Reactivity of the unsaturated complex [(C6Me6) 2Ru2(μ2-H)3]+ toward phosphines: Synthesis and molecular structure of the dinuclear cations [(C 6Me6)2Ru2(μ2-PR

Article abstract of DOI:10.1021/om049025n

The unsaturated trihydrido complex [(C₆Me₆) ₂Ru₂(μ₂-H)₃]⁺ reacts with diaryl- or dialkylphosphines PR₂H to give the dinuclear cations [(C₆Me₆)₂Ru₂(μ₂- PR₂)(μ₂-H)₂]⁺ (R= Ph, 1; R = t-Bu, 2). Surprisingly, complexes of the type [(C₆Me ₆)₂Ru₂(μ₂-PR₂) (μ₂-H)₂]⁺ with R = Ph (1), n-Bu (3), n-Oct (4) are also accessible in high yield from the reaction of [(C ₆Me₆)₂Ru₂-(μ₂-H) ₃]⁺ with the corresponding triaryl- or trialkylphosphine PPh₃, P(n-Bu)₃, or P(n-Oct)₃ by carbon-phosphorus bond cleavage. A possible intermediate of the reaction with PPh₃, [(C₆Me₆)₂Ru ₂(μ₂-PPh₂)(μ₂-H) (μ₂-Ph)]⁺ (5), could be isolated from the reaction mixture as the tetrafluoroborate salt, the single-crystal X-ray structure analysis of which reveals a bridging phenyl ligand coordinated in an η¹-μ₂ fashion to the diruthenium backbone. With the mixed phosphine PMe₂Ph, [(C₆Me₆) ₂Ru₂(μ₂-H)₃]⁺ reacts to give [(C₆Me₆) ₂Ru₂(μ₂-PMe₂)(μ₂-H) ₂]⁺ (6) and the corresponding intermediate [(C ₆Me₆)₂Ru₂(μ₂-PMe ₂)(μ₂-H)(μ₂-Ph)]⁺ (7). All dinuclear cations are isolated as the tetrafluoroborate salts.

Full text of DOI:10.1021/om049025n

1974
Organometallics 2005, 24, 1974-1981
Reactivity of the Unsaturated Complex
[(C6Me6)2Ru2(µ2-H)3]+ toward Phosphines: Synthesis and
Molecular Structure of the Dinuclear Cations
[(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ and Characterization of the
P-C Bond Activation Intermediate
[(C6Me6)2Ru2(µ2-PPh2)(µ2-H)(µ2-Ph)]+†
Mathieu J.-L. Tschan,‡ Fre´de´ric Che´rioux,§ Lydia Karmazin-Brelot,‡ and
Georg Su¨ss-Fink*,‡
Institut de Chimie, Universite´ de Neuchaˆtel, Avenue de Bellevaux 51, CH-2007 Neuchaˆtel,
Suisse, Laboratoire FEMTO-ST/LPMO, CNRS UMR 6174, 32 Avenue de l’Observatoire,
F-25044 Besanc¸on, France
Received December 9, 2004
The unsaturated trihydrido complex [(C6Me6)2Ru2(µ2-H)3]+ reacts with diaryl- or dialkyl-
phosphines PR2H to give the dinuclear cations [(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ (R) Ph, 1; R
) t-Bu, 2). Surprisingly, complexes of the type [(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ with R ) Ph
(1), n-Bu (3), n-Oct (4) are also accessible in high yield from the reaction of [(C6Me6)2Ru2-
(µ2-H)3]+ with the corresponding triaryl- or trialkylphosphine PPh3, P(n-Bu)3, or P(n-Oct)3
by carbon-phosphorus bond cleavage. A possible intermediate of the reaction with PPh3,
[(C6Me6)2Ru2(µ2-PPh2)(µ2-H)(µ2-Ph)]+ (5), could be isolated from the reaction mixture as the
tetrafluoroborate salt, the single-crystal X-ray structure analysis of which reveals a bridging
phenyl ligand coordinated in an η1-µ2 fashion to the diruthenium backbone. With the mixed
phosphine PMe2Ph, [(C6Me6)2Ru2(µ2-H)3]+ reacts to give [(C6Me6)2Ru2(µ2-PMe2)(µ2-H)2]+ (6)
and the corresponding intermediate [(C6Me6)2Ru2(µ2-PMe2)(µ2-H)(µ2-Ph)]+ (7). All dinuclear
cations are isolated as the tetrafluoroborate salts.
Introduction
of a ligand at the second metal center. However, to the
best of our knowledge, P-C cleavage in tertiary phos-
phines is known only for triarylphosphines and has
never been observed for trialkylphosphines, because of
competition between C-H activation and C-P activa-
tion in these compounds.3 However, the cleavage of
carbon-phosphorus bonds has been observed in the
case of alkyl-substituted diphosphines such as bis-
(dimethylphosphino)methane and bis(diphenylphos-
phino)methane.4 In ruthenium chemistry, C-P bond
cleavage has been almost exclusively observed with
arylphosphines in the case of carbonyl clusters, leading
to aryl-bridged ruthenium clusters.5
Tertiary phosphines are without any doubt among the
most important ligand systems used in organometallic
chemistry and in molecular catalysis.1 It is almost
impossible to quote all the applications of phosphines
in coordination chemistry and catalysis in the face of
the plethora of complexes and reactions even of the most
frequently used phosphines such as PPh3
1d,f
and P(n-
Bu)3.1e The cleavage of carbon-phosphorus bonds has
been observed in numerous cases, essentially by pyro-
lyzing metal carbonyl complexes with aromatic phos-
phines; these reactions are referenced in several exten-
sive reviews.2 In most of these cases, the triarylphosphine
ligand PR3, previously coordinated to a metal center in
di- or oligonuclear complexes, undergoes P-C bond
cleavage to give a phosphido-bridged derivative, the loss
of an aryl substituent R being accompanied by the loss
Over the three past decades, arene ruthenium com-
plexes have been extensively studied6 because of their
(2) (a) Garrou, P. E. Chem. Rev. 1985, 85, 171. (b) Lavigne, G. In
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D., Kaesz, H. D., Eds.; VCH: New York, 1990. (c) Kong, K. C.; Cheng,
C. H. J. Am. Chem. Soc. 1991, 113, 6313. (d) Morita, D. K.; Stille, J.
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4750.
* To whom correspondence should be addressed. E-mail: georg-
.suess-fink@unine.ch. Fax: 413 2718 2511. Tel: 413 2718 2405.
† Dedicated to Prof. Helen Stoeckli-Evans, from the University of
Neuchaˆtel, on the occasion of her 60th birthday.
‡ Universite´ de Neuchaˆtel.
§ Laboratoire FEMTO-ST/LPMO, CNRS UMR 6174.
