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1627 (s, C@O), 1354 (s, CAN), 653 (w, C@N). UV–Visible (CH2Cl2):
kmax (nm): 233, 247, 371, 457. 1H NMR (CDCl3): (d ppm): 9.27 (d,
2H, H-1), 8.29 (t, 2H, H-3), 8.09 (d, 2H, H-4), 7.94 (t, 2H, H-2),
7.73–7.25 (m, 15H, H-PPh3), 4.26 (m, 2H, H-6), 2.40, 1.83 (m, 8H,
H-7 and H-8). 13C NMR (CDCl3): (d ppm): 204.42 (C„O), 164.14
(C@O), 157.81 (C-5), 152.31 (C-1), 141.82 (C-3), 137.67–128.58
(CAPPh3), 127.63 (C-2), 125.31 (C-4), 52.32 (C-6), 32.68, 24.85
(C-7 and C-8). 31P NMR (DMSO): (d ppm): 28.51 (s, PPh3).
(d, 2H, H-1), 8.64 (d, 2H, HAPy), 8.53 (m, 2H, H-7), 8.39 (t, 2H, H-3),
8.21 (d, 2H, H-4), 7.96 (t, 2H, H-2) 7.82 (t, 2H, HAPy), 7.61 (t, 2H,
HAPy), 7.02 (m, 2H, H-8). 13C NMR (CDCl3): (d ppm): 204.16
(C„O), 163.25 (C@O), 158.17 (C-5), 152.49 (C-1), 152.33 (CAPy),
143.76 (C-6) 141.83 (C-3), 139.21 (CAPy), 128.01 (C-2), 126.41
(C-4), 126.41 (C-4), 125.91 (CAPy), 123.69 (C-8), 121.28 (C-7).
[Ru(CO)(Py)(L3)] (9)
Brown solid, yield: 48%, m.p. 205 °C, elemental analysis calcd.
(%) for C24H23N5O3Ru: C, 54.33; H, 4.37; N, 13.20. Found: C,
54.52; H, 4.60; N, 13.98. IR (KBr Pellets, cmÀ1): 1938 (s, C„O),
1619 (s, C@O), 1341 (s, CAN), 652 (w, C@N). UV–Visible (CH2Cl2):
kmax (nm): 233, 247, 350, 457. 1H NMR (CDCl3): (d ppm): 9.24 (d,
2H, H-1), 8.63 (d, 2H, HAPy), 8.24 (t, 2H, H-3), 8.07 (d, 2H, H-4),
7.96 (t, 2H, H-2,2), 7.81 (t, 2H, HAPy), 7.65 (t, 2H, HAPy), 4.44
(m, 2H, H-6), 2.43, 1.92 (m, 8H, H-7 and H-8). 13C NMR (CDCl3):
(d ppm): 204.51 (C„O), 164.01 (C@O), 157.80 (C-5), 152.37 (C-
1), 152.24 (CAPy), 141.80 (C-3), 139.27 (CAPy), 127.61 (C-2),
125.29 (C-4), 125.09 (CAPy), 54.01 (C-6), 32.71, 24.83 (C-7 and
C-8).
[Ru(CO)(AsPh3)(L1)] (4)
Pale brown solid, yield: 78%, mp. 243 °C, elemental analysis
calcd. (%) for C33H27N4AsO3Ru: C, 56.33; H, 3.87; N, 7.96. Found:
C, 56.53; H, 4.05; N, 7.64. IR (KBr Pellets, cmÀ1): 1941 (s, C„O),
1628 (s, C@O), 1352 (m, CAN), 654 (m, C@N). UV–Visible (CH2Cl2):
kmax (nm): 237, 244, 383, 430. 1H NMR (CDCl3): (d ppm): 9.24 (d,
2H, H-1), 8.35 (t, 2H, H-3), 8.07 (d, 2H, H-4), 7.90 (t, 2H, H-2),
7.88–7.17 (m, 15H, HAAsPh3), 4.05, 3.90 (m, 4H, H-6 and H-7).
13C NMR (CDCl3): (d ppm): 205.01 (C„O), 166.54 (C@O), 157.72
(C-5), 152.41 (C-1), 141.44 (C-3), 137.82–127.87 (CAAsPh3),
127.70 (C-2), 125.51 (C-4), 51.63 (C-6 and C-7).
[Ru(CO)(AsPh3)(L2)] (5)
General procedure for the ruthenium-catalyzed transfer
hydrogenation of ketones
Pale brown solid, yield: 69%, m.p. 248 °C, elemental analysis
calcd. (%) for C37H27N4AsO3Ru: C, 59.12; H, 3.62; N, 7.45. Found:
C, 59.75; H, 3.64; N, 7.48. IR (KBr Pellets, cmÀ1): 1945 (s, C„O),
1625 (s, C@O), 1342 (m, CAN), 652 (w, C@N). UV–Visible (CH2Cl2):
kmax (nm): 207, 245, 352, 447. 1H NMR (CDCl3): (d ppm): 9.26 (d,
2H, H-1), 8.57 (m, 2H, H-7), 8.38 (t, 2H, H-3), 8.19 (d, 2H, H-4),
7.93 (t, 2H, H-2) 7.85–7.20 (m, 15H, HAAsPh3), 7.06 (m, 2H, H-8).
13C NMR (CDCl3): (d ppm): 204.17 (C„O), 163.27 (C@O), 158.27
(C-5), 152.45 (C-1), 143.71 (C-6), 141.88 (C-3), 137.68–128.47
(CAAsPh3), 128.09 (C-2), 126.45 (C-4), 123.63 (C-8), 121.22 (C-7).
