558 J. Am. Chem. Soc., Vol. 119, No. 3, 1997
Allgeier et al.
solid product (1.072 g, 78%). Analytically pure samples were obtained
via recrystallization from ethanol. 1H NMR (C6D6): δ 3.97 (m, Fc
protons, 4H), 3.72 (m, Fc protons, 4H), 3.59 (t, OCH2, JH-H ) 5.5 Hz,
4H). 3.22 (t, CH2Cl, JH-H ) 5.5 Hz, 4H). HREIMS [M+]: Calcd,
m/z 341.9877; found, m/z 341.9872. Anal. Calcd for C14H16O2Cl2Fe:
C, 49.02; H, 4.70. Found: C, 48.87; H, 4.78.
silica and chromatographed in a glovebox. After treatment with 10%
Et2O in hexane to remove HPPh2, THF was used to elute the product,
which was isolated as yellow-orange solid (189 mg, 50%). 1H NMR
(CDCl3): δ 4.26 (dd, JH-H ) 1.9 Hz, 4H, Fc); 4.21 (dd, JH-H ) 1.9
Hz, 4H, Fc); 2.60 (m, 4H, CH2S); 2.25 (m, 4H, CH2P). 31P{1H} NMR
(CDCl3): δ -16.6 (s). FABMS [M+]: m/z 674. Anal. Calcd for
C38H36FeS2P2: C, 67.66; H, 5.38. Found: C, 67.02; H, 5.46.
2,2′-Bis(2-dicyclohexylphosphinoethoxy)-1,1′-binapthalene (4b).
A 2.0 M solution of butyllithium in pentane (0.9 mL, 1.8 mmol) was
added to a 15 mL THF solution of dicyclohexylphosphine (0.31 mL,
1.53 mmol) cooled to 0 °C. The resulting solution turned yellow-orange
over 1 h, at which time it was transferred dropwise to a 30 mL THF
solution of 2,2′-bis(2-chloroethoxy)-1,1′-binapthalene at 0 °C. The clear
solution was stirred for 10 h at 0 °C and 10 h at -78 °C. It was directly
chromatographed on alumina with 1:9 diethyl ether/pentane in a
glovebox to yield a colorless oil (271 mg, 50%), which was stored at
-40 °C in a glovebox freezer. 1H NMR (CDCl3): δ 8.0-7.8 (m, 4H,
aromatic); 7.5-7.0 (m, 4H, aromatic); 4.1 (m, 6H, CH2); 3.36 (t, JH-H
) 6.5 Hz, 2H, CH2); 1.8-0.9 (m, 44H, cyclohexyl). 31P{1H} NMR
(CDCl3): δ -10.9 (s). HRFABMS [M‚H+]: Calcd, m/z 735.4460;
found, m/z 735.4474.
Rhodium(I) [1,1′-Bis(2-diphenylphosphinoethoxy)ferrocene]-
tetrafluoroborate (5). In a typical preparation (η2-CH2CH2)4Rh2(µ-
Cl)2 (71.4 mg, 0.184 mmol) and AgBF4 (72 mg, 0.37 mmol) were mixed
as solids. Upon addition of 3-5 mL of THF a cloudy mixture
immediately formed. After stirring for 45 min a gray-black precipitate
was filtered off through Celite leaving an orange filtrate, which was
diluted (150 mL THF) and cooled to -40 °C. A solution of 1,1′-bis-
(2-diphenylphosphinoethoxy)ferrocene (3a) (236 mg, 0.367 mmol in
25 mL THF) was added dropwise via an addition funnel over 20 min.
After stirring for 1 h, the orange solution was warmed to room
temperature and the solvent removed in Vacuo, yielding 5 as an orange
powder (spectroscopic yield > 95%). Single crystals of 5 were obtained
by slow diffusion of pentane into a THF solution of the product. 1H
NMR (CD2Cl2): δ 7.5-7.2 (m, Ph, 20H); 4.75 (m, Fc protons, 4H);
4.10 (m, Fc protons, 4H); 3.75 (m, CH2O, 4H); 3.69 (m, THF, 4H),
2.62 (m, CH2P, 4H), 1.83 (m, THF, 4H). 31P{1H} NMR (CD2Cl2): δ
61.1 (d, JRh-P ) 210 Hz). HRFABMS [M+]: Calcd, m/z 745.0595;
found: m/z 745.0623.