(1) (a) van Leeuwen, P. W. N. M.; Kamer, P. C. J.; Reek, J. N. H.;
Dierkes, P. Chem. Rev. 2000, 100, 2741. (b) Tolman, C. A.; Faller, J.
W. In Homogeneous Catalysis with Metal Phosphine Complexes;
Pignolet, L. H., Ed.; Plenum Press: New York, 1983; pp 13-109. (c)
Forster, D. Adv. Organomet. Chem. 1979, 17, 255. (d) Evans, D.;
Osborn, J. A.; Wilkinson, G. J. Chem. Soc. A 1968, 3133. (e) Young, J.
F.; Osborn, J. A.; Jardine, F. H.; Wilkinson, G. J. Chem. Soc., Chem.
Commun. 1965, 7, 131. (f) Cannel, L. G.; Slaugh, L. H.; Mullineaux,
R. D. Chem. Abstr. 1965, 62, 16054.
10.1021/om049025n CCC: $30.25 © 2005 American Chemical Society
Publication on Web 03/15/2005

Reactivity of [(C6Me6)2Ru2(µ2-H)3]+ toward Phosphines
Organometallics, Vol. 24, No. 8, 2005 1975
potential to develop hydrogenation catalysts for unsat-
urated substrates such as olefins,7 ketones,8 and aro-
matic derivatives.9 The electron-deficient dinuclear
complex [(C6Me6)2Ru2(µ2-H)3]+, isolated as the tetrafluo-
roborate salt,10 is soluble in both water and organic
solvents and has turned out to be a versatile starting
material for organometallic synthesis: thus, it has been
used as a precursor for the assembly of trinuclear arene
ruthenium clusters11 and as a building block for conju-
gated organometallic polymers.12 In this paper we report
(i) the synthesis of the phosphido derivatives [(C6Me6)2-
Ru2(µ2-PR2)(µ2-H)2]+ from [(C6Me6)2Ru2(µ2-H)3]+ and
PR2H, (ii) a surprisingly facile P-C bond cleavage
occurring in the trisubstituted phosphines PPh3 and
PMe2Ph and even in the trialkylphosphines P(n-Bu)3
and P(n-Oct)3 by reaction with the dinuclear complex
[(C6Me6)2Ru2(µ2-H)3]+, and (iii) the characterization of
[(C6Me6)2Ru2(µ2-PPh2)(µ2-H)(µ2-Ph)]+, containing a bridg-
ing phenyl ligand, as a possible intermediate in the
reaction of [(C6Me6)2Ru2(µ2-H)3]+ with PPh3.
Figure 1. Molecular structure of 1. Displacement el-
lipsoids are drawn at the 50% probability level. Hydrogen
atoms, except the two hydrido ligands, are omitted for
clarity.
Results and Discussion
Recently we found [(C6Me6)2Ru2(µ2-H)3]+ to react with
thiophenols RSH to give complexes of the type [(C6Me6)2-
Ru2(µ2-SR)2(µ2-H)]+.12 In an effort to extend our reactiv-
ity study of [(C6Me6)2Ru2(µ2-H)3]+ to phosphorus deriva-
tives, we reacted [(C6Me6)2Ru2(µ2-H)3]+ with dialkyl- and
diarylphosphines R2PH. In contrast to the reaction with
RSH, giving thiolato or dithiolato hydrido derivatives,
Scheme 1. Synthesis of
[(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ by P-H Bond
Cleavage in R2PH
(5) (a) Briard, P.; Cabeza, J. A.; Llamazares, A.; Ouahab, L.; Reira,
V. Organometallics 1993, 12, 1006. (b) Cabeza, J. A.; Franco, R. J.;
Llamazares, A.; Reira, V.; Pe´rez-Carreno, E.; Van der Maelen, J. F.
Organometallics 1994, 13, 55. (c) Cabeza, J. A.; del Rio, I.; Reira, V.;
Garcia-Granda, S.; Bamidele Sanni, S. Organometallics 1997, 16, 3914.
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G.; Rheinwald, G.; Stoeckli-Evans, H.; Su¨ss-Fink, G. J. Chem. Soc.,
Dalton Trans. 1994, 3215. (c) Che´rioux, F.; Thomas, C. M.; Therrien,
B.; Su¨ss-Fink, G. Chem. Eur. J. 2002, 8, 4377. (d) Che´rioux, F.;
Therrien, B.; Su¨ss-Fink, G. Chem. Commun. 2004, 204. (e) Pinto, P.;
Marconi, G.; Heinemann, F. W.; Zenneck, U. Organometallics 2004,
23, 374. (f) Stodt, R.; Gencaslan, S.; Muller, I. M.; Shledrick, W. S.
Eur. J. Inorg. Chem. 2003, 1873. (g) Kraemer, R. Angew. Chem., Int.
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325.
(7) (a) Bennett, M. A.; Ennett, J. P. Inorg. Chim. Acta 1992, 198-
200, 583. (b) Daguenet, C.; Scopelliti, R.; Dyson, P. J. Organometallics
2004, 23, 4849. (c) Pertici, P.; Vitulli, G.; Bigelli, C.; Lazzaroni, R. J.
Organomet. Chem. 1984, 275, 113. (d) Bennett, M. A.; Huang, T. N.;
Smith, A. K.; Turney, T. W. J. Chem. Soc., Chem. Commun. 1978, 582.
(8) (a) Brandt, P.; Roth, P.; Andersson P. G. J. Org. Chem. 2004,
69, 4885. (b) Soleimannejad, J.; Sisson, A.; White, C. Inorg. Chim. Acta
2003, 352, 121. (c) Ghebreyessus, K. Y.; Nelson, J. H. J. Organomet.
Chem. 2003, 669, 48. (d) Yamakawa, M.; Yamada, I.; Noyori, R. Angew.
Chem., Int. Ed. 2001, 40, 2818. (e) Noyori, R.; Hashiguchi, S. Acc.
Chem. Res. 1997, 30, 97.
the reaction of R2PH leads only to the monophosphido
dihydrido derivatives [(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ (R
) Ph, 1; R ) t-Bu, 2) (see Scheme 1).
The reaction of [(C6Me6)2Ru2(µ2-H)3]+ with Ph2PH or
with t-Bu2PH, carried out in a dichloromethane solution
at 50 °C (pressurized Schlenk tube), yields the products
1 and 2 quantitatively. Both cations are easily isolated
as the tetrafluoroborate salts, giving air-stable black
crystals.
Black crystals of [1]BF4 suitable for X-ray analysis
were obtained by diffusion of hexane in a dichlo-
romethane solution of the complex. The single-crystal
X-ray structure analysis reveals for the cation 1 a
triangular Ru2P core, each ruthenium atom being
coordinated to a η6-C6Me6 ligand. The molecular struc-
ture of 1 is shown in Figure 1.
