Activation of C-H and H-H bonds by dinuclear iridium complexes. Oxidative addition to highly active unsaturated 32e- diiridium species

Article abstract of DOI:10.1016/j.jorganchem.2008.07.032

Reactions of [(Cp^*Ir)₂(μ-dmpm)(μ-H)₂][OTf]₂ (1) with NaO^tBu in aromatic solvent at room temperature give [(Cp^*Ir)(H)(μ-dmpm)(μ-H)(Cp^*Ir)(Ar)][OTf] [Ar = Ph (3), p-Tol (4a), m-Tol (4b), 2-furyl (5a), 3-furyl (5b)] via intermolecular aromatic C-H activation. Treatment of [(Cp^*Ir)₂(μ-dppm)(μ-H)₂][OTf]₂ (2) with weak base (Et₂NH) results in intramolecular C-H activation of a phenyl group in the dppm ligand to give [(Cp^*Ir)(H){μ-PPh(C₆H₄)CH₂PPh₂}(μ-H)(Cp^*Ir)][OTf] (6). Reaction of 1 with NaO^tBu in tetrahydrofuran under H₂ (1 atm) results in activation of the H-H bond to give [{(Cp^*Ir)(H)}₂(μ-dmpm)(μ-H)][OTf] (7). Reaction of 1 with NaO^tBu in dichloromethane under carbon monoxide (1 atm) gives a carbonyl-bridged Ir^II-Ir^II complex, [(Cp^*Ir)₂(μ-dmpm)(μ-H)(μ-CO)][OTf] (8-OTf). These results strongly suggest that the active species in C-H and H-H bond activation starting with 1 and 2 would be unsaturated 32e^- diiridium species. The structures of 3, 5a, 6, 7, and 8-BPh₄ have been determined by X-ray diffraction methods.

Full text of DOI:10.1016/j.jorganchem.2008.07.032

Journal of Organometallic Chemistry 693 (2008) 3375–3382
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Activation of C–H and H–H bonds by dinuclear iridium complexes. Oxidative
addition to highly active unsaturated 32eꢀ diiridium species
a
a
a
a,
*
Ken-ichi Fujita a,b, , Yoshinori Takahashi , Hirohide Nakaguma , Taro Hamada , Ryohei Yamaguchi
*
a Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
b Graduate School of Global Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
a r t i c l e i n f o
a b s t r a c t
Reactions of [(Cp*Ir)2(
l
-dmpm)(
-H)(Cp*Ir)(Ar)][OTf] [Ar = Ph (3), p-Tol (4a), m-Tol (4b), 2-furyl (5a), 3-furyl
-dppm)( -H)2][OTf]2 (2) with
weak base (Et2NH) results in intramolecular C–H activation of a phenyl group in the dppm ligand to give
[(Cp*Ir)(H){ -H)(Cp*Ir)][OTf] (6). Reaction of 1 with NaOtBu in tetrahydrofuran
-PPh(C6H4)CH2PPh2}(
under H2 (1 atm) results in activation of the H–H bond to give [{(Cp*Ir)(H)}2(
-dmpm)( -H)][OTf] (7).
Reaction of 1 with NaOtBu in dichloromethane under carbon monoxide (1 atm) gives a carbonyl-bridged
l
-H)2][OTf]2 (1) with NaOtBu in aromatic solvent at room temperature
Article history:
give [(Cp*Ir)(H)(
l
-dmpm)(
l
Received 9 February 2008
Received in revised form 24 July 2008
Accepted 29 July 2008
(5b)] via intermolecular aromatic C–H activation. Treatment of [(Cp*Ir)2(
l
l
Available online 5 August 2008
l
l
l
l
Keywords:
Dinuclear complex
Iridium
C–H activation
Oxidative addition
Cooperative reactivity
IrII–IrII complex, [(Cp*Ir)2(
l-dmpm)(l-H)(l-CO)][OTf] (8-OTf). These results strongly suggest that the
active species in C–H and H–H bond activation starting with 1 and 2 would be unsaturated 32eꢀ diiridi-
um species. The structures of 3, 5a, 6, 7, and 8-BPh4 have been determined by X-ray diffraction methods.
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
from (g5-C5R5)IrI(L)(L0) (L0 = CO [5a,5b], C2H4 [6a–c], or 2-nitrile
g
[7]) under photo-irradiative or thermal conditions (Scheme 1).
In the mean time, growing interests have been focused on the
activation of organic molecules on multinuclear metal complexes.
The proximity of the metal centers can lead to the exhibition of un-
ique functionality based on ‘‘cooperative reactivity” [9]. Actually, a
number of interesting reactions on multinuclear metal complexes
involving activation of inert bond in organic molecules have been
appeared in recent years. For example, some dinuclear iridium
The studies on the activation of inert C–H bonds in organic mol-
ecules by transition metal complexes have been attracting great
interest in organometallic chemistry because of their significance
in the functionalization of hydrocarbons [1]. A number of transi-
tion metal systems capable for the C–H activation have been dis-
covered in the past decades, and some of them have been
developed as catalysts for organic synthesis [2,3]. Since the first re-
ports on the C–H activation with (g5-C5R5)Ir [R = Me (Cp*); R = H
(Cp)] complexes by Bergman [4a] and Graham [5a], their capability
for the activation of alkanes, arenes, and other inert C–H bonds has
been vigorously investigated [4–8]. Up to date, the investigations
on C–H activation by Cp*Ir and CpIr complexes have been carried
out with mononuclear complexes in many cases. The true active
species in the oxidative addition of the C–H bond to these com-
R5
L'
R5
IrI
IrIII
R'
plexes is supposed to be an unsaturated 16eꢀ 5-C5R5)IrI(L) frag-
(g
L
L
H
ment, which is generated by the reductive elimination of hydrogen
or hydrocarbon from (g5-C5R5)IrIII(R0)(H)(L) (R0 = H [4a,4b,5c], alkyl
[4c,4d], or alkenyl [6c]), or by the dissociation of neutral ligand
-L'
hν or Δ
-R'H
hν or Δ
reductive
elimination
dissociation of
neutral ligand
R5
IrI
* Corresponding authors. Address: Graduate School of Human and Environmental
Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. Tel.: +81 75 753 6827;
fax: +81 75 753 6634 (K.-i. Fujita).
L
16e− active species
E-mail addresses: fujitak@kagaku.mbox.media.kyoto-u.ac.jp (K.-i. Fujita), yama@
kagaku.mbox.media.kyoto-u.ac.jp (R. Yamaguchi).
Scheme 1.
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.07.032

3376
K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
complexes are known to exhibit high capability for the activation
of C–H and H–H bonds. Bergman reported the oxidative addition
of C–H and H–H bonds to an IrII–IrII species [(Cp*Ir)(g1 g3
, -
C3H4)(Cp*Ir)] generated by the reductive elimination of benzene
from an IrIII–IrIII complex [(Cp*Ir)(Ph)(g1 3-C3H4)( -H)(Cp*Ir)]
[10]. Oro reported the activation of olefinic C–H bonds on an IrII–IrII
species generated by the oxidation of IrI–IrI complexes [Ir2(
-1,8-
(NH)2naphth)(
2-RHC@CHR)2(PiPr3)2] [11]. Heinekey reported
the activation of hydrogen on a hydrido-bridged IrII–IrII species
,g
l
l
g
generated by the protonation of IrI–IrI complex [Cp*Ir(
l-CO)]2
[12]. In these examples, unsaturated IrII–IrII species or electroni-
cally unbalanced IrIII–IrI species must be key intermediates in the
bond activation.
