Bis(2,6-dimethoxyphenyl) sulfide, selenide and telluride, and their derivatives

Article abstract of DOI:10.1016/S0022-328X(98)01157-7

2,6-Dimethoxyphenyl derivatives of sulfur, selenium, and tellurium, such as ΦEEΦ, Φ₂E, ΦSeH, [MeΦ₂E]X (X = MeSO₄, ClO₄), Φ₂EO · xH₂O, [Φ₂EOH]ClO₄, [Φ₂EOR]Cl

Full text of DOI:10.1016/S0022-328X(98)01157-7

Journal of Organometallic Chemistry 580 (1999) 282–289
Bis(2,6-dimethoxyphenyl) sulfide, selenide and telluride, and their
derivatives
Masanori Wada *, Shin-ichi Nobuki, Yoshinori Tenkyuu, Satoko Natsume,
Masahiro Asahara, Tatsuo Erabi
Department of Materials Science, Faculty of Engineering, Tottori Uni6ersity, Koyama, Tottori 680-0945, Japan
Received 27 October 1998; received in revised form 3 December 1998
Abstract
2,6-Dimethoxyphenyl derivatives of sulfur, selenium, and tellurium, such as FEEF, F2E, FSeH, [MeF2E]X (X=MeSO4, ClO4),
F2EO · xH2O, [F2EOH]ClO4, [F2EOR]ClO4 (R=Me, Et), Me2SnCl2 · 2F2EO (E=S, Se) [F=2,6-(MeO)2C6H3; E=S, Se, Te]
have been prepared, and their properties compared with common phenyl derivatives. The reaction rates of F2E with dimethyl
sulfate and butyl bromide increased in the order E=SBSeBTe, which were compared with those of Ph3M and F3M,
M=P\As\Sb. These reactivities are parallel with the electrochemical oxidation potentials reported for Ph2E and with the first
ionization potentials reported for Ph3M. The rate of F2Te was faster than that of Ph3P and slightly faster than that of F3Sb. From
the reactivity of [F2E-Me]+ salts with nucleophiles, the E+ –Me bond strengths were estimated to increase in the order
E=SeBSBTe. The reaction rates of F2EO with dimethyl sulfate increased in the order E=SBSeBTe, and the respective rate
of F2EO was faster than that of F2E. The origins of these reactivities and bond strengths are discussed. © 1999 Elsevier Science
S.A. All rights reserved.
Keywords: Sulfur; Selenium; Tellurium; 2,6-Dimethoxyphenyl; Onium; Reaction rate; Bond strength
the details of preparations and some basic reactions of
2,6-dimethoxyphenyl derivatives (Scheme 1), and also
compare the nucleophilic reactivities of F2E and F2EO
(E=S, Se, Te) (Eqs. (1) and (2)) with those of Group
15 elements.
1. Introduction
It is a basic chemical interest to compare the chemi-
cal and physical properties of compounds among ele-
ments as well as substituents. While a variety of
comparisons have been reported among Group 15 and
16 elements, there are few works of comparison be-
tween the two groups. As part of our systematic investi-
gation on the chemistry of 2,6-dimethoxyphenyl
derivatives such as F3M {M=P, As, Sb, Bi; F=2,6-
(MeO)2C6H3} [1,2], we attempted to study a series of its
derivatives of Group 16 elements. 2,6-Dimethoxyphenyl
derivatives of these elements in general have prominent
properties such as odorless character, higher crys-
tallinity and higher nucleophilicity than common
phenyl derivatives [3,4]. In the present paper, we report
F2E+RX“[F2E–R]X
(1)
(2)
F2EO+RX“[F2E–OR]X
{E=S, Se, Te; RX=(MeO)2SO2, BuBr, BuI}
2. Experimental
2.1. Physical measurements
1H- and 13C-NMR spectra were recorded for solu-
tions in CDCl3 using a JEOL model JNM-GX-270
* Corresponding author. Fax: +81-857-31-0881.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01157-7

M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
283
Scheme 1.
2.2.2. bSeSeb
spectrometer. IR spectra were recorded for Nujol mull
using a Shimadzu FTIR-4200 spectrophotometer. GC-
MS spectra were recorded using a Shimadzu QP-5000
mass spectrometer. The 1H- and 13C-NMR spectral
data are summarized in Tables 1 and 2, respectively.
A suspension of FLi was prepared as mentioned
above from 1,3-dimethoxybenzene (20 mmol), 15% hex-
ane solution of butyllithium (20 mmol) and TMEDA
(0.1 ml) under argon. To this suspension were added
elemental selenium (15 mmol), dry lithium chloride (ca.
