphyrin
radical species by means of EPR spectroscopy,[ and also by
17]
[16, 18]
means of magnetic-susceptibility measurements.
By anal-
ogy,[ we take the S ˆ 1 state of 1 to be the ground state.
19]
The absence of clear fundamental transitions (Dm ˆÆ 1) in
s
the present spectrum does not permit a precise determination
of the triplet-state zero-field splitting parameter (D) but
[20]
through the use of second-order perturbation theory we
�
1
estimate D ꢀ 0.5 cm (14 GHz), substantially larger than the
D parameter seen in the corresponding copper± porphyrin
�
1
[21, 22]
systems (0.116 cm ).
In the two extreme (S ˆ 1/2) valence-bond formulations of
III
�
2
, the compound would contain either Cu pc with a
8
III
.�
diamagnetic (d ) Cu center and an anion radical pc , or it
II
0
9
II
would contain Cu pc with a paramagnetic d Cu center and
0
a diamagnetic neutral pc . To determine the correct descrip-
tion, EPR studies of a single crystal were carried out.
A face-indexed crystal of 2 was fixed to a simple dual-axis
goniometer where the primary axis was a Kel-F rod perpen-
dicular to the applied field and the secondary axis was a Kel-F
screw. The crystal was aligned with its [101] direction along
the secondary axis of rotation so that one set of pc planes was
approximately perpendicular to the primary rotation axis.
EPR spectra were recorded at 108 intervals of rotation about
the primary axis. Figure 2 shows a spectrum for an orientation
Figure 1. Molecular structures of 1 (A) and 2 (B). The average Cu�O bond
length is 2.446(5) Š in 1 and is 2.526(5) Š in 2. Displacement ellipsoids are
set at the 50% probability level.
in which B is perpendicular to the plane of one of the sites,
0
along g . The values of g ˆ 2.16 and A ˆ 575 MHz derived
k
k
k
resemble one another, each consisting of a Cu(pc) unit with a
Cu�OReO linkage. The angle between the two independent
3
units is 68.56(4)8. The 24-atom cores of both of the symmetry-
independent macrocycles are essentially planar, the mean
deviations being 0.02(1) Š and 0.03(3) Š. The Cu atoms lie
0
.096(1) Š and 0.092(1) Š out of the planes of the 24-atom
cores, displaced toward the O atoms. In each macrocycle, one
of the fused benzene rings is slightly puckered. The maximum
out-of-plane distances are 0.163(7) Š and 0.307(7) Š. The
average Cu�N bond length is 1.957(8) Š; the Cu�O distances
are normal at 2.440(4) Š and 2.451(5) Š. The van der Waals
contacts between neighbors are 3.35 ± 3.37 Š.
The structure of 2 is shown in Figure 1B. The molecule,
which has a crystallographically imposed center of symmetry,
Figure 2. Single-crystal EPR spectrum of compound
orientation that maximizes the observed Cu hyperfine splitting. The
2 taken at an
consists of a Cu(pc) unit with two Cu�OReO linkages. The
3
measured A splitting is 190 G (575 MHz) at g ˆ 2.16. The observed line
k
k
mean deviation from the 24-atom core is 0.025(16) Š; the
maximum deviation is 0.082(8) Š. The average Cu�N dis-
tance is 1.97(1) Š; the Cu�O distance is 2.526(5) Š, longer by
k ?
widths of the individual hyperfine transitions in the g region and g peak
are both ꢀ200 MHz, suggesting that the A
?
(Cu) is close to zero. The crystal
was mounted and manipulated as described in the text. Experimental
conditions: Temperature 295 K; microwave frequency, 9.527 GHz; micro-
wave power, 200 mW; modulation amplitude, 10 G; scan time, 4 min.; time
constant, 64 ms.
0
.08 Š than the average value for 1 but still normal. The
packing displays a herringbone pattern.
Angew. Chem. Int. Ed. 2001, 40, No. 1
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245

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for this site are in good agreement with the values of 2.179 and
6
The spectrum also contains a narrow (40 G peak ± peak)
149171 (1) and CCDC-149172 (2). Copies of the data can be obtained free
of charge on application to CCDC, 12 Union Road, Cambridge CB21EZ,
UK (fax: (‡44)1223-336-033; e-mail: deposit@ccdc.cam.ac.uk).
05.5 MHz, respectively, for [Cu(pc)].[
23]
feature that occurs at g ˆ 2.04 and shows no resolved Cu (or
N) hyperfine splittings. Given the structure, this must
correspond to the perpendicular resonance for the magneti-
Received: September 19, 2000 [Z15824]
cally inequivalent molecule of 2. The observed value of g ˆ
?