2+
2+
Ph2P
Ir
PPh2
Ir
Me2P
Ir
PMe2
Ir
H
H
2
H
H
1
Cp*
Cp*
Cp*
Cp*
Fig. 1. ORTEP drawing of the cationic part of 3 with 30% thermal probability
ellipsoids. Hydrogen atoms (except hydride) are omitted for clarity. Selected (bond)
distances (Å): Ir(1)–Ir(2) = 3.190(1); Ir(1)–P(1) = 2.250(2); Ir(2)–P(2) = 2.259(2);
We have previously reported the preparation and some reactivities
of novel IrIII–IrIII complexes having a bridging diphosphine and mul-
tiple
hydrido
ligands,
[(Cp*Ir)2(
l-diphos)(l-H)2][OTf]2
Ir(1)–C(26) = 2.073(6);
H(102) = 1.39.
Ir(1)–H(101) = 1.62;
Ir(2)–H(101) = 1.77;
Ir(2)–
[diphos = bis(dimethylphosphino)methane
(dmpm)
(1) and
bis(diphenylphosphino)methane (dppm) (2)] [13,14]. Having these
dinuclear complexes 1 and 2 in hand, we have anticipated that
these complexes could generate unsaturated 32eꢀ IrII–IrII (or IrIII–
IrI) species by the abstraction of one of the bridging hydrides as a
proton, which might exhibit a high performance in the activation
of inert molecules (Eq. (1)). Bond activation by hydrido-bridged
32eꢀ diiridium species would be advantageous in view of further
development of the reaction system, because such activation could
give rise to a 34eꢀ IrIII–IrIII complex as a product, which can be still
regarded as unsaturated.
one of the iridium atoms with an Ir–C distance of 2.073(6) Å, show-
ing no interaction with another iridium center. The hydrides are
located in the difference Fourier maps. One of the hydrides is found
at bridging position and the other at terminal position, which is
coincident with the 1H NMR analysis. The iridium–iridium distance
is 3.190(1) Å, which is relatively larger than general monohydrido-
bridged iridium–iridium bond, reflecting the steric hindrance
around iridium centers by two Cp* ligands and phenyl ring. The
complex 3 would be a 34eꢀ one, if the bridging hydride is regarded
as a two-electron ligand.
+
+
2+
P
P
P
P
P
P
H+
H
or
2+ NaOtBu
+
ð1Þ
H
H
H
IrII
IrII
IrIII
IrI
IrIII
IrIII
Me2P
Ir
PMe2
Ir
Me2P
Ir
PMe2
Ir
(1.1 eq)
H
H
H
1
-
32e active species
Ar-H
r. t., 20 h
Cp*
Cp*
Cp*
Cp*
Ar
H
In this paper, we report the inter- and intra-molecular activa-
ð2Þ
tion of aromatic C–H bonds and hydrogen induced by the deproto-
nation of 1 and 2 [15]. Mechanistic aspects of these activation
reactions are also demonstrated.
(44%)
3 Ar = Ph
4a Ar = p-Tol
4b Ar = m-Tol
5a Ar = 2-Fur
5b Ar = 3-Fur
(52%)
(62%)
2. Results and discussion
The C–H activation of toluene starting with 1 gave a mixture of
the products [(Cp*Ir)(H)( -H)(Cp*Ir)(p-Tol)][OTf] (4a)
-dmpm)(
and [(Cp*Ir)(H)( -H)(Cp*Ir)(m-Tol)][OTf] (4b) in 1:2 ratio
-dmpm)(
2.1. Intermolecular activation of aromatic sp2 C–H bonds by dicationic
complex 1
l
l
l
l
(Eq. (2)), which were deduced to be p-tolyl and m-tolyl isomers,
respectively, according to the NMR signal patterns of aromatic ring.
No o-tolyl or benzyl metallated product was observed. There have
been several publications describing the regioselectivity of the C–H
activation of toluene by transition metal complexes [17], which
demonstrates that the cleavage of para and meta C–H bonds are
thermodynamically much favored compared to ortho and benzylic
ones. In some of these publications, the ratios of the para- and
meta-activated products are reported to be 1:2 similar to the pres-
ent study [17a,17d,17e]. The C–H activation of furan also gave two
Treatment of 1 with 1.1 equiv. of NaOtBu in benzene at room
temperature for 20 h gave [(Cp*Ir)(H)( -H)(Cp*Ir)-
l-dmpm)(l
(Ph)][OTf] (3) in 44% yield via intermolecular C–H activation of
benzene (Eq. (2)) [16]. In the 1H NMR spectrum of 3, two signals
for non-equivalent Cp* were found at d 2.12 and 1.85. Signals for
hydrides were observed at d ꢀ17.02 (terminal) and ꢀ25.39
(bridge). Signals due to aromatic protons were found at d 7.50,
6.94, and 6.88. In the 13C{1H} NMR, a signal due to the carbon at
ipso position of phenyl ring was found at d 132.8 as a doublet
(J = 13 Hz) coupling to a phosphorus. In the 31P{1H} NMR, two dis-
tinct signals were observed at d ꢀ25.3 and ꢀ37.6 as doublets cou-
pling to each other. All NMR data (1H, 13C{1H}, and 31P{1H}) of 3
were consistent with the proposed structure. The structure of 3
was confirmed by X-ray diffraction study. The molecular geometry
of 3 is shown in Fig. 1. It is apparent that the phenyl ring bonds to
products [(Cp*Ir)(H)(
l
-dmpm)(
l
-H)(Cp*Ir)(2-Fur)][OTf] (5a) and
[(Cp*Ir)(H)(
l
-dmpm)(
l
-H)(Cp*Ir)(3-Fur)][OTf] (5b) in 5:2 ratio
(Eq. (2)). In this reaction, the yield of the products was slightly
higher than those of the activation of benzene and toluene. In
the most of previous reports on the activation of furan, selective
cleavages of the C–H bond at 2-position have been observed [18].

K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
3377
P2a
P1a
P2
C45
Ir2a
Ir1a
P1
Ir2
Ir1
C26a
O1a
Fig. 2. ORTEP drawing of the cationic part of 5a with 30% thermal probability
ellipsoids (molecule A). Hydrogen atoms are omitted for clarity. In the unit cell
there are two independent molecules A and B, which are very similar to each other.
Selected (bond) distances (Å): Ir(1)–Ir(2) = 3.0938(8), 3.1370(8); Ir(1)–
P(1) = 2.253(3), 2.250(3); Ir(2)–P(2) = 2.249(3), 2.261(3); Ir(1)–C(26) = 2.05(1),
2.05(1); C(26)–O(1) = 1.38(1), 1.39(1).
Fig. 3. ORTEP drawing of the cationic part of 6 with 30% thermal probability
ellipsoids. Hydrogen atoms are omitted for clarity. Selected (bond) distances (Å):
Ir(1)–Ir(2) = 3.235(2);
C(45) = 2.10(2).
