Syntheses and molecular structures of 18/16-electron half-sandwich iridium(III) complexes with chelating anilido-imine ligands

Article abstract of DOI:10.1016/j.jorganchem.2008.05.002

A 18-electron complex Cp^*IrCl[o-C₆H₄N(C₆H₃-Me-p) (CH{double bond, long}NC₆H₃-Me-p)] (Cp^* = η⁵-pentamethylcyclopentadienyl) (1a) was obtained by the reaction

Full text of DOI:10.1016/j.jorganchem.2008.05.002

Journal of Organometallic Chemistry 693 (2008) 2597–2602
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Syntheses and molecular structures of 18/16-electron half-sandwich iridium(III)
complexes with chelating anilido-imine ligands
*
Xia Meng, Yue-Jian Lin, Guo-Xin Jin
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200 433, China
a r t i c l e i n f o
a b s t r a c t
A 18-electron complex Cp*IrCl[o-C6H4N(C6H3-Me-p) (CH@NC6H3-Me-p)] (Cp* =
g
5-pentamethylcyclopen-
Article history:
Received 18 January 2008
Received in revised form 29 April 2008
Accepted 6 May 2008
tadienyl) (1a) was obtained by the reaction of the lithium salt of o-C6H4N (C6H3-Me-p)(CH@NHC6H3-Me-p)
(L1) with [Cp*IrCl(
l
-Cl)]2 in toluene. However, when bulkier ligands (L2 = o-C6H4N(C6H3-Me-
p)(CH@NHC6H3-i-Me2-2,6), L3 = o-C6H4N(C6H3-Me-p) (CH@NHC6H3-i-Pr2-2,6)) were employed in the
same reaction, two 16-electron complexes {Cp*Ir[o-C6H4N(C6H3-Me-p)(CH@NC6H3-i-Me2-2,6)]}+Clꢀ
(2b) and {Cp*Ir[o-C6H4N(C6H3-Me-p)(CH@NC6H3-i-Pr2-2,6)]}+Clꢀ (3b) were formed. A 16-electron com-
plex {Cp*Ir [o-C6H4N(C6H3-Me-p) (CH@NC6H3-Me-p)]}+SO3 CF3ꢀ (1b) bearing L1 could be achieved by the
reaction of 1a with AgSO3CF3 in CH3CN solution. The molecular structures of 1a and 2b were determined
by X-ray crystallography. Theoretical calculations of all the 18/16-electron species were performed to study
their bonding characters and electronic properties. Electron donating effect of Cp* and steric effect of ani-
lido-imine ligand were considered as major factors in the formation of coordinative unsaturated complexes
1b, 2b, 3b.
Available online 10 May 2008
Dedicated to Herr Professor Dr. Wolfgang A.
Herrmann on the occasion of his 60th
birthday.
Keywords:
Iridium
Half-sandwich complexes
Anilido-imine ligands
Coordinative unsaturated
Molecular structures
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
gand were synthesized (Scheme 1) and coordinative unsaturated
complexes were obtained when bulky substitute AnIm were in-
Coordinative unsaturated complexes have attracted much
attention for the amazing chemistry they demonstrate [1,2]. In
the past decade, bulky aryl-substituted b-diketimine has been dra-
matically developed because of its strong electron donation and
steric constraints that can stabilize low-coordinate main group
and late transition metal complexes such as three coordinated
Zn, Cu, Ni, Ga complexes [3]. Chelating anilido-imine (AnIm) ligand
has similar steric and electronic features with b-diketimine, and a
volved. Some detailed studies on these 18/16-electron complexes
were performed to explore their electronic and steric features.
