Reactions of cyclometalated oxazoline half-sandwich complexes of iridium and ruthenium with alkynes and CO

Article abstract of DOI:10.1021/om901088v

The ligand 4,4-dimethyl-2-oxazolinylbenzene is easily cyclometalated by [IrCl₂Cp]₂ or [RuCl(MeCN)₂(p-cymene)]PF ₆ in the presence of sodium, acetate. In the case of iridium, the resultant complex dissolves in ac

Full text of DOI:10.1021/om901088v

Organometallics 2010, 29, 1413–1420 1413
DOI: 10.1021/om901088v
Reactions of Cyclometalated Oxazoline Half-Sandwich Complexes of
Iridium and Ruthenium with Alkynes and CO
David L. Davies,* Omar Al-Duaij, John Fawcett, and Kuldip Singh
Department of Chemistry, University of Leicester, Leicester, LE1 7RH U.K.
Received December 18, 2009
The ligand 4,4-dimethyl-2-oxazolinylbenzene is easily cyclometalated by [IrCl2Cp*]2 or [RuCl-
(MeCN)2(p-cymene)]PF6 in the presence of sodium acetate. In the case of iridium the resultant
complex dissolves in acetonitrile in the presence of KPF6 to give an acetonitrile-coordinated cationic
complex. The analogous complex is formed directly in the ruthenium cyclometalation reaction. These
labile cationic complexes undergo insertion reactions with internal and terminal alkynes. Internal
alkynes give only monoinsertion products, whereas terminal alkynes give mono- or di-insertion
products. The cations will also react with CO, but no insertion occurs in this case.
Introduction
complexes with alkynes are important to understand selec-
tivity and reactivity issues in the catalytic processes.
Cyclometalated complexes have been known for a long
time and have proven to be useful in organic synthesis and as
catalysts or catalyst precursors.1 However, much of the early
work involved the use of stoichiometric amounts of the
transition metal or required halogenated precursors to form
the M-C bond, neither of which is desirable from a financial
or atom-economic perspective. In recent years there has been
substantial progress in catalytic C-H bond activation and
subsequent C-C bond formation, which potentially pro-
vides a much cheaper and atom-economic methodology.2
One of the most general strategies involves regioselective
C-H functionalization dependent on coordination of an
adjacent functional group; metalation of an ortho C-H
bond of a substituted phenyl to form a five-membered ring
is particularly common. Coupling a C-H bond activation
step with an alkyne insertion into the cyclometalated M-C
bond and subsequent reductive elimination is a potential
route to heterocyclic products (Scheme 1). In this regard
studies of the stoichiometric reactions of cyclometalated
Stoichiometric reactions of alkynes with cyclopalladated
complexes have been widely studied and have found applica-
tion in the sythesis of heterocyclic molecules.3-5 The reac-
tivity of half-sandwich cyclometalated complexes with
unsaturated substrates is, however, comparatively little stu-
died, possibly due to a lack of general routes to such
complexes (see below). Early work by Pfeffer et al. showed
that arene ruthenium cyclometalated complexes [RuCl-
(DMBA)(arene)] (DMBAH = dimethylbenzylamine) would
react with alkynes to form coordinated isoquinolinium salts,
which could be liberated from the metal using copper salts as
oxidants.6-8 Recently Jones et al. have shown that related
Cp*Rh and Cp*Ir cyclometalated phenylpyridine complexes
undergo alkyne insertion and generate isoquinolinium salts
at room temperature after oxidative coupling with CuCl2.9
Miura and co-workers have recently reported a number of
catalytic reactions to form heterocycles in which they pro-
pose that cyclometalation at Cp*Rh followed by alkyne
insertion into the M-C bond are important steps in the
catalytic cycle.10 A similar sequence is likely involved in
*Corresponding author. E-mail: dld3@le.ac.uk.
(4) Spencer, J.; Pfeffer, M.; Kyritsakas, N.; Fischer, J. Organometal-
lics 1995, 14, 2214.
(5) Maassarani, F.; Pfeffer, M.; Leborgne, G. Organometallics 1987,
6, 2029.
(6) Pfeffer, M.; Sutter, J. P.; Urriolabeitia, E. P. Bull. Soc. Chim. Fr.
(1) For general reviews of cyclometalated complexes see: (a) Pfeffer,
M. Pure Appl. Chem. 1992, 64, 335. (b) Omae, I. Coord. Chem. Rev. 2004,
248, 995. For cyclopalladated complexes see for example: (c) Ryabov, A. D.
Synthesis 1985, 233. (d) Dupont, J.; Pfeffer, M.; Spencer, J. Eur. J. Inorg.
Chem. 2001, 1917. (e) Bedford, R. B. Chem. Commun. 2003, 1787.
(f) Dupont, J.; Consorti, C. S.; Spencer, J. Chem. Rev. 2005, 105, 2527.
For a recent review of cycloruthenated complexes see: (g) Djukic, J. P.;
Sortais, J. B.; Barloy, L.; Pfeffer, M. Eur. J. Inorg. Chem. 2009, 817.
(2) (a) Alberico, D.; Scott, M. E.; Lautens, M. Chem. Rev. 2007, 107,
174. (b) Kakiuchi, F.; Kochi, T. Synthesis 2008, 3013. (c) Lewis, J. C.;
Bergman, R. G.; Ellman, J. A. Acc. Chem. Res. 2008, 41, 1013. (d) Satoh, T.;
Miura, M. Chem. Lett. 2007, 36, 200. (e) Dyker, G., Ed. Handbook of C-H
Transformations; Wiley-VCH: Weinheim, 2005.
(3) (a) Spencer, J.; Pfeffer, M.; Decian, A.; Fischer, J. J. Org. Chem.
1995, 60, 1005. (b) Maassarani, F.; Pfeffer, M.; Spencer, J.; Wehman, E.
J. Organomet. Chem. 1994, 466, 265. (c) Beydoun, N.; Pfeffer, M.; Decian,
A.; Fischer, J. Organometallics 1991, 10, 3693. (d) Wu, G.; Rheingold, A. L.;
Geib, S. J.; Heck, R. F. Organometallics 1987, 6, 1941. (e) Wu, G. Z.;
Rheingold, A. L.; Heck, R. F. Organometallics 1986, 5, 1922. (f) Wu, G. Z.;
Geib, S. J.; Rheingold, A. L.; Heck, R. F. J. Org. Chem. 1988, 53, 3238.
1997, 134, 947.
(7) Abbenhuis, H. C. L.; Pfeffer, M.; Sutter, J.-P.; de Cian, A.;
Fischer, J.; Ji, H. L.; Nelson, J. H. Organometallics 1993, 12, 4464.
(8) Ferstl, W.; Sakodinskaya, I. K.; Beydoun-Sutter, N.; LeBorgne,
G.; Pfeffer, M.; Ryabov, A. D. Organometallics 1997, 16, 411.
(9) Li, L.; Brennessel, W. W.; Jones, W. D. J. Am. Chem. Soc. 2008,
130, 12414.
(10) (a) Fukutani, T.; Umeda, N.; Hirano, K.; Satoh, T.; Miura, M.
Chem. Commun. 2009, 5141. (b) Kokubo, K.; Matsumasa, K.; Nishinaka, Y.;
Miura, M.; Nomura, M. Bull. Chem. Soc. Jpn. 1999, 72, 303. (c) Mochida,
S.; Hirano, K.; Satoh, T.; Miura, M. J. Org. Chem. 2009, 74, 6295.
(d) Shimizu, M.; Hirano, K.; Satoh, T.; Miura, M. J. Org. Chem. 2009, 74,
3478. (e) Shimizu, M.; Tsurugi, H.; Satoh, T.; Miura, M. Chem.-Asian J.
2008, 3, 881. (f) Ueura, K.; Satoh, T.; Miura, M. Org. Lett. 2007, 9, 1407.
