Reactivity of dinuclear arene ruthenium complexes: Reactions of the hydrido complex [(p-Me-C6H4-Pri)2Ru 2Cl2(μ-Cl)(μ-H)] with NaX and HX (X=F, Cl, Br, I)

Article abstract of DOI:10.1016/S0022-328X(00)00155-8

The dinuclear hydrido complex [(p-Me-C₆H₄-Prⁱ)₂Ru ₂Cl₂(μ-Cl)(μ-H)] (1) reacts with the sodium halides NaX in methanol to give the halogen analogues [(p-Me-C₆H₄-Prⁱ)₂Ru ₂X₂(μ-X)(μ-H)] (2: X=F, 3: X=Br, 4: X=I). With HX, complex 1 reacts to give the tetrahalo complexes [(p-Me-C₆H₄-Prⁱ)₂Ru ₂X₂(μ-X)₂] (5: X=Cl, 6: X=Br, 7: X=I); in the case of X=I, a large excess of HI leads to the formation of the cationic complex [(p-Me-C₆H₄-Prⁱ)₂Ru ₂(μ-I)₃]⁺ (8). The X-ray structure analysis of 1 shows a dinuclear Ru₂ backbone with two terminal chloro ligands being trans with respect to each other as the two p-cymene ligands, the two bridging ligands lie in a plane perpendicular to the plane defined by the terminal chloro ligands and the ruthenium atoms.

Full text of DOI:10.1016/S0022-328X(00)00155-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 602 (2000) 188–192
Reactivity of dinuclear arene ruthenium complexes: reactions of
the hydrido complex [(p-Me-C6H4-Pri)2Ru2Cl2(m-Cl)(m-H)] with
NaX and HX (X=F, Cl, Br, I)
Georg Su¨ss-Fink *, Eva Garcia Fidalgo, Antonia Neels, Helen Stoeckli-Evans
Institut de Chimie, Uni6ersite´ de Neuchaˆtel, A6enue de Belle6aux 51, CH-2000 Neuenberg, Switzerland
Received 7 January 2000; accepted 29 February 2000
Abstract
The dinuclear hydrido complex [(p-Me-C6H4-Pri)2Ru2Cl2(m-Cl)(m-H)] (1) reacts with the sodium halides NaX in methanol to
give the halogen analogues [(p-Me-C6H4-Pri)2Ru2X2(m-X)(m-H)] (2: X=F, 3: X=Br, 4: X=I). With HX, complex 1 reacts to give
the tetrahalo complexes [(p-Me-C6H4-Pri)2Ru2X2(m-X)2] (5: X=Cl, 6: X=Br, 7: X=I); in the case of X=I, a large excess of HI
leads to the formation of the cationic complex [(p-Me-C6H4-Pri)2Ru2(m-I)3]+ (8). The X-ray structure analysis of 1 shows a
dinuclear Ru2 backbone with two terminal chloro ligands being trans with respect to each other as the two p-cymene ligands, the
two bridging ligands lie in a plane perpendicular to the plane defined by the terminal chloro ligands and the ruthenium atoms.
© 2000 Elsevier Science S.A. All rights reserved.
Keywords: Rutherium complexes; Hydrido complexes; Arene complexes
We therefore decided to study systematically the
reactivity of complex 1 towards NaX and HX in order
1. Introduction
to complete the series of hydrido complexes [(p-Me-
Arene ruthenium complexes have received much at-
tention over the past 25 years because of their unique
structures and properties and also due to their inherent
C6H4-Pri)2Ru2X2(m-Cl)(m-H)] (X=F, Cl, Br, I) and also
the series of the tetrahalo complexes [(p-Me-C6H4-
Pri)2Ru2X2(m-X)2] (X=Cl, Br, I). The single-crystal
catalytic potential [1]. Some of these complexes are
structure analysis of the starting complex 1 is also
reactive towards molecular hydrogen or hydrogen
reported.
transferring agents, consequently a considerable num-
ber of arene ruthenium complexes containing hydride
ligands have been synthesised [2–6].