1 g) and dry tetrahydrofuran (30 ml), and the mixture
was stirred at r.t. in the dark for 15 h to give a brown
suspension. Water (50 ml) was added to extract the
precipitates of FSeLi, the aqueous layer was treated
with 30% aqueous hydrogen peroxide (1.6 ml, 20 mmol)
as mentioned above, and the resultant precipitates
could be recrystallized from methanol to give orange
crystals of FSeSeF (6.5ꢀ5.0 mmol); m.p. 146–147°C;
MS [m/z (rel. intensity)] 434 and 432 (50, M+), 138
(100). Anal. Found: C, 44.67; H, 4.26%. Calc. for
C16H18O4Se2: C, 44.46; H, 4.20%. The organic layer was
dried under reduced pressure, and the residue was
recrystallized from diethyl ether to give F2Se (0.34
mmol) (see below for the characterization).
2.2. Preparation of bis(2,6-dimethoxyphenyl) disulfide,
diselenide and ditelluride
2.2.1. bSSb
A suspension of FLi was prepared from a 15%
hexane solution of butyllithium (12.5 ml, 20 mmol),
1,3-dimethoxybenzene (2.6 ml, 20 mmol), and a cata-
lytic amount of tetramethylethylenediamine (TMEDA)
(0.1 ml) as described elsewhere [1]. To this suspension
were added elemental sulfur (0.481 g, 15 mmol) and
benzene (15 ml), and the mixture was stirred at room
temperature (r.t.) for 15 h to give a brown suspension.
Water (50 ml) was added to extract the precipitates of
FSLi. To the aqueous solution was added 30% aqueous
hydroperoxide (1.6 ml, 20 mmol) to give precipitates,
immediately, which could be recrystallized from ace-
tone to give light yellow crystals of FSSF (7.1ꢀ5.2
mmol); m.p. 199–201°C (206–209 [5]); MS [m/z (ref.
intensity)] 338 (100, M+). Anal. Found: C, 56.60; H,
5.42; S, 18.88%. Calc. for C16Hl8O4S2: C, 56.78; H, 5.36;
S, 18.95%. The organic layer was dried under reduced
pressure, and the residue was recrystallized from 2-
propanol to give F2S (0.31 mmol) (see below for the
characterization).
2.2.3. bTeTeb
In an analogous manner to that mentioned above, a
treatment of FLi suspension with elemental tellurium
(15 mmol) in the presence of lithium chloride and
tetrahydrofuran gave dark brown crystals of FTeTeF
(4.5ꢀ3.2 mmol), which could be recrystallized from
methanol or toluene; m.p. 140–141°C; MS [m/z(rel.
intensity)] 530 (20, M+), 137 (100). Anal. Found: C,
36.24; H, 3.53%. Calc. for C16H18O4Te2: C, 36.29; H,
3.43%.

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M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
Table 1
1H-NMR spectral data for 2,6-dimethoxyphenyl derivatives of sulfur, selenium and telluriuma
Compounds
l(4-H)b
l(3,5-H)c
l(2,6-MeO)d
l(Others)
F2S
7.13
7.14
7.17
7.23
7.22
7.18
7.11
7.27
7.27
7.26
7.55
7.49
7.44
7.62
7.56
7.70
7.46
7.44
7.69
7.45
7.30
7.33
6.49
6.48
6.46
6.51
6.51
6.48
6.54
6.53
6.53
6.52
6.69
6.66
6.61
6.77
6.75
6.77
6.63
6.65
6.76
6.62
6.54
6.55
3.72
3.68
3.64
3.69
3.71
3.75
3.87
3.78
3.75
3.70
3.93
3.84
3.77
3.97
3.88
3.92
3.82
3.79
3.92
3.81
3.78
3.76
F2Se
F2Te
FSSF
FSeSeF
FTeTeF
FSeH
F2SO
F2SeO · H2O
F2TeO · (2/3)H2O
[MeF2S]ClO4
[MeF2Se]ClO4
[MeF2Te]ClO4
[F2SeOH]ClO4
[F2TeOH]ClO4
[F2SOMe]ClO4
[F2SeOMe]2SO4
[F2TeOMe]2SO4
[F2SOEt]ClO4
[F2SeOEt]2SO4
Me2SnCl2 · 2F2SO
Me2SnCl2 · 2F2SeO
2.02s[J(Se) 68 Hz, Se–H]
3.67s (Me–S)
3.57s (Me–Se)
3.06s (Me–Te)
e
e
4.12s (OMe)
3.72s (OMe)
3.64s (OMe)
4.41q[J(H) 7 Hz],1.46t[J(H) 7 Hz]
4.10q[J(H) 7 Hz],1.27t[J(H) 7 Hz]
1.19s[J(119Sn) 83.5 Hz, Me–Sn]
1.16s[J(119Sn) 85.5 Hz, Me–Sn]
a In CDCl3; F=2,6-(MeO)2C6H3; s, singlet, t, triplet, q, quartet.
b Triplet with JHH 8–9 Hz.
c Doublet with JHH 8–9 Hz.
d Singlet.
e Measured in the presence of CF3COOH (ca. 1 w/w%) to avoid deprotonation.
