Synthesis of chiral, half-sandwich ruthenium complexes from weakly coordinated solvent species

Article abstract of DOI:10.1002/ejic.200400590

The bis(acetonitrile) species 7 has been synthesized in a multistep protocol. This chiral phosphaferrocene-containing, half-sandwich ruthenium complex easily provides two coordination sites due to the high lability of the coordinated solvent molecules. Although complex 7 could not be isolated in pure form, it serves as a valuable starting material for the preparation of other half-sandwich complexes with, for example, pyridine (8), tmeda (9), N-(2-dimethylaminoethyl)-morpholine (10), or tricyclohexylphosphine (11) as ligands. Whereas the morpholine complex 10 was obtained as almost a 1:1 mixture of diastereomers, the mixed MeCN/PCy₃ complex 11 was formed with a high level of diastereoselectivity (90% de). The molecular structures of complexes 8, 10, and the cyclopentadiene derivative 3a were determined by X-ray diffraction. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200400590

FULL PAPER
Synthesis of Chiral, Half-Sandwich Ruthenium Complexes from Weakly
Coordinated Solvent Species
Laetitia Jekki,[a] Corinne Pala,[a] Beatrice Calmuschi,[a] and Christian Ganter*[b]
Keywords: Chirality / P ligands / Ruthenium / Sandwich complexes
The bis(acetonitrile) species 7 has been synthesized in a
multistep protocol. This chiral phosphaferrocene-containing,
half-sandwich ruthenium complex easily provides two coor-
dination sites due to the high lability of the coordinated sol-
vent molecules. Although complex 7 could not be isolated in
pure form, it serves as a valuable starting material for the
preparation of other half-sandwich complexes with, for ex-
ample, pyridine (8), tmeda (9), N-(2-dimethylaminoethyl)-
morpholine (10), or tricyclohexylphosphine (11) as ligands.
Whereas the morpholine complex 10 was obtained as almost
a 1:1 mixture of diastereomers, the mixed MeCN/PCy3 com-
plex 11 was formed with a high level of diastereoselectivity
(90% de). The molecular structures of complexes 8, 10, and
the cyclopentadiene derivative 3a were determined by X-ray
diffraction.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
to replace the tightly bound PPh3 ligand by other donor
ligands were unsuccessful. In order to have access to a
larger array of half-sandwich complexes we set out to de-
velop a new synthetic route based on a weakly coordinated
bis(solvent) species that allows the weakly bonded ligands
to be easily exchanged. Such bis(solvent) complexes might
also be of interest for catalytic asymmetric transformations.
Indeed, there is an increasing number of recent literature
reports on the application of chiral half-sandwich com-
plexes in catalytic asymmetric reactions.[14–19]
Introduction
In a series of previous papers we have outlined the chem-
istry of a new type of bidentate ligands that contain a sub-
stituted phosphaferrocene moiety as a chiral building
block.[1–3] The coordination chemistry employing these new
ligands, as well as their applicability in asymmetric catalysis,
has been studied by us[1,4] and independently by other
groups.[5–11] In a more recent project we have tethered the
chiral phosphaferrocene unit to a cyclopentadienyl ring and
explored the properties of this anionic ligand system 1
(Scheme 1).[12] For example, the half-sandwich complexes 2
were formed in the reaction of the Na salt of the Cp anion
1 with [RuCl2(PPh3)3].[13] A high diastereoselectivity of 90–
99% de was observed for the formation of the stereogenic
Ru atom in complexes 2.
Results and Discussion
Our synthetic strategy had to avoid the presence of
strongly binding phosphane ligands throughout the synthe-
sis. Therefore, we chose the half-open ruthenocene 5 as a
target, which should be easily converted into the cationic
pentadiene complex 6 upon protonation. We hoped to ex-
change the diene ligand in 6 with two molecules of a donor
solvent in the final step to yield the desired species with two
potential coordination sites available.
A large number of attempts to prepare the half-open ru-
thenocene from the sodium salt of 1 were unsatisfactory,
the product being obtained in low yields. However, ex-
change of Na for Tl as the cation gave a straightforward
access to excellent yields of complex 5. For this purpose, the
Na derivative was hydrolysed in wet THF and the neutral
cyclopentadiene derivative 3 was isolated as a pale-orange
solid in 91% yield after chromatography. The NMR spectra
indicated that 3 was formed as a 2.5:1 mixture of two iso-
mers that differ in the distribution of the double bonds in
the cyclopentadiene ring (Scheme 2).
Scheme 1.
Furthermore, substitution of chloride in complex 2 for
other ligands like I, H or H2 was easily accomplished and
proceeded in a stereospecific manner. However, all attempts
[a]
Institut für Anorganische Chemie, RWTH Aachen,
Professor-Pirlet-Str. 1, 52056 Aachen, Germany
[b]
Institut für Anorganische Chemie, Heinrich-Heine-Universität
Düsseldorf,
Universitätsstr. 1, 40225 Düsseldorf, Germany
E-mail: christian.ganter@uni-duesseldorf.de
Eur. J. Inorg. Chem. 2005, 745–750
DOI: 10.1002/ejic.200400590
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L. Jekki, C. Pala, B. Calmuschi, C. Ganter
FULL PAPER
Scheme 2.
