Versatile κ2,η2-C ligands assembled at iridium via [2+2] oxidative cyclization

Article abstract of DOI:10.1021/om100390m

The cationic Ir(I) complex [Ir(1, 2, 5,6-η-C₈H ₁₂)(NCMe)(PMe₃)]BF₄ has been observed to react with ester-substituted internal alkynes via [2+2] oxidative cyclization to form iridacyclopentene derivatives: [Ir(1-?-5,6-η-C₈H ₁₂-2-Z-{2'-?-C(CO₂R)dC(CO₂R)})(NCMe) ₂(PMe₃)]BF₄ (R = Me, tBu). These compounds contain fac-tridentate ligands that coordinate the Ir(III) centers?², through sp³ and sp² carbons, and η² through the remaining CdC bond of the former cyclooctadienes. The derivative with R = Me has been subjected to different substitution reactions of its labile acetonitriles, including sequential reactions against monodentate ligands such as CO and PMe₃, bidentate ligands such as 2,2'-bipy, and anions such as phenylacetylide, hydride, acetylacetonate, and cyclopentadienyl. The use of these reagents, individually or in combination, has led to compounds containing the new C-donor ligand in various coordination modes, including? ³;?²,η³;?²,η²;? ²; and?,η² (or its?³ extreme version). The transformations observed for this ligand include a C-H bond activation reaction at the coordination sphere of a formally Ir(V) complex effected by an external base as weak as chloride.

Full text of DOI:10.1021/om100390m

Organometallics 2010, 29, 3201–3209 3201
DOI: 10.1021/om100390m
Versatile K2,η2-C Ligands Assembled at Iridium via [2þ2]
Oxidative Cyclization
Olga Torres, Marta Martın, and Eduardo Sola*
´
ꢀ
ꢀ
ꢀ
Departamento de Quımica de Coordinacion y Catalisis Homogenea, Instituto de Ciencia de Materiales de
ꢀ
Aragon, Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain
Received April 30, 2010
The cationic Ir(I) complex [Ir(1,2,5,6-η-C8H12)(NCMe)(PMe3)]BF4 has been observed to react with
ester-substituted internal alkynes via [2þ2] oxidative cyclization to form iridacyclopentene derivatives:
[Ir(1-κ-5,6-η-C8H12-2-Z-{20-κ-C(CO2R)dC(CO2R)})(NCMe)2(PMe3)]BF4 (R = Me, tBu). These com-
pounds contain fac-tridentate ligands that coordinate the Ir(III) centers κ2, through sp3 and sp2 carbons,
and η2 through the remaining CdC bond of the former cyclooctadienes. The derivative with R = Me has
been subjected to different substitution reactions of its labile acetonitriles, including sequential reactions
against monodentate ligands such as CO and PMe3, bidentate ligands such as 2,20-bipy, and anions such as
phenylacetylide, hydride, acetylacetonate, and cyclopentadienyl. The use of these reagents, individually or
in combination, has led to compounds containing the new C-donor ligand in various coordination modes,
including κ3; κ2,η3; κ2,η2; κ2; and κ,η2 (or its κ3 extreme version). The transformations observed for this
ligand include a C-H bond activation reaction at the coordination sphere of a formally Ir(V) complex
effected by an external base as weak as chloride.
Introduction
besides its value and potential usage to ascertain mechan-
istic details, it holds an uncommon class of polydentate
ligand bearing various different C-donor functions. This
ligand is especially stable and versatile in the coordination
sphere of iridium and is just one reaction away from usual
starting complexes of this metal.
The cycloaddition reactions catalyzed by transition
metal complexes constitute a powerful method for the
synthesis of ring molecules.1 The [2þ2] version between
alkenes and alkynes, applicable to the preparation of
cyclobutenes, can be driven by a variety of complexes,2
under conditions especially mild in the case of electron-
poor alkynes.3 The prevalent mechanistic description of
such processes involves two consecutive different C-C
bond-forming elementary steps: the so-called oxidative
cyclization and a reductive elimination.4 Among the var-
ious evidence supporting this mechanism, the key metal-
lacyclopentene intermediate connecting the two C-C
forming steps has been observed in a few instances.5,6
The present work describes a further example of metalla-
cyclopentene, formed by oxidative cyclization between an
alkyne and a cationic Ir(COD) fragment. Selected experi-
ments on this species are presented to highlight that,
Results and Discussion
In a previous work,7 we described and discussed various
reactions between alkynes and the cationic iridium(I) com-
plex [Ir(1,2,5,6-η-C8H12)(NCMe)(PMe3)]BF4 (1), the out-
come of which strongly depended on the alkyne features.
Thus, a terminal alkyne such as phenylacetylene was
observed to initially undergo C-H oxidative addition to form
an unstable Ir(III) hydride-alkynyl species, which subse-
quently evolved into the iridacyclopentadiene complex
[Ir(1,4-κ-CHdC(Ph)CHdCPh)(1,2,5,6-η-C8H12)(NCMe)-
(PMe3)]BF4 (eq 1). In contrast, an internal alkyne such as
diphenylacetylene was found to form the Ir(III) alkenyl com-
pound [Ir(1,2,3,5,6-η-C8H11){Z-C(Ph)dCHPh}(NCMe)-
(PMe3)]BF4,7 after alkyne insertion into the hydride ligand,
resulting from a previous allylic C-H activation of the
cyclooctadiene.8 Now we have observed that this latter
reaction is also not general for internal alkynes, since those
bearing ester substituents undergo fast oxidative cycliza-
tion with one of the cyclooctadiene double bonds to afford
iridacyclopentene compounds (eq 1). This behavior agrees
with a trend previously recognized in ruthenium derivatives,
*To whom correspondence should be addressed. E-mail: sola@
unizar.es.
(1) (a) Lautens, M.; Klute, W.; Tam, W. Chem. Rev. 1996, 96, 49–92.
(b) Cycloaddition Reactions in Organic Synthesis; Kobayashi, S.; Jorgensen,
K. A., Eds.; Wiley-VCH: Weinheim, 2001.
(2) For recent reports and leading references: (a) Cockburn, N.;
Karimi, E.; Tam, W. J. Org. Chem. 2009, 74, 5762–5765. (b) Treutwein, J.;
Hilt, G. Angew. Chem., Int. Ed. 2008, 47, 6811–6813.
(3) Jordan, R. W.; Villeneuve, K.; Tam, W. J. Org. Chem. 2006, 71,
5830–5833.
€
(4) (a) Trost, B. M.; Indolese, A. F.; Muller, T. J. J.; Treptow, B. J.
Am. Chem. Soc. 1995, 117, 615–623. (b) Liu, P.; Tam, W.; Goddard, J. D.
Tetrahedron 2007, 63, 7659–7666.
(5) Rusell, D.; Tucker, P. A. J. Chem. Soc., Dalton Trans. 1975,
1749–1752.
(6) O’Connor, J. M.; Closson, A.; Gantzel, P. J. Am. Chem. Soc.
(7) Martın, M.; Sola, E.; Torres, O.; Plou, P.; Oro, L. A. Organome-
tallics 2003, 22, 5406–5417.
(8) Martın, M.; Torres, O.; Onate, E.; Sola, E.; Oro, L. A. J. Am.
~
2002, 124, 2434–2435.
Chem. Soc. 2005, 127, 18074–18084.
r
2010 American Chemical Society
Published on Web 06/21/2010
pubs.acs.org/Organometallics

3202 Organometallics, Vol. 29, No. 14, 2010
Torres et al.
Table 1. Bond Distances (A) and Angles (deg) for Complex 2
˚
Ir-P
2.2848(10)
2.110(3)
2.079(3)
2.394(4)
1.550(5)
Ir-N(1)
Ir-N(2)
2.135(3)
2.018(3)
2.317(4)
1.521(4)
1.346(5)
95.06(8)
87.48(10)
156.58(10)
80.62(14)
173.93(13)
88.57(12)
97.36(13)
95.36(12)
Ir-C(1)
Ir-C(9)
Ir-C(5)
Ir-C(6)
C(2)-C(10)
C(5)-C(6)
C(1)-C(2)
C(9)-C(10)
P-Ir-N(1)
P-Ir-C(1)
P-Ir-C(5)
N(1)-Ir-N(2)
N(1)-Ir-C(1)
N(1)-Ir-C(5)
N(1)-Ir-C(6)
N(1)-Ir-C(9)
1.341(5)
85.32(9)
P-Ir-N(2)
P-Ir-C(9)
P-Ir-C(6)
C(1)-Ir-C(9)
N(2)-Ir-C(1)
N(2)-Ir-C(5)
N(2)-Ir-C(6)
N(2)-Ir-C(9)
90.60(11)
167.35(10)
86.70(11)
98.02(12)
107.02(12)
75.69(13)
172.66(12)
Although rarely observed, metallacyclopentene skeletons
similar to those of 2 and 3, and related species derived from
norbornadiene, norbornene, or other alkenes, are very com-
monly proposed as intermediates in [2þ2] cycloaddition reac-
tions, especially in the chemistry of ruthenium.9 In spite of this,
complexes 2 and 3 have proved to be stable against possible
C-C reductive eliminations yielding cyclobutenes, even in the
presence of additional ligands (see below). This reluctance to
undergo C-C reductive eliminations becomes more significant
after observing that 2 contains two weakly coordinating acet-
onitrile ligands displaying long Ir-N distances, indicative of
their easy dissociation.10 This should contribute to facilitate
these reactions since, with regard to a “well-established” me-
chanistic tenet concerning C-C reductive eliminations,11,12 they
are kinetically much more facile from five-coordinate d6 metal
complexes than from the corresponding six-coordinate com-
pounds. Nevertheless, it should be noted that this conclusion
has been extracted from the investigation of tri- and tetramethyl
Pt(IV) complexes, in which any coordination vacancy is gener-
Figure 1. X-ray structure of the cation of complex 2.
according to which electron-withdrawing substituents at the
alkyne favor cycloadditions.3
11
ated at a position cis to both groups to be coupled. This is not
the case of complex 2 and certain Pd(IV) compounds, whose
13
reactivity seems to contradict the above conclusion.