The skeleton of [(C6Me6)2Ru2(µ2-PPh2)(µ2-H)2]+ (1)
consists of a triangle constituted of two ruthenium
atoms and one phosphorus atom. Significant bond
lengths and bond angles are listed in Table 1. The Ru-
Ru distance (2.6425(4) Å) is in accordance with a metal-
metal double bond. The presence of two phenyl groups
at the phosphorus atom forces the arene-Ru-Ru-
arene moieties to adopt a distorted geometry. The angle
between the two C6Me6 ligand planes is 34.81°. In the
case of the thiolato and dithiolato complexes [(C6Me6)2-
Ru2(µ2-SR)(µ2-H)2]+ and [(C6Me6)2Ru2(µ2-SR)2(µ2-H)]+ (R
) p-C6H4Br), these angles are 21 and 37°, respectively.12
This comparison shows that the distortion of the arene-
Ru-Ru-arene moiety due to the steric bulk of only one
(9) (a) Su¨ss-Fink, G. In Synthetic Methods of Organometallic and
Inorganic Chemistry; Herrmann, W. A., Ed.; Georg Thieme Verlag:
Stuttgart, Germany, 2001; Vol. 10. (b) Su¨ss-Fink, G.; Faure, M.; Ward,
T. R. Angew. Chem., Int. Ed. 2001, 41, 89. (c) Dyson, P. J.; Ellis, D. J.;
Hemdreson, W.; Laurenczy, G. Adv. Synth. Catal. 2003, 345, 216. (d)
Dyson, P. J.; Ellis, D. J.; Laurenczy, G. Adv. Synth. Catal. 2003, 345,
211.
(10) (a) Bennett, M. A.; Huang, T.-N.; Matheson, T. W.; Smith, A.
K. Inorg. Synth. 1982, 21, 74. (b) Jahncke, M.; Meister, G.; Rheinwald,
G.; Stoeckli-Evans, H.; Su¨ss-Fink, G. Organometallics 1997, 16, 1137.
(c) Bennett, M. A.; Ennett, P. J. Inorg. Chim. Acta 1992, 198-200,
583.
(11) (a) Vieille-Petit, L.; Therrien, B.; Su¨ss-Fink, G. Eur. J. Inorg.
Chem. 2003, 3707. (b) Vieille-Petit, L.; Therrien, B.; Su¨ss-Fink, G.;
Ward, T. J. Organomet. Chem. 2003, 684, 117. (c) Vieille-Petit, L.;
Karmazin-Brelot, L.; Labat, G.; Su¨ss-Fink, G. Eur. J. Inorg. Chem.
2004, 3907.
(12) Tschan, M. J.-L.; Che´rioux, F.; Therrien, B.; Su¨ss-Fink, G. Eur.
J. Inorg. Chem. 2004, 2405.

1976 Organometallics, Vol. 24, No. 8, 2005
Tschan et al.
Table 1. Selected Bond Lengths (Å) and Angles
(deg) in [1][BF4]
Table 2. Selected Bond Lengths (Å) and Angles
(deg) in [2][BF4]
Interatomic Distances
Interatomic Distances
Ru(1)-Ru(2)
Ru(1)-P(1)
Ru(2)-P(1)
Ru(1)-H(1)
Ru(2)-H(1)
2.6425(4)
2.2913(7)
2.2806(8)
1.75(4)
Ru(1)-H(2)
Ru(2)-H(2)
P(1)-C(1)
P(1)-C(7)
1.80(4)
1.77(4)
1.819(3)
1.818(3)
Ru(1)-Ru(1′)a
Ru(1)-P(1)
Ru(1′)-P(1)
Ru(1)-H(1)
Ru(1′)-H(1)
2.6400(8)
2.3210(18)
2.3210(18)
1.60(7)
Ru(1)-H(2)
Ru(1′)-H(2)
P(1)-C(13)
P(1)-C(16)
1.67(7)
1.67(7)
1.901(9)
1.894(9)
1.69(4)
1.60(7)
Bond Angles
Bond Angles
P(1)-Ru(1)-Ru(2) 54.50(2) Ru(1)-H(1)-Ru(2) 100.27
P(1)-Ru(1)-Ru(1′) 55.34(3) Ru(1)-H(1)-Ru(1′) 111.29
P(1)-Ru(1′)-Ru(1) 55.34(3) Ru(1)-H(2)-Ru(1′) 104.02
P(1)-Ru(2)-Ru(1) 54.88(2) Ru(1)-H(2)-Ru(2)
Ru(1)-P(1)-Ru(2) 70.62(2) C(1)-P(1)-C(7)
95.67
106.08(13)
Ru(1)-P(1)-Ru(1′) 69.32(6) C(13)-P(1)-C(16)
110.8(4)
a Symmetry transformations used to generate equivalent at-
oms: (′) x, -y + 1/2, z.
bond angles are listed in Table 2. The Ru-Ru distance
(2.6400(8) Å) is in accordance with a metal-metal
double bond. The presence of two tert-butyl groups on
the phosphorus bridging ligand causes the arene-Ru-
Ru-arene moieties to adopt a distorted geometry. The
angle between the two C6Me6 arene ligands is 50.80°.
This is due to the more important steric hindrance of
the tert-butyl groups with regard to the phenyl groups.
The C(16)-P(1)-Ru(1)-Ru(1′) torsion angle is 111.9(2)°,
and the C(13)-P(1)-Ru(1)-Ru(1′) torsion angle is
-111.0(2)°. The distance between the metal and the C6-
Me6 ring centroid is 1.7296 Å. The Ru-C distances fall
in the range 2.197(7)-2.269(7) Å, with an average Ru-C
distance of 2.24(3) Å.
The ruthenium-hydrogen distances in both cations
1 and 2 are within the range 1.60(7)-1.80(4) Å, which
compares well to the corresponding values (1.57(8) and
1.83(7) Å) in the isoelectronic neutral complex [(C5Me5)2-
Ru2(µ2-η2-C2Ph2)(µ2-H)2].13
Figure 2. Molecular structure of [(C6Me6)2Ru2(µ2-P(t-
Bu)2)(µ2-H)2]+ (2). Displacement ellipsoids are drawn at the
50% probability level. Hydrogen atoms, except the two
hydrido ligands, are omitted for clarity.
To our surprise, [(C6Me6)2Ru2(µ2-PPh2)(µ2-H)2]+ (1) is
equally well accessible from [(C6Me6)2Ru2(µ2-H)3]+ with
triphenylphosphine, implying the cleavage of a phos-
phorus-carbon bond in PPh3. This P-C cleavage is very
facile, since the almost quantitative reaction proceeds
at room temperature in dichloromethane solution. Even
with trialkylphosphines, the P-C bond cleavage occurs
under mild conditions: Thus, [(C6Me6)2Ru2(µ2-H)3]+
reacts with P(n-Bu)3 or with P(n-Oct)3 in refluxing
ethanol to give [(C6Me6)2Ru2(µ2-P(n-Bu)2)(µ2-H)2]+ (3)
and [(C6Me6)2Ru2(µ2-P(n-Oct)2)(µ2-H)2]+ (4) in good yields
(Scheme 2)
µ2-PPh2 ligand is similar to that of two µ2-SR ligands.