[
1] J. A. Thompson, K. Murata, R. Durcharne, M. Poirier, B. M. Hoffman,
[
23]
2
.04 is in agreement with that of 2.05 for [Cu(pc)]. This line
Phys. Rev. B 1999, 60, 523 ± 529.
is substantially narrower than that of a Cu(pc) g feature. We
[2] J. A. Thompson, K. Murata, D. C. Miller, J. L. Stanton, W. E.
?
Broderick, B. M. Hoffman, J. A. Ibers, Inorg. Chem. 1993, 32, 3546 ±
attribute the decrease in line width in 2 to inter-ion exchange
3
553.
[
24]
effects in this magnetically concentrated crystal.
These measurements show that both the g tensor and the
[3] T. Inabe, S. Nakamura, W.-B. Liang, T. J. Marks, R. L. Burton, C. R.
Kannewurf, K.-ichi Imaeda, J. Am. Chem. Soc. 1985, 107, 7224 ± 7226.
6
3,65
Cu hyperfine interactions are negligibly perturbed when
[4] S. M. Palmer, J. L. Stanton, J. Martinsen, M. Y. Ogawa, W. B. Heuer,
S. E. Van Wallendael, B. M. Hoffman, J. A. Ibers, Mol. Cryst. Liq.
Cryst. 1985, 125, 1 ± 11.
2‡
the Cu(pc) unit is doubly oxidized to [Cu(pc)] . Thus, the
Cu ion remains in its d electronic configuration. The
similarities in the g values of [Cu(pc)] and Cu(pc) further
II
9
[
[
5] J. Metz, M. Hanack, J. Am. Chem. Soc. 1983, 105, 828 ± 830.
6] S. M. Palmer, J. L. Stanton, N. K. Jaggi, B. M. Hoffman, J. A. Ibers,
L. H. Schwartz, Inorg. Chem. 1985, 24, 2040 ± 2046.
2‡
k
show that the energy separation between the ground state
d
x2-y2
and the dxy orbitals are essentially the same in these two
[7] H. B. Dunford, Heme Peroxidases, Wiley, New York, 1999.
[
8] J. Janczak, M. Razik, R. Kubiak, Acta Crystallogr. Sect. C 1999, 55,
59 ± 361.
9] F. Gingl, J. Strähle, Z. Naturforsch. B 1988, 43, 445 ± 448.
compounds.
3
In summary, structural and EPR studies show that [Cu-
[
(pc)(ReO )] (1) contains Cu(pc) units singly oxidized at the
4
[10] V. Börschel, J. Strähle, Z. Naturforsch. B 1984, 39, 1664 ± 1667.
[11] K. Ukei, Acta Crystallogr. Sect. B 1982, 38, 1288 ± 1290.
[12] D. Lexa, M. Reix, J. Chim. Phys. Phys. Chim. Biol. 1974, 71, 511 ± 516.
13] M. E. Meray, A. Louati, J. Simon, A. Giraudeau, M. Gross, T.
Malinski, K. M. Kadish, Inorg. Chem. 1984, 23, 2606 ± 2609.
14] E. Ough, T. Nyokong, K. A. M. Creber, M. J. Stillman, Inorg. Chem.
1988, 27, 2724 ± 2732.
ring to produce the spin triplet formed by ferromagnetic
9
II
coupling between the d Cu ion and a p radical delocalized
on the ring. Compound 2, [Cu(pc)(ReO ) ] which contains
[
[
[
4
2
Cu(pc)]2 moieties, also retains the paramagnetic Cu center,
‡
II
[
0
and thus contains a diamagnetic, doubly oxidized pc ring.
15] J. A. Ibers, L. J. Pace, J. Martinsen, B. M. Hoffman, Struct. Bonding
(
Berlin) 1982, 50, 1 ± 55.
Experimental Section
[16] B. S. Erler, W. F. Scholz, Y. J. Lee, W. R. Scheidt, C. A. Reed, J. Am.
Chem. Soc. 1987, 109, 2644 ± 2652.
Single crystals of both 1 and 2 grew at the anode of an electrolytic cell that
[17] M. Losada, J. Mol. Catal. 1975/76, 1, 245 ± 264.
[18] W. F. Scholz, C. A. Reed, Y. J. Lee, W. R. Scheidt, G. Lang, J. Am.
Chem. Soc. 1982, 104, 6791 ± 6793.
[19] P. Gans, G. Buisson, E. Du e e, J.-C. Marchon, B. S. Erler, W. F. Scholz,
C. A. Reed, J. Am. Chem. Soc. 1986, 108, 1223 ± 1234.
[20] W. A. Yager, E. Wasserman, R. M. R. Cramer, J. Chem. Phys. 1962, 37,
1148.
