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J.-H. Choi et al. / Polyhedron 117 (2016) 283–292
Found: C, 42.51; H, 4.38; N, 5.23. IR (KBr/cmꢀ1): 1647, 1566 (CO).
1H NMR (CDCl3): 0.92 (d, 36H, J = 11.1 Hz, P(CH3)3), 2.54 (d, 4H,
J = 15.6 Hz, CH2), 4.05 (d, 4H, J = 15.6 Hz, CH2), 4.74 (d, 4H,
J = 17.1 Hz, CH2), 6.98 (d, 4H, J = 6.9 Hz CH2), 7.13–7.41 (m, 40H,
Ar). 31P{1H} NMR (CDCl3): ꢀ14.8 (s, JPt–P = 3990 Hz). TOF-MS(ES
+): calcd for [M+H]+: 2149.4658; found: 2149.0176. 13C{1H} NMR
spectrum could not be measured because of its poor solubility.
CH2), 7.11–7.40 (m, 10H, Ar). 13C{1H} NMR (CDCl3): d 16.0 (d,
J = 40.1 Hz, P(CH3)3), 29.7 (s, C(CH3) 3), 44.4 (s, CH2), 54.4 (s, CH2)
68.1 (s, C(CH3) 3), 125.9, 126.2, 126.4, 128.1, 128.1, 128.2, 140.2,
143.3 (Ar), 155.1 (NC), 167.1 (CO), 180.7 (CO). 31P{1H} NMR (CDCl3):
d ꢀ23.8(s, JPt–P = 3212 Hz).
Complex [Pd(PMe3)(CN–tbutyl){C(O)N(Ar)–C(O)N(Ar)}], (Ar = p-
OMeC6H4), 10 was analogously prepared. Complex 10 (96%): Anal.
Calc. for C24H36N3O6P1Pd (599.95): C, 48.05; H, 6.05; N, 7.00.
Found: C, 48.47; H, 5.59; N, 6.79. IR (KBr/cm–1): 1659, 1604 (CO),
2198 (NC). 1H NMR (CDCl3): d 1.21 (s, 9H, C(CH3)3), 1.53 (d, 9H,
J = 10.2 Hz, P(CH3)3), 3.75 (s, 3H, OCH3), 3.76 (s, 3H, OCH3),
6.78–6.86 (m, 4H, Ar), 7.13–7.24 (m, 4H, Ar). 13C{1H} NMR (CDCl3):
d 15.9 (d, J = 30.8 Hz, P(CH3)3), 29.7 (s, C(CH3) 3), 55.6 (s, OCH3),
55.9 (s, OCH3), 68.2 (s, C(CH3) 3), 113.5, 113.8, 128.3, 129.8,
132.0, 145.5, 155.7, 158.1 (Ar), 163.8 (NC), 183.0 (CO), 207.3
(CO). 31P{1H} NMR (CDCl3): d ꢀ7.6.
4.4. Reactions of palladacyclic complexes with elemental sulfur
Dichloromethane (5 cm3) was added to a Schlenk flask contain-
ing cis-[Pd{–N(Ar)C(O)N(Ar)C(O)–}(PMe3)2] (Ar = p-MeOC6H4)
(284 mg, 0.51 mmol) and elemental sulfur (36 mg, 1.12 mmol).
The initial orange solution slowly turned to a homogeneous dark
red solution. After stirring for 3 h at room temperature, the solvent
was removed under vacuum. The resulting residue was washed
with n-hexane (3 times) to yield crude solids. Recrystallization
from CH2Cl2/diethyl ether gave white crystals of 6 (74 mg, 42%).
