Ruthenium half-sandwich complexes with sterically demanding cyclopentadienyl ligands

Article abstract of DOI:10.1021/om700461x

A chloro-bridged Ru^III complex of formula [Cp ^∧RuCl₂]₂ (Cp^∧ = η⁵-1-methoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl) (1) was obtained in a single step by reaction of [RuCl₃(solv)_n] with tert-butylacetylene in methanol. Complex 1 showed polymorphism and crystallized in two distinct forms: an isomer, 1a, with no significant metal-metal interactions (Ru...Ru = 3.684(1) or 3.743(1) A) and an isomer, 1b, in which the Ru atoms are 2.960(2) A apart from each other. In solution, a temperature-dependent equilibrium between the two isomers is established. When the reaction of [RuCl₃(solv)_n] with tert-butylacetylene was carried out in ethanol, the chloro-bridged dimer 2, with an ethoxy instead of a methoxy group attached to the cyclopentadienyl ligand, was formed. Complex 1 was found to be a versatile starting material for the synthesis of mononuclear half-sandwich complexes. With phosphine ligands or norbornadiene (nbd), the 16 e^- complexes [Cp ^∧RuCl(PCy₃)] (3), [Cp^∧RuCl(PPh ₃)] (4), and [Cp^∧RuCl-(PnBu₃)] (5), the 17 e^- complex [Cp^∧RuCl₂(PPh₃)] (7), and the 18 e^- complexes [Cp^∧RuX(PPh ₂RPPh₂)] (X = H, Cl; R = CH₂, C ₂H₄; 8-11) and [Cp^∧RuCl(nbd)] (12) were obtained. Crystallography analyses show that the Ru-P bond lengths in these complexes are longer than in corresponding pentamethylcyclopentadienyl complexes.

Full text of DOI:10.1021/om700461x

Organometallics 2007, 26, 4791-4799
4791
Ruthenium Half-Sandwich Complexes with Sterically Demanding
Cyclopentadienyl Ligands
Barnali Dutta, Euro Solari, Se´bastien Gauthier, Rosario Scopelliti, and Kay Severin*
Institut des Sciences et Inge´nierie Chimiques, EÄ cole Polytechnique Fe´de´rale de Lausanne (EPFL),
CH-1015 Lausanne, Switzerland
ReceiVed May 10, 2007
A chloro-bridged RuIII complex of formula [Cp∧RuCl2]2 (Cp∧ ) η5-1-methoxy-2,4-tert-butyl-3-
neopentylcyclopentadienyl) (1) was obtained in a single step by reaction of [RuCl3(solv)n] with tert-
butylacetylene in methanol. Complex 1 showed polymorphism and crystallized in two distinct forms: an
isomer, 1a, with no significant metal-metal interactions (Ru‚‚‚Ru ) 3.684(1) or 3.743(1) Å) and an
isomer, 1b, in which the Ru atoms are 2.960(2) Å apart from each other. In solution, a temperature-
dependent equilibrium between the two isomers is established. When the reaction of [RuCl3(solv)n] with
tert-butylacetylene was carried out in ethanol, the chloro-bridged dimer 2, with an ethoxy instead of a
methoxy group attached to the cyclopentadienyl ligand, was formed. Complex 1 was found to be a versatile
starting material for the synthesis of mononuclear half-sandwich complexes. With phosphine ligands or
norbornadiene (nbd), the 16 e- complexes [Cp∧RuCl(PCy3)] (3), [Cp∧RuCl(PPh3)] (4), and [Cp∧RuCl-
(PnBu3)] (5), the 17 e- complex [Cp∧RuCl2(PPh3)] (7), and the 18 e- complexes [Cp∧RuX(PPh2RPPh2)]
(X ) H, Cl; R ) CH2, C2H4; 8-11) and [Cp∧RuCl(nbd)] (12) were obtained. Crystallographic analyses
show that the Ru-P bond lengths in these complexes are longer than in corresponding pentamethylcy-
clopentadienyl complexes.
cyclopentadienyl ligand.1 To tune the reactivity, numerous co-
ligands have been employed such as phosphines, olefins, halides,
nitriles, and thiolates.1-9 Structural modifications of the cyclo-
pentadienyl ligand, however, are not very common, and many
investigations have focused on Cp and Cp* complexes. The
dominance of Cp and Cp* ligands can be explained by the fact
that easily accessible starting materials are available. The
cationic acetonitrile complex [CpRu(CH3CN)3](PF6) and the
chloro-bridged dimer [Cp*RuCl2]2 turned out to be particulartly
useful. The latter can be obtained in a one-step procedure from
[RuCl3(H2O)n] by refluxing with C5Me5H in methanol.10 For
the former, the conventional route involves photolysis of [CpRu-
(benzene)]+ in CH3CN.11 More recently, an efficient synthesis
has been developed where the final step does not require
photolysis.12 Both complexes are commercially available as well.
Introduction
Ruthenium half-sandwich complexes with cyclopentadienyl
ligands represent a very important class of catalysts.1 The
organic reactions catalyzed by these complexes include allylic2
and propargylic3 substitutions, cycloadditions,4 isomerizations,5
hydrogenations,6 alkane borylations,7 and atom-transfer radical
addition8 and polymerization9 reactions. For many of these the
success of the catalytic process has been attributed to the electron
richness of the ruthenium center or the steric hindrance of the
* Corresponding author. E-mail: kay.severin@epfl.ch.
(1) (a) Trost, B. N.; Frederiksen, M. U.; Rudd, M. T. Angew. Chem.,
Int. Ed. 2005, 44, 6630-6666. (b) Murahashi, S. I. Ruthenium in Organic
Synthesis; Wiley-VCH: Weinheim, 2004. (c) Bruneau, C.; Dixneuf, P. H.
Ruthenium Catalysts and Fine Chemistry; Springer: Berlin, 2004. (d)
De´rien, S.; Dixneuf, P. H. J. Organomet. Chem. 2004, 689, 1382-1392.
(e) Trost, B. M.; Toste, F. D.; Pinkerton, A. B. Chem. ReV. 2001, 101,
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12, 5178-5187. (b) Renaud, J. L.; Demerseman, B.; Mbaye, M. D.;
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S.-I., Ed.; Wiley-VCH: Weinheim, 2004, pp 309.
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Hartwig, J. F. J. Am. Chem. Soc. 2006, 128, 13684-13685.
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L.; Demonceau, A.; Noels, A. F. Top. Organomet. Chem. 2004, 11, 155-
171.
In a recent communication we have reported the synthesis
of the RuIII half-sandwich complexes 1 and 2, which have an
overall structure analogous to [Cp*RuCl2]2 but possess very
distinct 1-alkoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl
ligands (alkoxy ) MeO or EtO).13 These complexes are easily
accessible in a one-step reaction of [RuCl3(solv)n] with tert-
(10) (a) Fagan, P. J.; Ward, M. D.; Calabrese, J. C. J. Am. Chem. Soc.
1989, 111, 1698-1719. (b) Tilley, T. D.; Grubbs, R. H.; Bercaw, J. E.
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159-175. (b) Kamigaito, M.; Ando, T.; Sawamoto, M. Chem. ReV. 2001,
101, 3689-3746.
10.1021/om700461x CCC: $37.00 © 2007 American Chemical Society
Publication on Web 08/08/2007

4792 Organometallics, Vol. 26, No. 19, 2007
Dutta et al.
Scheme 1
butylacetylene (Scheme 1). First investigations had shown that
the dimeric RuIII complexes 1 and 2 can be transformed into
mononuclear RuII complexes.13 In the following, we describe
detailed investigations about this new class of compounds. It is
shown that the structure and the reactivity of 1 and 2 parallel
to some extent that of [Cp*RuCl2]2 but that the sterically
demanding 1-alkoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl
ligands favor the formation of electronically unsaturated 16 e-
complexes. The latter characteristic could be of importance for
future catalytic applications.