Ir(1)–P(1) = 2.285(4);
Ir(2)–P(2) = 2.224(4);
Ir(1)–
Very recently, however, Parkin reported that the activation of furan
by a molybdenocene complex resulted in the C–H cleavage at both
2- and 3-position, like the results in the present study [19]. X-ray
diffraction study of 5a was performed to confirm its structure.
The molecular geometry of 5a is shown in Fig. 2. The crystal struc-
ture of 5a is very similar to that of 3 except for the aryl group. No
interaction is observed between oxygen atom of the furan ring and
the iridium center (inter-atomic distance were 4.253 Å for mole-
cule A and 4.015 Å for molecule B), indicating that 5a would also
be a 34eꢀ structure.
2.3. Activation of hydrogen (H2) by dicationic complex 1
The reaction of 1 with 1.1 equiv. of NaOtBu in tetrahydrofuran
under H2 (1 atm) at room temperature for 20 h resulted in the acti-
vation of H2 to give [{(Cp*Ir)(H)}2(
l-dmpm)(l-H)][OTf] (7) in 61%
yield (Eq. (4)). In the 1H NMR spectrum of 7, signals due to two
Cp* ligands were observed equivalently at d 2.05 together with
those for methylene (d 3.63) and methyl (d 1.72) of the dmpm li-
gand. The signal due to three hydrides was found equivalently at
d ꢀ18.79 as a triplet (J = 13 Hz) coupling to the two phosphorus
atoms, indicating rapid interchange of three hydrides on the
NMR time scale. Upon cooling the sample to ꢀ80 °C, the reso-
nances due to the hydrides as well as the methylene protons in
dmpm ligand broadened, but well-resolved spectrum could not
be obtained at this temperature. In the 31P{1H} NMR at room tem-
perature, a single resonance was observed at d ꢀ40.7. Considering
that the most of Cp*IrIII complexes possess a 6-coordination mode,
the static structure of 7 must include two terminal hydrides and
2.2. Intramolecular activation of aromatic sp2 C–H bonds by dicationic
complex 2
In contrast to the intermolecular C–H activation by the dmpm
bridged diiridium complex 1, reaction of the dppm bridged diiridi-
um complex 2 with weak base (Et2NH) at room temperature for 1 h
resulted in intramolecular C–H activation of phenyl group of dppm
ligand to give [(Cp*Ir)(H){ -H)(Cp*Ir)][OTf]
l-PPh(C6H4)CH2PPh2}(l
(6) in quantitative yield (Eq. (3)). In the 1H NMR spectrum of 6,
two signals due to Cp* were found at d 1.90 and 1.70. Signals due
to hydrides were observed at d ꢀ15.63 (terminal) and ꢀ24.37
(bridge). In the 31P{1H} NMR, two signals were observed at d
ꢀ2.6 and ꢀ7.1 as doublets coupling to each other. All NMR data
(1H, 13C{1H}, and 31P{1H}) of 6 are consistent with the proposed
structure. The structure of 6 was confirmed by X-ray diffraction
study. The molecular geometry of 6 is shown in Fig 3. One of the
ortho carbons of phenyl group in dppm ligand is attached to one
of the iridium centers with an Ir–C distance of 2.10(2) Å. The irid-
one bridging hydride, i.e. (IrH)2(
(4). X-ray diffraction study of 7 was performed to confirm its struc-
ture, which also supports the proposed (IrH)2( -H) fashion. The
l-H) fashion as illustrated in Eq.
l
molecular geometry of 7 is shown in Fig. 4. The iridium–iridium
distance in 7 is 3.0248(5) Å, which is ca. 0.3 Å larger than the dou-
ble bond in the mother complex 1 [14], reflecting the single bond
character in 7. Although three hydrides could not be located in
the difference Fourier maps, existence of one bridging hydride
and two terminal hydrides on each iridium center could be antic-
ipated considering the geometry around the iridium centers. Clo-
sely related iso-electronic complexes, [{Cp*Ir(PMe3)(H)}2(
and [{Cp*Ir(CO)(H)}2(
tures have been elucidated to be (IrH)2(
l
-H)]+
ium–iridium distance [3.235(2) Å] is larger than that in
3
l
-H)]+ are known [12,20], and their struc-
[3.190(1) Å], possibly due to the steric hindrance of much bulky
dppm ligand in addition to two Cp* ligands.
l
-H) fashion.
+
NaOtBu
(1.1 eq)
H2 (1 atm)
THF
r. t., 20 h
+
2+
2+
PPh
Ir
Ph2P
Ir
Me2P
Ir
PMe2
Me2P
Ir
PMe2
Ir
Ph2P
Ir
PPh2
Ir
H
H
Ir
H
H
H
1
Et2NH
acetone
r. t.
ð3Þ
ð4Þ
Cp*
Cp*
Cp*
Cp*
Cp*
H
Cp*
Cp*
Cp*
H
H
H
2
6 (quant.)
7 (61%)

3378
K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
detected) was observed (Eq. (7)) [21]. This reaction would proceed
via reductive elimination of benzene from 3 to generate an active
intermediate at first, followed by C–H activation of furan. Addition-
ally, when the solution of the mixture of 5a and 5b in furan was
refluxed for 6 h, almost complete conversion into 5a was observed,
indicating that 5a would be thermodynamically more stable than
5b.
P2
P1
Ir2
+
+
Ir1
Me2P
Ir
PMe2
Ir
Me2P
Ir
PMe2
Ir
H
H
furan
reflux
ð7Þ
Cp*
Cp*
Cp*
Cp*
H
H
O
5a
3
2.4.3. Reaction of the dicationic complex 1 with base under CO
atmosphere
We next examined the reaction of 1 with CO in presence of base.
The reaction of 1 with 1.1 equiv. of NaOtBu under an atmosphere of
CO (1 atm) in dichloromethane gave an IrII–IrII complex,
Fig. 4. ORTEP drawing of the cationic part of 7 with 30% thermal probability
ellipsoids. Hydrogen atoms are omitted for clarity. Selected (bond) distances (Å):
Ir(1)–Ir(2) = 3.0248(5); Ir(1)–P(1) = 2.233(2); Ir(2)–P(2) = 2.257(2).
[(Cp*Ir)2(
l-dmpm)(l-H)(l-CO)][OTf] (8-OTf) in 46% yield (Eq.
(8)) [22]. In the 1H NMR spectrum of 8-OTf, signals due to two
Cp* were equivalently observed at d 2.08. Signals due to two meth-
ylene protons of dmpm ligand were non-equivalently observed at d
1.86 and 1.75, indicating a nonsymmetric character of this complex
respective to the plane defined by two iridium and two phosphorus
atoms. A signal for bridging hydride was found at d ꢀ16.93 as a
triplet. In the 13C{1H} NMR spectrum, a characteristic triplet signal
was found at d 218.2, which is due to the bridging carbonyl ligand.
In the IR spectrum of 8-OTf, absorption due to CO stretch was ob-
served at 1700 cmꢀ1 in the metal bridging carbonyl region [23].
These spectroscopic data support the structure of 8-OTf as illus-
trated in Eq. (8). To confirm the structure of 8 by X-ray diffraction,
attempts to obtain a single crystal were made. After some trials,
single crystals of 8-BPh4 having tetraphenylborate as a counter an-
ion were obtained by the recrystallization of 8-OTf in the presence
of three equivalents of NaBPh4. The NMR spectra of 8-OTf and 8-
BPh4 were essentially identical except for the signals due to anio-
nic moiety. The result of the X-ray diffraction study of 8-BPh4 is
shown in Fig. 5. It is apparent that CO bridges two iridium centers,
and 8 can be regarded as IrII–IrII complex with 34eꢀ structure.
