Synthesis, structure, and reactivity of iridacyclohexadienone and iridaphenol complexes

Article abstract of DOI:10.1021/ja971721+

Iridacyclohexadienone complexes, a new class of unsaturated six-membered metallacycles, have been synthesized, and their reactions with acids have been investigated. Treatment of CH=C(Me)-CH=C(Me)-CH=Ir(PMe₃)₃ ('iridabenzene' 1) with nitrous oxide produces the iridacyclohexadienone complex CH=C(Me)-CH=C-(Me)-C(O)-Ir(PMe₃)₃(H) (2), which upon stirring in diethyl ether solution slowly isomerizes to (1,2,5-η-2,4-dimethylpenta-1,3-dien-5-oyl)Ir(PMe₃)₃ (3). Treatment of 2 with methyl trifluoromethanesulfonate leads to removal of the metal hydride and production of CH=C(Me)-CH=C(Me)-C(O)-Ir(PMe₃)₃(O₃SCF₃) (4). In acetone solution, 4 forms an equilibrium mixture with a ring-contracted iridacyclopentadiene isomer, [CH=C(Me)-CH=C(Me)-Ir(PMe₃)₃(CO)]⁺O₃SCF₃^- (5). Treatment of 4 with trimethylphosphine generates the tetrakis(trimethylphosphine)iridncyclohexadienone complex [CH=C(Me)-CH=C(Me)-C(O)-Ir(PMe₃)4]⁺O₃SCF₃^- (6). Iridacyclohexadienone 2 reacts with trifluoromethanesulfonic acid to produce the iridacyclopentene complex [CH₂-C(Me)=CH-CH(Me)-Ir(PMe₃)₃(CO)]⁺O₃SCF₃^- (7). In contrast, treatment of iridacyclohexadienones 4 and 6 with trifluoromethanesulfonic acid leads to protonation of oxygen and production of the corresponding 'iridaphenols' 8 and 10. When 4 is treated with trifluoroacetic acid, an iridaphenol product is again generated (compound 9), but in this case the phenol proton forms an intramolecular hydrogen bond with the carbonyl oxygen of the trifluoroacetate ligand. The ring protons in compounds 8, 9, and 10 exhibit downfield ¹H NMR chemical shifts consistent with aromatic character. Compounds 3, 4, 6, 7, 8, and 9 have been structurally characterized by single-crystal X-ray diffraction.

Full text of DOI:10.1021/ja971721+

J. Am. Chem. Soc. 1997, 119, 8503-8511
8503
Synthesis, Structure, and Reactivity of Iridacyclohexadienone
and Iridaphenol Complexes1
John R. Bleeke* and Robert Behm
Contribution from the Department of Chemistry, Washington UniVersity,
St. Louis, Missouri 63130
ReceiVed May 27, 1997X
Abstract: Iridacyclohexadienone complexes, a new class of unsaturated six-membered metallacycles, have been
synthesized, and their reactions with acids have been investigated. Treatment of CHdC(Me)sCHdC(Me)sCHdIr-
(PMe3)3 (“iridabenzene” 1) with nitrous oxide produces the iridacyclohexadienone complex CHdC(Me)sCHdC-
(Me)sC(O)sIr(PMe3)3(H) (2), which upon stirring in diethyl ether solution slowly isomerizes to (1,2,5-η-2,4-
dimethylpenta-1,3-dien-5-oyl)Ir(PMe3)3 (3). Treatment of 2 with methyl trifluoromethanesulfonate leads to removal
of the metal hydride and production of CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)3(O3SCF3) (4). In acetone solution,
4 forms an equilibrium mixture with a ring-contracted iridacyclopentadiene isomer, [CHdC(Me)sCHdC-
(Me)sIr(PMe3)3(CO)]+O3SCF3- (5). Treatment of 4 with trimethylphosphine generates the tetrakis(trimethylphos-
phine)iridacyclohexadienone complex [CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)4]+O3SCF3- (6). Iridacyclohexa-
dienone 2 reacts with trifluoromethanesulfonic acid to produce the iridacyclopentene complex [CH2sC(Me)d
-
CHsCH(Me)sIr(PMe3)3(CO)]+O3SCF3 (7). In contrast, treatment of iridacyclohexadienones 4 and 6 with
trifluoromethanesulfonic acid leads to protonation of oxygen and production of the corresponding “iridaphenols” 8
and 10. When 4 is treated with trifluoroacetic acid, an iridaphenol product is again generated (compound 9), but in
this case the phenol proton forms an intramolecular hydrogen bond with the carbonyl oxygen of the trifluoroacetate
1
ligand. The ring protons in compounds 8, 9, and 10 exhibit downfield H NMR chemical shifts consistent with
aromatic character. Compounds 3, 4, 6, 7, 8, and 9 have been structurally characterized by single-crystal X-ray
diffraction.
Introduction
synthesizing iridacyclohexadiene complexes which can, in turn,
be dehydrogenated to “iridabenzenes”.1 These novel metalla-
cycles exhibit delocalized π-bonding and aromatic character.
We now report that treatment of iridabenzenes with nitrous
oxide, an oxygen atom source, leads to the production of another
new class of unsaturated six-membered metallacycles, iridacy-
clohexadienones. These molecules exhibit a variety of interest-
ing reactions, including reversible ring contraction and conver-
sion to “iridaphenols”.
Six-membered metallacycles, particularly those containing
unsaturated rings, have been studied to a much lesser extent
than their five-membered ring counterparts.2 This situation is
due in large part to the fact that few general synthetic pathways
to unsaturated six-membered metallacycles have been developed.
We have, therefore, embarked on a program to investigate the
use of pentadienide and heteropentadienide reagents as possible
synthons for the production of unsaturated six-membered
metallacycles. Using this approach, we have succeeded in
Results and Discussion
X Abstract published in AdVance ACS Abstracts, August 15, 1997.
(1) Metallacyclohexadiene and Metallabenzene Chemistry. 14. For
previous papers in this series, see: (a) Bleeke, J. R.; Peng, W.-J.
Organometallics 1987, 6, 1576. (b) Bleeke, J. R.; Xie, Y.-F.; Peng, W.-J.;
Chiang, M. J. Am. Chem. Soc. 1989, 111, 4118. (c) Bleeke, J. R.; Peng,
W.-J.; Xie, Y.-F.; Chiang, M. Y. Organometallics 1990, 9, 1113. (d) Bleeke,
J. R.; Haile, T.; Chiang, M. Y. Organometallics 1991, 10, 19. (e) Bleeke,
J. R.; Xie, Y.-F.; Bass, L.; Chiang, M. Y. J. Am. Chem. Soc. 1991, 113,
4703. (f) Bleeke, J. R.; Bass, L. A.; Xie, Y.-F.; Chiang, M. Y. J. Am. Chem.
Soc. 1992, 114, 4213. (g) Bleeke, J. R.; Ortwerth, M. F.; Chiang, M. Y.
Organometallics 1992, 11, 2740. (h) Bleeke, J. R.; Haile, T.; New, P. R.;
Chiang, M. Y. Organometallics 1993, 12, 517. (i) Bleeke, J. R.; Rohde, A.
M.; Boorsma, D. W. Organometallics 1993, 12, 970. (j) Bleeke, J. R.; Behm,
R.; Xie, Y.-F.; Clayton, Jr., T. W.; Robinson, K. D. J. Am. Chem. Soc.
1994, 116, 4093. (k) Bleeke, J. R.; Behm, R.; Xie, Y.-F.; Chiang, M. Y.;
Robinson, K. D.; Beatty, A. M. Organometallics 1997, 16, 606. (l) Bleeke,
J. R.; Behm, R.; Beatty, A. M. Organometallics 1997, 16, 1103. (m) Bleeke,
J. R.; Blanchard, J. M. B. J. Am. Chem. Soc. 1997, 119, 5443. See also:
Bleeke, J. R. Acc. Chem. Res. 1991, 24, 271.
A. Treatment of Iridabenzene 1 with Nitrous Oxide. As
shown in Scheme 1, treatment of CHdC(Me)sCHdC(Me)s
CHdIr(PMe3)3 (iridabenzene 1) with nitrous oxide (N2O) results
in the synthesis of an iridacyclohexadienone complex, CHdC-
(Me)sCHdC(Me)sC(O)sIr(PMe3)3(H) (2). Although the
detailed mechanism of this reaction is not known, metallaep-
oxide A (Scheme 1) appears to be a likely intermediate.
