FULL PAPER
a CO stream; yield 97%, 0.17 g. FTIR (CH2Cl2, νCO): ν = 2060,
crystals were obtained by the same method, yield 67%, 0.30 g. IR
˜
1985 cm–1.
(CH2Cl2, νCO, νCOMe): ν = 2077, 1726, 1662 cm–1. 1H NMR
˜
(300.13 MHz, CDCl3, 25 °C): δ = 9.93 (dd, JH,H = 0.6, 5.4 Hz, 1
[PPN]2[Rh2(μ-I)2I4(COMe)2(CO)2] (7):[22] Complex
4 (0.95 g,
H, 7-H), 8.31 (dd, JH,H = 1.2, 7.5 Hz, 1 H, 4-H), 8.22 (td, JH,H
=
1.0 mmol) was stirred overnight in methyl iodide (20 mL) at room
temperature. The removal of the excess MeI under vacuum quanti-
tatively gave a red solid, which was crystallized in dichloromethane/
diethyl ether at –20 °C; yield 72%, 0.79 g. Single crystals suitable
for X-ray analysis were obtained by slow diffusion of diethyl ether
1.5, 7.5 Hz, 1 H, 5-H), 7.9 (ddd, JH,H = 1.8, 5.7, 7.4 Hz, 1 H, 6-
H), 3.11 (s, 3 H, [Rh]COCH3), 2.89 (s, 3 H, 8, CH3CO) ppm.
13C{1H} NMR (75.475 MHz, CDCl3, 25 °C): δ = 209.27 (d, JC,Rh
= 21.1 Hz, CH3CO[Rh]), 202.93 (s, CH3CO), 154.57 (s, C-7),
182.96 (d, JC,Rh = 65.5 Hz, CO[Rh]), 151.27 (s, C-3), 140.23 (s, C-
5), 130.15 (s, C-6), 128.95 (s, C-4), 50.17 (s, CH3CO[Rh]), 27.14 (s,
CH3CO) ppm. C10H10I2NO3Rh (548.91): calcd. C 21.88, H 1.84,
N 2.55; found C 21.80, H 1.89, N 2.48.
into a dichloromethane solution at –20 °C. IR (CH2Cl2, νCO
,
νCOMe): ν = 2055 (vs), 1735 (vs), 1720 (vs) cm–1. 1H NMR
˜
(300.13 MHz, CD2Cl2, 25 °C): δselected = 3.15 (s, COCH3[Rh]), 3.13
(s, COCH3[Rh]) ppm. 13C{1H} NMR (75.468 MHz, CD2Cl2,
1
[RhI2(COMe)(CO)(methylpicolinate)] (12): The synthetic procedure
was the same as that for 11; yield 62%, 0.28 g. X-ray quality single
25 °C): δselected = 211.25 (d, JC,Rh = 20.2 Hz, COMe[Rh]), 204.10
1
1
(d, JC,Rh = 20.5 Hz, COMe[Rh]), 182.37 (d, JC,Rh = 71.0 Hz,
1
crystals were obtained in CH2Cl2/n-pentane at –20 °C. IR (CH2Cl2,
CO[Rh]), 182.03 (d, JC,Rh = 66.7 Hz, CO[Rh]) ppm. C78H66I6N2-
1
νCO, νCOMe): ν = 2077, 1733, 1685 cm–1. H NMR (300.13 MHz,
˜
O4P4Rh2 (2186.52): calcd. C 42.85, H 3.04, N 1.28; found C 42.62,
H 2.92, N 1.33. [PPN]2[Rh2(μ-I)2I4(13COMe)2(13CO)2] 7-13CO: IR
CDCl3, 25 °C): δ = 9.84 (dq, JH,H = 0.9, 5.4 Hz, 1 H, 7-H), 8.26
(ddd, JH,H = 0.6, 1.8, 7.8 Hz, 1 H, 4-H), 8.13 (td, JH,H = 1.8,
7.8 Hz, 1 H, 5-H), 7.87 (ddd, JH,H = 1.5, 5.4, 7.4 Hz, 1 H, 6-H),
4.21 (s, 3 H, COOCH3), 3.12 (s, 3 H, [Rh]COCH3) ppm. 13C{1H}
): ν = 2009 (vs), 1698 (s), 1682 (s) cm–1.
˜
13COMe
(CH2Cl2, ν13CO, ν
[PPN][RhI3(COMe)(CO)2] (8): Carbon monoxide was bubbled
through a solution of 7 (0.44 g, 0.2 mmol) in dichloromethane
(10 mL) for 5 min at room temperature. The complex formed was
characterized in situ by IR and NMR spectroscopy. Single crystals
suitable for X-ray analysis were obtained by crystallization from a
NMR (75.476 MHz, CDCl3, 298 K): δ = 207.51 (d, JC,Rh
=
21.6 Hz, [Rh]COCH3), 183.03 (d, JC,Rh = 66.3 Hz, [Rh]CO), 169.31
(s, COOCH3), 153.58 (s, C-7), 149.44 (s, C-3), 140.09 (s, C-5),
130.06 (s, C-6), 127.73 (s, C-4), 55.65 (s, COOCH3), 49.92 (s, [Rh]
COCH3) ppm. C10H10I2NO4Rh (564.91): calcd. C 21.26, H 1.78,
N 2.45; found C 21.25, H 1.87, N 2.39.
