Oxidative addition of RCO2H and HX to chiral diphosphine complexes of iridium(I): Convenient synthesis of mononuclear halo-carboxylate iridium(III) complexes and cationic dinuclear triply halogen-bridged iridium(III) complexes and their catalytic performance in asymmetric hydrogenation of cyclic imines and 2-phenylquinoline

Article abstract of DOI:10.1021/om051065j

Mononuclear iridium(III) complexes of general formula IrX(H)(O ₂CR)[(S)-binap] (2, R = CH3; 3, R = Ph; 4, R = C₆H ₄CH₃-p; a, X = Cl; b, X = Br; c, X = I) were prepared by one-pot reaction of [Ir(μ-X)(cod)]₂ with 2 equiv of (S)-BINAP [=2,2′-bis(diphenylphosphino)-1,1′-binaphthyl] and an excess of the corresponding carboxylic acid in toluene. The structure of (S)-2-4 bearing an (5)-BINAP was confirmed to be OC-6-23-A (A-conformation) by X-ray analysis of (S)-4a-c. In this reaction, the iridium-(I) complex {Ir(μ-Cl)[(S)-binap]} ₂ [(S)-5a] and pentacoordinated iridium(I) complexes IrX(cod)[(S)-binap] [(S)-7b, X = Br; (S)-7c, X = I] were generated prior to the oxidative addition of carboxylic acid. Cationic dinuclear iridium(III) complexes of general formula [{Ir(H)[(S)-binap]}₂(μ-X)₃]X [(S)-8: a, X = Cl; b, X = Br; c, X = I] were prepared, and their cationic bifacial octahedral dinuclear structure was characterized by spectral data and combustion analysis. The anionic portion of these complexes could be replaced by NaPF₆, leading to the corresponding PF₆ salts [{Ir(H)[(S)-binap]}₂(μ-X)₃]PF₆ [(S)-8: d, X = Cl; e, X = Br; f, X = I]. Iodo-acetate complexes of p-TolBINAP (=2,2′-bis(di-4-tolylphosphino)-1,1′r-binaphthyl) [(S)-9c] and SYNPHOS [=2,2′,3,3′-tetrahydro(5,5′-bi-1,4-benzodioxin)-6, 6′-diyl]bis(diphenylphosphine)] [(S)-10c] were also prepared according to the method used for the BINAP complex (S)-2c and were characterized spectroscopically. Cationic dinuclear complexes of p-TolBINAP [(S)-11c] and SYNPHOS [(S)-12c] were also generated. Using these complexes, the effect of halide variation was studied by asymmetric hydrogenation of 2-phenylpyrrolidine (13) and 2-phenyl-4,5,6,7-tetrahydro-3H-azepine (15) along with 2-phenylquinoline (16), and the results indicated that iodide complexes were better catalyst precursors for catalytic activity than the corresponding chloride and bromide complexes, but were not superior in enantioselectivity.

Full text of DOI:10.1021/om051065j

Organometallics 2006, 25, 2505-2513
2505
Oxidative Addition of RCO2H and HX to Chiral Diphosphine
Complexes of Iridium(I): Convenient Synthesis of Mononuclear
Halo-Carboxylate Iridium(III) Complexes and Cationic Dinuclear
Triply Halogen-Bridged Iridium(III) Complexes and Their Catalytic
Performance in Asymmetric Hydrogenation of Cyclic Imines and
2-Phenylquinoline
Tsuneaki Yamagata,† Hiroshi Tadaoka,† Mitsuhiro Nagata,† Tsukasa Hirao,†
Yasutaka Kataoka,† Virginie Ratovelomanana-Vidal,‡ Jean Pierre Genet,*,‡ and
Kazushi Mashima*,†
Department of Chemistry, Graduate School of Engineering Science, Osaka UniVersity, Toyonaka,
Osaka 560-8531, Japan, and Laboratoire de Synthe`se Se´lectiVe Organique et Produits Naturels,
Ecole Nationale Supe´rieure de Chimie de Paris, 11 Rue P. et M. Curie, 75231 Paris Cedex 05, France
ReceiVed December 14, 2005
Mononuclear iridium(III) complexes of general formula IrX(H)(O2CR)[(S)-binap] (2, R ) CH3; 3,
R ) Ph; 4, R ) C6H4CH3-p; a, X ) Cl; b, X ) Br; c, X ) I) were prepared by one-pot reaction of
[Ir(µ-X)(cod)]2 with 2 equiv of (S)-BINAP [)2,2′-bis(diphenylphosphino)-1,1′-binaphthyl] and an excess
of the corresponding carboxylic acid in toluene. The structure of (S)-2-4 bearing an (S)-BINAP was
confirmed to be OC-6-23-A (Λ-conformation) by X-ray analysis of (S)-4a-c. In this reaction, the iridium-
(I) complex {Ir(µ-Cl)[(S)-binap]}2 [(S)-5a] and pentacoordinated iridium(I) complexes IrX(cod)[(S)-binap]
[(S)-7b, X ) Br; (S)-7c, X ) I] were generated prior to the oxidative addition of carboxylic acid. Cationic
dinuclear iridium(III) complexes of general formula [{Ir(H)[(S)-binap]}2(µ-X)3]X [(S)-8: a, X ) Cl; b,
X ) Br; c, X ) I] were prepared, and their cationic bifacial octahedral dinuclear structure was characterized
by spectral data and combustion analysis. The anionic portion of these complexes could be replaced by
NaPF6, leading to the corresponding PF6 salts [{Ir(H)[(S)-binap]}2(µ-X)3]PF6 [(S)-8: d, X ) Cl; e, X )
Br; f, X ) I]. Iodo-acetate complexes of p-TolBINAP ()2,2′-bis(di-4-tolylphosphino)-1,1′-binaphthyl)
[(S)-9c] and SYNPHOS [)2,2′,3,3′-tetrahydro(5,5′-bi-1,4-benzodioxin)-6,6′-diyl]bis(diphenylphosphine)]
[(S)-10c] were also prepared according to the method used for the BINAP complex (S)-2c and were
characterized spectroscopically. Cationic dinuclear complexes of p-TolBINAP [(S)-11c] and SYNPHOS
[(S)-12c] were also generated. Using these complexes, the effect of halide variation was studied by
asymmetric hydrogenation of 2-phenylpyrrolidine (13) and 2-phenyl-4,5,6,7-tetrahydro-3H-azepine (15)
along with 2-phenylquinoline (16), and the results indicated that iodide complexes were better catalyst
precursors for catalytic activity than the corresponding chloride and bromide complexes, but were not
superior in enantioselectivity.
interest because they serve as highly active catalysts for
asymmetric hydrogenation of the CdN bond of imines to form
chiral amines. The most remarkable feature of the iridium-
diphosphine catalyst system is that the addition of an iodide
anion source or iodine to the catalyst systems significantly
enhances their catalytic activity and, in some cases, enantiose-
lectivity. A halide effect2 has been reported for asymmetric
reactions assisted by halide complexes of ruthenium,3-5 rho-
dium,6 and iridium7-17 bearing various chiral diphosphine
Introduction
Practical and efficient catalysts for asymmetric hydrogenation
of unsaturated organic compounds have been extensively
developed by making the coordination environment around the
transition metal center chiral, not only through the design and
synthesis of chiral ligands but also via rational combination with
auxiliary ligands on the transition metal center.1 Iridium
complexes with chiral diphosphine ligands have attracted much
* To whom correspondence should be addressed. E-mail: mashima@
chem.es.osaka-u.ac.jp. Fax: 81-6-6850-6245.
(2) Fagnou, K.; Lautens, M. Angew. Chem., Int. Ed. 2002, 41, 26.
(3) (a) Noyori, R.; Ohkuma, T.; Kitamura, M.; Takaya, H.; Sayo, N.;
Kumobayashi, H.; Akutagawa, S. J. Am. Chem. Soc. 1987, 109, 5856. (b)
Kitamura, M.; Ohkuma, T.; Inoue, S.; Sayo, N.; Kumobayashi, H.;
Akutagawa, S.; Ohta, T.; Takaya, H.; Noyori, R. J. Am. Chem. Soc. 1988,
110, 629. (c) Noyori, R.; Ikeda, T.; Ohkuma, T.; Widhalm, M.; Kitamura,
M.; Takaya, H.; Akutagawa, S.; Sayo, N.; Saito, T.; Taketomi, T.;
Kumobayashi, H. J. Am. Chem. Soc. 1989, 111, 9134. (d) Mashima, K.;
Kusano, K.; Sato, N.; Matsumura, Y.; Nozaki, K.; Kumobayashi, H.; Sayo,
N.; Hori, Y.; Ishizaki, K.; Akutagawa, S.; Takaya, H. J. Org. Chem. 1994,
59, 3064.
† Osaka University.
‡ Ecole Nationale Supe´rieure de Chimie de Paris.
(1) For comprehensive reviews on asymmetric catalysis: Noyori, R.
Asymmetric Catalysis in Organic Synthesis; Wiley: New York, 1994.
