Tethering versus non-coordination of hydroxy and methoxy side chains in arene half sandwich dichloro ruthenium complexes

Article abstract of DOI:10.1002/zaac.200500385

We are reporting on the hydroxyalkyl appended arene ruthenium half sandwich complexes [{η⁶-C₆H₅(CH₂) _nOH}RuCl₂] (n = 2, 3) and the methyl ether of the hydroxypropyl derivative. Most significantly, a structural comparison between the hydroxypropyl complex 1a and its methyl ether 2a reveals, that the latter adopts the conventional dichloro bridged dimeric structure while 1a is a monomer. Coordinative saturation of the ruthenium centre is achieved by intramolecular coordination of the appended hydroxy function, thus rendering the functionalized arene an eight electron donor chelate ligand. The structure is further stabilized by intermolecular OH...Cl hydrogen bridges between a terminal chloride ligand of one and the coordinated hydroxy group of a neighbour molecule, resulting in a sheet structure. These intermolecular interactions appear to be even stronger in the hydroxyethyl analogue. Several phosphine adducts have been prepared from the hydroxy or alkoxy functionalized [(η⁶-arene)RuCl₂]_n precursors, including water soluble P(CH₂OH)₃ adducts. Electrochemical properties of the phosphine adducts and of the dichloro bridged aryl ether complex 2a are also discussed.

Full text of DOI:10.1002/zaac.200500385

DOI: 10.1002/zaac.200500385
Tethering versus Non-Coordination of Hydroxy and Methoxy Side Chains in
Arene Half Sandwich Dichloro Ruthenium Complexes
Jadranka Cubriloa,b,*, Ingo Hartenbachb, Thomas Schleidb, and Rainer F. Winter*,a
ˇ
Regensburg, Institut für Anorganische Chemie der Universität
Received September 23rd, 2005.
Dedicated to Professor Henri Brunner on the Occasion of his 70th Birthday
Abstract. We are reporting on the hydroxyalkyl appended arene
ruthenium half sandwich complexes [{η6-C6H5(CH2)nOH}RuCl2]
(n ϭ 2, 3) and the methyl ether of the hydroxypropyl derivative.
Most significantly, a structural comparison between the hydroxy-
propyl complex 1a and its methyl ether 2a reveals, that the latter
adopts the conventional dichloro bridged dimeric structure while
1a is a monomer. Coordinative saturation of the ruthenium centre
is achieved by intramolecular coordination of the appended hy-
droxy function, thus rendering the functionalized arene an eight
electron donor chelate ligand. The structure is further stabilized
by intermolecular OH···Cl hydrogen bridges between a terminal
chloride ligand of one and the coordinated hydroxy group of a
neighbour molecule, resulting in a sheet structure. These intermole-
cular interactions appear to be even stronger in the hydroxyethyl
analogue. Several phosphine adducts have been prepared from the
hydroxy or alkoxy functionalized [(η6-arene)RuCl2]n precursors,
including water soluble P(CH2OH)3 adducts. Electrochemical pro-
perties of the phosphine adducts and of the dichloro bridged aryl
ether complex 2a are also discussed.
Keywords: Ruthenium; Crystal Structure; H-Bridge; Electro-
chemistry
Introduction
plexes of arenes with oxygen containing groups such as
ethers or the hydroxy function [12]. Kurosawa and co-work-
ers have briefly reported on [{η6-C6H5(CH2)nOH}RuCl2]
(n ϭ 2, 3) and assumed them to possess dimeric structures
with two chloride bridges connecting the {(η6-arene)RuCl}
units as it is ususally found for this type of complexes. No
analytical data were, however, provided and no further evi-
dence for these conclusions has been presented [13, 14]. The
cationic derivatives [{η6:η1-C6H5(CH2)3OH}Ru(PR3)Cl]ϩ
Transition metal half-sandwich complexes with potentially
coordinating groups appended to the cyclic perimeter are
receiving increasing attention as a special class of complexes
bearing hemilabile ligands. The dangling functionality may
serve to stabilize otherwise elusive and coordinatively un-
saturated species by forming an additional coordinate bond
to the metal atom, thus rendering the respective arene a
tetradentate chelate ligand. Recent work on arene half-
sandwich complexes of ruthenium has mainly concentrated
on tethered phosphine [1Ϫ9] or arsine [6] groups which
were found to readily coordinate to the metal atom. Ap-
pended phosphine groups may even serve as a “Trojan
horse” by anchoring the functionalized arene to the metal
atom prior to π-coordination. Arene displacement in com-
plexes [(η6-arene)RuCl2{PR2(CH2)naryl}] is then achieved
by an either thermally [1, 2, 4, 8] or oxidatively induced
substitution step [1]. These studies have also disclosed, that
tethered coordinating groups may endow such complexes
with reactivities that differ significantly from their non-tethered
congeners [10, 11]. Much less work has been done on com-
(PR3 ϭ PPh3, PEt3) and [{η6:η1-C6H5(CH2)3OH}RuL2]2ϩ
,
where L2 is a chelating dinitrogen donor such as 2,2Ј-bipyri-
dine, 1,10-phenanthroline or a bisoxazolonyl ligand, clearly
show the coordinating ability of the hydroxy group. Accord-
ing to NMR studies, the cationic derivatives preserve their
tethered structures with the oxygen atom bonded to the me-
tal even in methanolic solution [14]. The utility of those
complexes for cycloisomerization and ring closing meta-
thesis of diolefins has recently been demonstrated [15]. Ad-
ditional work made use of the reactivity inherent to the
hydroxy function and its conversion to a diaryl phosphinic
ester by reaction with Ph2PCl [14], deprotonation to a coor-
dinating alcoholate [14], and esterification by reaction with
ferrocene carboxylic acids [16] have been reported.
As a part of our ongoing programme on using arene di-
chloro ruthenium complexes as templates for cyclooligo-
merization and co-cyclization reactions [17] we have also
prepared and investigated ruthenium dichloro half-sand-
wich complexes with the hydroxy- and methoxypropyl side
chain (1a, 2a) as well as the shorter chain ethyl alcohol 3a.
We here report the full characterization of these complexes
along with the crystal structures of the propyl methyl ether
* Prof. Dr. Rainer F. Winter
a) Institut für Anorganische Chemie der Universität
Universitätsstraße 31
D-93040 Regensburg
e-mail: rainer.winter@chemie.uni-regensburg.de;
b) Institut für Anorganische Chemie der Universität Stuttgart
Pfaffenwaldring 55
D-70569 Stuttgart
400
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Arene Half Sandwich Dichloro Ruthenium Complexes
and the hydroxypropyl derivatives. Contrary to previous re-
ports, the latter complex turned out to be monomeric in the
solid state with the hydroxy function coordinated to the me-
tal atom and an intermolecular hydrogen bridge between
the OH proton and a chloride ligand of a neighbouring
molecule. We have also prepared the triisopropylphosphine
adducts of complexes 1a Ϫ 3a as well as the tricyclohexyl-
phosphine adducts of 1a and 2a and the P(CH2OH)3 con-
taining complexes 1d,e. Voltammetric data on most com-
plexes are provided as well.
