Preparation, structure determination, and electrochemical properties of bis{[1,4,8,11, 15,18,22,25-octaethyl-2,3,9,10,16,17,23,24-octakis(methylthio)- phthalocyaninato]titanium(IV)} benzene-1,2,4,5-tetrathiolate

Article abstract of DOI:10.1002/ejoc.200800502

4,5-Bis(methylthio)phthalonitrile 2 was prepared from 2,3,5,6- tetrabromodiethylbenzene in four steps. Tetramerization and cyclization of phthalonitrile 2 with lithium n-pentoxide at 115°C produced octaethyl-octakis(methylthio)phthalocyanine (3). A titanium atom was introduced into the phthalocyanine 3 by treatment with titanium(IV) tetrabutoxide in DMF at 130°C to give the corresponding metal complex 3-TiO. Linking of two molecules of the phthalocyanine 3-TiO with benzene-1,2,4,5-tetrathiol (BTT) produced a double-decker-type compound, bis{[octaethyl-octakis-(methylthio) phthalocyaninato]titanium(IV)} benzenetetrathiolate (6), in which the two phthalocyanines are connected axially through four titanium-sulfur coordination bonds. Double-decker derivative 7 was also obtained by a similar treatment of (tetra-tert-butylphthalocyaninato)titanium(IV) oxide with BTT. The structures of 6 and 7 were determined by NMR, IR, UV/Vis spectroscopy and FAB mass spectrometry. Both phthalocyanine skeletons of 6 have symmetrical structures, as shown by the ¹H and ¹³C NMR spectra. The electrochemical properties of 6 were examined by cyclic voltammetry with Ag/AgNO₃ as the reference electrode. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejoc.200800502

FULL PAPER
DOI: 10.1002/ejoc.200800502
Preparation, Structure Determination, and Electrochemical Properties of
Bis{[1,4,8,11,15,18,22,25-octaethyl-2,3,9,10,16,17,23,24-octakis(methylthio)-
phthalocyaninato]titanium(IV)} Benzene-1,2,4,5-tetrathiolate
Takeshi Kimura,*[a] Jun Kumasaka,[a] and Toshiharu Namauo[a]
Keywords: Phthalocyanines / Titanium / S ligands / Double-decker molecules
4,5-Bis(methylthio)phthalonitrile 2 was prepared from
2,3,5,6-tetrabromodiethylbenzene in four steps. Tetrameriza-
tion and cyclization of phthalonitrile 2 with lithium n-pentox-
nected axially through four titanium–sulfur coordination
bonds. Double-decker derivative 7 was also obtained by a
similar treatment of (tetra-tert-butylphthalocyaninato)titani-
ide at 115 °C produced octaethyl-octakis(methylthio)phthalo- um(IV) oxide with BTT. The structures of 6 and 7 were deter-
cyanine (3). A titanium atom was introduced into the
phthalocyanine 3 by treatment with titanium(IV) tetrabutox-
ide in DMF at 130 °C to give the corresponding metal com-
plex 3-TiO. Linking of two molecules of the phthalocyanine
3-TiO with benzene-1,2,4,5-tetrathiol (BTT) produced a
double-decker-type compound, bis{[octaethyl-octakis-
(methylthio)phthalocyaninato]titanium(IV)} benzenetet-
mined by NMR, IR, UV/Vis spectroscopy and FAB mass spec-
trometry. Both phthalocyanine skeletons of 6 have symmetri-
cal structures, as shown by the 1H and 13C NMR spectra.
The electrochemical properties of 6 were examined by cyclic
voltammetry with Ag/AgNO3 as the reference electrode.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
rathiolate (6), in which the two phthalocyanines are con- Germany, 2008)
trochemical and optical properties of octakis(benzylthio)-
Introduction
phthalocyanine (PcSBn), tetrakis(o-xylylenedithio)phthalo-
cyanines (PcSXyl), and related derivatives.[10] In relation to
the application of phthalocyanine to new functional materi-
als, it is significant that a Q-band absorption lies in the
near-infrared region of the UV/Vis absorption spectrum.
