Acceptor PCP pincer iridium chemistry: (CF3PCP) IrIII coordination properties

Article abstract of DOI:10.1021/om1008633

The syntheses of Ir(I) and Ir(III) complexes incorporating the electron-poor pincer ligand (1,3-C₆H₃(CH ₂P(CF₃)₂)₂) (^CF ₃PCP) are reported. Under mild conditions, the reaction of ^CF₃PCPH with [(cod)Ir(μ-Cl)]₂ in benzene gave polymeric [(cod)IrCl(μ-^CF₃PCPH)]_n, which was structurally characterized. Thermolysis of [(coe)₂Ir(μ- Cl)]₂ or [(cod)Ir(μ-Cl)]₂ with ^CF ₃PCPH in toluene at 120 °C resulted in metalation to give not the anticipated 16-electron (^CF₃PCP)Ir(H)Cl product but rather the coordinatively saturated ^CF₃PCPH-bridged dimer {(^CF₃PCP)Ir(H)Cl}₂(μ-^CF ₃PCPH). The bridging ^CF₃PCPH ligand is readily displaced to afford the monomeric products (^CF₃PCP)Ir(L) (H)Cl (L = CO, MeCN); the direct synthesis of (^CF₃PCP) Ir(L)(H)Cl (L = CO, MeCN, PhCN, C₂H₄, MeP(C ₂F₅)₂) was achieved by reacting [(coe) ₂Ir(μ-Cl)]₂ or [(cod)Ir(μ-Cl)]₂ with 2 equiv of ^CF₃PCPH in the presence of the corresponding trapping ligand. Chloride abstraction from (^CF₃PCP)Ir(CO) (H)Cl was examined: treatment with AgSbF₆ or Et₃Si ⁺B(C₆F₅)₄^- in the presence of 1 atm of CO in CH₂Cl₂ or 1,2-difluorobenzene cleanly afforded cis-(^CF₃PCP)Ir(CO)₂(H) ⁺, and the cis CO coordination geometry was confirmed by X-ray diffraction. Chloride abstraction in the presence of ethylene similarly gave (^CF₃PCP)Ir(CO)(C₂H₄)(H) ⁺, and abstraction with AgSbF₆ in the absence of trapping ligands afforded the Cl-bridged dimer {[(^CF₃PCP)Ir(CO)(H)] ₂(μ-Cl)}⁺, which was structurally characterized. Facile displacement of MeCN from (^CF₃PCP)Ir(MeCN)(H)Cl with PPh₃ was observed to give an 8:1 isomeric mixture of ( ^CF₃PCP)Ir(PPh₃)(H)Cl at-15 °C, with the major species having PPh₃ trans to the hydride.

Full text of DOI:10.1021/om1008633

Organometallics 2011, 30, 689–696 689
DOI: 10.1021/om1008633
III
Acceptor PCP Pincer Iridium Chemistry: (CF PCP)Ir
3
Coordination Properties
Jeramie J. Adams, Ade Lau, Navamoney Arulsamy, and Dean M. Roddick*
Department of Chemistry, Box 3838, University of Wyoming, Laramie, Wyoming 82071, United States
Received September 6, 2010
The syntheses of Ir(I) and Ir(III) complexes incorporating the electron-poor pincer ligand (1,3-
CF3
PCPH with
C6H3(CH2P(CF3)2)2) (CF PCP) are reported. Under mild conditions, the reaction of
3
[(cod)Ir(μ-Cl)]2 in benzene gave polymeric [(cod)IrCl(μ-CF PCPH)]n, which was structurally char-
3
CF3
acterized. Thermolysis of [(coe)2Ir(μ-Cl)]2 or [(cod)Ir(μ-Cl)]2 with
PCPH in toluene at 120 °C
resulted in metalation to give not the anticipated 16-electron (CF PCP)Ir(H)Cl product but rather the
3
CF3
coordinatively saturated
CF3
PCPH-bridged dimer {(CF3PCP)Ir(H)Cl}2(μ-CF3PCPH). The bridging
PCPH ligand is readily displaced to afford the monomeric products (CF3PCP)Ir(L)(H)Cl (L=CO,
MeCN); the direct synthesis of (CF PCP)Ir(L)(H)Cl (L=CO, MeCN, PhCN, C2H4, MeP(C2F5)2) was
3
achieved by reacting [(coe)2Ir(μ-Cl)]2 or [(cod)Ir(μ-Cl)]2 with 2 equiv of CF PCPH in the presence of
3
the corresponding trapping ligand. Chloride abstraction from (CF PCP)Ir(CO)(H)Cl was examined:
3
treatment with AgSbF6 or Et3SiþB(C6F5)4 in the presence of 1 atm of CO in CH2Cl2 or 1,2-
-
difluorobenzene cleanly afforded cis-(CF PCP)Ir(CO)2(H) , and the cis CO coordination geometry
þ
3
was confirmed by X-ray diþffraction. Chloride abstraction in the presence of ethylene similarly gave
CF3
(
PCP)Ir(CO)(C2H4)(H) , and abstraction with AgSbFþ6 in the absence of trapping ligands
afforded the Cl-bridged dimer {[(CF PCP)Ir(CO)(H)]2(μ-Cl)} , which was structurally characterized.
3
Facile displacement of MeCN from (CF PCP)Ir(MeCN)(H)Cl with PPh3 was observed to give an 8:1
3
isomeric mixture of (CF PCP)Ir(PPh3)(H)Cl at -15 °C, with the major species having PPh3 trans to
3
the hydride.
Introduction
(EP(R)2)2)IrI systems, which function as dehydrogenation
catalysts at elevated temperatures.2,3 The effects of aryl
backbone ring substitution, benzylic arm (1,3-C6H3(CH2P-
(R)2)2, PCP) versus resorcinol arm (1,3-C6H3(OP(R)2)2,
POCOP), and phosphine PR2 substituent effects on alkane
dehydrogenation activity have been examined.4 While aryl
substituents appear to induce relatively modest changes in
reactivity, less electron donating resorcinol pincers afford
more active dehydrogenation catalysts.5 Steric tuning effects
from phosphine alkyl substituent variation can be
significant.6 However, a broader range of phosphine substit-
uents, particularly those that are substantially more electron
withdrawing, has not received as much attention in iridium
pincer chemistry.
The trans-(R3P)2Ir(X)(L) motif has played an important
role in fundamental organometallic studies. Square-planar
Ir(I) systems typically follow established reaction pathways,
with the stereochemistry of oxidative addition by both polar
and nonpolar substrates being clearly delineated and well
understood.1 In recent years, the range of oxidative addition
substrates has been extended to nonpolar C-H and C-C
bonds and their addition to more reactive 14-electron frag-
ments, (R3P)2Ir(X). An important class of Ir(I) and Ir(III)
systems which impose a trans bis phosphine coordination
environment are terdentate “pincer” ((κ3P,C,P-1,3-C6H3-
(1) (a) Crabtree, R. H. The Organometallic Chemistry of the Transi-
tion Metals, 5th ed.; Wiley-Interscience: New York, 2005; Chapter 6. (b)
Johnson, C. E.; Eisenberg, R. J. Am. Chem. Soc. 1985, 107, 3148–3160. (c)
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Chem. Soc. 2002, 124, 10797–10809.
(4) (a) Morales-Morales, D. Iridium Complexes in Organic Synthesis;
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Morales, D. Iridium Complexes in Organic Synthesis; Wiley-VCH: 2009;
Chapter 12, pp 299-323.
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Goldman, A. S. Organometallics 2010, 29, 2702–2709. (c) Kundu, S.;
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5432–5444.
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B. C.; Scott, S. L. Chem. Commun. 2008, 253–255. (b) Goettker-
Schnetmann, I.; Brookhart, M. J. Am. Chem. Soc. 2004, 126, 9330–
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W.; Brookhart, M. Science (Washington, DC, U.S.) 2006, 312, 257–261.
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Angermund, K.; Kaska, W. C.; Fan, H.-J.; Hall, M. B. Angew. Chem.,
Int. Ed. 2001, 40, 3596–3600. (f) Ray, A.; Zhu, K.; Kissin, Y. V.; Cherian,
A. E.; Coates, G. W.; Goldman, A. S. Chem. Commun. 2005, 3388–3390.
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2274.
r
2011 American Chemical Society
Published on Web 02/03/2011
pubs.acs.org/Organometallics

690 Organometallics, Vol. 30, No. 4, 2011
Adams et al.
