Robust and Electron-Rich cis-Palladium(II) Complexes
FULL PAPER
H), 7.67 (d, J=7.4 Hz, 2H; Ph-H), 8.88 (s, 1H; NCHN), 10.94 ppm (s,
1H; NH); 13C{1H} NMR ([D6]DMSO): d=48.4 (CH2), 49.8 (CH2), 50.4
(CH2), 51.1 (CH2), 119.6 (CH), 124.1 (CH), 128.9 (CH), 129.2 (CH),
129.3 (CH), 134.2 (CH2C), 139.0 (O=CNC), 160.0 (NCHN), 165.2 ppm
(C=O); positive mode ESMS m/z: 294.23 [MꢀCl]+; elemental analysis
calcd (%) for C18H20N3OCl: C 65.55, H 6.11, N 12.74; found: C 65.39, H
6.03, N 12.87.
CH3CN (10 mL), THF (15ꢂ4mL), and H2O/MeoH (1:1), and then dried
under vacuum. Crystals suitable for X-ray diffraction studies were grown
by layer diffusion of dichloromethane into a dichloromethane solution of
the compound. Yield: 0.120, 31%; m.p. 2988C (dec); 1H NMR
([D6]DMSO): d=3.78 (d, J=14.4 Hz, 1H; NCHaHbC=O), 5.00 (d, J=
17.0 Hz, 1H; NCHaHbPh), 5.47 (d, J=14.4 Hz, 1H; NCHaHbC=O), 5.74
(d, J=17.0 Hz, 1H; NCHaHbPh), 6.82 (d, J=1.8 Hz, 1H; imi-H), 7.07 (t,
J=7.1 Hz; Ph-H), 7.26–7.53 (t, 25H; Ph-H, imi-H), 10.35 ppm (s, 1H;
NH); 13C{1H} NMR ([D6]DMSO): d=53.2 (CH2), 53.5 (CH2), 119.6
(CH), 121.8 (CH), 123.8 (CH), 126.2 (CH), 128.6 (CH), 128.8 (CH),
128.9–129.4 (overlapping signals CH), 128.8 (CH), 129.4 (CH), 130.2
(CH), 131.4 (unresolved, PC), 134.3 (d, 2JPC =11.1 Hz; PPh-CH), 135.8
(CH2C), 138.8 (O=CNC), 160.1 (NCN), 164.8 ppm (C=O); 31P{1H} NMR
([D6]DMSO): d=28.0 ppm; elemental analysis calcd (%) for
C36H32Cl2N3OPPd·0.75CH3OH: C 58.46, H 4.67, N 5.56; found: C 58.53,
H 4.92, N 5.69.
Synthesis of 3: A mixture of 2-(4,5-dihydro-1H-imidazol-1-yl)methylpyri-
dine (2.41 g, 14.9 mmol) and benzyl chloride (1.72 mL, 14.9 mmol) in
DMF (8 mL) was allowed to react at 808C for 2 days. After cooling, the
solvent was completely removed under vacuum. The brown residue was
washed several times with THF and diethyl ether, filtered on a frit under
nitrogen, and dried under vacuum. The compound is highly hygroscopic.
Yield: 3.12 g, 72%; 1H NMR (CDCl3): d=3.80 (m, 4H; NCH2CH2N),
4.80 (s, 2H; CH2C=O), 4.93 (s, 2H; PhCH2), 7.17 (dd, J=7.5, 5.1 Hz, 1H;
py-H), 7.24–7.35 (m, 5H; Ph-H), 7.45 (d, J=7.4 Hz, 1H; py-H), 7.63 (t,
J=7.7 Hz, 1H; py-H), 8.44 (d, J=4.2 Hz; py-H), 10.34 ppm (s, 1H;
NCHN); 13C{1H} NMR (CDCl3): d=47.6 (CH2), 48.4 (CH2), 52.0 (CH2),
52.5 (CH2), 123.2 (py-CH), 123.3 (py-CH), 128.6 (Ph-CH), 128.7 (Ph-
CH), 129.0 (Ph-CH), 132.4 (Ph-C), 137.3 (py-CH), 149.4 (py-CH), 152.6
(py-C), 159.4 ppm (NCHN); positive mode ESMS m/z: 252.15 [MꢀCl]+,
270.14 [MꢀCl+H2O]+; HRMS (FAB+): calcd for C16H18N3: 252.1501;
found: 252.1498.