The Q-bands of PcSBn and PcSXyl are observed at around
760 nm, which is a longer wavelength than that of unsubsti-
tuted phthalocyanine. To fabricate a double-decker-type
phthalocyanine with a symmetric structure and titanium–
sulfur bonds, octaethyl-octakis(methylthio)phthalocyanin-
atotitanium(IV) oxide (3-TiO) was prepared from diethyl-
benzene in seven steps and treated with benzene-1,2,4,5-tet-
rathiol (BTT). A double-decker compound consisting of
tBuPcTiO and BTT was also constructed. This paper re-
ports the preparation, structure determination, and the
electrochemical and optical properties of the double-
decker-type phthalocyanines connected through four tita-
nium–sulfur bonds.
Tetraazaporphyrins, phthalocyanines, and related com-
pounds have a variety of actual and potential applications
in many fields, for example, as dyes, pigments, catalysts, new
functional materials, and sensitizers for photodynamic ther-
apy.[1–4] Among the large number of these derivatives,
phthalocyanines that connect one or two axially coordinat-
ing groups on the central metal atom or that have a double-
decker structure have attracted much attention because
such molecules may be applied to electrochromic displays,
field-effect transistors, nonlinear optical materials, and dye-
sensitized solar cells.[1,5,6] Recently, Hanack and co-workers
reported (phthalocyaninato)titanium(IV) complexes as
compounds that have axially coordinating groups linked
through titanium–oxygen or titanium–sulfur bonds,[7] and
Kobayashi and co-workers have prepared a mutually per-
pendicular phthalocyanine pentamer and related deriva-
tives.[8] These products were prepared by the ligand-ex-
change reaction of (tetra-tert-butylphthalocyaninato)titani-
um(IV) oxide (tBuPcTiO) with o-catechol derivatives, o-
benzenedithiol, tetrahydroxy-p-benzoquinone, and octahyd-
roxyphthalocyanine. The compound constructed by the re-
action of tBuPcTiO with tetrahydroxy-p-benzoquinone in a
2:1 ratio is an unsymmetric double-decker-type molecule.
As a result of our continuing study of several cyclic oligo-
sulfides,[9] we recently reported the preparation and the elec-
Results and Discussion
4,5-Bis[(2-cyanoethyl)thio]-3,6-diethylphthalonitrile (1)
was prepared according to a method described previous-
ly.[10a] Compound 1 was treated with cesium hydroxide and
then methyl iodide in THF/methanol at room temperature
to produce 3,6-diethyl-4,5-bis(methylthio)phthalonitrile (2)
in 66% yield (Scheme 1). Two ethyl groups on the benzene
ring positioned next to the two sulfur atoms are required
[a] Center for Instrumental Analysis, Iwate University,
Morioka, Iwate 020-8551, Japan
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T. Kimura, J. Kumasaka, T. Namauo
FULL PAPER
to prepare compound 1 from 1,4-diethylbenzene by way of duce a dark-green precipitate. The product was separated
diethyl-1,2,3-benzotrithiole as a precursor. It is expected by silica gel column chromatography to give phthalocyanine
that electron-donating functional groups at the α-positions 3 in 41% yield.
