Electronic and steric effects in the insertion of alkynes into an iridium(III) hydride

Article abstract of DOI:10.1021/om049271z

Insertion of a variety of alkynes into the Ir-H bond of trans-[IrH(PPh ₃)₂(C(Ph.)=CHC-(O)Me)(acetone)]⁺ (1) follows three different routes depending on the alkyne structures. For relatively electron-rich alkynes (PhC≡CH, PhCH₂C≡CH, and p-OMeC ₆H₄C≡CH), double insertion occurs stepwise, each alkyne undergoing rearrangement to a vinylidene intermediate independently to afford an iridium(III) η²-butadienyl. In the first alkyne insertion, deuterium labeling and crossover experiments confirm that the alkyne to vinylidene rearrangement is intraligand. Both a vinyl and a vinylidene intermediate were trapped and isolated during this first insertion. In the second alkyne insertion, a C - H agostic intermediate was isolated. Electron-poor alkynes (p-CF₃C₆H₄C≡CH and p-NO₂C₆H₄C≡CH) also undergo double insertion into 1, but deuterium labeling experiments using p-CF ₃C₆H₄C≡CD indicate reversible C(sp)-H oxidative addition. Insertion of highly polarized alkynes (R ₁C≡CC(O)R₂] to 1 occurs only once and involves no vinylidene intermediates even when R₁ = H. The regio- and stereochemistry in this case are mainly controlled by the steric effects of R₁. In this series, rare cis-(PPh₃)₂ intermediates were isolated for HC≡CC(O)R (R = Me or OMe). X-ray crystal structures of representative products are reported.

Full text of DOI:10.1021/om049271z

62
Organometallics 2005, 24, 62-76
Electronic and Steric Effects in the Insertion of Alkynes
into an Iridium(III) Hydride
Xingwei Li, Tiffany Vogel, Christopher D. Incarvito, and Robert H. Crabtree*
Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520
Received September 18, 2004
Insertion of a variety of alkynes into the Ir-H bond of trans-[IrH(PPh3)2(C(Ph)dCHC-
(O)Me)(acetone)]+ (1) follows three different routes depending on the alkyne structures. For
relatively electron-rich alkynes (PhCtCH, PhCH2CtCH, and p-OMeC6H4CtCH), double
insertion occurs stepwise, each alkyne undergoing rearrangement to a vinylidene intermedi-
ate independently to afford an iridium(III) η2-butadienyl. In the first alkyne insertion,
deuterium labeling and crossover experiments confirm that the alkyne to vinylidene
rearrangement is intraligand. Both a vinyl and a vinylidene intermediate were trapped and
isolated during this first insertion. In the second alkyne insertion, a C-H agostic intermediate
was isolated. Electron-poor alkynes (p-CF3C6H4CtCH and p-NO2C6H4CtCH) also undergo
double insertion into 1, but deuterium labeling experiments using p-CF3C6H4CtCD indicate
reversible C(sp)-H oxidative addition. Insertion of highly polarized alkynes [R1CtCC(O)-
R2] to 1 occurs only once and involves no vinylidene intermediates even when R1 ) H. The
regio- and stereochemistry in this case are mainly controlled by the steric effects of R1. In
this series, rare cis-(PPh3)2 intermediates were isolated for HCtCC(O)R (R ) Me or OMe).
X-ray crystal structures of representative products are reported.
1. Introduction
by a concerted intraligand 1,2-hydrogen shift, which was
proposed before based on theoretical studies,1a,4,7 fol-
lowed by migratory insertion of the vinylidene into the
M-H bond to give a vinyl.8 Path (c) involves a C(sp)-H
oxidative addition to the metal to give a metal dihydride
or a dihydrogen intermediate,9 followed by a unimo-
lecular 1,3-hydrogen shift or a bimolecular proton shift9c
from the metal to the ligand to form a vinylidene, which
Alkyne insertion into metal hydrides (M-H) is a
fundamental step in many homogeneous catalytic reac-
tions such as alkyne hydrogenation, hydrosilation, and
oligomerization.1 Insertion can be followed by stoichio-
metric or catalytic C-C bond forming steps for organic
synthetic applications such as the synthesis of a variety
of polyenes.2-4 Despite its apparent simplicity, at least
three possible mechanisms have previously been pro-
posed for the insertion of alkynes into M-H to give
vinyls (Scheme 1). In path (a),5 the direct insertion of
an alkyne into the M-H bond via a four-centered
transition state affords the syn-insertion product; this
may then isomerize to the apparent anti-insertion
product via proposed η2-vinyl intermediates.6 In path
(b), the RCtCH first rearranges to a vinylidene ligand
(5) For regio- and stereochemistry of alkyne insertion, see: (a)
Navarro, J.; Sola, E.; Martin, M.; Dobrinovitch, I. T.; Lahoz, F. J.; Oro,
L. A. Organometallics 2004, 23, 1908. (b) Frohnapfel, D. S.; White, P.
S.; Templeton, J. L. Organometallics 2000, 19, 1497. (c) Selmeczy, A.
D.; Jones, W. D. Inorg. Chim. Acta 2000, 300-302, 138. (d) Herberich,
G. E.; Bariage, W. Organometallics 1987, 6, 1924. (e) Bassetti, M.;
Casellato, P.; Gamasa, M. P.; Gimeno, J.; Gonzalez-Bernardo, C.;
Martin-vaca, B. Organometallics 1997, 15, 5470. (f) Gao, Y.; Jennings,
M. C.; Puddephatt, R. L. Dalton Trans. 2003, 261. (g) Bassetti, M.;
Marini, S.; Diaz, J.; Gamasa, M. P.; Gimeno, J.; Rodriguez-Alvarez,
Y.; Garcia-Granda, S. Organometallics 2002, 21, 4815.
(6) (a) Chung, L. W.; Wu, Y.-D.; Trost, B. M.; Ball, Z. T. J. Am. Chem.
Soc. 2003, 125, 11578. (b) Crabtree, R. H. New J. Chem. 2003, 27,
771. (c) Tanke, R. S.; Crabtree, R. H. J. Am. Chem. Soc. 1990, 112,
7984. (d) Ojima, I.; Clos, N.; Donovan, R. J.; Ingallina, P. Organome-
tallics 1990, 9, 3127. (e) Frohnapfel, D. S.; Templeton, J. L. Coord.
Chem. Rev. 2000, 206, 199.
(7) (a) Silvestre, J.; Hoffmann, R. Helv. Chim. Acta 1985, 68, 1461.
(b) Wakatsuki, Y.; Koga, N.; Yamazaki, H.; Morokuma, K. J. Am.
Chem. Soc. 1994, 116, 8105. (c) Cadierno, V.; Gamasa, M. P.; Gimeno,
J.; Pe´rez-Carren˜o, E.; Garc´ıa-Granda, S. Organometallics 1999, 18,
2821. (d) Akita, M.; Ishii, N.; Takabuchi, A.; Tanaka, M.; Moro-oka,
Y. Organometallics 1994, 13, 258. (e) De Angelis, F.; Sgamellotti, A.;
Re, N. Organometallics 2002, 21, 2715.
(8) (a) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1995,
14, 3596. (b) Buil, M. L.; Esteruelas, M. A. Organometallics 1999, 18,
1798.
(9) (a) Li, X.; Appelhans, L. N.; Faller, J. W.; Crabtree, R. H.
Organometallics 2004, 23, 3378. (b) De los R´ıos, I.; Tenorio, M. J.;
Puerta, M. C.; Valerga, P. J. Am. Chem. Soc. 1997, 119, 6529. (c)
Wakatsuki, Y.; Koga, N.; Werner, H.; Morokuma, K. J. Am. Chem. Soc.
1997, 119, 360. (d) Windmu¨ller, B.; Wolf, J.; Werner, H. J. Organomet.
Chem. 1995, 502, 147. (e) Garcia Alonso, F. J.; Hoehn, A.; Wolf, J.;
Otto, H.; Werner, H. Angew. Chem. 1985, 97, 401. (f) Torkelson, J. R.;
McDonald, R.; Cowie, M. Organometallics 1999, 18, 4134.
(1) (a) Oliva´n, M.; Clot, E.; Eisenstein, O.; Caulton, K. G. Organo-
metallics 1998, 17, 3091 and references cited there. (b) Otsuka, S.;
Nakamura, A. Adv. Organomet. Chem. 1974, 14, 245. (c) Dash, A. K.;
Wang, J.-Q.; Eisen, M. S. Organometallics 1999, 18, 4724. (d) Bian-
chini, C.; Innocenti, P.; Meli, A.; Peruzzini, M.; Zanobini, F.; Zanello,
P. Organometallics 1990, 9, 2514.
(2) (a) Chin, C. S.; Kim, M.; Lee, H.; Noh, S.; Ok, K. M. Organome-
tallics 2002, 21, 4785. (b) Esteruelas, M. A.; Gracia-Yebra, C.; Olivan,
M.; Onate, E.; Tajada, M. A. Organometallics 2000, 19, 5098. (c) Deng,
M.; Leong, W. K. Organometallics 2002, 21, 1221. (d) Sola, E.; Torres,
O.; Plou, P.; Oro, L. A. Organometallics 2003, 22, 5406. (e) Slugovc,
C.; Mereiter, K.; Zobetz, E.; Schmid, R.; Kirchner, K. Organometallics
1996, 15, 5275. (f) Johnson, J. R.; Cuny, G. D.; Buchwald, S. L. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1760. (g) Esteruelas, M. A.; Herrero,
J.; Lopez, A. M.; Olivan, M. Organometallics 2001, 20, 3202.
(3) (a) Kishimoto, Y.; Eckerle, P.; Miyatake, T.; Kainosho, M.; Ono,
A.; Ikariya, T.; Noyori, R. J. Am. Chem. Soc. 1999, 121, 12035. (b)
Burrows, A. D.; Green, M.; Jeffery, J. C.; Lynam, J. M.; Mahon, M. F.
Angew. Chem., Int. Ed. 1999, 38, 3043. (c) Chin, C. S.; Lee, H.; Park,
H.; Kim, M. Organometallics 2002, 21, 3889. (d) Selnau, H. E.; Merola,
J. S. J. Am. Chem. Soc. 1991, 113, 4008.
(4) Li, X.; Incarvito, C. D.; Crabtree, R. H. J. Am. Chem. Soc. 2003,
125, 3698.
10.1021/om049271z CCC: $30.25 © 2005 American Chemical Society
Publication on Web 12/08/2004

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 63
Scheme 1
then might undergo migratory insertion to yield a vinyl
as in path (b). In contrast to path (b), however, the
hydrides in path (c) are not spectators in the vinylidene
formation step. In both path (b) and (c), the well-known
alkyne to vinylidene rearrangement10 is involved. Fully
authenticated examples of alkyne insertion through
paths (b) and (c) are rare because they have been mostly
proposed theoretically rather than shown experimen-
tally. This multiplicity of pathways makes the outcome
in any specific case hard to determine or predict.
Insertion of an alkyne into a metal hydride usually
requires a cis vacant site to accommodate the alkyne.
Since the insertion process would regenerate this site,
double or even multiple alkyne insertion that forms
C-C bonds should be possible in principle. These are
not very common, however, no doubt due to the fact that
the second alkyne insertion into the first-formed vinyl
is expected to be slower than the first insertion into
hydride. The second alkyne insertion is normally much
less favorable probably as a result of the following
effects: (1) the steric hindrance is greater; (2) coordina-
tion of some pendant functional groups in the resultant
vinyl may occur,11-14 (3) there may be coupling between
the vinyl ligand and other ligands,9a,15 and occasionally
(4) stable coordinatively saturated η2-vinyl complexes
can be formed.16 Despite their rarity, double or even
multiple insertion of alkynes into metal hydrides has
occasionally been reported.2b,3,4
We have briefly reported the double insertion of
unactivated alkynes into the iridium hydride 1 to afford
a rare Ir(III) η2-butadienyl.4 As reported in full here,
deuterium labeling and crossover experiments indicate
that each alkyne undergoes independent rearrangement
to give a vinylidene (eq 1). The first vinylidene inserts
into the hydride to form a vinyl intermediate, into which
the second vinylide inserts to give a proposed interme-
diate, observed in one case, stabilized by a C-H agostic
bond. This agostic intermediate can then rearrange to
yield the observed Ir(III) η2-butadienyl product. In this
paper we look in full at the intermediates involved in
the double insertion and find that electronic and steric
effects of the alkynes can change the pathway of the
insertion into the same Ir(III) hydride.
(10) Reviews: (a) Bruneau, C.; Dixneuf, P. H. Acc. Chem. Res. 1999,
32, 311. (b) Bruce, M. I. Chem. Rev. 1991, 91, 197.
(11) van der Zeijden, A. A. H.; Bosch, H. W.; Berke, H. Organome-
tallics 1992, 11, 563.
(12) Esteruelas, M. A.; Garcı´a, M. P.; Mart´ın, M.; Nu¨rnberg, O.; Oro,
L. A.; Werner, H. J. Organomet. Chem. 1994, 466, 249.
(13) (a) Atencio, R.; Bohanna, C.; Esteruelas, M. A. Lahoz, F. J.;
Oro, L. A. J. Chem. Soc., Dalton Trans. 1995, 2171. (b) Echavarren,
A. M.; Lopez, J.; Santos, A.; Romero, A.; Hermoso, J. A.; Vegas, A.
Organometallics 1991, 10, 2371. (c) Werner, H.; Meyer, U.; Peters, K.;
von Schnering H. G. Chem. Ber. 1989, 122, 2097.
(14) (a) Albertin, G.; Antoniutti, S.; Bordignon, E. J. Chem. Soc.,
Dalton Trans. 1995, 719. (b) Esteruelas, M. A.; Lahoz, F. J.; Oro, L.
A.; Schlunken, C.; Valero, C.; Werner, H. Organometallics 1992, 11,
2034.
2. Results and Discussion
2.1. Alkyne Double Insertion Involving Intrali-
gand Alkyne to Vinylidene Rearrangement (path
(b), Scheme 1). Addition of 2 equiv of the relatively
electron-rich terminal alkynes (RCtCH, R ) Ph, PhCH2,
and p-C6H4OMe) to 1 in acetone or CH2Cl2 caused an
immediate color change from yellow to orange; yellow
precipitates were obtained with Et2O. The products
were characterized as η2-butadienyls 2a-c (X ) H) on
(15) Wen, T. B.; Zhou, Z. Y.; Jia, G. Organometallics 2003, 22, 4947.
(16) (a) Stone, K. C.; Jamison, G. M.; White, P. S.; Templeton, J. L.
Organometallics 2003, 22, 3083. (b) Frohnapfel, D. S.; White, P. S.;
Templeton, J. L. Organometallics 2000, 19. 14797.
1
the basis of H, 31P, and 13C NMR spectroscopy, X-ray

