Reactivity of phosphane-imidazolium salts towards [Ir(COD)Cl]2: Preparation of new hydridoiridium(III) complexes bearing abnormal carbenes

Article abstract of DOI:10.1002/ejic.200800270

The unusual reactivity of chelating phosphane-imidazolium salts MesImEtPPh₂⁺+Br^-, DIPP-ImEtPPh₂ ⁺Br^-, and MesImEtPPh₂⁺BF ₄^- towards the low-oxidation-state iridium complex [Ir(COD)(μ-Cl)]₂ was studied. In the absence of a base, the C-H insertion at the C5 position of the imidazolium ring was the only reaction that occurred, with no normal NHC observed, leading to hydridoiridium(III) complexes. This reactivity was independent of the nature of the imidazolium counteranion and of the substitution pattern of the aryl group. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200800270

FULL PAPER
DOI: 10.1002/ejic.200800270
Reactivity of Phosphane–Imidazolium Salts Towards [Ir(COD)Cl]2:
Preparation of New Hydridoiridium(III) Complexes Bearing Abnormal
Carbenes
Joffrey Wolf,[a] Agnès Labande,*[a] Jean-Claude Daran,[a] and Rinaldo Poli*[a]
Dedicated to Prof. W. A. Herrmann on the occasion of his 60th birthday
Keywords: Carbenes / Phosphane ligands / Iridium / Hydrides / C–H activation
The unusual reactivity of chelating phosphane–imidazol-
ium salts MesImEtPPh2+Br–, DIPP-ImEtPPh2+Br–, and
NHC observed, leading to hydridoiridium(III) complexes.
This reactivity was independent of the nature of the imid-
azolium counteranion and of the substitution pattern of the
aryl group.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
–
MesImEtPPh2+BF4 towards the low-oxidation-state iridium
complex [Ir(COD)(µ-Cl)]2 was studied. In the absence of a
base, the C–H insertion at the C5 position of the imidazolium
ring was the only reaction that occurred, with no normal
iridium(III) complexes bearing chelating phosphane–(ab-
normal)NHC ligands.[16] They did not observe any influ-
ence of the counteranion on the product selectivity.
We are interested in the preparation of bifunctional imid-
azolium salts containing a coordinating heteroatom such as
phosphorus or sulfur, and their use as ligands or ligand
precursors for transition metals.[4–6] More particularly, we
recently described the use of phosphane–imidazolium salts
to prepare zwitterionic NiII complexes and showed their ex-
cellent activities for Kumada–Tamao–Corriu cross-coupling
reactions.[4] We now report the unusual reactivity of these
salts with [Ir(COD)Cl]2. These results were obtained during
attempts to synthesise new IrI precatalysts, according to the
same procedure that allowed us to access NiII and PdII ana-
logues.[4,5]
Introduction
N-Heterocyclic carbene (NHC) complexes are now
widely used for catalytic applications.[1] This interest is par-
ticularly due to the production of more robust catalysts by
coordination of NHCs to transition metals such as palla-
dium, nickel, rhodium, ruthenium, and iridium.[2] Over the
last fifteen years, a number of bidentate as well as polydent-
ate ligands incorporating NHCs[3] and other coordinating
atoms,[4–8] have been developed and used successfully in ca-
talysis.
A different binding mode for NHCs was described by
Crabtree and coworkers;[9] instead of the normal C2 coordi-
nation, the metal atom can bind to the C4 or C5 atom of
an imidazolium salt. Since this discovery, only a few exam-
ples of “abnormal” carbenes have been described, for exam-
ple with iridium,[10–12] ruthenium,[13] osmium,[14] and sev-
eral other transition metals.[15] In the case of Crabtree’s
work with the iridium precursor IrH5(PPh3)2, it was shown
that the formation of classical or abnormal NHCs was
anion-dependent; imidazolium salts bearing a halogen
anion led preferentially to classical NHCs, whereas nonco-
Results and Discussion
The phosphane–imidazolium salts were prepared accord-
ing to previously reported procedures (Scheme 1).[4] The re-
action of 1-[2-(diphenylphosphanyl)ethyl]-3-(2,4,6-trimeth-
ylphenyl)imidazolium bromide salt MesImC2H4PPh2+Br–
(1) with [Ir(COD)(µ-Cl)]2 yielded a mixture of two hydrido
complexes (4a and 4b) in a 1:1 ratio (Scheme 2). The two
complexes exhibit two almost equivalent 31P NMR signals
at δ = –1.1 and –2.4 ppm and two equivalent 1H NMR
hydride doublet resonances at δ = –15.22 and –14.55 ppm
(see Figure 1a).
