Design of reversible low redox potential systems using five-membered trichalcogenaheterocycles containing heavy chalcogens; sulfur, selenium, and tellurium

Article abstract of DOI:10.1246/bcsj.76.1043

4-Isopropyl-7-methoxy-1,3,2-benzodichalcogenastannoles and 2,2-bis(η⁵-pentamethylcyclopentadienyl)-1,3, 2-benzodichalcogenatitanoles, a synthetic equivalent of unstable ortho-benzenedichalcogenol, were prepared from 2-isopropyl-5-methoxybenzenechalcogenols in moderate yields by ortho-lithiation, chalcogenation, and protection with dichlorodimethylstannane and bis(η⁵-pentamethylcyclopentadienyl)titanocene dichloride, respectively. Some of the solid-state structures of the new-type stannoles and titannoles were confirmed by X-ray crystallographic analyses. Transformation into 4-isopropyl-7-methoxy-1,2,3-benzotrichalcogenoles was successfully carried out, namely by reacting the stannoles or titannoles with electrophiles containing one sulfur or selenium unit. The molecular structures of the new trichalcogenoles were determined by NMR, IR, mass spectra, X-ray crystallographic analyses, and theoretical calculations. In particular, it was elucidated that heavier multi-chalcogen linkages, selenium-selenium and selenium-tellurium bonds in the benzotrichalcogenoles were present in the five-membered ring by multi-nuclear NMR spectra in solution and confirmed by X-ray crystallographic analyses in the solid-state. The redox properties of the trichalcogenoles were studied by cyclic voltammetry. The voltammograms exhibited well-defined reversible one-electron redox couples. New type radical cations were isolated in quantitative yields in the one-electron oxidation of the trichalcogenoles with equimolar amounts of NOPF₆. The structures of the radical cation salts were analyzed by ³¹P-NMR, ESR spectra, elemental analyses, and theoretical calculations. One-electron reduction of the radical cations on treatment with one equivalent of samarium(II) iodide gave the neutral trichalcogenoles quantitatively.

Full text of DOI:10.1246/bcsj.76.1043

ꢀ 2003 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 76, 1043–1054 (2003) 1043
Design of Reversible Low Redox Potential Systems Using Five-Mem-
bered Trichalcogenaheterocycles Containing Heavy Chalcogens; Sulfur,
Selenium, and Tellurium
ꢀ
ꢀ
Noriyoshi Nagahora, Satoshi Ogawa, Satoko Yoshimura, Yasushi Kawai,y and Ryu Sato
Department of Chemical Engineering, Faculty of Engineering, Iwate University, Morioka 020-8551
yInstitute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011
(Received November 18, 2002)
4-Isopropyl-7-methoxy-1,3,2-benzodichalcogenastannoles and 2,2-bis(ꢀ5-pentamethylcyclopentadienyl)-1,3,2-
benzodichalcogenatitanoles, a synthetic equivalent of unstable ortho-benzenedichalcogenol, were prepared from 2-iso-
propyl-5-methoxybenzenechalcogenols in moderate yields by ortho-lithiation, chalcogenation, and protection with di-
chlorodimethylstannane and bis(ꢀ5-pentamethylcyclopentadienyl)titanocene dichloride, respectively. Some of the so-
lid-state structures of the new-type stannoles and titannoles were confirmed by X-ray crystallographic analyses.
Transformation into 4-isopropyl-7-methoxy-1,2,3-benzotrichalcogenoles was successfully carried out, namely by react-
ing the stannoles or titannoles with electrophiles containing one sulfur or selenium unit. The molecular structures of the
new trichalcogenoles were determined by NMR, IR, mass spectra, X-ray crystallographic analyses, and theoretical
calculations. In particular, it was elucidated that heavier multi-chalcogen linkages, selenium-selenium and selenium–
tellurium bonds in the benzotrichalcogenoles were present in the five-membered ring by multi-nuclear NMR spectra
in solution and confirmed by X-ray crystallographic analyses in the solid-state. The redox properties of the trichalco-
genoles were studied by cyclic voltammetry. The voltammograms exhibited well-defined reversible one-electron redox
couples. New type radical cations were isolated in quantitative yields in the one-electron oxidation of the trichalcogen-
oles with equimolar amounts of NOPF6. The structures of the radical cation salts were analyzed by 31P-NMR, ESR
spectra, elemental analyses, and theoretical calculations. One-electron reduction of the radical cations on treatment with
one equivalent of samarium(b) iodide gave the neutral trichalcogenoles quantitatively.
Our study was aimed at the design of a reversible, one-elec-
tron reduction–oxidation (redox) system with a low redox po-
tential using neutral trichalcogenoles incorporating sulfur, se-
lenium, and/or tellurium atoms. In the past, such trichalco-
genoles have received little attention due to their low stability,
as they are known to be readily converted to oligomeric or
polymeric forms.1;2 Recently, we reported a new efficient
method for the synthesis of stable trichalcogenoles incorporat-
ing sulfur and/or selenium atoms fused to a benzene ring.
These trichalcogenoles showed well-defined chemical and
electrochemical redox behavior.3{7 On the other hand, in con-
trast to the sulfur or selenium ring system,1;2;8{11 there is no re-
port for the synthesis of tellurium-containing trichalcogenoles
fused to a benzene ring, while the compounds themselves have
been predicted to have lower redox potentials.12{14 We re-
ported a preliminary communication of a new efficient method
via double-directing ortho-lithiation and stable metallacycles
with bis(ꢀ5-pentamethylcyclopentadienyl)titanium for the
synthesis of trichalcogenoles incorporating tellurium besides
sulfur and selenium atoms in the five-membered ring.15 Here,
we provide full details on the synthesis, structural characteriza-
tion, and redox properties of novel benzotrichalcogenoles con-
taining sulfur, selenium, and/or tellurium atoms, which have
both isopropyl and methoxy groups at the appropriate positions
on the benzene ring to stabilize the five-membered hetero-
cycles. Furthermore, we performed calculations with the den-
sity functional theory to gain understanding of the unusual sta-
bility of the corresponding radical cations with a 7p electron
framework that would have pseudoaromaticity.
Results and Discussion
Synthesis of 1,3,2-Benzodichalcogenastannoles 1a–d and
1,3,2-Benzodichalcogenatitanoles 2a–f.
2,2-Dimethyl-1,-
3,2-benzodichalcogenastannoles 1a–d and 2,2-bis(ꢀ5-penta-
methylcyclopentadienyl)-1,3,2-benzodichalcogenatitanoles 2a
–f, synthetic equivalents of unstable benzene-1,2-dichalcogen-
ols, were synthesized from commercially available 4-isopro-
pylphenol by following the modified methods previously
reported.7 The synthetic routes are shown in Scheme 1.
The substituted bromobenzene, the precursor of dichalcogen-
astannoles 1a–d and titanoles 2a–f, was prepared in an excel-
lent yield by a sequence of methylation, double-bromination,
and selective halogen-metal exchange reactions. Then, a
Grignard reaction and chalcogenation of the obtained bromo-
benzene gave the corresponding thiol and diselenide as iso-
lated products in 70% and 97% yields, respectively.16;17 The
novel sulfur- and/or selenium-containing dichalcogenastan-
noles 1a–d were prepared through ortho-lithiation by the dou-
ble-directing effect of the thiol (or selenol) and methoxy
groups18 followed by chalcogenation18{20 and stannylation21
with dichlorodimethylstannane in moderate yields. Unfortu-
nately, the tellurium-containing dichalcogenastannoles were

1044 Bull. Chem. Soc. Jpn., 76, No. 5 (2003)
Five-Membered Trichalcogenaheterocycles
Scheme 1. Reagents and conditions:ffi. MeI, K2CO3, acetone, reflux;ffl. Br2, Fe, CCl4, room temperature; ƒ. (a) BuLi, Et2O, room
temperature, (b) H3Oþ; Ð. (a) Mg, THF, (b) S8 or Se, (c) H3Oþ;ð. (a) BuLi, TMEDA, (b) S8 or Se, (c) Me2SnCl2 (1a; 53%, 1b;
23%); Þ. (a) LiAlH4, THF, (b) BuLi, TMEDA, (c) S8 or Se, (d) Me2SnCl2 (1c; 28%, 1d; 21%); þ. (a) BuLi, TMEDA, (b) S8, Se,
ꢀ
ꢀ
or Te, (c) Cp 2TiCl2 (2a; 44%, 2b; 70%, 2c; 55%); ¼. (a) LiAlH4, THF, (b) BuLi, TMEDA, (c) S8, Se, or Te, (d) Cp 2TiCl2 (2d;
28%, 2e; 41%, 2f; 40%).
ꢁ
Scheme 2. Reagents and conditions:ffi. SOCl2, THF, 0 C (3a; 93%, 3b; quant., 3c; 99%, 3d; quant.);ffl. NaI, HClO4, THF, H2O,
room temperature (4a; 95%, 4b; 99%, 4c; 96%, 4d; 99%); ƒ. (a) SeOCl2, THF, ꢂ78 ꢁC, (b) CF3SO3SiMe3, THF, ꢂ78 ꢁC,
ꢁ
(c) SmI2, THF, ꢂ78 C (4e; 82%, 4f; 82%, 4g; 85%, 4h; 92%).
not synthesized due to their tendency to be oxidized and form
an oligomeric mixture without the metal protection. The di-
chalcogenatitanoles 2a–f were also prepared by the ortho-
lithiation and chalcogenation of the thiol and diselenide fol-
lowed by titanylation22{26 with bis(ꢀ5-pentamethylcyclopenta-
ꢀ
dienyl)titanium dichloride (Cp 2TiCl2) in moderate yields.
