Synthesis and structural characterization of ruthenium(II) and iron(II) complexes containing 1,2-di-(2-thienyl)-ethene derived ligands as chromophores

Article abstract of DOI:10.1016/j.jorganchem.2008.11.019

A new family of three-legged piano stool structured organometallic compounds containing the η⁵-cyclopentadienylruthenium(II)/iron(II) fragments {M(η⁵-C₅H₅) (DPPE)}⁺, {Ru(η⁵-C₅H

Full text of DOI:10.1016/j.jorganchem.2008.11.019

Journal of Organometallic Chemistry 694 (2009) 433–445
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structural characterization of ruthenium(II) and iron(II)
complexes containing 1,2-di-(2-thienyl)-ethene derived ligands as chromophores
a
b
b
b,c
M. Helena Garcia a, , Pedro Florindo , M. Fátima M. Piedade , M. Teresa Duarte , M. Paula Robalo
,
*
Etienne Goovaerts d, Wim Wenseleers d
a Centro de Ciências Moleculares e Materiais, Faculdade de Ciências da Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal
b Centro de Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
c Departamento de Engenharia Química, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal
d Physics Department, University of Antwerp (UIA), Universiteitsplein 1, 2610 Wilrijk-Antwerpen, Belgium
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 23 July 2008
Received in revised form 6 November 2008
Accepted 7 November 2008
Available online 14 November 2008
A new family of three-legged piano stool structured organometallic compounds containing the
g
5-cyclo-
pentadienylruthenium(II)/iron(II) fragments {M(
g g
5-C5H5) (DPPE)}+, {Ru( 5-C5H5)(PPh3)2}+ and
{Ru(g
5-C5H5)(TMEDA)}+ with coordinated thiophene based chromophores, namely 5-(2-thiophen-2-yl-
vinyl)-thiophene-2-carbonitrile (L1) and 5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile
(L2) has been synthesized and fully characterized by 1H, 13C, 31P NMR, IR and UV–Vis spectroscopies. Also,
electrochemical studies were carried out by cyclic voltammetry and all experimental data are interpreted
Keywords:
Ruthenium(II)
Iron(II)
Monocyclopentadienyl
1,2-Di-(2-thienyl)-ethene nitrile ligands
Cyclic voltammetry
Nonlinear optics
and compared with related compounds under the scope of NLO properties. Compounds [Ru(
g
5-C5H5)-
g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))]
(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))][CF3SO3] (10Ru) [Fe(
[PF6] (1Fe) and [Ru(g5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H2S)NO2)][CF3SO3] (40Ru) were also crystallo-
graphically characterized.
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
leading to higher b values than the usual organic groups (NR2,
NH2, etc.).
Since the report by Green et al. [1], revealing good second har-
monic generation efficiencies for ferrocenyl derivatives, the inter-
est in organometallic chemistry for the development of new NLO
materials has increased considerably, motivated by the potential
relevance of these materials in optical device technology [2–9].
In order to obtain a nonzero second-order response (molecular
hyperpolarizability b), strongly asymmetric systems are needed.
Thiophene moiety has been studied as chromophore both in or-
ganic [16–18] and organometallic [19–25] materials for NLO and it
is nowadays recognized to exhibit enhanced second-order polariz-
abilities compared to
p-systems with phenylene bridges, mainly
due to its lower delocalization energy, leading to a more effective
conjugation. We recently reported the synthesis and NLO proper-
ties of
g
5-monocyclopentadienyliron(II) complexes with substi-
These systems can be obtained by combining a
with electron donor and/or acceptor groups (D-
systems) in which metal centers can behave either as acceptor
or donor group by simply varying the metal and/or its oxidation
state. Although interesting results have been achieved with ferro-
cene systems [10], half-sandwich complexes, in which the metal
p
-conjugated chain
tuted oligo-thiophene nitrile derived ligands [26]. The observed
constancy of b0 upon chain-lengthening was attributed to a lower-
ing of the charge transfer efficiency with increasing conjugation
length, considering torsion angles in oligo-thiophenes to be small
and thus not a significant factor to be considered in the observed
trend [27,28]. In order to complement this study and also to con-
firm these conclusions, a set of new compounds was synthesized,
p
-A or push–pull
center is coplanar with the
the NLO response of organometallic complexes. Concerning this
feature, systematic studies were made on
5-monocyclopentadie-
p-conjugated backbone, have boosted
where the extension of the
p system was featured by the introduc-
g
tion of one vinylene unit between two thiophene rings, also assur-
nylmetal complexes with benzene-based conjugated ligands
bound to the metal center through nitrile or acetylide linkages
[11–15]. Iron and ruthenium organometallic moieties have proven
to be very efficient donor groups for second-order NLO purposes,
ing the planarity of the chromophore.
The new compounds of general formula [M(g
5-C5H5)(LL)-
(NC(C4H2S)C(H)C(H)(C4H2S)Z))][Y], with Z = H, NO2 (M = Ru,
LL = DPPE {Y = PFꢀ, CF3SOꢀ}, 2PPh3 {Y = PF6ꢀ}, TMEDA {Y = PF6ꢀ};
6
3
M = Fe, LL = DPPE {Y = PFꢀ6 }) were characterized by the usual FT-
IR, UV–Vis, 1H 13C and 31P NMR spectroscopic techniques. The
* Corresponding author.
E-mail addresses: lena.garcia@ist.utl.pt, lena.garcia@fc.ul.pt (M.H. Garcia).
organometallic fragment [Ru(g
5-C5H5)(TMEDA)]+ was introduced
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.11.019

434
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
in these studies to evaluate the effect of the amine coligand on the
donor ability of the organometallic moiety, relatively to the
of the aldehyde 2 with hydroxylammonium chloride in pyridine
and dehydration with acetic anhydride leaded to L1. Reaction
of 1 with nitric acid in acetic acid afforded 2-nitro-5-(2-thio-
phen-2-yl-vinyl)-thiophene (3); L2 was then obtained from 3,
by formylation and reduction to nitrile, applying the procedure
described above for the synthesis of L1. All these reactions are
summarized in Scheme 1.
The new nitrile ligands, obtained with yields of 74% (L1) and
33% (L2) from 1, were fully characterized by IR, 1H and 13C NMR
spectroscopies. Elemental analyses are in accordance with the pro-
posed formulations.
[Ru(g
5-C5H5)(PP)]+ fragment (PP = DPPE and PPh3) currently used
in our published studies [8,11–13]. The electrochemical studies
were performed by means of cyclic voltammetry in order to
get an insight on the electronic properties of the complexes
and the results, together with the spectroscopic data, are
discussed under the scope of the structural features that can be
related to the NLO properties. X-ray diffraction studies of
compounds [Ru(
g
g
g
5-C5H5)(DPPE)(NC (C4H2S)C(H)C(H)(C4H3S))][CF3SO3]
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
(10Ru)
[Fe(
(1Fe) and [Ru(
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H2S)NO2)]-
The solid state FT-IR spectra (KBr pellets) showed the character-
istic stretching vibration of the nitrile functional group at
ꢁ2215 cmꢀ1 for both compounds. The FT-IR spectrum of L2 also
[CF3SO3] (40Ru) are also discussed.
shows the NO2 stretching bands at 1483 and 1337 cmꢀ1
.
2. Results and discussion
2.2. Synthesis of the Ru(II)/Fe(II) complexes
2.1. Synthesis of the ligands
Complexes of general formula [M(g
5-C5H5)(LL)(NC(C4H2S)-
The thiophene chromophores 5-(2-thiophen-2-yl-vinyl)-thio-
phene-2-carbonitrile (L1) and 5-[2-(5-nitro-thiophen-2-yl)-vi-
nyl]-thiophene-2-carbonitrile (L2) were synthesized according
to general procedures. The parent molecule 1,2-di-(2-thienyl)-
ethene (1) was prepared with good yield from 2-thiophenecarb-
oxaldehyde, by McMurry reaction [29]. Formylation of the
thiophene unit was achieved by treatment of 1 with DMF and
phosphorous oxychloride (Vilsmeier–Haack reaction). Reaction
C(H)C(H)(C4H2S)Z)][Y], with Z = H, NO2; M = Ru, LL = DPPE {Y =
PFꢀ, CF3SOꢀ}, 2PPh3 {Y = PFꢀ}, TMEDA {Y = PFꢀ}; M = Fe, LL = DPPE
6
3
6
6
{Y = PFꢀ6 }, were prepared by halide abstraction with a salt of the
adequate counter-ion, in dichloromethane, from the corresponding
neutral complex [M(g
5-C5H5)(LL)X] (M = Fe(II), X = I; M = Ru(II),
X = Cl), in the presence of a slight excess of the corresponding
nitrile (Scheme 2).
Scheme 1. Synthesis of nitrile ligands 5-(2-thiophen-2-yl-vinyl)-thiophene-2-carbonitrile (L1) and 5-[2-(5-nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile (L2). (I)
DMF, POCl3; (II) (i) H2NOHꢂHCl, (ii) Ac2O; (III) HNO3, AcOH; (IV) DMF, POCl3; (V) (i) H2NOHꢂHCl, (ii) Ac2O.
Scheme 2. Synthesis of the new complexes [M(g
5-C5H5)(LL)(NC(C4H2S)C(H)C(H)(C4H2S)Z)][Y].

