Ligand bridged heterodinuclear transition metal complexes - Syntheses, structures and electrochemical investigations

Article abstract of DOI:10.1002/zaac.200500229

The syntheses of the homo- and hererobimetallic compounds [L _n¹M(η⁵-C₅H₄)CMe ₂(η⁵-C₉H₆)²ML _n] (2a-5d), [(C₉H₇)CMe₂(η ⁵-C₅H₄)Fe(η⁵-C₅H ₄)CMe₂(η⁵-C₉H₆) ²ML_n] (6a-c), and [(η⁵-C₅H ₄)CMe₂(η⁵-C₉H₆) ²ML_n]₂Fe (7a-b) are reported with ¹ML_n = Rh(cod) 2, Ir(cod) 3, Mn(CO)₃ 4 and FeCp 5, ²ML_n = Rh(cod) a, Ir(cod) b, Mn(CO)₃ c and FeCp d, respectively. Crystal structures of 3a, 3b and 5c are described showing two different ligand conformations in form of two rotamers. The energetic difference between these both rotamers is insignificant small in the gas phase according to DFT calculations. The rotation barrier for the species has been determined to 23 kJ/mol. According to the absence of intermolecular interactions in the solid state, the preference for one of the conformers is deduced from packing effects. All complexes are investigated by cyclic voltammetry. The shift of the redox potentials with respect to the mononuclear reference systems is a suitable tool to determine intermetallic electronic interaction. For some compounds, the normal behaviour with an increasing separation of the redox potentials is observed. A second group of complexes shows the opposite behaviour with a decreasing in the potential differences. A mechanism of intramolecular catalytic oxidation is supposed for that species.