Jacobsen, E. N., Pfaltz, A., Yamamoto, H., Eds. ComprehensiVe Asymmetric
Catalysis; Springer, Berlin, 1999. Ojima, I., Ed. Catalytic Asymmetric
Synthesis, 2nd ed.; Wiley-VCH: New York, 2000. Noyori, R.; Ohkuma,
T. Angew. Chem., Int. Ed. 2001, 40, 40. Noyori, R. Angew. Chem., Int. Ed.
2002, 41, 2008. Genet, J. P. Pure Appl. Chem. 2002, 74, 77.
10.1021/om051065j CCC: $33.50 © 2006 American Chemical Society
Publication on Web 04/04/2006

2506 Organometallics, Vol. 25, No. 10, 2006
Yamagata et al.
ligands. We are interested in catalyst systems based on iridium-
(III) complexes because of their higher tolerance to air oxidation
compared with iridium(I) complexes. Although iridium(III)
species are considered key intermediates, there are only a few
iridium(III) catalyst precursors. Osborn and co-workers reported
that (1) neutral double iodine-bridged dinuclear hydride com-
plexes of iridium(III), [IrHI2(diphosphine)]2 [diphosphine: BI-
NAP ) 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl, DIOP,
NORPHOS, etc.], could be prepared by treating cationic
mononuclear iridium(I) complexes [Ir(diphosphine)(cod)]BF4
with excess amounts of LiI7a and (2) that a metathesis reaction
of [IrHI2(diphosphine)]2 with 1 equiv of AgOAc leads to Ir(I)-
(H)(O2CCH3)(diphosphine).7b Another iridium(III) system is the
iridium(III)-xyliphos-carboxylate complex {(S)-xyliphos ) (S)-
1-[(R)-2-(diphenylphosphanyl)ferrocenyl]ethyldi(3,5-xylyl)phos-
phane}, which was generated in situ by treating a cationic
iridium(I) complex bearing a xyliphos ligand with tetrabutyl-
ammonium iodide and acetic acid. This complex showed
catalytic activity for asymmetric hydrogenation of imines with
an extremely high turnover frequency and moderate enantiose-
lectivity.11 Additionally, several iridium(III) complexes bearing
xyliphos were recently reported.17 Here, we report the synthesis
of mononuclear halide-carboxylate and cationic triply halogen-
bridged dinuclear iridium(III) complexes of BINAP and its
derivatives and discuss their catalytic performance in the
asymmetric hydrogenation of cyclic imines and 2-phenylquino-
line.16
Figure 1. Crystal structure of 2c with numbering scheme.
Hydrogen atoms are omitted for clarity.
(H)(O2CCH3)[(R)-binap] [(R)-2c].7b The (S)-2-4 complexes
were characterized by spectral data together with X-ray analyses
of 4-methylbenzoate complexes (S)-4a-c. The IR spectra of
these complexes demonstrated a typical absorption band as-
signable to νIr-H in the range 2264-2280 cm-1. The 1H NMR
spectra of both isomers of (S)-2 together with (S)-3 and (S)-4
displayed a hydride signal around δ -25, whose coupling
pattern (doublet of doublets) and two coupling constants of JP-H
placed the hydride atom at a position cis to both phosphorus
atoms. The 31P{1H} NMR spectra of both isomers of (S)-2
together with (S)-3 and (S)-4 showed two doublets with an AB
pattern due to the two magnetically nonequivalent phosphorus
atoms of the BINAP ligand. These spectral data clearly indicated
that both BINAP and carboxylate acted as bidentate ligands,
suggesting that these complexes should have a ∆ or Λ geometry;
however, the trans-geometry was ruled out because of the
observation of two isomers for (S)-2. Structures of the major
isomer of (S)-2 together with (S)-3 and (S)-4 bearing (S)-BINAP
were determined to be OC-6-23-A (Λ-conformation) by X-ray
analyses for (S)-4a-c. Thus, the minor isomer of (S)-2 was
assigned the ∆-conformation.
Results and Discussion
Synthesis and Characterization of Mononuclear Halide-
Carboxylate BINAP-Iridium(III) Complexes. A simple one-
pot reaction of [Ir(µ-Cl)(cod)]2 (1a) with 2 equiv of (S)-BINAP
and 10 equiv of acetic acid in toluene afforded in modest yield
a mononuclear iridium(III) complex, IrCl(H)(O2CCH3)[(S)-
binap] [(S)-2a], as a mixture of major (>95%) and minor (<5%)
isomers (eq 1). Bromide [(S)-2b] and iodide [(S)-2c] derivatives
of (S)-2a were prepared by the same one-pot reactions, giving
a mixture of two isomers (eq 1). Benzoate [(S)-3a-c] and
4-methylbenzoate [(S)-4a-c] iridium(III) complexes of (S)-
BINAP were similarly prepared as only one isomer. This
synthetic method is much easier than the reported metathesis
reaction of [IrHI2((R)-binap)]2 with AgOAc, leading to Ir(I)-
(4) (a) Ikariya, T.; Ishii, Y.; Kawano, H.; Arai, T.; Saburi, M.; Yoshikawa,
S.; Akutagawa, S. J. Chem. Soc., Chem. Commun. 1985, 922. (b) Kawano,
H.; Ikariya, T.; Ishii, Y.; Saburi, M.; Yoshikawa, S.; Uchida, Y.; Kumoba-
yashi, H. J. Chem. Soc., Perkin Trans. 1 1989, 1571.
(5) Genet, J.-P. Acc. Chem. Res. 2003, 36, 908.
(6) Lautens, M.; Fagnou, K. J. Am. Chem. Soc. 2001, 123, 7170.
(7) (a) Chan, Y. N. C.; Osborn, J. A. J. Am. Chem. Soc. 1990, 112, 9400.
(b) Sablong, R.; Osborn, A. J. Tetrahedron: Asymmetry 1996, 7, 3059.
(8) Spindler, F.; Pugin, B.; Blaser, H.-U. Angew. Chem., Int. Ed. Engl.
1990, 29, 558.
(9) Spindler, F.; Pugin, B.; Jalett, H.-P.; Buser, H.-P.; Pittelkow, U.;
Blaser, H.-U. Chem. Ind. (Dekker) 1996, 68, 153.
(10) Blaser, H.-U.; Buser, H.-P.; Haeusel, R.; Jalett, H.-P.; Spindler, F.
J. Organomet. Chem. 2001, 621, 34.
(11) Pugin, B.; Landert, H.; Spindler, F.; Blaser, H.-U. AdV. Synth. Catal.
2002, 344, 974.
(12) Dorta, R.; Egli, P.; Zuercher, F.; Togni, A. J. Am. Chem. Soc. 1997,
119, 10857.
(13) Morimoto, T.; Nakajima, N.; Achiwa, K. Chem. Pharm. Bull. 1994,
42, 1951.
(14) Satoh, K.; Inenaga, M.; Kanai, K. Tetrahedron: Asymmetry 1998,
9, 2657.
(15) Xiao, D.; Zhang, X. Angew. Chem., Int. Ed. 2001, 40, 3425.
(16) Wang, W.-B.; Lu, S.-M.; Yang, P.-Y.; Han, X.-W.; Zhou, Y.-G. J.
Am. Chem. Soc. 2003, 125, 10536.
(17) Dorta, R.; Broggini, D.; Stoop, R.; Ruegger, H.; Spindler, F.; Togni,
A. Chem. Eur. J. 2004, 10, 267.
Figure 1 shows the crystal structure of (S)-4c. The (S)-4a
and (S)-4b complexes are isomorphic and are depicted in the
Supporting Information. The selected bond distances and angles
for (S)-4a-c are summarized in Table 1. The iridium(III) center
adopts a distorted octahedral geometry, where BINAP and
4-methylbenzoate are bidentate ligands, and a hydride atom is
placed at a position cis to the two phosphorus atoms. For (S)-
4c, the distance of Ir-P(1) [2.2505(9) Å] is slightly larger than
that of Ir-P(2) [2.2353(9) Å], while the distance of Ir-O(1)
[2.273(2) Å] is significantly larger than that of Ir-O(2) [2.191-
(2) Å] because the oxygen atom O(1) is trans to the hydride
atom. The distances of Ir-O(1) and Ir-O(2) in the iodide
complex (S)-4c are much larger than those in the chloride and
bromide complexes, whereas there is no clear difference between
the Ir-P distances. Although the bond distance of Ir-X
increased in the order of the covalent radii of the halogen atoms,

Mononuclear Halo-Carboxylate Iridium(III) Complexes
Organometallics, Vol. 25, No. 10, 2006 2507
Table 1. Selected Bond Lengths (Å) and Angles (deg) of 4a,
4b, and 4c
4a (X ) Cl)
4b (X ) Br)
4c (X ) I)
Ir-P1
Ir-P2
Ir-O1
Ir-O2
Ir-X
2.2483(6)
2.2333(6)
2.2564(16)
2.1736(16)
2.3990(5)
1.62(3)
2.2517(9)
2.2355(10)
2.2581(17)
2.1791(17)
2.5321(8)
1.605
2.2504(9)
2.2358(9)
2.2736(18)
2.1912(18)
2.7041(7)
1.668
Ir-H0
O2-Ir-P2
O2-Ir-P1
P2-Ir-P1
O2-Ir-O1
P2-Ir-O1
P1-Ir-O1
O2-Ir-X
P2-Ir-X
P1-Ir-X
O1-Ir-X
O1-Ir-H0
λa
167.71(4)
90.53(4)
93.26(2)
59.48(6)
108.26(4)
101.40(5)
84.56(4)
94.31(2)
165.87(2)
87.52(5)
163.6(12)
69.88(5)
167.60(4)
90.06(5)
93.24(3)
59.40(6)
108.20(5)
101.82(5)
84.73(5)
94.93(3)
164.60(2)
87.99(5)
152.47(4)
70.19(5)
167.25(4)
90.03(5)
92.51(3)
58.77(6)
108.48(5)
100.66(5)
86.71(5)
94.29(3)
163.26(2)
91.66(5)
161.74(4)
70.73(6)
Figure 2. Crystal structure of 7c with numbering scheme.