Results and Discussion
Complex 1 was obtained in the form of a brown precipitate
when a solution of commercial [RuCl3(H2O)n] in methanol and
tert-butylacetylene was heated at 55 °C. The yield of this
reaction did not exceed 35%, regardless of the absolute or the
relative concentrations. Further investigations revealed that the
presence of water was detrimental for the yield. We therefore
thought to reduce the water content of the starting material
[RuCl3(H2O)n]. This was achieved by dissolving [RuCl3(H2O)n]
in THF and distilling off the solvent. With the resulting [RuCl3-
(solv)n] it was possible to prepare complex 1 in 51% yield
(Scheme 1). When the reaction was performed in ethanol instead
of methanol, the ethoxy complex 2 was obtained in 40% yield.
We had reported that complex 1 crystallizes as a chloro-
bridged dimer.13 Two crystallographically independent but
structurally very similar complexes were observed in the crystal.
The Ru‚‚‚Ru distances of these dimers were 3.684(1) and 3.743-
(1) Å, indicating no significant metal-metal interaction (isomer
1a, Figure 1). Interestingly, we were able to obtain a second
type of crystal for complex 1 (isomer 1b). A crystallographic
analysis revealed a chloro-bridged dimer, in which the Ru atoms
are 2.960(2) Å apart from each other (Figure 1). This value is
in agreement with a metal-metal bond.
Figure 1. Graphic representation of the molecular structures of
complex 1a (top) (ref 13), 1b (middle), and 2 (bottom) in the crystal.
Thermal ellipsoids are at the 50% probability level. Hydrogen atoms
are not shown for clarity.
has been observed in the solid state.14 The complex [CpRuCl2]2
likewise shows a metal-metal bond with a length of 2.7748(6)
Å, although the cyclopentadienyl ligands adopt a cis and not a
trans configuration.17 The observation of both isomers of
complex 1 by crystallography is thus rather exceptional. Since
the two different crystals were obtained from the same solvent
methanol, it appeared likely that in solution the isomers 1a and
1b are in a dynamic equilibrium, similar to what had been
observed for [Cp*RuCl2]2. This was substantiated by 1H NMR
studies of complex 1 at variable temperatures (CD2Cl2), which
showed a strong temperature dependence of the chemical shifts
and a sharpening of some signals at - 50 °C.
A related phenomenon has been observed for [Cp*RuCl2]2.
This complex was initially believed to be an oligomer,10 but a
crystallographic study by Ko¨lle and co-workers showed that it
is a dimer with two µ-Cl bridges.14 Within the same crystal,
they observed two distinct complexes with Ru‚‚‚Ru distances
of 2.930(1) and 3.752(1) Å. Further experimental investigations
showed that in CD2Cl2 solution there is an equilibrium between
a paramagnetic species and diamagnetic dimer with antiferro-
magnetically coupled Ru(III) centers.14,15 A recent theoretical
study concluded that [Cp*RuCl2]2 is a rare system that fulfills
the criteria of bond-stretch isomerism.16 It is interesting to note
that for the structurally related complexes [(C5Me4Et)RuCl2]2
and [Cp*RuBr2]2 only the isomer with short Ru‚‚‚Ru distances
(13) Gauthier, S.; Solari, E.; Scopelliti, R.; Dutta, B.; Severin, K. Chem.
Commun. 2007, 1837-1839.
Complex 2 was likewise investigated by X-ray crystal-
lography. Its structure is analogous to that of isomer 1b, with
(14) Ko¨lle, U.; Kossakowski, J.; Klaff, N.; Wesemann, L.; Englert, U.;
Heberich, G. E. Angew. Chem., Int. Ed. Engl. 1991, 30, 690-691.
(15) Koelle, U.; Lueken, H.; Handrick, K.; Schilder, H.; Burdett, J. K.;
Balleza, S. Inorg. Chem. 1995, 34, 6273-6278.
(17) Ferna´ndez, I.; Pregosin, P. S.; Albinati, A.; Rizzato, S. Organome-
tallics 2006, 25, 4520-4529.
(16) McGrady, J. E. Angew. Chem., Int. Ed. 2000, 39, 3077-3079.

Ruthenium Half-Sandwich Complexes
Organometallics, Vol. 26, No. 19, 2007 4793
Table 1. Selected Distances (Å) and Angles (deg) for
Complexes 1a, 1b, and 2
Scheme 2
1aa
1b
2
Ru‚‚‚Ru
3.6840, 3.7431
2.358, 2.354
2.437, 2.446
2.443, 2.447
81.99(9), 80.20(9)
98.01(9), 99.80(9)
2.960(2)
2.408(3)
2.370(3)
2.381(3)
102.92(9)
77.08(9)
2.9768(5)
2.4151(9)
2.3721(8)
2.3829(9)
102.49(3)
77.51(3)
Ru-Clt
Ru-Clb
Ru-Clb′
Clb-RuClb′
Ru-Clb-Ru′
a Data from ref 13.
presence of Zn, deep violet solutions were obtained, from which
the highly air-sensitive complex [Cp∧RuCl(PCy3)] (Cp∧ ) η5-
1-methoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl) (3) was
a short Ru‚‚‚Ru distance of 2.9768(5) Å (Figure 1). As observed
for both 1a and 1b, the dimer 2 has a crystallographic inversion
center. A summary of the key structural data of complexes 1a,
1b, and 2 is given in Table 1.
1
isolated (Scheme 2). The H NMR spectrum of 3 (CD2Cl2)
showed three strong singlets between 1.1 and 1.5 ppm, which
can be attributed to the tert-butyl groups. As a consequence of
the planar chirality of 3, the methylene CH protons of the
neopentyl side chain are diastereotopic and appear as two
doublets at 2.75 and 3.23 ppm. The 31P{1H} NMR displayed a
single signal indicating the coordination of only one phosphine
ligand. Further characterization by elemental analysis and single-
crystal X-ray analysis (see below) confirmed the formation of
the 16 e- complex 3. The structurally related complex [Cp∧RuCl-
(PPh3)] (4) was obtained when PPh3 was used instead of PCy3
(Scheme 2). The reaction can be performed at room temperature,
but slightly better yields were obtained at elevated temperatures.
Crystallization from concentrated hexane solutions gave violet
crystals of complex 4, which are well soluble in nonpolar
solvents and very air sensitive. Structurally related complexes
of formula [Cp*RuCl(PR3)] are known with sterically demand-
ing phosphine ligands such as PCy3 and PiPr3.21 However, the
attempted preparation of mononuclear [Cp*RuCl(PPh3)] failed
and resulted in the formation of an insoluble polymer.22 The
successful preparation of complex 4 is thus direct evidence that
the sterically demanding Cp∧ ligand is able to stabilize
electronically unsaturated complexes, which are not accessible
with the widely used Cp* ligand. In this context it is interesting
to note that for the 18 e- complex [Cp*RuCl(PPh3)2], a
frequently used catalyst, the dissociation of a phosphine ligand
is often regarded as the key step to generate the catalytically
active species.1,23 In situ 31P NMR experiments showed that
the saturated complex [Cp∧RuCl(PPh3)2] is not formed, even if
an excess of PPh3 was added to a solution of complex 4 in
THF.
The formation of complexes 1 and 2 requires the coupling
of three tert-butylacetylenes with methanol or ethanol under
elimination of HCl. There are examples of transition metal-
mediated [2+2+1] cyclotrimerizations of alkynes,18,19 but they
are very rare compared to the more common [2+2+2] cyclo-
trimerizations.1,4 The coupling of three alkynes and an alcohol
giving a cyclopentadienyl ligand with an alkoxy substituent
directly attached to the ring issto the best of our knowledges
unprecedented. A plausible mechanism for this reaction could
involve an intramolecular reaction of a metallacyclopentadiene
with a vinylidene ligand.18a The formation of a fulvene
π-complex, which was suggested for other [2+2+1] cyclotri-
merizations of alkynes, appears unlikely in our case since the
nucleophilic attack of the alcohol would occur at the exocyclic
carbon atom.19
Attempts to substitute tert-butylacetylene with other alkynes
such as phenylacetylene, cyclohexylacetylene, or trimethylsi-
lylacetylene were not successful. When reacted with [RuCl3-
(solv)n], a mixture of unidentified products was obtained. This
was not entirely unexpected. A complicated multicomponent
reaction of this kind is likely to depend strongly on the size
and the reactivity of the alkyne. Furthermore, it was known that
(cyclopentadienyl)Ru half-sandwich complexes (including
[Cp*RuCl2]2)20 can react further with alkynes to give cycload-
dition products or polymers.1,4 It is conceivable, however, that
complexes with a structure analogous to 1 and 2 can be obtained
for other alkyne/alcohol combinations, given that a careful
optimization of the reaction conditions is carried out.
