High-spin polyarylmethyl polyradical: Fragment of a macrocyclic 2-strand based upon calix[4]arene rings

Article abstract of DOI:10.1021/ja971493j

Annelated triple-calix[4]arene-based tetradecaether 1-(OMe)₁₄ is synthesized. Its three isomers, 1X-(OMe)₁₄, 1Y-(OMe)₁₄, 1Z-(OMe)₁₄, are isolated and characterized. The corresponding triarylmethyl carbopolyanion

Full text of DOI:10.1021/ja971493j

J. Am. Chem. Soc. 1997, 119, 10335-10345
10335
High-Spin Polyarylmethyl Polyradical: Fragment of a
Macrocyclic 2-Strand Based upon Calix[4]arene Rings
Andrzej Rajca,* Kan Lu, and Suchada Rajca
Contribution from the Department of Chemistry, UniVersity of Nebraska,
Lincoln, Nebraska 68588-0304
ReceiVed May 7, 1997X
Abstract: Annelated triple-calix[4]arene-based tetradecaether 1-(OMe)14 is synthesized. Its three isomers, 1X-
(OMe)14, 1Y-(OMe)14, 1Z-(OMe)14, are isolated and characterized. The corresponding triarylmethyl carbopolyanion
is prepared and oxidized to polyradical 1. SQUID magnetometry for 1 in THF-d8/2-MeTHF gives S ) 6.2, below
the theoretical value of 7 expected for strong ferromagnetic coupling between 14 “unpaired” electrons. Chemical
quenching studies suggest that approximately one deuterium from the deuterated solvent is incorporated in 1, thus
accounting in part for S < 7. Study of the temperature dependence of magnetization indicates that ferromagnetic
coupling between “unpaired” electrons is not very strong in 1; i.e., the thermal population of low-spin excited states
is detected in the cryogenic temperature range. Upon exposure of 1 in THF-d8/2-MeTHF to ambient temperature
for 30 min, a narrow distribution of spin systems with an “average” S ) 2.5 is obtained; upon a longer exposure
time of 24 h, an “average” S ) 1 is produced.
Introduction
Two- and three-dimensional networks are prerequisites for
numerous interesting magnetic phenomena.1 Networks of
organic π-conjugated polyradicals, in which strong through-
bond ferromagnetic couplings are achieved, may provide a route
to an organic ferromagnet with a high Curie temperature.2,3 From
the synthetic point of view, polyradical networks, which are
highly annelated polymacrocyclic systems, are difficult targets.4,5
Oligomeric fragments of 2-strand are more straightforward
synthetic goals (Figure 1).3d Trimeric fragments of 2-strand,
with three linearly annelated macrocyclic rings, are especially
attractive targets, accessible by convergent synthetic routes.
Representative examples of such molecules are provided by
annelated calix[4]arenes, annelated macrocyclic DNA strands,
or annelated tetra-o-phenylenes.6,7
Calix[4]arene-based polyradicals have been shown to have
adequate properties as high-spin building blocks.4,8,9 Synthesis
X Abstract published in AdVance ACS Abstracts, October 15, 1997.
(1) Mattis, D. C. The Theory of Magnetism II; Springer-Verlag: Heidel-
berg, 1985.
(2) Mataga, N. Theor. Chim. Acta 1968, 10, 372.
Figure 1. 2-Strand, tetradecaradical 1(‚)14 and spin cluster correspond-
ing to 1(‚)14. Full circles in the 2-strand indicate sites for “unpaired”
electrons (e.g., triarylmethyl sites). Circles and lines in the spin cluster
representation correspond to sites with “unpaired” electrons and spin
coupling pathways through 1,3-phenylene moieties, respectively.
(3) For recent reviews on high-spin organic molecules, see: (a) Iwamura,
H. AdV. Phys. Org. Chem. 1990, 26, 179. (b) Dougherty, D. A. Acc. Chem.
Res. 1991, 24, 88. (c) Iwamura, H.; Koga, N. Acc. Chem. Res. 1993, 26,
346. (d) Rajca, A. Chem. ReV. 1994, 94, 871. (e) Miller, J. S.; Epstein, A.
J. Angew. Chem., Int. Ed. Engl. 1994, 33, 385. (f) Yoshizawa, K.; Hoffmann,
R. Chem. Eur. J. 1995, 1, 403.
(4) Rajca, A. In Molecule-Based Magnetic Materials; Turnbull, M. M.,
Sugimoto. T., Thompson, L. K., Eds.; ACS Symposium Series 644;
American Chemical Society: Washington, DC, 1996; Chapter 17, pp 258-
265.
(5) For selected attempts to synthesize high-spin organic networks, see:
Torrance, J. B.; Oostra, S.; Nazzal, A. Synth. Met. 1987, 19, 709. Bushby,
R. J.; Ng, K. M. Chem. Commun. 1996, 659.
(6) Bo¨hmer, V.; Do¨rrenba¨cher, R.; Vogt, W.; Zetta, L. Tetrahedron Lett.
1992, 769. Bo¨hmer, V.; Do¨rrenba¨cher, R.; Frings, M.; Heydenreich, M.;
de Paoli, D.; Vogt, W.; Ferguson, G.; Thondorf, I. J. Org. Chem. 1996, 61,
549.
(7) For polymacrocyclic DNA fragments, see: Chen, J.; Seeman, N. C.
Nature 1991, 350, 631. For a polyphenylene double-helix, see: Rajca, A.;
Safronov, A.; Rajca, S.; Schoemaker, R. Angew. Chem., Int. Ed. Engl. 1997,
36, 488.
and studies of an annelated calix[4]arene, such as the tri-
macrocyclic tetradecaradical 1(‚)14, is an initial step toward the
synthesis of highly annelated polymacrocyclic polyradicals
(Figure 1).3d
For a polyradical with high-spin ground state, ferromagnetic
coupling between “unpaired” electrons is a prerequisite.10 For
1(‚)14, this condition is satisfied through linking triarylmethyl
sites with 1,3,5-phenylyne moieties.10,11 However, some “un-
paired” electrons will not be generated, due to side (or
incomplete) chemical reactions; we refer to such triarylmethyl
sites as defects.8,12 The high degree of connectivity, associated
(8) For macrocyclic polyarylmethyls, see: Rajca, A.; Rajca, S.; Padma-
kumar, Angew. Chem., Int. Ed. Engl. 1994, 33, 2091. Rajca, A.; Rajca, S.;
Desai, S. R. J. Am. Chem. Soc. 1995, 117, 806.
(9) For macrocyclic polycarbenes, see: Matsuda, K.; Nakamura, N.;
Takahashi, K.; Inoue, K.; Koga, N.; Iwamura, H. J. Am. Chem. Soc. 1995,
117, 5550.
S0002-7863(97)01493-5 CCC: $14.00 © 1997 American Chemical Society

10336 J. Am. Chem. Soc., Vol. 119, No. 43, 1997
Rajca et al.
Scheme 1. Synthesis of Triple-Calix[4]arene Tetradecaethers 1-(OMe)14 (The Three Isolated Isomers Are Labeled 1X-(OMe)14,
1Y-(OMe)14, and 1Z-(OMe)14)
with a 2-strand, as illustrated by a cluster representation for
1(‚)14, may help to maintain π-conjugation and ferromagnetic
coupling between all remaining electrons (Figure 1). In order
to quantitatively evaluate the impact of defects on ferromagnetic
coupling in a high-spin polyradical, it is convenient to define a
parameter (Q), the percentage of polyradicals, in which all
remaining “unpaired” electrons are contained in a single spin
system with uninterrupted coupling.13 For example, if a yield
for generation of site with “unpaired” electron is 95%, the
following values of Q are obtained: 98, 97, and 96% for
2-strands with 14, 26, and 38 sites (Figure 1, n ) 1, 3, and
5),13 99 and 94% for monomacrocycles with 8 and 14 sites,8,13
∼70 and ∼50% for dendrimers with 15 and 31 sites,14 and
∼25% for a linear chain with 30 sites.15 Therefore, high-spin
polyradicals, based on 2-strands, should posses ferromagnetic
coupling even in the presence of moderate density of defects.
This paper describes synthesis and magnetic studies of
2-strand trimacrocyclic high-spin polyradical.
Results and Discussion
1. Synthesis of Annelated Trimacrocyclic Tetradecaether
1-(OMe)14. The synthesis is based upon a convergent route,
i.e., the construction of the two outer calix[4]arene rings
precedes the assembly of the center ring. Because of large
number of possible cis/trans isomers for 1-(OMe)14, only one
of the most abundant isomers of the outer calix[4]arene ring is
used in the synthesis.
Addition of methyl 4-tert-butylbenzoate to 2 equiv of
monolithiated 1,3,5-tribromobenzene16 in ether produces alcohol
2; subsequent etherification of 2 with sodium hydride/iodo-
methane gives ether 3 (Scheme 1). Double Li/Br exchange of
(10) Borden, W. T.; Davidson, E. R. J. Am. Chem. Soc. 1977, 99, 4587.
Fang, S.; Lee, M.-S.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc.
1995, 117, 6727. Ovchinnikov, A. A. Theor. Chim. Acta 1978, 47, 297.
West, A. P., Jr.; Silverman, S. K.; Dougherty, D. A. J. Am. Chem. Soc.
1996, 118, 1452.
(11) For selected examples of organic high-spin molecules and polymers,
see: Nakamura, K.; Inoue, K.; Iwamura, H. Angew. Chem., Int. Ed. Engl.
1993, 32, 872. Murray, M. A.; Kaszynski, P.; Kaisaki, D. A.; Chang, W.-
H.; Dougherty, D. A. J. Am. Chem. Soc. 1994, 116, 8152. Matsuda, K.;
Nakamura, N.; Inoue, K.; Koga, N.; Iwamura, H. Bull. Chem. Soc. Jpn.
1996, 69, 1483. Nishide, H.; Kaneko, T.; Nii, T.; Katoh, K.; Tsuschida, E.;
Lahti, P. J. Am. Chem. Soc. 1996, 118, 9695.
(14) Rajca, A.; Utamapanya, S. J. Am. Chem. Soc. 1993, 115, 10688.
(15) Utamapanya, S.; Kakegawa, H.; Bryant, L.; Rajca, A. Chem. Mater.
1993, 5, 1053.
(16) For 3,5-dibromophenyllithium, see: Chen, G. J.; Tamborski, C. J.
Organomet. Chem. 1983, 251, 149.
(12) Rajca, S.; Rajca, A. J. Am. Chem. Soc. 1995, 117, 9172.
(13) Rajca, A. In Modular Chemistry: Michl, J., Ed.; Kluwer Academic
Publications: Dordrecht, The Netherlands; in press.

High-Spin Polyarylmethyl Polyradical
J. Am. Chem. Soc., Vol. 119, No. 43, 1997 10337
Figure 2. Cis/trans isomers of calix[4]arene diols 6. “Ar” corresponds
to 4-tert-butylphenyl.
3 with t-BuLi in THF followed by addition of 1-(4-tert-
butylbenzoyl)pyrrolidine and hydrolysis provides diketone 4.
In the macrocyclization step to form the outer calix[4]arene ring,
5 (0.010 M in THF) is subjected to double Li/Br exchange with
t-BuLi (1.7 or 1.5 M in pentane); subsequently, diketone 4
(0.025 M in THF) is rapidly cannulated to a precooled (-78
°C) solution of the dilithium compound.8,17 Four cis/trans
isomers for calix[4]arene diol 6 are isolated [6A (7%), 6B (11%),
6C (7%), and 6D (variable, very small yields)] in the order of
increasing polarity on silica gel. Compounds 6A and 6B have
no elements of symmetry; 6C and 6D have a symmetry plane
on the NMR time scale. Among six possible cis/trans isomers
for diol 6, two of them have no elements of symmetry and the
other four have a symmetry plane (Figure 2). The two possible
nonsymmetrical isomers correspond to 6A and 6B.