(g) Ueura, K.; Satoh, T.; Miura, M. J. Org. Chem. 2007, 72, 5362. (h) Umeda,
N.; Tsurugi, H.; Satoh, T.; Miura, M. Angew. Chem., Int. Ed. 2008, 47, 4019.
r
2010 American Chemical Society
Published on Web 02/24/2010
pubs.acs.org/Organometallics

1414 Organometallics, Vol. 29, No. 6, 2010
Davies et al.
Scheme 1. Possible Catalytic Cycle for the Production of
Heterocycles via C-H Activation and Alkyne Insertion
Cp*Rh-catalyzed synthesis of indoles11 and isoquinolines12
reported by Fagnou. In the latter case Fagnou provided
evidence to suggest that, in some cases at least, C-N reductive
elimination can occur before oxidation by copper salts.12
In 2003 we reported a new route to half-sandwich (Cp*M,
M = Rh, Ir, or {p-cymene}Ru) cyclometalated complexes
via an acetate-assisted C-H activation.13 Subsequent studies
by us14 and others15 have shown that these are ambiphilic
metal ligand activations (AMLA),16 involving an electro-
philic metal center with assistance by hydrogen bonding to
the free arm of a coordinated acetate. Having discovered a
facile high-yield route to a range of half-sandwich cyclome-
talated complexes, we now disclose some of our results on the
reactivity of cyclometalated oxazolines with alkynes that are
relevant to the catalytic formation of heterocycles reported
by Miura10 and Fagnou.11,12
Figure 1. Molecular structure and atom-numbering scheme for
the cation of 2a with 50% displacement ellipsoids. AllH atoms are
˚
omitted for clarity. Selected bond distances (A) and angles (deg):
Ir-N(1) 2.118(3), Ir-N(2) 2.050(3), Ir-C(1) 2.068(3), Ir-C(14)
2.153(3), Ir-C(15) 2.173(3), Ir-C(16) 2.167(4), Ir-C(17)
2.170(3), Ir-C(18) 2.240(3), Ir-C(22) 2.168(6), C(1);Ir-N(1)
77.08(12), C(1);Ir-N(2) 88.62(12), N(1);Ir-N(2) 82.85(11).
The 1H NMR spectrum of 2a shows four multiplets in the
aromatic region as expected; however, the oxazoline methyls
give riseto a broad singlet at δ 1.47, whiletheCH2 protons are
observed as a sharp singlet at δ 4.58 and coordinated NCMe
gives a broad singlet at δ 2.42, 0.42 ppm downfield from
free NCMe. The equivalence of the CMe2 and of the CH2
protons suggests that the complex is fluxional on the NMR
time scale via dissociation of MeCN accompanied by epimeri-
zation at the metal center; such a process has been observed
previously for [Ru(MeCN)(DMBA)(arene)]þ.17 The 1H
NMR spectrum at 273 K showed two sharp singlets at δ
1.44 and 1.54 for the CMe2 protons and the broad singlet due
to NCMe resolved into two singlets at δ 2.42 (coordinated
NCMe) and 2.02 (free NCMe) (10:1 ratio), the latter obser-
vation consistent with exchange of free and coordinated
NCMe being slow at this temperature. Further cooling to
233 K led to resolution of the CH2 signal to two mutually
coupled doublets at δ 4.40 and 4.70; hence, at this tempera-
ture epimerization is slow compared to the NMR time scale.
The structure of 2a has been determined by X-ray crystal-
lography and is shown in Figure 1, with selected bond
distances and angles. The complex adopts the expected
pseudo-octahedral structure and confirms the coordina-
tion of NCMe. The chelate bite angle C(1)-Ir(1)-N(1)
[77.08(12)°] is similar to that [78.0(2)°] in the related [IrCl-
(Phpy)Cp*]9,18 (PhpyH = 2-phenylpyridine). The M-N(1)
Results and Discussion
Complex 1a was reacted with PhCtCPh in MeCN in the
presence of excess KPF6. Monitoring the reaction by electro-
spray mass spectrometry showed that even after 72 h the
reaction had not gone to completion. It is possible that MeCN
competes with PhCtCPh to replace the chloride in 1a. The
reaction is considerably slower than alkyne insertions observed
by Pfeffer6,7 and Jones9 for related species when the reactions
were conducted in methanol. It is known that alkyne insertions
into cyclopalladated complexes are more efficient if the initial
complex is cationic.5 Hence we prepared the cationic MeCN
complex 2a by reaction of 1a with KPF6.
˚
˚
bond length [2.118(3) A] is longer than M-N(2) [2.050(3) A],
consistent with a bond to an sp2 rather than an sp-hybridized
nitrogen. As found for other cyclometalated Cp*Rh/Ir
complexes, the Cp* is bonded in an asymmetric fashion with
(11) Stuart, D. R.; Bertrand-Laperle, M.; Burgess, K. M. N.; Fagnou,
K. J. Am. Chem. Soc. 2008, 130, 16474.
(12) Guimond, N.; Fagnou, K. J. Am. Chem. Soc. 2009, 131, 12050.
(13) Davies, D. L.; Al-Duaij, O.; Fawcett, J.; Giardiello, M.; Hilton,
S. T.; Russell, D. R. Dalton Trans. 2003, 4132.
(14) (a) Davies, D. L.; Donald, S. M. A.; Al-Duaij, O.; Macgregor,
S. A.; Polleth, M. J. Am. Chem. Soc. 2006, 128, 4210. (b) Boutadla, Y.;
Davies, D. L.; Macgregor, S. A.; Poblador-Bahamonde, A. I. Dalton Trans.
2009, 5887.
(15) Li, L.; Brennessel, W. W.; Jones, W. D. Organometallics 2009, 28,
3492.
(16) Boutadla, Y.; Davies, D. L.; Macgregor, S. A.; Poblador-
˚
three shorter Ir-C distances (ca. 2.16 A) and two longer
Ir-C distances (ca. 2.25 A).
13,18,19
˚
(17) Robitzer, M.; Ritleng, V.; Sirlin, C.; Dedieu, A.; Pfeffer, M. C. R.
Chim. 2002, 5, 467.
(18) Boutadla, Y.; Al-Duaij, O.; Davies, D. L.; Griffith, G. A.; Singh,
K. Organometallics 2009, 28, 433.
(19) Scheeren, C.; Maasarani, F.; Hijazi, A.; Djukic, J. P.; Pfeffer, M.;
Zaric, S. D.; LeGoff, X. F.; Ricard, L. Organometallics 2007, 26, 3336.
Bahamonde, A. I. Dalton Trans. 2009, 5820.

Article
We have previously reported that acetate-assisted cyclo-
Organometallics, Vol. 29, No. 6, 2010 1415
metalation of oxazolines with [RuCl2(p-cymene)]2 failed.13
However, we can now report that if the reaction is carried out
in acetonitrile at 45 °C starting from [RuCl(MeCN)2(p-
cymene)][PF6], then the reaction works, providing acetoni-
trile complex 2b. This process is similar to that used pre-
viously by Pfeffer et al. for cyclometalation of benzylamines
except that NaOH was used as base in those cases.20 The 1H
NMR spectrum of 2b shows appropriate signals for the
cyclometalated oxazoline, namely, four multiplets in the
aromatic region, two singlets at δ 1.47 and 1.57 due to
the methyls, and a singlet for the CH2 protons, which are
accidentally equivalent, at δ 4.50. The p-cymene shows the
expected signals for a chiral complex, and the coordinated
NCMe gives a broad singlet at δ 2.21, 0.2 ppm downfield
from free NCMe. The inequivalence of the oxazoline methyls
and of the p-cymene protons suggests that, unlike 2a dis-
cussed above, the rate of epimerization of 2b is slow on the
NMR time scale. It is known that ligand substitution is much
slower for arene ruthenium complexes than the correspond-
ing Cp*Ir ones.21
Having prepared cationic cyclometalated species 2a,b,
containing labile MeCN ligands, these complexes were then
reacted with alkynes. Reaction of 2a with PhCtCPh oc-
curred within a few hours ar room temperature in dichlor-
omethane to give monoinsertion product 3a. The 1H NMR
spectrum of 3a shows signals due to the Cp*, the oxazoline
ligand, and PhCtCPh in a 1:1:1 ratio. The CMe2 group gives
rise to two singlets at δ 1.31 and 1.37; the CH2 protons are
also inequivalent, giving two mutually coupled doublets at δ
4.27 and 4.58. The inequivalence of the CH2 protons and the
methyls of the CMe2 group is consistent with the metal center
being chiral and shows that epimerization at the metal is slow
on the NMR time scale. A singlet integrating to 3H at δ 2.00
is assigned to NCMe protons. This signal and that for the
Cp* are both upfield (0.42 and 0.48 ppm, respectively) of the
corresponding signals in 2a, suggesting they are affected by
the presence of ring currents. The NOESY spectrum shows
cross-peaks between the signals for Cp* and the doublets for
H3 and H6, confirming that the Cp* lies over the original
cyclometalated phenyl (see X-ray structure of 3b below).
