Reactivity and regioselectivity of insertion of unsaturated molecules into M-C (M = Ir, Rh) bonds of cyclometalated complexes

Article abstract of DOI:10.1021/om100796q

The reactivity of four different cyclometalated iridium and rhodium complexes (1, Ir-N-Me; 2, Rh-N-Me; 3, Ir-N-Py; 4, Rh-N-Py) with ancillary ligands with different electronic and steric properties has been investigated by reactions of ethylene (a), propylene (b), carbon monoxide (c), tert-butylisocyanide (d), acetylene (e), and phenylacetylene (f). Only coordination products were obtained for the reactions of ethylene and propylene with 1 and 3, while inserted and rearranged products were achieved for the reactions with 2 and 4. Insertion of a single equivalent of acetylene was observed for the reactions with 2, 3, and 4, whereas reaction with 1 produces a product in which 4 equiv of acetylene has undergone insertion. The reactions with carbon monoxide showed clean M-C bond insertion products, while tert-butylisocyanide formed only terminal adducts. Two equivalents of phenylacetylene were observed to insert for all of the cyclometalated complexes. The regioselectivity was also investigated for each cyclometalated complex by using a series of internal unsymmetrical alkynes, and the results revealed that the regioselectivity was controlled by both steric and electronic factors. The insertion compounds were fully characterized by ¹H NMR spectroscopy, ¹³C NMR spectroscopy, elemental analysis, and X-ray determinations for selected cases.

Full text of DOI:10.1021/om100796q

Organometallics 2010, 29, 4593–4605 4593
DOI: 10.1021/om100796q
Reactivity and Regioselectivity of Insertion of Unsaturated Molecules
into M-C (M = Ir, Rh) Bonds of Cyclometalated Complexes
Ling Li, Yunzhe Jiao, William W. Brennessel, and William D. Jones*
Department of Chemistry, University of Rochester, Rochester, New York 14627
Received August 16, 2010
The reactivity of four different cyclometalated iridium and rhodium complexes (1, Ir-N-Me;
2, Rh-N-Me; 3, Ir-N-Py; 4, Rh-N-Py) with ancillary ligands with different electronic and steric
properties has been investigated by reactions of ethylene (a), propylene (b), carbon monoxide (c), tert-
butylisocyanide (d), acetylene (e), and phenylacetylene (f). Only coordination products were obtained
for the reactions of ethylene and propylene with 1 and 3, while inserted and rearranged products were
achieved for the reactions with2 and 4. Insertion ofa single equivalent of acetylene was observed for the
reactions with 2, 3, and 4, whereas reaction with 1 produces a product in which 4 equiv of acetylene has
undergone insertion. The reactions with carbon monoxide showed clean M-C bond insertion
products, while tert-butylisocyanide formed only terminal adducts. Two equivalents of phenylacety-
lene were observed to insert for all of the cyclometalated complexes. The regioselectivity was also
investigated for each cyclometalated complex by using a series of internal unsymmetrical alkynes, and
the results revealed that the regioselectivity was controlled by both steric and electronic factors. The
1
insertion compounds were fully characterized by H NMR spectroscopy, 13C NMR spectroscopy,
elemental analysis, and X-ray determinations for selected cases.
Introduction
field of organometallic chemistry due to a variety of novel
and interesting synthetic applications,1-4 as well as applica-
tions in polymerization and copolymerization catalyzed by
transition metals.5-8 Studies of the fundamental steps of
insertion reactions of unsaturated molecules into metal-
carbon bonds have revealed very important information
about the exact role of the metal during the reactions. Also,
cyclometalated complexes with different ancillary ligands
have shown different reactivities and different mechanisms
depending on the stereoelectronic properties of the unsatu-
rated molecules employed.
Among all the group 10 transition metals, organopalladated
complexes have exhibited high reactivity with a wide variety of
unsaturated molecules, such as CO,9 isocyanides,9b,10
alkenes,9a,c,e,f,11 alkynes,9b,11a,f,12 allenes,13 SO2,14 and
O2,15 showing insertion into the Pd-C (sp2) and Pd-C (sp3)
bonds of palladacycles. Successive insertions of different
Insertion of unsaturated molecules into transition metal-
carbon bonds has been broadly investigated as an important
*To whom correspondence should be addressed. E-mail: jones@
chem.rochester.edu.
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2010 American Chemical Society
Published on Web 09/21/2010
pubs.acs.org/Organometallics

4594 Organometallics, Vol. 29, No. 20, 2010
Li et al.
unsaturated molecules9a,b,10d,16 and multiple insertions of the
same unsaturated molecules12d,e,g,h,17 have also been ob-
served. Pfeffer and co-workers found that insertion of 2 equiv
of diphenylacetylene and dimethylacetylene dicarboxylate
(DMAD) into the Pd-C bond of di-μ-chloro-bridged ortho-
palladated 2-benzylpyridine led to the formation of unex-
pected spiro-compounds via unobserved 10-membered-ring
intermediates.12h,17c The Pd center of the intermediates was
proposed to interact with the double bond of the benzyl ring,
which was responsible for the instability of the intermediates.
However, the similar nine-membered-ring product was stabi-
lized by reaction of a di-μ-chloro-bridged cyclopalladated
Schiff base dimer with double insertion of diphenylacetylene
or hex-3-yne. It also showed that the electron-donating ability
of the chelated metallocycle ligand made the insertion more
rapid. The related monomeric palladacycles retarded the reac-
tion dramatically,12g which implied that the bridging chloride
facilitated the coordination of alkyne. The reaction of a 2,20-
bipyridine-coordinated palladacycle in the presence of AgBF4
to remove the halidetoform a cationicarylpalladium complex
resulted in the insertion of three molecules of DMAD into the
Pd-aryl bond, while only one DMAD insertion was observed
to insert in the absence of AgBF4.12e It was also found that less
reactive substrates usually led to monoinserted products,
whereasthe more reactiveones resulted in further insertion.12b
Kinetically, it was observed that for the double insertion of
alkynes in a di-μ-chloro-bridged cyclopalladated dimer, the
insertion of the first alkyne molecule is the rate-determining
step, and electron-donating groups on the phenyl ring of the
benzyl group increase the reaction rate.12g However for the
double insertion into the Pd-methyl bond for the palladium
chloro methyl complexes, the rate of insertion for the second
alkyne is more than 3 orders magnitude slower than the first
insertion.12b
The regioselectivity for insertion reactions with unsymme-
trical alkynes was found to be high for most cases. The
Pfeffer group found that in the insertion of 4,4-dimethyl-2-
pentyne in palladacycles possessing a chelated sulfur or
nitrogen directing group, the major or sole regioisomer was
the insertion product in which the tert-butyl group was R to
the palladium atom. The opposite regiochemistry was ob-
served in the absence of this chelation.12f Reactions of the
ortho-palladated dimethylbenzylamine complexes with un-
symmetrical ester-activated alkynes showed that the carbox-
ylate group of the insertion products is preferentially next to
the phenyl group of the benzylamine moiety (i.e., β to the
metal). The reverse regioselectivity was observed in reactions
with electron-deficient palladium centers.12c Kinetic and
theoretical studies revealed that both electronic and steric
factors accounted for the substitution patterns of the
products.
For similar insertion reactions with platinum complexes,
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alkenes18b,20 have also been observed. It is interesting to
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of platinaoxetanes21 instead of the Pt-C bonds on the basis
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(OCH3), CO was selectively inserted into the Pt-O bond
without further insertion into the available Pt-C bond.23
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Pd-C(sp2) bonds was obtained from the methylplatinum
complex (C10H12OMe)Pt(PPh3)(Me).18c Insertion of unsa-
turated molecules into Ni-C bonds is also common.24
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unsymmetrical alkynes produced the regioisomer that has
the bulkier substituents attached to the R-carbon.24d The
insertion reaction of a nickelacycle with ethyl 2-butynoate,
however, resulted in only one regioisomer in which the methyl
group is R to the nickel center, the reverse selectivity.24c Bothe
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Article
A few examples of insertion reactions of unsaturated
Organometallics, Vol. 29, No. 20, 2010 4595
treated with one atmosphere of ethylene (a) in methanol at
room temperature. The yellow solutions of 1 and 3 turned
pale yellow within 5 min, producing 1a and 3a, respectively,
while the orange solutions of 2 and 4 turned bright red within
5 min, producing 2a and 4a, respectively (eqs 1 and 2). The
products are readily characterized by 1H NMR and 13C
NMR spectroscopies.
molecules into Ru-C bonds have also been documented in
the literature.25 It was found that the Ru-aryl bond was
subject to insertion over the Ru-alkyl bond as observed by
the reactions with ortho-metalated benzyl ruthenium com-
pounds.25f However, there have been only limited reports
about the insertion reaction with organo-rhodium and orga-
no-iridium complexes.26-28 In a previous paper, we reported
on the mechanism of acetate-assisted electrophilic activation
by [Cp*RhCl2]2.29 We also reported an example of the inser-
tion of dimethylacetylene dicarboxylate to produce isoquino-
linium salts following oxidative coupling of the insertion
products by copper(II) chloride.29b Closely related work has
been reported recently by Davies et al. on the activation of
4,4-dimethyl-2-oxazolinylbenzene by both [Cp*IrCl2]2 and
[(p-cymene)RuCl(MeCN)]þ and insertion reactions involving
terminal and internal alkynes.30
In this paper, we present a detailed study of the insertion
reactions of a variety of unsaturated molecules (ethylene,
propylene, carbon monoxide, tert-butylisocyanide, acety-
lene, and phenylacetylene) using four five-membered iridium
and rhodium cyclometalated complexes. The investigation
has been carried out by use of NMR spectroscopic methods
as well as X-ray structural determinations for key structures.
Mechanistic pathways are also proposed to rationalize the
experimental results. The regioselectivity of the insertion
reactions with unsymmetrical internal alkynes was also
studied with the goal of finding the factors controlling the
regioselectivity. The regioisomers were isolated by column
chromatography and fully characterized by NMR spectro-
scopies and X-ray structural analysis for selected cases.
Considering that cyclometalated complexes can oftentimes
be easily prepared by direct cleavage of a C-H bond
adjacent to a donor directing atom (nitrogen for example)
under mild conditions, it is important to learn more about
factors affecting the insertion chemistry as a guide to the
development of synthetic organic methods, especially for
heterocycle synthesis.
From the 1H NMR spectrum of 1a, the two doublets at δ
3.16 and 2.96 (δ 3.46 and 3.11 for 3a) suggest a structure with
coordinated freely rotating ethylene rather than an insertion
product. The 13C{1H} NMR spectrum showed a singlet at
δ 88.82 for the bound ethylene in 1a, also indicating facile
rotation. The coodination compounds 1a and 3a were
unstable and decomposed very quickly to starting material
without protection of the ethylene atmosphere. No crystals
of the products could be isolated to further confirm the
structures. In considering the mechanism of reaction, both 1
and 3 are coordinatively saturated 18-electron complexes,
and an open coordination site is required to form a 16-
electron intermediate, which could then coordinate ethy-
lene. There are two possible sequences for producing co-
ordinative unsaturation: (1) nitrogen dissociation or (2)
chloride dissociation to form a 16-electron iridium cation.
On the basis of previous results,29 the Ir-Cl bond lengths for
Results and Discussions
1. Reaction with Ethylene. The preparations of metalla-
cycles 1-4 have been reported from [Cp*IrCl2]2 and
[Cp*RhCl2]2 and the corresponding imines in the presence
of sodium acetate.29 Each cyclometalated complex was
˚
1 and 3 are around 2.4 A, which implies that the bonds are
more ionic than covalent and that polar solvents such as
methanol could favor ionic species, suggesting that chloride
dissociation is the preferred mechanism. By adding an excess
of ammonium chloride, the reaction of ethylene with 1 was
dramatically retarded, confirming the chloride dissociation
mechanism.
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Chakravorty, A. Organometallics 2001, 20, 1419. (d) Ferstl, W.; Sakodinskaya,
I. K.; Beydoun-Sutter, N.; Borgne, G. L.; Pfeffer, M.; Ryabov, A. D. Organo-
metallics 1997, 16, 411. (e) Bellachioma, G.; Cardaci, G.; Macchioni, A.;
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28, 3492. (b) Li, L.; Brennessel, W. W.; Jones, W. D. J. Am. Chem. Soc.
2008, 130, 12414. For an earlier report of this cyclometalation with phenyl
pyridine (regretfully overlooked in the above 2008 paper), see: Scheeren, C.;
Maasarani, F.; Hijazi, A.; Djukic, J.-P.; Pfeffer, M.; Zaric, S. D.; Le Goff,
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1H NMR confirmed the structures for 2a and 4a as
shown in eq 2 with an unusual [1,1] ethylene insertion,
showing a doublet (J = 7 Hz) for the methyl group and a
doublet of quartets (J = 7 Hz) for the methine. The X-ray
structures of 2a and 4a were also obtained to further confirm
the [1,1]-insertion products as shown in Figure 1. After
˚
insertion, the Rh-Cl bond is lengthened by 0.02 A, indicating
weaker rhodium chloride bonding. It was noticed that only
one of two possible stereoisomers was observed in each case,
as a new chiral carbon center was generated after insertion.
The preference for six-membered-ring metallacycles
over seven-membered-ring metallacycles accounts for the
[1,1]-insertion instead of [1,2]-insertion. A proposed me-
chanism is drawn in Scheme 1. The 16-electron cation is
formed first by dissociation of the chloride followed by
(30) Davies, D. L.; Al-Duaji, O.; Fawcett, J.; Singh, K. Organome-
tallics 2010, 29, 1413.