Anal. Calc. for C76H92N8O16P4Pd4 (1923.16): C, 47.46; H, 4.82; N,
5.83. Found: C, 47.29; H, 4.89; N, 5.82. IR (KBr/cmꢀ1): 1654, 1563
(CO). 1H NMR (CDCl3): d 1.02 (d, 36H, J = 10.2 Hz, P(CH3)3), 3.81
(s, 12H, OMe), 3.85 (s, 12H, OMe), 6.39 (br, 4H, Ar), 6.73–6.93 (m,
24H, Ar), 7.26 (br, 4H, Ar). 13C {1H} NMR (CDCl3): d 14.3(d,
J = 29.0 Hz, P(CH3)3), 55.7 (s, OMe), 56.0 (s, OMe), 113.5, 121.3,
130.5, 131.9, 133.6, 137.5, 156.7, 158.3 (Ar), 161.7 (CO), 173.8
(CO). 31P{1H} NMR (CDCl3): d ꢀ5.5. TOF-MS (ES+): calcd for [M
+H]+: 1921.1799; found: 1921.1095.
Analogous reactions of cis-[Pd{–N(Ar)C(O)N(Ar)C(O)–}(PR3)2]
(Ar = p-tolyl or p-chlorophenyl) by elemental sulfur gave corre-
sponding cyclic tetramers 7 and 8, respectively. Complex 7 (28%):
Anal. Calc. for C76H92N8O8P4Pd4 (1795.17): C, 50.85; H, 5.17; N,
6.24. Found: C, 50.82; H, 5.26; N, 6.28. IR (KBr/cmꢀ1): 1655, 1560
(CO). 1H NMR (CDCl3): d 1.01 (d, 36H, J = 5.1 Hz, P(CH3)3), 2.40 (s,
12H, CH3), 2.42 (s, 12H, CH3), 6.55 (d, 4H, J = 3.6 Hz, Ar), 6.75 (d,
4H, J = 3.6 Hz, Ar), 6.79 (d, 8H, J = 4.2 Hz, Ar), 7.17 (d, 4H,
J = 3.9 Hz, Ar), 7.21 (d, 8H, J = 3.9 Hz, Ar), 7.35 (d, 4H, J = 3.6 Hz,
Ar). 13C{1H} NMR (CDCl3): d 14.3 (d, J = 14.6 Hz, P(CH3)3), 21.6, (s,
CH3), 21.9, (s, CH3), 127.1, 129.0, 129.4, 129.8, 132.8, 136.3,
136.6, 142.2 (Ar), 162.0 (CO), 173.6 (CO). 31P{1H} NMR (CDCl3): d
ꢀ4.7. TOF-MS(ES+): calcd for [M+H]+: 1793.2206; found:
1793.1477.
4.6. Reactions of bis(phosphine) metallacycles with with tert-butyl
isocyanide
tert-Butyl isocyanide (21 mg, 0.25 mmol) was added to a CH2Cl2
(2 cm3) solution containing
1 (139 mg, 0.23 mmol) at room
temperature. After stirring the reaction mixture for 2 h at room
temperature, the solvent was completely removed under vacuum,
and then the resulting residue washed with hexane (2 cm3 ꢂ 3) to
obtain the crude solids. Recrystallization from CH2Cl2/diethyl ether
afforded white crystals of 9 (142 mg, 99%). Complex 10 (93%) was
similarly obtained. Spectroscopic data of the above products
coincided with those in the cleavage reactions.
4.7. Reactions of Pt(olefin)(PR3)2 or platinacycles with aryl isocyanate
Styrene (65 mg, 0.62 mmol) and tetrahydrofuran (toluene,
3 cm3) were added sequentially to a Schlenk flask containing
cis-[PtEt2(PMe2Ph)2] (164 mg, 0.31 mmol) at room temperature.