Hydrogen atoms are omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg)
for (S)-7ca
a λ is the dihedral angle between the least-squares planes through the
two naphthyl rings.
Ir-C49
Ir-C50
Ir-C46
Ir-C45
Ir-P2
Ir-P1
Ir-I
2.183(4)
2.194(3)
2.231(3)
2.245(3)
2.3248(8)
2.3297(8)
2.8905(3)
the structural features of these three complexes are almost the
same. The bis(pivalate)ruthenium complex with (S)-BINAP
complexes also forms the same Λ-configuration.18 The dihedral
angle of the two naphthyl planes of (S)-4 is in the range 69.88-
(5)-70.72(6)°, a higher range than that for Ru(OCOCMe3)2-
[(R)-binap] (65.47°)18 and Ir(I)(cod)[(S)-binap] [66.84(6)°] (vide
infra), but smaller than that for {Ir(µ-Cl)[(S)-binap]}2 [(S)-5a]
(74.06° and 76.83°)19 and [Ir2(µ-Cl)(OMe)2[(S)-binap]2]+Cl-
[81.4(1)°].20
P2-Ir-P1
P2-Ir-I
87.12(3)
93.26(2)
108.53(2)
100.84
103.14
88.87
148.29
165.89
92.49
P1-Ir-I
I-Ir-Cen1
I-Ir-Cen2
P1-Ir-Cen1
P1-Ir-Cen2
P2-Ir-Cen1
P2-Ir-Cen2
Cen1-Ir-Cen2
λb
The reaction outlined in eq 1 involved the formation of Ir-
(I)-BINAP complexes prior to the oxidative addition of acetic
acid. Iridium(I) complex {Ir(µ-Cl)[(S)-binap]}2 [(S)-5a], which
was readily obtained from the reaction of 1a or [Ir(µ-Cl)-
(cyclooctene)2]2 (6a) with 2 equiv of (S)-BINAP,19 reacted with
excess acetic acid in toluene to give (S)-2a quantitatively. In
contrast, reactions of 1b and 1c with (S)-BINAP in toluene at
room temperature led to the formation of the pentacoordinated
Ir(I) complexes IrX(cod)[(S)-binap] [(S)-7b, X ) Br; (S)-6c,
X ) I] (eq 2), to which acetic acid was oxidatively added to
give (S)-2b and (S)-2c, respectively. The stereochemistry of (S)-
2-4 was thus determined by the oxidative addition of acid to
83.86
66.84(6)
a Cen1: centroid of C45 and C46, Cen2: centroid of C49 and C50. b λ
is the dihedral angle between the least-squares planes through the two
naphthyl rings.
single-crystal X-ray analysis of the complex (S)-7c. The structure
of (S)-7c is shown in Figure 2, and selected bond distances and
angles are summarized in Table 2. The structural features are
the same as those of the pentacoordinated iridium(I) complex
Ir(I)(cod)[(S)-xyliphos].17 The iodide atom occupies the apical
position of the square pyramid, and the iridium atom is thus
deformed by 0.4335 Å out of the best plane defined by the two
phosphines of BINAP and the centroid of the CdC bonds of
the COD ligand. Such deformation was greater than that formed
for Ir(cod)(I)[(S)-xyliphos] [+0.3536 Å],17 Ir(Cl)(cod)[bis(µ2-
diphenylphosphino)iron] [0.3542 Å],21 and Ir(cod)(I)[1,3-bis-
(diphenylphosphino)propane] [0.3113 Å].22 The Ir-I distance
of (S)-7c [2.8905(3) Å] is significantly larger than that of the
iridium(III) complex (S)-2c [2.7041(7) Å], but was comparable
to that of the pentacoordinated idirium(I) complex Ir(cod)(I)-
[(S)-xyliphos], which was 2.888(4) Å.17
1
the idirium(I) complexes. The H NMR spectra of (S)-7b and
(S)-7c displayed signals due to protons of the coordinated COD
and those of BINAP in an exact 1:1 integral ratio, and there
was no hydride signal. The 31P{1H} NMR spectra of (S)-7b
and (S)-7c showed ABq (JP-P ) 38 Hz) due to the two
dissymmetric phosphorus atoms of the BINAP ligand.
Synthesis and Characterization of Cationic Dinuclear
Triply Halogen-Bridged Iridium(III)-BINAP Complexes.
The cationic dinuclear complex [{Ir(H)[(S)-binap]}2(µ-Cl)3]Cl
[(S)-8a] was prepared by adding excess aqueous HCl to a
mixture of 6a and 2 equiv of (S)-BINAP in toluene at room
temperature (eq 3). The cationic bifacial octahedral dinuclear
Although two structures, i.e., trigonal bipyramidal and square
pyramidal, are possible for the pentacoordinated iridium(I)
compounds, the spectral data suggested that (S)-7b and (S)-7c
adopted a square pyramidal structure, which was revealed by
(18) Ohta, T.; Takaya, H.; Noyori, R. Inorg. Chem. 1988, 27, 566.
(19) Yamagata, T.; Iseki, A.; Tani, K. Chem. Lett. 1997, 12, 1215.
(20) Tani, K.; Iseki, A.; Yamagata, T. Angew. Chem., Int. Ed. 1998, 37,
3381.
(21) Rosenberg, S.; Mahoney, W. S.; Hayes, J. M.; Geoffroy, G. L.;
Rheingold, A. L. Organometallics 1986, 5, 1065.
(22) Shibata, T.; Yamashita, K.; Ishida, H.; Takagi, K. Org. Lett. 2001,
3, 1217.

2508 Organometallics, Vol. 25, No. 10, 2006
Yamagata et al.
structure was determined by spectral data and combustion
analysis. The H NMR spectrum of (S)-8a showed a hydride
phino)-1,1′-binaphthyl][(S)-9c]andSYNPHOS[)2,2′,3,3′-tetra-
hydro(5,5′-bi-1,4-benzodioxin)-6,6′-diyl]bis(diphenylphosphine)]25
[(S)-10c] were prepared according to the method used for
synthesis of the BINAP complex (S)-2c and were characterized
spectroscopically. Cationic complex (S)-11c was prepared by
adding aqueous HI to a solution of the chloride complex (S)-
9a in toluene, which was prepared by the procedure described
for (S)-9c. Cationic complex (S)-12c was prepared by adding
aqueous HI to (S)-10c. Though these cationic dinuclear com-
plexes (S)-11c and (S)-12c contain some impurities, we used
them as catalyst precursors for asymmetric hydrogenation of
imines without purification and, in some cases, an situ mixture
of the acetate complex and an excess of aqueous HI.
1
signal at δ -22.70 with two coupling constants, JP-H of 15
and 21 Hz, indicating that the hydride was located at a position
cis to the two phosphines of BINAP. The stretching frequency
of Ir-H appeared at 2269 cm-1. The 31P{1H} NMR spectrum
of (S)-8a displayed a typical AA′BB′pattern. It is well estab-
lished that iridium(III) fragments “IrIII(X)(chiral diphosphine)”23as
well as isoelectronic ruthenium(II) fragments “RuII(X)(chiral
diphosphine)”24 form stable triply anionic ligand-bridged bifacial
octahedral dinuclear complexes, in which the AA′BB′ pattern
due to two chiral diphosphine ligands is observed by 31P{1H}
NMR spectroscopy. FAB-MS afforded a parent peak (M+
)
1738) due to the cationic fragment {Ir2H2Cl3[(S)-binap]2}+, in
accordance with the cationic dimeric structure of (S)-8a, which
was further confirmed by solution conductivity.
Similar treatment of a mixture of 6a and 2 equiv of
(S)-BINAP in toluene with excess aqueous HBr or aqueous HI
afforded the corresponding bromide and iodide complexes (S)-
8b and (S)-8c, whose structures were also revealed by spectral
data and combustion analysis together with EDAX measure-
ment, which confirmed the complete replacement of all the
chloride ions by bromide or iodide ions. The simple addition
of excess amounts of aqueous HBr or aqueous HI resulted in
the complete replacement of chloride during the oxidative
reaction, because the synthesis of 1b and 1c somewhat reduced
the chemical yield due to mechanical loss during the metathesis
reaction of chloride ions of 1a using NaX salts.7b The anions
of these complexes could be replaced using NaPF6, leading to
the corresponding PF6 salts (S)-8d-f. Complex (S)-8c was
additionally obtained by adding aqueous HI to the carboxylate
complex (S)-2a in toluene (eq 4) or by treatment of (S)-8a with
excess NaI in dichloromethane (eq 5). The spectral data of (S)-
8b were quite similar to those for (S)-8a, while (S)-8c gave
spectral data similar to those for (S)-8a, along with signals due
to small amounts of unidentified compounds. Osborn and Chan
reported a neutral dinuclear complex, {IrHI2[(R)-binap]}2, which
has the same chemical formula as the cationic dinuclear complex
(S)-8c.7a
Effect of Halide Ligand Bound to Iridium(III)-BINAP
Complexes for Asymmetric Hydrogenation of Cyclic Imines.