The molecular structure of complex 3 shows the expected
two-legged piano stool geometry (Figure 2). Both, the Ru-P
bond (2.4188(9) Å) and the Ru-Cl bond (2.3936(9) Å) are
slightly longer than what has been observed for the related
complex [Cp*RuCl(PCy3)] (Ru-P ) 2.3834(4) Å; Ru-Cl )
The structural similarity of complexes 1 and 2 with
[Cp*RuCl2]2 suggested that they should be suitable starting
materials for the synthesis of mononuclear RuII complexes. This
proved to be indeed the case. In a first series of experiments,
we investigated the reaction of complex 1 with various
phosphines. When 1 was reacted with PCy3 in THF in the
(21) (a) Huang, J.; Stevens, E. D.; Nolan, S. P.; Peterson, J. L. J. Am.
Chem. Soc. 1999, 121, 2674-2678. (b) Johnson, T. J.; Folting, K.; Streib,
W. E.; Martin, J. D.; Huffman, J. C.; Jackson, S. A.; Eisenstein, O.; Caulton,
K. G. Inorg. Chem. 1995, 34, 488-499. (c) Luo, L.; Nolan, S. P.
Organometallics 1994, 13, 4781-4786. (d) Arliguie, T.; Border, C.;
Chaudret, B.; Devillers, J.; Poilblanc, R. Organometallics 1989, 8, 1308-
1314. (e) Campion, B. K.; Heyn, R. H.; Tilley, T. D. Chem. Commun. 1988,
278-280.
(18) (a) Chin, C. S.; Lee, H. Chem.-Eur. J. 2004, 10, 4518-4522. (b)
Becker, E.; Mereitner, K.; Puchberger, M.; Schmid, R.; Kirchner, K.;
Doppiu, A.; Salzer, A. Organometallics 2003, 22, 3164-3170. (c)
Radhakrishnan, U.; Gevorgyan, V.; Yamamoto, Y. Tetrahedron Lett. 2000,
41, 1971-1974. (d) Kim, H. J.; Choi, N. S.; Lee, S. W. J. Organomet.
Chem. 2000, 616, 67-73. (e) Burrows, A. D.; Green, M.; Jeffery, J. C.;
Lynam, J. M.; Mahon, M. F. Angew. Chem., Int. Ed. 1999, 38, 3043-
3045. (f) Johnson, E. S.; Balaich, G. J.; Fanwick, P. E.; Rothwell, I. P. J.
Am. Chem. Soc. 1997, 119, 11086-11087. (g) O’Connor, J. M.; Hiibner,
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3631-3632. (h) Moran, G.; Green, M.; Orpen, A. G. J. Organomet. Chem.
1983, 250, C15-C20.
(19) (a) Lim, M. S.; Baeg, J. Y.; Lee, S. W. J. Organomet. Chem. 2006,
691, 4100-4108. (b) Han, W. S.; Lee, S. W. Organometallics 2005, 24,
997-1003.
(20) For the reaction of [Cp*RuCl2]2 with alkynes see: (a) Fukuyama,
T.; Yamaura, R.; Higashibeppu, Y.; Okamura, T.; Ryu, I.; Kondo, T.;
Mitsudo, T. A. Org. Lett. 2005, 7, 5781-5783. (b) Yamaguchi, I.; Osakada,
K.; Yamamoto, T. Inorg. Chim. Acta 1994, 220, 35.
(22) Braun, T.; Mu¨nch, G.; Windmu¨ller, B.; Gevert, O.; Laubender, M.;
Werner, H. Chem.-Eur. J. 2003, 9, 2516-2530.
(23) For selected examples see: (a) Pedro, F. M.; Santos, A. M.; Baratta,
W.; Ku¨hn, F. E. Organometallics 2007, 26, 302-309. (b) Miura, Y.; Shibata,
T.; Satoh, K.; Kamigaito, M.; Okamoto, Y. J. Am. Chem. Soc. 2007, 128,
16026-16027. (c) Majireck, M. M.; Weinreb, S. M. J. Org. Chem. 2006,
71, 8680-8683. (d) Zhang, Li.; Chen, X.; Xue, P.; Sun, H. H. Y.; Williams,
I. D.; Sharpless, K. B.; Fokin, V. V.; Jia, G. J. Am. Chem. Soc. 2005, 127,
15998-15999. (e) Tutusaus, O.; Delfosse, S.; Demonceau, A.; Noels, A.
F.; Nu´n˜ez, R.; Vin˜as, C.; Teixidor, F. Tetrahedron Lett. 2002, 43, 983-
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4794 Organometallics, Vol. 26, No. 19, 2007
Dutta et al.
at 1.5 and 14.9 ppm, demonstrating that two PnBu3 ligands of
complex 6 undergo exchange reactions. Furthermore, when an
excess of PnBu3 was employed in the reaction with 1, the two
doublets of complex 6 were already resolved at room temper-
ature (Figure 3e). This is in agreement with Le Chatelier’s
principle according to which a higher concentration of the
phosphine will shift the equilibrium to the right. When only 2
equiv of PnBu3 were used with respect to the dimer 1, the 31P-
{1H} NMR spectrum showed the peak of [Cp∧RuCl(PnBu3)]
(5) at 16.85 ppm (Figure 3f). These data demonstrate that the
PnBu3 ligand allows accessing both the electronically unsatur-
ated monophosphine complex 5 and the saturated bisphosphine
complex 6. For Cp*Ru complexes, an analogous situation was
found for the PMeiPr2 ligand. It was observed that [Cp*RuCl-
(PMeiPr2)] and [Cp*RuCl(PMeiPr2)2] are accessible depending
on the phosphine to [Cp*RuCl]4 ratio.24 Thereafter, the size of
PMeiPr2 can be regarded as the lower limit, which allows the
stabilization of [Cp*RuCl(PR3)] species. For the Cp∧ ligand it
is possible to access a 16 e- complex with the significantly
smaller phosphine PnBu3.
Figure 2. Graphic representation of the molecular structure of
complex 3 in the crystal. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms are not shown for clarity.
Selected bond lengths (Å) and angles (deg): Ru-P 2.4188(9), Ru-
Cl 2.3936(9); P-Ru-Cl 91.40(3).
The THF solution of complex 5 showed the typical blue-
violet color, which is characteristic for electronically unsaturated
[(cyclopentadienyl)RuCl(PR3)] complexes.21,24 When the THF
was removed under vacuum, a red solid was obtained. Redis-
solving this complex in THF or toluene gave again the blue-
violet color. Solutions in hexane, however, were red and showed
a
31P{1H} NMR spectrum that was clearly different from that
in THF (hexane: δ ) 10.30 ppm; THF: δ ) 15.30 ppm). These
observations can be explained by assuming that in the solid state
and in hexane complex 5 exists in the form of a chloro-bridged
dimer (Scheme 3). An equilibrium between the monomer and
a chloro-bridged dimer has also been observed for [Cp*RuCl-
(PMeiPr2)].24
Figure 3. 31P{1H} NMR spectra of a THF solution obtained from
the reaction of 1 with 4 equiv of PnBu3 recorded at 25 °C (a),
10 °C (b), -10 °C (c), and -30 °C (d). Spectrum “e” was obtained
at 25 °C from a reaction with an excess of PnBu3, and spectrum
“f” was obtained at -30 °C from a reaction with 2 equiv of PnBu3
with respect to 1.
Scheme 3
2.3776(5) Å).21a The PCy3 ligand is oriented toward the sterically
less crowded side of the Cp∧ ligand.
When complex 1 was reacted with the less bulky phosphine
PnBu3, a more complicated situation was encountered. With the
aim to prepare a complex analogous to the known [Cp*RuCl-
(PnBu3)2], we have reacted a THF solution of complex 1 with
4 equiv of PnBu3 in the presence of Zn. After workup, the 31P-
{1H} NMR spectrum (THF) showed a broad singlet at 15.30
ppm (Figure 3a). Upon cooling, the singlet transformed into a
pair of doublets at 15.66 and 1.73 ppm (2JPP ) 35 Hz) along
with a small singlet at 17.00 pm and a broad singlet at ca.