Here, a strong donor solvent is also likely to interfere with
the intramolecular coordination of the hydroxy group, as it
is present in the solid state (see following section) and very
likely also in a non-coordinating solvent like CD2Cl2.
Crystallographic investigation of 1a and 2a
Crystals suitable for crystallographic determinations of the
molecular structures have been obtained for the propyl
methyl ether as well as the hydroxypropyl benzene derived
complexes by slowly cooling a hot saturated solution of the
respective complex in ethanol. Plots of the molecular struc-
tures are provided as Figures 1 and 2. Relevant data per-
Results and Discussion
The dichloro complexes 1a-3a
The synthesis of the functionalized arene complexes 1a, 2a
and 3a followed the established methods [14, 18]. First the
parent arene was reduced to the corresponding cyclohexadi-
ene under Birch conditions [19]. The cyclohexadienes were
then reacted with commercial hydrated RuCl3 where they
simultaneously serve as reductant and ligand to give the
respective arene complexes [{η6-C6H5(CH2)nOR}RuCl2]
(n ϭ 3, R ϭ H: 1a, R ϭ Me: 2a; n ϭ 2, R ϭ H: 3a) in good
yields. These complexes were obtained as orange solids by
slowly cooling the concentrated mother liquors (1a, 2a) or
as an orange brown powdery precipitate (3a). The hydroxy
and methoxy substituted congeners 1a and 2a show mark-
edly differing solubilities. While the ether is readily soluble
in moderately polar organic solvents such as chloroform
and methylene chloride, the hydroxypropyl derivative 1a is
only moderately soluble in CH2Cl2. The shorter chain
hydroxyethyl analogue 3a finally is very sparingly soluble
even in boiling 1,2-dichloroethane and requires coordinat-
ing solvents like dimethylsulfoxide or dimethylformamide to
allow for NMR spectroscopic characterization. This already
points to the presence of significant intermolecular contacts
via hydrogen bridges sustained by the OH group as the do-
nor. In these donor solvents the arene protons and those of
the ethyl side chain of 3a give rise to sharp, well resolved
resonance signals. The 13C NMR spectra are likewise un-
suspicious. Asides from disrupting the intermolecular hy-
drogen bonds, donor solvents may also coordinate to the
metal atom and cleave the Ru-Cl bridges of [(η6-arene)RuCl2]2
dimers or displace other donors. Dichloro bridged di-
ruthenium complexes [(η6-arene)RuCl2]2 are known to form
monomeric complexes [(η6-arene)RuCl2(L)], [(η6-arene)-
RuCl(L)2]ϩ or [(η6-arene)Ru(L3)]2ϩ in strong donor sol-
vents (L ϭ dmso, dmf, OH2) [20Ϫ22]. As positive charge
accumulates upon chloride substitution, the resonance sig-
nals of the coordinated arene are commonly shifted to
lower field [14, 21, 22]. While the exact nature of the species
present in dmso or dmf solutions of the hydroxyethylben-
zene dichloro complex 3a remains an open issue, it is still
interesting to note a low field shift of 0.30 to 0.35 ppm for
the aryl protons when dmf-d7 is replaced by dmso-d6. No
such shift differences are observed for the protons of the
hydroxyalkyl side chain. Similar trends also prevail for 1a.
Figure 1 Molecular structure of [(η6-C6H5(CH2)3OMe)RuCl2]2
(2a) in the crystal.
Figure 2 Molecular structure of [(η6-C6H5(CH2)3OH)RuCl2] (1a)
in the crystal, showing a OH···Cl bonded pair.
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J. Cubrilo, I. Hartenbach, Th. Schleid, R. F. Winter
and angles. The ether substituted complex crystallizes as a
dimer, a structure which is commonly observed for com-
plexes of the general composition (η6-arene)RuCl2. Two
chloride bridges tie the ruthenium atoms together forming
a central Ru2Cl2 rhombus. There is a centre of inversion
located at the midpoint of the central Ru2Cl2 entity and the
unit cell contains two half molecules of 2a. As it is borne
out by crystallographic symmetry, the coordinated arenes
are situated on opposite sides of the central Ru2Cl2 ring
to give the sterically preferred transoid arrangement. The
methoxypropyl side chains point away from the terminal
chloride ligands and the central Ru2Cl2 ring such that the
molecule displays a “stretched” conformation. There is
some disorder concerning atoms C9 and O9 of the meth-
oxypropyl side chains. As is indicated in Figure 1, these
atoms are disordered over two positions (C91, C92, O91,
O92) with occupancy factors of 0.47 and 0.53 with the C7
and C10 atoms common to both different orientations. The
bonds to the bridging chloride ligands are somewhat longer
Table 1 Data pertinent to the data collection and structure solu-
tion of 1a and 2a.
2a
1a
Empirical formula
Formula weight
Temperature / K
C20H28Cl4O2Ru2
644.36
100(2)
C9H12Cl2ORu
308.16
100(2)
˚
λ / A
0.71073
0.71073
Crystal system
Space group
triclinic
P1
monoclinic
C2/c
¯
Crystal size / mm
Unit cell dimensions
0.3 ϫ 0.3 ϫ 0.2
0.25 ϫ 0.2 ϫ 0.2
˚
a / A
7.4241(2)
7.7451(3)
10.7216(3)
108.792(2)
92.177(2)
103.886(2)
1
13.6525(9)
9.3455(8)
15.7922(11)
˚
b / A
˚
c / A
α / deg
β / deg
γ / deg
90.47(1)
Z
8
3
˚
Volume / A
562.10(3)
1.904
2014.8(3)
2.032
ρcalcd / g·cmϪ3
Theta range / deg
Limiting indices
2.02Ϫ27.51
Ϫ8 Յ h Յ 9,
Ϫ10 Յ k Յ 10,
Ϫ13 Յ l Յ 13
12915
2573
0.0946
3.68Ϫ28.29
Ϫ18 Յ h Յ 18,
Ϫ12 Յ k Յ 10,
Ϫ21 Յ l Յ 19
11060
2483
0.0925
˚
(2.443(1) and 2.448(1) A) than those to the terminal one
Collected reflections
Unique reflections
R (int)
˚
(2.406(1) A), as it is usually observed for such dichloro
bridged dimers. These values compare favourably with
µ (Mo-Kα>) / mmϪ1
R1 (all data)
1.833
0.0377
2.041
0.0704
those for [(η6-C6Me6)RuCl2]2 (RuϪCl(terminal) ϭ 2.394(1),
˚
RuϪCl(bridge) ϭ 2.460(1) A) [23] and the two independent
wR2 (all data)
0.0952
1.171
0.0871
1.088
GooF on F2
molecules within the unit cell of [(p-cymene)RuCl2]2
F(000)
Largest diff. peak / hole
320
0.549/Ϫ1.197
1216
0.730/Ϫ0.901
˚
(RuϪCl(terminal) ϭ 2.416(3) A, RuϪCl(bridge) ϭ 2.451(3)
˚
and 2.464(3) A for the one and RuϪCl(terminal) ϭ 2.420
˚
˚
and 2.435(3) A, RuϪCl(bridge) ϭ 2.437(3) Ϫ 2.488(3) A for
the other molecule) [24]. The RuϪCl2 bond is roughly
orthogonal to the central Ru2Cl2 plane (85.2°) while the
planes of the arene rings are tilted at an angle of 54.6°
against the Ru2Cl2 entity. All other bond parameters, in-
cluding the average Ru-C(arene) distances, are unremark-
able and warrant no further discussion.
