Inorganic Chemistry
Article
2% of acetone in CH2Cl2 as solvent. 99 mg (0.11 mmol, 13% yield
based on [Ir(Ph-Im)2(μ-Cl)]2) of the pure product was obtained as
1
3
yellow solid. H NMR (400 MHz, CDCl3): δ 8.33 (d, JHH = 1.8 Hz,
2H, Hk), 8.02 (d, 3JHH = 6.0 Hz, 2H, Hh), 7.46 (d, 4JHH = 2.1 Hz, 2H,
Ha), 7.33 (dd, 3JHH = 5.9 Hz, 4JHH = 2.0 Hz, 2H, Hi), 7.15 (dd, 3JHH
=
7.8 Hz, 4JHH = 1.1 Hz, 2H, Hc), 6.98 (td, 3JHH = 7.6 Hz, 4JHH = 1.4 Hz,
2H, Hb), 6.95 (d, 4JHH = 2.0 Hz, 2H, Hd), 6.75 (td, 3JHH = 7.4 Hz, 4JHH
3
4
= 1.3 Hz, 2H, He), 6.45 (dd, JHH = 7.4 Hz, JHH = 1.3 Hz, 2H, Hf),
3.03 (s, 6H, Hg) 1.45 (s, 18H, Hj) ppm. 13C NMR (100 MHz,
CDCl3): δ 170.3 (NCN), 162.9, 156.3, 150.6, 146.4, 137.4, 133.9,
126.2, 124.8, 122.3, 122.3, 120.9, 114.9, 111.6 (ArC), 35.6 (NCH3),
35.2 (C(CH3)3) 30.3 (C(CH3)3) ppm. 31P NMR (81 MHz, CDCl3): δ
−144.5 (sept, 1JPF = 713 Hz, PF6) ppm. HRMS (ESI-TOF) m/z (%):
calcd. 775.3102; found 775.3092 (100) [(M − PF6)+].
was degassed by six vacuum and backfill cycles. The mixture was
heated to reflux overnight. After it cooled to room temperature, the
solution was filtered through Celite to remove silver residues, and the
Celite was washed with CH2Cl2. The orange solution was
concentrated and dried in vacuo to obtain the crude product as
brown solid in quantitative yield (3.65 g, 4.0 mmol). The crude was
used without further purification.
trans-3 and cis-3. A solution of 111 mg (0.6 mmol, 1 equiv) of
4,4′-dimethyl-2,2′-bipyridine and 356 mg (0.4 mmol, 1.33 equiv) of
[Ir(Ph-Im)2(μ-Cl)]2 in 20 mL of CH2Cl2 was stirred overnight under
nitrogen at room temperature. Then the dark solution was
concentrated, and the crude product was purified by column
chromatography on silica gel using 2% of acetone in CH2Cl2 as
solvent mixture to remove impurities. Then KPF6 was added to the
solvent mixture to elute the product from the silica as the
corresponding PF6 salt of the complex. First pure trans-3 was eluted
as yellow solution (orange emitting under UV light, Rf = 0.63−0.73 in
CH2Cl2/acetone = 4/1), and then small quantities of cis-3 were eluted
as pale yellow solution (yellow emitting under UV light, Rf = 0.38−
0.48 in CH2Cl2/acetone = 4/1). Then cis-3 was dissolved in CH2Cl2
filled in a crystallization tube, and a layer of heptane was added on top.
Single crystals suitable for X-ray structure analysis were obtained from
this solution.
trans-1. A solution of 259 mg (1.2 mmol, 3 equiv) of 4,4′-
dimethoxy-2,2′-bipyridine and 356 mg (0.4 mmol, 1 equiv) of [Ir(Ph-
Im)2(μ-Cl)]2 in 20 mL of CH2Cl2 was stirred overnight under
nitrogen at room temperature. Then the dark solution was
concentrated, and the crude product was prepurified on a short plug
of silica gel using 2% of acetone in CH2Cl2 as solvent. After impurities
were removed, KPF6 in acetone was used as the eluent to elute the
product as the corresponding PF6 salt. The solvent was removed in
vacuo, and the solid was redissolved in CH2Cl2 and filtered through
cotton to remove excess of KPF6. The product was purified on silica
gel using CH2Cl2 and then 2% of acetone in CH2Cl2 as solvent. 89 mg
(0.10 mmol, 13% yield based on [Ir(Ph-Im)2(μ-Cl)]2) of the pure
product was obtained as yellow solid. 1H NMR (400 MHz, CDCl3): δ
7.98 (d, 3JHH = 2.6 Hz, 2H, Hh), 7.83 (d, 3JHH = 6.4 Hz, 2H, Ha), 7.47
(d, 4JHH = 2.1 Hz, 2H, Hk), 7.15 (dd, 3JHH = 7.8 Hz, 4JHH = 1.2 Hz, 2H,
3
4
4
Hc), 6.96 (td, JHH = 7.6 Hz, JHH = 1.4 Hz, 2H, Hb), 6.91 (d, JHH
=
trans-3. 101 mg (0.12 mmol, 20% yield based on 4,4′-dimethyl-
2.0 Hz, 2H, Hd), 6.81 (dd, 3JHH = 6.4 Hz, 4JHH = 2.6 Hz, 2H, Hi), 6.73
1
2,2′-bipyridine) of pure trans-3 were obtained as orange solid. H
3
4
3
NMR (400 MHz, CDCl3): δ 8.47 (s, 2H, Hk), 7.92 (d, 3JHH = 5.6 Hz,
2H, Hh), 7.47 (d, 3JHH = 2.0 Hz, 2H, Ha), 7.16 (dd, 3JHH = 7.8 Hz, 4JHH
(td, JHH = 7.4 Hz, JHH = 1.3 Hz, 2H, He), 6.44 (dd, JHH = 7.4 Hz,
4JHH = 1.3 Hz, 2H, Hf), 4.13 (s, 6H, Hj) 3.08 (s, 6H, Hg) ppm. 13C
NMR (100 MHz, CDCl3): δ 171.0 (NCN), 167.2, 158.2, 151.2, 146.5,
137.5, 134.0, 126.1, 122.2, 122.0, 115.4, 114.9, 111.6, 109.3 (ArC),
56.8 (OCH3), 35.4 (NCH3) ppm. 31P NMR (81 MHz, CDCl3): δ
−144.4 (sept, 1JPF = 713 Hz, PF6) ppm. HRMS (ESI-TOF) m/z (%):
calcd. 723.2061; found 723.2047 (100) [(M − PF6)+].
