Synthesis, spectroscopy, and reactivity of a metallapyrylium

Article abstract of DOI:10.1021/om0008068

The first example of a stable metallapyrylium complex, [CH double bond C(Me)CH double bond C(Me)O double bond Ir(PEt₃)₃]⁺BF₄^- (2), has been prepared, and its reaction chemistry has been explored. Comp

Full text of DOI:10.1021/om0008068

324
Organometallics 2001, 20, 324-336
Syn th esis, Sp ectr oscop y, a n d Rea ctivity of a
Meta lla p yr yliu m 1
J ohn R. Bleeke,* J onathan M. B. Blanchard, and Edward Donnay
Department of Chemistry, Washington University, St. Louis, Missouri 63130
Received September 19, 2000
The first example of a stable metallapyrylium complex, [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+-
-
BF4 (2), has been prepared, and its reaction chemistry has been explored. Compound 2 is
obtained in ∼50% yield upon treatment of mer-CHdC(Me)CHdC(Me)OIr(H)(PEt3)3 (3) with
silver tetrafluoroborate in tetrahydrofuran. The other major product of this reaction, [mer-
-
CHdC(Me)CH2C(Me)dOIr(H)(PEt3)3]+BF4 (4), is readily converted back to 3 (by treating
1
with base) and can be reused. Compound 2 exhibits downfield H NMR chemical shifts for
its ring protons, consistent with its characterization as an aromatic metallacycle. The iridium
center in 2 is reactive toward a variety of 2e- donor reagents, including hydride reagents,
methyllithium, chloride reagents, and trimethylphosphine. The products of these reactions
are octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,3-diene ring skeleton.
The chloride reaction product, mer-CHdC(Me)CHdC(Me)OIr(Cl)(PEt3)3 (6), has been
characterized by X-ray diffraction. Compound 2 also undergoes [4 + 2] cycloaddition reactions
with various unsaturated substrates, including acetone, alkynes, alkenes, and sulfur dioxide.
In each of these reactions, the substrate adds across iridium and the central carbon atom of
the ring (C3) to produce octahedral Ir(III) compounds containing the iridaoxacyclohexa-1,4-
diene ring skeleton. The X-ray crystal structure of the sulfur dioxide cycloadduct, {fac-[CHd
C(Me)CHC(Me)dOIrS(O)2](PEt3)3}+BF4- (13), has been obtained. Finally, treatment of 2 with
nitrosobenzene generates a novel adduct containing two fused five-membered rings, {fac-
[C(Me)CHdC(Me)OIrON(Ph)dCH](PEt3)3}+BF4- (14). This reaction probably involves initial
[2 + 2] cycloaddition, followed by rearrangement. The structure of 14 has been confirmed
by X-ray diffraction.
In tr od u ction
During the past decade, we have been exploring the
chemistry of “iridabenzene” (1),2 a rare example of a
stable metallabenzene complex.3,4 We have found that
the physical and chemical properties of this species are
consistent with the presence of a genuinesalbeit fragiles
aromatic ring system. We now report the synthesis and
spectroscopic characterization of the oxygen-containing
analogue of 1, “iridapyrylium” (2),5 which, to our knowl-
edge, is the first example of a stable metalloxabenzene.6
In addition, we describe the reaction chemistry of 2 and
compare its chemical behavior to that of iridabenzene.
(1) Metallacyclohexadiene and Metallabenzene Chemistry. 16. Part
15: Bleeke, J . R.; Hinkle, P. V. J . Am. Chem. Soc. 1999, 121, 595.
(2) (a) Bleeke, J . R.; Xie, Y.-F.; Peng, W.-J .; Chiang, M. J . Am. Chem.
Soc. 1989, 111, 4118. (b) Bleeke, J . R. Acc. Chem. Res. 1991, 24, 271.
(c) Bleeke, J . R.; Behm, R.; Xie, Y.-F.; Chiang, M. Y.; Robinson, K. D.;
Beatty, A. M. Organometallics 1997, 16, 606. (d) Bleeke, J . R.; Behm,
R. J . Am. Chem. Soc. 1997, 119, 8503.
Resu lts a n d Discu ssion
A. Syn th esis a n d Sp ectr oscop y of Ir id a p yr yliu m
2. The synthesis of iridapyrylium is accomplished by the
series of steps outlined in Scheme 1. Treatment of (Cl)-
(3) For examples of other stable metallabenzenes, see: (a) Elliott,
G. P.; Roper, W. R.; Waters, J . M. J . Chem. Soc., Chem. Commun. 1982,
811. (b) Rickard, C. E. F.; Roper, W. R.; Woodgate, S. D.; Wright, L. J .
Angew. Chem., Int. Ed. 2000, 39, 750. (c) Gilbertson, R. D.; Weakley,
T. J . R.; Haley, M. M. J . Am. Chem. Soc. 1999, 121, 2597. (d)
Gilbertson, R. D.; Weakley, T. J . R.; Haley, M. M. Chem. Eur. J . 2000,
6, 437.
(4) Detection of a thermally unstable metallabenzene at low tem-
perature has also been reported: Yang, J .; J ones, W. M.; Dixon, J . K.;
Allison, N. J . Am. Chem. Soc. 1995, 117, 9976.
(5) A portion of this work has been communicated: Bleeke, J . R.;
Blanchard, J . M. B. J . Am. Chem. Soc. 1997, 119, 5443.
(6) Several examples of metallathiabenzenes have been reported:
(a) Chen, J .; Daniels, L. M.; Angelici, R. J . J . Am. Chem. Soc. 1990,
112, 199. (b) Chin, R. M.; J ones, W. D. Angew. Chem., Int. Ed. Engl.
1992, 31, 357. (c) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.;
Frediani, P.; Herrera, V.; Sanchez-Delgado, R. A. J . Am. Chem. Soc.
1993, 115, 2731. (d) Bleeke, J . R.; Hinkle, P. V. J . Am. Chem. Soc.
1999, 121, 595.
10.1021/om0008068 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 12/15/2000

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 325
Sch em e 1
Sch em e 2
Ir(PEt3)3 with potassium 2,4-dimethyloxapentadienide
generates the iridaoxacyclohexa-1,3-diene hydride com-
plex (3; Scheme 1) via C-H bond activation.7 When 2
equiv of this species is then reacted with 2 equiv of silver
tetrafluoroborate (AgBF4) in tetrahydrofuran, a clean
1:1 mixture of “iridapyrylium” (2; Scheme 1) and the
protonated ring compound 4 (Scheme 1) is generated.8,9
Treatment of this mixture with 1 equiv of lithium
diisopropylamide in tetrahydrofuran results in selective
deprotonation of 4 back to 3, which can then be
extracted with pentane, leaving pure 2 as a deep purple
solid. The recovered starting material, 3, can be treated
again with AgBF4 to produce additional iridapyrylium,
raising the overall yield of the process.10
Although the detailed mechanism of the conversion
of 3 to 2 and 4 is not known, the pathway outlined in
Scheme 2 is consistent with our observations. Treatment
of 3 with AgBF4 at -47 °C probably leads to 1e-
oxidation, generating the 17e- radical cation A. This
species then transfers a proton to a second equivalent
of 3, generating 4 and the 17e- neutral radical B. When
it is warmed, species B is oxidized by the second
equivalent of AgBF4, producing iridapyrylium 2. The
characteristic deep purple color of 2 appears at about
16 °C, indicating that this is the temperature at which
the final oxidation occurs.
(7) The detailed synthesis and spectroscopy of 3 have been previ-
ously reported: Bleeke, J . R.; Haile, T.; New, P. R.; Chiang, M. Y.
Organometallics 1993, 12, 517.
(8) Compound
4 can be synthesized independently by treating
compound 3 with HBF4‚OEt2 (see Experimental Section).
(9) The triflate salt of 4 was first characterized by Haile: Haile, T.
Ph.D. Dissertation, Washington University, St. Louis, MO, 1992.
(10) Attempts to increase the ratio of 2 to 4 in the original reaction
(Scheme 1) by adding external bases such as NEt3 were unsuccessful.

326 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
Sch em e 3
The 31P{1H} NMR spectrum of 2, like that of irida-
benzene 1, consists of a sharp singlet, which does not
broaden significantly, even upon cooling to -90 °C. This
behavior is indicative of a low-energy fluxional process
that exchanges the phosphine ligands. If compound 2
is isostructural with 1 (square pyamidal),2a the phos-
phine exchange probably occurs via a Berry-type process
involving trigonal-bipyramidal intermediates. In the 1H
NMR spectrum of 2, ring protons H1 and H3 are shifted
downfield to δ 9.35 and 6.45, from their positions of δ
5.76 and 4.02, respectively, in precursor 3.11 This
downfield shifting indicates metal orbital participation
in ring π-bonding and the establishment of a ring
current. The H1 signal is split into a quartet (J ) 6.0
Hz) by the 31P nuclei of the three exchanging phosphine
ligands. In the 13C{1H} NMR spectrum, the ring carbons
resonate at δ 170.7 (C4), 162.2 (C1), 147.3 (C2), and
112.2 (C3). The C1 signal is split into a phosphorus-
coupled quartet (J ) 22.7 Hz).
C it possesses 16e-. Structures B and C differ only in
the position of one electron pair. In B, it resides between
oxygen and iridium, forming the π bond, while in C it
resides on the oxygen atom.12
B. Rea ctivity of Ir id a p yr yliu m 2: Ad d ition to th e
Ir id iu m Cen ter . Because of the contribution from
resonance structure C, the iridium atom in 2 is reactive
toward a variety of 2e- donor reagents, including
hydride, methyllithium, chloride, and trimethylphos-
phine. The products of these reactions, all of which are
yellow, six-coordinate iridaoxacyclohexa-1,3-diene com-
pounds, are summarized in Scheme 3. Treatment of 2
with Li+Al(O-t-Bu)3(H)- regenerates the metal hydride
precursor 3. Similarly, treatment with methyllithium
produces 5, the methyl analogue of 3.13 The 31P{1H}
NMR spectrum of 5, like that of 3, consists of a doublet
(two axial phosphines) and a triplet (one equatorial
phosphine), indicating a mer arrangement of the phos-
phine ligands. In the 13C{1H} NMR spectrum, the signal
for ring carbon C1 is a doublet (J C-P ) 86.0 Hz) of
triplets (J C-P ) 16.0 Hz). The strong doublet coupling
indicates that C1 resides trans to a phosphine ligand.
Hence, the methyl ligand must lie trans to oxygen. One
interesting feature of the 13C NMR spectrum is the
extreme upfield shift of the iridium-bound methyl
carbon, δ -39.6. The corresponding signal for the methyl
One can write three reasonable resonance structures
for iridapyrylium 2 (A-C). In structures A and B, the
1
hydrogens in the H NMR spectrum is at δ 0.42.
(11) For comparison, the 1H NMR data for both 2 and 3 were
obtained in methylene chloride-d2. In benzene-d6, the chemical shift
values for H1 and H3 in compound 3 were δ 6.04 and 4.70, respec-
tively.7
(12) Note that in structures A and B the formal positive charge
resides on oxygen, while in C it resides on the iridium center.
(13) This reaction is always accompanied by the production of a
small quantity of hydride 3. The origin of this byproduct is not known.
iridium center possesses 18 valence electrons, while in