Etherifications of 6A-C provide the corresponding isomers
7A-C. The isomer 7B is selected for further synthetic
transformations. Following conversion of 7B to diketone 8, the
macrocyclization step to form the center calix[4]arene ring
mimics the procedure outlined above, except 7B and 8 (0.013
M in THF) are used in the place of 5 and 4.8,17 Three isomers
are isolated for triple-calix[4]arene diol: 9X (∼8%), 9Y (∼9%),
and 9Z (∼9%); the first two isomers have no element of
symmetry, and the third one has a 2-fold element of symmetry
on the NMR time scale. Etherifications of 9X-Z give the
corresponding tetradecaethers 1X-(OMe)14, 1Y-(OMe)14, and
1Z-(OMe)14.18
Figure 3. FAB MS for 1Y-(OMe)14. (A) Partial low-resolution
spectrum. (B) Stick plot for the (M - OCH3)+ ion cluster from the
high-resolution spectrum. (C) Calculated stick plot for the (M -
OCH3)+ ion cluster with formula C255H297O13 at natural isotopic
abundance.
13C DEPT/NMR spectra are obtained for most synthetic
intermediates in Scheme 1, except for all triple-calix[4]arene
derivatives, which are available only in small amounts. The
spectra are analyzed by comparing numbers of the expected
and measured resonances in distinct spectral regions (e.g.,
quaternary aromatic). Several spectral overlaps are encountered
for each calix[4]arene derivative, containing between 47 and
98 nonequivalent carbon atoms. Among the least resolved
spectral regions are methyl carbons of the t-Bu groups and
nonquaternary carbons in the aromatic region.
All compounds with only one calix[4]arene ring have sharp
1H NMR spectra at ambient temperature. For triple-calix[4]-
arene derivatives, 1H NMR spectra at ambient temperature are
broadened. However, at elevated temperatures (348 K), sharp
spectra are obtained, suggesting fast exchange between con-
formations on the NMR time scale (Figures 4 and 5).
IR spectra show the presence of the OH groups in the products
of both macrocyclization steps, calix[4]arene diols 6A-D and
triple-calix[4]arene diols 9X and 9Y.
In FAB MS, all 14 macrocylic intermediates give the expected
(M - OCH3)+ cluster ions as the most intense signals in the
high mass range; the diols show additional, moderately intense
(M - OH)+ cluster ions. Measured and calculated isotopic
distributions for (M - OCH3)+ cluster ions show satisfactory
agreement. FAB MS for triple-calix[4]arene 1Y-(OMe)14 is
shown in Figure 3.
1
All synthetic intermediates in Scheme 1 possess H reso-
nances in three regions: aromatic (8.8-6.3 ppm), C-OCH3/C-
OH moieties (3.2-2.1 ppm), and tert-butyl groups (1.4-1.1
ppm) (Figures 4 and 5). For selected macrocylic polyethers,
1
aromatic regions are analyzed with the help of H-1H COSY
correlations. The following discussion of the 1H NMR spectra
for two isomers of triple-calix[4]arene tetradecaether, 1Y-
(OMe)14 and 1Z-(OMe)14, highlights the spectral patterns
encountered in all other macrocyclic derivatives described in
this work.
Most NMR spectra are obtained in CDCl3. However, for
some polyethers with large number of Ar3COX (X ) H, CH3)
moieties, benzene-d6 and cyclohexane-d12 are used as solvents.
The isomer 1Y-(OMe)14, which lacks elements of symmetry
1
on the NMR time scale, gives the most complex H NMR
1
spectrum in the aromatic region. In the COSY spectrum, there
are 48 “singlet” off-diagonal peaks, 32 “quadruplet” off-diagonal
peaks, and two singlets without off-diagonal peaks. The 48
“singlet” off-diagonal peaks correlate 24 1-proton triplet (J ≈
2 Hz) resonances (eight 3-proton AMX/ABC spin systems),
corresponding to the eight inner benzene rings. The 32
“quadruplet” off-diagonal peaks correlate 32 2-proton doublet
(J ≈ 9 Hz) resonances (16 4-proton AX/AB spin systems),
corresponding to 16 outer benzene rings (4-tert-butylphenyls).
The two prominent singlets (at 7.214 and 7.181 ppm) are two
For selected diols, 6C, 6D, 9Y, 9Z, H NMR spectra are also
recorded in the presence of small amounts of D2O in order to
identify resonances corresponding to the OH groups.
(17) Rajca, A.; Padmakumar, R.; Smithhisler, D. J.; Desai, R. S.; Ross,
C. R.; Stezowski, J. J. J. Org. Chem. 1994, 59, 7701.
(18) Detailed analysis of the possible isomers for the annelated triple-
calix[4]arenes is complicated because 7B, used in the synthesis, corresponds
to one of the two nonsymmetrical isomers of 7. Another problem is the
possibility of the noninterconverting (rigid) conformations for the center
calix[4]arene ring (ref 6). We thank the reviewer for pointing out rigidity
of the center ring in the annelated triple-calix[4]arenes.

10338 J. Am. Chem. Soc., Vol. 119, No. 43, 1997
Rajca et al.
Figure 4. 1H NMR (500 MHz, C6D6) spectrum for 1Y-(OMe)14 at 348 K. Main plot: full spectrum, EM ) -1.85, GB ) 1.20. Insert plot: 1H-1H
COSY correlation in the aromatic region.
diagonal peaks correlate 12 2-proton triplets (J ≈ 2 Hz),
corresponding to four pairs of the inner benzene rings. The 20
“quadruplet” off-diagonal” peaks correlate 4 2-proton and 16
4-proton doublets (J ≈ 9 Hz), corresponding to two single and
eight pairs of the outer benzene rings.
For all 14 macrocyclic intermediates, most peaks are resolved
for the C-OCH3/C-OH moieties, with the exception of accidental
spectral overlaps. This spectral region is the least congested
and provides the best insight into purity of triple-calix[4]arene
derivatives. The 1H NMR spectrum for 1Y-(OMe)14 at 348 K
shows 12 3-proton and 1 6-proton resonances, in addition to
several small peaks. The latter may correspond to another
isomer of tetradecaether or an unknown impurity. However,
14 3-proton singlets can be resolved at 328 K (Figure 5). For
the symmetrical isomer, 1Z-(OMe)14, 6 sharp and 1 broadened
6-proton resonances are found at 348 K.
In the t-Bu group region, the number of singlet resonances
equals to the number of the AX/AB spin systems with J ≈ 9
Hz for the aromatic protons, except for accidental spectral
overlaps. For 1Y-(OMe)14, 14 9-proton and 2 18-proton
resonances are resolved. For the symmetrical isomer, 1Z-
(OMe)14, at 348 K, 5 18-proton and 1 54-proton resonances
are resolved, in addition to 1 18-proton resonance overlapped
with the signal from the solvent.
1
The analysis of the H NMR spectra for 1Y-(OMe)14 (and,
analogously, for 1X-(OMe)14) indicates lack of elements of
symmetry on the NMR scale for this isomer. However, for 1Z-
(OMe)14 2-fold element of symmetry, which divides the center
calix[4]arene ring, is found. Eight 4-tert-butylphenyls, associ-
ated with the exocyclic triarylmethyl centers, appear as four
Figure 5. Partial 1H NMR (500 MHz, C6D6) spectra for 1Y-(OMe)14
in the C-OCH3 region. Top: 298 K, EM ) 0.10. Middle: 328 K, EM
) -1.85, GB ) 1.20. Bottom: 348 K, EM ) -1.85, GB ) 1.20.
diastereotopic pairs.
2. Preparation and Quenching Studies of Annelated
Trimacrocyclic Polyradical 1. In these studies, isomers, 1X-
(OMe)14, 1Y-(OMe)14, and 1Z-(OMe)14 are typically used as
a mixture, designated as 1-(OMe)14. Polyradicals are generated
by the sequential procedure, similar to that described previ-
collapsed 4-proton AB systems, corresponding to the remaining
two outer benzene rings (4-tert-butylphenyls) (Figure 4).
The symmetrical isomer, 1Z-(OMe)14, provides much simpler
picture. In the COSY45 spectrum, there are 24 “singlet” and
20 “quadruplet” off-diagonal” peaks. The 24 “singlet” off-

High-Spin Polyarylmethyl Polyradical
J. Am. Chem. Soc., Vol. 119, No. 43, 1997 10339
Scheme 2. Generation of Polyradical 1 and Quenching
Studies Where “Ar” Corresponds to 4-tert-Butylphenyl
ously,19,20 but with modifications to accommodate micromolar
scale (Scheme 2).
Treatment of tetradecaether 1-(OMe)14 with an excess of
Na/K alloy in tetrahydrofuran (THF) or tetrahydrofuran-d8
(THF-d8) gives red solutions of the corresponding carbopoly-
anion. A quenching experiment is carried out in order to verify
structure of carbopolyanion. When the carbopolyanion is
prepared in THF and treated with MeOH, hydrocarbon 1-(H)14
Figure 6. SQUID magnetometry (H ) 0-5.0 T) for polyradical 1 in
THF-d8/2-MeTHF. Main plot: M/Msat vs H/(T - θ), θ ) -0.34 K;
the experimental points are obtained at T ) 2, 3, and 5 K. The lines
correspond to the S ) 5, 6, and 7 Brillouin functions. The fitting
parameters at T ) 2, 3, and 5 K are S ) 6.20, 6.22, and 6.20 and Msat
× 103 ) 6.03, 6.03, and 5.98 emu; the parameter dependence is 0.33,
0.44, and 0.60. Insert: plot of MT vs T at H ) 0.5 T.
1
is isolated. The H NMR spectra of 1-(H)14 consist of broad
resonances suggesting a complex mixture of isomers possessing
aromatic, triarylmethane (Ar3CH), and tert-butyl hydrogens and
devoid of CH3O groups. FAB MS shows (M - H)+ ion cluster,
with the most intense isotopic component at m/z 3179.1.21
Oxidation of the carbopolyanion in THF-d8 with I2, at the
temperatures close to the freezing point of the reaction mixture,
gives the annelated trimacrocyclic polyradical 1. [The addition
of I2 in small portions is accompanied by transfers of small
amounts of THF-d8 or 2-methyltetrahydrofuran (2-MeTHF).]
Part of the reaction mixture is transferred at low temperature to
a quartz tube, flame sealed, and stored in liquid nitrogen for
magnetic studies; the remaining reaction mixture in the oxidation
vessel is stirred with Na/K alloy at low temperature and,
subsequently, treated with MeOH or MeOD.
The hydrocarbon product isolated from the MeOH-quench
of polyradical 1 in THF-d8 gives and 1H NMR spectrum similar
to that for 1-(H)14. However, FAB MS shows an ion cluster
with identical isotopic peak height pattern, which is shifted by
+1 amu, compared to that for 1-(H)14.22,23 This discrepancy
may result from errors in integrations in the 1H NMR spectrum.
Because of large numbers of protons and broadeness of peaks,
such errors may be on the order of |1H|. These results are
compatible with 1-(H)13(D)1 (D1 isotopomer of 1-(H)14), for
which (M - H)+ cluster is observed in FAB MS.
shift corresponding to triarylmethane deuteria is observed in
the H NMR spectrum. FAB MS shows an ion cluster with
2
significantly wider isotopic distribution, shifted by +12/13 amu,
compared to that for 1-(H)14. Because of the possible isotope
effects, the contributions of (M - D)+, (M - H)+, and other
plausible clusters to the overall intensity is not known;
consequently, the relative amounts of D14-D11 isotopomers are
difficult to estimate. This product, labeled 1-(D)14, corresponds
to a distribution of highly deuterated isotopomers of 1-(H)14.
Magnetization (M) is measured as a function of magnetic field
(H ) 0-5.0 T) and temperature (T ) 1.8-130 K) for 0.001 M
1 in THF-d8/2-MeTHF or 1 in THF-d8, using a SQUID
magnetometer.
For 1 in THF-d8/2-MeTHF, the M vs H data at T ) 2, 3, and
5 K are initially fit to a Brillouin function, M vs H/T, with two
variable parameters, spin, S, and magnetization at saturation,
Msat. However, temperature-dependent values of S are obtained,
suggesting presence of small antiferromagnetic interactions.
Introduction of a mean-field parameter, θ ) -0.34, i.e.,
replacing H/T with H/(T - θ), gives an adequate fit with S )
6.2 (Figure 6).24 When the sample is melted at 130 K and,
then, slowly refrozen in the magnetometer, S does not change
but |θ| decreases from 0.34 to 0.23. Analogous analysis for 1
in THF-d8 gives S ) 5.8 and a very small |θ| < 0.05 K (θ <
0) but the fit to Brillouin function is not as good as for the
sample with S ) 6.2 (Figure 7). Increasing temperature of the
sample to 170 K, followed by slow cooling in the magnetometer,
also decreases |θ|.
