238
Y. Murata et al. / Inorganica Chimica Acta 368 (2011) 237–241
Merck Silica gel 60F254. N-(2,6-Diisopropylphenyl)-3-hydroxysali-
cylaldimine (HLOH) [1a], N-(2,6-diisopropylphenyl)-3-methoxysali-
cylaldimine (HLOMe) [1a], cis- (1,5-cyclooctadiene)dichloropalla-
dium [PdCl2(cod)] [5], and cis- (1,5-cyclooctadiene)chloromethyl-
palladium [PdClMe(cod)] [6] were also prepared according to
literature procedures.
from dichloromethane/hexane afforded 1c as yellow crystals. Yield
4
0.79 g (86%). 1H NMR(CDCl3):
d 7.97 (d, JPH = 11.4 Hz, 1H,
ArN@CH), 7.7–7.6 (m, 6H, Ar(phosphine)), 7.5–7.3 (m, 9H, Ar(phos-
3
phine)), 7.2 (m, 3H, N–Ar), 6.73 (d, JHH = 7.44 Hz, 1H, Ar), 6.72 (d,
3
3JHH = 8.43 Hz, 1H, Ar), 6.36 (t, JHH = 7.93 Hz, 1H, Ar), 3.67 (s, 3H,
3
OCH3), 3.52 (sep, JHH = 6.94 Hz, 2H, CH(CH3)2), 1.29 (d,
3
3JHH = 6.94 Hz, 6H, CH(CH3)2), 1.11 (d, JHH = 6.94 Hz, 6H,
3
2.2. Synthesis of palladium complexes
CH(CH3)2), ꢁ0.45 (d, JPH = 2.53 Hz, 3H, Pd–CH3). 13C{1H} NMR
(CDCl3): d 165.6, 160.5, 152.9, 147.7, 141.1, 135.0, 134.9, 131.9,
2.2.1. Synthesis of PdCl(PPh3)(LOH) (1a)
131.2, 130.1, 130.0, 128.1, 128.0, 127.2, 126.0, 123.2, 118.7,
2
To a solution of N-(2,6-diisopropylphenyl)-3-hydroxysalicyl-
113.2, 111.7, 55.4, 27.9, 25.0, 22.5, 1.79 (d, Jcp = 11.2 Hz, Pd–
aldimine (HLOH, 0.40 g, 1.4 mmol) in THF (5.0 mL) was added a
CH3). 31P{1H} NMR (CDCl3): d 35.9. ESI-TOF mass (in the positive
mode, MeOH), m/z 716.2 ([1c+Na]+; I = 100% in the range of m/z
100–2000). Anal. Calc. for C39H42NO2PPdꢂ0.5H2O: C, 66.62; H,
6.16; N, 1.99. Found: C, 66.63; H, 6.18; N, 1.93%.
t
solution of BuOK (1.0 M in THF, 2.8 mL, 2.8 mmol) at room tem-
perature. After stirring for 30 min, all volatiles were removed in va-
cuo. The resulting solid residue was dissolved in dichloromethane
(5.0 mL) and then PdCl2(cod) (0.38 g, 1.33 mmol) and PPh3 (0.35 g,
1.3 mmol) were added to the solution. After stirring at room tem-
perature overnight, triethylammonium hydrogen chloride (0.20 g,
1.5 mmol) was added. The reaction mixture was stirred for addi-
tional 30 min and then filtered. Removal of all volatiles in vacuo
gave crude products as yellow solids. Recrystallization from dichlo-
romethane/hexane afforded 1a as yellow crystals. Yield 0.63 g
2.3. General procedure for polymerization
In a glove box under a nitrogen atmosphere, a 20 mL Schlenk
flask was charged with 1 (0.011 mmol), THF (0.30 mL) and dichlo-
t
romethane (3.6 mL). In the case of the addition of BuOK (1.0 M in
THF, 11 lL, 0.011 mmol), the base was added before charging
4
(68%). 1H NMR (CDCl3): d 7.86 (d, JPH = 13.4 Hz, 1H, ArN@CH),
dichloromethane. After methyl acrylate (1.0 mL, 12 mmol) was
introduced to the flask, the reaction mixture was stirred at the
ambient temperature for 24 h. The reaction mixture was poured
into 50 mL of methanol and precipitated polymers were collected
by filtration and dried under vacuum at 60 °C for 24 h. Average
molecular weights (Mn) and the polydisperse index (PDI) of poly(-
methyl acrylate) were determined using polystyrene standards.
7.8–7.7 (m, 6H, Ar(phosphine)), 7.6–7.5 (m, 3H, Ar(phosphine)),
7.5–7.4 (m, 6H, Ar(phosphine)), 7.2–7.1 (m, 3H, N–Ar), 6.80 (dd,
4
3
3JHH = 7.44 Hz, JHH = 1.49 Hz, 1H, Ar), 6.74 (dd, JHH = 7.93 Hz,
4JHH = 1.49 Hz, 1H, Ar), 6.50 (t, JHH = 7.93 Hz, 1H, Ar), 4.99 (s, 1H,
3
OH), 3.45 (sep, 3JHH = 6.94 Hz, 2H, CH(CH3)2), 1.40 (d,
3JHH = 6.94 Hz, 6H, CH(CH3)2), 1.15 (d, JHH = 6.94 Hz, 6H,
3
CH(CH3)2). 13C{1H} NMR (CDCl3): d 163.3, 152.5, 147.7, 146.9,
141.3, 135.0, 134.8, 131.2, 131.1, 129.0, 128.6, 128.4, 128.3,
126.7, 125.1, 122.9, 118.0, 116.0, 115.6, 28.7, 24.6, 22.9. 31P{1H}
NMR (CDCl3): d 30.5. ESI-TOF mass (in the negative mode, MeOH),
m/z 698.2 ([1aꢁH]ꢁ; I = 100% in the range of m/z 100–2000). Anal.