Scheme 1
metalation of PCPH with IrCl3(H2O)x,2e,11 [(cod)Ir(μ-Cl)]2,5
or [(coe)2Ir(μ-Cl)]2 at elevated temperatures to form (PCP)-
Figure 1. Molecular structure of [(cod)IrCl(μ-CF PCPH)]n (1)
3
Ir(H)Cl products.12 Addition of CF PCPH to [(cod)Ir(μ-Cl)]2
3
with 30% probability thermal ellipsoids. All hydrogens are
˚
omitted for clarity. Selected bond lengths (A) and angles
in benzene at 20 °C gave a single complex (eq 1), as judged by
(deg): Ir(1)-C(14) = 2.150(5), Ir(1)-C(13) = 2.150(5), C-
(13)-C(14) = 1.420(7), Ir(1)-C(17) = 2.225(5), Ir(1)-C(18) =
2.203(5), C(17)-C(18) = 1.386(8), Ir(1)-P(2A) = 2.3373(12),
Ir(1)-P(1) = 2.3684(13), Ir(1)-Cl(1) = 2.3989(12); P(2A)-Ir-
(1)-P(1)=103.28(4), P(2A)-Ir(1)-Cl(1)=87.15(5), P(1)-Ir-
(1)-Cl(1)=83.85(5).
1H, 31P, and 19F NMR, which was characterized by X-ray
diffraction as polymeric [(cod)IrCl(μ-CF PCPH)]n (1) (Figure 1).
3
We have recently reported the synthesis of a new PCP
CF3
ligand,
PCPH (1,3-C6H4(CH2P(CF3)2)2),7 with a phos-
phine-accepting ability that is significantly enhanced relative
to other benzylic PCP ligands, POCOP ligands incorporat-
ing a resorcinol aryl backbone,5,8,9 and pincer ligands with
electron-withdrawing phosphine pendant groups.9,10 Our
initial studies centered on the coordination chemistry of
Thermolysis of [(coe)2Ir(μ-Cl)]2 or [Ir(cod)(μ-Cl)]2 in the
presence of 1.5-3 equiv of PCPH in toluene at 120 °C
resulted in metalation to give not the anticipated 16-electron
CF3
CF3
(
PCP)Ir(H)Cl product but rather the coordinatively
3
CF3
saturated
PCPH-bridged dimer {(CF PCP)Ir(H)Cl}2-
platinum and explored the electrophilic nature of the
CF3
PCP)Ptþ d8 14-electron moiety. In this paper, we extend
(μ-CF PCPH) (2) as a white solid (Scheme 1). An analogous
PhPCPH-bridged dimeric product has been reported for
rhodium.13 The reaction of [Ir(cod)(μ-Cl)]2 with 1 equiv of
3
(
the development of acceptor PCP chemistry to iridium. In
contrast to donor PCP compounds, we observe a general
trend where the coordinatively saturated six-coordinate
CF3
PCPH at 155 °C for 24 h similarly did not give
Ir(III) products (CF PCP)Ir(L)(H)Cl are preferred over
3
CF3
(
PCP)Ir(H)Cl but a new product tentatively assigned as
3
(unobserved) five-coordinate (CF PCP)Ir(H)Cl products.
3
the asymmetric dimer [(CF PCP)Ir(H)(μ-Cl)2Ir(cod)] (3). Di-
meric species similar to 3 have been previously observed as
byproducts in the synthesis of (PCP)M(H)Cl (M = Rh, Ir)
Results and Discussion
donor systems.6c,13,14 The reaction between
PCPH and
IrCl3 3H2O is similar: refluxing in a 9/1 isopropyl alcohol/
CF3
Metalation of CF PCPH by Iridium(I) Precursors. Access to
3
3
(PCP)Ir derivatives has generally been accomplished by the
H2O solution mixture for 20 h generated 2 as the major
isolable species. Monitoring the reaction between CF PCPH
3
(7) Adams, J. J.; Lau, A.; Arulsamy, N.; Roddick, D. M. Inorg.
Chem. 2007, 46, 11328–11334.
and IrCl3 3H2O by NMR with different isopropyl alcohol/
3
H2O (1/0, 9/1, 8/2) and IrCl3 3H2O/CF PCPH ratios (1/1, 1/
3
(8) (a) Solano-Prado, M. A.; Estudiante-Negrete, F.; Morales-
Morales, D. Polyhedron 2010, 29, 592–600. (b) Rubio, M.; Suarez, A.;
del, R. D.; Galindo, A.; Alvarez, E.; Pizzano, A. Organometallics 2009,
28, 547–560. (c) Rubio, M.; Suarez, A.; del, R. D.; Galindo, A.; Alvarez,
E.; Pizzano, A. Dalton Trans. 2007, 407–409. (d) Salem, H.; Ben-David,
Y.; Shimon, L. J. W.; Milstein, D. Organometallics 2006, 25, 2292–2300.
(e) Bedford, R. B.; Betham, M.; Blake, M. E.; Coles, S. J.; Draper, S. M.;
Hursthouse, M. B.; Scully, P. N. Inorg. Chim. Acta 2006, 359, 1870–
1878. (f) Morales-Morales, D.; Grause, C.; Kasaoka, K.; Redon, R.;
Cramer, R. E.; Jensen, C. M. Inorg. Chim. Acta 2000, 300-302, 958–963.
(9) (a) Benito-Garagorri, D.; Kirchner, K. Acc. Chem. Res. 2008, 41,
201–213. (b) Bolliger, J. L. B.; Oliver, Frech; Christian, M. Angew.
Chem., Int. Ed. Engl. 2007, 46, 6514–6517. (c) Miyazaki, F.; Yamaguchi,
K.; Shibasaki, M. Tetrahedron Lett. 1999, 40, 7379–7383.
(10) (a) Kossoy, E.; Rybtchinski, B.; Diskin-Posner, Y.; Shimon,
L. J. W.; Leitus, G.; Milstein, D. Organometallics 2009, 28, 523–533.
(b) Gagliardo, M.; Havenith, R. W. A.; van Klink, G.; van Koten, G.
J. Organomet. Chem. 2006, 691, 4411–4418. (c) Kossoy, E.; Iron, M. A.;
Rybtchinski, B.; Ben-David, Y.; Shimon, L. J. W. ; Konstantinovski, L.;
Martin, J. M. L.; Milstein, D. Chemistry 2005, 11, 2319–2326.
(d) Gagliardo, M.; Chase, P. A.; Lutz, M.; Spek, A. L.; Hartl, F.;
Havenith, R. W. A.; van Klink, G. P. M.; van Koten, G. Organometallics
2005, 24, 4553–4557. (e) Chase, P. A.; Gagliardo, M.; Lutz, M.; Spek,
A. L.; van Klink, G. P. M.; van Koten, G. Organometallics 2005, 24,
2016–2019.
3
1.5) showed 2 to be the major product in all cases.
The 31P NMR spectrum of 2 shows a broadened multiplet
at 50.7 ppm and a pseudoheptet at 25.3 ppm in a 2:1 ratio,
CF3
assigned as the cyclometalated
CF3
PCP and bridging
PCPH ligands, respectively. The 1H NMR aromatic
region exhibits a singlet at 7.56 ppm due to the unmetalated
(11) Moulton, C. J.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1976,
1020–1024.
(12) (a) Kuklin, S. A.; Sheloumov, A. M.; Dolgushin, F. M.;
Ezernitskaya, M. G.; Peregudov, A. S.; Petrovskii, P. V.; Koridze,
A. A. Organometallics 2006, 25, 5466–5476. (b) Morales-Morales, D.;
Cramer, R. E.; Jensen, C. M. J. Organomet. Chem. 2002, 654, 44–50.
(c) Tuba, R. T.; Verona, D.; Long, V.; Hampel, F.; Gladysz, J. A. Dalton
Trans. 2005, 2275–2283. (d) Vigalok, A.; Milstein, D. Acc. Chem. Res.
2001, 34, 798–807. (e) Vigalok, A.; Rybtchinski, B.; Gozin, Y.; Koblenz,
T. S.; Ben-David, Y.; Rozenberg, H.; Milstein, D. J. Am. Chem. Soc.
2003, 125, 15692–15693.
(13) Yao, J.; Wong, W. T.; Jia, G. J. Organomet. Chem. 2000, 598,
228–234.
(14) Pelczar, E. M.; Emge, T. J.; Goldman, A. S. Acta Crystallogr.,
Sect. C: Cryst. Struct. Commun. 2007, C63, m323–m326.