-22.00 ppm (Figure 3b-d). The two doublets in the low-
temperature spectra can be attributed to complex [Cp∧RuCl-
(PnBu3)2] (6), having two diastereotopic P atoms due to the
planer chirality of the cyclopentadienyl ligand. The singlet at
17.00 ppm is proposed to belong to the 16 e- complex
[Cp∧RuCl(PnBu3)] (5), which is in a dynamic equilibrium with
complex 6 and free PnBu3. This interpretation is supported by
Recently, we had reported that the RuIII complex [Cp*RuCl2-
(PPh3)] can be used as a catalyst precursor for highly efficient
atom-transfer radical addition reactions.25 We were therefore
interested to see whether we could prepare the analogous Cp∧
complex. Paramagnetic [Cp*RuCl2(PR3)] complexes are gener-
ally obtained by reaction of [Cp*RuCl2]2 with 2 equiv of PR3
at ambient temperature.21d,26 However, a similar reaction of
(24) Jime´nez Tenorio, M.; Puerta, M. C.; Valerga, P. J. Organomet.
Chem. 2000, 609, 161-168.
(25) (a) Thommes, K.; Ic¸li, B.; Scopelliti, R.; Severin, K. Chem.-Eur.
J. 2007, DOI: 10.1002/chem.200700442. (b) Quebatte, L.; Thommes, K.;
Severin, K. J. Am. Chem. Soc. 2006, 128, 7440-7441.
a
31P{1H}-31P{1H} exchange spectrum, performed at 10 °C
with a mixing time (τm) of 20 ms, which showed cross-peaks
(26) Arliguie, T.; Chaudret, B. Chem. Commun. 1986, 13, 985-986.

Ruthenium Half-Sandwich Complexes
Organometallics, Vol. 26, No. 19, 2007 4795
Figure 4. Graphic representation of the molecular structure of
complex 7 in the crystal. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms are not shown for clarity.
Selected bond lengths (Å) and angles (deg): Ru-P 2.3819(12),
Ru-Cl 2.3888(10), Ru-Cl′ 2.3722(11); P-Ru-Cl 82.22(4),
P-Ru-Cl′ 87.15(4), Cl-Ru-Cl1 98.69(4).
Figure 5. Graphic representation of the molecular structures of
complexes 8 (a), 9 (b), 10 (c), and 11 (d) in the crystal. Thermal
ellipsoids are at the 50% probability level. Hydrogen atoms are
not shown for clarity.
Scheme 4
Scheme 5
complex 1 with PPh3 in CH2Cl2 resulted in the formation of a
mixture of [Cp∧RuCl(PPh3)] (4) and [Cp∧RuCl2(PPh3)] (7)
(Scheme 4). The complexes could be separated by extraction
of the diamagnetic RuII complex 4 with hexane. Complex 7
was then obtained in 64% yield.
When complex 1 was reacted with dppm or dppe in THF at
room temperature in the presence of Zn, the 18 e- complexes
8 and 9 were obtained (Scheme 5). The coordination of two P
atoms to one metal center was clearly evidenced by the
31P{1H} NMR spectra, which showed a pair of doublets for the
two diastereotopic P atoms. Apparently, the energetic advantage
of the five- or four-membered chelate is sufficient to overcome
the steric protection provided by the bulky Cp∧ ligand. Fol-
lowing a synthetic procedure developed for Cp*Ru complexes,27j
the chloro compounds 8 and 9 were converted into the hydride
complexes 10 and 11 by reaction with NaOMe in MeOH
(Scheme 4). The hydride ligands give rise to distinct {1H} NMR
signals at -7.0 and -14.0 ppm, respectively.
In addition to NMR studies, the complexes 8-11 were
characterized by single-crystal X-ray analysis (Figure 5). Tables
2 and 3 give some key structural data along with the values of
the related Cp*Ru complexes [Cp*RuCl(dppm)],27e [Cp*RuCl-
(dppe)],27e and [Cp*RuH(dppe)].28a The comparison shows that
the Ru-P bond lengths found for the Cp∧ complexes are
consistently longer than those of the Cp* complexes. Yet again,
this can be explained by the increased steric demand of the
Cp∧ ligand.
A crystallographic analysis of complex 7 confirmed the
formation of a mononuclear complex with one PPh3 and two
chloro ligands opposite the Cp∧ ligand (Figure 4). At 2.3819-
(12) Å, the Ru-P bond length of 7 is longer than what has
been found for [Cp*RuCl2(PPh3)] (Ru-P ) 2.3506(2) Å).25a
Most likely as a result of the increased steric demand of the
Cp∧ ligand, the Cl-Ru-Cl′ and Cl-Ru-P angles found for 7
(98.69(4)°, 82.22(4)°, and 87.15(4)°) are smaller than those of
[Cp*RuCl2(PPh3)] (101.335(4)°, 86.509(4)°, and 91.156(4)°).
Next we have investigated the reaction of 1 with the chelating
phosphine ligands bis(diphenylphosphino)methane (dppm) and
bis(diphenylphosphino)ethane (dppe). In view of the observation
that the triphenylphosphine complex [Cp∧RuCl(PPh3)] (4) did
not show any tendency to add another PPh3 ligand, it was
interesting to see whether electronically saturated chelate
complexes or 16 e- complexes with one noncoordinated
phosphine group would form. An additional incentive to study
the reactions with dppm and dppe was the fact that the Cp*Ru
complexes with these ligands have found numerous applications
in organometallic synthesis27 and catalysis.28
Reaction of 1 with norbornadiene (nbd) in ethanol at 55 °C
gave complex [Cp∧RuCl(nbd)] (12) in 60% yield (Scheme 5).
Complex 12 was characterized by NMR spectroscopy, elemental
analysis, and X-ray crystallography (Figure 6). The accessibility
of 12 is of interest in view of the fact that the Cp* complexes
[Cp*RuCl(nbd)] and [Cp*RuCl(cod)] (cod ) 1,5-cyclooctadi-
ene) have been used extensively as catalysts for various organic
(27) (a) Belkova, N. V.; Dub, P. A.; Baya, M.; Houghton, J. Inorg. Chim.
Acta 2007, 360, 149-162. (b) Singh, K. S.; Thoene, C.; Kollipara, M. R.
J. Organomet. Chem. 2005, 690, 4222-4231. (c) Morandini, F; Munari,
I.; Panese, M.; Ravazzolo, A.; Consiglio, G. Inorg. Chim. Acta. 2005, 358,
2697-2700. (d) Aneetha, H.; Jime´nez Tenorio, M.; Puerta, M. C.; Valerga,
P.; Mereiter, K. Organometallics 2003, 22, 1779-1782. (e) Bruce, M. I.;
Ellis, B. G.; Low, P. J.; Skelton, B. W.; White, A. H. Organometallics
2003, 22, 3184-3198. (f) Law, J. K.; Mellows, H.; Heinekey, D. M. J.
Am. Chem. Soc. 2002, 124, 1024-1030. (g) Sato, M.; Kawata, Y.; Shintate,
H.; Habata, Y.; Akabori, S.; Unoura, K. Organometallics 1997, 16, 1693-
1701. (h) Jia, G.; Lough, A. J.; Morris, R. H. Organometallics 1992, 11,
161-171. (i) Kirchner, K.; Mauthner, K.; Mereiter, K.; Schmid, R. Chem.
Commun. 1993, 892-894. (j) Jia, G.; Morris, R. H. J. Am. Chem. Soc.
1991, 113, 875-883.
(28) (a) Guan, H.; Limura, M.; Magee, M. P.; Norton, J. R.; Zhu, G. J.
Am. Chem. Soc. 2005, 127, 7805-7814. (b) Guan, H.; Saddoughi, S. A.;
Shaw, A. P.; Norton, J. R. Organometallics 2005, 24, 6358-6364. (c)
Magee, M. P.; Norton, J. R. J. Am. Chem. Soc. 2001, 123, 1778-1779.