Both isomers have the phosphaferrocenylmethyl group
attached to an olefinic carbon atom, as indicated by the
signals for the CH2 groups in the DEPT spectra in both
cases. The isomers could not be separated by chromatogra-
phy, but cooling a hexane solution of the mixture afforded
crystals of one isomer suitable for X-ray diffraction. The
molecular structure of 3a is depicted in Figure 1 and rel-
evant geometrical data are summarized in Table 1.
Scheme 3.
The best yield (76%) was obtained when an equimolar
mixture of starting materials was heated as a slurry in tolu-
ene overnight. Complex 5 was isolated as a pale-yellow so-
lid after removal of TlI by filtration and chromatography
on alumina. The analytical data are in agreement with a
half-sandwich structure, with the phosphorus not coordi-
nated to the ruthenium atom. When an ethereal solution of
complex 5 was treated dropwise with HBF4 in diethyl ether,
protonation of the pentadienyl ligand occurred at the ter-
minal position to give an η4-coordinated pentadiene ligand.
This transformation is accompanied by the intramolecular
coordination of the P atom of the phosphaferrocene moiety
to the ruthenium atom, which thereby maintains an 18-elec-
tron count in the cationic product 6. Due to the presence
of the chiral phosphaferrocene group, the terminal carbons
of the pentadienyl ligand are diastereotopic and the proton-
ation leads to a 1:1 mixture of diastereomeric pentadiene
complexes which could not be separated. Accordingly, the
31P NMR spectrum shows two resonances at δ = 50.5 and
43.7 ppm, respectively, which are strongly downfield from
the signal at δ = –76.0 ppm for the precursor complex 5
with a non-coordinated phosphorus.
Figure 1. Molecular structure of complex 3a.
The diene ligand in cationic complex 6 could easily be
replaced by acetonitrile by stirring the complex in acetoni-
trile at room temperature for a couple of hours. Monitoring
the reaction progress by 31P NMR spectroscopy revealed
that this is not a clean transformation. First, a new signal
appears in the spectrum which is attributed to the bis(ace-
tonitrile) species 7; the intensity of this signal increases with
time at the expense of the signals for the two isomeric diene
complexes 6. However, the bis(acetonitrile) complex has a
limited stability under the reaction conditions and eventu-
ally starts to decompose to uncharacterized products before
all the diene complex has been consumed. The reproducibil-
ity of the reaction is not very good: repeated experiments
Table 1. Selected bond lengths [Å] and angles [°] for complex 3a.
Fe–P
P–C(11)
C(7)–C(10)
C(13)–C(14)
C(14)–C(15)
C(16)–C(17)
C(6)–P–C(11)
2.2799(6)
1.7794(15) C(6)–C(7)
1.437(2)
1.345(2)
1.481(2)
1.368(3)
88.93(8)
P–C(6)
1.767(2)
1.417(3)
1.421(2)
1.450(2)
1.454(3)
C(10)–C(11)
C(13)–C(17)
C(15)–C(16)
C(7)–C(6)–P
114.30(12)
111.95(13)
C(6)–C(7)–C(10) 111.37(14) C(11)–C(10)–C(7)
C(10)–C(11)–P
C(12)–C(11)–P
113.37(11) C(10)–C(11)–C(12) 124.10(14)
122.51(12)
Treatment of a solution of cyclopentadiene 3 in diethyl under identical conditions led, in some cases, to almost
ether with TlOEt precipitated the thallium cyclopentadien- pure solutions of the bis(acetonitrile) species 7, while in
ide Tl-1, which was isolated as a pale-yellow powder in al- other runs considerable degradation occurred. Variation of
most quantitative yield after filtration and drying. The Tl the reaction parameters (concentration, temperature, irradi-
salt was then allowed to react with the ruthenium butadiene ation) did not improve the reaction performance. Attempts
iodide 4 [20] to give the half-open ruthenocene 5 (Scheme 3). to isolate complex 7 in pure form failed and the characteri-
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Chiral, Half-Sandwich Ruthenium Complexes
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zation had therefore to be carried out from the reaction Table 2. Selected bond lengths [Å] and angles [°] for complex 8.
solution.
Ru–N(1)
Ru–P
P–C(12)
C(8)–C(7)
C(10)–C(12)
N(1)–Ru–N(2) 84.26(8)
N(2)–Ru–P
C(7)–P–Ru
2.139(2)
2.2797(6)
1.766(2)
1.416(4)
1.422(4)
Ru–N(2)
P–C(7)
C(7)–C(6)
C(8)–C(10)
2.153(2)
1.753(2)
1.521(3)
1.445(4)
However, the high reactivity of the bis(solvent) complex
7 could be exploited in subsequent substitution reactions
(Scheme 4). For example, when the cation 6 was stirred in
acetonitrile in the presence of an excess of pyridine for five
hours, the respective bis(pyridine) complex 8 could be iso-
lated in 91% yield after precipitation from the solution with
diethyl ether. During the reaction, the characteristic signals
of 7 are first detected in the 31P NMR spectrum, followed
by the appearance of the signal of complex 8. The use of
acetonitrile as solvent is essential for a fast reaction. Indeed,
when acetone was used instead of acetonitrile, the reaction
proceeded much slower and the conversion was incomplete
even after two days. Crystals suitable for X-ray diffraction
were obtained by slow diffusion of diethyl ether into an
acetone solution of bis(pyridine) complex 8. An ORTEP
view of the molecular structure is depicted in Figure 2; rel-
evant geometrical data are summarized in Table 2.