M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
435
1Ru M ¼ Ru; ðLLÞ ¼ DPPE; Z ¼ H; Y ¼ PF6ꢀ
Table 1
Selected 1H NMR data for ligands L1 and L2, free and coordinated to Ru/Fe
10Ru M ¼ Ru; ðLLÞ ¼ DPPE; Z ¼ H; Y ¼ CF3SOꢀ
3
organometallic fragments.
1Fe M ¼ Fe; ðLLÞ ¼ DPPE; Z ¼ H; Y ¼ PF6ꢀ
2Ru M ¼ Ru; ðLLÞ ¼ TMEDA; Z ¼ H; Y ¼ PF6ꢀ
Compound Proton
H3
H4
H6
H7
H9
H10
H11
g-
3Ru M ¼ Ru; ðLLÞ ¼ 2PPh3; Z ¼ H; Y ¼ PFꢀ
C5H5
6
4Ru M ¼ Ru; ðLLÞ ¼ DPPE; Z ¼ NO2; Y ¼ PFꢀ
L1
d 7.75
d 6.76
d 6.77
d 6.72
d 7.31 d 7.44 d 7.21 d 7.32 m 7.09 d 7.49
–
6
40Ru M ¼ Ru; ðLLÞ ¼ DPPE; Z ¼ NO2; Y ¼ CF3SOꢀ
1Ru
10Ru
1Fe
2Ru
3Ru
d 7.28 d 7.30 d 7.07 d 7.09 m 7.10 d 7.51 s 5.04
d 7.27 d 7.32 d 7.05 d 7.10 m 7.14 d 7.49 s 5.02
d 7.04 d 7.04 d 7.24 d 7.27 m 7.08 d 7.48 s 4.67
3
4Fe M ¼ Fe; ðLLÞ ¼ DPPE; Z ¼ NO2; Y ¼ PFꢀ
6
5Ru M ¼ Ru; ðLLÞ ¼ TMEDA; Z ¼ NO2; Y ¼ PFꢀ
br 7.93 d 7.38 d 7.47 d 7.24 d 7.31 m 7.11 d 7.52 s 4.32
6Ru M ¼ Ru; ðLLÞ ¼ 2PPh3; Z ¼ NO2; Y ¼ PFꢀ 6
a
a
a
d 7.52
d 7.20 d 7.31 m 7.11
s 4.76
6
L2
d 7.96
d 6.82
d 6.82
d 6.79
d 7.51 d 7.53 d 7.69 d 7.44 d 8.12
d 7.24 d 7.32 d 7.48 d 7.36 d 7.99
d 7.20 d 7.33 d 7.47 d 7.36 d 8.00
d 7.21 d 7.29 d 7.46 d 7.36 d 7.99
–
–
–
–
–
–
–
4Ru
40Ru
4Fe
5Ru
6Ru
s 5.03
s 5.02
s 4.70
s 4.34
s 4.77
Reactions were carried out at room temperature, stirring over-
night, under inert atmosphere. Compounds were recrystallized
from dichloromethane/n-hexane, n-heptane or diethyl ether,
affording crystalline yellow or orange products. With exception
of compounds 2Ru and 5Ru, which revealed to be very sensitive
to air, all compounds were fairly stable to air and moisture, either
in the solid state or in solution and were obtained in good yields of
70–90%. The formulation is supported by FT-IR and 1H, 13C, 31P
NMR spectroscopic data and by elemental analysis.
br 7.99 d 7.53 d 7.50 d 7.64 d 7.40 d 8.01
d 7.58
*
*
d 7.60 d 7.58 d 8.00
a
Masked by phosphine protons signals.
throughout the entire
group.
p-system, due to the pull effect of the NO2
The solid state IR spectra of the complexes present the character-
istic bands of the cyclopentadienyl ligand (ꢁ3050 cmꢀ1), the PF6ꢀ
(840 and 560 cmꢀ1) or CF3SO3ꢀ anions (1250 cmꢀ1) and the coordi-
nated nitrile(2193–2214 cmꢀ1). As observed beforefor other related
In the complexes with TMEDA coligand, this shielding effect is
not observed, despite the negative shift on mNC found for these
the complexes, marginally higher than for the corresponding DPPE
complexes. It also worth mentioning that for compounds with
TMEDA as coligand, namely 2Ru and 5Ru, the Cp ring is shielded,
relatively to the compounds with phosphines as coligands, in both
1H and 13C NMR spectra. These facts seem to indicate that the
g
5-monocyclopentadienyliron/ruthenium compounds, negative
shifts, in the range ꢀ3 to ꢀ21 cmꢀ1, were observed on
mNC by com-
parison with the corresponding values of the uncoordinated nitrile.
This effect has been attributed to
p-backdonation, due to
p bonding
between the d orbitals of the metal and the
p
* orbital of the nitrile
electron density is trapped in the metal centre and that p-backdo-
nation effect is limited only to the nitrile group, without delocal-
group, which leads to a decrease in N„C bond order [30]; accord-
ingly, the highest negative shift of ꢀ21 cmꢀ1 was found for the iron
derivative 4Fe, which presents the good NO2 acceptor group in the
ligand structure. Surprisingly, compounds presenting TMEDA as col-
igand, instead of phosphines, showed even higher negative shifts on
ization along the chromophore.
13C NMR data shows that the carbons of the chromophore
ligands remained almost unchanged or suffered a slight deshiel-
ding upon coordination, except for the carbon of the nitrile group
m
NC, althoughnoother evidence of p-backdonationhas beenfound in
which is clearly deshielded due to
centre.
r coordination to the metal
the remaining spectroscopic studies. This effect might be due to the
proximity of the TMEDA coligand due to the shorter distance Ru–N
when compared to Ru–P in the equivalent compounds with DPPE
or PPh3 coligands, and was also observed for other ruthenium com-
plexes with nitrogen ligands, where the effect of backdonation was
not noticed [31].
31P{1H} NMR data of the complexes showed a single sharp sig-
nal for the phosphine coligands (DPPE and PPh3) revealing the
equivalency of the two phosphorus atoms, and an expected desh-
ielding upon coordination, in accordance with its
character.
r donor
1H NMR resonances for the cyclopentadienyl ring are in the
characteristic range of monocationic ruthenium(II) and iron(II)
complexes. The effect of coordination on the nitrile ligands is ob-
served through the shielding of the first thiophene ring protons,
especially for the H3 protons (see Fig. 1 for numbering scheme),
indicating an electronic flow towards the aromatic ligand due to
2.3. UV–Visible studies
The optical absorption spectra of all the synthesized new com-
plexes were recorded in ꢃ5 ꢄ 10ꢀ5 mol dmꢀ3 solutions of
dichloromethane and methanol (Table 2) in order to identify any
metal-to-ligand charge transfer band (MLCT) and the
tion bands, expected for these complexes.
In order to understand the effect of the substituting groups on
the L1 and L2 chromophores, the electronic spectra of 1,2-di-(2-
thienyl)-ethene (1) and 2-nitro-5-(2-thiophen-2-yl-vinyl)-thio-
phene (3) were also obtained. These electronic spectra are shown
together in Fig. 2, for comparison.
p-backdonation involving the metal centre. This effect is very pro-
p–p
* absorp-
nounced in the complexes with DPPE, showing the better -donor
r
ability of this coligand, with shieldings on H3 up to 1.2 ppm, upon
coordination. In the complexes involving the L1 ligand, the shield-
ing effect is noticed only on H3, H4 and H6, but in the complexes
with L2 all the aromatic protons show a significant shielding (see
Table 1), this indicating that the electronic flow is extended
As expected, the introduction of the acceptor group NO2 leads
to a bathochromic shift of the
p–
p* transition band, while the ni-
trile group leads only to changes in band intensity, in relation to
compound 1. The electronic spectrum of L2 is similar to the one
of 3, presenting a slightly more energetic
p–
p* transition band
(20 nm).
The electronic spectra of all the complexes (see Fig. 3) showed
two intense absorption bands in the UV region, attributed to
electronic transitions occurring in the organometallic frag-
ment [MCp(LL)]+ (k ꢁ 240 nm) and coordinated chromophores
Fig. 1. Numbering scheme for NMR spectral assignments of Ru/Fe complexes and
free ligands.

436
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
Table 2
Optical spectra data for Ru(II)/Fe(II) complexes and organic compounds 1, 3, L1 and L2
in CH2Cl2 and MeOH (ca. 5 ꢄ 10ꢀ5 M) solutions.
Compound
kmax (nm) (
e
, Mꢀ1 cmꢀ1
MeOH
)
CH2Cl2
1,2-di-(2-thienyl)-ethene (1)
260(6000)
342(21800)
286(11200)
421(19300)
258(12400)
341(10000)
382(23500)
383(23100)
411(28200)
271(12400)
385(28200)
391(28200)
290(11000)
401(20000)
422(26900)
421(27200)
406(20500)
292(12500)
405(28200)
425(26800)
2-Nitro-5-(2-thiophen-2-yl-vinyl)-thiophene (3)
5-(2-Thiophen-2-yl-vinyl)-thiophene-2-carbonitrile
(L1)
[Ru(
g
5-C5H5)(DPPE)(L1)][PF6] (1Ru)
383(24000)
385(24100)
407(28800)
272(11900)
391(26600)
388(27500)
[Ru(g5-C5H5)(DPPE)(L1)][CF3SO3] (10Ru)
[Fe(g
5-C5H5)(DPPE)(L1)][PF6] (1Fe)
[Ru(
g
5-C5H5)(TMEDA) (L1)][PF6] (2Ru)
[Ru(g
5-C5H5)(PPh3)2(L1)][PF6] (3Ru)
5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-
thiophene-2-carbonitrile (L2)
[Ru(
g
5-C5H5)(DPPE)(L2)][PF6] (4Ru)
419(21700)
417(22600)
400(25300)
305(9800)
417(24000)
433(25400)
[Ru(g5-C5H5)(DPPE)(L2)][CF3SO3] (40Ru)
[Fe(g
5-C5H5)(DPPE)(L2)][PF6] (4Fe)
Fig. 3. Electronic spectra for complexes 4Ru (– –), 4Fe (—), 5Ru (—ꢂ—), 6Ru (—ꢂꢂ—)
and the uncoordinated ligand L2 (ꢂ ꢂ ꢂ) in dichloromethane.
[Ru(g
5-C5H5)(TMEDA)(L2)][PF6] (5Ru)
[Ru(g
5-C5H5)(PPh3)2(L2)][PF6] (6Ru)
2.4. Electrochemical studies
In order to get an insight on the electron richness of the organo-
metallic fragment and the coordinated chromophores, the electro-
chemical behavior of Ru(II) and Fe(II) compounds and the free
ligands, L1 and L2, was studied by cyclic voltammetry in dichloro-
methane and acetonitrile, between the limits imposed by the sol-
vents. Compounds possessing TMEDA as coligand, 2Ru and 5Ru,
were not studied due to fast decomposition in our current experi-
Table 3
Electrochemical data for complexes [M(
Z))][PF6] and for organic compounds 1, 3, L1 and L2, in dichloromethane.
g
5-C5H5)(LL)(NC(C4H2S)C(H)C(H)(C4H2S)-
Compound
Epa
(V)
Epc
(V)
Ep1/2 Epa ꢀ Epc Ia/
(V)
(mV)
Ic
1,2-di-(2-thienyl)-ethene (1)
1.28
–
–
–
–
–
–
–
–
–
–
–
0.83
–
–
–
–
–
–
–
–
–
–
–
110
–
–
–
–
–
–
–
110
–
–
100
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
ꢁ1
–
–
–
–
–
–
–
–
–
–
ꢁ1
–
–
–
–
–
–
–
–
0.36a
2-Nitro-5-(2-thiophen-2-yl-vinyl)-
thiophene (3)
1.58
–
ꢀ0.83
1.51
–
1.51
1.28
–
1.54
0.88
–
1.43
1.32
–
ꢀ1.01
5-(2-Thiophen-2-yl-vinyl)-thiophene-
2-carbonitrile (L1)
–
–
–
Fig. 2. Electronic spectra of compounds 1 (ꢂ ꢂ ꢂ), 3 (—ꢂ—), L1 (– –) and L2 (—),
recorded in ꢃ5 ꢄ 10ꢀ5 mol dmꢀ3 dichlomethane solutions.
[Ru(g
5-C5H5)(DPPE)(L1)][PF6] (1Ru)
1.12
ꢀ1.50
–
0.77
ꢀ1.46
1.30b
1.11b
ꢀ1.49
–
ꢀ0.98
ꢀ1.36
1.15
ꢀ0.88
ꢀ1.18
0.78
ꢀ0.86
ꢀ1.18
–
[Fe(g
5-C5H5)(DPPE)(L1)][PF6] (1Fe)
(k ꢁ 380–425 nm). No other defined bands can be observed. None-
theless, the broadening of the p–p
* absorption bands in the spectra,
[Ru(g
5-C5H5)(PPh3)2(L1)][PF6] (3Ru)
particularly for 1Fe and 4Fe, indicating a complex structure, let us
–
–
–
–
–
1.21
–
–
0.83
–
suspect that a new MLCT band might be overlapped with these
bands. Our previous results for
g
5-monocyclopentadienyliron(II)
5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-
thiophene-2-carbonitrile (L2)
1.23
ꢀ0.74
ꢀ1.15
1.27
ꢀ0.73
ꢀ1.04
0.88
ꢀ0.71
ꢀ1.03
1.41
1.23
ꢀ0.77
complexes with substituted oligo-thiophene nitrile ligands [26],
5-C5H5)(DPPE)(L2)][PF6] (4Ru)
showed that chain-lengthening leads to a bathochromic shift of
[Ru(g
the
Since complexes [M(
p–p
* transitions and to a hypsochromic shift of the MLCT band.
g
5-C5H5)(LL)(NC(C4H2S)C(H)C(H)(C4H2S)Z)][Y]
[Fe(g
5-C5H5)(DPPE)(L2)][PF6] (4Fe)
have approximately the same conjugation length of the complexes
[FeCp(P-P)(NC{C4H2S}3NO2)][PF6], for which the referred overlap
was observed, the present assumptions seem therefore quite
pertinent.
No visible solvatochromic effect was verified for the complexes
due to the small polarity difference between dichloromethane and
–
–
–
–
[Ru(g
5-C5H5)(PPh3)2(L2)][PF6] (6Ru)
–
ꢀ0.92
ꢀ1.00b ꢀ1.12
ꢀ1.15b ꢀ1.28
–
methanol, although shifts may be masked by the intense
absorption bands.
p–
p*
a
Attributed to a decomposition product originated by the irreversible oxidation.
Extremely weak.
b