2. Experimental
The dinuclear p-cymene hydrido complex [(p-Me-
C6H4-Pri)2Ru2Cl2(m-Cl)(m-H)] (1) was first obtained by
2.1. General
Bennett et al. from the reaction of [(p-Me-C6H4-
Pri)2Ru2Cl2(m-Cl)2] with molecular hydrogen, along
The following chemicals were purchased from com-
mercial sources and used without further purification:
RuCl3·nH2O (Johnson Matthey), (R)-(−)-5-isopropyl-
with the benzene, mesitylene, hexamethylbenzene and
1,2,4,5-tetramethylbenzene derivatives [7]. All these
compounds are well characterised, but there is no struc-
2-methyl-1,3-cyclohexadiene (Merck), KB[CH(CH3)-
tural information about these hydrido complexes; fur-
C2H5]3H (Aldrich), MgSO4, NaI (Fluka), NaBr
thermore, the other halogen analogues are not known.
(Fluka), HF 47% (Fluka), HCl 48% (Fluka), HBr 37%
(Fluka) and HI 47% (Fluka). All reactions and mani-
pulations were carried out under nitrogen using
standard Schlenck techniques. The organic solvents
were dried over appropriate drying agents, distilled and
* Corresponding author. Tel.: +41-32-7182400; fax: +41-32-
7182511.
E-mail address: georg.suess-fink@ich.unine.ch (G. Su¨ss-Fink)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 0 ) 0 0 1 5 5 - 8

G. Su¨ss-Fink et al. / Journal of Organometallic Chemistry 602 (2000) 188–192
189
2.3. Preparation of
stored under nitrogen prior to use. The complex
[(p-Me-C6H4-Pri)RuCl2(m-Cl)(m-H)]2 (1) was synthe-
sized according to published methods [7]. For the
preparative thin-layer chromatography, 20×20 cm
plates coated with silica gel (0.6–0.8 mm) without
UV-indicator (Fluka Silica Gel G.) were used. The
NMR spectra were recorded on a Varian Gemini 200
BB instrument using a Sun Varian Station for the
treatment of the spectra. The mass spectra (FAB) were
recorded by Professor Titus A. Jenny, University of
Fribourg, using a VG7070E spectrometer. Microanalyt-
ical data were obtained from the Mikroelementarana-
lytisches Laboratorium der ETH Zu¨rich, Switzerland.
[(p-Me-C6H4-Pri)2Ru2Br2(v-Br)(v-H)] (3)
A solution of NaBr (178.05 mg, 1.73 mmol) in 5 ml
of methanol was added dropwise to a solution of 1 (100
mg, 0.173 mmol) in 30 ml of methanol. The mixture
was stirred for 24 h at 25°C. After removal of the
solvent, the red residue was dissolved in 20 ml of
dichloromethane and the solution was filtered to re-
move the excess NaBr. The filtrate was concentrated
and the residue was submitted to thin-layer chromatog-
raphy using a 8:1 mixture of cyclohexane and iso-
propanol as eluent. The dark red main band containing
3 was extracted with acetone, followed by evaporation
to dryness to give the product as a dark red powder
(196 mg, 63% yield). MS: m/z 713.8. Found: C, 34.88;
H, 4.26. Calc. for C20H29Ru2Br3·C3H6O: C, 34.86; H,
4.62%.