2. Results and discussion
2.1. Syntheses of complexes
Anilido-imine ligands ortho-C6H4 (NHAr1)(CH@NAr2) L1–L5
were prepared in good yields by the reaction of ortho-
C6H4F(CH@NAr2) with corresponding LiN(H)Ar1 (Scheme 2)
according to the literature [6]. These ligands were characterized
by 1H NMR and IR spectroscopy. The NH resonances characteris-
tically appear at low field. The IR absorption bands of the imine
C@N stretch occur in the region 1620–1623 cmꢀ1 [5,6]. After the
AnIm ligands L1–L3 were treated with n-BuLi to give correspond-
rigid framework could protect the ligand backbone from a-carbon
attack which brings complexity to the products [4]. Since 2003,
complexes containing AnIm ligand was synthesized, some of them
shown excellent properties of fluorescence emission, such as Y, Al,
B complexes, etc. [4a,4e,4f,4i], others were used as ancillary ligands
for the mechanism and dynamic studies to stabilize reaction inter-
mediates [4c,4h]. At the same time, iridium complexes have long
been considered as a promising catalyst for many organic reactions
[5], for example for ketone and aldehyde hydrogenation, alcohol
dehydrogenation and C–H bond activation to synthesize organic
compounds. Thus, the building of half-sandwich iridium complex
with a proper ancillary ligand is an interesting and important sub-
ject. In this report, half-sandwich iridium complexes with AnIm li-
ing lithium salts in toluene solution, 1/2 equiv. of [Cp*IrCl(
l-Cl)]2
was added to give a dark red solution, and iridium complexes
1a, 2b and 3b were obtained in relatively high yields. (1) All
the complexes were air stable in solid state and well soluble
in hexane. X-ray crystallographic analysis confirms that 1a is
an 18-electron half-sandwich complex, while 2b which contains
a bulkier ligand is an unexpected 16-electron complex. However,
when ligands L4 and L5 were treated with the same procedure,
only starting materials were separated after reaction. This sug-
* Corresponding author. Tel.: + 86 21 65643776; fax: +86 21 65641740.
E-mail address: gxjin@fudan.edu.cn (G.-X. Jin).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.05.002

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X. Meng et al. / Journal of Organometallic Chemistry 693 (2008) 2597–2602
R2
R1
Cl
NH
N
Ir
R1
i), ii)
N
N
L1 R1=H, R2=Me
L2 R1=Me, R2=H
L3 R1=iso-Pr, R2=H
1a
AgSO3CF3/ CH3CN,
CH3CN
i), ii)
R2
R1
Ir
Ir
N
N
N
N
R1
SO3CF3
Cl
2b R1=Me, R2=H
3b R1=iso-Pr, R2=H
1b
i). n-BuLi, THF
ii) (Cp*IrCl)2Cl2, toluene, r.t.
Scheme 1. Synthesis of complexes 1a, 1b, 2b and 3b.
The 1H NMR of 1a, 2b and 3b show CH@N resonances at ca.
8.82–8.84 ppm. The hydrogen at Cp* of 1a and 2b is at a high field
of 1.16–1.18 ppm as a single signal, but the hydrogen of Cp* from
3b shift to a lower field at 1.52 ppm, indicating a remarkable repul-
sion between Cp* and AnIm ligand which reduces the overlap be-
tween Cp* and the metal center. The H atoms on methyl and
isopropyl which connect to the phenyl at imine nitrogen split into
two and four sets respectively, indicating that there is no mirror
plane in the molecules. Compared with the 18-electron complex
1a, almost all the hydrogen in 16-electron complex 1b slightly shift
into lower field, due to the positive charge it takes. The IR absorp-
tion bands of the imine C@N stretch blue shift to the region 1610–
1600 cmꢀ1 in comparison with the free ligands at about 1620 cmꢀ1
[6].
R3
R1
N
NH2
R1
R1
F
O
F
R1
R3
H
n-hexane,
MgSO4
25 ˚C
NHLi
R3
4
R2
R2
R2
R1
N
R4
2.2. Crystal Structures
NH
R2
R1
THF 25 ˚C
Single crystals of complexes 1a and 2b suitable for X-ray crys-
tallographic analysis were obtained by recrystallization of solvent
from n-hexane and toluene solution at low temperature, respec-
tively. The ORTEP diagrams of the molecular structures of these
complexes are shown in Figs. 1 and 2. Crystallographic data for
1a and 2b are summarized in Table 1. 1a and 2b were crystallized
in the monoclinic space group P21/n. Molecular structure analysis
reveals that 1a is neutral 18-electron species containing a chelating
L1, R1=R2=H, R3=R4=Me
L3, R1=i-Pr, R2=R3=H, R4=Me
L5, R1=R2=i-Pr, R3=R4=H
L2,R1=Me,R2= R3=H, R4=Me
L4, R1=R2=Me, R3=R4=H
anilido-imine ligand,
a g
5-Pentamethylcyclopentadiene (Cp*)
Scheme 2. Synthesis of ligands L1–L5.
group and a chloride, while 2b is a 16-electron cation with a chlo-
ride as equilibrium ion. The metal center of complex 1a adopts dis-
torted three-leg piano stool geometry [8,9], which is different from
the two-legged geometry of 2b. The dihedral angle between the
Ir1–N1–C1–C2–C3–N2 plane and Cp* is 63.2° for 1a. But for 2b,
these two planes are almost perpendicular (88.9°). In complex 1a
and 2b, the six-membered chelating rings are almost in the same
plane [5,6]. The aromatic groups connect to the amido and imino
nitrogen lie approximately parallel with the Cp*. The imino C@N
gests that bulky groups at phenyls which connect to the amido
and imino nitrogen atoms in the AnIm ligands greatly affect
the formation and stability of the expected products. A 16-elec-
tron complex with L1 could be achieved by changing Clꢀ into a
larger anion. When AgSO3CF3 solution in CH3CN was added into
a solution of 1a in toluene, bright red complex 1b was obtained
and characterized by 1H NMR and elemental analysis.