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 327
chloride ligand trans to ring carbon C1. The six-
membered ring is essentially planar; the sum of the six
internal angles is 719.3°, very close to the theoretical
value of 720° for a planar hexagon. However, to com-
pensate for the small O1-Ir-C1 angle (90.5°), the other
five internal angles expand to values greater than 120°
(range 125.1-127.3°; average 125.8°). The C-C and
C-O distances within the ring show the bond length
alternation expected for the iridaoxacyclohexa-1,3-diene
skeleton. The reason that compound 6 adopts a ligand
arrangement different from that of compounds 3 and 5
is not entirely clear but probably results from the fact
that chloride exerts a much weaker trans influence than
hydride or methyl.14 Hence, it prefers to reside trans to
ring carbon C1, a strong trans-influence ligand. The
weak trans influence of chloride is reflected in the rather
short bond distance between iridium and ring carbon
C1, 2.029(6) Å.15
Treatment of 2 with excess trimethylphosphine leads
to PMe3 addition at the iridium center and complete
replacement of the three bulky PEt3 ligands with
smaller PMe3’s, generating the tetrakis(trimethylphos-
phine) product 7 (Scheme 3). This reaction contrasts
sharply with the room-temperature reaction of irida-
benzene 1 with excess PMe3, which results in replace-
ment of one PEt3 ligand with PMe3 and retention of the
aromatic ring system.2c The reason for this difference
in behavior is that 1 reacts with PMe3 by a dissociative
mechanism, while the reaction of 2 with PMe3 involves
a series of associative steps, as shown in Scheme 4. The
associative steps are made possible by the fact that the
Ir-O π-electrons can be localized on the oxygen atom
(cf. resonance structure C), rendering the iridium atom
a reactive 16e- center.
F igu r e 1. ORTEP drawing of mer-CHdC(Me)CHdC(Me)-
OIr(Cl)(PEt3)3 (6).
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) w ith Estim a ted Sta n d a r d Devia tion s for
m er -CHdC(Me)CHdC(Me)OIr (Cl)(P Et3)3 (6)
Bond Distances
Ir-Cl
Ir-P1
Ir-P2
Ir-P3
Ir-O1
Ir-C1
2.508(2)
2.366(2)
2.379(2)
2.292(2)
2.089(4)
2.029(6)
C1-C2
C2-C3
C2-C5
C3-C4
C4-C6
O1-C4
1.344(10)
1.467(10)
1.540(11)
1.334(10)
1.532(9)
1.314(8)
The 31P{1H} NMR spectrum of 7 consists of three
signalssa doublet of doublets due to the two equivalent
trans-diaxial phosphines and two triplets of doublets
due to the inequivalent equatorial phosphines. In the
13C{1H} NMR spectrum, the signal for ring carbon C1
is a doublet of triplets of doublets pattern. The large
doublet coupling (J ) 74.0 Hz) is due to the trans-
equatorial phosphine, while the smaller triplet (J ) 11.3
Hz) and doublet (J ) 5.0 Hz) couplings result from the
axial and cis-equatorial phosphines, respectively. The
1H NMR signal for ring proton H1 is likewise a complex
multiplet, where the largest coupling (∼10 Hz) is due
to the cis-equatorial PMe3 ligand.
Bond Angles
Cl-Ir-P1
Cl-Ir-P2
Cl-Ir-P3
Cl-Ir-O1
Cl-Ir-C1
P1-Ir-P2
P1-Ir-P3
P1-Ir-O1
P1-Ir-C1
P2-Ir-P3
88.60(6)
89.93(7)
93.87(7)
84.33(14)
174.2(2)
168.11(6)
94.78(6)
83.76(13)
88.60(6)
97.09(7)
P2-Ir-O1
P2-Ir-C1
P3-Ir-O1
P3-Ir-C1
O1-Ir-C1
Ir-C1-C2
C1-C2-C3
C2-C3-C4
C3-C4-O1
Ir-O1-C4
84.36(13)
86.9(2)
177.70(13)
91.4(2)
90.5(2)
125.3(5)
125.1(7)
125.9(7)
127.3(6)
125.2(4)
When 2 is treated with bis(triphenylphosphoranyli-
dene)ammonium chloride (PPN+Cl-), chloride addition
product 6 (Scheme 3) is generated. This compound bears
a close resemblance to compounds 3 and 5, except that
the chloride ligand in 6 resides trans to ring carbon C1,
while the equatorial phosphine lies trans to oxygen. This
ligand arrangement is evident from the 13C{1H} NMR
spectrum of 6, where ring carbon C1 exhibits only weak
coupling (J C-P ) 7.7 Hz) to the equatorial phosphine
ligand. Ring proton H1, on the other hand, is rather
strongly coupled to this cis-equatorial phosphine, giving
All of the derivatives shown in Scheme 3 contain the
iridaoxacyclohexa-1,3-diene ring skeleton and hence
exhibit similar NMR chemical shifts for ring carbons
and hydrogens. In each case, carbon C4 resonates
farthest downfield (range δ 154.2-156.8; average δ
155.7) because it resides R to the oxygen atom, experi-
ences a strong inductive effect, and is the most positive
ring carbon. On the other hand, carbons C3 (range δ
97.4-100.4; average δ 98.9) and C1 (range δ 94.3-119.7;
average δ 107.6) resonate farthest upfield due to reso-
nance effects involving the oxygen lone pairs. As shown,
minor resonance structures can be drawn (B and C) in
1
rise to a doublet in the H NMR spectrum (J H-P ) 10.5
Hz).
(14) Huheey, J . E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry:
Principles of Structure and Reactivity, 4th ed.; HarperCollins: New
York, 1993; pp 543-547.
The structure of 6 has been confirmed by X-ray
crystallography (see ORTEP drawing in Figure 1).
Selected bond distances and angles are reported in
Table 1. As expected, the molecule is octahedral with
the phosphine ligands in a mer arrangement and the
(15) In mer-CHdCHCHdCHOIr(H)(PEt3)3, where C1 lies trans to
a PEt3 ligand, the Ir-C1 bond distance is 2.072(12) Å. See: Bleeke, J .
R.; Haile, T.; Chiang, M. Y. Organometallics 1991, 10, 19.

328 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
Sch em e 4
which negative charge is localized on these ring carbon
atoms.16 Carbon C2 resonates in a chemical shift region
temperature adduct with a static, facial arrangement
of PEt3 ligands. This cooling process is accompanied by
a color change from deep purple (2) to light yellow
(adduct) and is reversible. The NMR spectra of the
adduct, recorded at -40 °C in acetone-d6, clearly
demonstrate that it is the [4 + 2] cycloaddition product
8, as shown in Scheme 5. In particular, the signals for
H3 and C3 shift upfield to δ 3.95 and 74.9, respectively,
indicating that these atoms are no longer aromatic or
olefinic. Furthermore, the C4 signal shifts far downfield
to δ 224.5, as expected for a carbonyl carbon, while the
central carbon of the acetone moiety, C7, resonates at
δ 64.9, consistent with alkoxide character. The con-
nectivity of the molecule is further demonstrated by the
observation of coupling between C3 and C7 (J ) 30.3
Hz) when 13C-labeled acetone is used in the experi-
ment.18
While the acetone adduct (8) is stable only at low
temperature, other unsaturated substrates, including
alkynes and alkenes, react irreversibly with 2 to form
[4 + 2] cycloadducts that are stable at room tempera-
ture. For example, treatment of 2 with methyl propi-
olate, phenylacetylene, or (trimethylsilyl)acetylene gen-
erates cycloadducts 9-11, respectively (see Scheme 5),
which possess iridaoxabarrelene frameworks.18 Each of
these reactions is accompanied by a dramatic color
change from purple to yellow. The methyl propiolate
reaction occurs upon warming to room temperature,
while the (trimethylsilyl)acetylene reaction requires 1
h of stirring at room temperature, suggesting that
electron-poor alkynes are the preferred substrates.
The 31P{1H} NMR spectra of 9-11 each consist of
three separate doublet-of-doublet patterns, consistent
with a fac phosphine geometry. As in the case of the
acetone adduct 8, the signal for C3 is shifted upfield in
the 13C NMR (range δ 67.5-72.0; average δ 70.4),
indicating an sp3 center. Carbon C4 is likewise shifted
between C4 and C1/C3 (range δ 124.6-128.0; average
δ 126.6). In the 1H NMR, ring hydrogen H1 always
resonates farther downfield than H3 due to the mag-
netic anisotropic influences of the large metal atom. The
average H1 shift for compounds 3 and 5-7 is δ 6.04
(range δ 5.72-6.32), while the average H3 shift is δ 4.64
(range δ 4.38-4.76).
C. Rea ctivity of Ir id a p yr yliu m 2: [4 + 2] Cy-
cloa d d ition s.17 When iridapyrylium 2 is dissolved in
acetone-d6 at room temperature, its 31P NMR signal
broadens dramatically and three new broad humps
appear upfield in the 31P NMR spectrum. As the sample
is cooled to -40 °C, the iridapyrylium signal disappears
and the upfield humps sharpen into three clean doublet-
of-doublet signals, indicating the formation of a low-
(16) For a discussion of inductive effects vs resonance effects, see:
Morrison, R. T.; Boyd, R. N. Organic Chemistry, 5th ed.; Allyn and
Bacon: Boston, 1987; pp 202-203.
(17) For a good summary of cycloaddition reactions involving organic
components, see: Lowry, T. H.; Richardson, K. S. Mechanism and
Theory in Organic Chemistry, 3rd ed.; Harper and Row: New York,
1987; pp 903-931.
(18) While [4 + 2] cycloadditions are common reactions of iridaben-
zene 1, it shows no reactivity toward acetone or alkynes.