2.2. Preparation of
[(p-Me-C6H4-Pri)2Ru2F2(v-F)(v-H)] (2)
A solution of NaF (655.2 mg, 15.6 mmol) in 8 ml of
methanol was added dropwise to a solution of 1 (900
mg, 1.56 mmol) in 30 ml of methanol. The mixture was
stirred for 48 h at 25°C. After removal of the solvent in
vacuo, the orange–red residue was dissolved in 20 ml
of dichloromethane and the solution was filtered to
remove the excess NaF. The filtrate was concentrated
to 5 ml and submitted to thin-layer chromatography
using a 4:1:2 mixture of cyclohexane, chloroform and
acetone as eluent. After separation of the two bands
(orange and red), the plates were dried (1 min) and
reintroduced into the same eluent mixture. When the
red band (starting material) had separated completely
from the orange band, the product was extracted from
the main orange band with acetone. Evaporation to
dryness gave 2 as an orange–red powder (160.9 mg,
19% yield). MS: m/z 528.4. Found: C, 45.36; H, 5.31.
Calc. for C20H29Ru2F3: C, 45.42; H, 5.49%.
2.4. Preparation of
[p-Me-C6H4-Pri)2Ru2Br2(v-Br)(v-H)] (4)
A solution of NaBr (178.5 mg, 1.73 mmol) in 5 ml of
methanol was added dropwise to a solution of 1 (110
mg, 0.190 mmol) in 30 ml of methanol. The mixture
was stirred for 24 h at 25°C. After removal of the
solvent, the red residue was dissolved in the minimum
quantity of methanol. The product was separated by
thin-layer chromatography using a 8:1 mixture of cyclo-
hexane and isopropanol as eluent. The violet main
band containing 4 was extracted with acetone, followed
by evaporation to dryness to give the product as a
violet powder (190 mg, 85% yield). MS: m/z 853.61.
Found: C, 31.04; H, 3.85. Calc. for C20H29Ru2I3·C3-
H6O: C, 31.08; H, 4.04%.
2.5. Preparation of [(p-Me-C6H4-Pri)2RuX2(v-X)2]
(5: X=Cl, 6: X=Br, 7: X=I)
To a solution of compound 1 (150 mg, 0.259 mmol)
in 25 ml of THF, 0.692 mmol of concentrated HX
(37%, X=Cl; 48%, X=Br; 47%, X=I) was added.
The mixture was refluxed for 5 h and then the solution
was filtered and evaporated to dryness. The residue was
washed with 5 ml of H2O and then taken up in
dichloromethane (20 ml). After drying with MgSO4, the
solution was filtered and evaporated to dryness, which
gave the analytically pure product (yield: 5, 186.48 mg,
85%; 6, 240.76 mg, 79%; 7, 342.35 mg, 74%), identified
by the NMR data [8,9].
Scheme 1.
2.6. Preparation of [(p-Me-C6H4-Pri)2Ru2(v-I)3]I
(cation 8)
An excess of HI (0.275 ml, 2.48 mmol) was added to
a solution of compound 1 (120 mg, 0.207 mmol) in 35
Scheme 2.

190
G. Su¨ss-Fink et al. / Journal of Organometallic Chemistry 602 (2000) 188–192
Cie, 1995), equipped with a one-circle € goniometer
and a graphite-monochromator. Data collection was
performed at −50°C using Mo–Ka radiation (u=
,
0.71073 A). In total 170 exposures (3 min per exposure)
were obtained at an image plate distance of 70 mm with
0B€B170° and with the crystal oscillating through 1°
Scheme 3.
,
in €. The resolution was Dmin−Dmax 12.45–0.81 A.
Table 1
The structure was solved by direct methods using the
program SHELXS-97 [12], and refined by full-matrix
least-squares on F2 [13] with SHELXL-97 [13]. The posi-
tions of the hydride was derived from Fourier differ-
ence maps and refined, while the remaining hydrogen
atoms of the organic ligand were included in calculated
positions and treated as riding atoms using SHELXL-97
default parameters. Crystallographic details are given in
Table 1.