X. Meng et al. / Journal of Organometallic Chemistry 693 (2008) 2597–2602
2599
Table 1
Crystallographic data for 1a and 2b
Formula
Unit cell
Formula weight
Space group
a (Å)
C31H34ClIrN2 (1a)
Monoclinic
662.25
P2(1)/c
11.482(3)
27.835(7)
8.634(2)
2734.9(1)
90
C32H36ClIrN2 (2b)
Monoclinic
676.28
P2(1)/c
21.019(7)
8.143(3)
20.698(7)
3161.3(2)
90
b (Å)
c (Å)
Volume (Å3)
a
(°)
b (°)
97.647(4)
90
116.826(4)
90
c
(°)
Z
4
4
Temperature (K)
293(2)
293(2)
l
(Mo K
a
) (A)
0.71073
1.608
0.0301
0.0628
1.062
0.71073
1.421
0.0400
0.0899
0.939
Density (mg/m3)
a
R1 [I > 2
r
(I)]
b
wR2
Goodness-of-fit on F2
P
P
a
Fig. 1. Thermal ellipsoid plot of 1a (50% probability thermal ellipsoids). Selected
bond lengths (Å) and angles (°): Ir1–N2 2.085(4), Ir1–N1 2.106(4), Ir1–Cl1 2.489-
0(13), N1–C1 1.356(6), N2–C3 1.299(6), N2–Ir1–N1 87.96(15), N2–Ir1–Cl1 84.54
(11), N1–Ir1–Cl1 85.56(12).
R1
=
(||Fo| ꢀ |Fc||)/ |Fo|.
P
P
2
2
2
1=2
wR2 ¼ ½ ðjFoj ꢀ jFcj Þ = ðF2oÞꢁ
.
b
sition of the metal center. Besides, the similarity of absorption
bands of 18 and 16 electron complexes suggests that the electronic
features of these complexes are similar (see Fig. 3).
The cyclic voltammetery studies of complex 1a shows a quasi-
reversible reduction wave at ꢀ1.09 V which can be assigned to
the reduction process of 1a ? 1aꢀ [10]. However, complexes 1b,
2b and 3b present irreversible reductive waves at ꢀ1.00 V,
ꢀ1.06 V and ꢀ1.10 V. The wave declined quickly after several laps,
indicating 1bꢀ, 2bꢀ and 3bꢀ are unstable species. The different
electrochemical behaviors can be explained by different HOMO
and LUMO characters in 16 and 18 electron complexes. All the
compounds L1, L2, and L3 do not show any distinct reductive waves
in the experiment.
2.4. Theoretical calculations
DFT calculation was performed [11,12] in order to study the elec-
tronic properties of complexes 1a, 1b, 2b and 3b, and find out why
coordinative unsaturated complexes could be stabilized by AnIm li-
gands. Geometry optimization of the singlet state of the complexes
1a and 2b led to similar structures which were in good agreement
withexperimentaldata. Structuresof 1band3b werebuiltontheba-
sis of 2b and optimized for comparison. 18-electron structure of 3b
build on the basis of 1a was proved to be an unstable conformation
during the geometry optimization. 1b, 2b and 3b have similar con-
figuration and HOMO/LUMO distribution. The orbital energy dia-
gram for the frontier orbits of complex 1a, 1b and 2b is shown in
Fig. 4. The three complexes have similar energy gap between HOMO
and LUMO. But the HOMO and LUMO of 1a are about 4.7 eV higher
than those of 1b and 2b. In complex 1b and 2b, the frontier orbits
are mainly comprised of contributions from the dxz, dyz orbits of Ir,
pz orbits of N1, N2, and pz orbits associated with other atoms of the
chelating ligand.
