U.-P. Apfel et al. / Journal of Organometallic Chemistry 696 (2011) 1084e1088
1085
hydroxide (1.44 g, 36 mmol) was slowly added and the solution was
stirred for 4 days. Subsequently, the reaction mixture was acidified
with HCl to pH w3 and water (100 mL) was added. The solution was
extracted three times with diethyl ether (50 mL) and the combined
organic phases were dried with sodium sulfate. Removal of the
solvent under reduced pressure followed by bulb-to-bulb distilla-
ꢀ
1
Scheme 1. Representative [FeFe] hydrogenase model complexes [Fe
CH S) )] A and [Fe (CO) [(HO) )] B as well as the novel synthesized complexes
and 8.
2
6
(CO) (HOCH
tion (0.34 mbar, 50 C) afforded 191 mg (31%) of a yellow oil. H
NMR (400 MHz, CDCl ): ),
¼ 3.39e3.31 (m, 4H, CH and OCH
.78e2.71 (m, 4H, SCH ), 1.43 (t,
H,H ¼ 8.4 Hz, 2H, SH). C NMR
50 MHz, CDCl ): ), 26.0 (CH ). MS (DEI):
(
4
2
2
2
6
2
C
H
6 2
S
2
d
3
3
3
13
2
(
2
J
3
d
¼ 82.4 (CH), 57.4 (OCH
3
2
þ
2
. Experimental section
m/z ¼ 138 [M] . Elemental analysis was not performed due to the
volatility of the compound.
2.1. General
2 6 3 2 2
2.4. Synthesis of {Fe (CO) [H COCH(CH S) ]} (4)
All syntheses were carried out under an inert atmosphere. The
organic solvents used were dried and purified according to standard
2-Methoxypropane-1,3-dithiol (3) (50 mg, 0.36 mmol) and
procedures. Chemicals were used as received from Fluka or Acros
triiron dodecacarbonyl (182 mg, 0.36 mmol) were dissolved in
toluene (25 mL) and the solution was refluxed for 2 h. After evap-
oration to dryness, the crude product was purified via FC (diethyl
ether:hexane ¼ 1:10) yielding 115 mg (76%) of a red crystalline
product. Anal. calcd. for C H Fe O S ·Et O (416.29): C 34.31%; H
without further purification. [Fe
synthesized according to literature [12]. Thin layer chromatography
TLC): Merck silica gel 60 F254 plates; detection under UV light at
54 nm. Flash chromatography (FC): Fluka silica gel 60. A Büchi GKR-
2 6 2 2
(CO) (HOCH(CH S) )] A, was
(
2
10
8
2
7
2
2
1
1
5
1 apparatus was used for the bulb-to-bulb distillations. The H and
3.70%; S 13.08%. Found: C 34.20%; H 3.69%; S 13.52%. H NMR
13
1
ꢀ
3
C{ H} NMR spectra were recorded at 23 C on a Bruker Avance 200
or Avance 400 NMR spectrometer. Analysis and assignment of the
(400 MHz, CDCl ):
d
¼ 3.26 (s, 3H, OCH ), 2.76 (dd, J
¼ 3.8 Hz,
3
3
H,H
2
JH,H ¼ 13 Hz, 2H, CH H ), 2.72e2.64 (m, 1H, CH), 1.55e1.49 (m, 2H,
A
B
1
1
1
13
1
13
13
data were supported by H, H COSY, H, C HMQC, H, C HMBC and
DEPT 135 experiments. Chemical shifts (ppm) were determined
relative to the H and C signal from the solvent CDCl
CH H ). C NMR (50 MHz, CDCl ):
d
¼ 207.6/207.3 (CO), 81.5 (CH),
1
A
B
3
ꢁ
56.5 (OCH ), 26.88 (CH ). IR (KBr, cm ): 2073(vs), 2030 (vs), 1982
3
2
1
13
þ
þ
3
. IR spectra
(vs), 1947 (s). MS (DEI): m/z ¼ 388 [M ꢁ CO] , 360 [M ꢁ 2CO] , 332
þ
þ
þ
þ
were recorded on a PerkineElmer 2000 FT-IR spectrometer, mass-
spectrometric studies (DEI/MS) were performed on a SSQ710 Fin-
nigan MAT spectrometer and elemental analyses (C, H, N, S) were
carried out on a Leco CHNS-931 instrument.
[M ꢁ 3CO] , 304 [M ꢁ 4CO] , 276 [M ꢁ 5CO] , 246 [M ꢁ 6CO] .