2.3. Preparation of bis(2,6-dimethoxyphenyl)sulfide,
-selenide, and -telluride
in this layer were removed under reduced pressure, and
the residue could be recrystallized from diethyl ether to
give light yellow crystals of F2Se (9.2 mmol); m.p.
124–125°C; MS [m/z (rel. intensity)] 354 (100, M+).
Anal. Found: C, 54.11; H, 5.16%. Calc. for
C16H18O4Se1: C, 54.40; H, 5.14%. The aqueous layer
was acidified using 6 M hydrochloric acid to give FSeH
(9.2 mmol) (see below).
2.3.1. b2S
To a suspension of FLi, prepared as mentioned
above from 1,3-dimethoxybenzene (35 mmol), 15% hex-
ane solution of butyllithium (33 mmol), and TMEDA
(0.1 ml), was added a solution of disulfur dichloride
(0.8 ml, 10 mmol) in diethyl ether (45 ml) at 0°C under
argon. The mixture was stirred at r.t. for 6 h, water
(100 ml) was added, and the precipitates could be
recrystallized from ethanol to give F2S (8.4ꢀ5.6
mmol); m.p. 153–154°C; MS [m/z (rel. intensity)] 306
(100, M+). Anal. Found: C, 62.72; H, 5.92%. Calc. for
C16H18O4S1: C, 62.60; H, 5.91%. The aqueous layer was
acidified using 6 M hydrochloric acid to give FSH (8.7
mmol) [5,6].
2.3.3. b2Te
To a suspension of FLi, prepared as mentioned
above from 1,3-dimethoxybenzene (6 mmol), 15% hex-
ane solution of butyllithium (6 mmol) and TMEDA
(0.1 ml) under argon, was added a solution of FTeTeF
(2.65 g, 5 mmol) in benzene (50 ml). The mixture was
stirred at r.t. for 15 h, water (70 ml) was added, and the
grey precipitates could be recrystallized from acetone to
give light brown crystals of F2Te (4.0ꢀ3.3 mmol); m.p.
191–192°C; MS [m/z (rel. intensity)] 404 (67, M+), 77
(100). Anal. Found: C, 47.68; H, 4.66%. Calc. for
C16H18O4Te1: C, 47.81; H, 4.51%. On standing the
aqueous layer in air for 2 days, brown crystals of crude
FTeTeF (1.40 mmol) were obtained.
2.3.2. b2Se
To a suspension of FLi, prepared as mentioned
above from 1,3-dimethoxybenzene (15 mmol), 15% hex-
ane solution of butyllithium (15 mmol) and TMEDA
(0.02 ml) under argon, was added a solution of FSeSeF
(5.90 g, 13.6 mmol) in benzene (30 ml). The mixture
was stirred at r.t. for 15 h, water (30 ml) was added,
and the mixture was heated to dissolve the precipitates.
The organic layer was separated, the volatile materials
2.3.4. bSeH
The suspension of FLi was prepared as mentioned
above in 80 mmol scale of butyllithium, to which was

M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
285
added dry tetrahydrofuran (100 ml), lithium chloride
(3.4 g), and elemental selenium (4.74 g, 60 mmol) under
argon. The mixture was stirred in the dark at r.t. for 15
h to give a reddish–brown suspension. It was extracted
with cold water (ca. 100 ml), and to the aqueous layer
was added aqueous 6 M hydrochloric acid (21 ml). It
was cooled at 0°C overnight to give orange crystals,
which could be recrystallized from hexane to give FSeH
(45 mmol); m.p. 58–59°C; IR 2320 cm−1 (Se–H).
Anal. Found: C, 43.97; H, 4.52%. Calc. for
C8H10O2Se1: C, 44.25; H, 4.64%.
2.4.2. [b2SeOH]ClO4 and b2SeO · H2O
To a suspension of F2Se (0.708 g, 2 mmol) in acetic
acid (20 ml) was added 30% aqueous hydrogen perox-
ide (0.28 ml) to give an orange solution. It was diluted
with water (100 ml), and 60% aqueous perchloric acid
(0.32 ml) was added to give white crystals of
[F2SeOH]ClO4 in 87–79% yield after recrystallization
from ethanol; m.p. 139°C (decomposed explosively,
Caution!); IR 3340 (OH), 1100 (ClO4) cm−1. This salt
(0.470 g, 1 mmol) was suspended in 1 M sodium
hydroxide (5 ml) for 0.5 h, and the resultant solution
was extracted with dichloromethane (30 ml), from
which white crystals of F2SeO·H2O were obtained in
87–71% yield; m.p. 164–166°C. Anal. Found: C, 49.39;
2.4. Preparations of bis(2,6-dimethoxyphenyl) sulfoxide,
selenoxide and telluroxide
’
H, 5.19. Calc for C16H18O5Se H2O: C,49.62;H,5.21%.
2.4.1. b2SO
To a suspension of F2S (0.612 g, 2 mmol) in acetic
acid (5 ml) was added 30% aqueous hydrogen peroxide
(0.22 ml), and the mixture was stirred at r.t. for 8 h.