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 329
Sch em e 5
far downfield (range δ 217.6-219.7; average δ 218.5),
as expected for a carbonyl carbon. In each 13C{1H} NMR
spectrum, there are two carbons that are strongly
coupled to phosphorus (range 73.1-78.9 Hz; average
75.9 Hz), indicating that these are the R-ring carbons,
C1 and C7. The signal for C7 (a former alkyne carbon)
is always farther downfield (range δ 144.6-169.4;
average δ 159.0) than that for C1 (range δ 137.4-137.9;
average δ 137.6). â-Ring carbons C2 and C8 appear
within a rather narrow chemical shift range, δ 124.3-
131.0, and show little or no phosphorus coupling.
In the 1H NMR spectra of 9-11, there are always two
signals far downfield, one for H1 (range δ 7.10-7.19;
average δ 7.14) and the other for H7, the former alkyne
hydrogen (range δ 7.89-9.66; average δ 8.68). The
extreme downfield shift for H7 strongly supports the
regiochemistry of cycloaddition shown in Scheme 5 (i.e.,
the CH end of the alkyne is bonded to the iridium
center). This regiochemistry has been confirmed by two-
dimensional HMQC experiments, which show that the
downfield proton H7 is directly bonded to the phosphorus-
coupled carbon C7. The ring proton H3, which is doubly
allylic and is R to a CdO group, resonates in the range
δ 5.12-5.50 (average δ 5.25), farther downfield than H3
in the acetone adduct 8 (δ 3.95).
substrates are unreactive toward 2 or lead to slow
decomposition. These include terminal olefins such as
styrene and neo-hexene as well as constrained olefins
such as cyclopentene and maleic anhydride. The one
exception is methyl acrylate, which reacts slowly (5 h)
with 2 at room temperature to produce the [4 + 2]
cycloadduct 12 (Scheme 5). As a cycloaddition substrate,
methyl acrylate apparently benefits from the fact that
it is both terminal and electron-poor.
The 31P{1H} NMR spectrum of 12 is similar to those
of 9-11, except that there are two sets of peaks in an
approximate 55:45 ratio, indicating the presence of two
isomers with fac phosphine geometries. Similarly, the
13C NMR spectrum of 12 shows the presence of two
isomers; each carbon peak has a partner with a similar
chemical shift. The chemical shifts for ring carbons C1,
C2, C3, and C4 are close to those observed in 9-11,
while C7 and C8 are shifted far upfield, consistent with
their sp3 character in 12. In both isomers, the terminal
(CH2) carbon of the methyl acrylate moiety shows strong
phosphorus coupling, indicating that it is bonded di-
rectly to iridium. This, in turn, implies that the isomers
are not regioisomers but rather stereoisomers with
opposite stereochemistries at C8. In the 1H NMR
spectrum of 12, ring proton H1 resonates at δ 7.67 and
7.48 in the two isomers, while H3 resonates at δ 4.29
and 4.24. As expected, the protons on the ring’s satu-
rated moiety (H7’s and H8) are shifted upfield and
appear in the region δ 1.3-2.5.
Only terminal alkynes react cleanly with 2; disubsti-
tuted alkynes such as 2-butyne and diphenylacetylene
are unreactive or lead to slow decomposition of 2 upon
stirring at room temperature. Similarly, many alkene

330 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) w ith Estim a ted Sta n d a r d Devia tion s for
-
{fa c-[CHdC(Me)CHC(Me)dOIr S(O)2](P Et3)3}+BF 4
(13)
Bond Distances
Ir-P1
Ir-P2
Ir-P3
Ir-S1
Ir-O1
Ir-C1
C1-C2
C2-C3
2.4202(18)
2.3058(18)
2.3788(17)
2.3685(17)
2.184(4)
2.078(6)
1.326(10)
1.516(11)
C2-C5
C3-C4
S1-C3
C4-C6
O1-C4
S1-O2
S1-O3
1.503(11)
1.483(10)
1.848(7)
1.483(10)
1.263(8)
1.462(5)
1.454(5)
Bond Angles
P1-Ir-P2
P1-Ir-P3
P1-Ir-S1
P1-Ir-O1
P1-Ir-C1
P2-Ir-P3
P2-Ir-S1
P2-Ir-O1
P2-Ir-C1
P3-Ir-S1
P3-Ir-O1
P3-Ir-C1
S1-Ir-O1
S1-Ir-C1
97.33(7)
97.24(6)
94.35(6)
88.64(14)
170.49(19)
98.28(6)
O1-Ir-C1
Ir-C1-C2
C1-C2-C3
C2-C3-C4
C2-C3-S1
C4-C3-S1
C3-C4-O1
Ir-O1-C4
Ir-S1-O2
Ir-S1-O3
Ir-S1-C3
O2-S1-O3
C3-S1-O2
C3-S1-O3
83.1(2)
117.2(5)
116.5(6)
107.4(6)
104.2(5)
103.3(5)
118.7(6)
115.6(4)
116.0(2)
120.6(2)
89.6(2)
96.30(6)
170.90(13)
90.33(18)
160.02(6)
87.73(13)
87.17(18)
76.31(13)
79.14(19)
F igu r e 2. ORTEP drawing of {fac-[CHdC(Me)CHC(Me)d
114.2(3)
105.2(3)
105.9(3)
-
OIrS(O)2](PEt3)3}+BF4 (13).
Also notable is the constrained internal angle at sulfur
(C3-S1-Ir ) 89.6(2)°). Bonding within the iridaoxacy-
clohexa-1,4-diene ring is localized, as expected.
Although the detailed mechanisms of reactions lead-
ing to cycloadducts 8-12 are not known, it seems likely
that they proceed in a concerted (Diels-Alder) fashion
with the key orbital interaction involving a filled
π-orbital on the iridapyrylium ring and an empty π*
orbital on the unsaturated substrate. Undoubtedly,
these reactions are driven by the formation of a strong
C-O double bond in the ring and a stable octahedral
coordination geometry around the Ir(III) center. Note,
however, that in the formation of the acetone adduct, a
C-O double bond is also lost, which may explain why
this reaction is reversible.
Finally, treatment of 2 with sulfur dioxide results in
a cheleotropic [4 + 2] cycloaddition and production of
adduct 13 (Scheme 5). The 31P{1H} NMR spectrum of
13 consists of three doublet-of-doublet patterns, indica-
tive of a fac phosphine geometry. The 13C{1H} NMR
spectrum is similar to those of cycloadducts 8-12 with
carbonyl carbon C4 shifting downfield to δ 221.0 and
olefinic carbons C1 and C2 resonating at δ 147.4 and
133.9, respectively. The chemical shift of saturated
carbon C3 is, however, unusually high (δ 105.4), perhaps
reflecting the strongly electron-withdrawing nature of
the SO2 group. Ring protons H1 and H3 resonate at δ
7.67 and 5.55, respectively.
The structure of 13 has been confirmed by X-ray
crystallography. An ORTEP drawing is presented in
Figure 2, while selected bond distances and angles are
listed in Table 2. The sulfur atom of the SO2 unit is
bonded to Ir and ring carbon C3, causing the iridaox-
acyclohexa-1,4-diene ring to adopt a boat conformation.
Ir and C3 lie 1.063 and 0.727 Å, respectively, from the
C1/C2/C4/O1 plane, while the dihedral angles made by
planes C1/Ir/O1 and C2/C3/C4 with the C1/C2/C4/O1
plane are 41.8 and 55.0°, respectively. This rather
severe bending of the ends of the boat is undoubtedly
due to the demands of the five-membered rings in 13.
Cycloadducts 9-12 give lovely FAB mass spectra. In
each case, the parent ion envelope [M]+ is easily
detected and the [M - PEt3]+ envelope contains the
largest peaks in the spectrum. In contrast, the FAB
mass spectrum of 13 does not feature prominent peaks
for [M+] and [M - PEt3]+. Instead, the largest peaks in
the spectrum are those attributable to the parent
iridapyrylium 2, indicating that under the mass spectral
analysis conditions, SO2 is cleanly released.19
D. Rea ctivity of Ir id a p yr yliu m 2: [2 + 2] Cy-
cloa d d ition a n d Rea r r a n gem en t. When iridapyry-
lium 2 is treated with nitrosobenzene (PhNdO), a
surprising product (14) is obtained. The 31P{1H} NMR
spectrum of 14 indicates a fac arrangement of the three
PEt3 ligands, consistent with a cycloadduct. However,
the 13C{1H} NMR spectrum of 14 shows clearly that ring
carbon C1 is no longer bonded to the iridium center (no
C-P coupling), while the neighboring carbon C2 is
bonded to Ir (J C-P ) 78.7 Hz). Furthermore, the chemi-
cal shift of C2 (δ 42.7) indicates that it is no longer
aromatic or olefinic. In contrast, the signals for ring
carbons C1, C3, and C4 remain in the olefinic region of
the spectrum (δ 156.8, 102.0, and 172.3, respectively).
1
In the H NMR, H1 and H3 resonate at δ 7.25 and 3.56,
respectively.
The novel structure of 14 has been established by
X-ray crystallography (see Figure 3 for an ORTEP
drawing and Table 3 for selected bond distances and
angles). The molecule contains two metallacycles, which
are fused along the Ir-C2 bond. The sum of the five
internal angles in the metallacycle Ir/C2/C3/C4/O1 is
538.8°, while the corresponding sum in the metallacycle
(19) The mass spectra of 2 obtained in this way are of higher quality
than those obtained directly from pure 2, which is more air-sensitive
than 13 and harder to handle.