The hydrocarbon product isolated from MeOD quench of
1
polyradical 1 in 2-MeTHF/THF-d8 gives a H NMR spectrum
with integration suggesting presence of approximately two
triarylmethane hydrogens. Also, a broad singlet at the chemical
The M vs T data at constant H ) 0.5 T are plotted as MT vs
T (Figures 6 and 7, insert plots). A downward turn of the plot
at low T is consistent with both negative mean-field parameter
(θ < 0) and partial saturation of M at low T. More important
is the downward slope at high T, suggesting thermal population
of low-spin excited states; that is, the intramolecular ferro-
magnetic coupling is not strong.
(19) Rajca, A. J. Am. Chem. Soc. 1990, 112, 5890.
(20) Rajca, A.; Rajca, S. J. Am. Chem. Soc. 1996, 118, 8121.
(21) Isotopic intensities in FAB MS for low molecular weight calix[4]-
arene-based polyarylmethanes are compatible with M+ and (M + H)+
clusters (ref 8).
(22) The +1 amu mass shift of the (M - H)+ clusters between 1-(H)14
and 1-(H)13(D)1 was confirmed by repeating FAB MS analysis for both
compounds, using a narrow mass range, high-resolution scan with identical
mass calibration.
(23) The amount of 1-(H)13(D)1 was insufficient to permit observation
of its H NMR spectrum in a reasonable acquisition time.
(24) Carlin, R. L. Magnetochemistry; Springer-Verlag: Berlin, 1986.
Also, see: note 28.
2

10340 J. Am. Chem. Soc., Vol. 119, No. 43, 1997
Rajca et al.
Figure 8. Tentative structure for polyradical 1 and the corresponding
symmetric trimer model. “Ar” corresponds to 4-tert-butylphenyl.
Figure 7. SQUID magnetometry (H ) 0-4.8 T) for polyradical 1 in
THF-d8. Main plot: M/Msat vs H/(T - θ), θ ) -0.025 K; the
experimental points are obtained at T ) 1.8, 3, and 5 K. The lines
correspond to the S ) 5, 6, and 7 Brillouin functions. The fitting
parameters at T ) 1.8, 3, and 5 K are S ) 5.77, 5.78, and 5.76 and
Msat × 103 ) 3.85 emu at all temperatures; the parameter dependence
is 0.29, 0.42, and 0.63. Insert: plot of MT vs T at H ) 0.5 T.
The lower value of S, compared to the theoretical S ) 7 for
a perfect high-spin tetradecaradical, may be explained by the
presence of defects. Quenching experiments suggest that in the
reaction sequence in Scheme 2, one deuteron (or deuterium) is
abstracted from the solvent, at the stage of carbopolyanion (or
tetradecaradical); this would lead to a polyradical with S ) 6.5.
Furthermore, inadvertent moisture, excess of I2, dimerization,
etc., could further lower the average S to the observed value of
S ) 6.2 for 1 in THF-d8/2-MeTHF and S ) 5.8 for 1 in THF-
d8. Differences in values of S between the two types of samples
may arise from different temperatures at which their oxidations
are carried out; that is, the melting points (or softening range)
of the two reaction mixtures are significantly different. The
sites of the defects, corresponding to lowering value of S from
7 to 6.2 and 5.8, could not rigorously be determined.
For isolated polyradicals, in which intramolecular ferro-
magnetic coupling between all its “unpaired” electrons is
associated with energy exceeding RT (strong coupling), the data
M vs H/T should follow one Brillouin function and the plot
MT vs T should be flat throughout the T range; i.e., the
polyradical would behave as a perfect paramagnet. The drop
off in the MT vs T plot at high T suggests the presence of low-
lying low-spin excited state(s). One of the possible structures
is shown in Figure 8. Our speculation is that strain in the center
calix[4]arene ring may increase basicity of its arylmethyl
carbanion sites and, therefore, facilitate formation of the defect.
Furthermore, severe twisting of arylmethyl bonds around the
remaining site with “unpaired” electron in the center calix[4]-
arene ring could weaken the spin coupling. Therefore, the
resultant structure could be approximated as a trimer of S1)
1/2, S2 ) S3 ) 3. For such symmetric trimer, the Heisenberg
hamiltonian, -2J(S1S2 + S1S3), is analytically solvable;25,26
elucidation of eigenvalues reveals that the energy difference
between the S ) 13/2 ground state and S ) 11/2 lowest excited
Figure 9. SQUID magnetometry (H ) 0-5.0 T) for polyradical 1 in
THF-d8/2-MeTHF, following exposure to ambient temperature. (The
initial value of S is 6.2, see Figure 6.) The lines correspond to the
Brillouin functions with S ) 7, 5/2, and 1. After 0.5 h at ambient
temperature, the M/Msat vs H/(T - θ), θ ) -0.20 K, plot corresponds
to the experimental points at T ) 1.8, 3, and 5 K. The fitting parameters
at T ) 1.8, 3, and 5 K are S ) 2.56, 2.54, and 2.59 and Msat × 103 )
2.62, 2.62, and 2.61 emu; the parameter dependence is 0.41, 0.62, and
0.84. After 24 h at ambient temperature, the M/Msat vs H/(T - θ), θ )
0 K, plot corresponds to the experimental points at T ) 1.8, 3, and 5
K. The fitting parameters at T ) 1.8, 3, and 5 K are S ) 1.04, 1.14,
and 1.13 and Msat × 103 ) 1.13, 1.11, and 1.12 emu; the parameter
dependence is 0.52, 0.80, and 0.96.
state is only J. For 1 in THF-d8, the MT vs T data are fit to the
trimer model with J/k ≈ 70 K.27,28 This J/k should be scaled
by a factor of 2 to obtain J′/k across “twisted” 1,3-phenylene
moieties in the center calix[4]arene ring, i.e., J′/k ≈ 140 K.29
The small but significant value |θ|, (θ < 0) of the mean-
field correction, especially for more concentrated 1 in THF-d8/
2-MeTHF, suggests small antiferromagnetic interactions for
(27) Adequate fit to the trimer model requires introduction of a third
variable parameter, Mdia, (J and number of moles, N, are the other two
parameters) to account for a small error (ca. 1%) of point-by-point correction
for diamagnetism. Standard errors and parameter dependencies for variable
parameters are as follows: 3% and 0.97 (J), 0.1% and 0.51 (N), 5% and
0.97 (Mdia).
(28) Consideration of simple Boltzman factors shows that population of
the excited states in the 1.8-5 K range is negligible for the model trimer
with J/k ) 70 K. More rigorously, when M(H, T) is calculated for the model
trimer, excellent fits to Brillouin function at T ) 1.8, 3, and 5 K, with two
variable S and Msat, are obtained; i.e., S ) 6.500 in the 1.8-5 K range, as
expected for the ground state of the model trimer.
(25) Heisenberg, W. Z. Phys. 1926, 38, 441. Dirac, P. A. M. Proc. R.
Soc. 1926, 112A, 661.
(26) Belorizky, E.; Fries, P. H. J. Chim. Phys. (Paris) 1993, 90, 1077.
(29) Itoh, K. Pure Appl. Chem. 1978, 50, 1251. Jacobs, S. J.; Schultz,
D. A.; Jain, R.; Novak, J.; Dougherty, D. A. J. Am. Chem. Soc. 1993, 115,
1744.

High-Spin Polyarylmethyl Polyradical
J. Am. Chem. Soc., Vol. 119, No. 43, 1997 10341
with water and the solution was extracted with ether, the ether layer
was washed with water and brine and then dried over MgSO4.
Concentration in vacuo gave a brown solid (19.43 g). Recrystallization
from hexane gave 13.86 g (81%) of light yellow crystals. From three
reactions on the 18 g scale, 41.15 g (81%) of alcohol 2 was obtained
polyradicals in frozen solution. Determination of whether these
antiferromagnetic interactions are intra- or intermolecular by
dilution studies is hampered by the lack of sufficient amount
of tetradecaether precursors for polyradical.
Interestingly, when 0.001 M 1 in THF-d8/2-MeTHF is
measured after exposures to ambient temperature for 30 min
and 24 h, the M vs H data approximately follow Brillouin
functions and indicate decrease of S from the original value of
6.2 to ∼2.5 and ∼1, respectively (Figure 9). Also, Msat × 103,
which is linearly related to the number of “unpaired” electrons
in the sample, decreases from 6.0 to 2.6 and 1.1 emu,
respectively. However, Msat/S, which is linearly related to
number of moles of spin systems with an “average” S, is
approximately constant for the samples with S ) 6.2, ∼2.5,
and ∼1. Suprisingly, thermal decomposition of 1 does not
interrupt ferromagnetic coupling between the remaining “un-
paired” electrons; i.e., the “unpaired” electrons belong to a single
ferromagnetically coupled spin system.
1
from 15.52 g of methyl 4-tert-butylbenzoate; mp 146 °C; H NMR
(CDCl3) 7.615 (t, J ) 2, 2 H), 7.431 (d, J ) 2, 4 H), 7.382 (d, J ) 8.5,
2 H), 7.069 (d, J ) 8.5, 2 H), 2.678 (s, 1 H), 1.332 (s, 9 H); 13C{1H}-
DEPT(135°) NMR (CDCl3) 151.7, 149.5, 141.5, 133.4, 129.5, 127.4,
125.7, 122.9, 80.5, 34.6, 31.2; CH, CH3 133.4, 129.5, 127.4, 125.7,
31.2.
Ether 3. Sodium hydride (4.16 g of 60% dispersion in mineral oil,
0.104 mol) was washed with pentane under nitrogen flow followed by
addition of THF (215 mL). The resultant suspension was cooled to 0
°C. A solution of alcohol 2 (13.14 g, 20.79 mmol) in THF was added
to the suspension, followed, after 1 h, by iodomethane (20.8 mL, 0.333
mol). The reaction mixture was allowed to warm to ambient temper-
ature and followed with TLC until the starting material was not
detectable. After extraction with ether, the combined organic layer
was washed with water and brine and then dried over MgSO4.
Concentration in vacuo gave a light yellow solid, which was recrystal-
lized from MeOH/ether to give two crops of colorless crystals (12.41
g, 92%) of ether 3. From three reactions on the 13 g scale, 37.67 g
(90%) of ether 3 was obtained from 40.90 g of alcohol 2: mp 180 °C;
1H NMR (CDCl3) 7.565 (t, J ) 2, 2 H), 7.516 (d, J ) 2, 4 H), 7.378
(d, J ) 8.5, 2 H), 7.177 (d, J ) 8.5, 2 H), 3.007 (s, 3 H), 1.337 (s, 9
H); 13C{1H}DEPT(135°) NMR (CDCl3) 151.3, 147.9, 136.6, 133.1,
129.9, 129.1, 125.3, 122.7, 85.5, 52.2, 34.6, 31.3; CH, CH3 133.1, 129.8,
129.1, 125.3, 52.2, 31.3. Anal. Calcd for C24H22OBr4: C, 44.62; H,
3.43. Found: C, 44.54; H, 3.77.
Conclusion
A trimeric fragment of 2-strand, based on calix[4]arene
macrocycles, provides polyradical with high-spin ground state.
The measured value of spin, S ) 6.2, is below the theoretical
value of 7. Quenching studies suggest presence of defects; i.e.,
not all 14 but only 12 or 13 “unpaired” electrons are generated
in polyradical 1. Furthermore, ferromagnetic coupling between
these “unpaired” electrons is relatively weak, compared to that
of typical 1,3-phenylene-based polyarylmethyls, presumably,
because of out-of-plane distortion of the π-conjugated system.
Two- or three-dimensional net will require careful design to
accommodate π-conjugation, connectivity compatible with
ferromagnetic coupling, adequate steric hindrance to stabilize
radical sites, and efficient synthetic methodology.
Diketone 4. t-BuLi (26.3 mL of a 1.5 M solution in pentane, 39.5
mmol) was added to ether 3 (6.380 g, 9.876 mmol) in THF (200 mL)
at -78 °C over a period of 20 min. After 3 h, 1-(4-tert-butylbenzoyl)-
pyrrolidine (5.018 g, 21.72 mmol) in THF (100 mL) was quickly added
to the reaction mixture. The reaction mixture was allowed to warm to
ambient temperature overnight. After the reaction was quenched with
water and the solution was extracted with ether, the combined organic
layer was washed with water and brine and then dried over MgSO4.