Article
Organometallics, Vol. 30, No. 4, 2011 691
Scheme 2
CF3
bridging
maining aromatic protons for
PCPH proton. Overlapping resonances for re-
CF3
PCPH and the meta aro-
CF3
matic protons of the terdentate
PCP groups were
observed at 7.44 ppm. The para protons for the metalated
PCP ligands appear as a triplet at 7.20 ppm (3JHH =8
CF3
Hz). The benzylic protons of the metalated CF PCP groups
3
are diastereotopic and are assigned as two multiplets at
4.67 and 4.48 ppm, while the benzylic protons for the
bridging CF PCPH group appear as a doublet at δ 4.32. A
3
distinctive hydride resonance is observed at -18.91 ppm
(td, JPH = 16, 12 Hz), which confirms that the hydride
2
CF3
ligand in 2 is cis to two
CF3
PCPH phosphine.
The bridging
PCP phosphines and one
Figure 2. Molecular structure of (CF PCP)Ir(CO)(H)Cl (4) with
3
CF3
50% probability thermal ellipsoids. All hydrogen atoms (with
the exception of the hydride ligand) are omitted for clarity.
Selected bond distances (A) and angles (deg): Ir(1)-C(13) =
1.952(3), Ir(1)-C(1) = 2.103(2), Ir(1)-P(2) = 2.2489(6), Ir(1)-
P(1) = 2.2588(6), Ir(1)-Cl(1) = 2.4582(6), Ir(1)-H(1) = 1.54(4),
C(13)-O(1) = 1.118(4); C(13)-Ir(1)-C(1) = 179.30(11), C(1)-
Ir(1)-P(2) = 80.54(6), C(1)-Ir(1)-P(1) = 79.08(6), P(2)-Ir(1)-
P(1) = 158.65(2), C(13)-Ir(1)-Cl(1) = 92.39(9), C(13)-Ir(1)-
H(1) = 89.8(14), Cl(1)-Ir(1)-H(1) = 175.7(14).
PCPH ligand in complex 2 is readily
displaced: addition of 1 atm of CO to 2 or dissolution in
acetonitrile at 80 °C resulted in quantitative conversion to
˚
the monomeric products (CF PCP)Ir(L)(H)Cl (L = CO, 4;
3
L=MeCN, 5) with the release of 0.5 equiv of free CF PCPH.
3
CF3
The displacement of the bridging unmetalated
group by donor ligands suggested a direct synthesis of
(
PCPH
CF3
PCP)Ir(L)(H)Cl products: reaction of [(coe)2Ir(μ-Cl)]2
3
or [(cod)Ir(μ-Cl)]2 with 2 equiv of CF PCPH in the presence
of CO, MeCN, PhCN, C2H4, and MeP(C2F5)2 gave the
corresponding six-coordinate products 4-8 (Scheme 2).
The stereochemistry of compounds 5-7 was not deter-
mined by NMR data. X-ray data for 5, while suffering
from extensive disorder, nevertheless confirm the stereo-
chemistry shown in Scheme 2 with trans hydride and
chloride ligands. This disposition of ligands is consistent
with the structural determination of carbonyl complex 4
(Figure 2) and also the stereochemistry of the thermody-
namic Ph3P adduct isomer 13b (see later), and therefore
central L coordination is tentatively assumed for complexes
6 and 7. ν(CO) data for (RPCP)Ir(CO)(H)Cl provide a useful
a number of carbonyl complexes (PCP)Ir(CO)(H)Cl are
known,11,15-17 to our knowledge complexes 5-8 are the first
examples of neutral ligands other than CO coordinated to a
16-electron (RPCP)Ir(X)(Y)IrIII motif.18
Similar to the case for the bridging CF PCPH complex 2, the
3
31P NMR spectrum for 8 has a broadened metalated CF PCP
3
resonance at 48.3 ppm and a more resolved MeP(C2F5)2
resonance at 24.7 ppm, which integrate as 2:1. Analogously,
a diagnostic hydride resonance in the 1H NMR spectrum of 8
appears as a doublet of triplets (2JPH =16, 12 Hz) at -18.80
ppm, which confirms the cis disposition of both the pincer
and MeP(C2F5)2 ligands. Coordinated MeP(C2F5)2 has a
CF3 19F resonance at δ -76.1 and two distinct diastereotopic
electron density comparison with (CF PCP)Ir(CO)(H)Cl.
3
ν(CO) for R = iPr (1978 cm-1 15 and Ph (2018 cm-1 16
) are
)
CF2 ABX multiplets at δ -105.7 and -108.8.
substantially lower than the value of 2091 cm-1 observed for 4.
Further support for the reduced electron density of
CF3
(
In comparison to well-established (PCP)Ir(CO)(X)(Y) sys-
PCP)Ir(CO)(H)Cl (4) Chloride Abstraction Chemistry.
CF3
(
PCP)IrIII systems is provided by the 13C NMR spectrum
for complex 7: a coordinated ethylene resonance is observed at
tems, the only isoelectronic (PCP)Ir(CO)(X)(L)þ system
Pr
that we are aware of is (i PCP)Ir(CO)(H)(PPh3)þ.15 Ac-
cordingly, halide abstraction from complex 4 was examined
δ64.3, with a high 1JCH value of 166 Hz indicative of minimal π
back-bonding.
as a route to (CF PCP)Ir(CO)(H)(L)þ derivatives (Scheme 3).
3
CF3
In general, 1H NMR data for the metalated
PCP
Reaction of 4 with the chloride-abstracting reagents
-
framework are insensitive to the nature of L. Pincer 31P
resonances for 4-7 vary slightly (δ 56.1-58.8), whereas 8
gave an upfield shift at δ 48.3. The loss of symmetry across
the meridional pincer plane results in two unique 19F CF3
resonances for all six-coordinate adducts. Hydride re-
sonances range from δ -16.49 for 4 to δ -21.48 for 7. While
AgSbF6 and Et3SiþB(C6F5)4 at room temperature in the
presence of 1 atm of CO in CH2Cl2 and 1,2-difluoroben-
zene, respectively, resulted in quantitative conversion to the
dicarbonyl cation cis-(CF PCP)Ir(CO)2(H) (9a, SbF6-; 9b,
þ
3
B(C6F5)4-). A significant downfield shift in aromatic pro-
3
ton resonances to δ 7.51 (d, JHH = 8 Hz) and 7.41 ppm
(t, 3JHH=8 Hz) relative to 4 was observed and the diastereo-
topic benzylic resonances also shift downfield and collapse
to a multiplet at δ 4.60. The iridium hydride resonance
(15) Rybtchinski, B.; Ben-David, Y.; Milstein, D. Organometallics
1997, 16, 3786–3793.
(16) Li, R.-X.; Li, X.-J.; Wong, N.-B.; Tin, K.-C.; Zhou, Z.-Y.; Mak,
T. C. W. J. Mol. Catal. A: Chem. 2002, 178, 181–190.
(17) Mohammad, H. A. Y.; Grimm, J. C.; Eichele, K.; Mack, H.-G.;
Speiser, B.; Novak, F.; Quintanilla, M. G.; Kaska, W. C.; Mayer, H. A.
Organometallics 2002, 21, 5775–5784.
(18) Cyclooctene coordination to a pincer Ir(III) complex has been
reported.2b

692 Organometallics, Vol. 30, No. 4, 2011
Adams et al.
Scheme 3
Figure 4. Molecular structure of [(CF PCP)Ir(CO)(H)]2(μ-
3
þ
-
Figure 3. Molecular structure of cis-(CF PCP)Ir(CO)2(H) SbF6
(9a) with 50% probability thermal ellipsoids. All hydrogen atoms
(with the exception of the hydride ligand) and the SbF6 counterion
3
Cl)þSbF6 (11) with 30% probability thermal ellipsoids. All
hydrogen atoms (with the exception of the hydride ligands) and
the SbF6 counterion are omitted for clarity. Selected bond
-
˚
are omitted for clarity. Selected bond distances (A) and angles
˚
distances (A) and angles (deg): Ir(1)-C(13) = 1.958(4), Ir(1)-
(deg): Ir(1)-C(14) = 1.983(2), Ir(1)-C(13) = 2.0129(19), Ir-
(1)-C(1) = 2.1202(18), Ir(1)-P(2) = 2.2754(5), Ir(1)-P(1) =
2.2819(5), Ir(1)-H(1) = 1.48(3), C(13)-O(1) = 1.116(2), C-
(14)-O(2) = 1.120(3); C(14)-Ir(1)-C(1) = 169.29(8), C(1)-Ir-
(1)-P(2) = 80.49(5), C(1)-Ir(1)-P(1) = 80.77(5), P(2)-Ir(1)-
P(1) = 157.923(18), C(13)-Ir(1)-H(1) = 175.3(11).
