New dihydride- and alkene-η6-arene complexes of iridium

Article abstract of DOI:10.1021/om010024u

The synthesis of iridium derivatives of general formula [(η⁶-arene)IrH₂(PR₃)]BF₄ {arene = benzene: R = ⁱPr (1), Cy (2); R = ⁱPr: arene = toluene (4), 1,3,5-trimethylbenzene (5), 1,2,4-trimethylbenzene (6), hexamethylbenzene (7), 1-methylstyrene (8), phenol (9), aniline (10)} and [(η⁶-arene)Ir(η²-C₂H₄) (PⁱPr₃)]BF₄ {arene = benzene (23), toluene (24), 1,3,5-trimethylbenzene (25), hexamethylbenzene (26)} is described. 1 and 2 have been obtained by treatment of [Ir(μ-OMe)(cod)]₂ with [HPR₃]BF₄, followed by reaction with H₂, in acetone/benzene mixtures. A similar synthetic methodology has been used to prepare the naphthalene complex [(η⁶-C₁₀H₈)IrH₂ (PⁱPr₃)]BF₄ (16) and the thiophene derivative [(η⁵-SC₄H₄)IrH₂ (PⁱPr₃)]-BF₄ (17). Compounds 4-10 have been prepared from 1 by arene substitution in acetone solutions. The substitution reactions involved a tris-acetone intermediate, which has been characterized in acetone-d₆, [IrH₂(OC(CD₃)₂)₃ (PⁱPr₃)]⁺ (3). The η⁶-aniline ligand of 10 can be displaced by three N-bonded anilines, to give the complex [IrH₂(Κ-N, NH₂Ph)₃(PⁱPr₃)]BF₄ (11). Other N-containing arenes such as quinoline and isoquinoline gave only products with N-coordinating ligands, 12-15. The treatment of 1 with NaBPh₄ led to the zwitterionic compound [Ph₃B(η⁶-Ph)IrH₂(Pⁱ Pr₃)] (18). This complex has been used as an arene ligand t obtain the compounds [Ph₂B{(η⁶-Ph)IrH₂ (PⁱPr₃)}₂]BF₄ (19), [PhB{(η⁶-Ph)IrH₂ (PⁱPr₃)}₃](BF₄)₂ (20), and [B{(η⁶-Ph)IrH₂ (PⁱPr₃)}₄](BF₄)₃ (21), in which the BPh₄^- anion is coordinated to two, three, or four iridium centers, respectively. Treatment of 1 with styrene afforded the Ir(I) compound [(η⁶-C₆H₅Et)Ir (η²-CH₂=CHPh)(PⁱPr₃)] BF₄ (22). Under similar conditions, the reaction of 1, 4, and 5 with ethylene produced ethane and the ethylene complexes 23-25. Compound 26 and the zwitterionic complex [Ph₃B(η⁶-Ph) Ir(η²-C₂H₄) (PⁱPr₃)] (27) have been prepared by arene displacement from 23. 1 has been found to catalyze, under mild conditions, the hydrogenation of several unsaturated substrates, including imines. The molecular structure of 23 has been determined by X-ray crystallography.

Full text of DOI:10.1021/om010024u

2716
Organometallics 2001, 20, 2716-2724
New Dih yd r id e- a n d Alk en e-η6-Ar en e Com p lexes of
Ir id iu m
Francisco Torres, Eduardo Sola, Marta Mart´ın, Christian Ochs, Graciela Picazo,
J ose´ A. Lo´pez, Fernando J . Lahoz, and Luis A. Oro*
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received J anuary 12, 2001
The synthesis of iridium derivatives of general formula [(η6-arene)IrH2(PR3)]BF4 {arene
i
i
) benzene: R ) Pr (1), Cy (2); R ) Pr: arene ) toluene (4), 1,3,5-trimethylbenzene (5),
1,2,4-trimethylbenzene (6), hexamethylbenzene (7), 1-methylstyrene (8), phenol (9), aniline
(10)} and [(η6-arene)Ir(η2-C2H4)(PiPr3)]BF4 {arene ) benzene (23), toluene (24), 1,3,5-
trimethylbenzene (25), hexamethylbenzene (26)} is described. 1 and 2 have been obtained
by treatment of [Ir(µ-OMe)(cod)]2 with [HPR3]BF4, followed by reaction with H2, in acetone/
benzene mixtures. A similar synthetic methodology has been used to prepare the naphthalene
complex [(η6-C10H8)IrH2(PiPr3)]BF4 (16) and the thiophene derivative [(η5-SC4H4)IrH2(PiPr3)]-
BF4 (17). Compounds 4-10 have been prepared from 1 by arene substitution in acetone
solutions. The substitution reactions involved a tris-acetone intermediate, which has been
characterized in acetone-d6, [IrH2(OC(CD3)2)3(PiPr3)]+ (3). The η6-aniline ligand of 10 can be
displaced by three N-bonded anilines, to give the complex [IrH2(κ-N, NH2Ph)3(PiPr3)]BF4
(11). Other N-containing arenes such as quinoline and isoquinoline gave only products with
N-coordinating ligands, 12-15. The treatment of 1 with NaBPh4 led to the zwitterionic
compound [Ph3B(η6-Ph)IrH2(PiPr3)] (18). This complex has been used as an arene ligand to
obtain the compounds [Ph2B{(η6-Ph)IrH2(PiPr3)}2]BF4 (19), [PhB{(η6-Ph)IrH2(PiPr3)}3](BF4)2
(20), and [B{(η6-Ph)IrH2(PiPr3)}4](BF4)3 (21), in which the BPh4- anion is coordinated to two,
three, or four iridium centers, respectively. Treatment of 1 with styrene afforded the Ir(I)
compound [(η6-C6H5Et)Ir(η2-CH2dCHPh)(PiPr3)]BF4 (22). Under similar conditions, the
reaction of 1, 4, and 5 with ethylene produced ethane and the ethylene complexes 23-25.
Compound 26 and the zwitterionic complex [Ph3B(η6-Ph)Ir(η2-C2H4)(PiPr3)] (27) have been
prepared by arene displacement from 23. 1 has been found to catalyze, under mild conditions,
the hydrogenation of several unsaturated substrates, including imines. The molecular
structure of 23 has been determined by X-ray crystallography.
In tr od u ction
taining phosphines,5 phosphites,6 carbonyl ligands,7 and
diphosphines8 have been described, although, to the best
η6-Arene complexes of iridium and rhodium have been
known for approximately 30 years, and some of them,
especially those of rhodium, have been found to be good
catalyst precursors in a variety of catalytic transforma-
tions.1 Despite these facts, the relative significance of
such compounds within the organometallic chemistry
of rhodium and iridium is still minor, in contrast to the
relevance of complexes containing η6-arene ligands in
the chemistry of other late transition metals such as
ruthenium and osmium.2 This situation is, most likely,
a consequence of the scarcity of synthetic procedures
leading to rhodium and iridium η6-arene complexes,
since, in fact, the vast majority of complexes of this type
reported so far correspond to only two formulations:
[CpM(arene)]2+ 3 and [M(arene)(diene)]+.4 In addition to
the latter, few particular examples of complexes con-
(3) (a) White, C.; Maitlis, P. M. J . Chem. Soc. (A) 1971, 3322. (b)
White, C.; Thompson, S. J .; Maitlis, P. M. J . Chem. Soc., Dalton Trans.
1977, 1654. (c) Maitlis, P. M. Acc. Chem. Res. 1978, 11, 301. (d) Espinet,
P.; Bailey, P. M.; Downey, R. F.; Maitlis, P. M. J . Chem. Soc., Dalton
Trans. 1980, 1048. (e) Grundy, S. L.; Maitlis, P. M. J . Organomet.
Chem. 1984, 272, 265. (f) Rybinskaya, M. I.; Kudinov, A. R.; Kaga-
novich, V. S. J . Organomet. Chem. 1983, 246, 279. (g) Amouri, H.;
Besace, Y.; Le Bras, J .; Vaissermann, J . J . Am. Chem. Soc. 1998, 120,
6171.
(4) (a) Schrock, R. R.; Osborn, J . A. Inorg. Chem. 1970, 9, 2339. (b)
Osborn, J . A.; Schrock, R. R. J . Am. Chem. Soc. 1971, 93, 3089. (c)
Green, M.; Kuc, T. A. J . Chem. Soc., Dalton Trans. 1972, 832. (d)
Green, M.; Parker, G. J . Chem. Soc., Dalton Trans. 1974, 333. (e)
Dragget, P. T.; Green, M.; Lowrie, S. F. E. J . Organomet. Chem. 1977,
135, C60. (f) Bianchi, F.; Gallazzi, M. C.; Porri, L.; Diversi, P. J .
Organomet. Chem. 1980, 202, 99. (g) Uso´n, R.; Oro, L. A.; Cabeza, J .;
Foces-Foces, C.; Cano, F. H.; Garc´ıa-Blanco, S. J . Organomet. Chem.
1983, 246, 73. (h) Uso´n, R.; Oro, L. A.; Carmona, D.; Esteruelas, M.
A.; Foces-Foces, C.; Cano, F. H.; Garcı´a-Blanco, S.; Va´zquez de Miguel,
A. J . Organomet. Chem. 1984, 273, 111. (i) Oro, L. A.; Valderrama,
M.; Cifuentes, P.; Foces-Foces, C.; Cano, F. H. J . Organomet. Chem.
1984, 276, 67. (j) Valderrama, M.; Scotti, M.; Ganz, R.; Oro, L. A.;
Lahoz, F. J .; Foces-Foces, C.; Cano, F. H. J . Organomet. Chem. 1985,
288, 97. (k) Esteruelas, M. A.; Oro, L. A. Coord. Chem. Rev. 1999, 193-
195, 557, and references therein.