64 Organometallics, Vol. 24, No. 1, 2005
Li et al.
Figure 1.
Scheme 2
crystallography (for 2a, X ) H), and elemental analysis
1
(eqs 1, 2). Both H and 13C NMR spectroscopy indicate
that two alkyne units have been incorporated. In
particular, the 13C{1H} NMR spectrum shows a high-
field singlet signal for C(sp2) [δ 100.3 (s) for 2a (X )
H); 99.4 (s) for 2b (X ) H), 96.5 (s) for 2c (X ) H)],
assigned to C(13) on the basis of comparison with
previous data.17 The 1H NMR spectrum (acetone-d6)
shows two mutually trans-coupled HCdCH protons
[H(12) and H(13); crystallographic numbering (see
Figure 3) is used throughout, δ 6.42 (d, 3JHH ) 16.2 Hz)
and D and D-15 in A and C. These results show that
PhCH2 and H are always attached to the same carbon
in the four products, as are Ph and D, and there is no
crossover between these two alkyne units.
3
and 5.59 (d, JHH ) 16.2 Hz) for 2a (X ) H); 5.29 (dt,
3JHH ) 15.2 Hz) and 4.92 (d, 3JHH ) 15.2 Hz) for 2b (X
) H); 6.38 (d, 3JHH ) 16.0) and 5.32 (d. 3JHH ) 16.0 Hz)
for 2c (X ) H)]. Assignment of H(12) and H(13) by C-H
correlation spectroscopy showed that H(12) always
resonates to higher field of H(13). This assignment is
also confirmed by the additional coupling found between
C(12) and its adjacent CH2 group in 2b (X ) H). The
31P{1H} NMR spectra of 2a-c show a singlet for each
complex. The X-ray crystal structure of 2a (X ) H)
confirmed the bihapticity of the η2-butadienyl group.4
These experiments suggest that eq 1 goes by initial
alkyne insertion via path (b) in Scheme 1. No simple
vinyl intermediate was obtained from 1 and 1 equiv of
PhCtCH in acetone, which gave only the double inser-
tion product 2a (X ) H) (50% yield) and starting
material 1. The insertion of the second alkyne to lead
to 2a is therefore faster than that of the first. By moving
to the acetonitrile adduct of 1, however, the first vinyl
intermediate can be successfully trapped (Scheme 2).
Acetonitrile, more ligating than acetone, may inhibit the
binding of the second alkyne. In this reaction, a mixture
of the starting material, the simple vinyl complex 3, and
the double-insertion product 2a (X ) H) was detected
1
in a ratio of 0.5:10:1 by H and 31P NMR spectroscopy
(CD2Cl2, 25 °C, 8 h). The vinyl 3 was readily isolated
owing to its greater solubility in diethyl ether and was
1
fully characterized. The H NMR spectrum of 3 (CD2-
Cl2) shows a characteristic low-field resonance of a
triplet (3JPH ) 3.0 Hz) of doublets (3JHH ) 16.4 Hz) at
δ 8.22, assigned to the R-H of the styrenyl group, while
Deuterium labeling experiments show that R and D
always stay attached to both C(12) and C(15), which
used to be the C-2 positions of the alkyne unit (eqs 1,
2). A crossover experiment was performed using hydride
1 and a mixture of PhCH2CtCH and PhCtCD. All four
η2-butadienyl products (A-D, Figure 1) were obtained
with a ratio of A:B:C:D ) 1.00:1.56:0.76:0.73, based on
31P and 1H NMR analysis, where complex B is 2a (X )
D) and complex C is 2b (X ) H), whose 1H NMR spectra
are known. By comparison with the 1H NMR spectra of
the four products obtained from 1 and a mixture of
PhCtCH and PhCH2CtCH, the H(12) and H(15) sig-
nals associated with PhCH2 or Ph in A-D can be
separately distinguished and assigned. In particular, 1H
NMR signals for H(12) (δ 6.18) of A, H(12) (δ 6.42) and
H(15) (δ 5.72) of B, and H(15) of D (δ 5.67) essentially
disappear (<4% residual signal). Furthermore, the
absence of any resonance signal between δ 3.0 and 6.0
in the 2H NMR (76.77 MHz, 298 K, acetone-d6) spectrum
of the mixture confirmed the absence of any D-12 in C
the â-H in this group resonates as a doublet (3JHH
)
16.4 Hz) at δ 5.85. The coupling constant between these
two protons clearly indicates a trans orientation on the
CdC double bond. The 13C{1H} NMR spectrum of 3
shows a very low field triplet at δ 204.5 (2JPC ) 7.4 Hz),
assigned to the vinyl carbon of the iridacycle. This
carbenoid chemical shift suggests that this iridacycle
is essentially an iridafuran due to the presence of two
resonance structures (Figure 2). Another triplet at δ
118.4 (2JPC ) 9.0 Hz) is assigned to the R-carbon of the
styrenyl group. The 13C NMR spectrum confirmed the
presence of a CH3CN ligand (δ 3.2, CH3; δ 121.8 CN).
Addition of phenyl acetylene to a dichloromethane
solution of 3 slowly but cleanly leads to the double
insertion product 2a (X ) H), indicating that the vinyl
complex 3 is indeed an intermediate in alkyne double
insertion.
(17) (a) Karl, J.; Erker, G.; Frohlich, R. J. Am. Chem. Soc. 1997,
119, 11165. (b) Jia, G.; Lee, H. M.; Xia, H. P. Williams, I. D.
Organometallics 1996, 15, 5453.
Figure 2.

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 65
Scheme 3
Scheme 4
Although deuterium labeling experiments with RCt
CD (R ) Ph, PhCH2, and o-C6H4OMe) indicate we have
an alkyne to vinylidene rearrangement, all attempts
failed to observe the proposed vinylidene intermediate
by 1H NMR spectroscopy (acetone-d6, -30 °C). The
vinylidene ligand may be destabilized by being trans to
the high trans-effect ligand (the iridafuran carbon).
Independent evidence for this vinylidene intermediate
was obtained from trapping the vinylidene by nucleo-
philic attack of an -OH group. In this reaction of a
functionalized alkyne 2-ethynylbenzyl alcohol and hy-
dride 1, the iridium carbene hydride 4 was obtained (eq
by deuterium labeling, involves a second alkyne to
vinylidene rearrangement. Intermediates for this second
insertion were studied by reaction of PhCtCH with 5,
an analogue of 1 (Scheme 3). This reaction rapidly (15
min, RT) afforded 6, a C-H agostic complex, which was
readily isolated. Reflux of a dichloromethane solution
of 6 for 10 h afforded the η2-butadienyl 7 in high yield.
Both 6 and 7 were fully characterized by NMR spec-
troscopy with confirmation of the C-H agostic product
by X-ray crystallography.4 In the 1H NMR spectrum
(CD2Cl2) of 6 at room temperature, a characteristic
broad singlet at δ 5.21 (2H) was assigned to the C-H
agostic protons broadened by fluxionality caused by the
rotation of the C-C(phenyl) bond. Upon cooling, this
signal decoalesced to broad singlets at δ 3.80 and 6.54
at -75 °C. In the 13C{1H} NMR spectrum of 6 at -80
°C, decoalescence of signals for the agostic Ph ring at δ
107.2 (C-2′, agostic), 126.6 (C-6′), 136.3 (C3′), and 130.3
(C5′) was also confirmed by C-H correlation spectros-
copy. C(sp3)-H agostic complexes are well-known, but
C(sp2)-H agostic ones are somewhat rarer.2a,19
1
3), which was fully characterized by H, 13C, and 31P
NMR spectroscopy. In particular, the 13C{1H} NMR
spectrum (CD2Cl2) shows the Fischer carbene resonates
as a triplet at δ 292.5 (2JPC ) 7.9 Hz) and the two ring
1
CH2 groups at δ 79.4 (s) and 59.6 (s). In the H NMR
spectrum (CD2Cl2), the hydride resonates as a triplet
at δ -20.96 (2JPH ) 14 Hz) and the two CH2 groups
resonate at δ 4.53 (s, 2H) and 3.51 (s, 2H). Our proposed
pathway (eq 3) goes by intramolecular trapping of the
vinylidene by the pendant hydroxyl group to generate
a stable, cyclic carbene.2a,18 The fact that 4 is the only
product shows that this trapping is faster than the
alternative vinylidene insertion into Ir-H to yield a
vinyl.8
η2-Butadienyl 7 is a direct analogue of 2a (X ) H),
and like 2a (X ) H), the 13C{1H} NMR spectrum of 7
shows a characteristic high-field signal for C(sp2) at δ
100.6 (s) that is assigned to C(13). The trans arrange-
ment about the C(12)dC(13) bond in the butadienyl
group was clearly indicated by the mutal coupling of
1
the two HC(12)dC(13)H protons in H NMR spectrum
(CD2Cl2) at δ 6.42 (3JHH ) 16.0 Hz, 1H) and 5.38 (3JHH
) 16.0 Hz, 1H).
On the basis of its very similar NMR spectral char-
acteristics, a similar C-H agostic intermediate was also
found in the reaction between 1 and 2 equiv of o-CF3-
(C6H4)CtCH in CD2Cl2 (Scheme 4). The intermediate,
formed in 88% yield after 15 min at 0 °C, was charac-
terized by H, 31P, and 19F NMR spectroscopy, notably
1
from its broad C-H aryl resonance at δ 3.67 (1H).
Warming to room temperature led to a mixture of
agostic 8 (minor) and η2-butadienyl 9 (major) in equi-
librium, which was confirmed by the fact that the same
ratio of 8 to 9 was obtained from isolated 9 or with
The mechanism of the formation of the final η2-
butadienyl complex from the simple vinyl, also studied
(19) (a) Vigalok, A.; Milstein, D. Acc. Chem. Res. 2001, 34, 798. (b)
van der Boom, M. E.; Iron, M. A.; Atasoylu, O.; Shimon, L. J. W.;
Rozenberg, H.; Ben-David, Y.; Konstantinovski, L.; Martin, J. M. L.;
Milstein, D. Inorg. Chim. Acta 2004, 357, 1854. (c) Albeniz, A. C.;
Schulte, G.; Crabtree, R. H. Organometallics 1992, 11, 242.
(18) (a) O’Connor, J. M.; Pu, L.; Rheingold, A. L. J. Am. Chem. Soc.
1987, 109, 7578. (b) O’Connor, J. M.; Hiibner, K.; Closson, A.; Gantzel,
P. Organometallics 2001, 20, 1482.

66 Organometallics, Vol. 24, No. 1, 2005
Li et al.
Scheme 5
Scheme 6
temperature perturbation followed by relaxation. This
suggests that these two weak interactions are of com-
parable strength. Because of its lower solubility, 9 could
be isolated in solid form. Complex 9 could be character-
ized spectroscopically only from the mixture. In par-
ticular the 1H NMR spectrum of 9 shows two trans CH
vinyl protons (3JHH ) 15.8 Hz) at δ 6.57 and 5.65. The
19F{1H} NMR spectrum of 9 shows two singlets with
equal intensity at δ -59.55 and -59.58. No acceptable
13C{1H} NMR spectrum of 9 could be obtained due to
its poor solubility and its equilibration with 8. The
equilibrium constant (Keq) was measured by 31P NMR
spectroscopy in CD2Cl2: 22.7 at 21 °C, 17.8 at 28 °C,
and 13.7 at 35 °C. At higher temperatures the sample
decomposed, and at lower temperatures the longer
reaction time made the data less reliable.
The agostic complex 8 is therefore a kinetic interme-
diate leading to the more thermodynamically stable η2-
butadienyl 9. We propose that it is formed by the
migratory insertion of the vinyl group to the least
hindered side of the vinylidene ligand, anti to the â-Ph
group (Scheme 5), possibly because there is free rotation
around the iridium-vinylidene bond.10 This causes the
Ph group to approach the iridium in a cis geometry for
agostic interaction. Rearrangement of this agostic com-
plex to the more stable final η2-butadienyl complex most
likely goes through an η2-vinyl intermediate (Scheme 1
(a)).6
required in this rearrangement is not rate-determining.
The results are consistent with the rate-determing
slippage of an η2(C-C)-alkyne intermediate to an η2-
(C-H)-agostic species (path (b), Scheme 1), as suggested
in previous theoretical studies.7
2.2. Double Insertion of Relatively Electron-
Poor Alkynes. Surprisingly, moving to electron-
withdrawing groups as alkyne substituents led to a
change of mechanism. Two equivalents of such alkynes
ArCtCH (Ar ) p-C6H4CF3, p-C6H4NO2) were allowed
to react with 1 in acetone (Scheme 6). As we expected,
the reaction afforded η2-butadienyl 10a,b from alkyne
double insertion, although at a lower rate than for PhCt
CH (Scheme 6). The nature of the η2-butadienyl prod-
1
ucts was readily confirmed by H, 13C, and 31P NMR
spectroscopy and elemental analyses. In particular, the
13C{1H} NMR spectra of 10a and 10b show character-
istic peaks at δ 111.4 and 106.7, respectively, assigned
to C(12). In addition, the 19F{1H} NMR spectrum of 10b
gives two singlets (δ -63.08 and -63.64) with equal
intensity for the two CF3 groups.
The mechanistic change was evident from isotope
labeling experiments using ArCtCD (Ar ) p-C6H4CF3,
p-C6H4NO2), which indicated that deuterium fully
scrambled into the three methine positions [C(12), C(13),
and C(15)] of the butadienyl ligand. Similarly, addition
of 2 equiv of PhCtCH to a CH2Cl2 solution of a related
iridium hydride 11 also afforded the η2-butadienyl
double insertion product 12 with the same scrambling
pattern.
The kinetic isotope effect for the double insertion of
PhCH2CtCH was determined from a competition be-
tween PhCH2CtCD and PhCH2CtCH for reaction with
1
Complex 12 was fully characterized by H, 31P, and
1
1 in CH2Cl2. H NMR data show a kH/kD of 1.5 for the
13C NMR spectroscopy, elemental analysis, and X-ray
crystallography (Figure 3, Tables 1 and 2). The X-ray
crystal structure of 12 shows that the geometry about
first alkyne to vinylidene rearrangement, but 1.0 for the
second. This suggests that the C-H bond breaking

