Cyclopentadienyl ruthenium(II) complexes with bridging alkynylphosphine ligands: Synthesis and electrochemical studies

Article abstract of DOI:10.1002/chem.200901642

The reaction of [CpRuCl-(PPh₃)₂] (Cp= cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph₂PCH₂CH ₂PPh₂) with bis-and trisphosphine ligands 1,4-(Ph ₂PC= C)₂C₆H₄ (1) and 1,3,5-(Ph ₂PC= C)₃C₆H₃ (2), prepared by Ni-catalysed cross-coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal-directed self-assembly methodologies, two linear bimetallic complexes,[{CpRuCl(PPh ₃)}₂(μ-dppab)] (3) and[{CpRu(dppe)}₂(μ- dppab)](PF₆)₂ (4), and the mononuclear complex [CpRuCl(PPh₃)(η¹-dppab)] (6), which contains a dangling arm ligand, were prepared (dppab=1,4-bis[(diphenylphosphino) ethynyl]benzene). Moreover, by using the triphosphine 1,3,5- tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl-(PPh₃)}₃(μ₃-tppab)] (5) species was synthesised, which is the first example of a chiral-at-ruthenium complex containing three different stereogenic centres. Besides these open-chain complexes, the neutral cyclic species [{CpRuCl(μdppab)}₂] (7) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2. Two rigid macrocycles based on cis coordination of dppab to [CpRu-(PPh ₃)] were obtained, that is, the dinuclear complex [{CpRu(PPh ₃)(mdppab)}₂](PF₆)₂ (8) and the tetranuclear square [{CpRu(PPh₃)(mdppab)}₃](PF ₃)₃ (9). The solid-state structures of 7 and 8 have been determined by X-ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X-band ESR spectroscopy in the case of the electrogenerated paramagnetic species.

Full text of DOI:10.1002/chem.200901642

FULL PAPER
DOI: 10.1002/chem.200901642
Cyclopentadienyl Ruthenium(II) Complexes with Bridging
Alkynylphosphine Ligands: Synthesis and Electrochemical Studies
Barbara Di Credico,[a] Fabrizia Fabrizi de Biani,[b] Luca Gonsalvi,[a] Annalisa Guerri,[c]
Andrea Ienco,[a] Franco Laschi,[b] Maurizio Peruzzini,*[a] Gianna Reginato,[a]
Andrea Rossin,[a] and Piero Zanello[b]
Dedicated to the Centenary of the Italian Chemical Society
Abstract: The reaction of [CpRuCl-
(PPh3)2] (Cp=cyclopentadienyl) and
[CpRuCl(dppe)] (dppe=
Ph2PCH2CH2PPh2) with bis- and tris-
phosphine ligands
1,4-(Ph2PCꢀ
over, by using the triphosphine 1,3,5-
tris[(diphenylphosphino)ethynyl]ben-
zene (tppab), the trimetallic [{CpRuCl-
tested by reaction of the bimetallic pre-
cursor 3 with additional equivalents of
ligand 2. Two rigid macrocycles based
on cis coordination of dppab to [CpRu-
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
ACHUNTGERN(NUG PPh3)}3ACHTUNGTNER(NUGN m3-tppab)] (5) species was syn-
thesised, which is the first example of a
chiral-at-ruthenium complex containing
three different stereogenic centres. Be-
sides these open-chain complexes, the
ACHTUNGTRENNUNG
C)2C6H4 (1) and 1,3,5-(Ph2PCꢀ
C)3C6H3 (2), prepared by Ni-catalysed
cross-coupling reactions between termi-
nal alkynes and diphenylchlorophos-
phine, has been investigated. Using
metal-directed self-assembly methodol-
ogies, two linear bimetallic complexes,
A
ACHTUNGTRENNUNG
dppab)}2]
ACHTUNGTRENNUNG
clear
N
ACHTUNGTRENNUNG
neutral cyclic species [{CpRuCl
N
dppab)}4]AHCTUNGTRENNNUG
dppab)}2] (7) was also obtained under
different experimental conditions. The
coordination chemistry of such systems
towards supramolecular assemblies was
structures of 7 and 8 have been deter-
mined by X-ray diffraction analysis and
show a different arrangement of the
two parallel dppab ligands. All com-
pounds were characterised by various
methods including ESIMS, electro-
chemistry and by X-band ESR spec-
troscopy in the case of the electrogen-
erated paramagnetic species.
[{CpRuCl
N
2ACHTUNGTRENNUNG(m-dppab)] (3) and
[{CpRu
and
[CpRuCl
G
G
E
(4),
Keywords: electrochemistry · phos-
phane ligands · polynuclear com-
plexes · ruthenium · X-ray diffrac-
tion
U
Introduction
The incorporation of metal atoms into supramolecular as-
semblies is considered to be an efficient pathway for the de-
velopment of new functional materials with novel physical
and chemical properties.
[a] Dipl.-Chem. B. Di Credico, Dr. L. Gonsalvi, Dr. A. Ienco,
Dr. M. Peruzzini, Dr. G. Reginato, Dr. A. Rossin
Istituto di Chimica dei Composti OrganoMetallici ICCOM
Consglio Nazionale delle ricerche CNR
In particular, transition-metal centres may introduce
Lewis acidity,[1] magnetism,[2] redox activity[3] or lumines-
cence[4] properties into metallopolymers and macrocyclic
structures. The synthesis of metallomacrocycles represents
an interesting area to explore the development of “host–
guest” chemistry. These species contain large cavities that
can be occupied by small guest molecules that can in turn
modify the chemical properties and reactivity of the host
molecule. Furthermore, macrocyclic molecular squares, rec-
tangles or boxes have been prepared for applications in
via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence (Italy)
Fax : (+39)055-5225203
E-mail: m.peruzzini@iccom.cnr.it
[b] Dr. F. Fabrizi de Biani, Prof. Dr. F. Laschi, Prof. Dr. P. Zanello
Dipartimento di Chimica, Universitꢀ degli Studi di Siena
via A. De Gasperi 2, 53100, Siena (Italy)
[c] Dr. A. Guerri
Dipartimento di Chimica, Universitꢀ degli Studi di Firenze
via della Lastruccia 3, 50019, Sesto Fiorentino, Florence (Italy)
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areas such as molecular recognition, sensing and modelling
for biological systems.[5]
The dppab and tppab rigid ligands are significantly more
functionalised than those that contain merely acetylene as a
spacer (like dppa, diphenylphosphinoacetylene),[11] which
could help to spontaneously assemble large macrocyclic sys-
tems instead of discrete complexes. In addition, the presence
of CꢀC triple bonds conjugated with an aromatic ring
could favour an effective electronic communication between
the different metal centres held together by the alkynylphos-
phino bridge. Using metal-directed self-assembly methodol-
Ligands containing two or more metal-binding phospho-
rus donor atoms are versatile building blocks for the con-
struction of linear or cross-linked complexes by self-assem-
bly of ditopic or multitopic units with metal ions.[6] Although
the use of alkenyl and alkynylphosphines has precedents in
the coordination chemistry of a wide range of transition
metals,[7,8] ruthenium(II) complexes bearing these ligands
are rare.[9] Remarkably, the only complex containing a di-
phosphinoalkyne ligand is Dysonꢂs compound [{(p-
ogies, two linear bimetallic complexes, [{CpRuCl
dppab)] (3) and [{CpRu(dppe)}2A(m-dppab)](PF6)2 (4), and
the trimetallic [{CpRuCl(PPh3)}3A(m3-tppab)] (5) species
ACHUTNGTREN(NUG PPh3)}2ACHTUNGTRENNUNG(m-
A
N
ACHTUNGTRENNUNG
cymene)RuCl2}
N
A
CHTUNGTRENNUNG
noacetylene).[10] With the aim of expanding on this theme
and these architectures, we report here results on the syn-
thesis and structural characterisation of a family of cyclo-
pentadienyl ruthenium(II) (CpRu) complexes with the bi-
and tridentate phosphines 1,4-bis[(diphenylphosphino)eth-
(dppe=1,2-bis(diphenylphosphino)ethane) were prepared
and fully characterised. Moreover, the mononuclear com-
(h1-dppab)] (6) that contains a “dan-
plex [CpRuClACHTNUTRGENN(GU PPh3)ACHTUNGTRENNUGN
gling” diphosphine arm was synthesised, thereby showing
that ligand 1 may exhibit either m-h2- (end-on) or h1-coordi-
nation modes. Besides these open-chain complexes, the neu-
ACHTUNGTRENNUNG
A
tral cyclic species [{CpRuClACTHUNGTRENNU(G m-dppab)}2] (7) was also ob-
tained under different experimental conditions. Finally, the
pre-assembled metal-based mono- and dinuclear moieties
mentioned above were used as starting materials to prepare
metallomacrocycles of diverse shapes and sizes. Thus, self-
assembly of the dimetal precursor 3 with additional equiva-
lents of dppab led to an approximately 1:1 mixture of the
cyclic dimer [{CpRu
tetramer [{CpRu(PPh3)
macrocycles based on cis ligation of the {CpRuACHTUNGTRENNUNG
A
R
ACHTUGNTREN(UNNG PF6)2 (8) and the
A
R
ACHTUNGTRENNUNG
moiety belong to the growing family of polynuclear com-
pounds with potential applications in host–guest, inclusion,
and molecular recognition chemistry.[12] Apart from elemen-
tal analysis, routine chemico-physical characterisation (mul-
tinuclear NMR and FTIR spectroscopy) and single-crystal
X-ray diffraction data collection on selected complexes, all
of the compounds were analysed through ESIMS, electro-
chemical methods and, for the electrogenerated paramag-
netic species, by X-band ESR spectroscopy.
