Synthesis of iridium(III) carboxamides via the bimetallic reaction between Cp*(PMe3)IrPh(OH) and [Cp*(PMe3)Ir(Ph)NCR]+

Article abstract of DOI:10.1021/ic9907157

Reaction of Cp*(PMe₃)IrPh(OH) (1) with nitriles is undetectably slow in benzene solution at room temperature. However, in the presence of Cp*(PMe₃)IrPh(OTf) (2) (OTf = O₃SCF₃), the reaction is strongly catalyzed, leading to iridium(III) carboxamides Cp*(PMe₃)IrPh[NHC(O)R] (6a-d) [R = C₆H₄CH₃ (6a), C₆H₅ (6b), C₆H₄CF₃ (6c), CH₃ (6d)]. We propose that these transformations occur by initial displacement of the trifluoromethanesulfonate ( triflate ) anion of 2 by a molecule of nitrile, leading to a nitrile-substituted indium cation, [Cp*(PMe₃)IrPh(NCR)]⁺ (10). Following this, the nucleophilic hydroxide group of 1 attacks the (activated) nitrile molecule bound in 10, leading (after proton transfer) to the iridium carboxamide complex. In the case of nitriles possessing hydrogens a to the cyano group, competitive loss of one of these protons is observed, leading to iridium C-bound cyanoenolates such as Cp*(PMe₃)(Ph)Ir(CH₂CN) (7). Protonolysis of carboxamides 6a-d with HCl yields Cp*(PMe₃)IrPh(Cl) (9) and the free amides. A pronounced solvent effect is observed when the reaction between 1 and nitriles catalyzed by 2 is carried out in THF solution. The basic hydroxide ligand of 1 induces an overall dehydration/cyclization reaction of the coordinated aromatic nitrile. For example, the reaction of 1 with p-trifluorotolunitrile and a catalytic amount of 2 leads to the formation of 6c, water, [Ph(PMe₃)Ir[C₅Me₄CH₂C(C ₆H₄CF₃)N]] (12), and [Ph(PMe₃)Ir(C₅Me₄CH₂C(C ₆H₄CF₃)NH)]OTf (13). A mechanism to explain the formation of both 12 and 13 and the role each compound plays in the formation of the iridium carboxamides is proposed.

Full text of DOI:10.1021/ic9907157

4810
Inorg. Chem. 1999, 38, 4810-4818
Synthesis of Iridium(III) Carboxamides via the Bimetallic Reaction between
Cp*(PMe3)IrPh(OH) and [Cp*(PMe3)Ir(Ph)NCR]+
David M. Tellers, Joachim C. M. Ritter, and Robert G. Bergman*
Department of Chemistry, University of California, Berkeley, California 94720
ReceiVed June 18, 1999
Reaction of Cp*(PMe3)IrPh(OH) (1) with nitriles is undetectably slow in benzene solution at room temperature.
However, in the presence of Cp*(PMe3)IrPh(OTf) (2) (OTf ) O3SCF3), the reaction is strongly catalyzed, leading
to iridium(III) carboxamides Cp*(PMe3)IrPh[NHC(O)R] (6a-d) [R ) C6H4CH3 (6a), C6H5 (6b), C6H4CF3 (6c),
CH3 (6d)]. We propose that these transformations occur by initial displacement of the trifluoromethanesulfonate
(“triflate”) anion of 2 by a molecule of nitrile, leading to a nitrile-substituted iridium cation, [Cp*(PMe3)IrPh-
(NCR)]+ (10). Following this, the nucleophilic hydroxide group of 1 attacks the (activated) nitrile molecule bound
in 10, leading (after proton transfer) to the iridium carboxamide complex. In the case of nitriles possessing hydrogens
R to the cyano group, competitive loss of one of these protons is observed, leading to iridium C-bound cyanoenolates
such as Cp*(PMe3)(Ph)Ir(CH2CN) (7). Protonolysis of carboxamides 6a-d with HCl yields Cp*(PMe3)IrPh(Cl)
(9) and the free amides. A pronounced solvent effect is observed when the reaction between 1 and nitriles catalyzed
by 2 is carried out in THF solution. The basic hydroxide ligand of 1 induces an overall dehydration/cyclization
reaction of the coordinated aromatic nitrile. For example, the reaction of 1 with p-trifluorotolunitrile and a catalytic
amount of 2 leads to the formation of 6c, water, [Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N]] (12), and [Ph(PMe3)Ir-
(C5Me4CH2C(C6H4CF3)NH)]OTf (13). A mechanism to explain the formation of both 12 and 13 and the role
each compound plays in the formation of the iridium carboxamides is proposed.
Introduction
Scheme 1
We recently demonstrated that the reaction of Cp*(PMe3)-
Ir(Ph)OH (1) with ethylene to give hydroxyethyl complex 3,
involving formal insertion of ethylene into an iridium-oxygen
bond, is catalyzed by Cp*(PMe3)Ir(Ph)OTf (2) (eq 1).1 In this
reaction, the ethylene and hydroxide ligands are activated and
coupled by two individual [Cp*(PMe3)Ir(Ph)]+ fragments
(Scheme 1). This reaction is an unusual example of a tandem
activation of two ligands by identical metal centers.
Other groups have also discovered and attempted to model
similar reactivity patterns between two transition metals.2
Jacobsen and co-workers have demonstrated that the chromium-
catalyzed asymmetric ring opening of epoxides3,4 and the cobalt-
catalyzed kinetic resolution of chiral epoxides5 proceed in a
bimetallic fashion. Stanley and co-workers have developed
homobimetallic rhodium complexes which serve as highly
selective hydroformylation catalysts.6 In attempts to mimic
natural nucleases that possess two metal ions in their active sites,
researchers have developed dinuclear metal complexes that
exhibit markedly better catalytic behavior than their monomeric
analogues.7-17
(6) Broussard, M. E.; Joma, B.; Train, S. G.; Peng, W.; Laneman, S. A.;
Stanley, G. G. Science 1993, 260, 1784-1788.
(7) Williams, N. H.; Cheung, W.; Chin, J. J. Am. Chem. Soc. 1998, 120,
8079-8087.
(1) Ritter, J. C. M.; Bergman, R. G. J. Am. Chem. Soc. 1997, 119, 2580-
2581.
(2) van den Beuken, E. K.; Feringa, B. L. Tetrahedron 1998, 54, 12985-
(8) Frey, S. T.; Muthy, N. N.; Weintraub, S. T.; Thompson, L. K.; Karlin,
K. D. Inorg. Chem. 1997, 36, 956-957.
13011.
(3) Hansen, K. B.; Leighton, J. L.; Jacobsen, E. N. J. Am. Chem. Soc.
1996, 118, 10924-10925.
(9) Hurst, P.; Takasaki, B. K.; Chin, J. J. Am. Chem. Soc. 1996, 118,
9982-9983.
(4) Konsler, R. G.; Karl, J.; Jacobsen, E. N. J. Am. Chem. Soc. 1998,
120, 10780-10781.
(10) Liu, S.; Luo, Z.; Hamilton, A. D. Angew. Chem., Int. Ed. Engl. 1997,
36, 2678-2680.
(5) Tokunaga, M.; Larrow, J. F.; Kakiuchi, F.; Jacobsen, E. N. Science
1997, 277, 936-938.
(11) Molenveld, P.; Kapsabelis, S.; Engbersen, J. F. J.; Reinhoudt, D. N.
J. Am. Chem. Soc. 1997, 119, 2948-2949.
10.1021/ic9907157 CCC: $18.00 © 1999 American Chemical Society
Published on Web 09/25/1999

Synthesis of Iridium(III) Carboxamides
Inorganic Chemistry, Vol. 38, No. 21, 1999 4811
To extend the reaction manifold shown in Scheme 1 to other
unsaturated organic compounds, we decided to explore the
reaction of 1 with nitriles to generate iridium carboxamides.
The conversion of nitriles to amides is a synthetically difficult
reaction generally requiring harsh acidic or basic conditions.18
The use of transition metal cations catalyzes this reaction.19-22
We report the synthesis of a variety of iridium carboxamides,
which are analogous to key intermediates in metal-catalyzed
nitrile hydration reactions. These iridium carboxamides are
generated by the addition of 1 to RCN in the presence of a
catalytic amount of 2. We believe that a critical step in this
transformation is the transfer of the hydroxide ligand of 1 to an
iridium-bound nitrile.23
Results and Discussion
Aromatic Nitriles. When a solution of equimolar amounts
of 1 and p-tolunitrile was heated in benzene at 45 °C, no reaction
was observed even after 14 d. However, upon treatment of an
identical solution of 1 and p-tolunitrile with 0.02 equiv of
Cp*(PMe3)IrPh(OTf) (2), production of Cp*(PMe3)IrPh[NHC-
(O)C6H4CH3] (6a) was observed in 4 d at 45 °C (eq 2).
Figure 1. ORTEP diagram of Cp*(PMe3)IrPh[NHC(O)C6H4CH3] (6a).
Hydrogen atoms have been omitted for clarity. Thermal ellipsoids are
shown at 50% probability.