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 331
Sch em e 6
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) w ith Estim a ted Sta n d a r d Devia tion s for
-
{fa c-[C(Me)CHdC(Me)OIr ON(P h )dCH](P Et3)3}+BF 4
(14)
Bond Distances
Ir-P1
Ir-P2
Ir-P3
Ir-O1
Ir-O2
Ir-C2
O2-N1
N1-C1
2.315(3)
2.405(4)
2.300(4)
2.089(9)
2.112(9)
2.178(13)
1.323(14)
1.320(20)
N1-C41
C1-C2
C2-C5
C2-C3
C3-C4
C4-C6
O1-C4
1.449(21)
1.517(22)
1.493(21)
1.496(25)
1.347(23)
1.524(24)
1.337(20)
Bond Angles
P1-Ir-P2
P1-Ir-P3
P1-Ir-O1
P1-Ir-O2
P1-Ir-C2
P2-Ir-P3
P2-Ir-O1
P2-Ir-C2
P2-Ir-C2
P3-Ir-O1
P3-Ir-O2
P3-Ir-C2
98.7(1)
97.6(1)
173.6(3)
92.3(3)
92.8(5)
94.9(1)
87.1(3)
82.6(3)
160.6(4)
84.5(3)
170.0(3)
98.9(4)
O1-Ir-O2
O1-Ir-C2
O2-Ir-C2
Ir-O2-N1
O2-N1-C1
N1-C1-C2
Ir-C2-C1
C1-C2-C3
Ir-C2-C3
C2-C3-C4
C3-C4-O1
Ir-O1-C4
85.7(4)
80.9(5)
81.5(4)
112.6(8)
120.1(12)
122.2(12)
102.4(9)
98.5(12)
105.3(9)
118.9(4)
120.9(15)
113.1(9)
synthesized. Compound 2, like its metallabenzene ana-
logue CHdC(Me)CHdC(Me)CHdIr(PEt3)3 (1), exhibits
F igu r e 3. ORTEP drawing of {fac-[C(Me)CHdC(Me)-
1
-
OIrON(Ph)dCH](PEt3)3}+BF4 (14).
downfield H NMR chemical shifts for its ring protons,
consistent with the presence of an aromatic ring current.
Unlike 1, compound 2 reacts with 2e- donors at iridium
in an associative manner, generating six-coordinate
Ir(III) products with the iridaoxacyclohexa-1,3-diene
ring skeleton. This reactivity results primarily from the
fact that the electrons in the Ir-O π bond of 2 can be
localized on oxygen, rendering the iridium atom a
reactive 16e- center. The positive charge on 2 also
contributes to its enhanced reactivity toward anionic
reagents such as hydride, methyllithium, and chloride.
Like 1, compound 2 undergoes [4 + 2] cycloaddition
reactions with a variety of unsaturated substrates. For
example, both 1 and 2 react in a cheleotropic fashion
with sulfur dioxide and both undergo cycloaddition with
electron-poor olefins in Diels-Alder type processes.
However, 2 also forms cycloadducts with a series of
alkyne substrates that are completely unreactive toward
1. The enhanced reactivity of 2 in this case undoubtedly
results from the fact that a strong, localized carbon-
oxygen double bond is formed in the product. It is also
interesting to note that 2 undergoes reversible cycload-
dition with ketones such as acetone. In this case, the
formation of a carbon-oxygen double bond in the
product is offset by the loss of a carbon-oxygen double
bond in the ketone substrate. One final contrast involves
the reactivity of 1 with 2 with nitrosobenzene. 1 reacts
Ir/O2/N1/C1/C2 is 539.1°. Both numbers are close to the
theoretical value of 540° required for planar pentagons.
The two rings are virtually perpendicular to one an-
other, as dictated by the octahedral coordination geom-
etry around the iridium atom. The dihedral angle made
by the two ring planes is 89.1°. The phenyl ring on N1
is tilted at a 39.6° angle to the Ir/O2/N1/C1/C2 plane.
Bond distances within the two metallacycles of 14 are
consistent with the localized structure shown in Scheme
6.
Although the mechanism of this reaction is not
known, the connectivity of the final product (i.e., nitro-
gen bonded to C1) suggests that the initial interaction
may be a [2 + 2] cycloaddition involving the NO double
bond of nitrosobenzene and the metal-carbene bond of
2. Rearrangement of this strained cycloadduct, A (Scheme
6), could lead to the observed product 14. It is interest-
ing to note that iridabenzene 1 also reacts with ni-
trosobenzene, but the product in this case is a [4 + 2]
cycloadduct which undergoes no further rearrangement.
Su m m a r y
The first example of a stable metallapyrylium,
[CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4- (2), has been

