Dinuclear (arene)ruthenium complexes containing a chiral-at-phosphorus phosphanido bridge

Article abstract of DOI:10.1002/ejic.200601174

The unsaturated diruthenium cation [(η⁶-C₆Me ₆)(η⁶-p-iPrMeC₆H₄)Ru ₂(μ₂-H)₃]⁺ reacts with PPh ₂(CH₂)₃Ph to give the phosphanido complex [(η⁶-C₆Me₆)(η⁶-p-iPrMeC ₆H₄)-Ru₂{μ₂-PPh(CH ₂)₃Ph}(μ₂-H)₂]⁺ (1), which contains a stereogenic phosphorus atom in the bridge, and benzene. Heating of 1 in bromobenzene gives the first chiral-at-phosphorus diruthenium complex [(η⁶-C₆Me₆)Ru₂{μ₂- PPh(CH₂)₃-η⁶-Ph}(μ₂-Br) ₂]⁺ (3) due to the replacement of the p-cymene ligand by the phenyl group at the pendant arm and hydrido bridges by bromido bridges. The single-crystal X-ray structure analysis of [3][BF₄] reveals a racemic mixture of both enantiomers (R_P)-3 and (S_P)-3 in the crystal. Similarly, the reaction of [(η⁶-C₆Me ₆)(η⁶-p-iPrMeC₆H₄)Ru ₂(μ₂-H)₃]⁺ and the enantiopure phosphane (R)-PPh₂(CH₂)₂CHMePh yields the complex [(η⁶-C₆Me₆)(η⁶-p- iPrMeC₆H₄)Ru₂{μ₂-(R)-PPh(CH ₂)₂CHMePh}(μ₂-H)₂]⁺ (4) as a mixture of diastereomers. An optically active mixture (de = 4 %) of phosphanido-bridged complexes [(η⁶-C₆Me ₆)Ru₂{μ₂-(R)-PPh(CH₂) ₂CHMe-η⁶-Ph}(μ₂-Br)₂] ⁺ (6), containing the (R_C,S_P) and (R _C,R_P) diastereomers, is obtained upon heating of 4 in bromobenzene. The molecular structure of [6][BF₄] reveals that the two diastereomers (R_C,S_P)-6 and (R_C,R _P)-6 exist as two conformers. The non-chiral-at-phosphorus analogues [(η⁶-C₆Me₆)₂Ru ₂[μ₂-PPh(CH₂)₃Ph] (μ₂-H)₂]⁺ (2) and [(η⁶-C ₆Me₆)₂Ru₂{μ₂-(R) -PPh(CH₂)₂CHMePh}(μ₂-H)₂] ⁺ (5) have also been synthesized and structurally characterized by single-crystal X-ray structure analyses of [2][BF₄] and [5][BF ₄]. Wiley-VCH Verlag GmbH & Co. KGaA.

Full text of DOI:10.1002/ejic.200601174

FULL PAPER
DOI: 10.1002/ejic.200601174
Dinuclear (Arene)ruthenium Complexes Containing a Chiral-at-Phosphorus
Phosphanido Bridge
Mathieu J.-L. Tschan,[a] Georg Süss-Fink,*[a] Frédéric Chérioux,[b] and Bruno Therrien[a]
Dedicated to Professor Hans-Ludwig Krauss on the occasion of his 80th birthday
Keywords: Arene ligands / Ruthenium / Tethered complexes / P ligands / Hydride ligands
The unsaturated diruthenium cation [(η6-C6Me6)(η6-p-
iPrMeC6H4)Ru2(µ2-H)3]+ reacts with PPh2(CH2)3Ph to give
the phosphanido complex [(η6-C6Me6)(η6-p-iPrMeC6H4)-
Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+ (1), which contains a stereo-
genic phosphorus atom in the bridge, and benzene. Heating
of 1 in bromobenzene gives the first chiral-at-phosphorus di-
ruthenium complex [(η6-C6Me6)Ru2{µ2-PPh(CH2)3-η6-Ph}(µ2-
Br)2]+ (3) due to the replacement of the p-cymene ligand by
the phenyl group at the pendant arm and hydrido bridges by
bromido bridges. The single-crystal X-ray structure analysis
of [3][BF4] reveals a racemic mixture of both enantiomers
(RP)-3 and (SP)-3 in the crystal. Similarly, the reaction of [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3]+ and the enantiopure
phosphane (R)-PPh2(CH2)2CHMePh yields the complex [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-
H)2]+ (4) as a mixture of diastereomers. An optically active
mixture (de = 4%) of phosphanido-bridged complexes [(η6-
C6Me6)Ru2{µ2-(R)-PPh(CH2)2CHMe-η6-Ph}(µ2-Br)2]+ (6), con-
taining the (RC,SP) and (RC,RP) diastereomers, is obtained
upon heating of 4 in bromobenzene. The molecular structure
of [6][BF4] reveals that the two diastereomers (RC,SP)-6 and
(RC,RP)-6 exist as two conformers. The non-chiral-at-phos-
phorus analogues [(η6-C6Me6)2Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+
(2) and [(η6-C6Me6)2Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2]+
(5) have also been synthesized and structurally characterized
by single-crystal X-ray structure analyses of [2][BF4] and
[5][BF4].
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Thus, examples of tethered (arene)ruthenium complexes
containing oxygen,[7] phosphorus,[5,6,8] sulfur[9] and carbon
or nitrogen[10] donor atoms have been reported.
Introduction
(Arene)ruthenium complexes, in spite of their venerable
history, have not lost their fascination thanks to their rich
and diversified chemistry.[1] An increasing number of cata-
lytic reactions involving (arene)ruthenium complexes, such
as transfer hydrogenation reactions,[2] alkene metathesis[3]
or Diels–Alder reactions,[4] have contributed to the steadily
growing interest in these complexes, which owe their fer-
tility and versatility mainly to the stability of the arene–
ruthenium bond. The complete loss of the arene ligand can
be an undesired side-reaction during a catalytic process, al-
though the stability of the (arene)ruthenium moiety can be
increased by arene ligands containing chelating substitu-
ents.[5] The synthesis of such (arene)ruthenium complexes
can be achieved by intramolecular arene ligand exchange at
the ruthenium atom, which works only if either an electron-
poor arene ligand is replaced by an electron-rich one[6] or
if the reaction can take advantage of the chelate effect.[5]
Recently, we found that the unsaturated dinuclear cation
[(η6-C6Me6)2Ru2(µ2-H)3]+ reacts with tertiary phosphanes
such as PPh3 and PPhMe2 to give the phosphanido-bridged
complexes [(η6-C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ (R = Ph, Me)
and benzene.[11] The reaction proceeds by P–C activation
intermediates containing a bridging phenyl ligand, [(η6-
C6Me6)2Ru2(µ2-PR2)(µ2-Ph)(µ2-H)]+ (R = Ph, Me), and the
phenyl derivative is isolated as the tetrafluoroborate salt.
