Acetylacetonato(phosphane)iridium complexes: Synthesis and catalytic activity in the cyclization of alkynoic acids

Article abstract of DOI:10.1002/ejic.201000655

The iridium complex [Ir(acac)(η²-coe)₂] (1) has been easily prepared by the addition of Tl(acac) to a suspension of [Ir(μ-Cl)(η²-coe)₂]₂ in hexane. Complex 1 has been characterized fully including an

Full text of DOI:10.1002/ejic.201000655

FULL PAPER
DOI: 10.1002/ejic.201000655
Acetylacetonato(phosphane)iridium Complexes: Synthesis and Catalytic
Activity in the Cyclization of Alkynoic Acids
Michael J. Geier,[a] Christopher M. Vogels,[a] Andreas Decken,[b] and Stephen A. Westcott*[a]
Dedicated to the memory of Keith Fagnou
Keywords: Iridium / Phosphane ligands / Cyclization / Lactones
The iridium complex [Ir(acac)(η2-coe)2] (1) has been easily
prepared by the addition of Tl(acac) to a suspension of [Ir(µ-
Cl)(η2-coe)2]2 in hexane. Complex 1 has been characterized
fully including an X-ray diffraction study. It is moderately
stable and is a useful precursor to a number of different ace-
tylacetonato(phosphane)iridium complexes via addition of
monodentate and bidentate phosphanes. Reactions pro-
ceeded at room temperature to give high yields of the desired
square planar phosphane complexes [Ir(acac)(P)] (2: P = 2
PPh3, 3: P = 2 PMePh2, 4: P = dppm, 5: P = dppe, 6: P = dppp,
7: P = dppb, 8: P = dppf, 9: P = dcpe) except for those involv-
ing dppe, which gave a complicated mixture of products.
Complex [Ir(acac)(dppe)] (5) was prepared in a microwave
reactor at 125 °C. All complexes prepared in this study were
efficient in the intramolecular catalyzed cyclization of
4-pentynoic acid to give exclusive formation of the exocyclic
γ-methylene-γ-butyrolactone. Complex 1 was found to be the
most active and selective catalyst precursor for the intramo-
lecular cyclization of both 4-pentynoic acid and 5-hexynoic
acid.
found that bulky monodentate phosphite/rhodium systems
are highly active and selective hydroformylation catalysts
for a wide range of substrates, including di- and trisubsti-
tuted alkenes.[3l] Acetylacetonatorhodium complexes also
play an important role in the field of metal-catalyzed cycli-
zation or cycloaddition reactions. For example, Ojima and
co-workers have reported that derivatives of Rh(acac)-
(CO)2 catalyze the silane-initiated cyclization of enediynes
to give the corresponding biscyclopentyl products in excel-
lent yields (Scheme 1).[4]
Introduction
Transition metals have been employed as catalysts for in-
dustrial processes as early as the 19th century[1] and are cur-
rently used in the manufacture of bulk chemicals such as n-
butanal (hydroformylation) and acetic acid (carbonylation),
as well as in the generation of fine or specialty chemicals.
While the development of novel catalysts is the subject of
intense research, acetylacetonato(acac)-metal complexes
have always played a predominant role in this economically
and environmentally important area of chemistry. For in-
stance, one of the areas where β-diketonato-metal com-
plexes have made significant contributions in the last few
years has been in the catalyzed hydroformylation reaction.[2]
Although RhH(CO)(PPh3)3 is widely recognized as one of
the most versatile catalysts for the hydroformylation reac-
tion, the ease of synthesis, stability and ability to fine tune
the electronic and steric environments around the metal
center by the addition of ligands makes complexes of the
type Rh(acac)(CO)2 and Rh(acac)(H2C=CH2)2 valuable
precatalysts for this reaction.[3] Most of the work in this
area has involved reactions using modified phosphane and
phosphite derivatives. Indeed, van Leeuwen and co-workers
Scheme 1. The acetylacetonatorhodium cyclization of enediynes.
While acetylacetonato(phosphane)rhodium complexes
have been well studied in terms of synthesis, structure and
activities, it is somewhat surprising that the analogous
chemistry and potential catalytic properties of the iridium
complexes have not yet been fully explored. The iridium
complex [Ir(acac)(CO)2] has been used to generate other
organometallic complexes or clusters[5] and its oxidative ad-
dition chemistry with perfluoroalkyl iodides has been re-
cently investigated in an elegant study by Hughes and co-
workers.[6] However, very little is known about acetylace-
[a] Department of Chemistry and Biochemistry,
Mount Allison University,
Sackville, NB E4L 1G8, Canada
Fax: +1-506-364-2313
E-mail: swestcott@mta.ca
[b] Department of Chemistry, University of New Brunswick,
Fredericton, NB E3B 5A3, Canada
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Acetylacetonato(phosphane)iridium Complexes
tonatoiridium complexes containing phosphane ligands.[7]
While Esteruelas[7b–7d] and Werner[7e,7f] have carried out
Therefore we have decided to investigate the synthesis and elaborate studies on [Ir(acac)(η2-H2C=CH2)(PCy3)] (Cy =
characterization of these species and examine their poten- cyclohexyl) and [Ir(acac)(η2-H2C=CH2)(PiPr3)], respec-
tial to act as precatalysts in the cyclization of alkynoic acids, tively, much less is known about complexes containing two
the results of which are reported within.
monodentate phosphane ligands or bidentate phosphanes.
For instance, Eisenberg reported the synthesis of [Ir(acac)-
(PPh3)2] (2) in 1984 but little is known about its chemistry
and catalytic abilities.[7a] In a more recent study, Hughes
and co-workers have found that [Ir(acac)(PMe3)2] reacts at
room temperature with 1,2,3-triphenyl-3-vinylcyclopropene
to give an unusual 1,2,4-triphenyliridacyclohexadiene com-
plex containing cis-phosphane ligands.[7g] In this study we
have made 2 via the addition of two equivalents of PPh3 to
1 in high yield (94%). Analogous reactions with methyl-
diphenylphosphane gave the corresponding complex [Ir-
(acac)(PMePh2)2] (3) in yields of 83%. Complex 3 has been
characterized by a number of physical methods including
Results and Discussion
Synthesis and Characterization of Iridium Complexes
Although a new synthetic route to the ethylene com-
pound [Ir(acac)(η2-H2C=CH2)2] has recently been pre-
pared,[8] relatively low yields (45%) and thermal instability
at room temperature does not make this compound an ideal
starting material for substitution reactions. We therefore de-
cided to prepare the iridium complex [Ir(acac)(η2-coe)2] (1)
(coe = cis-cyclooctene = C8H14) by the addition of Tl(acac)
to a hexane suspension of [Ir(µ-Cl)(η2-coe)2]2.[9] Complex 1
was prepared in good yields at room temperature (18 h) and
crystals of 1 suitable for a single-crystal X-ray diffraction
study were grown from hexane at room temperature, the
structure of which is shown in Figure 1. The iridium oxygen
bond lengths of Ir(1)–O(1) 2.0598(19) and Ir(1)–O(2)
2.0521(19) Å are similar to those observed in the ethylene
complex [Ir(acac)(η2-H2C=CH2)2] and other acetylacetona-
toiridium complexes.[10] Likewise, the C=C double bonds of
the cyclooctene group are slightly elongated at C(6)–C(7)
1.414(4) and C(14)–C(15) 1.422(4) Å compared to
1.404(4) Å seen in [Ir(acac)(η2-H2C=CH2)2].[8] The iso-
structural rhodium analog Rh(acac)(η2-coe)2 also displayed
somewhat shorter alkene bonds at 1.402(3) and
1.405(3) Å,[11] which may signify a slight increase in back-
bonding into the alkene π* ligands on replacing rhodium
with iridium.
multinuclear NMR spectroscopy. As expected, a doublet is
1
observed in the H NMR spectra at δ = 1.71 ppm (JHP
=
8.4 Hz) for the phosphane methyl group and the 31P{1H}
NMR spectra shows a singlet at δ = –1.6 ppm. The forma-
tion of 3 has also been confirmed by a single-crystal X-ray
diffraction study (Figure 2). The molecular structure of 3
has a center of symmetry where the Ir(1)–P(1) distance of
2.2061(5) Å is typical of those observed in other iridium-
PMePh2 structures.[12] Likewise, the bond lengths within the
acac ring are similar to those reported previously[10]
(Table 1).
