Suijkerbuijk et al.
JOCArticle
yielding a green solution, which was stirred at room temperature
for 5 h. The resulting green suspension was cooled to 0 °C with
use of an ice/water bath and ice water (500 mL) was added. After
5 min of vigorous stirring the layers were separated and the
water layer was extracted once with CH2Cl2 (100 mL). The
combined organic layers were vigorously stirred with 6 M
K2CO3 solution in H2O (500 mL) until the whole mixture
attained a purple color and all solids had dissolved (due to the
low solubility of [6(Hþ)2]2þ in H2O and CH2Cl2 this can take
approximately 2 h). The layers were again separated and the
organic layer was dried (MgSO4), filtered, and concentrated to
40 mL. Further purification with column chromatography
(CH2Cl2/hexane 1:1, v/v), collection of the first purple band,
and evaporation of the solvent yielded crude 6 as a purple solid.
Yield 1050 mg (82%). The remaining chlorine contamination of
this product can be oxidized to the corresponding porphyrin:
the product was dissolved in CH2Cl2 (50 mL), DDQ (0.96 g,
4.23 mmol) was added, and the orange mixture was stirred for
2 h at room temperature. The mixture was filtered through a
short pad of silica gel (CH2Cl2/hexane 4:1, v/v), which gave the
title porphyrin as a purple, crystalline solid. 1H NMR (CDCl3) δ
8.91 (s, 8H, β-H), 8.28 (s, 8H, ArH), 4.93 (s, 16H, CH2Br), -2.90
(s, 2H, NH) ppm; 13C{1H} NMR (CDCl3) δ 141.8, 137.4, 136.9,
126.8, 118.1, 33.9 ppm; UV/vis [λmax (rel intensity), CH2Cl2] 422
(1.000), 517 (0.046), 551 (0.021), 591 (0.016), 648 (0.013) nm;
MALDI-TOF MS (DHB) m/z 1674.44 ([M þ H]þ), calcd for
C52H35Br12N4 1674.72. Anal. Calcd for C52H34Br12N4: C 37.32,
H 2.05, N 3.35. Found: C 37.39, H 1.98, N 3.31.
C 56.57, H 5.59, N 11.64, Ni 4.07. Found: C 56.50, H 5.68, N
11.51, 4.15. Crystals suitable for X-ray crystallographic analysis
were obtained by slow evaporation of a saturated solution of
[Ni(Br(NCN))4] in hexane at room temperature.
Standard procedure for 4-fold palladation: A solution of
[M1(Br(NCN))4] (M1 = 2H, Ni, Zn) in dry benzene (2 mM)
was treated with [Pd2dba3] CHCl3 (4.5-4.8 equiv) and the
3
solution was stirred for 16 h at room temperature under an N2
atmosphere, yielding a turbid mixture. HNEt2 (1 mL) was then
added to decompose the unreacted [Pd2dba3] CHCl3 and after
3
3 h of subsequent stirring at room temperature, all volatiles were
removed in vacuo. The dark residue was dissolved in CH2Cl2
(5 mM) and the mixture was filtered over Celite into a centrifuge
vessel and the Celite was washed with fresh CH2Cl2 until the
washings were colorless (the Celite retains Pd0). The volume of
the filtrate was reduced to ∼10 mL and hexane (50 mL) was
added, which resulted in (partial) precipitation of the product.
The suspension was then concentrated to ∼20 mL and the
now fully precipitated product was collected by centrifugation
(10 min at 2400 rpm).
5,10,15,20-Tetrakis(3,5-bis[(dimethylamino)methyl]-4-bromido-
palladio(II)phenyl)porphyrin ([2H(PdBr(NCN))4]). Purple solid.
Yield 90%. 1H NMR (CDCl3) δ 8.86 (s, 8H, β-H), 7.60 (s, 8H,
ArH), 4.27 (s, 16H, CH2N), 3.16 (s, 48H, N(CH3)2), -2.79 (s, 2H,
NH) ppm; 13C{1H} NMR (CDCl3) δ 157.4, 143.5, 138.8, 131.1,
126.5, 120.6, 75.1, 53.7 ppm; UV/vis [λmax (rel intensity), CH2Cl2]
426 (1.000), 522 (0.034), 558 (0.028), 594 (0.011), 653 (0.015) nm;
MALDI-TOF MS (DHB) m/z 1811.04 ([M þ H]þ), calcd for
C68H83Br4N12Pd4 1811.99. Anal. Calcd for C68H82Br4N12Pd4: C
45.05, H 4.56, N 9.27. Found: C 45.12, H 4.63, N 9.12.
5,10,15,20-Tetrakis(3,5-bis[(dimethylamino)methyl]-4-bromo-
phenyl)porphyrin ([2H(Br(NCN))4]). Porphyrin 6 (500 mg,
299 μmol) was dissolved in dry CH2Cl2 (100 mL) under a
nitrogen atmosphere. The solution was treated with Me2NH
(1.0 mL, excess), and the resulting clear solution was stirred for
90 min. Degassed H2O (60 mL) was added while stirring and
after 30 min the two layers were separated. The organic layer
was again washed with degassed H2O (100 mL), dried (MgSO4),
filtered, and concentrated to 10 mL. Hexane (60 mL) was added
and the purple solution was concentrated to 20 mL, whereupon
crystallization of the product started to set in. The mixture was
stored overnight at -30 °C, the supernatant was decanted, and
the resulting purple, glistening crystals were dried in vacuo and
[5,10,15,20-Tetrakis(3,5-bis[(dimethylamino)methyl]-4-bromido-
palladio(II)phenyl)porphyrinato]nickel(II)
([Ni(PdBr(NCN))4]).