Concentration in vacuo gave a light yellow solid (9.085 g). Column
chromatography (silica gel, 230-400 mesh, 5% ether in hexane)
produced 7.290 g (91%) of colorless solid of diketone 4, which was of
sufficient purity for the next step in the synthesis. From four reactions
on the 3, 4, and 6 g scales, 21.71 g (85%) of diketone 4 was obtained
from 20.42 g of ether 3. A sample for elemental analysis was obtained
by additional treatment with MeOH (to remove residual hexanes): mp
128-130 °C; FAB MS (ONPOE), m/z (% RA for m/z 300-810) at
(M + H)+ 807.1 (50), 808.1 (30), 809.1 (100), 810.1 (50), 811.1 (60),
812.1 (20) at (M - OCH3)+ 775.1 (25), 776.1 (15), 777.1 (50), 778.1
(30), 779.1 (30), 780.1 (15); calcd. for C46H49O3Br2 at (M + H)+ 807.2
Experimental Section
Materials and Special Procedures. Ether and tetrahydrofuran
(THF) for use on vacuum line were distilled from sodium/benzophenone
in a nitrogen atmosphere. Iodine (99.999%, resublimed crystals,
ultradry) was obtained from Johnson-Mathey. THF-d8 (99.95% D),
which was obtained from Cambridge Isotope Labs, was doubly vacuum
transferred from sodium/benzophenone prior to the use. t-BuLi was
obtained from either Aldrich (1.7 M in pentane) or Across (1.5 M in
pentane). Other major chemicals, including MeOD (99.5+% D), were
obtained from Aldrich. Synthesis of dibromotriether 5 was previously
described.8 Vacuum lines (10-3 Torr) were used for all air-sensitive
synthetic procedures.20
1
(50), 808.2 (30), 809.2 (100), 810.2 (50), 811.2 (60), 812.2 (30); H
NMR (CDCl3) 7.904 (t, J ) 2, 2 H), 7.826 (t, J ) 2, 2 H), 7.715 (t, J
) 2, 2 H), 7.666 (d, J ) 8.5, 4 H), 7.456 (d, J ) 8.9, 4 H), 7.367 (d,
J ) 8.5, 4 H), 7.248 (d, J ) 8.5, 4 H), 3.046 (s, 3 H), 1.333 (s, 18 H),
1.332 (s, 9 H); 13C{1H}DEPT(135°) NMR (CDCl3) 194.3, 156.9, 151.2,
146.6, 139.5, 137.2, 134.1, 133.8, 131.5, 130.2, 129.0, 128.4, 125.5,
125.3, 122.6, 86.0, 52.2, 35.1, 34.5, 31.3, 31.1. CH, CH3: 134.1, 131.6,
130.2, 129.0, 128.3, 125.5, 125.3, 52.2, 31.3, 31.0. Anal. Calcd for
C46H48O3Br2: C, 68.32; H, 5.98. Found: C, 68.29; H, 6.17.
Calix[4]arene Diols 6. t-BuLi (5.90 mL of 1.7 M solution in
pentane, 10.0 mmol) was added to a solution of dibromo triether 5
(2.764 g in 250 mL of THF, 2.50 mmol) at -78 °C. After 1 h, a
solution of diketone 4 (2.022 g in 100 mL of THF, 2.50 mmol) was
cannulated to the reaction mixture. The reaction mixture was allowed
to warm to ambient temperature overnight. After the reaction was
quenched with water (25 mL) and the solution was extracted with ether,
the combined organic layer was washed with water and brine and then
dried over MgSO4; concentration in vacuo gave a yellow solid. Column
chromatography (TLC grade silica gel, hexane/ether, 6 to 9%) produced
three isomers (in the order of increasing polarity on silica gel) 6A, 6B,
and 6C, which were of sufficient purity for the next step in the synthesis.
For example, from eight reactions on the 1 and 2 g scales, 1.941 g of
6A (7%), 3.250 g of 6B (11%), and 2.021 g of 6C (7%) were obtained
NMR Spectroscopy and Other Analyses. NMR spectra were
obtained with Omega spectrometers (1H, 300 and 500 MHz) in CDCl3,
benzene-d6, and acetone-d6; the chemical shift references were 1H (TMS,
0.0 ppm; benzene-d6, 7.15 ppm; acetone-d6, 2.04 ppm) and 13C (CDCl3,
77.0 ppm). Coupling constants (J) are given in hertz. Unless indicated
otherwise, exponential multiplications (EM) of 0.1 and 1.0 Hz, prior
to Fourier transform, were used for 1H and 13C NMR spectra,
respectively. For those selected 1H and 13C NMR spectra, where
spectral resolution was enhanced by combination of exponential
multiplication and Gaussian broadening (GB), prior to Fourier trans-
form, parameters EM and GB are shown with the spectral data. 2H
NMR spectrum for 1-(D)14 (and attempted spectrum for 1-(H)13(D)1)
in acetone was obtained without lock (40 000 scans, 0.13 s acquisition
time). IR spectra were obtained as previously described.14
Elemental analyses were completed by M-H-W Laboratories, P.O.
Box 15149, Phoenix, AZ 85060.
Alcohol 2. n-BuLi (24.0 mL of a 2.5 M solution in hexanes, 60.0
mmol) was added dropwise to 1,3,5-tribromobenzene (18.89 g, 60.0
mmol) in ether (500 mL) at -78 °C. After 2 h, methyl 4-tert-
butylbenzoate (5.174 g, 26.92 mmol) in ether (20 mL) was added to
the above reaction mixture. The reaction mixture was allowed to warm
to ambient temperature overnight. After the reaction was quenched

10342 J. Am. Chem. Soc., Vol. 119, No. 43, 1997
Rajca et al.
from 17.956 g of dibromo triether 5. In selected runs, a small amount
of the forth isomer 6D was isolated.
(q), 34.40 (q), 34.38 (q), 34.36 (q), 31.40, 31.37, 31.33; IR (cm-1) 3500
(O-H), 1599 (Ar).
For 6D: FAB MS (3-NBA) m/z (% RA for m/z 400-2300) at (M
- OCH3)+ 1721.9 (45), 1722.9 (55), 1723.9 (100), 1724.9 (95), 1725.9
(85), 1726.9 (60), 1727.9 (30), 1728.9 (10); at (M - OH)+ 1736.0
(15), 1737.0 (20), 1738.0 (40), 1739.0 (35), 1740.0 (35), 1741.0 (20),
For 6A: FAB MS (ONPOE), m/z (% RA for m/z 400-2000) at (M
- OCH3)+ 1721.8 (50), 1722.8 (60), 1723.8 (100), 1724.8 (95), 1725.8
(85), 1726.8 (65), 1727.8 (35) at (M - OH)+ 1735.7 (20), 1736.7 (25),
1737.7 (45), 1738.7 (45), 1739.7 (40), 1740.7 (30), 1741.7 (15); calcd
for C113H127O5Br2 at (M - OCH3)+ 1721.8 (35), 1722.8 (45), 1723.8
(100), 1724.8 (100), 1725.8 (95), 1726.8 (70), 1727.8 (35), 1728.8 (15);
1H NMR (500 MHz, EM ) -1.9, GB ) +0.9, CDCl3) 7.534 (t, J )
2, 1 H), 7.492 (t, J ) 2, 1 H), 7.439-7.421 (m, 4 H), 7.360 (t, J ) 2,
1 H), 7.273 (t, J ) 2, 1 H), 7.258-7.256 (m, 4 H), 7.240-7.054 (m,
22 H), 7.015 (d, J ) 9, 2 H), 6.912-6.895 (m, 3 H), 6.805 (d, J ) 9,
2 H), 6.769 (t, J ) 2, 1 H), 6.635 (t, J ) 2, 1 H), 6.337 (t, J ) 2, 1 H),
2.859 (s, 3 H), 2.722 (s, 3 H), 2.764 (s, 3 H), 2.745 (s, 2 H), 2.721 (s,
3 H), 1.311 (s, 9 H), 1.301 (s, 9 H), 1.290 (s, 9 H), 1.271 (s, 9 H),
1.263 (s, 27 H), 1.238 (s, 9 H); 13C{1H}DEPT(135°) NMR (125 MHz,
EM ) -1.1, GB ) + 0.9, CDCl3) aromatic quaternary region expected
28 resonances, found 27 resonances at 150.5 (q), 150.2 (q), 150.1 (q),
149.7 (q), 149.40 (q), 149.36 (q), 149.32 (q), 149.0 (q), 148.7 (q), 146.1
(q), 145.6 (q), 145.3 (q), 144.8 (q), 144.4 (q), 143.8 (q), 143.31 (q),
143.27 (q), 143.24 (q), 142.9 (q), 141.10 (q), 141.04 (q), 140.98 (q),
140.87 (q), 139.0 (q), 138.3 (q), 122.0 (q), 121.8 (q); aromatic
nonquaternary region expected 28 resonances, found 28 resonances at
129.7, 129.4, 129.3, 129.0, 128.8, 128.7, 128.41, 128.40, 128.34, 128.25,
127.9, 127.8, 127.60, 127.55, 127.44, 127.37, 127.1, 126.0, 125.8, 125.6,
124.8, 124.7, 124.6, 124.5, 124.41, 124.36, 124.34, 124.32; aliphatic
region 87.1 (q), 86.9 (q), 86.7 (q), 86.2 (q), 81.8 (q), 81.4 (q), 52.1,
52.0, 51.96, 51.9, 34.46 (q), 34.43 (q), 34.41 (q), 34.37 (q), 34.35(q),
31.38, 31.37, 31.34, 31.32; IR (cm-1) 3500 (O-H), 1596 (Ar).
1
1742.0 (10); H NMR (500 MHz, EM ) -1.1, GB ) + 0.5, CDCl3)
7.467 (t, J ) 2, 2 H), 7.447 (t, J ) 2, 2 H), 7.372 (t, J ) 2, 2 H), 7.355
(t, J ) 2, 2 H), 7.318 (d, J ) 9, 4 H), 7.24-7.07 (m, 20 H), 7.016 (d,
J ) 9, 2 H), 6.872 (d, J ) 9, 2 H), 6.858 (d, J ) 9, 4 H), 6.705 (t, J
) 2, 2 H), 6.477 (t, J ) 2, 2 H), 6.706 (bs, 2 H), 6.477 (bs, 2 H),
2.898 (s, 3 H), 2.808 (s, 6 H), 2.746 (s, 2 H, exchangeable D2O), 2.712
(s, 3 H), 1.370 (s, 18 H), 1.310 (s, 9 H), 1.275 (s, 18 H), 1.270 (s, 18
H), 1.267 (s, 9 H); IR (cm-1) 3500 (O-H), 1567 (Ar).
Calix[4]arene Hexaethers 7. Sodium hydride (0.42 g of 60%
dispersion in mineral oil, 10.6 mmol) was washed with pentane under
nitrogen flow followed by addition of THF (40 mL). The resultant
suspension was cooled to 0 °C. A solution of 6A (1.857 g in 30 mL
of THF, 1.060 mmol) was added to the suspension. After 15 min,
iodomethane (4.51 g, 3.29 mmol) was added to the reaction mixture.
The reaction mixture was allowed to warm to ambient temperature
slowly. After the mixture was extracted with ether, the combined
organic layer was washed with water and brine and then dried over
MgSO4; concentration in vacuo gave a yellow solid. An analogous
procedure was used to convert isomers 6B and 6C to the corresponding
hexaethers 7B and 7C.