of phthalocyanine cause the Q-band to shift to a longer
It is essential that phthalocyanine must have an appropri-
wavelength,[11] and phthalocyanine with methylthio groups ate metal atom in the central cavity in order to bind a bi-
simplifies the structure of the double-decker molecule com- dentate ligand in an axial fashion. Compound 3 was treated
pared with the benzylthio and xylylenedithio deriva- with titanium(IV) tetrabutoxide in DMF at 130 °C under
tives.[10a,10b] Tetramerization and cyclization of phthalonitr- argon for 2 h. After workup, a green solid was obtained and
ile 2 upon treatment with lithium in n-pentanol at 115 °C purified by column chromatography on silica gel to produce
for 1 h gave a green solid, which was filtered, dried, and [octaethyl-octakis(methylthio)phthalocyaninato]titanium(IV)
purified by silica gel column chromatography to produce oxide (3-TiO) in 96% yield. In contrast, the reaction of 2
octaethyl-octakis(methylthio)phthalocyanine (3) in 37% with urea, a few drops of DBU, and titanium(IV) tetrabu-
yield. Although the ethyl and methylthio groups on the toxide in n-pentanol at 155 °C under argon, which is a pro-
macrocycle are unobtrusive substituents, phthalocyanine 3 cedure used for the preparation of (phthalocyaninato)-
1
is soluble in chloroform and THF. In the H NMR spec- titanium(IV) oxide,[7] gave no product. In the 1H NMR
trum, compound 3 shows one triplet and one broadened spectrum of compound 3-TiO, one triplet and one double
quartet for the ethyl groups at δ = 1.66 and 4.89 ppm, quartet signal for the ethyl groups were observed together
respectively, and one singlet peak for the methylthio groups with one singlet peak for the methylthio groups (δ = 1.74,
at δ = 2.75 ppm. The signal of the two protons on the cen- 2.78, 4.94, and 5.02 ppm). The signals appeared at a slightly
tral pyrrole nitrogen atoms could not be observed in the lower field than did those of 3. The 13C NMR spectrum of
spectrum because of proton alternation. A UV/Vis absorp- 3-TiO showed three signals for the ethyl and the methylthio
tion spectrum showed that the Q-band absorption of 3 groups (δ = 16.8, 22.3, and 25.2 ppm) and four aromatic
(λmax = 750 nm, logε = 5.06) lies close to that of PcSBn signals for the phthalocyanine core (δ = 134.0, 146.8, 147.1,
(λmax = 755 nm, logε = 5.1). The structure of 3 was deter- and 151.8 ppm), which suggests that the compound has a
mined by fast atom bombardment mass spectrometry symmetric structure.[13] In the UV/Vis spectrum, the Q-
(FAB-MS), which showed the molecular ion peak ([M]+) at band of 3-TiO (λmax = 760 nm, logε = 5.15) was observed
m/z = 1106.35.
at a lower energy and with a narrower bandwidth than that
of 3 (Figure 1). It seems that the metallation of phthalocy-
anine with titanium(IV) oxide shifts the Q-band absorption
to a longer wavelength compared with that of the metal-
free molecule. To determine the structure, the FAB mass
spectrum of 3-TiO was recorded and the molecular ion
peak ([M]+) observed at m/z = 1168.3. In contrast,
tBuPcTiO was prepared by treatment of tert-butyl-
phthalonitrile with titanium(IV) tetrabutoxide by using a
literature procedure.[7]
Scheme 1. Preparation of the phthalocyanines.
Figure 1. UV/Vis spectra of phthalocyanines 3, 3-TiO, and 6 (c =
1.00ϫ10–5 mol/L).
Removal of the benzyl groups from PcSBn by Birch re-
duction may be utilized to prepare a new phthalocyanine
The construction of the double-decker-type compound
with eight sulfur functional groups at the β-positions.[10,12] with titanium–sulfur bonds from two molecules of (phthal-
Thus, PcSBn was treated with lithium metal in THF/liquid ocyaninato)titanium(IV) oxide required BTT as a link
ammonia under argon at –70 °C for 1 h. The solution was molecule. Wudl and co-workers have reported an excellent
gradually warmed to –33 °C and then to room temperature. procedure for the preparation of BTT.[14,15] 1,2,4,5-Tetrakis-
After evaporation of the ammonia, methyl iodide was (methylthio)benzene (4) was prepared from 1,2,4,5-tetra-
slowly added, and the solution was stirred for 20 h to pro- chlorobenzene according to the reported procedure.[14] The
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Properties of a Titanium(IV) Benzene-1,2,4,5-tetrathiolate
carbon–sulfur bond cleavage was achieved by the reaction
of 4 with lithium in THF/liquid ammonia, and the product
was purified by column chromatography. However, the BTT
obtained was easily oxidized in air to give an insoluble col-
orless solid. Therefore, the tetrathiol groups of BTT were
protected: Compound 4 was treated with lithium in THF/
liquid ammonia according to the procedure described
above, and the generated benzenetetrathiolate was sub-
sequently treated with 3-bromopropionitrile in THF/meth-
anol at room temperature. 1,2,4,5-Tetrakis(2-cyano-
ethylthio)benzene (5) was obtained according to this pro-
cedure in 31% yield (Scheme 2). Compound 5 was purified
more readily than BTT. The four thiol groups of BTT can
be generated from 5 in the reaction mixture before use in
the complexation reaction with 3-TiO and tBuPcTiO by
treatment with cesium hydroxide in THF/methanol under
argon at room temperature for 3 h. The reaction mixture
was acidified with concentrated hydrochloric acid. The pre-
pared solution was transferred by syringe under argon to a
reactor containing 3-TiO, and the reaction mixture was
stirred for 18 h. In the reaction, the oxygen atom on the
Scheme 3. Construction of the double-decker molecules.