M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
437
Table 4
acetonitrile the oxidation processes occurred at lower potential
as expected, namely Epa = 1.42 V (L1) and Epa = 1.12 V (compound
1). The reduction of L1 occurred at Epc = ꢀ1.70 V (Epa = ꢀ1.55 V)
and compound 1 was reduced at Epc = ꢀ1.30 V (Epa = ꢀ1.04 V). In
this solvent the polymerization process, leading to the deposition
on the electrode surface, was only observed for compound 1.
Compounds 3 and L2, were mostly characterized by two reduc-
tive irreversible processes in acetonitrile, due to the presence of
Electrochemical data for complexes [M(g
5-C5H5)(LL)(NC(C4H2S)C(H) C(H)(C4H2-
S)Z))][PF6] and for the organic compounds 1, 3, L1 and L2 in acetonitrile.
Compound
Epa
Epc
Ep1/2
Epa–Epc
Ia/
(V)
(V)
(V)
(mV)
Ic
1,2-di-(2-thienyl)-ethene (1)
1.12
–
–
–
–
–
–
–
–
–
–
–
–
ꢀ1.04 ꢀ1.30
2-Nitro-5-(2-thiophen-2-yl-vinyl)-
thiophene (3)
1.44
–
ꢀ0.83 ꢀ0.95
ꢀ1.53 ꢀ1.67
1.42
ꢀ0.89 120
the acceptor group NO2, at E1 = ꢀ0.95 V (Ep1cEp2a = ꢀ0.83 V) and
–
–
pc
E2pc = ꢀ1.67 V (Ep2a = ꢀ1.53 V) for compound 3 while these processes
became easier for L2 due to the presence of the second acceptor
group (N„C–) Ep1c = ꢀ0.91 V (Ep1a = ꢀ0.76 V) and Ep2c = ꢀ1.31 V
(E2pa = ꢀ1.16 V). In dichloromethane only the second reductive
process was found for compound 3, E2pc = ꢀ1.01 V (Ep2a = ꢀ0.83 V)
although L2 exhibits both processes in this solvent at E1pc = ꢀ0.98 V
(E1pa = ꢀ0.74 V) and Ep2c = ꢀ1.36 V (Ep2a = ꢀ1.15 V).
5-(2-Thiophen-2-yl-vinyl)-thiophene-
2-carbonitrile (L1)
–
–
ꢀ0.12a
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
ꢁ1
–
–
–
–
–
–
–
–
–
–
–
–
–
ꢁ1
–
–
–
–
–
–
ꢀ0.85a
ꢀ1.55 ꢀ1.70
[Ru(
g
5-C5H5)(DPPE)(L1)][PF6] (1Ru)
5-C5H5)(DPPE)(L1)][PF6] (1Fe)
1.41
1.12
–
–
0.98
ꢀ1.53b
ꢀ1.60 ꢀ1.75
[Fe(g
1.41
0.77
–
0.62
The electrochemical behaviour of the iron complexes 1Fe and
4Fe in dichloromethane is characterized by an irreversible process
at Ep1/2 = 0.83 V and Epa = 0.88 V for both complexes and attributed
to the Fe(II)/Fe(III) redox pair. This seems to indicate that the pres-
ence of the NO2 acceptor group in 4Fe has little influence on the
electron richness of the metal. It was also found that both com-
pounds L1 and L2 are easier to reduce as coordinated ligands than
as free compounds. The reduction process attributed to ligand L1,
occurs in compound 1Fe at Epc = ꢀ1.46 V, while no reduction oc-
curs for L1 as free compound, within the limits imposed by dichlo-
romethane. Similarly, the two reductive processes found for free
compound L2 at Ep1c = ꢀ0.98 V (Ep1a = ꢀ0.74 V) and Ep2c = ꢀ1.36 V
(E2pa = ꢀ1.15 V) became easier after coordination in compound
0.69 150
–
–
ꢀ1.46b
ꢀ1.73
1.27
–
–
–
–
[Ru(g
5-C5H5)(PPh3)2(L1)][PF6] (3Ru)
1.40
1.22
1.34 130
1.02
–
–
–
–
–
ꢀ1.46b
ꢀ1.59 ꢀ1.71
ꢀ1.65 120
5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-
thiophene-2-carbonitrile (L2)
1.18
–
–
–
–
–
–
–
–
–
ꢀ0.76 ꢀ0.91
ꢀ1.16 ꢀ1.31
[Ru(g
5-C5H5)(DPPE)(L2)][PF6] (4Ru)
1.13
0.98
ꢀ0.74 ꢀ0.86
ꢀ1.04 ꢀ1.14
ꢀ1.16 ꢀ1.28
ꢀ0.80 120
ꢀ1.09 100
ꢀ1.22 120
[Fe(g
5-C5H5)(DPPE)(L2)][PF6] (4Fe)
0.79
0.61
–
–
4Fe where E1pc = ꢀ0.86 V (Ep1a = ꢀ0.71 V) and E2pc = ꢀ1.18 V (E2pa
=
ꢀ0.73 ꢀ0.86
ꢀ0.79 130
ꢀ1.05 ꢀ1.17
ꢀ1.11 120
ꢀ1.03 V). Accordingly, it was found that the oxidation of L1 and
L2 compounds was more difficult as coordinated ligands. There-
fore, these observations all together indicate a regular dative sigma
[Ru(g
5-C5H5)(PPh3)2(L2)][PF6] (6Ru)
1.23
1.03
–
–
–
–
ꢀ0.73 ꢀ0.87
ꢀ1.03 ꢀ1.13
ꢀ1.18 ꢀ1.28
1.08 100
ꢀ1.23 100
coordination of both ligands, without any effect of
as was suggested by our spectroscopic data.
p backdonation
a
Attributed to a decomposition product originated by the irreversible oxidation.
Extremely weak.
b
The ruthenium(II) complexes show the same general behaviour
of the iron ones, except for the higher potential of the Ru(II)/Ru(III)
oxidation process, which being irreversible, present only very
small cathodic counterpart. Again, the metal centres seem unaf-
fected by the presence of the acceptor group in the coordinated
chromophore, as observed by comparison of Ru(II)/Ru(III) oxida-
tion potentials of 1Ru and 3Ru with the ones of 4Ru and 6Ru,
respectively.
mental conditions. Compounds 10Ru and 40Ru were not studied,
since the change of the counter-ion was not expected to influence
the electrochemical behavior of the complexes, when compared
with 1Ru and 4Ru, respectively. To complement our understanding
about the effect of the substituting groups on the electrochemical
behavior of the chromophores, the parent compound 1 and its ni-
tro derivative 3 (see Scheme 1) were also studied. Relevant data for
the redox changes exhibited by the studied compounds, in dichlo-
romethane and acetonitrile, are summarized in Table 3 and Table 4,
respectively.
The electrochemical behavior of organic compounds 1, 3, L1 and
L2 is characterized by one irreversible oxidation, with Epa ranging
from 1.23 V to 1.58 V in dichloromethane and from 1.12 V to
1.44 V in acetonitrile, without any cathodic counterpart. Although
this oxidation occurs at higher potentials for 3 and L1 than for the
parent compound 1, due to the presence of the acceptor groups
NO2 and NC, respectively, L2 does not follow the same trend, pre-
senting only one weak oxidation wave at a potential very similar to
1, (even lower in dichloromethane), suggesting the role of NC as a
weak donor group in the presence of the good acceptor NO2.
The cyclic voltammograms of the free ligand L1 and the parent
compound 1 (see Scheme 1) were quite similar in both solvents. In
dichloromethane, the oxidation occurred at Epa = 1.51 and 1.28 V,
respectively, with no cathodic counterpart. After few sweeps, some
additional oxidation and reduction broad waves were observed for
both compounds, attributed to the product deposition observed at
the platinum electrode surface, this being compatible with the ex-
pected potential-induced polymerization of thiophenes [32]. In
Fig. 4. Cyclic voltammograms of 4Fe (—) and L2 (ꢂ ꢂ ꢂ) ligand in acetonitrile.