C(1) = 2.095(3), Ir(1)-P(1) = 2.2595(9), Ir(1)-P(2) = 2.2734(9),
Ir(1)-Cl(1) = 2.5600(2), Ir(1)-H(1) = 1.27(5); C(13)-Ir(1)-
C(1) = 175.31(15), C(1)-Ir(1)-P(1) = 80.88(10), C(1)-Ir(1)-
P(2) = 81.37(10), P(1)-Ir(1)-P(2) = 160.88(3), C(13)-Ir(1)-
Cl(1) = 94.67(12), C(13)-Ir(1)-H(1) = 87.7(19), Cl(1)-Ir(1)-
H(1) = 176.0(18), Ir(1) -Cl(1)-Ir(1) = 169.39(7).
appears as a triplet at -10.74 ppm (2JHP = 14 Hz).
Inequivalent CF3 multiplets in the 19F NMR spectrum
appear at -57.3 and -58.9 ppm, consistent with a cis-
carbonyl coordination geometry, which was unambiguously
confirmed by X-ray diffraction (Figure 3). Carbonyl bands for
9 appear at 2184 and 2135 cm-1 and are substantially higher
in energy than ν(CO) values reported for (Ph3P)2Ir(CO)2-
(H)2þ (2085, 2050 cm-1).19
Halide abstraction from 4 with 0.5 equiv of AgSbF6 in
the absence of a trapping ligand led to the formation of
þ
the chloride-bridged dimer [(CF PCP)Ir(CO)(H)]2(μ-Cl)
3
-
SbF6 (11) (Figure 4). A related neutral chloride-bridged
dimer [(tBuMePCP)Ir(H)(Cl)]2(μ-Cl) has been reported.6c
CF3
-
(
PCP)Ir(CO)(η2-C2H4)(H)þSbF6 is moisture sensitive:
evaporating a solution of 10 in 1,2-difluorobenzene in
the presence of air gave colorless crystals which were
shown by X-ray diffraction to be the aquo complex
Halide abstraction with AgSbF6 in the presence of excess
C2H4 gave the corresponding ethylene adduct (CF PCP)Ir-
3
(
PCP)Ir(CO)(H)(H2O)þSbF6- (12) (Figure 5). Attempts
to obtain 12 on a preparative scale for complete character-
CF3
-
(CO)(H)(η2-C2H4)þSbF6 (10). 1H NMR spectra for 10
show overlapping benzylic and coordinated ethylene reso-
nances at δ 3.49, which integrate as 8:1 relative to the hydride
triplet at δ -11.79 (2JHP=12 Hz). A high-energy ν(CO) band
is observed at 2115 cm-1, and 13C data for η2-C2H4 (δ 76.9,
1JCH = 169 Hz) similarly reflects minimal π back-bonding.
ization were unsuccessful.
CF3
(
PCP)Ir(L)(H)Cl Ligand Substitution Studies. Ligand
exchange for Ir(III) pincer complexes has recently been exam-
ined in detail for the related silyl pincer system (BiPSi)-
Ir(H)(X)(L).20 While the kinetics of (CF PCP)Ir(L)(H)Cl ligand
3
ꢀ
(19) Malatesta, L.; Angoletta, M.; Caglio, G. J. Organomet. Chem.
1974, 73, 265–275.
(20) Sola, E.; Garcꢀa-Camprubꢀ, A.; Andres, J. L.; Martꢀn, M.; Plou, P.
J. Am. Chem. Soc. 2010, 132, 9111–9121.

Article
Organometallics, Vol. 30, No. 4, 2011 693
Isomer 13b, with PPh3 mutually cis to the hydride and aryl
backbone, exhibits a pseudoquartet hydride resonance
at -18.87 ppm (2JHP=16 Hz) due to similar cis phosphine
couplings.
CF3
Figure 5. Molecular structure of
(
PCP)Ir(CO)(H2O)-
(H)þSbF6- (12) with 30% probability ellipsoids. All hydrogen
atoms (with the exception of the hydride ligand) and the
˚
counterion are omitted for clarity. Selected bond distances (A)
Crystallographic Studies. Ir(III) pincer RPCP complexes
with strongly donating tert-butyl phosphine substituents are
the most common structurally characterized RPCP motif.14
Accordingly, the structural characterization of several
PCP Ir(III) systems were carried out for comparison.
Previous structurally characterized examples of six-coordi-
nate (PCP)Ir(CO)(X)(Y) compounds have variable CO site
and angles (deg): Ir(1)-C(13) = 1.962(4), Ir(1)-C(1) =
2.110(4), Ir(1)-O(1W) = 2.202(3), Ir(1)-P(1) = 2.2592(12),
Ir(1)-P(2) = 2.2722(11), Ir(1)-H(1) = 1.35(6), C(13)-O(1) =
1.120(5); C(13)-Ir(1)-O(1W) = 94.78(15), C(1)-Ir(1)-P(1) =
80.05(11), C(1)-Ir(1)-P(2) = 80.35(11), P(1)-Ir(1)-P(2) =
159.90(4), C(13)-Ir(1)-H(1) = 85(2), O(1W)-Ir(1)-H(1) =
179(3).
CF3
preferences, either trans or cis to the pincer Ir-C(aryl)
CF3
bond.14,21
(
PCP)Ir(CO)(H)(Y) compounds reported here
exchange and relative binding affinities have not been looked
at in any detail, some insight is afforded from the reactions
(4, 9a, 11, 12) all place CO trans to the pincer Ir-C(aryl)
bond and cis to the hydride ligand. In accord with prior
2
of (CF PCP)Ir(η -C2H4)(H)Cl with MeCN and also of
3
CF3
perfluoroalkylphosphine structural studies,22
(
PCP)Ir-
CF3
(
PCP)Ir(MeCN)(H)Cl (5) with Ph3P. Addition of 1 equiv
3
2
of MeCN to (CF PCP)Ir(η -C2H4)(H)Cl (7) at 20 °C resulted
in rapid equilibration within 10 min to form a 11/1 mixture of
5 and 7 (eq 2). Integration of 5 relative to 7 and the free ligand
resonances gave a Keq value of 9.3, corresponding to a
1.3 kcal mol-1 preference for MeCN binding relative to
ethylene. No transient kinetic isomer in the substitution of
7 with MeCN was observed at 20 °C. However, monitoring
the reaction of 7 with 0.7 equiv of MeCN in CD2Cl2 at -20 °C
revealed the initial appearance of a new hydride triplet
resonance (<5% intensity relative to 7) at δ -19.47,
which is assigned to kinetic isomer 5a with the MeCN
coordinated trans to the hydride ligand. After 10 min
at -20 °C a small amount of the thermodynamic isomer 5
was observed; at 0 °C resonances for 5 increased, and after
20 min the 7/5/5a ratio was 10/8/0.5. At 20 °C no 5a remained
after 1 h.
(CO)(H)Cl (4) (Figure 2) has significantly shorter Ir-P
bonds (2.2489(6) and 2.2588(6) A) than analogous donor
˚
phosphine complexes (tBuPCP)Ir(CO)(H)(X), where X =
23
˚
HNPh (Ir-P = 2.3422(6), 2.3338(5) A), X = CH2NO2
24
˚
(Ir-P = 2.3447(9), 2.3400(9) A), and X = CH3 (Ir-P =
2.3256(12), 2.3316(11) A).
14
˚
CF3
-
The complexes
(
PCP)Ir(CO)2(H)þSbF6
(9a),
þ
-
[(CF PCP)Ir(CO)(H)]2(μ-Cl) SbF6 (11), and (CF PCP)Ir-
(CO)(H2O)(H)þSbF6- (12) appear to be the first structurally
characterized cationic systems of the general form
(PCP)Ir(L)2(X)þ (Figures 3-5). Ir-P bond lengths of these
3
3
˚
complexes are slightly longer (0.01-0.02 A) than the Ir-P
bond lengths in 4 but are still significantly shorter than those
in neutral six-coordinate (tBuPCP)Ir(L)(X)X0 complexes
14,21b,25
˚
˚
(2.30-2.43 A range, 2.34 A average).
9a, the most
electron poor of these systems, has the longest Ir-P bonds
˚
(2.2754(5) and 2.2819(5) A) and a longer Ir-C(aryl) bond
(2.1202(12) A).
˚
(21) (a) Cartwright Sykes, A.; White, P.; Brookhart, M. Organome-
tallics 2006, 25, 1664–1675. (b) Ghosh, R.; Emge, T. J.; Krogh-Jespersen,
K.; Goldman, A. S. J. Am. Chem. Soc. 2008, 130, 11317–11327.