7A. From 6A (1.857 g), 1.652 g of crude 7A was obtained. Column
chromatography (TLC grade silica gel, hexane/ether, 96:4) gave a pale
yellow solid, 1.200 g. Crystallization/precipitation from methanol/ether
gave a white powder, 0.782 g (41 %), with mp ) 196-197 °C. For
7A: FAB MS (3-NBA) m/z (% RA for m/z 400-1900) at (M-OCH3)+
1748.8 (15), 1749.8 (50), 1750.8 (60), 1751.8 (100), 1752.8 (100),
1753.8 (85), 1754.8 (65), 1755.8 (30), 1756.8 (15); calcd for C115H131O5-
Br2 at (M-OCH3)+ 1749.8 (35), 1750.8 (45), 1751.8 (95), 1752.8 (100),
1753.8 (95), 1754.8 (70), 1755.8 (40), 1756.8 (15); 1H NMR (500 MHz,
EM ) -1.2, GB ) +0.7, CDCl3, 1H-1H COSY cross-peak) 7.582 (t,
J ) 2, 1 H, 7.276, 6.776), 7.513 (t, J ) 2, 1 H, 7.344, 7.049), 7.389
(t, J ) 2, 1 H, 7.357, 7.115), 7.357 (t, J ) 2, 1 H, 7.389, 7.115), 7.344
(t, J ) 2, 1 H, 7.513, 7.049), 7.292 (t, J ) 2, 1 H, 7.152, 7.108), 7.284
(d, J ) 9, 2 H, 7.158), 7.269 (t, J ) 2, 1 H, 7.582, 6.776), 7.220 (d,
J ) 9, 4 H, 7.161), 7.220 (d, J ) 9, 2 H, 7.124), 7.213 (d, J ) 9, 2 H,
7.017), 7.200 (d, J ) 9, 2 H, 7.051), 7.191 (d, J ) 9, 2 H, 7.120),
7.161 (d, J ) 9, 4 H, 7.220), 7.161 (d, J ) 9, 2 H, 6.944),7.158 (d, J
) 9, 2 H, 7.284), 7.152 (t, J ) 2, 1 H, 7.292 (overlapped), 7.108),
7.124 (d, J ) 9, 2 H, 7.220), 7.120 (d, J ) 9, 2 H, 7.191), 7.115 (t, J
) 2, 1 H, 7.389, 7.357), 7.051 (d, J ) 9, 2 H, 7.200), 7.049 (t, J ) 2,
1 H, 7.513, 7.344), 7.017 (d, J ) 9, 2 H, 7.213), 7.018 (t, J ) 2, 1 H,
7.152, 7.292), 6.944 (d, J ) 9, 2 H, 7.161), 6.776 (t, J ) 2, 1 H, 7.582,
7.276), 2.910 (s, 3 H), 2.849 (s, 3 H), 2.844 (s, 3 H), 2.788 (s, 3 H),
2.648 (s, 3 H), 2.619 (s, 3 H), 1.311 (s, 9 H), 1.284 (s, 18 H), 1.282 (s,
9 H), 1.278 (s, 9 H), 1.269 (s, 9 H), 1.267 (s, 18 H); 13C{1H}-
DEPT(135°) NMR (125 MHz, EM ) -1.0, GB ) +2.0, CDCl3)
aromatic quaternary region expected 28 resonances, found 26 resonances
at 150.12 (q), 149.96 (q), 149.91 (q), 149.40 (q), 149.35 (q), 149.28
(q),148.3 (q), 147.8 (q), 146.0 (q), 145.0 (q), 143.4 (q), 143.3 (q), 142.8
(q), 142.0 (q), 141.5 (q), 141.4 (q), 141.3 (q), 141.2 (q), 141.1 (q),
140.8 (q), 140.6 (q), 139.3 (q), 139.0 (q), 138.8 (q), 121.5 (q), 121.4
(q); aromatic nonquaternary region expected 28 resonances, found 23
resonances at 130.0, 129.6, 129.5, 129.2, 129.1, 129.0, 128.9, 128.8,
128.47, 128.44, 128.35, 128.32, 128.26, 128.1, 127.6, 127.5, 127.3,
126.4, 124.8, 124.6, 124.5, 124.4, 124.3; aliphatic region 87.3 (q), 86.9
(q), 86.8 (q), 86.62 (q), 86.59 (q), 86.47 (q), 52.4, 52.3, 51.99, 51.95,
51.91, 34.46 (q), 34.37 (q), 34.34 (q), 31.39, 31.34; IR (cm-1) 1598
(Ar). Anal. Calcd for C116H134O6Br2: C, 78.09; H, 7.57. Found: C,
78.13; H, 7.65.
For 6B: FAB MS (ONPOE), m/z (% RA for m/z 400-1800) at (M
- OCH3)+ 1720.9 (10), 1721.9 (45), 1723.0 (55), 1724.0 (100), 1725.0
(90), 1726.0 (85), 1727.0 (60), 1728.0 (30); at (M - OH)+ 1736.0
(20), 1737.0 (25), 1737.9 (40), 1738.9 (40), 1739.9 (35), 1741.0 (25),
1
1742.0 (10); H NMR (500 MHz, EM ) -1.9, GB ) +0.9, CDCl3)
7.482-7.472 (m, 2 H), 7.461 (t, J ) 2, 1 H), 7.442 (t, J ) 2, 1H),
7.420 (t, J ) 2, 1 H), 7.300 (t, J ) 2, 1 H), 7.246-6.968 (m, 33 H),
6.868 (t, J ) 2, 2 H), 6.829 (t, J ) 2, 1 H), 6.635 (t, J ) 2, 1 H), 2.849
(s, 3 H), 2.823 (s, 3 H), 2.770 (s, 3 H), 2.684 (s, 3 H), 2.608 (s, 1 H),
2.585 (s, 1 H), 1.288 (s, 9 H), 1.282 (s, 9 H), 1.280 (s, 9 H), 1.272 (s,
18 H), 1.270 (s, 9 H), 1.266 (s, 9 H), 1.260 (s, 9 H); 13C{1H}-
DEPT(135°) NMR (125 MHz, EM ) -1.2, GB ) +2.0, CDCl3)
aromatic quaternary region expected 28 resonances, found 27 resonances
at 150.3 (q), 150.2 (q), 150.0 (q), 149.52 (q), 149.46 (q), 149.43 (q),
149.34 (q), 149.30 (q), 148.81 (q), 148.78 (q), 145.32 (q), 145.21 (q),
145.16 (q), 145.10 (q), 143.7 (q), 143.6 (q), 143.24 (q), 143.21 (q),
142.9 (q), 142.7 (q), 141.4 (q), 141.3 (q), 140.6 (q), 140.1 (q), 138.9
(q), 122.0 (q), 121.8 (q); aromatic nonquaternary region expected 28
resonances, found 24 resonances at 130.0, 129.6, 129.2, 128.9, 128.64,
128.59, 128.48, 128.14, 128.11, 128.06, 127.9, 127.8, 127.48, 127.44,
127.39, 126.72, 126.66, 125.0, 124.73, 124.64, 124.56, 124.47, 124.39,
124.36; aliphatic region 87.0 (q), 86.8 (q), 86.7 (q), 86.2 (q), 81.63
(q), 81.60 (q), 52.2, 52.1, 52.0, 34.4 (q), 34.47 (q), 34.34 (q), 31.42,
31.37; IR (cm-1) 3500 (O-H), 1598 (Ar).
For 6C: FAB MS (3-NBA) m/z (% RA for m/z 400-2000) at (M
- OCH3)+ 1721.8 (50), 1722.8 (60), 1723.8 (100), 1724.8 (95), 1725.8
(85), 1726.8 (60), 1727.8 (30), 1728.8 (10); at (M - OH)+ 1735.8
(20), 1736.8 (25), 1737.8 (40), 1738.8 (40), 1739.8 (35), 1740.8 (25),
1741.8 (15). 1H NMR (500 MHz, EM ) -1.9, GB ) +0.9, CDCl3):
7.473 (t, J ) 2, 2 H), 7.465 (t, J ) 2, 2 H), 7.421 (t, J ) 2, 2 H), 7.318
(d, J ) 9, 4 H), 7.272 (t, J ) 2, 2 H), 7.230 - 7.212 (m, 8 H), 7.088
(d, J ) 9, 2 H), 7.001 (d, J ) 9, 4 H), 6.944 (d, J ) 9, 4 H), 6.867 (d,
J ) 9, 2 H), 6.732 (t, J ) 2, 2 H), 6.456 (t, J ) 2, 2 H), 2.819 (s, 6
H), 2.797 (s, 2 H, exch. D2O), 2.751 (s, 3 H), 2.589 (s, 3 H), 1.328
(s, 18 H), 1.300 (s, 9 H), 1.287 (s, 18 H), 1.274 (s, 9 H), 1.270 (s, 18
H); 13C{1H}DEPT(135°) NMR (125 MHz, EM ) -1.1, GB ) +0.9,
CDCl3) aromatic quaternary region expected 16 resonances, found 15
resonances at 150.4 (q), 149.8 (q), 149.5 (q), 149.4 (q), 148.7 (q), 145.1
(q), 145.0 (q), 143.9 (q), 143.4 (q), 142.6 (q), 141.2 (q), 140.8 (q),
140.5 (q), 139.7 (q), 122.0 (q); aromatic nonquaternary region expected
16 resonance, found 14 resonances at 130.1, 129.8, 128.5, 128.4, 128.3,
127.9, 127.7, 127.5, 127.46, 127.4, 126.2, 124.8, 124.5, 124.4; aliphatic
region 87.1 (q), 86.7 (q), 86.2 (q), 81.9 (q), 52.05, 51.97, 51.94, 34.49
7B. From 6B (2.969 g), 2.679 g of crude 7B was obtained. Column
chromatography (TLC grade silica gel, hexane/ether, 96.5:3.5) gave a
colorless solid, 1.602 g. A sample of 1.35 g was repurified by column
chromatography and precipitation from methanol/ether to give a white
powder, 0.8028 g (27%), with mp ) 192-194 °C; FAB MS (3-NBA)
m/z (% RA for m/z 400-2000) at (M-OCH3)+ 1748.2 (10), 1749.2
(15), 1750.2 (50), 1751.2 (55), 1752.2 (100), 1753.2 (90), 1754.2 (85),

High-Spin Polyarylmethyl Polyradical
J. Am. Chem. Soc., Vol. 119, No. 43, 1997 10343
1
1755.2 (60), 1756.2 (30), 1757.2 (15); H NMR (500 MHz, EM )
hexane/ether, 90:10) gave a light yellow solid, which was of sufficient
purity for the next step in the synthesis. From two reactions on the
0.2 and 0.3 g scales, 0.295 g (54%) of calix[4]arene diketone 8 was
obtained from 0.500 g of 7B. For 8: FAB MS (3-NBA) m/z (% RA
for m/z 400-2300) at (M - OCH3)+ 1912.6 (15), 1913.6 (20), 1914.6
-0.6, GB ) +0.5, CDCl3, 1H-1H COSY cross-peak) 7.556 (t, J ) 2,
1 H, 7.294, 6.815), 7.474 (t, J ) 2, 1 H, 7.341, 7.118), 7.414 (t, J )
2, 1 H, 7.354, 7.170), 7.354 (t, J ) 2, 1 H, 7.414, 7.170), 7.341 (t, J
) 2, 1 H, 7.474, 7.118), 7.294 (t, J ) 2, 1 H, 7.556, 6.815), 7.269 (d,
J ) 9, 2 H, 7.198), 7.238 (t, J ) 2, 1 H, 7.134, 7.091), 7.231 (s,
collapsed AB system, 4 H), 7.229 (d, J ) 9, 2 H, 7.182), 7.209 (d, J
) 9, 2 H, 7.012), 7.202 (d, J ) 9, 2 H, 7.101), 7.202 (d, J ) 9, 2 H,
7.091), 7.198 (d, J ) 9, 2 H, 7.269), 7.198 (d, J ) 9, 2 H, 7.016),
7.189 (d, J ) 9, 2 H, 7.094), 7.182 (d, J ) 9, 2 H, 7.091), 7.170 (t, J
) 2, 1 H, 7.414, 7.354), 7.134 (t, J ) 2, 1 H, 7.238, 7.091), 7.118 (t,
J ) 2, 1 H, 7.474, 7.341), 7.101 (d, J ) 9, 2 H, 7.202), 7.094 (d, J )
9, 2 H, 7.189), 7.091 (d, J ) 9, 2 H, 7.202), 7.091 (t, J ) 2, 1 H,
7.238,7.134), 7.016 (d, J ) 9, 2 H, 7.198), 7.012 (d, J ) 9, 2 H, 7.209),
6.815 (t, J ) 2, 1 H, 7.556, 7.294), 2.905 (s, 3 H), 2.855 (s, 3 H),
2.821 (s, 3 H), 2.756 (s, 3 H), 2.729 (s, 3 H), 2.667 (s, 3 H), 1.286 (s,
18 H), 1.284 (s, 9 H), 1.282 (s, 9 H), 1.276 (s, 9 H), 1.275 (s, 9 H),
1.270 (s, 18 H); 13C{1H}DEPT(135°) NMR (125 MHz, EM ) -1.1,
GB ) +0.5, CDCl3) aromatic quaternary region expected 28 reso-
nances, found 25 resonances at 150.0 (q), 149.9 (q), 149.8 (q), 149.44
(q), 149.37 (q), 149.26 (q), 149.23 (q), 148.3 (q), 148.2 (q), 145.9 (q),
144.5 (q), 143.7 (q), 142.7 (q), 142.6 (q), 141.9 (q), 141.37 (q), 141.33
(q), 141.2 (q), 140.94 (q), 140.90 (q), 140.6 (q), 139.25 (q), 139.20
(q), 139.15 (q), 121.4 (q); aromatic nonquaternary region expected 28
resonances found 25 resonances at 130.4, 129.8, 129.5, 129.2, 129.1,
128.80, 128.76, 128.50, 128.46, 128.30, 128.22, 128.10, 128.05, 127.9,
127.7, 127.3, 125.7, 124.9, 124.6, 124.5, 124.43, 124.41, 124.38, 124.36,
124.33; aliphatic region 87.1 (q), 86.9 (q), 86.8 (q), 86.6 (q), 86.3 (q),
52.3, 52.2, 52.0, 51.97, 51.96, 51.94, 34.43 (q), 34.39 (q), 34.37 (q),
34.35 (q), 34.34 (q), 31.37, 31.34, 31.32; IR (cm-1) 1598 (Ar). Anal.