2.4. Mechanistic experiments
2.4.1. C–H activation of benzene-d6 by 1
When the C–H activation reaction by 1 was carried out in ben-
zene-d6, D-incorporation was observed selectively in the bridging
hydride position (Eq. (5)). This result indicates that the crucial step
of the C–H activation involves the oxidative addition of a C–H bond
to one of the iridium centers (vide infra). H/D scrambling between
bridging and terminal hydrides in 3-d6 was slow; only a trace of
scrambling (<10%) was observed after the NMR sample of 3-d6
was allowed to stand for 3 h.
NaOtBu
(1.1 eq)
+
2+
Me2P
Ir
PMe2
Ir
Me2P
Ir
PMe2
Ir
D
H
H
1
d6
Cp*
Cp*
ð5Þ
Cp*
Cp*
H
r. t., 20 h
d5
3-d6
We also carried out the similar reaction of 1 with NaOtBu in an
equimolar amount of benzene and benzene-d6 (Eq. (6)). From the
1H NMR analysis of a mixture of products, the value of kinetic iso-
tope effect for the C–H activation of benzene by 1 was determined
to be 1.50, which is comparable to those reported for the C–H acti-
vation by mononuclear Cp*Ir complexes [4b,4d].
P1
P2
2+
t
(1.1 eq)
Me2P
Ir
PMe2
Ir
NaO Bu
H
H
1
C6H6 / C6D6 ( 1 : 1 )
r. t., 3 h
Ir2
Ir1
Cp*
Cp*
+
+
C26
ð6Þ
Me2P
Ir
PMe2
Me2P
Ir
PMe2
Ir
D
H
Ir
+
O1
Cp*
Cp*
d5
Cp*
Cp*
H
H
3-d6
3
kH/kD = 1.50
Fig. 5. ORTEP drawing of the cationic part of 8-BPh4 with 30% thermal probability
ellipsoids. Hydrogen atoms are omitted for clarity. Selected (bond) distances (Å)
and angles (°): Ir(1)–Ir(2) = 2.8727(5); Ir(1)–P(1) = 2.261(2); Ir(2)–P(2) = 2.253(2);
Ir(1)–C(26) = 2.005(6); Ir(2)–C(26) = 2.015(6); C(26)–O(1) = 1.189(7); Ir(1)–C(26)–
Ir(2) = 91.2(3); Ir(1)–C(26)–O(1) = 134.8(5); Ir(2)–C(26)–O(1) = 133.2(5).
2.4.2. C–H activation of furan starting with the phenyl complex 3
When the phenyl complex 3 was refluxed in furan for 20 h,
complete conversion into the 2-furyl complex 5a (5b was not

K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
3379
+
the bridging hydrides in 1 or 2 would be eliminated as a proton in-
duced by the reaction with base, generating an unsaturated 32eꢀ
IrII–IrII species A. This IrII–IrII species A would be in equilibrium
with the electronically unbalanced IrIII–IrI species B accompanied
by the migration of the hydride between the bridging and terminal
positions. When the reaction was carried out in CO atmosphere,
coordination of CO to A or B would occur immediately to afford
the CO-bridged complex 8. The C–H or H–H bond would approach
the IrI center in B, and the activation would occur to give the com-
plexes 3–7. This explanation means that crucial step of the bond
activation would involve the oxidative addition of C–H or H–H
bond to one of the iridium centers, which is supported by the
experimental results of the activation of benzene-d6 by 1 (vide
supra).
2+ NaOtBu
(1.1 eq)
Me2P
Ir
PMe2
Ir
H
Me2P
Ir
PMe2
Ir
H
H
1
ð8Þ
CO (1 atm)
CH2Cl2
r. t., 16 h
Cp*
Cp*
C
O
Cp*
Cp*
8-OTf (46%)
There are two possible paths for the formation of 8-OTf by the
reaction of 1 with CO in the presence of base (i.e. dissociative path
and associative path). To clarify this point, we carried out the reac-
tion of 1 with CO in the absence of base for 20 h, followed by the
treatment with NaOtBu (Eq. (9)). This reaction gave relatively com-
plicated mixture, and only a trace amount (<5%) of 8-OTf was ob-
served in 1H and 31P{1H} NMR analyses. Thus, we conclude that the
formation of 8-OTf from 1 shown in Eq. (8) would proceed via a
dissociative path through
a
32eꢀ diiridium intermediate
[(Cp*Ir)2( -H)]+. These results strongly suggest that C–
l
-diphos)(
l
3. Summary
H and H–H activation reactions starting with 1 would proceed
through the same 32eꢀ intermediate (vide infra).
We have described the inter- and intra-molecular activation of
aromatic C–H bonds and hydrogen on diphosphine and hydrido-
bridged dinuclear Cp*Ir complexes induced by the treatment with
base. From this work, three conclusions can be made. (1) Highly ac-
1. CO (1 atm)
2+
CD2Cl2
Me2P
Ir
PMe2
Ir
r. t., 20 h
tive 32eꢀ diiridium species [(Cp*Ir)2(
l
-diphos)(
l
l
-H)]+ can be gen-
H
H
1
8-OTf
( < 5%)
ð9Þ
2. NaOtBu (1.1 eq)
r. t., 8 h
erated by the treatment of dicationic [(Cp*Ir)2(
-diphos)(
l
-H)2]2+
Cp*
Cp*
with base, the bond activation readily occurs under ambient condi-
tions. (2) The critical stage of the bond activation on 32eꢀ species
involves the electron transfer between two iridium centers to af-
ford an electronically unbalanced IrIII–IrI species. This phenomenon
can be regarded as ‘‘cooperative reactivity” of dinuclear iridium
complexes. (3) Activation of C–H or H–H bond on the 32eꢀ species
gives the 34eꢀ complex as a product, which can be still regarded as
unsaturated. In view of further development of the reaction system
into the catalytic functionalization, the results presented in this
work are suggestive.
2.5. Possible mechanism for C–H and H–H activation reactions by
dinuclear iridium complexes
A possible mechanism for the C–H and H–H activation reactions
by 1 and 2 is summarized in Scheme 2. At the initial stage, one of
2+
+
P
P
P
P
-H+
H
H
4. Experimental
IrIII
IrIII
IrII
IrII
H
A
4.1. General
+
1, 2
P
P
CO
H
IrII
IrII
All manipulations were performed under a dry argon atmo-
sphere with standard Schlenk techniques. Melting points were
determined on a Yanagimoto micro melting point apparatus. Ele-
mental analyses were carried out at the Microanalysis Center of
Kyoto University. 1H, 13C{1H}, and 31P{1H} NMR spectra were mea-
sured with JEOL EX-270 and JEOL A-500 spectrometers. Solvents
were dried by using standard procedures and distilled prior to
C
O
+
8
P
P
IrIII
IrI
H
B
use. The complexes [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) and
-dppm)( -H)2][OTf]2 (2) were prepared by literature
H2
[(Cp*Ir)2(
l
l
+
Ar-H(D)
methods [13,14]. Other reagents were used as obtained from com-
mercial sources.