˚
Table 2 Selected bond lengths in A and angles in deg. for comple-
xes 1a and 2a.
2a
1a
Ru1ϪCl1
Ru1ϪCl1A
Ru1ϪCl2
Ru1ϪC1
Ru1ϪC2
Ru1ϪC3
Ru1ϪC4
Ru1ϪC5
Ru1ϪC6
Arenea)ϪRu1
C1ϪC2
C2ϪC3
C3ϪC4
C4ϪC5
C5ϪC6
C1ϪC6
C6ϪC7
C7ϪC8
2.4427(8)
2.4481(8)
2.4067(8)
2.178(3)
2.164(4)
2.174(3)
2.150(3)
2.177(3)
2.185(3)
1.643(3)
1.417(5)
1.416(6)
1.415(5
Ru1ϪCl1
Ru1ϪCl2
Ru1ϪO1
Ru1ϪC1
Ru1ϪC2
Ru1ϪC3
Ru1ϪC4
Ru1ϪC5
Ru1ϪC6
2.409(1)
2.421(1)
2.154(3)
2.181(4)
2.149(5)
2.157(5)
2.164(5)
2.194(5)
2.169(4)
1.640(3)
1.419(7)
1.422(7)
1.400(8)
1.422(7)
1.433(7)
1.422(7)
1.508(7)
1.526(7)
1.496(7)
1.448(6)
The hydroxypropyl derivative 1a, on the other hand, crys-
tallizes as a monomer. Intramolecular chelation makes the
arene ligand an eight electron donor ligand and renders the
ruthenium atom an electronically saturated 18 valence elec-
tron centre. The Ru-C6-C7-C8-C9-O1 six membered chelate
adopts a half-chair conformation with the flap pointing to-
ward Cl1 and is devoid of any notable strain. Thus, the
Ru-C(arene) bond lengths fall in the same range as those
observed in 2a and deviations of individual values from the
average are no larger as in non-tethered 2a. The RuϪCl
Arenea)ϪRu1
C(1)ϪC(2)
C(2)ϪC(3)
C(3)ϪC(4)
C(4)ϪC(5)
C(5)ϪC(6)
C(1)ϪC(6)
C(6)ϪC(7)
C(7)ϪC(8)
1.426(5)
1.419(5)
1.423(5)
1.504(5)
1.533(5)
˚
distances of 2.409(1) and 2.421(1) A compare well to those
found for the plethora of neutral adducts of the type
C8ϪC91 / C8ϪC92 1.526(9) / 1.564(8) C(8)ϪC(9)
C91ϪO91 / C92ϪO92 1.422(10) / 1.436(10) C(9)ϪO(1)
O91ϪC10/O92ϪC10 1.543(8) / 1.467(7)
[(η6-arene)RuCl2L] and phosphine tethered complexes like
[{η6-C6H5(CH2)3PMe2}RuCl2] (2.405(2) to 2.421(2) A),
˚
[{η6-C6H2Me3-2,4,6-(1-C3H6PPh2)}RuCl2]
(2.4159(10)
Cl1ϪRu1ϪCl2
85.65(3)
82.60(3)
87.35(3)
128.7(3)
130.3(3)
Cl(1)ϪRu(1)ϪCl(2)
O(1)ϪRu(1)ϪCl(1)
O(1)ϪRu(1)ϪCl(2)
AreneϪRu(1)ϪCl(1) 129.3(1)
AreneϪRu(1)-Cl(2) 128.2(1)
87.28(4)
83.57(10)
82.37(10)
Cl1ϪRu1ϪCl1A
Cl2ϪRu1ϪCl1A
Arenea)ϪRuϪCl1
Arenea)ϪRu1ϪCl2
and 2.4425(10) A), or in [(η6-C6Me5C3H6PPh2)RuCl2]
˚
(2.4016(12) and 2.4163(12) A) [4], [{η6-C6H3Me2-3,5-
˚
˚
(1-C3H6PPh2)}RuCl2]
(2.397(2)
and
(2.4040(10)
2.420(2) A),
Arenea)ϪRuϪCl1A 126.6(3)
AreneϪRuϪO(1)
129.9(1)
[{η6-C6H4Et-4-(1-C3H6PPh2)}RuCl2]
and
6
˚
Arenea) ϭ midpoint of the arene ring
2.4073(11) A) [3], or [{η -C6H5(CHMeC2H4)3PPh2}RuCl2]
˚
(2.4037(7) and 2.4271(6) A [9]. The RuϪO bond length of
˚
taining to the data collection and structure solution are col-
lected in Table 1. Table 2 provides important bond lengths
2.153(3) A is very similar to that observed in the dicationic
Ϫ
chelate [{η6:η1-C6H5(CH2)3OH}Ru(phen)]2ϩ(BF4)2 where
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Arene Half Sandwich Dichloro Ruthenium Complexes
˚
˚
phen denotes 1,10-phenanthroline (2.145(3) A), but is
in graphite (3.35 A). Still, in 1a the arene rings of molecules
notably longer as the Ru-O(alkoxylate) bond in
belonging to different sheets are offset against each others.
The structures of 1a and its triphenylphosphine adduct
as well as the comparison to that of the corresponding
methyl ether underpin the significance of even moderately
strong hydrogen bridges in determining the molecular con-
formation as well as the association and packing of individ-
ual molecules and the physical properties (such as solubilit-
ies) of compounds.
[{η6:η1-C6H5(CH2)3O}Ru(bipy)]ϩ(BF4)Ϫ (bipy ϭ 2,2Ј-bi-
˚
pyridine, 2.050(5) A) [14]. The OH proton, like every other
hydrogen atom of this structure, was directly located from
the electron density map. It is found to point away from the
metal and to project toward a chloride ligand of a neigh-
bour molecule forming a grossly linear (154.9(1)°) OH···Cl
˚
bridge with a H···Cl separation of 2.24(1) A and an O···Cl
˚
distance of 3.0513(2) A. The OH···Cl bridge present in 1a
is thus significantly shorter than the average hydrogen bond
Phosphine adducts of 1a-3a
between an OH donor and a metal atom bonded chloride
˚
Phosphine adducts of [{η6-C6H5(CH2)nOR}RuCl2]n are
readily prepared by reacting the corresponding dichloro
complexes with a slight excess of a phosphine in CH2Cl2. In
the case of 1a and 3a which are only moderately or nearly
insoluble in this medium, gradual dissolution of the starting
complex occurred as the phosphine complexes formed. The
synthesis of the P(CH2OH)3 derived complexes 1d,e re-
quires the use of methanol as the solvent, and only intrac-
table product mixtures were formed in CH2Cl2. Referring
to the work of Therrien and Stepnicka [16], the decidedly
higher solubility of the phosphine adducts may not only
be due to the presence of solubilizing substituents on the
phosphine but also to a change of the nature of the OH···Cl
contacts from intermolecular to intramolecular ones. At
present we have, however, no crystallographic evidence to
support the presence of intramolecular OH···Cl interactions
for the phosphine adducts reported herein.
ligand as the acceptor (dav Cl···H
ϭ
2.349(9) A,
˚
dav O···Cl ϭ 3.272(8) A) [25]. This signals, that the OH···Cl
interaction in 1a is rather strong. A similar intramolecular
˚
OH···Cl contact with an O···Cl distance of 3.121(2) A and
an OH···Cl angle of 159.2° has just been reported by
ˇ
ˇ
ˇ
Stepnicka,
Therrien
and
their
co-workers
for
[{η6-C6H5(CH2)3OH}RuCl2(PPh3)], the triphenylphos-
phine adduct of 1a [16].