This P–C bond-cleavage reaction occurs even in the case of
trialkylphosphanes such as PnBu3 and PnOct3 to give the
cations [(η6-C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ (R = nBu, nOct)
and the corresponding olefin and dihydrogen.[11] The
diphenylphosphanido
derivative
[(η6-C6Me6)2Ru2(µ2-
PPh2)(µ2-H)2]+ turned out to be a highly selective catalyst
for hydrogenation of carbon–carbon double bonds.[12]
The mixed dinuclear (arene)trihydridoruthenium com-
plex [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3]+, which we
synthesized recently,[13] reacts with phosphanes in the same
way as its symmetrical analogue, [(η6-C6Me6)2Ru2(µ2-
H)3]+, although, because of the asymmetry of the diruthe-
nium backbone, the reaction with mixed phosphanes allows
[a] Institut de Chimie, Université de Neuchâtel,
Case postale 158, 2009 Neuchâtel, Suisse
Fax: +41-32-718-2511
E-mail: georg.suess-fink@unine.ch
[b] Laboratoire FEMTO-ST/LPMO, CNRS UMR 6174,
32 Avenue de l’Observatoire, 25044 Besançon cedex, France
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the synthesis of phosphanido-bridged diruthenium com- hydrogen in this reaction is the conversion of the inter-
plexes that are chiral at the phosphorus atom. Moreover, mediate [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-PPh(CH2)3-
the use of mixed phosphanes containing a phenyl substitu- Ph}(µ2-Ph)(µ2-H)]+, which was observed by mass spectrom-
ent at the end of a pendant arm should give access to teth- etry in accordance with the fully characterized analogue
ered P-chiral diruthenium complexes.
[(η6-C6Me6)2Ru2(µ2-PPh2)(µ2-Ph)(µ2-H)]+,[11] into 1 by re-
In this paper, we report the synthesis of the first tethered action with H2.
chiral-at-phosphorus diruthenium complex, [(η6-C6Me6)-
Complex 1 possesses a stereogenic phosphanido bridge
Ru2{µ2-PPh(CH2)3-η6-Ph}(µ2-Br)2]+ (3), which was ob- and was obtained as a racemic mixture since the nucleo-
tained as a racemic mixture by heating of [(η6-C6Me6)(η6- philic attack of the phosphane occurs at one of the two
p-iPrMeC6H4)Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+ (1) in bro- ruthenium atoms and none of the two P–C(aryl) bonds is
mobenzene. The enantiopure phosphane (R)-PPh2(CH2)2- preferentially cleaved. The two hydrido ligands in 1 are dia-
CHMePh, reported by Zenneck et al.,[8c] gave an optically stereotopic, as seen by the 1H NMR spectrum, which exhib-
active mixture of the diastereomeric complexes (RC,SP)- its two doublets of doublets in the hydride region at δ =
2
2
and (RC,RP)-[(η6-C6Me6)Ru2{µ2-(R)-PPh(CH2)2CHMe-η6- –14.65 (dd, JH,H = 2.8, JH,P = 28 Hz, 1 H) and –16.06
Ph}(µ2-Br)2]+ (6).
(dd, 2JH,H = 2.8, 2JH,P = 31 Hz, 1 H) ppm. The two enantio-
mers of 1 are shown in Figure 1.
Results and Discussion
The dinuclear trihydrido complex [(η6-C6Me6)(η6-
iPrMeC6H4)Ru2(µ2-H)3]+ reacts with the mixed phosphane
PPh2(CH2)3Ph, which was recently reported by Wright et
al.,[5] to give the phosphanido-bridged complex [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+
(1; Scheme 1). The reaction was carried out at 55 °C in
dichloromethane solution, and the yield of [1][BF4] can be
increased from 30% to 38% by performing the reaction un-
der hydrogen pressure (3 bar). The reason for the use of
Figure 1. The two enantiomers of [(η6-C6Me6)(η6-p-iPrMeC6H4)-
Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+ (1).
As we failed to obtain crystals of [1][BF4] suitable for X-
ray structure analysis, we synthesized an achiral analogue
of 1 containing two hexamethylbenzene ligands. The cation
[(η6-C6Me6)2Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+ (2) is access-
ible in the same way as 1 from PPh2(CH2)3Ph and [(η6-
C6Me6)2Ru2(µ2-H)3]+ (Scheme 2). The reaction was carried
out under the same conditions as for 1 (CH2Cl2, 55 °C,
3 bar H2) and, in this case, the yield of the reaction was
much higher (85%). Dark-red crystals of [2][BF4] suitable
Scheme 1. Synthesis of [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-
PPh(CH2)3Ph}(µ2-H)2]+ (1).
Figure 2. Molecular structure of the two independent molecules of cation 2 (anions, solvent molecules, and hydrogen atoms, except for
the hydrido ligands, have been omitted for clarity).
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Dinuclear (Arene)ruthenium Complexes
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for X-ray structure analysis were obtained by slow diffusion
of hexane into a concentrated dichloromethane solution of
[2][BF4]. The molecular structure of cation 2 is shown in
Figure 2.
Scheme 3. Synthesis of [(η6-C6Me6)Ru2{µ2-PPh(CH2)3-η6-Ph}(µ2-
Br)2]+ (3).
The surprising substitution of the two hydrido bridges in
1 by two bromido bridges in 3 that occurs during arene
ligand exchange was confirmed by NMR monitoring: on
Scheme 2. Synthesis of [(η6-C6Me6)2Ru2{µ2-PPh(CH2)3Ph}(µ2-
H)2]+ (2).
1
comparing the H NMR spectra of [1][BF4] and [3][BF4] it
The single-crystal X-ray structure analysis for cation 2
reveals a PPh(CH2)3Ph moiety and two hydrido ligands
bridging the two ruthenium atoms, with each ruthenium
atom also being coordinated to an η6-C6Me6 ligand. The
Ru–Ru distances [2.670(2) and 2.767(2) Å] are similar to
those expected for a ruthenium–ruthenium double bond.
