Organometallics
Article
Melting points were measured in open capillaries on a JSGW melting
point apparatus and are uncorrected.
Materials. Solvents were dried by conventional methods, distilled
(d, J = 4.6 Hz, 1H, NP), 8.47 (d, J = 1.7 Hz, 1H, Im), 8.18 (dd, J =
7.85 Hz, J = 1.15 Hz, 1H, NP), 7.95 (s, 1H, NP), 7.94 (d, J = 8 Hz,
1H, Ph), 7.89 (d, J = 7.75 Hz, 1H, Ph), 7.71 (d, J = 1.8 Hz, 1H, Im),
7.51 (dd, J = 8.15 Hz, J = 4.25 Hz, 1H, NP), 7.06 (t, J = 7.17 Hz, 1H,
Ph), 7.06 (t, J = 5.9 Hz, 1H, Ph), 1.42 (s, 15H,CpMe5). 13C NMR (125
MHz, CDCl3, 292 K): 154.3 (Ir−Ccyclometalated), 152.1 (NCNNP), 147.7
(NCCNP), 143.4 (NCCNP), 137.1 (NCCNP), 134.1 (CCCNP), 132.1
(CCCNP), 130.7 (CCCNP), 128.7 (NCCPh), 124.3 (CCCPh), 122.9
(CCCPh), 122.1 (CCCPh), 118.8(NCCIm), 113.3 (NCCIm), 88.0
(CpMe5), 8.8 (CpMe5). ESI-MS: m/z 572 [M − Cl]+, where M =
Ir(L2H)Cp*Cl. Anal. Calcd for C26H25N3ClIr: C, 51.38; H, 4.15; N,
6.91. Found: C, 51.70; H, 4.25; N, 6.72.
Synthesis of 3. A mixture of [Cp*IrCl2]2 (40 mg, 0.05 mmol),
NaOAc (25 mg, 0.31 mmol), and L2H2 (14 mg, 0.05 mmol) was
reacted following a procedure similar to the synthesis of 1 for a period
of 12 h. Compound 3 was isolated as a red crystalline solid. Crystals
suitable for X-ray study were grown by slow vapor diffusion of diethyl
ether into a saturated dichloromethane solution of the compound.
Yield: 45 mg (91%). Mp: >250 °C. 1H NMR (500 MHz, CDCl3, 292
K): δ 8.72 (d, J = 5.5 Hz, 1H, NP), 8.34 (dd, J = 5.5 Hz, J = 1.25 Hz,
1H, NP), 8.02 (dd, J = 8.07 Hz, J = 1.25 Hz, 1H, Ph), 8.00 (dd, J =
7.35 Hz, J = 1.25 Hz, 1H, Ph), 7.70 (s, 1H, Im), 7.40 (dd, J = 8.1 Hz, J
= 4.6 Hz, 1H, NP), 7.40 (s, 1H, NP), 7.04 − 6.97 (m, 2H, Ph), 1.81 (s,
15H, CpMe5), 1.40(s, 15H, CpMe5). 13C NMR (125 MHz, CDCl3,
292 K): 155.9 (Ir−-Ccyclometalated), 154.2 (Ir−Ccyclometalated),146.1
(NCNNP), 144.1 (NCCNP), 137.2 (NCCNP), 134.4 (NCCNP), 132.4
(CCCNP), 129.7 (CCCNP), 128.8 (CCCNP), 122.2 (CCCNP), 126.2
(CCCPh), 124.4 (CCCPh), 122.8 (CCCPh), 121.2(CCCPh), 119.9-
(CCCPh), 114.5(NCCIm), 88.9 (CpMe5), 87.9 (CpMe5) 9.6 (CpMe5),
8.9 (CpMe5). ESI-MS: m/z 934 [M − Cl]+, where M = Ir2(L2)-
Cp2*Cl2. Anal. Calcd for C36H39N3Cl2Ir2: C, 44.57; H, 4.05; N, 4.33.
Found: C, 44.37; H, 4.07; N, 4.27.
