Inorganic Chemistry
Article
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18H, SiMe3). H NMR (599.7 MHz, THF-d8): δ 8.08 (d, J = 7.2 Hz,
to give a brown solid. The residue was redissolved in dichloromethane
and subjected to chromatography on alumina gel, with solvent
gradients being varied from CH2Cl2 to THF. Similar fractions were
combined and evaporated under high vacuum. The resulting solid was
dissolved in a minimum amount of acetone (HPLC grade) and stored
in a freezer (−30 °C) for 4 days. The product was obtained as an off-
4H, Ph-H2,6), 7.67 (d, J = 7.2 Hz, 4H, Ph-H3,5), 7.56 (d, J = 7.8 Hz,
6H, pyridyl-H3), 7.29 (pst, J = 7.5 Hz, 6H, pyridyl-H4), 7.14 (d, J =
5.4 Hz, 6H, pyridyl-H6), 6.49 (pst, J = 6.3 Hz, 6H, pyridyl-H5), 0.39
(s, 18H, SiMe3). 13C NMR (150.8 MHz, THF-d8): δ 188.4 (q, JC−B
=
50 Hz, pyridyl-C2), 158.9 (pyridyl-C6), 154.3 (q, JC−B = 54 Hz, Ph-
C1), 136.9 (Ph-C2,6), 135.4 (Ph-C4), 132.8 (Ph-C3,5 or pyridyl-C4)
132.4 (Ph-C3,5 or pyridyl-C4), 126.3 (pyridyl-C3), 120.3 (pyridyl-
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white solid (17.9 g, 35%). H NMR (500.0 MHz, CDCl3): δ 16.5 (br
s, 1H, pyridyl-NH), 8.48 (d, 3J = 5.0 Hz, 3H, pyridyl-H6), 7.58 (pst, 3J
= 7.5 Hz, 3H, pyridyl-H4), 7.45 (d, 3J = 8.0 Hz, 2H, Ph-H3,5), 7.36 (d,
C5), −0.8 (SiMe3). 11B NMR (192.4 MHz, THF-d8): δ −7.4 (w1/2
=
3
3J = 7.5 Hz, 3H, pyridyl-H3), 7.11 (pst, J = 6.3 Hz, 3H, pyridyl-H5),
20 Hz). High-resolution MALDI-MS (anthracene, positive mode).
C
1H5011B256Fe14N628Si2: m/z 844.3183. Found: m/z
48
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6.83 (br d, 3J = 6.0 Hz, 2H, Ph-H2,6). 13C NMR (125.7 MHz,
CDCl3): δ 183.4 (q, JC−B = 54 Hz, pyridyl-C2), 156.1 (not resolved,
Ph-C1), 143.7 (pyridyl-C6), 136.9 (pyridyl-C4), 136.3 (Ph-C2,6)
136.2 (Ph-C3,5), 131.6 (pyridyl-C3), 119.9 (pyridyl-C5), 90.6 (Ph-
C4). 11B NMR (160.4 MHz, CDCl3): δ −10.8 (w1/2 = 20 Hz). High-
Calcd for
844.3178 (M+). Single crystals for X-ray diffraction analysis were
obtained by slow evaporation of a solution in a mixture of decane and
toluene under a N2 atmosphere.
Synthesis of Bis[[4-(trimethylsilyl)phenyl]tris(2-pyridyl)-
borate]ruthenium(II) [Ru(Tpyb-Si)2]. Under the protection of
nitrogen, to a refluxing solution of RuCl2(DMSO)4 (0.61 g, 1.26
mmol) in anhydrous ethanol (40 mL) was added a hot solution of
Tpyb-Si (1.00 g, 2.53 mmol) and triethylamine (1.06 mL, 7.59 mmol)
in anhydrous ethanol (50 mL), and the reaction mixture was kept
stirring at reflux for 72 h. A light-brown precipitate formed, which was
collected by filtration of the hot suspension and washed with acetone
(2 × 5 mL) and ether (2 × 3 mL). Solvent evaporation gave the
product as a light-yellow-green solid, which was dried under high
vacuum at room temperature for 5 h. Yield: 0.45 g (40%). For further
purification, the product was redissolved in toluene, decane was added
to the solution, and toluene was allowed to evaporate to give bright-
yellow crystals. 1H NMR (500.0 MHz, C6D6): δ 8.56 (br d, J = 7.0 Hz,
4H, Ph-H2,6), 8.02 (d, J = 7.5 Hz, 6H, pyridyl-H3), 7.97 (d, J = 7.5
Hz, 4H, Ph-H3,5), 7.14 (d, J = 6.0 Hz, 6H, pyridyl-H6), 6.94 (pst, J =
7.5 Hz, 6H, pyridyl-H4), 6.00 (pst, J = 6.5 Hz, 6H, pyridyl-H5), 0.47
(s, 18H, SiMe3). 1H NMR (599.7 MHz, THF-d8): δ 8.08 (br d, J = 6.6
Hz, 4H, Ph-H2,6), 7.67 (d, J = 7.2 Hz, 4H, Ph-H3,5), 7.62 (d, J = 7.2
Hz, 6H, pyridyl-H3), 7.32 (pst, J = 6.6 Hz, 6H, pyridyl-H4), 7.09 (d, J
= 5.4 Hz, 6H, pyridyl-H6), 6.56 (pst, J = 5.7 Hz, 6H, pyridyl-H5), 0.39
(s, 18H, SiMe3). 13C NMR (150.8 MHz, THF-d8): δ 184.3 (nr,
pyridyl-C2), 155.6 (pyridyl-C6), 137.0 (Ph-C2,6), 135.4 (Ph-C4),
132.8 (Ph-C3,5 or pyridyl-C4), 132.3 (Ph-C3,5 or pyridyl-C4), 128.4
(pyridyl-C3), 121.3 (pyridyl-C5), −0.8 (SiMe3), Ph-C1 not observed.
