Enhanced emission and analyte sensing by cinchonine iridium(III) cyclometalated complexes bearing bent diphosphine chelators

Article abstract of DOI:10.1021/om400028n

Ir(III) complexes of cyclometalating ligands derived from the natural product cinchonine and bent (4,6-bis(diphenylphosphino)phenoxazine (Nixantphos), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos)) and planar diphosphine ligands (1,2-bis(diphenylphosphino)benzene (dppb)) exhibit good luminescence with quantum efficiencies higher than those of their parent congeners. Steric hindrance by both the bulky cinchonine-derived ligand and bent diphosphine could limit nonradiative energy transfer. The cinchonine-derived and parent complexes cover a broad emission range from 472 to 569 nm with quantum efficiencies up to 0.38 and lifetimes from 0.01 to 0.46 μs in degassed CH₂Cl₂ solution at room temperature. DFT calculations on selected examples are in good agreement with solid-state structures determined crystallographically and accurately predict wavelengths of emission by excited electron decay from a quinoline-centered orbital to an Ir 5d-phenyl molecular orbital. The complex [(pcn)₂Ir(Nixantphos)] [PF₆] (2; pcn = 2′-phenyl-9-O-benzyl-10,11-dihydrocinchonine- C₂,N) exhibits the highest quantum yield and could detect electron-deficient aromatic species at ppm levels.

Full text of DOI:10.1021/om400028n

Article
pubs.acs.org/Organometallics
Enhanced Emission and Analyte Sensing by Cinchonine Iridium(III)
Cyclometalated Complexes Bearing Bent Diphosphine Chelators
Shao-Xiong Luo,†,‡,# Lu Wei,†,‡,# Xin-Hai Zhang,† Min Hwee Lim,§ K. X. Vivian Lin,† M. H. Valerie Yeo,†
Wen-Hua Zhang,*,† Zhi-Pan Liu,*,∥ David J. Young,*,†,⊥ and T. S. Andy Hor*,†,§
†Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 3 Research Link, 117602, Singapore,
‡Raffles Institution, 1 Raffles Institution Lane, 575954, Singapore
§Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore
∥MOE Key Laboratory for Computational Physical Sciences, Fudan University, Shanghai 200433, People’s Republic of China
⊥Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE 1410, Brunei Darussalam
S
* Supporting Information
ABSTRACT: Ir(III) complexes of cyclometalating ligands derived from the natural
product cinchonine and bent (4,6-bis(diphenylphosphino)phenoxazine (Nixantphos), 4,5-
bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos)) and planar diphosphine
ligands (1,2-bis(diphenylphosphino)benzene (dppb)) exhibit good luminescence with
quantum efficiencies higher than those of their parent congeners. Steric hindrance by both
the bulky cinchonine-derived ligand and bent diphosphine could limit nonradiative energy
transfer. The cinchonine-derived and parent complexes cover a broad emission range from
472 to 569 nm with quantum efficiencies up to 0.38 and lifetimes from 0.01 to 0.46 μs in
degassed CH2Cl2 solution at room temperature. DFT calculations on selected examples are
in good agreement with solid-state structures determined crystallographically and
accurately predict wavelengths of emission by excited electron decay from a quinoline-
centered orbital to an Ir 5d−phenyl molecular orbital. The complex [(pcn)2Ir-
(Nixantphos)][PF6] (2; pcn = 2′-phenyl-9-O-benzyl-10,11-dihydrocinchonine-C2,N)
exhibits the highest quantum yield and could detect electron-deficient aromatic species at ppm levels.
azabicyclo[2.2.2]octane and benzyl moieties improve solubility
and serve to protect emission from triplet−triplet annihila-
tion.3−6 As a result, these complexes are highly soluble in
organic solvents and phosphoresce at tunable emission
wavelengths by modifying cyclometalating or ancillary ligands.
Improved quantum efficiencies of these complexes were
observed in comparison to those of their quinoline
congeners.7,8 In view of the increasingly diverse applications
of these second and third row transition metal based phosphors
in organic light-emitting diodes (OLEDs),9−30 light-emitting
electrochemical cells (LECs),31−37 sensing,38−44 biological
labeling and imaging,45−48 photoredox catalysts,48−53 and
metal−organic frameworks,44,54−56 further improvement in
the emission efficiency of these Cinchona alkaloid based Ir(III)
complexes is worthy of investigation.
INTRODUCTION
■
We have recently reported that, with relatively straightforward
synthetic modifications, Cinchona alkaloid derivatives (Chart 1)
function as novel cyclometalating and coordinating ligands for
phosphorescent Ir(III) complexes.1,2 The bulky 1-
Chart 1
To obtain highly emissive Ir(III) complexes, we incorporated
the bent-diphosphine ligands 4,6-bis(diphenylphosphino)-
phenoxazine (Nixantphos) and 4,5-bis(diphenylphosphino)-
9,9-dimethylxanthene (Xantphos), which are commonly found
as ligands in transition-metal-based catalysis57−62 but are exotic
as chelators in luminescent materials.63 We proposed that the
bent-diphosphine backbones would serve to reduce non-
Received: January 13, 2013
© XXXX American Chemical Society
A
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a
Chart 2. Structures of Complexes 1−12
a
−
The PF6 anions are omitted for clarity.
radiative relaxation of the excited cyclometalated complex by
further hindering intermolecular stacking. In addition, the two
methyl groups in Xantphos would provide further steric
hindrance to intermolecular interactions. We surmised that
these features in tandem with the dendrimer-like cinchonine-
derived ligand would maximize emission. To gauge the
importance of each of these influences, we included the
corresponding 2-phenylpyridine and 2-phenylquinoline cyclo-
B
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Figure 1. Complexes 6 (a), 7 (b), and 11 (c) with labeling scheme. Counterions, solvates, and hydrogen atoms, except H1 in 11, are omitted for
clarity.
Figure 2. UV−vis spectra of complexes 1−6 (a) and 7−12 (b) recorded in degassed CH2Cl2 solutions at room temperature.
metalating complexes and 1,2-bis(diphenylphosphino)benzene
(dppb) auxiliary ligand with a planar benzene backbone. The
dinuclear Ir(III) complexes [(pcn)2IrCl]2 (P1), [(pq)2IrCl]2
(P2), [(ppy)2IrCl]2 (P3), and [(fppy)2IrCl]2 (P4) (pcn = 2′-
phenyl-9-O-benzyl-10,11-dihydrocinchonine-C2,N; pq = 2-
phenylquinolinato-C2,N; ppy = 2-phenylpyidinato-C2,N; fppy
= 2-(4,6-difluorophenyl)pyridinato-C2,N) were combined with
our three diphosphine ligands to yield an array of 12 cationic,
mononuclear Ir(III) species (Chart 2). The energy of relevant
molecular orbitals in [(pq)2Ir(Xantphos)][PF6] (6) was
calculated using DFT methods to provide insight into the
mechanism of emission. The high quantum efficiency of 0.38
for [(pcn)2Ir(Nixantphos)][PF6] (2) permitted a preliminary
study of its use as a chemical sensor for detection of the
electron-deficient species 1-fluoro-4-nitrobenzene, 1-bromo-
2,4-dinitrobenzene, and 4-nitrophthalonitrile at ppm levels.
