8764 J. Am. Chem. Soc., Vol. 120, No. 34, 1998
Aubart and Bergman
transfer transition state for this reaction. Although minor, this
contribution is still important in the reaction of 3 with diaryl
disulfides.
18 h during which time it became a homogeneous, dark brown solution.
The volatile materials were removed in vacuo, and the residue was
washed with pentane (3 × 5 mL). The brown powder left behind was
dried in vacuo, dissolved in toluene (7 mL), and layered with pentane
(
8 mL). After 1 d, the solvents had diffused together and the mixture
was cooled to -30 °C. After 18 h, 2a (0.077 g, 84% yield) was isolated
as dark brown platelike crystals, mp 125-127 °C (dec). 1H NMR (CD
Cl ): δ 8.99 (d, 2H, JH-H ) 8.7 Hz), 7.39 (d, 2H, JH-H ) 8.7 Hz),
6.95 (m, 3H), 5.37 (s, 5H), 5.04 (s, 5H), 4.36 (s, 5H), 2.43 (s, 6H).
Experimental Section
2
-
2
General Procedure. Unless indicated, all manipulations were
carried out under an inert atmosphere in a Vacuum Atmospheres drybox
or by using standard Schlenk or vacuum line techniques. Solutions
were degassed by sequentially freezing to -196 °C, evacuating under
high vacuum, and thawing. This sequence was repeated three times
in each case. Glass reaction vessels fitted with ground glass joints
and Teflon stopcocks are referred to as bombs.
13
1
2 2
C{ H} NMR (CD Cl ): δ 191.0, 190.9, 127.1, 123.2, 119.4, 101.9,
99.0, 87.8, 24.1. Anal. Calcd for C25
Found: C, 49.95; H, 4.78.
H28CoSTa: C, 50.01; H, 4.70.
2
Cp Ta(µ-CH
2
)
2
6
Co(SC H
4
OCH
3 6 6
)Cp‚0.5 C H
(2b). In a 20-mL
vessel equipped with a magnetic stir bar, 1 (0.050 g, 0.11 mmol) was
suspended in toluene (6 mL). The yellow suspension was stirred, and
a solution of bis(p-methoxyphenyl) disulfide (0.021 g, 0.075 mmol) in
toluene (6 mL) was added dropwise over 2 min. The mixture was
stirred for 6 h during which time it became a homogeneous, red-violet
solution. The volatile materials were removed in vacuo, and the residue
was washed with cold pentane (4 × 5 mL, -30 °C). The residue was
dried in vacuo, dissolved in benzene (10 mL), and layered with pentane
1H, 13C, and 19F NMR spectra were obtained on either the 300-,
4
00-, or 500-MHz Fourier transform spectrometers at the University
of California, Berkeley (UCB) NMR facility. The 400- and 500-MHz
instruments were Bruker AM series spectrometers. Two additional
(300- and 400-MHz) instruments were Bruker AMX series spectrom-
eters, while some spectra were recorded on a 500-MHz Bruker DRX
series spectrometer.
(
7 mL). After 2 d, 2b (0.0434 g, 66% yield) was isolated as red-violet
crystals, mp 126-130 °C. The amount of benzene solvate was
quantified by NMR spectroscopy. 1H NMR (CD
Cl ): δ 8.81 (d, 2H,
H-H ) 8.4 Hz), 7.38 (d, 2H, JH-H ) 8.0 Hz), 7.32 (s, 3H), 6.76 (d,
IR spectra were recorded on a Mattson Galaxy series FT-IR 3000
spectrometer. Mass spectroscopic analyses were obtained at the UCB
mass spectrometry facility on AEI MS-12 and Kratos MS-50 mass
spectrometers. Elemental analyses were performed by the UCB
microanalytical lab. Melting points were recorded for compounds in
sealed capillary tubes under nitrogen and are uncorrected.