P
Ir
P
Ir
+
H
4.2. Reaction of [(Cp*Ir)2(
benzene. C–H activation of benzene
l
-dmpm)(l
-H)2][OTf]2 (1) with NaOtBu in
H
P
Ir
P
H
Ir
H
H
To a mixture of [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) (0.099 g,
(D) Ar
0.091 mmol) and NaOtBu (0.0095 g, 0.099 mmol) was added ben-
zene (10 mL), and the mixture was stirred at room temperature
for 20 h. After evaporation of the solvent (at this stage, formation
of 3 was confirmed by 1H NMR analysis in C6D6), the residue was
chromatographed on Florisil. Elution with dichloromethane and
methanol (30:1) followed by evaporation of the solvent gave 3
(0.041 g, 0.040 mmol, 44%) as an orange powder. Crystals of 3 suit-
able for an X-ray study were obtained by recrystallization from tol-
uene solution at ꢀ25 °C. 3: M.p.: 100.0–102.0 °C (dec). 1H NMR
(acetone-d6): d 7.50 (d, J = 7 Hz, 2H, o-Ph), 6.94 (t, J = 7 Hz, 2H, m-
Ph), 6.88 (t, J = 7 Hz, 1H, p-Ph), 4.70 (m, 1H, PCHHP), 2.61 (m, 1H,
+
P
Ir
P
H
Ir
+
H
H
P
P
(D)
H
7
Ir
Ir
H
Ar
3 - 6
Scheme 2.

3380
K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
PCHHP), 2.12 (s, 15H, C5Me5), 1.89 (dd, J = 11, 2 Hz, 3H, PMe), 1.85
(d, J = 2 Hz, 15H, C5Me5), 1.82 (d, J = 9 Hz, 3H, PMe), 1.75 (d,
J = 10 Hz, 3H, PMe), 1.35 (d, J = 11 Hz, 3H, PMe), ꢀ17.02 (dd,
J = 35, 5 Hz, 1H, Ir–H), ꢀ25.39 (ddd, J = 11, 5, 5 Hz, 1H, Ir–H–Ir).
13C{1H} NMR (acetone-d6): d 144.3 (s, Ph), 132.8 (d, J = 13 Hz, Ir–
C), 128.5 (s, Ph), 123.3 (s, Ph), 122.4 (q, J = 321 Hz, CF3), 97.0 (d,
J = 3 Hz, C5Me5), 95.9 (d, J = 3 Hz, C5Me5), 52.4 (dd, J = 36, 31 Hz,
PCH2P), 24.2 (d, J = 41 Hz, PMe), 18.1 (d, J = 34 Hz, PMe), 17.0 (d,
J = 44 Hz, PMe), 11.9 (dd, J = 29, 7 Hz, PMe), 11.2 (s, C5Me5), 10.6
(s, C5Me5). 31P{1H} NMR (acetone-d6): d ꢀ25.3 (d, J = 37 Hz),
ꢀ37.6 (d, J = 37 Hz). Anal. Calc. for C32H51F3O3P2SIr2 ꢁ C7H8: C,
42.14; H, 5.35. Found: C, 42.04; H, 5.27%.
11 Hz, 3H, PMe), 1.68 (d, J = 10 Hz, 3H, PMe), 1.61 (d, J = 11 Hz,
3H, PMe), ꢀ16.84 (dd, J = 37, 3 Hz, 1H, Ir–H), ꢀ26.15 (br, 1H, Ir–
H–Ir). 31P{1H} NMR (acetone-d6): d ꢀ31.9 (d, J = 40 Hz), ꢀ40.3 (d,
J = 40 Hz).
4.5. Reaction of [(Cp*Ir)2(
Intramolecular C–H activation of Ph group in dppm
l-dppm)(l-H)2][OTf]2 (2) with Et2NH.
To a solution of [(Cp*Ir)2(
0.020 mmol) in acetone (3 mL) was added Et2NH (0.014 g,
0.021 L, 0.19 mmol), and the mixture was stirred at room temper-
l-dppm)(l-H)2][OTf]2 (2) (0.034 g,
l
ature for 1 h. The color of the solution changed from dark green to
orange. After evaporation of the solvent, the residue was solved in
acetone. Slow diffusion of diethyl ether into this solution gave or-
ange crystals of 6 in quantitative yield. 6: M.p.: 142.1–143.1 °C. 1H
NMR (acetone-d6): d 7.78–6.37 (m, 19H, Ph), 5.05 (m, 1H, PCHHP),
3.10 (m, 1H, PCHHP), 1.90 (d, J = 2 Hz, 15H, C5Me5), 1.70 (d, J = 2 Hz,
15H, C5Me5), ꢀ15.63 (d, J = 29 Hz, 1H, Ir–H), ꢀ24.37 (m, 1H, Ir–H–
Ir). 13C{1H} NMR (acetone-d6): d 154.1–123.4 (Ph), 99.0 (s, C5Me5),
95.9 (d, J = 2 Hz, C5Me5), 44.7 (dd, J = 44, 31 Hz, PCH2P), 10.5 (brs,
C5Me5). 31P{1H} NMR (acetone-d6): d ꢀ2.6 (d, J = 41 Hz), ꢀ7.1 (d,
J = 41 Hz). Anal. Calc. for C46H53F3O3P2SIr2: C, 46.45; H, 4.49.
Found: C, 46.18; H, 4.65%.
l-dmpm)(l
4.3. Reaction of [(Cp*Ir)2( -H)2][OTf]2 (1) with NaOtBu in
toluene. C–H activation of toluene
To a mixture of [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) (0.070 g,
0.064 mmol) and NaOtBu (0.0068 g, 0.071 mmol) was added tolu-
ene (10 mL), and the mixture was stirred at room temperature
for 20 h. After evaporation of the solvent, the residue was chro-
matographed on Florisil. Elution with dichloromethane and meth-
anol (30:1) followed by evaporation of the solvent gave a mixture
of 4a and 4b (1:2; determined by NMR) (0.034 g, 0.033 mmol, 52%)
as an oily brown powder. 4a: 1H NMR (CD2Cl2): d 7.20 (d, J = 7 Hz,
2H, Tol), 6.74 (d, J = 7 Hz, 2H, Tol), 4.30 (m, 1H, PCHHP), 2.38 (m,
1H, PCHHP), 2.23 (s, 3H, Tol-Me), 2.02 (s, 15H, C5Me5), 1.74 (s,
15H, C5Me5), ꢀ17.20 (dd, J = 34, 5 Hz, 1H, Ir–H), ꢀ25.59 (ddd,
J = 11, 5, 5 Hz, 1H, Ir–H–Ir). 31P{1H} NMR (acetone-d6): d ꢀ25.5
(d, J = 37 Hz), ꢀ37.7 (d, J = 37 Hz). 4b: 1H NMR (CD2Cl2): d 7.22 (s,
1H, Tol), 7.08 (d, J = 7 Hz, 1H, Tol), 6.79 (t, J = 7 Hz, 1H, Tol), 6.69
(d, J = 7 Hz, 1H, Tol), 4.30 (m, 1H, PCHHP), 2.38 (m, 1H, PCHHP),
2.21 (s, 3H, Me), 2.02 (s, 15H, C5Me5), 1.74 (s, 15H, C5Me5),
ꢀ17.18 (dd, J = 34, 5 Hz, 1H, Ir–H), ꢀ25.53 (ddd, J = 11, 5, 5 Hz,
1H, Ir–H–Ir). 31P{1H} NMR (acetone-d6): d ꢀ25.6 (d, J = 37 Hz),
ꢀ37.8 (d, J = 37 Hz). Elemental analyses for 4a and 4b were unsat-
isfactory because of a small amount of contaminant.