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 67
Table 2. Selected Bond Lengths and Angles for
Complex 12
Bond Lengths (Å)
Ir(1)-P(1)
2.361(2)
2.365(2)
2.175(5)
2.009(6)
2.504(6)
2.029(6)
1.336(8)
1.474(8)
1.326(8)
Ir(1)-P(2)
Ir(1)-N(1)
Ir(1)-C(1)
Ir(1)-C(13)
Ir(1)-C(14)
C(12)-C(13)
C(13)-C(14)
C(14)-C(15)
Bond Angles (deg)
P(1)-Ir(1)-P(2)
175.53(5)
36.1(2)
C(13)-Ir(1)-C(14)
C(1)-Ir(1)-N(1)
C(1)-Ir(1)-C(14)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
78.3(2)
109.0(2)
122.7(5)
126.8(5)
-5 °C. After 30 min, when the alkyne and the iridium
hydride were still the only detectable species, deuterium
scrambling between them was already observed. The
deuteration of the free alkyne went from 98% to 88% in
the reaction mixture, while that of the iridium hydride
went from the natural abundance (∼ 0%) to 24%. This
scrambling was also confirmed by 2H NMR spectroscopy
(46.0 MHz, CH2Cl2, -5 °C), where the Ir-D resonance
at δ -20.8 was clearly observed. These results indicate
a reversible oxidative addition of the alkyne to the
iridium hydride.20 This would afford an IrIII(HD) or an
IrV(H)(D) intermediate, which can undergo either C-H
or C-D reductive elimination to lead to deuterium
scrambling in the starting materials. A detailed mech-
anism of this double insertion is hard to study experi-
mentally, since reversible C-H oxidative addition is the
source of the deuterium scrambling and any later step
will not change this feature. However, the direct inser-
tion mechanism (path (a), Scheme 1) is unlikely since
no reaction was observed between complex 1 and excess
MeCtCPh and PhCtCPh, where the Me group in
MeCtCPh or the Ph group in PhCtCPh would be
expected to behave as spectators during a direct inser-
Figure 3. ORTEP diagram of the cation of 12 shown with
50% probability ellipsoids.
the iridium center is octahedral, with five normal tightly
bound ligands and a sixth at a much longer distance,
corresponding to a weak secondary interaction. This
weak Ir- - -C(13) bond (2.504(6) Å) is ca. 0.5 Å longer
than the normal Ir-C(14) bond (2.029(6) Å), while
Ir- - -C(12) (3.11 Å) is outside the first coordination
sphere. The C(12)-C(13) double bond (1.336(8) Å) is
slightly elongated and is comparable to the C-C bonds
in the aromatic rings (1.337-1.415 Å). The C(12)-C(13)
double bond is highly twisted (86.7°) and deconjugated
from the C(14)-C(15) bond. All these crystal data are
closely comparable to those reported for 2a (X ) H).4
The scrambling of deuterium to the three possible
positions in the butadienyl group suggests that the
mechanism of the double insertion of these alkynes very
likely involves a C-H oxidative addition step. The
mechanism of the double insertion of p-CF3(C6H4)Ct
CD into 1 was investigated by 1H NMR spectroscopy at
Table 1. Crystallographic Data for 12, 15a and 18a
12‚acetone
15a
18a‚Et2O
empirical formula
C
66H57F6IrNOP2Sb
C50H44F6IrO3P2Sb
C60H58BF4IrO3P2
1168.01
molecular weight (g mol-1
)
1370.02
1182.74
Mo KR (monochr), 0.71073 Å
-100
radiation, λ (Å)
T (°C)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
23
-100
triclinic
monoclinic
P21/n (No. 14)
11.857(2)
35.049(7)
14.543(3)
90
monoclinic
C2 (No. 5)
25.032(5)
14.670(3)
13.062(3)
90
107.35(3)
90
4578.5(16)
4
1.716
36.30
0.15 × 0.15 × 0.10
9690, 9690
0.000
9690
597, 1
0.0359; 0.0684
1.043
-1.782, 0.601
P1h (No. 2)
13.6505(3)
15.9723(4)
21.6001(6)
76.77(3)
78.30(3)
83.67(3)
2481.1(9)
2
1.563
28.18
0.20 × 0.20 × 0.20
20 679, 12 176
0.0363
97.79(3)
90
5988(2)
4
1.520
27.85
0.30 × 0.20 × 0.20
20 137, 12 946
0.032
12 946
683, 4
0.0485; 0.116
1.041
-1.07, 1.33
Z
Dcalcd (g cm-3
)
µ(Mo KR) (cm-1
cryst size (mm)
)
total, unique no. of rflns
Rint
no. of observations used
12 176
624, 7
0.0365; 0.0788
1.036
-1.44, 0.789
no. of params, restrictions
b
Ra, Rw
GOF
min., max. resid dens (e Å -3
)
a R ) ∑||Fo| - |Fc||/∑|Fo|, for all I > 2σ(I). bRw ) [∑w(|Fo| - |Fc|)2/∑wFo
]
.
2
1/2

68 Organometallics, Vol. 24, No. 1, 2005
Li et al.
Figure 4.
tion pathway. Therefore, both the intraligand 1,2-H shift
pathway (path (b), Scheme 1) and the C-H oxidative
addition followed by 1,3-H shift pathway (path (c),
Scheme 1) are possible. Electrospray mass spectroscopy
of the reaction mixture 10b-d confirmed that all the four
possible masses were present, corresponding to 10b-d0
(4.6%), 10b-d1 (24.7%), 10b-d2 (43.4%), and 10b-d3
(27.2%), based on analysis of the isotope patterns.
The contrast between the mechanisms of the insertion
of PhCtCH into 1 and into 11 may be due to electronic
differences, because steric differences at the alkyne
binding site are small. Investigation of the electronic
differences was carried out by bubbling CO through
CH2Cl2 solutions of 1 and 11 to yield carbonyls 13 and
14, respectively (Figure 4). The CO stretching frequen-
cies in IR spectroscopy, a sensitive indicator of the
Figure 5. ORTEP diagram of the cation of 15a shown with
50% probability ellipsoids.
Scheme 7
electronic character of 1 and 11, show that 11 (νCO
)
-1
2042 cm
for CO adduct 14) is much more electron-
-1
rich than 1 (νCO ) 2052 cm
for 13) and should
therefore favor oxidative addition. The nature of the
alkyne substituents also plays a role: oxidative addition
should be favored by electronegative RCtC groups, as
is indeed the case for electron-poor aryl alkynes.
2.3. Insertion of Activated Alkynes into Hydride
1. Activated alkynes [HCtCC(O)R] are also electron-
poor, but they are much more polarized than the alkynes
discussed above. The addition of 2 equiv of HCtCC(O)-
OMe into a CH2Cl2 solution of 1 afforded an orange
solution, from which the simple vinyl 15a was isolated
(89%) as a yellow solid upon addition of ether (Scheme
8). Here, the substrate carbonyl group plays the role of
MeCN in the works described above, preventing sub-
sequent reaction with another equivalent of alkyne. In
have cis monodentate bisphosphine products derived
from trans bisphosphine starting materials without any
cis enforcer such as Cp or Cp*.9a,21
X-ray single-crystal analysis further confirmed this
proposed structure of 15a and that the insertion is anti
(Figure 5, Tables 1 and 3). Complex 15a crystallized in
the C-centered monoclinic space group C2 with one
molecule in the asymmetric unit and four molecules in
the unit cell. The geometry about the iridium atom can
best be described as a slightly distorted octahedron. The
bite-angles of the chelating ligands are 78.2(2)° and
77.8(2)° for O(1)-Ir(1)-C(1) and O(3)-Ir(1)-C(5), re-
spectively, and a strong trans-effect for C(5) is observed,
as the Ir(1)-P(2) bond is 0.15 Å longer than the Ir(1)-
P(1) bond which is trans to O(1). The strong trans-effect
of C(5) is due to its carbenoid character, consistent with
highly low-field resonance of C(5) in 13C NMR spectros-
copy. The two PPh3 ligands are indeed cis to each other,
and the large angle (100.51(6)°) is no doubt due to the
steric repulsion. The backbone of both chelating ligands
is essentially planar, and the phenyl ring, C(8-13), is
offset from this plane by 50.6°.
1
the H NMR spectra (CD2Cl2) of 15a, a characteristic
3
3
low-field resonance at δ 10.80 (dd, JHH ) 7.8 Hz, JPH
) 4.1 Hz), which became a doublet (3JHH ) 7.8 Hz) upon
31P decoupling, was assigned to C(1)-H on the basis of
the carbenoid character of C(1) in the resultant iridafu-
ran. C(2)-H resonates at δ 6.20 (dt, 3JHH ) 7.8 Hz, 4JPH
) 1.5 Hz). The 31P{1H} NMR spectrum of this complex
shows two mutually coupled doublets (10 Hz). This
suggests that the two PPh3 ligands are in a cis orienta-
tion, an extremely rare situation for the [IrH2(PPh3)2]+
fragment. Furthermore, in the 13C{1H} NMR spectrum
(CD2Cl2), C(1) gives a triplet at δ 179.3 (2JPC ) 6.0 Hz)
equally coupled to two cis phosphine ligands. In con-
trast, C(5) in the other iridafuran gives a doublet of
doublets at δ 212.3 (2JPC ) 84 Hz, 2JPC ) 7.4 Hz) due to
both trans (84 Hz) and cis (7.4 Hz) P-Ir-C coupling.
1
Both H and 13C NMR show that only one alkyne unit
is incorporated into the product, even with 2 equiv of
alkyne. An analagous product, 15b, is also observed
when 1 reacts with HCtCC(O)Me. It is rather rare to
(21) (a) Chin, C. S.; Oh, M.; Won, G.; Cho, H.; Shin, D. Polyhedron
1999, 18, 811. (b) Thomptson, J. S.; Bernard, K. A.; Rappol, J. P.;
Atwood, J. D. Organometallics 1990, 9, 2727. (c) Drouin, M.; Harrod,
J. F. Inorg. Chem. 1983, 22, 999. (d) Harrod, J. F.; Hamer, G.; Yorke,
W. J. Am. Chem. Soc. 1979, 101, 3987. (e) Longato, B.; Morandini, F.;
Bresadola, S. Inorg. Chem. 1976, 15, 650.
(20) For reversible alkyne C-H oxidative addition, see: Birk, R.;
Berke, H.; Huttner, G.; Zsolnai, L. Chem. Ber. 1988, 121, 471.

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 69
Scheme 8
Scheme 9
Table 3. Selected Bond Lengths and Angles for
Complex 15a
of the ipso-carbon of the triphenylphosphine ligands is
also consistent with trans-PPh3 groups.
Bond Lengths (Å)
The deuterium labeling pattern is entirely different
from before, indicating another mechanism functions in
this case. When D-CtCC(O)OMe reacts with 1, the
Ir(1)-P(1)
Ir(1)-P(2)
Ir(1)-O(1)
Ir(1)-O(3)
Ir(1)-C(1)
Ir(1)-C(5)
C(5)-C(6)
2.275(1)
2.424(2)
2.147(3)
2.142(4)
2.004(6)
2.079(5)
1.349(8)
1
resultant vinyl 15a-d gives H NMR data indicating
that deuterium remains bound to the same carbon C(1),
and there is essentially no scrambling (<4%). This result
is inconsistent with an alkyne to vinylidene rearrange-
ment (path (b) or (c), Scheme 1), but supports a direct
insertion mechanism (Scheme 9), resembling that pro-
posed in a tungsten case.11 Coordination of the alkyne,
followed by an insertion into the Ir-H, affords a five-
coordinate syn-insertion intermediate. An η2-vinyl in-
termediate then isomerizes this initial syn-insertion
intermediate to the anti one. In this intermediate (15),
carbene C(1), alkyl C(2), and carbene/vinyl C(5) are all
high trans-effect ligands, and either C(1) or C(2) must
be unfavorably located trans to C(5) if the PPh3 ligands
remain in their usual trans arrangement. Rearrange-
ment to the cis phosphine system at this stage avoids
these unfavorable interactions. This step is followed by
the coordination of the carbonyl oxygen to yield the
observed kinetic product 15a. The fact that 15a is the
only product obtained even with 2 equiv of HCtCC(O)-
Bond Angles (deg)
P(1)-Ir(1)-P(2)
C(1)-Ir(1)-O(1)
C(5)-Ir(1)-O(3)
100.51(6)
78.2(2)
77.8(2)
Prolonged reaction led to cis to trans isomerization;
1
the trans product observed in H and 31P NMR spec-
troscopy is identical to 16a, obtained by heating 15a in
1
acetonitrile under reflux. In the H NMR spectrum of
16a, a low-field resonance at δ 10.16 (d, 3JHH ) 7.8 Hz)
is again assigned to the C(1)-H of the iridafuran. The
31P{1H} NMR spectrum of 16a shows a singlet, consis-
tent with a trans phosphine. The 13C{1H} NMR spec-
trum gives further support: C(5) gives a triplet at δ
200.9 (2JPC ) 7.0 Hz) and C(1) another triplet at δ 181.7
(2JPC ) 7.2 Hz). Virtual coupling for the 13C NMR signal