Similar upfield shifts of Cp* resonances have been observed
for benzene bis(oxazoline) complexes, which have a similar
seven-membered chelate ring.22
Figure 2. Molecular structure and atom-numbering scheme for
the cation of 3b with 50% displacement ellipsoids. All H atoms
are omitted for clarity. The iPr and Me groups of the p-cymene
˚
are disordered. Selected bond distances (A) and angles (deg):
Ru-C(17) 2.095(4), Ru-N(1) 2.123(3), Ru-N(2) 2.053(3), C-
(17)-C(10) 1.336(6); C(17)-Ru-N(1) 81.50(13), C(17)-Ru-
N(2) 88.73(16), N(1)-Ru-N(2) 89.80(13).
as found by Pfeffer,7 not into the M-N bond.23 The FAB
mass spectrum of 3a shows an ion at m/z 679 due to [M -
NCMe]þ, confirming the presence of PhCtCPh.
Ruthenium complex 3b was obtained similarly from the
reaction of 2b with PhCtCPh in CH2Cl2 but required a
longer reaction time (24 h), consistent with the slower rate of
substitution at arene ruthenium compared with Cp*Ir.21 The
1H NMR spectrum of the crude product showed more than
one Ru(p-cymene) complex; however, after filtration
through silica only one product, 3b, remained. The 1H
NMR spectrum of 3b is similar to that of 3a with signals
for the p-cymene replacing the Cp*. As found in 3a, the
NCMe protons in 3b are strongly shielded at δ 1.78, 0.43 ppm
upfield from 2b; the four multiplets of the p-cymene are also
shifted 0.5-0.8 ppm upfield from 2b. The CMe2 group gives
rise to two singlets at δ 1.09 and 1.59, and the CH2 protons
are also inequivalent, giving two mutually coupled doublets
at δ 4.34 and 4.47. These observations confirm that epimeri-
zation at the metal is slow on the NMR time scale.
Recrystallization from dichloromethane/hexane gave
X-ray quality crystals of 3b. The crystal structure is shown
in Figure 2, with selected bond distances and angles. The
complex adopts the expected pseudo-octahedral structure
and confirms that the alkyne has, as expected, inserted into
the M-C bond rather than the M-N bond,23 with forma-
tion of a seven-membered ring. The C(17)-Ru(1)-N(1)
chelate bite angle of the seven-membered ring [81.50(13)o]
is larger than that [77.08(12)o] in the five-membered ring of
2a. The oxazoline ring is rotated out of the plane of the
phenyl [C(4)-C(9)] with a dihedral angle [N(1)-C(3)-
C(4)-C(9)] of 52.8°, which is much larger than the corre-
sponding angle (4.5°) in 2a. Presumably, this occurs as a
consequence of the expansion in ring size. Similar tilting of
the oxazoline ring is seen in benzene bisoxazoline complexes
with a seven-membered ring.22 The structure also shows that
The 13C{1H} NMR spectrum shows the expected signals
with the original cyclometalated carbon now being observed
at ca. δ 146, about 33 ppm upfield compared with 2a, a large
shift, consistent with insertion of alkyne into the M-C bond,
(20) Fernandez, S.; Pfeffer, M.; Ritleng, V.; Sirlin, C. Organometallics
1999, 18, 2390.
(21) Dadci, L.; Elias, H.; Frey, U.; Hornig, A.; Koelle, U.; Merbach,
A. E.; Paulus, H.; Schneider, J. S. Inorg. Chem. 1995, 34, 306.
(22) Davies, D. L.; Fawcett, J.; Garratt, S. A.; Russell, D. R.
Organometallics 2001, 20, 3029.
(23) Cabeza, J. A.; del Rio, I.; Grepioni, F.; Moreno, M.; Riera, V.;
Suarez, M. Organometallics 2001, 20, 4190.

1416 Organometallics, Vol. 29, No. 6, 2010
Davies et al.
the NCMe lies in the region of the ring current of the phenyl
[C(18)-C(23)] and the p-cymene is tilted to lie over the ring
[C(4)-C(9)]. These features account for the high-field shifts
observed in the 1H NMR spectrum of 3b (see above). Similar
features are expected for 3a.
In the course of our preliminary studies of the reaction of
PhCtCH with the chloride complex 1a even when only one
equivalent of alkyne was used, the ES mass spectrum often
showed ions due to a mixture of products corresponding to
insertion of one or two equivalents of alkyne, suggesting that
insertion of a second molecule of PhCtCH occurred at a
similar rate to the first insertion. To try to overcome these
difficulties, we again started from the acetonitrile complex
2a. Reaction of PhCtCH with 2a in 1:1 ratio in CH2Cl2 led
to formation of a monoinsertion complex, 5a, in 86% yield
after 1 h. The 1H NMR spectrum of the product showed only
one isomer was present. The signal for the coordinated
NCMe was observed at δ 1.99, more than 0.4 ppm upfield
from the corresponding signal in 2a, consistent with a ring
current from an adjacent phenyl, as discussed previously for
3a. This suggests that the phenyl of PhCtCH is adjacent to
iridium and the product is 5a rather than 5a0 (confirmed by
X-ray crystallography; see below). Unfortunately the signal
for the alkyne proton is underneath signals for the alkyne
phenyl, so NOE effects could not be used to corroborate the
assignment of which regioisomer was formed. The CMe2
group gave two singlets at δ 1.14 and 1.29, and the OCH2
protons were observed as two mutually coupled doublets at δ
4.11 and 4.42. The inequivalence of the CH2 protons and of
the methyls of the CMe2 group is consistent with the chiral
center at the metal and that epimerization at the metal is slow
on the NMR time scale. The 13C{1H} NMR spectrum of 5a
shows the expected signals. FAB mass spectrometry showed
only a peak at m/z 602 [M - NCMe]þ corresponding to
monoinsertion of PhCtCH.