titanium atom was gradually exchanged with benzenetet- shift of the aromatic ortho protons of benzenedithiolate
rathiolate. After workup, the green product was purified by connected axially to (tetra-tert-butylphthalocyaninato)tita-
column chromatography on silica gel and then on Bio- nium(IV) appeared at δ ≈ 5.9 ppm.[7b]
beads to produce bis{[octaethyl-octakis(methylthio)-
The 1H NMR spectrum of 7 shows similar signals to that
phthalocyaninato]titanium(IV)} benzenetetrathiolate (6) in of tBuPcTiO, and the aromatic protons of the benzenetet-
17% yield (Scheme 3). According to a similar treatment of rathiolate were observed at δ ≈ 3.60–3.62 ppm. When the
tBuPcTiO with BTT as described above, bis{[tetra-tert-bu- 13C NMR spectrum of 6 was recorded, the four signals cor-
tylphthalocyaninato]titanium(IV)} benzenetetrathiolate (7) responding to the phthalocyanine skeleton and the three
was obtained in 20% yield. Compounds 6 and 7 are stable signals arising from the ethyl and methylthio groups ap-
in air.
peared at δ = 16.4, 22.1, 25.1, 132.7, 146.5(0), 146.5(4), and
151.0 ppm, which are similar chemical shifts to those of 3-
TiO. The signals arising from the aromatic carbon atoms
of benzenetetrathiolate were observed at δ = 117.3 and
146.3 ppm and are different to the corresponding signals of
5 (δ = 134.3, 136.2 ppm).
The absorption wavelength and molar extinction coeffi-
cient of phthalocyanine 6 were determined by UV/Vis spec-
troscopy (Figure 1). The Q-band absorption of phthalocy-
anine 6 was observed at λmax = 757 nm (logε = 5.05). It can
be observed that the absorption of 6 has a slightly blue-
shifted wavelength (3 nm), decreased intensity, and broad-
ened bandwidth compared with that of 3-TiO, which could
originate from the double-decker structure of 6. Thus, it is
expected that the two phthalocyanines in the molecule in-
Scheme 2. Preparation of BTT.
The structures of 6 and 7 were examined by NMR spec- teract electronically with each other in the excited state on
1
troscopy. In the H NMR spectrum of 6, the signals of the measuring the spectrum. In the UV/Vis spectrum of 7, one
ethyl and methylthio groups connected to the phthalocyan- slightly broadened Q-band was observed at a slightly
ine core show clear up-field shifts compared with those of shorter wavelength than that of tBuPcTiO. To determine
3 and 3-TiO (δ = 1.40, 2.61, and 4.64 ppm), and the methyl- the structure, FAB mass spectra of 6 and 7 were recorded,
ene proton was observed as one broadened signal, which which showed molecular ion peaks ([M]+) at m/z = 2508.50
suggests that the two phthalocyanines exist in a C4-symmet- for 6 and m/z = 1770.60 for 7. These results imply that com-
ric structure on the NMR timescale. The signal arising from pounds 6 and 7 consist of two phthalocyanines and a ben-
the central benzene ring of the benzenetetrathiolate was ob- zenetetrathiolate. In the IR spectrum, the signal observed
served at δ = 3.79 ppm as one singlet peak, which shows at 972 cm–1 for the Ti=O bond of tBuPcTiO faded away in
that the benzene ring lies between the two phthalocyanine the spectrum of 7.[7,16] The signal at 977 cm–1 in the spec-
planes and is strongly influenced by the magnetic shielding trum of 3-TiO also disappeared in the spectrum of 6 with
of the macrocycle. According to Hanack et al. the chemical four strong signals observed at around 1050 cm–1.