70 Organometallics, Vol. 24, No. 1, 2005
Li et al.
Scheme 10
OMe suggests that the cis-trans isomerization of the
vinyl group and subsequent oxygen binding must be
faster than the insertion of a second equivalent of the
alkyne because the double-insertion product that would
be formed is not seen. Dissociation of the more labile
PPh3 in 15a is expected to yield another fluxional five-
coordinate intermediate. Rearrangement of the chelat-
ing ligands and recoordination of the PPh3 affords the
thermodynamic product 16a.
Figure 6. ORTEP diagram of the cation of 18a shown with
50% probability ellipsoids.
Since the insertion of these alkynes into 1 involved
no alkyne to vinylidine rearrangement, internal alkynes
are also expected to undergo this reaction. Indeed, the
reaction between 1 and Me-CtCCO2Et directly yielded
17 (Scheme 10), a trans phosphine complex, with no cis
phosphine intermediate ever being observed. Similari-
ties were found between the 13C{1H} NMR spectra of
17 and 16a,b.
A related internal alkyne, Ph-CtCC(O)Me, reacts
with 1, however, to give a different vinyl product, 18a
(Scheme 10), by insertion in different regio- and stre-
ochemistry. The choice of this alkyne simplifies the
elucidation of the final product: the insertion of this
alkyne would generate a symmetrical bis-iridafuran if
the insertion pathway for 16a,b or 17 is followed. In
fact, only 18a was obtained. In the 1H NMR spectrum,
the two methyl groups are distinct, and in the 13C{H}
NMR spectrum, a triplet at δ 197.2 and another triplet
at δ 112.0 were clearly assigned to the iridafuran carbon
C(4) and the vinyl carbon C(13), respectively. The 13P-
{1H} NMR spectrum (CD2Cl2) of 18a shows a singlet at
δ 6.48.
An X-ray crystal structure analysis confirmed the
proposed structure for 18a (Figure 6, Tables 1 and 4).
The high trans-effect carbene/vinyl C(4) is cis to the
vinyl C(13). The Ir(1)-C(4) bond is slightly (0.05 Å)
shorter than the Ir(1)-C(13) bond, and the Ir(1)-O(2)
bond is 0.1 Å longer than Ir(1)-O(1). The four-
membered iridacycle is essentially planar, and the
O(2)-Ir-C(13) bite-angle is very acute (62.08°). The
P(1)-Ir(1)-P(2) angle is 170.35°. The formation of 18a
is clearly from a direct syn insertion with different
regiochemistry. This insertion pattern was reported
before only for terminal or symmetrical internal acti-
vated alkynes in Ir,12 Ru,13 Os,13c,14,22 and W11 hydrides.
To distinguish between electronic and steric effects,
Ph-CtCCO2Et, electronically similar to Me-CtCCO2-
Table 4. Selected Bond Lengths and Angles for
Complex 18a
Bond Lengths (Å)
Ir(1)-P(1)
Ir(1)-P(2)
Ir(1)-C(4)
Ir(1)-C(13)
Ir(1)-O(1)
Ir(1)-O(2)
C(13)-C(14)
2.373(1)
2.373(1)
1.994(3)
2.048(3)
2.173(2)
2.272(2)
1.341(5)
Bond Angles (deg)
P(1)-Ir(1)-P(2)
170.35(3)
78.15(12)
62.08(11)
95.3(2)
C(4)-Ir(1)-O(1)
C(13)-Ir(1)-O(2)
Ir(1)-C(13)-C(12)
Ir(1)-O(2)-C(12)
C(13)-C(14)-C(15)
91.3(2)
125.0(3)
Et, but sterically similar to Ph-CtCC(O)Me, was al-
lowed to react with 1. As we expected, 18b, an analogue
of 18a, was isolated, as clearly observed in 13C NMR
spectroscopy, where a triplet at δ 197.6 is assigned to
C(4) and another triplet at δ 103.8 is assigned to the
vinyl carbon C(13). Comparison between insertion of Ph-
CtCC(O)OEt and Me-CtCC(O)OEt into 1 (Scheme 10)
highlights the role of steric effects, which reverse the
direction of the insertion to put the bulky phenyl group
one bond further away from the metal than would be
the case by analogy with 17; the phenyl group also ends
up trans with respect to the metal for the same reason.
The ligand in the four-membered iridacycle would be
expected to be hemilabile, because the carbonyl oxygen
might readily dissociate. Indeed, bubbling CO (1 atm)
slowly converts 18b to 19 within 1 h (eq 4), but no
(22) Bohanna, C.; Callejas, B.; Edwards, A. J.; Esteruelas, M. A.;
Lahoz, F. J.; Oro, L. A.; Ruiz, N.; Valero, C. Organometallics 1998,
17, 373.

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 71
(37% solution in D2O, 0.02 mL). The two layers were separated,
and the aqueous layer was extracted with CH2Cl2 (8 mL). The
CH2Cl2 layers were combined and dried over anhydrous Na2-
SO4, followed by removal of CH2Cl2 under reduced pressure.
1H NMR analysis indicated g98% deuteration of the â-H in
each alkyne.
reaction was found for 18a under the same reaction
conditions, indicating that the more basic ketone car-
bonyl oxygen is more tightly bond than the ester one.
3. Conclusions
General Procedure for the Synthesis of 2a-c (SbF6-).
To a stirred solution of the 1 (SbF6-, 120 mg, 0.104 mmol) in
CH2Cl2 (6 mL) was added 2 equiv of alkyne via syringe. The
color of the solutions changed immediately from yellow to dark
orange. The solutions were then stirred for 2 h at room
temperature and were concentrated to ca. 0.5 mL under
reduced pressure. Diethyl ether (15 mL) was then added to
give yellow powders, which were washed with diethyl ether
(2 × 20 mL), filtered, and dried in vacuo.
These results show that three different mechanisms
for alkyne insertion are possible in this system, with
the outcome being determined by a delicate balance of
steric and electronic effects. The results also show that,
in such cases, it can be dangerous to extend conclusions
based on a single mechanistic study to apparently
closely related cases. For relatively electron-rich alkynes,
double insertion occurs with two independent alkyne to
vinylidene rearrangements to afford η2-butadienyls. In
the first insertion of these alkynes, deuterium labeling
and crossover experiments confirmed that the alkyne
to vinylidene rearrangement is intraligand. Both a vinyl
intermediate and a vinylidene intermediate were trapped
and isolated respectively during the first alkyne inser-
tion. For the second alkyne insertion, a C-H agostic
intermediate was isolated. For insertion of relatively
electron-poor alkynes into 1, double insertion was also
observed. Deuterium labeling experiments show that we
have a rare case of reversible alkyne C-H oxidative
addition preceding insertion. Insertion of highly polar-
ized alkynes [R1CtCC(O)R2] to 1 occurs only once and
involves no vinylidene intermediates even when R1 )
H. The regio- and stereochemistry in this case are
mainly controlled by the steric hindrance of the R1
group. In this series, rare cis-(PPh3)2 intermediates were
isolated in the insertion of highly polarized terminal
alkynes [HCtCC(O)R, R ) Me or OMe] into 1. X-ray
crystal structures of representative products were re-
ported.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenyl-
but-1-en-3-on-1-yl)(1,4-diphenylbuta-1,4-dien-2yl)iridium-
(III) hexafluoantimonate [2a (SbF6-, X ) H)]: yield 86%.
1H NMR [500 MHz, 298 K, CO(Me)2-d6]: δ 7.62 (t, 3JH, H ) 7.4
Hz, 1H), 7.38-7.58 (m, 33H), 7.18 (d, 3JHH ) 7.8 Hz, 2H), 7.12
3
3
(t, JHH ) 7.7 Hz, 2H), 7.04 (m, 3H), 6.82 (d, JHH ) 7.4 Hz,
3
3
2H), 6.42 (d, JHH ) 16.2 Hz, 1H, H(12)), 6.31 (d, JHH ) 7.3
4
Hz, 2H), 5.92 (s, 1H, iridafuran C-H), 5.72 (d, JHH ) 1.6 Hz,
3
4
H(15)), 5.59 (dd, JHH ) 16.2 Hz, JHH ) 1.6 Hz, 1H, H(13)),
1.83 (t, JP, H ) 1.5 Hz, CH3). 13C{1H} NMR (100 MHz, CD2Cl2,
298 K): δ 213.0 (s, CdO), 196.6 (t, JP, ) 5.7 Hz, iridafuran
C
Ir-C), 145.5 (s), 138.2 (s, iridafuran C-H), 137.8 (s), 135.6 (t,
JPC ) 5.2 Hz), 134.9 (s), 133.7 (s, C(12)), 132.7 (t, JPC ) 6.8
Hz, C(14)), 131.5 (s), 130.6 (s), 129.6 (t, JPC ) 5.1 Hz), 129.3
(s), 129.1 (s), 128.7 (s), 128.6 (s), 128.3 (br s, C(15)), 127.4 (s),
127.0 (t, JPC ) 28.0 Hz, ipso-PPh3), 126.7 (s), 100.3 (s, C(3)),
26.6 (s, CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ
4.79 (s). Anal. Calcd for C62H52F6IrOP2Sb: C, 57.15; H, 4.02.
Found: C, 56.98; H, 4.00.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenyl-
but-1-en-3-on-1-yl)(1,4-dibenzylbuta-1,4-dien-2yl)iridium-
(III) hexafluoantimonate [2b (SbF6-, X ) H)]: yield 92%.
1H NMR [500 MHz, 298 K, CO(Me)2-d6]: δ 7.50-7.62 (m, 7
3
H), 7.40-7.48 (m, 24H), 7.38 (t, JHH ) 7.8 Hz, 2H), 7.24-
3
7.30 (m, 5H), 7.10-7.16 (m, 3H), 7.02 (d, JHH ) 7.9 Hz, 2H),
4. Experimental Section
3
6.63 (m, 2H), 6.14 (s, 1H, iridafuran C-H), 5.29 (dt, JHH
)
15.2 Hz, 3JHH ) 7.2 Hz, 1H, H(12)), 4.92 (br d, 3JHH ) 15.2 Hz,
1H, H(13)), 4.82 (td, JH, H ) 7.1 Hz, JH, H ) 1.6 Hz, 1H, H(15)),
2.92 (d, JH, H ) 7.1 Hz, 2H, CH2 vicinal to H(15)), 2.33 (d, 3JHH
) 6.9 Hz, 2H, CH2 vicinal to H(12)), 1.86 (s, 3H, CH3). 13C-
{1H} NMR (100 MHz, CD2Cl2, 298 K): 213.3 (s, CdO), 201.7
General Considerations. All reactions were carried out
under argon, although most of the products proved to be air
stable. CH2Cl2 was distilled from CaH2 under N2. Acetone was
used without further purification. 2-Ethynylbenzyl alcohol23
and iridium hydrides 1 and 54 ware prepared as previously
described. PhCtCD (98% D) and all other nondeuterated
organic chemicals were purchased from Aldrich without
(t, JP, ) 6.1 Hz, iridafuran Ir-C), 145.5 (s), 141.3 (s), 138.0
C
(s), 137.8 (s), 135.5 (t, JPC ) 5.1 Hz, PPh3), 132.4 (s), 131.6 (s),
129.7 (s), 129.6 (s, C(12)), 129.5 (s), 129.4 (t, JPC ) 5.3 Hz,
1
further purification. H and 13C NMR spectra were recorded
PPh3), 129.3 (s), 129.2 (s), 129.0 (s), 128.7 (s), 127.8 (t, JP, C
)
on Bruker 400 or 500 spectrometers, and chemical shifts are
reported with respect to SiMe4. 31P NMR spectra were recorded
on Bruker 400 spectrometers with external 85% H3PO4
standard. 2H NMR spectra were recorded on a GE Ω300
spectrometer using CD2Cl2 as an external standard. Elemental
analyses were performed at Atlantic Microlabs. X-ray diffrac-
tion for single crystals was measured on a Nonius KappaCCD
diffractometer. IR spectra were recorded on a Midac M1200
spectrometer.
Preparation of Deuterated Alkynes. MeOC(O)CtCD
was synthesized according to a literature report.24 PhCH2Ct
CD, p-MeO(C6H4)CtCD, p-CF3(C6H4)CtCD, and p-NO2(C6H4)-
CCD were synthesized from their corresponding protonated
alkynes. To stirred CH2Cl2 (8 mL) solutions of these protonated
alkynes (4.0 mmol) were added D2O (20 mL) and NaOD (40%
solution in D2O, 0.015 mL, 0.21 mmol). The resultant mixtures
were left to stir for 3 days, followed by quenching with DCl
27.5 Hz, ipso-PPh3), 127.4 (s), 126.7 (s), 126.4 (t, JPC ) 6.3 Hz,
C(14)), 124.6 (br s, C(15)), 99.4 (br s, C(13)), 40.3 (s, CH2), 39.7
(s, CH2), 26.6 (s, CH3). 31P{1H} NMR [161.9 MHz, acetone-d6,
298 K]: δ 2.21 (s). Anal. Calcd for C64H56F6IrOP2Sb: C, 57.75;
H, 4.24. Found: C, 57.99; H, 4.56.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(1,4-di-p-methoxyphenylbuta-1,4-dien-2-
yl)iridium(III) hexafluoantimonate [2c (SbF6-, X ) H)]:
recrystalized from CH2Cl2 and diethyl ether, yield 85%. 1H
NMR [400 MHz, 298 K, CO(Me)2-d6]: δ 7.35-7.65 (m, 33H),
3
3
7.16 (d, JHH ) 7.4 Hz, 2H), 6.76 (d, JHH ) 8.7 Hz, 2H), 6.68
3
3
(d, JHH ) 8.7 Hz, 2H), 6.61(d, JHH ) 8.7 Hz, 2H), 6.38 (d,
3JHH ) 16.0 Hz, 1H, H(12)), 6.23 (d, JHH ) 8.7 Hz, 2H), 5.94
3
(s, 1H, iridafuran CH), 5.66 (s, 1H, H(15)), 5.32 (d, 3JHH ) 16.0
Hz, 1H, H(13)), 3.83 (s, 3H, OCH3), 3.70 (s, 3H, OCH3), 1.82
(s, 3H, CH3). 13C{1H} NMR [125.8 MHz, (CD3)2C(O), 298 K]:
δ 213.6 (s), 198.4 (t, JPC ) 6.2 Hz, iridafuran Ir-C), 162.6 (s),
159.4 (s), 146.4 (s), 138.8 (s), 137.0 (s), 136.2 (t, JPC ) 5.1 Hz,
PPh3), 132.9 (s, PPh3), 131.8 (s), 131.5 (s), 131.2 (s), 131.1 (t,
JPC ) 6.5 Hz, C(14)), 130.1 (t, JPC ) 5.0 Hz, PPh3), 129.72 (s),
129.70 (s), 129.0 (s), 128.4 (s), 127.9 (t, JPC ) 27.2, ipso-PPh3),
(23) Nugent, B. M.; Williams, A. L.; Prabhakaran, E. N.; Johnston,
J. N. Tetrahedron 2003, 59, 8877.
(24) Labuschagne, A. J. H.; Schneider, D. F. Tetrahedron Lett. 1983,
24, 743.