To assess the regioselectivity of the alkyne insertion,
reaction of 2a with PhCtCCO2Et was investigated. The
1H NMR spectrum of the crude product showed only one
species. A singlet at δ 2.77 assigned to a coordinated NCMe
is at much lower field than in 3a (δ 2.00), suggesting that it is
not affected by a ring current of an adjacent phenyl, con-
sistent with phenyl being on the carbon atom adjacent to the
phenyl oxazoline, i.e., isomer 4a. The Cp* is observed at δ
1.41, 0.4 ppm upfield from 2a, consistent with a ring-current
effect from the originally cyclometalated phenyl. The CMe2
group gives rise to two sharp singlets at δ 1.31 and 1.46, with
the OCH2 protons being observed as two doublets at δ 4.23
and 4.53; the inequivalence is consistent with epimerization
at the metal being slow on the NMR time scale. Two multi-
plets are observed at δ 1.38 and 3.79, assigned to the CO2Et
protons. The 13C{1H} NMR spectrum shows the expected
number of carbon signals, and the FAB mass spectrum
shows an ion at m/z 676 due to [M - NCMe]þ. The IR
spectrum shows ν(CdN) at 1624 cm-1, similar to that in the
starting cationic complex with ν(CdO) at 1695 cm-1, con-
firming the presence of PhCtCCO2Et. The spectroscopic
data are consistent with isomer 4a; that is, the insertion
occurs such that the ester group is found on the carbon atom
adjacent to the metal, with the phenyl group being on the
carbon atom adjacent to the phenyl oxazoline. The regios-
electivity is the same as that found by Pfeffer for reaction of
this alkyne with [RuCl(DMBA)(C6H6)],6 which is oppposite
that usually observed for insertion into the M-C bond of
palladium complexes4,5,24 and nickel complexes.25 The re-
gioselectivity of insertion of this alkyne has also been studied
experimentally and computationally, and the regioselectivity
was found to depend on the exact palladium precursor used;
more electrophilic palladium species, particularly cationic
ones, favored insertion with the ester next to the metal.26
It is notable that in most studies involving catalytic reac-
tions of alkynes with cyclometalated intermediates there are
relatively few examples that involve terminal alkynes,27 and
the first example in which the cyclometalated intermediate is
generated by C-H activation was only reported in 2008.28
This may be due to the greater reactivity of terminal alkynes
leading to polymerization reactions and/or the possibility of
forming vinylidene complexes. Similarly to our knowledge
the only example of a stoichiometric reaction of a half-
sandwich cyclometalated complex with a terminal alkyne is
that of [CoI(DMBA)(Cp)],29 which reacts only with terminal
alkynes. Hence, we thought it would be informative to test
the reaction of 2a,b with PhCtCH.
The corresponding reaction was also attempted with the
cycloruthenated complex 2b. The 1H NMR spectrum of the
crude product showed a mixture of species; however after
filtration through silica only one product was isolated. The
1H NMR spectrum is similar to that of 5a but with signals
due to the p-cymene in place of the Cp*. Notably the signal
for coordinated NCMe is observed at δ 1.85, 0.36 ppm
upfield from that in 2b, consistent with the phenyl of the
alkyne being next to ruthenium, and the product is 5b not 5b0.
Unfortunately, as for 5a, due to the overlap of signals NOE
effects could not be used to corroborate the assignment of
(24) Pfeffer, M.; Rotteveel, M. A.; Le Borgne, G.; Fischer, J. J. Org.
Chem. 2002, 57, 2147.
(25) (a) Bennett, M. A.; Macgregor, S. A.; Wenger, E. Helv. Chim.
Acta 2001, 84, 3084. (b) Edwards, A. J.; Macgregor, S. A.; Rae, A. D.;
Wenger, E.; Willis, A. C. Organometallics 2001, 20, 2864.
(26) Kelly, A. E.; Macgregor, S. A.; Willis, A. C.; Nelson, J. H.;
Wenger, E. Inorg. Chim. Acta 2003, 352, 79.
(27) (a) Korivi, R. P.; Cheng, C.-H. Org. Lett. 2005, 7, 5179.
(b) Korivi, R. P.; Wu, Y.-C.; Cheng, C.-H. Chem.;Eur. J. 2009, 15, 10727.
(28) Chuan-Che, L.; Rajendra Prasad, K.; Chien-Hong, C. Chem.;
Eur. J. 2008, 14, 9503.
(29) Meneghetti, M. R.; Grellier, M.; Pfeffer, M.; Fischer, J. Orga-
nometallics 2000, 19, 1935.

Article
Organometallics, Vol. 29, No. 6, 2010 1417
Figure 4. Molecular structure and atom-numbering scheme for
the cation of 5b with 50% displacement ellipsoids. All H atoms
˚
are omitted for clarity. Selected bond distances (A) and angles
(deg): Ru-C(11) 2.097(3), Ru-N(1) 2.094(2), Ru-N(2)
2.059(2), C(10)-C(11) 1.347(4); C(11)-Ru-N(1) 83.49(10),
C(11)-Ru-N(2) 86.53(7), N(1)-Ru-N(2) 86.14(10).
Figure 3. Molecular structure and atom-numbering scheme for
the cation of 5a with 50% displacement ellipsoids. All H atoms
˚
are omitted for clarity. Selected bond distances (A) and angles
(deg): Ir-N(1) 2.095(4), Ir-N(2) 2.058(6), Ir-C(11) 2.079(5),
Ir-C(18) 2.234(6), Ir-C(19) 2.247(6), Ir-C(20) 2.171(5), Ir-C-
(20) 2.171(5), Ir-C(21) 2.169(6), Ir-C(22) 2.168(6), C(10)-C-
(11) 1.331(8); C(11)-Ir-N(1) 81.7(2), C(11)-Ir-N(2) 85.92(9),
N(1)-Ir-N(2) 86.3(2).
on the NMR time scale. Two multiplets at δ 1.27 and 4.11 are
assigned to the CO2Et protons, and the original alkyne
proton (H7) is observed as a singlet at δ 7.48. A NOESY
spectrum showed that (H7) is adjacent to (H6), confirming
that the insertion occurs with the CO2Et ending up on the
carbon atom adjacent to the metal. The 13C{1H} NMR
spectrum showed the expected number of carbon signals,
and the FAB mass spectrum showed an ion at m/z 600 due to
which regioisomer was formed. The 13C{1H} NMR spec-
trum showed the expected signals, and the FAB mass
spectrum showed an ion at m/z 512 due to [M - NCMe]þ,
confirming insertion of PhCtCH.
Careful recrystallization of 5a and 5b from dichloro-
methane/ether gave crystals suitable for X-ray diffraction,
and the structures are shown in Figures 3 and 4, respectively,
with selected distances and angles. Each complex adopts the
expected pseudo-octahedral structure and shows that the
alkyne has inserted into the M-C bond to form a seven-
membered ring. In both cases the phenyl of the alkyne is on
the carbon attached to the metal. The bond lengths and
angles are similar in both complexes. In 5b the Ru-C(11)
[M- NCMe]þ. The IR spectrum showed ν(CdN) at 1622 cm-1
,
similar to that in the starting complex 2a, and ν(CdO) at
1682 cm-1, confirming the incorporation of HCtCCO2Et.
Pfeffer previously suggested that the regioselectivity of al-
kyne insertion with [RuCl(DMBA)(arene)] depends mainly
on steric factors.6,7 However, the fact that the regioselectivity
we observe for HCtCCO2Et is the same as that for
PhCtCCO2Et suggests that at least in these cases, with an
alkyne containing one very electron-withdrawing substitu-
ent, electronic factors are also important.
Having observed clean insertion reactions with one
equivalent of PhCtCH, the reaction of 2a with two equiva-
lents of PhCtCH was attempted. Monitoring the reaction
by electrospray mass spectrometry suggested that the reac-
tion was complete after two hours The 1H NMR spectrum of
the product showed a 1:1:2 ratio of the Cp*, oxazoline, and
alkyne ligands, as expected for the formation of a di-inser-
tion product. The Cp* signal was observed at δ 1.76,
0.42 ppm downfield compared with the monoinsertion com-
plex 5a, suggesting it is no longer influenced by a ring
current. The CMe2 group gave two singlets at δ 1.18 and
1.37, and the OCH2 protons were observed as two mutually
coupled doublets at δ 2.94 and 4.18. In addition, two singlets
were observed at δ 4.68 and 6.41 due to the original alkyne
protons; there is no sign of a signal for MeCN. The FAB
mass spectrum showed an ion at m/z 704, corresponding to
the di-insertion of PhCtCH with no coordination of MeCN.