N(1)–Ru–P
99.96(6)
95.72(6)
108.36(8)
C(7)–P–C(12) 90.88(12)
C(12)–P–Ru 159.05(9)
C(8)–C(7)–P 113.21(18)
C(8)–C(7)–C(6) 130.5(2)
C(6)–C(7)–P 116.26(18)
different nitrogen donor groups of the morpholine deriva-
tive. As the two groups on nitrogen are incorporated into
the heterocyclic system of the morpholine the flexibility of
this donor is fairly low, and it should therefore be sterically
less demanding than the open-chain NEt2 analogue. Thus,
the difference in steric bulk of the morpholine and the di-
methylamino donor groups is less pronounced than one
would expect at first glance. While a chromatographic sepa-
ration of the two diastereomeric morpholine complexes 10
was not successful, one diastereomer could be obtained in
pure form by crystallization. The molecular structure of this
complex was determined by X-ray diffraction and is de-
picted in Figure 3; relevant geometrical data are summa-
rized in Table 3.
Scheme 4.
Figure 3. Molecular structure of the cation of complex 10.
Table 3. Selected bond lengths [Å] and angles [°] for complex 10.
Ru–N(1)
Ru–P
P–C(12)
C(7)–C(8)
C(12)–C(10)
2.214(4)
2.2912(13)
1.749(5)
1.409(6)
1.427(6)
Ru–N(2)
P–C(7)
C(7)–C(6)
C(8)–C(10)
2.210(4)
1.750(4)
1.517(6)
1.444(6)
Figure 2. Molecular structure of the cation of complex 8.
N(2)–Ru–N(1) 80.99(16)
N(1)–Ru–P
C(12)–P–C(7) 90.6(2)
C(12)–P–Ru
C(8)–C(7)–P
C(10)–C(12)–P 112.7(3)
97.83(12)
Similarly to the preparation of 8, the tmeda complex 9
was prepared in 98% isolated yield by treatment of an ace-
tonitrile solution of diene complex 6 with one equivalent of
tmeda. When a solution of diene cation 6 in acetonitrile
was treated with one equivalent of N-(2-dimethylamino-
ethyl)morpholine complex 10 was formed, with the morph-
oline derivative coordinated as an N,N Ј-chelate ligand.
N(2)–Ru–P
C(7)–P–Ru
C(6)–C(7)–P
97.66(11)
108.69(16)
116.1(3)
160.74(16)
113.5(3)
C(8)–C(7)–C(6) 130.1(4)
The Ru–P distances in the two cationic complexes 8
(228 pm) and 10 (229 pm) are almost identical and slightly
In the course of this reaction the ruthenium center be- longer than in neutral Ru-phosphaferrocene half-sandwich
comes stereogenic and complex 10 is formed as two diaste- complexes (224–225 pm).[2,13] As expected, the Ru–N bonds
reomers in a ratio of approximately 3:2. This poor diaste- are significantly shorter in the pyridine complex 8 (214 pm)
reoselectivity reflects the similar steric demands of the two than in the morpholine derivative 10 (221 pm) with its terti-
Eur. J. Inorg. Chem. 2005, 745–750
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L. Jekki, C. Pala, B. Calmuschi, C. Ganter
FULL PAPER
powder as a mixture of two isomers in a ratio of ca. 1:2.5. Crystals
suitable for X-ray diffraction were obtained by slowly cooling a
hexane solution to –18 °C. H NMR (500 MHz, CDCl3): δ = 2.21,
2.14 (s, 3 H, CH3), 2.93 (m, 4 H, CH2 in C5H5R), 3.26 (m, 4 H,
PCCH 2, major + minor), 3.71 (d, JC,P = 35.7 Hz, 2 H, PCH, major
+ minor), 4.13 (s, 2 × 5 H, Cp, major + minor), 5.9 (s, 1 H, C5H5R,
major), 6.24, 6.06 (s, 1 H, C5H5R, minor), 6.39 (s, 2 H, C5H5R,
major + minor), 6.47 (s, 1 H, C5H5R, major) ppm. 13C{1H}
(125.6 MHz, CDCl3): major isomer: δ = 17.1, 13.7 (s, CH3), 31.1
(d, JC,P = 20.2 Hz, PCCH2), 41.0 (s, CH2 in C5H5R), 72.0 (s, Cp),
ary amine donor functions. As is usually observed, on going
from an uncoordinated phosphaferrocene derivative (3a) to
the metal complexes 8 and 10 the C–P–C angle in the phos-
pholyl ring increases slightly from 88.9° (3) to 90.9° (8) and
90.6° (10). Furthermore, the P–C bonds in the phospholyl
ring contract slightly on coordination from ca. 178 pm to
175–176 pm.