The effect of halide variation in catalytic performance was
studied by asymmetric hydrogenation of 2-phenylpyrrolidine
(13) and 2-phenyl-4,5,6,7-tetrahydro-3H-azepine (15), using
acetate BINAP complexes (S)-2a-c. As expected on the basis
of the reported tendency of halide effects for iridium catalyst
systems,7-18 the iodide complex (S)-2c was a better catalyst
precursor in terms of catalytic activity among the tested catalysts
(S)-2a-c (Table 3, entries 1-3 and 12-14), though halogen
atoms bound to the iridium(III) center did not clearly affect
enantioselectivity. Asymmetric hydrogenation of 2-phenylpi-
peridine (14) was catalyzed by iodide complexes (S)-2c, (S)-
3c, and (S)-4c with different carboxylate ligands (entries 8-10)
with the same activity and enantioselectivity, indicating that the
(S)-2a + ex. aq. HI toulene, rt8 (S)-8c
(4)
(5)
(S)-8a + ex. aq. NaI CH Cl , rt8 (S)-8c
2
2
Synthesis and Characterization of Iodide Iridium(III)
Complexes Bearing p-TolBINAP and SYNPHOS. Iodo-
acetate complexes of p-TolBINAP [)2,2′-bis(di-4-tolylphos-
(25) For SYNPHOS see: (a) Duprat de Paule, S.; Champion, N.;
Ratovelomanana-Vidal, V.; Genet, J.-P.; Dellis, P French patent 0112499;
PCT FR02/03146, W003029259. (b) Duprat de Paule, S.; Jeulin, S.;
Ratovelomanana-Vidal, V.; Genet, J.-P.; Champion, N.; Dellis, P. Tetra-
hedron Lett. 2003, 44, 823. (c) Duprat de Paule, S.; Jeulin, S.; Ratovelo-
manana-Vidal, V.; Genet, J.-P.; Champion, N.; Dellis, P. Eur. J. Org. Chem.
2003, 1931. (d) Duprat de Paule, S.; Jeulin, S.; Ratovelomanana-Vidal, V.;
Genet, J.-P.; Champion, N.; Deschaux, G.; Dellis, P. Org. Process. Res.
DeV. 2003, 7, 399.
(23) (a) Tani, K.; Iseki, A.; Yamagata, T. Angew. Chem., Int. Ed. 1998,
37, 3381. (b) Dorta, R.; Togni, A. Organometallics 1998, 17, 3423.
(24) Mashima, K.; Nakamura, T.; Matsuo, Y.; Tani, K. J. Organomet.
Chem. 2000, 607, 51. Ohta, T.; Tonomura, Y.; Nozaki, K.; Takaya, H.;
Mashima, K. Organometallics 1996, 15, 1521.

Mononuclear Halo-Carboxylate Iridium(III) Complexes
Organometallics, Vol. 25, No. 10, 2006 2509
Table 3. Asymmetric Hydrogenation of 2-Phenylpyrrolidine
(13), 2-Phenylpiperidine (14), and
Table 4. Asymmetric Hydrogenation of 2-Phenylquinoline
(16) Catalyzed by Iodo-Dinuclear Iridium(III) Complexesa
2-Phenyl-4,5,6,7-tetrahydro-3H-azepine (15) Catalyzed by
entry
cat.
S/C
temp (°C)
time (h)
yield (%)
% eeb,c
Iridium(III)-BINAP Complexesa
1
2
3
4
5
6
(S)-2c
(S)-8c
(S)-9c
(S)-10c
(S)-11c
(S)-12c
100
100
100
200
100
100
30
30
30
30
30
30
24
24
24
45
24
24
>99
>99
>99
42
>99
46
50 (S)
31 (S)
52 (S)
64 (S)
49 (S)
60 (S)
entry
substrate
cat.
S/Cb
time (h)
yield (%)
% eec,d
1
2
3
4
5
6
7
8
13
13
13
13
13
13
14
14
14
14
14
15
15
15
(S)-2a
(S)-2b
(S)-2c
(S)-8a
(S)-8b
(S)-8c
(S)-2c
(S)-2c
(S)-3c
(S)-4c
(S)-8c
(S)-2a
(S)-2b
(S)-2c
100
100
100
200
210
18
18
18
18
18
19
1
40
41
41
3
21
38
47
15
24
82
99
99
99
99
99
99
96
99
85 (S)
89 (S)
86 (S)
82 (S)
82 (S)
83 (S)
90 (S)
91 (S)
91 (S)
91 (S)
91 (S)
69 (S)
60 (S)
67 (S)
a Hydrogenation was carried out in THF solution charged into an
autoclave under an initial hydrogen pressure of 50 atm unless otherwise
noted. b Enantiomeric excess (ee) of the product was determined by HPLC
analysis with a Chiralcel AS-H column. c The absolute configuration is given
in parentheses.
220
100
1000
1000
1000
1000
100
9
10
11
12
13
14
NAP complexes (S)-9c and (S)-11c and SYNPHOS complexes
(S)-10c and (S)-12c was performed (Table 4, entries 3-6). The
results consistently revealed that cationic halogen-bridged
dinuclear complexes (S)-10c and (S)-12c had better enantiose-
lectivity than the corresponding carboxylate complexes and
BINAP catalysts, though the catalytic activity of (S)-10c and
(S)-12c was lower. Asymmetric hydrogenation of 16 using the
[IrCl(cod)]2/(R)-MeO-biphep/I2 system afforded an enantiose-
lectivity of 72%,16 a better value than that obtained using our
system based on BINAP and its derivatives.
18
18
18
100
100
a Hydrogenation was carried out in toluene solution charged into an
autoclave under an initial hydrogen pressure of 60 atm at 20 °C. b Ratio of
substrate and catalyst. c Enantiomeric excess (ee) of the product. d The
absolute configuration is given in parentheses.
catalytically active species did not involve the carboxylate ligand
during hydrogenation.
The bis(carboxylate)ruthenium(II) complexes of BINAP are
reportedly less active than the corresponding halide complexes
for asymmetric hydrogenation of ketonic substrates.3 Thus, we
conducted an asymmetric hydrogenation of 13 using (S)-8a-c,
which did not contain a carboxylate ligand. Among the tested
complexes, (S)-8a-c (entries 4-6), the iodide complex (S)-8c
was the most active catalyst for asymmetric hydrogenation of
13 despite the fact that (S)-8c exhibited less enantioselectivity
than the carboxylate complexes (S)-2a-c. In addition, (S)-8c
catalyzed the asymmetric hydrogenation of 14 much faster than
complexes (S)-2c, (S)-3c, and (S)-4c (entry 11). The superiority
of (S)-8c might be due to the cleavage of the Ir-N bond of the
intermediate by HI. A similar additive effect of aqueous HX
was reported for the hydrogenation of R-ketoester using
ruthenium-halogen complexes of BINAP.3d For asymmetric
hydrogenation of cyclic imines 13, 14, and 15, hydrosilylation
based on chiral oxazolinyl-phosphine complexes of ruthenium,
rhodium, and iridium (up to 88% ee for 13; 25% ee for 14), as
well as hydrogenation or hydrosilylation using chiral ansa-type
titanocene/PhSiH3 systems (up to 99% ee for 13 and 14; 98%
ee for 15), have been reported.26
Conclusion
We developed a new and convenient one-pot reaction to
prepare mononuclear halide-carboxylate iridium(III) complexes
and cationic triply halogen-bridged dinuclear idirium(III) com-
plexes of BINAP, p-TolBINAP, and SYNPHOS. These iridium-
(III) complexes were tested as catalyst precursors for asymmetric
hydrogenation of cyclic imines 13-15 and 2-phenylquinoline
(16). The halide ligand remained intact and the carboxylate
ligand was eliminated during the catalytic reaction. Catalytic
activity of the cationic iodo-dinuclear BINAP complex 8c was
higher than that of the corresponding chloride and bromide
BINAP complexes and superior to all carboxylate complexes,
though the enantioselectivity was decreased. Cationic iodo-
dinuclear p-TolBINAP (S)-10c and SYNPHOS (S)-12c com-
plexes had better enantioselectivity for asymmetric hydrogena-
tion of 16 among the tested iridium(III) complexes. Our studies
of the catalytic application of these iridium(III) complexes as
well as application of our synthetic method to the preparation
of other Ir catalysts continue.