From the orbital diagram, we can infer that, in the 16-electron
complex 2b, HOMO is a bonding combination originating mainly
from AnIm ligands with a small metal contribution. And LUMO
mainly locates on the iridium atom and Cp* group with strong bond-
ing character, but shows anti-bonding character between Ir and
AnIm ligand. However, in the 18-electron complex 1a, HOMO has
a anti-bonding character and LUMO has a weak bonding character
between the Ir and N. The different feature of frontier orbits between
1a and 2b gives us an explanation of the different cyclic voltamme-
tery behavior which has been mentioned previously. Adding an elec-
tron to the LUMO of 1a will slightly intensify the bond between Ir
Fig. 2. Thermal ellipsoid plot of 2b (50% probability thermal ellipsoids). Chloride
anion was deleted for clarity. Selected bond lengths (Å) and angles (°): Ir1–N2
1.976(4), Ir1–N1 2.007(4), N1–C1 1.294(7), N2–C7 1.370(6), Ir1–C23 2.164(5), Ir1–
C25 2.175(6), Ir1–C26 2.199(6), Ir1–C27 2.217(6), Ir1–C24 2.221(5), N2–Ir1–N1
88.34(17).
bonds retain their double bond character which have already been
reported in the complexes containing AnIm ligand according to the
literatures [5,6]. The two Ir–N bonds in 1a (Ir(1)–N(2), 2.085(4) Å;
Ir(1)–N(1), 2.106(4) Å) are distinctly shorter than those bonds in 2b
(Ir(1)–N(2), 1.976(4) Å; Ir(1)–N(1), 2.007(4) Å), due to the stronger
electron affinity of the metal center which takes more positive
charge in complex 2b. The Ir–Cl bond in complex 1a is 2.489 Å
aligned with literatures [7,8].
2.3. Absorption spectroscopy and electrochemical properties of 1a, 1b,
2b, and 3b
The electronic spectrums of 1a, 1b, 2b, and 3b show three tran-
sitions at 270–290 nm, 325–345 nm and 420 nm in CH2Cl2. Com-
pared with free ligands, the absorption bands around 280 nm,
which could be assigned to the
p ? p
* transitions, are similar with
the bands in free ligands. The absorptions bond at 325–345 nm,
which are not observed in free ligands, must be assigned to the
p
?
p* transition of Cp* and the broad moderate intense absorp-
tions at 400–500 nm may receive contribution mainly from
p
? p
* transition of chelating ligands [4e,4i], LMCT and d ? d tran-

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X. Meng et al. / Journal of Organometallic Chemistry 693 (2008) 2597–2602
Fig. 3. UV–Vis spectra of 1a, 1b, 2b, 3b, L1, L2, and L3 in CH2Cl2.
Fig. 4. Orbital energy diagram for the frontier orbitals of 1a, 1b and 2b.
formation of 16-electron species, Cp* contributes as an electron
donating group to share positive charge of the complex, and the
AnIm behaves as a bulky ancillary ligand to protect the metal cen-
ter from outside attack.
Table 2
Calculated atomic charge distribution of the studied complexes
Ir
Cp*
Anilido-imine
1a
1b
2b
3b
0.24
0.46
0.43
0.36
0.37
0.59
0.60
0.61
ꢀ0.28
ꢀ0.05
ꢀ0.03
0.03
3. Conclusion
In this work, we have reported novel 18/16-electron iridium
complexes 1a, 1b, 2b and 3b containing anilido-imine and Cp* li-
gand. Crystal structures of 1a and 2b have been determined. All
of these complexes were studied by IR, 1H NMR, UV–Vis spectra,
elemental analyses, and cyclic voltammetery. DFT calculation helps
us to understand the electronic feature of these coordinate unsat-
urated complexes. Different frontier orbit distribution of the 18
and 16 electron complexes affect their electrochemical properties.
It is believed that the combination of electron donation from Cp*
and bulky substitution of AnIm ligand contribute to the stabiliza-
tion of 16-electron complex. A deep understanding on this subject
may help us to design and develop new complexes with controlla-
ble electronic and steric factors.
and AnIm ligand, making the Ir (II) species stable. But adding an elec-
tron to the anti-bonding LUMO of 2b will strongly weaken the Ir–
AnIm bond, leading to ligand decomposition.
Mulliken atomic charge distributions on Ir, Cp* and anilido-
imine ligand of complexes 1a, 1b, 2b and 3b are listed in Table 2.
Cp* shares more than half of the positive charge in all complexes.
This can be explained as efficient d–
p
overlap between Ir and Cp*
and
p
-back donation from Cp* to Ir. In contrast, due to the poor
bonding orbit between Ir and AnIm, the positive charge on iridium
does not efficiently shared by AnIm. Thus, we can infer that, in the

X. Meng et al. / Journal of Organometallic Chemistry 693 (2008) 2597–2602
2601
1377(w), 1329(s), 1253(w), 1209(w), 1171(m), 1116(w), 1034(m),
914(m), 860(w), 817(w), 799(m), 742(m), 645(w) cmꢀ1
4. Experimental
.