4596 Organometallics, Vol. 29, No. 20, 2010
Li et al.
Figure 1. Molecular structures for (a) 2a and (b) 4a with 50% displacement ellipsoids. H atoms are omitted for clarity. Selected bond
˚
distances (A) and angles (deg): (a) Rh(1)-N(1) 2.1003(14), Rh(1)-Cl(1) 2.4282(5), Rh(1)-C(1) 2.1185(16), C(1)-C(2) 1.480(2),
C(2)-C(7) 1.410(2), C(7)-C(8) 1.458(2), C(8)-N(1) 1.283(2), N(1)-Rh(1)-Cl(1) 91.55(4), C(1)-Rh(1)-Cl(1) 85.98(5), N(1)-
Rh(1)-C(1) 80.55(6), C(2)-C(1)-Rh(1) 108.51(11), C(7)-C(2)-C(1) 119.55(15), C(2)-C(7)-C(8) 120.89(16), N(1)-C(8)-C(7)
124.17(15), C(8)-N(1)-Rh(1) 123.70(11); (b) Rh(1)-N(1) 2.0974(10), Rh(1)-Cl(1) 2.4110(3), Rh(1)-C(1) 2.1112(12), C(1)-C(2)
1.48005(17), C(2)-C(7) 1.4153(17), C(7)-C(8) 1.4793(16), C(8)-N(1) 1.3581(15), N(1)-Rh(1)-Cl(1) 90.73(3), C(1)-Rh(1)-Cl(1)
85.65(3), N(1)-Rh(1)-C(1) 80.86(4), C(2)-C(1)-Rh(1) 106.31(8), C(7)-C(2)-C(1) 120.87(10), C(2)-C(7)-C(8) 121.37(10),
N(1)-C(8)-C(7) 119.42(10), C(8)-N(1)-Rh(1) 123.81(8).
Scheme 1. Proposed Pathway for the Insertion Reaction of Ethylene
ethylene coordination, and the ethylene-coordinated cation
undergoes insertion to form the unstable seven-membered
metallacycle. β-Hydrogen elimination occurs in intermediate
I, leading to an olefin hydride intermediate II. Note that
isomerism must occur in species II to give species III by
dissociation and recoordination of the olefin in order to
achieve the proper facial selectivity for the observed product
stereoselectivity at carbon in 2a and 4a. The olefin hydride
III then proceeds by insertion to produce the six-membered-
ring cation complex, which finally coordinates chloride to
form the observed product. It also deserves mentioning that
no further ethylene insertion was observed in the reactions of
ethylene with 2 or 4 under the same reaction conditions, even
after a week, which is different from the observation for the
reaction of ethylene with cycloruthenated tertiary amines.25a
2. Reaction with Propylene. The reactions with propylene
(b) with 1-4 were conducted under the same reaction con-
ditions as with ethylene, and similar results are summarized
in eqs 3 and 4, respectively. As propylene is a prochiral olefin,
two pale yellow isomers (1b/10b or 3b/30b) were formed in the
reactions of propylene with 1 and 3 at room temperature
within 5 min (ratios of 1:1.3 and 1:2.0, respectively). The
mixture of two rotamers decomposed quickly back to 1 and 3
without a propylene atmosphere.
Bright red [1,1]-insertion products were observed for the
reactions of propylene with 2 and 4 at room temperature
within 5 min. The product 2b from reaction with 2 is more
reactive, making the reaction not as clean as the reaction with

Article
Organometallics, Vol. 29, No. 20, 2010 4597
Figure 3. Molecular structure and atom-numbering scheme for
2c with 50% displacement ellipsoids. H atoms are omitted for
˚
clarity. Selected bond distances (A) and angles (deg): Rh(1)-N-
Figure 2. Molecular structure and atom-numbering scheme for
4b with 50% displacement ellipsoids. H atoms are omitted for
clarity. Selected bond distances (A) and angles (deg): Rh(1)-N-
(1) 2.1077(17), Rh(1)-Cl(1) 2.4077(5), Rh(1)-C(1) 2.1110(18),
C(1)-C(2) 1.482(3), C(2)-C(7) 1.415(2), C(7)-C(8) 1.473(3),
C(8)-N(1) 1.350(2), N(1)-Rh(1)-Cl(1) 91.18(4), C(1)-Rh(1)-
Cl(1) 86.12(5), N(1)-Rh(1)-C(1) 80.34(7), C(2)-C(1)-Rh(1)
106.00(12),C(7)-C(2)-C(1) 119.70(16),C(2)-C(7)-C(8) 121.51(16),
N(1)-C(8)-C(7) 119.52(16), C(8)-N(1)-Rh(1) 123.37(13).
(1) 2.0842(16), Rh(1)-Cl(1) 2.4144(5), Rh(1)-C(1) 2.0842(16),
C(1)-O(1) 1.215(2), C(1)-C(2) 1.507(3), C(2)-C(7) 1.401(3),
C(7)-C(8) 1.463(3), C(8)-N(1) 1.279(2), N(1)-Rh(1)-Cl(1)
91.13(5), C(1)-Rh(1)-Cl(1) 93.12(6), N(1)-Rh(1)-C(1) 88.27(7),
C(2)-C(1)-Rh(1) 116.70(13), C(7)-C(2)-CC(1) 123.47(17),
C(2)-C(7)-C(8) 123.13(18), N(1)-C(8)-C(7) 124.35(18), C(8)-
N(1)-Rh(1) 125.02(14).
˚
The methylated compounds were reacted under 1 atm of
carbon monoxide in methanol, and only the metal-methyl
insertion products were observed by 13C NMR spectroscopy, in
which the chemical shift for carbonyl carbon was above 190
ppm. This observed insertion preference is reversed compared
with the analogous ruthenium complexes.25f As CO insertions
commonly occur by alkyl migration to a coordinated carbon
monoxide,32 the mechanism likely involves nitrogen dissocia-
tion in the metallacycle prior to CO binding and insertion. The
reactions with methylated compounds took much longer to go
to completion, consistent with a slow chelate-opening step. The
insertion of CO seen here stands in contrast to the observation
of simple CO coordination by Davies et al. in Cp*Ir(4,4-
dimethyl-2-oxazolinylphenyl)(CH3CN)]þ.30
4. Reaction with tert-Butylisocyanide. Isocyanides are iso-
electronic with CO and are generally more reactive than
alkynes, undergoing facile insertion into metal-carbon
bonds.25b The same insertion pattern would be expected as
seen with CO. However, reaction of 1 and 2 with tert-
butylisocyanide (d) produced yellow, oily products 1d and
2d, as shown in eq 6. The products are very stable and undergo
no further reaction with excess isocyanide. IR absorptions for
the products at 2156 and 2177 cm-1, respectively, suggest the
existence of a terminal CtNR functional group. The X-ray
structure for 1d shown in Figure 4 was determined and
confirmed terminal coordination to the metal rather than
insertion into the M-C bond. These observations are puz-
zling considering the established facile insertion of isonitriles
relative to carbon monoxide. It is possible that strong metal-
aryl bonds are again responsible for the lack of insertion.
4. One possible reason for this is that the rhodium center with
N-methyl substitution is more electron-rich than the center
with N-pyridyl substitution, which makes 2 more reactive with
electron-rich olefins. The X-ray structure for 4b was deter-
mined to further confirm the [1,1]-insertion product as shown
in Figure 2. The X-ray structure confirmed a propyl group
instead of an isopropyl group as observed by Pfeffer in the
reaction of cycloruthenated tertiary amines.25a Only one ster-
eoisomer was observed for 2b and 4b, as seen with ethylene.
The varying results with rhodium compounds ([1,1]-in-
sertion) versus iridium compounds (coordination only)
could be accounted for by a stronger binding of the olefin
to iridium, lowering the energy of this complex relative to the
insertion complex. However, since the olefin coordination to
iridium is reversible, this is apparently not the reason for the
difference in reactivity. Another possibility is that iridium
does not undergo olefin insertion because the Ir-aryl bond is
stronger than the Rh-aryl bond. There is ample literature
precedent for this possibility,31 which indicates thermody-
namics accounts for the difference in reaction products.
3. Reaction with Carbon Monoxide. Light yellow products
were observed within 5 min in the reaction of carbon monoxide (c)
with 1-4under the same reaction conditions as mentioned above
(eq 5). However, the insertion products were not very stable and
decomposed slowly in either solid state or solution upon
exposure to air. The X-ray structure of 2c was obtained from
crystallization of a mixture of 2 and 2c and is shown in Figure 3.
Reaction of 3 and 4 with methyllithium at room temperature
overnight in dry dichloromethane produces the analogous
compounds with methyl coordination in place of chloride.
5. Reaction with Acetylene. Similar reactions of 1-4 have
been examined under 1 atm of acetylene (e) in methanol at
(31) Simoes, J. A. M.; Beauchamp, J. L. Chem. Rev. 1990, 90, 629.
(32) Noack, K.; Calderazzo, F. J. Organomet. Chem. 1967, 10, 101.