Activation of the C5sH bond in A by the iridium center would
lead to the observed product.3
The 1H NMR spectrum of 2 shows downfield signals for H1
(δ 8.16) and H3 (δ 6.76) and an upfield signal for the iridium
hydride (δ -10.80). The H1 signal is a broad doublet (J )
(3) Intermediate A can also be viewed as an (η2-aldehyde)metal complex,
and dissociation of the aldehyde CO bond from the iridium center may
precede C5-H bond activation.
(2) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles
and Applications of Organotransition Metal Chemistry; University Science
Books: Mill Valley, CA, 1987; pp 512-513.
S0002-7863(97)01721-6 CCC: $14.00 © 1997 American Chemical Society

8504 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bleeke and Behm
Scheme 1
20.3 Hz) due to coupling to the 31P nucleus of the adjacent PMe3
ligand in the ring plane, Pa (see Scheme 1),4 while the hydride
signal is split into a doublet (J ) 114.9 Hz) of triplets (J )
20.5 Hz), as a result of coupling to the trans 31P nucleus (Pc)
and the cis 31P nuclei (Pa and Pb), respectively. In the 13C{1H}
NMR spectrum, the carbonyl carbon (C5) resonates far down-
field at δ 230.4 and is split into a doublet (J ) 98.1 Hz) by
trans 31P nucleus Pa. The other four ring carbon signals appear
in the normal olefinic region of the spectrum (between δ 127.5
and δ 140.6). The C1 signal is a doublet (J ) 80.7 Hz) as a
result of strong coupling to trans 31P nucleus Pb. The 31P{1H}
spectrum consists of three separate but coupled signals, due to
the three inequivalent PMe3 ligands.
Figure 1. ORTEP drawing of (1,2,5-η-2,4-dimethylpenta-1,3-dien-5-
oyl)Ir(PMe3)3 (3). Selected bond distances (Å): Ir1-P1, 2.310(3); Ir1-
P2, 2.297(2); Ir1-P3, 2.360(2); Ir1-C1, 2.135(7); Ir1-C2, 2.143(6);
Ir1-C5, 2.063(6); O1-C5, 1.235(8); C1-C2, 1.464(9); C2-C3, 1.481-
(9); C2-C6, 1.533(10); C3-C4, 1.300(10); C4-C5, 1.508(9); C4-
C7, 1.531(10). Selected bond angles (deg): P1-Ir1-P2, 106.4(1); P1-
Ir1-P3, 98.1(1); P2-Ir1-P3, 93.7(1); P1-Ir1-C1, 103.0(2); P2-Ir1-
C1, 148.2(2); P3-Ir1-C1, 93.9(2); P1-Ir1-C2, 141.4(2); P2-Ir1-
C2, 108.4(2); P3-Ir1-C2, 95.8(2); P1-Ir1-C5, 87.8(2); P2-Ir1-
C5, 83.8(2); P3-Ir1-C5, 174.0(2); C1-Ir1-C2, 40.0(2); C1-Ir1-
C5, 85.5(3); C2-Ir1-C5, 79.9(3); Ir1-C1-C2, 70.3(4); Ir1-C2-C1,
69.7 (4); Ir1-C2-C3, 107.8(4); C1-C2-C3, 114.6(6); C2-C3-C4,
121.7(6); C3-C4-C5, 114.2(6); Ir1-C5-O1, 128.7(5); Ir1-C5-C4,
113.3(4); O1-C5-C4, 118.0(6).
Although compound 2 can be crystallized and is indefinitely
stable in the solid state under nitrogen, it slowly isomerizes in
diethyl ether solution to (1,2,5-η-2,4-dimethylpenta-1,3-dien-
5-oyl)Ir(PMe3)3, 3 (Scheme 1). It is interesting to note that the
overall conversion of compound 1 to compound 3 involves
metal-mediated migration of a hydrogen from C5 to C1. In
the 1H NMR spectrum of 3, only the H3 signal appears
downfield (δ 7.21); the two H1 resonances are found at δ 2.16
and 1.87. In the 13C{1H} NMR spectrum, the carbonyl carbon
signal (C5) remains far downfield at δ 237.3 and is split into a
wide doublet (JC-P ) 101.3 Hz). The signals for ring carbons
C3 and C4 likewise remain in the olefinic region at δ 166.7
and 144.7, respectively, but the signals for C2 and C1 are shifted
upfield to δ 46.9 and 37.8, respectively, as a result of their
π-coordination to the iridium center. As expected, they exhibit
moderate coupling (JC-P ) 36.0 and 33.5 Hz, respectively) to
31P nuclei in the PMe3 ligands. The 31P{1H} NMR spectrum
consists of three separate but coupled signals, due to the three
inequivalent PMe3 ligands.
Scheme 2
are occupied by C1, C2, and C5 of the penta-1,3-dien-5-oyl
ligand and the three PMe3 phosphorus atoms. The σ-bonded
carbon atom, C5, lies approximately trans to P3 and cis to P1
and P2. The π-bonded carbons, C1 and C2, reside nearly in
the Ir-P1-P2 plane and experience substantial back-bonding
as evidenced by the relatively long C1-C2 distance of 1.464-
(9) Å. In fact, the Ir-C1-C2 interaction approximates a
metallacyclopropane in which the iridium center is formally Ir-
(III). The carbon-carbon bond distances in the remainder of
the penta-1,3-dien-5-oyl ligand show the expected long-short-
long pattern, and the C5-O1 distance of 1.235(8) Å is normal
for a carbon-oxygen double bond.
B. Treatment of Iridacyclohexadienone 2 with Methyl
Triflate. When iridacyclohexadienone 2 is treated with methyl
trifluoromethanesulfonate (methyl triflate) in diethyl ether at
-10 °C, the hydride ligand is cleanly removed (as CH4) and
triflate coordinates to the iridium center (see Scheme 2). The
31P{1H} NMR spectrum of product 4 consists of a doublet
(intensity 2) and a triplet (intensity 1), indicating a meridional
arrangement of phosphine ligands and mirror plane symmetry.
The position of the triflate group (trans to C5) is clear from the
The structure of 3 has been confirmed by a single-crystal
X-ray diffraction study.5,6 The ORTEP drawing is reproduced
in Figure 1, while key bond distances and angles are reported
in the figure caption. Compound 3 can perhaps best be viewed
as a distorted octahedron in which the six coordination sites
(4) Similar large H-P couplings between ring R-protons and adjacent
phosphines in the ring plane have been observed in (η6-iridabenzene)Mo-
(CO)3 complexes (see ref 1f).
(5) Several other (1,2,5-η-penta-1,3-dien-5-oyl)metal complexes have
been previously characterized by X-ray diffraction: (a) Brammer, L.;
Crocker, M.; Dunne, B. J.; Green, M.; Morton, C. E.; Nagle, K. R.; Orpen,
A. G. J. Chem. Soc., Chem. Commun. 1986, 1226. (b) Crocker, M.; Dunne,
B. J.; Green, M.; Orpen, A. G. J. Chem. Soc. Dalton Trans. 1991, 1589.
(c) Garlaschelli, L.; Malatesta, M. C.; Panzeri, S. Organometallics 1987,
6, 63.
(6) (η5-Penta-1,3-dien-5-oyl)metal complexes have been postulated as
intermediates in the photolytic synthesis of hydroxyferrocenes from (η5-
cyclopentadienyl)(CO)2Fe(η1-buta-1,3-dienyl) complexes: Yongskulrote,
W.; Bramlett, J. M.; Mike, C. A.; Durham, B.; Allison, N. T. Organome-
tallics 1989, 8, 556.

Iridacyclohexadienone and Iridaphenol Complexes
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8505
Scheme 3
Scheme 4
Figure 2. ORTEP drawing of CHdC(Me)sCHdC(Me)sC(O)sIr-
(PMe3)3(O3SCF3) (4). Two independent molecules crystallized in the
asymmetric unit; selected bond distances and angles for molecule 1
are reported. Selected bond distances (Å): Ir1-P1, 2.347(6); Ir1-P2,
2.349(5); Ir1-P3, 2.405(5); Ir1-O2, 2.360(12); Ir1-C1, 2.052(17);
Ir1-C5, 1.987(19); O1-C5, 1.197(25); C1-C2, 1.332(26); C2-C3,
1.438(31); C2-C6, 1.492(32); C3-C4, 1.340(31); C4-C5, 1.523(27);
C4-C7, 1.492(32). Selected bond angles (deg): P1-Ir1-P2, 170.3-
(2); C1-Ir1-C5, 92.9(7); Ir1-C1-C2, 129.1(15); C1-C2-C3, 119.9-
(18); C2-C3-C4, 132.6(20); C3-C4-C5, 122.5(19); Ir1-C5-O1,
122.6(15); Ir1-C5-C4, 122.7(13); O1-C5-C4, 114.4(18).
signals, consistent with a facial arrangement of PMe3 ligands.