Synthesis of 1,2,3-Benzotrichalcogenoles 4a–l. Transfor-
mation into trichalcogenoles 4a–l was successfully carried out
by following our original method,7 namely by the reaction of
dichalcogenastannoles 1a–d and titanoles 2a–f with electro-
philes containing one sulfur or selenium unit such as a thionyl
chloride or seleninyl chloride. As shown in Scheme 2, treat-
Scheme 3. Reagents and conditions: ffi. SCl2 or SeOCl2,
ment of dichalcogenastannoles 1a–d with thionyl chloride
THF, room temperature (4i; 95%, 4j; 29%, 4k; 92%, 4l;
and sodium iodide/perchloric acid afforded novel trichalcogen-
oles 4a–d having a sulfur atom at the 2-position in excellent
23%).
fonate, and samarium(b) iodide gave novel trichalcogenoles
4e–h having a selenium atom at the 2-position in excellent
yields. In the case of tellurium-containing benzotrichalcogen-
yields via the corresponding trichalcogenole 2-oxides 3a–d.
Furthermore, sequential treatment of dichalcogenastannoles
1a–d with selenyl chloride, trimethylsilyl trifluoromethanesul-

N. Nagahora et al.
Bull. Chem. Soc. Jpn., 76, No. 5 (2003) 1045
Table 1. Multi-Nuclear NMR Data for 1,3,2-Benzodichalcogenastannoles 1a–d
Compound
119Sn NMR ꢁ/ppm
77Se NMR ꢁ/ppm
J117Sn-77Se; J119Sn-77Se/Hz
1a
1b
1c
1d
187.8
134.1
135.3
75.6
—
—
17.0
31.0
82.6
72.8
1052, 1100
1091, 1141
1059, 1109
1020, 1067
Fig. 1. 77Se NMR (left) and 119Sn NMR (right) spectra of 1,3,2-benzodiselenastannole 1d.
(Fig. 2), the 125Te-NMR spectrum showed a signal with a
77Se satellite, which could be assigned to the tellurium atom
at the 3-position bound to a selenium atom. Furthermore,
the 77Se-NMR spectrum showed two resonances at 141.7
and 555.2 ppm. The former, with both 77Se and 125Te satel-
lites, indicated the existence of a selenium atom at the 2-posi-
tion bound to both selenium and tellurium atoms. The latter,
with the 77Se satellite, was assigned to the selenium atom at
the 1-position bound to a selenium atom. Consequently, these
multi-nuclear NMR data clearly indicate that selenium–tin
bonding in benzodichalcogenastannoles, and selenium–sele-
nium and selenium-tellurium bonding in benzotrichalcogen-
oles is present in their five-membered rings.
X-ray Crystallographic Analysis. The crystal structures
of benzodithiastannole 1a and benzothiaselenatitanole 2b were
confirmed by X-ray crystallographic analyses (Figs. 3 and 4,
Tables 4 and 5). The five-membered ring of benzodithiastan-
nole 1a was almost coplanar with the benzene ring. The tin
atom of benzodithiastannole 1a has a tetrahedral structure,
the bond angle of S(1)–Sn(2)–S(3) (89.62(6)ꢁ) was the most
narrow around the tin atom. The sulfur–tin bond lengths are
similar to those of reported crystal structures.27{30 Two chal-
cogen atoms of benzothiaselenatitanole 2b were nearly copla-
nar with the benzene ring, while the titanium atom lay out of
this plane (Ch–Ti–Ch–C torsion angles are ca. 35ꢁ). The
stable five-membered dichalcogenametallacycles, a synthetic
equivalent of unstable benzene-1,2-dichalcogenols, were read-
ily prepared by protection with dichlorodimethylstannane or
the corresponding titanocene dichloride.
Table 2. Multi-Nuclear NMR Chemical Shifts for 1,3,2-
Benzodichalcogenatitanoles 2a–f
Compound
77Se NMR ꢁ/ppm
125Te NMR ꢁ/ppm
2a
2b
2c
2d
2e
2f
—
772.7
—
—
—
944.8
—
—
775.0
841.1, 844.0
1003.2
1055.0
oles 4i–l (Scheme 3), introduction of a sulfur or selenium atom
at the 2-position was performed by the reactions of benzodi-
chalcogenatitanoles 2c,f with sulfur dichloride or seleninyl
chloride, respectively.
Multi-Nuclear NMR Studies. Selenium has one, tin has
two, and tellurium has one NMR-active spin 1/2 nuclei of re-
latively high natural abundance: 77Se, 117Sn, 119Sn, and 125Te.
Therefore, the 77Se- and 119Sn-NMR spectra provided perti-
nent information on the new five-membered framework of di-
chalcogenastannoles 1a–d (Table 1). With respect to benzodi-
selenastannole 1d, the 77Se-NMR spectrum (Fig. 1) showed
two signals with 117Sn and 119Sn satellites, which were in ac-
cordance with the existence of two selenium atoms neighbor-
ing a tin atom in the five-membered ring. The 119Sn-NMR
spectra also showed 77Se satellites. Similarly, the 77Se- and
125Te-NMR spectra also provided pertinent information on
the new five-membered framework of dichalcogenatitanoles
2a–f (Table 2). The 77Se- and 125Te-NMR spectra of trichal-
cogenoles 4a–l indicated that each five-membered ring has the
selenium atom(s) and a tellurium atom at the appropriate
positions. The obtained spectral data are shown in Table 3.
The spectra of thiadiselenole 4f,g consisted of two equally
with 77Se satellites. The spectrum of triselenole 4h consisted
of three equally intense signals with 77Se satellites. The data
could be facilely assigned to be the number of selenium–sele-
nium bonds in the ring. In the case of diselenatellurole 4l
Fortunately, upon recrystallization, benzothiaselenatellurole
4j and benzodiselenatellurole 4l precipitated from the chloro-
form solution as brown and purple prisms, respectively. These
crystal structures were confirmed by X-ray crystallographic
analyses (Figs. 5 and 6, Tables 6 and 7). Two chalcogen
atoms at the 1- and 3-positions were almost coplanar with
the benzene ring, while the chalcogen atoms at the 2-position
lay out of this plane (Ch–Ch–Ch–C torsion angles are ca. 40ꢁ).

1046 Bull. Chem. Soc. Jpn., 76, No. 5 (2003)
Five-Membered Trichalcogenaheterocycles
Table 3. Multi-Nuclear NMR Data for 1,2,3-Benzotrichalcogenoles 4a–l
Compound
77Se NMR ꢁ/ppm
125Te NMR ꢁ/ppm
4a
4b
4c
4d
4e
4f
—
633.6
624.1
655.9, 645.4
701.3
568.9, 507.6 (JSe-Se ¼ 311 Hz)
581.8, 501.9 (JSe-Se ¼ 279 Hz)
543.0 (JSe-Se ¼ 292 Hz),
533.6 (JSe-Se ¼ 264 Hz),
436.7 (JSe-Se ¼ 292, 264 Hz)
—
295.3 (JSe-Te ¼ 878 Hz)
657.1
555.2 (JSe-Se ¼ 260 Hz),
141.7 (JSe-Se ¼ 260, JSe-Te ¼ 846 Hz)
—
—
—
—
—
—
—
4g
4h
—
4i
4j
4k
4l
1346.7
1095.2 (JTe-Se ¼ 878 Hz)
1383.9
1153.1 (JTe-Se ¼ 846 Hz)
Fig. 2. 77Se NMR (left and center) and 125Te NMR (right)
spectra of 1,2,3-benzodiselenatellurole 4l.
Fig. 4. ORTEP drawing of 2b (hydrogen atoms are omitted
for clarity). Thermal ellipsoids are drawn at the 50%
probability level.
Table 4. Crystallographic Data for 1,3,2-Benzodithiastan-
nole 1a and 1,3,2-Benzothiaselenatitanole 2b
1a
2b
Empirical formula
Formula weight
Crystal system
Space group
C12H18OS2Sn
361.08
monoclinic
P21=a
11.5648(7)
9.7060(9)
13.5324(8)
103.080(5)
1479.6(2)
4
C30H42OSSeTi
577.58
orthorhombic
P212121
10.109(4)
14.855(4)
16.680(4)
—
2805(1)
4
1.367
ꢀ
a/A
ꢀ
b/A
ꢀ
c/A
ꢂ/deg
ꢀ 3
V/A
Z
Fig. 3. ORTEP drawing of 1a. Thermal ellipsoids are
drawn at the 50% probability level.