Calc. for C37H37ClNO2PPd: C, 63.44; H, 5.32; N, 2.00. Found: C,
63.37; H, 5.43; N, 1.91%.
2.4. X-ray crystallography
A summary of crystal structure refinements of 1a–1c was given
in Table 1. Data were collected on
diffractometer using graphite-monochromated Mo K
a
Rigaku/Saturn70 CCD
radiation
a
(k = 0.71070 Å) at 153 K, and processed using CrystalClear (Rigaku)
[7]. The structures were solved by a direct method and refined by
full-matrix least-square refinement on F2. The non-hydrogen
atoms were refined anisotropically. All hydrogen atoms were lo-
cated on the calculated positions and not refined. All calculations
were performed using the CrystalStructure software package [8].
2.2.2. Synthesis of PdMe(PPh3)(LOH) (1b)
The complex was synthesized with PdClMe(cod) (0.35 g,
1.3 mmol) instead of PdCl2(cod) by the method similar to that used
for 1a. Yield 0.82 g (91%). 1H NMR (CDCl3): d 7.99 (d, 4JPH = 11.4 Hz,
1H, ArN@CH), 7.7–7.5 (m, 6H, Ar(phosphine)), 7.5–7.3 (m, 9H,
3
Ar(phosphine)), 7.2 (m, 3H, N–Ar), 6.78 (dd, JHH = 7.44 Hz,
3
4
4JHH = 1.49 Hz, 1H, Ar), 6.64 (dd, JHH = 8.43 Hz, JHH = 1.49 Hz, 1H,
3. Results and discussion
3
3
Ar), 6.34 (dd, JHH = 7.44 Hz, JHH = 8.43 Hz, 1H, Ar), 5.76 (s, 1H,
OH), 3.46 (sep, 3JHH = 6.94 Hz, 2H, CH(CH3)2), 1.34 (d,
3.1. Synthesis and structure of palladium complexes
3JHH = 6.94 Hz, 6H, CH(CH3)2), 1.13 (d, JHH = 6.94 Hz, 6H,
3
CH(CH3)2), ꢁ0.35 (d, JPH = 2.98 Hz, 3H, Pd–CH3). 13C{1H} NMR
A ligand precursor (HLOH) was readily prepared by the reaction
of 2,3-dihydroxybenzaldehyde with 2,6-diisopropylaniline in
methanol [1a]. Palladium complexes with a salicylaldiminato li-
gand bearing a hydroxyl group (LOH) were synthesized as shown
in Scheme 1. First, the reaction of the ligand precursor with 2
equiv. of tBuOK afforded a dianionic intermediate in situ. Then,
addition of PdCl(X)(cod) (X = Cl or = Me) and PPh3 in CH2Cl2 fol-
3
(CDCl3): d 165.8, 156.9, 149.1, 147.3, 140.9, 134.7, 134.5, 131.0,
130.6, 130.9, 130.3, 128.4, 128.3, 126.2, 125.2, 123.3, 117.0,
2
113.8, 113.1, 28.0, 25.1, 22.5, 0.19 (d, Jcp = 11.2 Hz, Pd–CH3).
31P{1H} NMR (CDCl3): d 43.32. ESI-TOF mass (in the negative mode,
MeOH), m/z 678.2 ([1bꢁH]ꢁ; I = 100% in the range of m/z 100–
2000). Anal. Calc. for C38H40NO2PPd: C, 67.11; H, 5.93; N, 2.06.
Found: C, 67.05; H, 5.97; N, 2.09%.
lowed by the treatment of Et3NꢂHCl afforded PdX(PPh3)(LOH
)
(X = Cl (1a) or = Me (1b)) in good yields. For comparison, a related
palladium complex with a salicylaldiminato ligand bearing a meth-
oxyl group (LOMe), PdMe(PPh3)(LOMe) (1c), in place of the hydroxyl
group was also synthesized by the reaction of the corresponding
2.2.3. Synthesis of PdMe(PPh3)(LOMe) (1c)
To a solution of N-(2,6-diisopropylphenyl)-3-methoxysalicyl-
aldimine (HLOMe, 0.42 g, 1.4 mmol) in THF (5.0 mL) was added a
t
t
solution of BuOK (1.0 M in THF, 1.4 mL, 1.4 mmol) at room tem-
salicylaldimine with BuOK followed by adding PdClMe(cod) and
perature. After stirring for 30 min, all volatiles were removed in va-
cuo. The resulting solid residue was dissolved in dichloromethane
(5.0 mL), and then PdClMe(cod) (0.35 g, 1.3 mmol) and PPh3
(0.35 g, 1.3 mmol) were added to the solution. After stirring at
room temperature overnight, all volatiles were removed in vacuo.
The resulting crude products were purified by recrystallization
PPh3 (Scheme 2). All complexes were fully characterized by ele-
mental analysis and NMR measurements.
The molecular structures of 1a–1c have been successfully deter-
mined by X-ray crystallography. Suitable single crystals of 1a–1c
were obtained by crystallization from hot heptane solution. For
1a, there are two independent molecules in a unit cell (see Table