438
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
On going to negative potentials, the electrochemical behaviour
of metal fragment. These results are in agreement with the better
donor character of the iron(II) fragment.
of the L1 coordinated chromophore in the complexes 1Ru, 1Fe
and 3Ru shows the presence of one cathodic wave at ꢀ1.50,
ꢀ1.46 and ꢀ1.49 V in dichloromethane and ꢀ1.75, ꢀ1.73 and
ꢀ1.71 V in acetonitrile, showing that the coordination of L1 either
to Ru(II) or to Fe(II) leads to a more difficult reduction. Compounds
with the L2 coordinated chromophore 4Ru, 4Fe and 6Ru present
also the reductive processes occurring at a little lower potential
than in the free ligand, due to the overall electron-withdrawing
effect of the ligand. This effect is more pronounced in the
second reduction potentials. The general electrochemical behav-
iour of these complexes is illustrated in Fig. 4, which shows the
comparison of 4Fe complex and the correspondent uncoordinated
ligand L2.
The HOMO–LUMO gaps estimated for compounds 4Ru and 4Fe
(Table 5) are similar to the values found for [M(
g
5-C5H5)(DPPE)-
(NC{C4H2S}3NO2)][PF6] complexes, C0 and C, in agreement with
the similar conjugation length of the chromophores. For both com-
plexes, the lower HOMO–LUMO gaps obtained in acetonitrile are
mainly due to the relative stabilization of the HOMO orbital in this
solvent, since the first reduction potential (LUMO), related to the
thiophene coordinated ligand, remain almost unchanged. This is
in disagreement with the large LUMO stabilizations verified for
compounds [MCp(DPPE)(NC{C4H2S}nNO2)][PF6] (n = 2, 3), specially
for the iron compounds, for which LUMO stabilizations of 90 mV
(B) and 100 mV (C) are verified, and this might be related to con-
formational changes in oligo-thiophene ligand structures due to
different solvent polarity, thus leading to a significant energy
lowering effect on LUMO. Ab initio calculations, suggesting that
terthiophene geometry are very sensitive to the chemical environ-
ment [27], and the fact that no LUMO stabilization is verified for
compound 4Fe, further supports this assumption. Although the
same trend is verified for the ruthenium analogues, LUMO stabili-
zations are lower, which may be attributed to the weaker donor
character of the [RuCp(DPPE)]+ moiety in relation to [FeCp(DPPE)]+,
leading to a lower push effect.
The voltammograms of complexes [Ru(
[PF6] (4Ru) and [Ru(
5-C5H5)(PPh3)2(L2)][PF6] (6Ru) in acetonitrile
revealed one additional third wave at Epa ꢃ ꢀ1.04 and Epc
g
5-C5H5)(DPPE)(L2)]-
g
ꢃ
ꢀ1.14 V which origin can possibly be explained by the formation
of a new product originated by substitution of the coordinated
phosphine, since this process was more evident in the case of the
compound with PPh3 as coligands. Also, the wave relative to the
oxidation RuII/RuIII showed some asymmetry compatible with
two oxidative processes. No further studies were carried out to
confirm this hypothesis, since the compounds are stable in the sol-
vents of interest for NLO measurements, namely dichloromethane
and chloroform.
The HOMO–LUMO gap can also be correlated with the solvato-
chromic behaviour in the electronic spectra of the complexes,
indicative of a bathochromic shift of the MLCT with increasing sol-
vent polarity, which is characteristic of electronic transitions with
an increase of the dipole moment upon photo-excitation. However,
in the present case, solvatochromic behaviour of the MLCT band
could not be clearly identified due to overlapping of this transition
with the one attributed to the coordinated thiophene ligand.
Also, it might be of interest the comparison of the M(II)/M(III)
oxidation potentials of compounds 4Fe and 4Ru to the oxidation
potentials of the related sets of iron(II) (A, B and C) and ruthe-
nium(II) (A0, B0 and C0) derivatives in which the oligo-thiophene
chromophores present 2, 4 and 6 double bonds, as presented in
Table 5. Although the increase in conjugation length leads to a
decrease in M(II)/M(III) oxidation potential within the series of
In view of the comparison of the compounds studied in this
work to other related metallothiophene derivatives for which some
studies of second-order nonlinear optics were performed [26], it is
of interest to evaluate the HOMO–LUMO gap, expressed by the
difference between the first oxidation and reduction potentials.
As assumed before [26], the M(II)/M(III) oxidation and the first
reduction potential can be related, respectively, to the relative
magnitude of the HOMO and the LUMO energies. This assumption
considers that the HOMO is essentially located in the metal frag-
ment and the LUMO in the nitrile ligand, as showed by the
Extended Hückel MO calculations performed in other similar com-
plexes containing p-benzonitrile derivatives [12]. In the present
work the HOMO–LUMO gap was estimated for compounds 4Ru
and 4Fe and the results are presented in Table 5, together with
the values already reported for other related thiophene derivatives
[26,33].
The data show that the HOMO–LUMO gap depends on the metal
fragment and the solvent used in the electrochemical experiments.
The HOMO–LUMO gap is higher for the ruthenium complex 4Ru
than for the iron derivative 4Fe, with differences of 0.41 V and
0.37 V in dichloromethane and acetonitrile, respectively. This is
mainly due to the stabilization of the HOMO orbital for the ruthe-
nium complex, since the LUMO is almost unaffected by the change
compounds [M(g
5-C5H5)(DPPE)(NC{C4H2S}nNO2)][PF6] [26,33],
compounds 4Ru and 4Fe do not follow this trend, showing higher
oxidation potentials, in both solvents, than compounds B0 and B,
respectively, despite the increase in conjugation length. This is
clearly illustrated in Fig. 5, which presents the variation of the
M(II)/M(III) oxidation potentials with the number of double bonds
of the chromophore, showing that the electronic density of the me-
tal centre is less than expected attending only to chromophores
conjugation length and suggesting improved metal–chromophore
conjugation for compounds 4Fe and 4Ru.
Table 5
Estimation of HOMO–LUMO gap based on electrochemical data for selected compounds.
Compound
Eox (V)
Ered (V)
HOMO–LUMO (V)
CH2Cl2
CH2Cl2
CH3CN
CH2Cl2
CH3CN
CH3CN
[FeCp(dppe)(L2)][PF6] (4Fe)
0.88
0.91
0.85
0.81
1.27
1.33
1.23
1.22
0.79
0.83
0.76
0.75
1.13
1.16
1.12
1.11
ꢀ0.86
ꢀ0.66
ꢀ0.86
ꢀ0.94
ꢀ0.88
ꢀ0.65
ꢀ0.82
ꢀ0.91
ꢀ0.86
ꢀ0.64
ꢀ0.77
ꢀ0.84
ꢀ0.86
ꢀ0.62
ꢀ0.79
ꢀ0.87
1.74
1.57
1.71
1.75
2.15
1.98
2.05
2.13
1.65
1.47
1.55
1.59
1.99
1.78
1.91
1.98
[FeCp(dppe)(NC{C4H2S}NO2)][PF6]a
A
B
C
[FeCp(dppe)(NC{C4H2S}2NO2)][PF6]a
[FeCp(dppe)(NC{C4H2S}3NO2)][PF6]a
[RuCp(dppe)(L2)][PF6] (4Ru)
[RuCp(dppe)(NC{C4H2S}NO2)][PF6]b A0
[RuCp(dppe)(NC{C4H2S}2NO2)][PF6]b B0
[RuCp(dppe)(NC{C4H2S}3NO2)][PF6]b C0
a
Ref. [26].
Ref. [33].
b