332 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
purple precipitate of compound 2 formed. The solution was
passed through a glass frit to give a yellow filtrate of 3, which
was recovered and reused. Methylene chloride was added to
redissolve the purple precipitate of 2, and the solution was
filtered. The methylene chloride was then removed under
vacuum. Yield of 2: 280 mg (42%).
with this substrate in a standard [4 + 2] fashion, while
2 appears to initially form a [2 + 2] cycloadduct, which
then rearranges to a novel product containing two fused
five-membered rings. The reasons for this divergent
behavior are not understood.
High-resolution FAB-MS: calcd for [M]+ (C24H53191IrOP3+),
641.2918; found, 641.2926.
Exp er im en ta l Section
1H NMR (methylene chloride-d2, 23 °C): δ 9.35 (qd, J H-P
)
Gen er a l Com m en ts. 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 and 13C-labeled NMR solvents were ob-
tained from Cambridge Isotope Laboratories or from Aldrich
in sealed vials and used as received. The following reagents
were used as obtained from the supplier indicated: silver
tetrafluoroborate (Aldrich), lithium diisopropylamide (Aldrich),
tetrafluoroboric acid (Aldrich), lithium tri-tert-butoxyalumi-
nohydride (Aldrich), methyllithium (Aldrich), bis(triphenylphos-
phoranylidene)ammonium chloride (PPN+Cl-; Aldrich), tri-
methylphosphine (Strem), methyl propiolate (Aldrich), phenyl-
acetylene (Aldrich), (trimethylsilyl)acetylene (Aldrich), sulfur
dioxide (Aldrich), nitrosobenzene (Aldrich). Methyl acrylate
(Aldrich) was dried over calcium hydride and distilled before
use. A detailed synthesis and full NMR characterization of
6.0 Hz, J H-H3 ) 1.6 Hz, 1, H1), 6.45 (d, J H-H1 ) 1.6 Hz, 1, H3),
2.38 (s, 3, ring CH3) 2.33 (s, 3, ring CH3), 1.95 (dq, J H-P ) 7.5
Hz, J H-H ) 7.5 Hz, 18, PEt3 CH2’s), 1.00 (dt, J H-P ) 15.5 Hz,
J H-H ) 7.5 Hz, 27, PEt3 CH3’s).
13C{1H} NMR (methylene chloride-d2, 23 °C): δ 170.7 (s,
C4), 162.2 (q, J C-P ) 22.7 Hz, C1), 147.3 (s, C2), 112.2 (s, C3),
28.5 (d, J C-P ) 2.8 Hz, ring CH3), 26.3 (br s, ring CH3), 19.8
(d, J C-P ) 32.8 Hz, PEt3 CH2’s), 9.0 (br s, PEt3 CH3’s).
31P{1H} NMR (methylene chloride-d2, 23 °C): δ 1.9 (br s, 3,
PEt3’s).
In d ep en d en t Syn th esis of [m er -CHdC(Me)CH2C(Me)d
OIr (H)(P Et3)3]+BF 4- (4). Compound 3, mer-CHdC(Me)CHd
C(Me)OIr(H)(PEt3)3 (50 mg, 0.077 mmol), was dissolved in 10
mL of diethyl ether to form a yellow solution and cooled to
-30 °C. To this solution was added HBF4‚OEt2 (12 mg, 0.077
mmol) in 5 mL of cold (-30 °C) diethyl ether. As the addition
proceeded, a white microfine precipitate of 4 formed and
remained suspended in the ether. Upon standing at -30 °C,
the precipitate dropped to the bottom of the flask, leaving a
clear solution, which was decanted. The residual ether was
removed in vacuo, and the product was washed with pentane
and dried under vacuum. Yield of 4: 54 mg (96%).
Anal. Calcd for C24H55BF4IrOP3: C, 39.39; H, 7.59. Found:
C, 39.19; H, 7.49.
mer-CHdC(Me)CHdC(Me)OIr(H)(PEt3)3 (3) is given in ref 7.
However, the J H-P values for the metal hydride signal are
incorrectly reported as 28.1 (t) and 17.2 Hz (d). The correct
couplings are 15.6 (t) and 9.3 Hz (d).
NMR experiments were performed on a Varian Unity Plus-
300 spectrometer (1H, 300 MHz; 13C, 75 MHz; 31P, 121 MHz;
29Si, 60 MHz), a Varian Unity Plus-500 spectrometer (1H, 500
MHz; 13C, 125 MHz; 31P, 202 MHz), or a Varian Unity-600
spectrometer (1H, 600 MHz; 13C, 150 MHz; 31P, 242 MHz). 1H,
13C, and 29Si spectra were referenced to tetramethylsilane,
High-resolution FAB-MS: calcd for [M]+ (C24H55193IrOP3+),
645.3096; found, 645.3097.
1
while 31P spectra were referenced to external H3PO4. Some H
1H NMR (methylene chloride-d2, 22 °C): δ 6.67 (d, J H-P
)
connectivities were determined from COSY (1H-1H correlation
spectroscopy) data. HMQC (1H-detected multiple quantum
coherence) and HMBC (heteronuclear multiple bond correla-
tion) experiments aided in assigning some of the 1H and 13C
peaks.
3.0 Hz, 1, H1), 3.86 (t, J H-P ) 6.0 Hz, 2, H3’s), 2.22 (s, 3, ring
CH3), 1.86 (dq, J H-P ) 7.5 Hz, J H-H ) 7.5 Hz, 6, PEt3 CH2’s),
1.79-1.72 (m, 6, PEt3 CH2’s), 1.71 (s, 3, ring CH3), 1.66-1.58
(m, 6, PEt3 CH2’s), 1.07 (dt, J H-P ) 14.5 Hz, J H-H ) 7.5 Hz, 9,
PEt3 CH3’s), 0.95 (m, 18, PEt3 CH3’s), -27.51 (td, J H-P ) 16.5
Hz, 12.0 Hz, 1, Ir-H).
Low-resolution and high-resolution fast atom bombardment
(FAB) mass spectra were obtained on a Kratos MS50 three-
sector tandem mass spectrometer. Microanalyses were per-
formed by Galbraith Laboratories, Inc., Knoxville, TN.
13C{1H} NMR (methylene chloride-d2, 22 °C): δ 215.7 (s,
C4), 125.7 (dt, J C-P ) 75.0 Hz, 14.0 Hz, C1), 120.8 (t, J C-P
)
4.5 Hz, C2), 50.3 (s, C3), 31.0 (s, ring CH3), 28.7 (d, J C-P ) 9.8
Hz, ring CH3), 20.1 (d, J C-P ) 25.6 Hz, PEt3 CH2’s), 16.8
(virtual t, J C-P ) 34.3 Hz, PEt3 CH2’s), 8.4 (d, J C-P ) 2.2 Hz,
PEt3 CH3’s), 7.9 (s, PEt3 CH3’s).
Syn th esis of [CHdC(Me)CHdC(Me)OdIr (P Et3)3]+BF 4
-
(2). Compound 3, mer-CHdC(Me)CHdC(Me)OIr(H)(PEt3)3
(600 mg, 0.93 mmol), was dissolved in 75 mL of tetrahydro-
furan (THF) to form a yellow solution and cooled to -47 °C.
Silver tetrafluoroborate (180 mg, 0.93 mmol) was dissolved in
25 mL of THF and added to the stirred solution of 3 over 2 h.
As the addition proceeded, the solution darkened to black-
orange. When the addition was complete, the solution was
warmed to room temperature, during which time it became
opaque purple. After addition of 70 mL of pentane, the solution
was filtered through a glass frit. The solvent was removed in
vacuo to reveal a bright purple film containing a 1:1 product
31P{1H} NMR (methylene chloride-d2, 22 °C): δ -6.0 (d, J P-P
) 17.0 Hz, 2, PEt3’s), -17.8 (t, J P-P ) 17.0 Hz, 1, PEt3).
Syn th esis of m er -CHdC(Me)CHdC(Me)OIr (H)(P Et3)3
(3) fr om 2. Compound 2, [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+-
BF4- (40 mg, 0.055 mmol), was dissolved in 15 mL of tetrahy-
drofuran and cooled to -30 °C. Similarly, lithium tri-tert-
butoxyaluminohydride (27 mg, 0.11 mmol) was dissolved in 5
mL of tetrahydrofuran and cooled to -30 °C. The hydride
reagent solution was then added dropwise to the stirred
solution of compound 2, causing an immediate color change
from purple to yellow. After the solution was warmed to room
temperature, the solvent was removed under vacuum. Multiple
extractions with pentane followed by filtration gave a trans-
lucent yellow solution. The pentane was removed in vacuo to
give a yellow solid. Yield of 3: 8 mg (23%).7
-
mixture of [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4 (2) and
[mer-CHdC(Me)CH2C(Me)dOIr(H)(PEt3)3]+BF4 (4). Yield of
-
mixture: 640 mg (94%).
The bright purple film was redissolved in 40 mL of THF
and cooled to -30 °C. Lithium diisopropylamide (65 mg, 0.60
mmol) in 10 mL of THF was added dropwise to the stirred
solution, and the solvent was then removed under vacuum.
Addition and vacuum removal of a small amount of methylene
chloride was repeated twice to facilitate residual THF removal.
The resultant film was dissolved in 4 mL of methylene
chloride to which ∼220 mL of pentane was added until a
Syn th esis of mer -CHdC(Me)CHdC(Me)OIr (CH3)(P Et3)3
(5). A 100 µL amount of 1.4 M methyllithium in diethyl ether
(0.14 mmol) was added to a stirred solution of compound 2,
[CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4- (50 mg, 0.068 mmol),