ˇ
ˇ
ˇ
All phosphine complexes are characterized by sharp
singlet resonances in their 31P NMR spectra with resonance
shifts near 30 ppm for the tricyclohexyl phosphine and the
tris(hydroxymethyl)phosphine and of about 40 ppm for the
triisopropylphosphine derivatives. The proton and carbon-
13 NMR spectra likewise show the resonances of the ring
protons and of the triisopropyl substituent (for 1bϪ3b) in
a symmetric environment, which indicates the presence of
a molecular mirror plane. For the tricyclohexylphosphine
complex 2b the appropriate number of CH2 multiplets ap-
pears in the 1H and 13C NMR spectra. Attempts to prepare
the P(CH2OH)3 derived monoadduct of the hydroxy-
propylbenzene derivative 1d initially lead to slightly impure
samples with some admixture of another phosphine com-
plex, as it was indicated by the presence of a second singlet
resonance at somewhat lower field. This second symmetric
phosphine complex was finally identified as the cationic
Figure 3 Plot showing the packing and the OH···Cl contacts
(dotted lines) within the solid state structure of compound 1a.
In 1a these interactions also form a peculiar hydrogen
bonding network that determines the packing in the crystal.
Molecules of 1a arrange in double sheets that run parallel
to the crystallographic ab plane. The RuϪCl2 vectors of the
molecules belonging to the upper layer and those of the
lower layer of each double sheet are roughly antiparallel to
each others. Each molecule forms two OH···Cl contacts
with different neighbours from the other layer of the double
sheet, one via its OH group and one via its Cl2 atom. As a
whole, molecules interlinked by these hydrogen bonds form
one-dimensional infinite zig-zag chains within the double
sheets which propagate along the a vector. The coordinated
arene rings of the molecules building the one layer within a
double sheet tilt toward the Cl2 atom of the constituents of
bis(phosphine)
adduct
[{η6-C6H5(CH2)3OH}RuCl-
{P(CH2OH)3}2]ϩClϪ. It was subsequently prepared and
fully characterized by reacting [{η6-C6H5(CH2)3OH}RuCl2]
and P(CH2OH)3 in a stoichiometric ratio of 1:2. Mixtures
of [{η6-C6H5(CH2)3OH}RuCl{P(CH2OH)3}2]ϩ ClϪ and
[{η6-C6H5(CH2)3OH}RuCl2] in CD2Cl2 are gradually
transformed to give predominantly [{η6-C6H5(CH2)3OH}-
RuCl2{P(CH2OH)3}]. Formation of the cationic bisadduct
[(η6-arene)RuCl{P(CH2OH)3}2]ϩ ClϪ was even more
pronounced in the case of 3a, where its formation besides
the expected monoadduct [{η6-C6H5(CH2)2OH}RuCl2-
˚
the other. These CH···Cl contacts, however, exceed 3.8 A
and are most probably too weak to allow for any significant
interaction. Adjacent double sheets pack such that the ar-
ene rings are strictly parallel to each others. The distance
˚
between the arene planes of adjacent layers is 3.197 A and
is thus shorter as the distance between the individual layers
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J. Cubrilo, I. Hartenbach, Th. Schleid, R. F. Winter
{P(CH2OH)3}] accounted to about 30 % of phosphine con-
taining species even when substoichiometric amounts of the
phosphine were employed. Owing to the low solubility of
3a in CH2Cl2 and the formation of several side products,
reactions of 3a with P(CH2OH)3 had to be performed in
methanol as the solvent. The highly polar methanol solvent
considerably aids in dissociating a chloride ligand, thus
opening a coordination site which is then occupied by a
second equivalent of the phosphine. The outcome of the
reactions with less than one equivalent of P(CH2OH)3 indi-
cates, that under these conditions chloride substitution oc-
curs at a similar rate as adduct formation. Of note is the
finding, that P(CH2OH)3 here coordinates without any loss
of formaldehyde from the phosphine. Reactions utilizing
this phosphine sometimes provide complexes that contain
partially deformylated PHn(CH2OH)3Ϫn ligands, mostly
with high chemoselectivity. A notable example in ruthenium
chemistry is provided by the work of Whittlesey [26]. The
factors that govern the event and the degree of deformyl-
ation from this phosphine are presently unknown. All the
new complexes bearing the P(CH2OH)3 ligand described
herein are hygroscopic and readily dissolve in water. This
may make them suitable precursors for water soluble arene
monophosphine half-sandwich catalysts. Half sandwich
ruthenium arene complexes have sucessfully been employed
in numerous catalytical applications [27] such as atom
transfer radical polymerization (ATRP) [28], ring-opening
or ring-closing metathesis [2, 29Ϫ31], or the cycloisomeriz-
ation of diolefins [15]. We also note that recent work dis-
closed the utility of closely related complexes
[(η6-arene)RuCl2{P(CH2OH)3}] in the catalytic isomeriz-
ation of allylic alcohols and the hydration of alkynes to ke-
tones under biphasic conditions [32]. Attempts to crystallize
any of these complexes in order to assess the intra- and
intermolecular hydrogen bonding which may involve the
hydroxyalkyl side chains on the arene and the phosphine
hydroxymethyl groups [26] have not yet provided suitable
specimen for X-ray diffraction studies.
(µ-Cl)2{RuCl(p-cymene)]Ϫ. This latter species dissociates
another equivalent of chloride but may be back oxidized to
the starting dimer by a sequence involving electron transfer
and chloride association steps [32]. Anodic oxidation of
[(η6-C6Me6)RuCl2]2 was observed to proceed in two sequen-
tial one-electron steps. Both processes are prone to fast
chemical follow processes which ultimately yield
nϩ
[(η6-C6Me6)RuCl3] and oligomeric [(η6-C6Me6)RuCl]n
by disproportionation [33].
Here, we report on the electrochemical properties of
[{η6-C6H5(CH2)3OMe)}RuCl2]2 (2a) in CH2Cl2/NBu4PF6.