11B NMR (192.4 MHz, THF-d8): δ −6.7 (w1/2 = 20 Hz). High-
resolution MALDI-MS (anthracene, negative mode). Calcd for
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C
1H1611B114N3127I1: m/z 448.0480. Found: m/z 448.0467 ([M −
21
H]−). Elem anal. Calcd for C21H17B1N3I1: C, 56.16; H, 3.82; N, 9.36.
Found: C, 55.90; H, 3.37; N, 9.11. Single crystals for X-ray diffraction
analysis were obtained by slow evaporation of a solution in a mixture
of CH2Cl2 and hexanes.
Synthesis of Bis[(4-iodophenyl)tris(2-pyridyl)borate]iron(II)
[Fe(Tpyb-I)2]. The product was prepared in analogy to the procedure
for Fe(Tpyb-Si)2 from FeCl2 (61 mg, 0.48 mmol), triethylamine (0.15
mL, 1.08 mmol), and Tpyb-I (0.47 g, 1.05 mmol) in anhydrous THF.
The volatile components were removed on a rotary evaporator to give
a red solid, which was purified by column chromatography on silica gel
with hexanes and then a 1:9 mixture of THF and hexanes as the
eluent. Solvent evaporation gave the product as a red solid, which was
dried under high vacuum at room temperature for 3 h. The product
was recrystallized by adding hexanes to a solution in THF (obtained
upon heating in THF) under a N2 atmosphere. Yield: 0.31 g (67%).
1H NMR (599.7 MHz, C6D6): δ 8.02 (br d, J = 7.8 Hz, 4H, Ph-H2,6),
7.98 (d, J = 7.8 Hz, 4H, Ph-H3,5), 7.68 (d, J = 7.2 Hz, 6H, pyridyl-
H3), 7.19 (d, J = 5.4 Hz, 6H, pyridyl-H6), 6.88 (pst, J = 7.2 Hz, 6H,
1
pyridyl-H4), 5.95 (pst, J = 6.3 Hz, 6H, pyridyl-H5). H NMR (599.7
MHz, THF-d8): δ 7.86 (br, 4H, Ph-H2,6), 7.83 (br, 4H, Ph-H3,5),
7.48 (d, J = 7.2 Hz, 6H, pyridyl-H3), 7.33 (pst, J = 7.2 Hz, 6H, pyridyl-
H4), 7.12 (d, J = 4.8 Hz, 6H, pyridyl-H6), 6.50 (pst, J = 6.0 Hz, 6H,
pyridyl-H5). 13C NMR (150.8 MHz, THF-d8): δ 187.7 (q, JC−B = 50
Hz, pyridyl-C2), 159.0 (pyridyl-C6), 152.9 (not resolved, Ph-C1),
139.7 (Ph-C3,5), 137.0 (Ph-C2,6), 132.7 (pyridyl-C4) 126.1 (pyridyl-
C3), 120.5 (pyridyl-C5), 91.1 (Ph-C4). 11B NMR (192.4 MHz,
C6D6): δ −7.4 (w1/2 = 20 Hz). 11B NMR (192.4 MHz, THF-d8): δ
resolution MALDI-MS (anthracene, positive mode). Calcd for
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C
1H5011B214N628Si2102Ru: m/z 890.2885. Found: m/z 890.2879
48
(M+). Elem anal. Calcd for C48H50B2N6Si2Ru·C7H8: C, 67.27; H, 5.95;
N, 8.56. Found: C, 67.03; H, 5.74; N, 8.42. Single crystals for X-ray
diffraction analysis were obtained by slow evaporation of a solution in
a mixture of decane and toluene.