Calcd for C116H134O6Br2: C, 78.09; H, 7.57. Found: C, 78.12; H, 7.64.
1
(75), 1915.6 (100), 1916.6 (75), 1917.6 (40), 1918.6 (15); H NMR
(500 MHz, EM ) -1.85, GB ) 1.20, C6D6, 1H-1H COSY cross-
peak) 8.519 (t, J ) 2, 1 H, 8.028, 7.986), 8.393 (t, J ) 2, 1 H, 8.188,
8.154), 8.188 (t, J ) 2, 1 H, 8.393, 8.154), 8.154 (t, J ) 2, 1 H, 8.393,
8.188), 8.121 (t, J ) 2, 1 H, 7.871, 7.502), 8.028 (bs, 1 H, 8.519,
7.986), 7.986 (t, J ) 2, 1 H, 8.519, 8.028), 7.871 (t, J ) 2, 1 H, 8.121,
7.502), 7.799 (t, J ) 2, 1 H, 7.792, 7.702), 7.792 (t, J ) 2, 1 H, 7.799,
7.702), 7.747 (d, J ) 9, 2 H, 7.182), 7.702 (t, J ) 2, 1 H, 7.799, 7.792),
7.694 (d, J ) 9, 2 H, 7.135), 7.540 (d, J ) 9, 2 H, 7.204), 7.507 (d, J
) 9, 2 H, 7.248), 7.502 (t, J ) 2, 1 H, 8.121, 7.871), 7.496 (d, J ) 9,
2 H, 7.233), 7.475 (d, J ) 9, 2 H, 7.281), 7.461 (d, J ) 9, 2 H, 7.152),
7.438 (d, J ) 9, 2 H, 7.146), 7.433 (d, J ) 9, 2 H, 7.233), 7.384 (d, J
) 9, 2 H, 7.186), 7.281 (d, J ) 9, 2 H, 7.475), 7.248 (d, J ) 9, 2 H,
7.507), 7.233 (d, J ) 9, 2 H, 7.433), 7.224 (d, J ) 9, 2 H, 7.496),
7.204 (d, J ) 9, 2 H, 7.540), 7.186 (d, J ) 9, 2 H, 7.384), 7.182 (d, J
) 9, 2 H, 7.747), 7.152 (d, J ) 9, 2 H, 7.475), 7.146 (d, J ) 9, 2 H,
7.438), 7.135 (d, J ) 9, 2 H, 7.694), 3.019 (s, 3 H), 3.000 (s, 3 H),
2.958 (s, 3 H), 2.931 (s, 3 H), 2.908 (s, 3 H), 2.849 (s, 3 H), 1.210 (s,
9 H), 1.203 (s, 9 H), 1.190 (s, 9 H), 1.183 (s, 9 H), 1.177 (s, 9 H),
1.174 (s, 9 H), 1.160 (s, 9 H), 1.142 (s, 9 H), 1.129 (s, 9 H), 1.118 (s,
9 H); 13C{1H}DEPT(135°) NMR (125 MHz, EM ) -1.10, GB ) 0.90,
CDCl3) carbonyl group region expected 2 resonances, found 2
resonances at 195.70 (q), 195.66 (q); aromatic quaternary region
expected 32 resonances found 31 resonances at 156.09 (q), 156.07 (q),
149.87 (q), 149.84 (q), 149.7 (q), 149.4 (q), 149.3 (q), 149.22 (q), 149.18
(q), 146.36 (q), 146.32 (q), 143.9 (q), 143.6 (q), 143.5 (q), 143.1 (q),
142.6 (q), 141.8 (q), 141.6 (q), 141.41 (q), 141.37 (q), 141.29 (q), 141.24
(q), 140.9 (q), 140.5 (q), 139.6 (q), 139.42 (q), 139.37 (q), 137.1 (q),
136.8 (q), 134.58 (q), 134.50 (q); aromatic nonquaternary region
expected 32 resonances, found 25 resonances at 132.3, 130.6, 130.4,
130.3, 129.7, 129.25, 129.19, 128.8, 128.6, 128.53, 128.46, 128.42,
128.35, 128.2, 128.1, 125.15, 125.09, 124.8, 124.57, 124.55, 124.39,
124.36, 124.35, 124.33, 124.28; aliphatic region 87.2 (q), 86.93 (q),
86.91 (q), 86.80 (q), 86.77 (q), 52.5, 52.22, 52.11, 52.09, 52.00, 51.91,
35.02 (q), 35.00 (q), 34.39 (q), 34.34 (q), 34.32 (q), 34.30 (q), 34.27
(q), 34.23 (q), 31.36, 31.34, 31.29, 31.27, 31.10, 31.09; IR (cm-1) 1662
(CdO), 1599 (Ar).
Triple-calix[4]arene Diols 9. t-BuLi (0.28 mL of 1.7 M solution
in pentane, 0.48 mmol) was added to a solution of 7B (0.209 g in 9
mL of THF, 0.12 mmol) at -78 °C. After 1 h, the reaction mixture
was warmed to -50 °C for 10 min. A solution of calix[4]arene
diketone 8 (0.229 g in 9 mL of THF, 0.12 mmol) was fast cannulated
to the above reaction mixture at -78 °C. The reaction mixture was
allowed to warm to ambient temperature. After 48 h, the reaction was
quenched with water (2 mL), and aqueous workup gave a yellow solid,
0.500 g. Column chromatography (TLC grade silica gel, hexane/ether,
∼10:1) gave three isomers 9X (following further purification by PTLC,
34.2 mg, 8%), 9Y (38.1 mg, 9%), and 9Z (38.9 mg, 9%), which were
of sufficient purity for the next step in the synthesis.
For 9X: FAB MS (3-NBA) wide-range scan, m/z (% RA for m/z
3400-4100) 3510 (35), 3525 (30), 3541 (100), 3555 (35); narrow-
range scan, m/z (% RA for m/z 3490-3560) at (M - OCH3)+ 3537.1
(15), 3538.1 (25), 3539.1 (50), 3540.1 (85), 3541.1 (100), 3542.1 (90),
3542.1 (60), 3544.1 (35), 3545.1 (20); calcd for C253H293O13 at (M -
OCH3)+ 3539.2 (25), 3540.2 (70), 3541.2 (100), 3542.2 (95), 3543.2
(70), 3544.2 (40), 3545.2 (20), 3546.3 (10); 1H NMR (CDCl3) 8.200-
6.570 (m, ArH), 2.799-1.838 (OCH3, OH), 1.331-1.139 (C(CH3)3);
IR (cm-1) 3500 (O-H), 1598 (Ar).
7C. From 6C (1.920 g), 1.824 g of crude 7C was obtained. Column
chromatography (TLC grade silica gel, hexane/ether, 98:2) followed
by crystallization/precipitation from methanol/ether gave a light yellow
powder, 0.520 g (27%). A sample of analytical purity was obtained
from another small scale reaction (from 0.105 g of 6C); column
chromatography (TLC grade silica gel, hexane/ether, 95:5) gave a
colorless solid, 0.035 g (33%), with mp ) 188-189 °C: FAB MS
(3-NBA) m/z (% RA for m/z 400-2100) at (M-OCH3)+ 1749.9 (55),
1750.9 (65), 1751.9 (100), 1752.9 (100), 1753.9 (90), 1754.9 (70),
1755.9 (40); 1H NMR (500 MHz, EM ) -1.85, GB ) +1.20, CDCl3,
1H-1H COSY cross-peak) 7.428 (t, J ) 2, 2 H, 7.252, 6.974), 7.390
(t, J ) 2, 2 H, 7.298, 7.111), 7.298 (t, J ) 2, 2 H, 7.390, 7.111), 7.290
(d, J ) 9, 2 H, 7.149), 7.252 (t, J ) 2, 2 H, 7.428, 6.974), 7.223 (d,
J ) 9, 4 H, 7.192), 7.205 (d, J ) 9, 2 H, 7.069), 7.193 (d, J ) 9, 4 H,
7.145), 7.192 (d, J ) 9, 4 H, 7.223), 7.187 (d, J ) 9, 4 H, 7.013),
7.149 (d, J ) 9, 2 H, 7.290), 7.145 (d, J ) 9, 4 H, 7.193), 7.111 (t, J
) 2, 2 H, 7.390, 7.298), 7.069 (d, J ) 9, 2 H, 7.205), 7.013 (d, J ) 9,
4 H, 7.187), 6.974 (t, J ) 2, 2 H, 7.428, 7.252), 2.927 (s, 3 H), 2.817
(s, 6 H), 2.787 (s, 6 H), 2.774 (s, 3 H), 1.327 (s, 9 H), 1.293 (s, 9 H),
1.284 (s, 36 H), 1.269 (s, 18 H); 13C{1H}DEPT(135°) NMR (125 MHz,
EM ) -1.0, GB ) +2.0, CDCl3) aromatic quaternary region expected
16 resonances, found 16 resonances at 150.0 (q), 149.8 (q), 149.5 (q),
149.3 (q), 149.2 (q), 147.4 (q), 145.5 (q), 143.0 (q), 142.5 (q), 141.42
(q), 141.33 (q), 141.26 (q), 140.4 (q), 139.6 (q), 138.4 (q), 121.5 (q);
aromatic nonquaternary region expected 16 resonances, found 16
resonances at 130.2, 130.0, 128.9, 128.54, 128.5, 128.21, 128.17,
128.13, 128.11, 127.8, 127.3, 124.9, 124.6, 124.43, 124.39, 124.33;
aliphatic region 87.2 (q), 86.9 (q), 86.6 (q), 86.4 (q), 52.4, 52.3, 52.1,
34.46 (q), 34.42 (q), 34.38 (q), 34.36 (q), 31.4; IR (cm-1) 1597 (Ar).
Anal. Calcd for C116H134O6Br2: C, 78.09; H, 7.57. Found: C, 78.35;
H, 7.73.
Calix[4]arene Diketone 8. t-BuLi (0.27 mL of a 1.7 M solution in
pentane, 0.46 mmol) was added to a solution of hexaether 7B (0.200
g in 2.5 mL of THF, 0.11 mmol) at -78 °C. After 1 h, the reaction
mixture was allowed to warm to -50 °C for 10 min by replacing the
dry ice/acetone bath with an EtOH/liquid N2 bath. After a solution of
1-(4-tert-butylbenzoyl)pyrrolidine (57.2 mg in 0.7 mL of THF, 0.25
mmol) was added to the reaction mixture at -78 °C, the reaction
temperature was raised to room temperature overnight. The reaction
was quenched with water (1 mL) followed by aqueous workup of the
resulting solution. Column chromatography (TLC grade silica gel,
For 9Y: FAB MS (3-NBA) wide-range scan, m/z (% RA for m/z
3400-4100) 3510 (35), 3525 (35), 3541 (100), 3555 (40); narrow-
range scan, m/z (% RA for m/z 3490-3575) at (M-OCH3)+ 3537.2
(20), 3538.2 (30), 3539.2 (55), 3540.2 (85), 3541.2 (100), 3542.2 (85),
1
3543.2 (65), 3544.2 (35), 3545.2 (25); H NMR (500 MHz, EM )
-2.10, GB ) 1.10, C6D6) 8.572-6.987 (m, Ar-H), 2.963 (s, 3H), 2.938
(s, 3 H), 2.910 (s, 3 H), 2.898 (s, 3 H), 2.864 (s, 3 H), 2.846 (s, 6 H),
2.779 (s, 3 H), 2.762 (s, 3 H), 2.725 (s, 3 H), 2.704 (s, 2 H,
exchangeable D2O), 2.683 (s, 3 H), 2.661 (s, 3 H), 1.314 (s, 9 H),

10344 J. Am. Chem. Soc., Vol. 119, No. 43, 1997
Rajca et al.