Asymmetic Hydrogenation of 2-Phenylquinoline by Iri-
dium(III) Complexes of BINAP, p-TolBINAP, and SYN-
PHOS. On the basis of the hydrogenation of cyclic imines, we
used iodide iridium(III) complexes (S)-2c and (S)-8c of BINAP
as catalyst precursors for asymmetric hydrogenation of 2-phen-
ylquinoline (16) with I2 as an additive,16 giving (S)-17 (Table
4, entries 1 and 2). The complexes (S)-2c and (S)-8c were active
catalysts, but the enantioselectivity was not satisfactory. To
optimize the chiral phosphine ligand (BINAP, p-TolBINAP, and
SYNPHOS), asymmetric hydrogenation of 16 using p-TolBI-
Experimental Section
General Procedures. All reactions and manipulations were
performed under argon by use of standard vacuum line and Schlenk
tube techniques. 1H NMR spectra were recorded on a Varian
Mercury 300, and chemical shifts are reported in ppm (δ) relative
to tetramethylsilane or referenced to the chemical shifts of residual
solvent resonances (CHCl3, C6H6, and CH2Cl2 were used as internal
standards, δ 7.26, 7.20, and 5.32, respectively). 31P{1H} NMR
spectra were recorded on a Varian Mercury 300 at 121.49 MHz,
and chemical shifts were referenced to external 85% H3PO4. 19F
NMR spectra were recorded on a Varian Mercury 300 at 282.34
MHz; chemical shifts were referenced to external R,R,R-trifluoro-
toluene (-67.73 ppm). Infrared spectra were recorded on a JASCO
FT/IR-230; mass spectra on a JEOL JMS DX-303HF spectrometer;
(26) (a) Takei, I.; Nishibayashi, Y.; Arikawa, Y.; Uemura S.; Hidai, M.
Organometallics 1999, 18, 2271. (b) Willoughby, C. A.; Buchwald, S. L.
J. Org. Chem. 1993, 58, 7627. (c) Verdaguer, X.; Lange, U. E. D.; Reding,
M. T.; Buchwald, S. L. J. Am. Chem. Soc. 1996, 118, 6784. (d) Beagley,
P.; Davies, P. J.; Blacker, A. J.; White, C. Organometallics 2002, 21, 5852.

2510 Organometallics, Vol. 25, No. 10, 2006
Yamagata et al.
GC analyses on a Shimadzu GC-14A gas chromatograph with a
Shimadzu C-R3A Chromatopac; and HPLC on a JASCO UV-970
and PU-980 with a Shimadzu C-R16A Chromatopac. Elemental
analyses were recorded on a Perkin-Elmer 2400 at the Faculty of
Engineering Science, Osaka University. All melting points were
recorded on a Yanaco MP-52982 and are not corrected.
Unless otherwise noted, reagents were purchased from com-
mercial suppliers and used without further purification. Dichloro-
methane (<0.003%) was degassed. Tetrahydrofuran, toluene,
hexane, and diethyl ether were distilled over sodium benzophenone
ketyl under argon prior to use. [Ir(µ-Cl)(coe)]2 (6a) (COE: cyclo-
octene),27 [Ir(µ-Cl)(cod)]2 (1a) (COD: 1,5-cyclooctadiene),27 and
[Ir(µ-Cl){(S)-binap}]2 [(S)-5a]19 were prepared according to the
literature methods. 2-Phenyl-1-pyrroline (13), 2-phenyl-3,4,5,6-
tetrahydropyridine (14), and 2-phenyl-4,5,6,7-tetrahydro-3H-azepine
(15) were prepared according to the literature.28,29
Preparation of [Ir(µ-Br)(cod)]2 (1b). Complex 1b was prepared
according to the modified literature method.30 To a Schlenk flask
were added Na2IrBr6 (2.11 g, 2.94 mmol), H2O (20 mL), 2-propanol
(9.0 mL), and COD (2.9 mL, 24 mmol). The mixture was then
refluxed for 12 h. After the reaction mixture was cooled to room
temperature, a dark yellow suspension was obtained. All volatiles
were removed under reduced pressure. The residue was extracted
with toluene (20 mL × 3). The combined toluene extract was
washed with H2O (20 mL) and ethanol (20 mL × 2), and then the
toluene solution was concentrated in vacuo to afford 1b (1.28 g,
57%) as a deep red solid. The purity was satisfactory in the
following reaction. Recrystallization from THF afforded an analyti-
cally pure product of 1b, mp 196-198 °C (dec). 1H NMR (CDCl3,
35 °C): δ 4.35 (m, 8H, dCH), 2.20-2.24 (m, 8H, -CHH-), 1.40-
1.50 (m, 8H, -CHH-). Anal. Calcd for C16H24Br2Ir2: C, 25.27;
H, 3.18. Found: C, 25.22; H, 2.83. The structure of 1b was
confirmed by X-ray analysis. A drawing and crystallographic data
are deposited as Supporting Information.
Preparation of [Ir(µ-I)(cod)]2 (1c). The mixture of [Ir(µ-Cl)-
(cod)]2 (1a) (0.429 g, 0.639 mmol) and NaI (1.33 g, 8.86 mmol) in
ether (50 mL) was stirred at ambient temperature for 12 h. All
volatiles were removed under reduced pressure, and the resulting
residue was washed with H2O (15 mL × 5) and ethanol (10 mL),
leaving 1c (0.441 g, 81%) as a deep red solid. The purity was
satisfactory in the following reaction, but recrystallization from THF
afforded an analytically pure product of 1c, mp 249-254 °C (dec).
1H NMR (CDCl3, 35 °C): δ 4.43-4.44 (m, 8H, dCH), 2.10-
2.14 (m, 8H, -CHH-), 1.13-1.36 (m, 8H, -CHH-). Anal. Calcd
for C16H24I2Ir2: C, 22.49; H, 2.83. Found: C, 22.82; H, 2.86. The
structure of 1c was confirmed by X-ray analysis. A drawing and
crystallographic data are deposited as Supporting Information.
yellow solid (183 mg, 80% yield), mp 105 °C (dec); major:minor
) 95:5. Major isomer (Λ-isomer): 1H NMR (C6D6, 35 °C): δ
6.34-8.24 (m, 32H, Ph + naphthyl), 1.55 (s, 3H, O2CCH3), -24.94
2
(dd, JH-P ) 23 and 17 Hz, 1H, Ir-H). 31P{1H} NMR (C6D6, 35
2
2
°C): δ -0.7 (d, JP-P ) 15 Hz), -1.5 (d, JP-P ) 15 Hz). Minor
isomer (∆-isomer): a hydride signal was observed in the 1H NMR
2
(C6D6, 35 °C): δ -24.8 (dd, JH-P ) 23 and 17 Hz, 1H, Ir-H).
IR (KBr tablet): 2270 cm-1 (Ir-H). Anal. Calcd for C46H36-
IIrP2O2: C, 55.15; H, 3.62. Found: C, 55.40; H, 3.88.
IrCl(H)(O2CCH3)[(S)-binap] [(S)-2a]. Although the complex
(S)-2a was obtained by the same procedure as (S)-2c, modification
by using [Ir(µ-Cl)(coe)]2 (6a) instead of [Ir(µ-Cl)(cod)]2 (1a) as a
starting material was conducted to give (S)-2a in 97% yield, mp
142 °C (dec); major:minor ) 96:4. Spectral data were superimposed
with that reported in the literature.7b Major isomer (Λ-isomer): 1H
NMR (CDCl3, 35 °C): δ 6.62-7.79 (m, 32H, Ph + naphthyl),
1.71 (s, 3H, O2CCH3), -26.26 (dd, 2JH-P ) 20, 23 Hz, 1H, Ir-H).
2
31P{1H} NMR (CDCl3, 35 °C): δ 0.7 (d, JP-P ) 19 Hz), -2.1
(d). Minor isomer (∆-isomer): a hydride signal was observed in
the 1H NMR (C6D6, 35 °C): δ -24.3 (dd, 2JH-P ) 23 and 17 Hz,
1H, Ir-H). IR (KBr tablet): 2264 cm-1 (Ir-H).
IrBr(H)(O2CCH3)[(S)-binap] [(S)-2b]: 66% yield, mp 120 °C
(dec); major:minor ) 96:4. Major isomer (Λ-isomer): 1H NMR
(CDCl3, 35 °C): δ 6.34-8.25 (m, 32H, Ph + naphthyl), 1.59 (s,
2
3H, O2CCH3), -25.19 (dd, JH-P ) 23, 19 Hz, 1H, Ir-H). 31P-
2
{1H} NMR (CDCl3, 35 °C): δ 1.3 (d, JP-P ) 17 Hz), -1.9 (d).
Minor isomer (∆-isomer): a hydride signal was observed in the
2
1H NMR (C6D6, 35 °C): δ -24.84 (dd, JH-P ) 23 and 17 Hz,
1H, Ir-H). IR (KBr tablet): 2268 cm-1 (Ir-H). Anal. Calcd for
C46H36BrIrP2O2: C, 57.86; H, 3.80. Found: C, 57.52; H, 3.91.
IrCl(H)(O2CPh)[(S)-binap] [(S)-3a]: 74% yield, mp 135 °C
1
(dec). H NMR (CDCl3, 35 °C): δ 6.34-8.24 (m, 37H, Ph +
2
naphthyl + PhCO2), -26.48 (dd, JH-P ) 23, 21 Hz, 1H, Ir-H).