The formation of compounds [Ir(1-κ-5,6-η-C8H12-2-Z-{20-κ-
C(CO2R)dC(CO2R)})(NCMe)2(PMe3)]BF4 (R=Me (2) and
tBu (3), eq 1) from 1 and one equivalent of the corresponding
alkyne is selective and almost immediate at 273 K. The structure
of 2determined by X-ray diffraction (Figure 1, Table 1) confirms
the occurrence of an oxidative cyclization reaction leading to a
fac-tridentate ligand. This ligand coordinates κ2 via sp3 and sp2
carbons and η2 through the remaining intact CdC double bond
of the cyclooctadiene. The bond distances within the resulting iri-
dacyclopentene ring are similar to those found in the related spe-
cies [(Tp)Ir{1,4-κ-CH2CH2C(CO2Me)dC(CO2Me)}(NCMe)]6
and confirm the localization of the double bond between the
former alkyne carbons. The metal-bonded carbons of the new
ligand produce P-coupled 13C{1H} NMR signals at character-
istic chemical shifts (at high and low field for the sp3 and sp2 κ
carbons: 18.69 (2.7 Hz) and 149.96 (11.6 Hz), respectively) and
indicative of their coordination trans to phosphine for the η ones
(100.91 (10.2 Hz) and 107.47 (11.1 Hz)).
Despite the small difference between the two Ir-N dis-
tances of 2, the acetonitrile ligand with the longest one, that
(9) See for example: Trost, B. M.; Toste, F. D.; Pinkerton, A. B.
Chem. Rev. 2001, 101, 2067–2096.
(10) See for example: (a) Torres, O.; Martın, M.; Sola, E. Organo-
ꢀ
metallics 2009, 28, 863–870. (b) Sola, E.; Navarro, J.; Lopez, J. A.; Lahoz,
F. J.; Oro, L. A.; Werner, H. Organometallics 1999, 18, 3534–3546.
(11) (a) Goldberg, K. I.; Yan, J.; Breitung, E. M. J. Am. Chem. Soc. 1995,
117, 6889–6896. (b) Hill, G. S.; Yap, G. P. A.; Puddephatt, R. J. Organometallics
1999, 18, 1408–1418. (c) Crumpton, D. M.; Goldberg, K. I. J. Am. Chem. Soc.
2000, 122, 962–963. (d) Crumpton-Bregel, D. M.; Goldberg, K. I. J. Am. Chem.
Soc. 2003, 125, 9442–9456. (e) Procelewska, J.; Zahl, A.; Liehr, G.; Van Eldik, R.;
Smythe, N. A.; Williams, B. S.; Goldberg, K. I. Inorg. Chem. 2005, 44, 7732–
7742. (f) Luedtke, A. T.; Goldberg, K. I. Inorg. Chem. 2007, 46, 8496–8498.

Article
Organometallics, Vol. 29, No. 14, 2010 3203
˚
Table 2. Bond Distances (A) and Angles (deg) for
Complexes 9 and 11
9
11
Ir-P
2.2867(17)
2.142(6)
2.2671(12)
2.126(3)
2.110(3)
2.119(4)
Ir-N
Ir-O(6)
Ir-O(7)
Ir-C(1)
2.063(7)
2.310(7)
2.257(7)
2.059(6)
2.059(6)
1.571(9)
1.509(7)
1.329(7)
1.351(9)
96.32(15)
Ir-C(5)
Ir-C(6)
Ir-C(9)
2.017(4)
1.913(4)
1.545(5)
1.507(5)
1.341(5)
1.323(7)
89.97(8)
175.79(8)
88.37(12)
Ir-C(20)
C(1)-C(2)
C(2)-C(10)
C(9)-C(10)
C(5)-C(6)
P-Ir-N
Ir-C(15)
P-Ir-O(6)
P-Ir-O(7)
P-Ir-C(1)
P-Ir-C(5)
P-Ir-C(6)
P-Ir-C(9)
P-Ir-C(20)
N-Ir-C(1)
N-Ir-C(5)
N-Ir-C(6)
N-Ir-C(9)
N-Ir-C(20)
90.47(16)
165.17(18)
157.26(19)
86.21(18)
85.20(19)
171.3(2)
87.6(2)
96.3(2)
94.1(2)
89.2(2)
91.90(11)
91.70(12)
88.56(11)
92.96(14)
171.58(14)
93.04(14)
87.76(14)
89.00(13)
78.89(17)
174.00(17)
95.11(17)
P-Ir-C(15)
O(6)-Ir-O(7)
O(6)-Ir-C(1)
O(6)-Ir-C(9)
O(6)-Ir-C(15)
O(7)-Ir-C(1)
O(7)-Ir-C(9)
C(1)-Ir-C(9)
C(1)-Ir-C(20)
C(9)-Ir-C(20)
80.9(3)
96.8(3)
171.1(2)
C(1)-Ir-C(15)
C(9)-Ir-C(15)
After completion of the 4a to 4b isomerization, the remaining
acetonitrile ligand can also be replaced by CO to give the com-
plex [Ir(1-κ-5,6-η-C8H12-2-Z-{20-κ-C(CO2Me)dC(CO2Me)})-
(CO)2(PMe3)]BF4 (6). This second substitution has proved to
be easily reversible, and as a result, the quantitative generation
of this product has been possible only in solution under CO
excess. By contrast, the other two bis-substituted compounds in
eq 1, that with three fac PMe3 ligands (7) andthe 2,20-bipyridine
derivative (8), have been easily isolated and found to be stable
against ligand dissociation.
Figure 2. X-ray structures of complexes 9 (above) and 11 (below).
The release and substitution of the η2 ligand moiety has not
been observed in any of the reactions summarized in eq 2, even
under large ligand excesses. Nevertheless, this process seems to
be much easier in the neutral derivatives of 2 described from this
point on. A representative example of substitution reaction
leading to a neutral complex is shown in eq 3. The reaction
between 2 and lithium phenylacetylide has been observed
to readily form [Ir(1-κ-5,6-η-C8H12-2-Z-{20-κ-C(CO2Me)d
C(CO2Me)})(CtCPh)(NCMe)(PMe3)] (9), the structure and
structural details of which are shown in Figure 2 and Table 2,
respectively. The compound meets at the coordination sphere
of iridium sp3, sp2, and sp κ carbons, together with the η2 alkene
fragment. In spite of such accumulation of reactive groups, the
complex has been found to be thermally stable.14
trans to the sp3carbon, can be selectively substituted in CH2Cl2
solution by ligands such as CO and PMe3. Workup and isolation
of these substitution kinetic products, [Ir(1-κ-5,6-η-C8H12-
2-Z-{20-κ-C(CO2Me)dC(CO2Me)})(NCMe)(L)(PMe3)]BF4
(L=CO (4a) and PMe3 (5a), eq 2), has not required provi-
sions other than short reaction times and low CO pressure in the
case of 4a and the careful use of one equivalent of PMe3 for 5a.
The effects of these ligand substitutions in the NMR spectra are
notable in the 13C{1H} signal corresponding to the κ CH, which
shifts to lower field (from δ 18.69 to 34.49 in 4a or 30.81 in 5a)
and splits due to an additional JCP coupling constant of 72.5 Hz
in the case of 5a. The transformation of 4a into its stable isomer
4b (eq 2) has been monitored by NMR in a sample of isolated4a
dissolved in CD2Cl2. At 323 K, the isomerization was complete
in about 20 h. The coordination position of CO in the new
isomer 4b can also be inferred from the 13C{1H} NMR signal
corresponding to the trans κcarbon, which also shifts downfield,
from δ139.57 (in 4a) to 158.55. In parallel, that corresponding to
the κ CH shifts back to a δ close to that in 2, 24.30 ppm.
With regard to the conclusions of eq 2, the structure of 9,
with the incoming acetylide ligand trans to the sp2 side of the
(12) (a) Madison, B. L.; Thyme, S. B.; Keene, S.; Williams, B. S. J. Am.
Chem. Soc. 2007, 129, 9538–9539. (b) Lindner, R.; Wagner, C.; Steinborn, D. J.
Am. Chem. Soc. 2009, 131, 8861–8874. (c) Gosh, R.; Emge, T. J.; Krogh-
Jespersen, K.; Goldman, A. S. J. Am. Chem. Soc. 2008, 130, 11317–11327.
(13) Racowski, J. M.; Dick, A. R.; Sandford, M. S. J. Am. Chem. Soc.
2009, 131, 10974–10983.
(14) For related compounds and reactions, see: (a) Chin, C. S.; Kim,
M.; Lee, H. Organometallics 2002, 21, 1679–1683. (b) Chin, C. S.; Lee, H.;
Eum, M.-S. Organometallics 2005, 24, 4849–4852.

3204 Organometallics, Vol. 29, No. 14, 2010
Torres et al.
iridacyclopentene, is that expected for the thermodynamic
substitution isomer. The hypothetic kinetic isomer likely
preceding the formation of 9 has not been observed. This
might be tentatively attributed to its short life, a possibility
that would suggest an enhancement of acetonitrile lability on
going from cationic to electron richer neutral complexes.