* To whom correspondence should be addressed. E-mail:
oro@posta.unizar.es.
(1) Zhou, Z.; Facey, G.; J ames, B. R.; Alper, H. Organometallics
1996, 15, 2496, and references therein.
(2) Bennett, M. A. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: New York,
1995; Vol. 7, p 549.
(5) (a) Crabtree, R. H.; Mellea, M. F.; Mihelcic, J . M.; Quirk, J . M.
J . Am. Chem. Soc. 1982, 104, 107. (b) Bleeke, J . R.; Donaldson, A. J .
Organometallics 1988, 7, 1588.
10.1021/om010024u CCC: $20.00 © 2001 American Chemical Society
Publication on Web 05/26/2001

η6-Arene Complexes of Iridium
Organometallics, Vol. 20, No. 13, 2001 2717
of our knowledge, systematic synthetic methods leading
to such derivatives are still unknown. Only very recently
have Werner et al. described an original synthetic
procedure, based on the use of the solvento complex [Rh-
(C8H14)2(acetone)2]PF6, that may largely contribute to
extend the amount and variety of η6-arene complexes
of rhodium.9 In this work, we describe a versatile
synthetic route to dihydride-η6-arene complexes of
Ir(III) containing bulky alkylphosphines. These new
complexes, which have been found to be active catalysts
for the hydrogenation of a variety of unsaturated
substrates, are also convenient precursors for the syn-
thesis of new η6-arene complexes of Ir(I) with alkene
ligands. Part of this work has been previously com-
municated.10
In CDCl3 solutions, the spectroscopic data of 1 and 2
support the proposed structures. The H NMR spectra
1
of these compounds show high-field doublets (J HP ) 27
Hz) corresponding to the hydride ligands and singlets
at about δ 6.7 for the η6-benzene ligands. These ligands
appear in the 13C{1H} NMR spectra as doublets, with
J CP coupling constants of about 2 Hz. Moreover, the 31P
off-resonance spectra of both compounds show triplets,
indicative of two equivalent hydride ligands. The spectra
of compound 1 in acetone-d6 solutions show, together
with the signals corresponding to 1, those due to the
cation [IrH2(OC(CD3)2)3(PiPr3)]+ (3), indicating that the
labile benzene ligand can be substituted by three
acetone ligands (eq 2). This cationic species, which is
Resu lts a n d Discu ssion
1. Ca tion ic Ir id iu m (III) Com p lexes. In a recent
paper, we reported on the synthesis and reactivity of
the tris-acetonitrile dihydride complex [IrH2(NCCH3)3-
(PiPr3)]BF4, which was obtained after treatment of the
iridium dimer [Ir(µ-OMe)(cod)]2 with the phosphonium
salt [HPiPr3]BF4 in acetone/acetonitrile, followed by
reaction with hydrogen.11 A similar one-pot synthesis,
in the absence of acetonitrile and in the presence of
benzene, affords the η6-arene complex [(η6-C6H6)IrH2-
(PiPr3)]BF4 (1), as a white solid in diethyl ether/THF
mixtures (eq 1). This procedure is also applicable to
similar to the aforementioned tris-acetonitrile complex
[IrH2(NCCH3)3(PiPr3)]+, is characterized by a doublet
at δ -31.08 (J HP ) 23.7 Hz) in the H NMR spectrum
1
and a singlet at δ 31.32 in the 31P{1H} NMR spectrum.
Even though this labile tris-acetone compound seems
to be rather stable in acetone solutions, our attempts
to isolate it by following the procedure described for 1,
in the absence of benzene, led only to intractable black
solids (nonisolated complexes such as 3 are drawn
between brackets).
The equilibrium depicted in eq 2 allows the facile
preparation of other arene derivatives by substitution
of the benzene ligand, provided that the desired arene
coordinates to the iridium better than benzene. This is
the case for methyl-substituted arenes, 1-methylstyrene,
phenol, or aniline (eq 3). The spectroscopic data of the
phosphonium salts of other bulky phosphines such as
PCy3, which afforded the complex [(η6-C6H6)IrH2(PCy3)]-
BF4 (2), but fails for the salts obtained by protonation
of smaller ligands such as PMe3 or pyridine. In the case
of pyridine, the treatment of the starting iridium dimer
with [Hpy]BF4, in acetone/benzene, led to an equimolar
mixture of the known complexes [Ir(cod)(py)2]BF412 and
[(η6-C6H6)Ir(cod)]BF4.4 This result suggests that, in the
case of small ligands, the reaction intermediates could
undergo facile disproportionation processes, in agree-
ment with the behavior previously observed for related
[Ir(cod)LL′]+ compounds.12
(6) (a) Nolte, M. J .; Gafner, G.; Haines, L. M. J . Chem. Soc., Chem.
Commun. 1969, 1406. (b) Uso´n, R.; Lahuerta, P.; Reyes, J .; Oro, L. A.;
Foces-Foces, C.; Cano, F. H.; Garcı´a-Blanco, S. Inorg. Chim. Acta 1980,
42, 75. (c) Burch, R. R.; Muetterties, E. L.; Day, V. W. Organometallics
1982, 1, 188. (d) Bittersmann, E.; Hildenbrand, K.; Cervilla, A.;
Lahuerta, P. J . Organomet. Chem. 1985, 287, 255.
(7) Valderrama, M.; Oro, L. A. Can. J . Chem. 1982, 60, 1044.
(8) (a) Halpern, J .; Chan, A. S. C.; Riley, D. D.; Pluth, J . J . Adv.
Chem. Ser. 1979, 4, 332. (b) Townsend, J . M.; Blount, J . F. Inorg. Chem.
1981, 20, 269. (c) Schnabel, R. C.; Roddick, D. M. Organometallics 1996,
15, 3550.
(9) Werner, H.; Canepa, G.; Ilg, K.; Wolf, J . Organometallics 2000,
19, 4756.
(10) Torres, F.; Sola, E.; Mart´ın, M.; Lo´pez, J . A.; Lahoz, F. J .; Oro,
L. A. J . Am. Chem. Soc. 1999, 121, 10632.
(11) Sola, E.; Navarro, J .; Lo´pez, J . A.; Lahoz, F. J .; Oro, L. A.;
Werner, H. Organometallics 1999, 18, 3534.
(12) Crabtree, R. H.; Morris, G. E. J . Organomet. Chem. 1977, 135,
395.
complexes shown in eq 3 are consistent with the fast
rotation of the arene ligands around the Ir-arene axis.
This rotation results in the chemical equivalence of the
1
hydride ligands in the 293 K H NMR spectra, except
for complex 6, in which the asymmetry of the arene
ligand allows the observation of nonequivalent hydrides
showing a mutual coupling constant of 5.1 Hz. The X-ray
structure of the mesitylene derivative 5, which has been
described in a previous communication,10 supports the
structural proposals for these dihydride derivatives.
The reactions of eq 3 were typically carried out by
treatment of acetone solutions of 1 with an excess of
the desired arene, except in the case of complex 10,

2718 Organometallics, Vol. 20, No. 13, 2001
Torres et al.
Ta ble 1. Equ ilibr iu m Con sta n ts for Ar en e
which required the use of a stoichiometric amount of
aniline. This is due to the fact that, in the presence of
an excess of this ligand, the η6-aniline is replaced by
three N-bonded aniline ligands, affording the complex
[IrH2(κ-N,NH2Ph)3(PiPr3)]BF4 (11) analogous to 3 (eq 4).
Rep la cem en t by Aceton e-d 6
complex
arene ligand
K (M)
1
2
4
5
7
benzene
benzene
toluene
1,3,5-trimethylbenzene
hexamethylbenzene
aniline
3.5 × 10-1
3.6 × 10-1
7.5 × 10-2
7.2 × 10-3
a
10
3.2 × 10-5
Complex 3 was not detected by 1H NMR.
a
concentration of arene complex. In agreement with
previous observations in related complexes,4k the more
electron-rich arene ligands lead to the more stable
complexes.
Even though poorly donating arene ligands cannot
displace benzene from complex 1, their complexes can
be obtained by using these ligands instead of benzene
in the synthetic procedure of eq 1. This alternative has
been used for the preparation of the naphthalene
complex [(η6-C10H8)IrH2(PiPr3)]BF4 (16) (eq 6). More-
Complex 11 can be formed in quantitative yield in
solution by using a moderate excess of ligand. However,
the elemental analyses and the NMR spectra of the
solids isolated from these solutions revealed that sig-
nificant amounts of complex 10 (ca. 20%) precipitate
together with 11. This has been found to occur even at
high aniline concentrations.
Other aromatic molecules such as quinoline and
isoquinoline, which may also coordinate to the metal
either as an arene or through the nitrogen atom, have
been found to prefer N-coordination at any concentra-
tion (eq 5). Thus, treatment of acetone-d6 solutions of 1
over, a similar reaction scheme in CH2Cl2 as solvent,
and under excess of thiophene, allows the preparation
of the compound [(η5-SC4H4)IrH2(PiPr3)]BF4 (17). The
lifetime of this complex in CDCl3 is short, and decom-
position to unidentified species is completed in a few
hours at room temperature. This low stability precluded
the isolation of an analytically pure solid, but still
allowed the spectroscopic characterization of the com-
plex in solution. The proposed η5-coordination of the
thiophene in 17 (eq 6) is inferred from the 13C{1H} NMR
signals of this ligand, which consist of two doublets at
δ 93.52 and 95.57 with J CP coupling constants of 3.7 and
2.4 Hz, respectively. Interestingly, this unusual coor-
dination mode is the only one observed even in the
presence of an excess of thiophene.13
with quinoline produced the compound [IrH2(κ-N,
quinoline)2(OC(CD3)2)(PiPr3)]BF4 (12), as the unique
observable species by NMR. This complex displays two
1
different hydride resonances in the H NMR spectrum,
indicating that the quinoline ligands coordinate one
trans to the phosphine and the other trans to one
hydride ligand. The use of the less sterically demanding
isoquinoline allowed the observation of three different
species, complexes 13, 14, and 15, corresponding re-
spectively to the coordination of one (trans to phos-
phine), two, and three N-donor ligands (eq 5). None of
these quinoline or isoquinoline products could be iso-
lated as an analytically pure solid. In fact, although the
products crystallized from acetone/ether solutions at low
temperature, the crystals so obtained slowly melted into
oils after isolation.