72 Organometallics, Vol. 24, No. 1, 2005
Li et al.
115.5 (s), 114.6 (s), 96.5 (s, C(13)), 56.3 (s, OCH3), 55.8 (s,
OCH3), 26.6 (s, CH3). 31P{1H} NMR [161.9 MHz, (CD3)2C(O),
298 K]: δ 5.70 (s). Anal. Calcd for C64H56F6IrO3P2Sb‚0.5CH2-
Cl2‚0.5O(CH2CH3)2: C, 55.37; H, 4.33; Cl, 2.46. Found: C,
55.34; H, 4.37; Cl, 2.45. The stoichiometry of CH2Cl2 and Et2O
Cl2, 298 K): δ 212.6 (s, CdO), 204.5 (t, JPC ) 7.4 Hz, iridafuran
Ir-C), 147.3 (s), 140.9 (s), 140.6 (s), 135.7 (t, JPC ) 5.0 Hz,
PPh3), 131.8 (s, PPh3), 130.2 (s), 129.02 (s), 129.00 (s), 128.8
(t, JPC ) 5.2 Hz, PPh3), 126.7 (t, JPC ) 27.1 Hz, ipso-PPh3),
126.0 (s), 125.3 (s), 121.8 (s, MeCN), 118.4 (t, JPC ) 8.9 Hz,
IrCH), 25.5 (s, CH3), 3.17 (s, CH3CN). 31P{1H} NMR (161.9
MHz, CD2Cl2, 298 K): δ 0.06 (s). Anal. Calcd for C56H49F6-
IrNOP2Sb: C, 54.16; H, 3.98; N, 1.13. Found: C, 54.49; H, 3.88;
N, 1.10.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(4,5-benzo-2-oxacyclohexylidene)(hydrido)-
iridium(III) hexafluoantimonate [4 (BF4-)]. To a stirred
solution of 1 (BF4-, 87 mg, 0.086 mmol) in CH2Cl2 (2 mL) was
added a CH2Cl2 solution (4 mL) of 2-ethynylbenzyl alcohol (23
mg, 0.174 mmol). The solution was stirred for 4 h at 23 °C,
followed by concentration to ca. 0.5 mL under reduced pres-
sure. Diethyl ether was then added, and the mixture was
scratched to give a light yellow powder, which was recrystal-
lized using CH2Cl2 and diethyl ether. Yield: 75 mg (80%). 1H
NMR (400 MHz, CD2Cl2, 295 K): δ 6.90-7.30 (m, 35 H), 6.83
(t, 8.0 Hz, 2H), 6.79 (d, 6.4 Hz, 1H), 6.56 (d, 5.6 Hz, 1H), 6.52
(s, 1H), 4.54 (s, 2H, CH2), 3.50 (s, 2H, CH2), 1.83 (s, 3H, CH3),
-20.94 (t, 13.6 Hz, 1H, Ir-H). 13C{1H} NMR (100 MHz, CD2-
Cl2, 298 K): δ 292.5 (t, 7.0 Hz, IrdC), 228.3 (t, 10 Hz, Ir-C),
213.5 (S), 146.3 (s), 137.6 (s), 134.4(t, 5.4 Hz), 131.7 (s), 130.9
(s), 130.3 (s), 129.7 (t, 28 Hz), 129.0 (t, 5.1 Hz), 128.5 (s), 128.0
(s), 127.9 (s), 126.7 (s), 126.3 (s), 124.8 (s), 79.4 (s, CH2), 59.6
(s, CH2), 26.8 (s). 31P{1H} NMR (161.9 MHz, CD2Cl2, 295 K):
δ 15.32 (s) Anal. Calcd for C55H48BF4IrO2P2: C, 61.06; H, 4.47.
Found: C, 60.78; H, 4.46.
1
was further confirmed by H NMR spectroscopy.
Syntheses of 2a-c (SbF6-, X ) D) are essentially the same
for those of 2a-c (X ) H) with comparable yields. The 1H NMR
(400 MHz, 298 K, acetone-d6) of 2a (X ) D) is essentially the
same as that of 2a (X ) H) except that δ 6.42 (H(12)) and 5.72
(H(15)) are missing (<4% for both) and 5.59 (H(13)) becomes
a singlet. The 1H NMR (400 MHz, 298 K, acetone-d6) of 2b (X
) D) is essentially the same as that of 2b (X ) H) except that
δ 5.29 (H(12)) and 4.82 (H(15)) are missing (<4% for both) and
1
4.92 (H(13)) becomes a singlet. The H NMR (400 MHz, 298
K, acetone-d6) of 2c (X ) D) is essentially the same as that of
2c (X ) H) except that δ 6.38 (H(12)) and 5.66 (H(15)) are
missing (<3% for both) and δ 5.32 (H(13)) becomes a singlet.
Crossover Experiment Using PhCH2CtCH and PhCt
CD. To a stirred solution of 1 (SbF6-, 200 mg, 0.173 mmol, in
5 mL of CH2Cl2) was added a mixture of PhCCD (21.4 mg,
0.207 mmol) and PhCH2CCH (16.1 mg, 0.138 mmol) at room
temperature. The solution changed from light yellow to dark
orange immediately, and it was stirred for 48 h, after which
the volatiles were removed in vacuo to yield a yellow solid.
The solid was then washed with 3 × 15 mL of pentane within
the reaction flask and dried in vacuo. Yield: 207 mg (91%
based on 1). The solid was then dissolved in ca. 1 mL of CD2-
Cl2, and ca. 0.1 mL of this solution was used for NMR (1H and
31P) analysis. A mixture of the four possible complexes (Figure
1) was characterized by 31P NMR. 31P{1H} NMR (161.9 MHz,
CD2Cl2, 298 K): δ 7.56 (s, A); 4.80 (s, B); 2.21 (s, C); and 0.11
(s, D). The ratio was A:B:C:D ) 1.00:1.56:0.76:0.73 from their
31P NMR signal integrations. Complex B is 2a (X ) D) and
complex C is 2b (X ) H), whose 1H NMR spectra were known.
Complex 6 (SbF6-). To the stirred solution of 1 (SbF6-, 249
mg, 0.215 mmol) in 5 mL of CH2Cl2 was added phenylacetylene
(44 mg, 0.431 mmol) at room temperature. The solution
changed from light yellow to dark red immediately. The
resulting solution was stirred for 15 min before it was quickly
concentrated to ca. 0.5 mL in vacuo. Diethyl ether (20 mL)
was added to the solution, and a yellow precipitate formed.
This precipitate was filtered, washed with Et2O (3 × 10 mL),
1
By comparison with the H NMR (400 MHz, CD2Cl2, 298 K)
spectra of the products obtained from 1 and the mixture of
PhCCH and PhCH2CCH, partial assignment is possible. A: δ
6.18 (d, proton residue, 0.04H, H(12)), 5.73 (s, 1H, iridafuran
C-H), 5.52 (s, 1H, H(13)), 4.78-4.85 (m, overlaping of H(15)
of A and H(15) of C), 2.97 (d, 3JHH) 6.8 Hz, 2H, CH2C(15)); B:
neither 6.42 (H(12)) nor 5.72 (H(15)) showed any proton
residue (<3%); D: δ 5.67 (s, proton residue, 0.04H, H(15)),
5.24-5.34 (m, overlaping of H(12) of D and H(12) of C), 5.08
(d, JHH ) 15.2 Hz, 1H, H(13)), 2.40 (d, JHH ) 7.2 Hz, 2H, CH2C-
(12)). 2H NMR (76.77 MHz, 298 K, acetone-d6) of the mixture:
broad and overlapping signals between δ 5.5 and 6.6, absence
of any signal between δ 3.0 and 6.0 (no D-12 in C or D and no
D-15 in A or C).
and dried in vacuo. Yield: 254 mg (0.195 mmol, 91%). Slow
-
diffusion of ether to the dichloromethane solution of 6 (SbF6
)
after 1 day at room temperature afforded an orange plate
crystal of 6 suitable for X-ray diffraction, together with a yellow
1
powder of 7 (SbF6-). H NMR (400 MHz, 298 K, CD2Cl2): δ
7.61 (d, 3JHH ) 8.0 Hz, 1H), 7.02-7.45 (m, 38 H), 6.82 (t, 3JHH
) 8.0 Hz, 1H), 6.80 (t, 3JHH ) 8.0 Hz, 1H), 6.58 (AB d, 3JHH
)
)
3
3
16.0 Hz, 1H), 6.57 (d, JHH ) 8.2 Hz, 1H), 6.50 (AB d, JHH
3
16.0 Hz, 1H), 5.20 (br s, 2H, agostic C-H), 2.38 (t, JHH ) 6.4
3
Hz, 2H, CH2), 2.23 (t, JHH ) 6.2 Hz, 2H, CH2), 1.31 (m, 2H,
CH2). 1H NMR (400 MHz, 198 K, CD2Cl2): 7.47 (t, 3JHH ) 6.8
Hz, 1H), 7.44 (d, 3JHH ) 8.0 Hz, 1H), 6.90-7.40 (m, 37H), 6.78
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(acetonitrile)(2-phenylvinyl)iridium(III)
hexafluoantimonate [3 (SbF6-)]. To a stirred solution of 1
(SbF6-, 200 mg, 0.173 mmol) in CH2Cl2 (6 mL) was added
acetonitrile (0.3 mL). The solution was stirred for 0.5 h before
all the volatiles were removed under reduced pressure (ca. 0.1
mmHg) to give a yellow powder, which was then dissolved in
CH2Cl2 (7 mL), followed by addition of phenylacetylene (18 mg,
0.176 mmol). The solution was stirred at 23 °C for 8 h, during
which time the color of the solution changed from light yellow
to orange. All the volatile was then removed in vacuo to give
a tarry residue, to which was added diethyl ether (60 mL).
The yellow ether solution was collected by filtration, and
removal of diethyl ether afforded a yellow powder, which was
recrystallized twice in diethyl ether to afford the analytically
pure product. Yield: 98 mg (45%). 1H NMR (400 MHz, 298 K,
CD2Cl2, 298 K): δ 8.22 (dt, 3JHH ) 16.0 Hz, 3JPH ) 3.0 Hz, 1H,
3
3
(t, JHH ) 8.2 Hz, 1H), 6.71 (t, JHH ) 8.4 Hz, 1H), 6.55 (d,
3JHH ) 16.0 Hz, 1H), 6.54 (br s, 1H, decoalesced pendant
agostic C-H), 6.46 (d, 3JHH ) 7.2 Hz, 1H), 6.37 (d, 3JHH ) 16.0
Hz, 1H), 3.80 (br s, 1H, actual agostic C-H), 2.38 (br s, 2H,
CH2), 2.12 (br s, 2H, CH2), 1.22 (br s, 2H, CH2).13C{1H} NMR
(100 MHz, CD2Cl2, 193 K): δ 214.7 (s, CdO), 149.0 (s), 148.8
(s), 144.3 (t, JPC ) 7.0 Hz, Ir-C), 143.2 (t, JPC ) 6.7 Hz, Ir-C),
140.0 (s), 139.7 (br s), 137.4 (br s), 136.8 (br s), 136.4 (s), 136.3
(s), 133.9 (br s, P(C6H5)3), 131.7 (s), 130.7 [br s, P(C6H5)3], 130.3
(s), 128.7 (s), 127.8 [br s, P(C6H5)3], 127.0 (s), 126.6 (br s,
decoalesce pendant agostic C-H), 126.1 [t, JHP ) 27.0 Hz, ipso-
PPh3], 126.1 (s, overlapping, confirmed by DEPT45) 125.6 (s),
125.1 (s), 122.6 (s), 107.2 (br s, agostic C-H), 36.5 (s, CH2), 27.3
(s, CH2), 22.3 (s, CH2). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298
K): δ 3.09 (s). Anal. Calcd for C62H52F6IrOP2Sb: C, 57.15; H,
4.02. Found: C, 56.78; H, 4.04.
3
Ir-CH), 7.39-7.48 (m, 7H), 7.24-7.33 (m, 26H), 7.19 (t, JHH
Complex 7 (SbF6-). Complex 6 (SbF6-, 100 mg, 0.0767
mmol) was dissolved in CH2Cl2 (5 mL), and the solution was
heated under reflux for 12 h, after which it was concentrated
to ca. 0.5 mL, followed by addition of Et2O (20 mL). A yellow
precipitate formed and was filtered. It was then washed with
) 8.0 Hz, 2H), 7.05 (t, 3JHH ) 7.3 Hz, 1H), 6.97 (d, 3JHH ) 7.6
3
Hz, 2H), 6.85 (d, JHH ) 7.2 Hz, 2H), 6.44 (s, 1H, iridafuran
3
CH), 5.85 (d, JHH ) 16.0 Hz, 1H, IrCHdCHPh), 1.55 (s, 3H,
Me), 1.45 (s, 3H, Me). 13C{1H} NMR (100.6 MHz, 298 K, CD2-

