Inorganic Chemistry
Article
(27 °C, CD2Cl2, 100.5 MHz): δ 195.2 (Rh−CO, dm, 1C, 1JRhC = 66.5 Hz),
181.3 (Ir−CO, s, 1C), 51.8 (CH2, m, 1C), 45.6 (CH2, m, 1C), 30.9 (tBu, s,
1C), 30.6 (tBu, s, 3C). IR (CH2Cl2): ν(CO) = 1944, 1896 (s) cm−1,
ν(Ge−H) = 2097 (w) cm−1. Compound 6 was also produced upon
warming solutions of 4 to ambient temperature.
Orange crystals were obtained by diffusion of pentane into a con-
centrated fluorobenzene solution of the compound. Isolated yield
68% (95.0 mg). Anal. Calcd for C77H66Ge2IrO3P4Rh·1.5C6H5F: C,
59.05; H, 4.21. Found: C, 59.32; H, 4.41. 31P{1H} NMR (27 °C;
1
2
C6D6, 161.9 MHz): δ 4.2 (Rh−P, ddd, 1P, JRhP =108 Hz, JPP = 108
e. [RhIr(GeH2Ph)(H)2(CO)2(κ1-dppm)(μ-GePhH)(μ-H)(dppm)] (7).
In a septum-sealed NMR tube under an Ar atmosphere, [RhIr-
(H)2(CO)2(μ-GeHPh)(dppm)2] (5) (30 mg 0.023 mmol) was dissolved
in 0.7 mL of CD2Cl2 and then cooled to −78 °C. A 3.2 μL (1.1 equiv)
amount of PhGeH3 was added to the NMR tube via a microliter syringe.
No reaction was observed by NMR at this temperature. Upon warming to
−40 °C, the intermediate 7 was observed in the 31P{1H} NMR spectrum
in approximately 30% yield after 1 h reaction time. Further warming to
−20 °C led to several unidentified products. 31P{1H} NMR (−40 °C,
Hz, 3JPP = 5 Hz), −2.3 (Ir−P, dd, 1P, 2JPP = 45 Hz, 3JPP = 5 Hz), −8.3
2
2
4
(Ir−P, ddd, 1P, JPP = 108 Hz, JR4hP = 8 Hz, JP1P = 8 Hz), −28.5
2
(pendent-P, dd, 1P, JPP = 45 Hz, JPP = 8 Hz). H NMR (27 °C;
C6D6, 498.1 MHz): δ 5.65 (Ge−H, d, 1H, 3JPH = 6.1 Hz), 5.16 (CH2, m,
1H), 3.88 (CH2, m, 1H), 3.54 (CH2, m, 1H), 3.26 (CH2, m, 1H),
−10.82 (Ir−H, dd, 1H, JPH = 19.6 Hz, JPH = 14.6 Hz). 13C{1H}
2
2
NMR (27 °C; CD2Cl2, 100.5 MHz): δ 202.4 (Rh−CO, dm, 1C,
1JRhC = 43.8 Hz), 200.5 (Rh−CO, dm, 1C, JRhC = 43.8 Hz), 184.8
1
(Ir−CO, bs, 1C), 58.3 (CH2, m, 1C), 38.5 (CH2, m, 1C).
1
i. [RhIr(CH3)(GeHPh2)(CO)(μ-H)(μ-CO)(dppm)2][CF3SO3] (11).
Under Ar, 30 mg (0.023 mmol) of [RhIr(CH3)(CO)2(dppm)2]-
[CF3SO3] (2) was taken into an NMR tube, dissolved in 0.7 mL of
CD2Cl2, and cooled to −78 °C in an acetone−dry ice bath. A 4.3 μL
(0.023 mmol) amount of diphenylgermane was added by a microliter
syringe, and the reaction was monitored by low-temperature NMR
spectroscopy. Immediately after addition of diphenylgermane the dark
orange color of the solution lightened. Between −80 and −60 °C
NMR analysis indicated quantitative formation of [RhIr(CH3)-
(GeHPh2)(CO)(μ-H)(μ-CO)(μ-dppm)2][CF3SO3] (11) in solution.
No attempt was made to isolate this compound at this temperature.
13C-enriched compound 11 was prepared as discussed above by
reacting 13C-enriched [RhIr(13CH3)(13CO)2(dppm)2][CF3SO3] (2)
with Ph2GeH2. 31P{1H} NMR (−80 °C; CD2Cl2, 161.9 MHz): δ 28.3
CD2Cl2, 161.9 MHz): δ 21.8 (Rh−P, dm, 1P, JRhP = 102 Hz), −10.5
(Ir−P, m, 1P), −18.3 (Ir−P, m, 1P), −28.4 (Pendent-P, m, 1P). 1H NMR
(−40 °C; CD2Cl2, 399.8 MHz): δ 5.22 (CH2, m, 1H), 4.92 (CH2, m,
1H), 3.67 (Ge−H, m, 1H), 3.58 (Ge−H, m, 1H), 3.31 (CH2, m, 1H),
2.56 (CH2, m, 1H), −12.10 (Rh−H, ddm, 1H, 2Jtrans‑PH = 159 Hz, 1JRhH
=
12.0 Hz), −12.58 (μ-H, b, 1H, 1JRhH = 14.0 Hz), −12.75 (Ir−H, dm, 1H,
2Jtrans‑PH = 129 Hz).