This observation, however, is not fairly supported by the
available structural features, which indicate that the Ir-N
distances trans to the sp3 κ carbon are nearly equal in cationic
and neutral compounds. Actually, the rest of the structural
parameters of 9 are also similar to those of 2.
Illustration of the coordination versatility of our new triden-
tate ligand can start in a second example of the neutral
derivative, the acetylacetonate complex [Ir(1-κ-5,6-η-C8H12-
2-Z-{20-κ-C(CO2Me)dC(CO2Me)})(κ2-O-acac)(PMe3)] (10),
which has been readily prepared from 2 and potassium acet-
ylacetonate. Although 10 has no more acetonitriles available, it
has shown itself able to slowly accommodate a CO or PMe3
additional ligand after release of the η2-alkene function and
reorganization of the acac coordination (eq 4).
[Ir(1-κ-5,6,7-η-C8H11-2-Z-{20-κ-C(CO2Me)dC(CO2Me)})-
(CO)(PMe3)] (13) (eq 4). The NMR spectroscopic observa-
tion of this reaction has evidenced that 13 and its precursor
11 are in slow equilibrium. The equilibrium can be shifted to
achieve quantitative formation of 13 by heating at 353 K for
about 48 h and can be reverted to 11 by addition of
acetylacetone excess, always under CO atmosphere to avoid
the accumulation of 10.
The characterization data of 13 are consistent with the struc-
tural proposal depicted in eq 4. The 13C{1H} NMR APT spec-
trum reveals the disappearance of one of the four CH2 char-
acteristic resonances of the ligand to give a new CH signal. The
1
1H/13C NMR correlation in combination with the H COSY
and NOESY spectra indicates that, from the two possible allylic
activations, only that leading to the proposed structure has
selectively occurred. The 13C{1H} NMR signals corresponding
to the allyl moiety are two doublets at δ 43.08 (JCP=21.2 Hz)
and 135.80 (JCP=8.2 Hz) and a singlet at δ 130.72. The mag-
nitude of the two coupling constants is consistent with a η3
coordination occupying the position trans to phosphine, but the
chemical shifts of the latter two signals suggest a κ coordination
as a better description. Most likely, this apparent discrepancy
just reflects the difficulties of the ligand to reach four of the six
octahedral coordination positions.
The attainment of other coordination modes requires the
participation of hydrides or protons. The hydride complex
[Ir(1-κ-5,6-η-C8H12-2-Z-{20-κ-C(CO2Me)dC(CO2Me)})H-
(NCMe)(PMe3)] (14) has been prepared by reaction of 2 with
one equivalent of KOH in methanol at low temperature.
Following the usual mechanistic proposals, this reaction should
involve the initial formation of a methoxo intermediate, which
would undergo hydrogen β-elimination to release formalde-
hyde.15 Neither this likely methoxo intermediate nor possible
isomers of 14 have been observed. Complex 14 displays a char-
acteristic 1H NMR hydride resonance at δ -11.58 (JHP=26.7
Hz), which exhibits NOE effects with that of PMe3, and another
two due to dCH and CH2 hydrogens of the ligand, in agreement
with the structure depicted in eq 5.
The structure of the carbon monoxide derivative [Ir(1-κ-
C8H12-2-Z-{20-κ-C(CO2Me)dC(CO2Me)})(κ2-O-acac)(CO)-
(PMe3)] (11) is shown in Figure 2. The relevant bond distances
and angles of the structure are collected in Table 2. Comparing
this X-ray structure with the previous two indicates that the
additional η2 coordination of the ligand hardly modifies the iri-
dacyclopropene ring geometry. A parameter illustrating some
minor structural effects is the Ir-C(9)-C(10)-C(2) torsion
angle of the metallacycle double bond, which reaches 15° and
12° in derivatives 2 and 9, respectively, but relaxes to 2° in
complex 11.
The spectroscopic data of the PMe3 analogue of 11,
[Ir(1-κ-C8H12-2-Z-{20-κ-C(CO2Me)dC(CO2Me)})(κ2-O-acac)-
(PMe3)2] (12), indicate that its structure is indeed analogous.
The coordination position of the phosphine ligands is inferred
from the 13C{1H} NMR signals of the κ carbons: a doublet of
doublets at δ37.85 (JCP=92.7 and 4.3) and a doublet at δ146.71
(JCP=10.3). Additionally, the signals corresponding to the al-
kene function are now singlets at δ 126.49 and 132.07, chemical
shifts typical for noncoordinated olefinic CH carbons.
The treatment of 14 with one equivalent of 2,20-bipyridine
has led to a product of formal insertion of the η2 alkene
fragment into the Ir-H bond: the complex [Ir(1,5-κ-C8H13-
2-Z-{20-κ-C(CO2Me)dC(CO2Me)})(κ2-N-bipy)(PMe3)] (15)
(eq 5). After this insertion, the ligand becomes formally
trianionic and coordinates κ3 through one sp2 and two sp3
carbons. The 1H/13C NMR correlation together with the 1H
COSY and NOESY spectra of 15 confirm that insertion has
selectively occurred in the carbon labeled as 6, that is, in the
sense expected from the structure of 14. The 13C{1H} NMR
signals corresponding to the three κ carbons are a singlet at δ
8.42 and two doublets at δ 16.42 (JCP = 76.6 Hz) and 162.56
(JCP = 11.8 Hz), in agreement with the proposed ligand
distribution around iridium.
The bis-phosphine derivative 12 has been found to be
thermally stable. In contrast, the heating of a toluene
solution of complex 11 under argon at 353 K has been
observed to slowly afford the precursor 10. The same experi-
ment carried out under CO atmosphere to avoid the latter
reverse reaction has led to a different evolution, namely,
the elimination of acetylacetone and formation of complex
ꢀ
(15) (a) Fernandez, M. J.; Esteruelas, M. A.; Covarrubias, M.; Oro,
L. A. J. Organomet. Chem. 1986, 316, 343-349. For leading references,
see: (b) Zhao, J.; Hesslink, H.; Hartwig, J. F. J. Am. Chem. Soc. 2001,
123, 7220–7227.

Article
Organometallics, Vol. 29, No. 14, 2010 3205
Other spectroscopic details of 17, such as the very large
13.8 Hz JHP coupling constant found in the 1H NMR signal
of the new CH generated after protonation, also seem rather
incompatible with a π-alkene but possible in the iridacyclo-
propane structure.
Also in agreement with the formulation given to 17, its
reaction with a good potential ligand such as chloride has not
led to the replacement of the possible η2 alkene function.
Instead, this very weak base has emerged capable of depro-
tonating 17 back to 16. Such an unexpected reaction has been
quantitatively achieved after a few minutes heating at 323 K
of a CH2Cl2 solution of 17 in the presence of a KCl suspen-
sion. Complex 17, or more precisely its Ir(III) π-alkene
extreme, resembles a family of Ir(III) cationic compounds
with Cp* ligands that has been extensively studied in the
17
context of C-H activation. The numerous mechanistic
investigations carried out in these compounds strongly sug-
gest that the activations involve sequences of oxidative
addition/reductive elimination elementary steps via Ir(V)
intermediates, which are isolable in some cases.18 However,
to the best of our knowledge, external base-induced C-H
activations such as that in eq 6 have never been described in
either Ir(III) or Ir(V) complexes of this family.19 Never-
theless, these reactions are known in highly electrophilic
complexes of other types.20
In summary, we have shown that internal alkynes with
ester substituents react with the cationic Ir(I) complex
[Ir(1,2,5,6-η-C8H12)(NCMe)(PMe3)]BF4 via oxidative cycli-
zations to afford Ir(III) derivatives having 1-κ-5,6-η-C8H12-
2-Z-{20-κ-C(CO2R)dC(CO2R)} ligands. In the coordination
sphere of Ir(III), this type of ligand has emerged stable
against reductive elimination, capable of accommodating
its coordination and electronic features as required by dif-
ferent incoming ligands and able to exploit the reversible
exchange of hydrides and protons with the metal center,
other basic ligands, and external bases. This versatility,
together with the ease with which the ligand can be
assembled, makes it a candidate to be considered when looking
for a simple, stabilizing, and strong-donor polydentate
auxiliary in the context of iridium chemistry and catalysis.
Figure 3. 13C{1H} APT NMR spectra of compounds 16 and 17
in CD2Cl2.
Complex 2has also been found able to accommodate a triden-
tate anionic ligand such as cyclopentadienyl after losing both
acetonitrile ligands and releasing the η2 CdC bond. This substi-
tution reaction has afforded the neutral iridacyclopentene com-
plex [Ir(η5-C5H5)(1-κ-C8H12-2-Z-{20-κ-C(CO2Me)dC(CO2-
Me)})(PMe3)] (16) (eq 6). With regard to our ligand, the
spectroscopic features of 16 are similar to those of 11 and 12,
thus indicating the same coordination mode.
In the presence of a strong Brønsted acid such as HBF4,
complex 16 has been observed to form the cationic derivative
17 (eq 6). The 13C{1H} NMR spectrum of this compound
(Figure 3) evidenced that the proton has attacked the former
sp2 κ carbon of the iridacyclopentene instead of the more
electron-rich sp3 one. This choice seems more suitable from a
thermodynamic point of view since it leads to a product that
remains electronically and coordinatively saturated, conditions
more difficult to maintain after the other mentioned alternative.