[21] H. Fujii, Inorg. Chem. 1993, 32, 875 ± 879.
[22] S. Konishi, M. Hoshino, M. Imamura, J. Am. Chem. Soc. 1982, 104,
2057 ± 2059.
[23] S. E. Harrison, J. M. Assour, J. Chem. Phys. 1964, 40, 365 ± 370.
[24] K. W. Plumlee, B. M. Hoffman, J. A. Ibers, Z. G. Soos, J. Chem. Phys.
1975, 63, 1926 ± 1942.
[25] A. Wolberg, J. Manassen, J. Am. Chem. Soc. 1970, 92, 2982 ± 2991.
[26] SMART Version 5.054 Data Collection and SAINT-Plus Version
consisted of two compartments separated by a glass frit. The [Cu(pc)]
[
2]
starting material was synthesized by metallation of very pure H
CuCl ´ xH O (99.9999%, dehydrated), followed by repeated sublimation.
The electrolytic cell was protected from light, kept purged with dry N , and
maintained at 120(5)8C. Each half-cell contained a solution of 1-chloro-
naphthalene (20 mL) that was 0.013m in [N(n-Bu) ][ReO ]; the solution in
the anode compartment was saturated with [Cu(pc)] ([Cu(pc)] < 10 m;
2
(pc) with
2
2
2
4
4
�
3
1
[25]
E
ox ˆ 0.98 V versus SCE ). A 2.0 mA current was passed through the cell
by platinum electrodes for three weeks, during which time the initially blue
solution turned green. A few dark-purple crystals of 1 and several dark-red
crystals of 2 grew on the anode in about a 1:10 ratio. These crystals were
separated manually. The Cu:Re ratio of each crystal was determined by
energy dispersive spectroscopy to provide a confirmation of the visual
identification. Both compounds are air and light stable.
6
.02A Data Processing Software for the SMART System. (Bruker
General crystallographic details: Bruker Smart 1000 CCD diffractome-
[
26]
Analytical X-Ray Instruments, Inc., Madison, WI, USA, 2000).
27] G. M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46, 467 ± 473.
[28] G. M. Sheldrick SHELXTL DOS/Windows/NT Version 5.10. (Bruker
ter,
MoKa radiation (l ˆ 0.71073 Š), w-scans, Tˆ 153 K. For 1, two
[
hemispheres were collected, one at 2q ˆ � 288, the other at 2q ˆ � 758. The
[27]
structures were solved by direct methods and refined with the program
[28]
Analytical X-Ray Instruments, Inc., Madison, WI, USA, 1999).
SHELXTL. Face-indexed absorption corrections were performed in the
program XPREP.[ All non-hydrogen atoms were refined anisotropically,
and hydrogen atoms were allowed to ride on their respective carbon atoms.
28]
Crystal structure analysis of 1: C32
H
16CuN
8
O
4
Re, dark purple prism, 0.42 Â
0
2
2
1
0
.25 Â 0.24 mm, monoclinic, P2
1
/c, a ˆ 20.455(4) b ˆ 11.947(2), c ˆ
3
7.327(6) Š, b ˆ 126.86(3)8, Vˆ 5343.4(19) Š , Tˆ 153 K, Z ˆ 8, 1calcd
ˆ
�
3
.054 gcm , 2qmax ˆ 56.68, 32531 reflections measured, 12544 unique,
�
1
0343 observed with I > 2s(I). m ˆ 53.8 cm , min/max transmission ˆ 0.19/
.35. R ˆ 0.127 (all data). Crystal structure analysis of 2:
ˆ 0.064, wR
Re
, Deep red polyhedron, 0.24 Â 0.37 Â 0.49 mm, mono-
1
2
C
32
H
16CuN
8
O
8
2
clinic, P2
1
/c, a ˆ 8.9825(18), b ˆ 9.3147(19), c ˆ 17.712(4) Š, b ˆ 95.96(3)8,
3
� 3
Vˆ 1474.0(5) Š , Tˆ 153 K, Z ˆ 2, 1calcd ˆ 2.425 gcm , 2qmax ˆ 56.548, 9208
reflections measured, 3541 unique, 3223 observed with I > 2s(I). m ˆ
�
1
89.8 cm
,
min/max transmission ˆ 0.063/0.18.
R
1
ˆ 0.0550, wR ˆ 0.128
2
(
all data). Crystallographic data (excluding structure factors) for the
structures reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication no. CCDC-
246
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Angew. Chem. Int. Ed. 2001, 40, No. 1