4.1. General procedures
4.3. Synthesis of Cp*IrCl[o-C6 H4N(C6H3-Me-p)(CH@NC6 H3-Me-p)]
(1a)
All manipulations of air- and/or water-sensitive compounds
were carried out under nitrogen using standard Schlenk tech-
niques. Solvents were dried by refluxing with appropriate drying
agents and distilled under nitrogen prior to use. All chemicals
which were commercially available were used without further
A solution of n-BuLi (1.6 M, 0.28 mL, 0.45 mmol) in hexane was
added dropwise to
a stirred solution of ligand L1 (0.123 g,
0.41 mmol) in THF (10 mL) at ꢀ78 °C. The mixture was slowly
warmed to room temperature and stirred for 3 h. The solvent
was removed under vacuum, and toluene (10 mL) was added to
the solid residue. The resultant mixture containing the lithium salt
of L1 was slowly channeled to a suspension of (Cp*IrCl2)2 (0.16 g,
0.2 mmol) in toluene (10 mL) and continuously stirred overnight
at room temperature. A dark red suspension was allowed to stand
for 1 day, and LiCl was removed by filtration. The solution was con-
centrated to about 3 mL, and cooled to ꢀ30 °C to obtain dark red
solid. Small red crystals were obtained through recrystallization
from hexane (0.19 g, 70%). Anal. Calc. for C31H34ClIrN2 (662.25):
C, 56.22; H, 5.17; N, 4.23. Found: C, 56.65; H, 4.91; N, 3.87%. 1H
NMR (400 MHz, CDCl3, 293 K): d 8.84 (s, 1 H, CH@NAr), 7.55 (d,
H, Ph–H), 7.42–7.39 (m, 8H, Ph–H), 7.15 (t, 1H, Ph–H), 7.08 (d,
1H, Ph–H), 6.60 (d, 1H, Ph–H), 2.52 (d, 6H, Ph–CH3), 1.18 (s, 15H,
Cp-5CH3) ppm. IR (KBr): 3052(w), 3011(w), 2914(s), 2860(s),
1612(s), 1591(s), 1503(s), 1496(m), 1436(m), 1372(w), 1338(m),
purification. The starting material [Cp*IrCl(
l-Cl)]2 was prepared
according to literature methods [6]. 1H NMR spectra were recorded
with a Varian Unity-400 spectrometer. Elemental analyses were
performed on an Elementarvario EL III Analyzer. Cyclic voltamme-
try (CV) was carried out on CH Instruments electrochemical work-
station (model 600A) at a scanning rate of 50 mV/s. Complex 1a
was dissolved in CH2Cl2 using 0.1 M N(nBu)4PF6 as the supporting
electrolyte [10]. UV spectra were recorded at room temperature
with an Agilgent instrument 8543.
4.2. Synthesis of o-C6H4NH (C6H3-Me-p)(CH@NC6H3-Me-p) (L1)
Ligands L1–L5 were prepared in good yields according to the lit-
erature without major modification, (2). Herein the synthesis of L1
will be taken as an example. A mixture of ortho-fluorobenzalde-
hyde (5.0 mL, 47.1 mmol), p-toluidine (5.0 g, 47.1 mmol), and
MgSO4 (1.0 g) in n-hexane (30 mL) was stirred for 2 h. The mixture
was filtered, and the yellow solid ortho-C6H4F(CHNC6H4Me-p) was
obtained after the solvent was removed, Pure product was ob-
tained by recrystallization from hexane. A solution of n-BuLi
(19.0 mL, 30.4 mmol) in hexanes was added to a solution of 2,6-
dimethylaniline (5.0 mL, 30 mmol) in THF (20 mL) at ꢀ78 °C. The
reaction mixture was warmed to room temperature and stirred
overnight. The resulting solution of LiNHAr was transferred into
a solution of ortho-C6H4F(CHNC6H4Me-p) (6.39 g, 30 mmol) in
THF (20 mL) at 25 °C. After stirring for 1 h, the reaction was
quenched with 10 mL H2O, the mixture was extracted with n-hex-
ane, and the organic phase was evaporated to vacuo to give a yel-
low solid crude product. Pure product was obtained as yellow
crystals by recrystallization from methanol. (5.4 g, 56%). Anal. Calc.
for C21H20N2 (300.4): C, 83.96; H, 6.71; N, 9.33. Found: C, 83.76; H,
6.91; N, 9.27%. 1H NMR (CDCl3): d 11.15 (s, 1H, NH), 8.59 (s, 1H,
CH@NAr), 7.40 (d, 1H, Ph–H), 7.28–7.12 (m, 10H, Ph–H), 6.77 (t,
1H, Ph–H), 2.37 (s, 3H, CH3), 2.35 (s, 3H, CH3). IR (KBr): 3200(w),
3072(w), 3011(w), 2914(s), 2878(s), 1617(s), 1594(s), 1566(s),
1518(s), 1452(s), 1325(m), 1181(m), 1155(m), 827(m), 750(m),
1165(m), 1104(m), 1026(m), 803(m), 742(m), 496(w) cmꢀ1
.