1
It was also possible to prepare a mono(acetonitrile) de-
rivative starting from the cationic complex 6. Thus, when
an acetonitrile solution of 6 was treated with one equivalent 75.6 (d, JC,P = 58.5 Hz, PCH), 93.3 (d, JC,P = 5.7 Hz, CCH3), 95.6
(d, JC,P = 6.7 Hz, CCH3), 97.4 (d, JC,P = 57.6 Hz, PCCH2), 134.4,
133.5, 126.5 (s, CH in C5H5R), 146.6 (s, CR in C5H5R) ppm; minor
isomer: δ = 17.1, 13.7 (s, CH3), 32.0 (d, JC,P = 22 Hz, PCCH2),
43.2 (s, CH2 in C5H5R), 72.0 (s, Cp), 75.5 (d, JC,P = 57.5 Hz, PCH),
93.3 (d, JC,P = 5.7 Hz, CCH3), 95.6 (d, JC,P = 6.7 Hz, CCH3), 98.3
(d, JC,P = 57.5 Hz, PCCH2), 132.2, 130.7, 127.0 (s, CH in C5H5),
149.2 (s, CR in C5H5R) ppm. 31P NMR (80.95 MHz, CDCl3): δ
= –79.7 (s, minor), –80.1 (s, major) ppm. MS (70 eV): m/z (%) =
310 (42) [M+], 244.9 (47) [M+ – Cp]. C17H19FeP (310.2): calcd. C
65.83, H 6.17; found C 65.61, H 6.08.
of tricyclohexylphosphane (PCy3), the mixed P,N complex
11 was formed in 96% yield. In contrast to the morpholine
derivative 10, a high level of stereodiscrimination (90% de)
was observed for the formation of complex 11. This reflects
the different steric properties of the acetonitrile and PCy3
ligands.
Conclusions
A high-yield route to half-sandwich ruthenium com-
Thallium Salt Tl-1: TlOEt (0.22 mL, 3.06 mmol) was added drop-
plexes with a tethered phosphaferrocene donor and two wise to a solution of cyclopentadiene 3 (947 mg, 3.06 mmol) in di-
ethyl ether (10 mL) at room temperature. After stirring for 30 min
the precipitate was isolated by filtration, washed with diethyl ether,
and dried in vacuo to give 1.74 g (3.03 mmol, 99%) of Tl-1 as a
pale-orange powder. 1H NMR (500 MHz, CDCl3): δ = 2.23 (s,
CH3), 2.26 (s, CH3), 3.28 (dd, JH,P = 15.3, JH,H = 7.0 Hz, 1 H,
CH2), 3.49 (m, 1 H, CH2), 3.66 (d, JH,P = 35.7 Hz, 1 H, PCH),
4.12 (s, 5 H, Cp), 5.84 (m, 2 H, C5H4), 5.99 (m, 2 H, C5H4) ppm.
13C{1H} (125.6 MHz, CDCl3): δ = 14.2 (s, CH3), 17.2 (s, CH3),
29.9 (d, JC,P = 20.9 Hz, CH2), 72.1 (s, Cp), 75.3 (d, JC,P = 58.1 Hz,
PCH), 92.9 (d, JC,P = 4.4 Hz, CCH3), 95.8 (d, JC,P = 6.5 Hz,
CCH3), 105.5 (s, C5H4), 106.1 (d, JC,P = 54.9 Hz, PCCH2), 108.0
(s, C5H4), 132.6 (s, CCH2) ppm. 31P NMR (80.95 MHz, CDCl3): δ
= –77.7 (s) ppm. SIMS (70 eV): m/z = 514 [M+], 310.2 [M+ – Tl],
205.1 [Tl+]. C17H18FePTl (513.53): calcd. C 39.76, H 3.53, found
C 39.01, H 3.39.
loosely coordinated acetonitrile molecules has been devised.
The bis(acetonitrile) complex is very reactive and easily pro-
vides two available coordination sites at the ruthenium. The
synthetic value of this approach has been corroborated by
the subsequent preparation of some derivatives with mono-
and bidentate nitrogen ligands. We are currently trying to
extend and improve the results with respect to the stereo-
discrimination in the complexation of difunctional ligands
and the use of the solvent complex for catalytic applica-
tions.
Experimental Section
All experiments were performed under nitrogen using Schlenk and
vacuum-line techniques. Hexane and toluene were distilled from
sodium; CHCl3 and CH2Cl2 from CaH2. THF and diethyl ether
were distilled from sodium/benzophenone. Acetonitrile was dried
with P4O10 and distilled from CaH2. Methanol and acetone were
dried with magnesium. The solvents were kept in Schlenk flasks
under nitrogen. Silica gel or alumina were heated to 200 °C, cooled
to room temperature under vacuum, and stored under nitrogen.