Dcalc/g cmꢂ3
1.621
ꢀ
ꢃ (Cu Kꢄ)/A
1.54178
3147
2997
0.051; 0.081
0.85
1.54178
5630
2852
0.055; 0.085
0.76
Total reflections
Independent reflections
Residuals: R; Rw
GOF
The Ch(1)–Se(2)–Te(3)–C(8) torsion angles of 4j and 4l were
35.98(7) and 37.33(9)ꢁ, respectively, which were smaller than
those of the benzotrichalcogenoles previously reported.1;5{7
The Te(3)–Se(2)–Ch(1)–C(9) torsion angles of 4j and 4l were
ꢂ42:83ð9Þ and ꢂ42:1ð1Þꢁ, respectively. Thus, we investigated
these distorted structures with the aid of density functional the-
ory calculations using the Gaussian 98 program.31 The elec-
tronic structures of benzotrichalcogenoles bearing isopropyl
and methoxy groups on the benzene ring were optimized and
characterized by frequency computations and a wave function
stability check at the B3LYP/3-21G level. Torsion angles of
ꢀ

N. Nagahora et al.
Bull. Chem. Soc. Jpn., 76, No. 5 (2003) 1047
ꢁ
ꢁ
ꢀ
Table 5. Selected Bond Lengths (A), Bond Angles ( ), and Torsion Angles ( )
Dithiastannole 1a
Bond lengths
Thiaselenatitanole 2b
Bond lengths
S(1)–Sn(2)
S(3)–Sn(2)
S(1)–C(9)
S(3)–C(8)
2.413(2)
2.407(2)
1.772(7)
1.761(6)
S(1)–Ti(2)
Se(3)–Ti(2)
S(1)–C(8)
Se(3)–C(9)
2.428(3)
2.553(2)
1.77(1)
1.89(1)
Bond angles
Bond angles
S(1)–Sn(2)–S(3)
C(15)–Sn(2)–C(16)
Sn(2)–S(1)–C(9)
Sn(2)–S(3)–C(8)
89.62(6)
111.5(4)
100.1(2)
101.2(2)
S(1)–Ti(2)–Se(3)
Ti(2)–S(1)–C(8)
Ti(2)–Se(3)–C(9)
81.80(9)
103.4(4)
94.9(4)
Torsion angles
Torsion angles
S(1)–Sn(2)–S(3)–C(8)
S(3)–Sn(2)–S(1)–C(9)
S(1)–C(9)–C(8)–S(3)
5.1(2)
ꢂ6:0ð2Þ
ꢂ2:9ð8Þ
S(1)–Ti(2)–Se(3)–C(9)
Se(3)–Ti(2)–S(1)–C(8)
Ti(2)–S(1)–C(8)–C(9)
Ti(2)–Se(3)–C(9)–C(8)
Se(3)–C(9)–C(8)–S(1)
ꢂ34:2ð4Þ
36.0(4)
ꢂ28:5ð9Þ
32.3(10)
ꢂ4ð1Þ
Values in parentheses are the greater of the range or the estimated S. D.
Fig. 5. ORTEP drawing (top) and side view (bottom) of 4j.
Thermal ellipsoids are drawn at the 50% probability level.
the optimized structures are summarized in Table 8, and are
comparable with those of the solid-state structures (Table 7)
determined by X-ray diffraction. Introduction of a heavier
chalcogen atom at the 1- and 3-positions spread out the torsion
angles of the trichalcogenole ring. The energies calculated for
the distorted form of the five-membered trichalcogenole rings
are lower than for the planar form. Consequently, the distorted
geometry of the five-membered trichalcogenole rings implies
the presence of lone pair-lone pair repulsion among the three
divalent chalcogen atoms.
Fig. 6. ORTEP drawing (top) and side view (bottom) of 4l.
Thermal ellipsoids are drawn at the 50% probability level.
since little is known about the electrochemical behavior of
polychalcogenide ring systems. Cyclic voltammograms were
measured in acetonitrile (MeCN) containing 0.1 M (1 M = 1
mol dmꢂ3) Bu4NClO4 as a supporting electrolyte using a
glassy-carbon working electrode and a Ag/0.01 M AgNO3
couple in the electrolyte solution as a reference electrode at
ꢁ
Electrochemical Studies. The solution redox properties of
the trichalcogenoles 4a–l were studied by cyclic voltammetry,
20 C under argon atmosphere. Interestingly, the typical vol-
tammograms of trithiole 4a and triselenole 4h (Fig. 7) specify

1048 Bull. Chem. Soc. Jpn., 76, No. 5 (2003)
Five-Membered Trichalcogenaheterocycles
Table 6. Crystallographic Data for 1,2,3-Benzothiaselena-
tellurole 4j and 1,2,3-Benzodiselenatellurole 4l
4j
4l
Empirical formula
Formula weight
Crystal system
Space group
C10H12OSSeTe
386.82
monoclinic
P21=a
C10H12OSe2Te
433.72
monoclinic
P21=a
ꢀ
a/A
7.373(5)
16.563(3)
10.046(2)
94.66(2)
1222.7(5)
4
7.389(3)
16.581(3)
10.165(3)
93.14(3)
1243.6(6)
4
ꢀ
b/A
ꢀ
c/A
ꢂ/deg
ꢀ 3
V/A
Z
Dcalc/g cmꢂ3
2.101
2.316
ꢀ
ꢃ (Mo Kꢄ)/A
Total reflections
Independent reflections
Residuals: R; Rw
GOF
0.71069
2420
2240
0.021; 0.037
0.94
0.71069
2467
2282
0.033; 0.039
1.87
Fig. 7. Cyclic voltammograms of 4a (top) and 4h (bottom)
in CH3CN (0.1 M Bu4NClO4); scan rate, 100 mV sꢂ1
.
ꢁ
ꢁ
ꢀ
Table 7. Selected Bond Lengths (A), Bond Angles ( ), and Torsion Angles ( )
Thiaselenatellurole 4j
Bond lengths
S(1)–Se(2)
Se(2)–Te(3)
Te(3)–C(8)
S(1)–C(9)
Diselenatellurole 4l
Bond lengths
Se(1)–Se(2)
Se(2)–Te(3)
Te(3)–C(8)
Se(1)–C(9)
2.2218(9)
2.5306(5)
2.101(3)
1.779(3)
2.3500(6)
2.5233(6)
2.113(3)
1.929(3)
Bond angles
Bond angles
Te(3)–Se(2)–S(1)
Se(2)–S(1)–C(9)
Se(2)–Te(3)–C(8)
S(1)–C(9)–C(8)
Te(3)–C(8)–C(9)
90.54(3)
99.68(10)
86.16(8)
119.6(2)
121.2(2)
Te(3)–Se(2)–Se(1)
Se(2)–Se(1)–C(9)
Se(2)–Te(3)–C(8)
Se(1)–C(9)–C(8)
Te(3)–C(8)–C(9)
90.52(3)
96.1(1)
88.43(9)
119.4(3)
122.2(3)
Torsion angles
Torsion angles
Te(3)–Se(2)–S(1)–C(9)
S(1)–Se(2)–Te(3)–C(8)
Se(2)–S(1)–C(9)–C(8)
Se(2)–Te(3)–C(8)–C(9)
ꢂ42:83ð9Þ
35:98ð7Þ
36:8ð2Þ
Te(3)–Se(2)–Se(1)–C(9)
Se(1)–Se(2)–Te(3)–C(8)
Se(2)–Se(1)–C(9)–C(8)
Se(2)–Te(3)–C(8)–C(9)
ꢂ42:1ð1Þ
37.33(9)
36.1(3)
ꢂ27:1ð3Þ
ꢂ25:8ð2Þ
Values in parentheses are the greater of the range or the estimatied S. D.
Table 8. Calculated Torsion Angles (ꢁ) of 1,2,3-Benzotrichalcogenoles 4a–l
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
Ch(3)–Ch(2)–Ch(1)–C(9) ꢂ39:9 ꢂ41:5 ꢂ39:8 ꢂ42:0 ꢂ39:0 ꢂ40:7 ꢂ39:0 ꢂ41:3 ꢂ41:8 ꢂ41:5 ꢂ42:0 ꢂ41:9
Ch(1)–Ch(2)–Ch(3)–C(8)
Ch(2)–Ch(1)–C(9)–C(8)
Ch(2)–Ch(3)–C(8)–C(9)
38.7
ꢂ27:7 ꢂ25:7 ꢂ30:4 ꢂ28:8 ꢂ28:6 ꢂ26:6 ꢂ31:0 ꢂ29:3 ꢂ22:0 ꢂ23:5 ꢂ24:4 ꢂ25:7
30.2 32.8 29.5 32.5 31.4 33.9 30.8 33.7 35.3 36.2 35.0 36.0
37.5
41.0
40.6
37.8
36.7
40.3
39.6
34.4
34.0
36.9
36.6
ꢀ
Optimized structures were obtained B3LYP/3-21G level.

N. Nagahora et al.
Bull. Chem. Soc. Jpn., 76, No. 5 (2003) 1049
ꢂ
ꢁ
ꢂ
ꢁ
ꢂ
ꢁ
Fig. 8. ESR spectra of 4aꢃþPF6 at ꢂ35 C (left), 4dꢃþPF6 at ꢂ35 C (center), and 4hꢃþPF6 at 8 C in CH3CN.