In the infrared spectrum of 5, the carbonyl CtO stretching band
is observed at 2054 cm-1
.
It is interesting to note that treatment of the tris(PEt3) analogue
of compound 1, CHdC(Me)sCHdC(Me)sCHdIr(PEt3)3, with
N2O leads to the formation of a stable iridacyclopentadiene-
carbonyl product (see Scheme 3).1j,k In this reaction, no
intermediates have been isolated, but the key step is apparently
a ring contraction similar to that shown in Scheme 2, except
accompanied by PEt3 loss rather than triflate dissociation. The
PEt3 extrusion probably results from the unfavorable steric
interactions of three mutually-cis-PEt3 ligands in the iridacy-
clohexadienone intermediate.
13C{1H} NMR spectrum, where the C5 signal is a singlet. In
contrast, the C1 signal is a strongly-coupled doublet (JC-P
)
78.2 Hz), due to C1’s trans relationship to a PMe3 ligand. The
1H and 13C NMR chemical shifts in 4 are similar to those in
precursor 2, although H1 and C1 are shifted somewhat down-
field to δ 9.25 and 156.7, respectively, while carbonyl carbon
C5 is shifted upfield to δ 188.7.
The solid state structure of 4 has been confirmed by X-ray
diffraction and is shown in Figure 2; key bond distances and
angles are reported in the figure caption. As expected, the
bonding around the metallacycle in 4 is localized with double
bonds between C1 and C2 and between C3 and C4 and single
bonds between C2 and C3 and between C4 and C5. The
carbonyl C5-O1 bond distance of 1.197(25) Å is typical for a
carbon-oxygen double bond. The internal angles within the
six-membered metallacycle sum to 719.7°, very close to the
value of 720° required for a planar hexagon, and range from
92.9(7)° for C1-Ir1-C5 to 132.6(20)° for C2-C3-C4.
When compound 4 is dissolved in acetone, it establishes an
equilibrium with the iridacyclopentadiene-carbonyl compound
5 (see Scheme 2). This process involves dissociation of the
labile triflate ligand and reversible “deinsertion” of the carbonyl
group. At room temperature, the equilibrium slightly favors 4
(the ratio of compound 4 to compound 5 is approximately 60:
40), but at 60 °C, equal quantities of 4 and 5 are observed by
NMR. Upon cooling, the equilibrium shifts back toward 4, and
at -30 °C, pure 4 crystallizes from the mixture as yellow blocks.
The 1H NMR spectrum of 5 includes two downfield signals
at δ 6.44 and 6.31, due to H3 and H1, respectively. In the
13C{1H} NMR spectrum of 5, there are five downfield signals
(δ 124.2-171.8), and carbons C1, C4, and C5 (the carbonyl
carbon) all exhibit strong C-P coupling due to their trans
relationships to PMe3 ligands. C5’s very large JC-P value of
110.7 Hz is typical for a metal-bound carbonyl ligand.7 The
31P{1H} NMR spectrum consists of three doublet-of-doublet
C. Treatment of Iridacyclohexadienone 4 with Trimeth-
ylphosphine. When iridacyclohexadienone 4 is treated with
trimethylphosphine, the tetrakis(PMe3) product 6 (see Scheme
4) is obtained.8 This reaction, like the ring contraction reaction
outlined in Scheme 2, involves dissociation of the labile triflate
ligand. Compound 6 is stable and shows no tendency to lose
PMe3 or contract to a five-membered ring in solution. The 1H
and 13C{1H} NMR spectra of 6 are very similar to those of
iridacyclohexadienone 2 (Vide supra). In particular, the signal
for H1 is found at δ 7.97 and is a doublet (J ) 19.1 Hz) due to
coupling to the cis-PMe3 ligand in the ring plane. H3 gives
rise to a singlet at δ 6.67. Ring carbons C1-C4 resonate in
the normal olefinic region of the 13C NMR spectrum (δ 129.3-
142.1), and C1 is a strongly coupled doublet (JC-P ) 73.0 Hz)
due to its trans relationship to a PMe3 ligand. Carbonyl carbon
C5 resonates at δ 220.1 and is likewise a doublet (JC-P ) 86.1
Hz). The 31P{1H} NMR spectrum of 6 consists of three
signalssa doublet of doublets, due to the two equivalent trans-
diaxial phosphines (related by mirror-plane symmetry), and two
triplets of doublets, due to the two inequivalent equatorial
phosphines.
The solid state structure of 6 has been determined by X-ray
crystallography and is shown in Figure 3; key distances and
angles are reported in the caption. The molecule resides on a
crystallographically-imposed mirror plane, which includes the
ring carbons, the iridium center, and the phosphorus atoms of
the equatorial PMe3 ligands. The metallacyclic ring in 6, like
(7) In general, the JC-P value increases with increasing s character in
the carbon hybridization.
(8) The same product is obtained when equilibrium mixtures of 4 and 5
react with PMe3.

8506 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bleeke and Behm
Figure 3. ORTEP drawing of the cation in [CHdC(Me)sCHd
Figure 4. ORTEP drawing of the cation in [CH2sC(Me)dCHsCH-
-
C(Me)sC(O)sIr(PMe3)4]+O3SCF3 (6). Two independent molecules
(Me)sIr(PMe3)3(CO)]+O3SCF3-‚1/2Me2C(O) (7). Selected bond dis-
tances (Å): Ir1-P1, 2.390(5); Ir1-P2, 2.378(5); Ir1-P3, 2.390(5); Ir1-
C1, 2.159(18); Ir1-C4, 2.159(21); Ir1-C5, 1.855(18); C1-C2,
1.514(30); C2-C3, 1.279(33); C2-C6, 1.444(29); C3-C4, 1.544(27);
C4-C7, 1.563(28); C5-O1, 1.143(25). Selected bond angles (deg):
P2-Ir1-C5, 169.7(6); C1-Ir1-C4, 80.8(7); Ir1-C1-C2, 110.7(14);
C1-C2-C3, 117.7(18), C1-C2-C6, 119.2(21); C3-C2-C6, 123.1-
(22); C2-C3-C4, 121.8(20); Ir1-C4-C3, 107.7(14); Ir1-C4-C7,
118.3(15); C3-C4-C7, 107.4(14); Ir1-C5-O1, 175.8(21).
crystallized in the asymmetric unit; selected bond distances and angles
for molecule 1 are reported. Selected bond distances (Å): Ir1-P1,
2.368(5); Ir1-P2, 2.437(6); Ir1-P3, 2.405(4); Ir1-C1, 2.064(18); Ir1-
C5, 2.082(21); O1-C5, 1.214(24); C1-C2, 1.383(28); C2-C3, 1.456-
(31); C2-C6, 1.504(26); C3-C4, 1.319(26); C4-C5, 1.516(26); C4-
C7, 1.535(35). Selected bond angles (deg): P1-Ir1-P1a, 166.9(2);
C1-Ir1-C5, 90.8(8); Ir1-C1-C2, 128.3(17); C1-C2-C3, 122.1(17);
C2-C3-C4, 131.7(18); C3-C4-C5, 122.7(19); Ir1-C5-O1, 122.3-
(15); Ir1-C5-C4, 124.4(13); O1-C5-C4, 113.3(19).
that in compound 4 (Vide supra), exhibits localized bonding
and the expected short-long-short-long alternation in carbon-
carbon bond lengths. The C5-O1 bond distance of 1.214(24)
Å is a normal carbon-oxygen double bond length. The internal
angles within the metallacycle range from 90.8(8)° (C1-Ir1-
C5) to 131.7(18)° (C2-C3-C4) and sum to 720°, as required
for a planar hexagon.
Scheme 5
It is interesting to compare the iridium-ring carbon distances
in compounds 4 and 6. While the Ir1-C1 distances are very
similar (2.052(17) Å in 4 vs 2.064(18) Å in 6), the Ir1-C5
distances are quite different. In compound 4, this distance is
1.987(19) Å, but in 6, it lengthens significantly to 2.082(21) Å.