The resultant precipitates were washed with 1.5 M
sodium hydroxide and then with water, and they were
recrystallized from toluene to give F2SO in 83–64%
yield; m.p. 185–188°C decomposed); IR 1050 cm−1
(SꢀO); MS [m/z (rel. intensity)] 306 (95, F2S+), 151
(100). Anal. Found: C, 59.59; H, 5.86%. Calc. for
C16H18O5S1: C, 59 61; H, 5.63%.
2.4.3. [b2TeOH]ClO4 and b2TeO · (2/3)H2O
To a suspension of F2Te (0.804 g, 2 mmol) in acetic
acid (10 ml) was added 30% aqueous hydrogen perox-
ide (0.30 ml) to give a colorless solution. It was diluted
with water (40 ml), and 60% aqueous perchloric acid
(0.40 ml) was added to give light yellow crystals of
[F2TeOH]ClO4 in 88–83% yield after recrystallization
from ethanol; m.p. 143°C (decomposed explosively,
Caution!); IR 3480 (OH), 1100 (ClO4) cm−1. This salt
(0.518 g, 1 mmol) was treated in 1 M sodium hydroxide
as mentioned above to give white crystals of F2TeO · (2/
3)H2O in 71% yield; m.p. 193–195°C. Anal. Found: C
44.50; H, 4.49. Calc. for C16H18O5Te·(2/3)H2O: C,
44.70; H, 4.53%.
Table 2
13C-NMR spectral data for 2,6-dimethoxyphenyl derivatives of sul-
fur, selenium and telluriuma
2.5. Preparations of methyl-bis(2,6-dimethoxyphenyl)-
sulfonium, -selenonium and -telluronium salts
Compounds
lb
2.5.1. [Meb2S]X (X=MeSO4, ClO4)
F2S
112.2, 160.1, 104.2, 128.1, 56.2
109.2, 160.0, 104.2, 128.4, 56.1
96.2, 161.3, 103.6, 129.2, 56.0
114.0, 161.2, 103.8, 130.9, 56.0
109.6, 160.9,103.8, 130.7, 56.1
90.6, 162.1, 103.4, 130.5, 56.1
107.4, 156.7, 104.0, 126.3, 56.2
120.8, 159.2, 104.6, 131.9, 56.2
119.2, 160.2, 104.7, 132.3, 56.2
To a mixture of F2S (1.53 g, 5 mmol) and 1,2-
dichloroethane (0.4 ml) was added dimethyl sulfate (0.5
ml, 5 mmol), and the mixture was heated at 55°C
overnight. The resultant suspension was washed with
diethyl ether (25 ml×3) and by benzene (35 ml) to
leave white solid of [MeF2S]MeSO4 in 89% yield, m.p.
119–127°C; IR 1255 cm−1 (MeSO4).
To an aqueous solution of [MeF2S]MeSO4 (0.5
mmol/10 ml) was added 60% aqueous perchloric acid (a
slight excess), and the resultant precipitates were recrys-
tallized from ethanol or water to give colorless crystals
of [MeF2S]ClO4 in 48% yield; m.p. 202°C (decom-
posed); IR 1100 and 625 cm−1 (ClO4). Anal. Found: C,
48.27; H, 4.94%. Calc. for C17H21Cl1O8S1: C, 48.52; H,
5.03%).
F2Se
F2Te
FSSF
FSeSeF
FTeTeF
FSeH
F2SO
F2SeO · H2O
F2TeO · (2/3)H2O –c, 162.2, 104.6, 132.6, 56.1
[MeF2S]ClO4
–c, 160.3, 105.3, 136.3, 57.0; 27.2(Me–S)
[MeF2Se]ClO4
[MeF2Te]ClO4
[F2SOMe]ClO4
[F2SeOMe]2SO4
[F2TeOMe]2SO4
[F2SOEt]ClO4
[F2SeOEt]2SO4
–c, 159.8, 105.4, 135.0, 56.8; 24.4 (Me–Se)
–c, 161.7, 105.0, 134.8, 56.6; 7.9 (Me–Te)
103.3, 160.4, 105.4, 138.9, 57.3; 63.6 (OMe)
110.4, 160.0, 105.3, 135.6, 56.8; 54.5 (OMe)
–c, 161.7, 105.3, 135.6, 56.7; 54.5 (OMe)
103.8, 160.3, 105.4, 138.7, 57.3; 74.5, 15.5 (OEt)
110.7, 160.2, 105.3, 135.4, 56.8; 63.5, 15.1 (OEt)
Me2SnCl2 · 2F2SO –c, 159.4, 104.9, 132.5, 56.3; 11.1 (Me–Sn)
Me2SnCl2 · 2F2SeO 116.1, 160.1, 105.0, 133.3, 56.4; 13.6 (Me–Sn)
2.5.2. [Meb2Se]X (X=MeSO4, ClO4)
To a mixture of F2Se (1.76 g, 5 mmol) and 1,2-
dichloroethane (1 ml) was added dimethyl sulfate (0.7
ml, 7 mmol), and the mixture was stirred overnight. It
a In CDCl3; F=2,6-(MeO)2C6H3.
b In the order of C(1), C(2,6), C(3,5), 2,6-MeO; and others.
c The C(1) resonance could not be observed.