Table 10. g-Values and Hyperfine Coupling Costants (hfc)
Table 9. Redox Potentials of 1,2,3-Benzotrichalcogenoles 4a–l
of 1,2,3-Benzotrichalcogenolium Hexafluorophosphates
Compound
Epa/V
Epc/V
E1=2/V
Compound
ꢂ
4dꢃþPF6ꢂ
4hꢃþPF6
g-Value
hfc/mT
4a
4b
4c
4d
4e
4f
4g
4h
4i
þ0:76
þ0:71
þ0:69
þ0:66
þ0:60
þ0:56
þ0:58
þ0:53
þ0:44
þ0:39
þ0:39
þ0:36
þ0:65
þ0:63
þ0:61
þ0:58
þ0:52
þ0:50
þ0:48
þ0:46
—
þ0:71
þ0:67
þ0:65
þ0:62
þ0:56
þ0:53
þ0:53
þ0:50
—
4aꢃþPF6ꢂ
2.013
2.025
2.061
0.110, 0.072
—
—
4j
4k
4l
—
þ0:25
—
þ0:32
þ0:26
þ0:31
Concentration, 2 mM sample MeCN/0.1 M Bu4NClO4; work-
ing electrode, glassy-carbon; reference electrode, Ag/0.01 M
AgNO3; counter electrode, Pt; scan rate, 100 mV sꢂ1
Fig. 9. Optimized structure of 4aꢃþ
.
results of the reversibility observed in cyclic voltammetry de-
scribed above clearly indicate that the trichalcogenoles provide
stable radical cations even at room temperature. Several novel
trichalcogenolium radical cation salts were readily isolated in
the one-electron oxidation of trichalcogenoles with equimolar
amount of NOPF6 in ether–MeCN (Scheme 4). The dark-blue
salts were stable at ambient temperature, and the structures of
radical ions in solution were analyzed by 31P-NMR and EPR
spectroscopies. Each salt dissolved readily in MeCN to give
a red-purple solution. The ESR spectra in the degassed MeCN
solution showed the presence of a double of doublet peak with
the hyperfine coupling constants aH of 0.110 and 0.0ꢂ72 mT
(4aꢃþPF6ꢂ), and a broad singlet peak (4dꢃþPF6 and
4hꢃþPF6ꢂ) attributable to trichalcogenolium radical cations
(Fig. 8, Table 10). The aH splitting due to two unequivalent
protons of the fused-benzene ring (4aꢃþPF6ꢂ) suggests a par-
tially spin-delocalized system over the benzene ring. This spin
delocalization could be elucidated by the theoretical
calculations. The electronic structure of the trithiolium radical
cation was optimized and characterized by frequency compu-
tations and wave function stability checks at the UB3LYP/6-
311+G(d,p) level. The optimized structure of the trithiolium
radical cation (Fig. 9) was completely coplanar with the benz-
Scheme 4. Reagents and conditions:ffi. NOPF6 (1 equimol.
amt.), CH3CN–Et2O, ꢂ78 ꢁC (4a; 94%, 4d; 98%, 4h;
quant.); ffl. SmI2 (1 equimol. amt.), THF, ꢂ78 ꢁC
(4aꢃþPF6ꢂ; quant., 4dꢃþPF6ꢂ; 98%, 4hꢃþPF6ꢂ; quant.).
a
well-defined reversible one-electron redox couple at
E1=2 ¼ þ0:71 and þ0:50 V, respectively. Moreover, most
of the trichalcogenoles exhibited one reversible one-electron
step with a low oxidation potential except for trichalcogenoles
4i,j (Table 9). The peak potentials of the first oxidation peak
(Ep) and half-wave (E1=2) have been found to be governed by
the atom present at the 2-position of the chalcogen ring, which
is in good agreement with those of the trichalcogenoles pre-
viously reported.7 It is a well-known fact that increasing sele-
nium and/or tellurium substitution normally leads to the low-
ering of the oxidation potential of a donor.12{14;32;33 As
expected, with increasing selenium and/or tellurium substitu-
tion, lowered oxidation peaks were obtained. Thus, the present
results suggest that the desired stable one-electron oxidized
species, benzotrichalcogenolium radical cations, can be gener-
ated during the electrochemical or chemical oxidation.
One-Electron Redox Reactions and ESR Studies. The

1050 Bull. Chem. Soc. Jpn., 76, No. 5 (2003)
Five-Membered Trichalcogenaheterocycles
Table 11. Calculated Nucleus-Independent Chemical Shift
(NICS) Values (ppm) at the Individual Ring Center of
1,2,3-Benzotrichalcogenoles and Corresponding Radical
Cations
analyses were carried out by a Yanagimoto MT-5 CHN corder.
High-resolution mass spectra were obtained using a JEOL JMS-
SX 102 spectrometer. Cyclic voltammetry was carried out with
a Cypress Systems CS-1090 galvanostat/potentiostat. A three-
electrode system was used, consisting of a glassy-carbon working
electrode, a platinum wire auxiliary electrode and a Ag/0.01 M
AgNO3 reference electrode. The measurements were carried
out in MeCN solution containing 0.1 M Bu4NClO4 as a supporting
electrolyte with scan rates 50–500 mV sꢂ1 under an Ar atmo-
NICS valuebÞ
CompoundaÞ
Six-membered ring
Five-membered ring
4a (C1)
4aꢃþ (Cs)
4h (C1)
ꢂ8:3
—
ꢂ10:3 (ꢂ6:0)cÞ
ꢂ9:4 (ꢂ9:5)cÞ
ꢂ7:9
ꢁ
sphere at 20 C. ESR data were taken in a JEOL RE2X spectro-
—
meter working in the X-band with DPPH and Mn2þ on MgO as
field markers. All solvents used in the reactions were purified
by the general methods. All reactions were carried out under a ni-
trogen atmosphere, but the work-up was performed in air. Silica-
gel column chromatography was performed with a Wakogel C-
200.
4hꢃþ (Cs)
ꢂ9:8 (ꢂ9:9)cÞ
a) The point groups are described in parentheses. b) GIAO-
ꢂ8:6 (ꢂ5:0)cÞ
B3LYP/6-311+G(d,p)//B3LYP/6-311+G(d.p) computed
NICS values were obtained at the central point in the plane.
c) NICS(1) values (ppm) are given in parentheses.
Computational Methods. All calculations were carried out
with Gaussian 98 program. The geometries were optimized with
the restricted Becke hybrid (B3LYP) methods for the neutral com-
pounds, and unrestricted B3LYP methods for the radical cations.
The zero-point vibrational energies were computed at the same le-
vel and were not scaled. All stationary points were characterized
by harmonic analysis. Nucleus-independent chemical shift
(NICS) values were evaluated by using the gauge invariant atomic
orbital (GIAO) approach and were obtained at a central point in
the plane of the rings, and NICS(1) refers to calculations at 1.0
ene ring (Cs symmetry), which also predicted the p-systems
consisted of the trithiolium and benzene ring. The spin distri-
bution of the trithiolium radical cation revealed that the calcu-
lated aH values for the proton of the benzene ring were 0.149
and 0.058 mT, respectively, being in fair agreement with the
observed values. The spin densities were mostly present in
the five-membered trithiolium ring with the 7p electron
system. Furthermore, this tendency of the spin delocalization
is also the case for all trichalcogenolium frameworks. In addi-
tion, in order to evaluate computationally the ring current of
these heterocyclic radical cations, nucleus-independent chemi-
cal shift34 (NICS) values, which are known as an effective and
simple probe of individual rings in polycyclic systems, were
calculated with the density functional theory. The calculated
NICS values of individual rings in trichalcogenoles and their
radical cations are shown in Table 11. The NICS(1) and
NICS(0) values for the six-membered ring of trichalcogen-
olium radical cations are close in magnitude to that for the
benzene ring of the corresponding neutral trichalcogenole, pro-
viding evidence for the existence of a diatropic ring current.
However, the NICS(1) values for the five-membered ring are
even smaller in magnitude than those of the six-membered
ring. These data suggest the radical cations with a 7p electron
framework have pseudoaromaticity.
ꢀ
A above the ring.
General Procedure for the Synthesis of 4-Isopropyl-7-meth-
Butyllithium
oxy-1,3,2-benzodichalcogenastannoles 1a–d.
(42.3 mL of a 1.54 M solution in hexane, 65.2 mmol) was added
to a stirred solution of 2-isopropyl-5-methoxybenzenethiol (2.93
g, 16.1 mmol) in N,N,N0,N0-tetramethylethylenediamine (9.8
mL, 65.2 mmol) at 0 ꢁC. After 2 h at room temperature, elemental
sulfur (2.09 g, 65.2 mmol) was added at 0 ꢁC, and the reaction
mixture was stirred for 24 h at room temperature. The hexane
was removed in vacuo and replaced with 10 mL of THF. The re-
action mixture was treated with sodium borohydride (619 mg,
ꢁ
16.3 mmol) at 0 C, and was stirred in reflux for 6 h. Then, the
solution was poured into water. The solution was neutralized with
diluted hydrochloric acid solution, treated with dichlorodimethyl-
stannane (4.30 g, 19.6 mmol), and stirred for 0.5 h at room
temperature. The mixture was extracted with dichloromethane.