−7.6 (w1/2 = 20 Hz). High-resolution MALDI-MS (anthracene,
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positive mode). Calcd for
C
1H3211B214N656Fe127I2: m/z 952.0322.
42
Found: m/z 952.0320 (M+). Elem anal. Calcd for C42H32B2N6FeI2: C,
52.99; H, 3.39; N, 8.83. Found: C, 52.97; H, 3.42; N, 8.74. Single
crystals for X-ray diffraction analysis were obtained by slow
evaporation of a solution in a mixture of decane and toluene.
Synthesis of 4-Iodophenyl Dibromoborane. In a glovebox, a
solution of 1-iodo-4-(trimethylsilyl)benzene (4.00 g, 14.5 mmol) in 20
mL of anhydrous CH2Cl2 was slowly added to a solution of BBr3 (1.36
mL, 14.3 mmol) in 8 mL of anhydrous CH2Cl2 and then kept stirring
overnight. The volatile materials were evaporated under high vacuum
for 5 h to give a light-brown liquid. The product was used without
further purification. Yield: 4.50 g (84%). 1H NMR (500.0 MHz,
CDCl3): δ 7.90 (d, 2H, J = 8.0, Ph-H), 7.86 (d, 2H, J = 8.0 Hz, Ph-H).
11B NMR (160.4 MHz, CDCl3): δ 57.2 (w1/2 = 250 Hz).
Synthesis of (4-Iodophenyl)tris(2-pyridyl)borate Free Acid
(Ligand 2, Tpyb-I). Under the protection of nitrogen, a solution of 4-
iodophenyl dibromoborane (42.8 g, 114 mmol) in 150 mL of
anhydrous CH2Cl2 was added dropwise to a solution of pyridyl
Grignard (139 g, 263 mmol) in anhydrous CH2Cl2 (600 mL), and the
reaction mixture was kept stirring overnight. The mixture was poured
into an aqueous NaHCO3 solution (500 mL) to give a light-brown
slurry, which was stirred for 3 h. The organic and aqueous layers were
separated, and the aqueous layer was extracted three times with 150
mL of CH2Cl2. The product was extracted into the aqueous phase by
treatment with an aqueous HCl solution (pH 2) and washed several
times with dichloromethane. A Na2CO3 solution was added until the
pH reached 8−9, followed by the addition of CH2Cl2 to reextract the
product into the organic layer. The combined organic layers were
dried over Na2SO4, and the solvent was removed by rotary evaporation
Synthesis of Bis[[4-(trimethylsilyl)ethynylphenyl]tris(2-
pyridyl)borate]iron(II) [Fe(Tpyb-CCR)2]. A Schlenk flask was
charged with Fe(Tpyb-I)2 (0.30 g, 0.32 mmol), (trimethylsilyl)-
acetylene (60 mg, 0.61 mmol), and piperidine [6.67 mL, 1:3 (v/v)] in
anhydrous THF (20 mL). The reaction vessel and reactants were then
subjected to three freeze−pump−thaw cycles. The reaction mixture
was allowed to warm to room temperature, the vessel was backfilled
with N2, and then CuI (3.0 mg, 5 mol %) and Pd(PPh3)2Cl2 (10 mg, 5
mol %) were added under a N2 atmosphere. The flask was then placed
in a 60 °C oil bath for 2 days. The mixture was poured into an aqueous
NaHCO3 solution (50 mL) and stirred for 10 min. The organic and
aqueous layers were separated, and the aqueous layer was extracted
three times with 50 mL of CH2Cl2. The combined organic layers were
dried over MgSO4, and the solvent was removed by rotary evaporation
to give a red solid. The product was purified by chromatography on
alumina gel, with solvent gradients being varied from hexanes to
CH2Cl2. The product was dried under high vacuum at 50 °C for 5 h to
give a red solid. Yield: 60 mg (22%). 1H NMR (599.7 MHz, THF-d8):
δ 8.06 (br d, J = 7.2 Hz, 4H, Ph-H2,6), 7.58 (d, J = 7.2 Hz, 4H, Ph-
H3,5), 7.47 (d, J = 7.8 Hz, 6H, pyridyl-H3), 7.32 (pst, J = 7.2 Hz, 6H,
I
Inorg. Chem. XXXX, XXX, XXX−XXX