Synthesis of 9: A mixture of 2 (0.269 g, 0.814 mmol), KHMDS (0.162 g,
0.814 mmol), PdCl2 (0.144 g, 0.814 mmol), and PPh3 (0.214 g, 0.814 mmol)
was stirred in acetonitrile (25 mL) at room temperature for 1 day. The in-
soluble solid was collected on a frit, washed with acetonitrile (10 mL)
and THF (15 mLꢂ4). The solid was then extracted with dichloromethane
(50 mL). The solvent was reduced to ca. 3 mL under vacuum. Upon addi-
tion of diethyl ether, a white solid was formed. Crystals suitable for X-
ray diffraction studies were grown by slow evaporation from its chloro-
form solution. Yield: 0.15, 26%; m.p. 2688C (dec); 1H NMR (CDCl3):
d=2.80 (virtual q, J=9.7 Hz, 1H; NCHaHbCHcHdN), 2.96 (virtual q, J=
9.7 Hz, 1H; NCHaHbCHcHdN), 3.18 (virtual q, J=9.7 Hz, 1H;
NCHaHbCHcHdN), 3.39 (virtual q, J=9.7 Hz, 1H; NCHaHbCHcHdN),
3.45 (d, J=15.0 Hz, 1H; NCHaHbC=O), 4.08 (d, J=14.0 Hz, 1H;
NCHaHbPh), 5.45 (d, J=15.0 Hz, 1H; NCHaHbC=O), 5.55 (d, J=
14.0 Hz, 1H; NCHaHbPh), 7.06 (t, J=7.8 Hz, 1H; Ph-H), 7.23–7.29 (m,
7H; Ph-H), 7.42–7.52 (m, 9H; Ph-H), 7.68–7.80 (m, 8H; Ph-H), 9.74 ppm
(s, 1H; NH); 13C{1H} NMR (CD2Cl2): d=47.9 (NCH2CH2N), 48.1
(NCH2CH2N), 54.5 (PhCH2), 55.8 (CH2CO), 119.9 (CH), 124.2 (CH),
Synthesis of 5: A mixture of 2 (0.164 g, 0.353 mmol), NaOAc (0.0289 g,
0.353 mmol), and PdCl2 (0.0313 g, 0.176 mmol) in acetonitrile (initial
water content ca. 1–2%; 15 mL) was allowed to react at room tempera-
ture for 1 day. The yellow precipitate was collected on a frit, washed with
CH3CN and methanol, and then dried under vacuum. Crystals suitable
for X-ray diffraction studies were grown by vapor diffusion of diethyl
ether into a 1:1 DMF/MeOH solution of the compound. Yield: 0.0167 g,
12%; m.p. 2108C (dec).
Synthesis of 6: A mixture of 3 (0.0559 g, 0.309 mmol), NaOAc (0.0253 g,
0.309 mmol), and PdCl2 (0.0548 g, 0.309 mmol) in CH3CN (10 mL) was
allowed to react at room temperature overnight. The solution was de-
128.5 (CH), 128.6 (d, 3JPC =2.1 Hz, PPh CH), 128.8 (CH), 129.1 (CH),
ꢀ
ACHTUNGTRENNUNGcanted and the residual solid was washed with wet methanol twice. The
2
129.8 (CH), 131.7 (d, 1JPC =2.6 Hz; PC), 133.5 (CH2C), 134.3 (d, JPC
=
solid was then filtered under nitrogen and dried under vacuum. The
1H NMR spectrum indicates a mixture of products. Small amounts of
crystals of 6 can be obtained by vapor diffusion of diethyl ether into a
DMF solution containing the mixture.
11.0 Hz; PPh-CH), 138.2 (O=CNC), 164.9 (C=O), 193.3 ppm (NCN);
31P{1H} NMR (CDCl3): d=27.6 ppm; elemental analysis calcd (%) for
C36H34Cl2N3OPPd: C 58.99, H 4.67, N 5.73; found: C 58.79, H 4.75, N
5.63.
Synthesis of 7: A mixture 3 (0.129 g, 0.488 mmol), KHMDS (0.109 g,
0.448 mmol), PdCl2 (0.079 g, 0.448 mmol), and PPh3 (0.1176 g,
0.448 mmol) in acetonitrile (20 mL) was stirred at room temperature
overnight. The solution was filtered through a plug of Celite. The solvent
was then removed under vacuum. The residue was re-dissolved in THF
(20 mL) and the solution was filtered through a plug of Celite. The sol-
vent was reduced to approximately 3 mL. Upon the addition of diethyl
ether, a pale-yellow precipitate was formed. The solid was filtered on a
frit, washed with diethyl ether and toluene, and dried under vacuum.