The organic layer was dried (MgSO4), filtered, and concentrated
in vacuo. Purification of the mixture by column chromatography
on silica gel with chloroform as the eluent gave 3.10 g (8.58
mmol, 53%) of 1a as colorless crystals: mp 201.0–202.0 ꢁC;
1H NMR (400 MHz) ꢁ 0.98 (s, 6H, Sn(CH3)2), 1.25 (d, J ¼ 6:8
Hz, 6H, CH(CH3)2), 3.50 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2),
3.88 (s, 3H, OCH3), 6.61 (d, J ¼ 8:4 Hz, 1H, ArH), 6.96 (d, J ¼
8:4 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 2.3, 23.2, 33.4, 56.1,
107.0, 121.8, 127.0, 139.0, 140.9, 156.2; 119Sn NMR (149 MHz)
ꢁ 187.7; IR (KBr) 2954, 1573, 1462, 1425, 1276, 1254, 1048,
791, 544 cmꢂ1; MS (70 eV) m=z 362 (Mþ); Anal. Calcd for
C12H18OS2Sn: C, 39.91; H, 5.02%. Found: C, 39.72; H, 5.01%.
7-Isopropyl-4-methoxy-2,2-dimethyl-1,3,2-benzothiaselena-
Interestingly, the radical cation salts undergo one-electron
reduction to give trichalcogenoles quantitatively on treatment
with samarium(b) iodide (Scheme 4). Thus, the facile inter-
conversion between trichalcogenoles and their radical cations
in the redox reactions is ascribed to the destabilization of the
distorted neutral trichalcogenide framework by the lone pair-
lone pair repulsion and the unusual stabilization of the oxi-
dized radical cation by the 7p electron framework.
Experimental
General. Melting and decomposition points were determined
on a Mel-Temp capillary tube apparatus and are uncorrected. 1H
(400 MHz) and 13C (101 MHz) NMR spectra were measured on a
Bruker AC-400 spectrometer using CDCl3 as a solvent with
Me4Si as the internal standard. 31P (162 MHz), 77Se (76 MHz),
119Sn (149 MHz), and 125Te (126 MHz) NMR spectra used
H3PO4, Me2Se, Me4Sn, and Me2Te as the external standard,
respectively. IR spectra were recorded on a JASCO FT-7300
spectrometer. Mass spectra were determined on a Hitachi M-
2000 spectrometer operating at 70 eV in the EI mode. Elemental
ꢁ
1
stannole (1b). Colorless crystals; mp 191.5–192.5 C; H NMR
(400 MHz) ꢁ 1.01 (s, 6H, Sn(CH3)2), 1.25 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 3.56 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.87 (s,
3H, OCH3), 6.59 (d, J ¼ 8:4 Hz, 1H, ArH), 7.02 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 1.8, 23.2, 33.9, 56.2,
107.0, 122.9, 124.3, 141.2, 141.5, 156.7; 77Se NMR (76 MHz) ꢁ
17.0 (JSe-117Sn ¼ 1052, JSe-119Sn ¼ 1100 Hz); 119Sn NMR (149

N. Nagahora et al.
Bull. Chem. Soc. Jpn., 76, No. 5 (2003) 1051
Hz) ꢁ 134.1 (JSn-77Se ¼ 1100 Hz); IR (KBr) 2956, 1463, 1423,
1275, 1254, 1047, 793 cmꢂ1; MS (70 eV) m=z 408 (Mþ); Anal.
Calcd for C12H18OSSeSn: C, 35.33; H, 4.45%. Found: C, 35.20;
H, 4.55%.
7-Isopropyl-4-methoxy-2,2-bis(pentamethylcyclopentadien-
yl)-1,3,2-benzothiatelluratitanole (2c). Deep green crystals; mp
ꢁ
1
171.0 C (decomp.); H NMR (400 MHz) ꢁ 1.15 (d, J ¼ 6:9 Hz,
6H, CH(CH3)2), 1.96 (s, 30H, CH3), 3.54 (sept, J ¼ 6:9 Hz, 1H,
CH(CH3)2), 3.85 (s, 3H, OCH3), 6.61 (d, J ¼ 8:2 Hz, 1H, ArH),
7.00 (d, J ¼ 8:2 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 13.4,
23.4, 32.2, 56.0, 104.6, 122.1, 123.5, 125.1, 141.8, 157.7, 158.4;
125Te NMR (126 MHz) ꢁ 944.8; IR (KBr) 2904, 1418, 1377,
1251, 1177, 806 cmꢂ1; MS (70 eV) m=z 628 (Mþ); Anal. Calcd
for C30H42OSTeTi: C, 57.54; H, 6.76%. Found: C, 57.24; H,
6.67%.
4-Isopropyl-7-methoxy-2,2-bis(pentamethylcyclopentadien-
yl)-1,3,2-benzothiaselenatitanole (2d). Deep green crystals; mp
206.5–207.0 ꢁC (decomp.); 1H NMR (400 MHz) ꢁ 1.22 (d,
J ¼ 6:9 Hz, 6H, CH(CH3)2), 1.90 (s, 30H, CH3), 3.71 (sept, J ¼
6:9 Hz, 1H, CH(CH3)2), 3.85 (s, 3H, OCH3), 6.64 (d, J ¼ 8:3 Hz,
1H, ArH), 6.99 (d, J ¼ 8:3 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
12.6, 23.8, 33.4, 55.7, 105.5, 120.4, 123.7, 142.0, 143.3, 151.4,
155.6; 77Se NMR (76 MHz) ꢁ 775.0; IR (KBr) 2900, 1554,
1420, 1253, 1038, 799 cmꢂ1; MS (70 eV) m=z 578 (Mþ); Anal.
Calcd for C30H42OSSeTi: C, 62.39; H, 7.33%. Found: C, 62.05;
H, 7.50%.
4-Isopropyl-7-methoxy-2,2-bis(pentamethylcyclopentadien-
yl)-1,3,2-benzodiselenatitanole (2e). Deep green crystals; mp
196.5–197.0 ꢁC (decomp.); 1H NMR (400 MHz) ꢁ 1.21 (d,
J ¼ 6:9 Hz, 6H, CH(CH3)2), 1.93 (s, 30H, CH3), 3.70 (sept, J ¼
6:9 Hz, 1H, CH(CH3)2), 3.86 (s, 3H, OCH3), 6.67 (d, J ¼ 8:3 Hz,
1H, ArH), 7.03 (d, J ¼ 8:3 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
12.8, 23.8, 34.0, 55.8, 105.5, 121.2, 123.8, 139.5, 142.6, 152.7,
156.3; 77Se NMR (76 MHz) ꢁ 841.1, 844.0; IR (KBr) 2902,
1449, 1420, 1378, 1253, 1040 cmꢂ1; MS (70 eV) m=z 626
(Mþ); Anal. Calcd for C30H42OSe2Ti: C, 57.70; H, 6.78%. Found:
C, 57.32; H, 6.91%.
4-Isopropyl-7-methoxy-2,2-dimethyl-1,3,2-benzothiaselena-
ꢁ
1
stannole (1c). Colorless crystals; mp 217.0–218.5 C; H NMR
(400 MHz) ꢁ 1.02 (s, 6H, Sn(CH3)2), 1.26 (d, J ¼ 6:7 Hz, 6H,
CH(CH3)2), 3.38 (sept, J ¼ 6:7 Hz, 1H, CH(CH3)2), 3.88 (s,
3H, OCH3), 6.67 (d, J ¼ 8:4 Hz, 1H, ArH), 6.96 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 1.9, 23.4, 36.3, 56.2,
108.0, 122.0, 129.6, 136.8, 142.4, 156.7; 77Se NMR (76 MHz) ꢁ
31.0 (JSe-117Sn ¼ 1091, JSe-119Sn ¼ 1142 Hz); 119Sn NMR (149
MHz) ꢁ 135.3 (JSn-77Se ¼ 1142 Hz); IR (KBr) 2957, 1571, 1458,
1425, 1274, 1252, 1215, 1036, 795, 768 cmꢂ1; MS (70 eV) m=z
408 (Mþ); Anal. Calcd for C12H18OSSeSn: C, 35.33; H, 4.45%.
Found: C, 35.23; H, 4.50%.
4-Isopropyl-7-methoxy-2,2-dimethyl-1,3,2-benzodiselena-
ꢁ
1
stannole (1d). Colorless crystals; mp 180.5–181.5 C; H NMR
(400 MHz) ꢁ 1.05 (s, 6H, Sn(CH3)2), 1.26 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 3.45 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.87 (s,
3H, OCH3), 6.66 (d, J ¼ 8:4 Hz, 1H, ArH), 7.04 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 1.4, 23.5, 36.8, 56.3,
108.0, 123.1, 127.3, 139.3, 143.1, 157.3; 77Se NMR (76 MHz) ꢁ
82.6 (JSe-117Sn ¼ 1059, JSe-119Sn ¼ 1109 Hz), 72.8 (JSe-117Sn
¼
1020, JSe-119Sn ¼ 1067 Hz); 119Sn NMR (149 MHz) ꢁ 75.6
(JSn-77Se ¼ 1067, 1109 Hz); IR (KBr) 2954, 1462, 1421, 1276,
1251, 1038, 794 cmꢂ1; MS (70 eV) m=z 456 (Mþ); Anal. Calcd
for C12H18OSe2Sn: C, 31.69; H, 3.99%. Found: C, 31.43; H,
3.88%.