under nitrogen, and deoxygenated prior to use. IrCl3·xH2O,
Pd(CH3COO)2, and PdCl2 were purchased from Arora Matthey
22
Kolkata (India). The compounds [IrCp*(μ-Cl)Cl]2
and
[Pd2(dba)3·CHCl3]23 were prepared according to the literature
procedures. 2,4-Dimethyl-7-amino[1,8]naphthyridine, 3-phenyl-2-
amino[1,8]naphthyridine, and 6,8-dimethyl-2′-phenylimidazo[1,2-a]-
[1,8]naphthyridine (L1H) were synthesized as reported earlier.9
Synthesis of L2H2. 3-Phenyl-2-amino[1,8]naphthyridine (165 mg,
0.74 mmol) was refluxed in ethanol/water (10/1) with a small excess
of α-chloroacetaldehyde (0.2 mL, 1.10 mmol) for 4 h in the presence
of an equivalent amount of Na2CO3 (988 mg, 1.10 mmol). After it was
cooled, the solution was evaporated to dryness and the residue was
chromatographed on silica and eluted with methanol/dichloromethane
to give the pure product. Yield: 169 mg (92%). Mp: 105−108 °C. 1H
NMR (500 MHz, CDCl3, 292 K): δ 8.72 (d, J = 4.85 Hz,1H, NP), 8.5
(s, 1H, Im), 8.20 (d, J = 7.45 Hz, 1H, NP), 7.98 (d, J = 9.15 Hz, 2H,
Ph. NP), 7.77 (s, 1H, Im), 7.60 (s, 1H, NP), 7.58−7.46 (m, 4H, Ph).
13C NMR (125 MHz, CDCl3, 294 K): 148.6 (CCNNP), 142.8
(NCNNP), 137.1 (CCCNP), 135.3 (NCCNP), 131.5 (CCCNP), 130.8
(CCCNP), 129.2 (CCCPh), 129.2 (CCCPh), 129.1 (NCCPh), 129.
(CCCPh), 129.0 (CCCPh), 128.8 (CCCPh), 123.48 (CCCNP), 121.6
(CCCNP), 118.7 (NCCIm), 112.60 (NCCIm).
Synthesis of L3Br. A 500 mg amount (2.03 mmol) of L2H2 was
dissolved in glacial acetic acid (10 mL), and 0.2 mL of bromine was
added. The mixture was stirred at room temperature for 15 h. The
precipitate was filtered and redissolved in water. The suspension was
made basic with sodium carbonate and extracted with dichloro-
methane. The organic layer was dried to give the pure product. Yield:
1
556 mg (86%). Mp: 204−206 °C. H NMR (500 MHz, CDCl3, 292
K): δ 8.87 (d, J = 4.3 Hz,1H, NP), 8.32 (d, J = 8.3 Hz, 1H, NP), 7.84
(s, 1H, Im), 7.82−7.78 (m, 3H, NP, Ph), 7.65 (dd, 1H, NP), 7.54−
7.46 (m, 3H, Ph). 13C NMR (125 MHz, CDCl3, 294 K): 148.6
(CCNNP), 143.7 (NCNNP), 142.1 (CCCNP), 138.2 (NCCNP), 137.6
(CCCNP), 133.1 (CCCNP), 130.7 (CCCPh), 130.0 (CCCPh), 129.4
(NCCPh), 129.3 (CCCPh), 129.2 (CCCPh), 129.1 (CCCPh), 127.6
(CCCNP), 123.8 (CCCNP), 122.8 (NCCIm), 119.5 (NCCIm).
Conversion of 2 to 3. Compound 2 (40 mg, 0.065 mmol) was
taken up in a 10 mL DCE solution, [Cp*IrCl2]2 (26 mg, 0.033 mmol)
and NaOAc (32 mg, 0.39 mmol) were added, and the mixture was
refluxed for 12 h; after that a procedure similar to the synthesis of 1
was followed. Yield: 61 mg (90%).
Synthesis of 4. A THF solution (10 mL) of anhydrous SnCl2 (15
mg, 0.082 mmol) was added dropwise to a dichloromethane solution
(10 mL) of 1 (51 mg, 0.08 mmol), whereupon the initial yellow
solution turned bright orange. The resultant solution was concentrated
under vacuum, and 15 mL of petroleum ether was added with stirring
to induce precipitation. Repeated washing followed by prolonged
drying under vacuum provided an orange crystalline solid. Crystals
suitable for X-ray study were grown by layering petroleum ether over a
dichloromethane solution of the compound. Yield: 62 mg (93%). Mp:
>250 °C. 1H NMR (500 MHz, DMSO-d6, 292 K): δ 9.09 (s, 1H, NP),
8.20 (d, J = 9.15 Hz, 1H, NP), 8.0 (dd, J = 6.85 Hz, J = 2.45 Hz, 1H,
Ph), 7.62 (dd, J = 6.42 Hz, J = 1.85 Hz, 1H, Ph), 7.54 (s, 1H, Im), 7.44
(d, J = 10.1 Hz, 1H, NP), 7.19−7.15 (m, 2H, Ph), 2.72 (s, 3H,
CH3NP), 2.70 (s, 3H, CH3NP), 1.71 (s, 15H, CpMe5). 13C NMR (125
MHz, DMSO-d6, 294 K): 159.9 (Ir−Ccyclometalated), 155.6 (NCNNP),
147.3 (CCCNP), 142.7 (NCCNP), 138.9 (CCCNP), 138.1 (CCCNP),
129.5 (CCCNP), 128.3 (CCCNP), 126.8 (NCCNP), 124.2 (CCCPh),
124.1 (CCCPh), 123.4 (CCCPh), 122.2 (CCCPh), 122.1 (CCCPh),
112.0 (NCCIm), 105.1 (NCCIm), 92.0 (CpMe5), 24.8 (CH3),
18.5(CH3), 9.9 (CpMe5). ESI-MS: m/z 600 [Ir(L1)Cp*]+. Anal.