2.5. Synthesis of 3-bromo-2-methylprop-1-ene (5) [17]
A suspension of 3-chloro-2-methylprop-1-ene (10 g, 0.11 mol)
and lithium bromide (15 g, 0.17 mol) was stirred for 12 h in 50 mL of
boiling acetone. Water (10 mL) was added to the reaction mixture;
the organic fraction was separated from the aqueous phase and was
dried using magnesium sulfate. Removal of the solvent under
reduced pressure and distillation of the residue (atm. pressure,
2
.2. Synthesis of 1,3-dithioacetyl-2-methoxy-propane (2)
Allylbromide (20 g, 165 mmol) and mercury(II) acetate (30 g,
7.7 mmol) were dissolved in methanol (300 mL) and stirred for 10
5
days at room temperature whereupon a white precipitate was
formed. After filtration and removal of the solvent to the oily
substance 400 mL of water were added. After addition of potassium
ꢀ
1
85e87 C) afforded 3 g (21%) 3-bromo-2-methylprop-1-ene.
NMR (200 MHz, CDCl ):
H
3
d
¼ 5.10 (m, 1H, cis-CH), 4.92 (m, 1H, trans-
ꢀ
þ
bromide (20 g, 168 mmol) and cooling to 0 C, bromine (26.3 g,
CH), 3.93 (s, 2H, CH Br), 1.86 (s, 3H, CH ). MS (DEI): m/z ¼ 134 [M] .
2
3
165 mmol) was slowly dropped into the stirred solution. After 3 h,
The purity was verified via GCeMS.
the mixture was extracted with diethyl ether (100 mL), washed
with water and saturated sodium thiosulfate solution. Removal of
2.6. Synthesis of 1,3-dibrom-2-methyl-2-hydroxypropane (6) [18]
the solvent under reduced pressure and bulb-to-bulb distillation
ꢀ
(
0.06 mbar, 50 C) yielded 10.2 g of crude 2-methoxy-1,3-dibrom-
3-Bromo-2-methylprop-1-ene (5) (2 g, 0.015 mol) was dissolved
þ
propane (1) [16]. MS(DEI): m/z ¼ 230 [M] . The crude product was
in a mixture of dimethylsulfoxide (90 mL) and water (0.5 mL), and
ꢀ
used in the next step without further purification.
the solution was cooled to ꢁ10 C. Afterwards, N-bromosuccini-
Potassium thioacetate (20 g, 175 mmol) was slowly added to
a solution of 2-methoxy-1,3-dibrompropane (10 g, 43.5 mmol) in
acetone (120 mL). After 1 week, the reaction mixture was filtered to
remove the precipitate which was washed several times with
acetone. The filtrate was evaporated under reduced pressure and
the residue was redissolved in diethyl ether, filtered again and
concentrated in vacuo. Bulb-to-bulb distillation (0.15 mbar, 110 C)
afforded 3.3 g (37%) of a yellow oil. Anal. calcd. for C
222.33): C 43.22%; H 6.35%; S 28.85%. Found: C 42.58%; H 5.85%; S
mide (5.27 g, 0.03 mol) was added in small portions within 15 min
and the mixture was stirred for an additional hour. The reaction was
stopped by addition of water (50 mL) which results in bleaching of
the solution. After extraction with diethyl ether (3 ꢂ 50 mL), the
organic phase was washed with saturated sodium chloride.
Removal of the solvent under reduced pressure followed by
ꢀ
ꢀ
Kugelrohr distillation (0.71 mbar, 55 C) afforded 1.62 g (47%) of
1
8
H
14
O
3
S
2
1,3-dibrom-2-methyl-2-hydroxypropane.
H NMR (400 MHz,
2
3
(
2
OCH
CDCl ):
d
¼ 3.54 (dd, J
¼ 13.8 Hz, J
¼ 10.4 Hz, 4H, CH ), 2.38
3
H,H
H,H
2
1
13
9.18%. H NMR (200 MHz, CDCl
3
):
d
¼ 3.45e3.33 (m, 4H, CH and
(s, 1H, OH), 1.47 (s, 3H, CH ). C NMR (100 MHz, CDCl ):
d
¼ 71.0
3
3
3
13
þ
3
), 3.06 (d, JH,H ¼ 5.8 Hz, 4H, SCH
2
), 2.32 (s, 6H, SC(O)CH
¼ 195.1 (SC(O)CH ), 78.6 (CH), 57.6 (OCH
); 30.5 (SC(O)CH
). MS (DEI): m/z ¼ 222 [M] .
3
).
C
),
(COH), 40.5 (CH ), 23.2 (CH ). MS (DEI): m/z ¼ 137 [MeCH Br] .
2
3
2
NMR (50 MHz, CDCl
3
):
d
3
3
þ
3
1.7 (CH
2
3
2.7. Synthesis of 4-methyl-4-hydroxy-1,2-dithiolane (7)
2
.3. Synthesis of 2-methoxypropane-1,3-dithiol (3)
1,3-Dibrom-2-methyl-2-hydroxypropan (6) (1.6 g, 6.9 mmol)
was added to sodium hydrogensulfide monohydrate (2.05 g,
0.028 mol) dissolved in absolute ethanol (40 mL). The resulting
solution was refluxed for 2 h, whereupon a white precipitate
To an ice-cooled solution of 1,3-dithioacetyl-2-methoxy-
propane (2) (1 g, 4.5 mmol) dissolved in methanol (20 mL), sodium