Results and Discussion
Synthesis and characterisation
of the alkynylphosphine li-
gands: Although ligands 1[13]
and 2[8] have been already de-
scribed, we report here on a
new synthetic pathway that
does not request the use of
highly reactive sodium, lithium
or magnesium ethynyl reagents
and also provides better yields
of both alkynylphosphines.
Thus, dppab (1) and tppab (2)
were prepared from the corre-
sponding terminal alkynes by a
Ni-catalyzed cross-coupling re-
action with chlorodiphenyl-
Scheme 1. Synthesis of the bidentate and tridentate ligands dppab 1 and tppab 2.
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Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
phosphine in the presence of NEt3 (Scheme 1). The Sonoga-
shira reaction of aryl bromides with trimethylsilyl acetylene
is used to prepare the terminal alkyne, after hydrolysis of
the SiMe3 protecting groups. The use of halophosphines
R2PX[14] represents a synthetic approach, based on an umpo-
lung process alternative to the literature methods, for exam-
stable, and can be handled in air without special precautions,
although they are better stored under nitrogen. The ob-
served stability towards air oxidation made column chroma-
tographic techniques suitable for the final purification of the
neutral CpRu derivatives, which could therefore be obtained
as analytically pure microcrystalline materials (see the Ex-
perimental Section). Phosphine exchange at the metal
centre in precursor 10 or halide abstraction using TlPF6 in
the presence of an additional ligand were the methodologies
used to prepare the RuII complexes. The reaction tempera-
ture and the metal-to-ligand molar ratio were the most im-
portant factors to influence the reaction outcome, hence the
nature of the obtained products.
In a first experiment aimed at preparing coordination
complexes that exploited both donor ends of the biphos-
phine 1, a 2:1 M/L ratio was employed and the reaction was
carried out at 608C in toluene. The reaction resulted in the
immediate formation (31P{1H} NMR spectroscopic monitor-
ing) of the bimetallic complex 3, which could be isolated
and purified in excellent yield as an orange microcrystalline
powder after chromatographic workup (Scheme 2). Remark-
ably, both Ru centres in 3 are stereogenic due to the pres-
ence of four different substituents on a distorted piano-
stool-coordinated polyhedron. In keeping with such stereo-
chemical arrangement, the 31P{1H} NMR spectrum of 3
shows two pairs of 1:1 doublets.[18] Correspondingly, two dis-
tinct and partially overlapped peaks can be observed in the
Cp region of the 1H NMR spectrum, thus confirming the for-
mation of a pair of enantiomers (RRu,RRu and SRu,SRu) to-
gether with the meso form (RRu,SRu and SRu,RRu). When a
solution of 3 in [D3]acetonitrile was warmed to 808C (NMR
spectroscopy tube test), no significant change in the intensi-
ꢁ
ple, the reaction of secondary phosphine R2PH with R X
substrates including halogenated alkynes.[15]
The classical synthesis of alkynylphosphines often involves
ꢁ
direct lithiation of the terminal CꢀC H bond, followed by
reaction of the in situ generated acetylide carbanion with
R2PX.[8,16] Although the latter preparative methodology was
also used in this work, the yields of the alkynylphosphines
were always significantly lower, so our alternative method
was preferred.
Synthesis and characterisation of neutral ruthenium com-
plexes with dppab: To explore the coordination properties
of these alkynylphosphines towards transition metals, we in-
vestigated the reactivity of both 1 and 2 with a variety of
RuII precursors. The easy-to-make, readily available and
stable RuII complex [CpRuCl
results. Several attempts were made also using other RuII
precursors such as [CpRu
(h6-C10H8)](PF6), [{(h6-p-cyme-
ne)RuCl2}2] and [Ru(PPh3)3Cl2]. Irrespective of the precur-
(PPh3)2] (10)[17] gave the best
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
sor used, mixtures of several products were formed, and nei-
ther simple 31P NMR identification nor isolation of pure
products after workup was possible. Thus, the reactivity of
both 1 and 2 with these RuII precursors was not investigated
further.
As a general consideration, the ruthenium complexes of
the polyphosphines here described are moderately air-
Scheme 2. Synthesis of dppab complexes 3, 6 and 7. The related 31P{1H} NMR spectroscopic signals are shown on the right side of the scheme.
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11987

M. Peruzzini et al.
ty ratio of the two pairs of doublets was observed, thereby
proving the absence of any dynamic process that could have
been expected from a pair of equilibrating rotamers. The si-
multaneous presence of two stereogenic metal atoms in a bi-
metallic complex is quite rare;[19,20] chiral (carbon) centres
are normally located on the ligands. Resolution of the dia-
stereomeric mixture by means of the chromatographic tech-
niques was impossible, due to the almost identical Rf values
of the diastereoisomers (dichloromethane/acetone 20:1).
The reaction was repeated using an M/L ratio of 1:2. In
this case, an equilibrium mixture between the species 6, 3
and 1 was observed. Among these products, complex 6,
which contained a dangling, uncoordinated diphosphine
arm, was the main product in the reaction crude. The overall
low yield of isolated 6 after workup (22%) likely reflects its
participation in a room temperature equilibrium, thereby
giving the bridged species 3 through dppab dissociation fol-
lowed by reaction of the coordinatively unsaturated
product. Complex 7 is likely to form through intermolecular
thermal replacement of the triphenylphosphine ligand in 6
by the pending P donor atom of a second equivalent of the
same ruthenium complex. Due to the presence of identical
phosphine ligands, no chirality at Ru was observed, which is
in line with the presence of a singlet resonance in the
31P{1H} NMR spectrum (d=18.67 ppm). Complex 7 belongs
to the known family of diruthenium complexes in which two
{CpRuL} moieties (L=s-donor ligand) are held together by
a pair of bidentate ligands.[20,21]
Synthesis and characterisation of cationic ruthenium com-
plexes of dppab: Removal of the chloride ligand in
{CpRuCl} species during the reaction with dppab could
easily favour the formation of either dinuclear cationic com-
plexes or macrocyclic species depending on the nature of
the ruthenium precursor and the stoichiometric ratio. This
possibility was firstly explored by using the precursor
{CpRuCl
G
a
second equivalent of
6
[CpRuClACTHNGUTER(NNUG dppe)] (11), which contains the chelating ancillary
(Scheme 3).
the
ligand redistribution
diphosphine 1,2-diphenylphosphinoethane (dppe) instead of
two monodentate phosphines such as PPh3. Using TlPF6 in
CH2Cl2/MeOH at ambient temperature as effective halide
scavenger on a 2:1 M/L solution afforded as expected the
bridged product 4 in quantitative NMR spectroscopic yield
(Scheme 4). Complex 4 shares with 3 the main structural
(6)+(6)Q(1)+(3) in solution did not permit the collection of
exhaustive ESIMS data for 6. The process can be followed
by 31P{1H} NMR spectroscopy, which shows that as the sig-
nals belonging to 6 decrease, those ascribable to free 1 and
complex 3 grow in parallel. A similar behaviour was also re-
cently observed by Dyson et al. for the RuII complex [(h6-p-
motif in which two {CpRuACTHUNGTRENNG(U dppe)} cations are held together
cymene)RuCl
(h1-dppa)], which also contains a bridging bi-
by a bridging dppab ligand. The most intriguing difference
between the two complexes is, apart from the cationic
versus neutral nature, the lack of stereogenicity at the metal
centres due to the presence of dppe chelating ligands.
dentate phosphine.[10]
A solution of a 1:2 ratio between [CpRuACHTNURTGNEUNG(PPh3)2Cl] and 1
in toluene heated at reflux did not yield 6, but rather gave
the diruthenamacrocycle 7 as a single stable thermodynamic
Scheme 3. Proposed mechanism for the (6)+(6)Q(1)+(3) reaction.
Scheme 4. Synthesis of the dinuclear complex 4. The related 31P{1H} NMR spectroscopic signals are shown on the right side of the scheme.
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Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
As 3 does not contain the sterically forcing dppe chelate,
addition of TlPF6 to a solution of 3 in the presence of an ad-
ditional equivalent of dppab is an efficient way to grow
polynuclear macrocyclic complexes featuring a 1:1 M/L
ratio. Thus, removal of the chloride ligand from a solution
of 3 in dichloromethane with TlPF6 did not provide any de-
fined product unless the reaction was carried out in the
presence of dppab. Workup of the solution after filtering out
TlCl gave a dark orange powder consisting of an approxi-
mate 1:1 mixture of complexes 8 and 9, which were assigned
as dinuclear [M2L2]2+ and tetranuclear [M4L4]4+ species
(Scheme 5).
formulas were unambiguously confirmed by a combination
of chemico-physical data including elemental analysis, molar
conductivity in solution, mass spectral and multinuclear
NMR spectroscopy. Particularly significant was the
31P{1H} NMR spectrum showing two practically superim-
posed AM2 spin systems, which provide confirmatory evi-
dence for the coordination of two different dppab ligands to
each {CpRuACTHNUGTRENUNG(PPh3)} moiety (top trace in Figure 1). Thus,
while 8 showed a high-frequency triplet (dP =38.95 ppm)
and a lower frequency doublet (dP =20.26 ppm) with 2J-
AHCTUNGTRENNUNG
The formation of discrete macrocycles of formula
ACHTUNGTRENNUNG
[cyclo-
A
C
posed structures (Scheme 5).
oured with respect to open-chain metallorganic polymers
To assess the dimeric versus tetrameric nature of 8 and 9,
respectively, the high-resolution ESIMS spectra of the two
complexes were of importance. In particular, 9 exhibits an
[Mꢁ2PF6]2+ signal at m/z 1991.3; its experimental isotopic
{CpRuACHTUNGTRENNUNG
(PPh3)(m,h1:1-dppab)}1 may be due to enthalpic ef-
fects.[22,23] In turn, entropic factors would favour the forma-
tion of small cycles over larger ones.[23] However, in the case
at hand, the observed 1:1 ratio
between 8 and 9 may find its
explanation in the rigidity of
dppab and the nearly 908 L-
Ru-L bond angle (95.538 for 8,
see below), which would lead
to the thermodynamically most
stable square arrangement fea-
tured by 9. A similar behav-
iour has been documented by
Rheingold and co-workers for
a family of Re–Pd polymetal-
lamacrocycles.[12] Complexes 8
and 9 were separated by frac-
tional crystallisation from a di-
luted
dichloromethane/n-
hexane solution from which
analytically pure samples of 8
and 9 were obtained as dark
orange and yellow microcrys-
tals, respectively. The proposed
Figure 1. 31P{1H} NMR (CD2Cl2) spectrum of the crude reaction mixture 6/TlPF6/dppab consisting of 8 and 9
(top) and the AM2 patterns due to the isolated complexes (8, middle; 9, bottom).