4.4. Synthesis of Cp*Ir[o-C6H4N(C6H3-Me-p)(CH@NC6 H3-Me-p)]
SO3CF3 (1b)
A solution of AgSO3CF3 (0.12 M, 1.6 mL, 0.2 mmol) in CH3CN
was added dropwise to a stirred solution of 1a (0.133 g, 0.2 mmol)
in toluene (10 mL) at room temperature. The mixture was stirred
for another 2 h, when the color gradually turned from dark red to
red. The solution was filtered to remove AgCl, and the solvent
was evaporated under vacuum to yield 2a (85%). Anal. Calc. for
C
32H34F3IrN2O3S (775.9): C, 49.53; H, 4.42; N, 3.61; S, 4.13. Found:
C, 50.01; H, 4.04; N, 3.84; S, 3.87%. 1H NMR (400 MHz, CDCl3,
293 K): d 9.00 (s, 1H, CH@NAr), 7.67 (d, 1H, Ph–H), 7.47–7.16 (m,
9H, Ph–H), 7.00 (d, 1H, Ph–H), 6.71 (d, 1H, Ph–H), 2.58 (d, 3H,
Ph–CH3), 2.52 (d, 3H, Ph–CH3), 1.18 (s, 15H, Cp-5CH3) ppm. IR
(KBr): 3026(w), 2918(s), 1610(s), 1575(s), 1536(s), 1504(m),
1454(m), 1270(s), 1222(m), 1148(s), 1030(s), 869(m), 762(m)
cmꢀ1
.
4.5. Synthesis of Cp*Ir[o-C6H4N(C6H3-Me-p)(CH@NC6H3-i-Me2-2, 6)]Cl
(2b)
517(m) cmꢀ1
.
The ligands L2–L5 were synthesized by the similar procedure
with L1, and all the 1H NMR resonances of these ligands were in
good accordance with the literatures.
Complex 2b was obtained in a similar strategy to that used in
the isolation of 1a (0.10 g, 75%). Anal. Calc. for C32H36ClIrN2
(676.28): C, 56.83; H, 5.37; N, 4.14. Found: C, 56.65; H, 4.99; N,
3.81%. 1H NMR (400 MHz, CDCl3, 293 K): d 8.82 (s, 1H, CH@NAr),
7.69 (d, H, Ph–H), 7.55 (d, 1H, Ph–H), 7.47–6.70 (m, 9H, Ph–H),
2.59 (d, 3H, Ph–CH3), 2.20 (d, 6H, Ph-2CH3), 1.16 (s, 15H, Cp-
5CH3) ppm. IR (KBr): 3388(m), 3072(s), 3061(s), 2960(m),
2865(w), 1600(s) 1505(s), 1499(s), 1447(m), 1404(m), 1326(s),
o-C6H4NH (C6H3-Me-p)(CH@NC6H3-Me2-2,6) (L2): Anal. Calc. for
C
22H22N2 (314.4): C, 84.04; H, 7.05; N, 8.91. Found: C, 83.95; H,
6.95; N, 8.90%. 1H NMR (CDCl3): d 11.07 (s, 1H, NH), 8.32 (s, 1H,
CH@NAr), 7.32–7.08 (m, 9H, Ph–H), 6.95 (m, 1H, Ph–H), 6.79 (m,
1H, Ph–H), 2.34 (s, 3H, PhCH3), 2.19 (m, 6H, Ph–CH3). IR (KBr):
3208(w), 3067(w), 3020(w), 2946(m), 2915(m), 2859(s), 2859(w),
1620(s), 1584(s), 1572(s), 1518(s), 1456(s), 1374(m), 1328(s),
1216(w), 1175(m), 1159(m), 1117(w), 1089(m), 1042(w), 910(m),
1179(m), 906(m), 768(m) cmꢀ1
.
859(w), 831(m), 801(w), 770(m), 754(m), 616(m) cmꢀ1
.