Alumina (Riedel-de Haën) was deactivated by addition of 5%
water. NMR spectra were measured with Varian Mercury 200,
VXR 300 and Unity 500 spectrometers. EI and FAB mass spectra
were measured on a Finnigan MAT 95 spectrometer. Elemental
analyses were performed by the microanalytical laboratory of the
(Dimethylpentadienyl)ruthenium Complex 5: Tl-1 (1.13 g,
2.21 mmol) was added to a suspension of ruthenium iodide 4
(894 mg, 2.21 mmol) in 35 mL of toluene and the mixture was re-
fluxed overnight. TlI was removed by filtration through Kieselguhr
and the filtrate was evaporated to dryness. The residue was ex-
tracted with hexane, the solution filtered through alumina, and the
solvent was removed in vacuo to yield 5 (849 mg, 1.68 mmol, 76%)
1
as an orange solid. H NMR (500 MHz, CDCl3): δ = 0.29 (d, JH,H
= 2.4 Hz, 1 H, Hendo), 0.31 (d, JH,H = 2.4 Hz, 1 H, Hendo), 1.87 (s,
CH3), 1.89 (s, CH3), 1.90 (s, CH3), 1.92 (s, CH3), 2.86 (d, JH,H
=
2.4 Hz, 1 H, Hexo), 2.87 (d, JH,H = 2.4 Hz, 1 H, Hexo), 3.07 (m, 2
H, CH2), 3.60 (d, JH,P = 36.0 Hz, 1 H, PCH), 3.90 (s, 5 H, Cp), 4.31
(m, 2 H, C5H4), 4.56 (m, 2 H, C5H4), 5.34 (s, CH) ppm. 13C{1H}
(125.6 MHz, CDCl3): δ = 13.9 (s, CH3), 16.9 (s, CH3), 27.9 (s, 2 ×
CH3), 30.5 (d, JC,P = 20.9 Hz, CH2), 42.2 (s, =CH2), 42.3 (s, =CH2)
72.2 (s, Cp), 76.2 (d, JC,P = 58.8 Hz, PCH), 77.4 (s, RC5H4), 78.0
(s, RC5H4), 78.5 (s, RC5H4), 79.1 (s, RC5H4), 92.3 (s, CH2=C), 92.7
(s, CH), 95.7 (d, JC,P = 6.1 Hz, CCH3), 98.8 (d, JC,P = 2.8 Hz,
CCH3), 100.2 (d, JC,P = 58.2 Hz, PCCH2) ppm. 31P NMR
(80.95 MHz, CDCl3): δ = –76.0 (s) ppm. MS (70 eV): m/z = 505.8
[M+], 309.9 [M+ – Ru – C7H11], 244.9 [M+ – Ru – C7H11 – Cp].
HRMS for C24H29FePRu: calcd. 506.039346; found 506.039321.
[12]
[20]
Universität Düsseldorf. Na-1
and ruthenium iodide 4
were
prepared as described in the literature.
Cyclopentadiene 3: Na-1 was obtained by addition of NaBEt3H
(0.62 mmol, 0.4 mL of a 1.5 m solution in THF) to a solution of 6-
(3,4-dimethylphosphaferrocen-2-yl)fulvene (127.7 mg, 0.41 mmol)
in diethyl ether/THF (1:1, 30 mL) at room temperature. After stir-
ring for 45 min water (5 mL) was added to the orange solution and
the phases were separated. The organic phase was washed with
water, dried with Na2SO4, and the solvent was removed in vacuum.
The crude product was filtered through a short plug of alumina
with hexane as eluent. After evaporation of the solvent, 3
(115.7 mg, 0.37 mmol, 91%) was isolated as an orange crystalline
(η4-2,4-Dimethylpentadiene)ruthenium Complex 6: HBF4 (0.38 mL,
54% solution in diethyl ether, 2.76 mmol) was added dropwise to a
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Chiral, Half-Sandwich Ruthenium Complexes
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solution of complex 5 (943 mg, 1.87 mmol) in diethyl ether (50 mL)
at –78 °C. After stirring for 30 min at room temperature the pre-
cipitate was isolated by filtration, washed twice with diethyl ether,
and dried in vacuo to give 1.05 g (1.78 mmol, 95%) of complex 6
as a 1:1 mixture of isomers as an orange powder. 1H NMR
Tetramethylethylenediamine Complex 9: tmeda (85 µL, 0.56 mmol)
was added to a solution of complex 6 (331.6 mg, 0.56 mmol) in
15 mL of acetonitrile at room temperature. The reaction mixture
was stirred for 7 h and the solvent was then evaporated under high
1
vacuum to give 9 as an orange powder (329.4 mg, 96%). H NMR
(500 MHz, [D6]acetone): isomer 1: δ = 1.46 (d, JH,H = 8.9 Hz, 3 H, (500 MHz, CD3CN): δ = 2.20, 2.18 (2 × s, 3 H, CCH3), 2.33 (m, 2