This explains why the reaction of [(C6Me6)2Ru2(µ2-H)3]+
with Ph2PH gives only monophosphido derivatives,
while the reaction with RSH leads also to dithiolato
derivatives, the steric hindrance not allowing the for-
mation of diphosphido (just as of trithiolato) derivatives.
The C(1)-P(1)-Ru(1)-Ru(2) torsion angle is 119.03-
(11)°, and the C(7)-P(1)-Ru(1)-Ru(2) torsion angle is
-108.89(12)°. The distances between the metal and the
associated ring centroid are very similar for both
ruthenium atoms (1.7025 Å for Ru(1) and 1.7022 Å for
Ru(2)). The Ru-C distances fall in the range 2.168(4)-
2.257(3) Å, with an average Ru-C distance of 2.22(3) Å
for each ruthenium atom.
Cations 1-4 have all been unambiguously character-
1
ized by their MS and H, 13C, and 31P NMR data, as
well as by satisfactory elemental analysis data of the
tetrafluoroborate salts; in none of the cases has 31P-
13C coupling been observed in the 13C NMR spectra.
These compounds are air-stable and soluble in polar
organic solvents such as methanol, ethanol, dichlo-
romethane, acetone, and acetonitrile. All these com-
Black crystals of [2]BF4 suitable for X-ray analysis
were obtained by slow diffusion of hexane in an acetone
solution of the complex. The asymmetric unit comprises
half a molecule of 2 with a disordered tert-butyl group
1
pounds are brown, except 2, which is violet. H NMR
-
and half a disordered BF4 anion. The single-crystal
spectra of 1-4 show a strong coupling constant (30 Hz)
between hydrido ligands and the phosphorus atom, in
accordance with the value found for [Cp2Fe2(CO)2(µ2-
PPh2)(µ2-H)].5e
X-ray structure analysis reveals for the cation 2 a
triangular Ru2P core, each ruthenium atom being
coordinated to a η6-C6Me6 ligand. The molecular struc-
ture of 2 is shown in Figure 2.
The complex possesses a crystallographically imposed
mirror plane (atoms P(1), H(1), H(2), C(13), C(14),
H(14a), C(16), B(1), and F(1) lie on this plane). The
skeleton of [(C6Me6)2Ru2(µ2-P(t-Bu)2)(µ2-H)2]+ (2) con-
sists of a triangle constituted by two ruthenium atoms
and one phosphorus atom. Significant bond lengths and
The P-C activation process in the trialkylphosphines
requires temperatures (refluxing ethanol) higher than
those for triarylphosphines but can be carried out
without hydrogen pressure. In addition, steric factors
(13) Omori, H.; Suzuki, H.; Kakigano, T.; Moro-Oka, Y. Organome-
tallics 1992, 11, 989.

Reactivity of [(C6Me6)2Ru2(µ2-H)3]+ toward Phosphines
Organometallics, Vol. 24, No. 8, 2005 1977
Scheme 2. Synthesis of
[(C6Me6)2Ru2(µ2-PR2)(µ2-H)2]+ by C-P Bond
Cleavage in PR3
Figure 3. Molecular structure of [(C6Me6)2Ru2(µ2-PPh2)-
(µ2-H)(µ2-Ph)]+ (5). Displacement ellipsoids are drawn at
the 50% probability level. Hydrogen atoms, except the
hydrido ligand, are omitted for clarity.
play an important role for trialkylphosphines: thus, the
reaction works with P(n-Bu)3 but not with the bulky
phosphines P(t-Bu)3 and PCy3. It is interesting to
compare the reaction of trisubstituted phosphines PR3
with [(C6Me6)2Ru2(µ2-H)3]+ to the reaction of PR3 with
the isoelectronic neutral complex [(C5Me5)2Ru2(µ2-H)4],
recently reported by Suzuki et al.,14 which did not result
in a P-C cleavage of the phosphine but in the fluxional
migration of the PR3 from one Ru atom to the other one.
To understand the P-C activation process of trialkyl-
phosphines, we studied the reaction of [(C6Me6)2Ru2(µ2-
H)3]+ with tri-n-octylphosphine, P(n-Oct)3, because the
organic byproducts should be liquid at room tempera-
ture and thus more easily detectable as the correspond-
ing side products of P(n-Bu)3. GC analysis of the reaction
solution reveals that the byproduct of the formation of
4 is the olefin (n-octene) and not the alkane (n-octane),
which means that the P-C activation in trialkylphos-
phines with [(C6Me6)2Ru2(µ2-H)3]+ involves a â-hydrogen
elimination.
To understand the P-C activation process in the
triaryl-substituted phosphines, we studied in detail the
reaction of [(C6Me6)2Ru2(µ2-H)3]+ with PPh3 to give 1.
The elimination of benzene as a reaction product during
this reaction was proven by gas chromatography. It
turned out that we could obtain a yield of 1 and PhH of
greater than 90% by carrying out the reaction under a
pressure of hydrogen (3 bar). Without hydrogen pres-
sure, the yield of 1 drops to 85%, giving also a violet
minor product in low yield, which can be separated from
1 by preparative thin-layer chromatography. This violet
complex, isolated as the tetrafluoroborate salt, turned
out to be the cation [(C6Me6)2Ru2(µ2-PPh2)(µ2-H)(µ2-
Ph)]+ (5).