4598 Organometallics, Vol. 29, No. 20, 2010
Li et al.
room temperature. Only 1 equiv of acetylene insertion was
observed for 2, 3, and 4 within 5 min at room temperature, as
shown in eq 7. The aromatic region of the 1H NMR spectrum
displayed two proton resonances with large coupling constants,
and single-crystal X-ray structures were also obtained for 3e
and 4e, as shown in Figure 5. The unusual seven-membered
metallacycles were obtained without further rearrangement. In
the reaction of 1 with acetylene, however, 4 equiv of acetylene
was observed to insert. The 1H NMR spectrum revealed eight
additional olefinic proton peaks (δ 5.1-2.8). No X-ray struc-
ture could be obtained to determine the structure of this species.
Compounds 2, 3, and4also reacted with additional acetylene at
long reaction times, but no reliable information could be
obtained as to the product identities.
Figure 4. Molecular structure and atom-numbering scheme for
1d with 50% displacement ellipsoids. H atoms are omitted for
˚
clarity. Selected bond distances (A) and angles (deg): Ir(1)-N(1)
2.076(5), Ir(1)-C(1) 2.060(5), Ir(1)-C(9) 1.924(5), C(1)-C(2)
1.388(8), C(1)-C(6) 1.400(7), C(6)-C(7) 1.438(8), C(8)-N(1)
1.448(7), C(9)-N(2) 1.161(6), Ir(1)-C(9)-N(2) 177.6(5),
C(9)-N(2)-C(10) 167.5(6), N(1)-Ir(1)-C(1) 77.8(2), C(2)-
C(1)-Ir(1) 128.5(4), C(1)-C(6)-C(7)114.4(5), C(6)-C(1)-Ir(1)
114.1(4), N(1)-C(7)-C(6) 116.6(5), C(7)-N(1)-Ir(1) 116.8(4).
6. Reaction with Propyne and Phenylacetylene. Terminal
alkynes such as propyne and phenylacetylene have been
employed in reactions with 1-4 in methanol at room tem-
perature. All of the reactions with propyne produced pro-
ducts that were too reactive toward further insertions to yield
any useful information about the nature of the products.
However, the reactions with phenylacetylene (f) showed
insertion of 2 equiv of alkyne, as shown in eq 8. The X-ray
structure (connectivity only; see Supporting Information) of
the product (1f) obtained by reaction of phenylacetylene with
1 was determined. The reactions of 2 and 4 with phenylace-
tylene were not as clean as the reactions of 1 and 3, and the
double-insertion products were formed along with small
quantities of byproducts.
was seen by Davies et al. in the reaction with Cp*Ir(4,4-
dimethyl-2-oxazolinylphenyl)(CH3CN)]þ.30
7. Reaction with Unsymmetrical Internal Alkynes. A series
of unsymmetrical internal alkynes of the type RCtCCO2Et
have been employed to investigate the regioselectivity of the
insertion reactions. Ethyl 2-butynoate (g), ethyl phenylpro-
piolate (h), and ethyl 4,4,4-trifluoro-2-butynoate (i) have
been reacted with 1-4 in methanol at room temperature,
and two regioisomers have been obtained for two of the three
cases, as shown in eq 9. The regioselectivity results are
summarized in Table 1.
Only one regioisomer was obtained for the reactions with
ethyl 2-butynoate, and the bulky but electron-withdrawing
carboxylate group of the insertion products is preferentially
located adjacent to the metal center, indicating the dom-
A plausible route to 1f is shown in Scheme 2. Due to the π-
overlap of the alkyne with the phenyl group, the alkyne C-C
bond is polarized as shown.33 The chloride of 1 dissociates
first to form a 16-electron cation, and then the phenyl
acetylene undergoes regioselective insertion to produce the
strongest M-C bond (counter to the polarization), forming
a seven-membered metallacycle I. Coordination of a second
alkyne and rearrangement to its vinylidene isomer allows
insertion to give the observed product. Additional evidence
for the proposed mechanism is that by adding excess pheny-
lacetylene to the product of 1 with dimethylacetylene dicar-
boxylate, the analogous phenylacetylene eight-membered-
ring cross-insertion product was formed slowly in methanol.
However, the reaction did not go to completion at room
temperature. A similar double insertion of phenylacetylene
1
inance of electronic effects on the regioselectivity. The H
NOE spectroscopy for 1g and X-ray structures for 3g and 4g
(Figure 6a,b) confirmed the regioselectivity preference.
However, the 13C NMR for 2g showed several doublets with
the coupling constants at ∼20 Hz, which implied the cou-
plings with the rhodium center. The X-ray determination for
2g further confirmed the ferrocene-type structure, which is
consistent with the 1H NMR and 13C NMR data, as shown in
Figure 6h. One new bond was formed between C(1) and C(9),
and the bond length of C(1)-C(2) was dramatically length-
ened.
However, the reactions of 1-4 with ethyl phenylpropio-
late and ethyl 4,4,4-trifluoro-2-butynoate yielded two regioi-
somers. The regioselectivities are not as good as seen in the
palladium analogues.12c,17c For the reactions with ethyl
(33) Cox, A. P.; Ewart, I. C.; Stigliani, W. M. J. Chem. Soc., Faraday
Trans. 2 1975, 71, 504.

Article
Organometallics, Vol. 29, No. 20, 2010 4599
Figure 5. Molecular structure and atom numbering scheme for (a) 3e and (b) 4e with 50% displacement ellipsoids. H atoms are omitted
˚
for clarity. Selected bond distances (A) and angles (deg) for 3e: Ir(1)-N(1) 2.112(4), Ir(1)-Cl(1) 2.4230(13), Ir(1)-C(1) 2.041(5),
C(1)-C(2) 1.334(8), C(2)-C(3) 1.474(8), C(3)-C(8) 1.399(8), C(8)-C(9) 1.491(7), C(9)-N(1) 1.348(7), N(1)-Ir(1)-Cl(1) 89.16(12),
C(1)-Ir(1)-Cl(1) 84.11(15), N(1)-Ir(1)-C(1) 86.5(2), C(2)-C(1)-Ir(1) 128.8(4), C(3)-C(2)-C(1) 124.5(5), C(8)-C(3)-C(2)
˚
124.8(5), C(9)-C(8)-C(3) 125.9(5), N(1)-C(9)-C(8) 123.7(4), C(9)-N(1)-Ir(1) 124.0(3). Selected bond distances (A) and angles
(deg) for 4e: Rh(1)-N(1) 2.120(5), Rh(1)-Cl(1) 2.4072(17), Rh(1)-C(1) 1.997(7), C(1)-C(2) 1.321(9), C(2)-C(3) 1.461(9), C(3)-C(8)
1.413(9), C(8)-C(9) 1.489(8), C(9)-N(1) 1.363(8), N(1)-Rh(1)-Cl(1) 92.07(14), C(1)-Rh(1)-Cl(1) 85.39(19), N(1)-Rh(1)-C(1)
85.4(2), C(2)-C(1)-Rh(1) 129.2(5), C(3)-C(2)-C(1) 125.1(6), C(8)-C(3)-C(2) 125.2(6), C(9)-C(8)-C(3) 124.7(6), N(1)-C(9)-
C(8) 122.7(5), C(9)-N(1)-Rh(1) 125.4(4).
Scheme 2. Proposed Pathway for Double Insertion of
Phenylacetylene
Table 1. Regioselectivities in the Reactions with Unsymmetrical
Alkynes
R
R0
1:10
2:20
3:30
4:40
COOEt
COOEt
COOEt
Me (g)
Ph (h)
CF3 (i)
1g only
1: 2.4
1:1.9
2g only
1:4.0
1:1.7
3g only
1:1.7
1:2.2
4g only
1:1.2
1:2.0
rated by column chromatography and characterized with
X-ray structures for selected cases, as shown in Figure 6. The
selected bond lengths and bond angles are summarized in
Table 2.
Finally, it is interesting to note that the regioselectivity can
be changed by the speed of adding the alkynes. For example,
when ethyl phenylpropiolate was added dropwise into a solu-
tion of 2, only one regioisomer was observed. Less reactive
alkynes were also employed for insertion reactions, such as
4,4-dimethyl-3-pentyne and 2-pentyne, but the reactions
were too reactive and multiple products were observed.
Conclusions
The insertion reactions of the five-membered iridium and
rhodium cyclometalated complexes with varying directing
groups have been studied with a wide range of unsaturated
molecules (ethylene, propylene, carbon monoxide, tert-bu-
tylisocyanide, acetylene, and phenylacetylene). The results
showed that the reactivity was affected by both electronic
and steric factors. Ethylene and propylene insert into the
rhodium derivatives in a [1,1] fashion, whereas only coordi-
nation is seen with iridium. Carbon monoxide inserts into
both rhodium and iridium derivatives, but isonitrile only
coordinates without inserting. Acetylene inserts one equiva-
lent with most of the derivatives, yet phenyl acetylene inserts
two equivalents, the first in a regiospecific [1,2] fashion and
phenylpropiolate, the major products were the insertion products
with the bulkier phenyl group next to the metal center, which
is consistent with both steric and electronic factors affecting
the regioselectivity. For the reactions with ethyl 4,4,4-tri-
fluoro-2-butynoate, the major products were the insertion
products with the more electron-withdrawing trifluorometh-
yl group next to the metal center, which also implies that the
regioselectivity is determined by electronic factors. Since two
electron-withdrawing substituents are present in these al-
kynes, mixtures of regioisomers are obtained. All the regioi-
somers, especially the major regioisomers, have been sepa-

4600 Organometallics, Vol. 29, No. 20, 2010
Li et al.
Figure 6. Molecular structure and atom-numbering scheme for (a) 3g, (b) 4g, (c) 10h, (d) 30h, (e) 10i, (f) 20I, (g) 30i, and (h) 2g (Cl- not
˚
shown) with 50% displacement ellipsoids. H atoms are omitted for clarity. For 2g, selected bond distances (A) and angles (deg):
Rh(1)-C(1) 2.177(9), Rh(1)-C(2) 2.159(8), Rh(1)-C(3) 2.223(6), Rh(1)-C(8) 2.246(7), Rh(1)-C(9) 2.274 (9), C(1)-C(2) 1.459(12),
C(2)-C(3) 1.440(10), C(3)-C(8) 1.440(8), C(8)-C(9) 1.432(13), C(9)-C(1) 1.459(10), C(1)-C(2)-C(3) 106.3(6), C(2)-C(3)-C(8)
108.5(6), C(3)-C(8)-C(9) 109.8(6), C(8)-C(9)-C(1) 105.9(6), C(9)-C(1)-C(2) 109.5(7).
the second in a [1,1] fashion. Ester-substituted internal ace-
tylenes RCCCOOEt give mixtures of single substrate inser-
tion regioisomers for R = Ph or CF3, but only a single regio-
isomer for R = Me. These observations with unsymmetrical
internal alkynes revealed that the regioselectivity was con-
trolled mainly by electronic factors, favoring products with
an electron-withdrawing group on the carbon adjacent to the
metal. This preference is in line with the anticipated asso-
ciated metal-carbon bond strengths when an R-electron-
withdrawing group is present.34
Experimental Section
General Information. RhCl3 3H2O and IrCl3 3H2O were pur-
3
3
chased from PressureChemical Co., and their dimers[Cp*RhCl2]2
and [Cp*IrCl2]2 were prepared by literature methods.35 The four
cyclometalated complexes were prepared as published.29 Anhy-
drous methanol was purchased from Mallinckrodt and used
(34) Evans, M. E.; Li, T.; Vetter, A. J.; Rieth, R. D.; Jones, W. D.
J. Org. Chem. 2009, 74, 6907.