Figure 2. Molecular structure of 3 with ellipsoids drawn at 50%
probability level. Hydrogen atoms omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–O(1) 2.0678(14), Ir(1)–P(1)
2.2061(5), P(1)–C(10) 1.831(2), P(1)–C(16) 1.832(2), P(1)–C(4)
1.8334(19), O(1)–C(1) 1.277(2); O(1)#1–Ir(1)–O(1) 88.08(8), O(1)
#1–Ir(1)–P(1) 175.04(4), O(1)–Ir(1)–P(1) 87.92(4), O(1)#1–Ir(1)–
P(1)#1 87.92(4), O(1)–Ir(1)–P(1)#1175.04(4), P(1)–Ir(1)–P(1)
#196.22(3).
The iridium complexes 4–9 were prepared readily by the
addition of the diphosphane to solutions of 1 in toluene or
THF (Scheme 2). Once again all new compounds have been
characterized fully, and spectroscopic data is consistent
with analogous acetylacetonatoiridium derivatives[10] and
the corresponding acetylacetonato(phosphane)rhodium
compounds.[13] X-ray diffraction studies were also carried
out for complexes 4 (Figure 3, a), 6 (Figure 3, b), and 9
(Figure 4). The iridium atoms assume a slightly distorted
square planar configuration with Ir–P distances of
Figure 1. Molecular structure of 1 with ellipsoids drawn at 50%
probability level. Hydrogen atoms omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–O(1) 2.0598(19), Ir(1)–O(2)
2.0521(19), Ir(1)–C(14) 2.117(3), Ir(1)–C(7) 2.120(2), Ir(1)–C(6)
2.125(3), Ir(1)–C(15) 2.129(3), C(6)–C(7) 1.414(4), C(14)–C(15)
1.422(4); O(2)–Ir(1)–O(1) 88.31(8), O(2)–Ir(1)–C(14) 90.28(9),
O(1)–Ir(1)–C(14) 166.47(9), O(2)–Ir(1)–C(7) 153.82(10), O(1)–
Ir(1)–C(7) 88.42(9), C(14)–Ir(1)–C(7) 86.92(10), O(2)–Ir(1)–C(6)
167.14(10), O(1)–Ir(1)–C(6) 91.04(9), C(14)–Ir(1)–C(6) 93.29(10),
C(7)–Ir(1)–C(6) 38.91(10), O(2)–Ir(1)–C(15) 88.21(9), O(1)–Ir(1)–
C(15) 154.15(10), C(14)–Ir(1)–C(15) 39.13(10).
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M. J. Geier, C. M. Vogels, A. Decken, S. A. Westcott
FULL PAPER
Table 1. Crystallographic data collection parameters for 1, 3, 4, 6, 9, and 10.
Complex
Formula
1
3
4
6
9
10
C21H35IrO2
C31H33IrO2P2
C30H29IrO2P2··0.5 C38H39IrO2P2
C6H14
718.76
C31H55IrO2P2
[C52H48IrP4]
Cl··2CHCl3
1263.17
Formula mass
Crystal dimen-
sions /mm3
Crystal system
Space group
Z
511.69
691.71
781.83
713.89
0.425ϫ0.35ϫ0.275 0.50ϫ0.35ϫ0.28 0.40ϫ0.40ϫ0.15 0.30ϫ0.20ϫ0.17 0.45ϫ0.25ϫ0.25 0.50ϫ0.40ϫ0.20
triclinic
P1
2
monoclinic
C2/c
4
monoclinic
P21/n
4
monoclinic
P21/c
4
monoclinic
C2/c
8
triclinic
¯
¯
P1
1
a /Å
b /Å
c /Å
α /°
β /°
γ /°
10.2741(13)
11.1866(15)
11.3708(15)
103.956(1)
113.087(1)
108.973(1)
1029.8(2)
1.650
19.575(2)
10.9709(10)
14.9089(16)
90
121.361(2)
90
2734.1(5)
1.680
173(1)
17.373(2)
11.2795(12)
17.460(3)
90
119.630(2)
90
2974.0(7)
1.605
173(1)
19.7378(16)
12.0941(10)
13.9907(12)
90
97.4220(10)
90
3311.8(5)
1.568
173(1)
32.632(5)
11.4377(16)
17.174(3)
90
92.075(3)
90
6405.9(16)
1.480
223(1)
10.6165(8)
12.0141(9)
12.2891(9)
117.314(1)
102.331(1)
95.470(1)
1326.38(17)
1.581
Volume /Å3
Dcalcd. /mgm–3
T /K
173(1)
173(1)
Radiation
Mo-Kα (λ =
0.71073 Å)
6.493
Mo-Kα (λ =
0.71073 Å)
5.027
Mo-Kα (λ =
0.71073 Å)
4.625
Mo-Kα (λ =
0.71073 Å)
4.160
Mo-Kα (λ =
0.71073 Å)
4.293
Mo-Kα (λ =
0.71073 Å)
3.026
µ /mm–1
Total reflections 7128
No. of variables 219
9275
166
2.22 to 27.49
1.121
0.0149
20286
318
1.35 to 27.50
0.996
0.0249
22829
390
1.04 to 27.49
1.112
0.0196
21990
327
1.89 to 27.50
1.056
0.0189
9079
331
1.95 to 27.50
1.057
0.0247
θ (0)
2.13 to 27.49
1.085
0.0178
GoF on F2
[a]
R1 [IϾ2σ(I)]
[b]
wR2 (all data) 0.0469
0.0377
0.0542
0.0495
0.0487
0.0636
Largest diff
1.083 and –1.320
0.698 and –0.717 1.339 and –0.620 0.755 and –0.391 0.935 and –0.279 2.331 and –0.869
peak & hole /Å
2
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = {Σ[w(Fo – Fc2)2]/Σ[Fo4]}1/2, where w = 1/[σ2(Fo2) + (0.0274 * P)2 + (0.6485 * P)] (1), 1/[σ2(Fo2) +
(0.0186 * P)2 + (1.9667 * P)] (3), 1/[σ2(Fo2) + (0.0281 * P)2] (4), 1/[σ2(Fo2) + (0.0713 * P)2 + (2.0278 * P)] (6), 1/[σ2(Fo2) + (0.0239 * P)2 +
(3.7666 * P)] (9) and 1/[σ2(Fo2) + (0.0440 * P)2 + (0.5245 * P)] (10); where P = [max (Fo2, 0) + 2*Fc2]/3.