Two independent molecules are observed in the crystal
structure of [2][BF4], with the major difference between
them being the conformation of the P(CH2)3Ph unit (see
Figure 2). Thus, the C1–C2–C3–C4 torsion angle in mole-
cule A is 170(3)° (anti conformation), while in molecule B
the C41–C42–C43–C44 torsion angle is –69(2)° (syn confor-
mation). These two molecules adopt a pairwise arrange-
ment in the unit cell of [2][BF4], as shown in Figure 3. The
presence of a bridging PPh(CH2)3Ph ligand forces the arene
moieties to adopt a tilted geometry. The two C6Me6 arene
ligands are not parallel to each other, and the angles be-
tween the C6Me6 planes are 34.9(2)° and 34.4(4)° for mole-
cules A and B, respectively.
becomes clear that both the p-cymene signals and the hy-
dride signals have disappeared and that coordination of the
η6-C6H5 substituent of the pendant arm gives rise to three
3
new signals at δ = 6.25 (m, 2 H, H-ortho), 5.43 (t, JH,H
=
4.8 Hz, 1 H, H-para), and 5.04 (m, 2 H, H-meta) ppm. As
expected, the three methylene groups in the ligand arm give
rise to two signals each because the CH2 protons are dia-
4
stereotopic (Figure 4). In contrast to 1 and 2, the JP,H
coupling (1 Hz) for 3, which gives rise to a doublet at δ =
1.94 ppm, is visible for the methyl protons of the η6-C6Me6
ligand, presumably due to the almost parallel arrangement
4
of the two η6-arene ligands. A similar JP,H coupling has
been observed in the mononuclear complexes [(η6-C6Me6)-
Ru(CO)(PMe3)Me]+,[14] [(η6-C6Me6)Ru(PR3)Me2], and
[(η6-C6Me6)Ru(PR3)(OCOCF3)Me] (PR3 = PMe3, PPh3,
PMe2Ph).[15] In accordance with the presence of two brom-
ido ligands, the ESI mass spectrum of [3][BF4] shows a par-
ent peak at m/z = 752. The molecular structure of this com-
plex was finally confirmed by single-crystal X-ray analysis.
Figure 4. The two enantiomers (RP)-3 and (SP)-3.
Dark-orange crystals of [3][BF4] suitable for an X-ray
structure analysis were obtained by slow diffusion of diethyl
ether into a concentrated acetone solution of [3][BF4]. Two
enantiomers are observed independently in the asymmetric
Figure 3. Pairwise arrangement of anti-2 (molecule A) and syn-2
(molecule B) in the unit cell of [2][BF4].
The arene exchange reaction between the p-cymene li- unit of [3][BF4] (see Figure 5).
gand and the phenyl substituent in the pendant arm of the
The ruthenium atoms in [3][BF4] are in a distorted octa-
phosphanido ligand in [(η6-C6Me6)(η6-p-iPrMeC6H4)- hedral geometry in which the two metal centers are bridged
Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2]+ (1) is achieved by heating by a tethered phosphanido and two bromido ligands. The
of [1][BF4] at 150 °C in bromobenzene. The reaction leads Ru–Br bond lengths [ranging from 2.552(1) to 2.586(1) Å]
to the dibromo complex [(η6-C6Me6)Ru2{µ2-PPh(CH2)3-η6- and Ru–Br–Ru angles [ranging from 82.16(4) to 82.90(4)°]
Ph}(µ2-Br)2]+ (3; Scheme 3), and the reaction requires more are similar to those found in other dinuclear (η6-arene)-
forcing conditions than in the case of [(η6-p-iPrMeC6H4)- ruthenium complexes bridged by bromine atoms, for exam-
Ru{PPh2(CH2)3Ph}Cl2].[5] Replacement of the C6M6 ligand ple [Ru2(η6-1,3,5-C6H3Et3)2(µ2-Br)3][Re2(CO)6(µ2-Br)3] and
is not observed.
[Ru2(η6-p-iPrMeC6H4)2(µ2-Br)3][Re2(CO)6(µ2-Br)3].[16] The
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Figure 5. Molecular structure of the two independent enantiomers of cation 3 (anions and hydrogen atoms have been omitted for clarity).
Ru–Ru distances [3.3973(3) and 3.3764(3) Å] are well out- pure phosphane (R)-PPh2(CH2)2CHMePh, which contains
side the range (2.28–2.95 Å) for a metal–metal single a stereogenic carbon center and is similar to the achiral
bond.[17] The phenyl rings of the η6-arene ligands are al- analogue PPh2(CH2)3Ph. Given the fact that racemization
most parallel, with an angle between the two planes of of the stereogenic carbon atom in this ligand was not ob-
8.8(7)° in (RP)-3 and 9.8(7)° in (SP)-3. The p-cymene ligand served during the synthesis of [RuCl2{η1-(R)-PPh2(CH2)2-
in [1][BF4] is replaced by the phenyl ring of the pendant CHMe-η6-Ph}],[8c] we can assume that the (RC) configura-
arm of the phosphanido ligand upon formation of [3][BF4], tion of (R)-PPh2(CH2)2CHMePh also does not change in
which gives rise to a six-membered metallacycle. Both the reaction with the dinuclear trihydrido complex.
The trihydrido complex [(η6-C6Me6)(η6-p-iPrMeC6H4)-
Ru2(µ2-H)3]+ reacts with the enantiopure phosphane (R)-
PPh2(CH2)2CHMePh to give the cation [(η6-C6Me6)(η6-p-
iPrMeC6H4)Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2]+ (4),
which was obtained as a mixture of the two diastereomers
(RC,RP)-4 and (RC,SP)-4 (Scheme 4). The reaction was car-
ried out in dichloromethane at 55 °C under hydrogen
(3 bar). The yield of 38% is similar to that for the synthesis
of 1. Unfortunately, we were not able to separate the two
diastereomers either by crystallization or by chromatog-
raphy on silica gel.
enantiomers of 3 show a chair-like conformation for the
six-membered metallacycles (see Figure 6).
