Organometallics
Article
Anal. Calcd for C25H38F6O2PRh: C, 48.55; H, 6.19. Found: C, 47.83;
H, 5.91. Correct elemental analysis was difficult to obtain because the
compound was oily. Complex [1d]BF4 was prepared similarly, using
AgBF4 instead of AgPF6. Crystals of [1d]BF4 were obtained by slow
diffusion of Et2O vapors into the solution of the complex in CH2Cl2.
[(C4Et4)Rh(C6Et6)]PF6 ([1e]PF6). Complex [(coe)2RhCl]2 (72 mg,
0,10 mmol) and AgPF6 (56 mg, 0.22 mmol) were dissolved in acetone
(2 mL), and the mixture was stirred for 2 h at room temperature. Then
3-hexyne (500 μL, 4.3 mmol, excess) was added, and reaction mixture
was stirred overnight at 60 °C. The precipitate of AgCl was removed
by centrifugation, and the brown solution was evaporated to dryness.
The solid was reprecipitated from CH2Cl2/Et2O and washed with
Et2O (3 × 5 mL) to give [1e]PF6 as a pale yellow, air-stable solid.
Yield: 92 mg, 70%. [1e]OTf was prepared similarly, using AgOTf
instead of AgPF6. 1H NMR (400 MHz, (CD3)2CO): δ 2.83 (q, J = 7.5
Hz, 12H, CH2C6Et6), 2.05 (q, J = 7.5 Hz, 8H, CH2C4Et4), 1.38 (t, J = 7.5
Hz, 18H, CH3C6Et6), 1.10 (t, J = 7.5 Hz, 12H, CH3C4Et4). 13C NMR
(101 MHz, (CD3)2CO): δ 118.6 (d, J = 4.0 Hz, C6Me6), 94.0 (d, J =
11.6 Hz, C4Et4), 22.0 (s, CH2C6Et6), 18.2 (s, CH2 C4Et4), 15.7 (s,
CH3C6Me6), 13.0 (s, CH3C4Et4). Anal. Calcd for C31H50F3O3RhS: C,
56.18; H, 7.60. Found: C, 56.48; H, 7.52.
were dissolved in nitromethane (0.5 mL), and the mixture was left
stirring overnight. The precipitate of AgCl was removed by
centrifugation, and the yellow solution was evaporated to dryness.
The solid was reprecipitated from CH2Cl2/Et2O and washed with
Et2O (2 × 5 mL) to give [3]PF6 as a pale yellow solid. This compound
is stable in air for several days, but notably decomposes (forms
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insoluble species) after several months. Yield: 45 mg, 78%. H NMR
(400 MHz, CD3NO2): δ 6.51 (s, 4H, C6H4Me2), 3.13 (d, J = 9.3 Hz,
4H, CHC8H14), 2.77 (s, 6H, C6H4Me2), 2.62 (dd, J = 12.3, 2.9 Hz, 4H,
CH2C8H14), 2.00−1.93 (m, 8H, CH2C8H14), 1.72−1.58 (m, 12H,
CH2C8H14). 13C NMR (101 MHz, CD3NO2): δ 124.0 (s, CC6H4Me2),
107.5 (s, CHC6H4Me2), 78.8 (d, J = 12.5 Hz, CHC8H14), 31.4 (s,
CH2C8H14), 31.1 (s, CH2C8H14), 25.8 (s, CH2C8H14), 17.9 (s,
CH3C6H4Me2). Anal. Calcd for C24H38F6RhP·Et2O: C, 51.85; H, 7.46.
Found: C, 51.39; H, 6.96.
[(coe)2Ir(p-xylene)]PF6 ([4]PF6). Complex [(coe)2IrCl]2 (45 mg,
0.05 mmol), AgPF6 (30 mg, 0.12 mmol), and an excess of p-xylene
(0.5 mL) were dissolved in dichloromethane (2 mL) and stirred
overnight at room temperature. The precipitate of AgCl was removed
by centrifugation, and the yellow solution was evaporated to dryness.
The residue was reprecipitated from CH2Cl2/petroleum ether and
washed with petroleum ether (3 × 5 mL) to give [4]PF6 as a beige
solid. This compound is stable in air for several days, but notably
decomposes (forms insoluble species) after several months. Yield: 42
mg, 64%. 1H NMR (400 MHz, (CD3)2CO): δ 6.63 (s, 4H, C6H4Me2),
2.55 (s, 6H, C6H4Me2), 2.44 (d, J = 9.9 Hz, 4H, CHC8H14), 2.33 (dd, J
= 12.9, 2.5 Hz, 4H, CH2C8H14), 1.81−1.67 (m, 8H, CH2C8H14), 1.50−
1.35 (m, 12H, CH2C8H14). 13C NMR (101 MHz, (CD3)2CO): δ 120.3
(s, C6H4Me2), 101.4 (s, C6H4Me2), 62.9 (s, CHC8H14), 32.7 (s,
CH2C8H14), 31.7 (s, CH2C8H14), 26.5 (s, CH2C8H14), 18.6 (s, C6H4Me2).