Orange solid. Yield 87%. 1H NMR (CDCl3) δ 8.76 (s, 8H, β-H),
7.39 (s, 8H, ArH), 4.22 (s, 16H, CH2N), 3.16 (s, 48H, N(CH3)2)
ppm; UV/vis [λmax (rel intensity), CH2Cl2] 423 (1.000), 531 (0.088)
nm; MALDI-TOF MS (DHB) m/z 1789.73 ([M - Br]þ), calcd for
C68H80Br3N12NiPd4 1788.98. Anal. Calcd for C68H80Br4N12-
NiPd4: C 43.69, H 4.31, N 8.99, Ni 3.14. Found: C 43.84, H
4.38, N 8.78, Ni 3.30. The small quantity in which this com-
pound was available did not allow for a satisfactory 13C NMR
measurement.
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stored under a nitrogen atmosphere. Yield 412 mg (99%). H
[5,10,15,20-Tetrakis(3,5-bis[(dimethylamino)methyl]-4-bromido-
palladio(II)phenyl)porphyrinato]zinc(II) ([Zn(PdBr(NCN))4]).
NMR (CDCl3) δ 8.84 (s, 8H, β-H), 8.19 (s, 8H, ArH), 3.85 (s,
16H, CH2N), 2.43 (s, 48H, N(CH3)2), -2.81 (s, 2H, NH) ppm;
13C{1H} NMR (CDCl3) δ 140.7, 137.3, 135.5, 127.3, 119.4, 64.4,
46.0 ppm; UV/vis [λmax (rel intensity), CH2Cl2] 421 (1.000), 518
(0.038), 552 (0.020), 592 (0.011), 650 (0.010) nm; ESI-HRMS m/z
692.1800 ([M þ 2H]2þ), calcd for 1/2C68H84Br4N12 692.1838.
1
Purple/greenish solid. Yield 90%. H NMR (CDCl3) δ 8.97
(s, 8H, β-H), 7.61 (s, 8H, ArH), 4.27 (s, 16H, CH2N), 3.17
(s, 48H, N(CH3)2) ppm; 13C{1H} NMR (CDCl3) δ 156.5,
150.4, 143.2, 139.4, 132.0, 126.3, 121.4, 75.0, 53.7 ppm; UV/
vis [λmax (log ε), CH2Cl2] 429 (5.75), 554 (4.35), 596 (4.00) nm;
ESI-MS m/z 1797.20 ([M - Br]þ), calcd for C68H80Br3-
Anal. Calcd for C68H82Br4N12 C6H14: C 60.33, H 6.57, N 11.41.
3
Found: C 60.39, H 6.35, N 11.29.
N12Pd4Zn 1796.25. Anal. Calcd for C68H80Br4N12Pd4Zn: C
[5,10,15,20-Tetrakis(3,5-bis[(dimethylamino)methyl]-4-bromo-
phenyl)porphyrinato]nickel(II) ([Ni(Br(NCN))4]). To a purple
solution of [2H(Br(NCN))4] (33.0 mg, 23.8 μmol) in dry toluene
(10 mL) was added Ni(acac)2 (122 mg, 476 μmol) and the
resulting mixture was heated at reflux temperature for 3 h. After
the reaction had completed (monitored by UV/vis spectroscopy)
the volatiles were evaporated. The remaining red solid was
partitioned between CH2Cl2 (10 mL) and water (10 mL) and
the organic layer was isolated, dried (MgSO4), and filtered.
Hexane (20 mL) was added and the solution was concentrated
to 10 mL and stored at -30 °C for 4 days. The resulting red/
orange crystals were isolated by centrifugation. Yield 35 mg
(100%). 1H NMR(CDCl3) δ 8.72 (s, 8H, β-H), 7.99(s, 8H, ArH),
3.78 (s, 16H, CH2N), 2.38 (s, 48H, N(CH3)2) ppm; 13C{1H}
NMR (CDCl3) δ 142.9, 139.6, 137.5, 134.7, 132.1, 127.2, 118.4,
64.3, 45.9 ppm; UV/vis [λmax (rel intensity), CH2Cl2]: 417 (1.000),
528 (0.090) nm; LDI-TOF MS m/z 1438.91 ([M]þ), calcd for
C68H80Br4N12Ni 1438.27. Anal. Calcd for C68H80Br4N12Ni:
43.53, H 4.30, N 8.96, Zn 3.49. Found: C 43.65, H 4.42, N
9.06, Zn 3.43. Crystals suitable for X-ray crystallographic
analysis were obtained by slow evaporation of a solution of
[Zn(PdBr(NCN))4] (4 mg) in a mixture of CH2Cl2 and hexanes
(2:1, v/v, 1.5 mL) and a drop of pyridine.
Standard procedure for 4-fold platination: A solution of
[M1(Br(NCN))4] (M1 = 2H, Ni, Zn) in dry benzene (1 mM)
was treated with [Pt2dipdba3] (5 equiv) and the solution was
stirred for 16 h at reflux temperature under an N2 atmosphere,
yielding a turbid mixture. HNEt2 (1 mL) was then added to
decompose the unreacted [Pt2dipdba3] and after 3 h of sub-
sequent stirring at room temperature, all volatiles were removed
in vacuo. The black residue was stirred in CHCl3 (2 mM) with a
saturated solution of NH4Cl in H2O for 48 h and the layers were
separated. The organic layer was dried (MgSO4) and filtered
over Celite into a centrifuge vessel, and the Celite was washed
with fresh CH2Cl2 until the washings were colorless (the Celite
retains Pt0). The volume of the filtrate was reduced to ∼10 mL
J. Org. Chem. Vol. 75, No. 5, 2010 1547