2.1890(9), 2.1764(7) Å (4), 2.1823(6), 2.1831(7) Å (6), and phane)] via the displacement of the diolefin from [(η5-
2.1763(6), 2.1799(7) Å for the cyclohexyl derivative 9. As C9H7)Ir(η4-cod)] (where cod = 1,5-cyclooctadiene) or [(η5-
with the analogous rhodium complexes,[14] iridium com- C9H7)Ir(η2-coe)2] with chiral diphosphanes.[15] Complexes
pounds 4–9 appear to be unstable in chlorinated solvents of the type [Ir(diphosphane)2]+ were said to be the major
as C–Cl bond activation to give a mixture of products was species formed in these reactions, although the nature of
observed after 24 h at room temperature.
the anion was not discussed in any significant detail. Also
relevant is the study by Leitner and co-workers who found
that addition of diphosphanes to Rh(hfacac)(η4-cod)
(hfacac = hexafluoroacetylacetonato anion) or Rh(hfacac)-
(diphosphane) afforded complexes of the type [Rh(diphos-
phane)2][hfacac].[16] To confirm that we were generating
[Ir(dppe)2]+ in this work, we independently prepared the
chloride derivative [[Ir(dppe)2]Cl] (10). Spectroscopic data
are consistent with known analogs and confirms the forma-
tion of these cations in solution.[17] A single-crystal X-ray
diffraction study on 10 (Figure 5) was carried out and
shows the iridium atom in a slightly distorted square planar
configuration with Ir–P distances of 2.2988(6) and
2.3003(7) Å. Although typical for other [Ir(diphosphane)2]+
cations,[18] these bonds are slightly elongated with respect
to the acac complexes in accord with the trans directing
series. The coordinated acac species 5 could be prepared in
high yields, however, but only at higher temperatures or
using a microwave reactor.[19] Interestingly, this type of re-
activity was specific only for the dppe case as all other di-
phosphanes proceeded smoothly over 18 h to give the corre-
sponding neutral products in high yields, without the obser-
vance of any of the cationic species.
Scheme 2. Synthesis of acetylacetonatoiridium complexes contain-
ing bidentate phosphanes.
Of singular interest in this study were attempts to gener-
ate the diphos derivative [Ir(acac)(dppe)] {5, dppe = 1,2-
bis(diphenylphosphanyl)ethane}, which gave a mixture of
products when reactions were carried out at room tempera-
ture. One of the products identified from this mixture ap-
pears to be the cationic species [Ir(dppe)2]+, where the
counterion is presumably acac–. Similar reactivity has been
reported during attempts to make [(η5-C9H7)Ir(diphos-
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Acetylacetonato(phosphane)iridium Complexes
Figure 4. Molecular structure of 9 with ellipsoids drawn at 50%
probability level. Hydrogen atoms omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–O(2) 2.0761(16), Ir(1)–O(1)
2.0856(17), Ir(1)–P(1) 2.1763(6), Ir(1)–P(2) 2.1799(7); O(2)–Ir(1)–
O(1) 89.01(7), O(2)–Ir(1)–P(1) 172.97(5), O(1)–Ir(1)–P(1) 92.45(5),
O(2)–Ir(1)–P(2) 92.70(5), O(1)–Ir(1)–P(2) 172.51(5), P(1)–Ir(1)–
P(2) 86.74(2).
Figure 3. (a) Molecular structure of 4 with ellipsoids drawn at 50%
probability level. Hydrogen atoms omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–O(2) 2.070(2), Ir(1)–O(1)
2.075(2), Ir(1)–P(2) 2.1764(7), Ir(1)–P(1) 2.1890(9); O(2)–Ir(1)–
O(1) 88.68(8), O(2)–Ir(1)–P(2) 98.13(6), O(1)–Ir(1)–P(2) 170.93(7),
O(2)–Ir(1)–P(1) 171.35(6), O(1)–Ir(1)–P(1) 99.96(7), P(2)–Ir(1)–
P(1) 73.31(3). (b) Molecular structure of 6 with ellipsoids drawn at
50% probability level. Hydrogen atoms omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–O(2) 2.0682(18), Ir(1)–O(1)
2.0759(17), Ir(1)–P(1) 2.1823(6), Ir(1)–P(2) 2.1831(7); O(2)–Ir(1)–
O(1) 88.56(7), O(2)–Ir(1)–P(1) 87.91(5), O(1)–Ir(1)–P(1) 175.88(5),
O(2)–Ir(1)–P(2) 176.79(5), O(1)–Ir(1)–P(2) 89.33(5), P(1)–Ir(1)–
P(2) 94.10(3).
Figure 5. Molecular structure of the cation in 10 with ellipsoids
drawn at 50% probability level. Hydrogen atoms omitted for clar-
ity. Selected bond lengths [Å] and angles [°]: Ir(1)–P(1) 2.2988(6),
Ir(1)–P(2) 2.3003(7); P(1)–Ir(1)–P(1)#1 180.0, P(1)–Ir(1)–P(2)
82.38(2), P(1)#1-Ir(1)–P(2) 97.62(2).
lactone. With this in mind, we have investigated compounds
1–9 for their ability to catalyze this potentially useful trans-
formation (Scheme 3).
Catalyzed Intramolecular Hydroalkoxylation
Catalysis with acetylacetonatoiridium compounds re-
mains a largely unexplored area,[20] but recent studies have
found that these complexes show promise in a number of
organic transformations including the [2+2] cycloaddition
of oxabicyclic alkenes with terminal alkynes.[20a] Related
studies have also shown that iridium complexes can be used
to effectively catalyze the synthesis of five- and six-mem-
bered oxygen-containing heterocycles from a number of un-
saturated organic substrates.[21] The resulting heterocycles
Scheme 3. The iridium catalyzed intramolecular cyclization of 4-
pentynoic acid.
Preliminary studies of 4-pentynoic acid were performed
are prevalent in natural products and have numerous appli- on an NMR scale using CD3CN as a solvent and
cations in pharmaceuticals, agricultural, fragrance and flav- 5 mol-% catalyst at room temperature. The reaction pro-
our chemicals. Elegant studies by Messerle and co-workers gress was monitored by 1H NMR spectroscopy and conver-
have found that cationic[22a] and neutral[22b] rhodium and sion of 4-pentynoic acid was determined by integration of
iridium compounds can be used for the intramolecular cy- product resonances relative to substrate resonances and 1,2-
clization of 4-pentynoic acid to give γ-methylene-γ-butyro- dimethoxybenzene as an internal standard. In all cases
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M. J. Geier, C. M. Vogels, A. Decken, S. A. Westcott
FULL PAPER
complete conversion of the unsaturated substrate to give perature after only two hours.[21a] In this study, we have re-
the desired γ-methylene-γ-butyrolactone A was observed. A examined the three representative iridium compounds and
more in depth study with representative iridium complexes found that only the bis cyclooctene complex 1 was efficient
1, 3 and 7 showed that reactions employing the cyclooctene in this transformation at room temperature (Figure 7). Al-
precursor 1 were complete within 12 hours (Figure 6). though taking 72 h for complete conversion to take place,
Slightly shorter reaction times occurred with the mono- this reaction was remarkably selective in the formation of
dentate phosphane complex 3 compared to the bidentate the desired six-membered ring lactone C. Once again, reac-
system 7, where addition of phosphane appears to retard tion rates could be improved by carrying out the cycliza-
reaction rates. Indeed, reactions using 7 and an additional tions at elevated temperatures (T = 100 °C, t = 30 min).
equivalent of dppb ligand proceeded with only 25% conver- Unfortunately, the diphosphane complex 3 failed to com-
sion at room temperature after 24 hours. Upon completion plete the cyclization of 5-hexynoic acid at room or elevated
of catalysis, no free phosphane was observed in solution by temperatures as degradation of the iridium complex was
31P NMR spectroscopy. Although these rates are somewhat observed eventually. Although catalyst decomposition was
slower than those observed by Messerle and co-workers not observed in reactions using 7, rates were remarkably
using RhI/IrI indolyl complexes, these results show promise slow at room temperature and 144 h was needed to com-
as the formation of the six-membered lactone ring B, as an plete the reaction.
unwanted side product, was not observed to any extent in
reactions carried out at room temperature. A remarkable
study by Valerga and co-workers has shown that complete
reversal of regioselectivity in favour of the endocyclic lac-
tone B can be achieved in reactions using σ-enynyl complex
[TpRu{C(Ph)=C(Ph)CϵCPh}(PMeiPr2)] {Tp = hydrotris-
(pyrazolyl)borate(1–)} as the catalyst precursor.[21g]
Scheme 4. The iridium catalyzed intramolecular cyclization of 5-
hexynoic acid.