ESI–MS (m/z): 751 (M+).
The catalytic transfer hydrogenation reactions were conducted
at a substrate/catalyst/base(S/C/base) molar ratio of 1:0.005:4.
The procedure was described as follows. A mixture containing ke-
tone (1 mmol), the ruthenium complex (1–9) (0.005 mmol) and
KOH (4 mmol) in 10 ml of iPrOH was heated to reflux for 2 h. After
completion of reaction the catalyst was removed from the reaction
mixture by the addition of petroleum ether followed by filtration
and subsequent neutralization with 1 M HCl. The ether layer was
filtered through a short path of silica gel by column chromatogra-
phy. The filtrate was subjected to GC analysis and the hydroge-
nated product was identified and determined with authentic
samples.
[Ru(CO)(AsPh3)(L3)] (6)
Brown solid, yield: 45%, m.p. 258 °C, elemental analysis calcd.
(%) for C37H33N4AsO3Ru: C, 58.65; H, 4.39; N, 7.39. Found: C,
58.92; H, 4.65; N, 7.98. IR (KBr Pellets, cmÀ1): 1940 (s, C„O),
1625 (s, C@O), 1354 (s, CAN), 653 (m, C@N). UV–Visible (CH2Cl2):
kmax (nm): 217, 222, 237, 382, 443. 1H NMR (CDCl3): (d ppm): 9.29
(d, 2H, H-1), 8.28 (t, 2H, H-3), 8.23 (d, 2H, H-4), 7.90 (t, 2H, H-2),
7.83–7.16 (m, 15H, HAAsPh3), 4.21 (m, 2H, H-6), 2.46, 1.87 (m,
8H, H-7 and H-8). 13C NMR (CDCl3): (d ppm): 204.47 (C„O),
164.11 (C@O), 157.79 (C-5), 152.37 (C-1), 141.78 (C-3), 137.41–
128.51 (CAAsPh3), 127.61 (C-2), 125.37 (C-4), 53.37 (C-6), 32.72,
24.84 (C-7 and C-8).
General procedure for the ruthenium-catalyzed N-alkylation of amine
A mixture of amine (0.3 mmol), ruthenium(II) complex (1, 2, 4
and 5) (3 Â 10–3 mmol), tBuOK (0.12 mmol) in benzyl alcohol or
p-methoxybenzyl alcohol (0.9 mmol) was placed in a flask under
atmospheric pressure of nitrogen and heated by an oil bath at
110 °C for 6 h. Then brine (3 ml) and CH2Cl2 (5 ml) were added.
The organic layer was separated and the aqueous layer was ex-
tracted into CH2Cl2. The combined organic extracts were dried with
magnesium sulfate and concentrated. The compounds were puri-
fied by chromatography and characterized by NMR spectroscopy.
The product yields were obtained by the 1H NMR integration com-
pared to the internal standard.
[Ru(CO)(Py)(L1)](7)
Brown solid, yield: 54%, m.p. 185 °C, elemental analysis calcd.
(%) for C20H17N5O3Ru: C, 50.42; H, 3.60; N, 14.70. Found: C,
50.58; H, 3.80; N, 14.72. IR (KBr Pellets, cmÀ1): 1941 (s, C„O),
1624 (s, C@O), 1347 (s, CAN), 649 (w, C@N). UV–Visible (CH2Cl2):
kmax (nm): 202, 221, 242, 382, 495. 1H NMR (CDCl3): (d ppm): 9.25
(d, 2H, H-1), 8.60 (d, 2H, Py), 8.38 (t, 2H, H-3), 8.06 (d, 2H, H-4),
7.93 (d, 2H, H-2), 7.84 (t, 2H, HAPy), 7.65 (t, 2H, HAPy), 4.03–
3.97 (4H, H-6 and H-7). 13C NMR (CDCl3): (d ppm): 205.12
(C„O), 166.57 (C@O), 157.71 (C-5), 152.47 (C-1), 151.27 (CAPy),
141.43 (C-1), 138.82 (CAPy), 127.77 (C-2), 125.94 (CAPy), 125.53
(C-4), 51.68 (C-6 and C-7).
N-phenylbenzylamine
1H NMR (300 MHz, CDCl3): d (ppm): 7.34–7.01 (m, 5H, phenyl),
7.11 (m, 2H, phenyl), 6.72 (t, 1H, phenyl), 6.58 (d, 2H, phenyl), 4.31
(s, 2H, ACH2NHA), 3.92 (br, 1H, ANHA).
N-phenyl-(p-methoxybenzyl) amine
1H NMR (300 MHz, CDCl3): d (ppm): 7.26 (d, 2H, phenyl), 7.17
(m, 2H, phenyl), 6.89 (d, 2H, phenyl), 6.65 (d, 2H, phenyl), 6.21
(d, 1H, phenyl), 4.21 (s, 2H, ACH2NHA), 3.95 (br, 1H, ANHA),
3.83 (s, 3H, AOMe).
[Ru(CO)(Py)(L2)] (8)
Green solid, yield: 64%, m.p. 196 °C, elemental analysis calcd.
(%) for C24H17N5O3Ru: C, 55.96; H, 3.27; N, 13.35. Found: C,
55.98; H, 3.84; N, 13.40. IR (KBr Pellets, cmÀ1): 1941 (s, C„O),
1618 (s, C@O), 1338 (s, CAN), 652 (m, C@N). UV–Visible (CH2Cl2):
kmax (nm): 202, 211, 242, 320, 434. 1H NMR (CDCl3): (d ppm): 9.34
Antioxidant assays
The ability of ruthenium complexes to act as hydrogen donors
or free radical scavengers was explored by conducting a series of