(22) (a) Ernst, M. F.; Roddick, D. M. Organometallics 1990, 9, 1586–
1594. (b) Schnabel, R. C.; Roddick, D. M. Inorg. Chem. 1993, 32, 1513–
1518. (c) Schnabel, R. C.; Roddick, D. M. Organometallics 1993, 12,
704–711. (d) Butikofer, J. L.; Hoerter, J. M.; Peters, R. G.; Roddick,
D. M. Organometallics 2004, 23, 400–408.
(23) Kanzelberger, M.; Zhang, X.; Emge, T. J.; Goldman, A. S.;
Zhao, J.; Incarvito, C.; Hartwig, J. F. J. Am. Chem. Soc. 2003, 125,
13644–13645.
(24) Zhang, X.; Emge, T. J.; Ghosh, R.; Krogh-Jespersen, K.; Goldman,
A. S. Organometallics 2006, 25, 1303–1309.
Generation of a kinetic isomer in the reaction between 5
and Ph3P was more definitive: displacement of MeCN from
5 with 1 equiv of PPh3 at -15 °C in 1,2-difluorobenzene
gave two isomers, 13a (PPh3 trans to hydride) and 13b (PPh3
trans to aryl backbone), in a 8/1 ratio (eq 3). Heating the
isomeric mixture to 80 °C for 10 min gave 100% conversion
to the thermodynamically favored isomer 13b. The stereo-
1
chemistry of the major species 13a was confirmed by H
(25) (a) Zhang, X.; Emge, T. J.; Ghosh, R.; Goldman, A. S. J. Am.
Chem. Soc. 2005, 127, 8250–8251. (b) Ghosh, R.; Zhang, X.; Achord, P.;
Emge, T. J.; Krogh-Jespersen, K.; Goldman, A. S. J. Am. Chem. Soc.
2007, 129, 853–866.
NMR spectra, which show a diagnostic hydride doublet of
triplets at -11.23 ppm (2JHP =129 Hz, 17 Hz) with a 2JPH
value typical of a trans hydride phosphine disposition.

694 Organometallics, Vol. 30, No. 4, 2011
Adams et al.
The asymmetric unit of 12 consists of a well-ordered
-
NMR experiments carried out in 1,2-difluorobenzene were
referenced to acetone-d6 capillaries. 31P spectra were referenced
to an 85% H3PO4 external standard. 19F spectra were referenced
to CF3CO2CH2CH3 (δ -75.32) and CF3C6H5 external stan-
CF3
(
PCP)Ir(CO)(H)(H2O)þ cation and SbF6 anion with
trans hydride and aquo ligands. The Ir-O bond length is
2.202(3) A, which, despite the higher metal coordination
˚
dards. IrCl3 xH2O was purchased from Pressure Chemical
3
number and greater trans influence of the hydride ligand, is
slightly shorter than the Ir-O bond in (tBuPCP)Ir(Me)-
Co.; all other reagents were purchased from Aldrich and were
used without further purification. AgSbF6 was dried under
þ
(H2O) (2.223(2) A)21b but is between the Ir-O bond lengths
˚
vacuum at 100 °C for 24 h prior to use. 1,3-C6H4(CH2P-
-
26
reported for Ir(H)2(THF)(PPh3)2(H2O)þSbF6 (2.258(9) A)
˚
(CF3)2)2,7 MeP(C2F5)2,
[(cod)Ir(μ-Cl)]2 and [(coe)2Ir
were prepared following
29
and trans,mer-IrCl2(H2O)(PMe2Ph)3þClO4 (2.189(6) A).
-
27
˚
- 31
(μ-Cl)]2,30 and Et3SiþB(C6F5)4
published procedures.
The molecular structure of [(cod)IrCl(μ-CF PCPH)]n (1)
(Figure 1) provides a model for how the Ir(cod)(Cl) moiety
initially interacts with PCPH ligands prior to metalation.
3
[(cod)IrCl(μ-CF PCPH)]n (1). Twenty milliliters of toluene
was added to a flask containing [Ir(cod)μ-Cl]2 (0.150 g, 0.223
3
mmol) and CF PCPH (125 uL, 0.197 g, 0.447 mmol). After it was
3
Unmetalated CF PCPH has significantly longer Ir-P bonds
3
than metalated CF PCP complexes (a 0.08-0.10 A difference
3
stirred for 10 min, the orange solution began to turn pale yellow
and formation of the pale yellow solid product was observed.
After 48 h the resulting product was collected via filtration and
dried under vacuum (0.180 g, 52% yield). Crystals suitable for
single-crystal X-ray diffraction were grown by the slow diffusion
of hexanes into a saturated solution of 1 in C6D6. Anal. Calcd
for C20H20P2F12ClIr: C, 30.88; H, 2.59. Found: C, 31.01; H,
˚
between 1 and 9a). A variety of (cod)IrCl(PR3)2 complexes
have been reported,28 but only the (cod)IrCl(PEt3)2 deriva-
tive has been structurally characterized.28a The Ir-P and
Ir-C(cod) bond lengths in 1 and (cod)IrCl(PEt3)2 are simi-
˚
lar, but the Ir-Cl bond in 1 is ∼0.03 A shorter.
1
3.06. H NMR (C6D6, 400.13 MHz, 20 °C): δ 7.56 (br s, 1H;
Summary
C6H4(CH2P(CF3)2)2), 7.34 (br s, 2H; C6H4(CH2P(CF3)2)2),
7.11-6.82 (m, 1H; C6H4(CH2P(CF3)2)2), 5.78 (br s, 4H; vinylic
cod), 3.73 (br s, 4H; C6H4(CH2P(CF3)2)2), 3.41 (br s, 4H;
vinylic cod), 1.82 (m, 8H; aliphatic cod), 1.43 (m, 8H; aliphatic).
31P{1H} NMR (C6D6, 161.97 MHz, 20 °C): δ 38.5 (br m). 19F
CF3
PCPH undergoes facile metalation reactions with com-
mon iridium starting materials. IR data for carbonyl deri-
vatives and 13C NMR data for ethylene complexes clearly
reflect the electron-poor nature of PCP Ir(III) metal centers
incorporating this acceptor ligand. Six-coordinate Ir(III)
pincer systems are quite common, particularly (PCP)Ir-
(CO)(X)(Y) derivatives, where CO is commonly added to
trap unsaturated (PCP)Ir(X)(Y) products or intermedi-
3
NMR (C6D6, 376.50 MHz, 20 °C): δ -52.6 (d, JFP = 64
Hz; PCF3).
{(CF PCP)Ir(H)Cl}2( μ- PCPH) (2). IrCl3 3H2O (0.300 g,
CF3
3
3
0.852 mmol) and CF PCPH (263 μL, 0.414 g, 0.937 mmol) were
3
dissolved in 30 mL of 1/9 H2O/isopropyl alcohol. The reaction
mixture was refluxed for 20 h, during which time the solution
color faded from dark olive green to pale yellow. Cooling to
room temperature and reducing the volume to 10 mL produced
a white precipitate; stirring an additional 16 h and filtering
afforded elementally pure product (0.315 g, 57% yield). Anal.
Calcd for C36H24P6F36Cl2Ir2: C, 24.24; H, 1.36. Found: C,
ates.14,21,23,24,25b In contrast to donor pincer analogues,
CF3
(
PCP)IrIII systems have a greater preference for binding
a sixth ligand in order to achieve an 18-electron d6 cþonfig-
uration. The cationic products (CF PCP)Ir(CO)2(H) and
3
CF3
(
PCP)Ir(CO)(η2-C2H4)(H)þ have no direct parallel in
donor pincer chemistry and are the conjugate acids of five-
1
24.57; H, 1.20. H NMR (acetone-d6, 400.13 MHz, 20 °C): δ
7.56 (s, 1H; μ-CF PCPH), 7.44 (m, 7H; overlapping μ-C6H4-
3
coordinate Ir(I) complexes (CF PCP)Ir(CO)2 and ( PCP)-
CF3
3
3
(CH2P(CF3)2)2 and m-C6H3(CH2P(CF3)2)2), 7.20 (t, JHH = 8
Ir(CO)(η2-C2H4). In the following paper we shall present the
synthesis, structure, and reactivity properties of four- and
Hz, 2H; p-C6H3(CH2P(CF3)2)2), 4.67 (m, 4H; C6H3(CH2P-
(CF3)2)2), 4.48 (m, 4H; C6H3(CH2P(CF3)2)2), 4.32 (d, 2JHP=7
Hz, 4H; μ-C6H4(CH2P(CF3)2)2), -18.91 (td, 2JPH =16, 12 Hz,
2H; IrH). 31P{1H} NMR (C6D6, 161.97 MHz, 20 °C): δ 50.7 (m,
4P; C6H3(CH2P(CF3)2)2), 25.3 (ps heptet, 2JFP=68 Hz, 2P; μ-
C6H4(CH2P(CF3)2)2). 19F NMR (C6D6, 376.50 MHz, 20 °C):
δ -53.7 (m, 12F; C6H3(CH2P(CF3)2)2), -55.5 (d, 2JFP=68 Hz,
12F; μ-(C6H4(CH2P(CF3)2)2), -58.0 (m, 12F; C6H3(CH2P-
(CF3)2)2).
five-coordinate (CF PCP)Ir derivatives which are derived
I
3
from (CF PCP)IrIII six-coordinate precursors.