–
–
ordinating anions BF4 or PF6 gave mostly abnormal
NHCs.[12] Monodentate ligands were then used instead of
bidentate NHCs, with similar results, showing no chelate
effect.[11] Recently, the group of Li reported hydrido-
[a] Laboratoire de Chimie de Coordination, UPR CNRS 8241 (lié
par convention à l’Université Paul Sabatier et à l’Institut
National Polytechnique de Toulouse),
We attribute this behavior to halogen exchange induced
by the bromide anion of 1. This hypothesis is confirmed
by the observation that using MesImC2H4PPh2+BF4– (3) in
205 route de Narbonne, 31077 Toulouse Cedex 4, France
Fax: +33-5-61553003
E-mail: agnes.labande@lcc-toulouse.fr
3024
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Eur. J. Inorg. Chem. 2008, 3024–3030

Hydridoiridium(III) Complexes Bearing Abnormal Carbenes
Scheme 1. Synthesis of phosphane–imidazolium salts. Mes = mesityl or 2,4,6-trimethylphenyl; DIPP = 2,6-diisopropylphenyl.
Scheme 2. Mixture of isomers 4a+4b from the reaction of ligand 1, or isomers 6a+6b from the reaction of ligand 2, with [Ir(COD)(µ-Cl)]2.
imidazole ring protons at δ = 9.74, 6.24, and 6.18 ppm, with
integration values of 1:0.5:0.5, whereas that of compound 5
exhibits two 1:1 resonances at δ = 8.45 and 6.40 ppm (see
Figure 2). Whereas the upfield imidazole ring 1H NMR res-
onances of 5 approximately match with those of 4a, the
downfield one is quite anion-dependent. Furthermore, 1:1
13C NMR resonances for quaternary carbon atoms are ob-
served at δ = 119.9 and 121.1 ppm, which is a typical region
for aryl substituents and not for NHC ligands. These results
indicate that the products are IrIII complexes coordinated
by
a bidentate phosphane–(abnormal)carbene ligand
1
(Scheme 2). The shift of the downfield H NMR resonance
is attributed to differences in hydrogen bonding between the
acidic imidazolium proton and the different counterion. Re-
lated hydridoiridium(III) complexes, also featuring an ab-
normal carbene coordination, were recently reported by Li
et al. and show similar NMR spectroscopic features (com-
plex A, Figure 3).[16] Danopoulos et al. also obtained
and crystallographically characterised a similar complex,
[Ir(COD)(Br){κ2:P,C5-Ph2PCH2CH2(N2C3HMes)}] (B in
Figure 3), from the reaction of 1 with [Ir(COD)(HCl)(µ-
Cl)2]2. It is related to 4b by elimination of HCl.[8]
1
Figure 1. H NMR spectra (500 MHz, 20 °C) of complexes (a) 4a/
4b (CDCl3), (b) 5 (CD2Cl2), (c) 6a/6b (CD2Cl2) (hydride reso-
nances).
place of 1 led to a single product 5, whose 31P and H (hy-
1
dride) NMR resonances match with those of 4a (Scheme 3,
Figure 1b). Thus, both products 4a and 5 contain a
chlorido ligand and a different counterion (Br– for 4a and
Complex 5 was also characterised by X-ray crystallogra-
BF4 for 5), whereas the chloride and bromide ions are ex- phy (Figure 4, Table 2). The Ir1–C2 distance [2.068(5) Å]
–
changed in 4b.
and the Ir1–Cl1 distance are in agreement with the data
1
The H NMR spectrum of the 4a/4b mixture indicates given by Li et al. for A (Table 1).[16] The Ir1–P1 distance,
C1 symmetry and reveals three signals corresponding to the however, appears much shorter than that in Li’s compound,
Scheme 3. Synthesis of complex 5 via an iridium(I) intermediate.
Eur. J. Inorg. Chem. 2008, 3024–3030
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J. Wolf, A. Labande, J.-C. Daran, R. Poli
FULL PAPER
Figure 2. 1H NMR spectra (500 MHz, 20 °C) of complexes (a) 4a/4b (CDCl3), (b) 5 (CD2Cl2), (c) 6a/6b (CD2Cl2) (imidazolium reso-
nances).
