Organometallics
Article
MHz, CD2Cl2, δ): 205.95 (m, CO), 165.92 (t, JP−C = 8.1 Hz, ArC),
150.88 (s, ArC), 121.94 (m, ArC), 90.77 (t, JP−C = 7.0 Hz, ArC),
41.31 (s, N(CH3)2), 32.56 (t, JP−C = 13.0 Hz, CH(CH3)2), 17.07 (t,
JP−C = 2.2 Hz, CH(CH3)2), 16.87 (s, CH(CH3)2). 31P{1H} NMR
(162 MHz, C6D6, δ): 227.87 (s). 31P{1H} NMR (162 MHz, CD2Cl2,
δ): 228.28 (s). Selected ATR-IR data (solid, cm−1): 1965 (s, νCO),
1906 (s, νCO). Anal. Calcd for C22H36NO4P2Co: C, 52.91; H, 7.27.
Found: C, 52.66; H, 7.34.
with chilled (−78 °C) methanol (6 mL × 2). The remaining solid was
dried under vacuum to yield a red powder (0.50 g, 59% yield). The
NMR and IR data matched with those reported in the literature.16
Synthesis of {2,6-(iPr2PO)2C6H3}Co(CNtBu)(CO) (3a). Under an
argon atmosphere, to a solution of {2,6-(iPr2PO)2C6H3}Co(CO)2
t
(100 mg, 0.22 mmol) in 15 mL of THF was added BuNC (152 μL,
1.35 mmol). The resulting mixture was stirred at 50 °C for 24 h, at
which point the mixture changed from yellow to orange. The volatiles
were removed under reduced pressure, and the orange-yellow residue
was washed with chilled (0 °C) methanol (0.5 mL × 3). The
remaining solid was dried under vacuum to afford a yellow powder
(40 mg), which was analyzed as a 4:1 mixture of 3a and 4a. A few
single crystals of 3a were obtained from a pentane solution of the
Synthesis of {2,6-(iPr2PO)2-4-OMe-C6H2}Co(CO)2 (1c). This
compound was prepared in 86% yield (as a yellow solid) by a
1
procedure similar to that used for 1a. H NMR (400 MHz, CD2Cl2,
δ): 6.13 (s, ArH, 2H), 3.71 (s, OCH3, 3H), 2.70−2.41 (m,
1
CH(CH3)2, 4H), 1.76−0.99 (m, CH(CH3)2, 24H). H NMR (400
1
MHz, C6D6, δ): 6.48 (s, ArH, 2H), 3.32 (s, OCH3, 3H), 2.32−2.17
(m, CH(CH3)2, 4H), 1.27−1.03 (m, CH(CH3)2, 24H). 13C{1H}
NMR (101 MHz, CD2Cl2, δ): 205.57 (t, JP−C = 13.1 Hz, CO), 165.37
(t, JP−C = 8.1 Hz, ArC), 159.41 (s, ArC), 126.64 (t, JP−C = 22.2 Hz,
mixture kept at −30 °C. H NMR (400 MHz, C6D6, δ): 6.84−6.76
(m, ArH, 3H), 2.46−2.36 (m, CH(CH3)2, 4H), 1.39−1.23 (m,
CH(CH3)2, 24H), 0.88 (s, C(CH3)3, 9H). 13C{1H} NMR (101 MHz,
C6D6, δ): 208.33 (m, CO), 165.81 (t, JP−C = 9.1 Hz, ArC), 163.20 (m,
CNtBu), 140.71 (t, JP−C = 23.7 Hz, ArC), 123.70 (s, ArC), 104.04 (t,
JP−C = 5.9 Hz, ArC), 55.33 (s, C(CH3)3), 32.90 (t, JP−C = 11.6 Hz,
CH(CH3)2), 32.51 (t, JP−C = 10.6 Hz, CH(CH3)2), 30.25 (s,
C(CH3)3), 17.82 (t, JP−C = 2.5 Hz, CH(CH3)2), 17.59 (s,
CH(CH3)2), 17.40 (s, CH(CH3)2), 17.32 (t, JP−C = 2.5 Hz,
CH(CH3)2). 31P{1H} NMR (162 MHz, C6D6, δ): 229.10 (s).
Selected ATR-IR data (solid, cm−1): 2092 (m), 2060 (m), 1899 (s,
νCO).