(III) precursors (P1−P4) were refluxed with diphosphine
ligands in CH2Cl2/MeOH (2/1, v/v) followed by an anion
exchange using excess NH4PF6 and column separation to give
orange, orange-red, or yellow-green fine powders. These
complexes show good solubility in CH2Cl2, CHCl3, MeCN,
1
and DMSO. Complexes 1−12 were characterized by H, 13C,
and 31P NMR spectroscopy and ESI-MS spectrometry and
additional 19F NMR analysis for 10−12. The ESI-MS spectra
gave diagnostic peaks which are ascribed to [(C∧N)2Ir(P−P)]+
(C∧N delineates cyclometalating ligands and P−P delineates
diphosphine ligands; see the Experimental Section). The 31P
NMR spectra for these complexes are also diagnostic and the
singlet resonances from −30.2 to 21.9 ppm indicated chemical
equivalence for the two phosphorus atoms, whereas the septets
−
at around −145 ppm are characteristic of PF6 anions.
Complexes 1−12 were further characterized by FT-IR and
their bulk purity confirmed by elemental analysis.
RESULTS AND DISCUSSION
Single-crystal structures of 6−8, 10, and 11 were obtained
through X-ray diffraction studies. These complexes exhibit
some common structural characteristics: the Ir(III) center
adopts a distorted-octahedral geometry with the two N donor
■
Synthesis of 1−12 and X-ray Structures of 6−8, 10,
and 11. The syntheses of complexes 1−12 were similar and
employed established procedures.1,2,32,64 The dinuclear iridium-
C
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Figure 3. Normalized luminescence spectra of complexes 1−6 (a) and 7−12 (b) recorded in degassed CH2Cl2 solutions at room temperature.
Table 1. Photophysical Data for 1−12 in Degassed CH2Cl2 at Room Temperature
a
complex
UV−vis, nm (ε, 103 L mol−1 cm−1
)
emission λmax, nm
Φ
τ, μs
[(pcn)2Ir(dppb)][PF6] (1)
227 (59.9), 284 (26.1), 344 (11.1), 414 (3.7)
531
563
569
525
553
555
488
495
517
472
497
476
0.19
0.38
0.13, 0.01
0.03, 0.10
0.01, 0.40
0.09, 0.006
0.01, 0.002
0.46
[(pcn)2Ir(Nixantphos)][PF6](2)
[(pcn)2Ir(Xantphos)][PF6] (3)
[(pq)2Ir(dppb)][PF6] (4)
229 (154.6), 289 (32.6), 344 (16.7), 373 (12.5), 427 (3.6)
228 (126.5), 285 (32.7), 356 (13.8), 482 (0.8)
230 (51.6), 280 (25.6), 334 (8.6), 345 (8.4), 385 (3.7), 406 (2.7)
227 (43.8), 274 (14.0), 338 (8.0), 435 (0.8)
0.16
0.047
0.048
0.025
0.16
[(pq)2Ir(Nixantphos)][PF6] (5)
[(pq)2Ir(Xantphos)][PF6] (6)
[(ppy)2Ir(dppb)][PF6] (7)
227 (39.0), 282 (12.1), 349 (3.8), 362 (3.9), 410 (1.2)
228 (74.0), 263 (33.6), 307 (12.6), 363 (5.9)
0.002, 0.08
0.008, 0.015
0.004, 0.030
0.22, 0.02
0.003, 0.06
0.004, 0.06
[(ppy)2Ir(Nixantphos)][PF6] (8)
[(ppy)2Ir(Xantphos)][PF6] (9)
[(F2ppy)2Ir(dppb)][PF6] (10)
[(F2ppy)2Ir(Nixantphos)][PF6] (11)
[(F2ppy)2Ir(Xantphos)][PF6] (12)
228 (88.4), 270 (30.6), 310 (16.1), 373 (4.6)
N.A.
227 (68.5), 263 (24.4), 318 (9.4), 358 (3.1)
0.0010
0.30
228 (68.5), 256 (31.6), 278 (14.1), 312 (10.7), 343 (5.3)
227 (68.2), 263 (22.7), 318 (8.5), 358 (3.0)
0.00070
0.020
227 (65.7), 262 (23.9), 314 (9.6), 356 (3.0)
a
With respect to Rhodamine 6G (Φ = 0.95 in ethanol).
atoms invariably trans to each other and the phosphine donors
trans to the two Ir−C bonds, regardless of the steric demands
of the phosphine and cyclometalating ligands (Figure 1, Figure
S1 (Supporting Information)). The average Ir−P bond distance
for 7 (2.35 Å, Table S4 (Supporting Information)) is much
shorter than those found in 6 (2.57 Å) and 11 (2.51 Å), which
is ascribed to the reduced bite angle (five-membered ring in 7
vs eight-membered rings in 6 and 11). It is nonetheless longer
cyclometalated phenylquinoline complexes.69−72 The two
phenyl rings in the Nixantphos backbone of 11 are tilted
with a dihedral angle between C1−C2−C3−C4−C5−C6 and
C7−C8−C9−C10−C11−C12 of 29.8°, which is similar to the
corresponding distortion in 6.
Photophysical Properties of 1−12. The UV−vis
absorption and emission spectra of complexes 1−12 are
given in Figures 2 and 3, and the details are given in Table 1.
The absorption spectra of all the complexes are dominated
by multiple bands originating from ligand-centered π−π*
transitions and MLCT transitions, in common with many
cyclometalated Ir(III) complexes. The intense bands in the
UV−vis spectra for all complexes in the high-energy portion of
the spectra between 230 and 350 nm can be assigned to the
spin-allowed 1(π−π*) ligand transition. The weaker, low-
energy bands at wavelengths longer than 400 nm suggest
than those found in [Ir(tpitH)(PPh3)2Cl2] (Ir−PtpitH
=
2.1898(12) Å) and doubly fused five-membered rings in
[Ir(tpit)(PPh3)2Cl] (Ir−Ptpit = 2.1529(8) Å).65 Furthermore,
average Ir−P bond distances found in 6 and 11 are much
longer than those found in Rh(Nixantphos)(CO)H(PPh3)
(average 2.34 Å),66 Ir(Nixantphos)Cl(COD) (average 2.43
Å),58 Ir(Xantphos)(CO)2Cl (average 2.42 Å), and Ir-
(Xantphos)(CO)2Br (average 2.41 Å),67 probably due to the
strong trans effect of the Ir−C bond, which serves to weaken
the Ir−P bonds. The respective average Ir−C and Ir−N bond
distances of 2.06 and 2.10 Å (6), 2.06 and 2.07 Å (7), and 2.03
and 2.06 Å (11) are similar and comparable to those in related
cyclometalated iridium(III) complexes.7,8,68 The two phenyl
rings in the Xantphos backbone of 6 are tilted with a dihedral
angle between C1−C2−C3−C4−C5−C6 and C10−C11−
C12−C13−C14−C15 of 31.0°. The two cyclometalated
phenylquinoline rings are also distorted and deviate from
coplanarity. Similar observations have been reported for other
3
substantial mixing of spin -forbidden MLCT and higher-lying
1MLCT transitions facilitated by the strong spin−orbit coupling
of the Ir(III) center (Figure 2).8,10,68,73−75
Complexes 1−12 give intensive emissions in a broad range of
color from 472 nm for 10 (blue) to 569 nm for 3 (orange). The
quantum yields for these complexes are up to 0.38 (2) at room
temperature, and lifetimes are in the range 0.01−0.46 μs.