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M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
was washed with diethyl ether (10 ml×3) to leave a
white solid of [MeF2Se]MeSO4 in quantitative yield, as
2.6.3. [b2TeOMe]2SO4
Yield 64%; m.p. 124–126 °C (decomposed).
1
characterized by H- and 13C-NMR spectra; m.p. 120–
123°C (decomposed); IR 1255 cm−1 (MeSO4).
To an aqueous solution of [MeF2Se]MeSO4 (0.5
mmol/5 ml) was added 60% aqueous perchloric acid (a
slight excess), and the resultant precipitates were recrys-
tallized from ethanol or water to give colorless crystals
of [MeF2Se]ClO4 in 56% yield; m.p. 166–167°C (de-
composed); IR 1100 and 625 cm−1 (ClO4). Anal.
Found: C, 43.69; H, 4.59%. Calc. for C17H21Cl1O8Se1:
C, 43.65; H, 4.53%).
2.6.4. [b2SOEt]CIO4
Yield 60–48%; m.p. 121–123 °C (decomposed).
2.6.5. [b2SeOEt]2SO4
Yield 75%; m.p. 120–123 °C (decomposed).
2.7. Formation of dimethyltin dichloride complexes of
bis(2,6-dimethoxyphenyl) sulfoxide, selenoxide and
telluroxide
2.7.1. Me2SnCl2 · 2b2SO
2.5.3. [Meb2Te]X (X=MeSO4, ClO4)
To a solution of Me2SnCl2 (1 mmol) in toluene (50
ml) was added F2SO (2 mmol), and the mixture was
stirred for 5 min to give white precipitates of the 1:2
adduct in 61% yield; m.p. 189–190°C (decomposed).
In an analogous manner to those mentioned above
using F2Te, both [MeF2Te]MeSO4 and [MeF2Te]ClO4
were prepared as colorless crystals in 78 and 63%
yields, respectively. [MeF2Te]MeSO4, m.p. 126–131°C
(decomposed); IR 1255 cm−1 (MeSO4). [MeF2Te]ClO4
(recrystallized from ethanol), m.p. 211–213°C (decom-
posed); IR 1100 and 625 cm−1 (ClO4). Anal. Found: C,
39.34; H, 4.08%. Calc. for C17H21Cl1O8Te1: C, 39.54; H,
4.10%.
Anal. Found: C, 47.12;
H
4.94%. Calc. for
C34H42Cl2O10S2Sn1: C, 47.24; H4.90%. The 1:2 adduct
was obtained even though the ratio of Me2SnCl2 and
F2SO was varied to 1:1 or 2:1.
2.7.2. Me2SnCl2 · 2b2SeO
To a solution of F2SeO H2O (1.5 mmol) in 2-
’
propanol (10 ml) was added Me2SnCl2 (1 mmol), and
the mixture was stirred for 1 h to give white precipi-
tates, which were recrystallized from ethanol to give
white crystals of the 1:2 adduct in 73% yield; m.p.
195–197°C. Anal. Found: C, 42.46; H 4.36%. Calc. for
C34H42Cl2O10Se2Snl: C, 42.62; H 4.42%.
2.6. Preparations of alkoxy-bis(2,6-dimethoxyphenyl)-
sulfonium, -selenonium and -telluronium salts
2.6.1. [b2SOMe]ClO4
A mixture of F2SO (1 mmol), 1,2-dichloroethane (0.2
ml), and dimethyl sulfate (0.1 ml) was heated at 60°C
for 1.5 h. It was washed with diethyl ether repeatedly (5
ml×3) and was extracted with water (15 ml). Perchlo-
ric acid (1 M, 1.5 ml) was added at 0°C to form white
precipitates, which were recrystallized from ethanol to
give crystals of [F2SOMe]ClO4 in 54–41% yield; m.p.
135–139°C (decomposed); IR 1100 cm−1 (ClO4). This
compound was characterized by 1H- and 13C-NMR
spectra, since recrystallization resulted in partial hy-
drolysis to give [F2SOH]ClO4.
2.8. Rate measurement
Reaction rates were determined by conductimetry for
solutions containing ArnE or ArnEO (0.01 M) in Table
3 and alkyl halide or dimethyl sulfate (0.20–0.80 M) in
acetonitrile in a boiling chloroform bath at 61.2°C.
Correlation coefficients were greater than 0.9998 except
for very fast reactions (Ph3Sb, F2TeO). The results are
summarized in Table 3. 2,6-Dimethoxyphenyl deriva-
tives of Group 15 elements in Table 3 were prepared as
described elsewhere [1,6].