Article
Organometallics, Vol. 29, No. 20, 2010 4601
a
0
0
0
0
˚
Table 2. Selected Bond Lengths (A) and Angles (°) for (a) 3g, (b) 4g, (c) 1 h, (d) 3 h, (e) 1i, (f) 2 i, and (g) 3 i
3g
4g
10h
30h
1i
20i
30i
M(1)-C(1)
2.071(4)
2.4081(16)
2.116(3)
1.346(6)
1.486(6)
1.407(5)
1.484(5)
1.353(5)
85.87(13)
87.34(12)
87.10(9)
126.8(3)
122.1(3)
123.9(4)
125.2(4)
122.1(3)
124.0(2)
2.058(3)
2.4015(8)
2.118(2)
1.339(4)
1.477(4)
1.404(4)
1.486(4)
1.352(4)
86.81(10)
88.65(9)
88.97(7)
126.2(2)
123.0(3)
124.5(3)
124.9(3)
121.2(2)
125.03(19)
2.051(5)
2.4133(13)
2.076(4)
1.352(7)
1.485(7)
1.404(7)
1.466(7)
1.286(6)
86.20(17)
88.96(14)
89.42(12)
125.2(4)
126.4(4)
125.0(4)
126.2(5)
126.4(5)
127.3(3)
2.054(6)
2.4175(15)
2.121(5)
1.331(8)
1.485(8)
1.402(8)
1.487(8)
1.352(8)
86.3(2)
89.26(16)
87.26(14)
125.2(5)
126.4(6)
123.5(5)
124.3(6)
123.2(5)
124.3(4)
2.067(2)
2.4286(7)
2.0991(19)
1.352(3)
1.491(3)
1.395(3)
1.472(3)
1.282(3)
87.23(8)
89.94(7)
87.05(6)
125.54(18)
125.6(2)
124.5(2)
126.0(2)
127.2(2)
126.63(16)
2.058(3)
2.4274(7)
2.103(2)
1.346(4)
1.490(3)
1.403(4)
1.468(3)
1.279(3)
87.93(9)
91.36(7)
88.44(6)
125.65(19)
125.8(2)
124.7(2)
126.2(2)
127.0(2)
127.15(18)
2.070(2)
2.4266(6)
2.121(2)
1.347(3)
1.496(3)
1.403(3)
1.485(3)
1.352(3)
88.23(8)
88.40(6)
85.73(6)
126.04(16)
123.6(2)
123.1(2)
126.6(2)
121.3(2)
126.37(16)
M(1)-Cl(1)
M(1)-N(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(8)
C(8)-C(9)
C(9)-N(1)
C(1)-M(1)-N(1)
C(1)-M(1)-Cl(1)
N(1)-M(1)-Cl(1)
M(1)-C(1)-C(2)
C(1)-C(2)-C(3)
C(2)-C(3)-C(8)
C(3)-C(8)-C(9)
C(8)-C(9)-N(1)
C(9)-N(1)-M(1)
a M = Ir for 3g, 1h, 3h, 1i, and 3i; M = Rh for 4g and 2i.
without further drying. Propylene, phenylacetylene, ethyl phenyl-
propiolate, and ethyl 4,4,4-trifluoro-2-butynoate were purchased
from Aldrich, carbon monoxide and acetylene were purchased
from Airgas, ethylene was purchased from Air Products, tert-
butylisocyanide was purchased from Strem, and ethyl 2-butynoate
was purchased from Fluka. All reactions described below were
carried out under nitrogen. However, once the reactions were
completed, the further workups weredone without precaution. All
NMR spectra were recorded on Bruker AMX400, AVANCE400,
or AVANCE500 spectrometers in CDCl3 (δ 7.26). Regioisomers
were separated by column chromatography (silica gel, J. T. Baker,
40-140 mesh, and 1-5% MeOH/CH2Cl2 as the eluent). Ele-
mental analyses were determined using a PerkinElmer 2400 Series
II analyzer equipped with a PerkinElmer model AD-6 autoba-
lance by Dr. William W. Brennessel.
1 H, J = 7.6, 0.8 Hz), 7.29 (td, 1 H, J = 7.4, 1.4 Hz), 7.23 (td, 1
H, J = 7.4, 1.0 Hz), 3.46 (d, 2 H, J = 8.4 Hz, C2H4), 3.11 (d, 2 H,
J = 8.2 Hz, C2H4), 1.72 (s, 15 H, C5Me5). 13C NMR: δ 166.14
(HCdN), 155.47 (Ir-C), 152.11, 143.40, 140.09, 136.50, 131.21,
125.44, 125.34, 125.10, 120.00, 99.82 (C5Me5), 88.64 (C2H4),
8.57 (C5Me5).
4a. An orange solution of 4 (40.0 mg, 0.094 mmol) in methanol
(15.0 mL) was bubbled with ethylene at room temperature. The
solution turned dark red within 5 min, the solvent was concen-
trated under vacuum, and the red solid 4a was obtained (38.9 mg,
91%). Anal. Calcd for C23H27ClNRh: C, 60.60; H, 5.97; N, 3.07.
Found: C, 60.33; H, 5.76; N, 3.02. 1H NMR: δ 9.28 (d, 1 H, J =
5.8 Hz, HCdN), 7.74 (d, 2 H, J = 4.7 Hz), 7.47 (d, 1 H, J = 7.5
Hz), 7.47 (d, 1 H, J = 7.6 Hz), 7.35 (dd, 1 H, J = 7.6, 1.2 Hz),
7.23 (dd, 1 H, J = 4.5, 1.2 Hz), 7.05 (td, 1 H, J = 7.6, 1.1 Hz),
3.92 (qd, 1 H, J = 7.0, 2.1 Hz, CHCH3), 1.68 (d, 3 H, J = 7.0 Hz,
CHCH3), 1.22 (s, 15 H, C5Me5). 13C NMR: δ 158.25, 155.48
(HCdN), 150.31, 137.43, 136.76, 129.88, 129.06, 122.88, 122.78,
122.52, 122.00, 94.16 (d, J = 6.8 Hz, C5Me5), 33.49 (d, J = 18.3
Hz, CHCH3), 19.07 (CHCH3), 8.48 (C5Me5).
1b and 10b. A yellow solution of 1 (10.0 mg, 0.021 mmol) in
CD3OD (1.0 mL) in a J-Young tube with 1 atm of propylene at
room temperature turned pale yellow within 5 min. The ob-
tained products 1b and 10b in a ratio of 1.3:1 decomposed slowly
without propylene protection. 1H NMR for 1b: δ 8.49 (s, 1 H,
HCdN), 7.75 (d, 1 H, J = 6.6 Hz), 7.66 (d, 1 H, J = 7.4 Hz), 7.39
(dd, 1 H, J = 8.1, 7.5 Hz), 7.27 (dd, 1 H, J = 7.6, 7.5 Hz), 3.85 (s,
3 H, N-Me), 3.21 (m, 3 H, CH2dCHCH3), 1.82 (s, 15 H, C5Me5),
1.34 (d, 3 H, J = 4.8 Hz, CH2dCHCH3). 13C NMR for 1b: δ
179.97 (HCdN), 162.31 (Ir-C), 145.81, 135.16, 131.57, 129.57,
123.80, 99.13 (C5Me5), 64.21 (CH2dCHCH3), 52.45 (N-Me),
49.03 (CH2dCHCH3), 16.14 (CH2dCHCH3), 7.30 (C5Me5). 1H
NMR for 10b: δ 8.41 (s, 1 H, HCdN), 7.74 (d, 1 H, J = 5.3 Hz),
7.69 (d, 1 H, J = 7.8 Hz), 7.35 (dd, 1 H, J = 8.2, 7.7 Hz), 7.24
(dd, 1 H, J = 7.5, 7.1 Hz), 3.91 (s, 3 H, N-Me), 3.60 (m, 1 H,
CH2dCHCH3), 3.53 (d, 1 H, J = 8.1 Hz, CH2dCHCH3), 2.85
(d, 1 H, J = 12.2 Hz, CH2dCHCH3), 1.80 (s, 15 H, C5Me5), 0.95
(d, 3 H, J = 5.4 Hz, CH2dCHCH3). 13C NMR for 10b: δ 179.69
(HCdN), 164.51 (Ir-C), 145.90, 134.13, 131.36, 129.53, 123.84,
99.45 (C5Me5), 67.42 (CH2dCHCH3), 53.34 (N-Me), 49.42
(CH2dCHCH3), 17.42 (CH2dCHCH3), 6.99 (C5Me5).
1a. A yellow solution of 1 (10.0 mg, 0.021 mmol) in CD3OD
(1.0 mL) in a J-Young tube with 1 atm of ethylene at room
temperature turned pale yellow within 5 min. The product 1a
1
decomposed slowly without ethylene protection. H NMR: δ
8.87 (d, 1 H, J = 1.0 Hz, HCdN), 7.77 (dd, 1 H, J = 7.4, 1.4 Hz),
7.48 (d, 1 H, J = 7.8 Hz), 7.22 (td, 1 H, J = 7.5, 1.6 Hz), 7.15 (td,
1 H, J = 7.4, 1.0 Hz), 4.11 (d, 3 H, J = 1.0 Hz, N-Me), 3.16 (d, 2
H, J = 8.6 Hz, C2H4), 2.96 (d, 2 H, J = 8.4 Hz, C2H4), 1.79 (s, 15
H, C5Me5). 13C NMR: δ 180.97 (HCdN), 160.19 (Ir-C),
145.87, 135.15, 131.96, 130.71, 124.71, 99.83 (C5Me5), 88.82
(C2H4), 51.73 (N-Me), 8.78 (C5Me5).
2a. An orange solution of 2 (40.0 mg, 0.10 mmol) in methanol
(15.0 mL) was bubbled with ethylene at room temperature. The
solution turned dark red within 5 min, the solvent was concen-
trated under vacuum, and the red solid 2a was obtained (39.6
mg, 92%). Anal. Calcd for C20H27ClNRh: C, 57.22; H, 6.48; N,
3.34. Found: C, 56.86; H, 6.35; N, 3.32. 1H NMR: δ 7.98 (dd, 1
H, J = 2.6, 1.4 Hz, HCdN), 7.42 (td, 1 H, J = 7.6, 1.2 Hz), 7.36
(d, 1 H, J = 7.6 Hz), 7.11 (dd, 1 H, J = 7.4, 1.3 Hz), 7.01 (tt, 1 H,
J = 7.4, 0.8 Hz), 4.36 (dq, 1 H, J = 6.8, 2.6 Hz, CHCH3), 3.86 (d,
3 H, J = 1.0 Hz, N-Me), 1.61 (d, 3 H, J = 7.0 Hz, CHCH3), 1.30
(s, 15 H, C5Me5). 13C NMR: δ 165.01 (HCdN), 151.51, 133.76,
131.95, 130.55, 122.82, 122.66, 93.91 (d, J = 6.6 Hz, C5Me5),
52.34 (N-Me), 33.18 (d, J = 6.6 Hz, CHCH3), 18.75 (CHCH3),
8.70 (C5Me5).
3a. A yellow solution of 3 (10.0 mg, 0.019 mmol) in CD3OD
(1.0 mL) in a J-Young tube with 1 atm of ethylene at room
temperature turned pale yellow within 5 min. The product 3a
2b. An orange solution of 2 (40.0 mg, 0.10 mmol) in methanol
(15.0 mL) was bubbled with propylene at room temperature.
The solution turned dark red within 5 min, the solvent was
concentrated under vacuum, and the red solid 2b was obtained
1
decomposed slowly without ethylene protection. H NMR: δ
9.32 (d, 1 H, J = 5.8 Hz, HCdN), 7.89 (td, 1 H, J = 8.2, 0.9 Hz),
7.82 (d, 1 H, J = 8.0 Hz), 7.71 (td, J = 8.2, 0.9 Hz, 2 H), 7.58 (dd,
1
(40.4 mg, 91%). H NMR: δ 8.25 (dd, 1 H, J = 3.9, 1.4 Hz,
HCdN), 7.66 (d, 1 H, J = 7.5 Hz), 7.14 (t, 2 H, J = 7.5 Hz), 6.84
(d, 1 H, J = 7.4 Hz), 5.20 (m, 1 H, CHCH2CH3), 3.78 (d, 3 H,
J = 1.0 Hz, N-Me), 2.09 (m, 2 H, CHCH2CH3), 1.66 (s, 15 H,
(35) Kang, J. W.; Moseley, K.; Maitlis, P. M. J. Am. Chem. Soc. 1969,
91, 5970.