l-dmpm)(l
4.6. Reaction of [(Cp*Ir)2( -H)2][OTf]2 (1) with NaOtBu
under hydrogen atmosphere. Activation of H–H bond of hydrogen
To a mixture of [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) (0.074 g,
0.068 mmol) and NaOtBu (0.0072 g, 0.075 mmol) was added tetra-
hydrofuran (7 mL) under an atmosphere of H2, and the mixture
was stirred at room temperature for 20 h. After evaporation of the
solvent, the residue was chromatographed on Silica-gel. Elution
with dichloromethane and methanol (30:1) followed by evapora-
tion of the solvent gave 7 (0.039 g, 0.041 mmol, 61%) as an orange
powder. 7: M.p.: 145.0 °C (dec). 1H NMR (CDCl3): d 3.63 (t,
J = 11 Hz, 2H, PCH2P), 2.05 (s, 30H, C5Me5), 1.72 (m, 12H, PMe),
ꢀ18.79 (t, J = 13 Hz, 3H, Ir–H). 13C{1H} NMR (CDCl3): d 120.9 (q,
J = 319 Hz, CF3), 94.6 (s, C5Me5), 55.0 (t, J = 34 Hz, PCH2P), 20.9 (m,
PMe), 11.1 (s, C5Me5). 31P{1H} NMR (CDCl3): d ꢀ40.7 (s). Anal. Calc.
for C26H47Ir2O3P2SF3: C, 33.11; H, 5.02. Found: C, 32.81; H, 4.95%.
4.4. Reaction of [(Cp*Ir)2( -H)2][OTf]2 (1) with NaOtBu in
l-dmpm)(l
furan. C–H activation of furan
To a mixture of [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) (0.062 g,
0.057 mmol) and NaOtBu (0.0060 g, 0.062 mmol) was added furan
(6 mL), and the mixture was stirred at room temperature for 20 h.
After evaporation of the solvent, the residue was chromatographed
on Florisil. Elution with dichloromethane and methanol (30:1) fol-
lowed by evaporation of the solvent gave a mixture of 5a and 5b
(5:2; determined by NMR) (0.035 g, 0.035 mmol, 62%) as an orange
powder. Crystals of 5a suitable for an X-ray study were obtained by
recrystallization from toluene solution at ꢀ25 °C. 5a: M.p.: 149.4–
149.9 °C. 1H NMR (acetone-d6): d 7.59 (d, J = 2 Hz, 1H, Fur), 6.27
(dd, J = 3, 2 Hz, 1H, Fur), 5.89 (d, J = 3 Hz, 1H, Fur), 4.95 (m, 1H,
PCHHP), 2.54 (m, 1H, PCHHP), 2.14 (s, 15H, C5Me5), 1.94 (d,
J = 3 Hz, 15H, C5Me5), 1.84 (d, J = 10 Hz, 3H, PMe), 1.78 (d,
J = 9 Hz, 3H, PMe), 1.77 (d, J = 9 Hz, 3H, PMe), 1.36 (d, J = 11 Hz,
3H, PMe), ꢀ16.38 (dd, J = 38, 3 Hz, 1H, Ir–H), ꢀ24.56 (ddd, J = 12,
5, 3 Hz, 1H, Ir–H–Ir). 13C{1H} NMR (acetone-d6): d 145.5 (s, Fur),
138.0 (d, J = 18 Hz, Ir–C), 122.4 (q, J = 322, CF3), 117.4 (s, Fur),
112.0 (s, Fur), 97.6 (d, J = 3, C5Me5), 96.1 (s, C5Me5), 52.8 (dd,
J = 36, 31 Hz, PCH2P), 25.3 (m, PMe), 18.1 (d, J = 45 Hz, PMe), 17.8
(d, J = 35 Hz, PMe), 12.1 (dd, J = 36, 8 Hz, PMe), 10.9 (s, C5Me5),
10.8 (s, C5Me5). 31P{1H} NMR (acetone-d6): d ꢀ26.0 (d, J = 39 Hz),
ꢀ39.5 (d, J = 39 Hz). Anal. Calc. for C30H49F3O4P2SIr2: C, 35.70; H,
4.89. Found: C, 35.60; H, 4.81%. 5b: 1H NMR (acetone-d6): d 7.36
(s, 1H, Fur), 6.12 (d, J = 6 Hz, 1H, Fur), 5.23 (d, J = 6 Hz, 1H, Fur),
5.07 (m, 1H, PCHHP), 2.39 (m, 1H, PCHHP), 2.11 (s, 15H, C5Me5),
1.93 (s, 15H, C5Me5), 1.86 (d, J = 6 Hz, 3H, PMe), 1.81 (d, J =
l-dmpm)(l
4.7. Reaction of [(Cp*Ir)2( -H)2][OTf]2 (1) with NaOtBu
under CO atmosphere
To a mixture of [(Cp*Ir)2(
l-dmpm)(l-H)2][OTf]2 (1) (0.100 g,
0.092 mmol) and NaOtBu (0.0097 g, 0.101 mmol) was added
dichloromethane (10 mL), and the mixture was stirred at room
temperature for 12 h. After evaporation of the solvent, the residue
was chromatographed on Florisil. Elution with dichloromethane
and methanol (30:1) followed by evaporation of the solvent gave
8-OTf (0.041 g, 0.042 mmol, 46%) as an orange powder. 8-OTf:
M.p.: 183.5–185.0 °C. IR (KBr): mCO 1700 cmꢀ1 1H NMR (acetone-
.
d6): d 2.08 (s, 30H, C5Me5), 1.86 (m, 1H, PCHHP), 1.85 (m, 6H,
PMe), 1.75 (m, 1H, PCHHP), 1.56 (m, 6H, PMe), ꢀ16.93 (t,
J = 10 Hz, 1H, Ir–H–Ir). 13C{1H} NMR (acetone-d6): d 218.2 (t,
J = 6.6 Hz, CO), 122.4 (q, J = 322 Hz, CF3), 98.4 (s, C5Me5), 30.8 (t,
J = 35 Hz, PCH2P), 19.2 (dd, J = 22, 21 Hz, PMe), 14.8 (dd, J = 24,
22 Hz, PMe), 10.5 (s, C5Me5). 31P{1H} NMR (acetone-d6): d ꢀ15.6
(s). Anal. Calc. for C27H45Ir2O4P2SF3: C, 33.46; H, 4.68. Found: C,
33.16; H, 4.64%. Crystals of 8-BPh4 suitable for an X-ray study were
obtained by slow diffusion of diethyl ether to a solution of 8-OTf in
acetone in the presence of three equivalents of NaBPh4. 8-BPh4:
M.p.: 241.0–242.8 °C. IR (KBr): mCO 1701 cmꢀ1 1H NMR (acetone-
.
