Preparation of phthalocyaninato and porphyrinato titanium (IV) benzenedichalcogenolates

Article abstract of DOI:10.1080/10426507.2010.520280

The reaction of octabutoxyphthalocyaninato titanium (IV) oxide (4) and tetraphenylporphyrinato titanium (IV) oxide (6) with diethylbenzenedithiol (3a)or diethylbenzenediselenol (3b) produced the corresponding titanium (IV) complexes (5) and (7a,b) with titanium-sulfur or titanium-selenium bonds. Optical and electrochemical properties of the products were determined by ultraviolet-visible (UV-Vis) spectroscopy and cyclic voltammetry. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426507.2010.520280

Phosphorus, Sulfur, and Silicon, 186:1234–1237, 2011
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2010.520280
PREPARATION OF PHTHALOCYANINATO
AND PORPHYRINATO TITANIUM (IV)
BENZENEDICHALCOGENOLATES
Takeshi Kimura, Kaori Amano, and Toshiharu Namauo
Center for Instrumental Analysis, Iwate University, Morioka, Iwate, Japan
Abstract The reaction of octabutoxyphthalocyaninato titanium (IV) oxide (4) and tetraphenyl-
porphyrinato titanium (IV) oxide (6) with diethylbenzenedithiol (3a) or diethylbenzenediselenol
(3b) produced the corresponding titanium (IV) complexes (5) and (7a,b) with titanium–sulfur
or titanium–selenium bonds. Optical and electrochemical properties of the products were
determined by ultraviolet-visible (UV-Vis) spectroscopy and cyclic voltammetry.
Keywords Phthalocyanine; porphyrin; S ligand; Se ligand; titanium
INTRODUCTION
Phthalocyanines and related compounds, connecting one or two axial coordinating
groups on the central metal atom, have attracted much attention because of their potential
applications in electrochromic displays, field-effect transistors, nonlinear optical materials,
and dye-sensitized solar cells.1–3 To functionalize these molecules, it is possible to select
central metal atoms and axial ligands. In many phthalocyanine complexes, the deriva-
tives with the titanium (IV) atom can connect two ligands in one face of the Pc-plane.4
As compounds with bidentate ligands, Hanack reported phthalocyaninato titanium (IV)
complexes with titanium–oxygen or titanium–sulfur bonds,5 and Kobayashi synthesized
a mutually perpendicular phthalocyanine pentamer and related derivatives.6 Porphyrinato
titanium (IV) complexes with titanium–oxygen or titanium–sulfur bonds were also de-
scribed.7 To construct new types of phthalocyanine and porphyrin complexes with an axial
bidentate ligand, octabutoxyphthalocyaninato titanium (IV) oxide (4) and tetraphenylpor-
phyrinato titanium (IV) oxide (6) were reacted with 3,6-diethyl-4,5-dibromobenzene-1,2-
dithiol (3a) or 3,6-diethyl-4,5-dibromobenzene-1,2-diselenol (3b). This article reports the
preparation and optical and electrochemical properties of octabutoxyphthalocyaninato tita-
nium (IV) diethyldibromobenzenedithiolates (5) and tetraphenylporphyrinato titanium (IV)
diethyldibromobenzenedichalcogenolates (7a,b).
To generate benzenedithiol (3a) as a bidentate sulfur ligand, bis(cyanoethylthio)-
benzene (2a), which was prepared from benzotrithiole (1a),8 was treated with CsOH in
tetrahydrofuran (THF)/MeOH under Ar (Scheme 1). The reaction mixture was acidified
Received 21 June 2010; accepted 27 August 2010.
Address correspondence to Takeshi Kimura, Center for Instrumental Analysis, Iwate University, Morioka,
Iwate 020-8551, Japan. E-mail: kimura@iwate-u.ac.jp
1234

PHTHALOCYANINE AND PORPHYRIN COMPLEXES
1235
Scheme 1 (i) NaBh4, K2CO3, THF/MeOH; (ii) BrCH2CH2CN; (iii) CsOH, THF/MeOH; (iv) HCl.
with concentrated HCl. The prepared benzenedithiol was transferred to a reactor containing
4 and the solution was stirred for 24 h (Scheme 2). After workup and purification with silica
gel column chromatography and Bio-beads (SX-1, Nippon-Bio-Rad, Tokyo, Japan) column
chromatography, phthalocyanine (5) with benzenedithiolate as the axial ligand was obtained
in 40% yield.9
Scheme 2 (i) 3a, THF/MeOH.
1
In the H NMR spectrum of 5, the signals of the butoxy groups were observed at
δ = 1.20 (t), 1.81 (sext), 2.18 (quint), and 4.63, 4.67 (dt) ppm. These chemical shifts
are located at a slightly upper field compared with those of 4: δ = 1.25 (t), 1.86 (sext),
2.21 (quint), and 4.64, 4.68 (dt) ppm. Signals for the ethyl group of benzenedithiolate
appeared at δ = −0.02 (t, CH3), 1.48 (bq, CH2) ppm, which are a higher magnetic field
than those of 2a: δ = 1.29 (t, CH3) and 3.28 (q, CH2) ppm. These results could indicate
that the benzene ring lies on the phthalocyanine plane and is strongly affected in the
magnetic shielding range of the macrocycle. The 13C NMR spectrum of 5 showed four
signals for the phthalocyanine skeleton, six signals for the ethyl and the butoxy groups, and
three signals for the coordinating benzene ring. Apparently, the phthalocyanine skeleton
of 5 is a C4 symmetric structure in the nuclear magnetic resonance (NMR) timescale at
25◦C, although benzenedithiolate coordinates to the central titanium atom. The fast atom
bombardment–mass spectrometry (FAB-MS) spectrum of 5 showed the corresponding
molecular ion peak at m/z = 1,488.4187 [M+].
The solution of benzenedithiol was then added to 6, and the reaction gave 7a with
benzenedithiolate as the axial ligand in 89% yield, after workup and purification (Scheme
3).10 Compound 7a seems more unstable than 5.
1
In the H NMR spectrum, 7a showed the signals of the phenyl groups and the
porphyrin core at δ = 7.74–7.85 (m, m,p-PhH), 8.16 (dd, o-PhH), 8.25 (dd, o-PhH), 9.05

