Organometallics
Article
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1
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3.2 (OMe), 54.5 (3H, OMe), 84.2 (C Me Ru), 93.6 (Ar), 95.9 (Ar),
08.1 (Ar), 122.5 (Ar), 129.3 (Ar), 133.5 (Ar), 151.0 (Ar), 152.5 (Ar),
59.3 (Ar), 181.8 ppm (Ar). Elemental analysis did not agree with the
(100 MHz, THF-d , −40 °C): δ 11.2 (C Me ), 11.6 (C Me ), 12.6
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(C Me ), 82.7 (C Me ), 89.7 (C Me ), 91.1 (C Me ), 106.1 (Ar),
5 5 5 5 5 5 5 5
4
117.0 (q, JCF = 31 Hz, C ), 126.1 (q, J = 270 Hz, −CF ), 144.6 (Ar),
CF
3
calculated value due to the inseparable impurity.
150.1 (Ar), 150.7 ppm (Ar). Anal. Calcd for C H CoF NRu : C, 53.00;
36 51 3 2
Reaction of 1 with 4-Picoline; Formation of Cp*Co(dmbpy)
H, 6.30; N, 1.72. Found: C, 53.16; H, 6.48; N, 1.65.
H/D Exchange between 13 with Pyridine-d . An NMR tube
equipped with a Teflon valve was charged with 13 (10.5 mg, 12.9 μmol)
(
10) and Cp* Ru (11). A glass tube equipped with a Teflon valve was
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charged with 1 (61.6 mg, 91.8 μmol), 4-picoline (20 μL, 230 μmol), and
heptane (4 mL). The reaction mixture was heated at 180 °C for 96 h.
The solution turned from brown to purple. 4,4′-Dimethoxybiphenyl
and pyridine-d (0.50 mL) with 2,2,4,4-tetramethylpentane (1.7 μL)
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as an internal standard. The reaction was carried out at 90 °C, and the
(
45 μmol in 1.5 mL of toluene) was then added to the tube as an internal
1
reaction was periodically monitored by H NMR spectroscopy. The
standard. Formation of 10 (40%) and 11 (25%) was quantitatively
1
H NMR spectrum recorded after 24 h showed that the intensity of the
1
analyzed by means of H NMR spectroscopy. Data for 10 are as follows.
hydrido ligands decreased to 34% due to deuteration. At the same time,
the intensity ratio of the residual ortho, meta, and para protons of
1
H NMR (400 MHz, benzened , rt): δ 1.65 (s, 6H, Me), 1.91 (s, 15H,
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3
C Me Co), 6.64 (d, J = 6.8 Hz, 2H, C H), 7.07 (s, 2H, C H),
.97 ppm (d, JHH = 6.8 Hz, 2H, C H). Data for 11 are as follows.
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HH
pyridine-d changed from 2.4:2.0:1.0 to 2.7:2.0:1.0.
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Reaction of 2 with 4-Picoline; Preparation of (Cp*Ru) -
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H NMR (400 MHz, benzene-d , rt): δ 1.64 ppm (s, 30H, C Me Ru).
(Cp*Rh)(μ-H) (μ -η (||)-C H NMe) (15). A glass tube equipped with
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Reaction of 1 with 4-Picoline; Preparation of (Cp*Ru) -
a Teflon valve and with a Teflon-coated stir bar was charged with 2
(82.5 mg, 0.115 mmol), 4-picoline (120 μL, 1.23 mmol), and toluene
2
{
(dmbpy)Co}(μ-H)(μ -H) (12). A glass tube equipped with a Teflon
3 2
valve and with a glass-coated stir bar was charged with 1 (54.1 mg,
0.6 μmol), 4-picoline (155 μL, 1.59 mmol), and toluene (8 mL). The
reaction mixture was stirred at 120 °C for 21 h. The solution turned from
brown to dark green. Removal of the solvent under reduced pressure
gave a dark green residual solid. The residue was washed five times with
(5 mL). The reaction mixture was stirred at 100 °C for 48 h. The
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solution turned from brown to purple. Removal of the solvent under
reduced pressure gave a purple residual solid. The residue was then
extracted five times with 3 mL of hexane, and the combined solution
was filtered through a glass filter (G4). Removal of the solvent under
reduced pressure followed by washing three times with 2 mL of
methanol gave 78.5 mg of 15 as a purple solid (0.0974 mmol, 85%).