This lengthening is probably due to the trans-PMe3 ligand,
which exerts a stronger trans influence on C5 than the weakly
coordinating triflate ligand.9
D. Treatment of Iridacyclohexadienone 2 with Triflic
Acid. Metallacyclohexadienone complexes can potentially serve
as synthetic precursors to metallaphenols.10 However, when
iridacyclohexadienone 2 is treated with trifluoromethanesulfonic
(triflic) acid, an iridacyclopentene-carbonyl complex, 7, is
generated instead (see Scheme 5). Although intermediates have
not been isolated in this reaction, the pathway outlined in
Scheme 5 seems reasonable. Direct protonation at C4 (or
protonation at oxygen, followed by enol-keto tautomerization)
would generate proposed intermediate C, and subsequent
migration of the metal hydride to C1 would lead to D. Triflate
dissociation and ring contraction, analogous to the conversion
of 4 to 5 (cf. Scheme 2), would generate the observed product,
7.11 Unlike compound 5, 7 does not equilibrate with a six-
membered ring-containing isomer.
1
The H NMR spectrum of compound 7 includes just one
downfield signal, a doublet (JH-P ) 7.0 Hz) at δ 5.25 due to
H3; the sp3 protons (H1’s and H4) resonate in the δ 1.83-2.55
range. In the 13C{1H} NMR spectrum, sp2 carbons C2 and C3
appear downfield at δ 145.5 and 142.2, respectively, while sp3
carbons C1 and C4 shift upfield to δ 13.4 and 20.6, respectively,
and exhibit strong coupling to the trans-PMe3 ligands. The
carbonyl carbon, C5, resonates at δ 174.9 and shows the very
strong phosphorus coupling (J ) 122.6 Hz) that is characteristic
of metal-bound carbonyl ligands.7 The 31P{1H} NMR spectrum
consists of three doublet-of-doublet signals, consistent with a
facial arrangement of the three PMe3 ligands. In the infrared
(9) Huheey, J. E. Inorganic Chemistry: Principles of Structure and
ReactiVity; Harper and Row: New York, 1972; pp 423-440.
(10) To our knowledge, there have been no prior reports of metallaphe-
nols. Perhaps the closest reported relative is an metallathiaphenol, synthe-
sized by Roper: Elliott, G. P.; Roper, W. R.; Waters, J. M. J. Chem. Soc.,
Chem. Commun. 1982, 811.
(11) Consistent with the proposed pathway is the observation that
deuterium is incorporated exclusively at C4 when DO3SCF3 is used in place
of HO3SCF3.
spectrum of 7, the CtO stretch is seen at 2036 cm-1
.
The structure of 7 has been confirmed by X-ray diffraction
and is reproduced in Figure 4; key bond distances and angles
are reported in the caption. The iridacyclopentene ring shows
the expected long-short-long alternation in carbon-carbon

Iridacyclohexadienone and Iridaphenol Complexes
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8507
Scheme 6
bond lengths. The iridium-ring carbon bond lengths (Ir1-C1
and Ir1-C4) are each 2.159 Å, substantially longer than the
iridium-carbon bonds in iridacyclohexadienones 4 and 6. This
is consistent with the fact that C1 and C4 in compound 7 are
sp3 hybridized, while the iridium-bound ring carbon atoms in 4
and 6 are sp2 hybridized.12
Figure 5. ORTEP drawing of the cation in [CHdC(Me)sCHd
C(Me)sC(OH)dIr(PMe3)3(O3SCF3)]+O3SCF3-‚CCl2H2 (8). Selected
bond distances (Å): Ir1-P1, 2.374(4); Ir1-P2, 2.372(4); Ir1-P3,
2.436(5); Ir1-O2, 2.214(12); Ir1-C1, 2.031(16); Ir1-C5, 1.916(16);
O1-C5, 1.331(20); C1-C2, 1.352(25); C2-C3, 1.406(26); C2-C6,
1.523(28); C3-C4, 1.355(26); C4-C5, 1.464(25); C4-C7, 1.532(28).
Selected bond angles (deg): P1-Ir1-P2, 172.2(2); C1-Ir1-C5, 90.2-
(7); Ir1-C1-C2, 129.1(12); C1-C2-C3, 121.0(16); C2-C3-C4,
129.7(16); C3-C4-C5, 121.3(16); Ir1-C5-O1, 116.1(12); Ir1-C5-
C4, 128.4(12); O1-C5-C4, 115.2(14).
E. Treatment of Iridacyclohexadienone 4 with Acids.
Treatment of iridacyclohexadienone complex 4 with acids leads
to protonation at the carbonyl oxygen and the production of
stable iridaphenols. For example, when compound 4 is reacted
with triflic acid in tetrahydrofuran, the solution immediately
turns from yellow to dark red-orange, signaling the formation
of iridaphenol 8 (see Scheme 6).13 The aromatization of the
ring in 8 is indicated by the downfield shifting of ring protons
H1 and H3. H1 moves downfield from δ 9.25 in precursor 4
to δ 10.54 in 8, while H3 shifts from δ 6.66 in 4 to δ 7.49 in
8. Significant downfield shifts are also observed in the 13C
NMR for ring carbons C1, C3, and C5. These carbons appear
at δ 179.0, 165.1, and 219.3, respectively, while C2 and C4
resonate at δ 126.6 and 132.0. The C5 signal remains a singlet
(as in precursor 4), indicating that the triflate ligand remains
trans to C5. The 31P{1H} NMR spectrum consists of a doublet
(intensity 2) and a triplet (intensity 1), consistent with a mer
arrangement of PMe3 ligands.
The structure of compound 8 has been determined by X-ray
diffraction and is shown in Figure 5; key distances and angles
are reported in the figure caption. As expected for a metal-
laphenol, the carbon-carbon bond distances within the ring have
moved toward equalization. Bonds C1-C2, C2-C3, C3-C4,
and C4-C5 exhibit distances of 1.352(25), 1.406(26), 1.355-
(26), and 1.464(25) Å, respectively. The phenol carbon-oxygen
bond, C5-O1, has lengthened from 1.197(25) Å in precursor
4 to 1.331(20) Å in 8. Furthermore, the iridium-carbon bonds
Ir1-C1 and Ir1-C5 have shortened to 2.031(16) and 1.916-
(16) Å, respectively, from their values of 2.052(17) and 1.987-
(19) Å in 4, indicating significant metal participation in ring
π-bonding. While the trend toward delocalization is clear, the
small differences observed in bond distances within the ring
appear to be real. This suggests that, of the two resonance
structures shown below, structure A contributes more strongly
than B to the bonding in compound 8. This may result, in part,
from the fact that the triflate ligand (trans to C5) exerts a weaker
trans influence than the phosphine ligand (trans to C1).9 In
addition, resonance structure A may benefit from heteroatom
(oxygen) stabilization of the metal carbene. The iridaphenol
ring in 8 is nearly planar; the iridium atom resides less than 0.1
Å out of the best plane made by ring carbons C1, C2, C3, C4,
and C5, and the dihedral angle between planes C1-C2-C3-
C4-C5 and C1-Ir1-C5 is a mere 3.8°. The sum of the internal
angles within the ring is 719.7°, close to the value of 720°
required for a planar hexagon. The phenol hydrogen in 8 is
hydrogen-bonded to an oxygen atom in the triflate counteranion.
The distance between the phenol oxygen (O1) and the triflate
oxygen is 2.654 Å, typical for oxygen atoms that are hydrogen-
bonded.14
Treatment of iridacyclohexadienone 4 with trifluoroacetic acid
also leads to the production of an iridaphenol, compound 9. As
shown in Scheme 6, this reaction is accompanied by exchange
of the triflate ligand for a trifluoroacetate ligand, which
coordinates cis to C5 (trans to C1), allowing intramolecular
hydrogen bonding to occur between the phenol hydrogen and
the carbonyl oxygen of the trifluoroacetate group. The position
of the trifluoroacetate ligand in 9 is evident from the 13C NMR
spectrum, where the C5 signal is now phosphorus-coupled (J
) 93.8 Hz) due to its trans relationship to PMe3 and the C1
1
signal is a singlet. Similarly, in the H NMR spectrum of 9,
the H1 signal (δ 8.95) splits into a doublet (J ) 19.2 Hz),
because it resides adjacent to an equatorial phosphine. The H3
and phenol protons appear as singlets at δ 7.50 and 17.50,
respectively.