d6): d 6.76–7.33 (m, 20H, Ph), 2.05 (s, 30H, C5Me5), 2.10 (m, 1H,
PCHHP), 1.78 (m, 6H, PMe), 1.68 (m, 1H, PCHHP), 1.51 (m, 6H,
PMe), ꢀ16.94 (t, J = 11 Hz, 1H, Ir–H–Ir). 13C{1H} NMR (acetone-

K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
3381
Table 1
Crystal data and structure refinement parameters for 3 ꢁ C7H8, 5a, 6, 7, and 8-BPh4
3 ꢁ C7H8
5a
6
7
8-BPh4
Description of crystal
Color, habit
Maximum crystal dimensions (mm)
Crystal system
Space group
a (Å)
Orange, cubic
0.30 ꢂ 0.30 ꢂ 0.30
Triclinic
Orange, block
0.35 ꢂ 0.35 ꢂ 0.30
Monoclinic
P21
10.845(3)
19.462(4)
17.299(4)
90
107.70(2)
90
3478(2)
4
Orange, prismatic
0.25 ꢂ 0.25 ꢂ 0.25
Monoclinic
P21
11.459(8)
13.782(9)
14.696(5)
90
Yellow, plate
0.40 ꢂ 0.30 ꢂ 0.20
Triclinic
Orange-red, plate
0.40 ꢂ 0.30 ꢂ 0.10
Triclinic
ꢀ
ꢀ
ꢀ
P1
P1
P1
13.702(3)
14.763(4)
11.466(5)
112.75(3)
97.02(3)
98.27(2)
2076(1)
2
10.620(1)
15.200(2)
10.116(1)
95.84(1)
92.787(9)
79.61(1)
1597.1(3)
2
13.741(2)
18.349(3)
9.586(2)
94.71(1)
105.16(1)
100.55(1)
2271.7(7)
2
b (Å)
c (Å)
a
(°)
b (°)
107.89(3)
90
2209(2)
c
(°)
V (Å3)
Z
2
Formula
C
39H59F3O3P2SIr2
C30H49F3O4P2SIr2
1009.16
1.927
C46H53F3O3P2SIr2
1189.37
1.788
C26H47F3O3P2SIr2
943.10
1.961
C50H65BOP2Ir2
1139.26
1.665
Formula weight
1111.34
1.778
Dcalc (g cmꢀ3
)
Data collection
Radiation (k, Å)
Temperature (K)
Scan technique
Scan width (°)
2hmax (°)
Mo K
203
a
(0.71069)
Mo K
203
a
(0.71069)
Mo K
291
a
(0.71069)
Mo K
203
a
(0.71069)
Mo K
203
a (0.71069)
x
ꢀ 2h
x
ꢀ 2h
x
ꢀ 2h
x
ꢀ 2h
x ꢀ 2h
(1.05 + 0.30tanh)
(1.05 + 0.30tanh)
(1.10 + 0.30tanh)
(1.21 + 0.30tanh)
(1.26 + 0.30tanh)
55.0
55.0
55.0
55.0
55.0
No. of reflections measured
Structure determination
No. of reflections used
No. of parameters varied
Data/parameter ratio
Transmission factors
Goodness-of-fit (GOF)
Ra
9991
8472
5532
7710
11038
6752
451
14.97
0.8394–0.9994
1.30
7324
756
9.69
0.6656–1.0000
1.18
4293
493
8.71
0.6895–1.0000
1.21
5894
334
17.65
0.3679–1.0000
1.75
7536
505
14.92
0.3924–1.0000
1.53
0.030
0.033
0.033
0.032
0.045
0.044
0.037
0.046
0.032
0.034
a
Rw
P
P
2
|Fo|, Rw ¼ ½ wðjFoj ꢀ jFcjÞ = wF2oꢃ1=2. w = [
r
2(Fo) + p2(Fo)2/4]ꢀ1
.
a
R =
R
||Fo| ꢀ |Fc||/
R
d6): d 218.0 (t, J = 5.9 Hz, CO), 164.8 (q, J = 50 Hz, Ph), 136.9 (s, Ph),
125.9 (q, J = 3 Hz, Ph), 122.1 (s, Ph), 98.3 (s, C5Me5), 30.7 (t,
J = 36 Hz, PCH2P), 18.9 (t, J = 21 Hz, PMe), 14.7 (t, J = 22 Hz, PMe),
10.4 (s, C5Me5). 31P{1H} NMR (acetone-d6): d ꢀ14.9 (s). Anal. Calc.
for C50H65Ir2OP2B: C, 52.71; H, 5.75. Found: C, 52.98; H, 5.78%.
Appendix A. Supplementary material
CCDC 223707, 223708, 223709, 675851 and 675852 contains
the supplementary crystallographic data for 3 ꢁ C7H8, 5a, 6, 7 and
8-BPh4. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2008.07.032.
4.8. X-ray structure analysis of 3 ꢁ C7H8, 5a, 6, 7, and 8-BPh4
Crystal data and experimental details for X-ray structure analy-
sis are summarized in Table 1. Diffraction data were obtained with
a Rigaku AFC-5S. The reflection intensities were monitored by three
standard reflections every 150 measurements. Reflection data were
corrected for Lorentz and polarization effects. Absorption correc-
tions were empirically applied (psi scans). Decay corrections were
not applied. The structures were solved by heavy-atom Patterson
methods [24,25], and refined anisotropically for non-hydrogen
atoms by full-matrix least squares calculations, except for carbon
and fluorine atoms of triflate anion in 6, which were refined isotrop-
ically. Atomic scattering factors and anomalous dispersion terms
were taken from the literature [26]. The hydrogen atoms were lo-
cated on idealized positions except for metal hydrides in 3 ꢁ C7H8,
which were defined on Fourier difference maps. Metal hydrides in
5a, 6, 7, and 8-BPh4 were not located. In 5a, there were two indepen-
dent molecules A and B, which were very similar to each other, in
the unit cell. In 5a and 6, the crystal chirality was tested by inverting
all the coordinates and refining to convergence once again. The re-
sults indicated the original choice should be the correct one. The cal-
culations were performed using the program system TEXSAN [27].
References
[1] (a) A.E. Shilov, G.B. Shul’pin, Chem. Rev. 97 (1997) 2879. and references cited
therein;
(b) J.A. Labinger, J.E. Bercaw, Nature 417 (2002) 507. and references cited
therein.
[2] For example (a) W. Xu, G.P. Rosini, M. Gupta, C.M. Jensen, W.C. Kaska, K. Krogh-
Jespersen, A.S. Goldman, Chem. Commun. (1997) 2273;
(b) H. Chen, S. Schlecht, T.C. Semple, J.F. Hartwig, Science 287 (2000) 1995;
(c) T. Matsumoto, D.J. Taube, R.A. Periana, H. Taube, H. Yoshida, J. Am. Chem.
Soc. 122 (2000) 7414;
(d) J.-Y. Cho, M.K. Tse, D. Holmes, R.E. Maleczka Jr., M.R. Smith III, Science 295
(2002) 305;
(e) T. Ishiyama, J. Takagi, K. Ishida, N. Miyaura, N.R. Anastasi, J.F. Hartwig, J.
Am. Chem. Soc. 124 (2002) 390.
[3] K. Godula, D. Sames, Science 312 (2006) 67. and references cited therein.
[4] (a) A.H. Janowicz, R.G. Bergman, J. Am. Chem. Soc. 104 (1982) 352;
(b) A.H. Janowicz, R.G. Bergman, J. Am. Chem. Soc. 105 (1983) 3929;
(c) J.M. Buchanan, J.M. Stryker, R.G. Bergman, J. Am. Chem. Soc. 108 (1986)
1537;
(d) P.O. Stoutland, R.G. Bergman, J. Am. Chem. Soc. 110 (1988) 5732.