M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
439
Fig. 6. Molecular diagram of cation 10Ru showing the numbered atoms.
[PF6] (40Ru), obtained by slow diffusion of n-hexane in dichloro-
methane solutions of compounds 10Ru and 1Fe and n-hexane/
acetone for 40Ru. Compounds 1Fe, and 40Ru crystallized in the
monoclinic spatial groups C2/c and P21/n, respectively and com-
pound 10Ru in the orthorhombic Pbca spatial group. Selected bond
distances and bond and torsion angles for these three compounds
are presented in Table 6, and molecular schemes and numbering
are depicted in Figs. 6–8.
Fig. 5. Variation of RuII/RuIII (d) and FeII/FeIII (j) oxidation potentials with the
number of chromophore double bonds of compounds [M(
g
5-C5H5)(DPPE)-
(NC{C4H2S}nNO2)][PF6] [26,33] and 4Ru/4Fe, in dichloromethane.
Table 6
All the complexes present a distorted three-legged piano stool
geometry around the metal atom, confirmed by the P–M–P and
Selected bond lengths [Å] and bond and torsion angles [°].
Bond lengths
10Ru
40Ru
1Fe
(C„)N–M–P angles close to 90°, with the remaining C(
g
5-cen-
M–Cpa
M–N(1)
N(1)–C(1)
C(1)–C(2)
C(2)–S(1)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(5)–S(1)
C(5)–C(6)
C(6)–C(7)
C(7)–C(8)
C(8)–S(2)
C(8)–C(9)
C(9)–C(100)
C(100)–C(101)
C(101)–S(2)
M(1)–P(1)
1.8575(3)
2.016(3)
1.151(5)
1.414(5)
1.736(4)
1.376(6)
1.409(6)
1.377(7)
1.733(4)
1.453(6)
1.343(7)
1.456(6)
1.719(5)
1.367(7)
1.421(8)
1.326(10)
1.710(8)
2.2834(10)
2.2913(11)
1.8593(5)
1.997(5)
1.148(8)
1.436(10)
1.700(8)
1.368(11)
1.398(11)
1.323(12)
1.715(8)
1.426(11)
1.295(14)
1.464(14)
1.702(12)
1.300(17)
1.303(17)
1.41(2)
1.685(12)
2.2803(16)
2.2724(17)
1.7061(12)
1.865(8)
1.164(11)
1.404(13)
1.717(9)
1.347(12)
1.374(13)
1.363(12)
1.721(8)
1.438(12)
1.327(13)
1.438(13)
1.715(9)
troid)-M-N(„C) and C(
g
5-centroid)-M–P angles between 124.0°
and 130.15°. The dihedral angles between the planes of the thio-
phene rings in compounds 1Fe (7.06°) and 40Ru (8.39°) are clearly
lower than the corresponding ones in the related compounds
[RuCp(DPPE)(NC{C4H2S}2NO2)][PF6] (17.6°) [33] and [RuCp(DPPE)
(NC{C6H4}2NO2)][PF6] (14.47°) [34]. This observation is in agree-
ment with the chromophore’s planarity improvement predicted
for the present compounds and suggests that dihedral angle be-
tween thiophene rings may in fact have some influence in the loss
of charge transfer efficiency with increasing conjugated length sug-
gested for compounds [FeCp(DPPE)(NC{C4H2S}nNO2)][PF6] (n = 2,
3) [26]. For compound 10Ru the dihedral angle is 17.64°, clearly
superior to the ones found for 1Fe and 40Ru, which might be ex-
plained by inferior conjugation along the chromophore in 10Ru
due to the combination of the organometallic donor [RuCp-
(DPPE)]+, a worst donor in relation to the iron analogue in 1Fe,
and L1, in which the acceptor group is absent in relation to 40Ru.
All the Ru compounds show bond distances Ru–N as well the
N–C placed in the range of the ones found for similar cyclope-
ntadienyldiphosphine complexes with thiophene based nitrile li-
gands (Ru–N 1.977–2.023 Å and N–C 1.139–1.178 Å) but smaller,
in general, than the ones found in cyclopentadienyldiphosphine
complexes with NCPh ligands presented on Table 7. Despite the
fact that some results, such as for example Ru–N distances, might
1.337(13)
1.409(15)
1.319(15)
1.701(11)
2.210(3)
M(1)–P(2)
2.201(3)
Angles
N(1)–M(1)–P(1)
N(1)–M(1)–P(2)
P(2)–M(1)–P(1)
Cpa–M(1)–N(1)
Cpa–M(1)–P(1)
Cpa–M(1)–P(2)
M(1)–N(1)–C(1)
N(1)–C(1)–C(2)
Torsion angles
M(1)–N(1)–C(1)–C(2)
N(1)–C(1)–C(2)–C(3)
N(1)–C(1)–C(2)–S(1)
C(1)–C(2)–C(3)–C(4)
C(5)–C(6)–C(7)–C(8)
86.38(9)
92.67(10)
84.17(4)
125.43(7)
129.66(2)
125.56(2)
178.2(3)
177.8(4)
89.12(16)
89.84(16)
84.35(6)
126.55(14)
128.93(5)
126.91(5)
175.8(5)
86.5(2)
91.6(2)
86.95(10)
124.0(2)
130.15(9)
125.17(8)
175.4(7)
176.3(10)
176.4(7)
75(18)
ꢀ7(21)
39(23)
suggest some evidence for
p backdonation for the present com-
122(13)
ꢀ55(13)
ꢀ177.4(4)
173.0(4)
93(14)
ꢀ90(15)
pounds, compared to other related nitriles, a careful study of the
other coordination geometrical parameters do not led us to any
conclusion or evidence about the significance of this effect.
For 1Fe, although NC bond distance (1.164(11) Å) is somewhat
higher than for compound 10Ru (1.151(5) Å), and C1–C2 distance
somewhat shorter (1.404(13) Å versus 1.414(5) Å for 10Ru) sug-
ꢀ82(14)
ꢀ174.3(7)
179.0(8)
88(15)
177.2(9)
ꢀ178.0(9)
a
Cp centroid.
2.5. X-ray structural studies
gesting some evidence for p-backdonation supported also by the
spectroscopic data, no conclusions can be drawn due to the large
X-ray diffraction studies were performed on single crystals of the
new compounds [Ru(
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))]-
[PF6] (10Ru) [Fe( 5-C5H5)(DPPE) (NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
(1Fe) and [Ru(
5-C5H5)(DPPE)(NC(C4H2S)C(H) C(H)(C4H2S)NO2)]-
error associated to 1Fe bond distances.
g
The bond angles M–N„C of the studied compounds present
only a slight deviation of the linearity, with values in accordance
to the ones found for related compounds (see Table 7).
g
g

440
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
Fig. 7. Molecular diagram of cation 40Ru, showing the numbered atoms.
Fig. 8. Molecular diagram of cation 1Fe, showing the numbered atoms, done with MERCURY. The ellipsoids are not shown due to severe anisotropy in some atoms.
Table 7
Selected geometrical parameters for ruthenium and iron derivatives containing CpM(phosphine)nitrile cations and the ones presented in this work.
Compound
M–N (Å)
N–C (Å)
C–C (Å)
M–N–C (°)
N–C–C (°)
[RuCp(DPPE)(L1)][CF3SO3] (10Ru)
[RuCp(DPPE)(L2)][CF3SO3] (40Ru)
[RuCp(PPh3)2(NCPh)][PF6]a
1.8575(3)
1.997(5)
2.037(1)
2.023(2)
2.031(1)
2.030(3)
1.995(6)
2.025(5) 2.016(6)
2.018(4)
2.002(5)
1.865(8)
1.892(2)
1.874(11)
1.875 (13)
1.902(9)
1.151(5)
1.148(8)
1.145(2)
1.146(2)
1.149(2)
1.136(5)
1.117(10)
1.153(8), 1.151(9)
1.149(6)
1.144(6)
1.164(11)
1.141(3)
1.129(14)
1.390 (19)
1.12(15)
1.414(5)
1.436(10)
1.440(2)
1.442(3)
1.424(2)
1.441(6)
1.464(12)
1.402(9), 1.416(10)
1.400(7)
1.411(7)
1.404(13)
1.444(3)
1.42(2)
178.2(3)
175.8(5)
177.8(4)
176.4(7)
177.84(16)
177.8(2)
175.15(18)
177.7(4)
176.0(9)
173.4(7), 178.6(7)
176.3(6)
177.1(7)
176.3(10)
174.5(2)
171.70(12)
171.24(15)
173.52(14)
177.4((3)
176.6(7)
176.3(5) 169.8(6)
176.7(4)
175.4(5)
[RuCp(PPh3)2(NCPhNO2)][PF6]a
[RuCp(PPh3)2(NCPhNMe2)][PF6]a
[RuCp(DPPE)(NCPh2NO2)][PF6]b
[RuCp(PPh3)2(NC{BDT})][PF6]c
[RuCp(PPh3)2(NC{BDT})][CF3SO3]c
[RuCp(DPPE)(NC{BDT})][PF6]c
[RuCp(DPPE)(NC{C4H2S}2NO2)][PF6]d
[FeCp(DPPE)(L1)][CF3SO3] (1Fe)
[FeCp(DPPE)(NCPh)][PF6]a
175.4(7)
172.16(18)
176.6(11)
175.6 (11)
172.0(10)
176.6(4)
[FeCp(DPPE)(NCC6H4NO2)][PF6]e
[FeCp(DPPE)(NCPhNO2)]If
177.4(15)
178.0 (16)
172.8(13)
178.1(5)
1.40 (2)
1421(15)
1.427(8)
[FeCp (PROPHOS)(NCPhNO2)][PF6]g
[FeCp(DPPE)(NC{BDT})][PF6]c
1.8639(4)
1.154(6)
BDT = benzo[1,2-b;4,3-b0]dithiophene; PROPHOS_ (R)-(_)-1,2-bis(diphenylphosphino)propane.
a
Ref. [35].
Ref. [34].
Ref. [31].
Ref. [33].
Ref. [12].
Ref. [36].
Ref. [37].
b
c
d
e
f
g