Scheme 5. Synthesis of complexes 8 and 9.
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11989

M. Peruzzini et al.
pattern matches the calculated values well (Figure 2), thus
validating the tetranuclear nature of this interesting ruthena-
macrocycle.
To explore the stability of the polymetallic species 8 and 9
and, most importantly, to verify whether any equilibration
Crystallographic studies: To verify whether the proposed
solution structures are confirmed in the solid state and also
to obtain crystallographic information on this class of com-
pounds, single crystals of 7 and 8 were grown by slow evapo-
ration of a diluted C2H4Cl2/EtOH solution. Selected bond
lengths and angles for 7 and 8 are provided in Table 1,
whereas Table 5 (see the Experimental Section) summarises
the main crystallographic data and parameters.
could account for the interconversion of
31P{1H} NMR spectra in CD3CN were recorded at different
temperatures. Thus, warming solution of in
9 into 8,
a
8
[D3]acetonitrile to 808C did not show any transformation
suggesting that 9 does not originate from the intermolecular
aggregation of two dinuclear dications 8. Similarly, the
31P{1H} NMR spectrum of a solution of tetramer 9 in
CD3CN does not change on increasing the temperature
from 20 to 808C. These results are mechanistically relevant
because they suggest that the two compounds do not take
part in equilibria, hence they should be generated through
different reaction pathways. Remarkably, this behaviour
contrasts with the results reported by Navarro and co-work-
ers for related cyclic ruthenium(II) complexes [(h6-p-cyme-
As shown in Figure 3, whereas the asymmetric unit of 7
consists of a single molecule without clathrated solvent mol-
Table 1. Selected bond lengths [ꢃ] and angles [8] for the dinuclear
species 7 and 8.
7
8
ꢁ
ꢁ
Ru1 P1
2.284(4)
2.309(4)
2.420(5)
2.293(5)
2.270(5)
2.444(4)
93.98(14)
92.2(2)
96.48(16)
93.65(18)
95.57(15)
91.63(17)
Ru1 P1
2.325(2)
2.333(2)
2.3595(19)
ꢁ
ꢁ
Ru1 P2
Ru1 P3
ꢁ
ꢁ
Ru1 Cl1
Ru1 P2
ꢁ
Ru2 P3
ne)4Ru4(m-4,7-phen-N4,N7)
ing phenanthroline ligand.[24]
Addition of TlPF6 to the orange solution containing
{[CpRuCl(PPh3)]2A(m-dppab)} and the excess of free dppab in
2ACHTUNGTREN(UNG m-OH)4]AHCUTNGTREN(NUNG NO3)4 bearing a bridg-
ꢁ
Ru2 P4
ꢁ
Ru2 Cl2
P1-Ru1-P2
P1-Ru1-Cl1
P2-Ru1-Cl1
P3-Ru2-P4
P3-Ru2-Cl2
P4-Ru2-Cl2
P1-Ru1-P3
P1-Ru1-P2
P3-Ru1-P2
95.44(7)
96.98(7)
94.59(7)
A
CHTUNGTRENNUNG
CH2Cl2 led to immediate precipitation of the white TlCl
powder. After two hours, the decanted supernatant becomes
reddish, assuming a fluorescent aspect.
Figure 2. Selected region of the a),b) calculated and c) experimental ESIMS spectra of a solution of 8 and 9 (ca. 1:1 ratio by 31P{1H} NMR spectroscopy)
and showing the [MꢁPF6]+ peak at m/z 1991.3 of the dimetallic complex
tetraruthenamacrocycle 9.
8
and the [Mꢁ2PF6]2+ peak at m/z 1991.3 of the
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Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
Dimer 7 (see Figure 3) exhibits a helical arrangement
with the two dppab ligands rolled up and slightly stretched;
the bridging phenyl rings almost lie one over the other. In
dimer 8, the dppab ligands are parallel to each other, and
the bridging phenyl rings are slightly slipped. The same con-
formation was found in the platinum and palladium
dimers.[25] Moreover, the two chloride ligands in 7 are mutu-
ally rotated (Cl1-Ru1-Ru2-Cl2=ꢁ60.7(6)8), whereas in 8
the two terminal PPh3 ligands are related by an inversion
centre. The overall conformation of 7 is close to that found
in [{Cp*2Mo2ACTHNUTRGNEUNG
(dppdfb)}2][26] (Cp*=h5-C5Me; dppdfb=m2-1,4-
Figure 3. Ball-and-stick diagrams of dimer 7 (top) and 8 (bottom). Two
views are shown. On the left, the molecules are perpendicular to the ben-
zene rings of the dppab ligands to show p–p stacking. On the right, the
complexes are viewed along the metal–metal line. The hydrogen atoms,
the carbon atoms of the PPh3 ligand (except for the Cipso), the PF6 anion
and the 1,2 dichloroethane solvent molecules are omitted for clarity.
bis(diphenylphosphino)-2,5-difluorobenzene) with a separa-
tion between the aryl centroids of 3.604 ꢃ and a similarly
rolled-up disposition of the bridging ligands. The different
structures adopted by 7 and 8 is likely due to external supra-
molecular forces rather than the ligand conformation.[27]
Coordination chemistry of tppab towards [CpRuClACHTUNGTRENNUNG(PPh3)2]:
ecules, that of 8 consists of half of the dinuclear dicationic
The coordination chemistry of the tridentate ligand tppab
towards {CpRu} fragments was also briefly investigated.
Under the reaction conditions described above, tppab gave
the trimetallic species 5 upon reaction of 10 with 2 in a 3:1
M/L ratio in toluene at 608C.
dimer of [{CpRu
N
ꢁ
PF6 anion and four 1,2-dichloroethane solvent molecules.
In both compounds each ruthenium atom is octahedrally co-
ordinated by two phosphorus atoms belonging to two differ-
ent dppab ligands in the cis position, by the Cp ring in a h5
fashion, thus occupying three contiguous coordination sites,
and by a chlorine atom (7) or a triphenylphosphine ligand
(8), respectively. In the neutral complex 7 the ruthenium
atoms Ru1 and Ru2 are kept apart by two bridging dppab li-
gands with a separation between the two metals of 12.74 ꢃ.
The 31P{1H} NMR spectrum of 5 disclosed three sets of
AM patterns (Scheme 6), which do not correspond to the
(two) expected sets of signals deriving from a symmetric
system containing a C3 axis. This can be explained by the
presence of two non-equivalent ligand dispositions around
the Ru centres, with concomitant loss of the C3 symmetry. If
the two stereochemically different Ru atoms are present in
a 2:1 ratio, the resulting complex still possesses a symmetry
plane, giving three sets of signals on the 31P NMR spectrum
(two diastereoisomers and a meso form). To the best of our
knowledge, complex 5 is the first example of a ruthenium
complex containing three different stereogenic centres with
chirality on the metal atom. Although examples of chiral tri-
nuclear metal complexes are known, the chirality in those
systems is usually associated with the presence of chiral or
atropisomeric ligands.[28]
ꢁ
This distance is shorter than the Ru1 Ru1’ distance of
14.83 ꢃ in 8. Although no related diruthenium compound
has been crystallographically authenticated, the intermetallic
distance in 7 is comparable to the metal–metal separation
found by Manners and co-workers in the related square-
planar dipalladium derivatives [{PdI
ACHTUNGTRENNUNG
2ACHTUNGTREN(UNGN dppab)}2] and [{PtI2-
(dppab)}2] (11.66 and 11.67 ꢃ, respectively).[25]
ꢁ
In the diruthenium dication 8, the Ru PACTHNURGTNEUNG(PPh3) bond
ꢁ
length (Ru1 P2=2.3595(19) ꢃ) is slightly longer than the
ꢁ
Ru P
ꢁ
ꢁ
(dppab) bond lengths (Ru1 P1=2.325(2), Ru1 P3=
2.333(2) ꢃ). These latter distances are longer than those
ꢁ
ꢁ
found in the neutral dimer 7 (Ru1 P1=2.284(4), Ru1 P2=
Electrochemistry and spectroelectrochemistry: The chloro
complexes 10 (mononuclear), 3 and 7 (dinuclear) and 5 (tri-
nuclear) display a substantially similar redox profile in cyclic
voltammetry. As a representative example, Figure 4 shows
the cyclic voltammetric behaviour of a solution of 3 in di-
chloromethane.
The dinuclear complex undergoes an oxidation process at
E8’=+0.52 V, which features chemical and electrochemical
reversibility in the time scale of cyclic voltammetry. This
first oxidation step is then followed by a further irreversible
oxidation almost overlapping the solvent discharge. An irre-
versible reduction is also present at very negative potential
values. Controlled potential coulometry in correspondence
to the first anodic process (working potential, Ew =+0.9 V)
showed the consumption of two electrons per molecule. As
a consequence of the exhaustive oxidation, the original
yellow solution turns reddish orange and the resulting solu-
ꢁ
ꢁ
2.309(4), Ru2 P3=2.293(5) and Ru2 P4=2.270(5) ꢃ),
likely reflecting the presence of two positive charges on the
ꢁ
bimetallic moiety. Similarly, the Ru Cpcentroid separations are
shorter in 7 (1.863(2), 1.865(2) ꢃ) than in 8 (1.881(3) ꢃ).