[5] (a) J.K. Hoyano, W.A.G. Graham, J. Am. Chem. Soc. 104 (1982) 3723;
(b) J.K. Hoyano, A.D. McMaster, W.A.G. Graham, J. Am. Chem. Soc. 105 (1983)
7190;
(c) P.E. Bloyce, A.J. Rest, I. Whitwell, W.A.G. Graham, R. Holmes-Smith, J. Chem.
Soc., Chem. Commun. (1988) 846.
[6] (a) D.M. Haddleton, R.N. Perutz, J. Chem. Soc., Chem. Commun. (1986) 1734;
(b) T.W. Bell, D.M. Haddleton, A. McCamley, M.G. Partridge, R.N. Perutz, H.
Willner, J. Am. Chem. Soc. 112 (1990) 9212;
(c) T.W. Bell, S.-A. Brough, M.G. Partridge, R.N. Perutz, A.D. Rooney,
Organometallics 12 (1993) 2933.
[7] P.A. Chetcuti, C.B. Knobler, M.F. Hawthorne, Organometallics 7 (1988) 650.
Acknowledgement
This work was partially supported by a Grant-in-Aid for Young
Scientists (B) Nos. 14750666 and 17750052 from the Ministry of
Education, Culture, Sports, Science and Technology, Japan.

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K.-i. Fujita et al. / Journal of Organometallic Chemistry 693 (2008) 3375–3382
[8] In addition to C–H activations by Cp*IrI species, C–H activations by cationic
Cp*IrIII species have been known. (a) P. Burger, R.G. Bergman, J. Am. Chem. Soc.
115 (1993) 10462;
[18] (a) H.E. Selnau, J.S. Merola, Organometallics 12 (1993) 1583;
(b) W.D. Jones, L. Dong, A.W. Myers, Organometallics 14 (1995) 855;
(c) T. Morikita, M. Hirano, A. Sasaki, S. Komiya, Inorg. Chim. Acta 291 (1999)
341;
(b) B.A. Arndtsen, R.G. Bergman, Science 270 (1995) 1970;
(c) D.M. Tellers, C.M. Yung, B.A. Arndtsen, D.R. Adamson, R.G. Bergman, J. Am.
Chem. Soc. 124 (2002) 1400.
(d) K.A. Pittard, J.P. Lee, T.R. Cundari, T.B. Gunnoe, J.L. Petersen,
Organometallics 23 (2004) 5514.
[9] (a) H. Suzuki, Eur. J. Inorg. Chem. (2002) 1009. and references cited therein;
(b) Y. Yuan, M.V. Jiménez, E. Sola, F.J. Lahoz, L.A. Oro, J. Am. Chem. Soc. 124
(2002) 752;
(c) J.R. Torkelson, F.H. Antwi-Nsiah, R. McDonald, M. Cowie, J.G. Pruis, K.J.
Jalkanen, R.L. DeKock, J. Am. Chem. Soc. 121 (1999) 3666;
(d) D.A. Vicic, W.D. Jones, Organometallics 18 (1999) 134.
[10] (a) W.D. McGhee, R.G. Bergman, J. Am. Chem. Soc. 108 (1986) 5621;
(b) W.D. McGhee, F.J. Hollander, R.G. Bergman, J. Am. Chem. Soc. 110 (1988)
8428.
[19] D.G. Churchill, B.M. Bridgewater, G. Zhu, K. Pang, G. Parkin, Polyhedron 25
(2006) 499.
[20] T.M. Gilbert, R.G. Bergman, J. Am. Chem. Soc. 107 (1985) 3502.
[21] We also carried out the reaction of 3-d6 in furan under reflux for 20 h, which
gave 5a with no deuterium.
[22] We also examined the reaction of 2 with base under CO atmosphere. However,
this reaction gave a complicated mixture, and we could not characterize the
product.
[23] (a) B.R. Sutherland, M. Cowie, Inorg. Chem. 23 (1984) 2324;
(b) R.G. Ball, W.A.G. Graham, D.M. Heinekey, J.K. Hoyano, A.D. McMaster, B.M.
Mattson, S.T. Michel, Inorg. Chem. 29 (1990) 2023;
[11] M.V. Jiménez, E. Sola, J. Caballero, F.J. Lahoz, L.A. Oro, Angew. Chem., Int. Ed. 41
(2002) 1208.
[12] D.M. Heinekey, D.A. Fine, D. Barnhart, Organometallics 16 (1997) 2530.
[13] K. Fujita, T. Hamada, R. Yamaguchi, J. Chem. Soc., Dalton Trans. (2000) 1931.
[14] K. Fujita, H. Nakaguma, F. Hanasaka, R. Yamaguchi, Organometallics 21 (2002)
3749.
(c) R. McDonald, M. Cowie, Inorg. Chem. 32 (1993) 1671.
[24] PATTY: P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, S. Garcia-
Granda, R.O. Gould, J.M.M. Smits, C. Smykalla, Technical Report of the
Crystallography Laboratory, University of Nijmegen, 1992.
[25] DIRDIF94, P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, R. de
Gelder, R. Israel, J.M.M. Smits, Technical Report of the Crystallography
Laboratory, University of Nijmegen, 1994.
[15] A part of this paper has been preliminarily reported. For
a preliminary
communication, see: K. Fujita, H. Nakaguma, T. Hamada, R. Yamaguchi, J. Am.
Chem. Soc. 125 (2003) 12368.
[16] Strong base such as NaOtBu was required for the intermolecular C–H activation
starting with 1. Use of weaker base such as Et2 NH resulted in no reaction.
[17] (a) W.D. Jones, F.J. Feher, J. Am. Chem. Soc. 106 (1984) 1650;
(b) M.D. Fryzuk, P.A. MacNeil, N.T. McManus, Organometallics 6 (1987) 882;
(c) W.D. Jones, E.T. Hessell, J. Am. Chem. Soc. 115 (1993) 554;
(d) P. Diversi, S. Iacoponi, G. Ingrosso, F. Laschi, A. Lucherini, C. Pinzino, G.
Uccello-Barretta, P. Zanello, Organometallics 14 (1995) 3275;
(e) M. Kanzelberger, B. Singh, M. Czerw, K. Krogh-Jespersen, A.S. Goldman, J.
Am. Chem. Soc. 122 (2000) 11017.
[26] (a) D.T. Cromer, G.T. Waber, International Tables for X-ray Crystallography,
vol. IV, Kynoch, Birmingham, UK, 1974;
(b) J.A. Ibers, W.C. Hamilton, Acta Crystallogr. 17 (1964) 781;
(c) D.C. Creagh, W.J. McAuley, in: A.J.C. Wilson (Ed.), International Tables for
X-ray Crystallography, vol. C, Kluwer Academic publishers, Boston,MA, 1992;
(d) D.C. Creagh, J.H. Hubbell, in: A.J.C. Wilson (Ed.), International Tables for
X-ray Crystallography, vol. C, Kluwer Academic publishers, Boston, MA, 1992.
[27] TEXSAN for Windows, Crystal Structure Analysis Package, Molecular Structure
Corporation, 1997.