M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
441
Table 8
Details of data collection and structure refinement for compound 10Ru.
Compound
10Ru
40Ru
1Fe
Chemical formula
Molecular weight
T (K)
C43H36F3NO3P2RuS3
930.92
150(2)
C43H35F3N2O5P2RuS3
975.92
150(2)
C42H36F6FeNS2P3
881.60
293(2)
Wavelength
Crystal system
Space group
a (Å)
b (Å)
c (Å)
0.71069
Orthorhombic
Pbca
17.2060(17)
20.266(2)
23.493(3)
0.71069
Monoclinic
P2(1)/n
10.7230(5)
8.5910(4)
50.918(2)
95.734(3)
4667.2(4)
4
0.71069
Monoclinic
C2/c
26.486(3)
23.188(2)
16.616(2)
125.828(10)
8273.9(17)
8
b (°)
–
V (Å3)
8191.9(16)
8
1.510
Z
Dcalc (g cmꢀ3
)
1.389
0.594
1.415
0.640
Absorption coefficient (mmꢀ1
)
0.668
F(000)
3792
1984
3616
h Range for data collection (°)
Limiting indices
1.78–30.68
ꢀ24 6 h 6 14;
ꢀ26 6 k 6 29;
ꢀ33 6 l 6 33
74122/12617
[Rint = 0.0661]
30.68 (99.4%)
Full-matrix least-squares on F2
12617/0/513
1.021
2.86–25.37
ꢀ12 6 h 6 11;
ꢀ10 6 k 6 10;
ꢀ60 6 l 6 61
58030/8483
[Rint = 0.0502]
25.37 (99.0%)
2.59–25.35
ꢀ31 6 h 6 25;
ꢀ27 6 k 6 0;
0 6 l 6 20
7828/7549
[Rint = 0.0770]
25.35 (99.9%)
Reflections collected/unique
Completeness to h
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
8483/0/540
1.115
7549/350/510
1.001
Final R indices [I > 2
r
(I)]
R1 = 0.0454;
wR2 = 0.1030
1.207/ꢀ1.014
R1 = 0.0764;
wR2 = 0.1874
1.046/ꢀ1.318
R1 = 0.0899;
wR2 = 0.1879
0.616/ꢀ0.521
Largest difference in peak/hole (e Åꢀ3
)
Detailed analysis of the geometric parameters in the three com-
pounds, led us to notice that in compounds 10Ru, 40Ru and 1Fe, the
plane of the thiophene ring closest to the metal centre is almost
perpendicular in relation to the plane defined by the metal atom,
the centroid of the cyclopentadienyl and the N1 and C1 atoms
making a dihedral angle of 76.99(6)° and 80.66(27)° 82.83(19)°,
respectively. As discussed before [31], the referred angle seems
to depend on the interplay of energetic stability and stereochemi-
cal hindrance, with parameters such as the cone angle and mono or
bidentate behaviour of the coordinated phosphine, size of the chro-
mophore and supramolecular interactions in the crystal packing,
playing an important role.
following the methods described in the literature: [Ru(
(DPPE)Cl] and [Ru(
5-C5H5)(PPh3)2Cl] [39], [Fe( 5-C5H5)(DPPE)I]
[12], [Ru(
5-C5H5)(TMEDA)Cl] [40], 1,2-di-(2-thienyl)-ethene
g
5-C5H5)
g
g
g
[29]. Solid state IR spectra were taken on a Mattson Satellite FTIR
spectrophotometer with KBr pellets; only significant bands are ci-
ted in the text. 1H, 13C and 31P NMR spectra were recorded on a
Bruker Avance 400 spectrometer at probe temperature. The 1H
and 13C chemical shifts are reported in parts per million (ppm)
downfield from internal Me4Si and the 31P NMR spectra are re-
ported in ppm downfield from external standard H3PO4 85%. Cou-
pling constants are reported in Hz. Spectral assignments of the
organic ligands follow the numbering scheme shown in Fig. 1.
Electronic spectra were recorded at room temperature on a
Jasco V-560 spectrometer in the range of 200–900 nm. Microanalyses
were performed using a Fisons Instruments EA1108 system. Data
acquisition, integration and handling were performed using a PC with
the software package Eager-200 (Carbo Erba Instruments).
3. Conclusions
A new family of Ru(II) and Fe(II) three-legged piano stool com-
plexes was synthesised and fully characterized. Spectroscopic and
electrochemical data show that 1,2-di-(2-thienyl)-ethene moiety
allows an improved electron-donor effect from the metal centre
towards NO2 acceptor group. Also, electrochemical and crystallo-
graphic data show improved planarity of the chromophore, allow-
ing a superior conjugation between the metal centre and the
acceptor group, despite the increase in conjugation length. Thus,
we are expecting improved NLO properties for these compounds,
compared with our related published compounds possessing oli-
go-thiophene nitrile derived ligands. Studies of the molecular
hyperpolarizability b by Hyper Rayleigh Scattering (HRS) for this
new family of compounds are currently in progress.
4.2. Synthesis of the ligands
4.2.1. 5-(2-Thiophen-2-yl-vinyl)-thiophene-2-carbaldehyde (2)
1,2-Di-(2-thienyl)-ethene (1.9 g, 10 mmol) was dissolved in 1,
2-dichloroethane (20 mL) and DMF (1.1 mL, 12 mmol). The solution
was cooled to 5 °C and POCl3 (1.5 mL, 12 mmol) was added drop-
wise. The mixture was then heated to reflux for 4 h. After cooling,
50 mL of saturated solution of NaCO2CH3 were added and the mix-
ture was stirred for a further hour. The mixture was then extracted
with dichloromethane, washed with a saturated solutionof NaHCO3,
wateranddriedovermagnesiumsulphate. Thesolventwasremoved
under vacuum and the product was purified by flash column chro-
matography (eluent: light petroleum/dichloromethane 6:4) to give
1.8 g (82%) of the desired product as yellow needles. IR (KBr,
4. Experimental
cmꢀ1):
m
(C@O) 1655 cmꢀ1. 1H NMR (Acetone-d6): 7.01(m, 1H, H10),
4.1. General procedures
7.21(d, 1H, H7, 3JHH = 16.0 Hz), 7.31(d, 1H, H9, 3JHH = 3.4 Hz), 7.36(d,
3
3
1H, H4, JHH = 3.9 Hz), 7.48(d, 1H, H6, JHH = 16.0 Hz), 7.49(d, 1H,
All the experiments were carried out under dinitrogen atmo-
sphere using standard Schlenk techniques. All solvents were dried
using standard methods [38]. Starting materials were prepared
3
H11
,
3JHH = 5.2 Hz), 7.88(d, 1H, H3, JHH = 3.9 Hz), 9.91(s, 1H, CHO).
13C NMR (Acetone-d6): 120.20(C2), 125.63(C6), 126.49(C11),

442
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
127.19(C4), 128.09(C10), 128.45(C9), 137.94(C3), 141.38(C8),
141.79(C5), 151.29(C2), 182.69(CHO). Anal. Found: C, 59.92; H,
3.72%. Calc. for C11H8OS2: C, 59.97; H, 3.66(%).
4.2.5. 5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile
(L2)
A solution of H2NOH ꢂ HCl (1.4 g, 20 mmol) in pyridine (4 mL)
was added to a solution of 5-[2-(5-nitro-thiophen-2-yl)-vinyl]-thi-
ophene-2-carbaldehyde (2.7 g, 10 mmol) in pyridine (20 mL),
cooled to 5 °C. After stirring for 5 min at that temperature, acetic
anhydride (10 mL) was added and the mixture was refluxed for
1 h. After cooling, the mixture was poured onto ice and the precip-
itate formed was filtered, washed with water, dissolved in dichlo-
romethane and dried over magnesium sulphate. The solvent was
removed under vacuum and the product was purified by flash
column chromatography (eluent: light petroleum/dichlorometh-
ane 1:1) to give 2.3 g (86%) of the desired product as light yellow
4.2.2. 5-(2-Thiophen-2-yl-vinyl)-thiophene-2-carbonitrile (L1)