1.301 (s, 9 H), 1.290 (s, 9 H), 1.269 (s, 9 H), 1.235 (s, 9 H), 1.220 (s,
9 H), 1.209 (s, 18 H), 1.202 (s, 9 H), 1.198 (s, 9 H), 1.194 (s, 9 H),
1.183 (s, 9 H), 1.178 (s, 9 H), 1.175 (s, 36 H), 1.158 (s, 9 H); IR
(cm-1) 3500 (O-H), 1596 (Ar).
(t, J ) 2, 1 H, 7.799, 7.670), 7.568 (t, J ) 2, 1 H, 7.757, 7.481), 7.560
(d, J ) 9, 2 H, 7.219), 7.514 (d, J ) 9, 2 H, 7.258), 7.514 (d, J ) 9,
2 H, 7.219), 7.496 (t, J ) 2, 1 H, 7.857, 7.649), 7.481 (t, J ) 2, 7.670,
7.568), 7.477 (d, J ) 9, 2 H, 7.186), 7.475 (t, J ) 2, 1 H, 7.971, 7.568),
7.472 (d, J ) 9, 2 H, 7.258), 7.468 (t, J ) 2, 1 H, 7.900, 7.712), 7.467
(d, J ) 9, 2 H, 7.279), 7.461 (d, J ) 9, 2 H, 7.210), 7.415 (d, J ) 9,
2 H, 7.245), 7.413 (t, J ) 2, 1 H, 8.182, 7.364), 7.412 (d, J ) 9, 2 H,
7.147), 7.405 (d, J ) 9, 2 H, 7.169), 7.373 (d, J ) 9, 2 H, 7.186),
7.365 (d, J ) 9, 2 H, 7.133), 7.364 (t, J ) 2, 1 H, 8.182, 7.413), 7.360
(d, J ) 9, 2 H, 7.173), 7.329 (d, J ) 9, 2 H, 7.147), 7.311 (d, J ) 9,
2 H, 7.227), 7.279 (d, J ) 9, 2 H, 7.467), 7.271 (t, J ) 2, 1 H, 8.665,
7.629), 7.271 (d, J ) 9, 2 H, 7.791), 7.258 (d, J ) 9, 2 H, 7.514),
7.258 (d, J ) 9, 2 H, 7.472), 7.254 (t, J ) 2, 1 H, 8.272, 8.008), 7.245
(d, J ) 9, 2 H, 7.415), 7.227 (d, J ) 9, 2 H, 7.311), 7.219 (d, J ) 9,
2 H, 7.560), 7.219 (d, J ) 9, 7.514), 7.214 (s, 4 H), 7.210 (d, J ) 9,
2 H, 7.461), 7.186 (d, J ) 9, 2 H, 7.477), 7.186 (d, J ) 9, 2 H, 7.373),
7.181 (bs, 4 H), 7.173 (d, J ) 9, 2 H, 7.360), 7.169 (d, J ) 9, 2 H,
7.405), 7.147 (d, J ) 9, 2 H, 7.412), 7.147 (d, J ) 9, 2 H, 7.329),
7.133 (d, J ) 9, 2 H, 7.365), 3.199 (s, 3 H), 2.976 (s, 3 H), 2.946 (s,
3 H), 2.914 (s, 3 H), 2.912 (s, 3 H), 2.887 (s, 3 H), 2.836 (s, 3 H),
2.815 (s, 3 H), 2.779 (s, 3 H), 2.776 (s, 6 H), 2.762 (s, 3 H), 2.621 (s,
3 H), 2.604 (s, 3 H), 1.316 (s, 9 H), 1.312 (s, 9 H), 1.291 (s, 9 H),
1.288 (s, 9 H), 1.242 (s, 9 H), 1.231 (s, 9 H), 1.227 (s, 9 H), 1.221 (s,
9 H), 1.217 (s, 9 H), 1.210 (s, 9 H), 1.204 (s, 18 H), 1.192 (s, 9 H),
1.189 (s, 9 H), 1.183 (s, 18 H), 1.174 (s, 9 H), 1.161 (s, 9 H); partial
For 9Z: FAB MS (3-NBA) wide-range scan, m/z (% RA for m/z
3400-4100) 3510 (40), 3525 (40), 3541 (100), 3555 (40); narrow-
range scan, m/z (% RA for m/z 3475-3580) at (M - OCH3)+ 3537.3
(20), 3538.3 (30), 3539.3 (55), 3540.3 (85), 3541.3 (100), 3542.3 (90),
3543.3 (65), 3544.3 (35), 3545.3 (30); 1H NMR (CDCl3) 7.857-6.684
(m, Ar-H), 2.719 (s, 6 H), 2.687 (s, 6 H), 2.645 (s, 6 H), 2.613 (s, 6
H), 2.581 (s, 1 H, exchangeable D2O), 2.542 (s, 6 H), 2.198 (s, 1 H,
exchangeable D2O), 2.146 (s, 6 H), 1.341-1.180 (C(CH3)3).
Triple-calix[4]arene Tetradecaethers 1-(OMe)14. Sodium hydride
(0.30 g of 60% dispersion in mineral oil) was washed with pentane
under nitrogen flow followed by addition of THF (3 mL). One-half
(1.5 mL) of the resultant suspension was transferred to a solution of
diol 9Y (31.2 mg in 1 mL of THF) at 0 °C; the other half (1.5 mL)
was transferred to a solution of diol 9Z (24.1 mg in 1 mL of THF) at
0 °C. After 10 min, iodomethane (0.1 mL) was added to each reaction
mixture. The reactions were quenched with a few drops of methanol
followed by aqueous workup. PTLC (hexane/ether, 10:1) followed by
treatment with methanol gave tetradecaethers 1Y-(OMe)14 (5.8 mg,
18%) and 1Z-(OMe)14 (4.9 mg, 20%). Tetradecaether 1X-(OMe)14
(7.0 mg, 20%) was obtained by the same method from 34.2 mg of diol
9X.
1
(methoxy and tert-butyl groups) H NMR (500 MHz, EM ) -1.85,
For 1X-(OMe)14: FAB MS (3-NBA) wide-range scan, m/z (% RA
for m/z 700-4800) 3538 (40), 3570 (100); narrow-range scan, m/z (%
RA for m/z 3520-3585) at (M - OCH3)+ 3565.5 (15), 3566.5 (20),
3567.5 (50), 3568.5 (80), 3569.5 (100), 3570.5 (90), 3571.5 (65), 3572.5
(35), 3573.4 (15); Calcd for C255H297O13 at (M - OCH3)+ 3567.3 (25),
3568.3 (70), 3569.3 (100), 3570.3 (100), 3571.3 (70), 3572.3 (40),
GB ) 1.20, C6D6, 328 K) 3.168 (s, 3 H), 2.966 (s, 3 H), 2.945 (s, 3
H), 2.923 (s, 3 H), 2.901 (s, 3 H), 2.896 (s, 3 H), 2.812 (s, 3 H), 2.794
(s, 3 H), 2.780 (s, 3 H), 2.769 (s, 3 H), 2.756 (s, 3 H), 2.753 (s, 3 H),
2.648 (s, 3 H), 2.575 (bs, 3 H), 1.315 (s, 9 H), 1.306 (s, 9 H), 1.298 (s,
9 H), 1.283 (s, 9 H), 1.247 (s, 9 H), 1.239 (s, 9 H), 1.227 (s, 9 H),
1.222 (s, 9 H), 1.215 (s, 9 H), 1.206 (s, 9 H), 1.201 (s, 9 H), 1.197 (s,
9 H), 1.194 (s, 9 H), 1.191 (s, 9 H), 1.184 (s, 9 H), 1.178 (s, 9 H),
1.170 (s, 9 H), 1.153 (s, 9 H).
1
3573.3 (20), 3574.3 (10); H NMR (500 MHz, C6D6, 298 K) 8.756-
6.990 (m, ArH), 3.099 (s, 3 H), 2.982 (s, 3 H), 2.946 (s, 3 H), 2.897
(s, 3 H), 2.871 (s, 3 H), 2.853 (s, 3 H), 2.788 (s, 3 H), 2.771 (s, 3 H),
2.727 (s, 3 H), 2.685 (s, 3 H), 2.666 (s, 9 H), 2.312 (s, 3 H), 1.331 (s,
9 H), 1.321 (s, 9 H), 1.290 (s, 9 H), 1.276 (s, 9 H), 1.270 (s, 9 H),
1.249 (s, 9 H), 1.233 (s, 9 H), 1.209 (s, 9 H), 1.202 (s, 18 H), 1.199 (s,
9 H), 1.190 (s, 9 H), 1.174 (s, 9 H), 1.160 (s, 9 H), 1.156 (s, 18 H),
1.120 (s, 9 H), 1.072 (s, 9 H); 1H NMR (500 MHz, EM ) -1.85, GB
) 1.20, C6D6, 348 K) 8.652 (t, J ) 2, 1 H), 8.153 (t, J ) 2, 1 H),
8.085 (t, J ) 2, 1 H), 8.072 (t, J ) 2, 1 H), 7.890 (t, J ) 2, 1 H), 7.846
(t, J ) 2, 1 H), 7.820 (t, J ) 2, 1 H), 7.804 (d, J ) 9, 1 H), 7.788 (t,
J ) 2, 1 H), 7.734 (t, J ) 2, 1 H), 7.724 (t, J ) 2, 1 H), 7.692 (t, J )