2
2
J
2
H, JH-H ) 8.4 Hz), 6.59 (d, 2H, J H1 -H ) 7.6 Hz), 5.33 (s, 5 H), 5.05
3 1
(s, 5H), 4.76 (s, 5H), 3.72 (s, 3H). C{ H} NMR (CD
2
Cl
2
): δ 155.9,
139.0, 133.5, 128.7, 117.0, 113.6, 102.7, 99.0, 88.3, 55.6. Anal. Calcd
for C27
H29CoOSTa: C, 50.56; H, 4.56. Found: C, 50.61; H, 4.51.
Unless specified, all reagents were purchased from commercial
suppliers and used without subsequent purification. Benzene, toluene,
diethyl ether, and pentane were distilled from sodium/benzophenone
ketyl under nitrogen. Acetone was dried over 4 Å molecular sieves
under nitrogen and subsequently distilled under vacuum. Methylene
chloride was distilled from calcium hydride under nitrogen. Benzene-
Cp
2
Ta(µ-CH Co(SC CH )Cp (2c). In a 20-mL vessel equipped
2
)
2
6
H
4
3
with a magnetic stir bar, 1 (0.0432 g, 0.0933 mmol) was suspended in
benzene (10 mL). The yellow suspension was stirred, and a solution
of di-p-tolyl disulfide (0.0162 g, 0.0657 mmol) in benzene (5 mL) was
added dropwise. The mixture was stirred for 8 h, during which time
it became a homogeneous, dark purple solution. The volatile materials
were removed in vacuo, and the residue was washed with pentane (4
5 mL) until the washings were colorless. The red powder left behind
was dried in vacuo. The powder was collected as analytically pure 2c
0.0516 g, 72% yield), mp 140-145 °C. H NMR (CD
d, 2H, JH-H ) 7.9 Hz), 7.34 (d, 2H, JH-H ) 7.9 Hz), 6.77 (m, 4H),
d
6
was vacuum transferred from sodium/benzophenone ketyl. Aceto-
nitrile, methylene-d chloride, and acetonitrile-d were vacuum trans-
ferred from calcium hydride. Paramagnetic Cp Ta(µ-CH CoCp (1)
2
3
×
2
2 2
)
2
2
was prepared according to the literature method. All disulfides were
recrystallized from diethyl ether at -30 °C under nitrogen. 2,6-
Dimethylphenylsulfenyl chloride was synthesized via the oxidation of
the corresponding thiol with chlorine gas dissolved in carbon tetra-
1
(
(
5
(
2 2
Cl ): δ 8.80
13
1
.32 (s, 5 H), 5.06 (s, 5H), 4.80 (s, 5H), 2.25 (s, 3H). C{ H} NMR
Cl ): δ 144.7, 132.0, 130.5, 128.4, 116.7, 102.7, 99.0, 88.2, 20.8.
CD
2
2
42
chloride, a general method for sulfenyl halide preparation. Preparation
of this compound by treating the corresponding thioester with thionyl
IR (KBr): 3111, 2916, 1734, 1655, 1639, 1630, 1595, 1479, 1439,
257, 1079, 1014, 906, 833, 808 cm . Anal. Calcd for C24H -
26
CoSTa: C, 49.16; H 4.47. Found: C, 49.20; H 4.76.
-1
1
4
3
chloride has been reported.
Bis(2,6-dimethylphenyl) Disulfide. In a fume hood, 2,6-dimeth-
ylthiophenol (0.22 mL, 1.6 mmol) was dissolved in diethyl ether (15
mL) in a 100-mL Schlenk flask equipped with a magnetic stir bar.
The colorless solution was stirred and cooled to 0 °C. A diethyl ether
Cp Ta(µ-CH ) Co(SC H )Cp‚C H (2d). In a 20-mL vessel
2
2
2
6
5
6
6
equipped with a magnetic stir bar, 1 (0.0965 g, 0.208 mmol) was
suspended in benzene (7 mL). The yellow suspension was stirred, and
a solution of diphenyl disulfide (0.0318 g, 0.146 mmol) in benzene (8
mL) was added dropwise over 3 min. The mixture was stirred for 3 h,
during which time it became a homogeneous, dark purple solution.