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 73
Et2O (2 × 15 mL) and dried in vacuo. Yield: 89 mg (0.068
on-1-yl)(1,4-di-p-trifluoromethylphenylbuta-1,4-dien-2-
yl)iridium(III) Hexafluoantimonate [10b (SbF6-)]. To a
stirred solution of the 1 (SbF6-, 150 mg, 0.141 mmol) in acetone
(6 mL) was added p-NO2C6H4CtCH (41.5 mg, 0.282 mmol).
The solutions were stirred for 12 h at 23 °C, followed by
concentration of the solution to ca. 0.5 mL. Diethyl ether (20
mL) was then added to the solution to give a yellow precipitate,
which was then filtered and recrystallized using CH2Cl2 and
diethyl ether. Yield for 10a (SbF6-): 143 mg (0.110 mmol,
1
mmol, 89%). H NMR (400 MHz, 298 K, CD2Cl2): δ 8.10 (d,
3JHH ) 7.6 Hz, 1H), 7.34-7.40 (m, 7H), 7.31 (t, 3JHH ) 7.6 Hz,
3
1H), 7.13-7.25 (m, 26H), 7.10 (t, JHH ) 7.2 Hz, 1H), 7.04 (t,
3
3
3JHH ) 7.6 Hz, 2H), 6.91 (d, JHH ) 8.0 Hz, 2H), 6.63 (d, JHH
3
) 7.2 Hz, 1H), 6.42 (d, JHH ) 16.0 Hz, 1H, H(12)), 6.34 (d,
3JHH ) 7.9 Hz, 2H), 6.22 (s, 1H, H(15)), 5.38 (d, JHH ) 16.0
3
Hz, 1H, H(13)), 2.16 (t, 3JHH ) 6.4 Hz, 2H, CH2), 2.09 (t, 3JHH
) 6.0 Hz, 2H, CH2), 1.11 (m, 2H, CH2CH2CH2). 13C{1H} NMR
1
3
(100 MHz, CD2Cl2, 298 K): δ 215.7 (s, CdO), 152.0 (t, JPC
)
78%). H NMR (400 MHz, acetone-d6, 283 K): δ 8.00 (d, JHH
) 8.5 Hz, 2H), 7.88 (d, 3JHH ) 8.4 Hz, 2H), 7.69 (t, 3JHH ) 7.5
Hz, 1H), 7.48-7.69 (m, 32H), 7.25 (d, 3JHH ) 7.4 Hz, 2H), 7.09
7.8 Hz, Ir-C), 150.8 (s), 143.7 (s), 138.1 (s), 137.0 (s), 135.1 (t,
JPC ) 5.2 Hz, PPh3), 134.9 (s), 133.5 (t, JP, C ) 6.6 Hz, C(14)),
133.0 (s), 131.9 (s), 129.9 (s), 129.5 (s), 129.3 (t, JPC ) 5.0 Hz,
PPh3), 128.9 (s), 128.5 (s), 127.7 (s), 127.4 (t, JPC ) 27.0 Hz,
ipso-PPh3), 127.3 (s), 126.7 (s), 126.0 (s, C(15)), 123.7 (s), 119.3
(s, C(12)), 100.6 (s, C(13)), 37.2 (s, CH2), 28.4 (s, CH2), 22.8 (s,
CH2).31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 0.96(s).
Anal. Calcd for C62H52F6IrOP2Sb: C, 57.15; H, 4.02. Found:
C, 57.15; H, 4.27.
3
3
(d, JHH ) 8.5 Hz, 2H), 6.40 (d, JHH ) 16.4 Hz, 1H), 6.11 (d,
3JHH ) 16.4 Hz, 1H), 5.88 (s, 1H), 5.73 (s, 1H), 1.81 (s, 3H,
CH3). 13C{1H} NMR (100 MHz, acetone-d6, 298 K): δ 214.1 (s,
CO), 190.2 (t, JPC ) 6.0 Hz, iridafuran Ir-C), 148.2 (s), 146.2
(s), 143.7 (s), 141.4 (t, JPC ) 6.9 Hz, C(14)), 141.3 (s), 138.4
(s), 135.7 (t, JPC ) 5.2 Hz, PPh3), 133.0 (s, PPh3), 131.8 (s),
130.6 (s), 130.0 (t, JPC ) 5.2 Hz, PPh3), 129.6 (s), 129.4 (s),
128.8 (s), 128.2 (s), 128.1 (t, JPC ) 2.6 Hz, C(15)), 126.5 (t, JPC
) 28 Hz, ipso-PPh3), 124.5 (s), 124.2 (s), 111.5 (s), 26.0 (s, CH3).
31P{1H} NMR (161.9 MHz, (CD3)2CO, 298 K): δ 8.01 (s, PPh3),
-142.1 (septet, 2JPF ) 708 Hz, PF6-). Anal. Calcd for C62H50F6-
IrN2O5P3: C, 57.19; H, 3.87; N, 2.15. Found: C, 57.46; H, 4.24;
N, 2.06. Complex 10a-d (SbF6-) was obtained at a comparable
yield through a direct method analogous to the synthesis of
10a (SbF6-). The 1H NMR spectrum of 10a-d (SbF6-) is similar
to that of 10a (SbF6-) except for three peaks: δ 6.40 (m, 0.41H),
6.11 (m, 0.30H), and 5.73 (m, 0.30H).
Observation of Complex 8 (SbF6-). In an NMR tube, 1
(SbF6-, 30 mg, 0.0259 mmol) was dissolved in CD2Cl2 (0.7 mL).
To this solution was added via syringe o-CF3C6H4CtCH (5.6
1
mg, 0.052 mmol) at 20 °C. The H, 31P, and 19F NMR spectra
(CD2Cl2, 10 °C) were quickly (within 25 min) measured, and
31P and 19F NMR spectra indicated that the solution contained
8 (88%) and 9 (12%). Partial 1H NMR (400 MHz, CD2Cl2, 283
K): δ 7.87 (s, 1H), 7.56 (d, 3JHH ) 8.0 HZ, 1H), 7.25 (t, 3JHH
)
3
3
7.6 Hz, 1H), 7.16 (t, JHH ) 7.4 HZ, 1H), 7.00 (d, JHH ) 16.0
Hz, 1H), 6.87 (m, 3.0 H), 6.58 (m, 2H), 6.07 (d, 3JHH ) 7.6 Hz,
3
The synthesis of 10b (SbF6-) is analogous to that of 10a
(SbF6-), using 1 (SbF6-, 150 mg, 0.130) and 2 equiv of
p-CF3C6H4CtCH (45 mg, 0.265 mmol) in acetone or CH2Cl2
(6 mL). Yield: 142 mg (0.099 mmol, 76%). 1H NMR (500 MHz,
1H), 5.57 (d, JHH ) 16.0 Hz), 5.24 (s, 1H), 3.67 (br s, 1H),
1.78 (s, 3H, CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 283 K):
δ 2.53. 19F{1H} NMR (376.3 MHz, CD2Cl2, 283 K): δ -59.32
(s), -60.77 (s). Isolation of 8 (SbF6-) was attempted, but only
a mixture of 8 (SbF6-) and 9 (SbF6-) in a ratio of 3:1 was
obtained.
3
3
298 K, CD2Cl2): δ 7.60 (t, JHH ) 7.5 Hz, 1H), 7.49 (t, JHH
)
)
3
7.3 Hz, 6H, para-PPh3), 7.29-7.45 (m, 28H), 7.27 (d, JHH
3
3
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(1,4-di-o-trifluoromethylphenylbuta-1,4-
dien-2-yl)iridium(III) hexafluoantimonate [9 (SbF6-)]. To
a stirred solution of 1 (SbF6-, 150 mg, 0.130 mmol) in CH2Cl2
(6 mL) was added o-CF3C6H4CtCH (45 mg, 0.264 mmol) via
syringe. The color of the solution changed from yellow to
orange immediately. The solution was then stirred for 18 h at
28 °C before all the solvent was removed under reduced
pressure to give a yellow tar, which was washed with ether (2
× 20 mL) until the ether solution was almost colorless. The
ether solution was discarded, and a yellow powder was
obtained, which was dissolved in CH2Cl2 (1 mL), quickly
precipitated with ether (20 mL), filtered, and dried in vacuo.
8.1 Hz, 2H), 7.08 (d, JHH ) 8.1 Hz, 2H), 6.32 (d, JHH ) 15.6
Hz, 1H, H(14)), 6.30 (d, 3JHH ) 7.2 Hz, 2H), 5.70 (s, 1H), 5.64
(s, 1H), 5.59 (d, 3JHH ) 15.6 Hz, 1H, H(13)), 1.69 (s, 3H, CH3).
13C{1H} NMR (100 MHz, CD2Cl2, 298 K): δ 213.2 (s, CO), 192.3
(t, JPC ) 6.2 Hz, iridafuran Ir-C), 144.9 (s), 140.7 (s), 138.2
(s), 137.8 (s), 136.2 (t, JPC ) 6.7 Hz, C(14)), 135.2 (t, JPC ) 5.2
Hz, PPh3), 132.5 (s, PPh3), 131.5 (s), 130.6 (s), 129.4 (t, JPC
)
5.1 Hz, PPh3), 129.2 (s), 128.5 (s), 127.8 (s), 127.6 (br s), 127.2
(s), 126.2 (t, JPC ) 27.7 Hz, ipso-PPh3), 126.1 (q, JFC ) 3.7 Hz,
C-CF3), 125.5 (q, JFC ) 3.6 Hz, C-CF3), 124.8 (q, JFC ) 271 Hz,
CF3), 124.5 (q, JFC ) 272 Hz, CF3), 106.9 (br s, C(14)), 26.1 (s,
CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 5.25 (s).
19F{1H} NMR (376.3 MHz, CD2Cl2, 283 K): δ -63.02 (s, 3F,
CF3), -63.64 (s, 3F, CF3). Anal. Calcd for C64H50F12IrOP2Sb:
C, 53.42; H, 3.50. Found: C, 53.07; H, 3.57.
Complex 10b-d (SbF6-) was obtained at a comparable yield
through a direct method analogous to the syntheis of 10b
(SbF6-). The 1H NMR spectrum of 10b-d (SbF6-) is similar to
that of 10b (SbF6-) except for three peaks: δ 6.32 (m, 0.44H),
5.64 (s, 0.26H), and 5.59 (m, 0.29H). Electron-spray MS
[molecular ion peaks, cation mode, mass (intensity)]: 1201.2
(3.46), 1202.2 (20.7), 1203.2 (51.6), 1204.2 (81.8), 1205.2 (100,
normalized), 1206.2 (86.3), 1207.2 (40.4), 1208.2 (11.8), 1209.2
(3.0). Calculated mole percentage of 10b-d0, 10b-d1, 10b-d2,
and 10b-d3 is 4.6, 24.7, 43.4, and 27.2, respectively.
1
Yield: 120 mg (0.083 mmol, 64%). The H NMR spectrum of
1
this powder [9 (SbF6-)] was quickly measured. H NMR (400
3
MHz, 298 K, CD2Cl2): δ 7.61 (t, JHH ) 7.5 Hz, 1H), 7.56 (d,
3
3JHH ) 7.8 Hz, 1H), 7.28-7.52 (m, 36H), 7.10 (t, JHH ) 7.6
Hz), 7.04 (m, 1H), 6.94 (t, 3JHH ) 7.6 Hz, 1H), 6.65 (d, 3JHH
)
15.6 Hz, 1H, H(12)), 6.43 (d, 3JHH ) 7.8 Hz, 1H), 6.10 (s, 1H),
3
5.91 (d, JHH ) 15.6 Hz, 1H, H(13)), 5.53 (s, 1H), 1.60 (s, 3H,
CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 8.74. 19F-
{1H} NMR (376.3 MHz, CD2Cl2, 298 K): δ -59.55 (s, 3F), 59.58
(s, 3F). Anal. Calcd for C64H50F12IrOP2Sb: C, 53.42; H, 3.50.
Found: C, 53.29; H, 3.70.
Measurement of the Keq between 8 (SbF6-) and 9
(SbF6-). In an NMR tube charged with a mixture of 8 (SbF6
)
-
trans-Bis(triphenylphosphine)(2-o-pyridylphenyl)(ac-
etone)(hydrido)iridium(III) Hexafluoantimonate [11
(SbF6-)]. To a stirred solution of [Ir(H)2(PPh3)2(acetone)2]SbF6
(300 mg, 0.280 mmol) in acetone (3 mL) was added via syringe
2-phenylpyridine (44 mg, 0.284 mmol). Bubbling and precipi-
tation were immediately observed. Diethyl ether (15 mL) was
then added to the suspension. The white precipitate was then
filtered and washed with diethyl ether (15 mL). Yield: 294
mg (0.252 mmol, 90%). 1H NMR (500 MHz, acetone-d6, 298
and 9 (SbF6-) in a ratio of 3:1 (18 mg) was added CD2Cl2 (0.7
mL). Enough time (6 h for 35 °C, 24 h for 28 °C, and 40 h for
21 °C) was allowed for the equilibrium to be reached. The [η2-
butadienyl 9]/[agostic 8] ratio at equilibrium was measured
to be 22.7, 17.8, and 13.7 at 21, 27, and 35 °C, respectively,
based on 31P{1H} NMR analysis.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(1,4-di-p-nitrophenylbuta-1,4-dien-2-yl)iri-
dium(III) Hexafluoantimonate [10a (SbF6-)] and trans-
Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-1-en-3-
3
K): δ 9.49 (s, 1H), 7.60 (t, JHH ) 7.5 Hz, 1H), 7.43 (m, 6H,
3
PPh3), 7.27-7.38 (m, 13H) 7.15-7.25 (m, 15H), 6.88 (t, JHH