Vibronic fine structures were observed for dppb- and Xantphos-
based structures 1, 4, 7, 9, 10, and 12, indicating that the
emission for these complexes is dominated by ligand-based
D
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Figure 4. HOMO (left) and LUMO (right) energy orbitals of 6 through DFT calculations.
(3π−π*) states. Meanwhile, the line shapes for the other
complexes (2, 3, 5, 6, 8, and 11) were structureless, suggesting
emission primarily from MLCT states.8,68 It should be noted
that the emission wavelengths for 2 (563 nm) and 3 (569 nm)
are similar, suggesting that the excited triplet energies for
Nixantphos and Xantphos are too high relative to 2-
phenylquinoline and the emission is dominated by the
[(pcn)2Ir] moiety. This observation is further supported by
the similar emission wavelengths of 5 (553 nm) and 6 (555
nm). This assumption is supported by the DFT calculations
discussed below. Obvious blue shifts to 531 nm (1) and 525
nm (4) were observed for 1 and 4, which both bear dppb as
chelating ligand, indicating that their HOMO has significant
diphosphine chelate character.76 On comparison of 1−6, 7−9,
and 10−12, it can be surmised that both the reduced
conjugation from quinoline to benzene and substitution of F
for H in a chromophore (ppy to fppy) leads to a hypsochromic
shift in emission.
Strong spin−orbit coupling leads to efficient phosphor-
escence in the majority of the complexes. The room-
temperature quantum yields of these complexes in degassed
CH2Cl2 were up to 0.38, and their luminescent lifetimes fall
between 0.01 and 0.46 μs, consistent with emission from a
triplet excited state. Moreover, the steric hindrance by the bulky
cinchonine ligand and bent-diphosphine ligand presumably
prevents deactivation of the emitters by limiting energy transfer
between the complexes. This is evidenced by the higher
quantum efficiency of complexes 1−3 relative to the parent
phenylquinoline complexes 4−6. The quantum yield of 0.38 for
2 is higher than those for quinoline/isoquinoline derived
emitters previously reported ((pq)2Ir(acac), 0.10;7,8 Ir(piq)3,
0.2673) and our previously reported cinchonine complexes with
nitrogen heterocyclic auxiliary ligands [(pcn)2Ir(bipy)][PF6]
(0.23) and [(pcn)2Ir(phen)][PF6] (0.24).2
set, as utilized in previous work.79 The detailed orbital energy
level as well as calculated bond distances and angles are given in
Tables S1 and S2 (Supporting Information). These results
suggest that Nixantphos- and Xantphos-based complexes have
similar HOMO and LUMO surfaces and that phosphorescence
is due to excited electron decay from a quinoline-dominated
LUMO to the HOMO, which has significant metal 5d−phenyl
π character. The average calculated bond distances for Ir−P
(2.60 Å), Ir−C (2.05 Å), and Ir−N (2.12 Å) and chelate angles
for P−Ir−P (109.8°), N−Ir−N (165.6°), and C−Ir−C (80.4°)
in complex 6, for example, compare favorably with the
experimental values determined by X-ray single-crystal
diffraction (Table S4 (Supporting Information)). The C−O−
C−C torsion angle of 139.1° calculated for 6 is also similar to
that found in the X-ray crystal structure (average 143.2°). The
singlet HOMO and LUMO and triplet spin-density surfaces of
[(pq)2Ir(Xantphos)]+ are illustrated in Figure 4. The calculated
HOMO and LUMO energies in the ground state are −5.15 and
−3.35 eV, respectively. The HOMO is principally composed of
a mixture of Ir d and phenyl π orbitals, whereas the LUMO is
predominantly localized on the quinoline moiety of the
cyclometalating ligands. The calculated MLCT gap of 2.26
eV (548 nm) is in good agreement with the energy of the
emission band found for 6 (555 nm) in CH2Cl2 at room
temperature.
Sensing. We proposed that complexes 1−3 which carry
bulky cinchonine-derived ligands and electron-rich diphosphine
moieties would interact strongly with electron-deficient
aromatic compounds, resulting in a decrease in photo-
luminescent intensity of the complexes. To test this hypothesis,
we selected 1-fluoro-4-nitrobenzene, 1-bromo-2,4-dinitroben-
zene, and 4-nitrophthalonitrile as analytes (Chart 3).
Chart 3
The Ir−P distances in dppb complexes 7 and 10
(2.3523(9)−2.3727(11) Å) are much shorter than those in
Nixantphos and Xantphos complexes 6, 8, and 11
(2.4688(15)−2.5801(18) Å) (Table S4 (Supporting Informa-
tion)). The shorter Ir−P bond means a stronger ligand field
and further destabilization of the metal-centered d−d excited
states, thereby favoring radiative decay. This could explain why
dppb complexes 7 and 10 are more efficient emitters than their
respective Nixantphos and Xantphos analogues.77
DFT Calculations. In order to gain insight into the
electronic structure of the complexes, we have carried out
DFT calculations on nine selected complexes using the SIESTA
package78 with generalized gradient approximation at the GGA-
PBE level and the optimized double-ζ plus polarization basis
Complex 2 was titrated with each analyte in degassed
CH2Cl2 solution. Photoluminescence decreased to less than a
third of its original value (Figures 5−9). This analyte-induced
reduction is ascribed to the formation of an electron donor−
acceptor pair between the Ir(III) complexes and the electron-
deficient analytes; there is a charge transfer from the phosphor
excited state to the low-lying molecular orbital associated with
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Figure 8. Titration of complex 2 with 1-bromo-2,4-dinitrobenzene in
degassed CH2Cl2 at an excitation wavelength of 390 nm.
Figure 5. Titration of complex 2 with 1-fluoro-4-nitrobenzene in
degassed CH2Cl2 at an excitation wavelength of 390 nm.
Figure 9. Fluorescence change on titration of complex 2 with 1-
bromo-2,4-dinitrobenzene at an excitation wavelength of 365 nm with
analyte concentration increasing from left to right.
Figure 6. Titration of complex 2 with 4-nitrophthalonitrile in degassed
CH2Cl2 at an excitation wavelength of 390 nm.