As no X-ray quality crystals of [4][BF4] could be ob-
tained, we treated the enantiopure phosphane (R)-
PPh2(CH2)2CHMePh with the bis(hexamethylbenzene) an-
alogue [(η6-C6Me6)2Ru2(µ2-H)3]+ to obtain [(η6-C6Me6)2-
Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2]+ (5; Scheme 5).
The dark-red crystals of [5][BF4] obtained by slow dif-
Figure 6. Capped-stick representation of the chair-like conforma-
tion observed in cations (RP)-3 and (SP)-3.
In order to obtain a mixture of diastereomers instead of
a racemic mixture of enantiomers we decided to treat [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3]+ with the enantio- fusion of diethyl ether into a concentrated solution of
Scheme 4. Synthesis of [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-(R)-PPh(CH2)2CH-MePh}(µ2-H)2]+ (4).
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Dinuclear (Arene)ruthenium Complexes
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Scheme 5. Synthesis of [(η6-C6Me6)2Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2]+ (5).
[5][BF4] in dichloromethane were found to be suitable for
The centrosymmetric space group P21/c of [5][BF4] sug-
X-ray analysis. The molecular structure of cation 5 was con- gests a racemic mixture of (RC) and (SC) enantiomers of 5
firmed by X-ray crystal structure analysis of its tetrafluo- in the crystal. However, the stereogenic carbon atom (C3 in
roborate salt (Figure 7).
Figure 7) in 5 is highly disordered, as demonstrated by the
exceptionally stretched ellipsoid along the C–H axis in the
ORTEP plot (Figure 7), which may give rise to a centrosym-
metric space group despite retention of the (RC) configura-
tion. The Ru–Ru distance [2.6346(8) Å] is similar to those
observed in [2][BF4] and remains within the range of a ru-
thenium–ruthenium double bond. As in [2][BF4], the pres-
ence of a bridging phosphanido ligand forces the arene moi-
eties to adopt a tilted geometry. The angle between the two
C6Me6 planes is 38.8(2)°.
As the question of the enantiomeric purity of 5 could
not be solved by X-ray crystallography because of the cen-
trosymmetric space group (P21/c) and disorder problems,
we used circular dichroism to find out whether or not the
stereogenic carbon center in the side-chain has racemized
during the synthesis of 5, despite the known enantiostability
of (R)-PPh2(CH2)2CHMePh.[8c] Although the concentra-
tion-dependent CD signal at 350 nm (Figure 8) shows 5 to
be optically active, which suggests that the stereogenic car-
bon center has (R) configuration, we cannot exclude partial
racemization during the synthesis of this compound.
As in the case of 1, the ligand exchange reaction between
p-cymene and the phenyl substituent on the pendant arm
Figure 7. Molecular structure of cation 5 (anion and hydrogen
atoms other than the hydrido ligands have been omitted for clar-
ity).
Figure 8. CD (left) and UV/Vis (right) spectra of [5][BF4] recorded in CH2Cl2 at two different concentrations (c1 = 5.05ϫ10–4 , c2 =
1.67ϫ10–3 ), m° = 10–3°.
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was achieved by heating of [(η6-C6Me6)(η6-p-iPrMeC6H4)- with a Flack parameter of 0.23(2). Both diastereomers,
Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2]+ (4) at 150 °C in (RC,RP)-6 and (RC,SP)-6, show the two ruthenium atoms to
bromobenzene. This reaction also leads to the dibromido be in a distorted octahedral geometry in which the metal
derivative
[(η6-C6Me6)Ru2{µ2-(R)-PPh(CH2)2CHMe-η6-
Ph}(µ2-Br)2]+ (6; Scheme 6), which was obtained as a mix-
ture of (RC,SP) and (RC,RP) diastereomers (Figure 9).
Scheme 6. Synthesis of [(η6-C6Me6)Ru2{µ2-(R)-PPh(CH2)2CHMe-
η6-Ph}(µ2-Br)2]+ (6).
Figure 10. The molecular structure of the diastereomers of cation
6 (anions, solvent molecules, and hydrogen atoms have been omit-
ted for clarity).
Figure 9. The two diastereomers (RC,RP)-6 and (RC,SP)-6.
Single crystals suitable for an X-ray structure analysis
were obtained by slow diffusion of diethyl ether into a con-
centrated acetone solution of [6][BF4]. Examination of the
structure with PLATON[18] revealed an ambiguity over the
¯
choice of the space group (P1 or P1). Expecting a chiral
molecule, resolution was performed in the noncentrosym-
Figure 11. The chair-like (left) and half-twist-like (right) conforma-
metric group P1. The structure was refined to convergence tions in cation 6.
1
Figure 12. Selected H NMR signals ([D6] acetone) of the diastereomeric mixture of [6][BF4].
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Figure 13. CD and UV/Vis spectra of [6][BF4] at two different concentrations (c1 = 5.86ϫ10–4 , c2 = 2.05ϫ10–3 ).
centers are bridged by a tethered phosphanido and two bro- ruthenium atom and a phenyl substituent in the side-arm of
mido ligands (Figure 10). The Ru–Br bond lengths (average the phosphanido bridge leads to chiral tethered derivatives.
2.572 Å) and the Ru–Br–Ru angles (average 82.15°) are sim- Introduction of a stereogenic carbon atom in the pendant
ilar to those found in [3][BF4]. Similarly, the Ru–Ru dis- arm of the phosphanido bridging ligand gives rise to the
tances [identical at 3.380(2) Å] are similar to those observed formation of diastereomeric complexes.
in [3][BF4]. The two η6-arene ligands are almost parallel to
each other in both molecules, with an angle between the
Experimental Section
two aromatic planes of 10.2(4)° for the (RC,SP) and 12.1(4)°
for the (RC,RP) isomer. Replacement of the p-cymene ligand
by a phenyl ring at the pendant arm of the phosphanido
ligand in [6][BF4] generates a six-membered metallacycle
upon coordination. Surprisingly, two conformations are ob-
served for the six-membered metallacycle, a chair-like
(RC,SP) and a half-twist-like (RC,RP) conformation for the
diastereomers of 6 (Figure 11).[19]
General Remarks: All manipulations were carried out under nitro-
gen using standard Schlenk techniques. All solvents were degassed
with nitrogen prior to use. The silica gel (type G) used for prepara-
tive thin-layer chromatography was purchased from Macherey–Na-
gel GmbH. The phosphanes were synthesized according to pre-
viously described methods.[5,8c] The starting compounds [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3][BF4][13] and [(C6Me6)2Ru2-
(µ2-H)3][BF4][20] were synthesized according to previously described
methods. Bromobenzene (puriss.) was purchased from Fluka,
stored under nitrogen, and dried with molecular sieves (4 Å).