4.6. Synthesis of Cp*Ir[o-C6 H4N(C6H3-Me-p)(CH@NC6 H3-i-Pr2-2,6)]Cl
(3b)
o-C6H4NH (C6H3-Me-p)(CH@NC6H3-i-Pr2-2,6) (L3): Anal. Calc. for
C
26H30N2 (370.5): C, 84.28; H, 8.16; N, 7.56. Found: C, 84.20; H,
8.31; N, 7.35%. 1H NMR (CDCl3): d 11.05 (s, 1H, NH), 8.30 (s, 1H,
CH@NAr), 7.33 (t, 2H, Ph–H), 7.27 (m, 1H, Ph–H), 7.19–7.13 (m,
7H, Ph–H), 6.80 (t, 1H, Ph–H), 3.05(m, 2H, CH(CH3)2), 2.34(s, 3H,
PhCH3), 1.19–1.17 (m, 12H, CH(CH3)). IR (KBr): 3200(w), 3060(w),
2919(m), 2867(s), 1619(s), 1596(s), 1571(s), 1527(s), 1461(s),
Complex 3b was obtained in a similar strategy to that used in
the isolation of 1a (0.10 g, 75%). Anal. Calc. for C35H42ClIrN2
(732.28): C, 59.04; H, 6.06; N, 3.82. Found: C, 58.64; H, 6.44; N,
3.62%. 1H NMR (400 MHz, CDCl3, 293 K) d8.82 (s, 1H, CH@NAr),
7.82 (d, H, Ph–H), 7.42–7.10 (m, 9H, Ph–H), 6.62 (d, 1H, Ph–H),

2602
X. Meng et al. / Journal of Organometallic Chemistry 693 (2008) 2597–2602
(d) V.C. Gibson, J.A. Segal, J.P. White, D.J. Williams, J. Am. Chem. Soc. 122
(2000) 7120;
(e) N.J. Hardman, C. Cui, H.W. Roesky, W.H. Fink, P.P. Power, Angew. Chem.,
Int. Ed. 40 (2001) 2172;
(f) H. Andres, E. Bominaar, J.M. Smith, N.A. Eckert, P.L. Holland, E. Münck, J.
Am. Chem. Soc. 124 (2002) 3012;
(g) A. Panda, M. Stender, R.J. Wright, M.M. Olmstead, P. Klavins, P.P. Power,
Inorg. Chem. 41 (2002) 3909;
6.51 (d, 1H, Ph–H) 6.04 (d, 1H, Ph–H), 5.66 (t, 1H, Ph–H), 5.29 (s,
1H, Ph–H), 3.67 (p, 1H, CH(CH3)2), 3.56 (p, 1H, CH(CH3)2), 2.33 (s,
3H, Ph–CH3), 1.52 (s, 15H, Cp-5CH3), 1.32 (d, 1H, CH(CH3)2), 1.26
(d, 1H, CH(CH3)2), 1.14 (d, 1H, CH(CH3)2), 0.88 (d, 1H, CH(CH3)2)
ppm. IR (KBr): 3388(m), 3073(s), 2961(m), 2918(w), 2867(s),
1599(s) 1505(s), 1447(m), 1402(s), 1311(s), 1218(m), 1149(m),
1089(m), 1029(m), 938 m), 881(m) cmꢀ1
.
(h) N.A. Eckert, E.M. Bones, R.J. Lachicotte, P.L. Holland, Inorg. Chem. 42 (2003)
1720;
(i) A.P. Dove, V.C. Gibson, P. Hormnirun, E.L. Marshall, J.A. Segal, A.J.P. White,
D.J. Williams, Dalton Trans. (2003) 3088;
4.7. X-ray structure determinations of 1a and 2b
(j) N.A. Eckert, J.M. Smith, R.J. Lachicotte, P.L. Holland, Inorg. Chem. 43 (2004)
3306;
(k) E.A. Gregory, R.J. Lachicotte, P.L. Holland, Organometallics 24 (2005) 1803;
(l) J. Vela, J.M. Smith, Y. Yu, N.A. Ketterer, C.J. Flaschenriem, R.J. Lachicotte, P.L.
Holland, J. Am. Chem. Soc. 127 (2005) 7857;
Single crystals of 1a and 2b suitable for X-ray structural analysis
were obtained from n-hexane and toluene. The intensity data of
the single crystal were collected on the CCD-Bruker Smart APEX
system [12]. All determinations of the unit cell and intensity data
(m) M. Susan, Kloek, K.I. Goldberg, J. Am. Chem. Soc. 129 (2007) 3460;
(n) L. Bourget-Merle, M.F. Lappert, J.R. Severn, Chem. Rev. 102 (2002) 3031.