AsolutionofH2NOH ꢂ HCl(1.4 g, 20 mmol)inpyridine(4 mL)was
added to a solution of 5-(2-thiophen-2-yl-vinyl)-thiophene-2-carb-
aldehyde (2.2 g, 10 mmol) in pyridine (20 mL), cooled to 5 °C. After
stirring for 5 min at that temperature, acetic anhydride (10 mL)
was added and the mixture was refluxed for 1 h. After cooling, the
mixture was poured onto ice and the precipitate formed was filtered,
washed with water, dissolved in dichloromethane and dried over
magnesium sulphate. The solvent was removed under vacuum and
the product was purified by flash column chromatography (eluent:
light petroleum/dichloromethane 7:3) to give 1.9 g (90%) of the de-
needles. IR (KBr, cmꢀ1):
(NO2) 732;. 1H NMR (Acetone-d6): 7.44(d, 1H, H9, JHH = 4.3 Hz),
m(CN) 2214; m(NO2) 1483 and 1337; d
3
3
3
sired product as light yellow needles. IR (KBr, cmꢀ1):
m(N„C)
7.51(d, 1H, H4, JHH = 3.2 Hz), 7.53(d, 1H, H6, JHH = 16.0 Hz),
3
3
2217. 1H NMR (Acetone-d6): 7.09(m, 1H, H10), 7.21(d, 1H, H7,
7.69(d, 1H, H7, JHH = 16.0 Hz), 7.96(d, 1H, H3, JHH = 3.2Hz),
8.12(d, 1H, H10
,
3JHH = 4.3 Hz). Anal. Found: C, 50.31; H, 2.33; N,
3
3JHH = 16.0 Hz), 7.31(d, 1H, H4, JHH = 3.9 Hz), 7.32(d, 1H, H9,
3
3JHH = 3.4 Hz), 7.44(d, 1H, H6, JHH = 16.0 Hz), 7.49(d, 1H, H11
,
10.41%. Calc. for C11H6S2N2O2: C, 50.37; H, 2.31; N, 10.68(%).
3JHH = 5.1 Hz), 7.75(d, 1H, H3, 3JHH = 3.9 Hz). 13C NMR (Acetone-d6):
106.48(C2), 114.00(CN), 119.15(C7), 125.54(C6), 126.22(C9),
126.48(C11), 128.06(C10), 128.46(C4), 138.87(C3), 141.15(C8),
149.59(C5). Anal. Found: C, 60.46; H, 3.37; N, 6.13%. Calc. for
C11H7NS2: C, 60.80; H, 3.25; N, 6.45(%).
4.3. Synthesis of the complexes
4.3.1. Preparation of [M(
(NC(C4H2S)C(H)C(H)(C4H2S)Z)][Y]
Complexes [M(
5-C5H5)(LL)(NCR)][Y] were prepared by halide
abstraction from the parent neutral complexes [M(
5-C5H5)(LL)X]
g
5-C5H5)(LL)
g
4.2.3. 2-Nitro-5-(2-thiophen-2-yl-vinyl)-thiophene (3)
g
HNO3 (0.70 mL, 10 mmol) was added to a solution of 1,2-di-(2-
thienyl)-ethene (1.9 g, 10 mmol) in acetic acid (AcOH) (40 mL).
After stirring for 2 h, the mixture was poured onto ice (100 mL).
The precipitate was filtered, dissolved in dichloromethane, washed
with a saturated solution of NaHCO3 and water, dried with magne-
sium sulfate and pumped to dryness. The product was recrystal-
lized from ethanol to give 1.2 g (51%) of the pure product as
(1 mmol) with TlPF6 or AgCF3SO3(1 mmol) in dichloromethane, in
the presence of a slight excess of the ligand (1.1 mmol), at room
temperature, for 16 h under inert atmosphere. After cooling to
room temperature, filtering and removing the solvent, the com-
plexes were washed with n-hexane (3 ꢄ 15 mL) and recrystallized
from acetone or dichloromethane/n-heptane, n-hexane or diethyl
ether giving crystalline products.
orange-red needles. IR (KBr, cmꢀ1):
m(NO2) 1487 and 1320;
d(NO2) 710; 1H NMR (Acetone-d6): 7.13(m, 1H, H3), 7.21(d, 1H,
4.3.1.1.
(1Ru). Yellow; recrystallized from CH2Cl2/(n-heptane); 75% yield;
[Ru(g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
3
3
H6, JHH = 16.0 Hz), 7.30(d, 1H, H9, JHH = 4.3 Hz), 7.37(d, 1H, H4,
3JHH = 3.4 Hz), 7.54(d, 1H, H2, JHH = 5.0 Hz), 7.60(d, 1H, H6,
3
IR (KBr, cmꢀ1): as(OSO, CF3SO3ꢀ) 1250; 1H NMR (Ace-
m(CN) 2212, m
3JHH = 16.0 Hz), 7.98 (d, 1H, H10 3JHH = 4.3 Hz). 13C NMR (Acetone-
,
tone-d6): 2.71(m, 2H, –CH2–), 2.84(m, 2H, –CH2–), 5.04(s, 5H, g5
-
d6): 119.39(C6), 125.42(C7), 126.82(C2), 127.24(C9), 128.20(C3),
129.17(C4), 130.20(C10), 141.00(C5), 148.91(C8), 150.26(C11). Anal.
Found: C, 50.46; H, 2.78; N, 6.03%. Calc. for C10H7S2NO2: C, 50.62;
H, 2.97; N, 5.90(%).
3
C5H5), 6.76(d, 1H, H3, 3JHH = 4.0 Hz), 7.07(d, 1H, H7, JHH = 16.0 Hz),
3
7.09(d, 1H, H9, JHH = 4.0 Hz), 7.10(m, 1H, H10), 7.28(d,1H, H4,
3JHH = 4.0 Hz), 7.30(d, 1H, H6, JHH = 16.0 Hz), 7.51(d, 1H, H11,
3
3JHH = 4.8 Hz), 7.51(m, 10H, C6H5(DPPE)), 7.63(m, 6H, C6H5(DPPE)),
8.02(m, 4H, C6H5(DPPE)). 13C NMR (Acetone-d6): 27.59(–CH2–,
DPPE), 82.57(g
5-C5H5), 105.46(C2), 118.63(C7), 121.18(CN),
4.2.4. 5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbaldehyde
(4)
125.68(C4), 125.92(C6), 126.84(C11), 128.01(C10), 128.76(C9),
129.05(CH, DPPE), 131.08(CH, DPPE), 133.26(CH, DPPE),
137.62(Cq, DPPE), 139.47(C3), 140.93(C8), 150.50(C5). 31P NMR
(Acetone-d6): 79.1(s, DPPE). Anal. Found: C, 53.39; H, 4.14; N,
1.48%. Calc. for C42H36NS2P3F6Ru ꢂ 0.3CH2Cl2: C, 53.35; H, 3.87; N,
1.47(%).
2-Nitro-5-(2-thiophen-2-yl-vinyl)-thiophene (2.4 g, 10 mmol)
was dissolved in 1,2-dichloroethane (20 mL) and DMF (1.1 mL,
12 mmol). The solution was cooled to 5 °C and POCl3 (1.5 mL,
12 mmol) was added dropwise. The mixture was then heated to re-
flux for 24 h. After cooling, 50 mL of a saturated solution of Na-
CO2CH3 were added and the mixture was stirred for a further
hour. The mixture was then extracted with dichloromethane,
washed with saturated solution of NaHCO3, water and dried over
magnesium sulphate. The solvent was removed under vacuum
and the product was purified by flash column chromatography
(eluent: light petroleum/dichloromethane 1:1) to give 2.0 g (75%)
4.3.1.2.
(10Ru). Yellow; recrystallized from CH2Cl2/(n-heptane); 75% yield;
IR (KBr, cmꢀ1): as(OSO, CF3SO3ꢀ) 1250; 1H NMR
(CN) 2212,
[Ru(g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))][CF3SO3]
m
m
(Acetone-d6): 2.70(m, 2H, –CH2–), 2.80(m, 2H, –CH2–), 5.02(s,
3
5H,
g
5-C5H5), 6.77(d, 1H, H3, JHH = 4.0 Hz), 7.05(d, 1H, H7,
of the desired product as yellow needles. IR (KBr, cmꢀ1):
1658;
(NO2) 1484 and 1324; d (NO2) 730; 1H NMR (DMSO-d6):
7.43(d, 1H, H4, J = 3.9 Hz), 7.52(d, 1H, H6, JHH = 16.0 Hz), 7.53(d,
m(C@O)
3
3JHH = 16.0 Hz), 7.10(d, 1H, H9, JHH = 4.0 Hz), 7.14(m, 1H, H10),
7.27(d, 1H, H4, JHH = 4.0 Hz), 7.32(d, 1H, H6, JHH = 16.0 Hz),
3
3
m
3
3
7.49(d, 1H, H11, JHH = 4.8 Hz), 7.52(m, 10H, C6H5(DPPE)), 7.67(m,
3
3
6H, C6H5(DPPE)), 8.07(m, 4H, C6H5(DPPE)). 13C NMR (Acetone-
1H, H4, JHH = 4.3 Hz), 7.66(d, 1H, H7, JHH = 16.0 Hz), 7.96(d, 1H,
H3, JHH = 3.9 Hz), 8.02(d, 1H, H10,
3JHH = 4.3 Hz), 9.97(s, 1H, CHO).
3
d6): 27.59(–CH2–, DPPE), 82.57(g
5-C5H5), 105.46(C2), 118.63(C7),
13C NMR (Acetone-d6): 124.30(C6), 126.36(C7), 127.93(C4),
130.23(C9), 131.51(C10), 139.19(C3), 143.26(C8), 143.35(C5),
149.49(C11), 149.74(C2), 184.63(CHO). Anal. Found: C, 50.89; H,
2.33; N, 5.30%. Calc. for C11H7S2NO3: C, 49.80; H, 2.66; N, 5.28(%).
121.18(CN), 125.68(C4), 125.92(C6), 126.84(C11), 128.01(C10),
128.76(C9), 129.05(CH, DPPE), 131.08(CH, DPPE), 133.26(CH,
DPPE), 137.62(Cq, DPPE), 139.47(C3), 140.93(C8), 150.50(C5). 31P
NMR (Acetone-d6): 79.1(s, DPPE). Anal. Found: C, 55.21; H, 3.82;