3
4
= 1.0 Hz, 2H, Hc), 7.10 (dd, JHH = 5.7 Hz, JHH = 0.8 Hz, 2H, Hi),
6.98 (td, 3JHH = 7.6 Hz, 4JHH = 1.3 Hz, 2H, Hb), 6.91 (d, 2JHH = 2.0 Hz,
3
4
2H, Hd), 6.75 (td, JHH = 7.4 Hz, JHH = 1.2 Hz, 2H, He), 6.45 (dd,
3JHH = 7.4 Hz, JHH = 1.1 Hz, 2H, Hf), 3.03 (s, 6H, Hg) 2.60 (s, 6H,
4
Hj) ppm. 13C NMR (100 MHz, CDCl3): δ 170.6 (NCN), 156.1, 151.0,
150.2, 146.4, 137.4, 133.9, 128.2, 126.2, 125.7, 122.3, 122.1, 114.9,
111.6 (ArC), 35.3 (NCH3), 21.3 (CH3) ppm. 31P NMR (81 MHz,
CDCl3): δ −144.3 (sept, 1JPF = 713 Hz, PF6) ppm. HRMS (ESI-TOF)
m/z (%): calcd. 691.2163; found 691.2166 (100) [(M − PF6)+].
cis-3. Pure cis-3 (30 mg, 0.04 mmol, 6% yield based on 4,4′-
1
dimethyl-2,2′-bipyridine) was obtained as yellow crystals. H NMR
(400 MHz, CDCl3): δ 8.13 (s, 1H, ArH), 8.08 (s, 1H, ArH), 8.04 (d,
3
3JHH = 5.6 Hz, 1H, ArH), 7.73 (d, JHH = 6.0 Hz, 1H, ArH), 7.48 (d,
3JHH = 2.0 Hz, 1H, ArH), 7.40 (d, 3JHH = 2.0 Hz, 1H, ArH), 7.21 (dd,
3JHH = 6.0 Hz, 4JHH = 0.8 Hz, 1H, ArH), 7.17 (td, 3JHH = 7.6 Hz, 4JHH
= 0.8 Hz, 2H, ArH), 7.09 (dd, 3JHH = 5.6 Hz, 4JHH = 1.0 Hz, 1H, ArH),
trans-2. A solution of 357 mg (1.33 mmol, 3.3 equiv) of 4,4′-di-tert-
butyl-2,2′-bipyridine and 356 mg (0.4 mmol, 1 equiv) of [Ir(Ph-
Im)2(μ-Cl)]2 in 20 mL of CH2Cl2 was stirred overnight under
nitrogen at room temperature. Then the dark solution was
concentrated, and the crude product was prepurified on a short plug
of silica gel using 2% of acetone in CH2Cl2 as solvent. After removing
impurities, KPF6 in acetone was used as the eluent to elute the product
as the corresponding PF6 salt. The solvent was removed in vacuo, and
the solid was redissolved in CH2Cl2 and filtered through cotton to
remove excess of KPF6. The product was purified on silica gel using
2
7.04−6.97 (m, 2H, ArH), 6.95 (d, JHH = 2.0 Hz, 1H, ArH), 6.84 (d,
3
4
3JHH = 2.4 Hz, 1H, ArH), 6.77 (td, JHH = 7.6 Hz, JHH = 1.0 Hz, 1H,
ArH), 6.69 (td, 3JHH = 7.6 Hz, 4JHH = 1.0 Hz, 1H, ArH), 6.52 (dd, 3JHH
= 7.6 Hz, 4JHH = 1.2 Hz, 1H, ArH), 6.10 (dd, 3JHH = 7.2 Hz, 4JHH = 0.8
Hz, 1H, ArH), 3.12 (s, 3H, NCH3), 3.09 (s, 3H, NCH3), 2.59 (s, 3H,
CH3), 2.49 (s, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 156.6,
156.4, 154.6, 152.1, 150.9, 150.2, 138.0, 132.0, 129.5, 128.3 126.0,
125.7, 124.4, 124.6, 122.9, 122.9, 122.8, 122.7, 115.0, 114.9, 111.4,
111.1 (ArC), 36.2 (NCH3), 35.8 (NCH3), 21.6 (CH3), 21.5 (CH3)
3033
Inorg. Chem. 2015, 54, 3031−3042