Figure 6. Cyclization of 4-pentynoic acid using iridium complexes
1, 3, and 7 at room temperature. Reactions monitored by 1H NMR
Figure 7. Cyclization of 5-hexynoic acid using iridium complexes
1, 3, and 7 at room temperature. Reactions monitored by 1H NMR
spectroscopy and product conversion confirmed by GC/MS.
spectroscopy and product conversion confirmed by GC/MS.
Selectivity in favour of the five-membered ring (Ͼ99%)
was also observed in reactions conducted at elevated tem-
peratures (T = 100 °C, t = 20 min) using a catalytic amount
Conclusions
of 1. Reactions with catalyst precursors 3 and 7 proceeded
at 100 °C (t = 1 h) and gave only minor amounts of the six- moderately stable precursor to a number of different acetyl-
membered product B (Ͻ2%). acetonato(phosphane)iridium complexes via addition of
We have found that complex [Ir(acac)(η2-coe)2] (1) is a
To expand the scope of these reactions, we then decided monodentate and bidentate phosphanes. Reactions proceed
to investigate analogous cyclizations of 5-hexynoic acid (see at room temperature to give high yields of the desired
Scheme 4). Reactions with this substrate are notoriously square-planar complexes except for those involving dppe,
difficult and long reaction times are usually required. For which gave a complicated mixture of products. Complex [Ir-
example, reactions using a cationic rhodium dicarbonyl (acac)(dppe)] (5) was prepared in a microwave reactor at
complex containing N-heterocyclic carbenes as a catalyst 125 °C. Although all complexes were efficient in the intra-
precursor does not exceed conversions of 80% after 8 days molecular catalyzed cyclization of 4-pentynoic acid to give
at 50 °C.[22a] Slightly better results have been achieved using exclusive formation of the exocyclic γ-methylene-γ-butyro-
rhodium trinuclear complexes with tris-carbene ligands, lactone, reactions employing complex 1 gave the best rates.
which gave 90% of the desired 6-methylidenetetrahydro-2- Complex 1 could also be used at elevated temperatures to
pyrone C after 5 days at 50 °C.[21c] A more recent study give the desired products in 20 min at 100 °C and was found
using catalytic amounts of AuCl/K2CO3 reported that the to be the best precatalyst for the cyclization of 5-hexynoic
desired lactone could be generated selectively at room tem- acid. Further studies will expand the catalytic potential of
4606
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 4602–4610

Acetylacetonato(phosphane)iridium Complexes
13C{1H} δ = 182.0 [C(O)], 135.6 (t, JCP = 23.0 Hz, CP), 132.4 (t,
JCP = 5.6 Hz, Ar), 129.2 (Ar), 127.9 (t, JCP = 4.6 Hz, Ar), 101.7
[C(H)=C], 55.3 (t, JCP = 30.2 Hz, PCH2), 27.9 (CH3); 31P{1H} δ =
–56.5. C30H29IrO2P2 (675.79): calcd. C 53.32, H 4.33; found C
53.02, H 4.58.
these iridium complexes and the scope of these cyclization
reactions, and the results of which will be published in due
course.
[Ir(acac)(dppe)] (5): To
a 5 mL THF solution of [Ir(acac)-
Experimental Section
(η2-coe)2] (200 mg, 0.39 mmol) was added a 5 mL THF solution of
1,2-bis(diphenylphosphanyl)ethane (155 mg, 0.39 mmol). The solu-
tion was heated (T = 125 °C) under microwave conditions at 200 W
for 1 h. Following removal of solvent the resulting orange solid was
washed with hexane (3ϫ5 mL) and collected by suction filtration
to afford 5; yield 223 mg (83%), m.p. 142–146 °C (decomp.). NMR
General: Reagents and solvents were purchased from Aldrich
Chemicals and used as received. [Ir(µ-Cl)(η2-coe)2]2
and [Ir-
[23]
(acac)(η2-coe)2] (1)[9] were prepared by known procedures. NMR
spectra were recorded on a JEOL JNM-GSX270 FT NMR (1H
270 MHz; 13C 68 MHz; 31P 109 MHz) spectrometer. Chemical
shifts (δ) are reported in ppm [relative to residual solvent peaks (1H
and 13C) or external H3PO4 (31P)] and coupling constants (J) in
Hz. Multiplicities are reported as singlet (s), doublet (d), triplet (t),
quintet (quint), multiplet (m), broad (br), and overlapping (ov).
Decomposition and melting points were determined using a Mel-
Temp apparatus and are uncorrected. A CEM Discover microwave
reactor was employed for all microwave reactions and the reaction
temperature was monitored by an internal IR pyrometer. Septum
sealed, thick-walled reaction tubes were used in order to withstand
the elevated pressures inherent with microwave reactions. Elemental
analyses were performed by Guelph Chemical Laboratories
(Guelph, ON). All reactions were performed under dinitrogen.
1
spectroscopic data (in C6D6): H δ = 8.05 (m, 8 H, Ar), 7.12–7.00
(ov m, 12 H, Ar), 5.39 [s, 1 H, C(H)=C], 1.84 (d, JHP = 14.6 Hz, 4
H, PCH2), 1.64 (s, 6 H, CH3); 13C{1H} δ = 181.7 [C(O)], 136.5 (d,
JCP = 50.3 Hz, CP), 133.1 (t, JCP = 4.6 Hz, Ar), 128.9 (Ar), 127.9
(t, JCP = 4.6 Hz, Ar), 101.7 [C(H)=C], 29.6 (m, PCH2), 27.8 (CH3);
31P{1H} δ = 33.9. C31H31IrO2P2 (689.82): calcd. C 53.97, H 4.54;
found C 54.16, H 4.88.
[Ir(acac)(dppp)] (6): To a 5 mL toluene solution of [Ir(acac)-
(η2-coe)2] (200 mg, 0.39 mmol) was added a 3 mL toluene solution
of 1,3-bis(diphenylphosphanyl)propane (161 mg, 0.39 mmol). The
reaction was allowed to proceed for 18 h at which point solvent
was removed under vacuum and the residual solid was triturated
with hexane (5 mL) to afford 6 as an orange solid; yield 210 mg
(77%), m.p. 97–100 °C (decomp.). NMR spectroscopic data (in
Synthesis of [Ir(acac)(PPh3)2] (2): Complex 2 was prepared by
modification of a known procedure.[7g] To a 5 mL toluene solution
of [Ir(acac)(η2-coe)2] (200 mg, 0.39 mmol) was added a 3 mL tolu-
ene solution of triphenylphosphane (206 mg, 0.79 mmol). The reac-
tion was allowed to proceed for 18 h at which point an orange-
yellow precipitate was collected by suction filtration and washed
with cold hexane (1 mL) to afford 2; yield 300 mg (94%), m.p. 195–
199 °C (decomp.). NMR spectroscopic data (in C6D6): 1H δ = 7.84
(m, 12 H, Ar), 6.97–6.87 (ov m, 18 H, Ar), 5.32 [s, 1 H, C(H)=C],
1.28 (s, 6 H, CH3); 13C{1H} δ = 181.2 [C(O)], 135.8 (m, CP), 135.2
(t, JCP = 5.1 Hz, Ar), 128.5 (Ar), 126.8 (t, JCP = 5.1 Hz, Ar), 101.6
[C(H)=C], 26.9 (CH3); 31P{1H} δ = 19.3. C41H37IrO2P2 (816.00):
calcd. C 60.34, H 4.58; found C 60.61, H 4.85.