1236
T. KIMURA ET AL.
Scheme 3 (i) 3a or 3b, THF/MeOH.
(s, PH) ppm. These chemical shifts are situated at a similar magnetic field to those of 6: δ
= 7.73–7.89 (m, m,p-PhH), 8.12 (dd, o-PhH), 8.48 (dd, o-PhH), 9.13 (s, PH) ppm. Signals
for the ethyl group of benzenedithiolate were observed at δ = 0.20 (t, CH3) and 1.64 (q,
CH2) ppm. The FAB-MS spectrum of 7a showed the corresponding molecular ion peak at
m/z = 1014.1 [MH+].
1
The similar treatment of 6 with 3b produced porphyrin (7b) in 91% yield. The H
and 13C NMR were similar to those of 5. However, the signal for the 77Se NMR spectrum
could not be observed at 25◦C. The FAB-MS spectrum of 7b exhibited the molecular ion
peak at m/z = 1,108.0 [MH+].
In the UV spectra measured in CHCl3, the Q band absorption of 5a was observed at
λmax = 702 nm, which is a wider bandwidth than that of 4 (λmax = 701 nm). In contrast,
7a and 7b showed the two split Soret band absorptions at λmax = 399 and 432 nm for 7a
and λmax = 396 and 427 nm for 7b, respectively, although the Soret band of 6 was found at
λmax = 425 nm. The electrochemical properties of 5a, 7a, and 7b were examined by cyclic
voltammetry using Ag/AgNO3 as a reference electrode (measured in CH2Cl2, scan rate:
200 mV/s). The results are summarized in Table I together with the redox potentials of 4
and 6.
Table 1 Redox potentials (vs. Ag/AgNO3)
E1/2 [V]
Compounds 4th Reduction 3rd Reduction 2nd Reduction 1st Reduction 1st Oxidation 2nd Oxidation
4
5a
6
7a
7b
−1.54
−1.39
−1.82
−1.20
−1.34
−1.64
−1.12
−1.03
−1.55a
−1.30
−1.05a
0.44b
0.53
0.91
1.04b
0.96a
0.95b
0.77a
1.15
1.34a
–
−1.29
aIrreversible (Ep/V).
bQuasireversible.

PHTHALOCYANINE AND PORPHYRIN COMPLEXES
1237
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1
9. Green crystals; H NMR (500 MHz, CDCl3) δ = 0.02 (t, J = 6.4 Hz, 6H, CH3), 1.20 (t,
J = 7.4 Hz, 24H, CH3), 1.48 (bq, J = 6.4 Hz, CH2), 1.81 (sext, J = 7.4 Hz, 16H, CH2), 2.18
(quint, J = 7.4 Hz, 16H, CH2), 4.64, 4.68 (dt, J = 8.0, 7.4 Hz, 16H, CH2), 8.77 (bs, 8H, Ar-H);
13C NMR (126 MHz, CDCl3) δ 11.5, 14.1, 19.6, 29.7, 31.6, 69.5, 105.4, 124.31, 130.7, 135.5,
148.5, 150.8, 153.0; high-resolution (HR)-FAB-MS: Anal. Calcd. for C74H90Br2N8O8S2Ti =
1,488.4169, found m/z = 1,488.4187 (M+).
10. 7a: Black green powder: 1H NMR (400 MHz CDCl3) δ = 0.20 (t, J = 7.4 Hz, 6H, CH3), 1.64 (q,
J = 7.4 Hz, 4H, CH2), 7.74–7.85 (m, 12H, m,p-PhH), 8.16 (m, 4H, o-PhH), 8.25 (m, 4H, o-PhH),
9.05 (s, 8H, b); 13C NMR (126 MHz CDCl3) δ = 11.4, 29.6, 123.7, 125.5, 127.1, 127.2, 128.3,
132.6, 133.1, 134.7, 141.2, 148.8, 150.3; HR-FAB-MS: Anal. Calcd. for C54H38Br2N4S248Ti =
1,012.0384. Found: m/z = 1012.0384 (M+); Anal. Calcd. for C54H38Br2N4S2Ti: C, 63.92; H,
1
3.77; N, 5.52%. Found: C, 63.46; H, 4.02; N, 5.15%; 7b: Black green powder: H NMR (400
MHz CDCl3) δ = 0.27 (t, J = 7.3 Hz, 6H, CH3), 1.80 (q, J = 7.3 Hz, 4H, CH2), 7.44–7.86 (m,
12H, m,p-PhH), 8.15 (d, J = 6.72 Hz, 4H, o-PhH), 8.29 (d, J = 6.72 Hz, 4H, o-PhH), 9.05 (s,
8H, b); 13C NMR (126 MHz CDCl3) δ = 11.6, 29.7, 124.2, 125.4, 127.1, 127.2, 128.3, 132.6,
133.0, 134.8, 138.0, 141.1, 149.3, 150.3; FAB-MS m/z = 1,108.0 [MH+].

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