Table 1. Crystal and Data Collection Parameters for
Cp*(PMe3)IrPh[NHC(O)C6H4CH3] (6a) and
[Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N] (12)
formula
fw
cryst size
C27H37IrNOP
614.79
0.25 × 0.30 ×
0.30 mm
monoclinic
C2/c
25.2021(3)
13.4474(2)
15.0355(2)
8
5011.6(1)
164
C27H32NF3PIr
650.75
0.33 × 0.10 ×
0.05 mm
monoclinic
C2/c
22.9330(5)
12.2372(2)
19.0405(4)
8
5222.4
170
1.655
52.25
ω (0.3)
10.0
Mo KR (λ )
0.710 69 Å)
graphite (2θmax
52.2°)
cryst syst
space group
a (Å)
b (Å)
c (Å)
Compound 6a was isolated in 86% yield as tan, air-stable
crystals. The N-H proton appears as a broad singlet at 4.79
Z
1
V (Å3)
T (K)
ppm in the H NMR spectrum (C6D6). In the 13C{1H} NMR
spectrum, the carbonyl carbon resonance appears at 173 ppm.
The carbonyl moiety on 6a exhibits a strong infrared stretch at
1604 cm-1. To confirm the connectivity of 6a, a single-crystal
X-ray diffraction study was performed. An ORTEP diagram of
6a is shown in Figure 1. Data collection parameters for 6a are
given in Table 1, and selected bonding parameters for 6a are
presented in Table 2. As expected for the tautomer of 6a
illustrated in eq 2, the C(10)-N(1) bond length of 1.329(5) Å
and the C(10)-O(1) bond length of 1.247(4) Å are consistent
with free amide single and double bonds, respectively.24
D
calcd (g/cm3)
1.630
54.26
µ(Mo KR, cm-1
)
scan type (deg/frame) ω (0.3)
scan rate (s/frame)
radiation
10.0
Mo KR (λ )
0.710 69 Å)
graphite (2θmax
52.1°)
monochromator
)
)
2θ range (deg)
3-45
3-45
no. of reflns measd
11 716 (unique: 4651 12553 (unique: 4885
(Rint ) 0.029))
0.020
0.027
0.028
1.23
0.030
280
(Rint ) 0.056))
Ra
Rw
0 0.044
b
0.053
0.076
1.30
0.030
298
(12) Ragunathan, K. G.; Schneider, H. J. Angew. Chem., Int. Ed. Engl.
1996, 35, 1219-1221.
Rall
GOF
p-factor
no. of variables
(13) Wilcox, D. E. Chem. ReV. 1996, 96, 2435-2458.
(14) Yamaguchi, K.; Koshino, S.; Akagi, F.; Suzuki, M.; Uehara, A.;
Suzuki, S. J. Am. Chem. Soc. 1997, 119, 5752-5753.
(15) Wall, M.; Hynes, R. C.; Chin, J. Angew. Chem., Int. Ed. Engl. 1993,
32, 1633-1635.
a R ) ∑||Fo| - |Fc||/∑|Fo|. b Rw ) [∑w(|Fo| - |Fc|)2/∑wFo ]1/2, w
2
) 1/σ2(Fo).
(16) Meyer, F.; Rutsch, P. J. Chem. Soc., Chem. Commun 1998, 1037-
1038.
Table 2. Selected Intramolecular Distances and Angles for
Cp*(PMe3)IrPh[NHC(O)C6H4CH3] (6a)
(17) Noveron, J. C.; Olmstead, M. M.; Mascharah, P. K. J. Am. Chem.
Soc. 1999, 121, 3553-3554.
(18) March, J. AdVanced Organic Chemistry, 4th ed.; John Wiley and
Sons: New York, 1992; pp 887-888.
Distance (Å)
Ir-N
2.099(3)
Ir-P(1)
2.273(1)
1.329(5)
1.247(4)
(19) Storhoff, B. N.; Lewis, H. C. Coord. Chem. ReV. 1977, 23, 1-29.
(20) Michelin, R. A.; Mozzon, M.; Bertain, R. Coord. Chem. ReV. 1996,
147, 299-338.
(21) Trogler, W. C.; Jensen, C. M. J. Am. Chem. Soc. 1986, 108, 723-
729.
Ir-C(101)a
Ir-C(1)
1.87950(10)
2.086(4)
N-C(10)
O-C(10)
Angles (deg)
Ir-N-C(10)
O-C(10)-N
128.7(2)
123.5(3)
O-C(10)-C(11)
118.2(3)
(22) Kim, J. H.; Britten, J.; Chin, J. J. Am. Chem. Soc. 1993, 115, 3618-
3622.
(23) For examples of a bimetallic catalyzed hydration of acetonitrile see:
(a) McKenzie, C. J.; Robson, R. J. Chem. Soc., Chem. Commun. 1988,
112-114 and (b) Curtis, N. J.; Hagen, K. S.; Sargeson, A. M. J. Chem.
Soc., Chem. Commun. 1984, 1571-1573.
(24) Robin, M. B.; Bovey, F. A.; Basch, H. The Chemistry of Amides;
Interscience: London, 1970; pp 1-72.
a C(101) is the centroid of cyclopentadienyl ring C(18)-C(22).
Complex 1 also reacted with benzonitrile and p-trifluorotolu-
nitrile in the presence of catalytic amounts of 2 (5 mol %) at
45 °C to yield Cp*(PMe3)IrPh[NHC(O)C6H5] (6b) (t1/2 ) 36

4812 Inorganic Chemistry, Vol. 38, No. 21, 1999
Tellers et al.
h) and Cp*(PMe3)IrPh[NHC(O)C6H4CF3] (6c) (t1/2 ) 4 h),
1
respectively (eq 2). The yields were quantitative by H NMR
spectroscopy, and 6b,c were isolated in 89% and 54% yields,
respectively, following crystallization. Compounds 6b,c exhibit
spectroscopic properties similar to those of 6a.
Aliphatic Nitriles. The reactions of aliphatic nitriles (R2HCCN)
with hydroxide complex 1 exhibit a similar dependence upon
the presence of triflate 2. However, an additional mode of
reactivity is observed with these substrates. For example,
treatment of a benzene solution containing equimolar amounts
of 1 and acetonitrile with 0.02 equiv of 2 resulted in the
generation of a 64:36 mixture of Cp*(PMe3)IrPh[NHC(O)CH3]
(6d) and Cp*(PMe3)Ir(CH2CN)Ph (7) (eq 3).25 Separation of
these product mixtures was not attempted; instead the identities
of 6d (vide infra) and 726 were confirmed via independent
syntheses.
performed at elevated temperatures in the presence of a large
excess of water (10 equiv). The free amide was produced,
however, by treatment of 6a-d with HCl. Addition of 1 equiv
of HCl (diethyl ether solution) to a solution of 6a-d in benzene
resulted in the quantitative formation of Cp*(PMe3)IrPh(Cl)
(9),29 as determined by NMR spectroscopy, and the free amide
(eq 6). The free amides were isolated in 38-73% yields, and
their identities were confirmed by gas chromatography and 1H
NMR spectroscopy.
These results suggest that, in addition to activating CH3CN
toward nucleophilic attack (to give 6d), 2 activates CH3CN
toward deprotonation at the R-carbon (to give 7), a type of
process that has previously been observed for other transition
metal nitrile complexes.27 These two competing modes of
reactivity are seen with a variety of other nitriles. The ratio of
the products from deprotonation and nucleophilic attack appears
to depend on both the steric and electronic properties of the
nitrile. In one example, treatment of 1 with diphenylacetonitrile
and a catalytic amount of 2 (5 mol %) gave exclusively the
deprotonation product Cp*(PMe3)Ir[NdCdC(Ph)2]Ph (8) (eq
4). The keteniminate 8 was isolated in 75% yield as bright
Proposed Mechanism. Formation of carboxamides 6a-d
from the corresponding nitriles and 1 is proposed to occur by
the mechanism outlined in Scheme 2. Precoordination of the
nitrile to 2 generates [Cp*(PMe3)IrPh(NCR)]+OTf- (10a-d)
(vide infra). The cationic iridium fragment “Cp*(PMe3)Ir(Ph)+”
serves to activate the nitrile toward nucleophilic attack. Transfer
of the hydroxide moiety from 1 to 10a-d, in a manner similar
to that reported in the reaction with ethylene,1 produces 2 and
the iminol 11, which quickly rearranges to generate the observed
carboxamide. For aliphatic nitriles, a second pathway is acces-
sible. In addition to generation of the carboxamide 6d, hydroxide
1 can deprotonate the R carbon of the cyano group on 10d,
leading to formation of 7 and regeneration of 2.
Effect of Added Salts. To determine whether 2 exerts its
effect in the formation of the carboxamides 6a-c simply by
increasing the ionic strength of the solution, we probed the effect
of added salt on the rate of the reaction.30,31 For example, a
benzene solution containing equimolar amounts of hydroxide
1 and acetonitrile was treated with 5 mol % tetrahexylammo-
nium tetra(3,5-bistrifluoromethyl)phenylborate, a benzene-
soluble salt. Neither 6d nor 7 was observed after prolonged
heating of this solution at 45 °C. Thus, addition of the borate
salt did not serve to promote formation of the carboxamide or
deprotonation products.
Reactions in THF. Having explored the effect of added
ammonium salts, we were interested in determining how
changing the solvent would affect the reaction of 1 with nitriles.