Crystals suitable for X-ray diffraction studies were grown by vapor diffu-
sion of diethyl ether into a MeOH solution of the compound. Yield:
0.053 g, 17%; m.p. 2278C; 1H NMR (CDCl3): d=2.80 (virtual q, J=
10.0 Hz, 1H; NCHaHbCHcHdN), 3.09 (virtual q, J=10.0 Hz, 1H;
NCHaHbCHcHdN), 3.26 (m, 2H; NCHaHbCHcHdN), 3.68 (d, J=14.0 Hz,
1H; NCHaHbPh), 4.69 (d, J=15.0 Hz, 1H; NCHaHbPy), 5.39 (d, J=
14.0 Hz, 1H; NCHaHbPh), 5.50 (d, J=15.0 Hz, 1H; NCHaHbPy), 7.04–
7.76 (m, 22H; py-H, PPh-H, Ph-H), 7.89 (d, J=7.8 Hz, 1H; py-H),
8.48 ppm (d, J=4.2 Hz, 1H; py-H); 13C{1H} NMR (CDCl3): d=47.8
(NCH2CH2N), 48.9 (NCH2CH2N), 54.2 (CH2Ph), 55.8 (CH2Py), 123.5
(py-CH), 124.4 (py-CH), 128.5–128.8 (PPh-CH, PPh-C, Ph-CH), 129.1
(Ph-CH), 129.8 (Ph-CH), 131.6 (unresolved d; PPh-C), 133.8 (Ph-C),
134.4 (d, 2JPC =11.2 Hz; PPh-CH), 138.0 (py-CH), 149.6 (py-CH), 154.4
(py-C), 192.6 ppm (NCN); 31P{1H} NMR (121.49 MHz, CDCl3): d=
27.8 ppm; elemental analysis calcd (%) for C34H32Cl2N3PPd: C 59.10, H
4.67, N 6.08; found: C 59.20, H 4.75, N 6.01.
Synthesis of 10: A mixture of 8 (0.105 g, 0.143 mmol) and PCy3 (0.0603 g,
0.215 mmol) was stirred in dichloromethane (20 mL) at room tempera-
ture overnight. The solution was allowed to filter through a small plug of
Celite. The solvent was then completely removed under vacuum. The res-
idue was washed with THF (15 mL). The white powder was collected on
a frit and dried under vacuum. Crystals suitable for X-ray diffraction
studies were grown by layer diffusion of MeOH into a dichloromethane
solution of the compound. Yield: 0.0559 g, 52.0%; m.p. 277–2798C;
1H NMR (CD2Cl2): d=1.25–1.97 (m, 24H; Cy-H), 2.17–2.25 (m, 9H; Cy-
H), 4.63 (d, J=14.5 Hz, 1H; NCHaHbC=O), 5.09 (d, J=14.1 Hz, 1H;
NCHaHbPh), 5.96 (d, J=14.5 Hz, 1H; NCHaHbC=O), 6.11 (d, J=
14.1 Hz, 1H; NCHaHbPh), 6.84 (d, J=2.0 Hz, 1H; imi-H), 7.08 (t, J=
7.4 Hz, 1H; Ph-H), 7.20 (d, J=2.0 Hz, 1H; imi-H), 7.29 (t, J=8.0 Hz,
2H; Ph-H), 7.40–7.44 (m, 3H; Ph-H), 7.52–7.55 (m, 2H; Ph-H), 7.66 (d,
J=7.4 Hz, 2H; Ph-H), 9.72 ppm (brs, 1H; NH); 13C{1H} NMR (CD2Cl2):
d=26.0 (Cy-CH2), 27.2 (d, JPC =11.2 Hz; Cy-CH2), 30.3 (d, JPC =7.9 Hz;
Cy-CH2), 37.4 (d, 1JPC =24.3 Hz; Cy-CH), 55.6 (CH2), 57.0 (CH2), 119.8
(CH), 121.8 (imi-CH), 122.9 (imi-CH), 124.2 (CH), 128.6 (CH), 128.9
(CH), 129.0 (CH), 129.3 (CH), 134.0 (CH2C), 138.1 (O=CNC), 163.2
(NCN), 164.1 ppm (C=O); 31P{1H} NMR (CD2Cl2): d=50.8 ppm; elemen-
tal analysis calcd (%) for C36H50Cl2N3OPPd: C 57.72, H 6.73, N 5.61;
found: C 57.88, H 6.73, N 5.69.
2
3
Synthesis of 11: A mixture of 9 (0.123 g, 0.168 mmol) and PCy3 (0.094 g,
0.336 mmol) was stirred in dichloromethane (25 mL) at room tempera-
ture overnight. The solvent was then completely removed under vacuum.
Diethyl ether (30 mL) and THF (5 mL) were added to wash the residual
solid. The white powder was collected on a frit and dried under vacuum.
Crystals suitable for X-ray diffraction studies were grown by vapor diffu-
Synthesis of 8: A mixture of 1 (0.172 g, 0.530 mmol), KHMDS (0.105 g,
0.530 mmol), PdCl2 (0.0931 g, 0.530 mmol), and PPh3 (0.138 g,
0.530 mmol) in acetonitrile (20 mL) was allowed to react at room temper-
ature overnight. The precipitate was then collected on a frit, washed with
Chem. Eur. J. 2009, 15, 405 – 417
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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