[4] (a) P.G. Hayes, G.C. Welch, D.J.H. Emslie, C.L. Noack, W.E. Piers, M. Parvez,
Organometallics 22 (2003) 1577;
were performed with graphite-monochromated Mo K
a radiation
(k = 0.71073 Å) at room temperature. These structures were solved
by direct methods, using Fourier techniques, and refined on F2 by
full matrix least-squares method. All the non-hydrogen atoms
were refined anisotropically, and all the hydrogen atoms were in-
cluded but not refined. Details of the data collection and refine-
ment are summarized in Table 1.
(b) H.Y. Gao, W.J. Guo, F. Bao, G.Q. Gui, J.K. Zhang, F.M. Zhu, Q. Wu,
Organometallics 23 (2004) 6273;
(c) A.M. Reynolds, B.F. Gherman, C.J. Cramer, W.B. Tolman, Inorg. Chem. 44
(2005) 6989;
(d) B.Y. Lee, H.Y. Kwon, S.Y. Lee, S.J. Na, S. Han, H. Yun, H. Lee, Y.W. Park, J. Am.
Chem. Soc. 127 (2005) 3031;
(e) X. M Liu, H. Xia, W. Gao, L. Ye, Y. Mu, Q. Su, Y. Ren, Eur. J. Inorg. Chem.
(2006) 1216;
(f) X.M. Liu, W. Gao, Y. Mu, G.H. Li, L. Ye, H. Xia, Y. Ren, S.H. Feng,
Organometallics 24 (2005) 1614;
4.8. Density functional theory (DFT) calculations
(g) Y.M. Badiei, A. Krishnaswamy, M.M. Melzer, T.H. Warren, J. Am. Chem. Soc.
12 (2006) 15056;
(h) E.C. Brown, I.B. Nahum, J.T. York, N.W. Aboelella, W.B. Tolman, Inorg.
Chem. 46 (2007) 486;
(i) Y. Ren, X.M. Liu, W. Gao, H. Xia, L. Ye, Y. Mu, Eur. J. Inorg. Chem. (2007)
1808.
The structure of 1a and 2b was optimized for the singlet state
using the DFT method with B3LYP functional in the gas phase in
the GAUSSIAN 03 packages. LANL2DZ basis set was used for Ir,
and 6-31G basis set was used for C, N, H and Cl atoms.
[5] (a) G. Bhalla, X.Y. Liu, J. Oxgaard, W.A. Goddard, R.A. Periana, J. Am. Chem. Soc.
127 (2005) 11372;
Supplementary material
(b) Y. Guari, S.S. Etienne, B. Chaudret, Eur. J. Inorg. Chem. (1999) 1047;
(c) F.C.C. Mouraa, E.N. Santosa, R.M. Lagoa, M.D. Vargasb, M.H. Araujoa, J. Mol.
Catal. A: Chem. 226 (2005) 243;
(d) L. Flores-Santos, E. Martin, A. Aghmiz, M. Dieguez, C. Claver, M. Masdeu-
Bulto, M.A. Munoz-Hernandez, Eur. J. Inorg. Chem. (2005) 2315;
(e) G. Bhalla, J. Oxgaard, W.A. Goddard, R.A. Periana, Organometallics 24
(2005) 5499;
(f) G. Bhalla, J. Oxgaard, W.A. Goddard, R.A. Periana, Organometallics 24 (2005)
3229;
(g) V.R. Landaeta, B.K. Munoz, M. Peruzzini, V. Herrera, C. Bianchini, R.A.
Sanchez-Delgado, Organometallics 25 (2006) 403;
CCDC 674229 and 674230 contain the supplementary crystallo-
graphic data for compounds 1a and 2b. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
(h) B.A. Messerle, K.Q. Vuong, Organometallics 26 (2007) 3031;
(i) K.D. Hesp, D. Wechsler, J. Cipot, A. Myers, R. McDonald, M.J. Ferguson, G.
Schatte, M. Stradiotto, Organometallics 26 (2007) 5430;
(j) E. Peris, R.H. Crabtree, Coord. Chem. Rev. 248 (2004) 2239;
(k) D.J. Weix, J.F. Hartwig, J. Am. Chem. Soc. 129 (2007) 7720.
[6] H.Y. Wang, X. Meng, G.-X. Jin, Dalton Trans. (2006) 2579.
[7] D. Carmona, M.P. Lamata, F. Viguri, R. Rodriguez, F.J. Lahoz, I.T. Dobrinovitch,
L.A. Oro, Dalton Trans. (2007) 1911.
Financial support by the National Science Foundation of China
(20531020, 20721063, 20771028), by Shanghai Leading Academic
Discipline project (B108) and by Shanghai Science and Technology
Committee (06XD14002) is gratefully acknowledged.
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