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 333
in 25 mL of tetrahydrofuran at -72 °C. After a few seconds
the solution color changed from purple to a greenish yellow.
The reaction mixture was warmed to room temperature, and
the solvent was removed under vacuum. The resulting solid
was extracted with ether and filtered, and the solvent was
again removed under vacuum to give a yellow-green film. Yield
of 5: 13 mg (29%).
Three times this volume of silica was placed into a column,
followed by the product-containing fraction. The column was
wetted with diethyl ether and eluted with a 20% mixture of
tetrahydrofuran in ether. When this fraction ran clear, tet-
rahydrofuran was used to flush the column. A translucent
yellow solution resulted. After in vacuo concentration, diffusion
of ether into the tetrahydrofuran solution at -30 °C gave
orange plates. Anal. Calcd for C18H44BF4IrOP4: C, 31.81; H,
6.54. Found: C, 31.72, H, 6.73.
High-resolution FAB-MS: calcd for [M - PEt3 + H]+
(C19H42191IrOP2+), 539.2317; found, 539.2318.
1H NMR (benzene-d6, 25 °C): δ 6.09 (br s, 1, H1), 4.73 (s, 1,
H3), 2.20 (br s, 3, ring CH3), 1.99 (s, 3, ring CH3), 2.0-1.8 (m,
18, PEt3 CH2’s), 1.1-0.9 (m, 27, PEt3 CH3’s), 0.42 (pseudo q,
J H-P ) 6.0 Hz, 3, Ir-CH3).
High-resolution FAB-MS: calcd for [M]+ (C18H44193IrOP4+),
593.1972; found, 593.1964.
1H NMR (methylene chloride-d2, 23 °C): δ 5.72 (br m, 1,
H1), 4.38 (s, 1, H3), 1.74 (br s, 3, ring CH3), 1.63 (d, J H-P
9.5 Hz, 9, PMe3 CH3’s), 1.59 (s, 3, ring CH3), 1.55 (d, J H-P
)
)
13C{1H} NMR (benzene-d6, 25 °C): δ 155.8 (s, C4), 126.4
(m, C2), 119.7 (dt, J C-P ) 86.0 Hz, 16.0 Hz, C1), 98.3 (s, C3),
29.5 (d, J C-P ) 10.7 Hz, ring CH3), 26.4 (s, ring CH3), 18.7 (d,
J C-P ) 19.0 Hz, PEt3 CH2’s), 14.5 (virtual t, J C-P ) 29.7 Hz,
PEt3 CH2’s), 8.6 (s, PEt3 CH3’s), 8.3 (s, PEt3 CH3’s), -39.6 (td,
J C-P ) 7.4 Hz, 3.2 Hz, Ir-CH3).
8.0 Hz, 9, PMe3 CH3’s), 1.44 (virtual t, J H-P ) 7.0 Hz, 18, PMe3
CH3’s).
13C{1H} NMR (methylene chloride-d2, 23 °C): δ 154.2 (s,
C4), 128.0 (m, C2), 107.6 (dtd, J C-P ) 74.0 Hz, 11.3 Hz, 5.0
Hz, C1), 100.4 (s, C3), 28.0 (d, J C-P ) 11.1 Hz, ring CH3), 23.7
(d, J C-P ) 7.2 Hz, ring CH3), 19.2 (d, J C-P ) 38.0 Hz, PMe3
CH3’s), 17.4 (d, J C-P ) 28.2 Hz, PMe3 CH3’s), 15.8 (virtual t,
J C-P ) 38.0 Hz, PMe3 CH3’s).
31P{1H} NMR (benzene-d6, 25 °C): δ -24.3 (d, J P-P ) 16.0
Hz, 2, PEt3’s), -37.3 (t, J P-P ) 16.0 Hz, 1, PEt3).
Syn th esis of m er -CHdC(Me)CHdC(Me)OIr (Cl)(P Et3)3
31P{1H} NMR (methylene chloride-d2, 23 °C): δ -37.1 (dd,
J P-P ) 20.0 Hz, 17.0 Hz, 2, PMe3’s), -52.4 (td, J P-P ) 17.0
Hz, 8.3 Hz, 1, PMe3), -55.7 (td, J P-P ) 20.0 Hz, 8.3 Hz, 1,
PMe3).
(6). Compound 2, [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4
-
(120 mg, 0.17 mmol), was dissolved in 20 mL of tetrahydro-
furan to form a purple solution and cooled to -30 °C. This
solution was added dropwise to a -30 °C solution of bis-
(triphenylphosphoranylidene)ammonium chloride (PPN+Cl-;
120 mg, 0.21 mmol) in 20 mL of tetrahydrofuran and 5 mL of
methylene chloride. The purple solution instantly turned
lemon yellow on contact with the PPN+Cl- solution. The
solvent was removed in vacuo. The resulting yellow-brown
solid was extracted with pentane and passed through a glass
frit to give a translucent lemon yellow solution, which produced
yellow crystals after concentration and cooling at -30 °C. Yield
of 6: 32 mg (28%). Anal. Calcd for C24H53ClIrOP3: C, 42.49;
H, 7.89. Found: C, 42.64; H, 8.22.
F or m a tion of {fa c-[CHdC(Me)CHC(Me)dOIr OC(Me)2]-
(P Et3)3}+BF 4- (8). Compound 2, [CHdC(Me)CHdC(Me)OdIr-
-
(PEt3)3]+BF4 (50 mg, 0.068 mmol), was dissolved in 0.5 mL
of acetone-d6 to form a purple solution. When the solution was
cooled, the color changed, ultimately becoming clear yellow
around -40 °C. When it was warmed, the solution reverted
to its original purple color. Repeated cooling and warming
cycles resulted in no significant product decomposition by
NMR.
1H NMR (acetone-d6, -40 °C): δ 7.15 (ddd, J H-P ) 6.6 Hz,
6.6 Hz, 5.4 Hz, 1, H1), 3.95 (m, 1, H3), 2.61 (s, 3, ring CH3),
1.86 (s, 3, ring CH3), 2.1-1.7 (m’s, 18, PEt3 CH2’s), 1.0-0.7
(br m’s, 27, PEt3 CH3’s).
High-resolution FAB-MS: calcd for [M + H]+ (C24H5435Cl-
191IrOP3+), 677.2685; found, 677.2697.
1H NMR (benzene-d6, 22 °C): δ 6.32 (d, J H-P ) 10.5 Hz, 1,
H1), 4.76 (br s, 1, H3), 2.12 (s, 3, ring CH3), 2.06 (s, 3, ring
CH3), 1.86-1.78 (m, 6, PEt3 CH2’s), 1.76 (dq, J H-P ) 7.5 Hz,
J H-H ) 7.5 Hz, 6, PEt3 CH2’s), 2.08-2.01 (m, 6, PEt3 CH2’s),
1.14 (virtual t of t, J H-P ) 14.0 Hz, J H-H ) 7.5 Hz, 18, PEt3
CH3’s), 0.91 (dt, J H-P ) 13.5 Hz, J H-H ) 7.5 Hz, 9, PEt3 CH3’s).
13C{1H} NMR (benzene-d6, 22 °C): δ 156.2 (s, C4), 124.6 (s,
C2), 99.1 (s, C3), 94.3 (pseudo q, J C-P ) 7.7 Hz, C1), 28.3 (s,
13C{1H} NMR (acetone-d6, -40 °C): δ 224.5 (d, J C-P ) 2.2
Hz, C4), 137.6 (ddd, J C-P ) 85.0 Hz, 7.7 Hz, 6.4 Hz, C1), 127.6
(s, C2), 74.9 (s, C3), 64.9 (dd, J C-P ) 3.5 Hz, 2.3 Hz, central
acetone C), 32.9 (d, J C-P ) 4.6 Hz, ring CH3), 27.2 (d, J C-P
)
9.3 Hz, ring CH3), 17.0 (d, J C-P ) 38.1 Hz, PEt3 CH2’s), 16.9
(d, J C-P ) 33.6 Hz, PEt3 CH2’s), 14.7 (d, J C-P ) 22.3 Hz, PEt3
CH2’s), 8.9 (d, J C-P ) 7.0 Hz, PEt3 CH3’s), 8.6 (d, J C-P ) 5.5
Hz, PEt3 CH3’s), 7.9 (d, J C-P ) 5.5 Hz, PEt3 CH3’s).
ring CH3), 25.6 (d, J C-P ) 7.6 Hz, ring CH3), 19.0 (d, J C-P
)
32.3 Hz, PEt3 CH2’s), 14.8 (virtual t, J C-P ) 30.0 Hz, PEt3
CH2’s), 8.8 (br s, PEt3 CH3’s).
31P{1H} NMR (acetone-d6, -40 °C): δ -20.6 (pseudo t, J P-P
) 10.5 Hz, 1, PEt3), -22.2 (dd, J P-P ) 19.0 Hz, 10.5 Hz, 1,
PEt3), -26.1 (dd, J P-P ) 19.0 Hz, 10.5 Hz, 1, PEt3).
31P{1H} NMR (benzene-d6, 22 °C): δ -18.3 (d, J P-P ) 17.6
Hz, 2, PEt3’s), -34.4 (t, J P-P ) 17.6 Hz, 1, PEt3).
Syn th esis of [CHdC(Me)CHdC(Me)OIr (P Me3)4]+BF 4
-
Syn t h esis of {fa c-[CH dC(Me)CH C(Me)dOIr CH dC-
(CO2Me)](P Et3)3}+BF 4 (9). A 1 mL solution of methyl
-
(7). Compound 2, [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4
-
propiolate (58 mg, 0.69 mmol) in tetrahydrofuran was slowly
(300 mg, 0.41 mmol), was dissolved in 50 mL of tetrahydro-
furan to form
a purple solution and cooled to -77 °C.
added to a stirred solution of compound 2, [CHdC(Me)CHdC-
Trimethylphosphine (1.04 g, 13.7 mmol) was dissolved in 10
mL of tetrahydrofuran and added to the stirred solution of 2
over 30 min. The solution lost the deep purple color and turned
yellow during the addition. When it was warmed to 25 °C, the
solution became translucent orange. After 3 h the tetrahydro-
furan was removed in vacuo, and the resultant brown-yellow
film was taken up in a minimum amount of methylene
chloride. The product was precipitated with diethyl ether and
recovered in methylene chloride. The methylene chloride
solution was passed through a glass frit, and the solvent was
removed in vacuo to give a yellow, slightly crystalline film.
Yield of 7: 200 mg (70%).
(Me)OdIr(PEt3)3]+BF4 (250 mg, 0.34 mmol), in 25 mL of
-
tetrahydrofuran at -72 °C. When the cold bath was removed
and the solution warmed to room temperature, the color
changed from purple to a dark yellow. The solvent was
removed under vacuum, and the resulting solid was washed
three times with pentane (5 mL each) and three times with
diethyl ether (10 mL each). Finally the solid was dissolved in
acetone and filtered. The acetone was removed in vacuo to give
a dark yellow foam. Yield of 9: 170 mg (62%).
High-resolution FAB-MS: calcd for [M]+ (C28H57193IrO3P3+),
727.3150; found, 727.3138.
1H NMR (acetone-d6, 25 °C): δ 9.66 (dtd, J H-P ) 7.5 Hz,
J H-P ) 4.5 Hz, J H-H3 ) 2.0 Hz, 1, H7), 7.19 (m, 1, H1), 5.50 (d,
To obtain crystals, the above product was dissolved in
tetrahydrofuran and vacuum-deposited onto silanized silica.