2. Zw itter ion ic Com p lexes. The η6-benzene ligand
of 1 can be readily displaced by the BPh4- anion to give
the zwitterionic complex [Ph3B(η6-Ph)IrH2(PiPr3)] (18)
(eq 7). This compound seems to be much more stable
The synthetic procedure of eq 3 requires the displace-
ment of benzene by a better donating arene ligand. The
relative coordinating capabilities of the different arenes
can be estimated in the equilibrium mixtures generated
by the arene complexes in acetone-d6 (eq 2), by evaluat-
ing to what extent each coordinated arene is displaced
by the solvent to give complex 3. Table 1 shows the
values of the equilibrium constant K, defined as K )
than the cationic species described above and can be also
(13) Precedents for such a coordination mode of thiophene to Rh
and Cr are known; see: (a) Sa´nchez-Delgado, R. A.; Marquez-Silva,
R. L.; Puga, J .; Tiripicchio, A.; Tiripicchio Camellini, M. J . Organomet.
Chem. 1986, 316, C35. (b) Spies, G. H.; Angelici, R. J . J . Am. Chem.
Soc. 1985, 107, 5569.
1
[3][arene]/[η6-arene complex], obtained by H NMR for
various complexes at 297 K and a 3.6 × 10-2 M initial

η6-Arene Complexes of Iridium
Organometallics, Vol. 20, No. 13, 2001 2719
conveniently prepared by displacement of the three
acetonitrile ligands of the complex [IrH2(NCCH3)3-
(PiPr3)]BF411 in CH2Cl2 as solvent. Compound 18, which
still has three arene rings available for coordination,
can be introduced as an arene ligand in the general
synthetic procedure of eq 1. Through this method, and
depending on the ratio [Ir(µ-OMe)(cod)]2/18 employed
in the synthesis, the complexes [Ph2B{(η6-Ph)IrH2-
(PiPr3)}2]BF4 (19), [PhB{(η6-Ph)IrH2(PiPr3)}3](BF4)2 (20),
and [B{(η6-Ph)IrH2(PiPr3)}4](BF4 )3 (21) can be obtained
(eq 8).
F igu r e 1. Molecular structure of the cation of complex 23.
The thermal ellipsoids correspond to 50% probability.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for [(η6-C6H6)Ir (η2-C2H4)(P iP r 3)]BF 4 (23)
Ir-P
2.2933(12)
2.266(5)
2.244(5)
2.288(5)
2.310(5)
2.252(5)
2.301(5)
2.108(5)
2.105(5)
1.430(7)
P-Ir-Ga
133.6(2)
93.3(2)
91.5(2)
130.5(2)
130.9(2)
39.7(2)
Ir-C(1)
Ir-C(2)
Ir-C(3)
Ir-C(4)
Ir-C(5)
Ir-C(6)
Ir-C(16)
Ir-C(17)
C(16)-C(17)
P-Ir-C(16)
P-Ir-C(17)
G-Ir-C(16)
G-Ir-C(17)
C(16)-Ir-C(17)
The identity of these cationic complexes has been
established by NMR spectroscopy, elemental analyses,
and conductivity measurements in acetone. Precedents
for BPh4- coordination to a cationic metal fragment are
relatively abundant,1,4a,14 but, to the best of our knowl-
edge, the simultaneous coordination of this anion to
various metal centers has been reported only for [Rh-
a
G represents the centroid of the C(1)-C(6) ring.
treatment of the Ir(III) dihydride complexes with hy-
drogen acceptors such as alkenes. Indeed, the treatment
of the cationic dihydride complexes 1, 3, and 4 with
ethylene produced ethane and, respectively, the Ir(I)
complexes [(η6-C6H6)Ir(η2-C2H4)(PiPr3)]BF4 (23), [(η6-
C6H5Me)Ir(η2-C2H4)(PiPr3)]BF4 (24), and [(η6-1,3,5-C6H3-
(Me)3)Ir(η2-C2H4)(PiPr3)]BF4 (25) (eq 10). The reaction
(C2H4)2]+ moieties.15 In this case, the BPh4 anion,
-
which is generally considered a noncoordinating anion,
can coordinate up to three rhodium centers. In this
respect, complex 21, which represents the first example
of the η24 coordination of BPh4-, can properly illustrate
the wide range of synthetic possibilities opened up by
the method herein described.
3. H yd r ogen a t ion R ea ct ion s a n d Ir (I) Com -
p lexes. In contrast to that shown in eq 3 for 1-meth-
ylstyrene, the reaction of 1 with styrene did not give
the arene substitution product. In turn, styrene was
hydrogenated to ethylbenzene, which remained coordi-
nated to the final reaction product [(η6-C6H5Et)Ir(η2-
CH2dCHPh)(PiPr3)]BF4 (22) (eq 9).16 This reaction
conditions required for these syntheses were different,
depending on the coordinating abilities of the corre-
sponding arene ligands. Thus, the formation of the
benzene derivative 23 was fast and took place at room
temperature, whereas the synthesis of the mesitylene
complex 25 required treatment with ethylene during 12
h at 313 K. The structure of complex 23 determined by
X-ray diffraction is shown in Figure 1. Important
distances and angles are collected in Table 2.
suggests that Ir(I) arene derivatives are accessible by
In the solid state, the ethylene and benzene ligands
of 23 are disposed parallel to each other. Such arrange-
ment seems to be maintained in solution for the three
(14) (a) Bochmann, M. Angew. Chem., Int. Ed. Engl. 1992, 31, 1181,
and references therein. (b) Oro, L. A.; Pinilla, E.; Tenajas, M. L. J .
Organomet. Chem. 1978, 148, 81.
1
ethylene derivatives 23-25, since they show H NMR
(15) (a) Aresta, M.; Quaranta, E.; Tommasi New J . Chem. 1997, 21,
595. (b) Aresta, M.; Quaranta, E.; Albinati, A. Organometallics 1993,
12, 2032.
patterns indicating nonrotating alkene ligands.17 In
(16) An analogous reaction leading to the cation [Ir(η6-C6H5Et)-
(PPh3)2]+ was reported in ref 5a.
(17) A hindered rotation of the ethylene has been also observed for
the rhodium analogue of 23. See ref 9.

2720 Organometallics, Vol. 20, No. 13, 2001
Torres et al.
Ta ble 3. Hyd r ogen a tion Rea ction s Ca ta lyzed by
Com p lex 1
Exp er im en ta l Section
All experiments were carried out under an atmosphere of
argon by Schlenk techniques. Oxygen-free solvents were
employed throughout. Diethyl ether, THF, and acetone were
distilled immediately prior to use from sodium/benzophenone,
and anhydrous CaCl2, respectively. CDCl3 and CD2Cl2 were
dried from activated molecular sieves. Acetone-d6 (<0.02%
D2O) was purchased from Euriso-top and used as received. The
complex [Ir(µ-OMe)(cod)]2 was prepared by published meth-
ods.19 All other reagents were obtained from common com-
mercial sources unless otherwise stated and were used as
received. IR spectra were recorded as Nujol mulls on polyeth-
ylene sheets using a Nicolet 550 spectrometer. Elemental
analyses were carried out with a Perkin-Elmer 2400 CHNS/O
substrate
substrate/catalyst T (K) time (h) yield
styrene
200
200
500
500
100
298
298
298
323
313
6
10
18
24
24
90
87a
phenylacetylene
2-cyclohexenone
cinnamaldehyde
N-benzylydenaniline
100b
100c
97
a
Conditions: solvent, 1,2-dichloroethane; P(H2) ) 1 atm.
Products: (a) ethylbenzene; (b) cyclohexanone (100%); (c) 3-phenyl-
2-propen-1-ol (55%), 3-phenylpropionaldehyde (45%).
turn, the NMR spectra of compounds 24 and 25 indicate
that rotation of the arenes around the Ir-arene axis is
fast on the NMR time scale.
analyzer. Conductivities were measured in ca. 5 × 10-4
M
solutions using a Philips PW 9501/01 conductometer. NMR
spectra were recorded on a Varian UNITY, a Varian Gemini
The features of complex 22 suggest that the cationic
Ir(I) species are less labile than the corresponding Ir(III)
dihydrides, since the substitution of the η6-ethylbenzene
ligand did not take place in the presence of an excess of
styrene. In agreement with this, the solutions of the Ir(I)
complexes 22-25 in acetone-d6 did not show any detect-
able product of arene substitution by solvent molecules.
Despite this fact, the benzene ligand of 23 could be
1
2000, and a Bruker ARX 300 MHz instrument. H (300 MHz)
and 13C (75.19 MHz) NMR chemical shifts were referenced to
TMS by using known shifts of residual proton or carbon signals
in the solvents. 31P (121 MHz) NMR were measured relative
to external 85% phosphoric acid. NMR coupling constants are
given in Hz. MS data were recorded on a VG Autospec double-
focusing mass spectrometer operating in the positive mode;
ions were produced with the Cs+ gun at ca. 30 kV, and
3-nitrobenzyl alcohol (NBA) was used as the matrix.