Deuterated NMR solvents were purchased from Cambridge Iso-
tope Laboratories, Inc. NMR spectra were recorded with a Bruker
400 MHz spectrometer. Mass spectra were recorded by Prof. Titus
Jenny at the University of Fribourg. Microanalyses were carried
out in the Laboratory of Pharmaceutical Chemistry at the Univer-
sity of Geneva.
The two diastereomers (RC,SP)-6 and (RC,RP)-6 are dis-
1
tinguishable in the H NMR spectrum, which shows two
doublets of almost equal intensity for the η6-C6Me6 protons
4
at δ = 1.95 and 1.94 ppm. As in 3, the JP,H coupling
(0.9 Hz) is also observable for the methyl protons of the η6-
C6Me6 ligand in 6 since the two arene ligands in this com-
plex are almost parallel to each other. Accordingly, two sig-
nals are observed for the para protons of the η6-C6H5 li-
gand [δ = 5.48 (t) and 5.31 ppm (t)] and for the methyl
substituent at the stereogenic carbon atom [δ = 1.29 (d) and
Synthesis of [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-PPh(CH2)3Ph}-
(µ2-H)2][BF4] [1][BF4]: [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3]-
[BF4] (230 mg, 0.39 mmol) was dissolved in dichloromethane
(250 mL) in a pressure Schlenk tube and the phosphane PPh2-
(CH2)3Ph (178 mg, 0.58 mmol) was added. The solution was then
flushed and pressurized with hydrogen (3 bar) and stirred at 55 °C
under hydrogen pressure for 18 h. After cooling to room tempera-
ture, the solvent was evaporated to dryness and the brown product
obtained was purified by preparative thin-layer chromatography on
silica gel (acetone/dichloromethane, 1:10). The product was ex-
tracted from the silica with acetone from the brown band, and
evaporation of the solvent gave the pure product (yield: 38%,
1
1.20 (d) ppm]. The integration of the H NMR signals sug-
gests that both diastereomers are present in almost equal
quantities, with a slight excess of one (52:48; Figure 12).
This diastereoselectivity (de = 4%) was confirmed by circu-
lar dichroism: The CD spectrum of [6][BF4] in dichloro-
methane, recorded at two different concentrations, indeed
shows a small concentration-dependent CD signal centered
at 460 nm (Figure 13).
120 mg, 0.15 mmol). 1H NMR (400 MHz, [D6]acetone, 25 °C): δ =
7.32–7.20 (m, 8 H, H-Ph), 7.04 (m, 2 H, H-Ph), 6.03 (t, JH,H
3
=
Conclusions
3
5 Hz, 2 H, H-Ar p-cymene), 5.72 (d, JH,H = 5.9 Hz, 1 H, H-Ar p-
3
We have synthesized several chiral-at-phosphorus phos-
phanidodiruthenium complexes and shown that an intra-
cymene), 5.65 (d, JH,H
=
6.2 Hz,
1
H, H-Ar p-cymene),
H, H-iPr,
2.73 (m, H, PPhCH2CH2CH2Ph), 2.57 (m,
2
3
molecular ligand exchange between one arene ligand at the PPhCH2CH2CH2Ph), 2.11 [s, 18 H, C6(Me)6], 2.02 (s, 3 H,
Eur. J. Inorg. Chem. 2007, 3091–3100
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3097

M. J.-L. Tschan, G. Süss-Fink, F. Chérioux, B. Therrien
FULL PAPER
CH3C6H4iPr), 1.27 [t, 3JH,H = 7 Hz, 6 H, CH(CH3)2] 0.89 (m, 2 H,
(η6-Ph), 30.2 (d, JC,P = 33 Hz, CH2), 24.5 (d, JC,P = 7 Hz, CH2),
2
2
PPhCH2CH2CH2Ph), –14.65 (dd, JH,H = 2.8, JH,P = 28 Hz, 1 H, 20.2 (d, JC,P = 16 Hz, CH2), 15.3 [C6(CH3)6] ppm. 31P{1H} NMR
2
2
hydride), –16.06 (dd, JH,H = 2.8, JH,P = 31 Hz, 1 H, hydride)
(160 MHz, [D6]acetone, 25 °C): δ = –14.53 (s) ppm. MS (ESI): m/z
ppm. 13C{1H} NMR (100 MHz, [D6]acetone, 25 °C): δ = 142.7 (C- = 752 [M + H]+. C27H34BBr2F4PRu2 (838.29): calcd. C 38.68, H
Ar), 142.1 (C-Ar), 132.67 (C-Ar), 132.5 (C-Ar), 129.6 (C-Ar), 129.6
(C-Ar), 129.4 (C-Ar), 129.3 (C-Ar), 129.2 (C-Ar), 128.37 (C-Ar),
128.2 (C-Ar), 126.7 (C-Ar), 99.2 (MeiPrC6H4), 97.4 [C6(Me)6], 97.2
(MeiPrC6H4), 85.3 (MeiPrC6H4), 84.6 (MeiPrC6H4), 82.8 (Me-
iPrC6H4), 81.5 (MeiPrC6H4), 37.1 (d, JC,P = 18 Hz, CH2), 32.7
(CH2), 31.7 (d, JC,P = 6.4 Hz, CH2), 23.7 [CH(CH3)2], 23.7
[CH(CH3)2], 20.3 (C6H4CH3), 17.5 [C6(CH3)6] ppm. 31P{1H} NMR
(160 MHz, [D6]acetone, 25 °C): δ = 114.62 (s) ppm. MS (ESI): m/z
= 728 [M + H]+. C37H50BF4PRu2 (814.71): calcd. C 54.54, H 6.18;
found C 54.51, H 6.20.
4.08; found C 38.75, H 4.16.