The structure of compound 9 has been confirmed by X-ray
diffraction and is shown in Figure 6; key bond distances and
angles are reported in the figure caption. The bonding within
the metallacycle in compound 9 is even more highly delocalized
than in compound 8. The Ir1-C1 and Ir1-C5 distances are
nearly identical at 2.002(12) and 2.023(13) Å, respectively, while
(12) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.
(13) Compound 1 and related aromatic metallacycles are typically orange
or red in color (see ref 1).
(14) Stout, G. H.; Jensen, L. H. X-Ray Structure Determination;
Macmillan Publishing Co., Inc.: New York, 1968; pp 302-303.

8508 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Bleeke and Behm
Scheme 7
trifluoroacetic acid. Apparently, the cationic charge on 6 and/
or the inertness of the tetrakis(PMe3) ligand set renders this
compound less reactive than 4 toward CF3CO2H.
Summary
Iridacyclohexadienones, a new class of unsaturated six-
membered metallacycles, have been synthesized by treating
iridabenzenes with nitrous oxide, an oxygen atom source. These
molecules undergo a number of interesting reactions, including
isomerization to (1,2,5-η-penta-1,3-dien-5-oyl)iridium com-
plexes via metal-mediated hydrogen transfer and reversible ring
contraction to iridacyclopentadiene complexes, an equilibrium
process that involves carbonyl insertion and deinsertion. When
treated with acids, iridacyclohexadienones generally protonate
at oxygen, producing iridaphenol complexes with aromatic
character. However, ring contraction can also occur upon
protonation, leading to iridacyclopentene products.
Figure 6. ORTEP drawing of the cation in [CHdC(Me)sCHd
C(Me)sC(OH)dIr(PMe3)3(O2CCF3)]+O3SCF3-‚CCl2H2 (9). Selected
bond distances (Å): Ir1-P1, 2.371(3); Ir1-P2, 2.355(3); Ir1-P3,
2.424(4); Ir1-O2, 2.236(10); Ir1-C1, 2.002(12); Ir1-C5, 2.023(13);
C1-C2, 1.371(19); C2-C3, 1.427(21); C2-C6, 1.513(24); C3-C4,
1.398(22); C4-C5, 1.371(20); C4-C7, 1.530(25); C5-O1, 1.345(15);
O2-C8, 1.253(19); C8-O3, 1.199(22). Selected bond angles (deg):
P1-Ir1-P2, 173.4; C1-Ir1-C5, 89.7(5); Ir1-C1-C2, 127.6(10); C1-
C2-C3, 123.4(13); C2-C3-C4, 128.4(14); C3-C4-C5, 120.5(14);
Ir1-C5-O1, 121.0(9); Ir1-C5-C4, 130.0(10); O1-C5-C4, 109.0-
(12); Ir1-O2-C8, 135.4(10); O2-C8-O3, 125.8(17).
Experimental Section
General Comments. All manipulations were carried out under a
nitrogen atmosphere, using either glovebox or double-manifold Schlenk
techniques. Solvents were stored under nitrogen after being distilled
from the appropriate drying agents. Deuterated NMR solvents were
obtained from Cambridge Isotope Laboratories in 1 g sealed vials and
used as received. The following reagents were used as obtained from
the supplier indicated: nitrous oxide (Aldrich), methyl trifluoromethane-
sulfonate (Aldrich), trimethylphosphine (Strem), trifluoromethane-
sulfonic acid (Aldrich), and trifluoroacetic acid (Aldrich). A detailed
ring C-C bonds C1-C2, C2-C3, C3-C4, and C4-C5 exhibit
distances of 1.371(19), 1.427(21), 1.398(22), and 1.371(20) Å,
respectively. Hence, it appears that resonance structures C and
D below contribute almost equally to the bonding in compound
synthesis and full NMR characterization of CHdC(Me)sCHdC-
(Me)sCHdIr(PMe3)3 (1) is given in ref 1k.
NMR experiments were performed on a Varian Unity-300 spec-
trometer (1H, 300 MHz; 13C, 75 MHz; 31P, 121 MHz), a Varian Unity-
500 spectrometer (1H, 500 MHz; 13C, 125 MHz; 31P, 202 MHz), or a
Varian VXR-600 spectrometer (1H, 600 MHz; 13C, 150 MHz; 31P, 242
MHz). 1H and 13C spectra were referenced to tetramethylsilane, while
31P spectra were referenced to external H3PO4. Some 1H connectivities
were determined from COSY (1H-1H correlation spectroscopy) data.
HMQC (1H-detected multiple quantum coherence) and HMBC (het-
eronuclear multiple bond correlation) experiments aided in assigning
9. Structure C may be stabilized by the presence of a
heteroatom (oxygen) on the carbene carbon, while resonance
structure D probably benefits from the weaker trans influence
of the trifluoroacetate group. The metallacycle in 9 is nearly
planar; the iridium atom lies only 0.100 Å out of the C1-C2-
C3-C4-C5 plane, and the dihedral angle between this plane
and the C1-Ir1-C5 plane is 4.0°. The sum of the six internal
angles within the metallaphenol ring is 719.6°.
1
some of the H and 13C peaks.
The infrared spectra were recorded on a Mattson Polaris FT IR
As mentioned above, the placement of the trifluoroacetate
ligand cis to C5 allows the phenol hydrogen to form an
intramolecular hydrogen bond, and the observed distance of
2.576 Å between the phenol oxygen (O1) and the trifluoroacetate
carbonyl oxygen (O3) is fully consistent with this type of
interaction. The molecule achieves the desired O1-O3 distance
by twisting the trifluoroacetate group out of the equatorial plane,
placing carbonyl oxygen O3 0.929 Å below the C1-C5-Ir1-
P3-O2 plane.
spectrometer.
Microanalyses were performed by Galbraith Laboratories, Inc.,
Knoxville, TN.
Synthesis of CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)3(H) (2).
N2O gas was bubbled through a stirring solution of orange CHdC-
(Me)sCHdC(Me)CHdIr(PMe3)3 (1) (0.31 g, 6.0 × 10-4 mol) in
diethyl ether at 25 °C until it turned a clear yellow color (∼30 s).
Crystallization from acetone at -30 °C resulted in dark yellow crystals
of 2. Yield: 0.25 g, 79%. Anal. Calcd for C16H36IrOP3: C, 36.29;
H, 6.85. Found: C, 36.06; H, 6.93. 1H NMR (benzene-d6, 25 °C): δ
8.16 (br d, JH-P ) 20.3 Hz, 1, H1), 6.76 (s, 1, H3), 2.31 (d, JH-P ) 2.9
Hz, 3, ring CH3’s), 2.15 (s, 3, ring CH3’s), 1.41 (d, JH-P ) 8.0 Hz, 9,
F. Treatment of Iridacyclohexadienone 6 with Triflic
Acid. As shown in Scheme 7, treatment of iridacyclohexadi-
enone 6 with triflic acid leads to production of iridaphenol 10.
1
Again, comparison of the H NMR spectrum of 10 vs that of
PMe3 CH3’s), 1.06 (d, JH-P ) 8.0 Hz, 9, PMe3 CH3’s), 1.04 (d, JH-P
)
precursor 6 shows significant downfield shifting of ring protons
H1 and H3, consistent with aromatization of the ring. The H1
signal moves from δ 7.97 in 6 to δ 9.18 in 10, while H3 shifts
from δ 6.67 to δ 7.55. In the 13C NMR, downfield shifts of
20-30 ppm are observed for ring carbons C1, C3, and C5.
Unlike iridacyclohexadienone 4, compound 6 does not react with
8.0 Hz, 9, PMe3 CH3’s), -10.80 (dt, JH-P ) 114.9, 20.5 Hz, 1, Ir-H).
13C{1H} (benzene-d6, 25 °C): δ 230.4 (br d, JC-P ) 98.1 Hz, C5),
140.6 (s, C3), 136.9 (d, JC-P ) 29.6 Hz, C4), 136.3 (br d, JC-P ) 80.7
Hz, C1), 127.5 (s, C2), 29.5 (d, JC-P ) 9.2 Hz, ring CH3), 22.6 (d,
JC-P ) 28.8 Hz, PMe3 CH3’s), 20.3 (d, JC-P ) 23.2 Hz, PMe3 CH3’s),
19.2 (s, ring CH3), 18.5 (d, JC-P ) 27.8 Hz, PMe3 CH3’s). 31P{1H}

Iridacyclohexadienone and Iridaphenol Complexes
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8509
NMR (benzene-d6, 25 °C): δ -51.1 (dd, JP-P ) 20.9, 20.3 Hz, 1,
PMe3), -56.5 (d, JP-P ) 20.9 Hz, 1, PMe3), -63.3 (d, JP-P ) 20.3
Hz, 1, PMe3).