334 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
J H-H7 ) 2.0 Hz, 1, H3), 3.70 (s, 3, OCH3), 2.79 (br s, 3, ring
CH3), 2.11 (s, 3, ring CH3), 2.3-1.7 (m, 18, PEt3 CH2’s), 1.3-
0.9 (m, 27, PEt3 CH3’s).
CH3), 19.8 (d, J C-P ) 37.1 Hz, PEt3 CH2’s), 17.6 (d, PEt3 CH2’s),
17.2 (d, PEt3 CH2’s), 10.0-7.0 (m, PEt3 CH3’s), -1.2 (s, Si-
CH3’s).
31P{1H} NMR (acetone-d6, 25 °C): δ -19.8 (dd, J P-P ) 12.4
Hz, 11.9 Hz, 1, PEt3), -25.3 (dd, J P-P ) 18.3 Hz, 12.4 Hz, 1,
PEt3), -26.1 (dd, J P-P ) 18.3 Hz, 11.9 Hz, 1, PEt3).
29Si{1H} NMR (acetone-d6, 25 °C): δ -5.9 (d, J Si-P ) 9.0
Hz, 1, Si).
13C{1H} NMR (acetone-d6, 25 °C): δ 219.7 (pseudo q, J C-P
) 3.5 Hz, C4), 169.4 (dm, J C-P ) 75.5 Hz, C7), 164.2 (d, J C-P
) 6.0 Hz, CO2), 137.9 (dt, J C-P ) 73.1 Hz, 7.8 Hz, C1), 125.8
(pseudo t, J C-P ) 3.6 Hz, C2), 124.3 (pseudo t, J C-P ) 3.6 Hz,
C8), 67.5 (s, C3), 51.9 (s, OCH3), 31.5 (d, J C-P ) 3.5 Hz, ring
CH3), 25.4 (d, J C-P ) 7.1 Hz, ring CH3), 20.0 (d, J C-P ) 39.4
Hz, PEt3 CH2’s), 17.7 (d, J C-P ) 25.2 Hz, PEt3 CH2’s), 17.3 (d,
J C-P ) 25.1 Hz, PEt3 CH2’s), 9.0-8.6 (m, PEt3 CH3’s).
31P{1H} NMR (acetone-d6, 25 °C): δ -18.8 (dd, J P-P ) 13.4
Hz, 12.5 Hz, 1, PEt3), -25.2 (dd, J P-P ) 18.9 Hz, 12.5 Hz, 1,
PEt3), -26.1 (dd, J P-P ) 18.9 Hz, 13.4 Hz, 1, PEt3).
Syn th esis of {fa c-[CHdC(Me)CHC(Me)dOIr CH2CH-
-
(CO2Me)](P Et3)3}+BF 4 (12). Methyl acrylate (32 mg, 0.37
mmol) was added dropwise to a stirred solution of compound
2, [CHdC(Me)CHdC(Me)OdIr(PEt3)3]+BF4 (53 mg, 0.073
-
mmol), in 15 mL of tetrahydrofuran at -30 °C. The reaction
mixture was warmed to room temperature and stirred for 5
h, during which time the color changed from purple to red and
finally to dark yellow. The solvent was removed under vacuum,
and the resulting solid was washed three times with pentane
(5 mL each) and three times with diethyl ether (10 mL each).
Finally the solid was dissolved in acetone and filtered. The
acetone was removed in vacuo to give a dark yellow film of a
mixture of two isomers. Yield of 12: 21 mg (35%).
Syn th esis of {fa c-[CHdC(Me)CHC(Me)dOIr CHdC(P h )]-
(P Et3)3}+BF 4- (10). A 2.5 mL solution of phenylacetylene (51
mg, 0.50 mmol) in tetrahydrofuran was added dropwise to a
stirred solution of compound 2, [CHdC(Me)CHdC(Me)OdIr-
(PEt3)3]+BF4 (250 mg, 0.34 mmol), in 25 mL of tetrahydro-
-
furan at -23 °C. This caused the color of the solution to change
from purple to red. After the solution was warmed to room
temperature, the solvent was removed under vacuum. Extrac-
tion with benzene was followed by filtration over a glass frit.
The volume of solvent was reduced to 3 mL, and diethyl ether
(100 mL) was added to form a yellow solution and a precipitate
or film. The precipitate was isolated via filtration and dried
under vacuum to give a brownish white solid. Yield of 10: 110
mg (39%).
High-resolution FAB-MS: calcd for [M]+ (C32H59191IrOP3+),
743.3385; found, 743.3395.
1H NMR (methylene chloride-d2, 25 °C): δ 7.89 (m, 1, H7),
7.34-7.16 (m, 5, phenyl H’s), 7.10 (m, 1, H1), 5.12 (br s, 1,
H3), 2.63 (br s, 3, ring CH3), 2.12 (s, 3, ring CH3), 2.1-1.8 (m,
18, PEt3 CH2’s), 1.3-0.9 (m, 27, PEt3 CH3’s).
High-resolution FAB-MS: calcd for [M]+ (C28H59193IrO3P3+),
729.3307; found, 729.3315.
Ma jor Isom er . 1H NMR (acetone-d6, 25 °C): δ 7.67 (br
pseudo q, J H-P ) 7.2 Hz, 1, H1), 4.29 (br s, 1, H3), 3.63 (s, 3,
OCH3), 2.73 (s, 3, ring CH3), 2.22 (buried, 1, H8), 2.05 (buried,
3, ring CH3), 1.55 (m, 1, H7a), 1.33 (buried, 1, H7b), 2.3-1.7
(m, 18, PEt3 CH2’s), 1.4-0.9 (m, 27, PEt3 CH3’s).
13C{1H} NMR (acetone-d6, 25 °C): δ 223.8 (s, C4), 175.2 (s,
CO2), 142.3 (dm, J C-P ) 82.5 Hz, C1), 125.2 (s, C2), 64.1 (s,
C3), 51.7 (s, OCH3), 35.1 (s, C8), 30.7 (d, J C-P ) 3.8 Hz, ring
CH3), 27.3 (d, J C-P ) 8.8 Hz, ring CH3), 24.0-17.0 (m, PEt3
CH2’s), 11.0-7.0 (m, PEt3 CH3’s), -0.5 (dm, J C-P ) 68.8 Hz,
C7).
31P{1H} NMR (acetone-d6, 25 °C): δ -24.9 (dd, J P-P ) 15.8
Hz, 11.5 Hz, 1, PEt3), -25.4 (pseudo t, J P-P ) 11.5 Hz, PEt3),
-26.4 (dd, J P-P ) 15.8 Hz, 11.5 Hz, 1, PEt3).
13C{1H} NMR (methylene chloride-d2, 25 °C): δ 218.3 (s,
C4), 144.6 (dm, J C-P ) 76.3 Hz, C7), 142.9 (s, phenyl ipso),
137.6 (dm, J C-P ) 77.6 Hz, C1), 131.0 (s, C8), 128.8 (s, phenyl
meta), 126.4 (s, phenyl para), 125.8 (s, phenyl ortho), 125.5
(s, C2), 72.0 (s, C3), 31.8 (d, J C-P ) 4.2 Hz, ring CH3), 25.6 (d,
J C-P ) 6.1 Hz, ring CH3), 19.9 (d, J C-P ) 39.3 Hz, PEt3 CH2),
17.6 (d, J C-P ) 24.9 Hz, PEt3 CH2), 17.4 (d, J C-P ) 24.8 Hz,
PEt3 CH2), 9.0-7.0 (m, PEt3 CH3’s).
Min or Isom er . 1H NMR (acetone-d6, 25 °C): δ 7.48 (br
pseudo q, J H-P ) 7.2 Hz, 1, H1), 4.24 (br s, 1, H3), 3.66 (s, 3,
OCH3), 2.73 (s, 3, ring CH3), 2.47 (m, 1, H8), 1.97 (buried, 3,
ring CH3), 1.71 (buried, 1, H7a), 1.35 (buried, 1, H7b), 2.3-
1.7 (m, 18, PEt3 CH2’s), 1.4-0.9 (m, 27, PEt3 CH3’s).
13C{1H} NMR (acetone-d6, 25 °C): δ 224.0 (s, C4), 178.4 (s,
CO2), 138.7 (dm, J C-P ) 82.5 Hz, C1), 127.4 (s, C2), 64.9 (s,
C3), 52.0 (s, OCH3), 41.9 (s, C8), 33.0 (d, J C-P ) 4.0 Hz, ring
CH3), 25.4 (d, J C-P ) 8.8 Hz, ring CH3), 24.0-17.0 (m, PEt3
CH2’s), 11.0-7.0 (m, PEt3 CH3’s), 1.1 (dm, J C-P ) 70.0 Hz, C7).
31P{1H} NMR (acetone-d6, 25 °C): δ -22.8 (dd, J P-P ) 12.0
Hz, 10.0 Hz, 1, PEt3), -25.7 (dd, J P-P ) 15.2 Hz, 12.0 Hz, 1,
PEt3), -27.4 (dd, J P-P ) 15.2 Hz, 10.0 Hz, 1, PEt3).
31P{1H} NMR (methylene chloride-d2, 25 °C): δ -20.6
(pseudo t, J P-P ) 12.3 Hz, 1, PEt3), -26.3 (dd, J P-P ) 18.0 Hz,
12.3 Hz, 1, PEt3), -26.7 (dd, J P-P ) 18.0 Hz, 12.3 Hz, 1, PEt3).
Syn t h esis of {fa c-[CH dC(Me)CH C(Me)dOIr CH dC-
(SiMe3)](P Et3)3}+BF 4 (11). A 1 mL solution of (trimethyl-
-
silyl)acetylene (70 mg, 0.71 mmol) in tetrahydrofuran was
added to a stirred solution of compound 2, [CHdC(Me)CHdC-
Syn th esis of {fa c-[CHdC(Me)CHC(Me)dOIr S(O)2]-
(Me)OdIr(PEt3)3]+BF4 (50 mg, 0.068 mmol), in 25 mL of
-
(P Et3)3}+BF4- (13). Compound 2, [CHdC(Me)CHdC(Me)OdIr-
(PEt3)3]+BF4- (190 mg, 0.26 mmol), was dissolved in 25 mL of
tetrahydrofuran and cooled to -72 °C. Sulfur dioxide gas was
condensed into the solution, causing an immediate color
change from purple to a light brownish red. The reaction
mixture was warmed to room temperature and left under a
nitrogen flow for 1 h. After removal of the solvent under
vacuum, the residue was extracted with methylene chloride
and filtered, and the solvent was again removed. A small
amount of acetone (1.5 mL) was used to redissolve the residue,
and 5-6 mL of diethyl ether was added. The mixture was then
cooled to -30 °C to obtain an oily yellow solid. The solution
was removed via pipet and the solid washed twice with -30
°C diethyl ether, withdrawing the ether each time. The solid
was dried under vacuum and then redissolved in a minimum
amount of acetone. Diethyl ether was added (∼5 mL) to give
an orange solution and a solid residue. After filtration the solid
tetrahydrofuran at -72 °C. When the solution was warmed
to room temperature and stirred for 1 h, the color changed
from purple to yellow. The solvent was removed under vacuum,
and the solid was washed with three successive 5 mL portions
of pentane followed by three 5 mL portions of diethyl ether.
The solid was further extracted with benzene, and the extracts
were filtered over a glass frit and dried under vacuum. Yield
of 11: 23 mg (41%).
High-resolution FAB-MS: calcd for [M]+ (C29H63191IrOP3Si+),
739.3467; found, 739.3468.
1H NMR (acetone-d6, 25 °C): δ 8.50 (pseudo q, J H-P ) 6.6
Hz, 1, H7), 7.13 (br s, 1, H1), 5.12 (s, 1, H3), 2.70 (br s, 3, ring
CH3), 2.06 (br s, 3, ring CH3), 2.3-1.7 (m, 18, PEt3 CH2’s), 1.3-
0.9 (m, 27, PEt3 CH3’s), 0.11 (s, 9, Si-CH3’s).
13C{1H} NMR (acetone-d6, 25 °C): δ 217.6 (s, C4), 163.1 (d,
J C-P ) 74.2 Hz, C7), 137.4 (d, J C-P ) 78.9 Hz, C1), 131.0 (s,
C8), 124.8 (s, C2), 71.7 (s, C3), 31.2 (s, ring CH3), 25.6 (s, ring