-
replaced by hexamethylbenzene or BPh4 in refluxing
acetone, affording the complexes [(η6-C6Me6)Ir(η2-
C2H4)(PiPr3)]BF4 (26) and [Ph3B(η6-Ph)Ir (η2-C2H4)(PiPr3)]
(27), respectively (eq 11). For these strong coordinating
The salts [HPiPr3]BF4 and [HPCy3]BF4 were prepared in
quantitative yields by slow addition of HBF4 solutions (54%
in diethyl ether) to diethyl ether solutions of PiPr3 and PCy3,
respectively. The white solids obtained were filtered, washed
with ether, and dried in vacuo. Data for [HPiPr3]BF4: 1H NMR
(CDCl3, 293 K) δ 1.41 (dd, J HP ) 17.6, J HH ) 7.2, 18H,
PCHCH3), 2.75 (m, 3H, PCHCH3), 5.71 (dq, J HP ) 468.4, J HH
) 4.2, 1H, PH); 31P{1H} NMR (CDCl3, 293 K) δ 42.37 (s). Data
for [HPCy3]BF4: 1H NMR (CDCl3, 293 K) δ 1.1-2.6 (m, 33 H)
5.75 (dq, J HP ) 474.3, J HH ) 3.9, 1H, PH); 31P{1H} NMR
(CDCl3, 293 K) δ 29.20 (s).
P r ep a r a tion of [(η6-C6H6)Ir H2(P iP r 3)]BF 4 (1). A suspen-
sion of [Ir(µ-OMe)(cod)]2 (300 mg, 0.45 mmol) in acetone/
benzene (20:1, 10 mL) was treated with [HPiPr3]BF4 (223 mg,
0.90 mmol), and the resulting orange solution was stirred for
1 h under hydrogen atmosphere (P ) 1 atm). The dark solution
obtained was filtered through Celite and dried in vacuo. After
treatment of the resulting residue with a mixture of diethyl
ether/THF (4:1) a white solid precipitated. The solution was
decanted and the solid washed with ether and dried in vacuo:
arene ligands, this synthetic approach (substitution) led
to higher yields and shorter reaction times than the
treatment of the dihydrides 7 and 18 with ethylene
(hydrogenation).
1
yield 327 mg (70%); IR 2237, 2208 ν(Ir-H); H NMR (CDCl3,
293 K) δ -16.66 (d, J HP ) 27.2, 2H, Ir-H), 1.08 (dd, J HP
)
15.6, J HH ) 7.2, 18H, PCHCH3), 2.14 (m, 3H, PCHCH3), 6.71
(s, 6H, C6H6); 31P{1H} NMR (CDCl3, 293 K) δ 51.23 (s); 13C-
{1H} NMR (CDCl3, 293 K) δ 19.78 (d, J CP ) 1.3, PCHCH3),
28.16 (d, J CP ) 34.4, PCHCH3), 97.99 (d, J CP ) 2.3, C6H6); MS
(FAB+, m/z (%)) 433 (100) [M+]; ΛM (acetone) ) 135 Ω-1 cm2
mol-1 (1:1). Anal. Calcd for C15H29BF4IrP: C, 34.69; H, 5.63.
Found: C, 34.28; H, 5.87.
The above-described synthetic strategies leading to
Ir(I) compounds strongly suggested that the η6-arene
complexes herein described could be efficient hydroge-
nation catalysts. Table 3 summarizes the results of some
representative catalytic reactions performed by 1. The
hydrogenation of carbon-carbon double and triple bonds
catalyzed by 1 took place under very mild conditions,
even for an arene-substituted alkene such as styrene.
R,â-Unsaturated ketones such as 2-hexenone were
selectively reduced at the alkene position, whereas the
hydrogenation of cinnamaldehyde occurred unselec-
tively at both alkene and carbonyl groups. Noteworthily,
imine substrates, which are commonly found to be
rather reluctant to hydrogenation,18 were also efficiently
hydrogenated under mild conditions. Current work in
our laboratory is aimed at the development of chiral
versions of these η6-arene derivatives that may catalyze
the enantioselective reduction of imines.
P r ep a r a tion of [(η6-C6H6)Ir H2(P Cy3)]BF 4 (2). The com-
pound was prepared following the procedure described for 1,
by using [HPCy3]BF4 (330 mg, 0.90 mmol): yield 437 mg (76%);
1
IR 2237, 2208 ν(Ir-H); H NMR (CDCl3, 293 K) δ -16.67 (d,
J HP ) 27.0, 2H, Ir-H), 1.12-1.32 (m, 16H), 1.68-1.98 (m,
17H), 6.68 (s, 6H, C6H6); 31P{1H} NMR (CDCl3, 293 K) δ 38.71
(s); 13C{1H} NMR (CD2Cl2, 293 K) δ 26.52 (s, CH2), 27.32 (d,
J CP ) 11.0, CH2), 30.54 (d, J CP ) 2.5, CH2), 38.55 (d, J CP
)
33.3, PCH), 98.15 (d, J CP ) 2.0, C6H6). Anal. Calcd for C24H41
-
BF4IrP: C, 45.07; H, 6.46. Found: C, 45.55; H, 6.42.
[Ir H2(OC(CD3)2)3(P iP r 3)]BF 4 (3). The NMR spectra of
acetone-d6 (0.5 mL) solutions of complex 1 (26 mg, 0.05 mmol)
at 293 K showed the presence of complex [IrH2(OC(CD3)2)3-
(18) J ames, B. R. Catal. Today 1997, 37, 209.
(19) Uso´n, R.; Oro, L. A.; Cabeza, J . A. Inorg. Synth. 1985, 23, 126.

η6-Arene Complexes of Iridium
Organometallics, Vol. 20, No. 13, 2001 2721
(PiPr3)]BF4 as the major species in solution, in equilibrium with
[(η6-C6H5OH)Ir H2(P iP r 3)]BF 4 (9). Yield: 91 mg (90%); IR
3286 (br) ν(O-H), 2218 (br) ν(Ir-H); 1H NMR (CDCl3, 293 K)
δ -17.64 (d, J HP ) 27.3, 2H, Ir-H), 1.09 (dd, J HP ) 15.5, J HH
1. Data for 3: 1H NMR (acetone-d6, 253 K) δ -31.08 (d, J HP
)
23.7, 2H, Ir-H), 1.15 (dd, J HP ) 13.5, J HH ) 6.8, 18H,
PCHCH3), 2.12 (m, 3H, PCHCH3); 31P{1H} NMR (acetone-d6,
253 K) δ 31.32 (s); 13C{1H} NMR (acetone-d6, 253 K) δ 16.49
(s, PCHCH3), 22.53 (d, J CP ) 35.2, PCHCH3).
) 7.2, 18H, PCHCH3), 2.11 (m, 3H, PCHCH3), 5.97 (t, J HH
)
6.6, 1H, CH), 6.42 (d, J HH ) 6.6, 2H, CH), 6.57 (t, J HH ) 6.6,
2H, CH), 9.10 (br, 1H, OH); 31P{1H} NMR (CDCl3, 293 K) δ
48.38 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.68 (s, PCHCH3),
P r ep a r a tion of Com p lexes 4-9. Solutions of 1 (100 mg,
0.19 mmol) in acetone (5 mL) were treated with a ca. 10-fold
excess of the desired arene and stirred for 1 h. The resulting
solutions were concentrated to ca. 0.5 mL and treated with a
mixture of diethyl ether/THF (4:1) to give white solids, which
were filtered, washed with ether, and dried in vacuo.
[(η6-C6H5Me)Ir H2(P iP r 3)]BF 4 (4). Yield: 91 mg (90%); IR
2245, 2201 ν(Ir-H); 1H NMR (CDCl3, 293 K) δ -16.81 (d, J HP
) 27.3, 2H, Ir-H), 1.07 (dd, J HP ) 15.3, J HH ) 7.2, 18H,
PCHCH3), 2.13 (m, 3H, PCHCH3), 2.64 (s, 3H, CH3), 6.54 (d,
27.35 (d, J CP ) 34.7, PCHCH3), 82.53 (s, CH), 83.22 (d, J CP
3.6, CH), 100.54 (s, CH), 149.39 (s, C); Anal. Calcd for C15H29
BF4IrOP: C, 33.65; H, 5.46. Found: C, 34.00; H, 5.17.
)
-
P r ep a r a tion of [(η6-C6H5(NH2))Ir H2(P iP r 3)]BF 4 (10). The
compound was prepared following the procedure described for
4, by using a stoichiometric amount of aniline (18 µL): yield
1
83 mg (82%); IR 3364, 3259 ν(N-H), 2177, 2226 ν(Ir-H); H
NMR (CDCl3, 293 K) δ -18.25 (d, J HP ) 27.6, 2H, Ir-H), 1.09
(dd, J HP ) 15.0, J HH ) 6.9, 18H, PCHCH3), 2.10 (m, 3H,
PCHCH3), 5.67 (dd, J HH ) 6.9, 5.7, 2H, CH), 5.72 (br, 2H, NH2),
6.09 (d, J HH ) 6.9, 2H, CH), 6.28 (t, J HH ) 5.7, 1H, CH); 31P-
{1H} NMR (CDCl3, 293 K) δ 45.62 (s); 13C{1H} NMR (CDCl3,
293 K) δ 19.47 (d, J CP ) 1.2, PCHCH3), 26.73 (d, J CP ) 34.5,
PCHCH3), 76.14 (s, CH), 99.92 (d, J CP ) 1.7, CH), 129.5 (br,
CH), 146.28 (d, J CP ) 2.4, C); MS (FAB+, m/z (%)) 448 (100)
[M+]. Anal. Calcd for C15H30NBF4IrP: C, 33.71; H, 5.66; N,
2.62 Found: C, 33.88; H, 6.00; N, 2.70.
J HH ) 6.0, 2H, CH), 6.59 (t, J HH ) 6.0, 1H, CH), 6.77 (t, J HH
)
6.0, 2H, CH); 31P{1H} NMR (CDCl3, 293 K) δ 50.93 (s); 13C-
{1H} NMR (CDCl3, 293 K) δ 19.61 (d, J CP ) 1.0, PCHCH3),
20.85 (s, CH3), 27.90 (d, J CP ) 35.1, PCHCH3), 95.53 (d, J CP
)
3.2, CH), 95.62, 100.11 (both s, CH), 116.54 (d, J CP ) 3.0, C);
MS (FAB+, m/z (%)) 447 (100) [M+]. Anal. Calcd for C16H31
-
BF4IrP: C, 36.03; H, 5.86. Found: C, 36.37; H, 5.76.