f. [RhIr(CO)2(μ-GeHPh)(μ-GePh2)(dppm)2] (8). A 74 mg (0.058
mmol) amount of [RhIr(H)2(CO)2(μ-GeHPh)(dppm)2] (5) in a
Schlenk flask was dissolved in 10 mL of CH2Cl2 followed by addition
of 11 μL (0.058 mmol) of Ph2GeH2. The reaction mixture was stirred
gently for 24 h, during which time the yellow solution of 5 turned
orange. The solvent volume was reduced to approximately 1 mL under
high vacuum, and the solution was layered with 3 mL of pentane,
yielding light yellow crystals (suitable for X-ray analysis) of compound
8 after 48 h in 77% yield. Anal. Calcd for C70H60Ge2IrO2P4Rh: C,
56.17; H, 4.01. Found: C, 55.91; H, 4.16. 31P{1H} NMR (27 °C;
1
(Rh−P, dm, 2P, JRhP = 140 Hz), −9.1 (Ir−P, m, 2P). 1H NMR
(−80 °C; CD2Cl2, 399.8 MHz): δ 5.09 (Ge−H, t, 1H, 3JPH = 13.0 Hz),
4.10 (CH2, m, 2H), 3.40 (CH2, m, 2H), 0.49 (CH3, t, 3H, 3JPH = 6.8 Hz),
1
−8.94 (μ-H, dm, 1H, JRhH = 13.6 Hz). 13C{1H} (−80 °C; CD2Cl2,
1
2
CD2Cl2, 201.6 MHz): δ 35.8 (Rh−P, ddd, 1P, JRhP = 112 Hz, JPP
=
=
100.5 MHz): δ 214.8 (μ-CO, dm, 1C, 1JRhC = 29 Hz), 173.3 (Ir−CO,
2
1
2
116 Hz, JPP = 28 Hz), 24.4 (Rh−P, ddd, 1P, JRhP = 115 Hz, JPP
2
1
140 Hz, 2J PP = 28 Hz), 7.8 (Ir−P, dd, 1P, 2JPP = 116 Hz, 2JPP = 20 Hz),
t, 1C, JPC2 = 9.0 Hz), 32.7 (CH2, m, 2C) 15.1 (CH3, dt, 1C, JRhC
=
28.0 Hz, JPC = 6.0 Hz). 19F NMR (−80 °C; CD2Cl2, 376.3 MHz):
δ 79.3 (CF3SO3, s, 3F).
2
2
1
−7.9 (Ir−P, dd, 1P, JPP = 140 Hz, JPP = 20 Hz). H NMR (27 °C;
CD2Cl2, 498.1 MHz): δ 6.14 (Ge−H, m, 1H), 5.13 (CH2, m, 1H), 4.49
(CH2, m, 1H), 3.02 (CH2, m, 1H), 2.94 (CH2, m, 1H). 13C{1H}
j. [RhIr(CH3)(CO)2(μ-GeHPh2)(μ-H)(dppm)2][CF3SO3] (12). Method
1: Warming the solution of compound 11 to −20 °C resulted in a
color change of the solution to light green from light orange. 31P{1H}
NMR suggested quantitative formation of compound 12. Method 2:
70 mg (0.055 mmol) of compound 2 in a Schlenk tube was dissolved
in 3 mL of THF followed by three freeze−pump−thaw cycles. The
reaction flask was then cooled to −15 °C in a salt−ice water bath. A
10.2 μL (0.055 mmol) amount of Ph2GeH2 was dissolved in another
Schlenk tube, and the solution was cannula transferred to the first
flask. The reaction was stirred for 30 min at this temperature, during
which time a greenish-yellow precipitate settled at the bottom of the
flask. After removal of THF via cannula, the solids were washed with
ether to give analytically pure complex. Isolated yield 67% (55.2 mg).
The complex was stable at ambient temperature in the solid state
under an inert atmosphere; however, it was unstable above 20 °C in a
solution of CH2Cl2. Anal. Calcd for C66H59F3IrO5P4RhGeS: C, 52.42; H,
3.91. Found: C, 52.79; H, 4.23. 13C-enriched compound 12 was
prepared under similar conditions as mentioned above by reacting
[RhIr(13CH3)(13CO)2(dppm)2][CF3SO3] (2) with Ph2GeH2. 31P{1H}
1
(CD2Cl2, 100.5 MHz): δ 200.5 (Rh−CO, dm, 1C, JRhC = 76 Hz),
187.0 (Ir−CO, bs, 1C), 37.5 (CH2, m, 1C), 34.1 (CH2, m, 1C)
g. [RhIr(H)2(CO)2(μ-GePh2)(dppm)2] (9). Under an Ar atmosphere,
100 mg of compound 1 (0.087 mmol) in a Schlenk tube was dissolved
in 20 mL of CH2Cl2. The solution was then cooled to 0 °C in an ice−
water bath, 17.8 μL (1.1 equiv) of Ph2GeH2 was added by syringe to
the vigorously stirred solution of 1, and the reaction was left for 6 h at
this temperature under a dynamic Ar flow (which is important for
effective removal of released CO; otherwise, the reaction mainly gave a
mixture of complexes 9 and 10). During this time the color of the
solution lightened. The solvent was reduced to 1 mL in vacuo, and the
remaining solution was layered with 3 mL of pentane. Colorless
crystals were separated after 24 h. Isolated yield 40% (47.0 mg). Anal.