Fortunately we were able to obtain suitable crystals of 7a
and have been able to determine its structure by X-ray
crystallography (see Figure 5). The structure shows an
eight-membered metallacycle formed by insertion of two
molecules of PhCtCH into the M-C bond of 5a. The
˚
bond length [2.097(3) A] and the chelate angle N(1)-Ru-
(1)-C(11) [83.49(10)o] are similar to the PhCtCPh insertion
product 3b [2.095(4) A and 81.50(13) , respectively],
o
˚
˚
although the Ru-N(1) bond length [2.094(2) A] is shorter
than that [2.123(3) A] in 3b. As found in 3b, in both 5a and 5b
˚
the oxazoline is rotated out of the plane of the phenyl
C(4)-C(9) (dihedral angle N(1)-C(3)-C(4)-C(9) = 48.4°
and 44.5°, respectively). In 5a, as found in 2a (see above) the
Cp* is bonded in an asymmetric fashion with three shorter
˚
Ir-C distances (ca. 2.17 A) and two longer Ir-C distances
The structures confirm that the NCMe
13,18,19
˚
(ca. 2.24 A).
lies in the region of the ring current of the alkyne phenyl and
that the Cp* and p-cymene lie over the original cyclometa-
lated phenyl ring.
To investigate possible electronic effects on the regioselec-
tivity of the alkyne insertion, HCtCCO2Et was also reacted
1
with 2a. The H NMR spectrum of the reaction mixture
showed only one product, 6a. The 1H NMR spectrum of 6a
shows the signal for coordinated NCMe protons at δ 2.71,
downfield relative to 3a and 5a but similar to 4a, since there is
no phenyl substituent on the alkyne. The CMe2 group shows
two sharp singlets at δ 1.22 and 1.37, with the OCH2 protons
observed as two doublets at δ 4.11 and 4.38, the inequiva-
lence consistent with epimerization at the metal being slow

1418 Organometallics, Vol. 29, No. 6, 2010
Davies et al.
530 and a fragment ion at m/z 502 [M - CO]þ. The ν(CO)
absorption is observed at 2042 cm-1 as expected for a
terminal CO and similar to those (2030 and 2036 cm-1
)
reported for analogous complexes.31 There was no evidence
for any insertion product under these reaction conditions.
In conclusion, we have shown that both internal and
terminal alkynes will insert into half-sandwich cyclometa-
lated phenyl oxazoline complexes. In all cases if only one
equivalent of alkyne is used, then monoinsertion products
can be isolated. The insertion seems to favor the isomer with
the more electron-withdrawing group next to the metal, but
more studies are needed to confirm the generality of this. In
no case does reductive elimination with concomitant C-N
bond formation occur spontaneously, and we have not yet
examined whether oxidizing agents can promote this trans-
formation. The MeCN ligand of 2a is also easily displaced by
CO; however in this case no subsequent insertion is observed.
Experimental Section
Figure 5. Molecular structure and atom-numbering scheme for
the cation of 7a with 50% displacement ellipsoids. All H atoms
˚
are omitted for clarity. Selected bond distances (A) and angles
(deg): Ir-N(1) 2.096(3), Ir-C(10) 2.150(4), Ir-C(11) 2.241(4),
Ir-C(12) 2.093(4), Ir-C(26) 2.228(4), Ir-C(27) 2.250(4), Ir-C-
(28) 2.235(4), Ir-C(29) 2.167(4), Ir-C(30) 2.224(4), C(9)-C-
(10) 1.470(6), C(10)-C(11) 1.449(6), C(11)-C(12) 1.402(6),
C(12)-C(19) 1.323(6), C(10)-Ir-N(1) 87.58(15).
The reactions described were carried out under nitrogen using
dry solvents; however, once isolated as pure solids, the com-
1
pounds can be handled in air. H and 13C{1H} NMR spectra
were obtained using Bruker ARX250 or 300 MHz spectro-
meters, with CDCl3 as solvent, unless otherwise stated. Chemi-
cal shifts were recorded in ppm (with tetramethylsilane as
internal reference). FAB mass spectra were obtained on a
Kratos concept mass spectrometer using NOBA as matrix.
The electrospray (ES) mass spectra were recorded using a
micromass Quattra LC mass spectrometer with dichloro-
methane or methanol as solvent. Infrared spectra were run as
solids in a diamond ATR cell using a Perkin-Elmer Spectrum 1
instrument. Microanalyses were performed by the Elemental
Analysis Service (University of North London). All starting
materials were obtained from Aldrich, with the exception of
[IrCl2Cp*]2,32 [RuCl2(p-cymene)]2,33 complex 1a, and oxazo-
line,34 which were prepared by literature methods.
organic fragment is bonded through the oxazoline nitrogen
and has an η3-interaction with three of the alkyne carbon
atoms; isomerization of the end alkyne unit has occurred to
give a vinylidene. The η3-allyl is bonded asymmetrically with
˚
Ir-C(12) being the shortest bond (2.093(4) A) and Ir-C(11)
being the longest at 2.241(4) A. The phenyl substituent
˚
[C(13)-C(18)] on the central carbon atom of the allyl is
oriented anti with respect to the Cp* on Ir.
Preparation of 2a. A mixture of 1a (70 mg, 0.13 mmol) and
KPF6 (55 mg, 0.30 mmol) in acetonitrile was stirred overnight.
The mixture was filtered through Celite to remove excess KPF6;
the filtrate was evaporated to dryness and was washed with
hexane. The complex was recrystallized from dichloromethane/
hexane, giving 2a as a yellow solid (75 mg, 83.3%). Anal. Calcd
for C23H30IrN2OPF6: C, 40.17, H, 4.40, N, 4.07. Found: C,
40.29, H, 4.37, N, 3.97. 1H NMR: δ 1.47 (br, 6H, 2ꢀMe), 1.80
(s, 15H, Cp*), 2.42 (br, 3H, NCMe), 4.58 (s, 2H, CH2), 7.15 (dt,
1H, J 7.5, 1, H4), 7.33 (dt, 1H, J 7, 1.5, H5), 7.48 (dd, 1H, J 7.5,
1.5, H3), 7.75 (d, 1H, J 7.5, H6). 13C NMR: δ 3.45 (NCMe), 9.87
(C5Me5), 27.00 (Me), 28.27 (Me), 67.96 (CMe2), 82.78 (OCH2),
90.96 (C5Me5), 119.64 (NCMe), 123.74, 127.36, 133.38, 135.20
(C3, C4, C5, C6), 156.64 (NCO), 179.26 (C1Ir). MS (FAB): m/z
We have established that insertion of alkynes into the
M-C bond of cyclometalated phenyl oxazoline complexes
occurs under very mild conditions if the starting complexes
have an easily substituted ligand such as MeCN. Many
cyclopalladated complexes undergo insertion reactions with
CO as well as with alkynes.30 To our knowledge there is only
one report of half-sandwich cyclometalated complexes with
CO,31 and these do not undergo insertion; hence we have
tested the reaction of 2a with CO.
Carbon monoxide was bubbled through a solution of 2a in
CDCl3. After 1.5 h the 1H NMR spectrum showed complete
conversion to a new product, 8a. After recrystallization the
1H NMR spectrum of 8a shows no MeCN present, the CMe2
group is observed as two singlets at δ 1.30 and 1.50, and the
OCH2 protons are observed as two mutually coupled doub-
lets at δ 4.20 and 4.22. These observations are consistent with
a chiral metal center and that, unlike 2a, no epimerization
occurs on the NMR time scale. The 13C{1H} NMR spectrum
shows the expected signals for the Cp* and oxazoline ligand
with an additional signal at δ 165.52 assigned to a terminal
CO. The FAB mass spectrum shows a molecular ion at m/z
502 [M - NCMe]þ. IR: ν(CdN) 1622 cm-1
.