Figure 3 illustrates the marked upfield shifts provoked by the
reaction in the 13C{1H} NMR signals of the iridacycle atoms,
especially large in those of sp2 carbons (9 and 10 in the figure)
but also very notable in that due to the sp3 one (1). This suggests
that these carbons have become much more electron-rich in spite
of the protonation. Interestingly, there is also a notable shift of
the signal corresponding to the five Cp carbons, but toward
downfield. This seems to indicate that, even though the proton
has been incorporated into our ligand, the necessary electron
density has eventually been supplied by the metal, which, in con-
sequence, demands more from the Cp ligand. Since the transfer
of electron density to our ligand must imply an enhanced back-
donation to the alkene moiety, it seems more realistic to describe
17 as an Ir(V) metallacyclopropene complex, [Ir(η5-C5H5)(1-κ-
C8H12-2-Z-{10,20-κ-C(CO2Me)dCH(CO2Me)})(PMe3)]BF4,
rather than as the alternative Ir(III) π-alkene extreme.16
Experimental Section
Equipment. C, H, and N analyses were carried out in a Perkin-
Elmer 2400 CHNS/O analyzer. FAB-MS data were recorded on
a VG Autospec double-focusing mass spectrometer operating in
the positive mode; ions were produced with a Csþ gun at ca.
30 kV, and 3-nitrobenzyl alcohol (NBA) was used as the matrix.
MALDI-TOF-MS were obtained in a Bruker Microflex mass
spectrometer using DCTB (1,1-dicyano-4-tert-butylphenyl-3-
methylbutadiene) as matrix. Infrared spectra were recorded in
solution or KBr using a FTIR Perkin-Elmer Spectrum One
spectrometer. Molar conductivities (ΛM) were measured in ca.
5 ꢀ 10-4 M solutions using a Philips PW 9501/01 conductimeter.
NMR spectra were recorded on Bruker Avance 400 or 300 MHz
(17) (a) Klei, S. R.; Golden, J. T.; Burger, P.; Bergman, R. G. J. Mol.
Catal. A: Chem. 2002, 189, 79-94. See also: (b) Alaimo, P. J.; Arndsten,
B. A.; Bergman, R. G. Organometallics 2000, 19, 2130–2143. (c) Leung,
D. H.; Fiedler, D.; Bergman, R. G.; Raymond, K. N. Angew. Chem., Int. Ed.
2004, 43, 963–966.
(18) Alaimo, P. J.; Bergman, R. G. Organometallics 1999, 18, 2707–
2717.
(19) For internal base-induced C-H activations in closely related
complexes, see: Davies, D. L.; Donald, S. M. A.; Al-Duaij, O.;
€
(16) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 4th ed.; Wiley: New York, 2001; Chapter 3, p 125.
Macgregor, S. A.; Polleth, M. J. Am. Chem. Soc. 2006, 128, 4210–4211.
(20) Hahn, C. Organometallics 2010, 29, 1331–1338.

3206 Organometallics, Vol. 29, No. 14, 2010
Torres et al.
1
spectrometers. H (400.13 or 300.13 MHz) and 13C (100.6 or
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(CO)(NCMe)(PMe3)]BF4 (4a). A 5 mL CH2Cl2
solution of 2 (164 mg, 0.24 mmol) was stirred under CO atmo-
sphere (ca. 1 bar) for 10 min at room temperature. The resulting
solution was concentrated to ca. 0.5 mL and treated with diethyl
ether to give a yellow solid. The solid was separated by decanta-
tion, washed with diethyl ether, and dried: yield 148 mg (91%).
Anal. Calcd (%) for C20H30BF4IrNO5P: C, 35.62; H, 4.48; N,
2.08. Found: C, 35.87; H, 4.43; N, 1.92. MS (FABþ, m/z (%)):
547 (20) [Mþ - NCMe], 519 (60) [Mþ - NCMe - CO]. IR (KBr,
cm-1): 2331 ν(NtC), 2058 ν(CtO), 1703 ν(OCO), 1059 ν(BF4).
1H NMR (CD2Cl2): δ 1.70 (m, 1H, CH2), 1.79 (d, JHP = 11.7,
9H, PCH3), 2.02 (m, 2H, CH2), 2.20 (m, 1H, CH2), 2.30, 2.45
(both m, 2H each, CH2), 2.65 (m, 1H, IrCH), 2.67 (s, 3H,
NCCH3), 3.20 (m, 1H, CH), 3.63, 3.75 (both s, 3H each, OCH3),
5.65, 6.27 (both m, 1H each, dCH). 31P{1H} NMR (CD2Cl2):
δ -24.15(s). 13C{1H} NMR (CD2Cl2, 253 K):δ 3.62 (s, NCCH3),
13.94 (d, JCP=43.8, PCH3), 21.95, 26.46 (both s, CH2), 34.49 (d,
JCP = 2.7, IrCH), 37.65, 37.68 (both s, CH2), 46.50 (s, CH),
51.39, 51.62 (both s, OCH3), 104.56 (d, JCP = 8.3, dCH), 112.36
(d, JCP=10.1, dCH), 124.45 (s, NCCH3), 139.57 (d, JCP=11.0,
IrCdC), 143.81 (d, JCP = 3.6, IrCdC), 163.74 (s, CO), 169.66 (d,
JCP = 4.2, IrCO), 174.76 (s, CO).
[Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)dC(CO2Me)})-
(CO)(NCMe)(PMe3)]BF4 (4b). A 0.5 mL CD2Cl2 solution of 4a
(65 mg, 0.10 mmol) in a NMR tube was heated at 323 K for 20 h.
The NMR monitoring of the resulting solution revealed the
quantitative transformation of the precursor complex into its
isomer 4b. MS (FAB, m/z (%)): 547 (13), [Mþ - NCMe], 519
(100) [Mþ - NCMe - CO]. IR (CD2Cl2, cm-1): 2061 ν(CtO),
1708 ν(OCO). 1H NMR (CD2Cl2): δ 1.61 (m, 2H, CH2), 1.77 (d,
9H, JHP =11.6, PMe3), 1.98, 2.06, 2.26, 2.29 (all m, 1H each,
CH2), 2.30 (s, 3H, NCCH3), 2.37, 2.63 (m, 1H, IrCH), 2.73 (both
m, 1H each, CH2), 2.78 (m, 1H, CH), 3.58, 3.66 (both s, 3H each,
OCH3), 4.80, 6.25 (both m, 1H each, dCH). 31P{1H} NMR
(CD2Cl2): δ -27.78 (s). 13C{1H} NMR (CD2Cl2): δ 2.88 (s,
NCCH3), 14.47 (d, JCP = 43.7, PCH3), 21.83 (d, JCP=1.3, CH2),
22.13 (s, CH2), 24.30 (d, JCP = 1.6, IrCH), 25.89 (s, CH2), 43.18
(d, JCP=1.7, CH2), 49.08 (d, JCP=1.5, CH), 51.36, 51.50 (both s,
OCH3), 99.13 (d, JCP = 10.4, dCH), 104.99 (d, JCP=8.2, dCH),
120.72 (s, NCCH3), 141.59 (d, JCP = 4.6, IrCdC), 158.55 (d,
75.5 MHz) NMR chemical shifts were measured relative to
partially deuterated solvent peaks but are reported in ppm
relative to tetramethylsilane. 31P NMR (162.0 or 121.5 MHz)
chemical shifts were measured relative to H3PO4 (85%). Cou-
pling constants, J, are given in hertz. In general, NMR spectral
assignments were achieved through 1H COSY, 1H NOESY, 13
C
APT, and H/13C-HSQC experiments. Spectroscopic data are
given at room temperature unless otherwise indicated.
1
Synthesis. All manipulations were carried out under argon by
standard Schlenk techniques. Solvents were obtained from an
Innovative Technology solvent purification system. Deuterated
solvents were carefully dried by known procedures and stored
under argon prior to use. The starting complex [Ir(1,2,5,6-η-
C8H12)(NCMe)(PMe3)]BF4 (1) was prepared as previously
reported.7 All commercial reagents were used as received with-
out further purification. All new complexes described below are
air sensitive in solution.
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(NCMe)2(PMe3)]BF4 (2). To a 5 mL CH2Cl2 solu-
tion of 1 (123 mg, 0.24 mmol) was added dimethylacetylene
dicarboxylate (30 μL, 0.24 mmol). The reaction mixture was
stirred at 273 K for 10 min, after which it was concentrated
under reduced pressure to ca. 0.5 mL. The addition of diethyl
ether produced a pale yellow solid, which was separated by
decantation, washed with diethyl ether, and dried in vacuo: yield
146 mg (87%). Anal. Calcd (%) for C21H33BF4IrN2O4P: C,
36.69; H, 4.84; N, 4.08. Found: C, 36.23; H, 4.47; N, 3.85. MS
(FABþ, m/z (%)): 519 (88) [Mþ - 2 NCMe]. IR (KBr, cm-1):
2322, 2293 ν(NtC), 1709 ν(OCO), 1059 ν(BF4). ΛM (ace-
tone)=83 Ω-1 cm2 mol-1 (1:1). 1H NMR (CD2Cl2): δ 1.63 (d,
JHP=11.2, 9H, PCH3), 1.68 (m, 3H, CH2), 2.00 (m, 1H, CH2),
2.12, 2.28 (both m, 1H each, CH2), 2.36 (s, 3H, NCCH3), 2.48
(m, 1H, CH2), 2.49 (m, 1H, IrCH), 2.60 (s, 3H, NCCH3), 2.75
(m, 1H, CH), 3.62, 3.73 (both s, 3H each, OCH3), 4.98, 5.80
(both m, 1H each, dCH). 31P{1H} NMR (CD2Cl2): δ -25.98 (s).