4602 Organometallics, Vol. 29, No. 20, 2010
Li et al.
C5Me5), 1.28 (t, 3 H, J = 7.2 Hz, CHCH2CH3). 13C NMR: δ
172.78 (HCdN), 144.93, 144.16, 142.22, 134.89, 130.14, 121.45,
116.66, 96.08 (d, J = 6.2 Hz, C5Me5), 49.06 (N-Me), 24.75
(CHCH2CH3), 9.56 (C5Me5), 9.43 (CHCH2CH3).
1.88 (s, 15 H, C5Me5). 13C NMR: δ 166.51 (Ir-C), 165.56
(HCdN), 155.62, 144.96, 143.82, 141.04, 136.49, 132.02,
126.11, 126.08, 125.76, 120.79, 101.61 (C5Me5), 9.24 (C5Me5).
4c. An orange solution of 4 (40.0 mg, 0.094 mmol) in metha-
nol (15.0 mL) was bubbled with carbon monoxide at room
temperature. The solution turned light yellow within 5 min, the
solvent was concentrated under vacuum, and the light yellow
solid 4c was obtained (41.2 mg, 97%). 1H NMR: δ 9.01 (d, 1 H,
J = 5.4 Hz, HCdN), 8.06 (td, 1 H, J = 7.9, 1.1 Hz), 7.99 (d, 2 H,
J = 7.1 Hz), 7.80 (dd, 1 H, J = 7.4, 1.8 Hz), 7.73 (td, 1 H, J =
6.6, 1.4 Hz), 7.49 (dd, 1 H, J = 7.3, 1.3 Hz), 7.32 (m, 2 H), 1.89 (s,
15 H, C5Me5). 13C NMR: δ 186.65 (d, J = 74.9 Hz, Rh-C),
165.55, 164.76 (d, J = 26.4 Hz), 155.88, 145.40, 141.85, 138.31,
133.30, 127.80, 127.18, 126.88, 122.33, 107.54 (d, J = 4.7 Hz,
C5Me5), 11.12 (C5Me5).
3b and 30b. A yellow solution of 3 (10.0 mg, 0.019 mmol) in
CD3OD (1.0 mL) in a J-Young tube with 1 atm of propylene at
room temperature turned pale yellow within 5 min. The ob-
tained products 3b and 30b in a ratio of 2.0:1 decomposed slowly
without propylene protection. 1H NMR for 3b: δ 8.56 (d, 1 H,
J = 5.7 Hz, HCdN), 8.14 (d, 1 H, J = 7.6 Hz), 7.99 (dd, 1 H,
J = 7.8 Hz), 7.91 (d, 1 H, J = 7.6 Hz), 7.65 (d, 1 H, J = 7.7 Hz),
7.39 (dd, 2 H, J = 6.7, 6.3 Hz), 7.28 (dd, 1 H, J = 7.4, 5.3 Hz),
3.38 (m, 1 H, CH2dCHCH3), 3.18 (d, 1 H, J = 6.7 Hz,
CH2dCHCH3), 1.87 (br, 1 H, CH2dCHCH3), 1.66 (s, 15 H,
C5Me5), 1.18 (br, 3 H, CH2dCHCH3). 13C NMR for 3b: δ
166.74 (Ir-C), 155.96, 153.57 (HCdN), 143.34, 139.76, 135.19,
130.89, 125.20, 124.38, 123.96, 120.14, 99.18 (C5Me5), 67.26
(CH2dCHCH3), 56.09 (CH2dCHCH3), 16.34 (CH2dCHCH3),
1d. A mixture of 1 (40.0 mg, 0.083 mmol) and tert-butyliso-
cyanide (11.0 μL, 0.095 mmol) were stirred at room temperature
in 15.0 mL of methanol for 3 h. The product obtained was
washed with hexane to remove excess substrate. The light yellow
compound 1d was isolated (43.6 mg, 93%). Anal. Calcd for
1
7.00 (C5Me5). H NMR for 30b: δ 8.63 (d, 1 H, J = 5.9 Hz,
HCdN), 8.12 (d, 1 H, J = 6.7 Hz), 8.01 (m, 1 H), 7.91 (d, 1 H,
J = 7.6 Hz), 7.69 (d, 1 H, J = 7.4 Hz), 7.35 (dd, 2 H, J = 7.7, 5.8
Hz), 7.25 (m, 1 H), 3.72 (m, 1 H, CH2dCHCH3), 2.73 (d, 1 H,
J = 12.1 Hz, CH2dCHCH3), 2.15 (m, 1 H, CH2dCHCH3), 1.64
C23H32ClN2Ir H2O (H2O found in X-ray structure): C, 47.45;
3
H, 5.89; N, 4.81. Found: C, 47.56; H, 5.81; N, 4.77. 1H NMR: δ
8.95 (s, 1 H, HCdN), 7.73 (d, 1 H, J = 6.8 Hz), 7.40 (d, 1 H, J =
7.4 Hz), 7.12 (td, 1 H, J = 7.5, 1.3 Hz), 7.07 (td, 1 H, J = 7.5, 1.3
Hz), 3.96 (s, 3 H, N-Me), 1.83 (s, 15 H, C5Me5), 1.23 (s, 9 H,
C(CH3)3). 13C NMR: δ 180.54 (HCdN), 179.75 (Ir-C), 156.26,
147.16, 134.67, 132.19, 130.46, 124.26, 96.19 (C5Me5), 59.02
(C(CH3)3), 52.68 (N-Me), 30.95 (C(CH3)3), 9.45 (C5Me5). IR
(solid): 2156 cm-1. The analogous phenylpyridyl complex 3d
displays an IR band at 2167 cm-1, but was not otherwise
characterized.
(s, 15 H, C5Me5), 0.84 (d, 3 H, J = 5.6 Hz, CH2dCHCH3). 13
C
NMR for 30b: δ 166.70 (Ir-C), 159.95, 153.63 (HCdN), 143.46,
139.71, 136.03, 130.77, 125.46, 124.44, 123.99, 119.86, 99.31
(C5Me5), 65.64 (CH2dCHCH3), 56.53 (CH2dCHCH3), 16.89
(CH2dCHCH3), 6.85 (C5Me5).
4b. An orange solution of 4 (40.0 mg, 0.094 mmol) in methanol
(15.0 mL) was bubbled with propylene at room temperature. The
solution turned dark red within 5 min, the solvent was concentrated
under vacuum, and the red solid 4b was obtained (39.8 mg, 91%).
1H NMR: δ 9.28 (d, 1 H, J = 5.6 Hz, HCdN), 7.75 (m, 2 H), 7.49
(d, 1 H, J = 7.8 Hz), 7.41 (td, 1 H, J = 7.4, 6.8 Hz), 7.34 (dd, 1 H,
J = 7.6, 1.0 Hz), 7.22 (m, 1 H), 7.02 (t, 1 H, J = 8.4 Hz), 3.74 (dt, 1
H, J = 11.3, 2.8 Hz, CHCH2CH3), 2.33 (m, 1 H, CHCH2CH3),
2.18 (m, 1 H, CHCH2CH3), 1.22 (s, 15 H, C5Me5), 0.98 (t, 3 H, J =
7.2 Hz, CHCH2CH3). 13C NMR: δ 158.50 (HCdN), 155.42,
149.81, 148.29, 137.45, 129.66 (2 C0s), 122.78, 122.53, 122.47,
121.87, 94.11 (d, J = 6.8 Hz, C5Me5), 41.89 (d, J = 6.6 Hz,
CHCH2CH3), 25.78 (CHCH2CH3), 15.19 (CHCH2CH3), 8.55
(C5Me5).
1c. A yellow solution of 1 (40.0 mg, 0.083 mmol) in methanol
(15.0 mL) was bubbled with carbon monoxide at room tem-
perature. The solution turned light yellow within 5 min, the
solvent was concentrated under vacuum, and the light yellow
solid 1c was obtained (40.2 mg, 95%). 1H NMR: δ 9.33 (s, 1 H,
HCdN), 7.91 (d, 1 H, J = 7.0 Hz), 7.44 (d, 1 H, J = 7.0 Hz), 7.23
(m, 2 H), 4.08 (s, 3 H, N-Me), 1.98 (s, 15 H, C5Me5). 13C NMR: δ
183.85 (HCdN), 164.31 (Ir-C), 150.75, 147.73, 135.44, 133.15,
131.68, 126.03, 101.47 (C5Me5), 53.24 (N-Me), 9.56 (C5Me5).
2c. An orange solution of 2 (40.0 mg, 0.10 mmol) in methanol
(15.0 mL) was bubbled with carbon monoxide at room tem-
perature. The solution turned light yellow within 5 min, the
solvent was concentrated under vacuum, and the light yellow
solid 2c was obtained (41.3 mg, 96%). 1H NMR: δ 8.96 (d, 1 H,
J = 2.9 Hz, HCdN), 7.77 (dd, 1 H, J = 7.4, 0.9 Hz), 7.38 (d, 1 H,
J = 7.6 Hz), 7.26 (td, 1 H, J = 7.5, 1.1 Hz), 7.16 (dd, 1 H, J =
7.3, 7.0 Hz), 3.84 (s, 3 H, N-Me), 1.83 (s, 15 H, C5Me5). 13C
NMR: δ 184.85 (d, J = 73.8 Hz, Rh-C), 180.01 (HCdN), 169.15
(d, J = 17.1 Hz), 145.89, 135.87, 132.56, 131.69, 126.10, 105.79
(d, J = 4.6 Hz, C5Me5), 51.21 (N-Me), 9.92 (C5Me5).
2d. The reaction was carried out as for 1d, using 2 (40.0 mg, 0.10
mmol), tert-butylisocyanide (13.0 μL, 0.11 mmol), and 15.0 mL of
methanol, RT, 3 h. The light yellow insertion compound 2d was
isolated (46.2 mg, 95%). Anal. Calcd for C23H32ClN2Rh 2H2O
3
(no X-ray structure for 2d): C, 54.07; H, 7.10; N, 5.48. Found: C,
54.23; H, 7.13; N, 5.45. 1H NMR: δ 8.81 (dd, 1 H, J = 4.0, 1.3 Hz,
HCdN), 7.74 (dd, 1 H, J = 7.4, 1.3 Hz), 7.45 (d, 1 H, J = 7.6 Hz),
7.26 (ddd, 1 H, J = 7.4, 1.3 Hz), 7.17 (td, 1 H, J = 7.4, 0.7 Hz),
3.92 (s, 3 H, N-Me), 1.82 (s, 15 H, C5Me5), 1.31 (s, 9 H, C(CH3)3).
13C NMR: δ 177.01 (HCdN), 174.17 (d, J = 28.5 Hz, Rh-C),
145.34 (2 C’s), 135.37, 131.50, 130.17, 124.59, 101.11 (d, J = 4.8
Hz, C5Me5), 59.00 (C(CH3)3), 50.70 (N-Me), 30.45 (C(CH3)3),
9.65 (C5Me5). IR(solid):2177cm-1. The analogous phenylpyridyl
complex 3d displays an IR band at 2167 cm-1, but was not
otherwise characterized.
1e. A yellow solution of 1 (40.0 mg, 0.083 mmol) in methanol
(15.0 mL) was bubbled with acetylene at room temperature. The
solution turned light yellow within 5 min, the solvent was con-
centrated under vacuum, and the bright yellow solid 1e was
1
obtained (45.4 mg, 93%). H NMR: δ 7.42 (dd, 1 H, J = 6.1,
2.6 Hz, HCdN), 7.17 (m, 2 H), 7.05 (m, 1 H), 6.70 (d, 1 H, J =
12.4 Hz), 5.14 (br, 1 H), 4.77 (dd, 1 H, J = 12.3, 10.2 Hz), 4.59 (dd,
1 H, J = 9.8, 9.0 Hz), 4.23 (d, 1 H, J = 5.4 Hz), 4.19 (d, 1 H, J =
8.8 Hz), 3.57 (s, 3 H, N-Me), 2.77 (d, 3 H, J = 5.0 Hz), 1.84 (s, 15
H, C5Me5). 13C NMR: δ 152.06 (HCdN), 145.63 (Ir-C), 142.08,
130.41, 129.14, 128.78, 127.71, 99.74 (2 C’s), 96.85 (C5Me5), 62.46,
62.39, 57.54, 55.39 (N-Me), 50.08 (2 C’s), 44.25, 8.96 (C5Me5).
2e. An orange solution of 2 (40.0 mg, 0.10 mmol) in methanol
(15.0 mL) was bubbled with acetylene at room temperature. The
solution turned dark red within 5 min, the solvent was concen-
trated under vacuum, and the red solid 2e was obtained (39.8
mg, 93%). The initial product is not stable and undergoes
3c. A yellow solution of 3 (40.0 mg, 0.077 mmol) in methanol
(15.0 mL) was bubbled with carbon monoxide at room tem-
perature. The solution turned light yellow within 5 min, the
solvent was concentrated under vacuum, and the light yellow
solid 3c was obtained (40.8 mg, 97%). 1H NMR: δ 9.00 (d, 1 H,
J = 5.7 Hz, HCdN), 8.03 (t, 1 H, J = 7.4 Hz), 7.96 (d, 1 H, J =
7.6 Hz), 7.76 (dd, 1 H, J = 5.5, 3.1 Hz), 7.70 (t, 1 H, J = 6.5 Hz),
7.46 (dd, 1 H, J = 5.8, 3.1 Hz), 7.25 (dd, 1 H, J = 5.6, 3.8 Hz),
1
additional reaction during recrystallization. H NMR: δ 8.53
(d, 1 H, J = 2.5 Hz, HCdN), 8.17 (dd, 1 H, J = 9.6, 4.7 Hz), 7.37
(m, 1 H), 7.29 (d, 1 H, J = 9.6 Hz), 7.21 (d, 1 H, J = 7.9 Hz), 7.16
(d, 2 H, J = 4.2 Hz), 3.88 (d, J = 1.3 Hz, N-Me), 1.32 (s, 15 H,
C5Me5). 13C NMR: δ 171.03 (HCdN), 166.54 (d, J = 29.8 Hz,
Rh-C), 140.75, 137.88, 133.20, 131.85, 131.46, 130.84, 124.90,
95.46 (d, J = 6.3 Hz, C5Me5), 56.31 (N-Me), 9.06 (C5Me5).