Table 3. Selected Bond Lengths (Å) and Angles
(deg) in [5][BF4]
Interatomic Distances
Ru(1)-Ru(2)
Ru(1)-P(1)
Ru(2)-P(1)
Ru(1)-H(1)
Ru(2)-H(1)
2.7307(4)
2.2881(13)
2.2917(13)
1.47(6)
Ru(1)-C(37)
Ru(2)-C(37)
P(1)-C(1)
2.264(5)
2.236(5)
1.837(5)
1.819(5)
P(1)-C(7)
1.59(6)
Bond Angles
P(1)-Ru(1)-Ru(2) 53.46(3) Ru(1)-H(1)-Ru(2)
P(1)-Ru(2)-Ru(1) 53.34(3) Ru(1)-C(37)-Ru(2)
Ru(1)-P(1)-Ru(2) 73.20(4) C(1)-P(1)-C(7)
126.35
74.71(14)
101.4(2)
In cation 5, each ruthenium atom is coordinated to a
η6-C6Me6 ligand, a bridging phosphorus atom, and the
bridging ipso carbon atom of a phenyl ligand. The η1-
µ2-C6H5 ring is orthogonal to the Ru-Ru vector. Sig-
nificant bond lengths and bond angles are given in Table
3. The Ru-Ru distance (2.7307(4) Å) is longer than in
complex 1 (2.6425(4) Å) but is in accordance with a
metal-metal double bond. The presence of two phenyl
groups at the bridging phosphorus atom forces the
arene-Ru-Ru-arene moieties to adopt a distorted
geometry. The angle between the nondisordered C6Me6
arene ligand and the disordered C6Me6 arene ligand is
36.00° (for moiety a) and 37.60° (for moiety b). The
C(1)-P(1)-Ru(2)-Ru(1) torsion angle is -109.57(18)°,
and the C(7)-P(1)-Ru(2)-Ru(1) torsion angle is
122.42(19)°. The distances between the metal and the
associated ring centroid are similar for both ruthenium
atoms (1.7319 Å for Ru(1) and moiety a, 1.7360 Å for
Ru(1) and moiety b, and 1.7599 Å for Ru(2)]. The Ru-C
distances fall in the range 2.183(12)-2.339(5) Å for the
C6Me6 arene ligands, with an average Ru-C distance
of 2.25(4) Å. The average Ru-Cipso distance for the
bridging phenyl ligand (2.25(2) Å) is similar to the other
average Ru-C distance. The Ru-Cipso distances are
shorter than in the trinuclear complexes [(CO)6Ru3(µ2-
PPh2)2(µ2-Ph)(µ3-L)] (L ) 2-amino-6-methylpyridinate,
2-mercaptobenzimidazolate, N,N-dimethylurea) con-
taining a bridging η1-µ2-phenyl group, described by
Cabeza et al.5 (2.29(2)-2.35(2) Å), but these complexes
are different inasmuch as the Ru3 skeleton contains only
single Ru-Ru bonds.
Dark purple crystals of [5]BF4 suitable for single-
crystal X-ray structure analysis were obtained by dif-
fusion of hexane in a dichloromethane solution of the
complex. The asymmetric unit comprises a molecule of
the cationic diruthenium complex with a C6Me6 ligand
disordered over two positions (moiety a and moiety b)
-
and a disordered BF4 anion. The molecular structure
of 5 is shown in Figure 3; only one position of the
disordered hexamethylbenzene ring is shown (moiety
a).
(14) Ohki, Y.; Suzuki, H. Angew. Chem., Int. Ed. 2002, 41, 2994.

1978 Organometallics, Vol. 24, No. 8, 2005
Tschan et al.
Figure 4. Reaction of [(C6Me6)2Ru2(µ2-H)3]+ with tri-
phenylphosphine followed by 1H NMR in the hydrido range
recorded in acetone-d6.
Figure 5. Reaction of [(C6Me6)2Ru2(µ2-H)3]+ with tri-
phenylphosphine followed by 1H NMR in the hexamethyl-
benzene range recorded in acetone-d6.
Scheme 3. Mechanistic Hypothesis of the
Reaction of [(C6Me6)2Ru2(µ2-H)3]+ with PPh3 To
Give 1
Scheme 4. Reactivity of [(C6Me6)2Ru2(µ2-H)3]+
toward Mixed Tertiary Phosphines
trace of 5 is detected, if the reaction of [(C6Me6)2Ru2-
(µ2-H)3]+ with PPh3 to give 1 is carried out under a
hydrogen atmosphere (3 bar) at room temperature over
a period of 5 days. These findings strongly support the
hypothesis of the phenyl complex 5 being an intermedi-
ate in the reaction of [(C6Me6)2Ru2(µ2-H)3]+ with PPh3
to give 1.
In the case of mixed alkylarylphosphines, the P-C
bond of the aryl substituent is cleaved preferentially
with respect to the P-C bond of the alkyl substituent:
thus, dimethylphenylphosphine reacts with [(C6Me6)2-
Ru2(µ2-H)3]+ to give the dimethylphosphido derivative
[(C6Me6)2Ru2(µ2-PMe2)(µ2-H)2]+ (6), in line with the
observation of Carty et al., according to which the P-C
bond cleavage in phosphines follows the order P-C(sp)
> P-C(sp2) > P-C(sp3).15 Also in this reaction, the
presence of hydrogen is beneficial for the yield of 6,
isolated as the tetrafloroborate salt (Scheme 4).
If the reaction of [(C6Me6)2Ru2(µ2-H)3]+ with PMe2Ph
is carried out in dichloromethane at 55 °C (pressure
Schlenk tube) without hydrogen being present, a mix-
To address the question of the intermediacy of the
phenyl complex 5 in the formation of 1 from [(C6Me6)2-
Ru2(µ2-H)3]+ with PPh3, we followed the reaction at room
temperature in acetone-d6 by 1H NMR spectroscopy,
which should allow us to decide if 5 and 1 are consecu-
tive or parallel products of the reaction of [(C6Me6)2Ru2-
(µ2-H)3]+ with PPh3 (Scheme 3).
In the beginning, only the hydride signal of the
starting complex [(C6Me6)2Ru2(µ2-H)3]+ at -15.89 ppm
is detected (Figure 4). After 3 h, this singlet has
considerably decreased, while two doublet signals had
appeared at -13.12 and -16.60 ppm, which can be
assigned to the hydrido ligands of [(C6Me6)2Ru2(µ2-
PPh2)(µ2-H)(µ2-Ph)]+ (5) and [(C6Me6)2Ru2(µ2-PPh2)(µ2-
H)2]+ (1), respectively. The signals of the hexamethyl-
benzene ligands show the same trend (Figure 5).
When the integrals of the C6Me6 signals of the three
complexes in the sequence t ) 3 h to t ) 23 h are
compared, it becomes clear that the disappearance of
the starting complex [(C6Me6)2Ru2(µ2-H)3]+ is balanced
by the formation of the two complexes [(C6Me6)2Ru2(µ2-
PPh2)(µ2-H)2]+ (1) and [(C6Me6)2Ru2(µ2-PPh2)(µ2-H)(µ2-
Ph)]+ (5). However, while the hexamethylbenzene signal
of 1 increases steadily with the decrease of the corre-
sponding [(C6Me6)2Ru2(µ2-H)3]+ signal, the hexameth-
ylbenzene signal of 5 stays almost constant.
ture of 6 and the expected intermediary phenyl complex
+
[(C
6Me6)2Ru2(µ2-PMe2)(µ2-H)(µ2-Ph)] (7) is obtained.
The two complexes can be separated by preparative
thin-layer chromatography and characterized by their
1H and 31P NMR as well as MS data. However, only 6
can be isolated in a pure form as the tetrafluoroborate
salt; the isolated product [7][BF4] is always contami-
nated by [6][BF4] (∼20%).
Conclusion
In conclusion, we have studied the reactivity of [(C6-
Me6)2Ru2(µ2-H)3]+ toward di- and trisubstituted phos-
phines. The results are summarized in Scheme 5.