1
C6D6): H δ = 7.86 (m, 8 H, Ar), 7.12–7.02 (ov m, 12 H, Ar), 5.24
[s, 1 H, C(H)=C], 2.27 (m, 4 H, PCH2), 1.61 (m, 2 H, PCH2CH2),
1.39 (s, 6 H, CH3); 13C{1H} δ = 181.3 [C(O)], 136.0 (m, CP), 133.7
(t, JCP = 4.6 Hz, Ar), 128.6 (Ar), 127.2 (t, JCP = 4.6 Hz, Ar), 101.4
[C(H)=C], 28.4 (m, PCH2), 27.3 (CH3), 20.4 (PCH2CH2); 31P{1H}
δ = –0.3. C32H33IrO2P2 (703.85): calcd. C 54.60, H 4.74; found C
54.91, H 5.05.
[Ir(acac)(dppb)] (7): To a 2 mL toluene solution of [Ir(acac)-
(η2-coe)2] (125 mg, 0.24 mmol) was added a 3 mL toluene solution
of 1,4-bis(diphenylphosphanyl)butane (104 mg, 0.24 mmol). The
reaction was allowed to proceed for 18 h at which point solvent
was removed under vacuum and the resulting solid was washed
with hexane (2ϫ1 mL) to afford 7 as an orange solid; yield 150 mg
(87%), m.p. 117–120 °C (decomp.). NMR spectroscopic data (in
[Ir(acac)(PMePh2)2] (3): To a 5 mL toluene solution of [Ir-
(acac)(η2-coe)2] (200 mg, 0.39 mmol) was added a 3 mL toluene
solution of methyldiphenylphosphane (156 mg, 0.78 mmol). The
reaction was allowed to proceed for 18 h at which point the volume
of solvent was reduced by one half under vacuum and the solution
stored at –30 °C. The resulting orange-yellow precipitate was col-
lected by suction filtration and washed with cold hexane (1 mL) to
afford 3; yield 225 mg (83%), m.p. 177–180 °C. NMR spectroscopic
1
C6D6): H δ = 7.84 (m, 8 H, Ar), 7.15–7.10 (ov m, 12 H, Ar), 5.20
[s, 1 H, C(H)=C], 2.30 (br. m, 4 H, PCH2), 1.79 (br. m, 4 H,
PCH2CH2), 1.34 (s, 6 H, CH3); 13C{1H} δ = 181.0 [C(O)], 138.0
(m, CP), 133.7 (t, JCP = 4.6 Hz, Ar), 128.5 (Ar), 127.2 (t, JCP
=
1
4.6 Hz, Ar), 101.4 [C(H)=C], 29.6 (m, PCH2), 27.1 (CH3), 23.9
(PCH2CH2); 31P{1H} δ = 10.8. C33H35IrO2P2 (717.88): calcd. C
55.21, H 4.92; found C 55.44, H 5.15.
data (in C6D6): H δ = 7.82 (m, 8 H, Ar), 7.08–7.03 (ov m, 12 H,
Ar), 5.30 [s, 1 H, C(H)=C], 1.71 (d, JHP = 8.4 Hz, 6 H, PCH3),
1.41 (s, 6 H, acac-CH3); 13C{1H} δ = 181.2 [C(O)], 137.9 (m, CP),
133.2 (t, JCP = 5.1 Hz, Ar), 128.5 (Ar), 127.2 (t, JCP = 5.1 Hz, Ar),
101.7 [C(H)=C], 27.1 (acac-CH3), 16.6 (m, PCH3); 31P{1H} δ =
–1.6. C31H33IrO2P2 (691.86): calcd. C 53.81, H 4.82; found C 53.96,
H 5.01.
[Ir(acac)(dppf)] (8): To
a 2 mL THF solution of [Ir(acac)-
(η2-coe)2] (100 mg, 0.20 mmol) was added a 3 mL THF solution of
1,1Ј-bis(diphenylphosphanyl)ferrocene (110 mg, 0.20 mmol). The
reaction was allowed to proceed for 18 h at which point a yellow
precipitate was collected by suction filtration and washed with hex-
ane (2ϫ1 mL) to afford 8 as a yellow solid; yield 120 mg (71%),
m.p. 215–218 °C (decomp.). NMR spectroscopic data (in C6D6):
1H δ = 8.08 (m, 8 H, Ar), 7.25–7.03 (ov m, 12 H, Ar), 5.17 [s, 1 H,
C(H)=C], 4.32 (d, JHP = 1.7 Hz, 4 H, Cp), 3.86 (s, 4 H, Cp), 1.29
(s, 6 H, CH3); 13C{1H} δ = 181.3 [C(O)], 137.4 (m, PAr), 135.1 (t,
JCP = 5.1 Hz, Ar), 128.8 (Ar), 126.9 (t, JCP = 5.1 Hz, Ar), 101.5
[C(H)=C], 80.2 (m, PCp), 75.4 (t, JCP = 4.6 Hz, Cp), 71.6 (Cp),
26.9 (CH3); 31P{1H} δ = 13.4. C39H35FeIrO2P2 (845.74): calcd. C
55.38, H 4.18; found C 55.11, H 4.13.
[Ir(acac)(dppm)] (4): To a 5 mL toluene solution of [Ir(acac)-
(η2-coe)2] (200 mg, 0.39 mmol) was added a 3 mL toluene solution
of bis(diphenylphosphanyl)methane (150 mg, 0.39 mmol). The re-
action was allowed to proceed for 18 h at which point hexane
(5 mL) was added and the solution stored at –30 °C. The resulting
orange-yellow precipitate was collected by suction filtration and
washed with cold hexane (1 mL) to afford 4; yield 230 mg (87%),
m.p. 95–99 °C (decomp.). NMR spectroscopic data (in C6D6): H
δ = 8.02 (m, 8 H, Ar), 7.13–6.94 (ov m, 12 H, Ar), 5.44 [s, 1 H,
C(H)=C], 3.96 (t, JHP = 10.4 Hz, 2 H, PCH2), 1.73 (s, 6 H, CH3);
1
Eur. J. Inorg. Chem. 2010, 4602–4610
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4607

M. J. Geier, C. M. Vogels, A. Decken, S. A. Westcott
FULL PAPER
[Ir(acac)(dcpe)] (9): To a 3 mL toluene solution of [Ir(acac)-
(η2-coe)2] (200 mg, 0.39 mmol) was added a 4 mL toluene solution
of 1,2-bis(dicyclohexylphosphanyl)ethane (165 mg, 0.39 mmol).
The reaction was allowed to proceed for 18 h at which point solvent
was removed under vacuum and the resulting solid washed with
cold hexane (1 mL) to afford 9 as a yellow solid; yield 200 mg
(72%), m.p. 146–150 °C (decomp.). NMR spectroscopic data (in
Acknowledgments
Thanks are gratefully extended to the Canada Research Chairs Pro-
gram, Canadian Foundation for Innovation-Atlantic Innovation
Fund, Natural Science and Engineering Research Council of
Canada (NSERC), and Mount Allison University for financial sup-
port. M. J. G. thanks NSERC for an Undergraduate Student Re-
search Award and we also thank Roger Smith and Dan Durant for
expert technical assistance and anonymous reviewers for helpful
suggestions.
1
C6D6): H δ = 5.36 [s, 1 H, C(H)=C], 2.46 (br. d, JHP = 12.1 Hz, 4
H, PCH2), 1.91–1.59 (ov m, 30 H, Cy), 1.69 (s, 6 H, CH3), 1.29–
1.11 (ov m, 14 H, Cy); 13C{1H} δ = 180.1 [C(O)], 101.6 [C(H)=C],
35.1 (d, JCP = 31.7 Hz, PCH), 29.0 (d, JCP = 11.3 Hz, PCH2), 28.0
(CH3), 27.3 (app t, JCP = 9.7 Hz), 26.7, 24.3 (dd, JCP = 34.8,
8.7 Hz); 31P{1H} δ = 53.7. C31H55IrO2P2 (714.06): calcd. C 52.14,
H 7.78; found C 51.97, H 7.81.