The volatile materials were removed in vacuo, and the residue was
washed with pentane (3 × 4 mL) until the washings were colorless.
The solid was dissolved in benzene (2 mL) and layered with pentane
(10 mL). After 1 d, 2d (0.0835 g, 66% yield) was isolated as dark
violet crystals, mp 129-132 °C. The amount of benzene solvate was
quantified by NMR spectroscopy. 1H NMR (CD Cl ): δ 8.82 (d, 2H,
(10 mL) solution of orange 2,6-dimethylphenylsulfenyl chloride (0.29
g, 1.7 mmol) was added, and the mixture turned slightly yellow. The
flask was capped with a rubber septum and allowed to stir for 1 h. The
volatile materials were removed in vacuo to leave a white residue which
was recrystallized from diethyl ether at -30 °C under nitrogen. Bis-
(
2,6-dimethylphenyl) disulfide (0.383 g, 85% yield) was isolated as
1
13
1
white crystals. The H and C{ H} NMR spectra of this material
matched that of bis(2,6-dimethylphenyl) disulfide prepared by alterna-
2
2
4
4,45
tive routes.
JH-H ) 7.8 Hz), 7.48 (d, 2H, JH-H ) 8.4 Hz), 7.35 (s, 6H), 6.96 (t,
JH-H ) 7.8 Hz), 6.82 (m, 1H), 6.78 (d, 2H, JH-H ) 8.4 Hz), 5.31 (s,
Cp Ta(µ-CH
2
2
)
2
Co(SC
6
H
3
(CH
3
)
2
)Cp (2a). In a 20-mL vessel
13
1
equipped with a magnetic stir bar, 1 (0.071 g, 0.15 mmol) was
suspended in toluene (5 mL). The yellow suspension was stirred, and
a solution of bis(2,6-dimethylphenyl) disulfide (0.0267 g, 0.0973 mmol)
in toluene (7 mL) was added dropwise. The mixture was stirred for
2 2
5H), 5.07 (s, 5H), 4.83 (s, 5H). C{ H} NMR (CD Cl ): δ 148.9,
131.7, 128.6, 127.4, 120.7, 116.6, 102.7, 99.0, 88.1. IR (KBr): 3115,
2954, 2914, 1732, 1572, 1452, 1435, 1425, 1263, 1078, 1020, 1011,
-
1
901, 841, 831, 822 cm . Anal. Calcd for C29
H 4.65. Found: C, 53.39; H 4.83.
H30CoSTa: C, 53.55;
(
42) Capozzi, G.; Modena, G. In The Chemistry of the Thiol Group; Patai,
S., Ed.; John Wiley & Sons Ltd: Great Britain, 1974; Vol. 2; p 791.
43) Cevasco, G.; Novi, M.; Petrillo, G.; Thea, S. Gazz. Chim. Ital. 1990,
20, 131.
Cp
2
2 2 6 4 3
Ta(µ-CH ) Co(SC H CF )Cp (2f). In a 20-mL vessel equipped
with a magnetic stir bar, 1 (0.075 g, 0.16 mmol) was suspended in
toluene (10 mL). The yellow suspension was stirred, and a solution
of bis[p-(trifluoromethyl)phenyl] disulfide (0.0391 g, 0.110 mmol) in
toluene (5 mL) was added dropwise over 2 min. The mixture became
a brown-orange homogeneous solution over the course of 2 min and
was allowed to stir for 18 h. The volatile materials were removed in
(
1
6
(
44) Fujihara, H.; Chiu, J.-J.; Furukawa, N. Bull. Chem. Soc. Jpn. 1991,
4, 699.
(
Soc. Jpn. 1989, 62, 3655.
45) Yamamoto, K.; Yoshida, S.; Nishide, H.; Tsuchida, E. Bull. Chem.