Calcd for C64H56GeIrO2P4Rh: C, 56.95; H, 4.15. Found: C, 56.72; H,
4.29. 31P{1H} NMR (27 °C; CD2Cl2, 161.9 MHz): δ 27.5 (Rh−P, m,
1P), 18.1 (Rh−P, m, 1P). −0.2 (Ir−P, m, 1P), −8.3 (Ir−P, m, 1P). 1H
NMR (27 °C; CD2Cl2, 399.8 MHz): δ 4.01 (CH2, bm, 1H), 3.82
(CH2, bm, 1H), 2.95 (CH2, bm, 1H), 2.55 (CH2, bm, 1H), −10.78
(bm), −11.09 (bm, 1H). 31P{1H} NMR (−80 °C; CD2Cl2, 161.9
MHz): δ 27.1(Rh−P, m, 1P), 17.8 (Rh−P, m, 1P), −0.8 (Ir−P, m,
1P), −8.6 (Ir−P, m, 1P). 1H NMR (−80 °C; CD2Cl2, 399.8 MHz): δ
4.12 (CH2, m, 1H), 3.95 (CH2, m, 1H), 3.00 (CH2, bm, 1H), 2.63
NMR (−20 °C; CD2Cl2, 161.9 MHz): δ 21.4 (Rh−P, dm, 2P, 1JRhP
=
1
99 Hz), −15.6 (Ir−P, m, 2P). H NMR (−20 °C; CD2Cl2, 399.8
MHz): δ 4.08 (CH2, m, 2H), 3.36 (CH2, m, 2H), 0.89 (CH3, t, 3H,
3JPH = 6.4 Hz), −1.92 (μ-Ge−H, ddm, 1H, 1JRhH = 25.2 Hz, 2JHH = 7.0 Hz),
(CH2, m, 1H), −10.76 (Rh−H, ddm, 1H, 2Jtrans‑PH = 129.0 Hz, 1JRh−H
=
−9.23 (ddm, μ-H, 1H, 1JRhH = 16.8 Hz, 2JHH = 7.0 Hz). 13C{1H} NMR
2
1
13.0 Hz), −11.09 (Ir−H, dm, 1H, Jtrans‑PH = 115.0 Hz). 13C{1H} NMR
(27 °C; CD2Cl2, 100.5 MHz): δ 197.9 (Rh−CO, dt, 1C, 1JRhC = 69 Hz,
(−20 °C, CD2Cl2, 100.5 MHz): δ 192.4 (Rh−CO, dt, 1C, JRhC
=
2
2
78.5 Hz, JPC = 14.2 Hz), 177.5 (Ir−CO, t, 1C, JPC = 7.8 Hz), 36.9
2JPC = 10 Hz), 182.9 (Ir−CO, t, 1C, JPC = 13 Hz).
(CH2, m, 2C), −25.1 (CH3, bt, 1C, JPC = 7.0 Hz). 19F NMR (−20
°C; CD2Cl2, 376.3 MHz): δ 79.3 (CF3SO3, s, 3F).
2
2
h. [RhIr(H)(GePh2H)(CO)3(κ1-dppm)(μ-GePh2)(dppm)] (10). In a
Schlenk tube 100 mg (0.087 mmol) of compound 1 was dissolved in
5 mL of benzene at ambient temperature. Three freeze−pump−thaw
cycles were applied to the solution, followed by addition of 64 μL
(4 equiv) of Ph2GeH2. After stirring the solution overnight in the
sealed Schlenk tube, the solvent volume was reduced in vacuo to 2 mL.
Subsequent addition of 10 mL of pentane gave rise to a yellow powder.
k. [RhIr(CO)2(μ-H)(μ-GePh2)(dppm)2][CF3SO3] (13). Method 1: As
the solution of compound 12 was warmed to ambient temperature the
color turned dark green from light green within a period of 2 h.
31P{1H} NMR suggested quantitative formation of compound 13.
Method 2: 70 mg (0.055 mmol) of compound 2 in a Schlenk tube was
dissolved in 3 mL of dry CH2Cl2 followed by three freeze−pump−
4022
dx.doi.org/10.1021/ic2021269 | Inorg. Chem. 2012, 51, 4020−4034