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and Celite (Fluka AG) were activated at 120 ꢀC for one
day before chromatographic use. Bibenzyltrisulfide was
purchased from Sigma. [CpCr(CO)3]2 (1) was synthe-
sized as described by Manning [14] from chromium
hexacarbonyl (99% purity from Merck).
2.3. Reaction of [CpCr(CO)3]2 (1) with Bz2S3 at 60 ꢀC
To a deep green solution of 1 (200 mg, 0.498 mmol) in
toluene (20 mL) was added bibenzyl trisulfide (139 mg,
0.498 mmol) and was stirred for 5 h at 60 ꢀC. The result-
ant dark brown reaction mixture was concentrated to
ca. 2 mL and loaded onto a silica gel column (1.5 · 8
cm) prepared in n-hexane. Elution gave two fractions:
2.2. Reaction of [CpCr(CO)3]2 (1) with Bz2S3 at
ambient temperature
(i) A dirty green solution in n-hexane–toluene (1:1, 45
mL) which yielded dark green crystalline solids of
[CpCr(CO)2]2S (3) (152 mg, 0.402 mmol, 80.8%
yield).
(ii) A deep purple solution in toluene–ether (3:1, 25
mL) which yielded dark purple crystalline solids
of [CpCr(SBz)]2S (5) (35 mg, 0.068 mmol, 13.7%
yield). A greenish blue layer remained uneluted at
the top rim of the column.
To a deep green solution of [CpCr(CO)3]2 (1) (200
mg, 0.497 mmol) in toluene (15 mL) was added Bz2S3
(138 mg, 0.497 mmol). The dirty green mixture was al-
lowed to stir at ambient temperature for 2 h. The result-
ant yellowish brown reaction mixture was concentrated
to ca. 2 mL in vacuo and then loaded onto a silica gel
column (1.5 · 10 cm) prepared in n-hexane. The follow-
ing fractions were eluted:
(i) A yellowish brown fraction in n-hexane–toluene
(2:1) (35 mL) which when concentrated to dryness
yielded deep green crystalline solids of
[CpCr(CO)2]2S (3) (108 mg, 0.286 mmol, 57.4%
yield).
(ii) A dark brown fraction in toluene (25 mL) which
when concentrated to dryness yielded dark brown
crystalline solids of [CpCr(CO)2(SBz)]2 (4) (98
mg, 0.166 mmol, 33.3% yield). 1H NMR (ben-
zene-d6): d 4.16 (s, Cp). 13C NMR (benzene-d6):
d 89.61 (s, Cp). IR: m (CO) at 1986 s, 1954 m,
1901 vs cmÀ1 (nujol), or 1991 vs, 1968 vs, sh,
1918 vs (toluene); other bands, 1066 vw, 1025
vw, 840 w, 722 w cmÀ1 (nujol). MS: m/z 149
[CpCrS], 205 [CpCr(CO)2S], 378 [CpCr(CO)2]2S,
2.4. Reaction of [CpCr(CO)2]2 (2) with Bz2S3
A deep green solution of 2 (200 mg, 0.578 mmol) in
toluene (20 mL) containing bibenzyl trisulfide (161 mg,
0.578 mmol) was stirred for 72 h at ambient tempera-
ture. The resultant dirty brown reaction mixture was fil-
tered through Celite, concentrated and loaded onto a
silica gel column (1.5 · 10 cm) prepared in n-hexane.
Two fractions were eluted: (i) a dirty green solution in
n-hexane–toluene (1:1, 45 mL) which gave dark green
crystalline solids of 3 (5 mg, 0.008 mmol, 5.1% yield)
and (ii) a deep purple solution in toluene–ether (3:1,
35 mL) which gave dark purple crystalline solids of 5
(135 mg, 0.264 mmol, 15.8% yield).
401
[CpCr4S4],
237
[CpCr(CO)2S2],
261
2.5. Thermolysis of [CpCr(CO)2(SBz)]2 (4)
CpCr(CO)4S, 346 [CpCr(CO)4Bz2S], 468 [Cp4Cr4],
596 [Cp4Cr4S4], 560 [Cp2Cr2(CO)4Bz2S], 592
[Cp2Cr2(CO)4Bz2S2]. Anal. Calc. for C28H24Cr2-
O4S2: C, 56.15; H, 4.35; Cr, 17.25; O, 10.37; S,
10.59. Found: C, 56.76; H, 4.05; Cr, 17.57; S,
10.81; O, 10.81%.
A stirred dark brown solution of 4 (100 mg, 0.169
mmol) in toluene (10 mL) was maintained at 80 ꢀC for
ca. 1 h. The resultant dirty brown solution was filtered
through Celite (1 cm disk), concentrated (ca. 1 mL)
and loaded onto a silica gel column (1.5 · 6 cm) pre-
pared in n-hexane. Two fractions were eluted: (i) a dirty
green fraction in n-hexane–toluene (2:1, 25 mL) which
gave dark green crystalline solids of 3 (39 mg, 0.103
mmol, 36.0% yield) and (ii) a deep purple solution in
ether (25 mL) which gave dark purple crystalline solids
of 5 (40 mg, 0.078 mmol, 27.4% yield).
(iii) A purple fraction in ether (10 mL) which when
concentrated to dryness yielded dark purple crys-
talline solids of [CpCrSBz]2S (5) (11 mg, 0.021
mmol, 4.3% yield). 1H NMR (benzene-d6): d
13.89 (br, Cp, m1/2 = 57 Hz). 13C NMR (ben-
zene-d6): d 101.03 (s, Cp), d 133.14, 135.60 (s,
Cp). IR: m at 1063 vw, 1015 vw, 840 w, 732 w
cmÀ1 (nujol). MS: m/z 149 [CpCrS], 295 [CpCr2S],
2.6. Thermolysis of [CpCr(SBz)]2S (5)
360
[Cp2Cr2S],
371[Cp2Cr2Bz2S],
401
[CpCr4S4], 480 [Cp2Cr2Bz2S2], 512 [Cp2Cr2Bz2S3].
Anal. Calc. for C24H24Cr2S3: C, 56.25; H, 4.68;
Cr, 20.31; S, 18.75. Found: C, 56.57; H, 4.15;
Cr, 19.59; S, 18.31%. A greenish blue frac-
tion remained uneluted at the top of the
column.
A stirred deep purple solution of 5 (100 mg, 0.195
mmol) in toluene (10 mL) was maintained at 100 ꢀC
for 20 h. The resultant dirty purple solution was filtered
through Celite (1 cm disk), concentrated (ca. 1 mL) and
loaded onto a silica gel column (1.5 · 6 cm) prepared in
n-hexane–toluene (1:1). Two fractions were eluted: (i) a