M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
443
N, 1.51%. Calc. for C43H36NS3P2F3O3Ru: C, 55.48; H, 3.90; N,
1.50(%).
4.3.1.7.
[Ru(
g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H2S)-
NO2)][CF3SO3] (40Ru). Yellow; recrystallized from CH2Cl2/(n-hex-
ane); 77% yield; IR (KBr, cmꢀ1):
m(CN) 2214,
m
as(OSO, CF3SOꢀ)
3
1
4.3.1.3.
(1Fe). Orange-red; recrystallized from CH2Cl2/(n-hexane); 90%
yield; IR (KBr, cmꢀ1): (PF6ꢀ) 839; 1H NMR (Ace-
(CN) 2197,
tone-d6): 2.66(m, 2H, –CH2–), 2.80(m, 2H, –CH2–), 4.67(s, 5H, g5
[Fe(g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
1243; H NMR (Acetone-d6): 2.70(m, 2H, –CH2–), 2.80(m, 2H, –CH2–),
3
5.02(s, 5H,
g
5-C5H5), 6.82(d, 1H, H3, JHH = 4.0 Hz), 7.20(d, 1H, H4,
3JHH = 4.0 Hz), 7.33(d, 1H, H6, JHH = 16.0 Hz), 7.36(d, 1H, H9,
3
m
m
3
-
3JHH = 4.4 Hz), 7.47(d, 1H, H7, JHH = 16.0 Hz), 7.50(m, 10H,
3
3
C5H5), 6.72(d, 1H, H3, JHH = 4.0 Hz), 7.04(d, 1H, H4, JHH = 4.0 Hz),
C6H5(DPPE)), 7.63(m, 6H, C6H5(DPPE)), 8.00(d, 1H, H10,
3
7.04(d, 1H, H7, JHH = 16.0 Hz), 7.08(m, 1H, H10), 7.24(d, 1H, H6,
3JHH = 4.3 Hz), 8.03(m, 4H, C6H5(DPPE)). 13C NMR (Acetone-d6):
3JHH = 16.0 Hz), 7.27(d, 1H, H9, JHH = 3.6 Hz), 7.48(d, 1H, H11,
27.64(–CH2–, DPPE), 82.69(g
5-C5H5), 107.70(C2), 120.68(CN),
3
3JHH = 5.1 Hz), 7.56(m, 10H, C6H5(DPPE)), 7.64(m, 6H, C6H5(DPPE)),
8.07(m, 4H, C6H5(DPPE)). 13C NMR (Acetone-d6): 28.47(–CH2–,
123.91(C6), 124.15(C7), 127.32(C9), 127.85(C4), 128.98(CH, DPPE),
130.40(C10), 131.07(CH, DPPE), 133.30(CH, DPPE), 137.33(Cq,
DPPE), 139.68(C3), 148.24(C5), 148.59(C8), 148.76(C11). 31P NMR
(Acetone-d6): 79.0(s, DPPE). Anal. Found: C, 52.85; H, 3.84; N,
2.80%. Calc. for C43H35N2S3O5P2F3Ru: C, 52.97; H, 3.61; N, 2.87(%).
DPPE), 81.05(g
5-C5H5), 107.18(C2), 119.81(C7), 126.53(C4),
126.56(C6), 127.63(C11), 128.89(CN), 129.03(C10), 129.58(C9),
130.12(CH, DPPE), 132.44(CH, DPPE), 133.91(CH, DPPE),
137.63(Cq, DPPE), 140.18(C3), 141.89(C8), 150.62(C5). 31P NMR
(Acetone-d6): ꢀ144.1(qt, JP,F = 710.2 Hz, PFꢀ) 97.0(s, DPPE). Anal.
4.3.1.8.
(4Fe). Orange-red; recrystallized from CH2Cl2/(n-hexane); 93%
yield; IR (KBr, cmꢀ1): (PFꢀ6 ) 839; 1H NMR (Acetone-
(CN) 2193,
d6): 2.67(m, 2H, –CH2–), 2.84(m, 2H, –CH2–), 4.70(s, 5H,
5-C5H5),
6.79(d, 1H, H3, JHH = 4.0 Hz), 7.21(d, 1H, H4, JHH = 4.0 Hz), 7.29(d,
[Fe(g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H2S)NO2)][PF6]
1
6
Found: C, 55.55; H, 4.18; N, 1.55%. Calc. for C42H36NS2P3F6Fe ꢂ
0.5CH2Cl2: C, 55.24; H, 4.04; N, 1.52(%).
m
m
g
3
3
4.3.1.4.
(2Ru). Dark-orange; recrystallized from CH2Cl2/(n-hexane); 50%
yield; IR (KBr, cmꢀ1): (PFꢀ6 ) 839; 1H NMR (Acetone-
(CN) 2193,
[Ru(g
5-C5H5)(TMEDA)(NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
3
3
1H, H6, JHH = 16.0 Hz), 7.36(d, 1H, H9, JHH = 4.3 Hz), 7.46(d, 1H,
3
m
m
H7, JHH = 16.0 Hz), 7.56(m, 10H, C6H5(DPPE)), 7.65(m, 6H,
d6): 2.58(m, 4H, ꢀCH2–), 2.90(s, 6H, –NCH3), 3.35(s, 6H, –NCH3),
C6H5(DPPE)), 7.99(d, 1H, H10
,
3JHH = 4.3 Hz), 8.08(m, 4H, C6H5,
4.32(s, 5H,
g
5-C5H5), 7.11(m, 1H, H10), 7.24(d, 1H, H7,
DPPE). 13C NMR (Acetone-d6): 27.58(–CH2–, DPPE), 80.33(g5
-
3
3JHH = 16.0 Hz), 7.31(d, 1H, H9, JHH = 3.4 Hz), 7.38(d, 1H, H4,
C5H5), 108.47(C2), 123.61(C6), 124.23(C7), 127.23(C9), 127.39(CN),
127.84(C4), 129.22(CH, DPPE), 130.10(C10), 131.52(CH, DPPE),
133.00(CH, DPPE), 136.64(Cq, DPPE), 139.25(C3), 147.68(C5),
148.33(C8), 150.08(C11). 31P NMR (Acetone-d6): ꢀ144.1(qt,
1JP,F = 710.7 Hz, PF6), 97.0(s, DPPE). Anal. Found: C, 54.74; H, 3.83;
N, 2.95%. Calc. for C42H35N2S2O2P3F6Fe: C, 54.44; H, 3.81; N, 3.02(%).
3JHH = 3.6 Hz), 7.47(d, 1H, H6, JHH = 16.0 Hz), 7.52(d, 1H, H11,
3
3JHH = 5.0 Hz) 7.93(br, 1H, H3). 13C NMR (Acetone-d6):
54.73(NCH3, TMEDA), 58.77(NCH3, TMEDA), 62.74(–CH2ꢀ, TME-
DA), 70.38(g
5-C5H5), 107.16(C2), 118.45(CN), 119.99(C7),
126.82(C6), 127.31(C4), 127.67(C11), 129.05(C10), 129.59(C9),
140.81(C8), 141.98(C3), 151.67(C5). 31P NMR (Acetone-d6):
ꢀ144.2(qt, JP,F = 711.2 Hz, PFꢀ). Anal. Found: C, 38.66; H, 4.14; N,
4.3.1.9. [Ru(
(5Ru). Dark-orange; recrystallized from CH2Cl2/(n-hexane); 50%
yield; IR (KBr, cmꢀ1): (PFꢀ6 ) 839; 1H NMR (Acetone-
(CN) 2189,
g
5-C5H5)(TMEDA)(NC(C4H2S)C(H)C(H)(C4H2S)NO2)][PF6]
1
6
6.01%. Calc. for C22H28N3S2PF6Ru ꢂ 0.6CH2Cl2: C, 39.02; H, 4.23; N,
6.04(%).
m
m
d6): 2.84(m, 4H, –CH2–), 2.90(s, 6H, -NCH3), 3.34(s, 6H, –NCH3),
3
4.3.1.5.
(3Ru). Yellow; recrystallized from CH2Cl2/(n-hexane); 70% yield;
IR (KBr, cmꢀ1): (PF6ꢀ) 840; 1H NMR (Acetone-d6):
(CN) 2214,
4.76(s, 5H,
[Ru(
g
5-C5H5)(PPh3)2(NC(C4H2S)C(H)C(H)(C4H3S))][PF6]
4.34(s, 5H,
g
5-C5H5), 7.40(d, 1H, H9, JHH = 4.3 Hz), 7.50(d, 1H, H6,
3
3JHH = 16.2 Hz), 7.53(d, 1H, H4, JHH = 4.0Hz), 7.64(d, 1H, H7,
3
m
m
3JHH = 16.0 Hz), 7.99(br, 1H, H3), 8.01(d, 1H, H10, JHH = 4.3 Hz).
g
5-C5H5), 7.11(m, 1H, H10), 7.20(d, 1H, H7,
13C NMR (Acetone-d6): 54.77(NCH3, TMEDA), 58.81(NCH3,
3JHH = 15.9 Hz), 7.24(m, 12H, C6H5(PPh3)), 7.31(d, 1H, H9,
3JHH = 3.7 Hz), 7.38(m, 14H, C6H5(PPh3)), 7.47(m, 7H, C6H5(PPh3)),
TMEDA), 62.77(–CH2–, TMEDA), 70.70(g
5-C5H5), 109.52(C2),
121.55(CN), 124.77(C6), 125.34(C7), 128.16(C9), 129.51(C4),
3
7.52(d, 1H, H3, JHH = 4.0 Hz), (H4, H6, H11 under the phosphines).
131.04(C10), 140.96(C3), 149.34(C5), 149.63(C8), 151.64(C11). 31P
1
13C NMR (Acetone-d6): 82.27(
g
5-C5H5), 105.35(C2), 119.80(C7),
NMR (Acetone-d6): ꢀ144.1(ht, JP,F = 711.0 Hz, PF6). Anal. Found:
126.18(CN), 127.07(C6), 127.21(C4), 127.85(C11), 129.08(C10),
129.42(CH, PPh3), 129.78(C9), 131.13(CH, PPh3), 134.26(CH, PPh3),
136.51(Cq, PPh3), 141.32(C3), 141.89(C8), 151.98(C5). 31P NMR
C, 40.24; H, 4.13; N, 8.25%. Calc. for C22H27N4S2O2PF6Ru ꢂ 0.3C6H14
:
C, 39.95; H, 4.40; N, 7.83(%).
1
(Acetone-d6): ꢀ144.1(ht, JP,F = 712.6 Hz, PF6), 41.4(s, PPh3). Anal.
4.3.1.10. [Ru(
(6Ru). Yellow; recrystallized from CH2Cl2/(n-hexane); 72% yield;
IR (KBr, cmꢀ1): (PF6ꢀ) 840; 1H NMR (Acetone-d6):
(CN) 2211,
4.77(s, 5H,
5-C5H5), 7.24(m, 12H, C6H5(PPh3)), 7.38(m,14H,
g
5-C5H5)(PPh3)2(NC(C4H2S)C(H)C(H)(C4H2S)NO2)][PF6]
Found: C, 58.98; H, 4.37; N, 1.26%. Calc. for C52H42NS2P3F6Ru: C,
59.31; H, 4.02; N, 1.33(%).
m
m
g
4.3.1.6.
(4Ru). Yellow; recrystallized from CH2Cl2/(n-hexane); 77% yield;
IR (KBr, cmꢀ1): (CN) 2214, mas(OSO, CF3SOꢀ3 ) 1243; 1H NMR (Ace-
tone-d6): 2.69(m, 2H, –CH2–), 2.80(m, 2H, –CH2–), 5.03(s, 5H, g5
[Ru(
g
5-C5H5)(DPPE)(NC(C4H2S)C(H)C(H)(C4H2S)NO2)][PF6]
C6H5(PPh3)), 7.47(m, 6H, C6H5(PPh3)), 7.58(d, 2H, H9 + H3,
J = 4.0 Hz), 7.60(d, 1H, H7, J = 16.1 Hz), 8.00(d, 1H, H10, J = 4.0 Hz),
m
(H4, H6 under the phosphines). 13C NMR (Acetone-d6): 84.49(g5
-
-
C5H5), 108.05(C2), 124.22(C6), 124.28(C7), 125.01(CN), 127.42(C9),
128.34(C4), 128.54(CH, PPh3), 130.13(C10), 130.25(CH, PPh3),
133.36(CH, PPh3), 135.54(Cq, DPPE), 140.45(C3), 148.28(C5),
149.15(C8), 150.25(C11). 31P NMR (Acetone-d6): ꢀ144.0(m, PFꢀ6 ),
41.4(s, PPh3). Anal. Found: C, 55.36; H, 3.95; N, 2.51%. Calc. for
C52H41N2S2O2P3F6Ru ꢂ 0.5CH2Cl2: C, 55.29; H, 3.71; N, 2.46(%).
3
3
C5H5), 6.82(d, 1H, H3, JHH = 4.0 Hz), 7.24(d, 1H, H4, JHH = 4.0 Hz),
7.32(d, 1H, H6, JHH = 16.0 Hz), 7.36(d, 1H, H9, JHH = 4.4Hz),
7.48(d, 1H, H7, JHH = 16.0 Hz), 7.52(m, 10H, C6H5(DPPE)), 7.63(m,
3
3
3
3
6H, C6H5(DPPE)), 7.99(d, 1H, H10, JHH = 4.3 Hz), 8.01(m, 4H,
C6H5(DPPE)). 13C NMR (Acetone-d6): 27.64(ꢀCH2–, DPPE),
82.69(g
5-C5H5), 107.70(C2), 120.68(CN), 123.91(C6), 124.15(C7),
127.32(C9), 127.85(C4), 128.98(CH, DPPE), 130.40(C10), 131.07(CH,
DPPE), 133.30(CH, DPPE), 137.33(Cq, DPPE), 139.68(C3),
148.24(C5), 148.59(C8), 148.76(C11). 31P NMR (Acetone-d6):
79.0(s, DPPE). Anal. Found: C, 51.71; H, 3.75; N, 2.96%. Calc. for
C42H35N2S2O2P3F6Ru: C, 51.11; H, 3.63; N, 2.88(%).
4.4. Electrochemical studies
The electrochemical experiments were performed on an EG&G
Princeton Applied Research Model 273A potentiostat/galvanostat
and monitored with a personal computer loaded with Electro-

444
M.H. Garcia et al. / Journal of Organometallic Chemistry 694 (2009) 433–445
chemistry PowerSuite v2.51 software from Princeton Applied Re-
search. Cyclic voltammograms were obtained in 0.1 M solutions
of [NBu4][PF6] in dried CH2Cl2 or CH3CN, at a three-electrode con-
figuration cell, with a platinum-disk working electrode (1.0 mm
diameter) probed by a Luggin capillary connected to a silver-wire
pseudo-reference electrode; a Pt wire auxiliary electrode was em-
ployed. The electrochemical experiments were performed under a
N2 atmosphere at room temperature. The redox potentials of the
complexes were measured at the presence of ferrocene, as the
internal standard, and the redox potential values were normally
quoted relative to the SCE by using the ferrocenium/ferrocene re-
dox couple (Ep/2 = 0.46 or 0.40 V versus SCE for CH2Cl2 or CH3CN,
respectively) [41].
Appendix A. Supplementary material
CCDC 694644–694646 contain the supplementary crystallo-
graphic data for compounds 10Ru, 40Ru and 1Fe. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplemen-
tary data associated with this article can be found, in the online
version, at doi:10.1016/j.jorganchem.2008.11.019.
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