2.6.2. [b2SeOMe]2SO4
A
mixture of F2SeO · H2O (1 mmol), 1,2-
dichloroethane (0.2 ml) and dimethyl sulfate (0.2 ml)
was stirred at r.t. for 1 h to give a clear solution. It was
washed with diethyl ether repeatedly (5 ml×3) to give
brown crystals of [F2SeOMe]2SO4 in 74% yield; m.p.
118–121°C (decomposed). This compound was charac-
3. Results and discussion
3.1. Preparation and properties of 2,6-dimethoxyphenyl
chalcogenides
1
terized by H-and 13C-NMR spectra, since recrystalliza-
2,6-Dimethoxyphenyllithium, FLi, is easily prepared
as a suspension by the reaction of 1,3-dimethoxyben-
zene and butyllithium in the presence of a catalytic
amount of tetramethylethylenediamine [1]. In contrast
to phenyllithium, FLi is poorly soluble in hydrocarbons
and diethyl ether, and its reactivity is often very poor.
tion resulted in partial hydrolysis to give
[F2SeOH]ClO4.
In essentially analogous manners to those above, the
following compounds were obtained using dialkyl sul-
fate at 60°C or at r.t.

M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
287
Table 3
FTeTeF. While all the diphenyl chalcogenides, Ph2E
(E=S, Se, Te), are liquid at r.t., all of F2E are crys-
talline with higher melting points than 120°C. These
chalcogenides F2E are also thermally stable, and the
GC-MS spectra also showed clearly the parent peaks,
M+.
Rate constants for the reactions, Eqs. (1) and (2)
RX
ArnE or ArnEO k2
(1 mol−1 s−1 a
Relative rate r
)
(MeO)2SO2 F2S
F2Se
9.23×10−5
1.13×10−3
3.13×10−2
7.72×10−3
2.20×10−4
1.63×10−4
2.61×10−2
1.39×10−3
4.47×10−2
1.0
0.99992
12.2
339
83.6
2.4
1.8
283
15
484
0.99992
0.99998
0.99994
0.99998
0.99920
0.99986
0.99996
0.99987
All of F2E (E=S, Se, Te) reacted with dimethyl
sulfate in dichloroethane to give the onium salts,
[MeF2E]MeSO4, which were soluble in water and could
be converted to the perchlorates for pure isolation.
It has long been known that the nucleophilic reaction
rates of Group 15 compounds, R3M, with alkyl halides
decrease in the order M=(NB) P\As\Sb [8–10],
which is parallel with the first ionization potential in
photoelectron spectra of Ph3M (M=P, 7.37; As, 7.60;
Sb, 7.80 eV) [11], as well as with the Brønsted basicity
[12,13], the dipole moment [8,9], and the Lewis basicity
to boron Lewis acids in gas-phase (calorimetry, et al.)
[14,15]. In contrast, little work has been reported on the
comparison of nucleophilic reaction rates of Ph2E,
probably due to their poor nucleophilicities. It has been
reported that the reaction of Ph2Se with bromine is
slower than that of Ph2Te [16]. Due to the higher
nucleophilicity of F2E than Ph2E, we could observe the
rates of reaction between F2E and dimethyl sulfate by
conductimetry, which clearly increased in the order
E=SBSeBTe with a relative ratio of 1:12:339 (Table
3). We also confirmed that the rates of reaction between
Ph3M and dimethyl sulfate decreased in the order M=
P\As\Sb with a relative ratio of 83.6:2.4:1.8, the
rate of F3Sb is faster than that of Ph3P, and that the
rate of F2Te is faster than that of Ph3P and slightly
faster than that of F3Sb (Table 3). With butyl bromide,
the reaction of F2Te also is faster than Ph3P, but it
attained equilibrium. The reaction of F2Te with butyl
iodide was very fast, but it also attained equilibrium. Of
special interest is the reversed reactivities between
Group 15 and 16 derivatives.
F2Te
Ph3P
Ph3As
Ph3Sb
F3Sb
F2SO
SeO · H2O
F2TeO · (2/3)H2O Too fast
\1000
BuBr
BuI
F2Te
(1.7×10−3 b
3.52×10−5
)
0.99991
0.99995
0.99999
0.99992
0.99997
Ph3P
F3PO
F3AsO
F3SbOc
(4.3×10−5 b
)
5.63×10−3
2.78×10−3
F2Te
(1.1×10−2 b
)
0.99997
a By conductimetry for solutions containing ArnE (or ArnEO) (0.01
M) and RX (0.20–0.80 M) in acetonitrile, at 61.2°C; kobs
k2[ArnE][RX]; F=2,6-(MeO)2C6H3.
=
b The reaction attained equilibrium.
c See the manuscript for the reaction.
In fact, while it reacted with elemental sulfur in hex-
ane–benzene to give the suspension of FSLi, it reacted
with neither elemental selenium nor with tellurium un-
der the analogous conditions or even in THF, although
2,4,6-trimethoxyphenyllithium has been reported to re-
act with elemental tellurium [7].