In particular, we were interested in increasing the concentration
of 2 relative to hydroxide 1, since the nitrile adducts 10a-d,
which are generated from 2 and the appropriate nitrile, are
sparingly soluble in benzene. To access a range of concentrations
wider than those available in benzene, we carried out the
orange crystals. This compound exhibits a strong infrared band
at 2105 cm-1 assigned to the NdCdC stretching mode. The
connectivity of this compound was confirmed crystallographi-
cally. An ORTEP diagram and structural information are
provided as Supporting Information.28 In contrast to our
observations with acetonitrile, the deprotonation of diphenyl-
acetonitrile does occur in the absence of 2, but at a slower rate.
This is consistent with our hypothesis that 2 functions to activate
the nitrile moiety.
As illustrated in eq 5, the iridium carboxamides 6a-d can
be synthesized independently in 65-88% isolated yields by
treatment of 1 with the appropriate organic amides. Cleavage
of the Ir-N bond in 6a-d would represent the final step in the
overall metal-mediated conversion of a nitrile to an amide.
Attempts to generate 1 and free amide by treatment of 6a-d
with water were unsuccessful even when the reactions were
1
(25) The ratio of 3d to 4 was determined by H NMR spectroscopy.
(26) Synthesis of compound 7 can be found in the Experimental Section.
(27) Buckingham, D. A.; Keene, F. R.; Sargeson, A. M. J. Am. Chem.
Soc. 1973, 95, 5649-5652.
(28) For an example of another structurally characterized iridium keten-
iminate complex, see: (a) Ibers, J. A.; Ricci, J. S.; Fraser, M. S.;
Baddley, W. H. J. Am. Chem. Soc. 1970, 92, 3489-3490. (b) Ibers,
J. A.; Ricci, J. S. J. Am. Chem. Soc. 1971, 93, 2391-2397.
(29) Kaplan, A. W.; Ritter, J. C. M.; Bergman, R. G. J. Am. Chem. Soc.
1998, 120, 6828-6829.
(30) Lowry, T. H.; Richardson, K. S. Mechanism and Theory in Organic
Chemistry; Harper and Row: New York, 1987; Chapter 2.
(31) Loupy, A.; Tchoubar, B. Salt Effects in Organic and Organometallic
Chemistry; VCH: New York, 1992.

Synthesis of Iridium(III) Carboxamides
Inorganic Chemistry, Vol. 38, No. 21, 1999 4813
Scheme 2
Scheme 4
while excess nitrile is maintained. As shown in Scheme 4,
reactions run in the presence of 10 mol % 2 at 45 °C in THF
result in the formation of not only 6c (30% NMR yield), but
also [Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N]] (12) (60% NMR
yield), small amounts of [Ph(PMe3)Ir(C5Me4CH2C(C6H4CF3)-
NH)]OTf (13), and water.33
The structure of the cyclometalated compound 12, a product
resulting from the formal addition of nitrile followed by
dehydration of 1, was initially assigned using NMR spectros-
copy. The 1H NMR spectrum (THF-d8) of compound 12
contains four cyclopentadienyl methyl signals on the cyclopen-
tadienyl ligand at δ 2.19, 2.02, 1.68, and 1.53. The methylene
protons on the cyclopentadienyl ligand are diastereotopic and
appear as two doublets centered at 3.66 and 3.59 ppm (2JH-H
) 17 Hz). Consistent with incorporation of p-trifluorotolunitrile,
12 exhibits a resonance in the 19F NMR spectrum (THF-d8) at
-59.4 ppm.
Scheme 3
Cyclometalated compound 12 was independently synthesized
by treatment of triflate 2 with an excess of p-trifluorotolunitrile
followed by addition of KOtBu (eq 8). Compound 12 was
reactions of 1, 2, and nitrile in THF. Treatment of a THF-d8
solution of 2 with 1 equiv of p-trifluorotolunitrile resulted in
the quantitative formation of [Cp*(PMe3)Ir(Ph)NCC6H4-
CF3]+OTf- (10c) as determined by 1H and 31P{1H} NMR
spectroscopy (eq 7). Addition of 1 equiv of hydroxide 1 to the
isolated in 35% yield following crystallization. This methodol-
ogy was previously employed for the deprotonation of
[Cp*(Ph2P(CH2)2PPh2)IrMe]+I- (14) with KOtBu leading to
formation of the iridium(I) fulvene (C5Me4CH2)(Ph2P(CH2)2-
PPh2)IrMe (15) (eq 9).34
nitrile adduct 10c (Scheme 3) led to the formation of carbox-
amide 6c in 60% yield after 2 d, along with triflate 2, nitrile
adduct 10c, and an unidentified, insoluble black precipitate. In
contrast, when a THF-d8 solution of triflate 2 was treated with
10 equiv of p-trifluorotolunitrile, followed by 1 equiv of 1, clean
formation of carboxamide 6c was observed in 5 h (Scheme 3).
The concentration of nitrile adduct 10c remained constant in
this reaction, as expected. It is therefore necessary to run these
reactions in the presence of excess nitrile to favor formation of
6c and prevent competing side reactions.32
The structural assignment of 12 was confirmed by a single-
crystal X-ray diffraction study. An ORTEP diagram (Figure 2)
confirms the connectivity. The data collection parameters are
presented in Table 1, and selected bonding parameters are
displayed in Table 3. The metallacycle causes the cyclopenta-
dienyl ligand to tilt such that the bridging Cp carbon C(3) is
only 2.153 Å from iridium. The remaining Cp carbon to iridium
(33) Treatment of 10c with a slurry of CsOH (1 equiv) in THF-d8 results
in immediate formation of 1 and free nitrile. Subsequently, consump-
tion of 1 and nitrile is observed, generating a product mixture similar
to that illustrated in Scheme 4. Presumably the presence of small
amounts of 2 catalyzes this reaction, but the heterogeneous nature of
this mixture makes analysis difficult.
An interesting change in the reactivity of 1 in THF is observed
as the amount of 2 is decreased below 1 equiv relative to 1
(32) Presumably, the cation derived from 2 which is generated during the
reaction is responsible for this decomposition.
(34) Glueck, D. S.; Bergman, R. G. Organometallics 1990, 9, 2862-2863.

4814 Inorganic Chemistry, Vol. 38, No. 21, 1999
Tellers et al.
Scheme 5
Figure 2. ORTEP diagram of Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N]
(12). Hydrogen atoms have been omitted for clarity. Thermal ellipsoids
are shown at 50% probability.
Table 3. Selected Intramolecular Distances and Angles for
[Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N] (12)
Distance (Å)
Ir-N
2.038(7)
1.8684(4)
2.153(10)
2.29(1)
Ir-C(7)
2.20(1)
1.27(1)
1.53(1)
1.50(1)
(>90%) and small amounts of 12 (<5%). The formation of
larger amounts of 12 is presumably not observed because
dissociation of the hydroxide, as proposed in THF, is unfavor-
able in benzene, a less polar solvent. Hughes and co-workers
have observed a similar solvent effect in the coupling of a Cp*
ligand and a perfluorobenzyl ligand on cobalt, which proceeds
in THF and not in benzene.35
Ir-C(101)a
Ir-C(3)
Ir-C(5)
N-C(1)
C(1)-C(2)
C(2)-C(3)
Angles (deg)
Ir-N-C(1)
N-C(1)-C(2)
C(1)-C(2)-C(3)
115.3(6)
122.7(8)
109.6(8)
N-C(1)-C(12)
C(2)-C(1)-C(12)
119.5(8)
117.8(8)
Reactivity of 12 and 13. Attempts to perform a kinetic
analysis on the triflate-catalyzed reaction of hydroxide 1 with
nitriles in THF at constant ionic strength were complicated by
formation of 12 and 13. In an attempt to gain a better
understanding of what roles, if any, 12 and 13 might play during
the reaction illustrated in Scheme 4, we subjected the inde-
pendently synthesized metallacycle 12 to conditions similar to
those of the original reaction. First, approximately 1 equiv of
water was added to a THF-d8 solution of 12. No reaction was
observed between these two complexes even after prolonged
heating. In a separate experiment, approximately 1 equiv of
water was added to a THF-d8 solution of triflate 2. The
formation of the aquo adduct [Cp*(PMe3)Ir(Ph)OH2]OTf (16)
was observed (eq 10). Subsequent addition of 1 equiv of 12 to
a C(101) is the centroid of cyclopentadienyl ring C(3)-C(7).
distances are longer: C(4)-Ir(1) ) 2.22(1) Å, C(5)-Ir(1) )
2.29(1) Å, C(6)-Ir(1) ) 2.29(1) Å and C(7)-Ir(1) ) 2.20(1)
Å.
Complex 13, the N-protonated analogue of 12 (see Scheme
4), was independently synthesized by treatment of a methylene
chloride solution of 12 with trifluoromethanesulfonic acid.
Following crystallization metallacyle 13 was isolated in 62%
yield. Compound 13 exhibits a broad resonance at δ 10.74 ppm
1
in the H NMR spectrum consistent with the N-H proton.
Analogous to 12, a set of doublets attributable to the diastereo-
topic methylene protons are observed at 3.99 and 3.78 (2JH-H
) 19 Hz).