Eur. J. Org. Chem. 2008, 5079–5084
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T. Kimura, J. Kumasaka, T. Namauo
FULL PAPER
The electrochemical properties of phthalocyanines 3, 3-
TiO, and 6 were examined by cyclic voltammetry using Ag/
AgNO3 as the reference electrode (solvent: CH2Cl2; scan
rate: 200 mV/s). The cyclic voltammogram of 3 contains
two reversible oxidations (E1/2 = 0.52 and 0.91 V) and two
reversible reduction potentials (E1/2 = –1.08 and –1.41 V),
which are slightly lower reduction potentials and higher
oxidation potentials than those of PcSBn (Table 1). In the
case of 3-TiO, there is one reversible and one irreversible
oxidation potential (E1/2 = 0.68 V and Ep = 1.13 V, respec-
tively) and two reversible reduction potentials (E1/2 = –0.80
and –1.14 V). It appears that the oxidation potential of the
titanium complex 3-TiO is slightly higher than that of 3.
As shown in Figure 2, one quasi-reversible oxidation poten-
tial (E1/2 = 0.70 V) and two reversible reduction potentials
(E1/2 = –0.86 and –1.14 V) were observed for 6. However,
the compound clearly did not show a peak potential for a
second oxidation. It seems that the first oxidation potential
for 6 is an overlay of two slightly different potentials. The
two different potentials may be related to an electronic in-
teraction between the two phthalocyanines through the cen-
tral benzene ring under the oxidation conditions. The first
oxidation potential of 6 is slightly higher than those of 3
and PcSBn, whereas the reduction and first oxidation po-
tentials are similar to those of 3-TiO. The differences in
potential (∆E) between the first oxidation and the first re-
duction were calculated to estimate the HOMO–LUMO
gaps of 3, 3-TiO, and 6, and are ∆E = 1.60, 1.48, and
1.56 V, respectively. It appears that the HOMO–LUMO gap
of 6 is lower than that of 3 and higher than that of 3-TiO.
The order of the HOMO–LUMO gaps of 3, 3-TiO, and 6
are in accord with the wavelengths of the Q band absorp-
tion.
Conclusions
Phthalocyanine 3 was prepared by tetramerization and
cyclization of 2 and subsequent treatment with titanium(IV)
tetrabutoxide, and then BTT produced double-decker
phthalocyanine 6. Double-decker derivative 7 was obtained
by a similar treatment of tert-butylphthalonitrile. As com-
pounds 6 and 7 did not decompose in air, the four tita-
nium–sulfur bonds in the product are stable. In the 1H
NMR spectrum of 6, the proton signal arising from the
central benzene ring was observed at an extremely high field
compared with that of usual aromatic compounds, which
suggests that the aromatic protons are strongly shielded in
the magnetic field of the phthalocyanines. As there are three
1
signals in the H NMR spectrum and seven signals in the
13C NMR spectrum for the phthalocyanines in compound
6, both phthalocyanines are C4-symmetric structures, which
suggests that the phthalocyanine rings can rotate around
the axial axis. The UV/Vis spectrum of 6 showed decreased
absorption and a broader bandwidth than those of the cor-
responding titanium oxides. Furthermore, the first oxi-
dation potential of 6 was observed as one quasi-reversible
oxidation potential. The results suggest that the two phthalo-
cyanines of 6 electronically interact with each other through
the central benzenetetrathiolate moiety in photochemically
excited and electrically oxidized states.
Experimental Section
General: NMR spectra were measured with a Bruker AC-400 spec-
trometer. Mass spectra were obtained with a JEOL JMS-700 mass
spectrometer. UV/Vis spectra were recorded with a JASCO Ubest
V-570 spectrometer. A JASCO FT/IR-4200 spectrometer was em-
ployed to record IR spectra. A Hokuto Denko Co. Model HAB-
151 apparatus was used to measure the oxidation potentials. Bio-
beads (SX-1) for column chromatography were purchased from
Nippon Bio-Rad Laboratories.
Table 1. Redox potentials (vs. Ag/AgNO3).