δ -44.9 (dd, JP-P ) 23.1, 22.0 Hz, 2, trans-diaxial PMe3’s), -62.7
(td, JP-P ) 22.0, 2.5 Hz, 1, PMe3), -68.5 (td, JP-P ) 23.1, 2.5 Hz, 1,
PMe3).
Synthesis of (1,2,5-η-2,4-Dimethylpenta-1,3-dien-5-oyl)Ir(PMe3)3
(3). A solution of compound 2 (0.33 g, 6.6 × 10-4 mol) in diethyl
ether was stirred at 25 °C for 24 h. Crystallization from acetone at
-30 °C resulted in pale yellow crystals of 3. Yield: 0.27 g, 81%.
Anal. Calcd for C16H36IrOP3: C, 36.29; H, 6.85. Found: C, 36.13;
Synthesis of [CH2sC(Me)dCHsCH(Me)sIr(PMe3)3(CO)]+O3-
-
SCF3 (7). Excess HO3SCF3 (0.063 g, 4.2 × 10-4 mol) in diethyl
ether was added dropwise via syringe to compound 2 (0.20 g, 3.8 ×
10-4 mol) in diethyl ether at -78 °C, causing the clear yellow solution
to become orange and cloudy. Upon warming to 25 °C, the solution
turned colorless with a fine white precipitate. After removal of the
ether under vacuum, the white residue was washed with pentane to
remove excess HO3SCF3. Crystallization from acetone at -30 °C
resulted in colorless crystals of 7. Yield: 0.12 g, 46%. Anal. Calcd
for C17H37F3IrO4P3S‚C1.5H3O0.5: C, 31.35; H, 5.69. Found: C, 31.31;
H, 5.79. 1H NMR (acetone-d6, 25 °C): δ 5.25 (d, JH-P ) 7.0 Hz, 1,
H3), 2.55 (m, 1, H1), 2.51 (m, 1, H4), 1.86 (d, JH-P ) 8.6 Hz, 9, PMe3
CH3’s), 1.83 (partially obscured, H1), 1.79 (partially obscured, ring
CH3’s), 1.79 (d, JH-P ) 9.3 Hz, 9, PMe3 CH3’s), 1.62 (partially
obscured, ring CH3’s), 1.61 (d, JH-P ) 9.3 Hz, 9, PMe3 CH3’s). 13C-
{1H} NMR (acetone-d6, 25 °C): δ 174.9 (dt, JC-P ) 122.6, 6.4 Hz,
CO), 145.5 (dt, JC-P ) 12.9, 2.3 Hz, C2), 142.2 (dt, JC-P ) 9.5, 3.3
Hz, C3), 28.8 (s, ring CH3), 20.6 (ddd, JC-P ) 58.7, 5.7, 3.5 Hz, C4),
20.1 (s, ring CH3), 18.4 (d, JC-P ) 31.3 Hz, PMe3 CH3’s), 18.3 (d,
JC-P ) 31.9 Hz, PMe3 CH3’s), 14.4 (d, JC-P ) 37.6 Hz, PMe3 CH3’s),
13.4 (ddd, JC-P ) 55.5, 7.0, 3.0 Hz, C1). 31P{1H} NMR (acetone-d6,
25 °C): δ -49.6 (dd, JP-P ) 26.4, 25.7 Hz, 1, PMe3), -62.0 (dd, JP-P
) 25.7, 12.2 Hz, 1, PMe3), -63.3 (dd, JP-P ) 26.4, 12.2 Hz, 1, PMe3).
IR (Nujol mull): 2036 cm-1 (CtO stretch).
1
H, 7.05. H NMR (benzene-d6, 25 °C): δ 7.21 (d, JH-P ) 9.4 Hz, 1,
H3), 2.16 (br d, JH-P ) 13.6 Hz, 1, H1), 1.98 (d, JH-P ) 8.5 Hz, 3,
ring CH3’s), 1.87 (m, 1, H1), 1.83 (s, 3, ring CH3’s), 1.42 (d, JH-P
)
7.2 Hz, 9, PMe3 CH3’s), 1.22 (d, JH-P ) 7.2 Hz, 9, PMe3 CH3’s), 0.97
(d, JH-P ) 6.0 Hz, 9, PMe3 CH3’s). 13C{1H} NMR (benzene-d6, 25
°C): δ 237.3 (dt, JC-P ) 101.3, 9.0 Hz, C5), 166.7 (s, C3), 144.7 (d,
JC-P ) 24.1 Hz, C4), 46.9 (dd, JC-P ) 36.0, 6.6 Hz, C2), 37.8 (ddd,
JC-P ) 33.5, 8.0 Hz, 3.0 Hz, C1), 28.1 (s, ring CH3), 22.4-22.1
(complex m, PMe3 CH3’s), 20.9 (dt, JC-P ) 21.4, 3.5 Hz, PMe3 CH3’s),
11.8 (s, ring CH3). 31P{1H} NMR (benzene-d6, 25 °C): -50.9 (dd,
JP-P ) 35.5, 5.5 Hz, 1, PMe3), -52.3 (dd, JP-P ) 35.5, 21.3 Hz, 1,
PMe3), -63.4 (dd, JP-P ) 21.3, 5.5 Hz, 1, PMe3).
Synthesis of CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)3(O3SCF3)
(4). Excess CH3O3SCF3 (0.16 g, 9.8 × 10-4 mol) in diethyl ether was
added dropwise via syringe to a solution of compound 2 (0.36 g, 7.1
× 10-4 mol) in diethyl ether at -10 °C, causing the clear yellow
solution to become cloudy. The ether was removed under vacuum,
and the yellow residue was washed with pentane to remove any excess
CH3O3SCF3. Crystallization from acetone at -30 °C produced orange/
yellow crystals of 4. Yield: 0.32 g, 66%. Anal. Calcd for
C17H35F3IrO4P3S: C, 30.13; H, 5.21. Found: C, 29.92; H, 5.18. 1H
NMR (acetone-d6, 25 °C): δ 9.25 (s, 1, H1), 6.66 (s, 1, H3), 2.02 (s,
3, ring CH3’s), 1.61 (s, 3, ring CH3’s), 1.60 (d, JH-P ) 9.8 Hz, 9, PMe3
CH3’s), 1.41 (virtual t, JH-P ) 8.6 Hz, 18, PMe3 CH3’s). 13C{1H} NMR
(benzene-d6, 25 °C): δ 188.7 (s, C5), 156.7 (dt, JC-P ) 78.2, 13.1 Hz,
C1), 145.7 (s, C3), 127.9 (s, C2), 127.1 (s, C4), 26.8 (d, JC-P ) 8.8
Hz, ring CH3), 20.0 (s, ring CH3), 15.7 (d, JC-P ) 40.1 Hz, PMe3
CH3’s), 15.1 (virtual t, JC-P ) 38.2 Hz, PMe3 CH3’s). 31P{1H} NMR
(acetone-d6, 25 °C): δ -32.3 (d, JP-P ) 25.0 Hz, 2, PMe3’s), -39.9
(t, JP-P ) 25.0 Hz, 1, PMe3).
Synthesis of [CHdC(Me)sCHdC(Me)sC(OH)dIr(PMe3)3-
(O3SCF3)]+O3SCF3- (8). Excess HO3SCF3 (0.10 g, 6.8 × 10-4 mol)
was added dropwise to a stirring solution of compound 4 (0.31 g, 4.6
× 10-4 mol) in tetrahydrofuran at 25 °C, causing the yellow solution
to turn a dark orange color. After removing the solvent under vacuum,
the residue was washed with diethyl ether to remove any excess HO3-
SCF3. Crystallization from methylene chloride at -30 °C resulted in
red crystals of 8. Yield: 0.24 g, 64%. Anal. Calcd for C18H36F6-
IrO7P3S2: C, 26.12; H, 4.39. Found: C, 25.87; H, 4.37. 1H NMR
(methylene chloride-d2, 25 °C): δ 10.54 (s, 1, H1), 7.49 (s, 1, H3),
2.24 (s, 3, ring CH3’s), 2.08 (s, 3, ring CH3’s), 1.69 (d, JH-P ) 7.8 Hz,
9, PMe3 CH3’s), 1.44 (t, JH-P ) 8.8 Hz, 18, PMe3 CH3’s). NOTE:
The phenol proton appears as a broad resonance in the δ 12-14 region.