We propose the mechanism outlined in Scheme 5 to explain
the formation of 12. The presence of excess nitrile promotes
dissociation of the hydroxide ion, generating an iridium/
hydroxide ion pair. The hydroxide then rapidly deprotonates
the Cp* methyl group. The resulting anion attacks the nitrile
carbon to generate 12. Analogous to the hydroxide dissocation
above, the displacement of anilide by a dative ligand to generate
an outer-sphere anion has been postulated in the formation of
a similar iridium fulvene complex.34 While we cannot rule out
dissociation of hydroxide followed by nucleophilic attack upon
the nitrile adduct to generate carboxamide 6c in THF, the
reaction which generates 12 appears to involve only one metal.
This is based upon the observation that the rate of formation of
the cyclometalated compound 12 is independent of added triflate
2. In addition, as illustrated in Scheme 3, under high concentra-
tions of triflate 2 in THF, carboxamide 6c is formed and no
metallacyle 12 is observed.
the THF-d8 solution containing triflate 2 and water generated a
mixture containing four compounds, as determined by NMR
spectroscopy (eq 11). Along with 12 and aquo adduct 16,
hydroxide 1 and [Ph(PMe3)Ir(C5Me4CH2C(C6H4CF3)NH)]OTf
(13) were observed. The equilibrium depicted in eq 11 is
suggested to account for these observations.36 In this transfor-
mation, metallacycle 13 and hydroxide 1 are generated by
deprotonation of 16 by 12. Compound 12 is incapable of
deprotonating water in the absence of triflate 2. It is only when
water is bound to the iridium cation “Cp*(PMe3)Ir(Ph)+” (i.e.,
the aquo adduct 16) that it is sufficiently acidic to be deproton-
ated by 12.
Consistent with dissociation of the hydroxide to generate an
ionic intermediate, the reaction between complex 1 and p-
trifluorotolunitrile to produce metallacyle 12 exhibits a de-
pendence on solvent polarity. Treatment of a benzene solution
of hydroxide 1 and a catalytic amount of triflate 2 with 10 equiv
of p-trifluorotolunitrile results in formation of carboxamide 6c
(35) Hughes, R. P.; Lindner, D. C.; Rheingold, A. L.; Yap, G. P. A.
Organometallics 1996, 15, 5678-5686.
(36) Attempts to quantitatively determine the equilibrium constant were
unsuccessful because the mixture slowly decomposes to unidentified
products.

Synthesis of Iridium(III) Carboxamides
Inorganic Chemistry, Vol. 38, No. 21, 1999 4815
Scheme 6
Formal addition of water or hydroxide to 12 and 13,
respectively, would result in formation of carboxamide 6c. We
were interested in exploring the possible intermediacy of either
12 or 13 in the formation of 6c. As mentioned previously, no
reaction was observed between 12 and water. Furthermore,
heating the reaction mixture shown in eq 11 does not lead to
generation of carboxamide 6c, demonstrating that neither 12
nor 13 is an intermediate in the formation of 6c. Consistent
with this, treatment of the solution shown in eq 10 with nitrile
leads only to formation of the carboxamide derived from the
added nitrile (eq 12). For example, addition of 10 equiv of
side product nor an intermediate in the generation of carbox-
amide 6c, but acts as a base in the regeneration of hydroxide 1.
The reactivity demonstrated in this paper illustrates an
example of an organometallic reaction which utilizes two metal
centers to effect a transformation. We hope that our results will
be helpful in understanding related processes that have recently
been observed in the fields of bioinorganic and organic
chemistry and ultimately in the development of new organo-
metallic reactions utilizing two metal centers.37
p-tolunitrile to a solution containing equimolar amounts of 2,
water, and 12 in THF-d8 leads to formation of carboxamide 6a
(not 6c) and 13 after heating at 45 °C for 2 d (eq 12).
Carboxamide 6a is generated from the reaction of triflate 2,
hydroxide 1, and p-tolunitrile and not from either 12 or 13.
The reactivity of 1 and 2 in the presence of p-trifluorotolu-
nitrile in THF is summarized in Scheme 6. The bimetallic
reaction between hydroxide 1 and the nitrile adduct 10c produces
6c and triflate 2 (Scheme 6, eq 1). In contrast, hydroxide 1 reacts
with free p-trifluorotolunitrile to generate 12 and water (Scheme
6, eq 2). This primarily occurs in the initial stages of the reaction.
As the concentration of water increases, the generation of aquo
adduct 16 becomes competitive with the formation of 10c
(Scheme 6, eq 3). As independently demonstrated, compound
16 can then be deprotonated by 12 to generate 13 and hydroxide
1 (Scheme 6, eq 4).
Experimental Section
General Procedures. Unless otherwise noted, reactions and ma-
nipulations were performed at ambient temperature in a recirculating
Vacuum Atmospheres inert atmosphere glovebox (N2) or using standard
Schlenk and vacuum techniques. Glassware was dried in an oven at
160 °C before use.
1
The H NMR spectra were recorded at 400 MHz, 13C{1H} NMR
spectra were recorded at 100 MHz (or, if specified, 125 MHz), 31P{1H}
NMR spectra were recorded at 161.9 MHz, and 19F NMR spectra were
recorded at 376.5 MHz. 31P and 19F NMR spectra were referenced
externally to 85% phosphoric acid in water and trichlorofluoromethane,
respectively. In cases where assignments of 13C{1H} resonances were
ambiguous, resonances were assigned by using DEPT 45, 90, and 135
pulse sequences. All chemical shifts are reported in parts per million
(ppm). Elemental analyses were performed by the University of
CaliforniasBerkeley Microanalytical facility. X-ray structural analyses
were performed at the University of CaliforniasBerkeley CHEXRAY
facility.
Conclusion
In summary, we have reported an unusual example of
bimetallic reactivity that results in the synthesis of a series of
iridium(III) carboxamides by the formal addition of an iridium
hydroxide to an iridium-nitrile complex. This reaction is
catalyzed by the cationic iridium Lewis acid 2, which activates
the nitrile toward nucleophilic attack. Transfer of a hydroxide
moiety from 1 to [Ir-NCR]+ results in the regeneration of 2.
In the case of aliphatic nitriles, deprotonation of the carbon R
to the nitrile moiety is possible. The iridium carboxamides 6a-c
react with HCl to quantitatively generate Cp*(PMe3)IrPh(Cl)
(9) and the free amides.
Unless otherwise noted, reagents were purchased from commercial
suppliers and used without further purification. Hexanes, pentane,
diethyl ether, tetrahydrofuran, benzene, and toluene were distilled from
sodium/benzophenone ketyl under N2 prior to use. Methylene chloride
and acetonitrile were distilled from CaH2 under N2. Deuterated solvents
were purified by the same method as their protiated analogues and
vacuum-transferred prior to use. Cp*(PMe3)Ir(Ph)Cl (9) and Cp*(PMe3)-
IrPh(OH) (1) were prepared by literature methods.29 KOtBu was
sublimed prior to use. Acetamide was recrystallized from hot benzene
prior to use. Benzamide was crystallized twice from ethanol and dried
in vacuo for 24 h.
In addition to formation of the expected carboxamides, an
alternate mode of reactivity for hydroxide 1 is observed in THF,
where complex 1 reacts with p-trifluorotolunitrile to generate
the cyclometalated compound 12. Compound 12 is neither a
Cp*(PMe3)Ir(Ph)OTf (2). Modification of a literature procedure
was employed.38 To a stirred solution of Cp*(PMe3)IrPh(Cl) (1.1 g,
(37) See refs 2-17.

4816 Inorganic Chemistry, Vol. 38, No. 21, 1999
Tellers et al.
2.2 mmol) in methylene chloride (15 mL) at -40 °C was added a slurry
of AgOTf (0.63 g, 2.4 mmol, 1.1 equiv) in methylene chloride (10 mL).
The mixture was allowed to warm to 20 °C and was protected from
light. After 1 h, the solvent was evaporated under reduced pressure,
and the residual orange solid was dissolved in C6H6 and filtered through
silylated silica gel (5 × 2 cm). The solvent was lyophilized to yield an
orange powder. Yield: 1.4 g, 97% (lit. yield: 94%). Spectroscopic data
were in accord with literature values.38
Cp*(PMe3)IrPh[NHC(O)C6H4CH3] (6a). Method 1. A glass vessel
sealed to a Kontes vacuum adapter was charged with 1 (23 mg, 0.045
mmol), 2 (1.0 mg, 0.0013 mmol), p-tolunitrile (5.3 mg, 0.045 mmol),
and benzene (10 mL). The vessel was heated for 4.5 d at 45 °C. The
tan solution was filtered, and the solvent was removed under reduced
pressure. The oily residue was dissolved in a minimum of ether (6
mL). The solution was filtered and concentrated (4 mL). Crystals of
6a were obtained by slow evaporation of the solvent at -40 °C.
Yield: 24 mg, 86%.
Method 2. A glass vessel attached to a Kontes vacuum adapter was
charged with 1 (84 mg, 0.17 mmol), p-toluamide (23 mg, 0.017 mmol),
and benzene (5 mL). The vessel was then heated for 12 h at 45 °C.
The vessel was brought into a drybox, and the solvent was removed
under reduced pressure. The tan solid was crystallized by slow
evaporation of a concentrated diethyl ether of 6a at -40 °C. Yield: 77
mg, 74%.