Rhodium(I) [1,1′-(2-Dicyclohexylphosphinoethoxy)ferrocene]-
tetrafluoroborate (6). A mixture of [RhCl(C8H14)2]x (53.5 mg, 0.15
mmol), AgBF4 (29 mg, 0.15 mmol), and 3 mL of THF was stirred for
1 h. After filtration through Celite the resulting orange filtrate was
diluted to 50 mL with THF and cooled to -40 °C. A 3 mL THF
solution of 1,1′-(2-dicyclohexylphosphinoethoxy)ferrocene (3b) (100
mg, 0.15 mmol) was added dropwise. The orange reaction solution
was stirred for 1 h and then concentrated in Vacuo. Upon addition of
excess hexane a pure orange powder precipitated from solution (71
mg, 55%). 1H NMR (CD2Cl2): δ 4.63 (dd, JH-H ) 2.0 Hz, 4H, Fc);
4.04 (dd, JH-H ) 2.0 Hz, 4H, Fc); 3.92 (dt, 4H, JH-H ) 6.6 Hz, JH-P
) 16.5 Hz, CH2O); 2.44 (m, 4H, ring CHP); 2.1-1.2 (m, 44H, CH2P
and Cy). 31P{1H} NMR (CD2Cl2): δ 68.3 (d, JRh-P ) 203 Hz).
FABMS [M+]: m/z 769.
Rhodium(I) [2,2′-Bis(2-dicyclohexylphosphinoethoxy)-1,1′-bi-
napthalene]tetrafluoroborate (8). A 4 mL portion of THF was added
to a mixture of [RhCl(C8H14)2]x (27 mg, 0.075 mmol) and AgBF4 (16
mg, 0.08 mmol) at room temperature. After 30 min a gray-black
precipitate was filtered away, and the orange filtrate was diluted to 75
mL and cooled to -78 °C. Following slow addition of a THF solution
of 2,2′-bis(2-dicyclohexylphosphinoethoxy)-1,1′-binapthalene]tetrafluo-
roborate (4b) (55 mg, 0.075 mmol) the reaction mixture was stirred
for 2 h, while warming to -10 °C. The solution was concentrated in
Vacuo to 7 mL at < -10 °C, and the product precipitated after addition
of 35 mL pentane. The product was purified via slow precipitation
from a pentane/dichloromethane mixture to yield 33 mg (48%) of
orange solid. When stored for periods longer than 2 h, the product
was cooled to e -40 °C. 31P{1H} NMR (CD2Cl2): δ 72.6 (d, JRh-P
) 203 Hz). FABMS [M+]: m/z 837.
1,1′-Bis(2-diphenylphosphinoethoxy)ferrocene (3a). A 0.5 M
solution of potassium diphenylphosphide (3.4 mL, 1.7 mmol) in THF
was diluted with 50 mL of THF and cooled to -10 °C. A solution of
1,1′-bis(2-chloroethoxy)ferrocene (0.14 g, 0.41 mmol) in THF was
added dropwise to the mixture through an addition funnel. The mixture
was slowly warmed to room temperature and stirred overnight. The
resulting orange solution contained a white precipitate, which presum-
ably was KCl. An Et2O/H2O extraction provided an orange-yellow
organic layer which was dried over MgSO4 and evaporated to an orange
oil. Column chromatography in a glovebox (silica gel, benzene eluent)
and recrystallization from ethanol provided an orange microcrystalline
product (0.25 g, 96%). 1H NMR (C6D6): δ 7.44 (m, Ph, 8H), 7.06
(m, Ph, 12H), 3.92 (m, Fc protons and OCH2, 8H), 3.66 (m, Fc protons,
4H), 2.46 (t, CH2P, JH-H ) 7.9 Hz, 4H). 31P{1H} NMR (C6D6): δ
21.9 (s). HRFABMS [M+]: Calcd, m/z 642.1540; found: m/z
642.1529. Anal. Calcd for C38H36FeO2P2: C, 71.04; H, 5.65.
Found: C, 70.45; H, 5.75.