ArC), 91.63 (t, JP−C = 7.1 Hz, ArC), 55.79 (s, OCH3), 32.71 (t, JP−C
=
13.1 Hz, CH(CH3)2), 17.12 (br, CH(CH3)2), 16.94 (s, CH(CH3)2).
31P{1H} NMR (162 MHz, C6D6, δ): 229.31 (s). 31P{1H} NMR (162
MHz, CD2Cl2, δ): 229.61 (s). Selected ATR-IR data (solid, cm−1):
1965 (s, νCO), 1908 (s, νCO). Anal. Calcd for C21H33O5P2Co: C,
51.86; H, 6.84. Found: C, 52.11; H, 6.92.
Synthesis of {2,6-(iPr2PO)2-4-CO2Me-C6H2}Co(CO)2 (1d). This
compound was prepared in 84% yield (as a yellow solid) by a
Synthesis of {2,6-(iPr2PO)2C6H3}Co(CNtBu)2 (4a). Under an
argon atmosphere, to a solution of {2,6-(iPr2PO)2C6H3}Co(CO)2
(0.50 g, 1.1 mmol) in 35 mL of THF was added tBuNC (0.75 mL, 6.6
mmol). The resulting mixture was stirred at 80 °C for 48 h, at which
point the mixture changed from yellow to orange. The volatiles were
removed under reduced pressure, and the orange-yellow residue was
treated with 40 mL of pentane and filtered into another Schlenk flask
via a cannula. The filtrate was concentrated under vacuum to give an
orange solid, which was washed with chilled (0 °C) methanol (1.5 mL
× 3). The remaining solid was dried under vacuum to afford the
product as an orange fine powder (0.27 g, 43% yield). 1H NMR (400
MHz, C6D6, δ): 6.82−6.76 (m, ArH, 3H), 2.59−2.50 (m, CH(CH3)2,
4H), 1.47−1.42 (m, CH(CH3)2, 12H), 1.40−1.35 (m, CH(CH3)2,
12H), 1.00 (s, C(CH3)3, 18H). 13C{1H} NMR (101 MHz, C6D6, δ):
1
procedure similar to that used for 1a. H NMR (400 MHz, CD2Cl2,
δ): 7.04 (s, ArH, 2H), 3.80 (s, CO2CH3, 3H), 2.59−2.48 (m,
CH(CH3)2, 4H), 1.31−1.23 (m, CH(CH3)2, 24H). 13C{1H} NMR
(101 MHz, CD2Cl2, δ): 204.63 (t, JP−C = 14.1 Hz, CO), 167.39 (s,
CO2CH3), 165.52 (t, JP−C = 8.1 Hz, ArC), 149.57 (t, JP−C = 21.2 Hz,
ArC), 127.08 (s, ArC), 104.89 (t, JP−C = 6.1 Hz, ArC), 51.95 (s,
CO2CH3), 32.77 (t, JP−C = 13.1 Hz, CH(CH3)2), 17.01 (br,
CH(CH3)2), 16.83 (s, CH(CH3)2). 31P{1H} NMR (162 MHz,
CD2Cl2, δ): 229.45 (s). Selected ATR-IR data (solid, cm−1): 1975 (s,
νCO), 1919 (s, νCO), 1708 (vCO). Anal. Calcd for C22H33O6P2Co: C,
51.37; H, 6.47. Found: C, 51.82; H, 6.48.
Synthesis of {2,6-(Ph2PO)2C6H3}Co(CO)2 (1e). In a glovebox,
1,3-(Ph2PO)2C6H4 (1.22 g, 2.55 mmol) dissolved in 20 mL of toluene
was added dropwise to a Schlenk flask containing a solution of
Co2(CO)8 (0.35 g, 1.02 mmol) in 15 mL of toluene. The flask was
taken outside of the glovebox, connected to a Schlenk line, and heated
with stirring at 110 °C for 24 h. The volatiles were removed under
reduced pressure, and the red oily residue was washed first with
pentane (20 mL, 10 mL × 2) and then with chilled (0 °C) methanol
(1.5 mL × 3). The resulting solid was dried under vacuum to afford
the product as a red powder (1.15 g, 95% yield). 1H NMR (400 MHz,
CD2Cl2, δ): 7.70−7.45 (m, ArH, 20H), 6.89 (t, JH−H = 7.8 Hz, ArH,
1H), 6.64 (d, JH−H = 7.8 Hz, ArH, 2H). 13C{1H} NMR (101 MHz,
C6D6, δ): 203.65 (t, JP−C = 10.1 Hz, CO), 163.71 (t, JP−C = 10.1 Hz,
ArC), 138.81 (t, JP−C = 25.3 Hz, ArC), 137.98 (t, JP−C = 24.2 Hz,
ArC), 131.08 (s, ArC), 131.00 (t, JP−C = 7.1 Hz, ArC), 128.72 (t, JP−C
= 5.1 Hz, ArC), 126.4 (s, ArC), 106.33 (t, JP−C = 8.1 Hz, ArC).