General Procedure for the Synthesis of 4-Isopropyl-7-meth-
oxy-1,3,2-benzodichalcogenatitanoles 2a–f. Butyllithium (3.12
mL of a 1.54 M solution in hexane, 4.80 mmol) was added to a
stirred solution of 2-isopropyl-5-methoxybenzenethiol (360 mg,
1.97 mmol) in N,N,N0,N0-tetramethylethylenediamine (5.0 mL,
33.0 mmol) at 0 ꢁC. After 2 h at room temperature, elemental sul-
fur (70 mg, 2.2 mmol) was added at 0 ꢁC. After the reaction mix-
ture was stirred for 12 h at room temperature, it was treated with
bis(pentamethylcyclopentadienyl)titanium(d) dichloride (780 mg,
7-Isopropyl-4-methoxy-2,2-bis(pentamethylcyclopentadien-
yl)-1,3,2-bꢁenzoselenatelluratitanole (2f). Deep green crystals;
1
mp 155.0 C (decomp.); H NMR (400 MHz) ꢁ 1.18 (d, J ¼ 6:9
Hz, 6H, CH(CH3)2), 1.99 (s, 30H, CH3), 3.60 (sept, J ¼ 6:9 Hz,
1H, CH(CH3)2), 3.84 (s, 3H, OCH3), 6.69 (d, J ¼ 8:3 Hz, 1H,
ArH), 7.07 (d, J ¼ 8:3 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
13.6, 23.8, 34.9, 56.0, 105.5, 122.4, 123.6, 125.0, 143.5, 155.5,
158.1; 77Se NMR (76 MHz) ꢁ 1003.2; 125Te NMR (126 MHz) ꢁ
1055.1; IR (KBr) 2904, 1449, 1377, 1308, 1252, 807 cmꢂ1; MS
(70 eV) m=z 674 (Mþ).
ꢁ
2.00 mmol) in THF (40 mL) at 0 C, and was stirred for 6 h at
room temperature. The solution was concentrated in vacuo, and
purified by column chromatography on silica gel with CCl4/
CHCl3 (1:1 v/v) as the eluent to give 456 mg (0.86 mmol, 44%)
of 2a as deep green crystals: mp 242.5–243.0 ꢁC (decomp.);
1H NMR (400 MHz) ꢁ 1.21 (d, J ¼ 6:9 Hz, 6H, CH(CH3)2),
1.87 (s, 30H, CH3), 3.69 (sept, J ¼ 6:9 Hz, 1H, CH(CH3)2),
3.86 (s, 3H, OCH3), 6.59 (d, J ¼ 8:2 Hz, 1H, ArH), 6.94 (d, J ¼
8:2 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 12.4, 23.5, 30.9, 55.7,
104.5, 119.9, 123.6, 140.6, 141.5, 154.8, 155.2; IR (KBr) 2900,
1552, 1449, 1378, 1254, 1209, 1047 cmꢂ1; MS (70 eV) m=z
530 (Mþ); Anal. Calcd for C30H42OS2Ti: C, 67.90; H, 7.98%.
Found: C, 67.64; H, 8.23%.
7-Isopropyl-4-methoxy-2,2-bis(pentamethylcyclopentadien-
yl)-1,3,2-benzothiaselenatitanole (2b). Deep green crystals; mp
230.0–230.5 ꢁC (decomp.); 1H NMR (400 MHz) ꢁ 1.19 (d,
J ¼ 6:9 Hz, 6H, CH(CH3)2), 1.89 (s, 30H, CH3), 3.67 (sept, J ¼
6:9 Hz, 1H, CH(CH3)2), 3.87 (s, 3H, OCH3), 6.61 (d, J ¼ 8:3 Hz,
1H, ArH), 6.97 (d, J ¼ 8:3 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
12.6, 23.5, 31.4, 55.7, 104.6, 120.7, 123.7, 137.5, 141.1, 155.86,
155.89; 77Se NMR (76 MHz) ꢁ 772.7; IR (KBr) 2904, 1550,
1443, 1419, 1377, 1275, 1252, 1047, 803 cmꢂ1; MS (70 eV)
m=z 578 (Mþ); Anal. Calcd for C30H42OSSeTi: C, 62.39; H,
7.33%. Found: C, 62.22; H, 7.62%.
General Procedure for the Synthesis of 4-Isopropyl-7-meth-
oxy-1,2,3-benzotrichalcogenole 2-Oxides 3a–d. 4-Isopropyl-7-
methoxy-2,2-dimethyl-1,3,2-benzodithiastannole (1a) (181 mg,
ꢁ
0.50 mmol) was dissolved in THF (10 mL) and cooled to 0 C.
A solution of thionyl chloride (0.04 mL, 0.60 mmol) in THF (6
ꢁ
mL) wasꢁadded at 0 C, and the reaction mixture was stirred for
2 h at 0 C. Then, the reaction mixture was poured into water.
The organic layer was extracted with dichloromethane and dried
over anhydrous magnesium sulfate. The solution was concen-
trated in vacuo and purified by column chromatography on silica
gel with tetrachloromethane as an eluent to give 121 mg (0.47
mmol, 94%) of 4-isopropyl-7-methoxy-1,2,3-benzotrithiole 2-ox-
ide (3a) as a green oil: 1H NMR (400 MHz) ꢁ 1.23 (d, J ¼ 6:8
Hz, 3H, CH(CH3)2), 1.34 (d, J ¼ 6:8 Hz, 3H, CH(CH3)2), 3.00
(sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.91 (s, 3H, OCH3), 6.86 (d,
J ¼ 8:4 Hz, 1H, ArH), 7.24 (d, J ¼ 8:4 Hz, 1H, ArH); 13C NMR
(101 MHz) ꢁ 22.6, 23.4, 34.8, 56.2, 110.0, 123.8, 125.8, 136.0,
137.5, 153.7; IR (neat) 2962, 2838, 1581, 1469, 1434, 1288,
1124, 1042, 807, 483, 437 cmꢂ1; MS (70 eV) m=z 260 (Mþ);

1052 Bull. Chem. Soc. Jpn., 76, No. 5 (2003)
Five-Membered Trichalcogenaheterocycles
Anal. Calcd for C10H12O2S3: C, 46.13; H, 4.64%. Found: C,
46.29; H, 4.61%.
7-Isopropyl-4-methoxy-1,2,3-benzodithiaselenole 2-Oxide
for C10H12OS2Se: C, 41.23; H, 4.15%. Found: C, 41.52; H,
4.28%.
4-Isopropyl-7-methoxy-1,2,3-benzodithiaselenole (4c). Or-
ange oil; 1H NMR (400 MHz) ꢁ 1.23 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 2.77 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.84 (s,
3H, OCH3), 6.70 (d, J ¼ 8:4 Hz, 1H, ArH), 7.01 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.5, 38.0, 56.2, 110.8,
125.3, 130.1, 140.9, 154.7; 77Se NMR (76 MHz) ꢁ 624.1; IR (neat)
2960, 2835, 1579, 1470, 1433, 1278, 1090, 1031, 804 cmꢂ1; MS
(70 eV) m=z 292 (Mþ); Anal. Calcd for C10H12OS2Se: C, 41.23;
H, 4.15%. Found: C, 41.52; H, 4.12%.
ꢁ
1
(3b). Orange crystals; mp 70.5–71.0 C; H NMR (400 MHz) ꢁ
1.23 (d, J ¼ 6:8 Hz, 3H, CH(CH3)2), 1.34 (d, J ¼ 6:8 Hz, 3H,
CH(CH3)2), 3.09 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.90 (s,
3H, OCH3), 6.87 (d, J ¼ 8:3 Hz, 1H, ArH), 7.29 (d, J ¼ 8:3
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 22.8, 23.6, 34.9, 56.3,
109.6, 125.3, 126.3, 139.0, 154.5; 77Se NMR (76 MHz) ꢁ
1152.3; IR (neat) 2961, 1581, 1557, 1464, 1265, 1222, 1115,
1040, 907, 463 cmꢂ1; MS (70 eV) m=z 308 (Mþ); Anal. Calcd
for C10H12O2S2Se: C, 39.09; H, 3.94%. Found: C, 39.18; H,
3.98%.
4-Isopropyl-7-methoxy-2,1,3-benzothiadiselenole (4d). Red
1
oil; H NMR (400 MHz) ꢁ 1.22 (d, J ¼ 6:8 Hz, 6H, CH(CH3)2),
4-Isopropyl-7-methoxy-1,2,3-benzodithiaselenole 2-Oxide
(3c). Yellow oil; 1H NMR (400 MHz) ꢁ 1.23 (d, J ¼ 6:8 Hz, 3H,
CH(CH3)2), 1.35 (d, J ¼ 6:8 Hz, 3H, CH(CH3)2), 2.77 (sept, J ¼
6:8 Hz, 1H, CH(CH3)2), 3.90 (s, 3H, OCH3), 6.90 (d, J ¼ 8:6 Hz,
1H, ArH), 7.25 (d, J ¼ 8:6 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
22.9, 23.7, 37.9, 56.3, 110.2, 125.7, 127.4, 137.9, 139.1, 154.7;
77Se NMR (76 MHz) ꢁ 1149.0; IR (neat) 2960, 1578, 1461,
1430, 1286, 1105, 1030, 807 cmꢂ1; MS (70 eV) m=z 308 (Mþ);
Anal. Calcd for C10H12O2S2Se: C, 39.09; H, 3.94%. Found: C,
39.42; H, 3.91%.