74 Organometallics, Vol. 24, No. 1, 2005
Li et al.
3
) 7.5 Hz, 1H), 6.49 (t, JHH ) 7.1 Hz, 1H), 2.11 (s, 6H, CH3),
solution was then concentrated to ca. 0.5 mL under reduced
pressure, followed by precipitation using diethyl ether (15 mL).
The white powder was filtered and dried in vacuo. Yield: 77
mg (0.068 mmol, 98%). 1H NMR (500.1 MHz, CD2Cl2, 298 K):
-15.77 (t, 2JPH ) 15.4 Hz, Ir-H). 13C{1H} NMR (100 MHz, CD2-
Cl2, 298 K): δ 164.2 (s), 148.1 (s), 144.5 (s), 141.6 (s), 137.5
(s), 134.1 (t, JPC ) 5.5 Hz, PPh3), 132.7 (t, JPC ) 8.6 Hz, Ir-C),
131.0 (s, PPh3), 129.9 (s), 128.8 (t, JPC ) 5.2 Hz, PPh3), 128.3
(t, JPC ) 26.5 Hz, ipso-PPh3), 125.3 (s), 122.9 (s), 122.2 (s), 119.9
(s), 31.7 (s, CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K):
δ 17.35 (s). Anal. Calcd for C50H45F6IrNOP2Sb: C, 51.51; H,
3.89; N, 1.20; F, 9.78. Found: C, 51.52; H, 3.86; N, 1.26; F,
9.64.
3
3
4
δ 8.81 (d, JHH ) 5.5 Hz, 1H), 7.53 (td, JHH ) 8.0 Hz, JHH
)
3
1.5 Hz, 1H), 7.40 (t, JHH ) 7.5 Hz, 6H, PPh3), 7.25-7.35 (m,
12H), 7.05-7.22 (m, 16H), 6.99 (td, 3JHH ) 7.8 Hz, 4JHH ) 1.0
3
2
Hz, 1H), 6.62 (t, JHH ) 7.5 Hz, 1H), -15.26 (t, JPH ) 12.5
Hz, 1H, Ir-H). 13C{1H} NMR (125.7 MHz, CD2Cl2, 298 K): δ
175.0 (t, JPC ) 7.4 Hz, CO), 165.0 (s), 153.3 (t, JPC ) 10.7 Hz,
Ir-C), 147.4 (s), 143.3 (s), 138.7 (s), 133.9 (t, JPC ) 5.4 Hz,
PPh3), 131.9 (s, PPh3), 131.2 (s), 129.1 (t, JPC ) 5.2 Hz, PPh3),
128.2 (t, JPC ) 29.1 HZ, ipso-PPh3), 126.7 (s), 124.9 (s), 124.6
(s), 121.1 (s). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ
5.83 (s). IR (CH2Cl2 film): 2042 cm-1 (νCO). Comparisons of
these data to those in previous literature confirmed the
structure of 14 (SbF6-).
trans-Bis(triphenylphosphine)(2-o-pyridylphenyl)(1,4-
diphenylbuta-1,4-dien-2-yl)iridium(III) Hexafluoanti-
monate [12 (SbF6-) and 12-d (SbF6-)]. To a stirred suspen-
sion of 11 (SbF6-, 200 mg, 0.172 mmol) in CH2Cl2 (4 mL) was
added PhCtCH (35 mg, 0.344 mmol). A red solution was
quickly formed. The solution was stirred at 23 °C for 2 h before
it was concentrated to ca. 0.5 mL. Diethyl ether (20 mL) was
added to the solution, and an orange precipitate appeared,
which was filtered, washed with ether (20 mL), and dried in
vacuo. Yield: 180 mg (0.137 mmol, 80%). A crystal of 12
(SbF6-) suitable for X-ray crystal structure analysis was
obtained by careful layering of the acetone solution of 12
cis-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-1-
en-3-on-1-yl)(η2-{O,C1}-methylprop-1-enoat-1-yl)iridium-
(III) Hexafluoantimonate [15a (SbF6-) and 15a-d (SbF6-)].
To a stirred solution of 1 (SbF6-, 150 mg, 0.130 mmol) in CH2-
Cl2 (6 mL) was added HCtCCO2Me (22 mg, 0.262 mmol) via
syringe. The solution was then stirred at 23 °C for 8 h, during
which time the color changed from light yellow to orange. The
solution was then concentrated to ca. 0.5 mL, followed by slow
addition of diethyl ether (15 mL). Yellow microcrystals formed,
which were filtered and washed with diethyl ether (2 × 15
mL). Analytically pure 15a (SbF6-) was obtained by drying
the microcrystal in vacuo. Yield: 136 mg (116 mmol, 89%).
1
(SbF6-) with pentane. H NMR (500 MHz, CD2Cl2, 298 K): δ
3
3
8.82 (d, JHH ) 5.1 Hz, 1H), 8.15 (d, JHH ) 7.4 Hz, 1H), 7.59
3
3
(t, JHH ) 7.3 HZ, 1H), 7.48 (t, JHH ) 7.5 Hz, 1H), 7.42 (t,
3JHH ) 7.6 Hz, 2H, Ph), 6.93-7.40 (m, 38 H), 6.80 (t, JHH
)
)
3
3
3
7.4 Hz, 1H), 6.58 (d, JHH ) 7.4 Hz, 2H, Ph), 6.52 (d, JHH
3
7.4 Hz, 1H), 6.37 (d, JHH ) 15.8 Hz, 1H, H(12)), 6.15 (s, 1H,
H(15)), 5.74 (d, JHH ) 15.8 Hz, 1H, H(13)). 13C{1H} NMR
3
3
1H NMR (400 MHz, CD2Cl2, 298 K): δ 10.80 (dd, JHH ) 7.8
(125.7 MHz, CD2Cl2, 302 K): δ 164.1 (s), 153.3 (s), 143.9 (s),
143.0 (br s), 139.1 (s), 138.8 (s), 135.7 (s), 134.8 (t, JPC ) 5.1
Hz, PPh3), 133.7 (s), 131.5 (s, PPh3), 131.2 (s), 131.0 (s), 130.3
(s), 129.9 (s), 129.0 (t, JPC ) 5.0 Hz, PPh3), 128.8 (t, JPC ) 6.0
Hz, C(14)), 128.2 (s), 128. 1 (s, C(12)), 127.8 (t, JPC ) 27.8 Hz,
ipso-PPh3), 127.4 (s), 127.2 (br s, C(15)), 126.1 (s), 125.9 (s),
124.4 (s), 123.7 (s), 121.6 (s), 103.8 (s, C(13)). 31P{1H} NMR
(161.9 MHz, CD2Cl2, 298 K): δ 2.27 (s). Anal. Calcd for
C63H51F6IrNP2Sb‚C3H6O: C, 57.86; H, 4.19; N, 1.02; Found:
C, 58.29; H, 4.12; N, 1.16.
3
Hz, JPH ) 4.1 Hz, 1H, IrCH, turned into a doublet (3JHH
)
7.8 Hz in 1H{31P} NMR spectroscopy), 7.03-7.53 (m, 31H), 7.00
3
4
(t, JHH ) 7.4 Hz, 2H, Ph), 6.84 (d, JPH ) 9.3 Hz, 1H,
iridafuran CH, turned into a singlet in 1H{31P} NMR spec-
troscopy), 6.32 (d, 3JHH ) 7.4 Hz, 2H, Ph), 6.20 (dt, 3JHH ) 7.8
4
Hz, JPH ) 1.5 Hz, 1H, IrCHdCH), 3.20 (s, 3H, OCH3), 2.39
(s, 3H, CH3). 13C{1H} NMR (125.7 MHz, CD2Cl2, 298 K): δ
216.8 (d, JPC ) 9.2 Hz, ketone iridafuran CdO), 212.3 (dd, JPC
) 84 Hz, JPC ) 7.5 Hz, iridafuran Ir-CPh), 185.3 (d, JPC ) 1.5
Hz, ester CO), 179.3 (t, JPC ) 6.0 Hz, IrCH), 142.6 (s), 137.0
(s), 135.2 (d, JPC ) 8.0 Hz, PPh3), 135.1 (d, JPC ) 10.6 Hz,
PPh3), 132.3 (d, JPC ) 2.5 Hz, PPh3), 131.7 (d, JPC ) 2.3 Hz,
PPh3), 130.4 (s), 130.2 (d, JPC ) 2.2 Hz), 129.7 (d, JPC ) 44
The synthesis of 12-d (SbF6-) followed the same method as
that of 12 (SbF6-), using 11 (SbF6-, 200 mg, 0.172 mmol) and
PhCtCD (36 mg, 0.349 mmol) in CH2Cl2 (4 mL). Yield: 168
1
mg (0.128 mmol, 75%). The H NMR (500 MHz, CD2Cl2, 298
K) data of 12-d (SbF6-) are the same as those of 12 (SbF6-),
except for three signals: δ 6.37 (m, 54% H, H(12)), 6.15 (s,
Hz, ipso-PPh3), 129.2 (d, JPC ) 2.0 Hz, PPh3), 129.1 (d, JPC
)
3.3 Hz, PPh3), 128.3 (dd, JPC ) 62.7 Hz, JPC ) 2.2 Hz, ipso-
PPh3), 127.9 (s), 124.0 (s), 55.1 (s, OCH3), 26.9 (s, CH3). 31P-
{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 0.20 (d, JPP ) 10
Hz, PPh3), -11.40 (d, JPP ) 10 Hz, PPh3). Anal. Calcd for
C50H44F6IrO3P2Sb: C, 50.77; H, 3.75. Found: C, 50.99; H, 3.79.
The synthesis of 15a-d (SbF6-) followed the same method
2
10% H, H(15)), 5.74 (m, 43% H, H(13)). H NMR (76.8 MHz,
CH2Cl2, 298 K): δ 5.0-6.8 (m, br).
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenyl-
but-1-en-3-on-1-yl)(carbonyl)(hydrido)iridium(III) Hexa-
fluoantimonate [13 (SbF6-)]. To a solution of 1 (SbF6-, 80
mg, 0.069 mmol) in CH2Cl2 (8 mL) was bubbled CO (1 atm)
for 15 min. The solution was then concentrated to ca. 0.5 mL
under reduced pressure, followed by precipitation using diethyl
ether (15 mL). The light yellow powder was filtered and dried
in vacuo. Yield: 75 mg (0.067 mmol, 96%). 1H NMR (500.1
-
as that of 15a (SbF6-), using 1 (SbF6 salt, 150 mg, 0.130
mmol) and DCtCCO2Me (22 mg, 0.260 mmol) in CH2Cl2 (4
mL). Yield: 128 mg (0.108 mmol, 83%). The 1H NMR (400
MHz, CD2Cl2, 298 K) data of 15a-d are the same as those of
15a, except for two signals: δ 10.80 missing (IrCD, <5% H),
2
3
6.20 (s, IrCDdCH). H NMR (76.77 MHz, CH2Cl2, 298 K): δ
MHz, CD2Cl2, 298 K): δ 7.55 (t, JHH ) 7.1 Hz, 6H, PPh3),
7.37-7.47 (m, 24H), 7.25-7.29 (m, 3H), 7.08 (t, 3JHH ) 7.7 Hz,
2H), 6.79 (s, 1H, iridafuran CH), 1.90 (s, 3H, CH3), -18.90 (t,
2JPH ) 11.7 Hz, Ir-H). 13C{1H} NMR (125.7 MHz, CD2Cl2, 298
K): δ 219.7 (t, JPC ) 9.2 Hz, iridafuran Ir-C), 215.3 (s,
iridafuran CO), 173.1 (t, JPC ) 6.3 Hz, CO), 142.2 (s), 136.2
(s), 134.4 (t, JPC ) 5.7 Hz, PPh3), 132.5 (s, PPh3), 132.2 (s),
131.5 (br s), 129.2 (t, JPC ) 5.5 Hz, PPh3), 128.7 (s), 127.6 (t,
JPC ) 29.8 Hz, PPh3), 26.3 (s, CH3). 31P{1H} NMR (161.9 MHz,
CD2Cl2, 298 K): δ 8.38 (s). IR (CH2Cl2 film): 2052 cm-1 (νCO).
Anal. Calcd for C47H40F6IrO2P2Sb: C, 50.10; H, 3.58. Found:
C, 50.50; H, 3.74.
10.8 (s).
cis-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-1-
en-3-on-1-yl)(η2-{O,C2}-pent-2-en-3-on-2-yl)iridium(III)
Hexafluoantimonate [15b (SbF6-)]. The synthesis of 15b
(SbF6-) is directly analogous to that of 15a (SbF6-) using 1
(SbF6-, 120 mg, 0.104 mmol) and HCtCC(O)Me (14 mg, 0.026
mmol) in CH2Cl2 at 23 °C. Yield: 95 mg (0.081 mmol, 78%).
3
1H NMR (400 MHz, CD2Cl2, 298 K): δ 11.29 (dd, JHH ) 7.2
3
Hz, JPH ) 3.6 Hz, 1H, IrCHdCH), 7.00-7.50 (m, 31H), 6.97
3
4
(t, JHH ) 7.6 Hz, 2H, Ph), 6.74 (d, JPH ) 9.2 Hz, 1H,
3
iridafuran CH), 6.62 (d, JHH ) 7.2 Hz, 1H, IrCHdCH), 6.35
3
trans-Bis(triphenylphosphine)(2-o-pyridylphenyl)(car-
bonyl)(hydrido)iridium(III) Hexafluoantimonate [14
(SbF6-)]. To a solution of 11 (SbF6-, 80 mg, 0.069 mmol) in
CH2Cl2 (8 mL) was bubbled CO (1 atm) for 20 min. The
(d, JHH ) 7.6 Hz, 2H, Ph), 2.35 (s, 3H, CH3), 1.58 (d, JPH
)
2.0 Hz, 3H, CH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 298 K):
215.7 (d, JPC ) 7.4 Hz, CO), 212.4 (t, JPC ) 2 Hz,), 211.8 (dd,
JPC ) 79.2 Hz, JPC ) 7.6 Hz, IrCPhd), 198.5 (t, JPC ) 5.6 Hz,