4JP-H ) 1 Hz, 15H, C5Me5), 1.16 (d, 2JP-H ) 11 Hz, 9H, PMe3). 13C{1H}
NMR (C6D6): δ 171.2 (s, CdO), 143.6 (s, NHC(O)C6H4CF3), 139.6
(d, 3JP-C ) 13 Hz, i-C6H5), 138.3 (d, 3JP-C ) 3 Hz, o-C6H5), 130.1 (q,
2JF-C ) 31 Hz, NHC(O)C6H4CF3), 127.9 (s, NHC(O)C6H4CF3), 127.2
3
(s, m-C6H5), 124.9 (q, JF-C ) 3.6 Hz, NHC(O)C6H4CF3), 122.3 (s,
p-C6H5), 92.7 (d, 2JP-C ) 3 Hz, C5Me5), 14.8 (d, 1JP-C ) 37 Hz, PMe3),
9.1 (s, C5Me5), CF3 not observed.31P{1H} NMR (C6D6): δ -37.9. 19F
NMR (C6D6): δ -62.1. IR (KBr): 3392 (s, N-H), 3056 (m), 2989
(m), 2910 (s), 2366 (w), 1619, 1569 (s), 1432 (s), 1326 (s), 1122 (s),
954 (s), 840 (s), 736 (s) cm-1. Anal. Calcd for C27H34IrNOPF3: C,
48.50; H, 5.12; N, 2.09. Found: C, 48.20; H, 5.08; N, 2.07.
Cp*(PMe3)IrPh[NHC(O)CH3] (6d). The procedure for the synthesis
of 6a (method 2) was followed using 80 mg of 1 and 10 mg of
acetamide. Amide 6d was crystallized at -40 °C by layering a saturated
toluene solution with pentane to afford tan, needlelike crystals of 6d.
Yield: 80 mg, 88%. 1H NMR (C6D6): δ 7.29 (d, J ) 7 Hz, 2H, o-C6H5),
7.11 (m, 2H, m-C6H5), 7.10 (m, 1H, p-C6H5), 3.59 (br s, 1H, NH),
4
2.09 (s, 3H, NHC(O)CH3), 1.49 (d, JP-H ) 2 Hz, 15H, C5Me5), 0.81
(d, 2JP-H ) 13 Hz, 9H, PMe3). 13C{1H} NMR (C6D6): δ 174.5 (s, Cd
3
O), 138.8 (d, JP-C ) 3.4 Hz, o-C6H5), 127.9 (s, m-C6H5), 122.4 (s,
2
p-C6H5), 92.8 (d, JP-C ) 3 Hz, C5Me5), 27.1 (s, NHC(O)CH3), 15.2
(d, 1JP-C ) 37 Hz, PMe3), 9.5 (s, C5Me5), i-C6H5 not observed.31P{1H}
NMR (C6D6): δ -38.2. IR (C6D6): 3373 (m, N-H), 2950 (m), 2909
(m), 2868 (m), 1628 (s), 1571 (s), 1422 (m), 1281 (m), 944 (m), 574
(w) cm-1. MS (EI): m/z 539 (M+). Anal. Calcd for C21H33IrNOP: C,
46.82; H, 6.18; N, 2.66. Found: C, 46.92; H, 6.24; N, 2.45.
1H NMR (C6D6): δ 8.11 (d, J ) 8 Hz, 2H, NHC(O)C6H4CH3), 7.45
(d, J ) 7 Hz, 2H, NHC(O)C6H4CH3), 7.20 (m, 2H, o-C6H5), 7.01 (m,
2H, m-C6H5), 6.95 (m, 1H, p-C6H5), 4.79 (br, 1H, NH), 2.08 (s, 3H,
NHC(O)C6H4CH3), 1.56 (d, 4JP-H ) 2 Hz, 15H, C5Me5), 1.20 (d, 2JP-H
) 11 Hz, 9H, PMe3). 13C{1H} NMR (CD2Cl2): δ 172.9 (s, CdO), 140.2
(d, 2JP-C ) 12 Hz, i-C6H5), 138.8 (d, 3JP-C ) 3 Hz, o-C6H5), 138.5 (s,
i-NHC(O) C6H5), 129.1 (s, o to NHC(O)C6H5), 128.0 (s, m-C6H5), 127.2
Cp*(PMe3)Ir(CH2CN)Ph (7). To a solution of 2 (420 mg, 0.67
mmol) in THF (10 mL) was added CH3CN (3.8 g, 93 mmol). The light
green-yellow solution was cooled to -40 °C, and a slurry of KOtBu
(75 mg, 0.67 mmol) in THF (2 mL) was added. The solution
immediately turned orange-yellow upon mixing. After being stirred for
30 min at -40 °C, the solution was warmed to room temperature and
the solvent was removed under reduced pressure. The residual solid
was extracted with ether (3 × 5 mL). The ether extracts were collected,
filtered through glass fiber filter paper, and concentrated under reduced
pressure. Hexanes were allowed to slowly diffuse into the ether solution
at -40 °C. A yellow-brown precipitate containing two unidentified
products formed. The remaining solution was separated from this
mixture, concentrated under reduced pressure, and layered with pentane
to yield yellow microcrystals of 7. Yield: 30 mg, 9%. Material suitable
for elemental analysis was obtained by recrystallizing this material in
an identical manner. 1H NMR (C6D6, 500 MHz): δ 7.12 (m, 2H, C6H5),
2
(s, p-C6H5), 122.5 (s, m to NHC(O)C6H5), 92.9 (d, JP-C ) 3 Hz,
1
C5Me5), 21.1 (s, NHC(O)C6H4CH3), 15.1 (d, JP-C ) 37 Hz, PMe3),
9.5 (s, C5Me5). 31P{1H} NMR (C6D6): δ -37.9. IR (CH2Cl2): 3345 (s,
N-H), 3128 (m), 2910 (s), 2306 (s), 2194 (s), 2094 (w), 2007 (w),
1756 (w), 1604 (s), 1444 (m), 1384 (m), 962 (s) cm-1. Anal. Calcd for
C27H37IrNOP: C, 52.70; H, 6.07; N, 2.30. Found: C, 52.64; H, 6.12;
N, 2.28.
Cp*(PMe3)IrPh[NHC(O)C6H5] (6b). Method 1. The procedure for
the synthesis of 6a (method 1) was followed using 65 mg of 1, 3.0 mg
of 2, and 13 mg of benzonitrile. The product was isolated as a light
tan solid after crystallization from ether. Yield: 71 mg, 89%.
Method 2. The procedure for the synthesis of 6a (method 2) was
followed using 78 mg of 1 and 19 mg of benzamide. Yield: 62 mg,
69%.
2
3
7.03 (m, 3H, C6H5), 1.64 (dd, JHb-Ha ) 15 Hz, JP-Ha ) 4 Hz, 1H,
IrCHaHbCN), 1.55 (dd, 2JHa-Hb ) 15 Hz, 2JP-Hb ) 8 Hz, 1H, IrCHaHb-
4
2
CN), 1.36 (d, JP-H ) 2 Hz, 15H, C5Me5), 1.02 (d, JP-H ) 10 Hz, 9
H, PMe3). 13C{1H} NMR (C6D6, 125 MHz): δ 139.3 (d, 4JP-C ) 4 Hz,
1H NMR (C6D6): δ 8.15 (d, J ) 9 Hz, 2H, o-NHC(O)C6H5), 7.43
(d, J ) 7 Hz, 2H, o-C6H5), 7.20 (m, 2H, m-NHC(O)C6H5), 7.19 (m,
2H, o-C6H5), 7.17 (m, 1H, p-NHC(O)C6H5), 7.13 (m, 1H, p-C6H5), 4.79
(s, 1H, N-H), 1.54 (d, 4JP-H ) 2 Hz, 15H, C5Me5), 1.19 (d, 2JP-C ) 11
Hz, 9H, PMe3). 13C{1H} NMR (C6D6): δ 172.9 (s, CdO), 141.0 (s,
2
3
m-C6H5), 135.9 (d, JP-C ) 12 Hz, i-C6H5), 129.5 (d, JP-C ) 5 Hz,
2
o-C6H5), 122.1 (s, p-C6H5), 92.9 (d, JP-C ) 3 Hz, C5Me5), 13.9 (d,
3
2
1JP-C ) 37 Hz, PMe3), 8.6 (d, JP-C ) 1 Hz, C5Me5), -29.6 (d, JP-C
) 8 Hz, CH2CN). 31P{1H} NMR (C6D6): δ -44.2 ppm. IR (KBr): 3052
(w), 2973 (w), 2956 (w), 2913 (s), 2357 (w), 2194 (s), 1733 (w), 1568
(m), 1474 (m), 1458 (m), 1422 (m), 1401 (m), 1379 (m), 1283 (m),
1020 (m), 952 (s), 735 (m), 704 (m), 678 (w) cm-1. MS (EI): m/z 673
(M+). Anal. Calcd for C21H31NIrP: C, 48.44; H, 6.00; N, 2.70. Found:
C, 48.80; H, 6.33; N, 2.75.
2
i-NHC(O)C6H5), 140.2 (d, JP-C ) 12 Hz, i-C6H5), 138.8 (3JP-C ) 3
Hz, o-C6H5), 128.9 (s, m-C6H5), 128.5 (s, p-C6H5), 128.2 (s, o-NHC-
(O)C6H5), 127.3 (s, m-NHC(O)C6H5), 122.5 (s, p-NHC(O)C6H5), 93.0
(d, 2JP-C ) 4 Hz,C5Me5), 15.3 (d, 1JP-C ) 37 Hz, PMe3), 9.5 (s, C5Me5).