As this result is ambiguous, we checked the reaction
of 5 with hydrogen: indeed, complex 5 is found to react
with H2 (3 bar) in dichloromethane at room temperature
to give quantatively 1 within 4 days. In addition, no
(15) Carty, A. J. Pure Appl. Chem. 1982, 54, 113.

Reactivity of [(C6Me6)2Ru2(µ2-H)3]+ toward Phosphines
Organometallics, Vol. 24, No. 8, 2005 1979
Scheme 5. Reactivity of [(C6Me6)2Ru2(µ2-H)3]+ toward Di- or Trisubstituted Phosphines
to dryness and the brown product obtained was purified by
preparative thin-layer chromatography on silica (eluant acetone/
dichloromethane 1/10). The fraction containing the product
was extracted from the brown band with acetone; evaporation
of the solvent gave the pure brown product (yield 93%, 0.15
mmol, 119 mg).
In the case of tertiary phosphines, facile cleavage of
a phosphorus-carbon bond is observed; even trialkyl-
phosphines undergo this process, so far considered to
be restricted to aromatic phosphines. With PPh3 and
PMe2Ph, the phenyl complexes [(C6Me6)2Ru2(µ2-PR2)-
(µ2-H)(µ2-Ph)]+ (R ) Ph, Me) have been identified as
P-C bond activation intermediates and unambiguously
characterized.
2
1H NMR (CD3COCD3, 400 MHz): δ -15.60 (2H, d, JH,P
)
4
30 Hz, hydride), 2.16 (36H, s, C6(CH3)6), 7.14 (4H, ddd, JH,H
3
3
) 1.7 Hz, JH,H ) 8 Hz, JH,P ) 12.5 Hz; CH of phenyl), 7.40
(6H, m, CH of phenyl). 13C{1H} NMR (CD3COCD3, 100 MHz):
δ 17.25 (Ru-CCH3), 97.22 (Ru-CCH3), 128.19, 128.30, 129.35,
129.38, 133.03, 133.16, 137.64, 137.99 (P-Ph). 31P{1H} NMR
(CD3COCD3, 161 MHz): 98.7 (s). MS (ESI, m/z): 715 [M +
H]+. Anal. Calcd for C36H48BF4PRu2: C, 53.85; H, 6.03.
Found: C, 54.15; H, 6.15.
Experimental Section
All manipulations were carried out under an inert atmo-
sphere of nitrogen using standard Sclenk techniques. All
solvents were degassed with nitrogen prior to use. Silica gel
(type G) used for preparative thin-layer chromatography was
purchased from Macherey Nagel GmbH. All phosphines were
purchased from Fluka, Aldrich, or Strem Chemicals and used
as received. The dinuclear trihydrido complex [(C6Me6)2Ru2-
(µ2-H)3]+ was synthezised by previously described methods.10
Deuterated NMR solvents were purchased from Cambridge
Isotope Laboratories, Inc. NMR spectra were recorded using
a Bruker 400 MHz and a Varian-Gemini 200 MHz spectrom-
eter, and ESI mass spectra were recorded at the University
of Fribourg by Prof. Titus Jenny. Microanalyses were carried
out by the Laboratory of Pharmaceutical Chemistry, Univer-
sity of Geneva.
Synthesis of [(C6Me6)2Ru2(µ2-PPh2)(µ2-H)2][BF4] ([1]-
[BF4]). (a) By Reaction of [(C6Me6)2Ru2(µ2-H)3][BF4] and
HPPh2. [(C6Me6)2Ru2(µ2-H)3][BF4] (100 mg, 0.16 mmol) and
diphenylphosphine (35 mg, 0.19 mmol, 33 µL) were dissolved
in degassed technical grade dichloromethane (25 mL) in a
pressurized Schlenk tube, and the mixture was stirred for 16
h at 50 °C. Then the solvent was evaporated to dryness and
the brown product obtained was purified by preparative thin-
layer chromatography on silica (eluant acetone/dichloromethane
1/10). The fraction containing the product was extracted from
the brown band with acetone; evaporation of the solvent gave
the pure product in quantitative yield.
Synthesis of [(C6Me6)2Ru2(µ2-P(t-Bu)2)(µ2-H)2][BF4] ([2]-
[BF4]). [(C6Me6)2Ru2(µ2-H)3][BF4] (100 mg, 0.16 mmol) and di-
tert-butylphosphine (28.5 mg, 0.19 mmol, 36 µL) were dissolved
in degassed technical grade dichloromethane (25 mL) in a
pressurized Schlenk tube, and the mixture was stirred for 16
h at 50 °C. Then the solvent was evaporated to dryness and
the violet product obtained was purified by preparative thin-
layer chromatography on silica (eluant acetone/dichloromethane
1/10). The fraction containing the product was extracted from
the violet band with acetone; evaporation of the solvent gave
the pure violet product in quantitative yield (100%, 0.16 mmol,
1
122 mg). H NMR (CD3COCD3, 400 MHz): δ -17.13 (2H, d,
3
2JH,P ) 30 Hz, hydride), 1.02 (18H, d, JH,P ) 14 Hz, CH3 of
t-Bu), 2.36 (36H, s, C6(CH3)6). 13C{1H} NMR (CD3COCD3, 100
MHz): δ 18.07 (Ru-CCH3), 33.43 (C(CH3) of t-Bu), 33.49
(C(CH3) of t-Bu), 38.04 (C(CH3) of t-Bu), 38.10 (C(CH3) of t-Bu),
96.51 (Ru-CCH3). 31P{1H} NMR (CD3COCD3, 161 MHz): δ
180.80 (t, 2JH,P ) 30 Hz). MS (ESI, m/z): 674 [M + H]+. Anal.
Calcd for C32H56BF4PRu2: C, 50.52; H, 7.42. Found: C, 50.70;
H, 7.47.
Synthesis of [(C6Me6)2Ru2(µ2-P(n-Bu)2)(µ2-H)2][BF4] ([3]-
[BF4]). [(C6Me6)2Ru2(µ2-H)3][BF4] (100 mg, 0.16 mmol) and tri-
n-butylphosphine (64 mg, 0.32 mmol, 80 µL) were dissolved
in degassed purissimum ethanol (100 mL) and heated under
reflux for 18 h. Then the solvent was evaporated to dryness
and the brown mixture obtained was purified by preparative
thin-layer chromatography on silica (eluant acetone/dichlo-
romethane 1/10). The fraction containing the product was
extracted from the main brown band with acetone; evaporation
of the solvent gave the pure brown product (yield 53%, 0.08
(b) By Reaction of [(C6Me6)2Ru2(µ2-H)3][BF4] and PPh3.