Crystallographic data of compound 1
Empirical formula
M (g mol−1
C20H29Cl3Ru2
577.92
)
Temperature (K)
Crystal system
Space group
223(2)
Orthorhombic
Pbca
,
a (A)
13.7542(18)
16.0142(18)
19.352(2)
4267.7(9)
,
b (A)
,
c (A)
U (A )
3
,
Z
8
Dcalc (g cm−3
F(000)
)
1.801
2304
3. Results and discussion
q limits (°)
hkl ranges
2.10–25.96
−16 to 16, −19 to 19, −23 to 23
The hydrido trichloro complex [(p-Me-C6H4-
Pri)2Ru2Cl2(m-Cl)(m-H)] (1) reacts in methanol with
sodium halides to give, by simple halide exchange, the
corresponding hydrido trihalo derivatives [(p-Me-C6H4-
Pri)2Ru2X2(m-X)(m-H)] (2: X=F, 3: X=Br, 4: X=I),
unknown hitherto (Scheme 1). All these complexes are
air-stable, crystalline solids which are intensely
coloured (2: orange, 3: red, 4: violet) and readily solu-
ble in polar organic solvents and in aromatic
hydrocarbons.
Reflections collected
Independent reflections
Reflections observed
[I=2|(I)]
27768
4123
3390
Goodness-of-fit on F2 a
0.976
Final R indices [I=2|(I)] b R1=0.0284, wR2=0.0526
R indices (all data)
R1=0.0365, wR2=0.0555
a S=[Sw(Fo2−F2c)2/(n−p)]1/2 (n, number of reflections; p, number
of parameters).
b R1=ꢀꢁFoꢂ−ꢂFcꢁ/SꢂFoꢂ. wR2=[Sw(F2o−Fc2)2/Sw(Fo)4]1/2
.
The new hydrido complexes were characterised by
1
their H-NMR data: apart from the typical signals of
ml of THF. The mixture was refluxed for about 6 h and
then filtered. The solvent was removed in vacuo, and
the residue was dissolved in benzene. Crystallization at
room temperature gave crystals of [(p-Me-C6H4-
Pri)2Ru2(m-I)3][In] in 63% yield. The product was iden-
tified by the IR and NMR data [11].
the two equivalent p-cymene ligands, there is a singlet
in the range of bridging hydrido ligands (Table 2). In
the mass spectra (electrospray), all complexes 2–4 show
the molecular peak with the expected isotope pattern.
The halide exchange reaction of [(p-Me-C6H4-
Pri)2Ru2Cl2(m-Cl)(m-H)] (1) can also involve the hydrido
ligand: if, instead of the sodium halide, the correspond-
ing acid HX is used, the known [8–10] tetrahalo com-
plexes [(p-Me-C6H4-Pri)2Ru2X2(m-X)2] (5: X=Cl, 6:
X=Br, 7: X=I) are obtained (Scheme 2). The reaction
takes place in refluxing THF (Scheme 3).
2.7. X-ray crystallography
An orange crystal of compound 1 was mounted on a
Stoe Imaging Plate Diffractometer System (Stoe and
Table 2
NMR data of compounds 2–4
Complex
l (1H) a
l (19F) a
[(p-Me-C6H4-Pri)2Ru2F2(m-H)(m-F)] (2)
[(p-Me-C6H4-Pri)2Ru2Br2(m-H)(m-Br)] (3)
[(p-Me-C6H4-Pri)2Ru2I2(m-H)(m-I)] (4)
1.47, 1.44 (d, 6H, CH(CH3)2), 2.20 (s, 3H, C6H4CH3), 3.01(sp, 1H, CH(CH3)2) −127.3, −151.7
5.67, 5.54 (d, 2H, C6H4), 5.46, 5.39 (d, 2H, C6H4), −9.97 (s, 1H, Ru2H)
1.42, 1.46 (d, 6H, CH(CH3)2), 2.39 (s, 3H, C6H4CH3), 3.04 (sp, 1H, CH(CH3)2)
5.00, 5.38 (d, 2H, C6H4), 5.59, 5.69 (d, 2H, C6H4), −11.02 (s, 1H, Ru2H)
1.08, 1.14 (d, 6H, CH(CH3)2), 1.99 (s, 3H, C6H4CH3), 2.81 (sp, 1H, CH(CH3)2)
4.98, 5.15 (d, 2H, C6H4), 5.25, 5.42 (d, 2H, C6H4), −13.16 (s, 1H, Ru2H) b
a Measured in CDCl3.
b Measured in C6D6.