1,1′-Bis(2-dicyclohexylphosphinoethoxy)ferrocene (3b). A 2.0 M
pentane solution of butyllithium (0.9 mL, 1.78 mmol) was added to a
colorless solution of dicyclohexylphosphine (0.32 mL, 1.58 mmol) in
15 mL of THF at 0 °C. After 50 min the resulting orange solution
was added dropwise to a solution of 1,1′-(2-chloroethoxy)ferrocene (252
mg, 0.74 mmol) in 20-25 mL of THF at 0 °C. After 8 h of slowly
warming to room temperature the orange reaction mixture was
evaporated onto alumina (predried at 0.02 mm Hg) and chromato-
graphed in a glovebox with 1:4 diethyl ether/pentane to yield a pure
orange oil (293 mg, 60%). 1H NMR (CDCl3): δ 4.05 (dd, JH-H ) 1.9
Hz, 4H, Fc); 3.86 (m, 4H, CH2O); 3.81 (dd, JH-H ) 1.9 Hz, 4H, Fc);
1.86-1.62 (m, 24H, CH2P and cyclohexyl); 1.56 (m, 4H, ring CHP);
1.35-1.05 (m, 20H, cyclohexyl). 31P{1H} NMR (CDCl3): δ -11.1
(s). HREIMS [M+]: Calcd, m/z 666.3418; found, m/z 666.3419. Anal.
Calcd for C38H60FeO2P2: C, 68.46; H, 9.07. Found: C, 68.62; H, 9.14.
2-Chloroethyldisulfide. This reaction was not carried out under
airfree conditions. Pyridine (5.3 mL, 0.064 mol) was added via syringe
to a 40 mL THF solution of 2-hydroxyethyldisulfide (2.0 mL, 0.016
mol) and thionyl chloride (4.8 mL, 0.064 mol). The resulting mixture
developed white and yellow precipitates as it became warm. After 18
h the reaction mixture was treated with water and extracted with ether.
Drying over Na2SO4 and removal of solvent provided a clean orange
brown liquid (2.54 g, 83%). Precipitates from the reaction mixture
were soluble in the aqueous layer, which was orange. 1H NMR
(CDCl3): δ 3.75 (t, JH-H ) 7.5 Hz, 4H, CH2Cl); 3.00 (t, JH-H ) 7.5
Hz, 4H, CH2S).
1,1′-Bis(2-chloroethylthio)ferrocene. To a solution of N,N,N ′,N ′-
tetramethylethylenediamine (1.6 mL, 10.6 mmol) in 20 mL of hexane
was added 2.0 M butyllithium in pentane (5.25 mL, 10.5 mmol). A
white precipitate developed below the pale yellow solution. Upon slow
addition of a saturated solution of ferrocene (0.974 g, 5.24 mmol) in
hexane an orange precipitate formed. After 31/2 h of stirring the reaction
mixture was cooled to 0 °C and diluted to 80 mL. 2-Chloroethyldis-
ulfide (2.08 g, 10.9 mmol) was added via syringe, and the reaction
mixture became brown as it was stirred overnight and warmed to room
temperature. Following an aqueous/ether extraction and drying over
MgSO4, the crude product was chromatographed on silica with 5%
ether in hexane. The product was isolated as an orange solid upon
removal of solvent (259 mg, 13%). A significant quantity of ferrocene
was recovered from the reaction product mixture. 1H NMR (CDCl3):
δ 4.31 (dd, JH-H ) 1.8 Hz, 4H, Fc); 4.25 (dd, JH-H ) 1.8 Hz, 4H, Fc);
3.52 (t, JH-H ) 8.0 Hz, 4H, CH2Cl); 2.83 (t, JH-H ) 8.0 Hz, CH2S).
HREIMS [M+]: Calcd, m/z 373.9420; found: m/z 373.9416. Anal.
Calcd for C38H36FeP2S2: C, 67.66; H, 5.38. Found: C, 67.02; H, 5.46.
1,1′-Bis(2-diphenylphosphinoethylthio)ferrocene (3c). Potassium
diphenylphosphide solution (2.6 mL of 0.5 M in THF, 1.3 mmol) was
added dropwise to a solution of 1,1′-bis(2-chloroethylthio)ferrocene (212
mg, 0.56 mmol) in 15 mL of THF, cooled to 0 °C. After 12 h and
warming to room temperature the reaction mixture was evaporated onto
Rhodium(I) [1,1′-Bis(2-diphenylphosphinoethylthio)ferrocene]-
(tetrafluoroborate) (9). A mixture of [RhCl(C8H14)2]x (27.3 mg, 0.076
mmol), AgBF4 (15 mg, 0.077 mmol), and 5 mL of THF was stirred
for 45 min. After filtration of a grey precipitate through Celite, the