4796 Organometallics, Vol. 26, No. 19, 2007
Dutta et al.
Table 2. Selected Distances (Å) and Angles (deg) for the Chloro Complexes 8 and 9, in Comparison with [Cp*RuCl(dppm)]
and [Cp*RuCl(dppe)]
8
[Cp*RuCl(dppm)]a
9
[Cp*RuCl(dppe)]a
Ru-Cl
Ru-P
2.4567(15)
2.3289(16)
2.3459(16)
71.32(6)
2.434(2)
2.282(2)
2.294(2)
71.53(6)
2.452(2)
2.353(3)
2.360(3)
82.22(9)
2.4532(5)
2.2882(5)
2.2812(5)
82.15(2)
Ru-P′
P-Ru-P′
a Data from ref 27e.
Table 3. Selected Distances (Å) and Angles (deg) for the
Hydrido Complexes 10 and 11 in Comparison with
[Cp*RuH(dppe)]
Conclusion
The chloro-bridged RuIII complexes 1 and 2 with η5-1-
methoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl (Cp∧) and
η5-1-ethoxy-2,4-tert-butyl-3-neopentylcyclopentadienyl ligands
can be easily obtained in a one-pot reaction from [RuCl3(solv)n]
and tert-butylacetylene in methanol or ethanol, respectively. The
methoxy complex [Cp∧RuCl2]2 (1) shows an unusual type of
polymorphism: in one crystalline form, the two Ru atoms are
bonded, whereas in the other form, they are not. The facile
accessibility of 1 and 2 makes them highly interesting starting
materials for the synthesis of novel Ru half-sandwich complexes.
Reactions of 1 with phosphine ligands and with nbd demonstrate
that mononuclear complexes are rapidly obtained. For potential
applications in the field of catalysis it is of special interest that
the Cp∧ ligand is sterically more demanding than the classical
Cp* ligand. Consequently, it is easier to stabilize electronically
unsaturated 16 e- complexes.
10
11
[Cp*RuH(dppe)]a
Ru-H
1.57(3)
1.574(19)
2.2433(14)
2.2601(13)
84.19(5)
1.59(2)
Ru-P
2.2531(11)
2.2652(11)
72.18(4)
2.2363(6)
2.2291(6)
83.73
Ru-P′
P-Ru-P′
a Data from ref 28a.
Experimental Section
General Procedures. All experiments were performed inside a
glovebox under an atmosphere of dinitrogen containing less than
1 ppm of oxygen and water. Thoroughly dried and deoxygenated
solvents were used. PPh3, PnBu3, nbd, cod, and NaOMe were
purchased from Fluka. Metallic Zn and dppm were commercial
products from Aldrich. tert-Butylacetylene was purchased from Alfa
Aesar and dppe from Acros Organics. PCy3 was obtained from
Strem Chemicals and RuCl3(H2O)n from Precious Metals Online.
Figure 6. Graphic representation of the molecular structure of
complex 12 in the crystal. Thermal ellipsoids are at the 50%
probability level. Hydrogen atoms are not shown for clarity.
Selected bond lengths (Å) and angles (deg): Ru-Cl 2.4738(10),
Ru-C20 2.265(3), Ru-C22 2.259(4), Ru-C23 2.226(3), Ru-C25
2.234(4); Cl-Ru-C25 78.28(9), Cl-Ru-C23 77.46(9).
Scheme 6
1
All chemicals were used as received, unless otherwise stated. H,
13C, and 31P NMR spectra were recorded on a Bruker spectrometer
at 400 MHz. The deuterated solvents CD2Cl2, C6D5CD3, and C6D6
(from Aldrich) for NMR experiments were degassed by three
freeze-pump-thaw cycles and then purified by vacuum transfer
at room temperature. The following numbering scheme was used
for the assignment of the 13C NMR data:
transformations.1,29 However, we did not succeed in preparing
the analogous cyclooctadiene complex [Cp∧RuCl(cod)]. The
difficulty in synthesizing this complex could be related to the
fact that the larger cod ligand is blocked by the bulky
Cp∧ ligand. A comparison of the structural data of complex 12
with that of [Cp*RuCl(nbd)]30 shows that the Ru-Cl bond and
the average distance of the Ru to the olefinic carbons atoms
are longer for complex 12 (12: Ru-Cl ) 2.4738(10) Å, Ru-
Cnbd ) 2.246 Å; [Cp*RuCl(nbd)]: Ru-Cl ) 2.443(2) Å, Ru-
Cnbd ) 2.18 Å). This reinforces the assumption that the cod
could not be coordinated due to steric hindrance from the Cp∧.
[Cp∧RuCl2]2 (1). [RuCl3(H2O)n] (500 mg, 1.90 mmol) was
dissolved in 25 mL of THF with heating, and then the solvent was
distilled off at 72 °C, normal pressure, using a Rotavapor. Complete
removal of the solvent at this temperature led to a green, insoluble
material. Hence, the last portion (5 mL) of the solvent was removed
under high vacuum. The procedure was repeated, and then the
resulting solid (reddish-brown in color) was dissolved in 10 mL of
dry MeOH under nitrogen followed by the addition of tert-
butylacetylene (1.0 mL, 8.0 mmol). The closed flask was heated at
55 °C for 24 h and then kept at -20 °C for 24 h to ensure complete
precipitation. The solid brown precipitate was isolated, washed with
MeOH (3.0 mL) followed by hexane (3.0 mL), and dried under
vacuum. Yield: 434 mg (51%). Anal. Calcd for C38H66Cl4O2Ru2:
C, 50.78; H, 7.40. Found: C, 50.47; H, 7.36. Single crystals were
(29) For recent examples see: (a) Yamamoto, Y.; Kinpara, K.; Ogawa,
R.; Nishiyama, H.; Itoh, K. Chem.-Eur. J. 2006, 12, 5618-5631. (b)
Villeneuve, K.; Tam, W. Organometallics 2006, 25, 843-848. (c) Ville-
neuve, K.; Tam, W. Eur. J. Org. Chem. 2006, 5449-5453. (d) Jordan, R.
W.; Villeneuve, K.; Tam, W. J. Org. Chem. 2006, 71, 5830-5833. (e) Liu,
P.; Jordan, R. W.; Kibbee, S. P.; Goddard, J. D.; Tam, W. J. Org. Chem.
2006, 71, 3793-3803.
(30) Lubia´n, R. T.; Paz-Sandoval, M. A. J. Organomet. Chem. 1997,
532, 17-29.

Ruthenium Half-Sandwich Complexes
Organometallics, Vol. 26, No. 19, 2007 4797
Table 4. Crystallographic Data for Complexes 1b, 2, and 3
1b
2
3‚THF
C41H74ClO2PRu
empirical formula
mol weight/g mol-1
cryst size/mm3
cryst syst
space group
a/Å
C38H66Cl4O2Ru2
898.85
C40H70Cl4O2Ru2
926.90
766.49
0.30 × 0.18 × 0.16
0.28 × 0.20 × 0.08
monoclinic
C2/c
27.5514(19)
8.0923(6)
0.53 × 0.17 × 0.12
triclinic
monoclinic
P1h
8.1010(12)
9.105(3)
P21/c
10.9422(17)
22.462(4)
b/Å
c/Å
15.473(4)
102.44(3)
101.329(18)
100.876(19)
1060.5(5)
20.1765(14)
90
95.420(6)
16.763(2)
90
102.942(12)
90
R/deg
â/deg
γ/deg
90
volume/Å3
4478.4 (5)
4015.5(11)
Z
1
4
4
density/g cm-3
temperature/K
absorp coeff/mm-1
θ range/deg
1.407
140(2)
0.993
1.375
140(2)
0.943
1.268
100(2)
0.529
3.04 to 25.02
-9 f 9, -10 f 10, -18 f 18
6898
3508 (Rint ) 0.0774)
semiempirical
1.0078 and 0.7995
3508/0/210
3.27 to 25.02
-32 f 32, -9 f 9, -21 f 22
12 085
3823 (Rint ) 0.0384)
semiempirical
0.9664 and 0.7047
3823/0/217
1.072
3.32 to 25.03
-13 f 13, -26 f 26, -19 f 19
43 157
7043 (Rint ) 0.0815)
semiempirical
1.0000 and 0.7203
7043/0/415
index ranges
no. of reflns collected
no. of indep reflns
absorp corr
max. & min. transmn
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
larg diff peak and hole/e Å-3
1.081
1.138
R1 ) 0.0923, wR2 ) 0.2385
R1 ) 0.1043, wR2 ) 0.2537
4.916 and -1.643
R1 ) 0.0366, wR2 ) 0.0840
R1 ) 0.0448, wR2 ) 0.0882
0.921 and -0.935
R1 ) 0.0443, wR2 ) 0.0635
R1 ) 0.0744, wR2 ) 0.0719
0.478 and -0.434
obtained from cold methanol.[(η5-1-Ethoxy-2,4-tert-butyl-3-
neopentylcyclopentadienyl)RuCl2]2 (2). The synthesis was per-
formed analogously to that of complex 3 using ethanol (20 mL)
instead of methanol. Yield: 365 mg (40%). Anal. Calcd for
C40H70Cl4O2Ru2: C, 51.83; H, 7.61. Found: C, 51.30; H, 7.31.
