Inorganic Chemistry
ARTICLE
was stirred at 120 °C overnight. The solid was collected and recrystal-
lized from DCM/hexane to afford 12 (88 mg, 10%) as yellow crystals.
Anal. Calcd for C68H56Cl2F4Ir2N8O4: C, 51.67; H, 3.57; N, 7.09; Found: C,
51.48; H, 3.50; N, 7.14; δH (700 MHz, CDCl3) 7.69 (2H, dd, J 2.4, 10.3),
7.35 (2H, dd, J 5.6, 8.4), 7.24ꢀ7.22 (2H, m), 6.88 (4H, s), 6.86 (2H, s),
6.66 (2H, td, J 2.4, 8.5), 6.47 (2H, td, J 2.4, 8.5), 6.40 (2H, s), 5.65 (2H, dd, J
2.4, 10.9), 2.44 (6H, s), 2.28 (12H, s), 2.18 (12H, s), 1.54 (6H, s); HRMS
(MALDI-TOF): calcd for [C68H56Cl2F4Ir2N8O4þHþ]: 1581.3074.
Found: 1581.3049.
(2H, dd, J 6.2, 12.2), 7.58 (1H, dd, J 5.5, 8.4), 7.54 (1H, dd, J 5.4, 8.3),
7.39ꢀ7.30 (1H, m), 7.12 (2H, s), 7.10 (2H, s), 6.83ꢀ6.75 (1H, m),
6.75ꢀ6.70 (1H, m), 6.47 (1H, dd, J 2.3, 9.7), 6.43 (1H, dd, J 2.3, 9.5),
2.94 (2H, dt, J 7.0, 14.0), 2.68 (2H, dt, J 6.8, 13.7), 2.54 (2H, dt, J 6.8,
13.5), 1.29ꢀ1.24 (18H, m), 1.20 (6H, d, J 6.8), 1.18 (6H, d, J 6.8), 1.12
(6H, d, J 6.8); λabs (CH2Cl2) (ε, 104 dm3 Mꢀ1 cmꢀ1) 243 nm (4.35);
HRMS (MALDI-TOF): calcd for [C52H56F2IrN5O4þHþ]: 1046.4008.
Found: 1046.3987.
Complex 18. Following the procedure for 16, 15 (70 mg, 0.05
mmol), picolinic acid (50 mg, 0.5 mmol), Na2CO3 (55 mg, 0.6 mmol),
and 2-ethoxyethanol (10 mL) gave yellow crystals of 18 (40 mg, 69%).
Anal. Calcd for C58H68F2IrN5O4: C, 61.68; H, 6.07; N, 6.20. Found: C,
61.75; H, 6.16; N, 6.02; δH (700 MHz, CDCl3) 8.18 (1H, d, J 7.8), 8.07
(1H, d, J 5.3), 7.88 (1H, td, J 1.4, 7.7), 7.56 (1H, dd, J 5.3, 8.4),
7.53ꢀ7.43 (6H, m), 7.38ꢀ7.33 (1H, m), 6.87 (1H, td, J 2.4, 8.6),
6.64 (1H, td, J 2.4, 8.6), 6.12 (1H, dd, J 2.4, 9.9), 1.35 (9H, s), 1.30
(9H, s), 1.25 (9H, s), 1.11 (18H, s), 0.71 (9H, s); λabs (CH2Cl2) (ε,
104 dm3 Mꢀ1 cmꢀ1) 256 nm (4.30); HRMS (MALDI-TOF): calcd
for [C58H68F2IrN5O4þHþ]: 1130.4977. Found: 1130.4927.
X-ray Crystallography. Single-crystal X-ray diffraction experi-
ments (Table 1) were carried out on Bruker 3-circle diffractometers
with CCD area detectors SMART 1000 (14, 16, 18) or SMART 6000
(12, 13, 15), using graphite-monochromated Mo-KR radiation (λ=0.71073
Å) and Cryostream (Oxford Cryosystems) open-flow N2 cryostats. The
structures were solved by Patterson method and refined by full-matrix least-
squares on F2 of all data, using SHELXTL 6.1422 and OLEX2 software.23
Full crystallographic data, excluding structure factors, have been deposited
at the Cambridge Crystallographic Data Center.
The diffraction of 12 was weak (mean I/σ(I) = 5.3, almost no
observed reflections with d < 0.9) and showed a pseudo I-centered
pattern, reflections with odd h þ k þ l having the mean intensity of about
14% of the overall average. In fact, the structure can be solved in the
space group I2/m and refined (with disordered model) to R1 = 0.13.