2
31P{1H} NMR (CDCl3, 35 °C): δ -1.3 (d, JP-P ) 18 Hz), -2.2
(d). IR (KBr tablet): 2279 cm-1 (Ir-H).
IrBr(H)(O2CPh)[(S)-binap] [(S)-3b]: 67% yield, mp 175 °C
1
(dec). H NMR (CD2Cl2, 35 °C): δ 6.50-8.09 (m, 37H, Ph +
2
naphthyl + PhCO2), -26.24 (dd, JH-P ) 23, 19 Hz, 1H, Ir-H).
2
31P{1H} NMR (CD2Cl2, 35 °C): δ 0.1 (d, JP-P ) 16 Hz), -3.6
(d). IR (KBr tablet): 2279 cm-1 (Ir-H). Anal. Calcd for C51H38-
BrIrP2O2: C, 60.24; H, 3.77. Found: C, 59.98; H, 3.94.
IrI(H)(O2CPh)[(S)-binap] [(S)-3c]: 77% yield, mp 148 °C (dec).
1H NMR (CD2Cl2, 35 °C): δ 6.57-8.03 (m, 37H, Ph + naphthyl
2
+ PhCO2), -25.91 (dd, JH-P ) 22, 17 Hz, 1H, Ir-H). 31P{1H}
2
NMR (CD2Cl2, 35 °C): δ 1.7 (d, JP-P ) 16 Hz), -2.7 (d). IR
(KBr tablet): 2279 cm-1 (Ir-H). Anal. Calcd for C51H38-
IIrP2O2‚0.25(CH2Cl2): C, 56.72; H, 3.58. Found: C, 56.47; H, 3.76.
Preparation of Hydrido(carboxylato)iridium(III) Complexes
IrX(H)(O2CR)[(S)-binap] (R ) CH3, Ph, C6H4CH3-4; X ) Cl,
Br, I). Typical Procedure. A mixture of [Ir(µ-I)(cod)]2 (1c) (102
mg, 0.119 mol) and (S)-BINAP (151 mg, 0.242 mol) in toluene
(15 mL) was stirred for 6 h at room temperature. Acetic acid (0.069
mL, 1.2 mmol) was added to the solution. After the solution was
stirred for 15 h, the orange solution finally turned to pale yellow.
All volatiles were removed under reduced pressure, and the residue
was dissolved in dichloromethane. Addition of hexane resulted in
the precipitation of IrI(H)(O2CCH3)[(S)-binap] [(S)-2c] as a pale
IrCl(H)(O2CC6H4CH3-4)[(S)-binap] [(S)-4a]: 96% yield, mp
147 °C (dec). 1H NMR (CDCl3, 35 °C): δ 6.56-7.87 (m, 36H, Ph
+ naphthyl + CH3C6H4CO2), 2.29 (s, 3H, CH3C6H4), -26.44 (dd,
2JH-P ) 20, 23 Hz, 1H, Ir-H). 31P{1H} NMR (CDCl3, 35 °C): δ
0.9 (d, 2JP-P ) 19 Hz), -2.7 (d). IR (KBr tablet): 2280 cm-1 (Ir-
H). Anal. Calcd for C52H40ClIrP2O2: C, 63.31; H, 4.09. Found:
C, 63.22; H, 3.86.
IrBr(H)(O2CC6H4CH3-4)(H)[(S)-binap] [(S)-4b]: 54% yield,
1
mp 168 °C (dec). H NMR (CD2Cl2, 35 °C): δ 6.46-7.90 (m,
36H, Ph + naphthyl + CH3C6H4CO2), 2.34 (s, 3H, CH3C6H4),
2
-26.28 (dd, JH-P ) 23, 19 Hz, 1H, Ir-H). 31P{1H} NMR (CD2-
(27) (a) Herde, J. L.; Lambert, J. C.; Senoff, C. V. Inorg. Synth. 1974,
15, 18. (b) Baghurst, D. R.; Michael, D.; Mingos, P.; Watson, M. J. J.
Organomet. Chem. 1989, 368 (3), C43-C45.
(28) Hua, D. H.; Miao, S. W.; Bharathi, S. N.; Katuhira, T.; Bravo, A.
J. Org. Chem. 1990, 55, 3682.
Cl2, 35 °C): δ -0.1 (d, 2JP-P ) 18 Hz), -3.5 (d). IR (KBr tablet):
2279 (Ir-H). Anal. Calcd for C52H40BrIrP2O2‚0.25(CH2Cl2): C,
59.64; H, 3.88. Found: C, 59.69; H, 4.01.
(29) Willoughby, C. A.; Buchwald, S. L. J. Am. Chem. Soc. 1994, 116,
8952.
(30) (a) Ainscough, E. H.; Robinson, S. D.; Levison, J. J. J. Chem. Soc.
(A) 1971, 3413. (b) Onderdelinden, A. L.; Ent, A. Inorg. Chim. Acta 1972,
420. (c) Muller, J.; Tschampel, M.; Pickardt, J. Z. Naturforsch. 1986, 41b,
76.
IrI(H)(O2CC6H4CH3-4)[(S)-binap] [(S)-4c]: 60% yield, mp 155
°C (dec). 1H NMR (CD2Cl2, 35 °C): δ 6.47-7.90 (m, 36H, Ph +
naphthyl + CH3C6H4CO2), 2.40 (s, 3H, CH3C6H4), -25.95 (dd,
2JH-P ) 22, 17 Hz, 1H, Ir-H). 31P{1H} NMR (CD2Cl2, 35 °C): δ
2
-1.8 (d, JP-P ) 17 Hz), -3.0 (d). IR (KBr tablet): 2270 cm-1

Mononuclear Halo-Carboxylate Iridium(III) Complexes
Organometallics, Vol. 25, No. 10, 2006 2511
(Ir-H). Anal. Calcd for C52H40IIrP2O2‚CH2Cl2: C, 54.74; H, 3.64.
temperature, and then aqueous HI (55%, 29 µL) was added via a
syringe. After the reaction mixture was stirred overnight at room
temperature, all volatiles were removed under reduced pressure.
The residue was dissolved in dichloromethane, and then hexane
was added to precipitate (S)-8c (66.0 mg, 79% yield) as an air-
stable pale yellow powder, mp 110 °C (dec). This compound
contained some impurities. 1H NMR (CDCl3, 300 MHz, -10 °C):
δ 6.6-8.4 (m, aromatic, 64H), -19.0 (dd, 2JH-P ) 11, 18 Hz, 1H,
Ir-H). 31P{1H} NMR (CDCl3, 121 MHz, -10 °C): δ -4.6 (m),
-12.8 (m). IR (film): 2228 cm-1 (broad, Ir-H). ESI-MS: m/z
2013 (M+). Conductivity Λ0 (CH2Cl2): 180.2 S cm2 mol-1. Anal.
Calcd for C88H66I4Ir2P4‚0.25(CH2Cl2): C, 49.06; H, 3.10. Found:
C, 48.94; H, 2.90.
Found: C, 55.11; H, 3.85.
Preparation of IrBr(cod)[(S)-binap] [(S)-7b]. A solution of
[Ir(µ-Br)(cod)]2 (1b) (37.2 mg, 0.049 mol) and (S)-BINAP (65.4
mg, 0.105 mol) in toluene (20 mL) was stirred at room temperature
for 6 h. Removal of all volatiles under reduced pressure afforded
a yellow-orange solid, which was washed with hexane (3 × 5 mL).
(S)-7b was obtained as a yellow-orange solid (61.4 mg, 70%), mp
1
158 °C (dec). H NMR (C6D6, 35 °C): δ 5.89-9.37 (m, 32H, Ph
+ naphthyl), 3.20-3.69 (m, 5H, dCH and -CH2-), 2.14-2.31
(m, 4H, -CH2-), 1.23-1.40 (m, 3H, -CH2-). 31P{1H} NMR
2
(C6D6, 35 °C): δ -3.66 (d, JP-P ) 38 Hz), -8.09 (d).
IrI(cod)[(S)-binap] [(S)-7c]: 91% yield, mp 167 °C (dec). H
1
[{Ir(H)[(S)-binap]}2(µ-Br)3]+Br- [(S)-8b]: 95% yield, mp 162
NMR (C6D6, 35 °C): δ 5.94-8.75 (m, 32H, Ph + naphthyl,), 3.78-
3.93 (m, 4H, dCH and -CH2-), 3.19 (m, 1H, -CH2-), 2.25-
2.80 (m, 3H, -CH2-), 1.23-1.89 (m, 4H, -CH2-). 31P{1H} NMR
(C6D6, 35 °C): δ -6.5 (d, 2JP-P ) 38 Hz), -11.0 (d). Anal. Calcd
for C52H44IIrP2‚0.25(CH2Cl2): C, 58.58; H, 4.19. Found: C, 58.46;
H, 3.81.
1
°C (dec). H NMR (CDCl3, 300 MHz, 35 °C): δ 6.2-8.2 (m,
2
aromatic, 64H), -21.52 (dd, JH-P ) 14, 16 Hz, 2H, Ir-H). 31P-
2
{1H} NMR (CDCl3, 121 MHz, 35 °C): δ -0.9 (d, JP-P ) 19
Hz), -9.2 (d). IR (film): 2268 cm-1 (Ir-H). ESI-MS: m/z 1872
(M+). Conductivity Λ0 (CH2Cl2): 139.8 S cm2 mol-1. Anal. Calcd
for C88H66Br4Ir2P4‚0.25(CH2Cl2): C, 53.73; H, 3.40. Found: C,
53.63; H, 3.39.