However, it was found incidentally that the reactions
proceeded in the presence of lithium chloride in THF to
give FSeLi or FTeLi. Magnesium chloride or iodide
was also effective in place of lithium chloride. The role
of these inorganic salts is not clear at present, but it is
expected that they form double salts with LiF to make
them soluble in the solvent. The reagents FELi (E=S,
Se, Te), thus prepared, could be oxidized in water using
hydrogen peroxide to give bis(2,6-dimethoxyphenyl)
dichalcogenides, FEEF (E=S, Se, Te), as light yellow
(S), orange (Se) or dark brown (Te) crystals with much
higher melting points than diphenyl dichalcogenides,
PhEEPh. These dichalcogenides, FEEF, are thermally
stable, and the GC-MS spectra showed clearly the
parent peaks, M+.
When [MeF2S]MeSO4 was treated with potassium
iodide in water, F2S began to precipitate immediately.
An
analogous
reaction
was
observed
for
[MeF2Se]MeSO4 with potassium iodide to give F2Se. In
order to see the relative reactivity and/or stability, a 1:1
mixture of [MeF2S]MeSO4 and [MeF2Se]MeSO4 was
treated in water with a half equimolar amount of
potassium iodide, and F2Se was obtained almost selec-
tively. Treatments of [MeF2Se]MeSO4 with piperidine
and triethylamine also resulted in very fast demethyla-
tions to give F2Se, and treatments with aqueous sodium
hydroxide and aqueous sodium bromide resulted in
A reaction of LiF with disulfur dichloride gave
bis(2,6-dimethoxyphenyl) sulfide, F2S, and 2,6-
dimethoxybenzenethiol,
FSH.
Bis(2,6-dimethoxy-
phenyl) selenide, F2Se, was prepared by the reaction of
LiF with FSeSeF, which formed 2,6-dimethoxyben-
zeneselenol, FSeH, as the by-product. Bis(2,6-
dimethoxyphenyl) telluride, F2Te, was prepared by the
reaction of LiF with FTeTeF, where the expected
by-product, FTeH, was air-sensitive to be oxidized to
slow
and
partial
demethylations.
When
[MeF2Te]MeSO4 was treated with aqueous potassium
iodide, anion exchange gave precipitates of [MeF2Te]I.
1
The H-NMR spectrum of [MeF2Te]I in chloroform-d1,
however, showed a partial decomposition to give F2Te
and iodomethane. These observations suggest that the

288
M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
E+ –Me bond strengths of [F2EMe]+ increase in the
order E=SeBSBTe, which is consistent with the
order of equilibrium constant observed for reactions
between Ph2E (E=S, Se) and methyl iodide [17,18].
The equilibrium constant of reactions between R3M
(M=P, As, Sb) and methyl iodide decreases in the
order M=P\As\Sb [17,18], which suggests that the
[R3M–Me]+ bond strength decreases in the order
M=P\As\Sb.
(Caution!: these salts are explosive.) When these salts
were treated with aqueous sodium hydroxide, we ob-
tained the oxides as the hydrates, F2SeO · H2O and
F2TeO · (2/3)H2O. The precise formulations of these
oxides are not known at present. Organometal (or
-metalloid) oxides of heavier elements (Sn, Sb, Te, I)
are apt to take polymeric structures or they dissolve in
forms of hydroxide [26–30]. The GC spectrum of
F2SO showed that it partially decomposed to F2S dur-
ing the measurement, and mass spectrum of F2SO
showed strong peak due to F2S+. Both F2SeO · H2O
and F2TeO · (2/3)H2O also decomposed during the GC
measurements completely to F2Se and F2Te, respec-
tively.
While [MeF2Te]I in solution gave equilibrium mix-
tures containing F2Te and iodomethane, [MeF3Sb]I
was stable in solution. This indicates that the F3Sb+
–
Me bond is stronger than the F2Te+ –Me bond as
well as the Me–I bond.
Oxidation potentials of Ph2E (electrochemical E0/V
vs. NHE=1.56 (S), 1.38 (Se), 0.95 (Te)) [19], Me(4-
RC6H4)E [19,20], Me2E [20], MePhE [20,21], and
FEEF [22] have been reported to decrease in the order
E=S\Se\Te, while those of phenoxachalcogenides,
C12H8OE [23], and chalcanthrenes, C12H8E2 [24,25],
studied both by photoelectron spectroscopy and
semiempirical MO calculation, have been reported by
somewhat different orders such as Se\S\Te. The
former order (S\Se\Te) parallels the rate order of
reactions between F2E and dimethyl sulfate (SBSeB
Te), while the latter parallels the E+ –Me bond
strength order of [F2E-Me]+(SeBSBTe).