[Cp∧RuCl(PCy3)] (3). PCy3 (62.3 mg, 222 µmol) and excess
Zn dust were added to a solution of complex 1 (100 mg, 111 µmol)
in THF (5 mL) and stirred at ambient temperature for 12 h. The
color of the solution changed from brown to violet. The solution
was filtered followed by complete removal of the solvent under
high vacuum. Hexane was added and removed under vacuum to
ensure complete removal of the THF. The product was then
extracted with hexane (5 mL), while the ZnCl2 formed during
reaction remained as a white solid. The product was obtained by
δ (ppm) 7.32-7.52 (m, 15 H, PPh3), 3.59 (s, 1 H, Cp-H), 3.22
2
2
(d, 1 H, CH2, JHH ) 16 Hz), 2.75 (d, 1 H, CH2, JHH ) 16 Hz),
2.63 (s, 3 H, OCH3), 1.46 (s, 9 H, t-Bu), 1.22 (s, 9 H, t-Bu), 1.10
(s, 9 H, t-Bu). 31P{1H} NMR (CD2Cl2, -20 °C): δ (ppm) 35.08
(s, 1 P, PPh3). 13C{1H} NMR (CD2Cl2, -20 °C): δ (ppm) 129-
136 (Ph), 120.04 (C13), 88.11, 83.43, 80.24 (C10, C11, C12), 57.73
(C9), 56.88 (C8), 37.02 (C7), 34.88, 32.97, 32.19 (C4, C5, C6),
33.30, 32.39, 31.98 (C1, C2, C3). Anal. Calcd for C37H48ClOPRu:
C, 65.71; H, 7.15. Found: C, 65.88; H, 7.05. Single crystals were
obtained from a solution of complex 4 in hexane.
[Cp∧RuCl(PnBu3)] (5). PnBu3 (55 µL, 222 µmol) and excess
Zn dust were added to a solution of complex 1 (100 mg, 111 µmol)
in THF (10 mL), and the mixture was stirred at 65 °C for 12 h.
The color of the solution changed from brown to blue-violet. The
solution was filtered followed by complete removal of the solvent
under high vacuum. Hexane was added and removed under vacuum
to ensure complete removal of the THF. The product was then
extracted with toluene (5 mL), while the ZnCl2 formed during
reaction remained as a white solid. The product was obtained by
removing the toluene under high vacuum. Yield: 64 mg (94%).
1H NMR (C6D5CD3, 25 °C): δ (ppm) 4.21 (s, 1 H, Cp-H), 4.19
1
removing the hexane under vacuum. Yield: 153 mg (99%). H
NMR (CD2Cl2, 25 °C): δ (ppm) 4.15 (s, 1 H, Cp-H), 3.55 (s, 3 H,
OCH3), 3.23, (d, 1 H, CH2, 2JHH ) 16 Hz), 2.75 (d, 1 H, CH2, 2JHH
) 16 Hz), 1.47 (s, 9 H, t-Bu), 1.34 (s, 9 H, t-Bu), 1.15 (s, 9 H,
t-Bu), 1.16-2.20 (m, 30 H, PCy3). 31P{1H} NMR (CD2Cl2,
25 °C): δ (ppm) 35.39 (s, 1 P, PCy3). 13C{1H} NMR (CD2Cl2,
25 °C): δ (ppm) 121.25 (C13), 83.72, 81.92, 81.10 (C10, C11,
C12), 61.10 (C9), 54.14 (C8), 39.31 (C7), 34.60, 34.52, 33.43 (C4,
C5, C6), 35.14, 34.27, 33.92 (C1, C2, C3), 29.0-38.0 (PCy3). Anal.
Calcd for C37H66ClOPRu: C, 64.00; H, 9.58. Found: C, 63.97; H,
9.44. Single crystals were obtained by slow evaporation from a
solution of complex 3 in CH2Cl2/hexane.
2
(d, 1 H, CH2, JHH ) 16 Hz), 3.53 (s, 3 H, OCH3), 3.06 (d, 1 H,
CH2, 2JHH ) 16 Hz), 2.06 (m, 6 H, PCH2CH2CH2CH3), 1.89 (s, 9
H, t-Bu), 1.65 (m, 6 H, PCH2CH2CH2CH3), 1.60 (s, 9 H, t-Bu),
1.53 (m, 6 H, PCH2CH2CH2CH3), 1.33 (s, 9 H, t-Bu), 1.12 (t, 9 H,
3
PCH2CH2CH2CH3, JHH ) 7 Hz). 31P{1H} NMR (C6D5CD3,
[Cp∧RuCl(PPh3)] (4). Excess metallic Zn was added to a
solution of complex 1 (100 mg, 111 µmol) in THF (5 mL) and
stirred for 5 min at ambient temperature followed by the addition
of PPh3 (58.3 mg, 222 µmol). The reaction mixture was then stirred
at 55 °C until the color of the solution became violet and no excess
PPh3 was detected in the 31P NMR (after nearly 45 min). The Zn
was filtered off, and the solvent was removed under vacuum.
Hexane (2 mL) was added, and the mixture was stirred for 5 min
and evaporated to ensure complete removal of the THF. The product
was then extracted with several portions of hexane, while the ZnCl2
formed during reaction remained as a white solid. The product was
obtained by removing the hexane under vacuum. Yield: 72 mg
(48%). The NMR spectra of the complex were recorded at -20 °C
because broad peaks were observed at RT (25 °C), possibly due to
25 °C): δ (ppm) 15.58 (s, 1 P, PnBu3). 13C{1H} NMR (C6D5CD3,
25 °C): δ (ppm) 82.48, 79.65, 79.53 (C10, C11, C12), 57.83 (C9),
52.73 (C8), 38.37 (C7), 34.85, 33.17, 32.57 (C4, C5, C6), 33.32,
32.66, 32.27 (C1, C2, C3), 27.80, 26.10, 25.98, 14.83 (PnBu3). Anal.
Calcd for C37H48ClOPRu: C, 60.41; H, 9.81. Found: C, 60.09; H,
10.20.
[Cp∧RuCl2(PPh3)] (7). PPh3 (29.2 mg, 111 µmol) was added
to a solution of complex 1 (100 mg, 111 µmol) in CH2Cl2 (10 mL),
and the mixture was stirred at ambient temperature for 24 h. The
color of the solution turned purple-red. The solvent CH2Cl2 was
completely removed under vacuum, and the solid was thoroughly
washed with hexane until the washings were no longer violet.
Complex 7 was obtained as a red solid and dried under high
vacuum. Yield: 100 mg (64%). Anal. Calcd for C37H48Cl2OPRu:
1
hindered rotation of the π-ligand. H NMR (CD2Cl2, -20 °C):

4798 Organometallics, Vol. 26, No. 19, 2007
Table 5. Crystallographic Data for Complexes 7, 8, and 9
Dutta et al.