Compound
E1/2 [V]
∆E[a] [V]
2nd re-
duction
1st re-
duction
1st oxi-
dation
2nd oxi-
dation
Oxidation Potentials: All measurements were performed by cyclic
voltammetry using Ag/AgNO3 (0.01 mol/L) as a reference electrode
(scan rate: 200 mV/s). A solution of nBu4NClO4 in CH2Cl2
(0.1 mol/L) was used as the electrolyte. The oxidation potential of
ferrocene was observed at E1/2 = 0.09 V with the apparatus without
any correction.
3
–1.41
–1.14
–1.14
–1,32
–1.08
–0.80
–0.86
–1.03
0.52
0.68
0.91
1.13[b]
–
1.60
1.48
1.56
1.52
3-TiO
6
PcSBn
0.70[c]
0.49
0.72
[a] ∆E is the difference between the first oxidation potential and the
first reduction potential. [b] Irreversible oxidation potential (Ep). [c]
Quasi-reversible oxidation potential.
4,5-Bis[(2-cyanoethyl)thio]-3,6-diethylphthalonitrile (1): Compound
1 was prepared from 1,4-diethylbenzene according to a method de-
scribed previously.[10a]
3,6-Diethyl-4,5-bis(methylthio)phthalonitrile (2): Compound
1
(0.522 g, 1.48 mmol) in THF (20 mL)/MeOH (20 mL) was treated
with CsOH·H2O (0.98 g, 6.60 mmol) at room temperature. Methyl
iodide (0.5 mL, 8.0 mmol) was then added, and the solution was
stirred at room temperature for 12 h. After acidification and evapo-
ration of the solvent, the product was extracted with CHCl3. The
solvent was evaporated, and the residue was purified by column
chromatography (Wakogel C-300HG, n-hexane/CHCl3 = 1:1 and
then CHCl3) to produce 2 in 66% yield (0.250 g); yellow crystals;
m.p. 150.5–151.0 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 1.29
4
4
(t, JH,H = 7.5 Hz, 6 H, CH3), 2.51 (s, 6 H, SCH3), 3.23 (q, JH,H
= 7.5 Hz, 4 H, CH2Ar) ppm. 13C NMR (101 MHz, CDCl3, 25 °C):
δ = 15.5, 21.0, 28.8, 115.0, 116.0, 149.6, 152.0 ppm. HRMS (EI):
calcd. for C14H16N2S2 [M]+ 276.0755; found 276.0756.
Figure 2. Cyclic voltammograms of 6.
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Properties of a Titanium(IV) Benzene-1,2,4,5-tetrathiolate
4
1,4,8,11,15,18,22,25-Octaethyl-2,3,9,10,16,17,23,24-octakis(methyl-
thio)phthalocyanine (3): Lithium (40 mg, 5.7 mmol) was placed in a
glass reactor, and n-pentanol (2 mL) was added under Ar. The solu-
tion was stirred at 115 °C for several minutes. Compound 2
(190 mg, 0.688 mmol) was added to the solution, which was then
stirred at 115 °C for 1 h. Then the reactor was cooled, aqueous
HCl and MeOH were added, and a green precipitate was filtered
off. The residue was purified by column chromatography (Wakogel
C-300HG, n-hexane/CHCl3 = 1:1, and Bio-beads, CHCl3) to pro-
duce 3 in 37% yield (70 mg); dark-green crystals; m.p. Ͼ300 °C.
3.21 (t, JH,H = 6.8 Hz, 8 H, CH2), 7.50 (s, 2 H, ArH) ppm. 13C
NMR (101 MHz, CDCl3, 25 °C): δ = 18.4, 29.2, 117.8, 134.3,
136.2 ppm. HRMS (EI): calcd. for C18H18S4 [M]+ 418.0414; found
418.0408.