The overall shape of the two bimetallic complexes 7 and 8
can be easily compared by looking at Figure 3. Two views,
one perpendicular to the central benzene rings and one
along the metal–metal direction, are shown.
The central benzene rings of the two dppab molecules are
perfectly stacked in an eclipsed conformation in 7, whereas
in 8 they are staggered. The separation between the arene
centroids is 3.629(3) ꢃ in 7 and 3.398(2) ꢃ in 8. In the struc-
turally related Pd and Pt dimers reported by Manners,
[{PdI2ACHTUNGTRENNUNG(dppab)}2] and [{PtI2HCATUNGTNER(NUGN dppab)}2], the phenyl rings of the
dppab ligands are largely apart from each other (5.814 and
5.772 ꢃ, respectively).
Chem. Eur. J. 2009, 15, 11985 – 11998
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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11991

M. Peruzzini et al.
Scheme 6. Synthesis of complex 5. The related 31P{1H} NMR spectroscopic signals are shown on the right side of the scheme.
Table 2. Formal electrode potentials (V vs. SCE) and peak-to-peak sepa-
rations [mV] for the redox changes exhibited by selected dppab and
tppab ruthenium complexes in CH2Cl2.
Oxidation processes
Reduction process
Ep
[a,b]
[b]
[a,b]
Ep
E8’
DEp
1
10
3
7
5
+1.4
+1.5
+1.4
+1.5
+1.4
+1.5
–
–
110
80
80
85
–
–
+0.48
+0.52[c]
+0.50[c]
+0.57[d]
+0.50[c]
ꢁ2.0
ꢁ2.0
ꢁ2.0
ꢁ1.7
8
100
[a] Peak potential value for irreversible processes. [b] Measured at
0.2 Vsꢁ1. [c] Two-electron process. [d] Three-electron process.
Figure 4. Cyclic voltammogram recorded at a platinum electrode in a so-
lution of 3 in CH2Cl2 (0.8ꢄ10ꢁ3 moldmꢁ3). [NBu4][PF6] (0.2 moldmꢁ3
supporting electrolyte. Scan rate 0.2 Vsꢁ1
G
)
ꢁ
ed complex [(h5-ind)RuCl
N
.
gives evidence that the electrogenerated 19-electron species
is unstable and that the chloride atom is rapidly decoordi-
nated.[31] Thus, we reasoned that a similar decoordination
could take place also in the present case. Finally, a compari-
son with the redox behaviour of the free dppab ligand 1 sug-
gests that the mentioned irreversible oxidation can be con-
ceivably ascribed to this latter species.
Replacement of the chloride ligand by a PPh3 unit to
afford complexes 8 and 9 causes severe electrode-poisoning
effects in the corresponding electrochemical investigation.
Nevertheless, sufficiently defined cyclic voltammograms of 8
have been obtained at a gold electrode and its redox poten-
tial values could be assessed. As reported in Table 1, also in
this case both the RuII/RuIII electrochemical process and the
dppab oxidation appear unaltered with respect to the Cl-
containing analogue 7, whereas the cathodic process moves
to a less negative value. The need for repeated electrode
cleaning after each cycle prevented further measurements
on this compound.
tion displays a cyclic voltammetric response quite comple-
mentary to the original one, thus confirming the complete
stability of the dication 32+ also over the long times of mac-
roelectrolysis.
As anticipated, the mononuclear 10, dinuclear 7 and tri-
nuclear 5 compounds display a qualitative similar redox be-
haviour that results in the electrogeneration of stable cations
10+, 72+ and 53+
.
The electrode potentials of the pertinent redox changes
are summarised in Table 2. Both first oxidation and reduc-
tion steps can be considered metal-based processes. This is
also supported by a comparison with the redox behaviour of
the benzene ruthenium complexes [(C6H6)RuCl2ACTHNUTRGNEUNG
(PR3)].[29]
Since the oxidation of the two or three RuII centres pres-
ent in 3, 7 and 5, respectively, occurs in a single step, we can
preliminarily assign the respective mixed-valent cations to
the charge-localised Robin–Day class I.[30] As will be illus-
trated below, the spectroelectrochemical experiments are in
agreement with such an assignment.
Because of the electrode poisoning, no reliable cyclic vol-
tammogram of the tetramer 9 could be obtained at gold or
platinum electrodes, but for the constant appearance of
severe adsorption processes around ꢁ0.5 V. Due to this fact,
As far as the irreversible reduction of 3, 7 and 5 is con-
cerned, we note that a recent study performed on the relat-
11992
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Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
we decided to use an ITO working electrode, which offers a
much larger electrode area (cm2 versus mm2) and, as illus-
trated in Figure 5, the growth of a film was recorded.
Irrespective of the investigated species, a general pattern
is observed: the spectrum of the neutral complexes is domi-
nated by an intense band in the high-energy region, which
can be reasonably ascribed to a metal-to-ligand charge
transfer. This band is slightly affected by the oxidation in
that, in the spectrum of the cations, two new bands appear
at 532–550 (weak) and at 1116–1250 nm (very weak), which
can be both ascribed to a RuIII d–d electron transfer. In
agreement with the electrochemical results, the UV/Vis
spectra of the Cl-containing compounds are also very similar
to the mononuclear parent complex 10, which is in line with
the spectral changes observed throughout the oxidation. Re-
markably, the spectra of the bi- and trinuclear compounds
change monotonically along with the subsequent electron
removals. This would support the localised nature of the
mixed-valent species. Moreover, no IT band has been de-
tected in the experimental window (low-energy limit=
3300 nm).
Figure 5. Electrodeposition of a film at an ITO electrode in a solution of
ACTHNUTRGNEUNG
9 in CH2Cl2 (0.1ꢄ10ꢁ3 moldmꢁ3). [NBu4][PF6] (0.2 moldmꢁ3) supporting
In view of the chemical stability of the different electro-
generated cations, we decided to study their magnetic prop-
erties by EPR analysis. Since, as discussed above, the differ-
ent complexes undergo oxidation processes involving a dif-
ferent number of electrons per molecule, in all cases we
drew the electrogenerated species after the removal of
about 0.7 electrons per molecule.
electrolyte. Scan rate 0.05 Vsꢁ1. (a) Return profile of the first cycle. *
Starting potential.
The observed electrochemical processes show only a
minor correspondence with the parent dinuclear compound
8: in fact, there is an oxidation process with features of elec-
trochemical
quasi-reversibility
(Epa =+0.38 V,
Epc =
In agreement with the expected low-spin RuIII species, the
absorption pattern is typical of one-electron paramagnetic
species, with magnetic features (gi, ai, DHi) characterised by
large anisotropies.[32,33] The computed lineshape analysis[34]
can be suitably carried out assuming the following S=1/2
electron spin Hamiltonian H=bHgS+SiIiaiS, which accounts
for the actual well-resolved rhombic spectral symmetry
(bHgS=electron spin Zeeman interaction between the un-
paired electron and the applied magnetic field, H (b=Bohr
magneton, g=g factor, S=spin); SiIiaiS=superhyperfine
coupling Hamiltonian (shpf) relevant to the sum of the mag-
netic interactions of the unpaired electron with the different
magnetically active nuclei present in the ligand framework
(I=nuclear spin, ai =hyperfine splitting)).[32] Figure 6 shows
the frozen solution spectra (CH2Cl2; T=104 K) of complex
7 after controlled-potential one-electron removal.
On the basis of the multiple derivative approach carried
out on the experimental spectra and on performing the re-
lated computer simulation,[34] there is no evidence for hyper-
fine (hpf) features arising from the naturally occurring 99Ru
(I=5/2, natural abundance=12.8%) and 101Ru (I=5/2, nat-
ural abundance=19.0%).[32,33] Such a spectral behaviour is
not unusual for glassy solutions of low-spin RuIII com-
pounds, in that they exhibit broad and poorly resolved (first
derivative) rhombic lineshapes due to the very low ligand
field symmetries experienced by the paramagnetic metal
centres.[32] As a matter of fact, the spread of the hpf signals
of the two magnetically active 99Ru and 101Ru nuclei (if
any), joined to the effective unpaired electron delocalisation
on the ligand framework, does not favour a significant spec-
tral resolution (three largely overlapping anisotropic sextu-
plets would be expected for the two isotopes of each ruthe-
ꢁ0.23 V), which could correspond to the RuII/RuIII redox
change, whereas the reduction at ꢁ1.4 V, which triggers the
film deposition, corresponds to an unidentified redox pro-
cess. It is rather common that 19-electron organometallic
centres undergo structural reorganisation as a consequence
of the loss of one ligand,[31] therefore the nature of the film
is still unknown and will be the subject of future work.
The spectroelectrochemical analysis in an optically trans-
parent thin-layer electrode (OTTLE) cell allowed us to fur-
ther confirm the valence-localised nature of the mixed-
valent species involved in the electron-transfer processes of
3, 7 and 5. Our efforts were directed mainly towards check-
ing for the appearance of an intervalence transition (IT)
band that would eventually contrast the Robin–Day classifi-
cation suggested by cyclic voltammetry. All the UV/Vis
spectral data pertaining to the studied complexes are shown
in Table 3.
Table 3. Electronic spectral data for complexes 10, 3, 7, 5 and their elec-
trogenerated cations. OTTLE cell, THF/
solution.
[PF6] (0.2 moldmꢁ3
ACHTUNGETRN[NUNG NBu4]ACHTUNGRTENNUNG )
l [nm]
354, 440[a]
345, 383, 532, 1250
371
388, 550, 1183
355
378, 535, 1116
361
388, 540, 1170
10
10+
3
32+
7
72+
5
53+
[a] Shoulder.