Table 1. Comparison of the main structural parameters of 5 and of
the iridium complexes described by Li et al. (A)[16] and Danopoulos
et al. (B).[8]
5
A
B
Bond lengths/Å
Ir1–C2[a]
Ir1–P1
Ir1–Cl1
Ir1–Br1
Ir1–H100
2.068(5)
2.2972(16)
2.4845(15)
–
2.065(6)
2.585(1)
2.5097(9)
–
2.018(9)
2.283(2)
–
2.6865(11)
–
Figure 3. Related iridium complexes reported by Li et al. (A)[16]
and Danopoulos et al. (B).[8]
1.586(19)
–
but is very close to the distance measured in Danopoulos’
compound B[8] where the N2 atom is also substituted with
a bulky aryl group. The C2–Ir1–P1 bite angle is also very
close to that of Li’s complex, with a large value of
92.70(13)°. The structure confirms the binding of the imid- C2–Ir1–H100
azole moiety through C5 (labeled as C2 in the structure). It
Bond angles/°
C2–Ir1–P1
C2–Ir1–Cl1
P1–Ir1–Cl1
92.70(13)
82.75(15)
86.81(5)
82(2)
92(2)
164(2)
92.24(16)
85.50(16)
90.83(5)
–
–
–
88.9(3)
–
–
–
–
–
P1–Ir1–H100
Cl1–Ir1–H100
[a] Labeled as C9 in Li’s complex A.[16]
also shows the presence of a hydrido ligand trans to the
chlorido ligand, with an Ir1–H100 bond length of
Figure 4. ORTEP view of compound 5. Ellipsoids are represented at the 30% probability level. Hydrogen atoms (except H100), cocrystal-
–
lised solvent molecules, and BF4 are omitted for clarity.
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Eur. J. Inorg. Chem. 2008, 3024–3030

Hydridoiridium(III) Complexes Bearing Abnormal Carbenes
1.586(19) Å and a relative angle to the Cl atom of 164(2)°. It is also independent of the substitution pattern of the aryl
The coordination is distorted octahedrally at the iridi- group. In fact, the recent paper by Li et al.[16] shows iden-
um(III) center. All other characterisations (elemental analy- tical chemistry for ligands bearing alkyl substituents (Me,
sis and mass spectrometry) confirmed the nature of these iPr) on the N3 atom of the imidazolium ring. Thus, this
products.
reactivity pattern appears to be quite general.
A
31P NMR spectroscopic monitoring of the [Ir(COD)-
(µ-Cl)]2/3 reaction at room temperature revealed additional
features. After 5 min, the ligand was completely consumed
and two products were visible: the final product with signal
at δ = 1.1 ppm and an intermediate compound with signal
at δ = 19.4 ppm which quickly disappeared (Scheme 3). Our
hypothesis is that, in a first step, the phosphane coordinates
to the iridium center, splitting the dimer. Subsequently, the
C–H insertion occurs at the C5 position of the imidazolium
ring, possibly assisted by a chelating effect. This hypothesis
is supported by the recent results obtained by Li et al.[16]
However, our observed reactivity differs from the results
Experimental Section
General: All reactions were carried out under dry argon using
Schlenk glassware and vacuum-line techniques. Solvents for synthe-
ses were dried and degassed by standard methods before use. Ele-
mental analyses were carried out by the analytical service of the
1
“Laboratoire de Chimie de Coordination” in Toulouse. H NMR
spectroscopic data were recorded with a Bruker AV-500 spectrome-
ter, operating at 500 MHz. 13C{H,P} and 31P{H} NMR spectro-
scopic data were recorded with a Bruker AV-500 instrument, op-
erating at 125.8 and 202.5 MHz, respectively. 19F NMR spectro-
described by Danopoulos with a similar ligand, where the scopic data were recorded with a Bruker AC-200 instrument, op-
erating at 188 MHz. The spectra were referenced internally using
the signal of the residual protio solvent (1H) or the solvent signals
(13C), the signal of CF3CO2H (10%) in C6D6 (19F) and externally
using 85% H3PO4 for 31P. Mass spectra were obtained from aceto-
nitrile or methanol solutions with a ThermoElectron TSQ7000 in-
strument (electrospray ionisation), and from dmso or dmf solutions
with a Nermag R10-10 instrument (FAB). [Ir(COD)(µ-Cl)]2 was
obtained from Strem and used as received. MesImEtPPh2+Br– (1),
mesityl substituent is replaced by DIPP (2,6-diisopro-
pylphenyl; compound 2).[8] That contribution indicated that
the interaction of [Ir(COD)(µ-Cl)]2 with 2, under unspeci-
fied reaction conditions, afforded the simple addition prod-
uct where the chlorido ligand had been replaced by a bro-
mide ion, [Ir(COD)(Br)(PPh2CH2CH2ImDIPP)], similar to
the proposed intermediate of our reaction leading to 5. In
the interest of checking whether a simple change of aryl
group would enforce such a significant reactivity change,
we decided to repeat the same reaction under conditions
similar to those leading to 4a/4b. The reactions were carried
out in two different solvents (CH2Cl2 or thf), which always
led to complete conversion at room temperature in 20 min
and led to an iridium complex bearing an abnormal car-
DIPP-ImEtPPh2+Br– (2), and MesImEtPPh2+BF4 (3) were pre-
–
pared as described previously.[4]
General Procedure for the Synthesis of IrIII Complexes: In a Schlenk
tube, CH2Cl2 was added to a phosphane–imidazolium salt and
[Ir(COD)(µ-Cl)]2 mixture, and the mixture was stirred at room
temp. for 30 min. The solvent was removed under vacuum, the resi-
due washed with diethyl ether until the ethereal phase remained
bene (mixture of isomers, 6a+6b, Scheme 2). These com- colorless, and then dried under vacuum. These reactions were also
performed in thf without any change in the results.