2, 1 H), 7.669 (t, J ) 2, 1 H), 7.654 (t, J ) 2, 1 H), 7.627 (t, J ) 2,
1 H), 7.593 (d, J ) 9, 1 H), 7.530 (t, J ) 2, 1 H), 7.511-7.150 (m,
ArH), 7.127 (d, J ) 9, 1 H), 7.104 (d, J ) 9, 1 H), 7.076 (d, J ) 9, 1
H), 7.033 (d, J ) 9, 1 H), 6.991 (t, J ) 2, 1 H), 3.210 (s, 3 H), 2.975
(s, 3 H), 2.917 (s, 6 H), 2.892 (s, 3 H), 2.851 (s, 3 H), 2.847 (s, 3 H),
2.820 (s, 3 H), 2.815 (s, 3 H), 2.803 (s, 3 H), 2.758 (s, 3 H), 2.750 (s,
3 H), 2.724 (s, 3 H), 2.430 (s, 3 H), 1.329 (s, 9 H), 1.317 (s, 9 H),
1.308 (s, 9 H), 1.263 (s, 9 H), 1.243 (s, 9 H), 1.240 (s, 9 H), 1.233 (s,
9 H), 1.222 (s, 9 H), 1.221 (s, 9 H), 1.214 (s, 9 H), 1.205 (s, 9 H),
1.198 (s, 18 H), 1.186 (s, 9 H), 1.181 (s, 9 H), 1.165 (s, 9 H), 1.151 (s,
9 H), 1.129 (s, 9 H).
For 1Z-(OMe)14: FAB MS (3-NBA) wide-range scan, m/z (% RA
for m/z 700-4800) 3538 (40), 3570 (100); narrow-range scan, m/z (%
RA for m/z 3510-3595) at (M - OCH3)+ 3566.5 (20), 3567.5 (50),
3568.5 (85), 3569.5 (100), 3570.5 (95), 3571.5 (65), 3572.5 (40), 3573.5
1
(20); H NMR (500 MHz, cyclohexane-d12, 298 K) 8.297 (bs, ArH),
7.447 (s, ArH), 7.288-6.939 (m, ArH), 7.795 (s, ArH), 7.697 (s, ArH),
2.779 (bs, OCH3), 2.693 (s, OCH3), 2.619 (s, OCH3), 2.423-1.810 (2
bs, OCH3), 1.381-1.217 (overlapped, C(CH3)3); 1H NMR (500 MHz,
1
EM ) -1.85, GB ) 1.20, cyclohexane-d12, 348 K, H-1H COSY45
cross-peak) 8.087 (t, J ) 2, 2 H, 6.948, 6.682), 7.547 (t, J ) 2, 2 H,
7.079, 6.936, after 2-Hz Gaussian broadening in both dimensions), 7.344
(t, J ) 2, 2 H, 7.251, 6.878), 7.271 (d, J ) 9, 4 H, 7.167), 7.251 (t, J
) 2, 2 H, 7.344, 6.878), 7.211 (t, J ) 2, 2 H, 7.190, 7.001), 7.190 (t,
J ) 2, 2 H, 7.211, 7.001), 7.177 (d, J ) 9, 4 H, 7.103), 7.167 (d, J )
9, 4 H, 7.271), 7.160 (d, J ) 9, 4 H, 7.075), 7.140 (d, J ) 9, 4 H,
7.066), 7.131 (d, J ) 9, 2 H, 7.016), 7.103 (d, J ) 9, 4 H, 7.177),
7.079 (d, J ) 9, 4 H, 6.836), 7.075 (d, J ) 9, 4 H, 7.160), 7.079 (t, J
) 2, 2 H, 7.547, 6.936), 7.071 (d, J ) 9, 4 H, 7.031), 7.066 (d, J ) 9,
4 H, 7.140), 7.050 (d, J ) 9, 2 H, 7.014), 7.050 (d, J ) 9, 4 H, 7.031),
7.031 (d, J ) 9, 4 H, 7.050), 7.031 (d, J ) 9, 4 H, 7.071), 7.016 (d, J
) 9, 2 H, 7.131), 7.014 (d, J ) 9, 2 H, 7.050), 7.010 (d, J ) 9, 4 H,
6.845), 7.001 (t, J ) 2, 2 H, 7.211, 7.190), 6.948 (t, J ) 2, 2 H, 8.087,
6.682), 6.936 (t, J ) 2, 2 H, 7.547, 7.079), 6.878 (t, J ) 2, 2 H, 7.251,
7.344), 6.845 (d, J ) 9, 4 H, 7.010), 6.836 (d, J ) 9, 4 H, 7.079),
6.682 (t, J ) 2, 2 H, 8.087, 6.948), 2.841 (s, 6 H), 2.707 (s, 6 H),
2.680 (s, 6 H), 2.637 (s, 6 H), 2.607 (s, 6 H), 2.486 (s, 6 H), 2.156 (bs,
6 H), 1.380 (bs, cyclohexane-d12 possibly overlapping some resonances
for t-Bu groups), 1.293 (s, 18 H), 1.252 (s, 54 H), 1.245 (s, 18 H),
1.239 (s, 18 H), 1.232 (s, 18 H), 1.214 (s, 18 H).
For 1Y-(OMe)14: FAB MS (3-NBA) wide-range scan, m/z (% RA
for m/z 700-4800) 3538 (45), 3570 (100); narrow-range scan, m/z (%
RA for m/z 3515-3590) at (M - OCH3)+ 3565.5 (15), 3566.5 (20),
3567.5 (45), 3568.5 (80), 3569.5 (100), 3570.5 (85), 3571.5 (65), 3572.5
(35), 3573.5 (20), 3574.4 (10); 1H NMR (500 MHz, C6D6, 298 K)
8.752-6.989 (m, ArH), 3.111 (s, 3 H), 3.001 (s, 3 H), 2.938 (s, 3 H),
2.903 (s, 3 H), 2.879 (s, 3 H), 2.798-2.709 (27 H), 1.299 (s, 9 H),
1.283 (s, 9 H), 1.273 (s, 9 H), 1.253 (s, 9 H), 1.220 (s, 9 H), 1.211 (bs,
18 H), 1.194 (s, 27 H), 1.190 (s, 9 H), 1.182 (s, 9 H), 1.161 (bs, 27 H),
1
1.136 (s, 9 H); H NMR (500 MHz, EM ) -1.85, GB ) 1.20, C6D6,
Reaction of Tetradecaethers 1-(OMe)14 with Na/K and MeOH
Quenching Product 1-(H)14. A drop of Na/K alloy was added to a
stirred tetradecaether (∼1 mg) in THF (∼0.5 mL) in a Schlenk vessel.
After 4 days of stirring, MeOH (few drops) was added. The usual
aqueous workup with ether gave crude product. Preparative TLC (2%
ether in hexane) gave 1-(H)14 (∼1 mg), most likely, as a mixture of
isomers: 1H NMR (500 MHz, acetone-d6) 7.7-6.2 (bm, 96 H), 5.6-
4.8 (bm, ∼14 H), 1.5-1.0 (bm, ∼200 H); FAB MS (3-NBA) wide-
range scan, m/z (% RA for m/z 1150-4900) 1399 (90), 3180 (100);
348 K, 1H-1H COSY cross-peak) 8.665 (t, J ) 2, 1 H, 7.629, 7.271),
8.272 (t, J ) 2, 1 H, 8.008, 7.254), 8.182 (t, J ) 2, 1 H, 7.413, 7.364),
8.008 (t, J ) 2, 1 H, 8.272, 7.254), 7.971 (t, J ) 2, 1 H, 7.614, 7.475),
7.900 (t, J ) 2, 1 H, 7.712, 7.468), 7.857 (t, J ) 2, 1 H, 7.649, 7.496),
7.799 (t, J ) 2, 1 H, 7.670, 7.601), 7.791 (d, J ) 9, 2 H, 7.271), 7.757
(t, J ) 2, 1 H, 7.568, 7.481), 7.712 (t, J ) 2, 1 H, 7.900, 7.486), 7.670
(t, J ) 2, 1 H, 7.799, 7.601), 7.649 (t, J ) 2, 1 H, 7.857, 7.496), 7.629
(t, J ) 2, 1 H, 8.665, 7.271), 7.614 (t, J ) 2, 1 H, 7.971, 7.475), 7.601

High-Spin Polyarylmethyl Polyradical
J. Am. Chem. Soc., Vol. 119, No. 43, 1997 10345
follow up solvent), this process was repeated 10-15 times until the
reaction mixture attained pale yellow-green color. While maintaining
the reaction mixture at near freezing point, a small portion of the
reaction mixture was transferred to the quartz tube to form a band of
the ∼4 mm height, 65 mm from the end of the tube. The tube was
flame sealed and stored in liquid nitrogen for insertion to SQUID
magnetometer.
The remainder of the polyradical was stirred with Na/K at near
freezing point of the reaction mixture for several hours and, then, at
-78 °C a few days. At -78 °C, either MeOH or MeOD (few drops)
was added. The usual aqueous workup with ether gave crude product.
Preparative TLC (2% ether in hexane) gave 1-(X)14 (X ) H, D, ∼1
mg), most likely, as a mixture of isomers.
Tetradecaradical 1 in THF-d8/2-MeTHF after MeOD quench,
1
1-(D)14: H NMR (500 MHz, acetone-d6) 7.7-6.2 (bm, 96 H), 5.6-
4.8 (bm, ∼2 H), 1.5-1.0 (bm, ∼200 H); 2H NMR (76.8 MHz, acetone-
h6) ∼5.4 (bs); FAB MS (3-NBA) wide-range scan, m/z (% RA for m/z
1500-3280) 3193 (100); narrow-range scan, m/z (% RA for m/z 3000-
3260) at (M - D)+/(M - H)+ 3188.1 (50), 3189.1 (70), 3190.1 (85),
3191.1 (100), 3192.1 (100), 3193.1 (93), 3194.2 (70), 3195.2 (55).
Tetradecaradical 1 in THF-d8 after MeOH quench, 1-(H)13(D)1:
1H NMR (500 MHz, acetone-d6) 7.7-6.2 (bm, 96 H), 5.6-4.8 (bm,
∼14 H), 1.5-1.0 (bm, ∼200 H); FAB MS (3-NBA) wide-range scan,
m/z (% RA for m/z 1500-3280) 3181 (100); narrow-range scan, m/z
(% RA for m/z 3000-3260) at (M - H)+ 3178.2 (65), 3179.2 (80),
3180.2 (100), 3181.2 (95), 3182.2 (85), 3183.2 (70); calcd for
C242H270D1 3178.1 (27), 3179.1 (73), 3180.1 (100), 3181.1 (90), 3182.1
(61), 3183.1 (33).
SQUID Magnetometry. A Quantum Design (San Diego, CA)
MPMS5S was used. The sample tubes were inserted to the mag-
netometer at low temperature under helium atmosphere as described
previously.30 Following the insertion to the sample chamber at 10 K,
the sample was immediately cooled to 30-40 K for a few minutes.
Subsequently, temperature in the sample chamber was increased to 90
K for 15-20 min and several sequences of helium purging and pumping
were applied to remove residual oxygen.
Following the measurement, the sample tube was allowed to attain
ambient temperature. After 6 weeks, the magnetic moment was
negligible (∼1% of the original value) and the sample was carefully
inserted to the magnetometer and subjected to the identical sequence
of measurements as the original sample. Such data were used for point-
by-point correction for diamagnetism.
Figure 10. Vessel for preparation of polyradical 1. “A” is a
compartment for generation of carbopolyanion, “B” is a coarse glass
frit, “C” is a compartment for generation of polyradical, “D” is a glass-
to-quartz seal, “E” is a 5 mm o.d. quartz tube with a thin flat bottom,
ca. 65 mm from the end of the tube, “F” is a 4-mm high-vacuum Kontes
stopcock, and “G” is a 9 mm solv-seal joint.
narrow-range scan, m/z (% RA for m/z 3110-3230) at (M - H)+ 3177.1
(40), 3178.1 (75), 3179.1 (100), 3180.1 (95), 3181.1 (85), 3182.1 (60);
calcd for C242H271 3177.1 (27), 3178.1 (73), 3179.1 (100), 3180.1 (90),
3181.1 (61), 3182.1 (33).
Numerical Curve Fitting. SigmaPlot for Windows software
package was used for numerical curve fitting. The reliability of a fit
is measured by the parameter dependence, which is defined as
dependence ) 1 - ((variance of the parameter, other parameter
constant)/(variance of the parameter, other parameters changing)).
Values close to 1 indicate overparametrized fit.
Tetradecaradical 1: Quenching Studies and SQUID Magnetom-
etry. Tetradecaether (∼2 mg) was placed in the compartment A of
the oxidation vessel (Figure 10). Following the heating of the vessel
under vacuum overnight (compartment A to ∼60 °C and the rest of
the vessel to 200 °C), the vessel was moved to an argon-filled glovebox
and a drop of Na/K alloy was attached to the wall in the compartment
A. The vessel was connected to the vacuum line, THF-d8 (∼0.3 mL)
was transferred under high vacuum from purple sodium/benzophenone,
and the Na/K alloy was allowed to contact the solution. After ∼4 days
of stirring, the reaction mixture (deep red color) was filtered and cooled
to the temperature just above the freezing point of THF-d8 (ap-
proximately -105 °C) with an acetone/EtOH/liquid nitrogen bath. A
small amount of iodine was transferred over the vacuum line to the
reaction mixture, followed by small amount of solvent, either 2-MeTHF
or THF-d8. While the temperature was maintained as low as possible
to permit stirring of the reaction mixture (-115 °C, for 2-MeTHF, as
Acknowledgment. We gratefully acknowledge the National
Science Foundation, Chemistry Division for the support of this
research (CHE-9510096) and The Camille and Henry Dreyfus
Teacher-Scholar Award Program (1991-1996). We thank Dr.
Ronald Cerny of the Nebraska Center for Mass Spectrometry
for mass spectral determinations and Dr. Richard Schoemaker
for two-dimensional NMR spectra. We thank Mr. Jirawat
Wongsriratanakul, Ms. Nisakorn Thongkon, and Dr. Shailesh
Desai for their help with the synthesis.
JA971493J
(30) Rajca, A.; Utamapanya, S.; Thayumanavan, S. J. Am. Chem. Soc.
1992, 114, 1884.