[(η6-1,3,5-C6H3(Me)3)Ir H2(P iP r 3)]BF 4 (5). Yield: 98 mg
(92%); IR 2220 (br) ν(Ir-H); 1H NMR (CDCl3, 293 K) δ -17.72
(d, J HP ) 28.5, 2H, Ir-H), 1.07 (dd, J HP ) 15.3, J HH ) 6.9,
18H, PCHCH3), 2.03 (m, 3H, PCHCH3), 2.64 (s, 9H, CH3), 6.39
(s, CH); 31P{1H} NMR (CDCl3, 293 K) δ 48.16 (s); 13C{1H} NMR
(CDCl3, 293 K) δ 19.57 (d, J CP ) 1.3, PCHCH3), 20.48 (s, CH3),
26.74 (d, J CP ) 35.0, PCHCH3), 94.30 (d, J CP ) 1.9, CH), 118.41
(d, J CP ) 1.8, C); MS (FAB+, m/z (%)) 475 (100) [M+]; Anal.
Calcd for C18H35BF4IrP: C, 38.50; H, 6.28. Found: C, 38.62;
H, 6.24.
[(η6-1,2,4-C6H3(Me)3)Ir H2(P iP r 3)]BF 4 (6). Yield: 98 mg
(92%); IR 2241, 2210 ν(Ir-H); 1H NMR (CD2Cl2, 293 K) δ
-17.38 (A part of a ABX spin system (X ) 31P) J HP ) 27.9,
J HH ) 5.1, 1H, Ir-H), -17.36 (B part of a ABX spin system (X
[Ir H2(KN-NH2P h )3(P iP r 3)]BF 4 (11). A solution of complex
10 (80 mg, 0.15 mmol) in acetone (5 mL) was treated with an
excess of aniline (100 µL, 1.1 mmol) and stirred for 30 min at
room temperature. The resulting solution was concentrated
to ca. 0.5 mL, and diethyl ether was slowly added to give a
white solid. The solid was filtered, washed with ether, and
dried in vacuo. The NMR spectrum of this material in CDCl3
shows a mixture of complexes 11 and 10 and aniline in a ca.
5:2:1 molar ratio. The elemental analysis of this material was
also consistent with the presence of 20% of the starting
complex 10. Several attempts to obtain analytically pure 11
by using a larger excess of aniline yielded, in all cases,
materials containing 20% of 10. Data for 11: IR 3442, 3344,
1
3292, 3242 ν(N-H), 2206 (br) ν(Ir-H); H NMR (CDCl3, 253
)
31P) J HP ) 27.9, J HH ) 5.1, 1H, Ir-H), 1.11, 1.12 (both dd,
K) δ -26.37 (d, J HP ) 22.5, 2H, Ir-H), 1.13 (dd, J HP ) 13.5,
J HH ) 6.9 Hz, 18H, PCHCH3), 2.07 (m, 3H, PCHCH3), 3.71 (d,
J HP ) 3.0, 2H, NH2Ph), 5.18 (d, J HH ) 10.2, 2H, NH2Ph), 5.75
(d, J HH ) 10.2, 2H, NH2Ph), 5.99 (d, J HH ) 7.8, 2H, CH), 6.84
(t, J HH ) 7.8, 1H, CH), 6.97 (t, J HH ) 7.8, 2H, CH), 7.07 (t,
J HH ) 7.5, 2H, CH), 7.17 (d, J HH ) 7.5, 4H, CH), 7.36 (t, J HH
) 7.5, 4H, CH); 31P{1H} NMR (CDCl3, 253 K) δ 26.65 (s); 13C-
{1H} NMR (CDCl3, 253 K) δ 19.33 (s, PCHCH3), 24.92 (d, J CP
) 32.5, PCHCH3), 119.98, 120.54, 124.20, 124.80, 128.51,
130.12 (all s, CH), 142.47, 145.66 (both s, C).
J HP ) 15.3, J HH ) 6.9, 9H, PCHCH3), 2.11 (m, 3H, PCHCH3),
2.48 (s, 3H, CH3), 2.58 (s, 3H, CH3), 2.60 (s, 3H, CH3), 6.40 (d,
J HH ) 6.0, 1H, CH), 6.44 (s, 1H, CH), 6.60 (d, J HH ) 6.0, 1H,
CH); 31P{1H} NMR (CDCl3, 293 K) δ 49.86 (s); 13C{1H} NMR
(CDCl3, 293 K) δ 18.42, 19.47 (both s, CH3), 19.61, 19.69 (both
d, J CP ) 1.5, PCHCH3), 20.09 (s, CH3), 28.11 (d, J CP ) 34.8,
PCHCH3), 95.13 (d, J CP ) 5.8, CH), 97.11, 101.33 (both s, CH),
100.57 (s, C), 113.69 (d, J CP ) 4.5, C), 114.88 (s, C); MS (FAB+,
m/z (%)) 475 (100) [M+]. Anal. Calcd for C18H35BF4IrP: C,
38.50; H, 6.28. Found: C, 38.66; H, 6.23.
[Ir H2(K-N,qu in olin e)2(OC(CD3)2)(P iP r 3)]BF 4 (12). The
treatment of a solution of complex 1 (26 mg, 0.05 mmol) in
acetone-d6 (0.5 mL) with quinoline (13 mg, 0.1 mmol) produced
C6H6 and complex 12, in quantitative yield. Our attempts to
isolate 12 from its acetone solutions, by addition of diethyl
ether, afforded yellow oils which gave incorrect elemental
analyses. Data for 12: 1H NMR (acetone-d6, 233 K) δ -28.94
(dd, J HP ) 24.0, J HH ) 6.3, 1H, Ir-H), -23.22 (dd, J HP ) 23.4,
J HH ) 6.3, 1H, Ir-H), 0.85 (dd, J HP ) 13.8, J HH ) 7.2, 9H,
PCHCH3), 1.18 (dd, J HP ) 12.6, J HH ) 6.9, 9H, PCHCH3), 2.15
(m, 3H, PCHCH3), 7.12 (dd, J HH ) 8.1, 5.7, 1H, CH), 7.28 (t,
[(η6-C6Me6)Ir H2(P iP r 3)]BF 4 (7). Yield: 101 mg (88%); IR
2220 (br) ν(Ir-H); 1H NMR (CDCl3, 293 K) δ -18.91 (d, J HP
)
29.7, 2H, Ir-H), 1.02 (dd, J HP ) 15.0, J HH ) 7.2, 18H,
PCHCH3), 1.98 (m, 3H, PCHCH3), 2.50 (s, 18H, CH3); 31P{1H}
NMR (CDCl3, 293 K) δ 45.41 (s); 13C{1H} NMR (CDCl3, 293
K) δ 17.65 (s, CH3), 19.50 (d, J CP ) 1.3, PCHCH3), 27.33 (d,
J CP ) 34.3, PCHCH3), 110.29 (d, J CP ) 2.2, C); MS (FAB+,
m/z (%)) 517 (100) [M+]. Anal. Calcd for C21H41BF4IrP: C,
41.79; H, 6.85. Found: C, 41.39; H, 6.73.
[(η6-C6H5(C(Me)dCH2))Ir H2(P iP r 3)]BF 4 (8). Yield: 95 mg
(90%); IR 2222 (br) ν(Ir-H); 1H NMR (CDCl3, 293 K) δ -16.80
(d, J HP ) 27.0, 2H, Ir-H), 1.09 (dd, J HP ) 15.3, J HH ) 6.9,
18H, PCHCH3), 2.09 (d, J HH ) 1.5, 3H, CH3), 2.15 (m, 3H,
PCHCH3), 5.41 (q, J HH ) 1.5, 1H, dCH2), 5.66 (s, 1H, dCH2),
6.75 (m, 3H, CH), 6.84 (m, 2H, CH); 31P{1H} NMR (CDCl3,
293 K) δ 51.07 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.80 (d,
J CP ) 4.3, PCHCH3), 21.73 (s, CH3), 28.44 (d, J CP ) 34.8,
PCHCH3), 92.81 (d, J CP ) 3.2, CH), 98.17 (d, J CP ) 1.9, CH),
99.31 (d, J CP ) 1.2, CH), 118.29 (d, J CP ) 3.3, C), 120.68 (s,
CH2), 137.20 (s, C); MS (FAB+, m/z (%)) 473 (30) [M+]. Anal.
Calcd for C18H33BF4IrP: C, 38.64; H, 5.94. Found: C, 38.33;
H, 6.00.
J HH ) 7.5, 1H, CH), 7.43 (t, J HH ) 7.2, 1H, CH), 7.59 (t, J HH
)
7.8, 1H, CH), 7.80 (t, J HH ) 7.2, 1H, CH), 7.91 (dd, J HH ) 7.8,
5.7, 1H, CH), 7.97 (d, J HH ) 5.7, 1H, CH), 8.12 (m, 2H, CH),
8.42 (d, J HH ) 9.0, 1H, CH), 8.52 (d, J HH ) 8.1, 1H, CH), 8.72
(d, J HH ) 8.1, 1H, CH), 9.61 (d, J HH ) 9.0, 1H, CH), 10.18 (d,
J HH ) 4.5, 1H, CH); 31P{1H} NMR (acetone-d6, 233 K) δ 23.95
(s); 13C{1H} NMR (acetone-d6, 233 K) δ 18.77 (d, J CP ) 1.4,
PCHCH3), 19.74 (s, PCHCH3), 26.11 (d, J CP ) 33.0, PCHCH3),
123.26, 123.69, 127.80, 128.80, 129.27, 129.36, 129.60 (all s,
CH), 130.33 (s, C), 130.84, 131.61 (both s, CH), 132.14 (s, C),
133.48, 139.58, 139.77 (all s, CH), 147.70, 148.56 (both s, C),
154.51, 155.86 (both s, CH).