pounds were fully characterised by NMR spectroscopy and
mass spectrometry, leaving no doubt about their nature. In-
deed, the NMR spectra present many similar features to
those of complexes 4a and 4b; the 1H NMR spectrum
(Chlorido)(1,5-cyclooctadiene){1-[2-(diphenylphosphanyl)ethyl]-3-
(2,4,6-trimethylphenyl)imidazol-5-ylidene}iridium Bromide and (Bro-
mido)(1,5-cyclooctadiene){1-[2-(diphenylphosphanyl)ethyl]-3-(2,4,6-
shows four signals corresponding to the imidazole ring pro- trimethylphenyl)imidazol-5-ylidene}iridium
Chloride
(4a+4b):
CH2Cl2 (3 mL), MesImEtPPh2+Br– (1) (60 mg, 125.4 µmol), and
[Ir(COD)(µ-Cl)]2 (46 mg, 68.5 µmol). A pale-yellow, air-sensitive
product was obtained. Yield: 94 mg (92%). C34H40BrClIrN2P·
CHCl3 (934.66): calcd. C 44.98, H 4.42, N 3.00; found C 45.01, H
tons at δ = 9.73, 9.71, 6.35, and 6.28 ppm, with integration
values of 0.5 each, for the mixture of 6a and 6b. We also
1
observe two equivalent H NMR hydride doublets at δ =
–15.07 and –14.41 ppm (Figure 1c) and two signals at δ =
–2.04 and –3.08 ppm in the 31P NMR spectrum, corre-
sponding to the two isomers. Moreover, the mass spectrum
clearly shows two peaks at m/z = 777.9 and 821.8, assigned
to cations 6a+ and 6b+, respectively.
4.35,
N 2.80. MS (FAB, mNBA matrix): m/z (%) = 627
(100) [C26H28ClIrN2P+], 671 (92) [C26H26BrIrN2P+], 735 (34)
[C34H40ClIrN2P+], 779 (36) [C34H40BrN2IrP+]. First Isomer: 1H
NMR (500 MHz, CDCl3, 20 °C): δ = 9.74 (s, 1 H, NCHN), 7.88–
7.98 [m, 2 H, o-CH(Ph2)], 7.54–7.64 [m, 3 H, m,p-CH(Ph2)], 7.32–
7.51 [m, 5 H, o,m,p-CH(Ph1)], 6.92 [br. s, 2 H, CH(Mes)], 6.18 (d,
3J = 1.4 Hz, 1 H, MesNCH=), 5.74–5.83 (m, 1 H, NCH2), 5.29–
5.33 [m, 1 H, CH(COD)], 5.17–5.23 [m, 1 H, CH(COD)], 4.61–4.69
[m, 1 H, CH(COD)], 3.83–3.91 (m, 1 H, NCH2), 3.73–3.81 [m,
1 H, CH(COD)], 3.37–3.55 (m, 1 H, CH2P), 3.01–3.12 [m, 1 H,
CH2(COD)], 2.65–2.80 [m, 4 H, CH2(COD); CH2P], 2.40–2.60 [m,
2 H, CH2(COD)], 2.25–2.40 [m + s, 4 H, CH2(COD); p-CH3], 1.90–
Conclusions
We have described an unusual reactivity of chelating
phosphane–imidazolium salts towards low-oxidation-state
iridium complexes. In the absence of a base, we have shown
that the C–H insertion at the C5 position of the imid-
azolium ring is the only occurring reaction, with no normal