Synthesis of [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-(R)-PPh(CH2)2-
CHMePh}(µ2-H)2][BF4] [4][BF4]: Synthesis of this complex fol-
lowed the procedure described for [1][BF4] but with [(η6-
C6Me6)(η6-p-iPrMeC6H4)Ru2(µ2-H)3][BF4] (260 mg, 0.44 mmol)
and (R)-PPh2(CH2)2CHMePh (210 mg, 0.66 mmol) as starting ma-
terials. The product was extracted from the brown band with ace-
tone, and evaporation of the solvent gave the pure product (yield:
38%, 138 mg, 0.17 mmol). 1H NMR (400 MHz, [D6]acetone,
25 °C): δ = 7.32 (m, 16 H, H-Ph), 6.98 (m, 4 H, H-Ph β of P), 6.09
3
3
Synthesis
of
[(η6-C6Me6)2Ru2{µ2-PPh(CH2)3Ph}(µ2-H)2][BF4] (d, JH,H = 6 Hz, 1 H, p-iPrMeC6H4), 6.04 (d, JH,H = 5.4 Hz, 1
[2][BF4]: [(η6-C6Me6)2Ru2(µ2-H)3][BF4] (150 mg, 0.24 mmol) was
dissolved in dichloromethane (200 mL) in a pressure Schlenk tube
and the phosphane PPh2(CH2)3Ph (93 mg, 0.30 mmol) was added.
The solution was then flushed and pressurized with hydrogen
(3 bar) and stirred at 55 °C under hydrogen pressure for 18 h. After
cooling to room temperature, the solvent was evaporated to dryness
and the brown product obtained was purified by preparative thin-
layer chromatography on silica gel (acetone/dichloromethane,
1:10). The product was extracted with acetone from the brown
band, and evaporation of the solvent gave the pure product (yield:
85%, 172 mg, 0.20 mmol). Crystals suitable for X-ray structure
analysis were obtained by diffusion of diethyl ether into a concen-
H, p-iPrMeC6H4), 5.98 (d, JH,H = 5.4 Hz, 1 H, p-iPrMeC6H4),
3
3
3
5.95 (d, JH,H = 6 Hz, 1 H, p-iPrMeC6H4), 5.75 (d, JH,H = 6 Hz,
3
1 H, p-iPrMeC6H4), 5.70 (t, JH,H = 6.6 Hz, 1 H, p-iPrMeC6H4),
3
5.64 (d, JH,H = 5.8 Hz, 1 H, p-iPrMeC6H4), 2.88 [m, 2 H,
MeC6H4CH(CH3)2], 2.7–2.2 [m, 6 H, PhCH(CH3)CH2CH2PPh2],
2.13 [s, 18 H, C6(CH3)6], 2.06 [s, 18 H, C6(CH3)6], 2.02 [s, 3 H,
MeC6H4CH(CH3)2], 1.98 [s, 3 H, MeC6H4CH(CH3)2], 1.28 [m, 18
H, MeC6H4CH(CH3)2, PhCH(CH3)CH2CH2PPh2], 1.25–0.7 [m, 4
2
2
H, PhCH(CH3)CH2CH2PPh2], –14.68 (td, JH,H = 2.8, JH,P
=
2
2
27.6 Hz, 2 H, hydride), –16.04 (dd, JH,H = 2.8, JH,P = 30.7 Hz, 1
H, hydride), –16.10 (dd, 2JH,H = 2.8, 2JH,P = 30.9 Hz, 1 H, hydride)
ppm. 13C{1H} NMR (100 MHz, [D6]acetone, 25 °C): δ = 147.2 (C-
Ar), 147.2 (C-Ar), 141.7 (C-Ar), 141.5 (C-Ar), 132.2 (C-Ar), 132.1
(C-Ar), 129.2 (C-Ar), 129.2 (C-Ar), 128.8 (C-Ar), 128.8 (C-Ar),
1
trated dichloromethane solution of [2][BF4]. H NMR (400 MHz,
[D6]acetone, 25 °C): δ = 7.38–7.20 (m, 8 H, H-Ph), 6.95 (m, 2 H,
H-Ph), 2.78 (t, 3JH,H = 7.4 Hz, 2 H, PPhCH2CH2CH2Ph), 2.55 (m, 127.9 (C-Ar), 127.8 (C-Ar), 127.5 (C-Ar), 127.3 (C-Ar), 126.6 (C-
2 H, PPhCH2CH2CH2Ph), 2.17 [s, 18 H, C6(CH3)6], 0.86 (m, 2 H, Ar), 113.3 (C-Ar), 98.8 (MeiPrC6H4), 98.3 (MeiPrC6H4), 97.1
2
2
PPhCH2CH2CH2Ph), –15.18 (dd, JH,H = 3, JH,P = 28 Hz, 1 H, [C6(CH3)6], 97.0 [C6(CH3)6], 96.8 (MeiPrC6H4), 85.2 (MeiPrC6H4),
2
hydride), –16.50 (dd, 2JH,H = 3, JH,P = 30 Hz, 1 H, hydride) ppm.
84.8 (MeiPrC6H4), 84.2 (MeiPrC6H4), 83.9 (MeiPrC6H4), 82.9
13C{1H} NMR (100 MHz, [D6]acetone, 25 °C): δ = 142.4 (C-Ar), (MeiPrC6H4), 81.2 (MeiPrC6H4), 81.1 (MeiPrC6H4), 41.1 (CHMe),
132.1 (C-Ar), 132.0 (C-Ar), 128.9 (C-Ar), 128.8 (C-Ar), 128.0 (C- 40.9 (d, JC,P = 4.3 Hz, CH2), 38.2 (d, JC,P = 21 Hz, CH2), 32.3
Ar), 127.9 (C-Ar), 126.3 (C-Ar), 96.9 [C6(Me)6], 36.7 (d, JC,P
=
[CH(CH3)2], 23.3 [CH(CH3)], 23.3 [CH(CH3)2], 21.5 [CH(CH3)2],
20 Hz, CH2), 31.8 (CH2), 31.52 (d, JC,P = 12 Hz, CH2), 17.4 21.2 (C6H4CH3), 20.0 [CH(CH3)],17.2 [C6(CH3)6], 17.2 [C6(CH3)6]
[C6(CH3)6] ppm. 31P{1H} NMR (160 MHz, [D6]acetone, 25 °C): δ ppm. 31P{1H} NMR (160 MHz, [D6]acetone, 25 °C): δ = 114.82
= 101.73 (s) ppm. MS (ESI): m/z 756 [M + H]+. C39H56BF4PRu2
(s), 114.73 (s) ppm. MS (ESI): m/z = 742 [M +
H]+.
(844.78): calcd. C 55.45, H 6.68; found C 55.39, H 6.61.
C38H54BF4PRu2 (830.75): calcd. C 54.93, H 6.55; found C 55.09,
H 6.72.