Metallapyrylium
Organometallics, Vol. 20, No. 2, 2001 335
Ta ble 4. X-r a y Diffr a ction Str u ctu r e Su m m a r y
6
13
14
formula
fw
C
678.2
24H53ClIrOP3
C24H53BF4IrO3P3S
793.64
C33.5H62BF4IrNO2P3
882.8
cryst syst
space group
monoclinic
P21/n
monoclinic
P21/n
monoclinic
P21/c
a, Å
b, Å
c, Å
11.244(5)
15.914(10)
16.591(7)
90.0
90.75(4)
90.0
11.2386(3)
16.7463(4)
17.4531(4)
90.0
98.124(2)
90.0
11.987(4)
11.712(2)
28.215(5)
90.0
91.05(2)
90.0
R, deg
â, deg
γ, deg
V, Å3
2969(3)
4
3251.80(14)
4
3960.4(15)
4
Z
cryst dimens, mm
cryst color and habit
calcd density, g/cm3
radiation, Å
temp, K
0.51 × 0.46 × 0.39
orange irregular
1.518
Mo KR, 0.710 73
295
0.20 × 0.12 × 0.05
orange plate
1.621
Mo KR, 0.710 73
200
0.25 × 0.45 × 0.50
yellow prism
1.480
Mo KR, 0.710 73
298
2θ range, deg
data collected
h
k
l
3.0-50.0
3.38-52.84
3.0-50.0
0 to 13
0 to 18
-14 to +14
none detected
-14 to +13
0 to 14
0 to 13
-33 to +33
none detected
-20 to +20
-21 to +21
total decay
none detected
no. of data collected
no. of unique data
no. of obsd dataa
Mo KR linear abs coeff, cm-1
abs cor applied
data to param ratio
final R indices (obsd data)a
R indices (all data)
goodness of fit
4971
4735
3728
47.63
41 077
6656
5296
43.65
7301
6944
3452
35.40
semiempirical
17.5:1
R1 ) 0.0340, wR2 ) 0.0783
R1 ) 0.0508, wR2 ) 0.0872
1.053
empirical, sadabs
19.2:1
R1 ) 0.0448, wR2 ) 0.0845
R1 ) 0.0665, wR2 ) 0.0932
1.093
semi-empiral
9.3:1
R1 ) 0.0340, wR2 ) 0.0783
R1 ) 0.0508, wR2 ) 0.0872
1.13
a
For 6 and 13, I > 2σ(I); for 14, I > 3σ(I).
was discarded, and the filtrate was dried under vacuum. The
resulting residue was redissolved in a minimum amount of
acetone. Addition of diethyl ether and a few drops of toluene,
followed by cooling to -30 °C, gave X-ray-quality crystals.
Yield of 13: 93 mg (45%).
Diethyl ether diffusion at -30 °C gave a bright yellow
crystalline product. Yield of 14: 85 mg (66%).
Anal. Calcd for C30H58BF4IrNO2P3: C, 43.06; H, 7.00.
Found: C, 43.45; H, 6.95.
High-resolution FAB-MS: calcd for [M]+ (C30H58193IrNO2P3+),
750.3310; found, 750.3313.
1H NMR (methylene chloride-d2, -40 °C): δ 7.53 (d, J H-H
) 7.8 Hz, 2, phenyl ortho), 7.45 (m, 3, phenyl meta & para),
7.25 (d, J H-P ) 4.2 Hz, 1, H1), 3.56 (d, J H-P ) 5.4 Hz, 1, H3),
2.21-2.16 (br m, 6, PEt3 CH2’s), 1.99-1.94 (br m, 6, PEt3
CH2’s), 1.91-1.86 (br m, 6, PEt3 CH2’s), 1.70 (s, 3, ring CH3),
1.44 (d, J H-P ) 6.6 Hz, 3, ring CH3), 1.16-1.10 (br m, 18, PEt3
CH3’s), 0.99 (m, 9, PEt3 CH3’s).
High-resolution FAB-MS: calcd for [M - SO2]+ (C24H53
-
193IrOP3+), 643.2939; found, 643.2941.
1H NMR (acetone-d6, 25 °C): δ 7.67 (m, 1, H1), 5.55 (s, 1,
H3), 2.89 (s, 3, ring CH3), 2.17 (s, 3, ring CH3), 2.50-2.10 (m,
18, PEt3 CH2’s), 1.30-1.00 (m, 27, PEt3 CH3’s).
13C{1H} NMR (acetone-d6, 25 °C): δ 221.0 (s, C4), 147.4 (dt,
J C-P ) 71.2 Hz, 7.5 Hz, C1), 133.9 (s, C2), 105.4 (s, C3), 29.2
(d, J C-P ) 3.4 Hz, ring CH3), 22.3 (d, J C-P ) 6.6 Hz, ring CH3),
20.3 (d, J C-P ) 38.8 Hz, PEt3 CH2’s), 18.8 (d, J C-P ) 25.6 Hz,
PEt3 CH2’s), 18.1 (d, J C-P ) 30.0 Hz, PEt3 CH2’s), 9.5 (d, J C-P
) 6.6 Hz, PEt3 CH3’s), 8.6 (d, J C-P ) 5.6 Hz, PEt3 CH3’s).
31P{1H} NMR (acetone-d6, 25 °C): δ -21.3 (dd, J P-P ) 14.0
Hz, 10.0 Hz, 1, PEt3), -21.7 (dd, J P-P ) 15.0 Hz, 10.0 Hz, 1,
PEt3), -24.9 (pseudo t, J P-P ) 14.5 Hz, 1, PEt3).
13C{1H} NMR (methylene chloride-d2, -40 °C): δ 172.3 (d,
J C-P ) 10.5 Hz, C4), 156.8 (s, C1), 139.8 (s, phenyl ipso), 129.7
(s, phenyl para), 129.5 (s, phenyl meta), 120.4 (s, phenyl ortho),
102.0 (pseudo t, J C-P ) 4.1 Hz, C3), 42.7 (ddd, J C-P ) 78.7
Hz, 6.3 Hz, 4.0 Hz, C2), 27.9 (s, ring CH3), 19.0 (s, ring CH3),
18.6 (d, J C-P ) 23.7 Hz, PEt3 CH2’s), 17.8 (d, J C-P ) 24.0 Hz,
PEt3 CH2’s), 15.3 (d, J C-P ) 24.8 Hz, PEt3 CH2’s), 10.1 (d, J C-P
) 5.9 Hz, PEt3 CH3’s), 9.5 (d, J C-P ) 5.4 Hz, PEt3 CH3’s), 8.2
(d, J C-P ) 6.4 Hz, PEt3 CH3’s).
Syn th esis of {fa c-[C(Me)CHdC(Me)OIr ON(P h )dCH]-
(P Et3)3}+BF4- (14). Compound 2, [CHdC(Me)CHdC(Me)OdIr-
(PEt3)3]+BF4- (110 mg, 0.15 mmol), was dissolved in 20 mL of
tetrahydrofuran to form a purple solution and cooled to -30
°C. Nitrosobenzene (18 mg, 0.17 mmol) was dissolved in 10
mL of tetrahydrofuran, cooled to -30 °C, and added to the
stirred purple solution, causing it to turn orange-yellow. The
solution was stirred at 25 °C for 30 min before the tetra-
hydrofuran was removed in vacuo. The resultant film was
repeatedly extracted with toluene, and each successive extrac-
tion was passed through a glass frit. The toluene volume was
reduced by ∼75% and stored at -30 °C.
31P{1H} NMR (methylene chloride-d2, -40 °C): δ -22.9
(pseudo t, J P-P ) 10.5 Hz, 1, PEt3), -34.3 (dd, J P-P ) 15.0 Hz,
10.5 Hz, 1, PEt3), -34.4 (dd, J P-P ) 15.0 Hz, 10.5 Hz, 1, PEt3).
X-r a y Diffr a ction Stu d ies of m er -CHdC(Me)CHdC-
(Me)OIr (Cl)(P Et3)3 (6), {fa c-[CHdC(Me)CHC(Me)dOIr S-
(O)2](P Et3)3}+BF4- (13), an d {fa c-[C(Me)CHdC(Me)OIr ON-
(P h )dCH](P Et3)3}+BF 4 (14). Single crystals of compounds
-
Multiple crops of microfine yellow crystals were recovered
on a glass frit with subsequent in vacuo solvent reductions.
The recovered microfine crystals were washed with cold
toluene and pentane and dissolved in a minimum of acetone.
6, 13, and 14 were either sealed in a glass capillary or mounted
on a glass fiber under a nitrogen atomosphere. X-ray data for
6 and 14 were collected on a Siemens R3m/V diffractometer
at room temperature, while data for 13 was obtained using a

336 Organometallics, Vol. 20, No. 2, 2001
Bleeke et al.
Bruker SMART charge coupled device (CCD) detector system
at 200 K. In each case, graphite-monochromated Mo KR
radiation was supplied by a sealed-tube X-ray source.
Structure solution and refinement were carried out using
the SHELXTL-PLUS software package (PC version).20 The
iridium atom positions were determined by direct methods.
The 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, while hydrogen atoms were placed at idealized
positions and assumed the riding model.
In compound 14, the tetrafluoroborate anion was disordered
and was, therefore, refined using DFIX constraints. Its F-B-F
angles were fixed at 109.5°, and a common B-F distance was
refined. The toluene molecule of crystallization (1/2 equiv) was
refined isotropically. Its disordered methyl group was assigned
an occupancy factor of 0.5.
Ack n ow led gm en t. We thank Nigam P. Rath (Uni-
versity of MissourisSt. Louis) for determining the X-ray
crystal structure of compound 13. Support from the
National Science Foundation and the donors of the
Petroleum Research Fund, administered by the Ameri-
can Chemical Society, is gratefully acknowledged. We
also thank J ohnson Matthey Alfa/Aesar for a loan of
IrCl3‚3H2O. Washington University’s High Resolution
NMR Service Facility was funded in part by NIH
Support Instrument Grants (RR-02004, RR-05018, and
RR-07155). The Washington University Mass Spectrom-
eter Resource is supported by the NIH Center for
Research Resources (Grant P41RR0954).
Su p p or tin g In for m a tion Ava ila ble: Text giving struc-
ture determination summaries and listings of final atomic
coordinates, thermal parameters, bond lengths, and bond
angles for compounds 6, 13, and 14. This material is available
free of charge via the Internet at http://pubs.acs.org.
Crystal data and details of both collection and structure
analysis are listed in Table 4.
(20) Sheldrick, G. M. Bruker Analytical X-ray Division, Madison,
WI, 1997.
OM0008068