7
8
9‚0.5 THF
C47H61ClO1.5P2Ru
empirical formula
mol weight/g mol-1
cryst size/mm3
cryst syst
C37H48Cl2OPRu
711.69
C44H55ClOP2Ru
798.34
848.42
0.23 × 0.15 × 0.10
0.35 × 0.19 × 0.17
0.30 × 0.22 × 0.16
monoclinic
P21/n
monoclinic
monoclinic
space group
P21/n
P21/n
a/Å
b/Å
c/Å
10.254(3)
22.984(4)
14.983(2)
90
98.176(17)
90
3495.1(12)
4
25.177(3)
12.1663(11)
27.959(4)
90
107.204(8)
90
8181.3(16)
8
25.021(4)
12.680(3)
27.431(5)
90
105.612(16)
90
8382(3)
8
1.345
100(2)
0.550
3.30 to 25.01
-29 f 29, -11 f 15, -32 f 32
53 204
14 406 (Rint ) 0.1381)
semiempirical
1.0000 and 0.9297
14 406/35/946
R/deg
â/deg
γ/deg
volume/Å3
Z
density/g cm-3
temperature/K
absorp coeff./mm-1
θ range/deg
1.353
140(2)
0.675
1.296
100(2)
0.558
2.88 to 25.03
-12 f 12, -27 f 27, -17 f 17
22 058
5988 (Rint ) 0.0807)
semiempirical
0.7807 and 0.7673
5988/0/379
3.32 to 25.00
-29 f 29, -14 f 14, -33 f 33
86 845
14 323 (Rint ) 0.1191)
semiempirical
1.0000 and 0.7089
14 323/0/883
1.134
index ranges
no. of reflns collected
no. of indep reflns
absorp corrr
max. & min. transmn
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
larg diff peak and hole/e Å-3
0.859
1.071
R1 ) 0.0367, wR2 ) 0.0495
R1 ) 0.0804, wR2 ) 0.0606
0.637 and -0.602
R1 ) 0.0609, wR2 ) 0.1021
R1 ) 0.1249, wR2 ) 0.1283
1.058 and -0.928
R1 ) 0.0838, wR2 ) 0.1553
R1 ) 0.1780, wR2 ) 0.2001
1.333 and -0.862
1
C, 62.44; H, 6.80. Found: C, 62.50; H, 6.82. Crystals of the
complex 7 were obtained from a solution of CH2Cl2.
C3), 30.47, 30.42 (dppe). [NMR data obtained from H, 13C{1H},
31P{1H}, and H(F2)-13C(F1) HSQC experiments]. Anal. Calcd
1
[Cp∧RuCl(dppm)] (8). dppm (85.5 mg, 222 µmol) and excess
metallic zinc were added to a solution of complex 1 (100 mg, 111
µmol) in THF (5 mL), and the mixture was stirred at ambient
temperature for 24 h. The color of the solution changed from brown
to bright orange. The solution was then filtered followed by the
removal of THF under reduced pressure. Methanol (4 mL) was
added to dissolve the ZnCl2 formed during reduction. An orange
powder was collected by filtration, which was washed thoroughly
with methanol. Yield: 145 mg (82%). 1H NMR (C6D6, 25 °C): δ
for C45H57ClOP2Ru: C, 66.53; H, 7.07. Found: C, 66.45; H, 7.08.
Orange-yellow crystals of complex 9 were obtained by slow
evaporation of a hexane/THF solution.
[Cp∧RuH(dppm)] (10). Complex 8 (75.0 mg, 94 µmol) was
taken in 10 mL of methanol, and an excess of NaOMe (20 mg)
was added. The resulting mixture was stirred at room temperature
for 1 h. The yellow solid formed during the reaction was collected
by filtration, washed thoroughly with methanol, and dried under
high vacuum. Yield: 65 mg (90%). 1H NMR (CD2Cl2, 25 °C): δ
(ppm) 7.2-7.8 (m, 20 H, 4 Ph), 4.86 (s, 1 H, Cp-H), 4.72, 3.89
(m, 2 H, dppm), 3.41 (s, 3 H, OCH3), 3.13 (d, 1H, CH2, 2JHH ) 16
Hz), 2.93 (d, 1 H, CH2, 2JHH ) 16 Hz), 1.16 (s, 9 H, t-Bu), 1.15 (s,
9 H, t-Bu), 1.13 (s, 9 H, t-Bu), -11.38 (dd, 1 H, Ru-H, 2JPH ) 32,
2JPH ) 32 Hz). 31P{1H} NMR (C6D6, 25 °C): δ (ppm) 14.90 (d, 1
P, dppe, 2JPP ) 68 Hz), 14.37 (d, 1 P, dppe, 2JPP ) 68 Hz). 13C{1H}
(CD2Cl2, 25 °C): δ (ppm) 128-141 (4 Ph), 136.05 (C13), 104.88,
96.48, 91.83 (C10, C11, C12), 60.64 (C9), 57.68 (C8), 40.94 (C7),
34.17, 33.85, 33.67 (C4, C5, C6), 34.09, 33.81, 33.53 (C1, C2,
C3), 28.74 (dppm). Anal. Calcd for C45H58OP2Ru: C, 69.18; H,
7.39. Found: C, 68.69; H, 6.69. Orange-yellow crystals of complex
10 were obtained by slow evaporation of a MeOH solution.
2
(ppm) 6.85-8.30 (m, 20 H, 4Ph), 4.71 (ddd, 1 H, P-CH2-P, JHH
2
2
) 22, JPH ) 11, JPH ) 11 Hz), 4.58 (s, 1 H, Cp-H), 4.33 (ddd,
2
2
2
1 H, P-CH2-P, JHH ) 19, JPH ) 9, JPH ) 9 Hz), 3.36 (d, 1 H,
CH2, 1JHH ) 17 Hz), 2.96 (d, 1 H, CH2, 1JHH ) 17 Hz), 2.76 (s, 3
H, OCH3), 1.93 (s, 9 H, t-Bu), 1.43 (s, 9 H, t-Bu), 1.39 (s, 9 H,
t-Bu). 31P{1H} NMR (C6D6, 25 °C): δ (ppm) 5.20 (d, 1 P, dppm,
2JPP ) 41), -1.50 (d, 1 P, dppm, 2JPP ) 41). 13C{1H} NMR (C6D6,
25 °C): δ (ppm) 130.0-142.0 (4 Ph), 132.53 (C13), 106.32, 98.37,
92.17 (C10, C11, C12), 58.32 (C9), 56.11 (C8), 41.19 (C7), 36.73,
36.16, 35.67 (C4, C5, C6), 36.35, 35.95 (C1, C2, C3), 33.72 (dppm).
Anal. Calcd for C44H55ClOP2Ru: C, 66.19; H, 6.94. Found: C,
66.36; H, 7.07. Orange crystals of complex 8 were obtained by
slow evaporation of a hexane solution.
[Cp∧RuH(dppe)] (11). Complex 9 (75.0 mg, 92 µmol) was taken
in 10 mL of methanol, and excess (20 mg) sodium methoxide was
added. The resulting mixture was stirred at room temperature for
1 h. The yellow solid formed during the reaction was collected by
filtration, washed thoroughly with methanol, and dried under high
vacuum. Yield: 66 mg (89%). 1H NMR (CD2Cl2, 25 °C): δ (ppm)
7.2-8.0 (m, 20 H, 4 Ph), 4.63 (s, 1 H, Cp-H), 3.20 (s, 3 H, OCH3),
2.0-2.4 (m, 6 H, dppe, CH2), 1.25 (s, 9 H, t-Bu), 0.89 (s, 9 H,
t-Bu), 0.88 (s, 9 H, t-Bu), -13.87 (dd, 1 H, Ru-H, 2JPH ) 35, 2JPH
) 35 Hz). 31P{1H} NMR (C6D6, 25 °C): δ (ppm) 84.19 (d, 1 P,
dppe, 2JPP ) 11 Hz), 83.45 (d, 1 P, dppe, 2JPP ) 11 Hz). 13C{1H}
(CD2Cl2, 25 °C): δ (ppm) 128-146 (4 Ph), 136.05 (C13), 105.19,
96.66, 93.28 (C10, C11, C12), 62.10 (C9), 57.22 (C8), 39.37 (C7),
33.99, 33.95 (C4, C5, C6), 34.16, 33.62, 33.36 (C1, C2, C3), 36.27,
36.13 (dppe). Anal. Calcd for C45H58OP2Ru: C, 69.47; H, 7.51.