13C{1H} NMR (methylene chloride-d2, 25 °C): δ 219.3 (s, C5), 179.0
(d, JC-P ) 76.9 Hz, C1), 165.1 (s, C3), 132.0, 126.6 (s’s, C2 and C4),
Synthesis of [CHdC(Me)sCHdC(Me)sIr(PMe3)3(CO)]+O3SCF3-
(5). Crystals of compound 4 were dissolved in acetone at room
temperature. After 1 h, the NMR spectrum revealed an equilibrium
mixture of compounds 4 and 5 in a ratio of 60:40. 1H NMR (acetone-
d6, 25 °C): δ 6.44 (d, JH-P ) 8.7 Hz, 1, H3), 6.31 (t, JH-P ) 10.3 Hz,
1, H1), 2.44 (d, JH-P ) 6.0 Hz, 3, ring CH3’s), 1.95 (d, JH-P ) 8.6 Hz,
9, PMe3 CH3’s), 1.92 (d, JH-P ) 9.8 Hz, 9, PMe3 CH3’s), 1.92 (s, 3,
ring CH3’s), 1.62 (d, JH-P ) 7.3 Hz, 9, PMe3 CH3’s). 13C{1H} NMR
(benzene-d6, 25 °C): δ 171.8 (dt, JC-P ) 110.7, 6.2 Hz, CO), 153.7 (s,
25.6 (d, JC-P ) 8.0 Hz, ring CH3), 19.0 (s, ring CH3), 16.7 (d, JC-P
)
30.1 Hz, PMe3 CH3’s), 15.4 (virtual t, JC-P ) 38.9 Hz, PMe3 CH3’s).
31P{1H} NMR (methylene chloride-d2, 25 °C): δ -29.70 (d, JP-P
25.1 Hz, 2, PMe3’s), -41.3 (t, JP-P ) 25.1 Hz, 1, PMe3).
)
Synthesis of [CHdC(Me)sCHdC(Me)sC(OH)dIr(PMe3)3-
-
(O2CCF3)]+O3SCF3 (9). A synthetic procedure similar to that
C2), 148.1 (s, C3), 143.7 (d, JC-P ) 65.8 Hz, C4), 124.2 (ddd, JC-P
)
67.1, 13.0, 5.9 Hz, C1), 32.6 (m, ring CH3), 20.8 (d, JC-P ) 7.0 Hz,
described for compound 8 was employed, except that CF3COOH (0.20
g, 1.7 × 10-3 mol) was substituted for HO3SCF3. Crystallization from
methylene chloride/diethyl ether resulted in orange crystals of 9.
Yield: 0.29 g, 80%. Anal. Calcd for C19H36F6IrO6P3S: C, 28.82; H,
4.59. Found: C, 28.39; H, 4.61. 1H NMR (methylene chloride-d2, 25
°C): δ 17.50 (s, 1, phenol H), 8.95 (d, JH-P ) 19.2 Hz, 1, H1), 7.50
(s, H3), 2.14 (s, 3, ring CH3’s), 2.00 (s, 3, ring CH3’s), 1.66 (d, JH-P
) 8.6 Hz, 9, PMe3 CH3’s), 1.33 (virtual t, JH-P ) 7.7 Hz, 18, PMe3
ring CH3), 20.5 (d, JC-P ) 31.7 Hz, PMe3 CH3’s), 18.5 (d, JC-P
)
32.4 Hz, PMe3 CH3’s), 17.6 (d, JC-P ) 28.0 Hz, PMe3 CH3’s). 31P-
{1H} NMR (acetone-d6, 25 °C): δ -48.0 (dd, JP-P ) 26.7, 26.0 Hz,
1, PMe3), -61.2 (dd, JP-P ) 26.0, 13.4 Hz, 1, PMe3), -66.1 (dd, JP-P
) 26.7, 13.4 Hz, 1, PMe3). IR (Nujol mull): 2054 cm-1 (CtO stretch).
Synthesis of [CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)4]+O3-
SCF3- (6). Excess PMe3 (0.16 g, 2.1 × 10-3 mol) was added dropwise
to compound 4 (0.10 g, 1.5 × 10-4 mol) in tetrahydrofuran at 25 °C,
and the resulting solution was stirred for 30 min. Crystallization from
acetone at -30 °C resulted in yellow crystals of 6. Yield: 0.09 g,
80%. Anal. Calcd for C20H44F3IrO4P4S: C, 31.87; H, 5.90. Found
CH3’s). 13C{1H} (methylene chloride-d2, 25 °C): δ 250.8 (d, JC-P
)
93.8 Hz, C5), 162.1 (s, C3), 146.3 (s, C1), 132.7 (d, JC-P ) 9.6 Hz,
C4), 131.2 (s, C2), 26.0 (s, ring CH3), 18.4 (s, ring CH3), 15.3 (virtual
t, JC-P ) 39.2 Hz, PMe3 CH3’s), 13.9 (d, JC-P ) 30.8 Hz, PMe3 CH3’s).
31P{1H} NMR (methylene chloride-d2, 25 °C): δ -34.5 (d, JP-P
28.6 Hz, 2, PMe3’s), -43.7 (t, JP-P ) 28.6 Hz, 1, PMe3).
)
C, 31.85; H, 6.23. 1H NMR (acetone-d6, 25 °C): δ 7.97 (d, JH-P
)
19.1 Hz, 1, H1), 6.67 (s, 1, H3), 2.06 (s, 3, ring CH3’s), 1.71 (d, JH-P
) 7.9 Hz, 9, PMe3 CH3’s), 1.66 (d, JH-P ) 7.3 Hz, 9, PMe3 CH3’s),
1.59 (s, 3, ring CH3’s), 1.52 (virtual t, JH-P ) 7.33 Hz, 18, trans-
diaxial PMe3 CH3’s). 13C{1H} NMR (acetone-d6, 25 °C): δ 220.1 (d,
JC-P ) 86.1 Hz, C5), 142.1 (s, C3), 136.7 (dtd, JC-P ) 73.0, 13.8, 4.2
Synthesis of [CHdC(Me)sCHdC(Me)sC(OH)dIr(PMe3)4]2+
-
(O3SCF3-)2 (10). Excess HO3SCF3 (0.12 g, 8.0 × 10-4 mol) was added
dropwise to a stirring solution of compound 6 (0.11 g, 1.5 × 10-4
mol) in tetrahydrofuran at 25 °C, causing the yellow solution to turn a
clear orange color with some precipitation of the final product. After
the solvent was removed under vacuum, the residue was washed with
diethyl ether to remove any excess HO3SCF3. Crystallization from
methylene chloride resulted in dark orange crystals of 10. Yield: 0.09
Hz, C1), 133.1 (d, JC-P ) 27.9 Hz, C4), 129.3 (s, C2), 27.7 (d, JC-P
)
7.8 Hz, ring CH3), 20.3 (d, JC-P ) 30.9 Hz, PMe3 CH3’s), 17.8 (s, ring
CH3), 17.7 (virtual t, JC-P ) 39.4 Hz, trans-diaxial PMe3 CH3’s), 17.2
(d, JC-P ) 25.3 Hz, PMe3 CH3’s). 31P{1H} NMR (acetone-d6, 25 °C):

8510 J. Am. Chem. Soc., Vol. 119, No. 36, 1997
Table 1. X-ray Diffraction Structure Summary
Bleeke and Behm
3
4
6
7
8
9
Crystal Parameters and Data Collection Summary
formula
formula weight
crystal system
space group
a, Å
b, Å
c, Å
C16H36IrOP3
529.6
monoclinic
P21/n
9.359(1)
15.743(3)
14.871(4)
90.0
95.68(2)
90.0
C17H35F3IrO4P3S
677.6
monoclinic
P21/c
C20H44F3IrO4P4S
753.7
monoclinic
P21/m
C18.5H40F3IrO4.5P3S C19H38Cl2F6IrO7P3S2 C20H38Cl2F6IrO6P3S
708.7
monoclinic
C2/c
912.6
monoclinic
P21/c
9.109(3)
22.210(11)
17.370(11)
90.0
92.10(4)
90.0
876.6
monoclinic
P21/c
8.930(3)
22.446(11)
17.436(8)
90.0
91.37(4)
90.0
9.100(2)
29.364(8)
20.080(6)
90.0
93.05(2)
90.0
15.196(6)
11.117(2)
18.505(7)
90.0
103.57(3)
90.0
30.485(8)
11.613(3)
16.948(4)
90.0
108.48(2)
90.0
R, deg
â, deg
γ, deg
V, Å3
2180.4(8)
4
5358(2)
8
3038(2)
4
5691(2)
8
3512(3)
4
3494(3)
4
Z
crystal
dimensions,
mm
0.65 × 0.45 × 0.35 0.48 × 0.46 × 0.34 0.12 × 0.20 × 0.30 0.50 × 0.45 × 0.35 0.54 × 0.34 × 0.30 0.32 × 0.34 × 0.32
crystal color
yellow prism
yellow prism
yellow prism
colorless block
orange prism
orange prism
and habit
densitycald, g/cm3 1.613
1.680
1.647
1.654
1.726
1.666
radiation, Å