Chem. Eur. J. 2009, 15, 11985 – 11998
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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11993

M. Peruzzini et al.
Table 4. X-band EPR spectra of the studied ruthenium complexes (in
CH2Cl2) after one-electron removal, recorded at liquid-nitrogen tempera-
ture (T=104 K).[a]
gl
gm
gh
<g> dglꢁh al
am ah
<a> meff
10 2.388 2.120 1.949 2.152 0.439 ꢂ29 32 ꢂ35 ꢂ32
1.86
1.86
1.85
1.86
3
7
5
2.342 2.124 1.968 2.145 0.374 ꢂ27 27 ꢂ29 ꢂ29
2.302 2.117 1.975 2.131 0.327 ꢂ27 34 ꢂ36 ꢂ32
2.349 2.113 1.963 2.142 0.386 ꢂ28 25 ꢂ31 ꢂ28
[a] gi: ꢃ0.008; ai: ꢃ1 G; meff: ꢃ0.01; <g>=1/3
ACHTNUGTNER(UNGN gl+gm+gm); <a>=1/3-
(al+am+am); l=low field, m=medium field, h=high field; dglꢁh =gꢁgh.
G
For the cations [3]+, [7]+ and [6]+ the ai values refer to mean shpf values
(2 nearly magnetically equivalent 31P).
it does so with some loss of intensity, which is likely due to
the slight instability of the complex upon contact with air.
Such a spectral behaviour holds for all the tested para-
magnetic species. On the basis of the anisotropic gi features
Figure 6. The liquid nitrogen X-band spectrum of 7 after the removal of
one electron, in frozen CH2Cl2: a) experimental first-derivative spectrum,
b) experimental second-derivative spectrum, c) and d) simulated first-
and second-derivative spectra, respectively.
and related aiACTHNUTRGNEUNG
(31P) couplings, the actual singly occupied mo-
lecular orbital (SOMO) is expected to be mainly constituted
by the 4d RuIII orbitals with important contributions arising
from the 3s and 3p orbitals of the two coordinating P
atoms.[32]
In conclusion, in spite of the different molecular struc-
tures of the electrogenerated cations, the X-band multiple
derivative approach performed under glassy conditions gives
evidence to: 1) the presence of identical rhombic spectral
symmetries as supported by similar dglꢁh parameters; 2) the
significant Ru/31P magnetic interactions in the gm and gh re-
gions; and 3) the absence of detectable Ru/35Cl and Ru/37Cl
magnetic interactions. In keeping with this evidence, the re-
lated meff parameters are nearly identical and significantly
higher than the spin-only value (meff =1.73 mB), as expected
in the presence of effective nd metal orbital contributions.
nium centre).[32,33] Thus, no evidence for magnetic coupling
of the unpaired electron with the two naturally occurring
35Cl (I=3/2, natural abundance=75.4%) and 37Cl (I=3/2,
natural abundance=24.6%) was detected.
The appearance of the three well-separated absorptions
characterised by gi values significantly different from that of
the free electron (gelectron =2.0023) is in agreement with the
existence of low-spin RuIII spin-orbit coupling.[32] Multiple
derivative procedures testify to the presence of two magneti-
cally different phosphine ligands. In fact, the gm (m=
medium field) lineshape, particularly resolved in the under-
lying shpf interactions (first- to third-derivative mode), gives
evidence of three well-separated signals (theoretical relative
intensity 1:2:1) characterised by slightly different linewidths
and heights. Such a spectral pattern supports the presence of
active 31P magnetic interactions (second- and third-deriva-
tive modes) that arise from the interaction of the unpaired
electron with two nearly equivalent P nuclei. By analogy,
similar spectral features are expected for the unresolved gl
and gh (l and h=low and high field, respectively) regions,
even if the gh absorption is affected by the presence of a
number of intense spike signals that largely superimpose the
underlying phosphorous absorptions (second-derivative
mode). Figure 6c and d show the simulated lineshapes, per-
Conclusions
The rigid alkynyldiphosphines dppab and tppab have been
synthesised by means of an alternative method that provides
better yields and avoids the use of lithium or magnesium
salts. The coordination behaviour of the two alkynylphos-
phines towards the {CpRu} synthon has been investigated
using different stoichiometries and reaction conditions that
have allowed us to synthesise mononuclear, dinuclear and
tetranuclear complexes in which the diphosphine may act as
a terminal or bridging ligand between two {CpRu} units. A
triruthenium species has been obtained from the tppab
ligand.
formed on the basis of “mean” shpf aACHTUNGTRNEUNG
(31P) values; accord-
ingly, the al and ah parameters are evaluated as upper limits
for shpf interactions relevant to the corresponding DHi as:
al ꢂDHl, and ah ꢂDHh.
The presence of stereogenic metal centres in some of
these complexes results in the formation of diastereomeric
pairs that are easily discernable by NMR spectroscopic
methods. Consistently, a rare example of a trinuclear chiral-
at-metal complex is generated when the triphosphine tppab
is used as a ligand capable of coordinating three {CpRu}
moieties. Of particular interest are the two polycations 8
and 9, which represent intriguing examples of polyruthena-
macrocycles that do not interconvert into each other.
The computed values for whole set of S=1/2 complexes
studied here are collected in Table 4.
Upon raising the temperature, the anisotropic signal rap-
idly reduces before disappearing at the glassy-fluid transi-
tion phase (T=120 K). Rapidly refreezing the room-temper-
ature solution makes the rhombic spectrum recover, even if
11994
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Chem. Eur. J. 2009, 15, 11985 – 11998

Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
mercury pool was used as the counter electrode. The UV/Vis spectroelec-
The dppab ligands in the dimetallic dimer assume either a
parallel conformation or a helical one as shown by the X-
ray studies for 7 and 8, respectively. The central benzene
rings of dppab are almost perfectly aligned in 8, whereas in
7 they are slipped relative to one another. The preference
for one shape or the other seems to be imposed by external
packing forces in the solid state.
Electrochemistry, supported by spectroelectrochemistry
and EPR spectroscopy, pointed out that both dppab and
tppab ligands do not allow any efficient communication
path between the redox-active Ru centres. In fact, the par-
trochemical measurements were carried out using
a Perkin–Elmer
Lambda 900 UV/Vis spectrophotometer and an OTTLE cell equipped
with a Pt-minigrid working electrode (32 wirescmꢁ1), Pt minigrid auxil-
AHCTUNGTRENNUNG
iary electrode, Ag wire pseudoreference and CaF2 windows.[38] The elec-
trode potential was controlled during electrolysis by an Amel potentio-
stat 2059 equipped with an Amel function generator 568. Nitrogen-satu-
rated solutions of the compound under study were used with [NBu4]ACHTUNGTRENNUNG[PF6]
(0.2 moldmꢁ3) as supporting electrolyte. Working potential was kept
fixed at the peak potential of the process under study and spectra were
progressively collected every 2 min of electrolysis.
X-band EPR spectra were recorded using an ER 200-SRCB Bruker spec-
trometer. The external magnetic field (H) was calibrated using a Micro-
wave Bridge ER041 MR Bruker wavemeter and the temperature was
controlled using an ER 4111VT Bruker device (accuracy=ꢃ1 K). The
diphenylpicrylhydrazyl (DPPH) free radical was used as suitable “field-
ACHTUNGTRENNUNGtially oxidised bi- and trinuclear compounds behave exactly
as the parent mononuclear cation [10]+ and can thus be
classified as Robin–Day class I mixed-valence complexes
with a localised charge.
marker” (gisoACHTUNRGTNEUNG(DPPH)=2.0036) for the determination of accurate gi
values. To ensure quantitative spectral reproducibility, the paramagnetic
samples were placed into a calibrated quartz capillary tube permanently
positioned in the resonance cavity.
Synthesis of 1,4-bis[(diphenylphosphino)ethynyl]benzene (dppab, 1):
Experimental Section
Chlorodiphenylphosphine (1.8 mL, 9.6 mmol), [NiACTHNURGTNEUNG(acac)2] (0.31 g,
0.12 mmol; acac=acetylacetonate) and Et3N (4 mL, 28.8 mmol) were
added to a solution of 1,4-diethynylbenzene (0.50 g, 4.0 mmol) in toluene
(50 mL). The mixture was stirred at 808C for 5 h. The solution was ex-
tracted with CH2Cl2 (3ꢄ40 mL) and the combined organic phases were
washed with brine (50 mL), dried over Na2SO4 and concentrated. The
crude product was purified by silica gel column chromatography to
afford 1 (1.29 g, 65%) as a white, low-melting solid. Rf =0.6 (n-hexane/
CH2Cl2 2:1); 1H NMR (400 MHz, CDCl3, 258C): d=7.38–7.35 (m, 12H;
P-C6H5), 7.50 (s, 4H; C6H4), 7.68–7.63 ppm (m, 8H; P-C6H5); 13C NMR
General: All manipulations were performed under a dry nitrogen atmos-
phere using vacuum lines and standard Schlenk techniques. Dichlorome-
thane and methanol were dried by standard methods and distilled under
nitrogen before use. All the other solvents were dried and degassed by
an MB SPS solvent purification system. 1,4-Diethynylbenzene,[35] 1,3,5-
triethynylbenzene,[36] [CpRu(PPh3)2Cl][17] and [CpRu(dppe)Cl][37] were
ACTHNUTRGENNUG CAHTUNGTRENNUGN
prepared from literature methods. Other reagents were obtained from
commercial suppliers and used without further purification. Reactions
were monitored by TLC on silica gel; detection was made using a
KMnO4 basic solution. Flash column chromatography was performed
using glass columns (10–50 mm wide) and silica gel (230–400 mesh).