Preparation of 2b. A mixture of NaOAc (34 mg, 0.41 mmol),
[RuCl2(p-cymene)]2 (100 mg, 0.16 mmol), the oxazoline (57 mg,
0.33 mmol), and KPF6 (120 mg, 0.65 mmol) was heated at 45 °C
in acetonitrile for 3 h. The mixture was filtered throgh Celite,
evaporated to dryness, and washed with ether to give 2b as a
green solid (180 mg, 92%). Anal. Calcd for C23H29N2ORuPF6:
C, 46.39, H, 4.91, N, 4.70. Found: C, 46.23, H, 4.80, N, 4.62. 1H
NMR: δ 0.84 (d, 3H, J 7, CHMeMe0), 1.09 (d, 3H, J 7,
CHMeMe0), 1.47 (s, 3H, oxaz-Me), 1.57 (s, 3H, oxaz-Me),
2.14 (s, 3H, Cy-Me), 2.21 (s, 3H, NCMe), 2.48 (sept, 1H, J 7,
CyCHMeMe), 4.50 (s, 2H, NCH2), 5.21 (d, 1H, J 6, Cy), 5.26
(30) For example see: (a) Thompson, J. M.; Heck, R. F. J. Org.
Chem. 1975, 40, 2667. (b) Tollari, S.; Cenini, S.; Tunice, C.; Palmisano, G.
Inorg. Chim. Acta 1998, 272, 18. (c) Tollari, S.; Demartin, F.; Cenini, S.;
Palmisano, G.; Raimondi, P. J. Organomet. Chem. 1997, 527, 93.
(d) Lindsell, W. E.; Palmer, D. D.; Preston, P. N.; Rosair, G. M.; Jones,
R. V. H.; Whitton, A. J. Organometallics 2005, 24, 1119.
(32) White, C.; Yates, A.; Maitlis, P. M. Inorg. Synth. 1992, 29, 228.
(33) Bennett, M. A.; Smith, A. K. J. Chem. Soc., Dalton Trans. 1974,
233.
(31) Arita, S.; Koike, T.; Kayaki, Y.; Ikariya, T. Organometallics
(34) Denmark, S. E.; Nakajima, N.; Nicaise, O. J.-C.; Faucher,
2008, 27, 2795.
A.-M.; Edwards, J. P. J. Org. Chem. 1995, 60, 4884.

Article
Organometallics, Vol. 29, No. 6, 2010 1419
(d, 1H, J 6, Cy), 5.92 (d, 2H, J 6, Cy), 6.07 (d, 1H, J 6, Cy), 7.08
(dt, 1H, J 7.5, 1, H4), 7.29 (dt, 1H, J 7.5, 1.5 H5), 7.40 (dd, 1H,
J 7.5, 1, H3), 8.03 (d, 1H, J 7.5, H6). 13C NMR: δ 3.54 (NCMe),
18.97 (Cy-MeC6H4), 21.35, 23.54 (Cy-CHMeMe0), 27.65, 28.04
(oxaz-MeMe0) 31.28 (CyCHMeMe), 67.28 (iCMe2), 81.55,
82.24, 91.35, 91.37, (CH (C6H4Cy)), 81.95 (CH2), 104.64,
105.92 (C (C6H4 Cy)), 124.03 (NCMe), 123.83, 126.99, 131.92,
139.72 (C3, C4, C5, C6), 173.12 (NCO), 175.92 (C1Ru). MS
(FAB): m/z (%) 410 [M]þ, 451 [M - NCMe]þ. IR: ν(CdN)
81.65 (OCH2), 91.93 (C5Me5), 124.56 (NCMe), 126.67, 127.05,
128.22, 129.96 131.92, 132.52, 133.61 (Ar-H), 142.64 (C8),
144.69 (C1), 168.71 (CNO) (other quaternary carbons are
not seen). MS (FAB): m/z 676 [M - NCMe]þ. IR: ν(CdN):
1624 cm-1; ν(CdO) 1695 cm-1
.
Preparation of 5a. Phenylacetylene (11 mg, 0.11 mmol) was
added to solution of 2a (73 mg, 0.11 mmol) in dichloromethane,
and the mixture was stirred for 1 h. The mixture was then filtered
through Celite to remove excess KPF6, and the filtrate was
evaporated to dryness and washed with hexane to give 5a as a
pale yellow solid (72 mg, 86%). Anal. Calcd for C31H36Ir-
N2OPF6: C, 47.14, H, 4.59, N, 3.55. Found: C, 47.28, H, 4.37,
1622 cm-1
.
Preparation of 3a. PhCtCPh (67 mg, 0.38 mmol) and KPF6
(103 mg, 0.56 mmol) were added to a solution of 1a (100 mg,
0.19 mmol) in acetonitrile; after stirring for 72 h, no insertion
was observed by ESMS. Other experiments (see above) show
that at this stage 2a was formed. The acetonitrile was replaced by
dichloromethane, and the solution was stirred for 24 h and
filtered through Celite to remove excess KPF6. The filtrate was
evaporated to dryness and then washed with hexane to give 3a as
a yellow solid (122 mg, 76%). Anal. Calcd for C37H40IrN2OPF6:
C, 51.32; H, 4.66; N, 3.24. Found: C, 51.12; H, 4.53; N, 3.31. 1H
NMR: δ 1.31 (s, 3H, CMeMe0), 1.37 (s, 3H, CMeMe0), 1.41 (s,
15H, Cp*), 2.00 (s, 3H, NCMe), 4.27 (d, 1H, J 9, OCHH0), 4.58
(d, 1H, J 9, OCHH0), 6.30 (br, 1H, Ph), 6.74 (br m, 2H, Ph), 6.81
(br m, 2H, Ph), 6.99 (m, 5H, H6, Ph), 7.24 (m, 2H, H4, Ph), 7.31
(dt, 1H, J 7.5, 1.5, H5), 7.72 (dd, 1H J 7.5, 1, H3). 13C NMR: δ
2.35 (NCMe), 8.74 (C5Me5), 24.64, 27.57 (2ꢀMe), 72.31
(CMeMe0), 81.50 (CH2), 91.66 (C5Me5), 124.80 (NCMe),
124.17, 125.32, 125.95, 127.52, 128.12, 131.72 132.40, 134.14
(Ar-H), 141.88 (C2), 146.3, 147.91 (C1, C7), 151.38 (iC, Ph of
alkyne), 152.40 (C8), 169.16 (CNO). MS (FAB): m/z 679 [M -
1
N, 3.47. H NMR: δ 1.14 (s, 3H, CMeMe0), 1.29 (s, 3H,
CMeMe0), 1.34 (s, 15H, Cp*), 1.99 (s, 3H, NCMe), 4.11 (d,
1H, J 9, OCHH0), 4.42 (d, 1H, J 9, OCHH0), 6.97 (m, 2H, Ph),
7.06 (m, 2H, H7, Ph), 7.20 (m, 4H, H4, H6, Ph), 7.41 (dt, 1H, J
7.5, 1.5, H5), 7.63 (dt, 1H, J 8, 1.5, H3). 13C NMR: δ 2.67
(NCMe), 8.93 (C5Me5), 24.89, 27.33 (2ꢀMe), 72.66 (CMeMe0),
81.08 (CH2), 91.55 (C5Me5), 121.84 (NCMe), 122.97 (iC, Ph),
125.82, 127.02, 125.82, 132.07, 132.11, 133.02 (Ar-H), 132.11
(C7), 143.63 (C1), 152.59 (iC, Ph of alkyne), 155.68 (C8), 169.00
(CNO). MS (FAB): m/z 602 [M - NCMe]þ. IR: ν(CdN)
1527 cm-1
.