Although the lattice parameters suggest a pseudomerohedral twin law
(ꢀ1 0 0/0 ꢀ1 0/1 0 1) giving the transformed cell a = 12.123,
b = 14.384, c = 20.330 Å, R = γ = 90°, β = 107.86°, no satisfactory
correction could be achieved on this model. The DMSO molecule of
crystallization is disordered [except the O(3) atom] between positions A
and B with occupancies 0.535(4) and 0.465(4), respectively. ADP
ellipsoids of all atoms of the host molecule (though not of the DMSO)
are elongated in the same direction, not consistent with any reasonable
libration model but pointing toward the solvent-occupied cavity. This
can be attributed either to a whole-molecule translational disorder
(related to the DMSO disorder) or to incommensurate modulation
which could not be rationalized, although some reflections indeed show
shoulders or weak satellite peaks which could be tentatively attributed to
Complex 13. Following the procedure for 12, 9 (533 mg, 1.5 mmol),
iridium chloride (200 mg, 0.6 mmol) and 2-ethoxyethanol:water (10 mL;
3:1 v/v) gave 13 (230 mg, 40%) as yellow crystals. Anal. Calcd for
C92H104Cl2F4Ir2N8O4: C, 57.64; H, 5.47; N, 5.84; Found: C, 57.48; H,
5.40; N, 5.72; δH (700 MHz, CDCl3) 7.63 (2H, dd, J 2.4, 10.1), 7.27
(4H, ddd, J 5.7, 8.5, 19.7), 7.13 (2H, s), 7.01 (4H, s), 6.59 (2H, s), 6.51
(2H, td, J 2.5, 8.3), 6.47 (2H, td, J 2.4, 8.4), 5.52 (2H, dd, J 2.4, 10.8), 3.55
(2H, dt, J 6.6, 13.4), 2.89 (4H, tt, J 6.9, 14.0), 2.16 (4H, dt, J 6.8,
13.6), 2.05 (2H, dt, J 6.8, 13.6), 1.44 (6H, d, J 6.4), 1.30 (12H, d, J
6.9), 1.24 (12H, d, J 6.9), 1.01 (18H, d, J 6.8), 0.96 (12H, d, J 6.8),
0.81 (6H, d, J 6.8), 0.77 (6H, d, J 6.9). HRMS (MALDI-TOF): calcd
for [C92H104Cl2F4Ir2N8O4þHþ]: 1917.6830. found: 1917.6828.
Complex 14. Following the procedure for 12, 11 (280 mg, 0.7
mmol), iridium chloride (115 mg, 0.3 mmol), and 2-ethoxyethanol/
water (10 mL, 3:1 v/v) gave 14 (100 mg, 40%) as yellow crystals. Anal.
Calcd for C96H116Cl2Ir2N8O8: C, 58.67; H, 5.95; N, 5.70; Found: C,
58.50; H, 5.73; N, 5.76; δH (700 MHz, CDCl3) 7.46 (2H, d, J 2.4), 7.18
(4H, dd, J 8.4, 11.3), 7.04 (2H, s), 7.00 (4H, s), 6.55 (2H, s), 6.36 (2H,
dd, J 2.4, 8.3), 6.27 (2H, dd, J 2.4, 8.5), 5.35 (2H, d, J 2.4), 3.75 (6H, s), 3.41
(2H, dt, J 6.7, 13.4), 3.29 (6H, s), 2.90 (2H, dt, J 6.9, 13.8), 2.85 (2H, dt, J
7.0, 13.9), 2.25ꢀ2.14 (6H, m), 1.42 (6H, d, J 6.4), 1.28 (12H, t, J 7.3), 1.25
(12H, d, J 6.9), 1.02 (6H, d, J 6.7), 0.99 (24H, t, J 7.3), 0.79 (12H, t, J 6.5).
HRMS (MALDI-TOF): calcd for [C96H116Cl2Ir2N8O8þHþ]: 1965.7630.
Found: 1965.7627.
Complex 15. Following the procedure for 12, 10 (640 mg, 1.6
mmol), iridium chloride (230 mg, 0.7 mmol) and 2-ethoxyethanol/
water (10 mL, 3:1 v/v) gave 15 (140 mg, 14%) as yellow crystals. Anal.