2722 Organometallics, Vol. 20, No. 13, 2001
Torres et al.
Isoqu in olin e Com p lexes 13-15. A solution of complex 1
(26 mg, 0.05 mmol) in acetone-d6 (0.5 mL) was treated with
isoquinoline (6 mg, 0.05 mmol). The 1H and 31P{1H} NMR
spectra of this solution at room temperature showed several
broad resonances. After cooling this solution at 233 K, the
NMR spectra revealed the presence of a mixture of complexes,
consisting of compounds 1 and 3 (ca. 30% of the reaction
mixture), and two new species. On the basis of their spectro-
scopic data (see below), these new species were identified as
the compounds [IrH2(κ-N,isoquinoline)(OC(CD3)2)2(PiPr3)]BF4
(13) and [IrH2(κ-N,isoquinoline)2(OC(CD3)2)(PiPr3)]BF4 (14).
The addition to the previous solution of six more equivalents
of isoquinoline (39 mg, 0.6 mmol) produced a new mixture of
complexes, consisting of complex 14 together with the new
complex [IrH2(κ-N,isoquinoline)3(PiPr3)]BF4 (15) in about
equimolar amounts. Partial data for 13: 1H NMR (acetone-
temperature. The resulting solution was dried and methanol
added to give a white solid, which was filtered, washed with
methanol, and dried in vacuo: yield 116 mg (91%); IR 2225,
2205 ν(Ir-H); 1H NMR (CDCl3, 293 K) δ -16.78 (d, J HP ) 28.1,
2H, Ir-H), 0.97 (dd, J HP ) 14.9, J HH ) 7.1, 18H, PCHCH3),
1.89 (m, 3H, PCHCH3), 6.03 (t, J HH ) 6.0, 1H, CH), 6.20 (t,
J HH ) 6.0, 2H, CH), 6.45 (d, J HH ) 6.0, 2H, CH), 7.00 (t, J HH
) 6.9, 3H, CH), 7.11 (t, J HH ) 6.9, 6H, CH), 7.44 (d, J HH ) 6.9,
6H, CH); 31P{1H} NMR (CDCl3, 293 K) δ 46.79 (s); 13C{1H}
NMR (CDCl3, 293 K) δ 19.67 (s, PCHCH3), 28.21 (d, J CP ) 34.3,
PCHCH3), 90.99 (s, CH), 98.30 (d, J CP ) 3.5, CH), 99.03,
123.06, 126.18, 135.72 (all s, CH). Anal. Calcd for C33H43
BIrP: C, 58.83; H, 6.43. Found: C, 58.82; H, 6.89.
-
P r ep a r a tion of [P h 2B{(η6-P h )Ir H2(P iP r 3)}2]BF 4 (19). A
suspension of [Ir(µ-OMe)(cod)]2 (100 mg, 0.15 mmol) in acetone
(5 mL) was treated with [HPiPr3]BF4 (74.3 mg, 0.30 mmol) and
with complex 18 (202 mg, 0.3 mmol). The resulting orange
solution was stirred under hydrogen atmosphere (P ) 1 atm)
for 1 h, and the resulting brown solution was filtered through
Celite and dried in vacuo. Treatment of the residue with a
mixture of diethyl ether/THF (4:1) produced a white solid,
which was filtered, washed with ether, and dried in vacuo:
yield 271 mg (82%); IR 2210 (br) ν(Ir-H); 1H NMR (CDCl3,
d6, 233 K) δ -29.58 (d, J HP ) 21.3, 2H, Ir-H), 1.07 (dd, J HP
)
13.8, J HH ) 6.9, 18H, PCHCH3), 2.10 (m, 3H, PCHCH3), 8.27
(d, J HH ) 7.8, 1H, CH), 8.47 (dd, J HH ) 6.4, 2.2, 1H, CH), 9.44
(d, J HH ) 3.0, 1H, CH); 31P{1H} NMR (acetone-d6, 233 K) δ
28.32 (s). Partial data for 14: 1H NMR (acetone-d6, 233 K) δ
-29.31 (dd, J HP ) 22.2, J HH ) 7.8, 1H, Ir-H), -22.35 (dd, J HP
) 22.2, J HH ) 7.8, 1H, Ir-H), 1.05 (dd, J HP ) 14.7, J HH ) 6.9,
9H, PCHCH3), 1.19 (dd, J HP ) 13.6, J HH ) 7.2, 9H, PCHCH3),
2.14 (m, 3H, PCHCH3), 7.72 (t, J HH ) 7.2 Hz, 1H, CH), 8.37
(dd, J HH ) 6.3, 2.2 Hz, 1H, CH), 8.96 (br, 1H, CH), 9.51 (d,
J HH ) 3.0 Hz, 1H, CH), 9.93 (br, 1H, CH); 31P{1H} NMR
(acetone-d6, 233 K) δ 24.46 (s). Partial data for 15: 1H NMR
(acetone-d6, 233 K) δ -22.36 (d, J HP ) 23.4, 2H, Ir-H), 1.00
(dd, J HP ) 13.8, J HH ) 6.9, 18H, PCHCH3), 2.27 (m, 3H,
PCHCH3), 8.64 (t, J HH ) 7.8, 1H, CH), 8.15 (dd, J HH ) 6.3,
7.4, 2H, CH), 8.30 (d, J HH ) 7.4, 2H, CH), 8.93 (dd, J HH ) 6.3,
293 K) δ -16.79 (d, J HP ) 27.9, 4H, Ir-H), 0.97 (dd, J HP
)
15.0, J HH ) 7.2, 36H, PCHCH3), 1.98 (m, 6H, PCHCH3), 6.36
(t, J HH ) 6.0, 2H, CH), 6.44 (t, J HH ) 6.0, 4H, CH), 6.52 (d,
J HH ) 6.0, 4H, CH), 7.03 (t, J HH ) 6.9, 2H, CH), 7.12 (t, J HH
)
6.9, 4H, CH), 7.43 (d, J HH ) 6.9, 4H, CH); 31P{1H} NMR
(CDCl3, 293 K) δ 48.59 (s); 13C{1H} NMR (CDCl3, 293 K) δ
19.69 (s, PCHCH3), 28.21 (d, J CP ) 34.8, PCHCH3), 93.98 (s,
CH), 98.04 (d, J CP ) 3.1, CH), 99.80, 124.59, 126.77, 135.35
(all s, CH); MS (FAB+, m/z (%)) 1027 (100) [M+]; ΛM (acetone)
) 124 Ω-1 cm2 mol-1 (1:1). Anal. Calcd for C42H66B2F4Ir2P2:
C, 45.24; H, 5.97. Found: C, 45.73; H, 6.06.
2.2 Hz, 1H, CH), 8.97 (d, J HH ) 6.3, 2H, CH), 9.85 (d, J HH
)
3.0, 1H, CH), 10.02 (br, 2H, CH); 31P{1H} NMR (acetone-d6,
233 K) δ 24.94 (s).
P r ep a r a tion of [P h B{(η6-P h )Ir H2(P iP r 3)}3](BF 4)2 (20).
The compound was prepared following the procedure described
for 19, by using 50 mg (0.07 mmol) of [Ir(µ-OMe)(cod)]2, 37.1
mg (0.15 mmol) of [HPiPr3]BF4, and 202 mg (0.3 mmol) of
complex 18: yield 182 mg (78%); IR 2210 (br) ν(Ir-H); 1H NMR
(CDCl3, 293 K) δ -16.71 (d, J HP ) 27.3, 6H, Ir-H), 1.00 (dd,
J HP ) 15.0, J HH ) 7.2, 54H, PCHCH3), 2.10 (m, 9H, PCHCH3),
6.48 (m, 3H, CH), 6.60 (m, 12H, CH), 7.12 (m, 3H, CH), 7.51
(m, 2H, CH); 31P{1H} NMR (CDCl3, 293 K) δ 49.49 (s); 13C-
{1H} NMR (CDCl3, 293 K) δ 19.66 (d, J CP ) 1.4, PCHCH3),
P r ep a r a tion of [(η6-C10H8)Ir H2(P iP r 3)]BF 4 (16). The
compound was prepared following the procedure described for
1, by using [Ir(µ-OMe)(cod)]2 (100 mg, 0.15 mmol), [HPiPr3]-
BF4 (74 mg, 0.30 mmol), naphthalene (300 mg, 2.3 mmol), and
acetone (5 mL): yield 113 mg (66%); IR 2220 (br) ν(Ir-H); 1H
NMR (CDCl3, 293 K) δ -19.65 (d, J HP ) 25.5, 2H, Ir-H), 0.81
(dd, J HP ) 15.3, J HH ) 7.2, 18H, PCHCH3), 1.86 (m, 3H,
PCHCH3), 6.66 (A part of an AA′BB′X spin system (X ) 31P),
J AB ) 5.70, J AB′ ) 1.2, J AA′ ) 3.5, J AX ) 0.6, 2H, CH), 7.44 (B
part of an AA′BB′X spin system, J BB′ ) J BX ) 0, 2H, CH), 7.75
(m, 2H, CH), 7.86 (m, 2H, CH); 31P{1H} NMR (CDCl3, 293 K)
28.14 (d, J CP ) 35.0, PCHCH3), 95.93 (s, CH), 98.51 (d, J CP
)
3.0, CH), 100.00, 125.89, 127.44, 134.96 (all s, CH); MS (FAB+,
m/z (%)) 1469 (25) [M(BF4)+], 691 (50) [M2+]; ΛM (acetone) )
241 Ω-1 cm2 mol-1 (2:1). Anal. Calcd for C51H89B3F8Ir3P3: C,
39.36; H, 5.76. Found: C, 38.95; H, 5.99.