Figure 10. Titration of a 2.05 × 10−7 mol L−1 solution of complex 2 in
degassed CH2Cl2 with a 9 ppm solution of 1-fluoro-4-nitrobenzene at
an excitation wavelength of 345 nm.
Figure 7. Fluorescence change on titration of complex 2 with 4-
nitrophthalonitrile at an excitation wavelength of 365 nm with analyte
concentration increasing from left to right.
the strongly electron-withdrawing nitro group.80,81 The
probable location of contact between analyte and complex is
at the ancillary diphosphine ligand because of the steric
hindrance provided by the bulky quinuclidine moiety.
The detection limit of a 0.2 μM solution of complex 2 toward
1-fluoro-4-nitrobenzene under these conditions was between
3.6 and 9 ppm of analyte (see Figures 10 and 11).
Indeed, titration with 3.6 ppm analyte resulted in a slight
increase in emission by the complex. This may be due to
inhibition of aggregation by the photoluminescent complex.
superior emission properties of the former. This is enhanced by
the bent chelating diphosphine ligands. The energy-harvesting
ability, inherent chirality, and ligand hemilability of these
natural product derived Ir(III) complexes suggest their
potential as photoredox catalysts. Complex 2 is sensitive to
electron-deficient aromatic species at ppm levels and hence may
potentially be used for the detection of TNT and related
explosives. We are exploring these possibilities.
EXPERIMENTAL SECTION
■
All synthetic procedures involving IrCl3·xH2O and other Ir(III) species
were carried out in the dark and under a N2 atmosphere using standard
Schlenk techniques. Elemental analyses were performed on a Perkin-
Elmer PE 2400 CHNS Elemental Analyzer. The 1H, 13C, and 31P
CONCLUSION
A comparative study of cinchonine-derived cyclometalated
Ir(III) diphosphines and their parent congeners indicates the
■
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Synthesis of [(pcn)2Ir(Nixantphos)][PF6] (2). Complex 2 was
purified on a neutral Al2O3 column using ethyl acetate/MeOH (30/1
v/v) as eluent to give an orange-red solid. Yield: 0.24 g (66% based on
1
Ir). H NMR (400 MHz, CDCl3): δ 9.53−9.59 (m, 2H), 8.75−8.79
(m, 1H), 7.83 (br, 3H), 7.51−7.55 (m, 3H), 7.36−7.47 (m, 1H),
7.31−7.33 (m, 1H), 7.23−7.31 (m, 1H), 7.07−7.13 (m, 1H), 6.95−
6.99 (m, 1H), 6.80−6.84 (m, 1H), 6.59−6.73 (m, 3H), 6.52−6.56 (m,
1H), 6.24−6.32 (m, 2H), 6.06−6.08 (m, 1H), 5.94−5.98 (m, 1H),
5.45−5.54 (m, 1H), 4.51−4.61 (m, 1H), 2.83−3.28 (m, 3H), 1.83−
2.01 (m, 1H), 1.36−1.64 (m, 4H), 1.22−1.27 (m, 1H), 0.82−0.91 (m,
2H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 170.5, 148.6, 147.7,
146.7, 146.7, 137.7, 136.6, 133.7, 132.9, 132.9, 132.7, 132.1, 130.3,
129.9, 129.2, 128.9, 128.8, 128.7, 128.4, 128.3, 128.2, 127.9, 126.4,
126.0, 125.9, 123.2, 123.0, 118.8, 118.7, 72.2, 62.9, 62.8, 61.4, 60.8,
51.4, 51.0, 50.7, 50.6, 37.5, 27.7, 27.6, 27.4, 26.6, 26.5, 25.8, 25.7, 14.6,
12.3 ppm. 31P NMR (162 MHz, CDCl3): δ −30.2, −30.6 (sh), −143.0
(hept) ppm. MS (ESI) (CH2Cl2, 150 °C): m/z 1666.3 [Ir-
(pcn)2(Nixantphos)]+. Anal. Calcd for C100H93F6IrN5O3P3: C, 66.23;
H, 5.13; N, 3.86. Found: C, 66.01; H, 5.47; N, 3.73. IR (KBr pellet):
3390 (m), 3059 (w), 2926 (s), 2856 (m), 2346 (w), 1725 (w), 1602
(m), 1578 (m), 1543 (m), 1519 (w), 1455 (s), 1435 (m), 1406 (s),
1376 (m), 1294 (w), 1200 (m), 1160 (w), 1116 (m), 1091 (m), 1013
(m), 940 (w), 843 (s), 766 (w), 743 (m), 695 (m), 557 (m), 525 (m)
cm−1.
Figure 11. Titration of a 2.05 × 10−7 mol L−1 solution of complex 2
with a 3.6 ppm solution of 1-fluoro-4-nitrobenzene in degassed
CH2Cl2 at an excitation wavelength of 345 nm.
NMR spectra were recorded on a Bruker AMX 400 MHz (Bruker
AMX 500 MHz for complex 1) spectrometer, and their chemical shifts
were referenced to Me4Si (TMS) (1H and 13C) or 85% H3PO4 (31P).
The 19F NMR spectra were recorded on a Bruker ACF 300
spectrometer. IR spectra were recorded on a Bruker IFS 48 FTIR
spectrometer as KBr pellets. UV−vis spectra were recorded on a
UVIKON spectrometer. Electrospray mass spectra were obtained in
positive-ion mode with a Finnigan/MAT LCQ mass spectrometer.
Peaks were assigned from the m/z values and the isotope distribution
patterns. Photoluminescence was measured using a Perkin-Elmer LS55
luminescence spectrometer and the quantum yield determined using
Rhodamine 6G (quantum yield 0.95 in ethanol) as reference.82 The
phosphorescence lifetime was measured using an Edinburgh FL920P
Lifetime Spectrometer.
Synthesis of [(pcn)2Ir(Xantphos)][PF6] (3). Complex 3 was
purified on a neutral Al2O3 column using ethyl acetate/MeOH (30/1
v/v) as eluent to give an orange-red solid. Yield: 0.21 g (55% based on
1
Ir). H NMR (400 MHz, CDCl3): δ 9.48 (dd, J = 12.6, 8.7 Hz, 1H),
7.89 (dd, J = 11.9, 6.2 Hz, 2H), 7.51−7.29 (m, 5H), 7.23−7.08 (m,
3H), 7.05−6.93 (m, 1H), 6.81−6.50 (m, 7H), 6.41−6.22 (m, 3H),
6.16 (t, J = 7.6 Hz, 1H), 6.00 (t, J = 7.7 Hz, 2H), 5.65−5.37 (m, 1H),
4.65−4.54 (m, 1H), 4.51 (s, 1H), 3.11 (d, J = 6.5 Hz, 1H), 3.00−2.74
(m, 4H), 2.13−1.98 (m, 4H), 1.88 (dd, J = 26.8, 17.4 Hz, 2H), 1.72−
1.35 (m, 6H), 1.32−1.20 (m, 1H), 0.91 (t, J = 7.1 Hz, 3H) ppm.