Calcd for C78H97ClF3IrN6O3: C, 65.45; H, 7.52; N, 5.45; Found: C,
65.63; H, 7.80; N, 5.31; δH (400 MHz, CDCl3) 8.18ꢀ8.05 (3H, m),
7.63 (1H, d, J 1.6), 7.54 (1H, d, J 1.6), 7.47ꢀ7.33 (6H, m), 7.05 (2H, d, J
8.7), 6.88ꢀ6.78 (1H, m), 6.60ꢀ6.49 (1H, m), 6.02 (1H, dd, J = 10.2,
2.4), 1.39 (9H, s), 1.38 (9H, s), 1.33 (9H, s), 1.31 (9H, s), 1.18 (9H, s),
1.00 (9H, s), 0.85 (9H, s), 0.81 (9H, s), 0.60 (9H, s). MS (MALDI-
TOF) m/z = 1042.3 (M ꢀ 408).
Complex 16. A mixture of complex 13 (80 mg, 0.04 mmol),
acetylacetone (0.1 mL), Na2CO3 (100 mg, 0.8 mmol), and 2-ethox-
yethanol (10 mL) was stirred at 120 °C overnight. The solvent was
removed under reduce pressure, and the product was purified by column
chromatography (SiO2, eluent DCM/hexane (2:3 v/v) followed by
recrystallization from DCM/hexane to give 16 as yellow crystals (50 mg,
61%). Anal. Calcd for C51H59F2IrN4O4: C, 59.92; H, 5.82; N, 5.48.
Found: C, 59.74; H, 5.93; N, 5.20; δH (700 MHz, CDCl3) 7.58 (1H, dd,
J 5.5, 8.3), 7.44 (1H, dd, J 5.6, 8.3), 7.21 (1H, dd, J 2.4, 9.6), 7.11 (2H, s),
7.03 (2H, s), 6.91 (1H, td, J 2.4, 8.7), 6.58 (1H, td, J 2.5, 8.6), 6.18 (1H,
dd, J 2.4, 10.1), 5.37 (1H, s), 2.95 (1H, dt, J 7.0, 13.9), 2.90 (1H, dt, J 6.9,
13.8), 2.74 (2H, hept, J 6.9), 2.32 (2H, hept, J 6.8, 13.7), 1.88 (6H, d, J
3.6), 1.28 (6H, d, J 6.9), 1.24 (6H, d, J 6.9), 1.17 (12H, d, J 6.8), 1.05
it. 18 CH2Cl2 also gave few observed reflections with d < 0.9,
3
notwithstanding strong diffraction at low angles.
’ RESULTS AND DISCUSSION
Synthesis. The OXD ligands 8ꢀ11 were synthesized in moder-
ate to high yields, starting from benzonitrile derivatives 4 and 5,
following the tetrazole route24 via 6 and 7, as shown in Scheme 1.
The OXD ligands were then reacted with iridium chloride under
standard conditions25 (step iii) for forming a bridged μ-dichloro-
bridged diiridium C∧N ligand complex (e.g., complex 2). These
reactions did not follow the usual course. Instead, the diiridium
complexes 12ꢀ14 were obtained from 8, 9, and 11, respectively, and
the monoiridium complex 15 was obtained from 10. Presumably, the
substantial twisting of part of the OXD system caused by the ortho-
alkyl substituents leads to steric overcrowding which inhibits the
normal course of the metalꢀligand coordination reactions, to the
(6H, d, J 6.8), 1.00 (6H, d, J 6.8); λabs (CH2Cl2) (ε, 104 dm3 Mꢀ1 cmꢀ1
)
263 nm (3.80); HRMS (MALDI-TOF): calcd for [C51H59F2IrN4O4 þ
Hþ]: 1023.4213.
Complex 17. Following the procedure for 16, 13 (100 mg, 0.05
mmol), picolinic acid (40 mg, 0.5 mmol), Na2CO3 (55 mg, 0.6 mmol),
and 2-ethoxyethanol (10 mL) gave yellow crystals of 17 (30 mg, 28%).
Anal. Calcd for C52H56F2IrN5O4: C, 59.75; H, 5.40; N, 6.70. Found: C,
59.65; H, 5.48; N, 6.55; δH (700 MHz, CDCl3) 8.25 (1H, d, J 7.7), 7.87
3356
dx.doi.org/10.1021/ic102153x |Inorg. Chem. 2011, 50, 3354–3362