[(C6Me6)2Ru2(µ2-H)3][BF4] (100 mg, 0.16 mmol) and triphen-
ylphosphine (93 mg, 0.32 mmol) were dissolved in technical
grade dichloromethane (25 mL) degassed with hydrogen, and
the mixture was stirred for 2 days at room temperature under
3 bar of hydrogen by using a pressurized Schlenk tube (the
disappearance of the green starting compound [H3Ru2(C6Me6)2]-
[BF4] was monitored by TLC). Then the solvent was evaporated
1
mmol, 64 mg). H NMR (CD2Cl2, 400 MHz): δ -16.48 (2H, d,

1980 Organometallics, Vol. 24, No. 8, 2005
Table 4. Crystallographic Data for the Structures of Complexes [1][BF4], [2][BF4], and [5][BF4]
[1][BF4] [2][BF4] [5][BF4]
36H48BF4PRu2 32H56BF4PRu2 42H52BF4PRu2
Tschan et al.
chem formula
formula wt
cryst color and shape
cryst size
cryst syst
space group
a (Å)
C
C
C
800.66
760.69
876.76
black block
black block
dark purple block
0.30 × 0.30 × 0.30
0.30 × 0.10 × 0.10
0.30 × 0.20 × 0.10
monoclinic
orthorhombic
monoclinic
P21/c
Pnma
P21/n
10.3464(9)
22.5729(13)
11.2717(7)
b (Å)
18.4596(12)
16.3209(8)
17.0632(14)
c (Å)
18.1656(14)
8.7729(6)
19.4068(12)
â (deg)
96.111(10)
90
92.226(7)
V (Å3)
3449.7(5)
3232.0(3)
3729.7(4)
Z
4
4
4
Dcalcd (g cm-3
)
1.542
1.563
1.561
µ(Mo KR) (mm-1
temp (K)
F(000)
scan range (deg)
)
0.968
1.028
0.903
153(2)
153(2)
153(2)
1632
1568
1792
2.28 < θ < 25.90
2.28 < θ < 25.90
2.28 < θ < 25.90
cell refinement params rflns
no. of rflns measd
no. of indep rflns
no. of rflns obsd (I > 2σ(I))
Rint
8000
7347
8000
25 771
24 403
29 114
6476
3264
6886
5277
1394
4647
0.0306
0.1421
0.0927
final R indices (I > 2σ(I))
R indices (all data)
R1 ) 0.0293, wR2a ) 0.0748
R1 ) 0.0383, wR2a ) 0.0774
1.019
R1 ) 0.0389, wR2a ) 0.0814
R1 ) 0.1093, wR2a ) 0.0925
0.749
R1 ) 0.0431, wR2a ) 0.0973
R1 ) 0.0722, wR2a ) 0.1057
0.900
goodness of fit
residual density: max, min ∆F (e Å-3
)
1.554, -0.849
1.282, -1.282
1.022, -1.343
2
2
a The structure was refined on Fo2: wR2 ) [∑[w(Fo - Fc )2]/∑w(Fo2)2]1/2, where w-1 ) [∑(Fo2) + (aP)2 + bP] and P ) [max(Fo2, 0) +
2
2Fc ]/3.
3
2JH,P ) 30 Hz, hydride), 0.89 (6H, t, JH,H ) 13 Hz, CH2CH3),
acetone/dichloromethane 1/10). A violet fraction could be
observed, above the brown one ([1][BF4]) on the preparative
thin-layer chromatography plate, which was extracted from
silica with acetone. The evaporation of the solvent gave the
impure product [5][BF4], contaminated by [1][BF4] (∼40%). The
product [5][BF4] crystallizes from slow diffusion of hexane in
a dichloromethane solution of the mixture of [5][BF4] and [1]-
[BF4]. 1H NMR (CD3COCD3, 200 MHz): δ -13.12 (1H, d, 2JH,P
) 30 Hz, hydride), 1.92 (36H, s, C6(CH3)6), 6.40-8.0 (14H, m,
CH of phenyl), 8.60 (1H, d, 3JH,H ) 7.6 Hz, CH of phenyl). 31P-
{1H} NMR (CD3COCD3, 80 MHz): δ 117 (s). MS (ESI, m/z):
791 [M + H]+.
0.95 (4H, hept, 3JH,H ) 13 Hz, CH2CH2CH3), 1,31 (4H, q, 3JH,H
2
3
) 13 Hz, CH2CH2CH2), 1.87 (4H, td, JH,P ) 4.4 Hz, JH,H
)
13 Hz, P-CH2CH2), 2.26 (36H, s, C6(CH3)6). 13C{1H} NMR
(CDCl3, 100 MHz): δ 14.36 (CH3), 18.42 (Ru-CCH3), 24.09
(CH2), 24.26 (CH2), 28.97 (CH2), 29.15 (CH2), 30.47 (P-CH2),
96.61 (Ru-CCH3). 31P{1H} NMR (CDCl3, 161 MHz): δ 115.91
(t, JH,P ) 30 Hz). MS (ESI, m/z): 674 [M + H]+. Anal. Calcd
2
for C32H56BF4PRu2: C, 50.52; H, 7.42. Found: C, 50.71; H,
7.49.
Synthesis of [(C6Me6)2Ru2(µ2-P(n-Oct)2)(µ2-H)2][BF4]
([4][BF4]). [(C6Me6)2Ru2(µ2-H)3][BF4] (200 mg, 0.32 mmol) and
tri-n-octylphosphine (240 mg, 0.65 mmol, 288 µL) were dis-
solved in degassed purissimum ethanol (100 mL) and heated
under reflux for 18 h. Then the solvent was evaporated to
dryness and the brown mixture obtained was purified by
preparative thin-layer chromatography on silica (eluant acetone/
dichloromethane 1/10). The fraction containing the product
was extracted from the main brown band with acetone;
evaporation of the solvent gave the pure brown product (yield
45%, 0.14 mmol, 125 mg). 1H NMR (CD3COCD3, 400 MHz): δ
Synthesis of [(C6Me6)2Ru2(µ2-PMe2)(µ2-H)2][BF4] ([6]-
[BF4]). [(C6Me6)2Ru2(µ2-H)3][BF4] (100 mg, 0.16 mmol) and
dimethylphenylphosphine (33 mg, 0.24 mmol, 36 µL) were
dissolved in technical grade dichloromethane (100 mL) de-
gassed with hydrogen and heated to 55 °C for 16 h under 3
atm of hydrogen by using a pressurized Schlenk tube. Then
the solvent was evaporated to dryness and the brown mixture
obtained was purified by preparative thin-layer chromatog-
raphy on silica (eluant acetone/dichloromethane 1/10). The
fraction containing the product was extracted from the brown
band with acetone; evaporation of the solvent gave the pure
brown product (yield 27%, 4.3 mmol, 29 mg).