13C{1H} NMR (CD2Cl2): δ 2.63, 3.59 (both s, NCCH3), 12.09
(d, JCP = 41.5, PCH3), 18.69 (d, JCP = 2.7, IrCH), 21.86, 22.16,
25.36 (all s, CH2), 38.40 (d, JCP = 2.3, CH2), 47.54 (d, JCP = 1.7,
CH), 50.89, 50.93 (both s, OCH3), 100.91 (d, JCP = 10.2, dCH),
107.47 (d, JCP=11.1, dCH), 118.91, 122.72 (both s, NCCH3),
139.74 (d, JCP =4.0, IrCdC), 149.96 (d, JCP =11.6, IrCdC),
163.24 (s, CO), 175.08 (d, JCP = 3.1, CO). The crystals used in
the X-ray experiment were obtained from a CH2Cl2 solution of 2
layered with hexane, at room temperature.
JCP = 13.2, IrCdC), 163.23 (d, JCP=1.4, CO), 172.64 (d, JCP
8.9, IrCO), 174.18 (d, JCP = 2.9, CO).
=
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(NCMe)(PMe3)2]BF4 (5a). To a 5 mL CH2Cl2
solution of 2 (151 mg, 0.22 mmol) was added trimethylpho-
sphine (28 μL, 0.26 mmol) using a microsyringe. The reaction
mixture was stirred at room temperature for 5 min, after which it
was concentrated to ca. 0.5 mL. The addition of diethyl ether
produced a yellow solid, which was separated by decantation,
washed with diethyl ether, and dried: yield 142 mg (81%). Anal.
Calcd (%) for C22H39BF4IrNO4P2: C, 36.57; H, 5.44; N, 1.94.
Found: C, 36.25; H, 5.28; N, 1.91. MS (FABþ, m/z (%)): 595
(60) [Mþ - NCMe], 519 (78) [Mþ - NCMe - PMe3]. IR (KBr,
cm-1): 2290 ν(NtC), 1696 ν(OCO), 1060 ν(BF4). 1H NMR
(CD2Cl2, 253 K): δ 1.33 (d, JHP=8.0, 9H, PCH3), 1.60 (m, 1H,
CH2), 1.61 (d, JHP = 10.8, 9H, PCH3), 1.89, 2.03, 2.07, 2.18
(all m, 1H each, CH2), 2.40 (m, 2H, CH2), 2.45 (m, 1H, CH2),
2.52 (m, 1H, IrCH), 2.64 (s, 3H, NCCH3), 3.05 (m, 1H, CH),
3.59, 3.68 (both s, 3H each, OCH3), 5.21, 5.68 (both m, 1H
each, dCH). 31P{1H} NMR (CD2Cl2, 253 K): δ -53.07, -29.05
(both d, JPP=5.6). 13C{1H} NMR (CD2Cl2, 253 K): δ 3.94 (s,
NCCH3), 14.50 (d, JCP = 25.3, PCH3), 14.74 (dd, JCP=42.4,
2.5, PCH3), 21.61, 22.29 (both s, CH2), 26.71 (d, JCP = 6.5,
CH2), 30.81 (dd, JCP=72.5, 2.7, IrCH), 37.55 (d, JCP=2.1, CH2),
45.90 (d, JCP = 5.0, CH), 51.50, 51.83 (both s, OCH3), 100.20 (d,
JCP = 9.06, dCH), 105.69, (d, JCP = 11.1, dCH), 122.99 (s,
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2tBu)d
C(CO2tBu)})(NCMe)2(PMe3)]BF4 (3). To a 5 mL CH2Cl2 solu-
tion of 1 (103 mg, 0.20 mmol) was added di-tert-butylacetylene
dicarboxylate (47 μL, 0.20 mmol). The reaction mixture was
stirred at 258 K for 5 min, after which it was concentrated to
ca. 0.5 mL. The addition of diethyl ether produced a yellow
solid, which was separated by decantation, washed with diethyl
ether, and dried: yield 183 mg (81%). Anal. Calcd (%) for
C27H45BF4IrN2O4P: C, 42.02; H, 5.87; N, 3.63. Found: C,
42.17; H, 5.95; N, 3.90. MS (FABþ, m/z (%)): 685 (12) [Mþ],
644 (32) [Mþ - NCMe], 603 (100) [Mþ - 2NCMe]. IR (KBr,
cm-1): 2321, 2290 ν(NtC), 1698 ν(OCO), 1059 ν(BF4). 1H
NMR (CD2Cl2): δ 1.44, 1.51 (both s, 9H each, C(CH3)3), 1.63
(d, JHP = 11.3, 9H, PCH3), 1.68 (m, 3H, CH2), 2.00, 2.12 (both
s, 1H each, CH2), 2.25 (s, 3H, NCCH3), 2.28 (m, 2H, CH2), 2.48
(m, 1H, CH2), 2.49 (m, 1H, IrCH), 2.54 (s, 3H, NCCH3), 2.75
(m, 1H, CH), 4.98, 5.80 (both m, 1H each, dCH). 31P{1H} NMR
(CD2Cl2): δ -25.69 (s). 13C{1H} NMR (CD2Cl2): δ 3.01, 3.53
(both s, NCCH3), 12.24 (d, JCP = 41.4, PCH3), 18.52 (d, JCP
=
2.7, IrCH), 21.77, 22.63, 25.43 (all s, CH2), 28.02, 28.10 (both s,
OC(CH3)3), 38.33 (d, JCP = 2.3, CH2), 47.90 (d, JCP = 1.4, CH),
79.04, 79.68 (both s, OC(CH3)3), 100.16 (d, JCP = 10.4, dCH),
105.94 (d, JCP = 11.2, dCH), 118.87, 122.42 (both s, NCCH3),
141.03 (d, JCP = 4.3, IrCdC), 147.95 (d, JCP = 12.2, IrCdC),
163.06 (d, JCP = 1.2, CO), 173.80 (d, JCP = 3.0, CO).
NCCH3), 143.09 (dd, JCP=10.5, 3.9, IrCdC), 145.34 (d, JCP
13.8, IrCdC), 163.73 (d, JCP=1.1, CO), 177.05 (dd, JCP=6.3,
=
3.1, CO).

Article
[Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)dC(CO2Me)})(CO)2-
Organometallics, Vol. 29, No. 14, 2010 3207
mixture of toluene/hexane at 273 K to form a yellow solid, which
was separated by decantation, washed with hexane, and dried: yield
78 mg (66%). Anal. Calcd (%) for C27H35IrNO4P: C, 49.07; H,
5.34; N, 2.11. Found: C, 48.98; H, 5.17; N, 2.01. MS (MALDIþ, m/
z): 620 [Mþ - NCMe]. IR (KBr, cm-1): 2218 ν(NtC), 2099
(PMe3)]BF4 (6). Method A: CO was bubbled during 1 min
through a 0.5 mL CD2Cl2 solution of 4b (45 mg, 0.07 mmol)
in a NMR tube. Method B: A 5 mL CH2Cl2 solution of 2
(155 mg, 0.22 mmol) was placed under an atmosphere of CO (ca.
1 bar) and heated for 20 h at 323 K. The resulting solution was
dried to give a yellow residue. MS (FABþ, m/z (%)): 547 (65)
[Mþ - CO], 519 (100) [Mþ - 2CO]. IR (KBr, cm-1): 2118, 2084
ν(CtO), 1695 ν(OCO), 1024 ν(BF4). 1H NMR (CD2Cl2): δ 1.79
(m, 2H, CH2), 2.04 (d, 9H, JHP = 11.7, PMe3), 2.26, 2.31 (both
m, 1H each, CH2), 2.57 (m, 2H, CH2), 2.72, 2.77 (both m, 1H,
CH2), 2.81 (m, 1H, IrCH), 3.34 (m, 1H, CH), 3.70, 3.80 (both s,
3H each, OCH3), 5.47, 6.65 (both m, 1H each, dCH). 31P{1H}
(CD2Cl2): δ -25.14 (s). 13C{1H} NMR (CD2Cl2): δ 13.13 (d,
JCP = 44.7, PCH3), 19.07, 24.08 (both s, CH2), 31.52 (s, IrCH),
40.75 (d, JCP = 1.9, CH2), 46.34 (s, CH), 49.15, 49.38 (both s,
OCH3), 96.89 (d, JCP = 8.0, dCH), 106.86 (d, JCP = 6.0, dCH),
142.97 (d, JCP = 12.0, IrCdC), 144.48 (d, JCP = 4.2, IrCdC),
160.74 (d, JCP = 3.2, IrCO), 161.42 (d, JCP = 0.8, CO), 164.65
(d, JCP = 7.8, IrCO), 171.87 (d, JCP = 2.3, CO).
1
ν(CtC), 1690 (ν(OCO). H NMR (CD2Cl2, 253 K): δ 1.40 (m,
1H, CH2), 1.53 (m, 2H, CH2), 1.65 (d, JHP = 10.9, 9H, PCH3), 1.89
(m, 1H, CH2), 2.19 (m, 3H, 2 CH2 þ IrCH), 2.22 (s, 3H, NCCH3),
2.45, 2.53 (both m, 1H each, CH2), 2.65 (m, 1H, CH), 3.59, 3.71
(both s, 3H each, OCH3), 3.87, 5.48 (both m, 1H each, dCH), 7.22
(m, 5H, CH). 31P{1H} NMR (CD2Cl2, 253 K): δ -30.55 (s).