Anal. Calcd for C24H38F6IrP·CH2Cl2: C, 40.11; H, 5.39. Found: C,
40.22; H, 5.61.
[(C4Et4)Rh(p-methylaniline)]PF6 ([1f]PF6). Complex [1a]PF6 (52
mg, 0.1 mmol) and p-methylaniline (107 mg, 1 mmol) were dissolved
in acetone (2 mL) and refluxed for 18 h. Solvent was evaporated to
dryness, and the solid was washed with Et2O (2 × 5 mL) and
reprecipitated from CH2Cl2/Et2O to give [1f]PF6 as a pale yellow, air-
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stable solid. Yield: 46 mg, 88%. H NMR (400 MHz, (CD3)2CO): δ
6.64 (d, J = 6.8 Hz, 2H, 4-MeC6H4NH2), 6.44 (d, J = 7.0 Hz, 2H, 4-
MeC6H4NH2), 5.73 (s, 2H, 4-MeC6H4NH2), 2.28 (s, 3H, 4-
MeC6H4NH2), 2.14 (q, J = 7.5 Hz, 8H, CH2C4Et4), 1.11 (t, J = 7.5
Hz, 12H, CH3C4Et4). 13C NMR (101 MHz, (CD3)2CO): δ 134.2 (s, 4-
MeC6H4NH2), 106.2 (d, J = 4.5 Hz, 4-MeC6H4NH2), 100.8 (d, J = 4.8
Hz, 4-MeC6H4NH2), 95.1 (d, J = 11.9 Hz, C4Et4), 85.6 (m, 4-
MeC6H4NH2), 18.4 (s, CH2C4Et4), 17.7(s, 4-MeC6H4NH2), 12.8 (s,
CH3C4Et4). Anal. Calcd for C19H29F6NPRh: C, 43.94; H, 5.63; N, 2.70.
Found: C, 43.84; H, 5.62; N, 2.61.
[(C4Et4)Rh(2-mesitylacetonitrile)]PF6 ([1g]PF6). Complex
[1a]PF6 (52 mg, 0.1 mmol) and 2-mesitylacetonitrile (158 mg, 1
mmol) were dissolved in acetone (2 mL) and refluxed for 18 h.
Solvent was evaporated, and the brown oil was washed with Et2O (3 ×
5 mL), dissolved in CH2Cl2, and eluted through a short pad of silica
gel with a CH2Cl2/acetone (5:1) mixture. Eluent was evaporated, and
the residue was reprecipitated several times from CH2Cl2/Et2O to give
[1g]PF6 as a colorless, air-stable, oily substance. Yield: 34 mg, 60%. 1H
NMR (400 MHz, (CD3)2CO): δ 6.97 (s, 2H, Me3C6H2CH2CN), 4.16
[(C4Et4)Ir(C6Et6)]PF6 ([5]PF6). Complex [(coe)2IrCl]2 (45 mg, 0.05
mmol) and AgPF6 (30 mg, 0.12 mmol) were dissolved in 1,2-
dichloroethane (2 mL) and vigorously stirred for 5 min at room
temperature. Then 3-hexyne (400 μL, 3.5 mmol, excess) was added,
and reaction mixture was stirred at 80 °C for 6 h. The precipitate of
AgCl was removed by centrifugation, and the brown solution was
evaporated to dryness. The solid was reprecipitated from CH2Cl2/
Et2O and washed with Et2O (3 × 5 mL) to give [5]PF6 as a beige, oily
yellow, air-stable solid. The product was then dissolved in a minimal
amount of CH2Cl2 and crystallized by slow diffusion of Et2O vapors.
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Yield: 49 mg, 65%. H NMR (400 MHz, CDCl3): δ 2.63 (q, J = 7.4
Hz, 12H, CH2C6Et6), 1.92 (q, J = 7.4 Hz, 8H, CH2C4Et4), 1.37 (t, J = 7.4
Hz, 18H, CH3C6Et6), 1.08 (t, J = 7.4 Hz, 12H, CH3C4Et4). 13C NMR
(101 MHz, (CD3)2CO): δ 110.8 (s, C6Et6), 84.7 (s, C4Et4), 22.9 (s,
CH2C6Et6), 18.3 (s, CH2C4Et4), 16.4 (s, CH3C6Et6), 14.7 (s, CH3C4Et4).