Thus, the reactivity orders of F2E and Ar3M are
found to be parallel with the oxidation potentials re-
ported for Ph2E and Ph3M, respectively. There then
arises the question, why the oxidation potential orders
of Ph2E and Ph3M reverse the respective element or-
ders? Based on electronegativity consideration, the oxi-
dation potential of Group 15 elements is expected to
decrease in the order P\As\Sb, the reverse order of
experimental observation [11].
Essentially in an analogous manner to that ex-
plained for the oxidation potentials [11], we also ex-
plain the reactivity order P\As\Sb by the fact that
the three phenyl groups compensate the electronegativ-
ity of M enough to increase the nucleophilicity of the
non-bonded electron pair in the order.
The other question is why the bond strength order
(SeBSBTe) is not parallel with the element order. At
present, we have no appropriate explanation and fur-
ther works are in progress.
Treatments of F2EO (E=S, Se, Te) with dialkyl
sulfate in 1,2-dichloroethane resulted to give their
alkoxonium salts, [F2EOR]X (R=Me, Et). The reac-
tions of F2EO were faster than those of F2E and the
rates increased also in the order E=SBSeBTe
(Table 3). The order may be related with the basicity
or the E–O bond polarity of F2EO (F2E+ –O−). In
contrast, an unusual order of reactivity was observed
for the reaction of F3MO with butyl bromide; M=
PBAs]Sb (Table 3). The reactivity orders except for
the position of Sb paralleled with the electronegativity
orders of these Group 15 and 16 elements, respec-
tively, where the M–O and E–O bond polarities of
F3M+ –O− and F2E+ –O− must increase in the re-
verse order to electronegativity. The pKa values of
Ph3MO and Ph2EO have been studied in water, and
the Brønsted basicity increases in the order of
Ph2SOBPh3POBPh2SeOBPh3AsO [31]. The basicity
and the dipole moment of R3MO and/or R2EO also
have been known to increase in the parallel orders of
M=PBAsBSb and E=SBSeBTe, which are the
reverse orders of M–O or E–O bond dissociation
energy [1,32–34]. Analogous orders have been ob-
served for the basicity, SꢀSeBPBAsBSb, and the
nucleophilicity, PBSBSeBAsBSb, of PhnM=
C5Ph4 [35]. The rates of deuterium exchange of
[(CH3)4M]+ and [(CH3)3E]+ decrease in the orders of
M=(N)BP\As\Sb and E=S\Se\Te, respec-
tively, which must reflect the Brønsted basicity orders
of the intermediate ylides [36]. The poorer reactivity of
F3SbO than F3AsO with butyl bromide is tentatively
attributed to the polymeric property of the former [1].
While we obtained 1:1 adducts of F3PY (Y=O, S)
with dimethyltin dichloride even though F3PY was
used in excess [2], both F2SO and F2SeO · H2O formed
2:1 adducts with dimethyltin dichloride even though
the ratio of F2SO and Me2SnCl2 was varied to 1:1 or
1:2. However, F2TeO · (2/3)H2O reacted with
dimethyltin dichloride to give complex mixtures. Most
probably F2TeO · (2/3)H2O reacted as a Brønsted base
to form partial hydrolysis product of dimethyltin
dichloride.
3.2. Preparation and properties of
bis(2,6-dimethoxyphenyl) sulfoxide, selenoxide and
telluroxide
Treatment of F2S with hydrogen peroxide in acetic
acid resulted in the precipitation of the oxide, F2SO.
In contrast, F2SeO and F2TeO, thus prepared, are
highly soluble, and treatment of the aqueous solutions
with perchloric acid gave precipitates of [F2EOH]ClO4

M. Wada et al. / Journal of Organometallic Chemistry 580 (1999) 282–289
289
3.3. H- and 13C-NMR spectra
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show a triplet due to 4-protons, a doublet due to
3,5-protons and a very sharp singlet due to 2,6-methoxy
protons. In general, as expected, cationic compounds
showed the resonances at lower magnetic field than
neutral compounds. The 4-proton resonance shifts, in
general, to higher magnetic fields in the order E=SB
SeBTe
with
exceptions
for
F2E
and
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order. 2,6-Methoxy proton resonance is the most sensi-
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exception for FEEF. The methyl proton resonance, as
well as the carbon resonance, of [MeF2E]ClO4 also is
sensitive to E and shifts to a higher magnetic field in the
order E=SBSeBTe. These results of chemical shift
are not in accord with the well-known electronegativity
order of chalcogenides, S5Se\Te. There is, however,
a possibility that the true electronegativity order is
S\Se\Te, which explains the general trend of the
proton chemical shifts. In contrast, the proton reso-
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)
observed for
SnMe2Cl2 · 2F2EO is larger for E=SSne than S, suggest-
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to be observed, but it shifts to a higher magnetic field in
the order E=SBSeBTe for FEEF and F2E. How-
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other four resonances due to the F-group are far less
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Acknowledgements
This work was supported by the Grant-in-Aid for
Scientific Research No. 08455492 from the Ministry of
Education, Science and Culture.
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