The mixture was heated at 80 °C for 18 h to give a pale yellow solu-
tion. p-Chlorophenyl isocyanate (95 mg, 0.62 mmol) was added to
the mixture at room temperature. After stirring for 2 h at room
temperature, the volatiles were completely removed under
vacuum, and then the remaining residue was extracted with excess
diethyl ether. The collected extracts were evaporated under
vacuum to give crude organic products. The organic products were
purified by chromatography over silica gel, eluting with ethyl acet-
ate/hexane (1:3). The collected organic products recrystallized
from excess diethyl ether at room temperature to afford white
solids of p-chlorophenyl isocyanurate, (Ar–NCO)3 (Ar = p-ClC6H4)
(87 mg, 91%). The remaining solid, 11, was characterized by IR
and NMR spectroscopy. Complex 11: IR (KBr/cm–1): 1719, 1690
(CO). 1H NMR (CDCl3): d 0.83 (d, 6H, J = 8.4 Hz, P(CH3)2Ph), 1.76
(d, 6H, J = 11.1 Hz, P(CH3)2Ph), 7.02–7.48 (m, 18H, Ar). 13C{1H}
Complex 8 (34%): Anal. Calc. for C88H76N8O8Cl8P4Pd4 (2206.79):
C, 47.89; H, 3.47; N, 5.08. Found: C, 47.74; H, 3.42; N, 5.09. IR
(KBr/cmꢀ1): 1655, 1560 (CO). 1H NMR (CDCl3): d 1.29 (d, 12H,
J = 10.2 Hz, P(CH3)2Ph), 1.42 (d, 12H, J = 10.2 Hz, P(CH3)2Ph),
6.57–7.44(m, 52H, Ar). 13C{1H} NMR (CDCl3):
d 11.9 (d,
J = 32.9 Hz, P(CH3)2Ph), 14.2 (d, J = 27.6 Hz, P(CH3)2Ph), 128.5,
128.6, 128.7, 130.2, 130.9, 130.9, 131.0, 133.1, 135.0, 135.0,
137.0, 142.3 (Ar), 161.4 (CO), 170.6 (d, J = 10.4 Hz, CO). 31P{1H}
NMR (CDCl3):
d
2.3(s). TOF-MS(ES+): calcd for [M+Na]+:
2222.8281; found: 2223.0322.
NMR (CDCl3):
d
13.5 (d, J = 26.6 Hz, P(CH3)2Ph), 15.3
(d, J = 18.5 Hz, P(CH3)2Ph), 128.0, 128.5, 128.6, 128.7, 128.8,
129.1, 129.3, 129.4, 130.2, 130.3, 130.4, 130.5, 130.7, 130.8,
131.9, 148.3 (Ar), 166.5 (CO), 183.8 (CO). 31P{1H} NMR (CDCl3):
d ꢀ14.3 (d, J = 13.0 Hz, JPt–P = 1794 Hz), ꢀ11.7 (d, J = 19.4 Hz,
JPt–P = 3504 Hz). We could not obtain pure analytical data due to
the presence of isocyanurate.
Analogous reaction with p-tolyl isocyanate was performed.
p-Tolyl isocyanurate (Ar–NCO)3 (Ar = p-MeC6H4) was obtained in
90% yield.
p-Chlorophenyl isocyanate (0.074 g, 0.48 mmol) was added to a
THF (3 cm3) solution containing 2 (0.055 g, 0.08 mmol) at room
temperature. After stirring the reaction mixture for 18 h at 55 °C
temperature, the solvent was completely removed under vacuum,
and then the resulting residue extracted with excess diethyl ether
to afford white solids. The collected extracts were evaporated
4.5. Reactions of cyclic tetramers (5 and 6) with tert-butyl isocyanide
tert-Butyl isocyanide (9 mg, 0.11 mmol) was added to a CH2Cl2
(2 cm3) solution containing 5 (59 mg, 0.027 mmol) at room temper-
ature. After stirring the reaction mixture for 2 h at room tempera-
ture, the solvent was completely removed under vacuum, and
then the resulting residue washed with hexane (2 cm3 ꢂ 3) to
obtain the crude solids. Recrystallization from THF/(diethyl ether)
afforded white crystals of [Pt(PMe3)(CN–tbutyl){C(O)N(R)–C(O)N
(R)}], (R = CH2C6H5) (9, 67 mg, 98%). Anal. Calc. for C24H32N3O2P1Pt
(620.58): C, 46.45; H, 5.20; N, 6.77. Found: C, 46.56; H, 5.34; N,
6.60. IR (KBr/cmꢀ1): 1646, 1595 (CO), 2194 (NC). 1H NMR (CDCl3):
d 1.24 (s, 9H, C(CH3)3), 1.67 (d, 9H, J = 10.8 Hz, JPt–H = 35 Hz P
(CH3)3), 4.65 (s, 2H, CH2), 5.17 (d, J = 5.4 Hz, JPt–H = 37 Hz, 2H,