Preparation of 5b. PhCtCH (33 mg, 0.33 mmol) was added to
solution of 2b (194 mg, 0.33 mmol) in dichloromethane; after
stirring overnight, the mixture was filtered through Celite,
1
evaporated to dryness, and then washed with hexane. The H
NMR spectrum suggested the compound was not pure, so it was
washed through a short plug of silica (DCM/NCMe) to give 5b
as an orange solid (120 mg, 53%). Anal. Calcd for C31H35Ru-
N2OPF6: C, 53.37, H, 5.06, N, 4.02. Found: C, 53.47, H, 5.01, N,
3.95. 1H NMR: δ 1.00 (s, 3H, oxz Me), 1.18 (d, 1H, J 7,
CHMeMe0), 1.21 (d, 1H, J 7, CHMeMe0), 1.58 (s, 3H, oxz
Me), 1.85 (s, 3H, NCMe), 2.06 (s, 3H, Me-Cy), 2.71 (sept, 1H,
J 7, CHMeM0), 4.32 (d, 1H, J 9, OCHH0), 4.35 (d, 1H, J 9,
OCHH0), 4.39 (dd, 1H, J 6, 1, Cy), 5.03 (dd, 1H, J 6, 1, Cy), 5.35
(dd, 1H, J 6, 1, Cy), 5.41 (dd, 1H, J 6, 1, Cy), 7.12 (m, 4H, H7,
Ph), 7.29 (m, 4H, H4, H6, Ph), 7.50 (dt, 1H, J 7.5, 1.5, H5), 7.68
(d, 1H, J 7.5, H3). 13C NMR: δ 3.05 (NCMe), 19.43 (Me-Cy),
22.73, 23.69 (CHMeMe0), 25.28, 27.63 (2ꢀMe), 31.37 (CH(iPr)),
71.01 (CMe2), 80.58 (CH2), 82.00, 84.76, 87.84, 88.68
(CH(C6H4)), 108.07, 113.97 (C(C6H4), 124.01 (NCMe),
125.60, 125.90, 127.28, 128.05, 130.66 131.43, 132.08 (Ar-H),
132.32 (C7), 143.72 (C1), 152.48 (iC, Ph of alkyne), 168.57
(CNO), 176.01 (C8). MS (FAB): m/z 512 [M - NCMe]þ. IR:
NCMe]þ. IR: ν(CdN) 1624 cm-1
.
Preparation of 3b. PhCtCPh (33 mg, 0.19 mmol) was added
to solution of 2b (100 mg, 0.17 mmol) in dichloromethane. After
stirring for 24 h the solution was evaporated to dryness and then
washed with hexane. The 1H NMR spectrum suggested the
compound was not pure, so it was washed through a short plug
of silica (DCM/NCMe) to give 3b as a pure complex as a green
solid (66 mg, 51%). Anal. Calcd for C37H39RuN2OPF6: C,
1
57.43, H, 5.08, N, 3.62. Found: C, 55.81, H, 4.67, N, 3.29. H
NMR: δ 1.09 (s, 3H, oxz Me), 1.11 (d, 1H, J 7, CHMeMe0), 1.31
(d, 1H, J 7, CHMeMe0), 1.59 (s, 3H, oxz Me), 1.78 (s, 3H,
NCMe), 2.27 (s, 3H, Me-Cy), 2.90 (sept, 1H, J 7, CHMeMe0),
4.34 (d, 1H, J 9, OCHH0), 4.35 (d, 1H, J 6, Cy), 4.47 (d, 1H, J 9,
OCHH0), 4.54 (d, 1H, J 6, Cy), 5.10 (d, 1H, J 6, Cy), 5.65 (d, 1H,
J 6, Cy), 6.18 (d, 1H, J 8, Ph), 6.73 (t, 1H, J 7.5, Ph), 6.83 (m, 3H,
Ph), 6.96 (m, 3H, Ph), 7.14 (d, 1H, J 7.5, H6), 7.31 (m, 3H, H4,
ν(CdN) 1635 cm-1
.
Ph), 7.38 (dt, 1H, J 7.5, 1.5, H5), 7.62 (dd, 1H, J 7.5, 1, H3). 13
NMR: 2.99 (NCMe), 19.57 (Me-Cy), 22.74, 24.45
C
Preparation of 6a. EtO2CCtCH (21 mg, 0.22 mmol) was
added to solution of 2a (75 mg, 0.11 mmol) in dichloromethane.
After stirring for 3 h, the mixture was filtered through Celite,
evaporated to dryness, and then washed with hexane to give 6a
as a pale yellow solid (70 mg, 82%). Anal. Calcd for C28H36Ir-
N2O3PF6: C, 42.80, H, 4.62, N, 3.57. Found: C, 42.70, H, 4.51,
δ
(CHMeMe0), 25.44, 28.28 (2ꢀMe), 31.61 CH(iPr)), 71.08
(CMe2), 81.57 (OCH2), 80.32, 85.32, 88.09, 91.28 (CH(C6H4)),
109.46, 112.61 (C(C6H4), 126.46 (NCMe), 124.32, 125.57,
126.25, 127.80, 128.49, 131.80 132.02, 133.58, (Ar-H),141.87
(C2), 145.92, 148.88 (C1, C7), 151.54 (iC, Ph of alkyne), 168.64
(C9), 171.46 (C8). MS (FAB): m/z 588 [M - NCMe]þ. IR:
1
N, 3.56. H NMR: δ 1.22 (s, 3H, CMeMe0), 1.27 (m, 3H,
ꢀ
CO2CH2CH3), 1.30 (s, 15H, Cp*), 1.37 (s, 3H, CMeMe), 2.71
ν(CdN) 1602 cm-1
.
(s, 3H, NCMe), 4.11 (m, 3H, CO2CH2CH3, overlap, d, 1H, J 9,
OCHH0), 4.38 (d, 1H, J 9, OCHH0), 7.22 (m, 2H, H4, H6), 7.45
(dt, 1H, J 7.5, 1.5, H5), 7.48 (s, 1H, H7), 7.62 (d, 1H, J 7.5, H3).
13C NMR: δ 3.93 (NCMe), 8.61 (C5Me5), 14.84 (CO2CH2CH3),
24.81, 27.37 (2ꢀMe), 60.52 (CO2CH2CH3), 72.99 (CMeMe0),
81.14 (OCH2), 91.67 (C5Me5), 123.25 (NCMe), 126.95, 131.82,
132.43, 133.09 (C3, C4, C5, C6), 136.60 (C7), 141.65, 144.01 (C1,
C8), 168.64 (CNO), 174.70 (CO2). MS (FAB): m/z 600 [M -
Preparation of 4a. PhCtCCO2Et (21 mg, 0.12 mmol) was
added to solution of 2a (75 mg, 0.11 mmol) in dichloromethane;
after stirring for 3 h, the solution was filtered through Celite,
1
evaporated to dryness, and then washed with hexane. The H
NMR spectrum suggested the compound was not pure, so it was
washed through a short plug of silica (DCM/NCMe) to give 4a
as a beige solid (66 mg, 51%). Anal. Calcd for C34H40Ir-
N2O3PF6: C, 47.38, H, 4.68, N, 3.25. Found: C, 47.25, H,
4.63, N, 3.16. 1H NMR: δ 1.31 (s, 3H, CMeMe0), 1.38 (m, 3H,
CO2CH2CH3), 1.41 (s, 15H, Cp*), 1.46 (s, 3H, CMeMe0), 2.77 (s,
3H, NCMe), 3.79 (m, 2H, CO2CH2CH3), 4.23 (d, 1H, J 9,
OCHH0), 4.53 (d, 1H, J 9, OCHH0), 7.06 (m, 3H, Ph), 7.26 (m,
NCMe]þ. IR: ν(CdN) 1622 cm-1; ν(CdO) 1682 cm-1
.
Preparation of 7a. PhCtCH (21.6 mg, 0.22 mmol) was added
to solution of 2a (73 mg, 0.11 mmol) in dichloromethane; after
stirring for 2 h, the mixture was filtered through Celite, evapo-
rated to dryness, and then washed with hexane to give 7a as a
brown solid (80 mg, 89%). Anal. Calcd for C37H39IrNOPF6: C,
2H, H4, H6, Ph), 7.36 (m, 1H, H5), 7.68 (dd, 1H, J 7.5, 1, H3). 13
C
1
NMR: δ 4.12 (NCMe), 8.53 (C5Me5), 14.15 (CO2CH2CH3),
52.23, H, 4.62, N, 1.65. Found: C, 52.23, H, 4.54, N, 1.64. H
NMR: δ 1.18 (s, 3H, CMeMe0), 1.37 (s, 3H, CMeMe0), 1.76
24.63, 27.24 (2xMe), 59.48 (CO2CH2CH3), 72.79 (CMeMe0),

1420 Organometallics, Vol. 29, No. 6, 2010
Table 1. Crystallographic Data for 2a, 3b, 5a, 5b, and 7a
Davies et al.