NHC observed. Contrary to related iridium chemistry pre-
viously reported by the Crabtree group,[12] this reactivity is
2
2.12 [m + s, 7 H, CH2(COD); o-CH3], –14.55 (d, JP,H = 8.1 Hz, 1
H, IrH) ppm. 13C NMR (125.8 MHz, CDCl3, 20 °C): δ = 140.2 [s,
p-C(Mes)], 137.1 (s, NCHN), 135.0, 134.1 [s, o-C(Mes)], 134.5 [d,
2JC,P = 10.4 Hz, o-CH(Ph2)], 132.9 [d, JC,P = 7.8 Hz, o-CH(Ph1)],
2
132.6 [d, JC,P = 2 Hz, p-CH(Ph2)], 131.7 [d, JC,P = 2 Hz, p-
4
4
independent of the nature of the imidazolium counteranion. CH(Ph1)], 131.5 [s, NC(Mes)], 129.5 [d, 3JC,P = 15 Hz, m-CH(Ph2)],
Eur. J. Inorg. Chem. 2008, 3024–3030
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J. Wolf, A. Labande, J.-C. Daran, R. Poli
FULL PAPER
129.4, 129.3 [s, CH(Mes)], 128.6 [d, i-C(Ph2)], 128.1 [d, JC,P
=
CH(COD)], 94.6 [d, JC,P = 9.4 Hz, CH(COD)], 94.1, 84.4 [s,
3
3
10.6 Hz, m-CH(Ph1)], 128.0 [d, i-C(Ph1)], 123.8 (s, MesNCH=),
CH(COD)], 45.7 (s, NCH2), 35.6, 30.7 [s, CH2(COD)], 29.6 [d,
2
2
3
119.9 (d, JC,P = 7.9 Hz, IrC), 96.7 [d, JC,P = 16 Hz, CH(COD)], 3JC,P = 2.1 Hz, CH2(COD)], 28.0 [d, JC,P = 3.8 Hz, CH2(COD)],
2
1
93.3 [d, JC,P = 9.5 Hz, CH(COD)], 91.7, 82.4 [s, CH(COD)], 45.3 25.1 (d, JC,P = 39.7 Hz, CH2P), 20.8 [s, p-CH3(Mes)], 17.1, 17.0
(s, NCH2), 34.1 [d, JC,P = 2 Hz, CH2(COD)], 31.6, 30.0 [s, [s, o-CH3(Mes)] ppm. 31P NMR (202.5 MHz, CD2Cl2, 20 °C): δ =
3
3
1
CH2(COD)], 29.7 [d, JC,P = 2 Hz, CH2(COD)], 25.0 (d, JC,P
=
2.42 (s, PPh2) ppm. 19F NMR (188 MHz, CD2Cl2, 20 °C): δ =
40.1 Hz, CH2P), 21.1 [s, p-CH3(Mes)], 17.9, 17.7 [s, o-CH3(Mes)] –76.2 (s, BF4) ppm.
ppm. 31P NMR (202.5 MHz, CDCl3, 20 °C): δ = –2.39 (s, PPh2)
ppm. Second Isomer: 1H NMR (500 MHz, CDCl3, 20 °C): δ = 9.74
(s, 1 H, NCHN), 7.88–7.98 [m, 2 H, o-CH(Ph2)], 7.54–7.64 [m, 3
H, m,p-CH(Ph2)], 7.32–7.51 [m, 5 H, o,m,p-CH(Ph1)], 6.94 [br. s, 2
H, CH(Mes)], 6.24 (d, 3J = 1.4 Hz, 1 H, MesNCH=), 5.74–5.83
(m, 1 H, NCH2), 5.35–5.41 [m, 1 H, CH(COD)], 5.06–5.11 [m, 1
H, CH(COD)], 4.61–4.69 [m, 1 H, CH(COD)], 4.07–4.17 (m, 1 H,
NCH2), 3.63–3.69 [m, 1 H, CH(COD)], 3.37–3.55 (m, 1 H, CH2P),
3.01–3.12 [m, 1 H, CH2(COD)], 2.65–2.80 [m, 4 H, CH2(COD);
CH2P], 2.40–2.60 [m, 2 H, CH2(COD)], 2.25–2.40 [m + s, 4 H,
CH2(COD); p-CH3], 1.90–2.12 [m + s, 7 H, CH2(COD); o-CH3],
(Chlorido)(1,5-cyclooctadiene){1-[2-(diphenylphosphanyl)ethyl]-3-