Insertion of Alkynes into an Ir(III) Hydride
Organometallics, Vol. 24, No. 1, 2005 75
IrCH), 143.9 (s), 137.8 (s), 136.4 (s), 134.7 (d, JPC ) 2.6 Hz,
PPh3), 134.6 (d, JPC ) 2.6 Hz, PPh3), 131.8 (d, JPC ) 2.5 Hz,
(s). Anal. Calcd for C52H48F6IrO3P2Sb: C, 51.58; H, 4.00.
Found: C, 51.51; H, 3.94.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(η2-{O,C2}-1-phenyl-but-1-(E)-en-3-one-2-
yl)iridium(III) Tetrafluoroborate [18a (BF4-)] and trans-
Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-1-en-3-
on-1-yl)(η2-{O,C2}-ethylbut-2-(E)-enoat-2-yl)iridium-
PPh3), 131.2 (d, JPC ) 2.0 Hz, PPh3), 129.9 (s), 129.1 (d, JPC
2.2 Hz), 128.7 (d, JPC ) 6.7 Hz, PPh3), 128.60 (d, JPC ) 6.1 Hz,
PPh3), 128.57 (d, JPC ) 45.4 Hz, ipso-PPh3), 127.9 (dd, JPC
)
)
60.6 Hz, JPC ) 2.0 Hz, ipso-PPh3), 127.7 (s), 26.4 (s, CH3), 23.7
(d, JPC ) 4.1 Hz, CH3). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298
K): δ 4.73 (d, JPP ) 11.6 Hz, PPh3), -11.40 (d, JPP ) 11.7 Hz,
PPh3). Anal. Calcd for C50H44F6IrO2P2Sb: C, 51.47; H, 3.80.
Found: C, 51.49; H, 3.80.
(III) Hexafluoroantimonate [18b (SbF6-)]. The synthesis
-
of 18a (BF4-) is directly analogous to that of 17 using 1 (BF4
,
101 mg, 0.100 mmol) and Ph-CtCC(O)Me (29 mg, 0.201
mmol). Yield: 85% (93 mg, 0.085 mmol). H NMR (500 MHz,
acetone-d6, 295 K): δ 7.45-7.60 (m, 31H), 7.4 (t, JHH ) 7.0
Hz, 2H), 7.21-7.32 (m, 5H), 7.12 (s, 1H), 6.68 (d, JHH ) 6.7
1
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(η2-{O,C1}-methylprop-1-enoat-1-yl)iridium-
(III) Hexafluoantimonate [16a (SbF6-)]. Complex 15a
(SbF6-, 100 mg, 0.084 mmol) was dissolved in acetonitrile (5
mL) and was refluxed for 10 h. The solvent was then removed
under reduced pressure to give a yellow residue, which was
washed with diethyl ether (15 mL) to give a yellow powder.
Analytically pure 15a (SbF6-) was obtained by drying this
3
3
Hz, 2H), 6.37 (s, 1H), 1.68 (s, 3H), 0.95 (s, 3H). 13C NMR (125
MHz, CD2Cl2, 295 K): δ 227.7 (s), 212.8 (s), 197.2 (t, JPC ) 5.4
Hz, iridafuran Ir-C), 148.8 (s), 147.8 (s), 139.0 (s), 138.4 (s),
135.5 (t, JPC ) 5.4 Hz, PPh3), 132.2 (s), 131.05 (s), 129.30, (s),
129.29 (t, JPC ) 5.4 Hz, PPh3), 128.9 (s), 128.4 (s), 128.2 (s),
126.8 (t, JPC ) 27 Hz, ipso-PPh3), 111.6 (t, JPC ) 6 Hz, Ir-C),
32.3 (s), 24.8 (s). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K):
δ 6.48 (s). Anal. Calcd for C56H48BF4IrO2P2: C, 61.48; H, 4.42.
Found: C, 61.73, H, 4.49.
1
powder in vacuo. Yield: 90 mg (0.076 mmol, 90%). H NMR
3
(400 MHz, CD2Cl2, 298 K): δ 10.17 (d, JHH ) 7.8 Hz, 1H,
3
IrCHdCH), 7.10-7.65 (m, 33H), 7.05 (d, JHH ) 7.2 Hz, 2H,
Ph), 6.39 (s, 1H, iridafuran CH), 6.00 (dt, 3JHH ) 7.8 Hz, 3JPH
5
The synthesis of 18b (SbF6-) is also directly analogous to
that of 17 using 1 (SbF6-, 85 mg, 0.073 mmol) and Ph-CtCC-
(O)OEt (25 mg, 0.144 mmol). Yield: 88% (82 mg, 0.065 mmol).
1H NMR (500 MHz, CD2Cl2, 295 K): δ 7.30-7.55 (m, 31H),
) 1.4 Hz, 1H, IrCHdCH), 2.89 (s, 3H, OCH3), 1.45 (t, JPH
)
1.5 Hz, CH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 298 K): δ
213.3 (s, ketone CO), 200.9 (t, JPC ) 5.8 Hz, IrCPh), 184.4 (s,
ester CO), 181.7 (t, JPC ) 7.2 Hz, IrCHdCH), 147.2 (s), 138.8
(s), 135.5 (t, JPC ) 5.2 Hz, PPh3), 132.2 (s, PPh3), 130.8 (s),
129.6 (s), 129.0 (t, JPC ) 5.2 Hz, PPh3), 127.9 (s), 126.0 (t, JPC
) 27.8 Hz, ipso-PPh3), 123.8 (s), 54.3 (s, OCH3), 25.1 (s, CH3).
31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 9.44 (s). Anal.
Calcd for C50H44F6IrO3P2Sb: C, 50.77; H, 3.75. Found: C,
50.67; H, 3.62.
7.27 (t, 3JHH ) 7.6 Hz, 2H), 7.15-7.25 (m, 3H), 7.03 (d, 3JHH
)
3
7.6 Hz, 2H), 6.70 (d, JHH ) 7.9 Hz, 2H), 6.58 (s, 1H), 6.29 (s,
3
3
1H), 3.22 (q, JHH ) 7.2 Hz, 2H), 1.50 (s, 3H), 0.65 (t, JHH
)
7.2 Hz, 3H). 13C NMR (125 MHz, CD2Cl2, 295 K): δ 212.7 (s),
197.7 (t, JPC ) 5.4 Hz, iridafuran Ir-C), 184.7 (s), 147.7 (s),
145.4 (s), 138.8 (s), 137.6 (s), 135.5 (t, JPC ) 5.4 Hz, PPh3),
132.2 (s), 131.0 (s), 129.2 (t, JPC ) 5.4 Hz, PPh3) 129.1 (s), 128.6
(s), 128.4 (s), 128.2 (s), 126.3 (t, JPC ) 26.9 Hz, ipso-PPh3), 104.0
(t, JPC ) 7.5 Hz, Ir-C), 63.4 (s), 24.5 (s), 13.6 (s). 31P{1H} NMR
(161.9 MHz, CD2Cl2, 298 K): δ 5.54 (s). Anal. Calcd for
C57H50F6IrO3P2Sb‚CH2Cl2: C, 51.30; H, 3.86; Cl, 5.22. Found:
C, 51.33; H, 3.84; Cl, 5.57.
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenyl-
but-1-en-2-on-1-yl)(η2-{O,C2}-pent-2-en-3-on-2-yl)iridium-
(III) Hexafluoantimonate [16b (SbF6-)]. The synthesis of
16b (SbF6-) is directly analogous to that of 16a (SbF6-) using
80 mg (0.069 mmol). Yield: 74 mg (0.063 mmol, 93%). 1H NMR
3
(400 MHz, CD2Cl2, 298 K): δ 10.81 (d, JHH ) 7.5 Hz, 1H,
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(carbonyl)(ethylbut-2-(E)-enoat-2-yl)irid-
ium(III) Hexafluoroantimonate [19 (SbF6-)]. The complex
18b (SbF6-, 30 mg, 0.024 mmol) was dissolved in CH2Cl2 (6
mL), and CO (1 atm) was bubbled through the solution for 1
h. Diethyl ether (15 mL) was then added to this solution to
give a light yellow precipitate, which was filtered, washed with
diethyl ether (2 × 10 mL), and dried in vacuo. Yield: 30 mg
(0.023 mmol, 99%). 1H NMR (500 MHz, CD2Cl2, 295 K): δ
IrCHdCH), 7.42-7.52 (m, 7H), 7.30-7.38 (m, 14H), 7.18-7.26
3
(m, 12H), 7.09 (d, JHH ) 7.5 Hz, 2H, Ph), 6.59 (s, 1H,
3
3
iridafuran CH), 6.47 (d, JHH ) 7.5 Hz, JPH ) 1.2 Hz, 1H,
5
5
IrCHdCH), 1.42 (t, JPH ) 2.0 Hz, CH3), 1.29 (t, JPH ) 2.0
Hz, CH3). 13C{1H} NMR (125.8 MHz, CD2Cl2, 298 K): δ 213.6
(s, CO), 213.4 (s, CO), 203.4 (t, JPC ) 5.8 Hz, IrCPh), 198.1 (t,
JPC ) 6.0 Hz, IrCH), 147.6 (s), 139.0 (s), 137.9 (s), 135.6 (t,
JPC ) 5.1 Hz, PPh3), 132.2 (s, PPh3), 130.7 (s), 129.5 (s), 128.9
(t, JPC ) 5.2 Hz, PPh3), 128.0 (s), 125.8 (t, JPC ) 30.2 Hz, ipso-
PPh3), 25.0 (s, Me), 24.6 9 (s, Me). 31P{1H} NMR (161.9 MHz,
CD2Cl2, 298 K): δ 10.44 (s). Anal. Calcd for C50H44F6IrO2P2-
Sb: C, 51.47; H, 3.80. Found: C, 51.39; H, 3.72.
3
7.32-7.60 (m, 33H), 7.20 (t, JHH ) 7.6 Hz, 2H), 7.10-7.15
(m, 3H), 6.84 (s, 1H), 6.30-6.35 (m, 2H), 5.73 (s, 1H), 3.66 (q,
3
3JHH ) 7.2 Hz, 2H), 1.52 (s, 3H), 0.76 (t, JHH ) 7.2 Hz, 3H).
13C NMR (125 MHz, CD2Cl2, 295 K): δ 219.1 (t, JPC ) 9.0 Hz,
ridafuran Ir-C), 215.8 (s), 176.2 (s), 172.5 (t, JPC ) 8.6 Hz, Ir-
CO), 151.4 (s), 143.9 (s), 143.4 (s), 140.1 (s), 135.7(t, JPC ) 5.8
Hz, PPh3) 132.8 (s), 132.0 (s), 131.4 (s), 129.4 (t, JPC ) 5.8 Hz,
PPh3), 128.4 (s), 128.2 (s), 127.6 (t, JPC ) 27.8 Hz, ipso-PPh3),
127.5 (s), 107.1 (t, JPC ) 7.0 Hz, Ir-C), 61.9 (s), 25.8 (s), 13.7
(s). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ -7.4 (s) IR
(cm-1): 2063 (νCO, IrCO), 1679 (νCO, ester). Anal. Calcd for
C58H50F6IrO4P2Sb: C, 53.55; H, 3.87. Found: C, 53.47; H, 4.12.
Structure Determination of 12a‚acetone, 15a, and 18a‚
Et2O. Crystals of 12a was obtained by layering its acetone
solution with pentane. Crystals of 15a and 18a were obtained
by slow diffusion of Et2O into their CH2Cl2 solutions. Suitable
crystals were selected and mounted on thin glass fibers using
epoxy cement and cooled to data collection temperature. All
measurements were made on a Nonius KappaCCD diffracto-
meter with graphite-monochromated Mo KR radiation, and
intensity data were collected by using the ω-scan mode. The
data were corrected for Lorentz and polarization effects, and
no absorption correction was applied. The structures were
solved by direct methods and refined by full-matrix least-
trans-Bis(triphenylphosphine)(η2-{O,C1}-1-phenylbut-
1-en-3-on-1-yl)(η2-{O,C2}-ethylbut-2-enoat-2-yl)iridium-
(III) Hexafluoantimonate [17 (SbF6-)]. To a stirred solution
of 1 (SbF6-, 85 mg, 0.073 mmol) in CH2Cl2 (5 mL) was added
Me-CtCCO2Et (21 mg, 0.19 mmol). The solution was refluxed
for 5 h, followed by concentration to ca. 0.5 mL. A yellow
precipitate appeared upon addition of diethyl ether (10 mL).
Analytically pure 17 was obtained by recrystallization using
CH2Cl2 and diethyl ether. Yield: 62 mg (0.051 mmol, 70%).
1H NMR (500 MHz, CD2Cl2, 295 K): δ 7.53 (t, 3JHH ) 6.8 Hz,
3
6H), 7.30-7.45 (m, 26H), 7.15 (t, JHH ) 7.9 Hz, 2H), 6.71 (d,
3
3JHH ) 7.2 Hz, 2H), 6.36 (s, 1H), 5.76 (s, 1H), 3.34 (q, JHH
)
7.3 Hz, 2H), 1.75 (s, 3H), 1.50 (t, JPH ) 1.6 Hz, 3H), 0.81 (t,
3JHH ) 7.0 Hz, 3H). 13C NMR (125 MHz, CD2Cl2, 295 K): δ
212.2 (s), 203.6 (t, JPC ) 6.5 Hz, iridafuran Ir-C), 191.2 (t, JPC
) 7.7 Hz, iridafuran Ir-C), 183.1 (s), 149.2 (s), 141.2 (s), 135.3
(t, JPC ) 4.8 Hz, PPh3), 132.0 (s), 129.5 (s), 128.8 (t, JPC ) 4.4
Hz, PPh3), 128.5 (s), 127.4 (s), 125.7 (t, JPC ) 26.8 Hz, ipso-
PPh3), 125.2 (s), 63.5 (s), 33.7 (s), 24.6 (s), 15.7 (s), 14.1 (s),
10.8 (s). 31P{1H} NMR (161.9 MHz, CD2Cl2, 298 K): δ 4.93

76 Organometallics, Vol. 24, No. 1, 2005
Li et al.
squares techniques. The non-hydrogen atoms were refined
anisotropically, and hydrogen atoms were treated as idealized
contributions.
Complex 12a cocrystallized with one molecule of acetone
that possesses a high degree of thermal motion. To counter
the effect of inflated thermal parameters, the carbon-carbon
and carbon-oxygen bonds were fixed at ideal lengths and non-
hydrogen atoms were refined isotropically.
Complex 15a crystallized in the C-centered monoclinic space
group C2 with one molecule in the asymmetric unit and four
molecules in the unit cell. In the asymmetric unit, the
hexafluorantimonate counterion resides on a 2-fold axis of
rotation, resulting in two crystallographically independent
Sb0.5F3 fragments. While one fragment is well ordered, the
second is plagued with positional disorder. Alternative sites
(50:50) were modeled for each of the fluorine atoms, and both
components of the disorder were refined with anisotropic
displacement parameters.
Within the 245.5 Å3 unit cell void space occupied by solvent
molecules, a total of 84 electrons were calculated, compared
to 84 electrons for the two molecules of solvent. In this
treatment of solvent, the contributions of the solvent molecules
are collective and not as individual atoms. Hence, the atom
list (see Supporting Information) does not contain the atoms
-
of the solvent molecules. For 18a, the BF4 counterion is
plagued with positional disorder. Alternative sites for F(2-4)
were effectively modeled with occupancy factor ratios of 50:
50. All boron and fluorine atoms were refined with anisotropic
displacement parameters, and the B-F bonds were restrained
to ideal distances for ease of refinement.
Acknowledgment. Generous financial support from
the U.S. Department of Energy and the Johnson Mat-
they Company is greatly acknowledged.
Supporting Information Available: Detailed X-ray crys-
tallographic data of atomic positional parameters, bond dis-
tances and angles, and anisotropic thermal parameters (PDF
and CIF) for 12a, 15a, and 18a. This material is available free
of charge via the Internet at http://pubs.acs.org.
Complex 18a cocrystallized with diethyl ether in a ratio of
1:1. Squeeze/Platon25 was applied to resolve one molecule of
severely disordered diethyl ether within the asymmetric unit.
(25) Spek, A. L. Acta Crystallogr. 1990, A46, C34.
OM049271Z