2.83 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.82 (s, 3H, OCH3),
6.71 (d, J ¼ 8:4 Hz, 1H, ArH), 7.06 (d, J ¼ 8:4 Hz, 1H, ArH);
13C NMR (101 MHz) ꢁ 23.6, 38.0, 56.2, 110.6, 125.7, 129.0,
140.2, 141.7, 155.7; 77Se NMR (76 MHz) ꢁ 655.9, 645.4; IR (neat)
2959, 1578, 1464, 1432, 1278, 1078, 1030, 804 cmꢂ1; MS (70 eV)
m=z 340 (Mþ); Anal. Calcd for C10H12OSSe2: C, 35.52; H, 3.58%.
Found: C, 35.67; H, 3.34%.
General Procedure for the Synthesis of 4-Isopropyl-7-meth-
oxy-1,2,3-benzotrichalcogenoles 4e–h. To a solution of 4-iso-
propyl-7-methoxy-2,2-dimethyl-1,3,2-benzodithiastannole
(181 mg, 0.50 mmol) in THF (10 mL) was added seleninyl chlor-
(1a)
4-Isopropyl-7-methoxy-2,1,3-benzothiadiselenole 2-Oxide
ꢁ
1
ꢁ
(3d). Orange crystals; mp 63.0–64.0 C; H NMR (400 MHz) ꢁ
1.22 (d, J ¼ 6:8 Hz, 3H, CH(CH3)2), 1.35 (d, J ¼ 6:8 Hz, 3H,
CH(CH3)2), 2.85 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.89 (s,
3H, OCH3), 6.91 (d, J ¼ 8:6 Hz, 1H, ArH), 7.28 (d, J ¼ 8:6
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 155.4, 141.1, 140.4,
129.3, 126.1, 110.0, 56.3, 37.9, 23.9, 23.0; 77Se NMR (76 MHz)
ꢁ 1159.3, 1156.4; IR (neat) 2960, 1578, 1461, 1430, 1286,
1264, 1105, 1030, 807 cmꢂ1; MS (70 eV) m=z 356 (Mþ); Anal.
Calcd for C10H12O2SSe2: C, 33.91; H, 3.41%. Found: C, 34.24;
H, 3.37%.
ide (0.042 mL, 0.60 mmol) in THF (6 mL) at ꢂ78 C. After 40
min at ꢂ78 ꢁC, the reaction mixture was treated with trimethylsi-
lyl trifluꢁoromethanesulfonate (0.11 ꢁmL, 0.6 mmol) in THF (2 mL)
at ꢂ78 C. After 30 min at ꢂ78 C, 0.1 M samarium(b) iodide
THF solution (12.0 mL, 1.2 mmol) was added at ꢂ78 ꢁC. The re-
sulting solution was stirred for 45 min at ꢂ78 ꢁC, then was stirred
for 90 min at room temperature, and then poured into water. The
organic layer was extracted with dichloromethane, washed with
sodium chloride solution, and dried over anhydrous magnesium
sulfate. The solution was concentrated in vacuo and purified by
column chromatography on silica gel with hexane as an eluent
to give 119 mg (0.41 mmol, 82%) of 4-isopropyl-7-methoxy-
1,3,2-benzodithiaselenole (4e) as a reddish brown oil: 1H NMR
(400 MHz) ꢁ 1.22 (d, J ¼ 6:8 Hz, 6H, CH(CH3)2), 3.09 (sept, J ¼
6:8 Hz, 1H, CH(CH3)2), 3.84 (s, 3H, OCH3), 6.60 (d, J ¼ 8:5 Hz,
1H, ArH), 6.93 (d, J ¼ 8:5 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
23.2, 34.7, 56.1, 110.5, 125.2, 129.9, 138.5, 142.8, 154.7;
77Se NMR (76 MHz) ꢁ 701.3; IR (neat) 2963, 1712, 1577, 1468,
1432, 1275, 1039, 903 cmꢂ1; MS (70 eV) m=z 292 (Mþ); Anal.
Calcd for C10H12OS2Se: C, 41.23; H, 4.15%. Found: C, 41.03;
H, 4.16%.
General Procedure for the Synthesis of 4-Isopropyl-7-meth-
oxy-1,2,3-benzotrichalcogenoles 4a–d. To a solution of 1,2,3-
benzotrithiole 2-oxide 3a (87 mg, 0.33 mmol) and sodium iodide
(253 mg, 1.67 mmol) in THF (30 mL) and H2O (3.1 mL) was
ꢁ
added a 70% perchloric acid solution (4.0 mL) at 0 C. After 6
h at room temperature, the reaction mixture was neutralized with
aqueous sodium hydrogencarbonate solution and extracted with
dichloromethane. The organic layer was washed with aqueous so-
dium hydrogensulfite solution and dried over anhydrous magne-
sium sulfate. The solution was concentrated in vacuo and purified
by column chromatography on silica gel with tetrachloromethane
as an eluent to give 78 mg (0.32 mmol, 97%) of 1,2,3-benzo-
7-Isopropyl-4-methoxy-1,2,3-benzothiadiselenole (4f).
1
trithiole 4a as an orange oil: H NMR (400 MHz) ꢁ 1.23 (d, J ¼
Brown oil; 1H NMR (400 MHz) ꢁ 1.22 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 3.15 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.83 (s,
3H, OCH3), 6.61 (d, J ¼ 8:4 Hz, 1H, ArH), 7.00 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.4, 34.9, 56.1, 110.4,
125.7, 128.0, 139.4, 143.6, 155.5; 77Se NMR (76 MHz) ꢁ 568.9,
507.6 (JSe-Se ¼ 311 Hz); IR (neat) 2958, 1579, 1463, 1432,
1274, 1039, 802 cmꢂ1; MS (70 eV) m=z 340 (Mþ); HRMS m=z
Calcd for C10H12OSSe2: 339.8939. Found: 339.8950.
6:9 Hz, 6H, CH(CH3)2), 2.95 (sept, J ¼ 6:9 Hz, 1H, CH(CH3)2),
3.84 (s, 3H, OCH3), 6.65 (d, J ¼ 8:4 Hz, 1H, ArH), 6.97 (d, J ¼
8:4 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.1, 35.0, 56.1, 110.4,
125.3, 137.5, 141.7, 153.9; IR (neat) 2960, 2836, 1582, 1473,
1435, 1279, 1236, 1094, 1039, 803, 580 cmꢂ1; MS (70 eV) m=z
244 (Mþ); Anal. Calcd for C10H12OS3: C, 49.15; H, 4.95%.
Found: C, 49.51; H, 4.97%.
7-Isopropyl-4-methoxy-1,2,3-benzodithiaselenole (4b).
4-Isopropyl-7-methoxy-1,2,3-benzothiadiselenole (4g).
Reddish brown oil; 1H NMR (400 MHz) ꢁ 1.22 (d, J ¼ 6:8 Hz,
6H, CH(CH3)2), 3.02 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.83
(s, 3H, OCH3), 6.66 (d, J ¼ 8:4 Hz, 1H, ArH), 7.03 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.3, 35.1, 56.1, 110.4,
125.7, 127.2, 138.3, 142.7, 155.0; 77Se NMR (76 MHz) ꢁ 633.6;
IR (neat) 2959, 2835, 1582, 1469, 1434, 1278, 1231, 1181,
1082, 1038, 803 cmꢂ1; MS (70 eV) m=z 292 (Mþ); Anal. Calcd
Reddish-brown oil; 1H NMR (400 MHz) ꢁ 1.23 (d, J ¼ 6:8 Hz,
6H, CH(CH3)2), 2.90 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.84
(s, 3H, OCH3), 6.66 (d, J ¼ 8:4 Hz, 1H, ArH), 6.97 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.5, 37.8, 56.2, 110.8,
125.2, 131.4, 140.0, 141.4, 155.6; 77Se NMR (76 MHz) ꢁ 581.8,
501.9 (JSe-Se ¼ 279 Hz); IR (neat) 2958, 1575, 1464, 1431,
1274, 1087, 1030, 804 cmꢂ1; MS (70 eV) m=z 340 (Mþ); HRMS

N. Nagahora et al.
Bull. Chem. Soc. Jpn., 76, No. 5 (2003) 1053
m=z Calcd for C10H12OSSe2: 339.8939. Found: 339.8940.
4-Isopropyl-7-methoxy-1,2,3-benzotriselenole (4h).
C10H12OSe2Te: C, 27.69; H, 2.79%. Found: C, 27.96; H, 2.80%.
General Procedure for the Synthesis of 4-Isopropyl-7-
Dark
brown oil; 1H NMR (400 MHz) ꢁ 1.23 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 2.96 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.83 (s,
3H, OCH3), 6.67 (d, J ¼ 8:4 Hz, 1H, ArH), 7.04 (d, J ¼ 8:4
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.7, 37.9, 56.2, 110.7,
125.7, 129.7, 141.0, 142.1, 156.3; 77Se NMR (76 MHz) ꢁ 543.0
(JSe-Se ¼ 292 Hz), 533.6 (JSe-Se ¼ 265 Hz), 436.7 (JSe-Se ¼ 292,
265 Hz); IR (neat) 2957, 1576, 1459, 1430, 1275, 1029, 803
cmꢂ1; MS (70 eV) m=z 386 (Mþ, C10H12O78Se80Se2); HRMS
m=z Calcd for C10H12OSe3: 387.8384. Found: 387.8389.
General Procedure for the Synthesis of Tellurium-Contain-
ing 7-Isopropyl-4-methoxy-1,2,3-benzotrichalcogenoles 4i–l.