(2,6-diisopropylphenyl)imidazol-5-ylidene}iridium Bromide (6a+6b):
CH2Cl2 (3 mL), DIPP-ImEtPPh2+Br– (2) (82 mg, 157 µmol), and
[Ir(COD)(µ-Cl)]2 (53 mg, 79 µmol). A pale-yellow, air-sensitive
product was obtained. Yield: 118 mg (87 %). C37H46BrClIrN2P·
CH2Cl2 (942.30): calcd. C 48.44, H 5.13, N 2.97; found C 48.41,
H 5.13, N 2.92. ESI-MS (positive mode): m/z (%) = 777.9 (100)
[C37H46ClIrN2P+], 821.8 (33) [C37H46BrIrN2P+]. First Isomer: 1H
NMR (500 MHz, CD2Cl2, 20 °C): δ = 9.73 (d, 4J = 1.1 Hz, 1 H,
NCHN), 8.02–8.05 [m, 2 H, o-CH(Ph2)], 7.63–7.69 [m, 3 H, m,p-
CH(Ph2)], 7.39–7.55 [m, 5 H, o,m,p-CH(Ph1)], 7.32 [d, 3J = 6.5 Hz,
2
–15.22 (d, JP,H = 8.3 Hz, 1 H, IrH) ppm. 13C NMR (125.8 MHz,
3
1 H, m-CH(DIPP)], 7.31 [d, J = 6.6 Hz, 1 H, m-CH(DIPP)], 6.28
CDCl3, 20 °C): δ = 140.2 [s, p-C(Mes)], 137.4 (s, NCHN), 134.8,
3
2
134.2 [s, o-C(Mes)], 134.4 [d, JC,P = 10.4 Hz, o-CH(Ph2)], 132.8
[d, J = 1.6 Hz, 1 H, (DIPP)NCH=], 5.70–5.78 (m, 1 H, NCH2),
[d, 2JC,P = 7.9 Hz, o-CH(Ph1)], 133.3 [d, 4JC,P = 11 Hz, p-CH(Ph2)],
5.31–5.36 [m, 1 H, CH(COD)], 5.16–5.20 [m, 1 H, CH(COD)],
4.67–4.75 [m, 1 H, CH(COD)], 3.89–3.97 (m, 1 H, NCH2), 3.66–
3.74 [m, 1 H, CH(COD)], 3.54–3.61 (m, 1 H, CH2P), 3.00–3.09 [m,
1 H, CH2(COD)], 2.66–2.91 [m, 3 H, CH2(COD); CH2P], 2.54–2.63
[m, 1 H, CH2(COD)], 2.32–2.52 [m, 4 H, CH2(COD); CH(CH3)2],
1.90–2.12 [m, 1 H, CH2(COD)], 1.16–1.26 [m, 12 H, CH(CH3)2],
4
131.6 [d, JC,P = 2 Hz, p-CH(Ph1)], 131.5 [s, NC(Mes)], 129.6 [d,
3JC,P = 15 Hz, m-CH(Ph2)], 129.4, 129.3 [s, CH(Mes)], 128.6 [d, i-
C(Ph2)], 128.2 [d, 3JC,P = 10.4 Hz, m-CH(Ph1)], 128.0 [d, i-C(Ph1)],
2
2
123.5 (s, MesNCH=), 121.1 (d, JC,P = 8.1 Hz, IrC), 98.6 [d, JC,P
2
= 16.2 Hz, CH(COD)], 93.8 [d, JC,P = 9.1 Hz, CH(COD)], 93.9,
2
–14.41 (d, JP,H = 8.2 Hz, 1 H, IrH) ppm. 13C NMR (125.8 MHz,
83.7 [s, CH(COD)], 45.6 (s, NCH2), 35.5, 31.0 [s, CH2(COD)], 29.6
3
3
CD2Cl2, 20 °C): δ = 146.0, 145.3 [s, o-C(DIPP)], 137.4 (s, NCHN),
[d, JC,P = 2 Hz, CH2(COD)], 28.2 [d, JC,P = 2 Hz, CH2(COD)],
2
2
1
134.6 [d, JP,C = 10.5 Hz, o-CH(PPh2)], 133.0 [s, JP,C = 6.7 Hz, o-
24.9 (d, JC,P = 39.5 Hz, CH2P), 21.1 [s, p-CH3(Mes)], 17.8, 17.6
CH(PPh2)], 132.5 [d, JP,C = 2.6 Hz, p-CH(PPh2)], 131.4 [d, 4JP,C
=
4
[s, o-CH3(Mes)] ppm. 31P NMR (202.5 MHz, CDCl3, 20 °C): δ =
–1.14 (s, PPh2) ppm.