3
Experimental Section
General Procedures. All manipulations were conducted under
N2 or vacuum using high-vacuum-line and glovebox techniques
unless otherwise noted. All ambient-pressure chemistry was
carried out under a pressure of approximately 590 Torr
(elevation ∼2195 m). All solvents were dried using standard
procedures and stored under vacuum. Aprotic deuterated sol-
vents used in NMR experiments were dried over activated
[(CF PCP)Ir(H)( μ-Cl)2Ir(cod)] (3). An NMR tube was
3
charged with ca. 17 mg of [(cod)Ir(μ-Cl)]2 (0.025 mmol),
CF3
PCPH (7 μL, 0.012 g, 0.027 mmol), and 0.5 mL of toluene-
d8. After the mixture was warmed to 155 °C for 24 h, the single
product 3 was formed, as judged by NMR. 1H NMR (toluene-
3
˚
3 A molecular sieves. Elemental analyses were performed by
d8, 400.13 MHz, 20 °C): δ 6.66 (t, JHH = 8 Hz, 1H; p-C6H3-
(CH2P(CF3)2)2), 6.50 (d, JHH = 8 Hz, 2H; m-C6H3(CH2P-
3
Desert Analytics. Infrared spectra were obtained on a Bomem
MB100 FTIR instrument. NMR spectra were obtained with a
Bruker DRX-400 instrument using 5 mm NMR tubes fitted with
Teflon valves (Chemglass CG-512 or New Era CAV-VBP).
2
(CF3)2)2), 3.90 (dm, JPH = 14 Hz, 2H; C6H3(CH2P(CF3)2)2),
2
3.36 (dm, JPH = 18, 2H; C6H3(CH2P(CF3)2)2), 2.08 (m, 2H;
vinylic cod), 2.01 (m, 4H; aliphatic cod), 1.05 (m, 4H; aliphatic
2
cod), -21.82 (t, JHP = 16.9 Hz, 1H; IrH). 31P{1H} NMR
(toluene-d8, 161.97 MHz, 20 °C): δ 55.1 (m). 19F NMR
(toluene-d8, 376.50 MHz, 20 °C): δ -54.0 (m, 6F; PCF3), -60.5
(m, 6F; PCF3).
(26) Luo, X. L.; Schulte, G. K.; Crabtree, R. H. Inorg. Chem. 1990,
29, 682–686.
(27) Deeming, A. J.; P., G. P.; Dawes, H. M.; Hursthouse, M. B.
J. Chem. Soc., Dalton Trans. 1986, 2545–2549.
(28) (a) Brym, M.; Jones, C. Transition Met. Chem. (Dordrecht,
Neth.) 2003, 28, 595–599. (b) Burk, M. J.; Crabtree, R. H. Inorg. Chem.
1986, 25, 931–932. (c) Crabtree, R. H.; Quirk, J. M.; Fillebeen-Khan, T.;
Morris, G. E. J. Organomet. Chem. 1979, 181, 203–212. (d) Denise, B.;
Pannetier, G. J. Organomet. Chem. 1978, 148, 155–164. (e) Haines,
L. M.; Singleton, E. J. Chem. Soc., Dalton Trans. 1972, 1891–1896.
(29) Peters, R. G.; Bennett, B. L.; Schnabel, R. C.; Roddick, D. M.
Inorg. Chem. 1997, 36, 5962–5965.
(30) Wilkinson, G. Inorg. Synth. 1972, 13, 126–131.
(31) Lambert, J. B.; Zhang, S.; Ciro, S. M. Organometallics 1994, 13,
2430–2443.

Article
Organometallics, Vol. 30, No. 4, 2011 695
CF3
(
mmol),
PCP)Ir(CO)(H)Cl (4). [(coe)2Ir(μ-Cl)]2 (0.600 g, 0.670
and dried under vacuum (0.323 g, 69% yield). Anal. Calcd
for C14H12P2F12ClIr: C, 24.10; H, 1.73. Found: C, 24.38; H,
CF3
PCPH (368 μL, 0.580 g, 1.338 mmol), and 10 mL
1
3
of toluene were combined in a medium-walled glass reaction
tube fitted with a Teflon valve. One atmosphere of CO was
introduced, and the reaction mixture was heated to 115 °C for
4 h. The solution was cooled to room temperature and trans-
ferred to a filtration assembly. Volatiles were removed, and the
residue was redissolved in 10 mL of dichloromethane. Addition
of 20 mL of CH3OH and concentration to ca. 7 mL yielded a
white precipitate, which was collected and dried under vacuum
(0.622 g, 67% yield). Crystals suitable for single-crystal X-ray
diffraction were grown by slow evaporation from a toluene
solution. Anal. Calcd for C13H11P2F12OClIr: C, 22.35; H, 1.16.
Found: C, 22.53; H, 1.16. 1H NMR (C6D6, 400.13 MHz, 20 °C):
1.43. H NMR (C6D6, 400.13 MHz, 20 °C): δ 6.82 (t, JHH =
3
8 Hz, 1H; p-C6H3(CH2P(CF3)2)2), 6.72 (d, JHH = 8 Hz, 2H;
m-C6H3(CH2P(CF3)2)2), 3.86 (s, 4H; C2H4), 3.74 (dt, 2JHH=17
Hz, 2JPH=5 Hz, 2H; C6H3(CH2P(CF3)2)2), 3.12 (dt, 2JH2H=17
2
Hz, JPH =6 Hz, 2H; C6H3(CH2P(CF3)2)2), -21.48 (t, JHP
=
14.0 Hz, 1H; IrH). 31P{1H} NMR (C6D6, 161.97 MHz, 20 °C): δ
58.8 (m). 13C NMR (C6D6, 100.61 MHz, 20 °C): δ 143.3 (s; CAr
-
CH2P(CF3)2), 139.9 (t, 2JCP=9 Hz; CAr-Ir), 125.5 (d, 1JCH=162
Hz; p-C6H3(CH2P(CF3)2), 123.5 (dm, 1JCH=158 Hz; m-C6H3-
(CH2P(CF3)2), 64.3 (t, JCH = 166 Hz; Ir(C2H4)), 35.9 (tm,
1
1JCH =136 Hz; CH2P(CF3)2). 19F NMR (C6D6, 376.50 MHz,
20 °C): δ -54.8 (m, 6F; PCF3), -60.9 (m, 6F; PCF3).
3
CF3
δ 6.83 (t, JHH = 8 Hz, 1H; p-C6H3(CH2P(CF3)2)2), 6.65 (d,
(
0.335 mmol),
PCP)Ir(MeP(C2F5)2)(H)Cl (8). [(coe)2Ir(μ-Cl)]2 (0.300 g,
3JHH =8 Hz, 2H; m-C6H3(CH2P(CF3)2)2), 3.71 (dt, 2JHH =18
Hz, 2JPH=5 Hz, 2H; C6H3(CH2P(CF3)2)2), 3.09 (dt, 2JHH=18
PCPH (188 μL, 0.296 g, 0.669 mmol), and
CF3
MeP(C2F5)2 (242 μL, 0.380 g, 1.338 mmol) were dissolved in 20
mL of toluene, and the mixture was refluxed for 3 h, during
which time the color changed from orange-red to yellow. The
reaction mixture was cooled, and a small amount of solid was
filtered off. The volatiles were removed, 30 mL of hexanes was
added, and the residue was triturated to give a white solid
suspension in a yellow solution. White 8 was collected by
filtration and dried (0.450 g, 70% yield). Anal. Calcd for
C17H11P3F22ClIr: C, 21.41; H, 1.16. Found: C, 21.78; H, 1.17.
1H NMR (C6D6, 400.13 MHz, 20 °C): δ 6.84 (t, 3JHH=7 Hz, 1H;
2
2
Hz, JPH =6 Hz, 2H; C6H3(CH2P(CF3)2)2), -16.49 (t, JHP
=
14.4 Hz, 1H; IrH). 31P{1H} NMR (C6D6, 161.97 MHz, 20 °C): δ
56.7 (m). 19F NMR (C6D6, 376.50 MHz, 20 °C): δ -54.4 (m, 6F;
PCF3), -61.4(m, 6F;PCF3). IR(CH2Cl2, cm-1):ν(CO) 2091 cm-1
.