CH2Cl2/n-hexane mixture under a CO atmosphere at –20 °C. IR
(CH2Cl2, νCO, νCOMe): ν = 2140 (w), 2084 (vs), 1704 (s) cm–1. H
1
˜
NMR (300.13 MHz, CD2Cl2, 25 °C): δselected
=
2.97 (s,
COCH3[Rh]) ppm. 13C{1H} NMR (75.468 MHz, CD2Cl2, 25 °C):
X-ray Molecular Structure Determination: The crystallographic
data were collected at low temperature [–93(2) °C] with a Stoe
IPDS diffractometer for 4, an Oxford Diffraction Xcalibur CCD
diffractometer for 8 and a Bruker Kappa APEX II diffractometer
for 7a, 11 and 12, all equipped with an Oxford Cryosystems Cryos-
tream cooler device and with Mo-Kα radiation (λ = 0.71073 Å).
The structures were solved by direct methods by using SHELXS-
97[35] or SIR92,[36] and all non-hydrogen atoms were refined aniso-
tropically by using the least-squares method on F2 with the aid of
the program SHELXL-97.[37] Molecular drawings were prepared
with the program ORTEP.[38] The crystal data and refinements pa-
rameters are shown in Table 1.
1
δselected = 216.85 (d, JC,Rh = 18.2 Hz, COMe[Rh]), 177.70 (d,
1JC,Rh = 54.1 Hz, CO[Rh]) ppm. [PPN][RhI3(13COMe)(13CO)2] 8-
13CO: IR (ν13CO, ν
): ν = 2015 (vs), 1675 (s) cm–1.
˜
13COMe
[PPN][RhI3(COMe)(CO)(L)] (L = Py, 1,2-Me2Im): To a solution
of 7 (0.44 g, 0.2 mmol) in dichloromethane (20 mL) was added a
solution of L (L = pyridine or 1,2-dimethylimidazole, 2.2 equiv.) in
dichloromethane (5 mL). The mixture was stirred for 3 h at room
temperature. The resulting red solution was evaporated to dryness,
and the solid residue was washed several times with diethyl ether
and then n-pentane (3ϫ 20 mL). Finally, the compound was puri-
fied by crystallization in CH2Cl2/toluene at –20 °C, yield 58–62%.
CCDC-905028 (for 7), -905029 (for 11), -905030 (for 12), -905031
(for 8) and -905032 (for 4) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[PPN][RhI3(COMe)(CO)(Py)] (9):[22] IR (CH2Cl2, νCO, νCOMe): ν
˜
= 2069, 1713 cm–1. 1H NMR (300.13 MHz, CD2Cl2, 25 °C): δ =
9.67 (br d, 2 H, o-H Py), 7.79 (t, JH,H = 7.5 Hz, 1 H, p-H Py), 7.24
(t, JH,H = 7.5 Hz, 2 H, m-H Py), 3.08 (s, 3 H, COCH3) ppm.
13C{1H} NMR (75.476 MHz, CDCl3, 25 °C): δ = 218.43 (br.,
COCH3), 185.34 (d, JC,Rh = 59.7 Hz, [Rh]CO), 158.06 (s, Py),
137.40 (s, Py), 123.42 (s, Py), 50.19 (s, COCH3) ppm.
Kinetic Experiments: The kinetic experiments were monitored by
using IR spectroscopy with a solution cell (0.1 mm path length).
The reductive elimination reactions under moderate CO pressure
were performed in a glassware reactor (Top Industrie) at 25 °C.
Complex 7 (0.84 g, 0.38 mmol) was dissolved in dichloromethane
(8.4ϫ10–3 m, 45 mL), and the reactor was filled with CO gas to the
desired pressure. An aliquot of the reaction mixture was transferred
by a syringe into the IR cell. The kinetic measurements were moni-
tored by the decay of the νCO band of 8 at 2083.5 cm–1 and the
growth of the νCO band of 4 at 2058 cm–1. The spectra were re-
corded at a regular time intervals.
[PPN][RhI3(COMe)(CO)(1,2-MeIm)] (10): IR (CH2Cl2, νCO
,
νCOMe): ν = 2057, 1708 cm–1. 1H NMR (300.13 MHz, CD2Cl2,
˜
25 °C): δ = 7.86 (s, 1 H, CH 1,2-MeIm), 6.78 (s, 1 H, CH, 1,2-
MeIM), 3.56 (s, 3 H, CH3 1,2-MeIm), 3.08 (s, 3 H, COCH3), 2.72
(s, 3 H, COCH3) ppm. 13C{1H} NMR (75.476 MHz, CDCl3,
25 °C): δ = 186.05 (d, JC,Rh = 57.7 Hz, [Rh]CO), 148.80 (s), 135.32
(s), 118.6 (s), 49.98 (s, COCH3), 33.78 (s, CH3 1,2-MeIM), 17.43
(s, CH3 1,2-MeIM) ppm.
[RhI2(COMe)(CO)(2-acetylpyridine)] (11): To a solution of 7
(0.88 g, 0.4 mmol) in dichloromethane (20 mL) was added a solu-
tion of 2-acetylpyridine (0.3 g, 2.4 mmol) in dichloromethane
(5 mL). The mixture was stirred for 3 h at room temperature. The
resulting red solution was evaporated to dryness. The product was
then extracted into diethyl ether, and the solution was evaporated
under reduced pressure. Finally, the compound was purified by
crystallization in CH2Cl2/n-pentane at –20 °C. X-ray quality single
The reductive elimination in the absence of CO was performed in
an infrared cell (CaF2 window, 1.00 mm path length) fitted with a
thermostatted jacket and placed in the sample compartment. The
FTIR spectra (4.0 cm–1 resolution) were scanned in the region
4000–450 cm–1 and saved at regular time intervals by using the
spectrum software TIMEBASE. The absorbance (At) versus time
data for the appropriate νCO frequencies were extracted by sub-
tracting the solvent spectrum.
Eur. J. Inorg. Chem. 2014, 326–336
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