Voltammograms at room temperature show a close to
reversible reduction at Ϫ0.79 V (peaks A/AЈ) and an irre-
Electrochemistry
The electrochemical behaviour of half-sandwich dichloro
complexes of the type [(η6-arene)RuCl2]2 has been probed
by various authors and displays a rather intricate behaviour
with a rich chemistry following or even preceding each
electron transfer step. As it is evidenced by these investi-
gations, prototypical [(p-cymene)RuCl2]2, in supporting
electrolyte solution, is in equilibrium with the salt
[{(p-cymene)Ru}2(µ-Cl3)]ϩ ClϪ. This dissociation step is
promoted by media of high ionic strength and is virtually
complete in CH2Cl2/NBu4PF6. The trichloro bridged
dimer gives a cathodic peak which precedes the reduction
of the neutral dichloro bridged dimer. Authentic
[(η6-arene)RuCl2]2 is reduced in a chemically partially re-
versible and kinetically quasireversible one-electron step,
and the resulting reduction product was assigned the un-
symmetrical dichloro bridged structure [{(p-cymene)Ru}-
Figure 4 Cyclic voltammograms of complex 2a in CH2Cl2/
NBu4PF6 at v ϭ 0.1 V/s. a) 298 K; b) 196 K (CO2/isopropanol
slush bath); c) 298 K, but in the presence of excess NaSbF6.
404
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Z. Anorg. Allg. Chem. 2006, 400Ϫ408

Arene Half Sandwich Dichloro Ruthenium Complexes
versible anodic oxidation at Ep ϭ 0.33 V (peak C). Peaks A
and C are associated with about the same peak currents
under all conditions (Figures 4a-c). When the scan is re-
versed after traversing peak C, the new cathodic peak D is
observed at Ep ϭ Ϫ0.42 V. As the sweep rate is increased
or the temperature is lowered, the reversibility of the oxi-
dation step increases and the associated counter peak CЈ
appears (E1/2 ϭ 0.285 V) with the concomitant disappear-
ance of peak D (see Figure 4b). This behaviour is highly
reminiscent of other dichloro bridged ruthenium dimers
such that peaks A and C are due to the reduction and the
oxidation of [{η6-C6H5(CH2)3OMe)}RuCl2]2. In the case of
[(η6-C6Me6)RuCl2]2, a peak corresponding to D has been
ascribed to the reduction of monomeric [(η6-C6Me6)RuCl3]
formed in the disproportionation following oxidation.
Compared to [(η6-C6Me6)RuCl2]2, wave C/CЈ is shifted by
about 450 mV to more negative potentials and this may
indicate some remarkable stabilization of the oxidized form
through intramolecular solvation by the appended ether
moiety. When the cathodic sweep is continued past the
A/AЈ couple, another irreversible reduction peak is ob-
served at ca. Ϫ1.20 V (peak B in figures 4a, c). This feature
is associated with considerably higher currents as the A/AЈ
couple and peak C. Peak B is followed by additional, broad
and ill-defined features at even more cathodic potentials
(not shown in Figures 4a-c). On the reverse scan, an ad-
ditional anodic peak (peak E) at Ϫ0.53 V indicates the for-
mation of a new electroactive follow product.
Figure 5 CV of compound 2b in CH2Cl2/NBu4PF6, 298 K, v ϭ 0.1 V/s.
half-wave potentials thus reflect the electron density at the
ruthenium atom and electron donation from the ancillary
ligands. We observe essentially the same behaviour for the
phosphine adducts 1b-d, 2b,c and 3b. There is just one an-
odic wave within the CH2Cl2/NBu4PF6 electrolyte window,
and this wave always constitutes a chemically reversible
couple with ip,c/ip,a ratios of at least 0.95 even at low sweep
rates. The voltammetric response of compound 2b is dis-
played as Figure 5 and may serve as a representative ex-
ample. Peak potential differences slightly exceed the values
of the internal ferrocene/ferrocenium standard with larger
differences as the sweep rate is increased. Such findings are
diagnostic of somewhat sluggish electron transfer kinetics
(quasireversible behaviour). Half-wave potentials and peak-
to-peak separations are listed in Table 3. Comparison of the
data shows that the half-wave potentials are sensitive to
both, the identity of the phosphine and of the arene ligands.
The more basic PiPr3 and PCy3 adducts lead to distinctly
lower E1/2 values as the tris(hydroxylated) P(CH2OH)3 with
a difference of 190 mV between 1b and 1d. No clear trend
arises from the substitution of the arene ligand. While the
3-hydroxypropylbenzene derived complex 1b is somewhat
easier to oxidize than its methyl ether 2b, the opposite holds
for the PCy3 complexes 1c, 2c.
Addition of the mild chloride scavenger NaSbF6 to the
supporting electrolyte solution has the effect of further in-
creasing the intensity of peak B and decreasing the chemical
reversibility of the A/AЈ couple, most probably by accelerat-
ing the rate of chloride dissociation from reduced
Ϫ
[{η6-C6H5(CH2)3OMe)}RuCl2]2 (Figure 4c). Given the
known propensity of [(η6-arene)RuCl2]2 to chloride loss in
ionizing media and the qualitative changes induced by the
presence of NaSbF6, we assign peak B as the reduction of
such a chloride dissociation product. Possible candidates
are trichloro bridged [{η6-C6H5(CH2)3OMe}Ru(µ-Cl3)Ru-
{η6-C6H5(CH2)3OMe}]ϩ or an unsymmetric complex
[{η6:η1-C6H5(CH2)3OMe}Ru(µ-Cl2)RuCl{η6-C6H5(CH2)3-
OMe}] with one appended ether moiety coordinated to a
ruthenium centre. While additional experiments are neces-
sary to unambiguously establish the nature of this species,
we favour the latter structure since trichloro bridged dimers
are commonly easier reduced as their neutral dichloro
bridged precursors. The hydroxy appended complexes gave
only ill defined, broad voltammetric responses and were not
further investigated. This is possibly due to a combination of
their limited solubility and a coupling of proton transfer from
the side chain hydroxy group to the electron transfer processes.
Half-sandwich phosphine complexes of the type
[(η6-arene)RuCl2(PR3)], on the other hand, display much
simpler electrochemical responses and usually undergo a
chemically reversible oxidation at fairly positive potentials
[4, 16, 34]. This oxidation is assigned as the Ru(II/III)
couple, i. e. as an essentially metal centred process. The
Table 3 Redox potentials of the complexes; peak-to-peak separa-
tions are given in parantheses a)
d)
2a
ϩ0.295(60) (C/CЈ) b), Ϫ0.790(65) (A/AЈ); Ϫ1.20 (B) c), Ϫ0.53 (E)
Ϫ0.43 (F) , Ϫ0.42 (D)
,
e
f
1b
1c
1d
2b
2c
3b
ϩ0.705(82)
ϩ0.735(81)
ϩ0.895 (81)
ϩ0.770 (73)
ϩ0.685 (75)
ϩ0.775 (77)
a) potentials are provided relative to the Fc/Fcϩ scale; b) at 196 K; c) irreversi-
ble reduction peak; d) irreversible anodic peak following reduction; e) irrever-
sible anodic peak following reduction in the presence of NaSbF6; f) irreversi-
ble cathodic peak following oxidation.