To a solution of 2,2-bis(ꢀ5-pentamethylcyclopentadienyl)-7-iso-
propyl-4-methoxy-1,3,2-benzothiatelluratitanole (2c) (532 mg,
0.85 mmol) in THF ꢁ(10 mL) was added sulfur dichloride (0.1
mL, 1.7 mmol) at 0 C. After 30 min at room temperature, the
reaction mixture was poured into water. The organic layer was
extracted with dichloromethane and dried over anhydrous magne-
sium sulfate. The solution was concentrated in vacuo and purified
by column chromatography on silica gel with hexane as an eluent
to give 274 mg (0.81 mmol, 95%) of 7-isopropyl-4-methoxy-
1,2,3-benzodithiatellurole (4i) as a red oil: 1H NMR (400 MHz)
ꢁ 1.21 (d, J ¼ 6:9 Hz, 6H, CH(CH3)2), 3.10 (sept, J ¼ 6:9 Hz,
1H, CH(CH3)2), 3.82 (s, 3H, OCH3), 6.70 (d, J ¼ 8:4 Hz, 1H,
ArH), 7.05 (d, J ¼ 8:4 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ
23.5, 35.3, 56.2, 109.8, 118.3, 126.7, 139.6, 147.6, 158.2;
125Te NMR (126 MHz) ꢁ 1346.7; IR (neat) 2958, 1577, 1460,
1431, 1261, 1036, 803 cmꢂ1; MS (70 eV) m=z 342 (Mþ); Anal.
Calcd for C10H12OS2Te: C, 35.33; H, 3.56%. Found: C, 35.12;
H, 3.34%.
methoxy-1,2,3-benzotrichalcogenolium Hexafluorophosphate
4aꢀþPF6ꢁ, 4dꢀþPF6ꢁ, and 4hꢀþPF6
ꢁ
.
A solution of 4-isopro-
pyl-7-methoxy-1,2,3-benzotrithiole (4a) (80 mg, 0.33 mmol) in
Et2O (10 mL) under argon was treated with nitrosonium hexa-
fluorophosphate (60 mg, 0.33 mmol) in acetonitrile (2 mL) at
ꢁ
ꢂ78 C. The solution immediately changed from orange to dark
ꢁ
blue. After stirring for 30 min at ꢂ78 C, the dark blue product
was separated from the solution by filtration. The product was
washed with ether and dried under reduced pressure to give 120
mg (0.31 mmol, 94%) of 4-isopropyl-7-methoxy-1,2,3-benzo-
trithiolium hexafluorophosphate (4aꢃþPF6ꢂ): Dark blue powder
(from ether); mp 95.0–96.5 ꢁC (decomp.); 31P NMR (162 MHz,
CD3CN) ꢁ ꢂ143:6 (sept, JP-F ¼ 706 Hz); Anal. Calcd for
C10H12OS3PF6: C, 30.85; H, 3.11%. Found: C, 30.90; H,
3.29%; X-band ESR (MeCN, 238 K) g ¼ 2:013 (aH1 ¼ 0:110,
aH2 ¼ 0:072 mT).
4-Isopropyl-7-methoxy-2,1,3-benzothiadiselenolium Hexa-
fluorophosphate (4dꢀþPF6ꢁ). Dark blue powder (from ether);
mp 107.5–108.0 ꢁC (decomp.); 31P NMR (162 MHz, CD3CN) ꢁ
ꢂ143:7 (sept, JP-F ¼ 706 Hz); X-band ESR (MeCN, 238 K)
g ¼ 2:025.
4-Isopropyl-7-methoxy-1,2,3-benzotriselenolium Hexafluor-
ophosphate (4hꢀþPF6ꢁ). Dark blue powder (from ether); mp
195.0–197.0 ꢁC (decomp.); 31P NMR (162 MHz, CD3CN) ꢁ
ꢂ143:6 (sept, JP-F ¼ 707 Hz); Anal. Calcd for C10H12OSe3PF6:
C, 22.66; H, 2.28%. Found: C, 22.82; H, 2.26%; X-band ESR
(MeCN, 281 K) g ¼ 2:061.
General Procedure for the Reduction with Samarium(b)
Iodide of 1,2,3-Benzotrithiolium Hexafluorophosphate (4aꢀþ
-
7-Isopropyl-4-methoxy-1,2,3-benzothiaselenatellurole (4j).
Red crystals; mp 96.0–96.5 ꢁC; 1H NMR (400 MHz) ꢁ 1.21 (d,
J ¼ 6:8 Hz, 6H, CH(CH3)2), 3.22 (sept, J ¼ 6:8 Hz, 1H,
CH(CH3)2), 3.82 (s, 3H, OCH3), 6.64 (d, J ¼ 8:4 Hz, 1H, ArH),
7.05 (d, J ¼ 8:4 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.5,
35.2, 56.2, 109.7, 117.9, 126.6, 140.7, 147.9, 158.3; 77Se NMR
(76 MHz) ꢁ 295.3 (J77Se-125Te ¼ 878 Hz); 125Te NMR (126
MHz) ꢁ 1095.2 (J125Te-77Se ¼ 878 Hz); IR (KBr) 2954, 1460,
1275, 1223, 1038, 584 cmꢂ1; MS (70 eV) m=z 388 (Mþ); Anal.
Calcd for C10H12OSSeTe: C, 31.05; H, 3.13%. Found: C, 30.72;
H, 2.93%.
PF6ꢁ). A solution of 4-isopropyl-7-methoxy-1,2,3-benzotrithio-
lium hexafluorophosphate (4aꢃþPF6ꢂ) (47 mg, 0.12 mmol) in
THF (5 mL) at ꢂ78 ꢁC under argon was treated with 0.1 M
samarium(b) iodide THF solution (1.2ꢁmL, 0.12 mmol). The so-
lution was stirred for 30 min at ꢂ78 C, and poured into water.
The organic layer was extracted with dichloromethane and dried
over anhydrous magnesium sulfate. The solution was concen-
trated in vacuo and purified by column chromatography on silica
gel with tetrachloromethane as an eluent to give 29 mg (0.12
mmol, quant.) of 4-isopropyl-7-methoxy-1,2,3-benzotrithiole
(4a) as an orange oil.
7-Isopropyl-4-methoxy-2,1,3-benzothiaselenatellurole (4k).
Red oil; 1H NMR (400 MHz) ꢁ 1.21 (d, J ¼ 6:8 Hz, 6H,
CH(CH3)2), 2.91 (sept, J ¼ 6:8 Hz, 1H, CH(CH3)2), 3.81 (s,
3H, OCH3), 6.74 (d, J ¼ 8:3 Hz, 1H, ArH), 7.09 (d, J ¼ 8:3
Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.8, 38.2, 56.3, 110.0,
120.6, 126.6, 141.6, 146.8, 158.7; 77Se NMR (76 MHz) ꢁ 657.1;
125Te NMR (126 MHz) ꢁ 1383.9; IR (neat) 2957, 1459, 1429,
1259, 1027, 804 cmꢂ1; MS (70 eV) m=z 388 (Mþ); Anal. Calcd
for C10H12OSSeTe: C, 31.05; H, 3.13%. Found: C, 31.19; H,
3.13%.
7-Isopropyl-4-methoxy-1,2,3-benzodiselenatellurole (4l).
Red crystals; mp 96.0–96.5 ꢁC; 1H NMR (400 MHz) ꢁ 1.21 (d,
J ¼ 6:8 Hz, 6H, CH(CH3)2), 3.04 (sept, J ¼ 6:8 Hz, 1H,
CH(CH3)2), 3.81 (s, 3H, OCH3), 6.70 (d, J ¼ 8:3 Hz, 1H, ArH),
7.09 (d, J ¼ 8:3 Hz, 1H, ArH); 13C NMR (101 MHz) ꢁ 23.9,
38.1, 56.3, 110.0, 120.2, 126.6, 142.4, 146.6, 159.0; 77Se NMR
(76 MHz) ꢁ 555.2 (J77Se-77Se ¼ 260 Hz), 141.7 (J77Se-77Se ¼ 260
Hz, J77Se-125Te ¼ 846 Hz); 125Te NMR (126 MHz) ꢁ 1153.1
(J125Te-77Se ¼ 846 Hz); IR (KBr) 2954, 1573, 1457, 1426, 1272,
1025 cmꢂ1; MS (70 eV) m=z 433 (Mþ); Anal. Calcd for
X-ray Crystal Structure Analyses. Diffraction data were col-
lected on a Rigaku AFC7R diffractometer employing Mo Kꢄ or
Cu Kꢄ radiation using the !=2ꢅ scan technique. The structure
was determined by direct methods (SHELXS8635 or SIR9236)
and expanded using Fourier technique (DIRDIF9437). All calcu-
lations were performed using the teXsan38 crystallographic soft-
ware package of Molecular Structure Corporation.
We thank Dr. Yuji Mikata (KYOUSEI Science Center, Nara
Women’s University) for X-ray crystallographic analyses,
Prof. Shigeya Niizuma (Faculty of Humanities and Social
Science, Iwate University) for ESR spectra, and Ms. Shiduko
Nakajo (Division of Elemental Analysis, Iwate University)
for elemental analyses. Computation time was provided by
the Super Computing and Information Sciences Center, Iwate
University.
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