CH3), 2.22 (s, CH3), 2.28 (s, CH3), 2.34 (s, CH3), 2.35 (m, 2 H, H, C5H4-CH ), 2.52 (m, 2 H, NCH2), 2.72 (d, JH,P = 3 Hz, 3 H,
2
=CH2), 2.40 (s, CH3), 2.93 (m, 2 H, CH2), 3.70 (d, JH,P = 32.0 Hz,
1 H, PCH), 3.81 (m, 1 H, =CH-C), 4.63 (m, 1 H, C5H4), 4.65 (s, 5
H, Cp), 5.38 (m, 1 H, C5H4), 5.61 (m, 1 H, C5H4), 5.83 (m, 1 H,
C5H4) ppm; isomer 2: δ = 1.24 (d, JH,H = 8.4 Hz, 3 H, CH3), 1.83
(s, CH3), 1.91 (m, 2 H, = CH2), 2.30 (s, CH3), 2.31 (s, CH3), 2.47
NCH3), 2.72 (m, 1 H, NCH2), 2.87 (m, 1 H, NCH2), 3.13 (s, 3 H,
NCH3), 3.15 (d, JH,P = 4 Hz, 3 H, NCH3), 3.28 (s, 3 H, NCH3),
3.53 (d, JH,P = 32 Hz, 1 H, PCH), 4.11, 4.09 (2 × m, 1 H, C5H4),
4.25 (s, 5 H, Cp), 5.06, 4.64 (2 × m, 1 H, C5H4) ppm. 13C{1H}
(125.6 MHz, CD3CN): δ = 14.3 (d, JC,P = 4.8 Hz, CH3), 16.5 (s,
(s, CH3), 3.01 (m, 2 H, CH2), 3.38 (m, 1 H, =CH-C), 4.10 (d, JH,P CH3), 23.8 (d, JC,P = 16.3 Hz, CpCH2), 60.0, 59.4 (2 × s, NCH3),
= 32.4 Hz, 1 H, PCH), 4.51 (s, 5 H, Cp), 4.83 (m, 1 H, C5H4), 5.25 61.7 (s, C5H4), 61.7 (d, JC,P = 36.5 Hz, PCH), 62.3 (d, J = 15.3 Hz,
(m, 1 H, C5H4), 5.63 (m, 1 H, C5H4), 5.73 (m, 1 H, C5H4) ppm. NCH3), 62.9 (d, J = 16.3 Hz, NCH3), 64.5, 63.8 (2 × s, NCH2),
13C{1H} (125.6 MHz, [D6]acetone): isomer 1: δ = 15.9 (d, JC,P
66.8 (s, C5H4), 75.3 (s, Cp), 77.5 (d, JC,P = 10.5 Hz, C5H4), 89.5 (s,
6.0 Hz, CH3), 16.1 (d, JC,P = 5.6 Hz, CH3), 23.6 (d, JC,P = 15.9 Hz,
quat.), 90.5 (s, C5H4), 107.8, 110.6, 117.5 (3 × s, Cquat.) ppm. 31P
=
C
CH2), 24.6 (s, CH3), 26.4 (s, CH3), 34.3 (s, CH3), 43.2 (s, =CH2), NMR (80.95 MHz, CD3CN): δ = 16.5 (s) ppm. FAB MS (NBA
43.3 (s, =CH-C), 57.5 (s, PCH), 76.1 (s, Cp), 82.8 (s, RC5H4), 85.4 matrix): m/z = 527 [cation], 87 [BF4 –]. C23H34BF4FeN2PRu: calcd
(s, RC5H4), 86.9 (s, RC5H4), 88.9 (s, RC5H4) ppm; isomer 2: δ = C 45.05, H 5.59, N 4.57; found C 45.90, H 5.78, N 3.84.
13.9 (s, CH3), 14.0 (d, JC,P = 5.0 Hz, CH3), 23.9 (d, JC,P = 16.5 Hz,
Morpholine Complex 10: N-(2-Dimethylaminoethyl)morpholine
(1.3 equiv., 82 µL, 0.48 mmol) was added to a solution of cationic
complex 6 (220 mg, 0.37 mmol) in 10 mL of acetonitrile and stirred
for 1 d at room temperature. The solvent was evaporated under
CH2), 24.7 (s, CH3), 26.0 (s, CH3), 34.0 (s, CH3), 43.8 (s, =CH2),
43.9 (s, =CH-C), 60.4 (s, PCH), 76.5 (s, Cp), 83.3 (s, RC5H4), 83.6
(s, RC5H4), 85.8 (s, RC5H4), 90.2 (d, JC,P = 4.9 Hz, RC5H4) ppm.
31P NMR (80.95 MHz, CDCl3): δ = 50.5 (s, isomer 1), 43.7 (s,
high vacuum to give 10 as a red powder (223.5 mg, 97%) as a mix-
isomer 2) ppm. SIMS (70 eV): m/z = 507 [M+], 411 [M+ – C7H11].
ture of isomers in a ratio of about 3:2. Crystals suitable for X-ray
C24H30BF4FePRu (593.2): calcd. C 48.59, H 5.10; found C 47.85,
H 5.18.
diffraction were obtained by layering a CH2Cl2 solution with hex-
1
ane. H NMR (500 MHz, CD3CN, mixture of isomers): δ = 2.21,
Bis(acetonitrile) Complex 7: A solution of cationic complex 6
(118 mg, 0.20 mmol) in 15 mL of acetonitrile was stirred at room
temperature. The reaction progress was monitored by 31P NMR
spectroscopy. After 4 h all volatiles were evaporated off under high
vacuum to give an orange oil of 7 which was immediately charac-
terized by NMR spectroscopy in CD3CN. 1H NMR (200 MHz,
CD3CN): δ = 2.20 (s, 6 H, CH3CN), 2.44, 2.42 (2 × s, 3 H, CH3),
2.72 (m, 2 H, CH2), 3.89 (d, JH,P = 34.2 Hz, 1 H, PCH), 4.28 (br.
s, 1 H, C5H4), 4.52 (s, 5 H, Cp), 5.37, 5.27, 4.71 (3 × br. s, 1 H,
C5H4) ppm. 31P NMR (202.25 MHz, CD3CN): δ = 4.2 (s) ppm.