Z. Anorg. Allg. Chem. 2006, 400Ϫ408
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
zaac.wiley-vch.de
405

ˇ
J. Cubrilo, I. Hartenbach, Th. Schleid, R. F. Winter
[{C6H5(CH2)3OH)}Ru(PCy3)Cl2] (1c): Compound 1a (0.30 g,
0.97 mmol) and 0.273 g (0.49 mmol) of PCy3 were dissolved in 6 ml
of CH2Cl2 and stirred overnight. The filtered solution was dried in
vacuo and the residue was washed with 3ϫ4 ml of Et2O and dried.
Compound 1a was obtained as an orange brown fluffy powder in
a yield of 396 mg (69.2 %). Analysis calcd. for C27H45Cl2OPRu
(588.6); C 56.00 (calc 55.16); H 8.25 (7.71) %. mpϭ141.0 °C.
Experimental Section
Materials and methods. Hydrated RuCl3 (Ru content 42.41 %) was
obtained from Johnsson Matthey, and PiPr3, PCy3, and
P(CH2OH)3 from Strem. Solvents were dried over the appropriate
drying agents, distilled and stored under argon over molecular si-
eves. The functionalized cyclohexadienes required for the synthesis
of the [(η6-arene)RuCl2]n complexes were prepared by Birch re-
duction of their aromatic precursors following the general protocol
[19]. Electrochemistry was performed in a home-built cylindrical
vacuum tight one compartment cell. A spiral shaped Pt wire and a
Ag wire as the counter and reference electrodes are sealed into
opposite sides of the glass wall while the respective working elec-
trode (Pt or glassy carbon 1.1 mm polished with 0.25 µm diamond
paste (Buehler-Wirtz) before each experiment) is introduced via a
teflon screw cap with a suitable fitting. The cell may be attached
to a conventional Schlenk line via two sidearms equipped with
teflon screw valves and allows experiments to be performed under
an atmosphere of argon with approximately 2.5 ml of analyte solu-
tion. CH2Cl2 for electrochemical work was obtained from Fluka
(Burdick&Jackson Brand) and freshly distilled from CaH2 before
use. NBu4PF6 (0.25 mM) was used as the supporting electrolyte. All
potentials are referenced versus the ferrocene/ferrocenium couple.
Electrochemical data were acquired with a computer controlled
EG&G model 273 potentiostat utilizing the EG&G 250 software
package. NMR spectra were recorded on either a Bruker AC 250
or a Bruker AS 200 series spectrometer, at 293 K, in the indicated
solvent. Resonance shifts were referenced to residual, partially pro-
tonated solvent (1H), the solvent signal itself (13C) or external
H3PO4 (31P).
1H-NMR (CDCl3): δ ϭ 1.14-1.55 (m, br, 16 H), 1.6-1.9 (m, 10 H), 2.23 (m,
4 H), 2.49 (m, 3H), all CH2, CH (PCy3)), 1.93 (tt, J ϭ 7.7, 6.2 Hz, 2H,
CH2CH2CH2), 2.71 (t, J ϭ 7.7 Hz, 2H, PhCH2), 3.46 (t, J ϭ 6.2 Hz, 2H,
CH2O), 5.39 (m, 3H), 5.52 (t, J ϭ 5.0 Hz, 2H). 13C NMR(CDCl3): δ ϭ 27.9,
28.05, 29.36, 30.00, 30.26 (each s, CH2), 36.16 (d, JP-C ϭ 18.9 Hz, CH(PCy3),
2
72.13 (s, OCH2), 77.60, 84.97 (s, CH), 88.75 (d, JP-C ϭ 5.1 Hz, CH), 112.05
2
(d, JP-C ϭ 6.3 Hz, Cq). 31P NMR (CDCl3): δ ϭ 31.61 (s, PCy3).
[{η6-C6H5(CH2)3OH)}RuCl2{P(CH2OH)}3]
(1d):
134 mg
(0.43 mmol) of [{η6-C6H5(CH2)3OH}RuCl2] (1a) was reacted with
50 mg (0.40 mmol) of tris(hydroxymethyl)phosphine, P(CH2OH)3,
in 5 ml of CH2Cl2. The reaction mixture was allowed to stir over-
night and filtered by canula to remove some undissolved material.
The vacuum dried residue was washed with 3ϫ2 ml of Et2O. After
drying under vacuum 106 mg (57 %) of a brown, hygroscopic pow-
der was obtained. Analysis calcd. for C12H21O4PRuCl2 (432.2); C
31.68 (calc 33.34); H 5.34 (4.90) %. mp ϭ 106 °C.
1H-NMR (CD3OD): δ ϭ 1.93 (m, 2H, CH2CH2CH2), 2.55 (t, J ϭ 7.8 Hz,
3
3
2H, PhCH2), 3.32 (t, JH-H ϭ 0.9 Hz, 3H, P(CH2OH)3, 3H), 3.47 (d, JH-
ϭ 0.9 Hz, 6H, P(CH2OH)3), 4.83 (s, br, OH), 5.51 (t, J ϭ 6.8 Hz, 2H),
H
5.62 (dd, J ϭ 6.8, 4.6 Hz, 2H), 5.89 (t, J ϭ 4.6 Hz, 1H). 13C NMR(CDCl3):
δ ϭ 30.19 (s, CH2) 30.58 (s, PhCH2), 57.38 (d, JP-2C ϭ 64.2 Hz, P(CH2OH)3),
72.74 (s, CH2O), 78.28, 87.52 (s, CH), 88.70 (d, JP-C ϭ 5.3 Hz, CH), 111.5
2
(d, JP-C ϭ 4.2, Cq). 31P NMR (CDCl3): δ ϭ 29.06 (s, P(CH2OH)3).
[{η6-C6H5(CH2)3OH)}RuCl(P(CH2OH)3)2]؉ Cl؊ (1e): 0.052 g
(0.176 mmol) of [{η6-C6H5(CH2)3OH}RuCl2]2 was reacted with
45 mg (0.36 mmol) of tris(hydroxymethyl)phosphine, P(CH2OH)3,
in 5 ml of CH2Cl2. The reaction mixture was allowed to stir over-
night and filtered by canula to remove some undissolved material.
The filtered solution was dried in vacuo and the residue was washed
with 3ϫ2 ml of Et2O. After removing of Et2O in vacuo 56 mg
(59.3 %) of 1e was obtained as a brown, waxy, hygroscopic solid.
C15H30Cl2O7P2Ru (556.3).
[{η6-C6H5(CH2)3OH}RuCl2]2 (1a): In
a typical run, 9.30 g
(67.30 mmol) of (1,4-cyclohexadienyl)-1-propanol was combined
with 2.78 g (11.66 mmol) of hydrated RuCl3 in 70 ml of ethanol.
The mixture was heated under reflux for 6h. The microcrystalline
solid obtained after storing the mother liquor in the fridge over-
night was recrystallized from hot ethanol to give orange crystals of
1a in a yield of 2.79 g (77.6 %). Analysis calcd. for C9H12Cl2ORu
(308.2); C 35.43 (calc 35.08); H 3.97 (3.93) %;. mp ϭ 230.5 °C.