A purple single crystal suitable for the XRD study was prepared by
4
mL of pentane to remove unreacted 1. The residue was then extracted
five times with 3 mL of toluene, and the combined solution was filtered
through a glass filter (G4). Removal of the solvent under reduced
pressure gave the crude product (29.6 mg, 41.2 μmol, 51%). Analytically
pure 12 was obtained by recrystallization from the toluene solution
stored at −30 °C (16.5 mg, 23.0 μmol, 27%). A green single crystal
suitable for the XRD study was prepared by recrystallization from
recrystallization from the mixed solvent of acetone and toluene in a
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2
:1 volume ratio at −30 °C. H NMR (400 MHz, THF-d , −80 °C):
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δ −22.13 (dd, J = 32.4 Hz, J = 4.0 Hz, 1H, Rh−H−Ru), −17.13 (d,
RhH
HH
J
= 21.1 Hz, 1H, Rh−H−Ru), −10.79 (d, J = 4.0 Hz, 1H, Ru−H−
1
RhH
HH
the m-xylene solution stored at −30 °C. 12: H NMR (400 MHz,
Ru), 1.62 (s, 15H, C Me Ru), 1.81 (s, 15H, C Me Ru), 1.85 (s, 15H,
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benzene-d , rt): δ −129.08 (br s, 6H, C Me), −27.68 (br s, 30H,
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C Me Rh), 2.04 (s, 3H, C Me), 5.92 (dd, J = 6.4, 1.2 Hz, 1H, C H),
.41 (d, JHH = 6.4 Hz, 1H, C H), 6.92 ppm (s, 1H, C H). H NMR
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HH
C Me Ru), 34.81 (br s, 2H, Ar), 81.47 (br s, 2H, Ar), 116.26 ppm (br s,
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2
H, Ar). μeff (Evans method, 298 K, benzene-d ): 2.5 μ . Elemental
6 B
(
1
(
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400 MHz, THF-d , rt): δ −19.24 (br s, 2H, Rh−H−Ru), −10.46 (s,
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analysis did not agree with the calculated value due to high sensitivity
toward air and moisture.
Dehydrogenative Coupling of 4-Picoline by 12. A glass tube
equipped with a Teflon valve was charged with 12 (13.4 mg, 18.6 μmol),
-picoline (36 μL, 370 μmol), and heptane (3.5 mL). The reaction
H, Ru−H−Ru), 1.74 (s, 30H, C Me Ru), 1.87 (s, 15H, C Me Rh), 2.02
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br s, 3H, C Me), 5.87 (dd, J = 6.4, 2.0 Hz, 1H, C H), 6.39 (d, J
=
HH
HH
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3
13
1
.4 Hz, 1H, C H), 6.96 ppm (s, 1H, C H). C{ H} NMR (100 MHz,
THF-d , −80 °C): δ 11.3 (C Me ), 11.6 (C Me ), 12.8 (C Me ), 20.7
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(
C Me), 80.7 (C Me Ru), 87.1 (C Me Ru), 96.3 (d, J
= 4 Hz,
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RhC
mixture was heated at 180 °C for 96 h. Biphenyl (123 μmol in 5.0 mL of
toluene) was then added to the tube as an internal standard. Formation
of 4,4′-dimethyl-2,2′-bipyridine was quantitatively analyzed by GC (79%).
C Me Rh), 114.3 (Ar), 127.2 (Ar), 140.9 (Ar), 151.3 (Ar), 154.8 ppm
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2
(
d, JRhC = 28 Hz, C ). Anal. Calcd for C H NRhRu : C, 53.66; H,
36 54 2
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.75; N, 1.74. Found: C, 53.79; H, 6.65; N, 1.52.
Reaction of 3 with 4-Picoline; Preparation of (Cp*Ru) (Cp*Ir)-
Thermolysis of 12 in Pyridine-d . An NMR tube equipped with a
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Teflon valve was charged with 12 (2.0 mg, 2.8 μmol) and pyridine-d5
0.50 mL). Hexamethylbenzene (0.7 mg, 4 μmol) was added as an
2
(
μ-H) (μ -η (||)-C H NMe) (16). A glass tube equipped with a Teflon
3 3 5 3
(
valve and with a Teflon-coated stir bar was charged with 3 (139.4 mg,
0.173 mmol), 4-picoline (170 μL, 1.75 mmol), and toluene (5 mL). The
reaction mixture was stirred at 160 °C for 5 days. The solution turned
from brown to dark red. Removal of the solvent under reduced pressure
gave a dark red residual solid. The residue was extracted with hexane
and purified by column chromatography on alumina with a mixture of
hexane and toluene (10:1) as an eluent. Complex 16 was obtained
as a dark red solid upon removal of the solvent under reduced pressure
internal standard. The tube was heated at 120 °C, and the reaction
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was periodically monitored by H NMR spectroscopy. The H NMR
spectrum recorded after 3 h showed that 0.59 μmol of 12 was converted
and 0.54 μmol of 4,4′-dimethyl-2,2′-bipyridine was formed along with
the appearance of a broad signal at δ −27.45 ppm.