2.7 Hz, p-CH(PPh2)], 131.2 [s, NC(Mes)], 131.0 [s, p-CH(DIPP)],
3
3
129.4 [d, JP,C = 10.5 Hz, m-CH(PPh2)], 127.9 [d, JP,C = 10.5 Hz,
m-CH(PPh2)], 125.5 [d, 3JC,P = 8.5 Hz, (DIPP)NCH=], 124.3, 124.1
(Chlorido)(1,5-cyclooctadiene){1-[2-(diphenylphosphanyl)ethyl]-3-
2
2
(2,4,6-trimethylphenyl)imidazol-5-ylidene}iridium Tetrafluoroborate
[s, m-CH(DIPP)], 120.1 (d, JC,P = 8.4 Hz, IrC), 96.8 [d, JP,C =
–
(5): CH2Cl2 (3 mL), MesImEtPPh2+BF4 (3) (60 mg, 123 µmol), 16.2 Hz, CH(COD)], 93.8 [d, 2JP,C = 9.0 Hz, CH(COD)], 91.7, 82.7
and [Ir(COD)(µ-Cl)]2 (43 mg, 63 µmol). A cream-white, air-sensi-
tive product was obtained. Yield: 87 mg (86%). Suitable X-ray crys-
tals were obtained by layer diffusion of pentane into a CH2Cl2
[s, CH(COD)], 45.4 (s, NCH2), 33.7 [d, 3JP,C = 2.1 Hz, CH2(COD)],
3
31.9 [s, CH2(COD)], 29.9 [d, JP,C = 4.3 Hz, CH2(COD)], 29.7 [d,
3JP,C = 2.2 Hz, CH2(COD)], 28.5, 28.4 [s, CH(CH3)2], 25.0 (d, 1JC,P
solution at –20 °C. C34H40BClF4IrN2P·0.5CH2Cl2 (864.66): calcd. = 40.3 Hz, CH2P), 24.3, 24.2, 24.1, 24.0 [s, CH (CH3)2] ppm. 31P
C 47.93, H 4.78, N 3.24; found C 47.53, H 4.90, N 3.36. ESI-MS
NMR (202.5 MHz, CD2Cl2, 20 °C): δ = –3.08 (s, PPh2) ppm. Sec-
1
(positive mode): m/z (%) = 627.1 (10) [C26H28ClIrN2P+], 735.1
ond Isomer: H NMR (500 MHz, CD2Cl2, 20 °C): δ = 9.71 (d, 4J
(100) [C34H40ClIrN2P+]. ESI-MS (negative mode): m/z (%) = 87
= 1.2 Hz, 1 H, NCHN), 7.98–8.01 [m, 2 H, o-CH(Ph2)], 7.63–7.69
–
(100) [BF4 ]. 1H NMR (500 MHz, CD2Cl2, 20 °C): δ = 8.45 (s, 1 [m, 3 H, m,p-CH(Ph2)], 7.39–7.55 [m, 5 H, o,m,p-CH(Ph1)], 7.36
H, NCHN), 7.99 [dd, 3J = 7 Hz; 3JP,H = 11.5 Hz, 2 H, o-CH(Ph2)],
7.63–7.72 [m, 3 H, m,p-CH(Ph2)], 7.43–7.57 [m, 5 H, o,m,p-
CH(Ph1)], 7.04 [br. s, 2 H, CH(Mes)], 6.40 (d, 4J = 1 Hz, 1 H,
[d, J = 7.9 Hz, 1 H, m-CH(DIPP)], 7.35 [d, J = 7.9 Hz, 1 H, m-
CH(DIPP)], 6.35 [d, 3J = 1.5 Hz, 1 H, (DIPP)NCH=], 5.70–5.78
(m, 1 H, NCH2), 5.37–5.43 [m, 1 H, CH(COD)], 5.10–5.17 [m, 1
3
3
MesNCH=), 5.47–5.54 [m, 1 H, CH(COD)], 5.14 (dddd, 2,3J = 2.3, H, CH(COD)], 4.67–4.75 [m, 1 H, CH(COD)], 4.20–4.27 (m, 1 H,
3
7.6, 14.3 Hz; JP,H = 27.4 Hz, 1 H, NCH2), 5.05–5.12 [m, 1 H, NCH2), 3.76–3.83 [m, 1 H, CH(COD)], 3.38–3.43 (m, 1 H, CH2P),
CH(COD)], 4.73–4.77 [m, 1 H, CH(COD)], 4.12 (ddd, 2,3J = 11,
3.00–3.09 [m, 1 H, CH2(COD)], 2.66–2.91 [m, 3 H, CH2(COD);
3
12 Hz; JP,H = 19.6 Hz, 1 H, NCH2), 3.62–3.69 [m, 1 H, CH2P], 2.54–2.63 [m, 1 H, CH2(COD)], 2.32–2.52 [m, 4 H,
CH(COD)], 3.49–3.58 (m, 1 H, CH2P), 3.02–3.12 [m, 1 H, CH2(COD); CH(CH3)2], 1.90–2.12 [m, 1 H, CH2(COD)], 1.16–1.26
2
CH2(COD)], 2.92–3.00 [m, 1 H, CH2(COD)], 2.66–2.82 [m, 3 H, [m, 12 H, CH(CH3)2], –15.07 (d, JP,H = 8.1 Hz, 1 H, IrH) ppm.