Anal. Calcd for C30H50F6IrP: C, 48.18; H, 6.74. Found: C, 48.50; H,
6.39.
(d,
J = 2.5 Hz, 2H, Me3C6H2CH2CN), 2.59 (s, 6H,
Me3C6H2CH2CN), 2.42 (s, 3H, Me3C6H2CH2CN), 2.19 (q, J = 7.5
Hz, 8H, CH2C4Et4), 1.12 (t, J = 7.5 Hz, 12H, CH3C4Et4). 13C NMR (101
MHz, (CD3)2CO): δ 116.9 (s, Me3C6H2CH2CN), 116.3 (d, J = 4.1
Hz, Me3C6H2CH2CN), 116.0 (d, J = 3.9 Hz, Me3C6H2CH2CN), 107.8
(d, J = 4.4 Hz, Me3C6H2CH2CN), 104.9 (d, J = 4.2 Hz,
Me3C6H2CH2CN), 97.9 (d, J = 11.7 Hz, C4Et4), 19.1 (s,
Me3C6H2CH2CN), 18.9 (s, CH2C4Et4), 18.6 (s, Me3C6H2-CH2CN),
17.3 (s, Me3C6H2CH2CN), 13.7 (s, CH3C4Et4). Anal. Calcd for
C23H33F6NPRh: C, 48.35; H, 5.82. Found: C, 48.36; H, 6.25.
[(C2H4)2Rh(C6Me6)]PF6 ([2]PF6). Complex [(C2H4)2RhCl]2 (98
mg, 0.25 mmol), AgPF6 (146 mg, 0.57 mmol), and hexamethylben-
zene (416 mg, 2.6 mmol, excess) were dissolved in acetone/CH2Cl2
(1:1, 2 mL, CH2Cl2 improves solubility of C6Me6), and the mixture
was stirred overnight. The precipitate of AgCl was removed by
centrifugation and washed with CH2Cl2, and the combined yellow
solution was evaporated to dryness. The solid was reprecipitated from
CH2Cl2/Et2O and washed with Et2O (3 × 5 mL) to give the product.
Yield: 166 mg, 84%. 1H NMR (400 MHz, (CD3)2CO): δ 2.78 (br d, J
= 12.5 Hz, 4H, CH2), 2.41 (br d, J = 12.5 Hz, 4H, CH2), 2.36 (s, 18H,
CH3). The spectral data are similar to those previously reported.13,21
Crystals of [2]PF2O2 were obtained by slow diffusion of Et2O vapors
into the solution of [2]PF6 in acetone.
[(C4Ph4)Ir(p-xylene)]+ ([6]PF6). Complex [(coe)2IrCl]2 (45 mg,
0.05 mmol), AgPF6 (30 mg, 0.12 mmol), and p-xylene (0.5 mL) were
dissolved in 1,2-dichloroethane (2 mL), and the mixture was stirred for
2 h at room temperature. Then diphenylacetylene (107 mg, 0.6 mmol)
was added, and reaction mixture was heated at 80 °C for 12 h. The
precipitate of AgCl was removed by centrifugation, and the brown
solution was evaporated to dryness. The solid was reprecipitated from
CH2Cl2/Et2O and washed with Et2O (3 × 5 mL) to give the product
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[6]PF6 as a beige solid. Yield: 18 mg, 23%. H NMR (400 MHz,
(CD3)2CO): δ 7.39 (m, 20H, CHPh), 7.11 (s, 4H, CHC6H4Me2), 1.96 (s,
6H, CH3C6H4Me2). 13C NMR (101 MHz, CD3NO2): δ 129.3 (s,
PhC4Ph4), 129.1 (s, PhC4Ph4), 129.1 (s, PhC4Ph4), 110.5 (s, C6H4Me2),
94.2 (s, C4Ph4), 82.4 (s, C6H4Me2), 16.4 (s, CH3C6H4Me2). Correct
analysis could not be obtained, apparently, because of the slow
decomposition of the substance.
General Procedure for Catalytic Reductive Amination. A 2
mL glass vial was placed in a 10 mL stainless steel autoclave and
charged with the catalyst (0.005 mmol, 1.0 mol %), p-anisidine (62
mg, 0.5 mmol), p-tolylaldehyde (59 μL, 0.5 mmol), and tert-butanol
(0.5 mL). The use of a glass vial is crucial because interaction of the
catalyst with the metal surface of the autoclave led to decreased
[(coe)2Rh(p-xylene)]PF6 ([3]PF6). Complex [(coe)2RhCl]2 (36
mg, 0.05 mmol), AgPF6 (28 mg, 0.11 mmol), and p-xylene (0.5 mL)
E
Organometallics XXXX, XXX, XXX−XXX