CF3
(
PCP)Ir(MeCN)(H)Cl (5). [(coe)2Ir(μ-Cl)]2 (0.350 g, 0.390
mmol) and CF PCPH (225 μL, 0.354 g, 0.801 mmol) were added
to a medium-walled storage tube fitted with a Teflon valve and
dissolved in 5 mL of MeCN. The reaction mixture was warmed
to 135 °C for 1 h with periodic agitation, cooled to room tem-
perature, and transferred into a round-bottom flask. The vola-
tiles were removed to give a white solid, and 20 mL of hexanes
was added. The white product was triturated, and the elemen-
tally pure 5 was collected by filtration (0.426 g, 77% yield). Anal.
Calcd for C14H11P2F12NClIr: C, 23.63; H, 1.56; N, 1.97. Found:
C, 23.86; H, 1.52; N, 1.88. 1H NMR (C6D6, 400.13 MHz, 20 °C):
3
3
m-C6H3(CH2P(CF3)2)2), 6.68 (d, JHH = 7 Hz, 2H; p-C6H3-
2
(CH2P(CF3)2)2), 4.03 (br dt, JHH = 16 Hz, 2H; C6H3(CH2P-
(CF3)2)2), 3.15 (br dt, 2JHH=16 Hz, 2H; C6H3(CH2P(CF3)2)2),
2.17 (d, 2JHP=8 Hz, 3H; (CH3)P(CF2CF3)2), -18.80 (td, 2JPH
=
16.0, 12.0 Hz, 1H; IrH). 31P{1H} NMR (C6D6, 161.97 MHz,
20 °C): δ 48.3 (m, 2P; P(CF3)2), 24.7 (m, 1P; (CH3)P(CF2CF3)2).
19F NMR (C6D6, 376.50 MHz, 20 °C): δ -52.7 (br m, 6F;
PCF3), -56.8 (br m, 6F; PCF3), -76.1 (s, 6F; (CH3)P-
3
δ 6.80 (t, JHH = 8 Hz, 1H; p-C6H3(CH2P(CF3)2)2), 6.68 (d,
3JHH =8 Hz, 2H; m-C6H3(CH2P(CF3)2)2), 3.76 (dt, 2JHH =17
Hz, 2JPH=7 Hz, 2H; C6H3(CH2P(CF3)2)2), 3.16 (dt, 2JHH=18
2
(CF2CF3)2), ABX δA -105.7 (2JFF =367 Hz, JF P =94 Hz,
A
A
2
2F; (CH3)P(CF2CF3)2), δB -108.8 (2JFF =316 Hz, 2JF P=71.5
Hz, 2F; (CH3)P(CF2CF3)2).
Hz, JPH =5 Hz, 2H; C6H3(CH2P(CF3)2)2), 0.50 (s, 3H; CH3-
B
B
CN), -18.15 (t, 2JHP =16.0 Hz, 1H; IrH). 31P{1H} NMR (C6D6,
161.97 MHz, 20 °C): δ 56.1 (m). 19F NMR (C6D6, 376.50 MHz,
20 °C): δ-53.3(m,6F;PCF3),-60.2 (m, 6F; PCF3).Partial spectro-
scopic data for 5a: 1H NMR (CD2Cl2, 400.13 MHz, 0 °C) δ 2.30 (s,
3H; CH3CN), -19.47 (t, 2JHP=17.0 Hz, 1H; IrH); 31P{1H} NMR
(CD2Cl2, 161.97 MHz, 0 °C) δ 51.8 (m); 19F NMR (CD2Cl2, 376.50
CF3
(
PCP)Ir(CO)2(H)þSbF6- (9a). Complex 4 (0.200 g, 0.286
mmol) and AgSbF6 (0.098 g, 0.286 mmol) were dissolved in 15
mL of CH2Cl2, and 1 atm of CO was introduced. The reaction
mixture was stirred for 4 h, and AgCl precipitation was ob-
served. The AgCl was removed by filtration, ca. 30 mL of
hexanes was added to the filtrate, and the volume was reduced
by half. The resulting precipitate 9a was collected by filtration
(0.186 g, 70% yield). Crystals suitable for X-ray diffraction were
grown by slow evaporation from a methylene chloride solution.
The complex is stable indefinitely at -25 °C in an inert atmo-
sphere glovebox but decomposes into an insoluble gray solid
after 1 month at ambient temperature under N2. Anal. Calcd for
C14H8O2P2F18SbIr: C, 18.16; H, 0.87. Found: C, 17.84; H, 0.93.
1H NMR (CD2Cl2, 400.13 MHz, 20 °C): δ 7.51 (d, 3JHH=8 Hz,
2H; m-C6H3(CH2P(CF3)2)2), 7.41 (t, 3JHH=8 Hz, 1H; p-C6H3-
(CH2P(CF3)2)2), 4.60 (m, 4H; C6H3(CH2P(CF3)2)2), -10.74 (t,
2JHP=14.0 Hz, 1H; IrH). 31P{1H} NMR (CD2Cl2, 161.97 MHz,
20 °C): δ 54.3 (m). 19F NMR (CD2Cl2, 376.50 MHz, 20 °C):
δ -57.3 (m, 6F; PCF3), -58.9 (m, 6F; PCF3). IR: ν(CO) 2184,
MHz, 0 °C) δ -57.6 (m, 6F; PCF3), -61.3 (m, 6F; PCF3).
CF3
(
mmol) and
PCP)Ir(PhCN)(H)Cl (6). [(coe)2Ir(μ-Cl)]2 (0.300 g, 0.335
CF3
PCPH (188 μL, 0.296 g, 0.670 mmol) were
dissolved in 10 mL of PhCN. The reaction mixture was refluxed
for 15 min and then cooled. The volatiles were removed, giving a
yellow-brown product of ∼95% purity. The crude product was
dissolved in 15 mL of dichloromethane and the solution was
cooled to -78 °C, precipitating a white solid, which was
collected by cold filtration and dried (0.240 g, 50% yield). Anal.
Calcd for C19H13P2F12NClIr: C, 29.53; H, 1.70; N, 1.81. Found:
C, 29.46; H, 1.64; N, 1.64. 1H NMR (C6D6, 400.13 MHz, 20 °C):
δ 6.58 (d, 3JHH=8 Hz, 2H; o-C6H5CN) 6.82 (t, 3JHH=8 Hz, 1H;
p-C6H3(CH2P(CF3)2)2), 6.74 (m, 1H; p-C6H5CN partially over-
lapping with m-C6H3(CH2P(CF3)2)2), 6.70 (d, 2H, 3JHH=8 Hz;
3
m-C6H3(CH2P(CF3)2)2), 6.54 (ps t, 2H, JHH = 8 Hz; p-
C6H5CN), 3.80 (br dt, 2JHH=18 Hz, 2H; C6H3(CH2P(CF3)2)2),
2135 cm-1
.
(
CF3
-
PCP)Ir(CO)2(H)þB(C6F5)4 (9b). An NMR tube was
2
2
3.19 (dt, JHH = 18 Hz, JPH = 6 Hz, 2H; C6H3(CH2P-
(CF3)2)2), -17.79 (t, 2JHP=16.0 Hz, 1H; IrH). 31P{1H} NMR
(C6D6, 161.97 MHz, 20 °C): δ 56.6 (m). 19F NMR (C6D6, 376.50
charged with a ca. 15 mg sample of 4 (0.021 mmol), Et3Siþ-
B(C6F5)4 (0.018 g, 0.022 mmol), and 0.5 mL of 1,2-difluor-
-
obenzene. One atmosphere of CO was introduced, and the
reaction mixture was agitated at room temperature for 20 min.
The volatiles were removed under vacuum, and the residue was
taken up in CD2Cl2. 1H, 19F, and 31P NMR were identical with
those for 9a, except for the presence of the B(C6F5)4 counterion.
MHz, 20 °C): δ -52.9 (m, 6F; PCF3), -59.8 (m, 6F; PCF3).