G. Su¨ss-Fink et al. / Journal of Organometallic Chemistry 602 (2000) 188–192
191
Table 3
NMR data of complexes 5–8
Complex l
l (1H) a
1.28 (d, 6H, CH(CH3)2), 2.16 (s, 3H, C6H4CH3), 2.92 (sp, 1H, CH(CH3)2)
5.33 (d, 2H, C6H4), 5.47 (d, 2H, C6H4)
1.29 (d, 6H, CH(CH3)2), 2.23 (s, 3H, C6H4CH3), 2.98 (sp, 1H, CH(CH3)2)
5.40 (d, 2H, C6H4), 5.52 (d, 2H, C6H4)
1.25 (d, 6H, CH(CH3)2), 2.36 (s, 3H, C6H4CH3), 2.98 (sp, 1H, CH(CH3)2)
5.43 (d, 2H, C6H4), 5.48 (d, 2H, C6H4)
1.30 (d, 6H, CH(CH3)2), 2.34 (s, 3H, C6H4CH3), 2.90 (sp, 1H, CH(CH3)2)
5.56 (d, 2H, C6H4), 5.66 (d, 2H, C6H4)
[(p-Me-C6H4-Pri)RuCl(m-Cl]2 (5)
[(p-Me-C6H4-Pri)RuBr(m-Br]2 (6)
[(p-Me-C6H4-Pri)RuI(m-I)]2 (7)
[(p-MeC6H4-Pri)2Ru2(m-I)3]+ (8)
a Measured in CDCl3.
,
,
In the case of HI, the reaction with 1 is sensitive to
stoichiometry: while a 1:4 ratio leads to the tetraiodo
complex 7, an excess of HI (1:10) gives rise to the
formation of the known [11] cation [(p-Me-C6H4-
Pri)2Ru2(m-I)3]+ (8), which crystallizes as the polyiodide
salt (Table 3).
distances [RhꢀRh 2.906(1) A, IrꢀIr 2.903(1) A] are also
in the range of bonding interactions. By contrast, in the
tetrahalo complexes 5 and 6, the RuꢀRu distances
,
[3.853(1) and 4.092(1) A, respectively] [10] are too long
for bonding interactions, in accordance with the elec-
tron count of 36e.
The molecular structure of the hydrido trichloro
complex 1 was solved by a single-crystal X-ray struc-
ture analysis using a suitable crystal grown in benzene
(Fig. 1). Interatomic distances and angles are given in
The angle Ru1ꢀCl1ꢀRu2 is found to be 75.616(19)°
and compares well with the corresponding angles of
72.65(8) and 73.20(6)° in [(C5Me5)2Rh2Cl2(m-Cl)(m-H)]
[14] and [(C5Me5)2Ir2Cl2(m-Cl)(m-H)] [15], which is in
line with a description of the bonding situation in terms
of a closed RuHRu three-center two-electron interac-
tion in which there is substantial metalꢀmetal bonding.
The angles Cl2ꢀRu1ꢀRu2 [88.98(2)°] and Cl3ꢀRu2ꢀRu1
[87.48(2)°] are almost right angles, the torsion angle
,
Table 4. The RuꢀRu distance of 2.9573(4) A is in
accordance with a metalꢀmetal bond, as expected from
the electron count (34e). In the isoelectronic hydrido
trichloro complexes [(C5Me5)2Rh2Cl2(m-Cl)(m-H)] [14]
and [(C5Me5)2Ir2Cl2(m-Cl)(m-H)] [15], the metal–metal
Fig. 1. Molecular structure of 1. PLUTON
/PLATON view (50% probability ellipsoids [14].