2.20, 2.20, 2.19 (4 × s, 3 H, CH3), 3.27, 3.25, 3.24, 3.12 (4 × s, 3
H, NCH3), 4.24 (s, 5 H, Cp), 4.28 (s, 5 H, Cp) ppm. 31P NMR
(202 MHz, CD3CN): δ = 13.9 (s, major), 12.9 (s, minor) ppm. FAB
MS (NBA matrix): m/z = 569 [cation], 411 [cation – morpholine].
C25H36BF4FeN2OPRu (655.3): calcd. C 45.82, H 5.54, N 4.28;
found C 45.01, H 5.67, N 4.51.
Tricyclohexylphosphane Complex 11: One equivalent of tricyclohex-
ylphosphane (97 mg, 0.37 mmol) was added to a solution of com-
plex 6 (222 mg, 0.37 mmol) in 10 mL of acetonitrile and stirred for
1 d at room temperature. The solvent was evaporated under high
vacuum to give Ru-9 as an orange foam (291mg, 96%) as a mixture
of two isomers in a ratio of about 19:1 (90% de). 1H NMR
(300 MHz, C6D6): major isomer: δ = 1.9–1.1 (m, 36 H, PCy3 and
CH3CN), 1.94, 1.88 (2 × s, 3 H, CH3), 2.38 (m, 1 H, PCCH2), 2.59
(m, 1 H, PCCH2), 3.33 (d, JH,P = 32.6 Hz, 1 H, PCH), 3.36 (s, 1
H, C5H4), 4.33 (s, 5 H, Cp), 5.01, 5.20, 5.86 (3 × s, 1 H, C5H4)
ppm. 31P NMR (121.45 MHz, C6D6): major isomer: δ = 59.6 (d,
JP,P = 55 Hz, PFc), 18.1 (d, JP,P = 55 Hz, PCy3) ppm; minor isomer:
δ = 59.4 (d, JP,P = 48 Hz, PFc), 18.1 (d, JP,P = 48 Hz, PCy3) ppm.
Bis(pyridine) Complex 8: An excess of pyridine (260 µL, 3.21 mmol)
was added to a solution of cationic complex 6 (336 mg, 0.57 mmol)
in 15 mL of acetonitrile at room temperature. The reaction mixture
was stirred for 4 h. The solvents were removed under high vacuum
to give an orange oil, which was redissolved in acetone. Complex
8 (338 mg, 0.52mmol, 91%) was isolated as an orange powder upon
precipitation with diethyl ether. Red crystals were obtained by dif-
fusion of diethyl ether into an acetone solution. 1H NMR
(500 MHz, [CD3]2CO): δ = 2.27, 2.26 (2 × s, 3 H, CH3), 2.65 (m,
2 H, CH2-Phosp.), 3.88 (d, JH,P = 33.3 Hz, 1 H, PCH), 4.11 (s, 5
H, Cp), 5.38, 5.10, 4.73, 4.12 (4 × s, 1 H, C5H4R), 7.51, 7.36 (br.
X-ray Crystallographic Study: Crystal data and details of the struc-
t, J = 7.0 Hz, 2 H, C5H5N-Hmeta), 8.00, 7.88 (2 × br. t, J = 7.6 Hz, ture determination are listed in Table 4. Data collection was per-
1 H, C5H5N-Hpara), 8.94 (br. d, J = 5.2 Hz, 2 H, C5H5N-Hortho), formed with a Bruker Smart APEX CCD (Mo-K radiation, λ =
α
9.19 (br. d, J = 4.9 Hz, 2 H, C5H5N-Hortho) ppm. 13C{1H} 0.71073 Å, graphite monochromator) area detector. The unit-cell
(125.6 MHz, [CD3]2CO): δ = 16.4, 14.3 (2 × s, CH3), 24.1 (d, JC,P
= 16.3 Hz, CH2), 62.2 (s, C5H4), 62.5 (d, JC,P = 36.5 Hz, PCH),
69.9 (s, C5H4), 74.8 (s, Cp), 83.2 (d, JC,P = 10.5 Hz, C5H4), 85.1 (d,
J = 5.8 Hz, C5H4), 89.2 (s, CR in RC5H4), 91.2 (d, J = 2 Hz,
parameters were obtained by the least-squares refinement of 8096
reflections. All the structures were solved by direct methods
(SHELXS-97)[21] and refined by full-matrix least-squares pro-
2
cedures based on F with all measured reflections (SHELXL-
PCCH2), 111.4 (d, J = 7.66 Hz, CCH3), 111.7 (d, J = 12.5 Hz, 97).[22] The SADABS[23] program was used for absorption correc-
CCH3), 126.6, 126.4 (2 × s, Cmeta-C5H5N), 138.3, 138.2 (2 × s,
tion of the structures. All non-hydrogen atoms were refined aniso-
Cpara-C5H5N), 158.4, 157.9 (2 × d, JC,P = 7.7 Hz, Cortho-C5H5N) tropically. H atoms were in part located from difference Fourier
ppm. 31P NMR (202.25 MHz, [CD3]2CO): δ = 10.5 (s) ppm. maps; the remaining hydrogens were introduced at their idealized
C27H28BF4FePN2Ru (655.2): calcd. C 49.49, H 4.31, N 4.28; found
C 48.82, H 4.38, N 4.19. FAB MS: m/z = 490 [cation – py], 411
[cation – 2 py].
