22
J. Lasri / Polyhedron 57 (2013) 20–23
have been reported previously by us [12a]. C, H and N elemental
analyses were carried out by the Microanalytical Service of the
Instituto Superior Técnico. 1H and 13C spectra (in CDCl3) were mea-
sured on a Bruker Avance II 400 MHz (UltraShield™ Magnet) spec-
trometer at ambient temperature. 1H and 13C chemical shifts (d)
are expressed in ppm relative to Si(Me)4. J values are in Hz. Infrared
spectra (4000–400 cmÀ1) were recorded on a Bio-Rad FTS 3000MX
and a Jasco FT/IR-430 instrument in KBr pellets and the wavenum-
bers are in cmÀ1. Electrospray mass spectra were carried out with
an ion-trap instrument (Varian 500-MS LC Ion Trap Mass Spec-
trometer) equipped with an electrospray (ESI) ion source. The solu-
tions in methanol were continuously introduced into the mass
whereupon the colourless [Pd(dppe)2]Cl2 precipitated. This precip-
itate was separated by filtration and identified by 31P{1H}(CDCl3)
NMR: d = 55.9 (56.7 ppm [13]). The solution was then dried in va-
cuo, washed with three 5 mL portions of hexane and dried under
air.
No reaction was observed using complex 1 and 1 eq of dppe,
and only the starting material was recovered.
: yield, 90%. IR (cmÀ1): 1676
NC(=O)C6F4NCCH2CH2CMe2 1a:
m
(NC@O), 1583 m
(NC@N). 1H NMR (CDCl3), d: 1.75 and 1.76 (two
s, 6H, two CH3), 2.27 (t, JHH 8 Hz, 2H, CH2), 3.15 (t, JHH 8 Hz, 2H,
CH2). 13C{1H} NMR (CDCl3), d: 27.1 and 27.3 (CH3), 31.3 and 38.3
(CH2), 71.6 (C(Me)2), 126.9–134.4 (Caromatic), 151.5 (NC@N), 167.4
(NC@O). ESI+-MS, m/z: 287 [M + H]+. Anal. Calc. for C13H10N2OF4:
C, 54.55; H, 3.52; N, 9.79. Found: C, 54.73; H, 3.34; N, 9.54%.
spectrometer source with a syringe pump at a flow rate of 10 lL/
min. The drying gas temperature was maintained at 350 °C and
dinitrogen was used as the nebulizer gas at a pressure of 35 psi.
Scanning was performed from m/z = 50 to 1500.
: yield, 87%. IR (cmÀ1): 1691
N=C(Pr)ONCHCH2CH2CMe2 2a:
m
(C@N). 1H NMR (CDCl3), d: 0.99 (t, JHH 7.2 Hz, 3H, CH3CH2), 1.31
4.2. Synthesis of complex 3
and 1.39 (two s, 6H, two CH3), 1.62–1.72 (m, 2H, CH2), 2.20–2.25
(m, 2H, CH2), 2.90–2.92 (m, 4H, CH2), 5.15 (m, 1H, N–CH–
N).13C{1H} NMR (CDCl3), d: 14.2 (CH3CH2), 19.5 (CH2CH3), 22.5
and 27.9 ((CH3)2C), 29.7 and 31.1 (CH2CH2), 32.1 (CH2CH2CH3),
61.7 (Me2C–N), 87.1 (N–CH–N), 167.7 (C(O)@N). ESI+-MS, m/z:
183 [M+H]+. Anal. Calc. for C10H18N2O: C, 65.90; H, 9.95; N,
15.37. Found: C, 65.50; H, 9.57; N, 15.55%.
A solution of 4-cyanobenzaldehyde (29.6 mg, 0.226 mmol) in
acetone (4 mL) was added at room temperature to cyclic nitrone
(25.6 mg, 0.226 mmol) and palladium(II) chloride (20.0 mg,
0.113 mmol), and the mixture was stirred at room temperature
for 1 d. Along the course of the reaction, the brown powder of PdCl2
dissolved, forming an homogeneous light yellow solution. The
reaction mixture was then dried in vacuo, washed with three
5 mL portions of diethyl ether and dried under air. The final com-
plex 3 was recrystallized from acetone.
: yield, 85%. IR (cmÀ1):
N=C(p-CHOC6H5)ONCHCH2CH2CMe2 3a.
1635 m(C@N) and 1681 m
(C@O). 1H NMR (CDCl3), d: 1.27 and 1.31
(two s, 6H, two CH3), 1.96 (t, JHH 7.5 Hz, 2H, CH2), 2.44 (t, JHH
7.5 Hz, 2H, CH2), 5.17 (m, 1H, N–CH–N), 7.48 (d, JHH 7.8 Hz, 2H,
CHaromatic), 7.89 (d, JHH 7.8 Hz, 2H, CHaromatic), 10.09 (s, 1H, CHO).