Bis{[1,4,8,11,15,18,22,25-Octaethyl-2,3,9,10,16,17,23,24-octakis-
(methylthio)phthalocyaninato]titanium(IV)} Benzene-1,2,4,5-tetra-
thiolate (6): Compound 5 (24.1 mg, 0.058 mmol) and CsOH·H2O
(400 mg, 2.4 mmol) were placed in a glass reactor under Ar. THF
(5 mL) and MeOH (5 mL) were added to the reactor, and the solu-
tion was stirred for 3 h. Concentrated HCl (0.4 mL) was added,
and the solution was transferred by syringe under Ar to a reactor
containing 3-TiO (99.6 mg, 0.085 mmol) and THF (3 mL). The
solution was stirred for 18 h, and the solvent was evaporated. The
residue was purified by column chromatography (Wakogel C-
300HG, n-hexane/CHCl3 = 1:1, and Bio-beads, CHCl3) to produce
6 in 17% yield (18.6 mg); dark-green powder, m.p. Ͼ300 °C. 1H
4
1H NMR (400 MHz, CDCl3, 25 °C): δ = 1.66 (t, JH,H = 7.4 Hz,
4
24 H, CH3), 2.75 (s, 24 H, SCH3), 4.89 (br. q, JH,H = 7.4 Hz, 16
H, CH2) ppm. UV (CHCl3): λmax = 750 nm (logε = 5.06). MS
(FAB): m/z = 1106.35 [M]+. PcSBn (120 mg, 0.07 mmol) and lith-
ium (42 mg, 6.1 mmol) were placed in a glass reactor, and THF
(5 mL) was added under Ar. Then the solution was cooled to
–70 °C, and NH3 (30 mL) was introduced into the reactor and con-
densed. The solution was stirred at this temperature for 1 h and
gradually warmed to –33 °C. NH3 was evaporated in a stream of
N2 gas. After the evaporation of NH3 was complete, THF (5 mL)
and MeOH (10 mL) were added to the blue-green solid. NH4Cl
(370 mg, 6.9 mmol) and MeI (0.4 mL, 6.4 mmol) were added, and
the solution was stirred at room temperature for 20 h. Aqueous
HCl and MeOH were added to the solution, and a green precipitate
was filtered off. The residue was purified by column chromatog-
raphy (Wakogel C-300HG, n-hexane/CHCl3 = 1:1) to produce 3 in
41% yield (31.6 mg).
4
NMR (400 MHz, CDCl3, 25 °C): δ = 1.40 (t, JH,H = 7.3 Hz, 48
H, CH3), 2.61 (s, 48 H, SCH3), 3.79 (s, 2 H, ArH), 4.64 (br., 32 H,
CH2) ppm. 13C NMR (101 MHz, CDCl3, 25 °C): δ = 16.4, 22.1,
25.1, 117.3, 132.7, 146.3, 146.5(0), 146.5(4), 151.0 ppm. UV/Vis
(CHCl3): λmax = 757 nm (logε = 5.05). IR (KBr): ν = 2962, 2917,
˜
2850, 1733, 1455, 1340, 1298, 1262, 1217, 1181, 1094, 1051, 968,
941, 801 cm–1. MS (FAB): m/z = 2506.50 [M]+. C118H130N16S20Ti2
(2506.40): C 56.48, H 5.22, N 8.93; found C 57.57, H 5.71, N 8.16.
(Tetra-tert-butylphthalocyaninato)titanium(IV) Oxide (tBuPcTiO):
tert-Butylphthalonitrile (1.038 g, 5.672 mmol), urea (188 mg,
3.133 mmol), and 8 drops of DBU were placed in a glass reactor
under Ar. Ti(OBu)4 (0.8 mL, 2.354 mmol) and n-pentanol (10 mL)
were added to the reactor, and the solution was stirred at 155 °C
for 7 h. After cooling to room temperature, MeOH (400 mL) and
water (100 mL) were added, and the solution was filtered. The resi-
due was purified by column chromatography (Wakogel C-300HG,
n-hexane/CHCl3 = 1:1 and then CHCl3) to produce tBuPcTiO in
31 % yield (360 mg); dark-blue powder. 1H NMR (400 MHz,
CDCl3, 25 °C): δ = 1.85–1.92 (m, 36 H, CH3), 8.37–8.43 (m, 4 H,
ArH), 9.40–9.64 (m, 8 H, ArH) ppm. UV/Vis (CHCl3): λmax = 702,
666, 637, 604 nm.[7]
[1,4,8,11,15,18,22,25-Octaethyl-2,3,9,10,16,17,23,24-octakis(methyl-