Reaction of 1 with 4-(Trifluoromethyl)pyridine; Preparation
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of (Cp*Ru) (Cp*Co)(μ-H) (μ -η (||)-C H NCF ) (13). A glass tube
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equipped with a Teflon valve was charged with 1 (72.75 mg, 0.108 mmol),
(31.7 mg, 35.4 mmol, 20%). A red single crystal suitable for the
4
-(trifluoromethyl)pyridine (40 μL, 0.35 mmol), and toluene (4 mL).
XRD study was prepared by recrystallization from the mixed solvent
of acetone and toluene in a 2:1 volume ratio at −30 °C. H NMR
The reaction mixture was stirred at 100 °C for 63 h. The solution turned
from brown to dark green. Removal of the solvent under reduced pressure
gave a dark green residual solid. The residue was then extracted five times
with 2 mL of hexane, and the combined solution was filtered through a
glass filter (G4). Removal of the solvent under reduced pressure followed
by washing two times with 1 mL of methanol gave 71.9 mg of 13 as a dark
green solid (0.0881 mmol, 82%). A green single crystal suitable for the
1
(
(
400 MHz, THF-d , −70 °C): δ −23.98 (s, 1H, Ir−H−Ru), −19.05
8
s, Hz, 1H, Ir−H−Ru), −10.52 (s, 1H, Ru−H−Ru), 1.62 (s, 15H,
C Me Ru), 1.83 (s, 15H, C Me Ru), 1.97 (s, 15H, C Me Ir), 2.01 (s, 3H,
C Me), 5.89 (d, JHH = 6.4 Hz, 1H, C H), 6.39 (d, JHH = 6.4 Hz, 1H,
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C H), 6.72 ppm (s, 1H, C H). H NMR (400 MHz, THF-d
δ −21.39 (br s, 2H, Ir−H−Ru), −10.31 (s, 1H, Ru−H−Ru), 1.74
(s, 30H, C Me Ru), 1.98 (s, 15H, C Me Ir), 2.00 (d, JHH = 1.2 Hz, 3H,
C Me), 5.86 (dd, JHH = 6.4, 2.0 Hz, 1H, C H), 6.40 (d, JHH = 6.4 Hz,
1H, C H), 6.75 ppm (s, 1H, C H). C{ H} NMR (100 MHz,
THF-d , −70 °C): δ 10.9 (C Me ), 11.5 (C Me ), 12.7 (C Me ), 20.7
(C Me), 79.4 (C Me ), 85.5 (C Me ), 90.9 (C Me ), 112.9 (Ar), 126.9
, rt):
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XRD study was prepared by recrystallization from the heptane solution
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stored at −30 °C. H NMR (400 MHz, toluene-d , −40 °C): δ −27.72 (d,
HH
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J
(
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= 10.0 Hz, 1H, μ-H), −17.76 (s, 1H, μ-H), −11.83 (s, 1H, μ-H), 1.60
s, 15H, C Me Ru), 1.64 (s, 15H, C Me Co), 1.83 (s, 15H, C Me Ru),
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.99 (d, J = 6.8 Hz, 1H, Ar), 6.26 (d, JHH = 6.8 Hz, 1H, Ar), 7.67 ppm (s,
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HH
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H, C H). H NMR (400 MHz, toluene-d , 80 °C): δ 1.69 (s, 15H,
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C Me Co), 1.76 (s, 30H, C Me Ru), 6.09 (d, J = 6.0 Hz, 1H, Ar), 6.45
(Ar), 130.7 (Ar), 141.3 (Ar), 152.2 ppm (Ar). Anal. Calcd for
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HH
3
(
d, JHH = 6.0 Hz, 1H, Ar), 7.65 ppm (br s, 1H, C H). The signal for the
hydrido ligands could not be observed due to broadening. C{ H} NMR
C H NIrRu : C, 48.30; H, 6.08; N, 1.56. Found: C, 48.63; H,
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13
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6.24; N, 1.51.
K
Organometallics XXXX, XXX, XXX−XXX