1H-NMR (CD3OD): δ ϭ 1.98 (tt, J ϭ 7.75, 6.1 Hz, 2H, CH2CH2CH2), 2.48
(t, J ϭ 7.75 Hz, 2H, PhCH2), 3.48 (dt, J ϭ 6.1, 2.5 Hz, 2H, CH2O), 4.07 (d,
1H-NMR (CDCl3): δ ϭ 1.85 (tt, J ϭ 7.2, 7.0 Hz, 2H, CH2CH2CH2), 2.63 (t,
J ϭ 7.2 Hz, 2H, PhCH2), 3.38 (t, J ϭ 7.0 Hz, 2H, CH2O), 5.39 (d, J ϭ
5.4 Hz, 2H), 5.57 (t, J ϭ 5.1 Hz, 2H), 5.64 (dt, J ϭ 5.4, 5.1 Hz, 1H). 1H-
NMR (dmso-d6): δ ϭ 1.81 (tt, J ϭ 7.6, 6.3 Hz, 2H, CH2CH2CH2), 2.43 (t,
J ϭ 7.6 Hz, 2H, PhCH2), 3.36 (t, J ϭ 6.3 Hz, 2H, CH2O), 5.73 (t, J ϭ
5.5 Hz, 1H), 5.74 (d, J ϭ 5.5 Hz, 2H), 5.98 (t, J ϭ 5.5 Hz, 2H). 13C
NMR(CDCl3): δ ϭ 29.76 (s, CH2), 30.05 (s, PhCH2), 71.79 (s, CH2O), 80.17,
80.86, 84.37 (each s, CH), 111.89 (Cq).
2
2
J ϭ 2.5 Hz, 1H, OH), 4.38 (dd, JPH ϭ 18.7, JHH ϭ 11.6 Hz, 12 H,
P(CH2OH)3), 4.82 (s(br), 6H, P(CH2OH)3), 5.41 (t, J ϭ 5.9 Hz, 1H), 6.25
(d, J ϭ 5.9 Hz, 2H), 6.58 (t, J ϭ 5.9 Hz, 2H). 13C NMR(CDCl3): δ ϭ 35.90
(s, CH2) 37.40 (s, PhCH2), 57.37 (d, JP-C ϭ 32.9 Hz, P(CH2OH)3), 72.00 (s,
2
CH2OH), 78.72, 87.08 (s, CH), 89.72 (d, JP-C ϭ 5.7 Hz, CH), the Cipso
quaternary carbon atom was not observed. 31P NMR (CDCl3): δ ϭ 38.18
(s, P(CH2OH)3).
[{η6-C6H5(CH2)3OMe)}RuCl2]2 (2a): Compound 2a was prepared
analogously to 1a from 7.31 g (48.00 mmol) of (1,4-cyclohexa-
dienyl)-1-propyl methyl ether and 1.97 g (8.27 mmol) of RuCl3 in
60 ml of ethanol. The orange red solution was allowed to cool over-
night at 4 °C, which gave 2a as a crystalline solid. The mother
liquor was removed by filtration and concentrated by distillation
to 15 ml. A further crop of microcrystals was obtained by cooling
this solution overnight in a fridge. The combined yield was 2.02 g
(73.5 %). Analysis calcd. for C20H28Cl4O2Ru2 (644.4); C 37.43 (calc
37.28); H 4.52 (4.38) %. mpϭ245 °C.
1H-NMR (CDCl3): δ ϭ 1.81 (tt, J ϭ 7.2, 5.9 Hz, 2H, CH2CH2CH2), 2.57 (t,
J ϭ 7.2 Hz, 2H, PhCH2), 3.22 (s, 3H, OCH3), 3.32 (t, J ϭ 5.9 Hz, 2H,
CH2O), 5.32 (d, J ϭ 5.7 Hz, 2H), 5.55 (t, J ϭ 5.2 Hz, 1H), 5.63 (dd, J ϭ 5.7,
5.2 Hz, 2H). 13C NMR(CDCl3): δ ϭ 29.76 (s, CH2), 30.05 (s, PhCH2), 58.90 (s,
OCH3), 71.79 (s, CH2O), 80.17, 80.86, 84.37 (each s, CH), 101.41 (Cq).
[{η6-C6H5(CH2)3OH)}Ru(PiPr3)Cl2] (1b): 0.30 g (0.97 mmol) of 1a
was reacted with 185 µl (0.48 mmol) of PiPr3 in 5 ml of CH2Cl2.
The reaction mixture was stirred overnight and filtered by cannula.
The clear solution was dried in vacuo. Then the residue was washed
with 3ϫ4 ml of Et2O. Drying in vacuo gave 354 mg of 1b (77.7 %).
Analysis calcd. for C18H33Cl2OPRu (468.4); C 47.10 (calc 46.16);
H 7.46 (7.10) %. mpϭ115.0 °C.
1H-NMR (CDCl3): δ ϭ 1.28, 1.34 (each d, J ϭ 7.2 Hz, 9 H, CH3(PiPr3)),
1.92 (tt, J ϭ 8.55, 6.2 Hz, 2H, CH2CH2CH2), 2.71 (t, J ϭ 8.55 Hz, 2H,
PhCH2), 2.77 (m, 3H, CH(PiPr3)), 3.43 (t, J ϭ 6.2 Hz, 2H, OCH2), 5.31 (t,
J ϭ 5.6 Hz, 2H), 5.42 (d, J ϭ 5.8 Hz, 2H), 5.57 (dt, J ϭ 5.8, 5.6 Hz, 1H).
13C NMR(CDCl3): δ ϭ 19.84 (s, CH3) 25.58 (d, JP-C ϭ 20.43 Hz, CH), 29.12
(s, CCH2), 29.72 (s, PhCH2), 71.72 (s, CH2O), 77.67, 85.20 (each s, CH),
2
2
87.94 (d, JP-C ϭ 5.8 Hz, CH), 111.89 (d, Cq, JP-C ϭ 7.2 Hz). 31P NMR
(CDCl3): δ ϭ 36.52 (s, PiPr3);.
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Z. Anorg. Allg. Chem. 2006, 400Ϫ408

Arene Half Sandwich Dichloro Ruthenium Complexes
[{η6-C6H5(CH2)3OCH3}Ru(PiPr3)Cl2] (2b): 0.20 g (0.31 mmol) of 1
was reacted with 237 µl (0.62 mmol) of PiPr3 in 8 ml of CH2Cl2.
The reaction mixture was stirred overnight at room temperature
and filtered via a paper-tipped cannula. The solvent was then re-
moved under vacuum and the dry residue was washed with 3ϫ4 ml
of Et2O. The solid was then vacuum dried to yield 254 mg of 2b
(85 %). Analysis calcd. for C19H35Cl2OPRu (482.4); C 47.34 (calc
47.30); H 7.30 (7.31) %. mpϭ117 °C.