31P{1H} NMR (C6D6): δ -37.9. IR (KBr): 3381 (s), 3059 (s), 2972
(s), 2910 (s), 1620 (s), 1564 (s), 1428 (s), 1279 (m), 1242 (w), 1018
(w), 956 (s), 739 (m), 696 (m) cm-1. Anal. Calcd for C26H35IrNOP:
C, 51.98; H, 5.87; N, 2.33. Found: C, 52.13; H, 6.07; N, 2.28.
Cp*(PMe3)Ir[NHC(O)C6H3CF3]Ph (6c). Method 1. The procedure
for the synthesis of 6a (method 1) was followed using 26 mg of 1, 1.0
mg of 2, and 9.1 mg of p-CF3C6H4CN. The product was obtained as a
light tan solid after crystallization from ether. Yield: 19 mg, 54%.
Method 2. The procedure for the synthesis of 6a (method 2) was
followed using 150 mg of 1 and 57 mg of p-trifluorotoluamide. Yield:
130 mg, 65%.
Cp*(PMe3)Ir[NdCdC(Ph)2]Ph (8). A glass vessel attached to a
Kontes vacuum adapter was charged with 1 (77 mg, 0.15 mmol),
diphenylacetonitrile (30.0 mg, 0.15 mmol), and benzene (5 mL). The
solution was heated at 45 °C for 2 h, over which time it turned a bright
orange color. After 2 h, the solvent was lyophilized, and the orange
solid was redissolved in a minimum of pentane/benzene (9:1), filtered
through Celite, and evaporated under reduced pressure to yield 8. The
orange solid was crystallized by allowing pentane to diffuse into a
saturated toluene solution of 8 at room temperature. Yield: 78 mg,
1
75%. H NMR (C6D6): δ 7.80 (d, 4H, J ) 8 Hz, NdCdC(o-C6H5)2),
1H NMR (C6D6): δ 7.91 (d, J ) 8 Hz, 2H, C(O)C6H4CF3), 7.37 (d,
J ) 7 Hz, 2H, o-C6H5), 7.31 (d, J ) 8 Hz, 2H, C(O)C6H4CF3), 7.21
(m, 2H, m-C6H5), 7.15 (m, 1H, p-C6H5), 4.70 (br s, 1H, NH), 1.52 (d,
7.33 (t, 4H, J ) 7 Hz, NdCdC(m-C6H5)2), 7.31 (m, 2H, o-C6H5), 7.20
(m, 2H, m-C6H5), 7.13 (m, 1H, p-C6H5), 6.93 (t, 2H, J ) 7 Hz, Nd
4
CdC(p-C6H5)2), 1.27 (d, 15H, JP-H ) 2 Hz, C5Me5), 0.89 (d, 9H,
2JP-H ) 11 Hz, PMe3). 13C{1H} NMR (C6D6): δ 142.6 (s, NdCd
C(C6H5)2), 139.7 (d, 3JP-C ) 4 Hz, o-C6H5), 138.3 (d, 2JP-C ) 14 Hz,
(38) Woerpel, K. A.; Bergman, R. G. J. Am. Chem. Soc. 1993, 115, 7888-
3
7889.
i-C6H5), 129.7 (d, JP-C ) 5 Hz, NdCdC(C6H5)2), 128.8 (s, NdCd

Synthesis of Iridium(III) Carboxamides
Inorganic Chemistry, Vol. 38, No. 21, 1999 4817
C(i-C6H5)2), 128.6 (NdCdC(o-C6H5)2), 128.2 (d, J ) 3 Hz, m-C6H5),
123.6 (NdCdC(m-C6H5)2), 122.9 (s, p-C6H5), 119.4 (s, NdCdC(p-
C6H5)2), 94.4 (d, 2JP-C ) 3 Hz, C5Me5), 14.6 (d, 1JP-C ) 38 Hz, PMe3),
9.4 (s, C5Me5). 31P{1H} NMR (C6D6): δ -35.5. IR (KBr): 3048 (m),
2908 (m), 2105 (s), 1587 (s), 1376 (w), 1307 (m), 1255 (m), 1178
(m), 944 (s), 752 (s), 692 (s) cm-1. MS (EI): m/z 673 (M+). Anal.
Calcd for C32H39IrNP: C, 58.91; H, 5.84; N, 2.08. Found: C, 59.01;
H, 6.01; N, 2.07.
Anal. Calcd for C28H33NF6IrO3PS: C, 42.00; H, 4.15; N, 1.75. Found:
C, 42.01; H, 4.48; N, 1.64.
[Cp*(PMe3)Ir(Ph)NCCH3]+OTF- (10d). The procedure for the
synthesis of 10a was followed using 72 mg of 2 and 4.7 mg of
acetonitrile. Nitrile adduct 10d was purified by precipitation from a
concentrated methylene chloride solution with diethyl ether to afford
an off-white powder. Yield: 45 mg, 60%. 1H NMR (CD2Cl2, 500 MHz):
δ 7.17 (m, 2H, o-C6H5), 7.03 (m, 2H, m-C6H5), 6.97 (m, 1H, p-C6H5),
[Cp*(PMe3)Ir(Ph)NCC6H4CH3]+OTF- (10a). To a stirred solution
of 2 (110 mg, 0.18 mmol) in CH2Cl2 (5 mL) was added a solution of
p-tolunitrile (21 mg, 0.18 mmol) in CH2Cl2 (1 mL). Upon addition,
the initally orange solution turned light green. After 15 min, the solution
was filtered through glass fiber filter paper, and the solvent was removed
under reduced pressure to yield a light green solid. The product was
isolated as a light green solid after crystallization from a concentrated
methylene chloride solution layered with diethyl ether. Yield: 90 mg,
67%. 1H NMR (CD2Cl2): δ 7.67 (d, 2H, J ) 8 Hz, NCC6H4CH3), 7.46
(d, 2H, J ) 8 Hz, NCC6H4CH3), δ 7.23 (m, 2H, o-C6H5), 7.07 (m, 2H,
m-C6H5), 7.01 (m, 1H, p-C6H5), 2.51 (s, 3H, NCC6H4CH3), 1.74 (d,
15H, 4JP-H ) 2 Hz, C5Me5), 1.52 (d, 9H, 2JP-H ) 11 Hz, PMe3). 13C{1H}
NMR (CD2Cl2): δ 143.0 (s, NCC6H4CH3 (i to CH3)), 138.0 (s, p-C6H5),
2.80 (d, JP-C ) 2 Hz, 3H, CH3CN), 1.69 (d, JP-C ) 2 Hz, 15H,
C5Me5), 1.48 (d, 2JP-H ) 11 Hz, 9H, PMe3). 13C{1H} NMR (125 MHz,
CD2Cl2): δ 137.5 (s, p-C6H5), 134.2 (d, 2JP-C ) 14 Hz, i-C6H5), 128.5
4
4
2
(s, m-C6H5), 123.2 (s, o-C6H5), 116.9 (s, NCCH3), 95.5 (d, JP-C ) 3
1
Hz, C5Me5), 13.9 (d, JP-C ) 39 Hz, PMe3), 8.6 (s, C5Me5), 4.2 (s,
CH3CN).31P{1H} NMR (CD2Cl2): δ -34.2. 19F NMR (CD2Cl2): δ
-77.0. IR (KBr): 3059 (m), 2988 (s), 2924 (s), 2294 (w), 1571 (s),
1502 (m), 1465 (s), 1427 (s), 1384 (s), 1257 (s), 1156 (s), 1031 (s),
961 (s), 862 (m), 747 (s), 707 (s), 682 (w), 638 (s) cm-1. Anal. Calcd
for C22H32NF3IrO3PS: C, 39.4; H, 4.81; N, 2.10. Found: C, 39.28; H,
5.10; N, 1.99.
[Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N]] (12). To a solution of 2
(105 mg, 0.17 mmol) in THF (10 mL) was added p-CF3C6H4CN (720
mg, 4.2 mmol). It was found that an excess of p-trifluorotolunitrile is
necessary to drive the equilibrium toward formation of the adduct
[Cp*(PMe3)IrPh(NCC6H4CF3)]OTf (10c). Reactions run in the presence
of only 1 equiv of p-trifluorotolunitrile led to the formation of 12 and
a variety of unidentified products. The light green-yellow solution was
cooled to -40 °C, and a slurry of KtOBu (20 mg, 0.17 mmol) in THF
(2 mL) was added. The solution immediately turned red upon mixing
and became a darker red color as it warmed to room temperature. After
the solution was stirred for 30 min at room temperature, the solvent
was removed under reduced pressure. The residual solid was extracted
with benzene (15 mL) and filtered through glass fiber filter paper
directly into a glass vessel attached to a vacuum Kontes adapter. The
solvent was lyophilized and the residual material left under full vacuum
(25 °C, 0.01 Torr) for 24 h to remove the remaining p-CF3C6H4CN.