192
G. Su¨ss-Fink et al. / Journal of Organometallic Chemistry 602 (2000) 188–192
Table 4
Acknowledgements
,
Selected bond lengths (A) and bond angles (°) for 1
We thank the Fonds National Suisse de la Recherche
Scientifique for financial support of this work. A gener-
ous loan of ruthenium trichloride hydrate by the John-
son Matthey Technology Centre is gratefully
acknowledged.
H(1Ru)ꢀRu(1)ꢀRu(2) 52.211(17) H(1Ru)ꢀRu(2)ꢀRu(1) 0.0000(0)
,
Bond lengths (A)
Ru(1)ꢀH(1Ru)
Ru(1)ꢀC(2)
Ru(1)ꢀC(3)
Ru(1)ꢀC(1)
Ru(1)ꢀC(6)
Ru(1)ꢀC(5)
Ru(1)ꢀC(4)
Ru(1)ꢀCl(2)
Ru(1)ꢀCl(1)
Ru(1)ꢀRu(2)
1.75(2)
Ru(2)ꢀH(1Ru)
Ru(2)ꢀC(12)
Ru(2)ꢀC(16)
Ru(2)ꢀC(15)
Ru(2)ꢀC(11)
Ru(2)ꢀC(13)
Ru(2)ꢀC(14)
1.76(3)
2.151(2)
2.171(3)
2.178(2)
2.179(3)
2.207(3)
2.211(3)
2.4053(8) Ru(2)ꢀCl(3)
2.4115(7) Ru(2)ꢀCl(1)
2.9573(4)
2.154(3)
2.170(3)
2.177(3)
2.178(3)
2.198(3)
2.216(3)
2.4122(9)
2.4127(7)
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C(3)ꢀRu(1)ꢀCl(2)
H(1Ru)ꢀRu(1)ꢀCl(1)
C(3)ꢀRu(1)ꢀCl(1)
H(1Ru)ꢀRu(1)ꢀRu(2) 32.5(8)
C(5)ꢀRu(1)ꢀRu(2)
Cl(2)ꢀRu(1)ꢀRu(2)
Cl(1)ꢀRu(1)ꢀRu(2)
Cl(3)ꢀRu(2)ꢀCl(1)
85.9(9)
H(1Ru)ꢀRu(2)ꢀCl(3)
90.6(9)
90.81(8)
84.5(7)
160.53(7) C(12)ꢀRu(2)ꢀCl(3)
84.6(8)
93.56(8) C(12)ꢀRu(2)ꢀCl(1)
H(1Ru)ꢀRu(2)ꢀCl(1)
164.69(8)
H(1Ru)ꢀRu(2)ꢀRu(1) 32.5(7)
172.77(9) Cl(3)ꢀRu(2)ꢀRu(1)
88.98(2) Cl(1)ꢀRu(2)ꢀRu(1)
52.211(17) Ru(1)ꢀCl(1)ꢀRu(2)
89.77(3) Cl(2)ꢀRu(1)ꢀCl(1)
87.48(2)
52.173(18)
75.616(19)
88.82(3)
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Cl3ꢀRu2ꢀRu1ꢀCl2 being −179.04(3)°, so that the two
terminal chloro ligands are almost perfectly opposite to
each other and lie in the same plane with the RuꢀRu
backbone. The angles Cl3ꢀRu2ꢀCl1 and Cl2ꢀRu1ꢀCl1
are found to be 89.77(3) and 88.82(3)°, respectively;
therefore the plane defined by the chloro bridge and the
Ru2 backbone is almost perpendicular to that defined
by the termine chloro ligands and the two ruthenium
atoms. The bridging hydride ligand is almost in the
same plane as the chloro bridge, the torsion angle
HꢀRu1ꢀCl1ꢀRu2 being −3.7(9)°.
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