2a
3b
5a
5b
7a
empirical formula
fw
C
687.66
150(2)
monoclinic
C2/c
25.528(4)
12.890(2)
15.351(3)
90
95.196(3)
90
5030.4(15)
8
1.816
5.435
2688
23H30F6IrN2OP
C37H37F6N2OPRu
771.73
150(2)
triclinic
P1
9.4592(12)
10.6699(13)
19.855(3)
C31H36F6IrN2OP
789.79
150(2)
monoclinic
P2(1)/c
13.9443(10)
12.4836(8)
18.8176(13)
90
106.414(1).
90
3142.2(4)
C31H35F6N2OPRu
697.65
150(2)
monoclinic
P2(1)/c
15.3684(8)
8.6735(5)
22.3405(12)
90
96.764(1)
90
2957.2(3)
4
1.567
0.650
1424
C75H80Cl2F12Ir2N2O2P2
1786.69
150(2)
triclinic
P1
10.2780(12)
10.6585(13)
16.300(2)
90.631(2)
97.335(2)
101.336(2)
1735.3(4)
1
1.710
4.034
886
temperature/K
cryst syst
space group
˚
a/A
˚
b/A
˚
c/A
R/deg
β/deg
γ/deg
93.500(2)
103.563(2)
114.285(2)
1747.4(4)
2
1.467
3
˚
U/A
Z
4
1.670
4.363
1560
density (calcd)/Mg/m3
abs coeff/ mm-1
F(000)
0.558
788
cryst size/mm
theta range/deg
index ranges
0.22 ꢀ 0.20 ꢀ 0.09
1.60 to 26.00
-31 e h e 31,
-15 e k e 15,
-18 e l e 18
19 090
0.29 ꢀ 0.21 ꢀ 0.18
2.13 to 25.00
-11 e h e 11,
-12 e k e 12,
-23 e l e 23
12 602
0.34 ꢀ 0.13 ꢀ 0.07
1.52 to 26.00
-17 e h e 17,
-15 e k e 15,
-23 e l e 23
23 528
0.29 ꢀ 0.21 ꢀ 0.18
1.33 to 25.00
-18 e h e 18,
-10 e k e 10,
-26 e l e 26
20 816
0.21 ꢀ 0.11 ꢀ 0.09
1.26 to 27.00
-13 e h e 13,
-13 e k e 13,
-20 e l e 20
14 726
reflns collected
indep reflns (Rint
)
4938 [R(int) =
0.0335]
6076 [R(int) =
0.0310]
6165 [R(int) =
0.0787]
5210 [R(int) =
0.0896]
7434 [R(int) =
0.0305]
data/restraints/params
goodness-of-fit, F2
4938/0/315
1.057
6076/0/458
1.044
6165/72/440
0.955
5210/0/431
1.056
7434/0/449
0.972
final R indices [I > 2σ(I)]
R1 = 0.0240,
wR2 = 0.0648
R1 = 0.0271,
wR2 = 0.0659
1.549 and -1.662
R1 = 0.0524,
wR2 = 0.1352
R1 = 0.0598,
wR2 = 0.1408
1.199 and -0.730
R1 = 0.0420,
wR2 = 0.0884
R1 = 0.0558,
wR2 = 0.0936
3.595 and -0.827
R1 = 0.0446,
wR2 = 0.1205
R1 = 0.0471,
wR2 = 0.1229
1.255 and -1.132
R1 = 0.0345,
wR2 = 0.0694
R1 = 0.0400,
wR2 = 0.0713
1.882 and -1.679
R indices (all data)
-3
˚
largest diff peak and hole/e A
(s, 15H, Cp*), 2.94 (d, 1H, J 9, OCHH0), 4.18 (d, 1H, J 9,
OCHH0), 4.68 (s, 1H, H7), 6.41 (s, 1H, H10), 7.02 (m, 3H, Ph),
7.13 (m, 3H, Ph), 7.34 (m, 2H, Ph), 7.40 (dt, 1H, J 6.5, 1.5, H4),
7.50 (m, 2H, Ph), 7.55 (dd, 1H, J 7, 1, H6), 7.77 (dt, 1H, J 7, 1.5,
H5), 7.83 (dd, 1H, J 7.5, 1, H3). 13C NMR: δ 9.50 (C5Me5), 25.99,
27.66 (2ꢀMe), 48.58 (C7), 71.01 (CMeMe0), 80.44 (OCH2),
95.99 (C5Me5), 104.92 (C9), 119.84 (C10), 127.37, 127.47,
127.90, 128.51, 128.69, 131.65, 132.32 133.64 (Ar-H), 123.98,
125.38 (iC, Ph), 133.75, 138.24 (C1, C8), 152.61 (iC), 165.33
X-ray Crystal Structure Determinations. Details of the struc-
ture determinations of crystals of 2a, 3b, 5a, 5b, and 7a are given in
Table 1. Data were collected on a Bruker Apex 2000 CCD
diffractometer using graphite-monochromated Mo KR radiation,
˚
λ = 0.7107 A at 150 K. The data were corrected for Lorentz and
polarization effects, and empirical absorption corrections
(SADABS).35 were applied in all cases. The structures were solved
by Patterson methods and refined by full-matrix least-squares on
F2 using the program SHELXTL.36 All hydrogen atoms bonded to
(CNO). MS (FAB): m/z 704 [M]þ. IR: ν(CdN) 1604 cm-1
.
carbon were included in calculated positions (C-H = 0.96 A)
˚
Preparation of 8a. CO was bubbled through a solution of 2a (42
mg, 0.62 mmol) in CDCl3 for 1.5 h. The solution was evaporated
to dryness and was recrystallized from dichloromethane/hexane
togive 8a as a yellow precipitate(38mg, 92.3.3%). Anal. Calcd for
C22H27IrN2O2PF6: C, 39.17, H, 4.03, N, 2.08. Found: C, 39.05, H,
3.96, N, 1.97. 1H NMR: δ 1.30 (s, 3H, Me), 1.50 (s, 3H, Me), 2.00
(s, 15H, Cp*), 4.20 (d, 1H, J 5, CHH0) 4.22 (d, 1H, J 5, CHH0),
7.30 (dt, 1H, J 7.5, 1, H4), 7.43 (dt, 1H, J 7, 1.5, H5), 7.63 (m, 2H,
H3, H6). 13C NMR: δ 10.05 (C5Me5), 27.05 (Me), 27.85 (Me),
69.20 (CMe2), 81.99 (OCH2), 102.17 (C5Me5), 126.01, 129.12,
134.42, 136.27 (C3, C4, C5, C6), 144.76 (C2), 165.52 (CO), 180.44
(C1Ir). MS (FAB): m/z 530 [M]þ, 502 [M - CO]þ. IR: ν(CtO)
using a riding model. All non-hydrogen atoms were refined with
anisotropic displacement parameters without positional restraints.
Figures were drawn using the program ORTEP.37
Atomic coordinates, bond lengths and angles, and thermal
parameters have been deposited at the Cambridge Crystallo-
graphic Data Centre, CCDC Nos. 758499-758503.
Acknowledgment. We thank the Saudi Arabian govern-
ment (O.A.-D.) for a studentship and Johnson Matthey for
a loan of iridium trichloride and ruthenium trichloride.
2042 cm-1, ν(CdN) 1614 cm-1
.
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.
(35) SADABS, Version 6.02; Bruker Inc.: Madison, WI, 1998-2000.
(36) SHELXTL, Version 6.10; Bruker Inc.: Madison, WI, 1998-2000.
(37) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.