The remaining material was crystallized at -40 °C from a concentrated
toluene solution layered with pentane to yield 12 as bright red-orange
crystals. Yield: 38 mg, 35% yield. 1H NMR (THF-d8): δ 7.87 (d, J )
8 Hz, 2H, C6H4CF3), 7.52 (d, J ) 8 Hz, 2H, C6H4CF3), 7.28 (m, 2H,
C6H5), 6.79 (m, 3H, C6H5), 3.66 (d, J ) 17 Hz, 1H, C5Me4CHaHb),
3.59 (d, J ) 17 Hz, 1H, C5Me4CHaHb), 2.19 (s, 3H, C5Me4CH2), 2.02
(s, 3H, C5Me4CH2), 1.68 (d, J ) 4 Hz, 3H, C5Me4CH2), 1.53 (s, 3H,
C5Me4CH2), 1.37 (d, J ) 10 Hz, 9H, PMe3). 13C{1H} NMR (CD2Cl2):
δ 368.5 (d, 3JP-C ) 7 Hz, CdN), 143.1 (s, C6H4CF3), 139.5 (m, C6H4-
2
134.3 (d, JP-C ) 10 Hz, i-C6H5), 133.7 (s, NCC6H4CH3 (o to CN)),
131.2 (s, m-C6H5), 129.3 (s, NCC6H4CH3 (o to CH3)), 124.0 (s,
o-C6H5), 120.3 (s, NCC6H4CH3), 106.9 (s, NCC6H4CH3 (i to CN)),
96.7 (s, C5Me5), 22.5 (s, NCC6H4CH3), 14.6 (d, 1JP-C ) 30 Hz, PMe3),
9.3 (s, C5Me5). 31P{1H} NMR (CD2Cl2): δ -34.1. 19F NMR (CD2Cl2):
δ -77.0. IR (KBr): 3054 (s), 2980 (s), 2918 (s), 2247 (w), 1603 (s),
1571 (s), 1503 (m), 1460 (s), 1261 (s), 1148 (s), 1065 (m), 1030 (s),
956 (s), 856 (w), 819 (m), 740 (s), 638 (s) cm-1. Anal. Calcd for C28H36-
NF3IrPO3S: C, 45.03; H, 4.86; N, 1.88. Found: C, 44.68; H, 4.94; N,
1.84.
[Cp*(PMe3)Ir(Ph)NCC6H5]+OTF- (10b). The procedure for the
synthesis of 10a was followed using 76.0 mg of 2 and 12.4 mg of
benzonitrile. The product was isolated as a light green solid after
crystallization from a concentrated methylene chloride solution layered
with diethyl ether. Yield: 47 mg, 53%. 1H NMR (CD2Cl2, 500 MHz):
δ 7.83 (m, 2H, NCC6H5), 7.68 (m, 2H, NCC6H5), 7.52 (m, 1H,
NCC6H5), 7.27 (m, 2H, o-C6H5), 7.10 (m, 2H, m-C6H5), 7.04 (m, 1H,
5
4
p-C6H5), 1.77 (d, 3H, JP-H ) 2 Hz, CH3CN), 1.69 (d, 15H, JP-H
)
2 Hz, C5Me5), 1.56 (d, 9H, JP-H ) 11 Hz, PMe3). 13C{1H} NMR
(CD2Cl2, 125 MHz): δ 137.4 (s, p-C6H5), 135.2 (s, p-NCC6H5) 133.7
(d, JP-C ) 14 Hz, i-C6H5), 133.2 (s, o-NCC6H5), 129.9 (s, m-C6H5),
128.7 (s, m-NCC6H5), 123.3 (s, o-C6H5), 119.4 (s, NCC6H5), 109.6 (s,
2
2
2
1
i-NCC6H5), 96.1 (d, JP-C ) 3 Hz, C5Me5), 14.0 (d, JP-C ) 40 Hz,
PMe3), 8.70 (s, C5Me5). 31P{1H} NMR (CD2Cl2): δ -34.0. 19F NMR
(CD2Cl2): δ -77.0. IR (KBr): 3066 (m), 2990 (m), 2970 (m), 2918
(m), 2291 (w), 2228 (w), 1571 (m), 1464 (m), 1428 (m), 1386 (m),
1272 (s), 1224 (s), 1151 (s), 1031 (s), 961 (m), 763 (s), 686 (m), 638
(m), 572 (m), 517 (m) cm-1. HRMS (FAB, nitrobenzyl alcohol) m/z
for [C26H34NPIr]+: calcd 584.2058, obsd 584.2045. Anal. Calcd for
C26H34NF3IrPO3S: C, 44.25; H, 4.59; N, 1.91. Found: C, 43.76; H,
4.90; N, 1.78.
2
CF3), 138.7 (d, JP-C ) 13 Hz, i-C6H5), 128.3 (s, o-C6H5), 127.0 (s,
m-C6H5), 126.1 (s, C6H4CF3), 125.3 (q, 3JF-C ) 3 Hz, C6H4CF3), 122.4
(s, p-C6H5), 109.2 (d, 2JP-C ) 2 Hz, C5Me4CH2), 97.3 (s, C5Me4CH2),
2
93.3 (s, C5Me4CH2), 87.0 (d, JP-C ) 12 Hz, C5Me4CH2), 83.4 (s,
3
1
C5Me4CH2), 36.6 (d, JP-C ) 1 Hz, C5Me4CH2), 13.8 (d, JP-C ) 30
Hz, PMe3), 10.4 (s, C5Me4CH2), 10.0 (s, C5Me4CH2), 9.5 (s, C5Me4-
CH2), 8.3 (d, JP-C ) 2 Hz, C5Me4CH2), CF3 not observed. 31P{1H}
3
NMR (THF-d8): δ -33.72. 19F NMR (THF-d8): δ -59.4. IR (KBr):
3044 (m), 2974 (m), 2905 (m), 2868 (w), 1611 (m), 1568 (m), 1528
(m), 1404 (w), 1325 (s), 1308 (s), 1281 (m), 1157 (s), 1117 (s), 1065
(s), 1018 (m), 952 (m), 847 (m), 737 (m), 705 (m) cm-1. MS (EI):
m/z 651 (M+). Anal. Calcd for C27H32NF3PIr: C, 49.83; H, 4.96; N,
2.15. Found: C, 50.12; H, 5.14; N, 2.02.
[Cp*(PMe3)Ir(Ph)NCC6H4CF3]+OTF- (10c). The procedure for
the synthesis of 10a was followed using 120 mg of 2 and 33 mg of
p-trifluorotolunitrile. Nitrile adduct 10c was crystallized by layering a
concentrated methylene chloride solution with pentane to afford clear,
light green crystals. Yield: 60 mg, 40%. 1H NMR (CD2Cl2, 500 MHz):
δ 8.07 (d, 2H, JH-H ) 9 Hz, NCC6H4CF3), 7.93 (d, 2H, JH-H ) 8 Hz,
NCC6H4CF3), 7.26 (m, 2H, o-C6H5), 7.12 (m, 2H, m-C6H5), 7.05 (m,
[Ph(PMe3)Ir(C5Me4CH2C(C6H4CF3)NH)]+OTf- (13). To a stirred
solution of 12 (70.0 mg, 0.11 mmol) in methylene chloride (5 mL) at
-40 °C was added a solution of HOTf (16.1 mg, 0.11 mmol) in
methylene chloride (0.5 mL). Upon warming, the clear solution turned
from orange to yellow. The solvent was removed under reduced
pressure. The yellow solid was redissolved in methylene chloride,
filtered, concentrated, layered with pentane, and cooled to -40 °C.
Compound 12, isolated as a microcrystalline yellow solid, was rinsed
4
2
1H, p-C6H5), 1.78 (d, 15H, JP-H ) 2 Hz, C5Me5), 1.58 (d, 9H, JP-H
) 11 Hz, PMe3). 13C{1H} NMR (125 MHz, CD2Cl2): δ 137.9 (s,
p-C6H5), 136.4 (q, JF-C ) 34 Hz, NCC6H4CF3 (i to CF3)), 134.9 (s,
NCC6H4CF3 (o to CN)), 134.2 (d, i-C6H5, 13 Hz), 129.1 (s, o-C6H5),
2
3
127.3 (q, JF-C ) 4 Hz, NCC6H4CF3 (o to CF3)), 123.6 (s, m-C6H5),
123.5 (q, 1JF-C ) 270 Hz, NCC6H4CF3), 118.6 (s, NCC6H4CF3), 114.1
(s, NCC6H4CF3 (i to CN)), 97.0 (d, 2JP-C ) 3 Hz, C5Me5), 14.6 (1JP-C
) 40 Hz, PMe3), 9.23 (s, C5Me5). 31P{1H} NMR (CD2Cl2): δ -34.2.
19F NMR (CD2Cl2): δ -62.1 (NCC6H4CF3), -77.0 (OSO3CF3). IR
(KBr): 3102 (w), 3060 (s), 2992 (s), 2919 (s), 2249 (w), 1613 (m),
1570 (s), 1503 (m), 1461 (m), 1409 (m), 1384 (s), 1321 (s), 1268 (s),
1
with pentane (3 × 5 mL) and dried in vacuo. Yield: 53 mg, 62%. H
NMR (CD2Cl2): δ 10.74 (s, 1H, N-H), 8.02 (d, J ) 8 Hz, 2H, C6H4-
CF3), 7.77 (d, J ) 8 Hz, 2H, C6H4CF3), 7.03 (m, 5H, C6H5), 3.99 (d,
J ) 20 Hz, 1H, C5Me4CHaHb), 3.78 (d, J ) 19 Hz, 1H, C5Me4HaHb),
2.16 (s, 3H, C5Me4CH2), 1.92 (d, 4JP-H ) 2 Hz, 3H, C5Me4CH2), 1.68
(d, 4JP-H ) 4 Hz, 3H, C5Me4CH2), 1.51 (d, 2JP-H ) 10 Hz, 9H, PMe3),
1147 (s), 1064 (s), 1031 (s), 952 (s), 853 (s), 742 (s), 637 (s) cm-1
.

