Supporting Information
A Novel Iron Complex for Cross-coupling Reactions of Multiple
C-Cl Bonds in Polychlorinated Solvents with Grignard Reagents
Yashraj Gartia,a Sharon Pulla,a Punnamchandar Ramidi,a Carolina Costa Farris,a
Zeid Nima,b Darin E. Jones,a Alexandru S. Biris,bζ and Anindya Ghosh*aζ
a
Department of Chemistry, University of Arkansas at Little Rock, 2801 South University Avenue, AR 72204, U.S.A
b
Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University
Avenue, AR 72204, U.S.A
*Corresponding author: E-mail: axghosh@ualr.edu, Phone: 501 569 8827, Fax: 501 569 8838
ζ
These two authors contributed equally to this manuscript
Synthesis of the 1 and 2
The ligand (1) was synthesized according to the literature procedure [S1]. Ligand and the
iron(III) complex (2) synthesis are presented schematically in the Figure S1.
O
a)
Reflux, 3 h
O + 2 SOCl
2
N
O
Dimethoxyethane
Cl
OH
OH
NH2
O
O
N
Cl
Pyridine-2,6-dicarbonyl dichloride
Pyridine-2,6-dicarboxylic acid
b)
O
+ 2
O
N
Et3N, THF
NH
2 h, 0 oC
Cl
O
N
HN
Cl
N2,N6-bis(2,6-diisopropylphenyl)pyridine-2,6dicarboxamide (1)
O
c)
O
N
NH
HN
i) nBuli (2.5 eq)
ii) FeCl3
THF, 0 oC
(1)
O
O
N
N
Fe
N
Cl
2
Figure S1. Schematic representation of ligand (1) and its iron complex synthesis (2).
A. Synthesis of 2, 6-Pyridinedicarboxylic acid chloride.
2, 6-Pyridinedicarboxylic acid (10 g, 0.06 mol) was taken in a round bottom flask and to
it 30 mL of dimethoxyethane was added. To this solution, thionyl chloride (10 mL, 0.14 mol)
was added and refluxed for 3 h. The solvent dimethoxyethane and excess of thionyl chloride
were removed under vacuum to obtain a pale white product. Pure white crystalline acid chloride
was obtained by recrystallization from hexane. Yield 80% (9.73 g). 1H NMR (60 MHz, 295K,
CDCl3, δ): 8.50 (m, 2H); 8.75 (d, 1H). FT-IR (KBr, cm-1) 704 (s, str, C-Cl), 1710 (s, str, CO).
B. Synthesis of N2,N6-bis(2,6-diisopropylphenyl)pyridine-2,6-dicarboxamide (1).
The reaction was performed under inert atmosphere. 2,6-Pyridinedicarboxylic acid
chloride (1 g, 0.005 mol) was taken in a round bottom flask with 15 mL THF. The solution was
cooled to 0 °C using an ice bath. A mixture of 2,6-diisopropyl aniline (2 mL, 0.01 mol) and
triethylamine (1.6 mL, 0.0115 mol) in 15 mL THF were added drop-wise in a 2, 6-THF solution
of pyridinedicarboxylic acid chloride by an addition funnel. The reaction mixture was stirred at 0
°C for 2 h. A precipitate of triethylammine hydrochloride salt formed during the reaction. After 2
h the reaction mixture was filtered to remove the precipitate. The solvent was removed using a
rotary evaporator. The crude product was washed with hot hexane and the product was
crystalized from ethanol.
Yield 63% (1.5 g). 1H NMR (600 MHz, 298 K, CDCl3, δ) :1.29 (d, 24H, JH-a,H-b = 6.87 Hz,CH3);
3.25 (m, 4H, JH-a,H-b = 6.87 Hz,CH ); 7.38 (t, 2H); 7.24 (d, 4H); 8.6 (m, 1H); 8.74 (d, 2H); 9.11 (s,
2H). 13C{1H} NMR (CDCl3, 298 K): δ 162.6 (C-7), 148.8 (C-2, C-6), 146.0 (C-9), 139.7 (C-4),
130.6 (C-8), 128.7 (C-3, C-5), 126.0 (C-10), 123.7 (C-11), 29.0 (C-CH), 23.7 (C-CH3). FT-IR
(KBr, cm-1) 3363 (s, m, NH), 3287 (s, str, NH), 1660 (s, str, CO). ESI-MS (negative ion mode):
m/z 484.5 (M-H+, 100). Anal. Calcd for C31H39N3O2 (Mol Wt 485.7): C, 76.66; H, 8.09; N, 8.65.
Found: C, 76.61; H, 8.12; N, 8.73.
C. Synthesis of Fe (III) complex (2)
Ligand (1, 145 mg, 0.3 mmol) was dissolved in 10 mL of dry THF under N2 atmosphere
and cooled to 0 °C. n-Butyllithium (0.4 mL, 0.63 mmol, 1.6 M in hexane) was added slowly to
the reaction mixture at 0 °C. After stirring the reaction mixture for 30 min, anhydrous solid
FeCl3 (48.6 mg, 0.3 mmol) was added to the reaction mixture. The solution was warmed up to
room temperature and stirred overnight to yield a red solution. The reaction mixture was filtered
and passed through a short column of alumina to remove any precipitate and impurities. After
that the solvent was removed under reduced pressure to obtain a red solid.
Yield: 91% (156 mg). ESI-MS: m/z 575.1, 1620 cm-1 (s, str, CO), λmax: 364 nm, ε: 2664 M-1cm-1,
E1/2 : 0.03 V and ∆Ep : 0.97 V. Calcd for C31H37ClFeN3O2•C4H8O: C, 64.97; H, 7.01; N, 6.49.