Found: C, 69.67; H, 7.34. Orange-yellow crystals of complex 11
were obtained by slow evaporation of a MeOH solution.
[Cp∧RuCl(dppe)] (9). dppe (88.7 mg, 222 µmol) and excess
metallic zinc were added to a solution of complex 1 (100 mg, 111
µmol) in THF (5 mL), and the mixture was stirred at ambient
temperature for 24 h. The color of the solution changed from brown
to orange-yellow. The solution was then filtered followed by
removal of THF under reduced pressure. Methanol (4 mL) was
added to dissolve the ZnCl2 formed during reduction. The solution
was filtered to obtain an orange-yellow powder, which was washed
1
with methanol. Yield: 144 mg (80%). H NMR (CD2Cl2, 25 °C):
δ (ppm) 7.2-8.0 (m, 20 H, 4 Ph), 4.43 (s, 1 H, Cp-H), 3.18 (s, 3
H, OCH3), 2.85 (m, 2 H, CH2), 2.27 (m, 2 H, PCH2CH2P), 2.71
(m, 2 H, PCH2CH2P), 1.26 (s, 9 H, t-Bu), 1.19 (s, 9 H, t-Bu), 1.03
(s, 9 H, t-Bu). 31P{1H} NMR (C6D6, 25 °C): δ (ppm) 63.79 (d, 1
P, dppe, 2JPP ) 8 Hz), 63.25 (d, 1 P, dppe, 2JPP ) 8 Hz). 13C{1H}
(CD2Cl2, 25 °C): δ (ppm) 128-143 (4 Ph), 132.88 (C13), 106.23,
94.00, 93.35 (C10, C11, C12), 58.00 (C9), 56.13 (C8), 39.76 (C7),
34.88, 34.57, 32.85 (C4, C5, C6), 33.98, 33.01, 32.62 (C1, C2,

Ruthenium Half-Sandwich Complexes
Organometallics, Vol. 26, No. 19, 2007 4799
Table 6. Crystallographic Data for Complexes 10, 11, and 12
10 11
12‚hexane
C32H55ClORu
empirical formula
mol weight/g mol-1
cryst size/mm3
cryst syst
C44H56OP2Ru
763.90
C45H58OP2Ru
777.92
592.28
0.48 × 0.30 × 0.25
0.56 × 0.31 × 0.31
0.36 × 0.30 × 0.23
monoclinic
monoclinic
monoclinic
space group
P21/n
P21/c
C2/c
a/Å
10.8194(9)
16.2705(19)
28.378(6)
b/Å
24.2560(18)
12.6160(10)
15.705(3)
c/Å
14.9797(5)
19.209(3)
14.595(3)
R/deg
90
95.803(6)
90
3911.0(5)
90
90
â/deg
97.415(10)
90
3910.0(8)
113.41 (3)
90
5970(2)
γ/deg
volume/Å3
Z
4
4
8
density/g cm-3
temperature/K
absorp coeff/mm-1
θ range/deg
1.297
140(2)
0.515
2.86 to 25.03
-12 f 12, -28 f 27, -17 f 17
23 164
6886 (Rint ) 0.0785)
semiempirical
1.0059 and 0.8315
6886/0/436
1.322
100(2)
0.516
1.318
100(2)
0.637
3.39 to 25.03
-33 f 33, -18 f 18, -17 f 17
58 560
5268 (Rint ) 0.0888)
semiempirical
1.0000 and 0.8712
5268/42/325
3.40 to 25.03
-19 f 19, -15 f 15, -22 f 22
64 646
6877 (Rint ) 0.1194)
semiempirical
1.0000 and 0.5970
6877/19/445
index ranges
no. of reflns collected
no. of indep reflns
absorp corr
max. & min. transmn
no. of data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
larg diff peak and hole/e Å-3
0.779
1.142
1.113
R1 ) 0.0413, wR2 ) 0.0550
R1 ) 0.0978, wR2 ) 0.0646
0.800 and -0.776
R1 ) 0.0630, wR2 ) 0.1530
R1 ) 0.0824, wR2 ) 0.1663
2.325 and -1.947
R1 ) 0.0412, wR2 ) 0.0748
R1 ) 0.0607, wR2 ) 0.0819
0.683 and -0.601
[Cp∧RuCl(nbd)] (12). Norbornadiene (50 µL, 445 mmol) was
added to a solution of complex 1 (100 mg, 111 µmol) in ethanol
(5 mL) and stirred at 55 °C. The color of the solution changed
from brown to light orange. After 3 h, some faint white precipitate
appeared. After 6 h, the solution was filtered to remove the
precipitate. The EtOH solution was concentrated under reduced
pressure to give the product in the form of an orange, microcrys-
talline material. The product was washed with ethanol and dried
under vacuum. Yield: 67 mg (60%). 1H NMR (CD2Cl2, 25 °C): δ
(ppm) 5.19 (m, 1 H, CHdCH, nbd), 4.83 (s, 1 H, Cp-H), 4.67 (m,
1 H, CHdCH, nbd), 4.47 (m, 1 H, CHdCH, nbd), 3.72 (s, 3 H,
OCH3), 3.55-3.70 (m, 3 H, CHdCH, nbd, CH bridge, nbd), 2.56
(d, 1 H, CH2, J ) 16), 2.36 (d, 1 H, CH2, J ) 16), 1.36 (m, 2 H,
CH2, nbd), 1.19 (s, 9 H, t-Bu), 1.17 (s, 9 H, t-Bu), 1.15 (s, 9 H,
t-Bu). 13C{1H} NMR (CD2Cl2, 25 °C): δ (ppm) 117.95, (C13),
87.67, 81.35, 80.76 (C10, C11, C12), 65.59, 62.53 (CHdCH, nbd),
59.23 (C9), 57.86 (bridging C, nbd), 53.09 (C8), 51.15 (CH2, nbd),
40.59 (C7), 37.35, 36.29, 33.77 (C4, C5, C6), 35.55, 35.08, 33.61
(C1, C2, C3). Anal. Calcd for C26H41ClORu: C, 61.70; H, 8.17.
Found: C, 61.58; H, 8.19. Single crystals were obtained from a
solution of complex 12 in hexane.
II CCD (3, 8, 9, 11, and 12), or a Marresearch mar345 IPDS (1b
and 7). Data were reduced by CrysAlis RED 1.7.131 (1b, 2, 7, and
10) and EvalCCD (3, 8, 9, 11, and 12).32 Absorption correction
was applied to all sets using a semiempirical method.33 All structures
were refined using full-matrix least-squares on F2 with all non-H
atoms anisotropically defined. The hydrogen atoms were placed in
calculated positions using the “riding model” with Uiso ) aUeq
(where a is 1.5 for methyl hydrogen atoms and 1.2 for others).
Structure refinement and geometrical calculations were carried out
on all structures with SHELXTL.34 Disorder problems have been
found for compound 9 and 12, and these were treated by applying
some restraints and constraints.
Acknowledgment. The work was supported by the Swiss
National Science Foundation and by the EPFL.
Supporting Information Available: X-ray crystallographic file
in CIF format is available free of charge via the Internet at
http://pubs.acs.org.
OM700461X
Crystallographic Investigations. The relevant details of the
crystals, data collection, and structure refinement can be found in
the Supporting Information (cif file). Diffraction data were collected
using Mo KR radiation on different equipment and at different
temperatures: a four-circle kappa goniometer equipped with an
Oxford Diffraction KM4 Sapphire CCD (2 and 10) a Bruker APEX
(31) CrysAlis RED 1.7.1; Oxford Diffraction Ltd.: Abingdon, Oxford-
shire, OX14 1 RL, UK, 2006.
(32) Duisenberg, A. J. M.; Kroon-Batenburg, L. M. J.; Schreurs, A. M.
M. J. Appl. Crystallogr. 2003, 36, 220-229.
(33) Blessing, R. H. Acta Crystallogr. Sect. A 1995, 51, 33-38.
(34) Sheldrick, G. M. SHELXTL; University of Go¨ttingen: Go¨ttingen,
Germany, 1997; Bruker AXS, Inc.: Madison, WI, 1997.