[1] a) Homogeneous Catalysis (Eds.: G. W. Parshall, S. D. Ittel), 2nd
ed., Wiley, New York, 1992; b) Catalytic Asymmetric Synthesis
(Ed.: I. Ojima), 2nd ed., Wiley-VCH, New York, 2000; c) Ap-
plied Homogeneous Catalysis with Organometallic Compounds
(Eds.: B. Cornils, W. A. Herrmann), Wiley-VCH, Weinheim,
2002; d) R. H. Crabtree, The Organometallic Chemistry of the
Transition Metals, 4th ed., Wiley-Interscience, New York,
2005.
[2] a) Rhodium-Catalyzed Hydroformylation (Eds.: P. W. N. M.
van Leeuwen, C. Claver), Kluwer Academic, Dordrecht, 2000;
b) C. Claver, M. Diéguez, O. Pàmies, S. Castillón, Top. Or-
ganomet. Chem. 2006, 18, 35–64; c) L. Damoense, M. Datt, M.
Green, C. Steenkamp, Coord. Chem. Rev. 2004, 248, 2393–
2407; d) M. Beller, J. Seayad, A. Tillack, H. Jiao, Angew. Chem.
Int. Ed. 2004, 43, 3368–3398; e) J.-C. Wasike, S. J. Obrey, R. T.
Baker, G. Bazan, Chem. Rev. 2005, 105, 1001–1020; f) M. L.
Clarke, Curr. Org. Chem. 2005, 9, 701–718.
[[Ir(dppe)2]Cl] (10): To a 5 mL toluene solution of [Ir(acac)-
(η2-coe)2] (100 mg, 0.20 mmol) was added a 3 mL toluene solution
of 1,2-bis(diphenylphosphanyl)ethane (159 mg, 0.40 mmol) and
NBu4Cl (56 mg, 0.20 mmol). The reaction was allowed to proceed
for 18 h at which point an orange solid was collected by suction
filtration and washed with cold hexane (1 mL) to afford 10; yield
75 mg (37%), m.p. 250–256 °C (decomp.). NMR spectroscopic data
(in CDCl3): 1H δ = 7.30 (m, 16 H, Ar), 7.24–7.14 (ov m, 24 H, Ar),
2.09 (t, JHP = 9.4 Hz, 8 H, PCH2); 13C{1H} δ = 133.4 (t, JCP
=
2.6 Hz, Ar), 131.2 (Ar), 130.9 (m, CP), 128.5 (t, JCP = 2.6 Hz, Ar),
29.6 (app quint, JCP = 12.8 Hz, PCH2); 31P{1H} δ = 50.7.
·
C52H48ClIrP4 0.5C7H8 (1070.95): calcd. C 62.24, H 4.90; found C
62.59, H 4.72.
[3] a) N. Sakai, S. Mano, K. Nozaki, J. Am. Chem. Soc. 1993, 115,
7033–7034; b) G. D. Cuny, S. L. Buchwald, J. Am. Chem. Soc.
1993, 115, 2066–2068; c) E. A. Karakhanov, Y. S. Kardasheva,
E. A. Runova, D. A. Sakharov, M. V. Terenina, Petrol. Chem.
2006, 46, 264–268; d) R. P. J. Bronger, J. P. Bermon, J. Herwig,
P. C. J. Kamer, P. W. N. M. van Leeuwen, Adv. Synth. Catal.
2004, 346, 789–799; e) O. Artyushin, I. Odinets, E. Goryunov,
I. Fedyanin, K. Lyssenko, T. Mastryukova, G.-V. Röschen-
thaler, T. Kégl, G. Keglevichm, L. Kollár, J. Organomet. Chem.
2006, 691, 5547–5559; f) E. Schwab, S. Mecking, Organometal-
lics 2005, 24, 3758–3763; g) A. M. Trzeciak, P. Psˇteˇpnicˇka, E.
Mieczyn´ska, J. J. Ziołkowski, J. Organomet. Chem. 2005, 690,
3260–3267; h) M. Rosales, A. González, B. González, C. Mora-
tinos, H. Pérez, J. Urdaneta, R. A. Sánchez-Delgado, J. Or-
ganomet. Chem. 2005, 690, 3095–3098; i) M. T. Reetz, X. Li,
Angew. Chem. Int. Ed. 2005, 44, 2962–2964; j) E. Zuidema,
E. Daura-Oller, J. J. Carbó, C. Bo, P. W. N. M. van Leeuwen,
Organometallics 2007, 26, 2234–2242; k) C. J. Cobley, R. D. J.
Froese, J. Klosin, C. Qin, G. T. Whiteker, K. A. Abboud, Orga-
nometallics 2007, 26, 2986–2999; l) P. C. J. Kamer, P. W. N. M.
van Leeuwen, J. N. H. Reek, Acc. Chem. Res. 2001, 34, 895–
904; m) E. Fuchs, M. Keller, B. Breit, Chem. Eur. J. 2006, 12,
6930–6939.
General Procedure for the Cyclization of Alkynoic Acids: A 0.5 mL
CD3CN solution of alkynoic acid was added to a suspension of the
appropriate iridium catalyst (5 mol-%) in 0.5 mL of CD3CN. The
progress of the cyclization was monitored over time by 1H and 13
C
NMR spectroscopy. Cyclized product NMR spectra were consis-
tent with reported literature values.[22]
X-ray Crystallography: Crystals of 1, 3, 4, and 9 were grown from
saturated hexane solutions, at –30 °C, crystals of 10 were grown
from a CDCl3 solution layered with hexane at room temp. and
crystals of 6 were grown by slow evaporation of a C6D6 solution
at room temp. Single crystals were coated with Paratone-N oil,
mounted using a polyimide MicroMount and frozen in the cold
nitrogen stream of the goniometer. A hemisphere of data was col-
lected on a Bruker AXS P4/SMART 1000 diffractometer using ω
and θ scans with a scan width of 0.3° and 10 s exposure times. The
detector distances were 5 cm. All data collection was performed at
173 K with the exception of 9 which was carried out at 223 K due
to loss of crystallinity at lower temperatures. The data were reduced
(SAINT)[24] and corrected for absorption (SADABS).[25] The struc-
tures were solved by direct methods and refined by full-matrix le-
ast-squares on F2 (SHELXTL).[26] The asymmetric cell for 4 con-
tains half a molecule of hexane, which is disordered over multiple
sites. This was modelled using disordered electron density
(SQUEEZE).[27] The chloroform molecules and chloride anions for
10 were disordered over two positions and refined with site occu-
pancies of 0.5. All non-hydrogen atoms were refined using aniso-
tropic displacement parameters. Hydrogen atoms were included in
calculated positions and refined using a riding model with the ex-
ception of 10 where hydrogen atoms for the chloroform molecules
were omitted.
[4] a) I. Ojima, A. C. Moralee, V. C. Vassar, Top. Catal. 2002, 19,
89–99; b) B. Bennaccer, M. Fujiwara, S.-Y. Lee, I. Ojima, J.
Am. Chem. Soc. 2005, 127, 17756–17767.
[5] a) H. Huang, A. L. Rheingold, R. P. Hughes, Organometallics
2009, 28, 1575–1578; b) V. Miranda-Soto, J. Pérez-Torrente,
L. A. Oro, F. J. Lahoz, M. L. Martín, M. Parra-Hake, D. B.
Grotjahn, Organometallics 2006, 25, 4374–4390; c) C. Buron,
L. Stelzig, O. Guerret, H. Gornitzka, V. Romanenko, G. Ber-
trand, J. Organomet. Chem. 2002, 664, 70–76; d) F. Li, B. C.