scan type
scan rate,
deg/min
Mo KR, 0.710 73
Mo KR, 0.710 73
Mo KR, 0.710 73
Mo KR, 0.710 73
Mo KR, 0.710 73
Mo KR, 0.710 73
θ:2θ
ω
θ:2θ
ω
θ:2θ
θ:2θ
var; 4.00-29.30
var; 4.00-29.30
var; 4.19-29.30
var; 4.19-29.30
var; 4.19-29.30
var; 5.00-29.30
in ω
2θ range, deg
scan range (ω),
deg
3.0-50.0
1.20
3.0-50.0
1.20
3.0-50.0
1.40
3.0-50.0
1.60
3.0-50.0
1.60
3.0-50.0
1.40
data collected
h 0 f 11
k 0 f 18
l -17 f 17
none detected
298
h 0 f 10
k 0 f 34
l -23 f 23
none detected
298
h 0 f 18
k 0 f 13
l -22 f 21
none detected
298
h 0 f 36
k 0 f 14
l -21 f 21
none detected
298
h 0 f 10
k 0 f 26
l -20 f 20
40%
h 0 f 10
k 0 f 26
l -20 f 20
none detected
298
total decay
temperature, K
298
Treatment of Intensity Data and Refinement Summary
no. of data
collected:
no. of unique
data:
no. of observed 2976
data I > 3σ(I)
Mo KR linear
abs coeff,
cm-1
4098
3851
10055
9425
4815
52.80
5916
5688
3389
47.14
5076
4972
2763
49.77
6534
6126
3492
42.75
6615
6195
3709
42.33
63.42
abs correction
applied
semiempirical
semiempirical
9.8:1
semiempirical
9.9:1
semiempirical
11.2:1
semiempirical
9.6:1
semiempirical
10.0:1
data to parameter 15.6:1
ratio
Ra
0.0270
0.0373b
1.14
0.0515
0.0726c
0.66
0.0447
0.0711d
0.61
0.0589
0.0837e
0.90
0.0559
0.0692f
1.58
0.0478
0.0639g
1.14
a
Rw
GOFh
2
a R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) (∑w(|Fo| - |Fc|)2/∑w|Fo| )1/2
.
b w ) [σ2(Fo) + 0.0006(Fo)2]-1 c w ) [σ2(Fo) + 0.0098(Fo)2]-1 d w ) [σ2(Fo)
. .
+ 0.0119(Fo)2]-1
.
e w ) [σ2(Fo) + 0.0065(Fo)2]-1
.
f w ) [σ2(Fo) + 0.0008(Fo)2]-1
.
g w ) [σ2(Fo) + 0.0019(Fo)2]-1
.
h GOF ) [∑w(|Fo| - |Fc|)2/
(Nobservations - Nvariables)]1/2
.
g, 64%. Anal. Calcd for C21H45F6IrO7P4S2: C, 27.90, H, 5.03.
Found: C, 27.25; H, 5.06. 1H NMR (methylene chloride-d2, 25 °C):
δ 9.18 (dd, JH-P ) 18.7, 6.1 Hz, 1, H1), 7.55 (s, 1, H3), 2.27 (s, 3,
ring CH3’s), 2.11 (s, 3, ring CH3’s), 1.81 (d, JH-P ) 8.5 Hz, 9, PMe3
CH3’s), 1.78 (d, JH-P ) 8.5 Hz, 9, PMe3 CH3’s), 1.51 (virtual t, JH-P
) 7.5 Hz, 18, trans-diaxial PMe3 CH3’s). NOTE: The phenol proton
appears as a broad resonance in the δ 12-14 region. 13C{1H} NMR
(methylene chloride-d2, 25 °C): δ 246.0 (d, JC-P ) 98.3 Hz, C5), 165.6
(6), [CH2sC(Me)dCHsCH(Me)sIr(PMe3)3(CO)]+O3SCF3-‚1/2Me2C-
(O) (7), [CHdC(Me)sCHdC(Me)sC(OH)dIr(PMe3)3(O3SCF3)]+O3-
SCF3-‚CCl2H2 (8), and [CHdC(Me)sCHdC(Me)sC(OH)dIr(P-
Me3)3(O2CCF3)]+O3SCF3-‚CCl2H2 (9). Single crystals of compounds
3, 4, 6, 7, 8, and 9 were sealed in glass capillaries under an inert
atmosphere. Data were collected on a Siemens R3m/V diffractometer
at room temperature, using graphite-monochromated Mo KR radiation.
Three standard reflections were measured every one hundred events
as check reflections for crystal deterioration and/or misalignment.
All data reduction and refinement were done using the Siemens
SHELXTL PLUS package on a VAX 3100 workstation.15 Crystal data
and details of data collection and structure analysis are listed in Table
1.
(s, C3), 164.6 (d, JC-P ) 72.5 Hz, C1), 134.4 (s, C2), 131.1 (d, JC-P
)
10.8 Hz, C4), 27.4 (d, JC-P ) 7.6 Hz, ring CH3), 25.6 (s, ring CH3),
21.3 (d, JC-P ) 32.9 Hz, PMe3 CH3’s), 18.5 (virtual t, JC-P ) 41.7 Hz,
trans-diaxial PMe3 CH3’s), 17.8 (d, JC-P ) 32.0 Hz, PMe3 CH3’s).
31P{1H} NMR (methylene chloride-d2, 25 °C): δ -49.0 (dd, JP-P
)
27.7 Hz, 21.7 Hz, 2, trans-diaxial PMe3’s), -63.5 (td, JP-P ) 21.7,
8.5 Hz, 1, PMe3), -65.2 (td, JP-P ) 27.7, 8.5 Hz, 1, PMe3).
X-ray Diffraction Studies of (1,2,5-η-2,4-Dimethylpenta-1,3-dien-
5-oyl)Ir(PMe3)3 (3), CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)3-
(O3SCF3) (4), [CHdC(Me)sCHdC(Me)sC(O)sIr(PMe3)4]+O3SCF3-
The iridium atom positions in compounds 3, 4, 6, and 8 were
determined by direct methods; its positions in compounds 7 and 9 were
(15) Atomic scattering factors were obtained from the following:
International Tables for X-Ray Crystallography; Kynoch Press: Birming-
ham, England, 1974; Vol. IV.

Iridacyclohexadienone and Iridaphenol Complexes
J. Am. Chem. Soc., Vol. 119, No. 36, 1997 8511
calculated from Patterson maps. In all cases, remaining non-hydrogen
atoms were found by successive full-matrix least-squares refinement
and difference Fourier map calculations. In general, non-hydrogen
atoms were refined anisotropically except in cases of disorder, while
hydrogen atoms were placed in idealized positions and assumed the
riding model.
Program (Grant CHE-8811456). Washington University’s High
Resolution NMR Service Facility was funded in part by National
Institutes of Health Biomedical Support Instrument Grant 1 S10
RR2004 and by a gift from Monsanto Company.
Supporting Information Available: Structure determination
summaries, listings of final atomic coordinates, thermal param-
eters, bond lengths, and bond angles for compounds 3, 4, 6, 7,
8, and 9, and ORTEP drawings of the second independent
molecules in compounds 4 and 6 (56 pages). See any current
masthead page for ordering and Internet access instructions.
Acknowledgment. Support from the National Science
Foundation (Grant CHE-9303516) and the donors of the
Petroleum Research Fund, administered by the American
Chemical Society, is gratefully acknowledged. We thank
Johnson Matthey Alfa/Aesar for a loan of IrCl3‚3H2O. Wash-
ington University’s X-ray Crystallography Facility was funded
by the National Science Foundation’s Chemical Instrumentation
JA971721+