(100.6 MHz, CDCl3, 258C): d=135.90 (d, 1J
G
2
132.62 (d, J
A
129.13 (s; P-pC6H5), 128.67 (d, 3J
ACHTUNGTRENNUNG
ipsoC6H4), 107.06 (d, 2J
A
Deuterated solvents for routine NMR spectroscopic measurements were
dried over molecular sieves. 1H and 13C{1H} NMR spectra were recorded
using a Bruker Avance DRX-300 spectrometer operating at 300.13 (1H)
and 75.48 MHz (13C) and a Bruker DRX-400 instrument operating at
400.13 (1H) and 100.61 MHz (13C). Peak positions are relative to tetrame-
thylsilane (1H) and were calibrated against the residual solvent reso-
nance. 31P{1H} NMR spectra were recorded using the same instruments
operating at 161.95 and 121.5 MHz. Chemical shifts were measured rela-
tive to external 85% H3PO4, with downfield shifts reported as positive.
FTIR spectra were measured using a Perkin–Elmer Spectrum BX instru-
ment with KBr pellets or solution cells. Elemental combustion microana-
8.1 Hz; ꢀC-C6H5); 31P{1H} NMR (162.0 MHz, CDCl3, 258C): d=
ꢁ33.3 ppm (s, 2P; PC6H5); IR (KBr): n˜ =2163 cmꢁ1 (CꢀC); MS (70 eV):
m/z (%): 494 (15) [M+], 77 (100) [C6H5+]; elemental analysis calcd (%)
for C34H24P2: C 82.58, H 4.86; found: C 83.01, H 4.55.
Synthesis of 1,3,5-tris[(diphenylphosphino)ethynyl]benzene (tppab, 2):
Chlorodiphenylphosphine (2.0 mL, 10.9 mmol), [NiACTHNUGTRENUNG(acac)2] (0.25 g,
0.1 mmol) and Et3N (3.3 mL, 23.76 mmol) were added to a solution of
1,3,5-triethynylbenzene (0.50 g, 3.3 mmol) in toluene (50 mL) The mix-
ture was stirred at 808C for 5 h. The solution was extracted with CH2Cl2
(3ꢄ40 mL) and the combined organic phases were washed with brine
(50 mL), dried over Na2SO4 and concentrated. The crude product was pu-
rified by silica gel column chromatography to afford 2 (1.51 g, 75%) as a
white solid. Rf =0.5 (n-hexane/CH2Cl2 2:1); m.p. 1108C; 1H NMR
(400 MHz, CDCl3, 258C): d=7.73–7.60 (m, 22H; P-C6H5), 7.43–7.40 ppm
(m, 26H, C6H4; P-C6H5); 13C NMR (100.6 MHz, CDCl3, 258C): d=135.56
ACHTUNGTRENNUNGlyses (C, H, N) were obtained using a Perkin–Elmer 2400 series II ele-
mental analyzer.
Mass spectra were obtained at a 70 eV ionisation potential and are re-
ported in the form m/z (intensity relative to base=100). ESIMS spectra
were done using an LTQ Orbitrap mass spectrometer (ThermoFisher,
San Jose, CA, USA) equipped with a conventional ESI source by direct
injection of the sample solution. The instrument parameters were the fol-
lowing: flow rate 3 mlminꢁ1, capillary voltage 60 V, tube lens 185 V, nomi-
nal resolution (at m/z 400) 60000. Eighty scans were accumulated and
averaged for each spectrum.
(d, 1J
21.1 Hz; P-oC6H5), 129.16 (s; C6H4), 128.68 (d, 3J
mC6H5), 123.56 (s; P-pC6H5), 105.35 (d, 2J
(C,P)=3.0 Hz; P-Cꢀ),
88.22 ppm (d, 1J
A
ACHTUNGTRENNUNG(C,P)=
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
A
CDCl3, 258C): d=ꢁ33.5 (s, 3P; PC6H5). IR (KBr): n˜ =1577 cmꢁ1 (CꢀC);
MS (70 eV): m/z (%): 702 (11) [M+], 77 (100) [C6H5+]; elemental analy-
sis calcd (%) for C48H33P3: C 82.04, H 4.73; found: C 81.86, H 4.90.
Electrochemical and spectroelectrochemical studies: Anhydrous 99.9%
dichloromethane was purchased from Aldrich. Fluka [NBu4]ACTHNUTRGNEUGN[PF6] (elec-
trochemical grade) was used as supporting electrolyte (0.2 moldmꢁ3).
Cyclic voltammetry was performed in a three electrode cell containing a
platinum working electrode surrounded by a platinum-spiral counter
electrode, and an aqueous saturated calomel reference electrode (SCE)
mounted with a Luggin capillary. A BAS 100W electrochemical analyzer
was used as polarising unit. All the potential values are referred to the
saturated calomel electrode (SCE). Under the present experimental con-
ditions, the one-electron oxidation of ferrocene in CH2Cl2 solution occurs
at E8’=+0.39 V. Controlled potential coulometry was performed in an
H-shaped cell with anodic and cathodic compartments separated by a sin-
tered-glass disk. The working macroelectrode was a platinum gauze; a
Synthesis of [{CpRuCl
(0.68 g, 0.14 mmol) in toluene (10 mL) was added to a solution of [CpRu-
(PPh3)2Cl] (0.20 g, 0.28 mmol) in toluene (10 mL). The mixture was
ACHTUNGTERNN(UNG PPh3)}2AHCTUNGTRENGN(UN m-dppab)] (3): A solution of dppab
AHCTUNGTRENNUNG
stirred at 608C for 4 h. The solvent was removed in vacuo, and the resi-
due washed with n-hexane at 608C, filtered and concentrated under
vacuum. The crude product was purified by silica gel column chromatog-
raphy to afford 3 (0.17 g, 89%) as an orange solid consisting of a 1:1 mix-
ture of two diastereoisomers (NMR spectroscopic signals due to the
second diastereoisomer are given in parenthesis). Rf =0.8 (CH2Cl2/ace-
tone 20:1); 1H NMR (400 MHz, CD2Cl2, 258C): d=7.95–7.88 (m, 5H),
7.68–7.62 (m, 5H), 7.40–7.33 (m, 9H), 7.26–7.10 (m, 30H), 4.22 (4.23)
Chem. Eur. J. 2009, 15, 11985 – 11998
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
11995

M. Peruzzini et al.
ppm (s, 10H); 13C NMR (100.6 MHz, CD2Cl2, 258C): d=140.30 (136.16)
(d, 1J (C6H5)2), 137.07 (d, 1J
(C,P)=50.4 Hz; RuP-ipso (C,P)=40.4 Hz;
RuP-ipso (C,P)=10.7 Hz; RuP-o(C6H5)3), 132.38
(C6H5)3), 134.08 (d, 2J
(131.84) (d, 3J
(C,P)=11.1, 3.0 Hz; RuP-m(C6H5)2), 131.90 (s; C6H4),
129.38 (d, 4J (C6H5)2), 129.07 (d, 4J
(C,P)=1.5 Hz; RuP-p (C,P)=1.9 Hz;
RuP-p (C,P)=10.2 Hz; RuP-m(C6H5)3),
(C6H5)3) 128.13 (127.99) (d, 3J
127.49 (d, 2J
(C,P)=9.6 Hz; RuP-o(C6H5)2), 122.97 (122.96) (s; RuP-
ipsoC6H4), 107.34 (d, 2J
Synthesis of [CpRuCl
in toluene (10 mL) was added to a solution of [CpRuAHCTUNGTRENNUNG
ACHTUNGTRENNUNG
G
E
ACHTUNGTRENNUNG
(0.11 g, 0.15 mmol) in toluene (10 mL). The mixture was stirred at 608C
for 1 h. The solvent was removed in vacuo, and the solid residue washed
with warm n-hexane (2ꢄ20 mL) and dried under vacuum. The crude
product was purified by silica gel column chromatography to afford 6
(0.31 g, 22%) as a yellow solid. Rf =0.7 (CH2Cl2/acetone 20:1); 1H NMR
(400 MHz, CD2Cl2, 258C): d=7.97–7.91 (m, 2H), 7.69–7.50 (m, 8H),
7.39–7.29 (m, 17H), 7.23–7.17 (m, 4H), 7.13–7.06 (m, 8H), 4.23 ppm (s,
5H, C5H5); 13C NMR (100.6 MHz, CD2Cl2, 258C): d=140.58 (dd, J-
E
N
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
E
U
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
N
ACHTUNGTRENUN(NG C,P)=72.4,
2.0 Hz; PCꢀC), 82.01 (m; Ru-C5H5); 31P{1H} NMR (162.0 MHz, CD2Cl2,
258C): d=45.22 (44.94) (d, 2J
ACHTNUGTRNEG(UN P,P)=14.1 Hz, 2P; RuP-(C6H5)3), 21.45
(21.17) ppm (d, 2J
ACHTUNGTRENNUNG(P,P)=12.8 Hz, 2P; RuP-(C6H5)2); IR (KBr): n˜ =2166
ACHUNTRGEN(NUG C,P)=50.0, 3.3 Hz; RuP-ipsoACHUTNGTREN(NNGU C6H5)2), 137.02 (dd, J (C,P)=4 0.6, 1.7 Hz;
1
(CꢀC), 1720, 802 cmꢁ1; ESIMS (MeOH) positive ion: m/z (%): 1422
RuP-ipso
A
N
ACHTNUGNERT(NGNU C6H5)2), 135.98
3
2
(21) [M]+, 1387 (20) [M+ꢁCl], 673 (100) [CpRuCl
N
G
(d, J
N
G
ACHTUNGTRENNUNG
U
ACHTUNGTRENNUNG
N
G
ACHTUNGTRENNUNG
E
N
ACHTUNGTRENNUNG
Synthesis of [{CpRu
(0.13 g, 0.37 mmol) in MeOH (0.5 mL) was added to a solution of [CpRu-
ACHTUNGTRENNUNG(dppe)Cl] (0.10 g, 0.17 mmol) in dichloromethane (30 mL). The mixture
ACHTUNGTRENNUNG(dppe)}2ACHTNURTGEN(GNNU m-dppab)]ACHTNUGTRENN(UGN PF6)2 (4): A solution of TlPF6
T
R
ACHTUNGTRENNUNG
U
E
ACHTUNGTRENNUNG
ꢀC-Po
G
A
ACHTUNGTRENNUNG
was stirred for 4 h and the supernatant was separated from TlCl. A solu-
tion of dppab (0.04 g, 0.08 mmol) in dichloromethane (10 mL) was then
mixed together with the previous solution and stirred at room tempera-
ture overnight. After this time, the solvent was removed in vacuo, and
the solid residue washed with warm n-hexane (2ꢄ20 mL at 608C) and
dried under vacuum. The crude product was purified by silica gel column
chromatography to afford 4 (0.10 g, 65%) as an orange solid. Rf =0.3
(CH2Cl2/acetone 20:1); 1H NMR (400 MHz, CD2Cl2, 258C): d=7.68 (m,
4H), 7.47–7.17 (m, 60H), 6.96–6.89 (m, 8H), 4.99 (s, 10H), 3.21–3.15 (m,
4H), 2.71–2.73 (m, 4H); 13C NMR (100.6 MHz, CD2Cl2, 258C): d=135.34
2.2 Hz; RuPCꢀ), 107.40 (d, 2J
ACHTUNGTRENNUNG
(C,P)=10.0 Hz; ꢀC-P
(C6H5)2), 88.83 (d, 1J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
(KBr): n˜ =2172 cmꢁ1 (CꢀC); ESIMS (MeOH) positive ion: m/z (%):
958 (12) [M]+; elemental analysis calcd (%) for C57H44ClP3Ru: C 71.43,
H 4.63; found: C 72.31, H 4.75.