Gates, J. Phys. Chem. B 2004, 108, 11259–11264; e) J. A. Cam-
erano, M. A. Casado, M. A. Ciriano, F. J. Lahoz, L. A. Oro,
Organometallics 2005, 24, 5147–5156.
[6] H. Huang, N. R. Hurubeanu, C. J. Bourgeois, S.-M. Cheah, J.
Yuan, A. L. Rheingold, R. P. Hughes, Can. J. Chem. 2009, 87,
151–160.
[7] a) R. P. Hughes, H. A. Trujillo, J. W. Egan Jr., A. L. Rheingold,
J. Am. Chem. Soc. 2000, 122, 2261–2271; b) R. Castarlenas,
M. A. Esteruelas, M. Martín, L. A. Oro, J. Organomet. Chem.
CCDC-774663 (for 1), -774664 (for 3), -774665 (for 4),
-774666 (for 10), -774667 (for 6), -774668 (for 9) contain the supple-
mentary crystallographic data for this and can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
4608
www.eurjic.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2010, 4602–4610

Acetylacetonato(phosphane)iridium Complexes
1998, 564, 241–247; c) M. A. Esteruelas, F. J. Lahoz, E. Oñate,
L. A. Oro, L. Rodríguez, Organometallics 1996, 15, 823–834;
d) M. A. Esteruelas, F. J. Lahoz, E. Oñate, L. A. Oro, L.
Rodríguez, Organometallics 1995, 14, 263–268; e) H. Werner,
B. Papenfuhs, P. Steinert, Z. Anorg. Allg. Chem. 2001, 627,
1807–1814; f) B. Papenfuhs, N. Mahr, H. Werner, Organometal-
lics 1993, 12, 4244–4246; g) B. C. Whitmore, R. Eisenberg, In-
org. Chem. 1984, 23, 1697–1703.
V. A. Bhirud, A. Uzun, P. W. Kletnieks, R. Cracium, J. F. Haw,
D. A. Dixon, M. M. Olmstead, B. C. Gates, J. Organomet.
Chem. 2007, 692, 2107–2113.
P. Diversi, G. Ingrosso, A. Immirzi, W. Porzio, M. Zocchi, J.
Organomet. Chem. 1977, 125, 253–271.
a) C.-L. Ho, W.-Y. Wong, Z.-Q. Gao, C.-H. Chen, K.-W.
Cheah, B. Yao, Z. Xie, Q. Wang, L. Wang, X.-M. Yu, H.-S.
Kwok, Z. Lin, Adv. Funct. Mater. 2008, 18, 319–331; b) C.
Yang, X. Zhang, H. You, L. Zhu, L. Chen, L. Zhu, Y. Tao, D.
Ma, Z. Shuai, J. Qin, Adv. Funct. Mater. 2007, 17, 651–661; c)
C. J. Bourgeois, H. Huang, R. B. Larichev, L. N. Zakharov,
A. L. Rheingold, R. P. Hughes, Organometallics 2007, 26, 264–
271; d) M. Velusamy, K. R. J. Thomas, C.-H. Chen, J. T. Lin,
Y. S. Wen, W.-T. Hsieh, C.-H. Lai, P.-T. Chou, Dalton Trans.
2007, 3025–3034; e) L. Chen, C. Yang, M. Li, J. Qin, J. Gao,
H. You, D. Ma, Cryst. Growth Des. 2007, 7, 39–46; f) C.-H.
Yang, W.-L. Su, K.-H. Fang, S.-P. Wang, I.-W. Sun, Organome-
tallics 2006, 25, 4514–4519; g) I. R. Laskar, S.-F. Hsu, T.-M.
Chen, Polyhedron 2006, 25, 1167–1176; h) K. R. J. Thomas, M.
Velusamy, J. T. Lin, C.-H. Chien, Y.-T. Tao, Y. S. Wen, Y.-H.
Hu, P.-T. Chou, Inorg. Chem. 2005, 44, 5677–5685; i) D. Car-
mona, J. Ferrer, M. Lorenzo, F. J. Lahoz, I. T. Dobrinovitch,
L. A. Oro, Eur. J. Inorg. Chem. 2005, 1657–1664; j) I. R. Las-
kar, T.-M. Chen, Chem. Mater. 2004, 16, 111–117.
[16]
[17]
R. Fornika, C. Six, H. Görls, M. Kessler, C. Krüger, W. Leitner,
Can. J. Chem. 2001, 79, 642–648.
a) A. Rossin, M. Caporali, L. Gonsalvi, A. Guerri, A. Lledós,
M. Peruzzini, F. Zanobini, Eur. J. Inorg. Chem. 2009, 3055–
3059; b) J. Langer, M. J. Fabra, P. García-Orduña, F. J. Lahoz,
L. A. Oro, Chem. Commun. 2008, 4822–4824; c) D. Yakhvarov,
P. Barbaro, L. Gonsalvi, S. M. Carpio, S. Midollini, A. Orland-
ini, M. Peruzzini, O. Sinyashin, F. Zanobini, Angew. Chem. Int.
Ed. 2006, 45, 4182–4185; d) M. P. Lanci, D. W. Brinkley, K. L.
Stone, V. V. Smirnov, J. P. Roth, Angew. Chem. Int. Ed. 2005,
44, 7273–7276; e) R. W. Hilts, R. A. Franchuk, M. Cowie, Or-
ganometallics 1991, 10, 1297–1304; f) U. Casellato, B. Corain,
R. Graziani, B. Longato, G. Pilloni, Inorg. Chem. 1990, 29,
1193–1198; g) M. A. Lilga, Y. S. Sohn, J. A. Ibers, Organome-
tallics 1986, 5, 766–771; h) M. A. Lilga, J. A. Ibers, Organome-
tallics 1985, 4, 590–598; i) M. A. Lilga, J. A. Ibers, Inorg. Chem.
1984, 23, 3538–3543; j) K. Leonard, K. Plute, R. C. Halti-
wanger, R. M. DuBois, Inorg. Chem. 1979, 18, 3246–3251; k)
T. Herskovitz, J. Am. Chem. Soc. 1977, 99, 2391–2392; l) A. D.
English, T. Herskovitz, J. Am. Chem. Soc. 1977, 99, 1648–1649;
m) L. Vaska, D. L. Catone, J. Am. Chem. Soc. 1966, 88, 5324–
5325.
a) A. L. Casalnuovo, T. Laska, P. V. Nilsson, J. Olofson, L. H.
Pignolet, Inorg. Chem. 1985, 24, 233–235; b) J. E. Hoots, T. B.
Rauchfuss, S. R. Wilson, J. Chem. Soc., Chem. Commun. 1983,
1226–1228; c) A. P. Ginsberg, W. E. Lindsell, C. R. Sprinkle,
K. W. West, R. L. Cohen, Inorg. Chem. 1982, 21, 3666–3681;
d) S. Z. Goldberg, R. Eisenberg, Inorg. Chem. 1976, 15, 58–63;
e) M. J. Nolte, E. Singleton, M. Laing, J. Am. Chem. Soc. 1975,
97, 6396–6400.
a) P. Harrisson, J. Morris, T. B. Marder, P. G. Steel, Org. Lett.
2009, 11, 3586–3589; b) X. Xu, X. Xu, H. Li, X. Xie, Y. Li,
Org. Lett. 2010, 12, 100–103; c) S. L. Dabb, J. H. H. Ho, R.
Hodgson, B. A. Messerle, J. Wagler, Dalton Trans. 2009, 634–
642; d) P. Nilsson, K. Olofsson, M. Larhed, Top. Curr. Chem.