Article
3e. A yellow solution of 3 (40.0 mg, 0.077 mmol) in methanol
Organometallics, Vol. 29, No. 20, 2010 4603
15.0 mL of methanol, RT, 3 h. The bright yellow insertion
compound 1g was isolated (46.5 mg, 94%). Anal. Calcd for
C24H31ClNO2Ir: C, 48.60; H, 5.27; N, 2.36. Found: C, 48.46; H,
5.28; N, 2.34. 1H NMR: δ 8.56 (s, 1 H, HCdN), 7.49 (d, 1 H, J =
7.8 Hz), 7.42 (t, 1 H, J = 7.5 Hz), 7.21 (t, 1 H, J = 7.4 Hz), 7.10
(d, 1 H, J = 7.6 Hz), 4.23 (m, 2 H, CH2CH3), 3.90 (s, 3 H,
N-Me), 2.34 (s, 3 H, Me), 1.33 (t, 3 H, J = 7.2 Hz, CH2CH3),
1.30 (s, 15 H, C5Me5). 13C NMR: δ 176.90 (CdO), 170.50
(HCdN), 146.59 (Ir-C), 142.03, 132.63 (2 C’s), 131.85, 130.69,
130.59, 125.40, 88.30 (C5Me5), 58.79 (CH2CH3), 56.63 (N-Me),
23.38 (Me), 15.16 (CH2CH3), 8.50 (C5Me5).
2g. The reaction was carried out as for 1d, using 2 (40.0 mg,
0.10 mmol), ethyl 2-butynoate (15.0 μL, 0.13 mmol), and
15.0 mL of methanol, RT, 3 h. The red insertion compound
2g was isolated (49.8 mg, 97%). 1H NMR: δ 7.85 (m, 1 H,
HCdN), 7.42 (m, 2 H), 7.22 (m, 1 H), 7.01 (m, 1 H), 4.44 (dq, 2
H, J = 7.1, 3.3 Hz, CH2CH3), 3.25 (d, 3 H, J = 5.4 Hz, N-Me),
2.31 (s, 3 H, Me), 1.57 (s, 15 H, C5Me5), 1.43 (t, 3 H, J = 7.1 Hz,
CH2CH3). 13C NMR: δ 166.51 (CdO), 129.21, 128.21, 126.03
(d, J = 3.1 Hz), 122.21, 120.16, 98.65 (d, J = 7.1 Hz), 98.27 (d,
J = 7.7 Hz, C5Me5), 94.28 (br), 89.05 (d, J = 5.6 Hz), 85.81 (d,
J = 8.7 Hz), 72.29 (d, J = 8.7 Hz, N-Me), 62.53 (CH2CH3),
32.84 (Me), 14.68 (CH2CH3), 8.51 (C5Me5).
(15.0 mL) was bubbled with acetylene at room temperature. The
solution turned bright red within 5 min, the solvent was con-
centrated under vacuum, and the bright red solid 3e was ob-
tained (40.7 mg, 97%). Anal. Calcd for C23H25ClNIr: C, 50.86;
H, 4.64; N, 2.58. Found: C, 50.52; H, 4.51; N, 2.50. 1H NMR: δ
9.36 (dd, 1 H, J = 5.9, 1.5 Hz, HCdN), 8.40 (d, 1 H, J = 10.7
Hz), 7.67 (td, 1 H, J = 7.7, 1.6 Hz), 7.55 (d, 1 H, J = 10.7 Hz),
7.32 (m, 2 H), 7.22 (d, 1 H, J = 7.8 Hz), 7.17 (m, 1 H), 7.10 (m, 2
H), 1.30 (s, 15 H, C5Me5). 13C NMR: δ 165.23, 156.15 (Ir-C),
153.16 (HCdN), 144.23, 137.47, 136.47, 133.28, 130.63, 130.43,
128.83, 128.19, 124.49, 123.51, 87.61 (C5Me5), 8.88 (C5Me5).
4e. An orange solution of 4 (40.0 mg, 0.094 mmol) in
methanol (15.0 mL) was bubbled with acetylene at room
temperature. The solution turned dark red within 5 min, the
solvent was concentrated under vacuum, and the red solid 4e
was obtained (40.3 mg, 95%). Anal. Calcd for C23H25ClNRh: C,
1
60.87; H, 5.55; N, 3.09. Found: C, 60.44; H, 5.56; N, 3.07. H
NMR: δ 9.48 (dd, 1 H, J = 5.8, 1.4 Hz, HCdN), 8.24 (dd, 1 H,
J = 9.4, 4.8 Hz), 7.71 (td, 1 H, J = 7.7, 1.7 Hz), 7.40-7.28 (m, 4
H), 7.19 (m, 3 H), 1.28 (s, 15 H, C5Me5). 13C NMR: δ 167.36 (d,
J = 29.4 Hz), 164.72, 155.51 (HCdN), 142.17, 137.39, 136.05,
133.39, 130.73, 130.69, 128.89, 128.04, 124.86, 122.81, 95.53 (d,
J = 6.5 Hz, C5Me5), 9.14 (C5Me5).
1f. The reaction was carried out as for 1d, using 1 (40.0 mg,
0.083 mmol), phenylacetylene (21.0 μL, 0.19 mmol), and 15.0
mL of methanol, RT, 3 h. The bright red insertion compound 1f
was isolated (50.8 mg, 89%). 1H NMR: δ 8.42 (s, 1 H, HCdN),
7.95 (d, 1 H, J = 7.6 Hz), 7.79-7.67 (m, 5 H), 7.46-7.33 (m, 8
H), 6.74 (s, 1 H), 6.01 (s, 1 H), 3.82 (s, 3 H, N-Me), 1.72 (s, 15 H,
C5Me5). 13C NMR: δ 168.73 (HCdN), 149.36 (Ir-C), 136.12,
134.93, 134.76, 133.33, 131.96, 130.86, 129.63 (2 C’s), 129.02 (2
C’s), 128.93, 128.71, 128.67, 128.60 (2 C’s), 128.19, 127.78,
127.55 (2 C’s), 127.45, 121.02, 98.51 (C5Me5), 50.10 (N-Me),
8.99 (C5Me5).
3g. The reaction was carried out as for 1d, using 3 (40.0 mg,
0.077 mmol), ethyl 2-butynoate (12.0 μL, 0.10 mmol), and 15.0
mL of methanol, RT, 3 h. The bright yellow insertion compound
3g was isolated (47.2 mg, 97%). Anal. Calcd for C27H31ClNO2Ir:
C, 51.54; H, 4.97; N, 2.23. Found: C, 51.10; H, 4.96; N, 2.24. 1H
NMR: δ9.46 (dd, 1 H, J = 6.0, 1.6Hz, HCdN), 7.71 (td, 1 H, J =
7.7, 1.7 Hz), 7.53 (dd, 1 H, J = 8.0, 1.2 Hz), 7.42 (m, 2 H), 7.21 (td,
1 H, J = 7.5, 1.1 Hz), 7.15 (td, 1 H, J = 7.5, 1.1 Hz), 7.06 (dd, 1 H,
J = 7.8, 1.3 Hz), 4.18 (q, 2 H, J = 7.2 Hz, CH2CH3), 2.34 (s, 3 H,
Me), 1.28 (t, 3H, J =7.2Hz, CH2CH3), 1.25 (s, 15 H, C5Me5). 13
C
NMR: δ 176.97 (CdO), 164.49 (Ir-C), 155.22 (HCdN), 147.37,
142.63, 137.95, 137.90, 133.63, 133.00, 129.68, 128.99, 127.35,
125.25, 123.70, 88.15 (C5Me5), 58.63 (CH2CH3), 22.99 (Me),
15.09 (CH2CH3), 8.53 (C5Me5).
2f. The reaction was carried out as for 1d, using 2 (40.0 mg,
0.10 mmol), phenylacetylene (25.0 μL, 0.23 mmol), and 15.0 mL
of methanol, RT, 3 h. The dark red insertion compound 2f was
isolated (51.5 mg, 85%). 1H NMR: δ 8.11 (d, 1 H, J = 3.2 Hz,
HCdN), 8.01 (d, 1 H, J = 7.6 Hz), 7.76-7.13 (m, 13 H), 6.92 (s,
4g. The reaction was carried out as for 1d, using 4 (40.0 mg,
0.094 mmol), ethyl 2-butynoate (12.0 μL, 0.10 mmol), and
15.0 mL of methanol, RT, 3 h. The red insertion compound 4g
was isolated(49.5mg, 98%). Anal. Calcd for C27H31ClNO2Rh: C,
60.06; H, 5.79; Cl, 6.57; N, 2.59. Found: C, 59.69; H, 5.86; N, 2.55.
1H NMR: δ 9.55 (dd, 1 H, J = 5.9, 1.3 Hz, HCdN), 7.73 (td, 1 H,
J = 7.6, 1.6 Hz), 7.58 (dd, 1 H, J = 7.8, 0.8 Hz), 7.44 (td, 1 H, J =
7.5, 1.2 Hz), 7.40 (d, 1 H, J = 7.6 Hz), 7.21 (m, 2 H), 7.14 (dd, 1 H,
J = 7.6, 1.0 Hz), 4.18 (m, 2 H, CH2CH3), 2.25 (s, 3 H, Me), 1.28 (t,
3 H, J = 7.2 Hz, CH2CH3), 1.24 (s, 15 H, C5Me5). 13C NMR: δ
175.10 (CdO), 163.91 (Ir-C), 154.87 (HCdN), 154.03 (d, J = 34.5
Hz, Rh-C), 145.75, 137.73, 137.33, 133.66, 132.32, 129.78, 129.01,
127.20, 125.49, 123.05, 95.91 (d, J = 6.7 Hz, C5Me5), 58.84
(CH2CH3), 23.53 (Me), 14.94 (CH2CH3), 8.74 (C5Me5).
1 H), 6.08 (s, 1 H), 3.30 (s, 3 H, N-Me), 1.70 (s, 15 H, C5Me5). 13
C
NMR: δ 165.70, 138.93, 136.60, 130.49, 130.19, 130.09, 129.79,
129.56, 128.95, 128.79, 128.66, 128.58, 127.57, 126.59, 103.35 (d,
J = 22.3 Hz), 103.12 (d, J = 28.2 Hz), 101.31 (d, J = 30.6 Hz),
94.33 (d, J = 39.1 Hz, C5Me5), 86.32 (d, J = 28.4 Hz), 84.31 (d,
J = 30.4 Hz), 57.38 (N-Me), 9.60 (C5Me5).
3f. The reaction was carried out as for 1d, using 3 (40.0 mg,
0.077 mmol), phenylacetylene (18.0 μL, 0.16 mmol), and 15.0
mL of methanol, RT, 3 h. The bright red insertion compound 3f
was isolated (52.4 mg, 94%). 1H NMR: δ 9.00 (dd, 1 H, J = 5.9,
1.3 Hz, HCdN), 7.68 (d, 1 H, J = 6.8 Hz), 7.61 (td, 1 H, J = 7.4,
1.1 Hz), 7.48-7.33 (m, 6 H), 7.19-6.99 (m, 8 H), 6.91 (t, 1 H,
1h and 10h. The reaction was carried out as for 1d, using 1 (40.0
mg, 0.083 mmol), ethyl phenylpropiolate (17.0 μL, 0.10 mmol),
and 15.0 mL of methanol, RT, 3 h. The bright yellow inser-
tion compounds 1h and 10h with a ratio of 1:2.4 were obtained
(51.2 mg, 94%). The two regioisomers were separated by
column chromatography using 2% MeOH/CH2Cl2 as the elu-
ent. Anal. Calcd for C27H31ClNO2Rh: C, 53.16; H, 5.08; N,
J = 7.3 Hz), 6.30 (s, 1 H), 4.33 (s, 1 H), 1.67 (s, 15 H, C5Me5). 13
C
NMR: δ 157.83 (HCdN), 156.50 (Ir-C), 154.72, 139.54,
135.62, 135.54, 133.75, 131.81, 130.91, 130.47, 128.78, 128.59,
128.22, 127.40, 127.23, 126.23, 125.94, 124.78, 119.46, 101.91,
98.08, 95.54 (C5Me5), 53.60, 51.00, 8.82 (C5Me5).
4f. The reaction was carried out as for 1d, using 4 (40.0 mg,
0.094 mmol), phenylacetylene (22.0 μL, 0.20 mmol), and 15.0
mL of methanol, RT, 3 h. The red insertion compound 4g was
isolated (53.6 mg, 91%). 1H NMR: δ 9.78 (dd, 1 H, J = 5.8, 1.1
Hz, HCdN), 7.79-7.71 (m, 2 H), 7.48-7.35 (m, 5 H), 7.27-7.15
(m, 7 H), 7.10-7.03 (m, 5 H), 1.28 (s, 15 H, C5Me5). 13C NMR: δ
175.77 (d, J = 126.2 Hz, Rh-C), 164.17, 155.12 (HCdN),
153.99, 141.93, 137.38, 136.03, 134.76, 133.16, 131.86, 130.48,
130.29, 130.03, 129.08, 128.99, 128.87, 128.04, 127.68, 127.58,
127.19, 126.64, 125.10, 124.56, 122.85, 95.88 (d, J = 26.0 Hz,
C5Me5), 9.21 (C5Me5).
1
2.14. Found: C, 53.09; H, 5.18; N, 2.16. The H NMR for the
major regioisomer 10h: δ 8.71 (d, 1 H, J = 1.4 Hz, HCdN), 7.39
(m, 2 H), 7.29 (m, 1 H), 7.23 (d, 1 H, J = 8.0 Hz), 7.16 (br, 2 H),
6.95 (m, 1 H), 6.84 (br, 2 H), 3.89 (d, 3 H, J = 1.2 Hz, N-Me),
3.77 (m, 1 H, CH2CH3), 3.64 (m, 1 H, CH2CH3), 1.34 (s, 15 H,
C5Me5), 0.77 (t, 3 H, J = 7.2 Hz, CH2CH3). 13C NMR for 10h: δ
171.96 (CdO), 170.61 (HCdN), 166.58 (Ir-C), 153.29, 141.57,
135.46, 132.90, 132.46, 131.06, 130.89, 130.59, 126.06, 125.81,
124.28, 88.51 (C5Me5), 60.09 (CH2CH3), 56.48 (N-Me), 13.65
(CH2CH3), 8.65 (C5Me5).
1g. The reaction was carried out as for 1d, using 1 (40.0 mg,
0.083 mmol), ethyl 2-butynoate (12.0 μL, 0.10 mmol), and
2h and 20h. The reaction was carried out as for 1d, using 2 (40.0
mg, 0.10 mmol), ethyl phenylpropiolate (20.0 μL, 0.12 mmol),