13C{1H} NMR (101 MHz, CD2Cl2, δ): 203.40 (m, CO), 163.09 (t,
172.69 (m, CNtBu), 165.55 (t, JP−C = 11.1 Hz, ArC), 143.09 (t, JP−C
=
25.3 Hz, ArC), 122.34 (s, ArC), 103.51 (t, JP−C = 6.1 Hz, ArC), 54.82
(s, C(CH3)3), 33.11 (t, JP−C = 9.1 Hz, CH(CH3)2), 30.79 (s,
C(CH3)3), 18.20 (t, JP−C = 3.1 Hz, CH(CH3)2), 18.17 (s,
CH(CH3)2). 31P{1H} NMR (162 MHz, C6D6, δ): 225.93 (s).
Selected ATR-IR data (solid, cm−1): 2077 (m), 2043 (m), 1912 (m,
br). Anal. Calcd for C28H49N2O2P2Co: C, 59.36; H, 8.72; N, 4.94.
Found: C, 58.80; H, 8.81; N, 4.82.
General Procedure for the Catalytic Hydrosilylation of
Aldehydes. To a 50 mL Schlenk flask were added 1b (10 mg, 0.020
mmol), an aldehyde (2.0 mmol), (EtO)3SiH (406 μL, 2.2 mmol), and
2 mL of THF. The resulting mixture was exposed to a Schlenk line
filled with argon and stirred at 50 °C for 12 h. The reaction mixture
was then quenched with a 10% aqueous solution of NaOH (∼5 mL)
and stirred vigorously at 50 °C for 24 h. The organic product was
extracted with Et2O (20 mL × 3) or CH2Cl2 (20 mL × 3, for products
from 4-(dimethylamino)benzaldehyde and 2-naphthaldehyde), dried
over anhydrous MgSO4, and concentrated under vacuum. If needed,
the alcohol product could be further purified by flash column
chromatography (with 20% ethyl acetate in hexanes as eluent). The
1H and 13C{1H} NMR spectra of the primary alcohol products are
J
P−C = 9.9 Hz, ArC), 138.48 (t, JP−C = 24.7 Hz, ArC), 137.52 (t, JP−C
= 24.4 Hz, ArC), 131.52 (s, ArC), 130.91 (t, JP−C = 7.1 Hz, ArC),
128.91 (t, JP−C = 5.3 Hz, ArC), 126.15 (s, ArC), 105.93 (t, JP−C = 7.1
Hz, ArC). 31P{1H} NMR (162 MHz, C6D6, δ): 191.41 (s). 31P{1H}
NMR (162 MHz, CD2Cl2, δ): 189.89 (s). Selected ATR-IR data
(solid, cm−1): 2001 (s, νCO), 1936 (s, νCO). Anal. Calcd for
C32H23O4P2Co: C, 64.88; H, 3.91. Found: C, 65.13; H, 4.13.
Synthesis of {2,6-(tBu2PO)2C6H3}Co(CO) (2f). In a glovebox, a
solution of 1,3-(tBu2PO)2C6H4 (0.70 g, 1.76 mmol) in 20 mL of
toluene was added dropwise to a Schlenk flask containing Co2(CO)8
(0.30 g, 0.88 mmol) predissolved in 15 mL of toluene. The flask was
taken outside of the glovebox, connected to a Schlenk line, and heated
with stirring at 110 °C for 36 h. After the mixture was cooled to room
temperature, the volatiles were removed under vacuum. The resulting
purple-red solid was treated with 40 mL of pentane and 60 mL of
diethyl ether and then filtered through a pad of Celite. The filtrate was
concentrated under vacuum to give a wine red solid, which was rinsed
X-ray Structure Determinations. Single crystals of 1a−d, 3a,
and 4a were obtained from pentane solutions kept at −30 °C. Single
crystals of 1e were obtained from a THF solution kept at −30 °C.
Crystal data collection and refinement parameters are provided in the
K on a Bruker PHOTON100 CMOS detector at Beamline 11.3.1 at
the Advanced Light Source (Lawrence Berkeley National Laboratory)
using synchrotron radiation tuned to λ = 0.7749 Å. Intensity data for
1b,d were collected at 150 K on a Bruker APEX-II CCD
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Organometallics XXXX, XXX, XXX−XXX