thio)phthalocyaninato]titanium(IV) Oxide (3-TiO): Compound 3
(130.5 mg, 0.118 mmol) was placed in a glass reactor, and
Ti(OBu)4 (1.0 mL, 2.942 mmol) and DMF (10 mL) were added un-
der Ar. Then the solution was stirred at 130 °C for 2 h, cooled to
room temperature, and poured into brine. Then the green precipi-
tate was filtered. After drying, the product was purified by column
chromatography (Wakogel C-300HG, n-hexane/CHCl3 = 1:1 and
then CHCl3) to produce 3-TiO in 96% yield (131.9 mg); dark-green
powder; m.p. Ͼ300 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ =
1.74 (t, 4JH,H = 7.3 Hz, 24 H, CH3), 2.78 (s, 24 H, SCH3), 4.94 (dq,
4
3
3JH,H = 12.2 Hz, JH,H = 7.3 Hz, 8 H, CH2), 5.02 (dq, JH,H
=
Bis[(tetra-tert-butylphthalocyaninato)titanium(IV)] Benzene-1,2,4,5-
tetrathiolate (7): Compound
12.2 Hz, JH,H = 7.3 Hz, 8 H, CH2) ppm. 13C NMR (101 MHz,
4
5
(28 mg, 0.067 mmol) and
CDCl3, 25 °C): δ = 16.8, 22.3, 25.2, 134.0, 146.8, 147.1, 151.8 ppm.
CsOH·H2O (554 mg, 3.70 mmol) were placed in a glass reactor un-
der Ar. Compound 7 was obtained in 20% yield (26.9 mg) accord-
ing to the procedure described above; dark-blue powder; m.p.
Ͼ300 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 1.67–1.72 (s, 36
H, CH3), 3.60–3.62 (m, 2 H, ArH), 8.18–8.22 (m, 4 H, ArH), 9.22–
9.43 (m, 8 H, ArH) ppm. UV/Vis (CHCl3): λmax = 697 nm. IR
UV/Vis (CHCl3): λmax = 760 nm (logε = 5.15). IR (KBr): ν = 2950,
˜
2917, 2861, 1655, 1300, 1244, 1180, 1094, 1074, 1052, 977,
794 cm–1. MS (FAB): m/z = 1168.3 [M]+. C56H64N8OS8Ti
(1168.24): C 57.51, H 5.52, N 9.58; found C 54.43, H 5.30, N 8.74.
1,2,4,5-Tetrakis[(2-cyanoethyl)thio]benzene (5): 1,2,4,5-Tetrakis-
(methylthio)benzene (4) (682 mg, 2.6 mmol) and lithium (359 mg,
50 mmol) were placed in a glass reactor. THF (5 mL) was added
under Ar, and the solution was cooled to –78 °C. NH3 (about
30 mL) was introduced into the reactor and condensed. The solu-
tion was stirred at this temperature for 2 h and gradually warmed
to room temperature. NH3 was evaporated under a stream of N2
gas. After the evaporation of NH3, deaerated MeOH (10 mL) and
THF (10 mL) were added to the residue, and NH4Cl (3984 mg,
74.5 mmol) was added to the solution. 3-Bromopropionitrile
(1.5 mL, 18 mmol) was added dropwise from a syringe, and the
solution was stirred at room temperature for 12 h. The solvent was
then evaporated, and the product was dissolved in CHCl3/MeOH
= 1:1. The solution was washed with water and dried. After evapo-
ration the product was separated by column chromatography
(Wakogel C-300HG, CHCl3/MeOH = 1:1) to produce 5 in 31%
yield (337 mg); colorless crystals; m.p. 115.1–115.6 °C. 1H NMR
(KBr): ν = 2959, 2363, 1612, 1483, 1395, 1364, 1326, 1256, 1150,
˜
1073, 927, 829, 803, 754 cm–1. MS (FAB): m/z = 1770.60 [M]+.
C102H98N16S4Ti2 (1770.60): C 69.14, H 5.57, N 12.65; found C
68.15, H 5.97, N 11.75.
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Eur. J. Org. Chem. 2008, 5079–5084
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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Received: May 23, 2008
Published Online: September 16, 2008
5084
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 5079–5084