4604 Organometallics, Vol. 29, No. 20, 2010
Li et al.
and 15.0 mL of methanol, RT, 3 h. The red insertion compounds
2h and 20h with a ratio of 1:4.0 were obtained (54.8 mg, 95%).
The two regioisomers were separated by column chromatogra-
Ir-C), 139.90 (q, J = 27.9 Hz), 138.07, 132.69, 131.88, 131.43,
130.86, 128.18 (q, J = 279 Hz, CF3), 127.42, 89.10 (C5Me5),
61.50 (CH2CH3), 57.13 (N-Me), 14.10 (CH2CH3), 8.47 (C5Me5).
1H NMR for the minor regioisomer 1i: δ 8.63 (s, 1 H, HCdN),
7.68 (d, 1 H, J = 8.0 Hz), 7.50 (td, 1 H, J = 7.7, 1.3 Hz), 7.36 (td,
1 H, J = 7.5, 0.8 Hz), 7.22 (d, 1 H, J = 7.8 Hz), 4.26 (q, 2 H, J =
7.1 Hz, CH2CH3), 3.89 (d, 3 H, J = 1.3 Hz, N-Me), 1.32 (t, 3 H,
J = 7.1 Hz, CH2CH3), 1.29 (s, 15 H, C5Me5). 13C NMR for 1i: δ
174.46 (q, J = 6.0 Hz, Ir-C), 170.65 (HCdN), 160.21 (CdO),
137.82, 134.74, 131.90, 131.61 (q, J = 2.6 Hz), 130.64, 127.16
(q), 126.98, 123.88 (q, J = 280.8 Hz, CF3), 89.40 (C5Me5), 59.10
(CH2CH3), 56.49 (N-Me), 14.86 (CH2CH3), 8.28 (C5Me5).
2i and 20i. The reaction was carried out as for 1d, using 2 (40.0
mg, 0.10 mmol), ethyl 4,4,4-trifluoro-2-butynoate (18.0 μL, 0.12
mmol), and 15.0 mL of methanol, RT, 3 h. The bright yellow
insertion compounds 2i and 20i with a ratio of 1:1.7 were ob-
tained (54.2 mg, 95%). The two regioisomers were separated by
column chromatography using 1% MeOH/CH2Cl2 as the elu-
ent. Anal. Calcd for C24H28ClF3NO2Rh: C, 51.67; H, 5.06; N,
2.51. Found: C, 51.70; H, 5.12; N, 2.49. 1H NMR for the major
regioisomer 20i: δ 8.65 (d, 1 H, J = 1.7 Hz, HCdN), 8.21 (d, 1 H,
J = 8.0 Hz), 7.46 (td, 1 H, J = 7.6, 1.4 Hz), 7.38 (td, 1 H, J = 7.6,
1.2 Hz), 7.26 (d, 1 H, J = 7.4 Hz), 4.20 (m, 1 H, CH2CH3), 4.00
(m, 1 H, CH2CH3), 3.88 (s, 3 H, N-Me), 1.24 (s, 15 H, C5Me5),
1.21 (t, 3 H, J = 7.2 Hz, CH2CH3). 13C NMR for 20i: δ170.72
(HCdN), 170.01 (CdO), 158.05 (m, Rh-C), 138.94 (q, J = 7.4
Hz), 136.79, 132.02, 131.97, 131.31, 130.79, 127.57, 126.69 (q,
J= 276.4 Hz, CF3), 96.69 (d, J=6.0Hz,C5Me5), 61.58 (CH2CH3),
56.65 (N-Me), 14.06 (CH2CH3), 8.73 (C5Me5). 1H NMR for the
minor regioisomer 2i:δ8.59 (d, 1 H, J=1.6Hz, HCdN), 7.74 (d, 1
H, J = 8.0 Hz), 7.50 (td, 1 H, J = 7.6, 1.4 Hz), 7.38 (td, 1 H, J =
7.6, 1.0 Hz), 7.29 (dd, 1 H, J = 7.7, 1.0 Hz), 4.22 (m, 2 H,
CH2CH3), 3.82 (d, 3 H, J = 1.2 Hz, N-Me), 1.30 (t, 3 H, J = 7.2
Hz, CH2CH3), 1.26 (s, 15 H, C5Me5). 13C NMR for 2i: δ 173.85
(d, J = 33.6 Hz, Rh-C), 173.08 (CdO), 170.37 (HCdN), 136.37,
134.22, 132.01, 131.51 (q, J = 3.0 Hz), 130.52, 127.16, 125.41 (q,
J = 26.4 Hz), 122.25 (q, J = 280.8 Hz, CF3), 96.93 (d, J = 6.5 Hz,
C5Me5), 59.34 (CH2CH3), 55.93 (N-Me), 14.71 (CH2CH3), 8.56
(C5Me5).
1
phy using 2% MeOH/CH2Cl2 as the eluent. H NMR for the
major regioisomer 20h: δ 8.65 (s, 1 H, HCdN), 7.42 (br, 1 H),
7.25-7.20 (m, 8 H), 3.95 (m, 1 H, CH2CH3), 3.91 (s, 3 H, N-Me),
3.68 (m, 1 H, CH2CH3), 1.37 (s, 15 H, C5Me5), 0.61 (m, 3 H,
CH2CH3). 13C NMR for 20h: δ 172.85 (CdO), 170.60 (HCdN),
159.63 (d, J = 35.0 Hz, Rh-C), 140.18, 134.20, 132.01, 130.46,
129.25, 128.73, 128.63, 127.89, 126.62, 125.85, 124.22, 96.23 (d,
J = 6.5 Hz, C5Me5), 69.22 (CH2CH3), 56.33 (N-Me), 14.25
(CH2CH3), 8.78 (C5Me5).
3h and 30h. The reaction was carried out as for 1d, using 3 (40.0
mg, 0.077 mmol), ethyl phenylpropiolate (16.0 μL, 0.095 mmol),
and 15.0 mL of methanol, RT, 3 h. The bright yellow insertion
compounds 3h and 30h with a ratio of 1:1.7 were obtained (51.8
mg, 97%). The two regioisomers were separated by column
1
chromatography using 0.5% MeOH/CH2Cl2 as the eluent. H
NMR for the major regioisomer 30h: δ 9.60 (dd, 1 H, J = 6.0, 1.2
Hz, HCdN), 7.78 (td, 1 H, J = 7.6, 1.5 Hz), 7.56 (dd, 1 H, J =
7.8, 1.0 Hz), 7.43 (m, 3 H), 7.29 (d, 1 H, J = 7.8 Hz), 7.18 (m, 3
H), 7.02 (br, 2 H), 6.90 (t, 1 H, J = 7.3 Hz), 3.74 (m, 1 H,
CH2CH3), 3.62 (m, 1 H, CH2CH3), 1.28 (s, 15 H, C5Me5), 0.74 (t,
3 H, J = 7.1 Hz, CH2CH3). 13C NMR for 30h: δ 171.89 (CdO),
167.98 (Ir-C), 164.32, 155.23 (HCdN), 154.13, 142.62, 138.88,
137.92, 135.47, 133.68, 130.54, 129.34, 127.69, 127.55, 126.08,
125.93, 124.17, 123.74, 88.69 (C5Me5), 60.06 (CH2CH3), 13.83
(CH2CH3), 8.95 (C5Me5). 1H NMR for the minor regioisomer
3h: δ 9.40 (dd, 1 H, J = 5.8, 1.0 Hz, HCdN), 7.76 (td, 1 H, J =
7.6, 1.2 Hz), 7.45 (d, 1 H, J = 7.8 Hz), 7.23 (dd, 1 H, J = 7.6, 1.2
Hz), 7.18 (td, 1 H, J = 7.6, 1.2 Hz), 7.16-7.02 (m, 8 H), 3.87 (m,
1 H, CH2CH3), 3.63 (m, 1 H, CH2CH3), 1.32 (s, 15 H, C5Me5),
0.54 (br, 3 H, CH2CH3). 13C NMR for 3h: δ 177.01 (CdO),
164.37 (Ir-C), 155.44 (HCdN), 147.91, 146.43, 145.93, 138.39,
138.31, 133.57, 132.94, 130.08, 128.77, 127.79 (2 C’s), 127.35,
125.87, 125.57, 124.10, 88.48 (C5Me5), 58.07 (CH2CH3), 13.99
(CH2CH3), 8.55 (C5Me5). For 3h and 30h, Anal. Calcd for
C32H33ClIrNO2: C, 55.60; H, 4.81; N, 2.03. Found: C, 55.85;
H, 4.95; N, 1.97.
4h and 40h. The reaction was carried out as for 1d, using 4 (40.0
mg, 0.094 mmol), ethyl phenylpropiolate (20.0 μL, 0.12 mmol),
and 15.0 mL of methanol, RT, 3 h. The red insertion compounds
4h and 40h with a ratio of 1:1.2 were obtained (53.4 mg, 95%).
The two regioisomers were separated by column chromatogra-
3i and 30i. The reaction was carried out as for 1d, using 3 (40.0
mg, 0.077 mmol), ethyl 4,4,4-trifluoro-2-butynoate (14.0 μL,
0.095 mmol), and 15.0 mL of methanol, RT, 3 h. The bright
yellow insertion compounds 3i and 30i with a ratio of 1:2.2 were
obtained (52.0 mg, 98%). The two regioisomers were separated
by column chromatography using 0.5% MeOH/CH2Cl2 as the
eluent. Anal. Calcd for C27H28ClF3NO2Ir: C, 47.47; H, 4.13; N,
2.05. Found: C, 47.33; H, 4.03; N, 2.06. 1H NMR for the major
regioisomer 30i: δ 9.59 (dd, 1 H, J = 6.0, 1.2 Hz, HCdN), 8.24
(d, 1 H, J = 8.0 Hz), 7.75 (td, 1 H, J = 7.7, 1.5 Hz), 7.44 (m, 2 H),
7.33 (td, 1 H, J = 7.6, 1.1 Hz), 7.20 (td, 1 H, J = 6.8, 1.5 Hz),
7.07 (dd, 1 H, J = 7.7, 1.0 Hz), 4.18 (m, 1 H, CH2CH3), 3.96 (m,
1 H, CH2CH3), 1.22 (s, 15 H, C5Me5), 1.16 (t, 3 H, J = 7.2 Hz,
CH2CH3). 13C NMR for 30i: δ 171.29 (CdO), 163.53 (HCdN),
155.27, 147.06 (q, J = 28.3 Hz, Ir-C), 140.12 (q, J = 6.0 Hz),
139.19, 138.45, 138.17, 133.36, 130.86, 129.03, 128.16 (q, J =
279.8 Hz, CF3), 127.20 (2 C’s overlap), 124.05, 88.95 (C5Me5),
61.35 (CH2CH3), 14.06 (CH2CH3), 8.52 (C5Me5). 1H NMR for
the minor regioisomer 3i: δ 9.41 (dd, 1 H, J = 6.0, 1.3 Hz,
HCdN), 7.77 (td, 1 H, J = 7.7, 1.6 Hz), 7.69 (d, 1 H, J = 8.0
Hz), 7.47 (m, 2 H), 7.32 (td, 1 H, J = 7.6, 1.0 Hz), 7.18 (td, 1 H,
J = 6.8, 1.4 Hz), 7.10 (dd, 1 H, J = 7.7, 1.2 Hz), 4.18 (m, 2 H,
CH2CH3), 1.24 (s, 15 H, C5Me5), 1.23 (t, 3 H, J = 7.2 Hz,
CH2CH3). 13C NMR for 3i: δ 174.47 (m Ir-C), 163.56 (HCdN),
160.51 (CdO), 154.95, 139.97, 138.32 (2 C’s overlap), 133.82,
130.84 (m), 128.73, 126.91, 126.85, 126.70, 123.93, 123.47 (q,
J = 280.8 Hz, CF3), 89.05 (C5Me5), 58.78 (CH2CH3), 14.55
(CH2CH3), 8.18 (C5Me5).
1
phy using 1% MeOH/CH2Cl2 as the eluent. H NMR for the
major regioisomer 40h: δ 9.52 (d, 1 H, J = 5.8 Hz, HCdN), 7.78
(td, 1 H, J = 7.6, 1.2 Hz), 7.46 (d, 1 H, J = 7.6 Hz), 7.26 (m, 1 H),
7.21-7.05 (m, 9 H), 3.91 (m, 1 H, CH2CH3), 3.61 (m, 1 H,
CH2CH3), 1.32 (s, 15 H, C5Me5), 0.53 (m, 3 H, CH2CH3). 13
C
NMR for 40h: δ 175.13 (CdO), 163.84, 160.18 (d, J = 34.7 Hz,
Rh-C), 155.01 (HCdN), 145.82, 144.45, 140.25, 138.20, 137.79,
133.59, 133.08, 129.63, 128.75, 127.80, 127.21, 125.92, 125.79,
123.48, 96.19 (d, J = 6.7 Hz, C5Me5), 58.31 (CH2CH3), 13.97
(CH2CH3), 8.79 (C5Me5). For 4h and 40h, Anal. Calcd for
C32H33ClNO2Rh: C, 63.85; H, 5.53; N, 2.33. Found: C, 64.22;
H, 5.32; N, 2.23.
1i and 10i. The reaction was carried out as for 1d, using 1 (40.0
mg, 0.83 mmol), ethyl 4,4,4-trifluoro-2-butynoate (16.0 μL, 0.11
mmol), and 15.0 mL of methanol, RT, 3 h. The bright yellow
insertion compounds 1i and 10i with a ratio of 1:1.9 were
obtained (52.3 mg, 97%). The two regioisomers were separated
by column chromatography using 1% MeOH/CH2Cl2 as the
eluent. Anal. Calcd for C24H28ClF3NO2Ir: C, 44.54; H, 4.36; N,
2.16. Found: C, 44.50; H, 4.29; N, 2.11. 1H NMR for the major
regioisomer 10i: δ 8.70 (d, 1 H, J = 1.1 Hz, HCdN), 8.18 (d, 1 H,
J = 7.7 Hz), 7.47 (td, 1 H, J = 7.7, 1.2 Hz), 7.37 (td, 1 H, J = 7.5,
1.2 Hz), 7.18 (dd, 1 H, J = 7.7, 1.1 Hz), 4.24 (m, 1 H, CH2CH3),
4.03 (m, 1 H, CH2CH3), 3.94 (d, 3 H, J = 1.4 Hz, N-Me), 1.28 (s,
15 H, C5Me5), 1.24 (t, 3 H, J = 7.2 Hz, CH2CH3). 13C NMR for
10i: δ 171.17 (CdO), 170.72 (HCdN), 145.58 (q, J = 27.9 Hz,
4i and 40i. The reaction was carried out as for 1d, using 4 (40.0
mg, 0.094 mmol), ethyl 4,4,4-trifluoro-2-butynoate (16.0 μL,
0.11 mmol), and 15.0 mL of methanol, RT, 3 h. The red insertion