13C{1H} NMR (101 MHz, D2O): δ 170.76, 170.58, 156.93, 152.21,
151.95, 150.75, 148.91, 148.78, 146.79, 137.73, 135.53, 134.86, 133.59,
132.90, 132.69, 132.51, 132.43, 132.07, 130.16, 129.48, 129.15, 129.09,
128.71, 128.57, 128.40, 128.33, 128.05, 127.78, 126.46, 126.21, 125.97,
123.60, 123.38, 123.21, 119.46, 119.34, 72.18, 71.98, 63.20, 61.45,
51.48, 50.75, 37.83, 37.71, 37.42, 28.26, 27.63, 26.54, 26.44, 25.88,
25.68, 12.35 ppm. 31P NMR (162 MHz, CD2Cl2): δ −29.4, −145.0
(hept) ppm. MS (ESI) (CH2Cl2, 150 °C): m/z 1693.3 [Ir-
(pcn)2(Xantphos)]+. Anal. Calcd for C103H98F6IrN4O3P3: C, 67.21;
H, 5.33; N, 3.05. Found: C, 67.57; H, 5.42; N, 2.80. IR (KBr pellet):
3345 (m), 3056 (m), 2931 (s), 2868 (m), 1602 (s), 1580 (m), 1543
(m), 1517 (w), 1483 (m), 1453 (m), 1436 (m), 1407 (s), 1369 (m),
1291 (w), 1222 (m), 1201 (m), 1161 (w), 1116 (m), 1090 (m), 1027
(m), 999 (w), 940 (w), 842 (s), 790 (m), 747 (s), 695 (s), 650 (w),
610 (w), 557 (s), 520 (m), 531 (m) cm−1.
Synthesis of [(pcn)2Ir(dppb)][PF6] (1). A mixture of
[(pcn)2IrCl]2 (P1; 0.23 g, 0.1 mmol) and 1,2-bis(diphenylphosphino)-
benzene (dppb; 0.094 g, 0.21 mmol) in a double-necked flask was
flushed three times with N2. A CH2Cl2/MeOH mixture (20 mL/10
mL) was added under N2 and the solution heated to reflux for 12 h.
The solution was then cooled to room temperature and NH4PF6 (0.16
g, 1.0 mmol) in MeOH (5 mL) added under N2. The mixture was
stirred for another 15 h and the solvent evaporated. The resulting
orange-red residue was dried under vacuum and CH2Cl2 (5 mL)
added. NH4Cl was removed by filtration. The solvent was removed
and the product purified by chromatography on neutral Al2O3 column
using ethyl acetate/MeOH (30/1 v/v) as eluent to give an orange-red
solid. Yield: 0.28 g (82% based on Ir). 1H NMR (500 MHz, CD2Cl2):
δ 8.62−8.66 (m, 2H), 8.24−8.27 (m, 2H), 8.02 (s, 1H), 7.83−7.85 (m,
1H), 7.75−7.77 (m, 1H), 7.67−7.68 (m, 1H), 7.51−7.62 (m, 4H),
7.33−7.44 (m, 9H), 7.24−7.29 (m, 2H), 7.12−7.17 (m, 5H), 6.78−
6.84 (m, 1H), 6.53−6.62 (m, 2H), 6.45−6.49 (m, 3H), 6.34−6.40 (m,
4H), 5.01−5.73 (m, 4H), 4.34−4.39 (m, 2H), 2.91−2.95 (m, 2H),
2.69−2.81 (m, 6H), 1.83−2.05 (m, 2H), 1.68−1.74 (m, 1H), 1.22−
1.52 (m, 7H), 0.85−0.88 (m, 3H) ppm. 13C{1H} NMR (126 MHz,
CD2Cl2): δ 171.1, 168.9, 152.1, 151.3, 147.4, 147.4, 145.3, 145.0,
139.8, 139.6, 139.5, 138.3, 137.9, 137.8, 134.2, 134.1, 133.9, 133.8,
133.6, 133.4, 133.9, 133.8, 133.6, 133.4, 133.0, 132.7, 132.5, 131.3,
131.2, 130.8, 129.1, 129.0, 128.9, 128.8, 128.7, 128.6, 128.5, 128.4,
128.3, 128.1, 127.2, 127.1, 126.9, 126.8, 126.7, 126.6, 126.5, 126.4,
124.3, 124.0, 72.1, 71.9, 62.0, 61.0, 51.3, 50.9, 50.5, 50.3, 37.8, 37.8,
28.0, 27.6, 26.8, 26.7, 25.6, 25.5, 12.1, 12.0 ppm. 31P NMR (202 MHz,
CD2Cl2): δ 14.5, −143.6 (hept) ppm. MS (ESI) (CH2Cl2, 150 °C):
m/z 1561.6 [Ir(pcn)2(dppb)]+, 781.6 [Ir(pcn)2(dppb) + H]2+. Anal.
Calcd for C94H90F6IrN4O2P3: C, 66.12; H, 5.28; N, 3.28. Found: C,
66.50; H, 5.39; N, 3.39. IR (KBr pellet): 3422 (w), 3054 (w), 2930
(m), 2868 (m), 2349 (w), 1735 (w), 1655 (w), 1606 (m), 1579 (w),
1542 (m), 1455 (m), 1343 (m), 1370 (w), 1291 (w), 1202 (w), 1162
(w), 1110 (w), 1086 (m), 940 (w), 840 (s), 751 (m), 734 (m), 733
(m), 700 (m), 663 (w), 650 (w), 557 (m), 527 (m) cm−1.
Synthesis of [(pq)2Ir(dppb)][PF6] (4). Complex 4 was purified on
a silica gel column using ethyl acetate/MeOH (30/1 v/v) as eluent to
1
give an orange-red solid. Yield: 0.090 g (38% based on Ir). H NMR
(400 MHz, CDCl3): δ 8.47−8.51 (m, 1H), 8.14−8.16 (m, 1H), 7.95−
7.97 (m, 1H), 7.81−7.83 (m, 1H), 7.72−7.74 (m, 1H), 7.42−7.51 (m,
5H), 7.33−7.36 (m, 2H), 7.21−7.26 (m, 2H), 7.04−7.15 (m, 5H),
6.77−6.81 (m, 1H), 6.58−6.61 (m, 1H), 6.28−6.36 (m, 5H), 5.74−
5.77 (m, 1H) ppm. 13C{1H} NMR (101.1 MHz, CDCl3): δ 172.0,
170.3, 147.1, 145.6, 140.3, 139.3, 134.1, 134.0, 133.5, 133.2, 132.1,
132.0, 131.9, 131.4, 131.1, 131.1, 130.9, 129.6, 129.4, 129.1, 128.8,
128.8, 128.7, 127.9, 127.3, 126.9, 126.8, 124.4, 118.8 ppm. 31P NMR
(162 MHz, CDCl3): δ 14.1, −143.5 (hept) ppm. MS (ESI) (CH2Cl2,
150 °C): m/z 1047.1 [Ir(pq)2(dppb)]+. Anal. Calcd for
C60H44F6IrN2P3: C, 60.45; H, 3.72; N, 2.35. Found: C, 56.91; H,
3.64; N, 1.94 (corresponding to 4·CH2Cl2). IR (KBr pellet): 3431
(w), 3050 (w), 2919 (m), 2850 (m), 1704 (w), 1606 (m), 1578 (m),
1547 (m), 1515, 1483 (w), 1453 (m), 1434 (m), 1330 (m), 1288 (w),
1265 (w), 1218 (w), 1147 (w), 1118 (w), 1089 (m), 1027 (w), 1000
(w), 841 (s), 790, 766 (s), 751 (m), 731 (m), 700 (m), 557 (s), 533
(s), 514 (m) cm−1.