positions [d(CH) = 0.98 Å] and were refined using a riding model.
The absolute configuration for complex 3a was confirmed by evalu-
ation of the Flack parameter.[24] CCDC-237071 (for 3a), -237069
Eur. J. Inorg. Chem. 2005, 745–750
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
749

L. Jekki, C. Pala, B. Calmuschi, C. Ganter
FULL PAPER
Table 4. Crystallographic data for compounds 3a, 8, and 10.
Compound
3a
8
10
Formula
M
Crystal system
Space group
a/Å
b/Å
c/Å
α/°
β/°
C17H19FeP
310.14
orthorhombic
P212121
9.2086(19)
11.208(2)
14.540(3)
90
90
90
1500.7(5)
4
C30H34BF4FeN2OPRu
713.29
C25H36BF4FeN2OPRu
655.27
monoclinic
P21/c
8.311(3)
21.113(7)
14.944(5)
90
97.390(9)
90
2600.3(15)
4
triclinic
¯
P1
9.6510(9)
13.1340(13)
13.3840(13)
75.710(2)
68.860(2)
79.530(2)
1525.3(3)
2
γ/°
V/Å3
Z
T/K
Dc/g cm–3
F000
293
1.373
648
1.095
293
1.553
724
1.074
293
1.674
1336
1.251
µ(Mo-Kα)/cm–1
o
2θmax
/
54.88
56.64
56.74
Total reflections
19492
3423
3306
244
0.0250, 0.0627
0.0259, 0.0631
0.039(12)
21164
7569
6867
411
0.0368, 0.0923
0.0410, 0.0951
–
35782
6470
4726
Independent reflections
Observed reflections [I Ͼ 2σ(I)]
Parameters refined
R1/wR2 [I Ͼ 2σ(I)]
R1/wR2 (all data)
329
0.0577, 0.1201
0.0862, 0.1318
–
Flack’s param.
[11]
R. Shintani, G. C. Fu, Org. Lett. 2002, 4, 3699.
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5444.
C. Kaulen, C. Pala, C. Hu, C. Ganter, Organometallics 2001,
20, 1614.
M. Ito, M. Hirakawa, K. Murata, T. Ikariya, Organometallics
2001, 20, 379.
Y. Morisaki, T. Kondo, T. Mitsudo, Organometallics 1999, 18,
4742.
B. M. Trost, P. L. Fraisse, Z. T. Ball, Angew. Chem. 2002, 114,
1101; Angew. Chem. Int. Ed. 2002, 41, 1059.
Y. Matsushima, K. Onitsuka, T. Kondo, T. Mitsudo, S. Takah-
ashi, J. Am. Chem. Soc. 2001, 123, 10 405.
(for 8) and -237070 (for 10) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[12]
[13]
[14]
[15]
[16]
[17]
Acknowledgments
Financial support of this work by the Deutsche Forschungsgemein-
schaft (DFG, Graduiertenkolleg 440) is gratefully acknowledged.
[1] For a review see: C. Ganter, J. Chem. Soc. Dalton Trans. 2001,
3541.
[2] C. Ganter, L. Brassat, C. Glinsböckel, B. Ganter, Organomet-
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[20] A. Bauer, U. Englert, S. Geyser, F. Podewils, A. Salzer, Or-
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[5] S. Qiao, G. C. Fu, J. Org. Chem. 1998, 63, 4168.
[6] R. Shintani, M. M.-C. Lo, G. C. Fu, Org. Lett. 2000, 2, 3695.
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Chem. Soc. 2000, 122, 9870.
[21] G. M. Sheldrick, SHELXS-97, Program for solution of crystal
structures, University of Göttingen, Germany, 1997.
[22] G. M. Sheldrick, SHELXL-97, Program for refinement of crys-
tal structures, University of Göttingen, Germany, 1997.
[23] G. M. Sheldrick, SADABS, University of Göttingen, Germany,
1996.
[8] M. Ogasawara, K. Yoshida, T. Hayashi, Organometallics 2001,
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[24] H. D. Flack, Acta Crystallogr. Sect. A 1983, 39, 876.
Received July 8, 2004
Published Online January 27, 2005
750
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 745–750