2
3
-16.34 (2H, d, JH,P ) 30 Hz, hydride), 0.88 (6H, t, JH,H ) 7
Hz, CH2CH3), 1.25-1.37 (24H, broad, CH2CH2CH2CH2CH2CH2-
CH2CH3), 2.02 (4H, m, P-CH2), 2.33 (36H, s, C6(CH3)6). 13C-
{1H} NMR (CD2Cl2, 100 MHz): δ 14.25 (CH3), 18.22 (Ru-
CCH3), 23.04 (CH3CH2), 28.37 (CH2), 28.40 (CH2), 29.18 (CH2),
29.35 (CH2), 29.48 (CH2), 29.59 (CH2), 29.87 (CH2), 30.08 (CH2),
31.02 (CH2), 31.19 (CH2), 32.16 (P-CH2), 32.21 (P-CH2), 96.59
(Ru-CCH3). 31P{1H} NMR (CD3COCD3, 161 MHz): δ 118.05
2
1H NMR (CD2Cl2, 400 MHz): δ -16.19 (2H, d, JH,P ) 32
2
Hz, hydride), 1.42 (6H, d, JH,P ) 13 Hz, P-CH3), 2.28 (36H,
s, C6(CH3)6). 13C{1H} NMR (CD2Cl2, 100 MHz): δ 18.14 (Ru-
CCH3), 30.07 (P-CH3), 96.82 (Ru-CCH3). 31P{1H} NMR (CD2-
Cl2, 161 MHz): δ 67.90 (t, 2JH,P ) 32 Hz). MS (ESI, m/z): 590
[M + H]+. Anal. Calcd for C27.5H45BF4O0.5PRu2 ([6][BF4]‚1/2-
CH3COCH3): C, 46.95; H, 6.45. Found: C, 46.94; H, 6.31.
Isolation and Characterization of [(C6Me6)2Ru2(µ2-
PMe2)(µ2-H)(µ2-Ph)][BF4] ([7][BF4]). [(C6Me6)2Ru2(µ2-H)3]-
[BF4] (100 mg, 0.16 mmol) and dimethylphenylphosphine (33
mg, 0.24 mmol, 36 µL) were dissolved in technical grade
dichloromethane (100 mL) degassed with nitrogen (instead of
hydrogen) and heated under reflux for 20 h. Then the solvent
was evaporated to dryness and the brown mixture obtained
was purified by preparative thin-layer chromatography on
silica (eluant acetone/dichloromethane 1/10). A violet fraction
could be observed, above the brown one ([1][BF4]) on the
preparative thin-layer chromatography plate, which was ex-
(t, JH,P ) 30 Hz). MS (ESI, m/z): 786 [M + H]+. Anal. Calcd
for C40H72BF4PRu2: C, 57.06; H, 8.62. Found: C, 57.07; H,
8.89.
2
Isolation and Characterization of [(C6Me6)2Ru2(µ2-
PPh2)(µ2-H)(µ2-Ph)][BF4] ([5][BF4]). [(C6Me6)2Ru2(µ2-H)3]-
[BF4] (100 mg, 0.16 mmol) and triphenylphosphine (93 mg,
0.32 mmol) were dissolved in technical grade dichloromethane
(25 mL) degassed with nitrogen (instead of hydrogen), and the
mixture was stirred for 2 days at room temperature (the
disappearance of the green starting compound [H3Ru2(C6Me6)2]-
[BF4]) was monitored by TLC). Then the solvent was evapo-
rated to dryness and the brown mixture obtained was purified
by preparative thin-layer chromatography on silica (eluant

Reactivity of [(C6Me6)2Ru2(µ2-H)3]+ toward Phosphines
Organometallics, Vol. 24, No. 8, 2005 1981
tracted from silica with acetone. The evaporation of the solvent
gave the impure product [7][BF4], contaminated by [6][BF4]
(∼20%). 1H NMR (CD3COCD3, 400 MHz): δ -16.79 to -16.69
(1H, m, hydride), 1.56 (6H, d, 2JH,P ) 10 Hz, CH3 of P(CH3)2),
2.176 (12H, s, C6(CH3)6), 2.117 (12H, s, C6(CH3)6), 2.19 (12H,
s, C6(CH3)6), 7.19-7.24 (2H, m. CH of phenyl), 7.41-7.44 (3H,
m, CH of phenyl), 31P{1H} NMR (CD3COCD3, 161 MHz): δ 31
semiempirical absorption correction was applied using MU-
LABS (PLATON03):17 Tmin ) 0.7474, Tmax ) 0.8297. In the
-
structure of [5][BF4], the BF4 counteranion and one hexa-
methylbenzene ring are disordered over two positions; a
semiempirical absorption correction was applied using MU-
LABS (PLATON03):18 Tmin ) 0.66327, Tmax ) 0.86390.
Crystallographic details are given in Table 4, and significant
bond lengths and bond angles are listed in Table 1 for [1][BF4],
Table 2 for [2][BF4], and Table 3 for [5][BF4]. The figures were
drawn with ORTEP.19
2
(t, JH,P ) 24 Hz). MS (ESI, m/z): 666 [M + H]+.
X-ray Crystallographic Study. Data were collected using
a Stoe imaging plate diffractometer system (Stoe & Cie, 1995)
equipped with a one-circle æ goniometer and a graphite
monochromator (Mo-KR radiation, λ ) 0.710 73 Å). Totals of
192 exposures for [1][BF4] and 200 exposures for [2][BF4] and
[5][BF4] (3 min per exposure) were obtained at an image plate
distance of 70 mm with 0 < æ < 192° for [1][BF4] and 0 < æ <
200° for [2][BF4] and [5][BF4], and with the crystal oscillating
through 1° in æ. The resolution was Dmin - Dmax ) 12.45-
0.81 Å.
Acknowledgment. Financial support of the Fond
National Suisse de la Recherche Scientifique is grate-
fully acknowledged (Grant No. 200020-105’132). We
thank the Johnson Matthey Technology Centre for a
generous loan of ruthenium trichloride hydrate and
Professor H. Stoeckli-Evans (Universite´ de Neuchaˆtel,
Neuchaˆtel, Switzerland) for helpful discussions.
The structures were solved by direct methods using the
program SHELXS-9716 and refined by full-matrix least squares
on F2 with SHELXL-97.16 The hydrido ligands were located
from Fourier difference maps, and during the least-squares
refinement they were held fixed with Uiso(H) ) 0.05 Å2; the
remaining hydrogen atoms were included in calculated posi-
tions and treated as riding atoms using SHELXL-97 default
parameters. All non-hydrogen atoms were refined anisotropi-
cally. In the structure of [2][BF4], one tert-butyl group and the
Supporting Information Available: Complete tables of
crystal and structure refinement data, atomic coordinates,
bond lengths and angles, anisotropic displacement parameters,
and hydrogen coordinates for compounds 1, 2, and 5 as CIF
files. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM049025N
(17) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(18) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.
-
BF4 counteranion are disordered over two positions, and a
(16) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(19) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.