2
P.P. Sarmah, D.K. Dutta / Journal of Molecular Catalysis A: Chemical 372 (2013) 1–5
limited (India) and used after distilled using standard technique.
Methyl iodide (99.5%), KBr (IR grade) and CHCl3 (IR grade) were
purchased from M/S Merck, Germany and used without further
purification. Carbon monoxide gas (99.9%) was purchased from
Alchemie gases and chemicals Pvt. Ltd. (India).
2b: yield: 0.053 g, 76%. IR (KBr): 2065 [(CO)], 1734
[(acyl)] cm . 1H NMR (300 MHz, CDCl ) data (ı in ppm): ı 2.43
−
1
3
(3H, s, CH ), ı 7.85–8.93 (5H, m, Py, Ph), ı 9.36 (H-2, d, JH–H = 7.6 Hz,
3
Py). 13C NMR (75 MHz, CDCl ) data (ı in ppm): ı 46.0 (CH ), ı
3
3
129.8–155.0 (m, Ph, Py), ı 170.0 (COOH), ı 188 (br, CO), ı 207.6
(br, COacyl).
Elemental analyses were performed on a Perkin-Elmer 2400 ele-
−
1
mental analyzer. IR spectra (4000–400 cm ) were recorded in KBr
3a: yield: 0.051 g, 72%. IR (KBr): 2076 [(CO)], 1731
[(acyl)] cm . 1H NMR (300 MHz, CDCl ) data (ı in ppm): ı
−
1
discs and CHCl on a Shimadzu IRAffiniry-1 spectrophotometer. The
3
3
1
13
H and C NMR spectra were recorded at room temperature (r.t.)
1.19 (3H, t, JH–H = 6.1 Hz, CH ), ı 2.87 (2H, q, JH–H = 6.1 Hz, CH ), ı
3
2
in CDCl solution on a Bruker DPX-300 Spectrometer and chemical
7.89–8.37 (4H, m, Ph), ı 8.71 (H-3, d, JH–H = 7.9 Hz, Py), ı 9.59 (H-4,
3
shifts were reported relative to SiMe . Mass spectra of the com-
d, JH–H = 7.9 Hz, Py). 13C (75 MHz, CDCl ) data (ı in ppm): ı 22.1
4
3
plexes were recorded on ESQUIRE 3000 Mass Spectrometer. The
carbonylation reactions of methanol were carried out in a high pres-
sure reactor (Parr-4592, USA) fitted with a pressure gauge and the
reaction products were analyzed by GC (Chemito 8510, FID).
(CH ), ı 56.3 (CH ), ı 122.7–159.1 (m, Ph, Py), ı 167.5 (COOH), ı
189 (br, CO), 205 (br, COacyl).
3 2
3b: yield: 0.049 g, 69%. IR (KBr): 2067 [(CO)], 1739
[(acyl)] cm . 1H NMR (300 MHz, CDCl ) data (ı in ppm): ı 1.27
−
1
3
(
3H, t, JH–H = 6.3 Hz, CH ), ı 2.98 (2H, q, JH–H = 6.3 Hz, CH ), ı
3
2
2.2. Starting materials
7.89–8.91 (5H, m, Ph), ı 9.28 (H-2, d, JH–H = 7.6 Hz, Py). (75 MHz,
CDCl ) data (ı in ppm): ı 25.3 (CH ), ı 56.6 (CH ), ı 125.9–153.9
3
3
2
[
Rh(CO) Cl] was prepared by passing CO gas over RhCl ·3H O
(m, Ph, Py), ı 169.3(COOH), ı 191 (br, CO), ı 208 (br, COacyl).
2
2
3
2
◦
at 100 C in the presence of moisture [27].
2
.5. Synthesis of [Rh(CO)ClI L] (4a and 4b)
2
2
.3. Synthesis of the complexes [Rh(CO) ClL] (1a and 1b),
2
L = quinoline-2-carboxylic acid (a), quinoline-8-carboxylic acid (b)
0.018 mmol (0.05 g) of [Rh(CO) ClL] (1a and 1b) was dissolved
2
3
in dichloromethane (5 cm ). To that solution iodine was added
(0.02 mmol, 0.025 g). The reaction mixture was stirred for 6 h to
generate 4a and 4b. The color of the solution changed from yel-
lowish red to dark reddish brown and the solvent was evaporated
under vacuum. Excess iodine was removed by washing several time
with hexane and stored over silica gel in a desiccator.
About 0.257 mmol (100 mg) [Rh(CO) Cl] was dissolved in
2
2
3
dichloromethane (10 cm ) and to this solution, 0.514 mmol (89 mg)
of the appropriate ligand was added. The reaction mixture was
stirred at r.t. for 30 min and the solvent was evaporated under vac-
uum. The dark purple compounds so obtained were washed with
diethyl ether, recrystallised and stored over silica gel under vacuum
in a desiccator.
Analytical data for 4a and 4b are as follows:
4a: yield: 0.048 g, 57%. IR (KBr): 2065 [(CO)] cm 1. 1H NMR
−
Analytical data for 1a and 1b are as follows:
(300 MHz, d -DMSO) data (ı in ppm): ı 7.81–8.43 (4H, m, Ph), ı
6
13
1
a: yield: 0.156 g, 83%. IR (KBr): 2085, 1999 [(CO)], 1660
8.77(H-3, d, JH–H = 7.2 Hz, Py), ı 9.76 (H-4, d, JH–H = 7.2 Hz, Py).