2006, 266, 103–144; e) M. Larhed, C. Moberg, A. Hallberg,
Acc. Chem. Res. 2002, 35, 717–727; f) I. A. I. Mkhalid, R. B.
Coapes, S. N. Edes, D. N. Coventry, F. E. S. Souza, R. Ll.
Thomas, J. J. Hall, S.-W. Bi, Z. Lin, T. B. Marder, Dalton Trans.
2008, 1055–1064.
a) B.-M. Fan, X.-J. Li, F.-J. Peng, H.-B. Zhang, A. S. C. Chan,
Z.-H. Shao, Org. Lett. 2010, 12, 304–306; b) Y. Iuchi, M. Hyot-
anishi, B. E. Miller, K. Maeda, Y. Obora, Y. Ishii, J. Org.
Chem. 2010, 75, 1803–1806; c) K. Koda, T. Matsu-ura, Y.
Obora, Y. Ishii, Chem. Lett. 2009, 38, 838–839; d) A. Behr, G.
Henze, L. Johnen, S. Reyer, J. Mol. Catal. A 2008, 287, 95–
101; e) S. Kezuka, S. Tanaka, T. Ohe, Y. Nakaya, R. Takeuchi,
J. Org. Chem. 2006, 71, 543–552; f) J. Krüger, B. Manmontri,
G. Fels, Eur. J. Org. Chem. 2005, 1402–1408; g) R. Takeuchi,
Y. Akiyama, J. Organomet. Chem. 2002, 651, 137–145; h) R.
Takeuchi, M. Kashio, J. Am. Chem. Soc. 1998, 120, 8647–8655;
i) H. Takaya, T. Naota, S.-I. Murahashi, J. Am. Chem. Soc.
1998, 120, 4244–4245.
[8]
[9]
[10]
[18]
[19]
[11]
[12]
J. M. Burke, R. B. Coapes, A. E. Goeta, J. A. K. Howard, T. B.
Marder, E. G. Robins, S. A. Westcott, J. Organomet. Chem.
2002, 649, 199–203.
a) A. Albinati, A. Togni, L. M. Venazi, Organometallics 1986,
5, 1785–1791; b) M. Cowie, B. L. Haymore, J. A. Ibers, J. Am.
Chem. Soc. 1976, 98, 7608–7617; c) D. A. Dobbs, R. G.
Bergman, J. Am. Chem. Soc. 1993, 115, 3836–3837; d) D. A.
Dobbs, R. G. Bergman, Organometallics 1994, 13, 4594–4605;
e) G. R. Clark, B. W. Skelton, T. N. Waters, J. Organomet.
Chem. 1975, 85, 375–394; f) J. Chen, L. M. Daniels, R. J. An-
gelici, Polyhedron 1990, 9, 1883–1891; g) R. Bau, C. J.
Schwerdtfeger, L. Garlaschelli, T. F. Koetzle, J. Chem. Soc.,
Dalton Trans. 1993, 3359–3362; h) J. R. Dilworth, C. Lu, J. R.
Miller, Y. Zheng, J. Chem. Soc., Dalton Trans. 1995, 1957–
1964; i) M. T. Ahmet, C. Lu, J. R. Dilworth, Y. Zheng, D. E.
Hibbs, M. B. Hursthouse, K. M. A. Malik, J. Chem. Soc., Dal-
ton Trans. 1995, 3143–3152; j) G. R. Clark, B. W. Skelton, T. N.
Waters, J. E. Davies, Acta Crystallogr., Sect. C 1987, 43, 1708–
1709; k) M. J. Nolte, E. Singleton, E. van der Stok, Acta Crys-
tallogr., Sect. B 1978, 34, 1684–1687; l) P. N. Swepston, N. L.
Jones, J. A. Ibers, S. Maoyu, H. Jinling, L. Jiaxi, Acta Crys-
tallogr., Sect. C 1984, 40, 39–41.
[20]
[13]
[21]
a) C. M. Vogels, A. Decken, S. A. Westcott, Can. J. Chem.
2006, 84, 146–153; b) A. T. Axtell, J. Klosin, K. A. Abboud,
Organometallics 2006, 25, 5003–5009; c) A. T. Axtell, C. J. Co-
bley, J. Klosin, G. T. Whiteker, A. Zanotti-Gerosa, K. A. Ab-
boud, Angew. Chem. Int. Ed. 2005, 44, 5834–5838; d) A. M.
Trzeciak, B. Borak, Z. Ciunik, J. J. Ziółkowski, M. F. C. Gu-
edes da Silva, A. J. L. Pombeiro, Eur. J. Inorg. Chem. 2004,
1411–1419; e) M. A. Esteruelas, F. J. Lahoz, M. Martín, A.
Martínez, L. A. Oro, M. C. Puerta, P. Valerga, J. Organomet.
Chem. 1999, 577, 265–270; f) M. A. Esteruelas, F. J. Lahoz, E.
Oñate, L. A. Oro, L. Rodríguez, P. Steinert, H. Werner, Organo-
metallics 1996, 15, 3436–3444.
a) H. Harkat, A. Y. Dembelé, J.-M. Weibel, A. Blanc, P. Pale,
Tetrahedron 2009, 65, 1871–1879; b) T. L. Mindt, R. Schibli, J.
Org. Chem. 2007, 72, 10247–10250; c) M. Viciano, E. Mas-
Marzá, M. Sanaú, E. Peris, Organometallics 2006, 25, 3063–
3069; d) E. Mas-Marzá, E. Peris, I. Castro-Rodríguez, K.
Meyer, Organometallics 2005, 24, 3158–3162; e) E. Mas-Marzá,
M. Sanaú, E. Peris, Inorg. Chem. 2005, 44, 9961–9967; f) K.
Melis, F. Verpoort, J. Mol. Catal. A 2003, 194, 39–47; g) M.
Jiménez-Tenorio, M. C. Puerta, P. Valerga, F. J. Moreno-Do-
rado, F. M. Guerra, G. M. Massanet, Chem. Commun. 2001,
2324–2325; h) T.-J. Kim, D.-H. Kim, S.-C. Shim, J.-H. Jeong,
Bull. Korean Chem. Soc. 1995, 16, 1126–1128; i) D. M. T. Chan,
T. B. Marder, D. Milstein, N. J. Taylor, J. Am. Chem. Soc. 1987,
109, 6385–6388; j) G. A. Krafft, J. A. Katzenellenbogen, J. Am.
Chem. Soc. 1981, 103, 5459–5466; k) R. A. Amos, J. A. Katz-
enellenbogen, J. Org. Chem. 1978, 43, 560–564.
[14]
[15]
D. A. Kanas, S. J. Geier, C. M. Vogels, A. Decken, S. A.
Westcott, Inorg. Chem. 2008, 47, 8727–8735.
F. Morandini, G. Pilloni, G. Consiglio, A. Mezzetti, Organome-
tallics 1995, 14, 3418–3422.
Eur. J. Inorg. Chem. 2010, 4602–4610
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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M. J. Geier, C. M. Vogels, A. Decken, S. A. Westcott
FULL PAPER
[22] a) S. Elgafi, L. D. Field, B. A. Messerle, J. Organomet. Chem.
[25]
[26]
George Sheldrick, Bruker AXS, Inc., Madison, Wisconsin,
USA, 2004.
G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
2000, 607, 97–104; b) J. H. H. Ho, D. S.-C. Black, B. A. Mes-
serle, J. K. Clegg, P. Turner, Organometallics 2006, 25, 5800–
5810.
[27] Platon: A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
[23] J. L. Herde, J. C. Lambert, C. V. Senoff, Inorg. Synth. 1974, 15,
Received: June 15, 2010
Published Online: August 24, 2010
18–20.
[24] SAINT 7.23A, Bruker AXS, Inc., Madison, Wisconsin, USA,
2006.
4610
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