Article
Organometallics, Vol. 29, No. 20, 2010 4605
compounds 4i and 40i with a ratio of 1:2.0 were obtained (54.6 mg,
98%). The two regioisomers were separated by column chroma-
tography using 1% MeOH/CH2Cl2 as the eluent. Anal. Calcd for
C27H28ClF3NO2Rh: C, 54.61; H, 4.75; N, 2.36. Found: C, 54.76;
H, 4.78; N, 2.33. 1H NMRfor the major regioisomer 40i: δ 9.69 (d,
1 H, J = 4.7 Hz, HCdN), 8.27 (dd, 1 H, J = 8.0, 0.8 Hz), 7.78 (td,
1 H, J = 7.6, 1.6 Hz), 7.47 (td, 1 H, J = 7.7, 1.3 Hz), 7.42 (d, 1 H,
J = 7.9 Hz), 7.35 (td, 1 H, J = 7.6, 1.2 Hz), 7.25 (td, 1 H, J = 6.8,
1.1 Hz), 7.14 (dd, 1 H, J = 7.7, 1.1 Hz), 4.17 (m, 1 H, CH2CH3),
3.94 (m, 1 H, CH2CH3), 1.21 (s, 15 H, C5Me5), 1.17 (t, 3 H, J =
Hz), 123.57, 122.22 (q, J = 277 Hz, CF3), 96.86 (d, J = 6.6 Hz,
C5Me5), 59.19 (CH2CH3), 14.64 (CH2CH3), 8.65 (C5Me5).
X-ray Crystal Structure Determinations. Data were collected
on a Bruker SMART APEX II CCD Platform diffractometer at
100.0(1) K. The data collection was carried out using Mo KR
radiation. The intensity data were corrected for absorption. The
structures were solved using SIR 9736 and refined using
SHELXL-97.37 All non-hydrogen atoms were refined with
anistropic displacement parameters. All hydrogen atoms were
found from the difference Fourier map and refined indepen-
dently from the carbon atoms with individual isotropic displa-
cement parameters. See Supporting Information for details.
13
7.2 Hz, CH2CH3). C NMR for 40i: δ 170.14 (CdO), 163.10
(HCdN), 159.48 (dq, J = 40.4, 28.3 Rh-C), 155.09, 139.39 (q,
J = 8.3 Hz), 138.29, 137.85, 137.72, 133.38, 130.91, 129.02, 127.45,
127.11, 126.87 (q, J= 278.8 Hz, CF3), 123.50, 96.63 (d, J=6.9Hz,
Acknowledgment. Financial support from the National
Science Foundation (CHE-0717040) is gratefully acknowl-
edged. The Center for Enabling New Technologies through
Catalysis (CENTC) Elemental Analysis Facility is also
acknowledged for use of its analytical facility (CHE-
0650456).
1
C5Me5), 61.43 (CH2CH3), 14.03 (CH2CH3), 8.82 (C5Me5). H
NMR for the minor regioisomer 4i: δ 9.49 (d, 1 H, J = 4.7 Hz,
HCdN), 7.78 (td, 1 H, J = 7.7, 1.6 Hz), 7.74 (d, 1 H, J = 8.0 Hz),
7.49 (td, 1 H, J = 7.7, 1.4 Hz), 7.44 (d, 1 H, J = 7.8 Hz), 7.34 (td, 1
H, J = 7.6, 1.0 Hz), 7.22 (td, 1 H, J = 6.6, 1.4 Hz), 7.18 (dd, 1 H,
J = 7.8, 1.2 Hz), 4.17 (m, 2 H, CH2CH3), 1.24 (s, 15 H, C5Me5),
1.22 (m, 3 H, CH2CH3). 13C NMR for 4i: δ 174.18 (d, J = 70.6 Hz,
Rh-C), 173.26 (CdO), 163.16, 154.92 (HCdN), 139.82, 138.36,
136.96, 134.05, 131.08, 128.89, 127.21, 126.94, 125.86 (q, J = 26.3
Supporting Information Available: Full structure descriptions
of compounds 2a, 4a, 4b, 2c, 1d, 3e, 4e, 1f, 2g, 3g, 4g, 10h, 30h, 10i,
20i, and 30i, cif files, and 1H and 13C NMR spectra for the
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org. The cif files have also been
deposited with the Cambridge Crystallographic Data Centre
as CCDC 786368-786383.
(36) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.;
Spagna, R. SIR97: A new program for solving and refining crystal
structures; Istituto di Cristallografia, CNR: Bari, Italy, 1999.
(37) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.