Found: C, 64.61; H, 6.84; N, 6.68.
a
200
150
100
50
0
ppm
b
c
10
8
6
4
ppm
2
0
Figure S2 :1H-NMR of the ligand (1). Inset figure shows the
13
C-NMR of the ligand. 1H NMR
(600 MHz, 298 K, CDCl3, δ) :1.29 (d, 24H); 3.25 (m, 4H); 7.38 (t, 2H); 7.24 (d, 4H); 8.6 (m,
1H); 8.74 (d, 2H); 9.11 (s, 2H). 13C{1H} NMR (CDCl3, 298 K): δ 162.6 (C-7), 148.8 (C-2, C-6),
146.0 (C-9), 139.7 (C-4), 130.6 (C-8), 128.7 (C-3, C-5), 126.0 (C-10), 123.7 (C-11), 29.0 (CCH), 23.7 (C-CH3).
2.5e+5
100
intensity
relative intensity
2.0e+5
80
60
40
20
1.5e+5
0
484.0 484.5 485.0 485.5 486.0 486.5 487.0 487.5 488.0
m/z
1.0e+5
5.0e+4
0.0
480
482
484
486
488
490
492
494
m/z
Figure S3: ESI-MS of the ligand (1), m/z 484.5 (M-H). Inset figure shows the theoretically
predicted mass spectrum of the ligand. m/z 485.30 (100.0%), 486.31 (34.1%), 487.31 (6.0%),
486.30 (1.1%)
1.0e-5
current (uA)
5.0e-6
0.0
-5.0e-6
-1.0e-5
-1.5e-5
-0.2
-0.1
0.0
0.1
potential (V)
0.2
0.3
Figure S4: Cyclic voltammogram of complex 2 in acetonitrile (0.1 M n-tetrabutylammonium
hexafluorophosphate) at room. A scan rate of 100 mV/s was used within a voltage range of 0.15 to 0.3 V. A glassy carbon electrode was used as the working electrode. A platinum ring
electrode was used as the counter electrode. Ag/AgCl was used as the reference electrode.
Pentene
intensity
3e+7
2e+7
1e+7
Decane
Octane
Hexane
Nonane
0
2
4
6
8
Retention time (min)
Figure S5: Gas chromatogram of reaction of CH2Cl2 with 12 equivalents of butylmagnesium
chloride. Reactions were performed in THF using 2 (0.5 mg, 0.87 µmol), CH2Cl2 (27 µL, 0.42
mmol) and butylmagnesium chloride (2.5 mL, 5.04 mmol) at room temperature.
5e+7
Dichloromethane
intensity
4e+7
3e+7
Pentene
2e+7
1e+7
Decane
Octane
Nonane
Hexane
0
2
3
4
5
6
7
8
Retention time (min)
Figure S6: Gas chromatogram of reaction of CH2Cl2 with 1 equivalent of butylmagnesium
chloride. Chromatogram shows large amount of unreacted CH2Cl2 as only 1 equivalent of
Grignard reagent was used. Reactions were performed in THF using 2 (0.5 mg, 0.87 µmol),
CH2Cl2 (27 µL, 0.42 mmol) and butylmagnesium chloride (0.2 mL, 0.42 mmol) at room
temperature.
1e+7
Decane
Nonene
intensity
8e+6
6e+6
Pentene
4e+6
5-butyl nonane
2e+6
0
2
4
6
8
Retention time (min)
Figure S7: Gas chromatogram of cross coupling of CHCl3 with butylmagnesium chloride.
Reactions were performed in THF using 2 (0.5 mg, 0.87 µmol), CHCl3 (34 µL, 0.42 mmol) and
butylmagnesium chloride (0.63 mL, 1.26 mmol) at room temperature.
6e+7
Triphenylmethane
5e+7
Decane
intensity
4e+7
3e+7
2e+7
Diphenylmethane
1e+7
Toluene
0
2
4
6
8
10
12
14
16
18
20
Retention Time (min)
Figure S8: Gas chromatogram of cross coupling of CHCl3 with phenylmagnesium chloride.
Reactions were performed in THF using 2 (0.5 mg, 0.87 µmol), CHCl3 (34 µL, 0.42 mmol) and
phenylmagnesium chloride (0.63, 1.26 mmol) at room temperature.
4e+7
Decane
5-Butyl nonane
Intensity
3e+7
2e+7
Nonane
5,5 - Dibutyl nonane
1e+7
0
5
6
7
8
9
Retention time (min)
Figure S9: Gas chromatogram of reaction of CCl4 with 4 equivalent of butylmagnesium
chloride. Reactions were performed in THF using 2 (0.5 mg, 0.87 µmol), CCl4 (40 µL, 0.42
mmol) and butylmagnesium chloride (0.82 mL, 1.68 mmol) at room temperature.
Figure S10: UV/Vis spectra of the 2 and its complexes with various Grignard reagents.
Figure S11: ESI-MS of the butyl complex of (2) m/z 597.4 (M-H). Inset figure shows the
theoretically predicted mass spectrum of the 2 complexed to butyl group (2-butyl group is a
possible intermediate).
2
Absorbance
2
1.5
1.5
1
Absorbance
0.5
0
2
1
4
6
Time / min
8
10
0.5
0
350
400
450
500
550
600
Wavelength (nm)
Figure S12: Decrease in the absorbance of the 2-butyl complex upon addition of CH2Cl2. Inset
figure shows the decrease in absorbance of the 2-butyl complex with time.
References
[S1] J.-C. Wasilke, G. Wu, X. Bu, G. Kehr and G. Erker, Organometallics, 2005, 24, 42894297.