G
dx.doi.org/10.1021/om400028n | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Synthesis of [(pq)2Ir(Nixantphos)][PF6] (5). Complex 5 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/v)
as eluent to give an orange-red solid. Yield: 0.068 g (52% based on Ir).
1H NMR (400 MHz, CDCl3): δ 9.45−9.49 (m, 1H), 8.11−8.15 (m,
1H), 7.66−7.70 (m, 1H), 7.49−7.58 (m, 3H), 6.95−7.40 (m, 16H),
6.54−6.84 (m, 14H), 6.38−6.42 (m, 2H), 6.22−6.26 (m, 2H), 5.96−
5.98 (m, 3H), 5.58−5.60 (m, 1H) ppm. 13C{1H} NMR (101 MHz,
CDCl3): δ 162.1, 148.7, 146.5, 139.7, 136.0, 133.6, 132.7, 131.7, 130.6,
130.2, 130.0, 129.2, 129.0, 128.9, 128.8, 128.3, 128.2, 128.0, 126.5,
126.1, 125.9, 123.1, 118.4, 118.4, ppm. 31P NMR (162 MHz, CDCl3):
δ −30.4, −143.3 (hept) ppm. MS (ESI) (CH2Cl2, 150 °C): m/z
1152.0 [Ir(pq)2(Nixantphos)]+. Anal. Calcd for C66H47F6IrN3OP3: C,
61.06; H, 3.62; N, 3.24. Found: C, 61.00; H, 4.02; N, 2.67. IR (KBr
pellet): 3338 (br), 3055 (m), 2927 (m), 2055 (m), 1610 (s), 1569 (s),
1518 (m), 1461 (s), 1438 (s), 1407 (s), 1295 (m), 1201 (m), 1117
(m), 1095 (m), 1028 (w), 999 (w), 872 (br), 728 (s), 693 (s), 557 (s),
518 (sh), 408 (w) cm−1.
135.1, 134.9, 134.8, 134.8, 132.8, 131.3, 130.4, 130.0, 129.8, 129.7,
129.6, 128.8, 128.7, 128.4, 126.0, 124.5, 124.4, 124.1, 123.1, 120.3
ppm. 31P NMR (162 MHz, CD2Cl2): δ −21.1, −143.4 (hept) ppm.
MS (ESI) (CH2Cl2, 150 °C): m/z 1052.2 [Ir(ppy)2(Nixantphos)]+.
Anal. Calcd for C58H43F6IrN3OP3: C, 58.15; H, 3.59; N, 3.51. Found:
C, 57.85; H, 3.81; N, 3.23. IR (KBr pellet): 3392 (m), 3056 (w), 1608
(m), 1586 (m), 1571 (m), 1482 (s), 1456 (s), 1435 (s), 1398 (s),
1321 (w), 1295 (w), 1269 (w), 1228 (w), 1203 (w), 1168 (w), 1089
(w), 1027 (w), 999 (w), 845 (vs), 792 (w), 744 (s), 732 (s), 697 (s),
630 (w), 558 (s), 523 (s), 506 (m), 462 (w), 435 (w), 415 (w) cm−1.
Synthesis of [(ppy)2Ir(Xantphos)][PF6] (9). Complex 9 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/v)
as eluent to give a yellowish green solid. Yield: 0.20 g (89% based on
Ir). 1H NMR (400 MHz, CDCl3): δ 8.61 (d, J = 5.7 Hz, 1H), 7.90 (q,
J = 7.8 Hz, 2H), 7.57 (d, J = 7.6 Hz, 1H), 7.29−7.26 (m, 2H), 7.12−
7.05 (m, 4H), 6.83 (d, J = 3.1 Hz, 4H), 6.76 (t, J = 6.7 Hz, 1H), 6.69
(t, J = 5.3 Hz, 1H), 6.60 (t, J = 7.4 Hz, 1H), 6.40 (t, J = 7.7 Hz, 2H),
6.24 (t, J = 7.4 Hz, 1H), 5.16 (d, J = 7.1 Hz, 1H), 1.49 (s, 3H) ppm.
13C {1H} NMR (101 MHz, CDCl3): δ 168.58, 154.64, 153.80, 153.34,
142.13, 139.31, 134.47, 133.02, 132.77, 131.47, 131.36, 131.02, 130.62,
130.29, 130.00, 129.93, 128.90, 128.42, 125.51, 124.58, 124.00, 123.27,
120.78, 118.89, 118.56, 118.23, 36.15, 29.02 ppm. 31P NMR (162
MHz, CD2Cl2): δ −20.2, −145.0 (hept) ppm. MS (ESI) (CH2Cl2, 150
°C): m/z 1079.1 [Ir(ppy)2(Xantphos)]+. Anal. Calcd for
C61H48F6IrN2OP3: C, 59.80; H, 3.92; N, 2.29. Found: C, 58.69; H,
4.41; N, 1.97. IR (KBr pellet): 3855 (w), 3650 (w), 3421 (w), 3050
(w), 2961 (w), 1608 (m), 1583 (m), 1562 (m), 1480 (s), 1437 (m),
1409 (s), 1320 (w), 1232, 1167 (w), 1118 (w), 1027 (w), 1000 (w),
841, 792 (m), 750 (s), 734 (s), 696 (m), 630 (w), 609 (w), 587 (w),
557 (m), 534 (w) cm−1.