1H-NMR (CDCl3): δ ϭ 1.29, 1.34 (each d, J ϭ 7.2 Hz, 9H, CH3(PiPr3)),
1.93 (tt, J ϭ 7.3, 6.2 Hz, 2H, CH2CH2CH2), 2.71 (t, J ϭ 7.3 Hz, 2H,
PhCH2), 2.82 (m, CH(PiPr3), 3H), 3.30 (s, 3H, OCH3), 3.47 (t, J ϭ 6.2 Hz,
2H, CH2O), 5.36 (t, J ϭ 5.4 Hz, 2H), 5.40 (d, J ϭ 5.0 Hz, 2H), 5.58 (dd,
J ϭ 5.4, 5.0 Hz, 1H). 13C NMR(CDCl3): δ ϭ 20.53 (s, CH3(PiPr3), 25.94 (d,
JP-C ϭ 20.5 Hz, CH(PiPr3), 29.52 (s, CH2), 30.16 (s, PhCH2), 58.86 (s,
OCH3), 72.15 (s, CH2O), 77.05, 87.89 (s, CH), 88.47 (d, 2JP-C ϭ 5.0 Hz,
CH), 112.39 (Cq). 31P NMR (CDCl3): δ ϭ 41.45 (s, PiPr3).
The single crystal structures of 1a and 2a were determined on a
Bruker-Nonius Kappa CCD diffractometer and solved and refined
with the program package SHELX-97 [35]. A numerical absorption
correction was carried out for both crystals with the program
HABITUS [37]. The packing plot of compound 1a was obtained
with the program MERCURY [38, 39]. Crystallographic data for
1a (CCDC 284428) and 2a (CCDC 284429) have been deposited at
the Cambridge Crystallographic Data Centre and can be obtained
free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax (ϩ44) 1223-336-033, or at
deposit@ccdc.cam.ac.uk.
Acknowledgement. We thank Dr. Rainer Ruf for his aid in the struc-
ture refinement. Financial support of this work by the Deutsche
Forschungsgemeinschaft (grant WI 1262/4-1) is gratefully acknowl-
edged.
[{C6H5(CH2)3OCH3)}Ru(PCy3)Cl2] (2c): Compound 2a (0.100 g,
0.150 mmol) and 0.103 g (0.31 mmol) of PCy3 were dissolved in
4 ml of CH2Cl2 and stirred overnight. The filtered solution was
dried under vacuum and the residue was washed with 3I>4ml of
Et2O and dried. Compound 2c was obtained as an orange brown
fluffy powder in a yield of 130 mg (72 %). Analysis calcd. for
C28H47Cl2OPRu (602.6); C 56.00 (calc 55.81); H 8.15 (7.86) %.
mp ϭ 234 °C.
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1H-NMR (CDCl3): δ ϭ 1.26 (m (br), 12 H), 1.41 (t, J ϭ 12.2 Hz, 3H), 1.76
(m (br), 9 H), 2.1 (m, 6 H), 2.42 (m, 3H), all CH2, CH (PCy3), 1.94 (tt, J ϭ
7.8, 6.4 Hz, 2H, CH2CH2CH2), 2.65 (t, J ϭ 7.8 Hz, 2H, PhCH2), 3.31 (s,
3H, OCH3), 3.45 (t, J ϭ 6.4 Hz, 2H, CH2O), 5.37 (m, 3H), 5.57 (m, 2H).
13C NMR(CDCl3): δ ϭ 26.8 (d, JPC ϭ 1.05 Hz, CH2), 27.9, 28.1 (s, CH2),
5
4
29.5 (d, JP-C ϭ 1.05 Hz, CH2), 30.2 (d, JP-C ϭ 2.1 Hz, PhCH2), 36.3 (d,
1JPC ϭ 18.9 Hz, CH(PCy3)), 58.65 (s, CH2O), 72.0 (s, OCH3), 77.45, 77.5,
85.6 (s, CH), 88.3 (d, JP-C ϭ 5.3 Hz, CH), 111.9 (d, JP-C ϭ 5.8 Hz, Cq).
31P NMR (CDCl3): δ ϭ 32.91 (s, PCy3).
2
2
[{η6-C6H5(CH2)2OH)}RuCl2] (3a): In
a typical run, 3.60 g
(29.03 mmol) of 2-(1,4-cyclohexadienyl)ethanol was reacted with
1.20 g (5.03 mmol) of RuCl3 in 20 ml of ethanol. The reaction mix-
ture was heated under reflux for 6h and the solution was left to
cool down overnight in a fridge. Ethanol was removed by cannula
filtration and the microcrystalline solid was recrystallized by slowly
cooling a hot solution in ethanol. After drying under vacuum,
1.09 g (73.7 %) were obtained as orange microcrystals. Analysis
calcd. for C8H10Cl2ORu (294.1); C 33.16 (calc 32.67); H 3.46
(3.43) %. mpϭ211 °C.
1H-NMR (dmf-d7): δ ϭ 2.57 (t, J ϭ 6.0 Hz, 2H, PhCH2), 3.70 (dt, J ϭ 6.0,
5.4 Hz, 2H, CH2O), 4.66 (t, J ϭ 5.4 Hz, 1H, OH), 5.46 (m, 3H), 5.61 (t, J ϭ
5.6 Hz, 2H); 1H-NMR (dmso-d6): δ ϭ 2.56 (t, J ϭ 6.1 Hz, 2H, CH2O), 3.66
(br, 2H, CH2O), 4.75 (br, 1H, OH), 5.76 (m, 3H), 5.96 (t, J ϭ 5.9 Hz, 2H);
13C NMR (dmf-d7): δ ϭ 37.0 (s, CH2), 61.0 (s, OCH2), 78.0, 80.9, 84.0
(each s, CH), 98.6 (Cq).
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[{η6-C6H5(CH2)2OH}Ru(PiPr3)Cl2] (3b): A suspension of 0.175 g
(0.59 mmol) of 3a in 7 ml of CH2Cl2 was treated with 112.5 µl
(0.59 mmol) of PiPr3. After stirring overnight, the reaction mixture
had turned into a brown solution. Small quantities of undissolved
material were removed by cannula filtration. The filtered solution
was dried in vacuo and the residue was washed with 3ϫ4 ml of
Et2O and vacuum dried. Compound 3b was obtained as a brown
solid in a yield of 220 mg (82 %). Analysis calcd. for C17H31Cl2O-
PRu (454.4); C 45.28 (calc 44.94); H 7.02 (6.88) %. mp ϭ 121 °C.
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1H-NMR (CD2Cl2): δ ϭ 1.29 and 1.36 (each d, J ϭ 7.2 Hz, 9H, CH3(PiPr3),
2.72 (m, 3H, CH(PiPr3)), 2.84 (t, J ϭ 5.7 Hz, 2H, PhCH2), 4.07 (t, J ϭ
5.7 Hz, 2H, CH2O), 5.31 (m, 3H), 5.76 (m, 2H). 13C NMR(CD2Cl2): δ ϭ
21.77 (d, 3JP-C ϭ 1.8 Hz, CH3(PiPr3)), 27.74 (d, JP-C ϭ 20.4 Hz, CH(PiPr3)),
2
31.51 (s, CCH2), 62.13 (s, CH2O), 80.12, 84.79 (s, CH), 92.31 (d, JP-C
ϭ
4.7 Hz, CH), 110.89 (Cq, JP-C ϭ 4.8. Hz). 31P NMR(CDCl3): δ ϭ 41.25
2
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1993, 12, 610.
(s, PiPr3).
Z. Anorg. Allg. Chem. 2006, 400Ϫ408
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