δ 49.52 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.24 (d, J CP
1.3, PCHCH3), 27.57 (d, J CP ) 34.5, PCHCH3), 93.87 (d, J CP
)
)
2.8, CH), 94.43 (d, J CP ) 2.2, CH), 111.90 (s, C), 127.95, 132.61
(both s, CH). Anal. Calcd for C19H33BF4IrP: C, 39.93; H, 5.82.
Found: C, 40.12; H, 5.88.
P r ep a r a tion of [B{(η6-P h )Ir H2(P iP r 3)}4](BF 4)3 (21). The
compound was prepared following the procedure described for
19, by using 50 mg (0.07 mmol) of [Ir(µ-OMe)(cod)]2, 37.1 mg
(0.15 mmol) of [HPiPr3]BF4, and 303 mg (0.45 mmol) of complex
18: yield 258 mg (72%); IR 2210 (br) ν(Ir-H); 1H NMR (CDCl3,
[(η5-SC4H4)Ir H2(P iP r 3)]BF 4 (17). A solution of [Ir(µ-OMe)-
(cod)]2 (100 mg, 0.15 mmol) in CH2Cl2/thiophene (20:1, 5 mL)
was treated with [HPiPr3]BF4 (74 mg, 0.30 mmol), and the
resulting orange solution was stirred for 30 min under
hydrogen atmosphere (P ) 1 atm). The dark solution obtained
was filtered through Celite and dried in vacuo. The resulting
residue was then washed with diethyl ether to give a beige
oil. The spectroscopic analysis of this oil in CDCl3 (see below)
shows the presence of complex 17 and traces of thiophene. All
our attempts to crystallize 17 from its freshly prepared
solutions were unsuccessful. Data for 17: 1H NMR (CDCl3,
293 K) δ -16.51 (d, J HP ) 27.0, 8H, Ir-H), 1.04 (dd, J HP
)
15.3, J HH ) 7.2, 72H, PCHCH3), 2.12 (m, 12H, PCHCH3), 6.45
(t, J HH ) 6.0, 4H, CH), 6.71 (t, J HH ) 7.2, 18H, CH), 6.78 (br,
18H, CH); 31P{1H} NMR (CDCl3, 293 K) δ 49.95 (s); 13C{1H}
NMR (CDCl3, 293 K) δ 19.70 (d, J CP ) 1.4, PCHCH3), 28.28
(d, J CP ) 35.0, PCHCH3), 96.85 (s, CH), 98.95 (br, CH), 99.98
(s, CH); ΛM (CH3NO2) ) 268 Ω-1 cm2 mol-1 (3:1). Anal. Calcd
for C60H112B4F12Ir4P4: C, 36.10; H, 5.65. Found: C, 36.40; H,
5.49.
293 K) δ -17.88 (d, J HP ) 25.2, 2H, Ir-H), 1.07 (dd, J HP
)
P r epar ation of [(η6-C6H5Et)Ir (η2-CH2dCHP h )(P iP r 3)]BF4
(22). A solution of 1 (100 mg, 0.19 mmol) in acetone (5 mL)
was treated with styrene (ca. 500 µL) and stirred for 30 min
at room temperature. The resulting solution was concentrated,
and diethyl ether was added to give a pale yellow solid, which
was filtered, washed with ether, and dried in vacuo: yield 100
15.3, J HH ) 7.2, 18H, PCHCH3), 2.15 (m, 3H, PCHCH3), 6.57
(m, 2H, CH), 6.94 (m, 2H, CH); 31P{1H} NMR (CDCl3, 293 K)
δ 52.53 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.67 (d, J CP
1.0, PCHCH3), 27.53 (d, J CP ) 34.3, PCHCH3), 93.52 (d, J CP
3.7, CH), 95.57 (d, J CP ) 2.4, CH).
)
)
P r ep a r a tion of [P h 3B(η6-P h )Ir H2(P iP r 3)] (18). A solution
of 1 (100 mg, 0.19 mmol) in acetone (5 mL) was treated with
NaBPh4 (130 mg, 0.40 mmol) and stirred for 30 min at room
1
mg (81%); H NMR (CDCl3, 293 K) δ 1.09 (t, J HH ) 7.5, 3H,
CH3), 1.15, 1.18 (both dd, J HP ) 14.4, J HH ) 7.8, 9H, PCHCH3),

η6-Arene Complexes of Iridium
Organometallics, Vol. 20, No. 13, 2001 2723
Ta ble 4. Cr ysta llogr a p h ic Da ta for 23
1.88 (ddd, J HH ) 8.4, 3.6, J HP ) 5.1, 1H, dCH2), 2.00 (m, 3H,
PCHCH3), 2.16, 2.17 (both q, J HH ) 7.5, 1H, CH2), 3.14 (dd,
formula
C17H31BF4IrP
545.40
J HH ) 10.8, 3.6, 1H, dCH2), 3.75 (ddd, J HH ) 10.8, 8.4, J HP
6.0, 1H, dCH), 5.26 (d, J HH ) 6.3, 1H, CH), 5.49 (td, J HH
6.3, 1.2, 1H, CH), 5.71 (d, J HH ) 6.3, 1H, CH), 6.41 (td, J HH
6.3, 1.2, 1H, CH), 6.78 (t, J HH ) 6.3, 1H, CH), 7.02 (tt, J HH
)
)
)
)
fw
temp, K
173(2)
cryst syst
space group
monoclinic
P21/c (no. 14)
4
7.2, 1.2, 1H, CH), 7.07, 7.22 (both m, 2H, CH); 31P{1H} NMR
(CDCl3, 293 K) δ 20.41 (s); 13C{1H} NMR (CDCl3, 293 K) δ
14.12 (s, CH3), 17.38 (s, CH2), 19.32, 19.44 (both s, PCHCH3),
24.27 (d, J CP ) 30.7, PCHCH3), 25.66 (s, dCH2), 41.35 (s, d
Z
a, Å
b, Å
c, Å
8.3723(7)
17.1013(15)
13.8467(12)
91.913(2)
1981.4(3)
1064
1.828
6.851
1.89-27.0
12 459
4323 (Rint ) 0.0379)
3516
0.6102, 0.2901
4323/21/227
0.934
â, deg
CH), 93.58 (d, J CP ) 4.2, CH), 93.79 (s, CH), 94.83 (d, J CP
)
V, Å3
3.0, CH), 95.39 (d, J CP ) 1.0, CH), 100.61 (d, J CP ) 1.0, CH),
123.31 (d, J CP ) 2.7, C), 126.14, 126.82, 128.77 (all s, CH),
144.48 (s, C); MS (FAB+, m/z (%)) 563 (20) [M+]. Anal. Calcd
for C25H39BF4IrP: C, 46.22; H, 6.05. Found: C, 46.06; H, 5.77.
P r ep a r a tion of [(η6-C6H6)Ir (η2-C2H4)(P iP r 3)]BF 4 (23).
Ethylene was bubbled through a solution of 1 (100 mg, 0.19
mmol) in acetone (5 mL) for 30 min at room temperature. The
resulting solution was concentrated, and diethyl ether was
added to give a pale yellow solid, which was filtered, washed
F(000)
F(calcd), g cm-3
µ(Mo KR), mm-1
θ range data collec, deg
no. of collected reflns
no. of unique reflns
no. of obsd reflns [I g 2σ(I)]
min., max. transmn factors
no. of data/restraints/params
GOFa
1
R1(F), wR2(F2) [obsd]b
R1(F), wR2(F2) [all data]
0.0338, 0.0616
0.0437, 0.0639
with ether, and dried in vacuo: yield 88 mg (85%); H NMR
(CDCl3, 293 K) δ 1.60 (dd, J HP ) 14.1, J HH ) 7.2, 18H,
PCHCH3), 2.07 (A-part of a AA′MM′X spin system (X ) 31P),
J AA′ ) 8.5, J AM ) 11.3, J AM′ ) 2.3, J AX ) 4.9, 2H, CH2), 2.39
(m, 3H, PCHCH3), 3.32 (M-part of a AA′MM′X spin system (X
GOF ) (∑[w(Fo - Fc2)2]/(n - p))1/2, where n and p are the
a
2
b
number of data and parameters. R1 ) ∑||Fo| - |Fc||/∑|Fo|,wR2
)
(∑[w(Fo - Fc2)2]/∑[w(Fo2)2])1/2 where w ) 1/[σ2(Fo2) + (0.0196P)2]
2
)
31P), J MM′ ) 8.5, J MX ) 0.8, 2H, CH2), 7.01 (s, 6H, C6H6);
and P ) [Max(0,Fo2) + 2Fc2]/3.
31P{1H} NMR (CDCl3, 293 K) δ 22.43 (s); 13C{1H} NMR (CDCl3,
293 K) δ 19.31 (d, J CP ) 1.4, PCHCH3), 19.53 (d, J CP ) 2.2,
C2H4), 24.43 (d, J CP ) 32.2, PCHCH3), 95.89 (d, J CP ) 2.2,
C6H6); MS (FAB+, m/z (%)) 459 (100) [M+]; ΛM (acetone) )
129 Ω-1 cm2 mol-1 (1:1). Anal. Calcd for C17H31BF4IrP: C,
37.37; H, 5.90. Found: C, 37.02; H, 5.55.