Calcd for C28H29N3Cl3SnIr: C, 40.72; H, 3.54; N, 5.09. Found: C,
40.31; H, 3.52; N, 5.11.
Synthesis of 5. A THF solution (10 mL) of anhydrous SnCl2 (30
mg, 0.164 mmol) was added dropwise to a dichloromethane solution
(10 mL) of 3 (78 mg, 0.08 mmol) following a procedure similar to the
synthesis of 4. Compound 5 was isolated as a red crystalline solid.
Yield: 100 mg (93%). Mp: >250 °C dec. 1H NMR (500 MHz, DMSO-
d6, 292 K): δ 8.68(d, J = 5.1 Hz, 1H, NP), 8.55 (s, 1H, Im), 8.41 (d, J
= 7.75 Hz, 1H, Ph), 8.31 (d, J = 8.3 Hz, 1H, NP), 7.83 (d, J = 7.75 Hz,
1H, Ph), 7.70−7.65 (m, 1H, NP), 7.26 (t, J = 7.6 Hz, 1H, Ph), 7.15 (J
= 8.3 Hz, 1H, NP), 7.13 (t, 1H, Ph), 2.00 (s, 15H, CpMe5), 1.52 (s,
15H, CpMe5).
Synthesis of 1. [Cp*IrCl2]2 (44 mg, 0.06 mmol), NaOAc (28 mg,
0.34 mmol), and L1H (33 mg, 0.12 mmol) were dissolved in
dichloroethane (10 mL), and the mixture was refluxed for 4 h under
nitrogen. The resulting orange-red suspension was filtered through a
small bed of Celite. The filtrate was then concentrated under reduced
pressure, followed by the addition of 15 mL of diethyl ether with
stirring to induce precipitation. Repeated washings followed by
prolonged drying under vacuum provided the cyclometalated
compound 1 as a red solid. Crystals suitable for X-ray study were
grown by slow vapor diffusion of diethyl ether into a saturated
dichloromethane solution of the compound. Yield: 66 mg (86%). Mp:
1
>250 °C. H NMR (500 MHz, CDCl3, 292 K): δ 8.54 (s, 1H, NP),
7.82 (d, J = 7.75 Hz, 1H, Ph), 7.69 (d, J = 8.05 Hz, J = 10 Hz, 1H,
NP), 7.63 (d, J = 7.15 Hz, 1H, Ph), 7.57 (d, J = 9.75 Hz, 1H, NP), 7.19
(s, 1H, Im), 7.11 (t, J = 7.3 Hz 1H, Ph), 7.0 (t, J = 7.42 Hz, 1H, Ph),
2.73 (s, 3H, CH3NP), 2.67 (s, 3H, CH3), 1.73 (s, 15H, CpMe5). 13C
NMR (125 MHz, CDCl3, 292 K): 159.2 (Ir−Ccyclometalated), 154.3
(NCNNP), 146.6 (CCCNP), 143.2 (NCCNP), 139.0 (CCCNP), 136.2
(CCCNP), 129.7 (CCCNP), 128.7 (CCCNP), 126.8 (NCCNP), 122.8
(CCCPh), 122.6 (CCCPh), 122.2 (CCCPh), 122.1 (CCCPh), 121.5
(CCCPh), 113.3 (NCCIm), 104.1 (NCCIm), 87.5 (CpMe5), 24.8(CH3),
18.7(CH3), 9.47 (CpMe5). ESI-MS: m/z 600 [M − Cl]+, where M =
Ir(L1)Cp*Cl. Anal. Calcd for C28H29N3ClIr: C, 52.89; H, 4.60; N,
6.61. Found: C, 52.47; H, 4.56; N, 6.45.
Synthesis of 2. A mixture of [Cp*IrCl2]2 (40 mg, 0.05 mmol),
NaOAc (25 mg, 0.31 mmol), and L2H2 (27 mg, 0.11 mmol) were
reacted by following a procedure similar to the synthesis of 1.
Compound 2 was isolated as a red crystalline solid. Crystals suitable
for X-ray study were grown by slow vapor diffusion of diethyl ether
into a saturated dichloromethane solution of the compound. Yield: 60
mg (91%). Mp: >250 °C. 1H NMR (500 MHz, CDCl3, 292 K): δ 8.60
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dx.doi.org/10.1021/om4004658 | Organometallics 2013, 32, 4306−4313