CH2(COD); CH2P], 2.47–2.58 [m, 2 H, CH2(COD)], 2.32–2.42 [m
+ s, 4 H, CH2(COD); p-CH3], 2.00–2.15 [m + s, 7 H, CH2(COD);
13C NMR (125.8 MHz, CD2Cl2, 20 °C): δ = 145.9, 145.4 [s, o-
2
C(DIPP)], 137.6 (s, NCHN), 134.4 [d, JP,C
= 10.5 Hz, o-
2
2
4
o-CH3], –15.12 (d, JP,H = 8.3 Hz, 1 H, IrH) ppm. 13C NMR
CH(PPh2)], 132.9 [s, JP,C = 8.0 Hz, o-CH(PPh2)], 132.5 [d, JP,C =
2.4 Hz, p-CH(PPh2)], 131.4 [d, JP,C = 2.5 Hz, p-CH(PPh2)], 131.1
4
(125.8 MHz, CD2Cl2, 20 °C): δ = 140.6 [s, p-C(Mes)], 135.9 (s,
2
3
NCHN), 134.8, 134.4 [s, o-C(Mes)], 134.3 [d, JC,P = 7.3 Hz, o- [s, NC(Mes)], 131.0 [s, p-CH(DIPP)], 129.4 [d, JP,C = 10.5 Hz, m-
2
4
3
3
CH(Ph2)], 132.8 [d, JC,P = 8 Hz, o-CH(Ph1)], 132.6 [d, JC,P
=
CH(PPh2)], 128.1 [d, JP,C = 10.6 Hz, m-CH(PPh2)], 125.3 [d, JC,P
= 8.5 Hz, (DIPP)NCH=], 124.3, 124.2 [s, m-CH(DIPP)], 120.2 (d,
2.3 Hz, p-CH(Ph2)], 131.4 [d, JC,P = 2.6 Hz, p-CH(Ph1)], 131.3 [s,
4
NC(Mes)], 129.5 [d, JC,P = 10.6 Hz, m-CH(Ph2)], 129.4 [br. s,
2JC,P = 8.6 Hz, IrC), 98.7 [d, JP,C = 15.7 Hz, CH(COD)], 94.2 [d,
3
2
1
1
CH(Mes)], 128.8 [d, JC,P = 58.7 Hz, i-C(Ph1)], 128.6 [d, JC,P
=
2JP,C = 9.3 Hz, CH(COD)], 93.9, 84.2 [s, CH(COD)], 45.8 (s,
58.7 Hz, i-C(Ph2)], 128.1 [d, JC,P = 10.5 Hz, m-CH(Ph1)], 124.5 (s, NCH2), 35.2 [d, JP,C = 2.1 Hz, CH2(COD)], 32.2 [s, CH2(COD)],
3
3
MesNCH=), 121.4 (d, 2JC,P = 9.2 Hz, IrC), 98.7 [d, 2JC,P = 15.6 Hz,
29.4 [d, JP,C = 2.1 Hz, CH2(COD)], 28.6, 28.5 [s, CH(CH3)2], 28.3
3
3028
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Eur. J. Inorg. Chem. 2008, 3024–3030

Hydridoiridium(III) Complexes Bearing Abnormal Carbenes
3
1
[d, JP,C = 3.9 Hz, CH2(COD)], 25.1 (d, JC,P = 39.6 Hz, CH2P),
(F.S.E.) for a Ph.D. fellowship to J. W., and Yannick Coppel for
24.3, 24.2, 24.1, 24.0 [s, CH(CH3)2] ppm. 31P NMR (202.5 MHz, NMR spectroscopic analysis of the iridium complexes.
CD2Cl2, 20 °C): δ = –2.04 (s, PPh2) ppm.
Crystallographic Data: A single crystal was mounted under inert
perfluoropolyether on the tip of a glass fiber and cooled in the
cryostream of a Bruker APEX2 diffractometer. Data were collected
using the monochromatic Mo-Kα radiation (λ = 0.71073). The final
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Table 2. Crystallographic data for compound 5.
5
Empirical formula
Formula mass
C36H44BCl5F4IrN2P
991.96
Temperature/K
Crystal system
Space group
180(2)
triclinic
¯
P1
a/Å
b/Å
10.071(5)
15.126(5)
c/Å
α/°
15.988(5)
68.528(5)
β/°
74.532(5)
78.030(5)
2168.0(15)
γ/°
V/Å3
Z
2
Density
1.520
3.468
µ/mm–1
F(000)
984
Range for data collection θ/°
Reflections collected
Independent reflections
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices for all data
30.5 Ͼ θ Ͼ 1.4
57426
13227 [R(int) = 0.0612]
1.087
R1 = 0.0481, wR2 = 0.1217
R1 = 0.0628, wR2 = 0.1267
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Acknowledgments
We thank the Centre National de la Recherche Scientifique
(C.N.R.S.) for support of this work, the Fonds Social Européen
Eur. J. Inorg. Chem. 2008, 3024–3030
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3029

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Received: March 13, 2008
Published Online: May 21, 2008
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Eur. J. Inorg. Chem. 2008, 3024–3030