(dd, J HP ) 13.8, J HH ) 7.2, 18H, PCHCH3), 1.43 (A-part of a
AA′BB′X spin system (X ) 31P), J AA′ ) 7.5, J AB ) 9.9, J AB′
)
2.1, J AX ) 0, 2H, CH2), 1.70 (B-part of a AA′BB′X spin system
(X ) 31P), J BB′ ) 7.5, J BX ) 2.7, 2H, CH2), 1.82 (m, 3H,
PCHCH3), 2.19 (s, 18H, CH3); 31P{1H} NMR (CDCl3, 293 K) δ
17.83 (s); 13C{1H} NMR (CDCl3, 293 K) δ 16.33 (s, CH3), 19.38
(d, J CP ) 0.9, PCHCH3), 23.53 (d, J CP ) 30.2, PCHCH3), 23.85
(d, J CP ) 1.2, C2H4), 107.95 (d, J CP ) 1.6, C); MS (FAB+, m/z
(%)) 543 (75) [M+]; ΛM (acetone) ) 100 Ω-1 cm2 mol-1 (1:1).
Anal. Calcd for C23H43BF4IrP: C, 43.88; H, 6.88. Found: C,
43.40; H, 7.01.
P r ep a r a tion of [(η6-C6H5Me)Ir (η2-C2H4)(P iP r 3)]BF 4 (24).
The compound was prepared following the procedure described
for 23, but starting from complex 4 (100 mg, 0.19 mmol). The
reaction time under ethylene atmosphere was 3 h: yield 76
mg (73%); 1H NMR (CDCl3, 293 K) δ 1.16 (dd, J HP ) 14.4, J HH
) 7.2, 18H, PCHCH3), 1.74 (A-part of a AA′BB′X spin system
(X ) 31P), J AA′ ) 8.5, J AB ) 11.2, J AB′ ) 2.1, J AX ) 4.2, 2H,
CH2), 1.98 (m, 3H, PCHCH3), 2.34 (s, 3H, CH3), 3.32 (B-part
of a AA′BB′X spin system (X ) 31P), J BB′ ) 8.5, J BX ) 1.8, 2H,
CH2), 6.17 (d, J HH ) 6.3, 2H, CH), 6.64 (dd, J HH ) 6.3, 6.0,
2H, CH), 6.72 (t, J HH ) 6.0, 1H, CH); 31P{1H} NMR (CDCl3,
293 K) δ 22.43 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.26 (d,
J CP ) 1.3, PCHCH3), 21.96 (d, J CP ) 2.0, C2H4), 24.35 (d, J CP
) 30.7, PCHCH3), 94.30 (d, J CP ) 3.2, CH), 94.88, 96.50 (both
s, CH), 113.12 (d, J CP ) 3.0, C); MS (FAB+, m/z (%)) 473 (100)
[M+]; Anal. Calcd for C18H33BF4IrP: C, 38.64; H, 5.94. Found:
C, 38.34; H, 5.76.
P r ep a r a tion of [P h 3B(η6-P h )Ir (η2-C2H4)(P iP r 3)] (27). A
solution of 23 (100 mg, 0.18 mmol) in acetone (5 mL) was
treated with NaBPh4 (65 mg, 0.20 mmol) and stirred for 8 h
at 323 K. The resulting suspension was taken to dryness and
the residue treated with methanol, to give a white solid. The
solid was filtered off, washed with methanol, and dried in
vacuo: yield 103 mg (82%); 1H NMR (CDCl3, 293 K) δ 1.11
(dd, J HP ) 13.5, J HH ) 6.9, 18H, PCHCH3), 1.41 (A-part of a
AA′BB′X spin system (X ) 31P), J AA′ ) 8.5, J AB ) 10.9, J AB′
)
2.2, J AX ) 4.8, 2H, CH2), 1.84 (m, 3H, PCHCH3), 2.31 (B-part
of a AA′BB′X spin system (X ) 31P), J BB′ ) 8.5, J BX ) 0.9, 2H,
CH2), 5.96 (t, J HH ) 6.3, 2H, CH), 6.08 (d, J HH ) 6.3, 2H, CH),
6.47 (t, J HH ) 6.3, 1H, CH), 7.02 (tt, J HH ) 7.2, 2.1, 3H, CH),
7.12 (t, J HH ) 7.2, 6H, CH), 7.33 (brd, J HH ) 7.2, 6H, CH);
31P{1H} NMR (CDCl3, 293 K) δ 18.01 (s); 13C{1H} NMR (CDCl3,
293 K) δ 18.80 (s, C2H4), 19.23 (s, PCHCH3), 24.21 (d, J CP
30.7, PCHCH3), 91.57, 94.22 (both s, CH), 95.86 (d, J CP ) 4.1,
CH), 123.35, 126.14, 136.16 (all s, CH). Anal. Calcd for C35H45
BIrP: C, 60.08; H, 6.48. Found: C, 59.98; H, 6.75.
P r ep a r a tion of [(η6-1,3,5-C6H3(Me)3)Ir (η2-C2H4)(P iP r 3)]-
BF 4 (25). The compound was prepared following the procedure
described for 23, but starting from complex 5 (150 mg, 0.27
mmol). In this case, the reaction with ethylene required 12 h
at 313 K: yield 125 mg (80%); 1H NMR (CDCl3, 293 K) δ 1.15
(dd, J HP ) 14.1, J HH ) 7.2, 18H, PCHCH3), 1.82-1.90 (m, 5H,
CH2 and PCHCH3), 2.22 (B-part of a AA′BB′X spin system (X
)
-
)
31P), J AB ) 11.1, J AB′ ) 2.2, J BB′ ) 8.1, J BX ) 0.9, 2H, CH2),
2.47 (s, 9H, CH3), 6.10 (s, 3H, CH); 31P{1H} NMR (CDCl3, 293
K) δ 19.69 (s); 13C{1H} NMR (CDCl3, 293 K) δ 19.28 (d, J CP
Ca ta lytic Rea ction s. The reactions were carried out in a
conventional glass hydrogenation apparatus equipped with a
shaker. The reaction solvent was 1,2-dichloroethane (8 mL),
the hydrogen pressure was set to 1 atm, and 1 mmol of
substrate was used in each reaction. The course of the catalytic
reactions was followed by GC in a HP 5890 series II gas
chromatograph with a HP-Innowax cross-linked poly(ethylene
glycol) column (30 m × 0.53 mm × 1.0 µm).
)
1.4, PCHCH3), 19.47 (s, CH3), 22.68 (d, J CP ) 30.9, PCHCH3),
23.58 (d, J CP ) 2.3, C2H4), 94.41 (d, J CP ) 2.3, CH), 114.35 (d,
J CP ) 2.3, C); MS (FAB+, m/z (%)) 501 (100) [M+]. Anal. Calcd
for C20H37BF4IrP: C, 40.84; H, 6.53. Found: C, 40.77; H, 6.38.
P r ep a r a tion of [(η6-C6Me6)Ir (η2-C2H4)(P iP r 3)]BF 4 (26).
A solution of 23 (200 mg, 0.37 mmol) in acetone (5 mL) was
treated with hexamethylbenzene (450 mg, 2.8 mmol) and
stirred for 48 h at room temperature. The resulting solution
was concentrated to ca. 0.5 mL, and then diethyl ether was
added, causing the precipitation of a white solid. The solid was
separated by decantation, washed with ether, and dried in
vacuo: yield 145 mg (63%); 1H NMR (CDCl3, 293 K) δ 1.09
X-r a y Str u ctu r a l Deter m in a tion of Com p ou n d 23. A
summary of crystal data and refinement parameters for 23 is
given in Table 4. Suitable crystals for X-ray diffraction were
obtained by slow diffusion of n-hexane into a concentrated
solution of 23 in acetone. The selected crystal was a pale yellow
irregular block of approximate dimensions 0.24 × 0.09 × 0.08

2724 Organometallics, Vol. 20, No. 13, 2001
Torres et al.
mm. Diffraction data were recorded at 173 K on a Bruker
SMART APEX diffractometer with a CCD area detector, using
graphite-monochromated Mo KR radiation (λ ) 0.71073 Å).
Cell constants were obtained from the least-squares refine-
ment of three-dimensional centroids of 3837 reflections in the
range 4.76° e 2θ e 52.28°. A total of 1771 frames of data were
collected with scan widths of 0.3° in ω and exposure times of
10 s/frame. Data were corrected for absorption with the
SADABS routine, based on the method of Blessing,20 inte-
grated in the Bruker SAINT program.21
The structure was solved by the Patterson method
(SHELXS97)22 and difference Fourier techniques and refined
by full-matrix least-squares on F2 (SHELXL97),22 first with
isotropic and then with anisotropic displacement parameters
for the non-hydrogen atoms. The hydrogen atoms were intro-
duced in calculated positions or localized in a difference Fourier
map (for the olefinic ligand) and refined riding on the corre-
sponding carbon atoms. Scattering factors, corrected for
anomalous dispersion, were as implemented in the refinement
program.22
Ack n ow led gm en t. We thank the Direccio´n General
de Investigacio´n Cient´ıfica y Te´cnica for the support of
this research (Project No. PB94-1186). C.O. thanks the
Alexander von Humboldt Foundation for a Feodor
Lynen Fellowship. G.P. thanks Programa CYTED for a
fellowship. Our special gratitude goes to Prof. J airton
Dupont for his support of this work.
Su p p or tin g In for m a tion Ava ila ble: Full listings of
crystallographic data, complete atomic coordinates, isotropic
and anisotropic thermal parameters, and bond distances and
angles for complex 23. This material is available free of charge
via the Internet at http://pubs.acs.org.
(20) Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33.
(21) SAINT+, version 6.01; Bruker AXS, Inc., Madison, WI, 2000.
(22) Sheldrick, G. M. SHELX97; University of Go¨ttingen, Germany,
1997.
OM010024U