Synthesis of [{(CpRuCl)
0.40 mmol) in toluene (10 mL) was added to a solution of [CpRu-
AHCTUNTGRENNG(UN PPh3)2Cl] (0.15 g, 0.20 mmol) in toluene (20 mL). The mixture was
ACHTUNGTRNEN(UNG m-dppab)}2] (7): A solution of dppab (0.68 g,
(m; RuP-ipso
C6H4), 131.78–131.68 (m; RuP-m
(C6H5)dppe), 131.27 (m, 2J
(C,P)=12.6 Hz; RuP-o
(m, 2J
(C,P)=12.6 Hz; RuP-o(C6H5)dppe), 130.07 (brs; RuP-p
128.84–128.66 (m; RuP-m(C6H5)2 +RuP-p
(C6H5)dppe), 128.41 (d, 2J-
(C,P)=11.1 Hz; RuP-o (C,P)=2.2 Hz; RuP-
(C6H5)2, 122.33 (d, 3J
ipsoC6H4), 106.58–106.44 (m; RuPCꢀC), 88.34–87.60 (m; RuPCꢀ),
86.22 ppm (m; Ru-C5H5), 26.70 ppm (dm, 1J
(P,P)=23.7 Hz; RuP-CH2)
26.48 (dm, 1J(P,P)=22.2 Hz; RuP-CH2); 31P{1H} NMR (162.0 MHz,
CD2Cl2, 258C): d=70.99 (d, J
2J
A
ACHTUGNTRENN(UGN C6H5)dppe), 133.22 (s;
AHCTUNGTRENNUNG
gently brought to reflux and stirred for 4 h. After this time, the superna-
tant was filtered off and the solid residue washed with warm n-hexane
(2ꢄ20 mL at 608C) and dried under vacuum. The crude product was pu-
rified by silica gel column chromatography to afford 7 (0.67 g, 25%) as
an orange solid. Rf =0.8 (CH2Cl2/acetone 20:1); 1H NMR (400 MHz,
CD2Cl2, 258C): d=8.18–8.13 (m, 8H), 7.58–7.53 (m, 8H), 7.39–7.32 (m,
12H), 7.21 (s, 8H), 7.00–6.96 (m, 4H), 6.89–6.86 (m, 8H), 4.49 ppm (s,
10H); 13C NMR (100.6 MHz, CD2Cl2, 258C): d=140.41 (m; RuP-ipso-
A
R
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
R
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
2
AHCTUNTGREUNNG(N P,P)=36.5 Hz, 1P; RuP-(C6H5)2), 30.33 (t,
N
N
ACHTNUGNERT(NGNU C6H5)2), 131.46
1
(P,P)=36.5 Hz, 2P; RuP-(C6H5)2), ꢁ144.4 ppm (sept, J
ACHTUNGTREN(NGNU P,F)=711.2 Hz,
T
ACHTUNGTRENNUNG
2P, PF6); IR (KBr): n˜ =2171 (CꢀC), 840 cmꢁ1 (P-F); ESIMS (MeOH)
positive ion: m/z (%): 1796 (19) [MꢁPF6]+; elemental analysis calcd (%)
for C96H82F12P8Ru2: C 60.25, H 4.32; found: C 60.46, H 4.70.
E
E
ACHTUNGTRENNUNG
(s; C6H4), 107.82 (m; RuPCꢀC), 86.74 (m; RuPCꢀ), 83.29 ppm (s; Ru-
C5H5); 31P{1H} NMR (162.0 MHz, CD2Cl2, 258C): d=18.67 ppm (s, 4P; P-
Synthesis of [{CpRuCl
(0.15 g, 0.20 mmol) in toluene (35 mL) was added to a solution of [CpRu-
(PPh3)2Cl] (0.47 g, 0.60 mmol) in the same solvent (30 mL). The mixture
A
E
A
solution of tppab
A
m/z (%): 1359 (20) [MꢁCl]+, 1392 (35) [M]+; elemental analysis calcd
(%) for C78H58Cl2P4Ru2: C 67.29, H 4.20; found: C 66.95, H 4.70.
ACHTUNGTRENNUNG
was stirred at 608C for 3 h. The solvent was removed in vacuo, and the
solid residue washed with warm hexane (2ꢄ20 mL at 608C) and dried
under vacuum. The crude product was purified by silica gel column chro-
matography to afford 5 (0.30 g, 70%) as an orange solid containing a
1:2:1 mixture of three diastereoisomers (31P NMR spectroscopic signals
of diastereoisomers are given in parenthesis). Rf =0.6 (CH2Cl2/acetone
30:1); 1H NMR (400 MHz, CD2Cl2, 258C): d=7.86–7.76 (m, 8H), 7.71–
7.61 (m, 8H), 7.38–7.03 (m, 62H), 4.22 ppm (s, 15H); 13C NMR
Synthesis of [{CpRu
CATHNUGTRNE(GNU PPh3)ACUHTNGTREN(NNGU m-dppab)}2]ACHTNURGTEG(NNUN PF6)2 (8) and [{CpRuACHTUNGTRENNUNG(PPh3)ACHTUNGTRENNUNG(m-
dppab)}4](PF6)4 (9): A solution of TlPF6 (0.40 g, 0.15 mmol) in MeOH
AHCTUNGTRENNUNG
(0.5 mL) was added to a solution of 3 (0.74 g, 0.52 mmol) and dppab
(0.26 g, 0.52 mmol) in dichloromethane (30 mL). The mixture was stirred
for 2 h and the supernatant was separated from TlCl by filtration. After
this time, the solvent was removed in vacuo and the solid residue dried.
The crude product was purified by silica gel column chromatography (di-
chloromethane/acetone 20:1) to afford an orange solid (0.87 g, 57%
based on 3) consisting of a mixture of 8 and 9 in an approximate 1:1
ratio. Dissolution of the solid mixture in ca. 150 mL CH2Cl2, followed by
slow addition of n-hexane, led to selective precipitation of 9 (0.47 g, 21%
based on 3) as a yellow solid. The remaining red solution was concentrat-
ed to dryness to afford pure 8 (0.40 g, 36% based on 3).
(100.6 MHz, CD2Cl2, 258C): d=139.95 (135.91) (d, 1J
RuP-ipso (C,P)=40.7 Hz; RuP-ipso(C6H5)3), 134.04
(C6H5)2), 136.91 (d, 1J
(d, 2J
(C,P)=10.7 Hz; RuP-o(C6H5)3), 132.60–132.36 (132.82–131.59) (m;
RuP-m(C6H5)2), 129.45 (brs, 3C; C6H3), 129.26 (brs; RuP-p(C6H5)2),
129.12 (brs; RuP-p (C,P)=10.0 Hz; RuP-
(C6H5)3), 128.17 (127.99) (d, 3J
(C6H5)3), 127.48 (d, 2J
(C,P)=9.3 Hz; RuP-o(C6H5)2), 122.82 (brs; RuP-
ipso
(C6H4)3), 105.11 (d, 2J
(C,P)=68.1 Hz; RuPCꢀ), 82.00 ppm (m; Ru-C5H5); 31P{1H} NMR
(162.0 MHz, CD2Cl2, 258C): d=45.53 (45.30, 45.129 (P,P)=46.7 Hz,
(d, 2J
(P,P)=46.7 Hz, 3P; RuP-
ACHTUNGTREN(NUNG C,P)=46.5 Hz;
A
R
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
Compound 8: Rf =0.6 (CH2Cl2/acetone 20:1); 1H NMR (400 MHz,
CD2Cl2, 258C): d=7.70–7.47 (m, 40H), 7.37–7.11 (m, 30H), 7.03 (s, 8H),
4.83 ppm (s, 10H); 13C NMR (100.6 MHz, CD2Cl2, 258C): d=135.95–
m
N
N
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
135.23 (m; RuP-ipso
10.4 Hz; RuP-o(C6H5)3), 132.01–131.91 (m; RuP-o
C6H4), 131.11–130.56 (m; RuP-m(C6H5)2), 130.20 (brs; RuP-p
128.83–128.35 (m; RuP-p(C6H5)2 +RuP-m(C6H5)3), 122.16 (s; RuP-ipso-
N
N
ACHTUNGTRENNUNG(C,P)=
3P; RuP-(C6H5)3), 23.00 (22.70, 22.51) (d, 2J
ACHTUNGTRENNUNG
T
ACHTUNGTRENNUNG
(C6H5)2); IR (KBr): n˜ =2175 (CꢀC), 840 cmꢁ1 (P-F); ESIMS (MeOH)
ACHTUNGTRENNUNG
positive ion: m/z (%): 673 (17) [MꢁC6H3ꢁ
ACHUTGTNNERNUG(CpRuClACHTUNTGERN(NGUN PPh3)-
A
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
A
ACHTUNGTREN(NUNG C,P)=79.1 Hz;
RuPCꢀ), 86.18 ppm (m; Ru-C5H5); 31P{1H} NMR (162.0 MHz, CD2Cl2,
11996
www.chemeurj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 11985 – 11998

Cyclopentadienyl Ruthenium(II) Complexes
FULL PAPER
258C): d=38.95 (t, 2J
A
G
with the program CrysAlis RED[40] Absorption correction was applied
through the program ABSPACK.[40] The structures were solved with
direct methods implemented in the program Sir97[41] and the refinement
was completed by full-matrix least squares against F2 using all data im-
plemented in SHELXL.[42] Full details of crystallographic data are given
in Table 5.