Synthesis of [(η6-C6Me6)Ru2{µ2-PPh(CH2)3-η6-Ph}(µ2-Br)2][BF4]
[3][BF4]: [(η6-C6Me6)(η6-p-iPrMeC6H4)Ru2{µ2-PPh(CH2)3Ph}(µ2-
H)2][BF4] (120 mg, 0.15 mmol) was dissolved in bromobenzene
(25 mL) that had been dried with molecular sieves (4 Å) and satu-
rated with nitrogen prior to use. The solution was heated at 150 °C
for 20 h. After cooling to room temperature, the solvent was evapo-
Synthesis of [(η6-C6Me6)2Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-
H)2][BF4] [5][BF4]: Synthesis of this complex followed the pro-
cedure described for [2][BF4] but with [(η6-C6Me6)2Ru2(µ2-H)3]-
[BF4] (100 mg, 0.16 mmol) and (R)-PPh2(CH2)2CHMePh (57 mg,
0.18 mmol) as starting materials. The product was extracted from
rated to dryness in a trap-to-trap apparatus. The brown-red prod- the brown band with acetone, and evaporation of the solvent gave
uct obtained was purified by preparative thin-layer chromatog-
raphy on silica gel (acetone/dichloromethane, 1:10). The product
was extracted with acetone from the lowest major orange band (Rf
= 0.4). Evaporation of the solvent gave the pure product (yield:
30%, 38 mg, 0.045 mmol). Crystals suitable for X-ray structure
analysis were obtained by slow diffusion of diethyl ether into a
concentrated acetone solution of [3][BF4]. 1H NMR (400 MHz,
the pure product (yield: 86%, 117 mg, 0.14 mmol). Crystals suitable
for X-ray structure analysis were obtained by slow diffusion of di-
ethyl ether into a concentrated acetone solution of [5][BF4]. 1H
NMR (400 MHz, [D2]dichloromethane, 25 °C): δ = 7.36–7.17 (m,
3
8 H, H-Ph), 6.75 (m, 2 H, H-Ph), 2.76 [q, JH,H = 7 Hz, 1 H,
PhCH(CH3)(CH2)2PPh2], 2.40–2.10 [m,
2 H, PhCH(CH3)-
CH2CH2PPh2], 2.13 [s, 18 H, C6(CH3)6], 2.05 [s, 18 H, C6(CH3)6],
3
[D6]acetone, 25 °C): δ = 7.96 (br., 2 H, P-Ph), 7.53 (m, 3 H, P-Ph), 1.29 [d, JH,H = 7 Hz, 3 H, PPhCH(CH3)CH2CH2Ph] 0.65 [m, 2
3
2
2
6.25 (m, 2 H, H-ortho η6-Ph), 5.43 (t, JH,H = 4.8 Hz, 1 H, H-para
H, PPhCH(CH3)CH2CH2Ph], –15.28 (dd, JH,H = 3, JH,P =
η6-Ph), 5.04 (m, 2 H, H-meta η6-Ph), 3.44 (m, 1 H, CH2), 3.05 (td,
28.1 Hz, 1 H, hydride), –16.67 (dd, JH,H = 3, JH,P = 31.3 Hz, 1
2
2
2
3JH,H = 3.7, JH,H = 15.3 Hz, 1 H, CH2), 2.58 (m, 1 H, CH2), 2.38 H, hydride) ppm. 13C{1H} NMR (100 MHz, [D6]acetone, 25 °C):
4
(m, 1 H, CH2), 1.98 (m, 1 H, CH2), 1.94 [d, JP,H = 1 Hz, 18 H,
δ = 147.3 (Ph), 140.8 (Ph), 132.1 (Ph), 132.0 (Ph), 128.9 (Ph), 128.8
C6(CH3)6], 1.40 (m, 1 H, CH2) ppm. 13C{1H} NMR (100 MHz, (Ph), 128.0 (Ph), 127.9 (Ph), 127.3 (Ph), 126.6 (Ph), 96.9 [C6-
[D6]acetone, 25 °C): δ = 136.6 (P-Ph), 136.4 (P-Ph), 130.6 (P-Ph), (CH3)6], 41.1 (d, JC,P = 18 Hz, CH2), 41.0 (CH), 38.2 (d, JC,P
=
130.6 (P-Ph), 129.2 (P-Ph), 129.1 (P-Ph), 99.2 (η6-Ph), 94.9 (η6-
Ph), 93.8 [C6(CH3)6], 84.9 (η6-Ph), 82.0 (η6-Ph), 81.7 (η6-Ph), 72.5
8 Hz, CH2), 21.2 [CH(CH3)] 17.4 [C6(CH3)6], 17.3 [C6(CH3)6] ppm.
31P{1H} NMR (160 MHz, [D6]acetone, 25 °C): δ = 102.33 (s) ppm.
3098
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3091–3100

Dinuclear (Arene)ruthenium Complexes
Table 1. Crystallographic and selected experimental data for [2][BF4]·0.5CH2Cl2, [3][BF4], [5][BF4], and [6][BF4]·(CH3)2CO.