13C{1H} NMR (CDCl3), d: 22.1 and 28.2 (CH3), 28.7 and 31.7 (CH2),
68.2 (Me2C–N), 90.5 (N–CH–N), 128.9, 130.7, 134.3 and 138.5 (Caro-
matic), 159.9 (C(O)@N), 191.5 (HC@O). ESI+-MS, m/z: 245 [M + H]+
and 277 [M + Na]+. Anal. Calc. for C14H16N2O2: C, 68.83; H, 6.60;
N, 11.47. Found: C, 68.49; H, 6.54; N, 11.65%.
:
yield,
Trans-[PdCl2{N=C(p-CHOC6H4)ONCHCH2CH2CMe2}2] 3
79%. IR (cmÀ1): 1639
m(C@N) and 1705
m
(C@O). 1H NMR (CDCl3),
d: 1.30 and 1.32 (two s, 6H, two CH3), 2.07 (t, JHH 7.5 Hz, 2H,
CH2), 3.39 (t, JHH 7.5 Hz, 2H, CH2), 5.66 (dd, JHH 7.2 Hz, JHH 3.3 Hz,
1H, N–CH–N), 8.07 (d, JHH 7.8 Hz, 2H, CHaromatic), 8.93 (d, JHH
7.8 Hz, 2H, CHaromatic), 10.11 (s, 1H, CHO). 13C{1H} NMR (CDCl3),
d: 21.9 and 27.6 (CH3), 29.3 and 34.3 (CH2), 69.9 (Me2C–N), 89.5
(N–CH–N), 128.3, 130.6, 137.2 and 139.3 (Caromatic), 163.7
(C(O)@N), 191.1 (HC@O). ESI+-MS, m/z: 667 [M+H]+. Anal. Calc.
for C28H32N4O4Cl2Pd: C, 50.50; H, 4.84; N, 8.41. Found: C, 50.39;
H, 4.54; N, 8.45%.
: yield, 80%. IR (cmÀ1):
N=C(Ph)ON(Me)C(H)(C6H2Me3-2,4,6) 4a.
1675 (C@N). 1H NMR (CDCl3), d: 2.18, 2.26 and 2.42 (three s, 9H,
CH3Ph), 2.52 (s, 3H, CH3N), 5.45 (s, 1H, N–CH–N), 7.43–7.94 (m,
7H, CHaromatic). 13C{1H} NMR (CDCl3), d: 20.3, 20.9 and 21.7 (CH3-
Ph), 47.1 (CH3N), 90.7 (N–CH–N), 126.9, 127.4, 128.6, 131.8,
131.9, 133.9, 136.9 and 140.1 (Caromatic), 161.7 (C(O)@N). ESI+-MS,
m/z: 281 [M+H]+. Anal. Calc. for C18H20N2O: C, 77.11; H, 7.19; N,
9.99. Found: C, 77.46; H, 7.34; N, 9.55%.
4.3. Synthesis of complex 4
A solution of acyclic nitrone (39.6 mg, 0.224 mmol) in benzoni-
trile (4 mL) was added at room temperature to palladium(II) chlo-
ride (20.0 mg, 0.113 mmol), and the mixture was heated at 60 °C
under stirring for 1 d. The solvent was then removed in vacuo
and the resulting oily residue was treated in a manner similar to
that described above to obtain the final complex 4.
Acknowledgments
This work has been supported by the Fundação para a Ciência e a
Tecnologia (FCT), Portugal. The author expresses gratitude to the FCT
and the Instituto Superior Técnico (IST) for his research contract
(Ciência 2007 program). J.L. gratefully acknowledges the Portuguese
NMR Network (IST-UTL Center) for access to the NMR facility.
Thanks are also due to Ms. Ana Dias for the analytical service.
:
yield, 67%. IR
[PdCl2{N=C(Ph)ON(Me)C(H)(C6H2Me3-2,4,6)}2] 4.
(cmÀ1): 1657 (C@N). 1H NMR (CDCl3), d: 2.32, 2.49 and 2.91 (three
s, 9H, CH3Ph), 3.17 (s, 3H, CH3N), 6.15 (s, 1H, N–CH–N), 6.90–7.97
(m, 7H, CHaromatic). 13C{1H} NMR (CDCl3), d: 20.1, 20.7 and 21.4
(CH3Ph), 47.5 (CH3N), 91.3 (N–CH–N), 128.5, 129.4, 131.7, 133.1,
133.8, 136.3, 137.9 and 140.3 (Caromatic), 163.6 (C(O)@N). ESI+-MS,
m/z: 703 [MÀCl]+. Anal. Calc. for C36H40N4O2Cl2Pd: C, 58.58; H,
5.46; N, 7.59. Found: C, 58.63; H, 5.69; N, 7.66%.
References
4.4. Liberation of the new heterocycles 1a–4a from complexes 1–4
1,2-Bis(diphenylphosphino)ethane (dppe) (2 eq) was added to a
solution of 1 (20.0 mg, 0.027 mmol), 2 (20.0 mg, 0.037 mmol), 3
(20.0 mg, 0.029 mmol) or
4 (20.0 mg, 0.028 mmol) in CHCl3
(5 mL) and the mixture was allowed to stand at 40 °C for 30 min,