4818 Inorganic Chemistry, Vol. 38, No. 21, 1999
Tellers et al.
1.41 (s, 3H, C5Me4CH2). 13C{1H} NMR (CD2Cl2): δ 199.4 (d, 3JP-C
)
previously.44 Non-hydrogen atoms were refined anisotropically. Hy-
drogen atoms were included in calculated positions but not refined.
The function minimized in the full-matrix least-squares refinement was
∑w(|Fo| - |Fc|)2. The weighting scheme was based on counting statistics
and included a factor to downweight the intense reflections. Data
collection and refinement parameters for 6a and 12 can be found in
Table 1, while those for 8 can be found in the Supporting Information.
The positional and thermal parameters for the non-hydrogen atoms and
the complete list of intramolecular distances and angles for all
structurally characterizated compounds are given in the Supporting
Information.45
6a. Crystals of 6a were obtained by slow evaporation of a diethyl
ether solution at -40 °C. On the basis of the systematic absences of
hkl, h + k * 2n, and h0l, l * 2n, packing considerations, a statisical
analysis of intensity distribution, and the successful solution and
refinement of the struture, the space group was determined to be C2/c
(no. 15). No decay correction was applied. An empirical absorption
correction (Tmax ) 0.920, Tmin ) 0.798) was applied using XPREP.42
8. Crystals of 8 were obtained by slow diffusion of pentane into a
concentrated solution of 8 at room temperature. On the basis of the
systematic absence of h0l, h + 1 * 2n, and 0k0, k * 2n, the space
group was uniquely determined to be P21/n (no. 14). No decay
2
6 Hz, CdN), 138.1 (s, C6H4CF3), 137.5 (s, C6H4CF3), 135.1 (d, JP-C
) 15 Hz, i-C6H5), 134.0 (q, 2JF-C ) 32 Hz, C6H4CF3), 128.7 (s, o-C6H5),
128.5 (s, m-C6H5), 126.7 (q, 3JF-C ) 4 Hz, C6H4CF3), 123.5 (s, p-C6H5),
2
103.2 (d, JP-C ) 3 Hz, C5Me4CH2), 99. 7 (s, C5Me4CH2), 95.2 (d,
2JP-C ) 12 Hz, C5Me4CH2), 86.8 (s, C5Me4CH2), 85.6 (s, C5Me4CH2),
1
34.5 (s, C5Me4CH2), 15.8 (d, JP-C ) 40 Hz, PMe3), 10.3 (s, C5Me4-
3
CH2), 9.3 (s, C5Me4CH2), 9.2 (s, C5Me4CH2), 8.05 (d, JP-C ) 2 Hz,
C5Me4CH2), CF3 not observed. 31P{1H} NMR (CD2Cl2): δ -37.9. 19F
NMR (CD2Cl2): δ -61.5 (C6H4CF3), -77.0 (OSO3CF3). IR (KBr):
3495 (m), 3186 (m), 3055 (m), 2974 (m), 2916 (m), 1619 (w), 1570
(m), 1524 (m), 1422 (m), 1325 (s), 1281 (s), 1251 (s), 1224 (m), 1162
(s), 1131 (s), 1068 (s), 1030 (m), 955 (m), 737 (m), 637 (s) cm-1
.
Anal. Calcd for C28H33F6IrNO3PS: C, 42.00; H, 4.15; N, 1.75. Found:
C, 41.81; H, 4.09; N, 1.54.
[Cp*(PMe3)Ir(Ph)OH2]OTf (16). Complex 16 could not be isolated.
A procedure similar to that reported for the synthesis of Cp*(PMe3)-
Ir(Ph)OH2]F*nH2O was followed.39 An NMR tube was charged with
2 (31 mg, 0.049 mmol), THF-d8 (452 mg), and H2O (180 µL, 200
equiv). The tube was sealed in vacuo. Spectroscopic data were recorded
1
after 24 h at ambient temperature. H NMR (THF-d8, 500 MHz): δ
7.14 (d, J ) 7 Hz, 2H, o-C6H5), 6.93 (t, J ) 8 Hz, 2H, m-C6H5), 6.79
(t, J ) 7 Hz, 1H, p-C6H5), 4.39 (s, H2O), 1.56 (d, 4JP-C ) 2 Hz, 15H,
C5Me5), 1.42 (d, 2JP-C ) 11 Hz, 9H, PMe3). 13C{1H} NMR (THF-d8):
δ 144.4 (d, 2JP-C ) 14 Hz, i-C6H5), 137.6 (s, o-C6H5), 128.4 (s, m-C6H5),
123.0 (s, p-C6H5), 93.4 (d, 2JP-C ) 3 Hz, C5Me5), 13.9 (d, 1JP-C ) 39
Hz, PMe3), 9.1 (s, C5Me5). 31P{1H} NMR (THF-d8): δ -26.7. 19F NMR
(THF-d8): δ -75.5.
correction was applied. An empirical absorption correction (Tmax
)
0.862, Tmin ) 0.554) was applied using SADABS.43
12. Crystals of 12 were obtained from a concentrated toluene solution
of 12 after 7 d. On the basis of the systematic absences of hkl, h + k
* 2n, and h01, l * 2n, packing considerations, a statistical analysis of
intensity distribution, and the successful solution and refinement of
the structure, the space group was determined to be C2/c (no. 15). No
decay correction was applied. An empirical absorption correction (Tmax
) 0.862, Tmin ) 0.375) was applied using SADABS.43
Reaction of Iridium Carboxamides 6a-d with HCl. In a typical
reaction, HCl (1 equiv, 1 M in Et2O) was added dropwise to a stirred
solution of the iridium carboxamide in benzene (3 mL) at room
temperature. Upon addition, the solution turned from tan to orange,
and a white precipitate formed. The orange solution was decanted, and
the remaining solid was rinsed with cold toluene (3 × 1 mL). The
identity of the free amides was confirmed by comparison with authentic
Acknowledgment. We acknowledge the National Science
Foundation (Grant No. CHE-963374) for financial support of
this work. J.C.M.R. acknowledges support through a NATO
Postdoctoral Fellowship administered through the Deutscher
Akademischer Austauschdienst (DAAD). We thank Dr. Fred
Hollander and Dr. Ryan Powers of the University of Californias
Berkeley CHEXRAY facility for structure determinations.
1
samples using gas chromatography and H NMR spectroscopy. Yield
from 6a: 10.6 mg, 73%. Yield from 6b: 7.9 mg, 61%. Yield from 6c:
10.5 mg, 57%. Yield from 6d: 2.6 mg, 38%.
X-ray Structure Determinations. X-ray diffraction measurements
were made on a Siemens SMART diffractometer40 with a CCD area
detector. The crystal was mounted on a glass fiber using Paratone N
hydrocarbon oil. Cell constants and an orientation matrix for data
collection were obtained from a least-squares refinement using the
measured positions of reflections in the range 3.00° < 2θ < 45.00°.
Data were integrated using the program SAINT41 with box parameters
of 1.6 × 1.6 × 0.6 to a maximum 2θ value of 52.1°. No decay
correction was applied. An empirical absorption correction based on
comparison of redundant and equivalent data and an ellipsoidal model
of the absorption surface was applied using the program XPREP42 or
SADABS.43 The structures were solved using methods described
Supporting Information Available: ORTEP diagrams and tables
giving positional and thermal parameters for the non-hydrogen atoms
and the complete list of intramolecular distances and angles for
Cp*(PMe3)IrPh[NHC(O)C6H4CH3] (6a), Cp*(PMe3)Ir[NdCdC(Ph)2]-
Ph (8), and [Ph(PMe3)Ir[C5Me4CH2C(C6H4CF3)N]] (12). This material
is available free of charge via the Internet at http://pubs.acs.org.
IC9907157
(42) XPREP (v 5.03) Part of the SHELXTL Crystal Structure Determination
Package, Siemens Industrial Automation, Inc., Madision, WI, 1995.
(43) SADABSsSiemens Area Detector ABSsorption correction program,
George Sheldrick, 1996. Advance copy, private communication.
(44) Kaplan, A. W.; Polse, J. L.; Ball, G. E.; Andersen, R. A.; Bergman,
R. G. J. Am. Chem. Soc. 1998, 120, 11649-11662.
(39) Veltheer, J. E.; Burger, P.; Bergman, R. G. J. Am. Chem. Soc., 1995,
117, 12478-12488.
(40) SMART Area-Detector Software Package; Siemens Industrial Auto-
mation, Inc., Madision, WI, 1995.
(41) SAINT: SAX Area-Detector Integration Program, V4.024, Siemens
Industrial Automation, Inc., Madison, WI, 1995.
(45) Selected intramolecular bond angles and distances for compounds 6a
and 12 can be found in Tables 2 and 3, respectively.