C
−1
1
[
( COOH)] cm
.
H NMR (300 MHz, CDCl ) data (ı in ppm):
NMR (75 MHz, d -DMSO) data (ı in ppm): ı 123.7–155.3 (m, Ph,
3
6
ı 7.91–8.28 (4H, m, Ph), ı 8.39 (H-3, d, JH–H = 8.4 Hz, Py), ı
Py), ı 171.2 (COOH), ı 187 (br, CO).
9
.32 (H-4, d, JH–H = 8.4 Hz, Py). 13C NMR (75 MHz, CDCl ) data
4b: yield: 0.066 g, 81%. IR (KBr): 2068[(CO)] cm . 1H NMR
−1
3
(
(
(
ı in ppm): ı 125.7–149.3 (m, Ph, Py), ı 169.5 (COOH), ı 186.1
(300 MHz, d -DMSO) data (ı in ppm): ı 7.81–8.96 (5H, m, Py, Ph),
6
CO, JRh–C = 67.7 Hz), ı 189 (CO, 1JRh–C = 64.3 Hz). C12H7NClO Rh
1
ı 9.29 (H-2, d, JH–H = 7.1 Hz, Py). C (75 MHz, d -DMSO) data (ı in
13
4
6
367.57): cald. C 39.18, H 1.90, N 3.81; found C 39.01, H 1.81, N
ppm): ı 129.1–154.6 (m, Ph, Py), ı 168.7 (COOH), ı 189.2 (br, CO).
+
3
.75. MS: m/z = 367.5 [M ].
1
b: yield: 0.164 g, 87%. IR (KBr): 2073, 1985 [(CO)], 1666
2.6. Kinetic experiments
−
. H NMR (300 MHz, CDCl ) data (ı in ppm): ı
3
1 1
[
7
( COOH)] cm
13
.81–8.91 (5H, m, Py, Ph), ı 9.23 (H-2, d, JH–H = 7.6 Hz, Py).
C
The kinetic experiments of OA reaction of complexes 1a and
NMR (75 MHz, CDCl ) data (ı in ppm): ı 123.7–151.0 (m, Ph,
1b with neat CH I were monitored using FT-IR spectroscopy in a
solution cell (NaCl windows, 1 mm path length). In order to obtain
3
3
1
Py), ı 167.2 (COOH), ı 186.4 (CO, JRh–C = 64.7 Hz), ı 188.2 (CO,
1
JRh–C = 62.3 Hz). C12H7NClO Rh (367.57): cald. C 39.18, H 1.90, N
.81; found C 38.96, H 1.82, N 3.71. MS: m/z = 367.7 [M ].
pseudo-first-order condition, excess of CH I relative to metal com-
4
3
+
−1
3
plex was used. FT-IR spectra (4.0 cm resolution) were scanned
−
1
in the (CO) region (2200–1650 cm ) and saved at regular time
interval using spectrum software. After completion of experiment,
absorbance versus time data for the appropriate (CO) frequencies
were extracted by subtracting the solvent spectrum and analyzed
off line using OriginPro 8 software. Kinetic measurements were
made by following the decay of lower frequency (CO) band of the
2
.4. Synthesis of [Rh(CO)(COR)ClIL] {R = CH , (2a and 2b),
3
R = C H5 (3a and 3b)}
2
[
Rh(CO) ClL] (50 mg) (1a and 1b) was dissolved in
2
3
3
dichloromethane (5 cm ) and each of RX (3 cm ) (RX = CH I,
3
−
1
C2H5I) was added to it. The reaction mixture was then stirred at
r.t. for about 6–12 h to yield 2a, 2b and 3a, 3b. The color of the
solution changed from yellowish red to dark reddish brown and
the solvent was evaporated under vacuum. The compounds so
obtained were washed with diethyl ether and stored over silica gel
in a desiccator.
complexes 1a and 1b in the region 1980–2000 cm . The pseudo
first order rate constants were found from the gradient of the plot
of ln(A /At) versus time, where A0 is the initial absorbance and At
0
is the absorbance at time, t.
2.7. Carbonylation of methanol using complexes 1a and 1b as
Analytical data for 2a, 2b, 3a and 3b are as follows:
catalyst precursors
2
a: yield: 0.046 g, 67%. IR (KBr): 2073 [(CO)], 1726
(acyl)] cm . 1H NMR (300 MHz, CDCl ) data (ı in ppm): ı 2.51
−
1
CH OH (0.099 mol, 4 cm ), CH3I (0.016 mol, 1 cm ), H O
3 2
3
3
[
(
3
3
3H, s, CH ), ı 7.93–8.39 (4H, m, Ph), ı 8.69 (H-3, d, JH–H = 7.7 Hz,
Py), ı 9.64 (H-4, d, JH–H = 7.7 Hz, Py). C NMR (75 MHz, CDCl ) data
ı in ppm): ı 45.0 (CH ), ı 123.9–151.3 (m, Ph, Py), ı 169.9 (COOH),
ı 189 (br, CO), ı 204.0 (br, COacyl).
(0.055 mol, 1 cm ) and catalyst (0.0514 mmol) were taken into the
reactor. The reactor was then purged with CO for about 5 min and
then pressurized with CO gas (5, 10 and 20 bar) at 25 C. The car-
bonylation reactions were carried out at 130 ± 2 C for 1 h with CO
3
13
3
◦
(
3
◦