Preparation of [IrI(O2CCH3)(H){(S)-p-tolbinap}] [(S)-9c]. A
mixture of [Ir(µ-I)(cod)]2 (1c) (148 mg, 0.174 mol) and (S)-p-
TolBINAP (238 mg, 0.350 mol) in toluene (30 mL) was stirred
for 6 h at room temperature. To this mixture was added acetic acid
(0.099 mL, 1.7 mol). After the solution was stirred for 15 h, a pale
yellow solution was concentrated under reduced pressure to remove
all volatiles. The resulting residue was dissolved in dichloromethane,
and then addition of hexane induced the precipitation of (S)-9c as
-
[{Ir(H)[(S)-binap]}2(µ-Cl)3]+PF6 [(S)-8d]: 89% yield. 1H
NMR (CDCl3, 300 MHz, 35 °C): δ 6.24-7.98 (m, aromatic, 64H),
-22.68 (dd, 2JH-P ) 14, 16 Hz, 2H, Ir-H). 31P{1H} NMR (CDCl3,
2
121 MHz, 35 °C): δ -1.5 (d, JP-P ) 17 Hz), -9.0 (d), -144.7
(sep, JP-F ) 704 Hz).
-
[{Ir(H)[(S)-binap]}2(µ-Br)3]+PF6 [(S)-8e]: 96% yield. 1H
NMR (CDCl3, 300 MHz, 35 °C): δ 6.22-8.17 (m, aromatic, 64H),
1
a pale yellow powder (122 mg, 33% yield), mp 121 °C (dec). H
-21.51 (dd, 2JH-P ) 14, 16 Hz, 2H, Ir-H). 31P{1H} NMR (CDCl3,
NMR (C6D6, 300 MHz, 35 °C): δ 6.19-8.25 (m, 28H, C6H4CH3
+ naphthyl,), 2.01 (s, 3H, C6H4CH3), 2.00 (s, 3H, C6H4CH3), 1.72
(s, 3H, O2CCH3), 1.69 (s, 3H, C6H4CH3), 1.62 (s, 3H, C6H4CH3).
-24.95 (dd, 2JP-H ) 22, 17 Hz, 1H, Ir-H). 31P {1H} NMR (C6D6,
2
121 MHz, 35 °C): δ 2.3, (d, JP-P ) 17 Hz), 10.6 (d), -144.8
(sep, JP-F ) 704 Hz).
-
[{Ir(H)[(S)-binap]}2(µ-I)3]+PF6 [(S)-8f]: 96% yield. This
compound contained small amount of unidentified compounds. 1H
NMR (CDCl3, 300 MHz, 35 °C): δ 6.63-8.36 (m, aromatic, 64H),
-19.0 (br, 1H, Ir-H). 31P{1H} NMR (CDCl3, 121 MHz, 35 °C):
δ -6.21 (br), -11.9 (br), -144.8 (sep, JP-F ) 704 Hz).
2
121 MHz, 35 °C): δ -3.0 (d, JP-P ) 17 Hz), -3.8 (d). IR (KBr
tablet): 2270 cm-1 (Ir-H).
IrCl(O2CCH3)(H)[(S)-p-tolbinap] [(S)-9a]: 39% yield, mp
1
>140 °C (dec). H NMR (C6D6, 300 MHz, 35 °C): δ 6.18-8.25
[{Ir(H)[(S)-tolbinap]}2(µ-I)3]+I- [(S)-11c]: 58% yield. This
compound contained small amount of unidentified compounds. 1H
NMR (CDCl3, 300 MHz, 35 °C): δ 6.2-8.4 (m, aromatic, 56H),
2.33 (s, C6H4Me, 6H), 2.11 (s, C6H4Me, 6H), 2.08 (s, C6H4Me,
6H), 1.91 (s, C6H4Me, 6H), -19.11 (dd, J ) 16, 21 Hz, 2H, Ir-
H). 31P{1H} NMR (CDCl3, 121 MHz, 35 °C): δ -6.2 (m), -13.6
(m). IR (film): 2222 cm-1 (Ir-H). ESI-MS: m/z 2125 (M+).
(m, 28H, C6H4CH3 + naphthyl,), 2.01 (s, 3H, C6H4CH3), 2.00 (s,
3H, C6H4CH3), 1.72 (s, 3H, O2CCH3), 1.69 (s, 3H, C6H4CH3), 1.67
2
(s, 3H, C6H4CH3), -25.39 (dd, JH-P ) 23, 20 Hz, 1H, Ir-H).
2
31P{1H} NMR (C6D6, 121 MHz, 35 °C): δ -0.8 (d, JP-P ) 17
Hz), -4.3 (d). IR (KBr tablet): 2270 cm-1 (Ir-H).
[IrI(O2CCH3)(H){(S)-synphos}] [(S)-10c]: 94% yield. 1H NMR
(CDCl3, 300 MHz, 35 °C): δ 7.14-7.86 (m, 20H, phenyl H), 6.32-
6.57 (m, 6H, aromatic H), 3.81-4.02 (m, 8H, -CH2-), 1.63 (s,
[{Ir(H)[(S)-synphos]}2(µ-I)3]+I- [(S)-12c]. This compound was
1
in situ generated and characterized by H and 31P NMR spectros-
2
3H, O2CCH3), -26.39 (dd, JH-P ) 17, 23 Hz, 1H, Ir-H). 31P-
copy and contained a small amount of unidentified compounds.
2
{1H} NMR (CDCl3, 121 MHz, 35 °C): δ -4.22 (d, JP-P ) 16
1H NMR (CDCl3, 300 MHz, 35 °C): δ 6.26-8.27 (m, 52H,
Hz), -5.80 (d).
2
aromatic H), 3.46-4.34 (m, 16H, -CH2-), -19.71 (dd, JH-P
)
Preparation of [{Ir(H)[(S)-binap]}2(µ-Cl)3]+Cl- [(S)-8a]. A
mixture of [IrCl(coe)2]2 (6a) (120.0 mg, 179.0 µmol) and (S)-BINAP
(239.0 mg, 384.2 µmol) in toluene (5 mL) was stirred for 3 h at
room temperature. Upon addition of 35% hydrochloric acid (79
µL), the color of the solution immediately turned to yellow. After
the reaction mixture was stirred overnight, all volatiles were
removed under reduced pressure. The residue was dissolved in
dichloromethane, and then precipitation by hexane afforded (S)-8a
(290.7 mg, 92% yield) as an air-stable pale yellow powder, mp
162 °C (dec). 1H NMR (CDCl3, 300 MHz, 35 °C): δ 6.3-8.1 (m,
14, 16 Hz, 2H, Ir-H). 31P{1H} NMR (CDCl3, 121 MHz, 35 °C):
δ -6.3 (br), -13.4 (br).
Structure Determination of (S)-4a-c and (S)-7c. Single
crystals of (S)-4a, (S)-4b, and (S)-4c‚CH2Cl2 were obtained by
crystallization from a mixture of CH2Cl2 and hexane. Single crystals
of (S)-7c‚4(C6H6) were obtained by crystallization from benzene.
All measurements were made on a Rigaku RAXIS RAPID imaging
plate area detector with graphite-monochromated Mo KR radiation.
Details of X-ray data collections are listed in Table 5. The structures
were solved by direct methods with SIR-9731 and refined against
F2 with SHELXL-97.32
2
aromatic, 64H), -22.70 (dd, JH-P ) 15, 21 Hz, 1H, Ir-H). 31P-
2
{1H} NMR (CDCl3, 121 MHz, 35 °C): δ -0.4 (d, JP-P ) 20
Hz), -7.9 (d). IR (film): 2269 cm-1 (Ir-H). ESI-MS: m/z 1738
(M+). Conductivity Λ0 (CH2Cl2): 301.6 S cm2 mol-1. Anal. Calcd
for C88H66Cl4Ir2P4‚0.5(CH2Cl2): C, 58.53; H, 3.72. Found: C,
58.51; H, 3.73.
The X-ray crystallographic information files, in CIF format, are
available from the Cambridge Crystallographic Data Centre on
(31) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.;
Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 1999, 32, 115.
(32) Sheldrick, G. M. SHELX97, Programs for Crystal Structure Analysis
(Release 97-2); University of Go¨ttingen, Germany, 1998.
Preparation of [{Ir(H)[(S)-binap]}2(µ-I)3]+I- [(S)-8c]. A reac-
tion mixture of [IrCl(coe)2]2 (6a) (33.5 mg, 39.2 µmol) and (S)-
BINAP (53.7 mg, 86.2 µmol) in toluene (5 mL) was stirred at room

2512 Organometallics, Vol. 25, No. 10, 2006
Yamagata et al.