FULL PAPER
[2][BF4]·0.5CH2Cl2
[3][BF4]
[5][BF4]
[6][BF4]·(CH3)2CO
Empirical formula
Formula mass
Crystal system
Space group
Crystal color and shape
Crystal size
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C39.5H55BClF4PRu2
885.21
orthorhombic
Pca21
C27H34BBr2F4PRu2
838.28
C40H56BF4PRu2
856.77
monoclinic
P21/c
red plate
0.40ϫ0.28ϫ0.10
10.756(2)
C31H42BBr2F4OPRu2
910.39
triclinic
triclinic
¯
P1
P1
red block
orange plate
0.48ϫ0.20ϫ0.07
10.4799(11)
16.6813(17)
18.038(2)
99.150(15)
105.969(14)
102.461(12)
2879.1(5)
red block
0.46ϫ0.28ϫ0.12
10.4690(9)
11.3906(9)
15.5091(13)
95.506(10)
101.751(10)
110.354(9)
1669.4(2)
2
0.85ϫ0.28ϫ0.12
18.7393(15)
20.0175(10)
20.8971(18)
20.776(4)
17.745(4)
104.29(3)
γ [°]
V [Å3]
7838.8(10)
8
3842.7(13)
4
Z
4
T [K]
173(2)
1.500
0.926
173(2)
1.934
3.923
173(2)
1.481
0.874
173(2)
1.811
3.393
Dc [gcm–3]
µ [mm–1]
Scan range [°]
Unique reflections
Reflections used [I Ͼ 2σ(I)]
Rint
4.62 Ͻ 2θ Ͻ 54.18
11455
2657
3.92 Ͻ 2θ Ͻ 51.96
9529
3436
4.74 Ͻ 2θ Ͻ 51.64
5612
3860
4.32 Ͻ 2θ Ͻ 51.98
10511
8765
0.0766
0.0739
0.0484
0.0495
Final R indices [I Ͼ 2σ(I)][a]
R indices (all data)
Goodness-of-fit
Max/min ∆ρ/e [Å–3]
0.0464, wR2 0.0713
0.2138, wR2 0.1234
0.469
0.0467, wR2 0.0748
0.1615, wR2 0.0899
0.672
0.0511, wR2 0.1468
0.0789, wR2 0.1620
1.033
0.0635, wR2 0.1659
0.0760, wR2 0.2010
1.096
0.441, –0.499
1.225, –1.183
0.763, –0.845
1.640, –3.755
2
2 2
2
[a] Structures were refined on Fo2: wR2 = {Σ[w(Fo – Fc ) ]/Σw(Fo2)2}1/2, where w–1 = [Σ(Fo2) + (aP)2 + bP] and P = [max(Fo2,0) + 2Fc ]/
3.
MS (ESI): m/z = 770 [M + H]+. C40H56BF4PRu2 (856.79): calcd.
C 56.07, H 6.58; found C 56.03, H 6.51.
Synthesis of [(η6-C6Me6)Ru2{µ2-(R)-PPh(CH2)2CHMe-η6-Ph}(µ2-
Br)2][BF4] [6][BF4]: Synthesis of this complex followed the pro-
cedure described for [3][BF4] but with [(η6-C6Me6)(η6-p-iPrMe-
(λ = 0.71073 Å). Data were collected in the φ range 0–200°, with
increments of 1.2°, 1.5°, 1.0° and 1.0°, respectively, in the 2θ range
from 2.0–26° (Dmax–Dmin = 12.45–0.81 Å). The structures were
solved by direct methods using the program SHELXS-97.[21] Re-
finement and all further calculations were carried out using
SHELXL-97.[22] The H atoms were included in calculated positions
and treated as riding atoms using the SHELXL default parameters
in all cases. The non-H atoms were refined anisotropically, using
weighted full-matrix least squares on F2. Crystallographic details
are summarized in Table 1. Figures 2, 5, 7, and 10 were drawn with
ORTEP,[23] while Figures 3, 6, and 11 were produced with the pro-
gram MERCURY.[24] CCDC-629980 ([2][BF4]·0.5CH2Cl2), -629981
([3][BF4]), -629982 ([5][BF4]), and -629983 {[6][BF4]·(CH3)2CO}
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
C6H4)Ru2{µ2-(R)-PPh(CH2)2CHMePh}(µ2-H)2][BF4]
(110 mg,
0.13 mmol) as starting material. The product was extracted from
the lowest main orange band (Rf = 0.4) with acetone and evapora-
tion of the solvent gave the pure product (yield: 40%, 45 mg,
0.053 mmol). Crystals suitable for X-ray structure analysis were ob-
tained by slow diffusion of diethyl ether into a concentrated ace-
tone solution of [6][BF4]. 1H NMR (400 MHz, [D6]acetone, 25 °C):
δ = 7.97 (br., 4 H, P-Ph), 7.54 (m, 6 H, P-Ph), 6.25 (m, 4 H, η6-
3
3
Ph), 5.47 (t, JH,H = 4.9 Hz, 1 H, η6-Ph), 5.30 (t, JH,H = 4.5 Hz,
1 H, η6-Ph), 5.05 (m, 4 H, η6-Ph), 3.52 (m, 1 H, CH2), 3.27 (m, 1
H, CH2), 2.98 (m, 1 H, CH), 2.70–2.0 (m, 5 H, CH, CH2), 1.95 [d,
Crystallographic
data_request/cif.
Data
Centre
via
www.ccdc.cam.ac.uk/
4JP,H = 0.9 Hz, 18 H, C6(CH3)6], 1.94 [d, JP,H = 0.9 Hz, 18 H,
C6(CH3)6], 1.64 (m, 1 H, CH2), 1.52 (m, 1 H, CH2), 1.29 (d, JH,H
= 6.6 Hz, 3 H, CH3), 1.20 (d, JH,H = 7 Hz, 3 H, CH3) ppm.
4
3
3
Acknowledgments
13C{1H} NMR (100 MHz, [D6]acetone, 25 °C): δ = 137.6 (P-Ph),
137.6 (P-Ph), 134.0 (br., P-Ph), 132.6 (P-Ph), 132.0 (P-Ph), 131.7
(P-Ph), 130.2, 130.2 (br., P-Ph), 130.0 (P-Ph), 129.9 (P-Ph), 129.3
(P-Ph), 128.5 (P-Ph), 99.0 (η6-Ph), 96.1 (η6-Ph), 94.9 [C6(CH3)6],
90.7 (η6-Ph), 90.3 (η6-Ph), 83.8 (η6-Ph), 82.2 (η6-Ph), 81.9 (η6-Ph),
78.1 (η6-Ph), 75.0 (η6-Ph), 73.5 (η6-Ph), 72.7 (η6-Ph), 39.1 (CH2),
34.2 (d, JC,P = 15 Hz, CH2), 31.8 (CH), 29.1, 24.5 [CH(CH3)], 23.5,
20.0, 16.4 [C6(CH3)6] ppm. 31P{1H} NMR (160 MHz, [D6]acetone,
25 °C): δ = –8.71 (s), –9.82 (s) ppm. MS (ESI): m/z = 766
[M + H]+. C28H36BBr2F4PRu2 (852.31): calcd. C 39.45, H 4.26;
found C 39.65, H 4.45.
Financial support from the Fond National Suisse de la Recherche
Scientifique is gratefully acknowledged. The authors are also in-
debted to the Johnson Mathey Technology Centre for a loan of
ruthenium trichloride hydrate and to Professor H. Stoeckli-Evans
for free access to X-ray facilities.
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Received: December 11, 2006
Published Online: June 6, 2007
3100
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