CF3
(
PCP)Ir(η2-C2H4)(H)Cl (7). [(coe)2Ir(μ-Cl)]2 (0.300 g,
0.335 mmol) and CF PCPH (188 μL, 0.296 g, 0.669 mmol) were
dissolved in 20 mL of toluene. One atmosphere of C2H4 was
introduced, and the reaction mixture was refluxed for 3 h. The
reaction mixture was cooled, and the volatiles were removed to
give a pale yellow solid. Thirty milliliters of hexanes was added,
and the solid was triturated to give a white suspension in a yellow
solution. The elementally pure white 7 was collected by filtration
3
CF3
(
-
PCP)Ir(CO)(H)(η2-C2H4)þSbF6 (10). Complex
4
(0.213 g, 0.308 mmol) and AgSbF6 (0.105 g, 0.207 mmol) were dis-
solved in 25 mL of dichloromethane, 1 atm of C2H4 was
introduced, and the reaction mixture was stirred for 3 h at
ambient temperature. The AgCl precipitate was filtered away

696 Organometallics, Vol. 30, No. 4, 2011
Adams et al.
from the colorless solution, and the solution was reduced to ca.
10 mL and cooled to -78 °C to give 10 as a white precipitate
(0.158 g, 55% yield). Anal. Calcd for C15H12OP2F18SbIr: C,
19.44; H, 1.31. Found: C, 19.44; H, 1.22. 1H NMR (CD2Cl2,
complete conversion to isomer 13b, as judged by NMR. Spectro-
scopic data for 13b: 1H NMR (C6D6, 400.13 MHz, 20 °C) δ 8.00
(m, 6H; PPh3), 7.06 (m, 6H; PPh3), 6.97 (m, 3H; PPh3), 6.89 (t,
3JHH=8 Hz, 1H; p-C6H3(CH2P(CF3)2)2), 6.79 (d, 3JHH=8 Hz,
3
2
400.13 MHz, 20 °C): δ 7.41 (d, JHH = 8 Hz, 2H; m-C6H3-
(CH2P(CF3)2)2), 7.31(t, JHH = 8 Hz, 1H; p-C6H3(CH2P-
(CF3)2)2), 4.51 (m, 8H; overlapping C6H3(CH2P(CF3)2)2
2H; m-C6H3(CH2P(CF3)2)2), 4.15 (br dt, JHH = 16 Hz, 2H;
3
2
C6H3(CH2P(CF3)2)2), 3.24 (br dt, JHH = 16 Hz, 2H; C6H3-
(CH2P(CF3)2)2), -18.86 (dt, 2JHP=17.0 Hz, 2JHP=12.0 Hz, 1H;
IrH); 31P{H} NMR (C6D6, 161.97 MHz, 20 °C) δ 48.5 (m, 2P;
C6H3(CH2P(CF3)2)2), -15.1 (br s, 1P; PPh3); 19F NMR (C6D6,
376.50 MHz, 20 °C) δ -52.0 (m, 6F; PCF3), -57.5 (m, 6F; PCF3).
X-ray Crystallography. The X-ray diffraction data for all
complexes were measured at 150 K on a Bruker SMART APEX
II CCD area detector system equipped with a graphite mono-
chromator and a Mo KR fine-focus sealed tube operated at 1.5
kW power (50 kV, 30 mA). Crystals were attached to either a
Hampton Research cryoloop or a MiTeGen micromount using
Paratone N oil. The detector was placed at a distance of 5.9 cm
from the crystal during the data collection.
2
and C2H4), -10.94 (t, JHP = 12.0 Hz, 1H; IrH). 31P{1H}
NMR (CD2Cl2, 161.97 MHz, 20 °C): δ 56.8 (m). 13C NMR
(CD2Cl2, 100.61 MHz, 20 °C): δ 140.5 (s; ipso-C6H3CH2P-
(CF3)2), 129.0 (d, 1JCH=165 Hz; p-C6H3(CH2P(CF3)2), 126.0
1
1
(dm, JCH = 161 Hz; m-C6H3(CH2P(CF3)2), 76.9 (t, JCH
169 Hz; Ir(C2H4)), 35.7 (tm, 1JCH=139 Hz; CH2P(CF3)2). 19
NMR (CD2Cl2, 376.50 MHz, 20 °C): δ -53.8 (m, 6F; PCF3),
-61.7 (m, 6F; PCF3). IR: ν(CO) 2115 cm-1
=
F
.
[(CF PCP)Ir(CO)(H)]2(μ-Cl) SbF6- (11). Complex 4 (0.200 g,
0.286 mmol) and AgSbF6 (0.049 g, 0.144 mmol) were dissolved
in 15 mL of 1,2-dichloroethane. The reaction mixture was
refluxed for 4 h, and the solution changed from colorless to
pale green with a AgCl suspension. The reaction mixture was
cooled to room temperature and allowed to stand undisturbed
overnight, resulting in the deposition of large blue-green crystals
of 11, which were filtered and manually separated from AgCl
(0.156 g, 68% yield). Anal. Calcd for C26H16O2P4F20ClSbIr2: C,
19.55; H, 1.01. Found: C, 19.63; H, 0.75. 1H NMR (1,2-
difluorobenzene, 400.13 MHz, 20 °C): δ 3.01 (m, 8H; C6H3-
(CH2P(CF3)2)2), -22.73 (t, 2JHP =16.0 Hz, 1H; IrH). 31P{1H}
þ
3
A series of narrow frames of data were collected with a scan
width of 0.5° in ω or φ and an exposure time of 10 s per frame.
The frames were integrated with the Bruker SAINT Software
package32 using a narrow-frame integration algorithm. The
data were corrected for absorption effects by the multiscan
method (SADABS). Crystallographic data collection para-
meters and refinement data are deposited as Supporting Infor-
mation. The structures were solved by direct methods (1, 4) or
Patterson methods (9a, 11, 12) using the Bruker SHELXTL (V.
6.10) software package. All non-hydrogen atoms were located in
successive Fourier maps and refined anisotropically.
Hydrogen atoms in structures 4, 9a, and 11 were located on
difference Fourier maps and refined isotropically. All hydrogen
atoms in complex 1 were placed in calculated positions with
isotropic thermal parameters set to 1.2 times that of the attached
non-hydrogen atom. Hydride and aquo hydrogen atoms for 12
were located on difference Fourier maps and refined isotropi-
cally; the remaining hydrogen atoms were placed in calculated
positions. The metal centers in 11 are related by a crystal-
lographic 2-fold rotational axis along the bridging chloride
atom.
NMR (1,2-difluorobenzene, 161.97 MHz, 20 °C): δ 59.2 (m). 19
F
NMR (1,2-difluorobenzene, 376.50 MHz, 20 °C): δ -55.8 (m,
6F; PCF3), -60.6 (m, 6F; PCF3).
CF3
(
PCP)Ir(PPh3)(H)Cl Mixture of Isomers 13a,b. Complex 5
(0.469 g, 0.660 mmol) and PPh3 (173 g, 0.660 mmol) were
dissolved in ca. 20 mL of 1,2-difluorobenzene at -15 °C. The
reaction mixture was stirred for 3 h at -15 °C and then was
slowly warmed to room temperature and stirred for an addi-
tional 21 h. The volume was reduced to ca. 7 mL, and ca. 30 mL
of hexanes was added to precipitate the product as a white
powder. The product was collected via filtration and shown to
be an ∼8:1 mixture of 13a and 13b by 1H NMR integration of
1
IrH resonances. Spectroscopic data for 13a: H NMR (C6D6,
Acknowledgment. We thank The National Science
Foundation (No. CHE-0457435) and DOE/EPSCoR
(No. DE-FG02-08ER15979) for financial support.
400.13 MHz, 20 °C) δ 7.67 (br m, 6H; PPh3), 6.87 (br m, 9H;
PPh3), 6.56 (t, 3JHH=8 Hz, 1H; p-C6H3(CH2P(CF3)2)2), 6.31 (d,
3JHH=8 Hz, 2H, m-C6H3(CH2P(CF3)2)2), 3.13 (br dt, 2JHH=18
Hz, 2JPH=5 Hz, 2H; C6H3(CH2P(CF3)2)2), 2.59 (br d, 2JHH=18
Hz, 2H; C6H3(CH2P(CF3)2)2), -11.23 (dt, 2JHP(PPh )=129 Hz,
Supporting Information Available: CIF files giving crystal-
lographic data for complexes 1, 4, 9a, 11, and 12. This material is
available free of charge via the Internet at http://pubs.acs.org.
3
2JHP(PCP)=17 Hz, H; IrH); 31P{H} NMR (C6D6, 161.97 MHz,
20 °C) δ 43.9 (m, 2P; C6H3(CH2P(CF3)2)2), -23.0 (br s, 1P;
PPh3); 19F NMR (C6D6, 376.50 MHz, 20 °C) δ -52.8 (m, 6F;
PCF3), -61.9 (m, 6F; PCF3). Thermal conversion to 13b: warm-
ing a NMR sample of 13a in C6D6 to 80 °C for 10 min gave
(32) APEX2 Software Suite V. 2.2; Bruker AXS Inc., Madison, WI,
2008.