Table 5. Crystal Data and Structure Refinement Details for (S)-4a, (S)-4b, (S)-4c‚CH2Cl2, and (S)-7c‚4C6H6
4a
4b
4c‚CH2Cl2
7c‚4C6H6
empirical formula
fw
C52H40ClIrO2P2
986.43
C52H40BrIrO2P2
1030.89
C53H42ICl2IrO2P2
1162.81
C52H44IIrP2‚4(C6H6)
1362.34
temperature (K)
wavelength (Å)
cryst syst
space group
a (Å)
103(1)
0.71069
monoclinic
P21
13.8788(2)
15.29428(19)
10.75023(17)
112.2875(5)
2111.43(5)
2
100(1)
0.71075
monoclinic
P21
14.041(5)
15.355(5)
13.958(5)
134.74(2)
2137.5(13)
2
100(1)
0.71075
monoclinic
P21
11.134(4)
15.215(6)
13.984(5)
106.04(3)
2276.8(15)
2
120(1)
0.71075
monoclinic
P21
11.3956(4)
15.9527(7)
16.7221(8)
97.047(2)
3016.9(2)
2
b (Å)
c (Å)
â (deg)
volume (Å3)
Z
D
calcd (Mg/m3)
1.552
3.342
984
1.602
4.174
1020
1.696
3.839
1140
1.500
2.822
1368
abs coeff (mm-1
F(000)
)
cryst size (mm)
θ range for data collection (deg)
limiting indices
0.36 × 0.19 × 0.17
2.66 to 32.57
-21 e h e 21
-23 e k e 23
-16 e l e 16
88 135
0.40 × 0.16 × 0.13
3.02 to 32.57
-21 e h e 21
-22 e k e 23
-21 e l e 21
91 111
0.24 × 0.18 × 0.18
3.03 to 32.51
-16 e h e 16
-22 e k e 22
-21 e l e 21
108 564
0.60 × 0.18 × 0.13
3.13 to 32.53
-17 e h e 17
-24 e k e 24
-25 e l e 25
154 719
no. of reflns collected
no. of unique reflns
R(int)
15 241
0.0530
15 322
0.0427
16 290
0.0521
21 637
0.0781
θ (deg)
completeness (%)
abs corr
32.57
99.9
numerical
0.7914/0.5121
32.57
99.4
numerical
0.7754/0.3199
32.51
99.4
32.53
99.5
numerical
0.7102/0.3587
numerical
0.7941/0.5402
max./min. transmn
refinement method
no. of data/restraints/params
goodness-of-fit on F2
R1/wR2 [I > 2σ(I)]
R1/wR2 (all data)
Flack parameter (x)
full-matrix least-squares on F2
16 290/0/549
1.039
0.0228/0.0486
0.0250/0.0493
-0.009(2)
15 322/0/522
1.091
0.0213/0.0458
0.0231/0.0462
0.012(3)
16 290/0/549
1.016
0.0229/0.0429
0.0268/0.0435
-0.0014(18)
1.225/-1.372
21 637/0/720
1.133
0.0337/0.0770
0.0391/0.0798
0.020(3)
∆/F(max./min.) (e‚Å-3
)
0.893/ -0.959
1.020/-1.161
1.695/-1.823
quoting the deposition numbers CCDC 249402 for (S)-4a, CCDC
249403 for (S)-4b, CCDC 249404 for (S)-4c‚CH2Cl2, and CCDC
249405 for (S)-7c‚4(C6H6). Copies of this information may be
obtained free of charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or CCD Home Page: http://www.ccdc.cam.ac.uk).
General Procedure for the Ir-Catalyzed Asymmetric Hydro-
genation of Cyclic Imines. A Schlenk flask was charged with an
imine and a hydrido(carboxylato)iridium(III) complex under argon.
Toluene ([iridium complex] ) 0.5 mol/L) was added, and then the
resulting yellow solution was transferred to a stainless steel
autoclave. The autoclave was charged three times by H2 to displace
the argon, and subsequently the pressure was increased to 60 kg/
cm2. The reaction mixture in the autoclave was stirred at ambient
temperature. After H2 was released, solvent was removed and then
Ku¨gelrohr distillation afforded a colorless oil comprised of the
starting imine and the resulting amine. The conversions and the
enantiomeric excesses were determined by 1H NMR, GC, or HPLC
analysis of the crude product or its derivatives.
compound obtained by the reaction of the isolated amine with
trifluoroacetic anhydride in CH2Cl2 at room temperature. 1H NMR
(CDCl3, 35 °C): δ 7.38-7.19 (m, 5H), 3.61-3.56 (m, 1H), 3.22-
3.17 (m, 1H), 2.84-2.76 (m, 1H), 1.90-1.86 (m, 1H), 1.83-1.77
(m, 2H), 1.69-1.45 (m, 4H including N-H). GC (J&W Scientific
DB-1, temp ) 100 °C (2 min), 20 °C up per 1 min, and 250 °C):
imine t ) 6.8 min, amine t ) 6.1 min. Chiral GC (GL Science
Chirasil DEX-CB, temp ) 115 °C): (S) t ) 32.3 min, (R) t )
35.3 min.
1-Aza-2-phenylcycloheptane. The conversion was determined
by 1H NMR and GC analysis of the crude product, and the
1
enantiomeric excess was determined by analysis. H NMR (300
MHz,CDCl3, 35 °C): 7.37-7.17 (m, 5H), 3.75 (dd, J ) 3.7 Hz,
10 Hz, 1H), 3.14 (dt, J ) 5, 14 Hz, 1H), 2.92-2.81 (m, 1H), 2.01-
1.92 (m, 1H), 1.88-1.55 (m, 8H). GC (J&W Scientific DB-1, temp
) 100 °C (2 min), 20 °C up per 1 min, and 250 °C): imine t ) 7.5
min, amine t ) 7.4 min. Chiral HPLC (Chiralcel OD-H column,
hexane, 1.0 mL/min., 254 nm temp ) 30 °C): (R) t ) 16.8 min,
(S) t ) 19.1 min.
2-Phenylpyrrolidine. The conversion was determined by 1H
NMR and GC analysis of the crude product, and the enantiomeric
excess was determined by GC analysis of the trifluoroacetoamide
compound obtained by the reaction of the isolated amine with
trifluoroacetic anhydride in CH2Cl2 at room temperature. 1H NMR
(CDCl3, 35 °C): δ 7.41-7.36 (m, 3H), 7.35-7.19 (m, 2H), 4.12
(t, J ) 8 Hz, 1H), 3.24-3.17 (m, 1H), 3.05-2.97 (m, 1H), 2.24-
2.13 (m, 1H), 1.97-1.79 (m, 3H including N-H), 1.73-1.61 (m,
1H). GC (J&W Scientific DB-1, temp ) 100 °C (2 min), 20 °C up
per 1 min, and 250 °C): imine t ) 5.8 min, amine t ) 5.5 min.
Chiral GC (GL Science Chirasil DEX-CB, temp ) 115 °C): (S)
t ) 24.6 min, (R) t ) 25.4 min.
Procedure for the Ir-Catalyzed Asymmetric Hydrogenation
of 2-Phenylquinoline. The reaction mixture containing iridium
complex (S)-12c (5.4 mg, 0.0025 mmol) in tetrahydrofuran was
transferred by a syringe to a dry 10 mL Schlenk, in which I2 (6.35
mg, 0.05 mmol) and 2-phenylquinoline (103 mg, 0.5 mmol) were
placed beforehand. This Schlenk was equipped with a magnetic
bar and a stopper and connected to a supply of vacuum/argon. The
mixture was degassed with three vaccum/argon cycles. The
hydrogenation was performed under H2 (initial pressure was 60
kg/cm2) at 30 °C. After releasing the hydrogen, the reaction mixture
was concentrated. The purification was performed by a short silica
gel column eluted with a mixture of cyclohexane and EtOAc (98:
2) to give the pure product. The enantiomeric excess of the product
was determined by chiral HPLC (Chiralcel OJ, Chiralcel OD-H).
1H NMR (CDCl3, 35 °C): δ 2.02-2.11 (1H, m), 2.13-2.20 (1H,
2-Phenylpiperidine. The conversion was determined by 1H
NMR and GC analysis of the crude product, and the enantiomeric
excess was determined by analysis of the trifluoroacetoamide

Mononuclear Halo-Carboxylate Iridium(III) Complexes
Organometallics, Vol. 25, No. 10, 2006 2513
m), 2.74-2.81 (1H, m), 2.90-2,96 (1H, m), 4.08 (1H, br), 4.45-
4.49 (1H, m), 6.55-6.58 (1H, m), 6.68-6.69 (1H, m), 7.04-7.05
(2H, m), 7.32-7.44 (5H, m). MS (EI): m/z 209 (M+). HPLC
(Chiralcel OD-H, hexane and i-PrOH (90:10), detector: 254 nm,
flow rate: 1 mL/min) (S) t ) 9.5 min, (R) t ) 11.0 min.
Professor Emeritus K. Tani for fruitful discussions and sugges-
tions.
Supporting Information Available: X-ray structural informa-
tion for complexes (S)-4a, (S)-4b, (S)-4c‚CH2Cl2, and (S)-7c‚
4(C6H6) together with 1b and 1c. This material is available free of
charge via the Internet at http://pubs.acs.org.
Acknowledgment. This research was supported by a Grant-
in-Aid for Scientific Research from the Ministry of Education,
Culture, Sports, Science and Technology, Japan. We thank
OM051065J