Synthesis of [(pq)2Ir(Xantphos)][PF6] (6). Complex 6 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/
v) as eluent to give an orange-red solid. Yield: 0.127 g (46.9% based on
Ir). 1H NMR (400 MHz, CDCl3): δ 9.40 (d, J = 8.6 Hz, 1H), 8.22 (d,
J = 8.6 Hz, 1H), 7.86 (d, J = 7.5 Hz, 1H), 7.76 (d, J = 8.8 Hz, 1H),
7.61 (d, J = 7.8 Hz, 2H), 7.21−7.07 (m, 4H), 6.99 (t, J = 7.3 Hz, 1H),
6.74 (t, J = 7.3 Hz, 3H), 6.69−6.51 (m, 5H), 6.43 (t, J = 7.4 Hz, 2H),
6.25 (t, J = 7.3 Hz, 2H), 6.14 (t, J = 7.7 Hz, 1H), 5.92 (d, J = 7.1 Hz,
2H), 5.66 (d, J = 5.9 Hz, 1H), 2.02 (s, 3H) ppm. 13C{1H} NMR (101
MHz, CDCl3): δ 171.47, 156.85, 148.86, 146.59, 140.13, 135.34,
134.91, 133.56, 132.67, 131.90, 131.70, 130.38, 130.23, 129.58, 129.20,
128.59, 128.55, 128.14, 127.76, 127.19, 126.57, 126.15, 125.81, 123.33,
118.80, 37.32, 28.29 ppm. 31P NMR (162 MHz, CD2Cl2): δ −29.3,
−145.0 (hept) ppm. MS (ESI) (CH2Cl2, 150 °C): m/z 1179.1
[Ir(pq)2(Xantphos)]+. Anal. Calcd for C69H52F6IrN2OP3: C, 62.54; H,
3.93; N, 2.11. Found: C, 61.34; H, 3.85; N, 2.05 (corresponding to
[(pq)2Ir(Xantphos)][PF6]·0.3CH2Cl2). IR (KBr pellet): 3052 (m),
2963 (m), 2924 (m), 2858 (w), 2263 (w), 2025 (w), 1954 (w), 1819
(w), 1719 (w), 1685 (w), 1606 (s), 1578 (s), 1549 (s), 1517 (s), 1482
(m), 1465 (m), 1451 (m), 1438 (s), 1406 (s), 1364 (w), 1339 (m),
1291 (m), 1273 (w), 1241 (m), 1219 (s), 1197 (m), 1167 (m), 1148
(w), 1085 (m), 1038 (w), 1027 (m), 999 (m), 915 (m), 875 (s), 843
(s), 791 (s), 765 (s), 746 (s), 723 (s), 695 (s), 642 (m), 610 (w), 557
(s), 532 (m), 520 (s), 493 (m), 458 (s), 443 (w), 418 (w) cm−1.
Synthesis of [(ppy)2Ir(dppb)][PF6] (7). Complex 7 was purified
on a silica gel column using ethyl acetate/MeOH (30/1 v/v) as eluent
Synthesis of [(Fppy)2Ir(dppb)][PF6] (10). Complex 10 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/v)
as eluent to give a yellowish green solid. Yield: 0.044 g (36% based on
1
Ir). H NMR (400 MHz, CDCl3): δ 8.06−8.13 (m, 2H), 7.85−7.87
(m, 1H), 7.48−7.61 (m, 6H), 7.37−7.39 (m, 1H), 7.07−7.11 (m, 1H),
6.83−6.86 (m, 2H), 6.51−6.56 (m, 1H), 6.35−6.43 (m, 3H), 5.56−
5.59 (m, 1H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 164.6, 162.4,
153.3, 139.0, 137.8, 134.5, 134.3, 134.2, 132.4, 131.0, 130.9, 130.0,
129.9, 128.7, 128.7, 127.8, 124.3, 124.1, 123.7, 114.1, 113.9, 100.3
ppm. 31P NMR (162 MHz, CDCl3): δ 21.9, −143.8 (hept) ppm. 19F
NMR (282 MHz, CDCl3): δ 2.43 (d, JC−F = 713 Hz), −29.68 to
−29.74 (m), −31.70 to −31.72 (m), −77.97 (s) ppm. MS (ESI)
(CH2Cl2, 150 °C): m/z 1019.3 [Ir(fppy)2(dppb)]+. Anal. Calcd for
C52H36F10IrN2P3: C, 53.66; H, 3.10; N, 2.41. Found: C, 52.85; H, 2.97;
N, 2.37. IR (KBr pellet): 3855 (w), 3752 (w), 3650 (w), 3445 (w),
3136 (w), 3058 (w), 2924 (w), 2343 (w), 1631 (w), 1603 (s), 1578
(s), 1561 (m), 1481 (m), 1455 (w), 1434 (m), 1406 (m), 1295 (m),
1271 (w), 1252 (m), 1227 (w), 1191 (w), 1165 (m), 1109 (m), 1091
(m), 1040 (w), 991 (m), 844 (s), 783 (w), 740 (m), 753 (m), 702
(m), 668 (w), 617 (w), 569 (m), 558 (m), 541 (s), 532 (s) cm−1.
Synthesis of [(Fppy)2Ir(Nixantphos)][PF6] (11). Complex 11
was purified on silica gel column using ethyl acetate/MeOH (30/1 v/
v) as eluent to give a yellowish green solid. Yield: 0.23 g (89% based
1
to give a yellowish green solid. Yield: 0.13 g (57% based on Ir). H
NMR (400 MHz, CDCl3): δ 8.07−8.11 (m, 2H), 7.97−7.98 (m, 2H),
7.58−7.62 (m, 4H), 7.42−7.53 (m, 12H), 7.31−7.32 (m, 2H), 7.02−
7.06 (m, 2H), 6.96−7.00 (m, 2H), 6.89−6.93 (m, 2H), 6.76−6.79 (m,
4H), 6.27−6.35 (m, 6H), 6.14−6.16 (m, 2H), 5.29 (s, 1H) ppm.
13C{1H} NMR (101 MHz, CDCl3): δ 168.1, 158.3, 158.2, 157.4,
157.4, 152.9, 143.4, 141.2, 140.8, 140.4, 138.2, 137.5, 134.3, 134.3,
133.7, 132.0, 131.9, 130.9, 130.8, 130.7, 129.9, 129.7, 129.6, 129.1,
128.9, 128.7, 128.4, 125.3, 123.8, 123.2, 120.4 ppm. 31P NMR (162
MHz, CD2Cl2): δ 21.8, −143.7 (hept) ppm. MS (ESI) (CH2Cl2, 150
°C): m/z 947.2 [Ir(ppy)2(dppb)]+. Anal. Calcd for C52H40F6IrN2P3:
C, 57.19; H, 3.67; N, 2.57. Found: C, 54.78; H, 3.52; N, 2.39
(corresponding to 7·CH2Cl2). IR (KBr pellet): 3671 (w), 3444 (m),
3125 (m), 3053 (m), 3003 (m), 2342 (w), 1982 (w), 1891 (w), 1821
(w), 1610 (s), 1582 (s), 1567 (m), 1554 (m), 1481 (s), 1454 (m),
1482 (m), 1454 (m), 1435 (s), 1318 (m), 1306 (m), 1271 (m), 1229
(m), 1188 (m), 1167 (m), 1111 (s), 1090 (s), 1067 (m), 1060 (m),
1050 (w), 1027 (m), 1000 (m), 947 (w), 928 (w), 910 (w), 852 (s),
780 (s), 753 (s), 699 (s), 665 (s), 630, 557 (s), 530 (s), 516 (s) cm−1.