13C{1H} NMR (CD2Cl2, 253 K): δ 3.39 (s, NCCH3), 13.13 (d,
J
CP = 41.4, PCH3), 17.04 (d, JCP = 3.3, IrCH), 21.34, 22.60, 26.94
(all s, CH2), 40.38 (d, JCP = 2.3, CH2), 49.47 (s, CH), 50.50, 50.90
(both s, OCH3), 79.60 (d, JCP = 12.4, dCH), 95.40 (d, JCP
=
14.0, dCH), 96.56 (d, JCP = 20.2, IrCtCPh), 105.56 (d, JCP = 1.7,
IrCtCPh), 114.56 (s, NCCH3), 127.97 (s, CH), 129.88 (s, C),
130.75 (s, CH), 137.37 (d, JCP = 3.2, IrCdC), 164.01 (s, CO),
172.76 (d, JCP = 11.9, IrCdC), 178.02 (s, CO). The crystals used in
the X-ray experiment were obtained from a CH2Cl2 solution of 9
layered with hexane, at room temperature.
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(PMe3)3]BF4 (7). To a 5 mL CH2Cl2 solution of
2 (147 mg, 0.22 mmol) was added trimethylphosphine (57 μL,
0.53 mmol) using a microsyringe. The reaction mixture was
stirred at room temperature for 5 min, after which it was
concentrated to ca. 0.5 mL. The addition of diethyl ether
produced a yellow solid, which was separated by decantation,
washed with diethyl ether, and dried: yield 146 mg (90%). Anal.
Calcd (%) for C23H45BF4IrO4P3: C, 36.47; H, 5.99. Found: C,
36.79; H, 6.20. MS (FABþ, m/z (%)): 595 (56) [Mþ - PMe3]. IR
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(K2-O-acac)(PMe3)] (10). To a 5 mL acetone solu-
tion of 2 (309 mg, 0.45 mmol) was added potassium acetylace-
tonate (62 mg, 0.45 mmol). The reaction mixture was stirred at
room temperature for 2 h, after which it was taken to dryness.
The residue was dissolved in toluene and filtered through Celite.
The resulting solution was concentrated to ca. 0.5 mL and
treated with hexane to give a yellow solid. The solid was
separated by decantation, washed with hexane, and dried: yield
151 mg (54%). Anal. Calcd (%) for C22H34IrO6P: C, 42.78; H,
5.55. Found: C, 42.56; H, 5.83. MS (FABþ, m/z (%)): 618 (100)
[Mþ], 542 (90) [Mþ - PMe3]. IR (KBr, cm-1): 1706, 1677
ν(OCO), 1583, 1517 ν(acac). 1H NMR (CDCl3): δ 1.20 (m,
1H, CH2), 1.34 (d, JHP = 11.1, 9H, PCH3), 1.53, 1.64 (both m,
1H each, CH2), 1.69, 1.81 (both s, 3H each, CH3), 2.03 (m, 2H,
CH2), 2.12, 2.18, 2.31 (all m, 1H each, CH2), 2.61 (m, 1H, IrCH),
2.68 (m, 1H, CH), 3.63, 3.76 (both s, 3H each, OCH3), 4.64 (m,
1H, dCH), 5.07 (s, 1H, CH), 5.22 (m, 1H, dCH). 31P{1H} NMR
(CDCl3): δ -16.50 (s). 13C{1H} NMR (CDCl3): δ 10.65 (d,
1
(KBr, cm-1): 1697 ν(OCO), 1060 ν(BF4). H NMR (CD2Cl2):
δ 1.33 (d, JHP = 7.6, 9H, PCH3), 1.73 (d, JHP = 9.6, 9H, PCH3),
1.92 (d, JHP = 8.0, 9H, PCH3), 1.5-2.6 (m, CH2 þ IrCH þ CH),
3.66, 3.70 (both s, 3H each, OCH3), 4.33, 5.01 (both m, 1H each,
dCH). 31P{1H} NMR (CD2Cl2): δ -37.94 (dd, JPP = 26.5, 3.9),
-61.87 (dd, JPP = 14.4, 3.9), -62.38 (dd, JPP = 26.5, 14.4).
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(K2-N-bipy)(PMe3)]BF4 (8). To a 5 mL CH2Cl2
solution of 2 (134 mg, 0.19 mmol) was added 2,20-bipyridine
(30 μL, 0.19 mmol). The reaction mixture was stirred at room
temperature for 20 h, after which it was concentrated to ca.
0.5 mL. The addition of diethyl ether produced a yellow solid,
which was separated by decantation, washed with diethyl ether,
and dried: yield 99 mg (67%). Anal. Calcd (%) for C27H35BF4Ir-
N2O4P: C, 42.58; H, 4.63; N, 3.68. Found: C, 42.56; H, 4.73; N,
3.70. MS (MALDIþ, m/z): 675 [Mþ]. 1H NMR (CD2Cl2): δ 1.07
(d, JHP = 10.8, 9H, PCH3), 1.29, 1.48, 1.70, 1.75, 2.08, 2.39,
2.56, 2.62 (all m, 1H each, CH2), 2.80 (m, 1H, CH), 2.94 (m, 1H,
IrCH), 3.71, 3.91 (both s, 3H each, OCH3), 4.26, 4.43 (both m,
1H each, dCH), 7.66 (dd, JHH = 8.0, 5.2, 1H, CH), 7.86 (dd,
JCP = 38.8, PCH3), 13.15 (d, JCP = 3.3, IrCH), 22.38 (d, JCP
=
1.4, CH2), 22.78 (s, CH2), 25.96 (d, JCP = 0.9, CH2), 28.11, 28.21
(both s, CH3), 36.61 (d, JCP = 2.0, CH2), 48.63 (s, CH), 50.59,
50.81 (both s, OCH3), 99.26 (d, JCP=11.5, dCH), 99.47 (s, CH),
108.77 (d, JCP = 13.6, dCH), 137.11 (d, JCP = 2.9, IrCdC),
157.32 (d, JCP=11.2, IrCdC), 163.54 (d, JCP=1.1, CO), 177.19
(d, JCP=3.3, CO), 183.72, 187.01 (both s, CO).
Preparation of [Ir(1-K-C8H12-2-Z-{20-K-C(CO2Me)dC(CO2-
Me)})(K2-O-acac)(CO)(PMe3)] (11). CO was bubbled during 2
min through a 5 mL toluene solution of 10 (105 mg, 0.17 mmol).
The reaction was stirred at room temperature for 5 days, after
which it was concentrated to ca. 0.5 mL and treated with hexane.
The yellow solid formed was separated by decantation, washed
with hexane, and dried: yield 68 mg (62%). IR (KBr, cm-1):
2012 ν(CtO), 1704, 1691 ν(OCO), 1579, 1514 ν(acac). 1H NMR
(CD2Cl2): δ 1.35 (m, 1H, CH2), 1.56 (d, JHP = 11.4, 9H, PCH3),
1.75 (m, 1H, CH2), 1.93 (s, 3H, CH3), 1.95 (m, 1H, CH2), 1.98 (s,
3H, CH3), 2.03, 2.10, 2.18, 2.51 (all m, 1H each CH2), 2.60 (s,
1H, IrCH), 2.66 (m, 1H, CH2), 3.62, 3.74 (both s, 3H each,
OCH3), 3.94 (s, 1H, CH), 5.39 (s, 1H, CH), 5.48, 5.73 (both m,
1H each, dCH). 31P{1H} NMR (CD2Cl2): δ -33.92 (s). 13C{1H}
NMR (CD2Cl2): δ 12.44 (d, JCP = 43.9, PCH3), 25.73 (s, CH2),
26.90 (d, JCP = 6.4, CH3), 27.41 (s, CH2), 27.53 (s, CH3), 33.45
(d, JCP = 1.8, CH2), 33.83 (s, CH2), 42.01 (d, JCP = 4.4, IrCH),
48.33 (s, CH), 50.62, 50.83 (both s, OCH3), 100.70 (s, CH),
126.28, 132.20 (both s, dCH), 142.64 (d, JCP =9.3, IrCdC),
146.60 (s, IrCdC), 164.14 (s, CO), 175.19 (d, JCP=4.8, IrCO),
176.99 (s, CO), 186.00 (d, JCP=4.0, CO), 186.45 (s, CO). The
crystals used in the X-ray experiment were obtained by slow
evaporation at room temperature of a solution of 11 in toluene.
JHH = 8.0, 5.6, 1H, CH), 8.23 (dd, JHH = 8.0, 8.0, 1H, CH), 8.35
(dd, JHH = 8.0, 8.0, 1H, CH), 8.52 (d, JHH = 5.6, 1H, CH), 8.57
(d, JHH = 8.0, 1H, CH), 8.68 (d, JHH = 8.0, 1H, CH), 9.17 (d,
JHH = 5.2, 1H, CH). 31P{1H} NMR (CD2Cl2,): δ -28.76 (s).
13C{1H} NMR (CD2Cl2): δ 11.93 (d, JCP = 40.5, PCH3), 16.37
(d, JCP = 3.2, IrCH), 21.73, 22.03, 25.37, 35.93 (all s, CH2),
49.76 (s, CH), 51.39, 51.64 (both s, OCH3), 94.31 (d, JCP
11.0, dCH), 102.78 (d, JCP = 12.8, dCH), 124.78, 125.74,
127.96, 128.26, 139.92, 140.81 (all s, CH), 143.09 (d, JCP
=
=
4.1, IrCdC), 147.08 (d, JCP = 13.8, IrCdC), 150.35, 154.09
(both s, CH), 155.82, 156.82 (both s, C), 164.36 (d, JCP = 1.8,
CO), 176.21 (d, JCP = 3.7, CO).