(P,P)=37.5 Hz, 2P; RuP-(C6H5)2), ꢁ144.6 ppm (sept, 1J
ACHTUNGTRENNUNG
2P; PF6); IR (KBr): n˜ =2168 (CꢀC), 837 cmꢁ1 (P-F); ESIMS (MeOH)
positive ion: m/z (%): 1991 (100) [MꢁPF6]+; elemental analysis calcd
(%) for C114H88F12P8Ru2: C 64.11, H 4.15; found: C 64.36, H 4.98.
Compound 9: Rf =0.4 (CH2Cl2/acetone 20:1); 1H NMR (400 MHz,
CD2Cl2, 258C): d=7.72–7.67 (m, 20H), 7.53–7.43 (m, 60H), 7.28–7.20 (m,
60H), 7.08 (brs, 16H), 4.84 ppm (s, 20H); 13C NMR (100.6 MHz, CD2Cl2,
In compound 7, a merohedral twinning is present and the twin compo-
nent was found to be 0.50(7). The cyclopentadienyl ring bonded to Ru2
was fitted as a rigid group and the carbon atoms were restrained to have
the same Uij components. All the non-hydrogen atoms were refined ani-
sotropically and the hydrogen atoms were fixed in calculated positions
and refined isotropically with thermal factors related to those of the
atom they are bound to.
258C):): d=137.45–136.64 (m; RuP-ipso
133.59 (d, 2J
(C,P)=10.4 Hz; RuP-o(C6H5)3), 133.05–132.92 (m; RuP-o-
(C6H5)2), 132.09–131.97 (m; RuP-o(C6H5)2), 131.84 (brs; C6H4), 131.81–
130.83 (m; RuP-m(C6H5)2), 129.71 (brs; RuP-p(C6H5)3), 128.91–128.40
(C6H5)3), 122.17 (s; RuP-ipso(C6H4)),
(C,P)=80.4 Hz; RuPCꢀ),
ACHTUTNGREN(GUN C6H5)3 +RuP-ipsoACHTUGNTREN(NUGN C6H5)2),
C
ACHTUNGTRENNUNG
N
ACHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
(m; RuP-p
G
T
ACHTUNGTRENNUNG
107.34–107.25 (m; RuPCꢀC), 87.92 (d, 1J
ACHTUNGTRENNUNG
The crystals of 8 were unstable when removed from the mother liquor at
room temperature and they were mounted using cryo-techniques. All the
non-hydrogen atoms were refined anisotropically, except for the carbon
86.22 ppm (m; Ru-C5H5); 31P{1H} NMR (162.0 MHz, CD2Cl2, 258C): d=3
9.23 (t, 2J(P,P)=38.5 Hz; 8P, RuP-(C6H5)2), 23.88 (d, 2J
ACHTUNGTRENNUNG ACHTUTGNREN(NUGN P,P)=38.5 Hz,
4P, RuP-(C6H5)2), ꢁ144.6 (sept, 1J
A
ꢁ
atoms of three solvent molecules of 1,2-dichloroethane. The C C and the
n˜ =2168 (CꢀC), 837 cmꢁ1 (P-F); ESIMS (MeOH) positive ion: m/z (%):
ꢁ
C Cl bond lengths of the latter were restrained to 1.55 ꢃ and forced to
923 (100) [Cp2Ru2ACHTUNGTRENNUNG
be equal with an estimated standard deviation of 0.02. The hydrogen
atoms were placed in calculated positions and refined isotropically with
thermal factors related to those of the atom they are bound to. Geomet-
rical calculations were performed by PARST97[43] and molecular plots
were produced by the program ORTEP3.[44] All the calculations were
performed using the package WINGX.[45]
analysis calcd (%) for C228H176F24P16Ru4: C 64.11, H 4.15; found: C 64.23,
H 4.21.
Crystallographic studies: Data collection for complexes 7 and 8 was car-
ried out using an Oxford Diffraction Xcalibur3 diffractometer equipped
with MoKa radiation (0.71073 ꢃ). Data collection was performed at 150 K
with the program CrysAlis CCD[39] and data reduction was carried out
Table 5. Crystal data and structure refinement for compounds 7 and 8.
Acknowledgements
7
8
formula
Mr
T [K]
l [ꢃ]
crystal system
space group
a [ꢃ]
b [ꢃ]
c [ꢃ]
a [8]
b [8]
C78H58Cl2P4Ru2
1392.16
150(2)
0.71069
orthorhombic
Pca21
18.7930(10)
17.3350(10)
20.0080(10)
90
90
90
6518.1(6)
4
1.419
0.688
2832
0.15ꢄ0.07ꢄ0.05
3.75 to 25.00
ꢁ22ꢂhꢂ15,
ꢁ20ꢂkꢂ20,
ꢁ23ꢂlꢂ23
23772
C130H120Cl16F12P8Ru2
2927.36
150(2)
0.71069
triclinic
¯
P1
B.D.C, A.R. and M.P. acknowledge the motu proprio FIRENZE HY-
DROLAB project by Ente Cassa di Risparmio di Firenze (http://www.
iccom.cnr.it/hydrolab/) and PRIN 2007 (MIUR) for funding this research
activity, through a doctoral grant to B.D.C and a post-doctoral grant to
A.R. B.D.C. would like to thank Mr. Fabrizio Zanobini for experimental
support at ICCOM-CNR, and Dr. Guido Mastrobuoni, Dr. Elena Mi-
chelucci and Dr. Angela Casini for ESIMS spectra at University of Flor-
ence. P.Z., F.L. and F.F.B. gratefully acknowledge the financial support of
the University of Siena (PAR 2008).
12.7488(5)
15.2991(8)
19.4914(9)
67.404(5)
74.656(4)
83.577(4)
3384.5(3)
1
1.436
0.697
1488
0.2ꢄ0.15ꢄ0.1
3.73 to 27.49
ꢁ15ꢂhꢂ15,
ꢁ18ꢂkꢂ19,
ꢁ25ꢂlꢂ23
22066
g [8]
[1] W. Maverick, S. C. Buckingham, Q. Yao, J. R. Bradbury, G. G. Stan-
ley, J. Am. Chem. Soc. 1986, 108, 7430–7431.
[2] J. Padilla, G. Gatteschi, P. Chaudhuri, Inorg. Chim. Acta 1997, 260,
217–220.
[3] F. S. McQuillan, H. Chen, A. Hamor, C. J. Jones, Polyhedron 1996,
15, 3909–3913.
[4] R. V. Slove, D. I. Yoon, R. M. Calhoun, J. T. Hupp, J. Am. Chem.
Soc. 1995, 117, 11813–11814.
V [ꢃ3]
Z
1calcd [Mgmꢁ3
]
m [mmꢁ1
]
F
G
size [mm3]
q range [8]
limiting indices
[5] P. J. Stang, B. Olenyuk, Acc. Chem. Res. 1997, 30, 502–518; A.
Kumar, S.-S. Sun, A. J. Lees, Coord. Chem. Rev. 2008, 252, 922–939;
S. Tashiro, M. Tominaga, M. Kawano, B. Therrien, T. Ozeki, M.
Fujita, J. Am. Chem. Soc. 2005, 127, 4546–4547; J. L. Boyer, L. M.
Kuhlman, T. B. Rauchfuss, Acc. Chem. Res. 2007, 40, 233–242.
[6] “Phosphine, Arsine and Stibine Complexes of the Transition Ele-
ments”: C. A. McAuliffe, W. Levason, Studies in Inorganic Chemis-
try, Vol. 1, Elsevier, Amsterdam, 1978; “Catalytic Aspects of Metal
Phosphine Complexes”: C. E. Alyea, D. W. Meek, Advances in
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reflns collected
unique reflns
Rint
completeness to q=258 [%] 99.2
absorption correction
10001
0.0907
12383
0.0431
96.4
semi-empirical
semi-empirical
from equivalents
1/0.76941
12383/9/727
1.061
R1 =0.0978,
wR2 =0.2762
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wR2 =0.3073
–
from equivalents
0.9662/0.9271
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0.926
R1 =0.0774,
wR2 =0.1661
R1 =0.1639,
wR2 =0.2194
0.52(7)
max/min transmission
data/restraints/parameters
goodness-of-fit on F2
final R indices (I>2s(I))
R indices (all data)
absolute structure
parameter
largest diff. peak and hole
0.960 and ꢁ0.669
2.184 and ꢁ1.121
[eAꢁ3
]
Chem. Eur. J. 2009, 15, 11985 – 11998
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Received: June 16, 2009
Published online: September 29, 2009
11998
www.chemeurj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2009, 15, 11985 – 11998