Synthesis of [(ppy)2Ir(Nixantphos)][PF6] (8). Complex 8 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/v)
as eluent to give a yellowish green solid. Yield: 0.137 g (56% based on
Ir). 1H NMR (400 MHz, CDCl3): δ 8.93 (s, 1H), 7.84 (br, 1H), 7.35−
7.42 (m, 1H), 7.23−7.26 (m, 6H), 7.14 (br, 2H), 6.97−7.05 (m, 3H),
6.78−6.85 (m, 5H), 6.58−6.62 (m, 1H), 6.41−6.45 (m, 2H), 6.25−
6.28 (m, 1H), 6.15 (s, 1H), 5.23−5.25 (m, 1H) ppm. 13C{1H} NMR
(101 MHz, CD2Cl2): δ 168.6, 155.7, 155.6, 155.5, 142.2, 140.2, 138.9,
1
on Ir). H NMR (400 MHz, CDCl3): δ 8.69 (d, J = 5.6 Hz, 1H),
8.29−8.32 (m, 1H), 7.98−8.02 (m, 1H), 7.64 (d, J = 7.5 Hz, 1H),
7.38−7.41 (m, 1H), 7.13−7.23 (m, 4H), 6.81−6.95 (m, 6H), 6.61−
6.68 (m, 1H), 6.44−6.48 (m, 2H), 6.10−6.16 (m, 1H), 4.56−4.58 (m,
1H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 165.0 (m), 162.2
(m), 159.8 (m), 157.7 (m), 156.7 (m), 154.8, 153.7, 140.5, 134.3,
133.2, 132.6, 131.3, 130.7, 130.6, 130.0, 129.5, 129.2, 129.1, 128.6,
126.5, 125.9, 124.7, 124.5, 113.1, 112.9, 99.7 ppm. 31P NMR (162
MHz, CDCl3): δ −23.8, −145.0 (hept) ppm. 19F NMR (282 MHz,
CDCl3): δ 2.39 (d, JC−F = 712 Hz), −27.89 (s), −32.31 to −32.35 (m)
ppm. MS (ESI) (CH2Cl2, 150 °C): m/z 1124.1 [Ir-
(fppy)2(Nixantphos)]+. Anal. Calcd for C58H39F10IrN3OP3: C, 54.85;
H, 3.07; N, 3.31. Found: C, 55.08; H, 3.33; N, 3.20. IR (KBr pellet):
3384 (m), 3141 (w), 3080 (m), 2925 (w), 2853 (w), 2613 (w), 2099
(w), 1969 (w), 1922 (w), 1846 (w), 1603 (s), 1577 (s), 1559 (s), 1522
(w), 1507 (w), 1480 (s), 1457 (s), 1434 (s), 1405 (s), 1297 (s), 1270
(m), 1254 (m), 1227 (m), 1207 (m), 1165 (s), 1110 (m), 1108 (s),
H
dx.doi.org/10.1021/om400028n | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1089 (m), 1040 (w), 1027 (w), 993 (s), 842 (s), 786 (s), 741 (s), 696
(s), 663 (w), 569 (m), 557 (s), 525 (s), 503 (m), 461 (w), 448 (w),
435 (w) cm−1.
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: andyhor@nus.edu.sg (T.S.A.H.); zhangw@imre.a-star.
edu.sg (W.-H.Z.); zpliu@fudan.edu.cn (Z.-P.L.); david.young@
ubd.edu.bn (D.J.Y.).
Synthesis of [(Fppy)2Ir(Xantphos)][PF6] (12). Complex 12 was
purified on a silica gel column using ethyl acetate/MeOH (30/1 v/v)
as eluent to give a yellowish green solid. Yield: 0.17 g (66% based on
1
Ir). H NMR (400 MHz, CDCl3): δ 8.68−8.69 (m, 1H), 8.30−8.32
Author Contributions
(m, 1H), 7.98−8.01 (m, 1H), 7.63−7.64 (m, 1H), 7.37−7.41 (m, 1H),
7.15−7.25 (m, 4H), 6.80−6.95 (m, 5H), 6.46−6.48 (m, 2H), 6.11−
6.16 (m, 1H), 4.56−4.58 (m, 1H), 1.50 (s, 2H) ppm. 13C {1H} NMR
(101 MHz, CDCl3): δ 164.87, 164.42, 162.12, 153.86, 153.50, 153.29,
148.12, 138.63, 136.28, 135.18, 134.42, 134.32, 134.22, 133.98, 133.74,
133.55, 132.89, 132.71, 132.48, 131.33, 130.42, 128.70, 128.52, 128.36,
128.25, 128.16, 128.00, 127.86, 127.11, 127.00, 126.71, 124.54, 124.38,
123.96, 123.72, 122.81, 122.69, 122.30, 121.82, 117.68, 117.49, 99.26,
97.01, 60.79, 58.60, 53.81, 34.78, 32.22, 30.09 ppm. 31P NMR (162
MHz, CD2Cl2): δ −20.1, −143.7 (hept) ppm. 19F NMR (282 MHz,
CDCl3): δ 2.36 (d, JC−F = 712 Hz), −27.81 to −27.87 (m), −32.28 to
−32.35 (m) ppm. MS (ESI) (CH2Cl2, 150 °C): m/z 1151.2
[Ir(fppy)2(Xantphos)]+. Anal. Calcd for C61H44F10IrN2OP3: C,
56.48; H, 3.40; N, 2.16. Found: C, 56.36; H, 3.70; N, 2.13. IR (KBr
pellet): 3855 (w), 3737 (w), 3650 (w), 3400 (m), 3065 (m), 2971 (
m), 2344 (w), 1971 (w), 1763 (w), 1602 (s), 1578 (s), 1480 (s), 1455
(m), 1434 (s), 1408 (s), 1366 (m), 1297 (m), 1270 (m), 1253 (s),
1197 (m), 1165 (m), 1119 (m), 1108, 1089 (m), 1040 (w), 1013 (w),
992 (s), 930 (w), 843 (s), 789 (m), 775 (m), 750 (s), 697 (s), 608
(w), 587 (w), 570 (m), 557 (m), 519 (s) cm−1.
#These authors contributed equally to this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by IMRE assured funding (10-
1C0212); D.J.Y. acknowledges funding from Universiti Brunei
Darussalam. We are grateful to the NUS and IMRE for support
as well as Dr. Jonathan Hobley (IMRE) and the reviewers for
their insightful discussion and comments.
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ASSOCIATED CONTENT
■
S
* Supporting Information
Tables and figures files giving detailed DFT results, crystallo-
graphic data for 6−8, 10, and 11, selected bond distances and
angles for 6−8, 10, and 11, X-ray structures of 8 and 10 with
1
labeling, and H, 13C, 31P, and 19F (10−12) NMR spectra for
1−12 and CIF files giving crystallographic data for 6−8, 10,
and 11. This material is available free of charge via the Internet
at http://pubs.acs.org.
I
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