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})(CtCPh)(NCMe)(PMe3)] (9). To a 5 mL THF
solution of 2 (124 mg, 0.18 mmol) was added lithium phenyla-
cetylide (23 mg, 0.20 mmol). The reaction mixture was stirred at
273 K for 90 min, after which some drops of wet acetone were
added to destroy the acetylide excess. The resulting suspension
was dried, and the residue was dissolved in CH2Cl2, filtered
through Celite, and dried again. The residue was treated with a

3208 Organometallics, Vol. 29, No. 14, 2010
Torres et al.
Preparation of [Ir(1-K-C8H12-2-Z-{20-K-C(CO2Me)dC(CO2-
Me)})(K2-O-acac)(PMe3)2] (12). To a 5 mL toluene solution of
10 (96 mg, 0.15 mmol) was added trimethylphosphine (16 μL,
0.15 mmol) using a microsyringe. The reaction mixture was stirred
at 353 K for 3 h, after which it was concentrated to ca. 0.5 mL and
treated with hexane. The yellow solid formed was separated by
decantation, washed with hexane, and dried: yield 69 mg (65%).
Anal. Calcd (%) for C25H43IrO6P2: C, 43.28; H, 6.25. Found: C,
43.33; H, 6.31. MS (FABþ, m/z (%)): 692 (15) [Mþ]. IR (KBr,
cm-1): 1707, 1680 ν(OCO), 1583, 1517 ν(acac). 1H NMR (toluene-
d8): δ 0.98 (d, JHP=7.7, 9H, PCH3), 1.17 (d, JHP=10.6, 9H, PCH3),
1.52 (s, 3H, CH3), 1.58 (m, 1H, CH2), 1.64 (s, 3H, CH3), 2.05 (m,
1H, CH2), 2.45 (m, 3H, CH2), 2.58, 2.82, 3.00 (all m, 1H each, CH2),
2.80 (m, 1H, IrCH), 3.44, 3.57 (both s, 3H each, OCH3), 4.18 (m,
1H, CH), 4.98 (s, 1H, CH), 5.70, 5.90 (both m, 1H each, dCH).
31P{1H} NMR (toluene-d8): δ -38.16, -31.23 (both d, JPP = 4.9).
13C{1H} NMR (toluene-d8): δ 13.17 (dd, JCP = 41.6, 3.2, PCH3),
14.27 (d, JCP = 19.7, PCH3), 26.51 (s, CH2), 26.81 (d, JCP = 6.2,
solution of KOH (1.67 M, 0.31 mmol). The reaction mixture was
stirred at 248 K for 15 min and dried. The residue was dissolved
in CH2Cl2, filtered through Celite, and treated with 2,20-bipyr-
idine (48 mg, 0.31 mmol). The reaction mixture was stirred for 10
min at room temperature, after which it was concentrated to ca.
0.5 mL and treated with hexane to give a dark red solid. The
solid was separated by decantation, washed with hexane, and
dried: yield 128 mg (62%). Anal. Calcd (%) for C27H36IrN2O4P:
C, 47.99; H, 5.37; N, 4.15. Found: C, 47.75; H, 5.15; N, 3.93. MS
(MALDIþ, m/z): 675 [Mþ - H]. IR (KBr, cm-1): 1700, 1670
ν(OCO). 1H NMR (CDCl3): δ 0.82 (d, JHP = 7.7, 9H, PCH3),
0.81 (m, 1H, CH2), 0.94 (m, 1H, IrCH), 1.44 (m, 1H, CH2), 1.53,
1.69 (m, 2H each, CH2), 2.02 (m, 1H, CH2), 2.24 (m, 2H, CH2),
2.34 (m, 1H, CH2), 3.04 (m, 1H, CH), 3.25 (m, 1H, IrCH), 3.65,
3.86 (both s, 3H each, OCH3), 7.32, 7.38, 7.82, 7.89 (all m, 1H
each, CH), 8.08 (d, JHH = 3.7, 1H, CH), 8.11 (d, JHH = 3.4, 1H,
CH), 9.00 (d, JHH = 5.5, 1H, CH), 9.33 (d, JHH = 5.7, 1H, CH).
31P{1H} NMR (CD2Cl2): δ -45.48 (s). 13C{1H} NMR (CDCl3):
CH3), 27.46 (s, CH3), 28.80 (d, JCP = 2.6, CH2), 34.23 (d, JCP
=
δ 8.42 (s, IrCH), 11.87 (d, JCP = 23.3, PCH3), 16.42 (d, JCP =
1.9, CH2), 34.65 (d, JCP=11.7, CH2), 37.85 (dd, JCP=92.7, 4.3,
IrCH), 48.02 (d,. JCP = 4.9, CH), 49.92, 50.03 (both s, OCH3),
100.75 (s, CH), 126.49, 132.07 (both s, dCH), 146.45 (d, JCP = 9.8,
IrCdC), 146.71 (d, JCP = 10.3, IrCdC), 163.65 (s, CO), 179.12 (d,
JCP = 2.3, CO), 182.79, 183.12 (both s, CO).
76.6, IrCH), 26.14, 28.38 (both s, CH2), 28.52 (d, JCP = 1.9,
CH2), 33.01 (d, JCP=2.9, CH2), 33.14 (d, JCP = 3.2, CH2), 50.51,
51.61 (both s, OCH3), 54.33, 121.92, 122.35, 124.80, 125.62,
134.21, 135.12 (all s, CH), 138.51 (d, JCP = 5.2, IrCdC), 150.89
(s, CH), 152.88 (d, JCP = 0.8, CH), 156.37 (s, C), 157.16 (d,
[Ir(1-K-5,6,7-η-C8H11-2-Z-{20-K-C(CO2Me)dC(CO2Me)})-
(CO)(PMe3)] (13). A 5 mL toluene solution of 11 (35 mg, 0.05
mmol) was placed under an atmosphere of CO (ca. 1 bar) and
heated for 48 h. at 353 K. The resulting solution was dried to give
a yellow residue, which was studied without further purification.
MS (FABþ, m/z (%)): 546 (92) [Mþ], 517 (100) [Mþ - CO]. IR
(CH2Cl2, cm-1): 1991 ν(CtO), 1701 ν(OCO). 1H NMR (C6D6):
δ 1.23 (d, JHP = 9.8, 9H, PCH3), 2.10, 2.65, 2.72, (all m, 1H each,
CH2), 2.78 (m, 2H, CH2), 3.05 (m, 1H, IrCH), 3.25 (m, 1H, CH),
3.52 (s, 3H, OCH3), 3.59 (m, 1H, CH), 3.65 (m, 1H, CH2), 3.73
(s, 3H, OCH3), 5.88, 6.10 (both m, 1H each, CH). 31P{1H} NMR
JCP = 1.4, C), 162.56 (d, JCP=11.8, IrCdC), 165.42 (d, JCP
2.7, CO), 180.95 (d, JCP = 2.5, CO).
=
Preparation of [Ir(η5-C5H5)(1-K-C8H12-2-Z-{20-K-C(CO2-
Me)dC(CO2Me)})(PMe3)] (16). To a 5 mL acetone solution
of 2 (131 mg, 0.19 mmol) was added cyclopentadienyl thallium (53
mg, 0.19 mmol). The reaction mixture was stirred at room tem-
perature for 3 h, after which the resulting suspension was filtered
through Celite and concentrated to ca. 0.5 mL. The addition of
hexane gave a yellow solid, which was separated by decantation,
washed with hexane, and dried: yield 67 mg (59%). Anal. Calcd (%)
for C22H32IrO4P: C, 45.27; H, 5.52. Found: C, 45.06; H, 5.22. MS
(FABþ, m/z (%)): 584 (53) [Mþ]. IR (KBr, cm-1): 1699, 1688
ν(OCO). 1H NMR (C6D6): δ 1.28 (d, JHP = 10.6, 9H, PCH3), 1.73,
1.93, 2.16, 2.22, 2.27, 2.64 (all m, 1H each, CH2), 2.80 (m, 1H,
IrCH), 2.85, 3.12 (both m, 1H each, CH2), 3.53, 3.73 (both s, 3H
each, OCH3), 3.88 (m, 1H, CH), 4.96 (d, 5H, JHP = 1.1, CH), 5.83,
5.94 (both m, 1H each, dCH). 31P{1H} NMR (C6D6):δ-31.33 (s).
13C{1H} NMR (C6D6): δ 16.93 (d, JCP =39.6, PCH3), 25.80 (s,
CH2), 26.30 (d, JCP = 5.9, IrCH), 30.53 (d, JCP = 1.9, CH2), 36.54,
40.82 (both s, CH2), 50.19, 50.28 (both s, OCH3), 51.26 (s, CH),
84.04 (d, JCP = 3.2, CH), 125.77, 131.82 (both s, dCH), 143.95 (s,
IrCdC), 151.72 (d, JCP = 12.8, IrCdC), 163.49 (d, JCP = 1.4, CO),
177.85 (d, JCP = 2.4, CO).
(C6D6): δ -59.24 (s). 13C{1H} NMR (C6D6): δ 18.60 (d, JCP
=
30.1, PCH3), 23.71, 28.20 (both s, CH2), 29.54 (d, JCP = 3.3,
CH2), 43.08 (d, JCP = 21.2, CH), 45.63 (d, JCP = 6.2, IrCH),
50.08 (s, OCH3), 50.32 (s, CH), 50.59 (s, OCH3), 130.72 (s, CH),
135.80 (d, JCP = 8.2, CH), 141.19 (d, JCP = 8.8, IrCdC), 149.79
(d, JCP = 14.1, IrCdC), 164.78 (d, JCP = 3.0, CO), 173.07 (d,
J
CP = 6.5, IrCO), 177.10 (s, CO).
Preparation of [Ir(1-K-5,6-η-C8H12-2-Z-{20-K-C(CO2Me)d
C(CO2Me)})H(NCMe)(PMe3)] (14). To a 5 mL methanol solu-
tion of 2 (111 mg, 0.16 mmol) was added 90 μL of another
methanol solution of KOH (1.67 M, 0.16 mmol). The reaction
mixture was stirred at 248 K for 15 min and dried. The residue
was dissolved in CH2Cl2, filtered through Celite, and dried
again. The new residue was treated with a mixture of toluene/
hexane to form a yellow solid, which was separated by decanta-
tion, washed with hexane, and dried: yield 85 mg (94%). Anal.
Calcd (%) for C19H31IrNO4P: C, 40.70; H, 5.57; N, 2.49. Found:
Preparation of [Ir(η5-C5H5)(1-K-C8H12-2-Z-{10,20-η-C(CO2-
Me)dCH(CO2Me)})(PMe3)]BF4 (17). To a 5 mL CH2Cl2 solu-
tion of 16 (149 mg, 0.25 mmol) was added 35 μL of a diethyl ether
solution of HBF4 (54%, 0.25 mmol). The reaction mixture was
stirred at room temperature for 10 min, after which it was concen-
trated to ca. 0.5 mL. The addition of diethyl ether gave a yellow
solid, which was separated by decantation, washed with diethyl
ether, and dried: yield 127 mg (75%). Anal. Calcd (%) for C22H33-
BF4IrO4P: C, 39.35; H, 4.95. Found: C, 39.24; H, 5.00. MS (FABþ,
m/z(%)):585(55) [Mþ]. 1HNMR(CD2Cl2):δ1.01 (m, 1H, IrCH),
1.46 (m, 1H, CH2), 1.87 (d, JHP=10.8, 9H, PCH3), 2.02, 2.16, 2.33,
2.35 (all m, 1H each, CH2), 2.35 (m, 1H, CH), 2.43, 2.64, 2.68 (all m,
1H each, CH2), 3.09 (d, JHP=13.8, 1H, CdCH(CO2CH3)), 3.71,
3.81 (both s, 3H each, OCH3), 5.50, 5.74 (both m, 1H each, dCH),
5.80 (s, 5H, CH). 31P{1H} NMR (CD2Cl2): δ -28.05 (s). 13C{1H}
NMR (CD2Cl2):δ-14.25 (d, JCP=4.3, IrCH), 16.14 (d, JCP=43.1,
PCH3), 26.85, 27.40, 30.48, 36.66 (all s, CH2), 39.98 (d, JCP=3.1,
CdCH(CO2CH3)), 43.47 (d, JCP=4.1, CdCH(CO2CH3)), 50.78
(s, CH), 52.91, 53.49 (both s, OCH3), 95.25 (d, JCP = 1.4, CH),
128.18, 131.16 (both s, dCH), 169.05, 170.65 (both s, CO).
X-ray Crystallography. X-ray data were collected at 100.0(2)
K on a Bruker SMART APEX CCD with graphite-monochro-
C, 40.21; H, 5.29; N, 2.35. MS (MALDIþ, m/z): 519 [Mþ
-
NCMe]. IR (KBr, cm-1): 1960 ν(IrH), 1690 ν(OCO). 1H NMR
(CD2Cl2, 253 K): δ -11.58 (d, JHP = 26.7, 1H, IrH), 1.39, 1.52
(both m, 2H, each, CH2), 1.56 (d, JHP = 10.4, 9H, PCH3), 1.69
(m, 1H, IrCH), 2.03 (m, 2H, CH2), 2.11 (s, 3H, NCCH3), 2.26,
2.55 (both m, 1H each, CH2), 2.60 (m, 1H, CH), 2.75 (m, 1H,
dCH), 3.57, 3.69 (both s, 3H each, OCH3) 4.75 (m, 1H, dCH).
31P{1H} NMR (CD2Cl2, 253 K): δ -34.52 (s). 13C{1H} NMR
(CD2Cl2, 253 K): δ 3.10 (s, NCCH3), 16.32 (d, JCP = 3.7, IrCH),
16.41 (d, JCP = 38.5, PCH3), 20.90 (d, JCP = 1.9, CH2), 22.99,
29.63 (both s, CH2), 42.82 (d, JCP = 2.2, CH2), 49.44 (s, CH),
50.14, 50.76 (both s, OCH3), 59.83 (d, JCP = 16.3, dCH), 69.62
(d, JCP = 11.9, dCH), 113.98 (s, NCCH3), 135.19 (d, JCP = 3.4,
IrCdC), 163.91 (d, JCP = 2.0, CO), 178.58 (d, JCP = 1.5, CO),
181.26 (d, JCP = 12.2, IrCdC).
Preparation of [Ir(1,5-K-C8H13-2-Z-{20-K-C(CO2Me)dC(CO2-
Me)})(K2-N-bipy)(PMe3)] (15). To a 5 mL methanol solution of
2 (211 mg, 0.31 mmol) was added 180 μL of another methanol
˚
mated Mo KR radiation (λ = 0.71073 A). Data were collected

Article
Organometallics, Vol. 29, No. 14, 2010 3209
over the complete sphere by a combination of four sets. Data
were corrected for absorption by using a multiscan method
applied with the SADABS program.21 The structures were solved
by the Patterson method and refined by full-matrix least-squares
on F2 using the Bruker SHELXTL program package,22 includ-
ing isotropic and subsequently anisotropic displacement
parameters. Weighted R factors (Rw) and goodness of fit (S )
are based on F2, and conventional R factors are based on
F. Hydrogen atoms were calculated using a restricted riding
model on their respective carbon atoms with the thermal
parameter related to the bonded atom. All the highest electronic
residuals were observed in close proximity to the Ir centers and
make no chemical sense.
Crystal data for 9: C27H35IrNO4P CH2Cl2, M = 745.66;
3
colorless needle, 0.16 ꢀ 0.02 ꢀ 0.02 mm3; monoclinic, P21/c;
˚
˚
˚
a=11.4457(11) A, b=12.3481(12) A, c=20.3787(19) A, β=
95.733(2)°; Z = 4; V = 2865.8(5) A ; Dc = 1.728 g cm-3; μ =
3
˚
4.936 mm-1, minimum and maximum transmission factors
0.5056 and 0.9077; 2θmax =58.02; 24 502 reflections collected,
6917 unique [R(int)=0.0961]; number of data/restraints/para-
meters 6917/4/354; final GoF 0.630, R1 = 0.0406 [3772 reflec-
tions I > 2σ(I)], wR2=0.0640 for all data; largest difference peak
-3
˚
1.530 e A
.
Crystal data for 11: C23H34IrO7P, M = 645.67; colorless
laminar prism, 0.18 ꢀ 0.10 ꢀ 0.06 mm3; monoclinic, P21/c;
˚
˚
˚
a=8.839(3) A, b=34.989(11) A, c=8.603(3) A, β=114.591(6)°;
3
Z=4; V = 2.419.3(13) A ; Dc=1.773 g cm-3; μ=5.625 mm-1
,
˚
Crystal data for 2: C21H33BF4IrN2O4P CH2Cl2, M = 709.35;
colorless irregular block, 0.24 ꢀ 0.20 ꢀ 0.16 mm3; monoclinic,
3
minimum and maximum transmission factors 0.4308 and
0.7289; 2θmax = 57.82°; 16 285 reflections collected, 5837 unique
[R(int)=0.0393]; number of data/restraints/parameters 5837/0/
311; final GoF 0.817, R1 = 0.0297 [4365 reflections I > 2σ(I )],
˚
˚
˚
P21/c; a = 18.5507(19) A, b = 8.8012(9) A, c = 17.5506(18) A,
β=97.040(2)°; Z=4; V=2843.9(5) A ; Dc=1.804 g cm-3; μ=4.996
3
˚
mm-1, minimum and maximum transmission factors 0.3802 and
0.5020; 2θmax = 57.74; 34 371 reflections collected, 6996 unique
[R(int) = 0.0381]; number of data/restraints/parameters 6996/0/
355; final GoF 0.942, R1 = 0.0281 [5375 reflections I > 2σ(I)],
-3
˚
wR2=0.0430 for all data; largest difference peak 1.56 e A
.
Acknowledgment. This work was supported by the
Spanish MICINN (Grants CTQ2009-08023 and Consolider
Ingenio 2010 INTECAT CSD2006-0003).
-3
˚
wR2 = 0.0584 for all data; largest difference peak 2.29 e A
.
(21) Blessing, R. H. Acta Crystallogr. 1995, A51, 33–38. SADABS:
Area-Detector Absorption Correction; Bruker-AXS: Madison, WI, 1996.
(22) SHELXTL Package v. 6.10; Bruker-AXS: Madison, WI, 2000.
Supporting Information Available: X-ray crystallographic file
for complexes 2, 9, and 11 in CIF format. This material is
available free of charge via the Internet at http://pubs.acs.org.
€
Sheldrick, G. M. SHELXS-86 and SHELXL-97; University of Gottingen:
€
Gottingen, Germany, 1997.