Full text of DOI:10.1002/zaac.200500229

Articles
DOI: 10.1002/zaac.200500229
Ligand Bridged Heterodinuclear Transition Metal Complexes ؊ Syntheses,
Structures and Electrochemical Investigations
Petra Escarpa Gaede* and Christoph van Wüllen
Berlin, Technische Universität, Institut für Chemie
Received May 5th, 2005.
Dedicated to Professor Jörn Müller on the Occasion of his 70th Birthday
Abstract. The syntheses of the homo- and hererobimetallic com-
All complexes are investigated by cyclic voltammetry. The shift of
the redox potentials with respect to the mononuclear reference
systems is a suitable tool to determine intermetallic electronic inter-
action. For some compounds, the normal behaviour with an in-
creasing separation of the redox potentials is observed. A second
group of complexes shows the opposite behaviour with a decreasing
in the potential differences. A mechanism of intramolecular cataly-
tic oxidation is supposed for that species.
pounds
[Ln1M(η5-C5H4)CMe2(η5-C9H6)2MLn]
(2a-5d),
[(C9H7)CMe2(η5-C5H4)Fe(η5-C5H4)CMe2(η5-C9H6)2MLn] (6a-c),
and [(η5-C5H4)CMe2(η5-C9H6)2MLn]2Fe (7a-b) are reported with
1MLn ϭ Rh(cod) 2, Ir(cod) 3, Mn(CO)3 4 and FeCp 5, 2MLn
ϭ
Rh(cod) a, Ir(cod) b, Mn(CO)3 c and FeCp d, respectively. Crystal
structures of 3a, 3b and 5c are described showing two different
ligand conformations in form of two rotamers. The energetic diffe-
rence between these both rotamers is insignificant small in the gas
phase according to DFT calculations. The rotation barrier for the
species has been determined to 23 kJ/mol. According to the ab-
sence of intermolecular interactions in the solid state, the prefe-
rence for one of the conformers is deduced from packing effects.
Keywords: Organometallic compunds; Heterobimetallic com-
pounds; Metal-metal interactions; Cyclic voltammetry, Conforma-
tion analysis
Introduction
Bimetallic complexes have found much interest in the last
decade. Cooperative effects involving two metal centers kept
in close proximity by a bridging ligand have led to unpre-
cedented reactivity in stoichiometric or catalytic reactions
[1]. Extensive work has been concentrated on Cp systems
linked by methylene or dimethylsilylene units [2] because
the strong metal-Cp bond prevents the dissociation into two
mononuclear metal complex fragments during the reaction
[3]. Furthermore, various metal atoms in different oxidation
states can be bounded to such ligands. This has led to a
number of binuclear complexes of type A (see fig. 1), which
can be further classified as homo- or heterobimetallic spe-
cies. While the synthesis of homonuclear compounds pre-
sents no particular difficulty for this ligand system, its sym-
metrical structure makes the selective preparation of bime-
tallic complexes problematic. The reason is that the depro-
tonation/metallation reaction used to introduce a metal
Figure 1
complex fragment proceeds at all Cp rings with almost the
same rate, independent of whether the other Cp ring in the
same ligand has already been metallated. Therefore the re-
action with only one equivalent of reagent ends up usually
with a mixture of the mono- and the homobinuclear pro-
ducts.
To overcome this problem, an unsymmetric ligand has
been introduced and bimetallic complexes of type B have
been obtained [4]. Our work follows a different route by
replacing one of the Cp rings with an indenyl system [5],
which leads to complexes of type C. This adds an interest-
ing aspect to the reactivity of these compounds in catalytic
reactions due to the well known “indenyl” effect which
stands for the easy change from η5 to η3 hapticity [6]. The
acidity of both ring systems in the ligand precursor 1 is so
* Dr. P. Escarpa Gaede
Technische Universität Berlin
Institut für Chemie, Sekr. C2
Straße des 17. Juni 135
D-10623 Berlin (Germany)
Fax: 49 30 3142 1106; Tel: 49 30 3142 3740
E-mail: Escarpa@chem.tu-berlin.de
Supporting information for this article is available on the
WWW under http://www.wiley-vch.de/home/zaac or from the
author.
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P. Escarpa Gaede, C. van Wüllen
Scheme 2 Syntheses of the complexes 6a-c and 7a-c.
corresponding to complexes with coupled ligands like
[Mn(CO)3(η5-C5H4)CMe2(C9H6)(C9H6)CMe2(C5H5)]
or
[Mn(CO)3(η5-C5H4)CMe2(C9H6)(C5H4)CMe2(C9H7)] and
[Mn(CO)3(η5-C5H4)CMe2(C9H6)(C9H6)CMe2(η5-
Scheme 1 Stepwise synthesis to obtain the heterobimetallic com-
plexes 2a to 5d with numbering scheme for the NMR data.
C5H4)Mn(CO)3], respectively. The coupling of olefin li-
gands in this kind of metathesis reaction is typical for
manganese described in the literature [10]. The separation
of this mixture by column chromatography was only
partly successful.
different that the deprotonation is exclusively found at the
Cp ring and heterobimetallic compounds can be obtained
in a stepwise synthesis shown in scheme 1.
We have recently reported the synthesis of the ferrocene
derivative 6, which can be obtained form monolithiated 1
and FeCl2 [11]. Further deprotonation and metallation
steps at the indenyl rings lead to the heterobimetallic species
6a and 7a with one or two additional rhodium cyclo-
octadiene (cod) fragments coordinated to the indenyl parts
of the ligands [11]. Due to the equivalence of both indenyl
substitutions at the ferrocene derivative 6, we found the bi-
nuclear and the trinuclear species 6a and 7a in the product
mixture including some starting material, when 6 reacted
with only one equivalent of base and metal reagent. The
compounds were separated by column chromatography. We
extended this synthesis to introduce the metal moieties
Ir(cod) and Mn(CO)3 instead of the Rh(cod) fragments and
synthesized the complexes 6b, 6c, 7b and 7c, respectively
(see scheme 2). Again, compound 7c could not be isolated
with satisfying purity because of side products formed in
the reaction of a dilithio salt and [Mn(CO)5Br], as dis-
cussed above.
Results and Discussion
The length of the linker between the two five membered
rings controls the strength of the steric and electronic inter-
action in these bimetallic complexes. A short bridging
group keeps both metal complex fragments in close proxi-
mity, which should enhance intermetallic interaction. For
this reason we choose the dimethylcarbon group as the
linker between the two five membered rings to synthesize
and investigate complexes of type C. This ligand system had
been introduced to the syntheses of mono- [7], homobi-
metallic [8] and of some heterobimetallic complexes [9]. We
have expanded the group of heterobimetallic compounds
with this ligand by synthesizing the complexes
[(1MLn)(C5H4)CMe2(C9H6)(2MLn)] (2a-5d) with combi-
nations of the metal complex fragments 1MLn, 2MLn
ϭ
Rh(cod)1), Ir(cod), Mn(CO)3 and FeCp according to
scheme 1. In all cases, the reaction proceeds with high selec-
tivity and the products were obtained in good yields. Only
for the synthesis of [Mn(CO)3(C5H4)CMe2(C9H6)Mn(CO)3]
(4c) from the dilithio salt and two equivalents of
[Mn(CO)5Br], fore side products were detected by MS.
These compounds were identified as [Mn2(CO)10], the
mononuclear species [Mn(CO)3(C5H4)CMe2(C9H7)] (4) and
two species giving molecular ions at m/z ϭ 580 and 718,
All synthesized compounds were characterized by MS,
1H- and 13C-NMR spectroscopy (see experimental section,
the numbering of the atoms corresponds to that in figure 1).
Crystallographic studies
Single crystals of the complexes 3a, 3b and 5c were obtained
by slow evaporation from an diethyl ether solution at 4 °C.
Figure 2 shows the molecular structures of these three com-
pounds, Table 1 gives the crystallographic data. Selected
bond distances and interplanar angles are listed in Table 2
and 3, respectively.
1) cod ϭ cyclooctadiene (C8H12)
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Ligand Bridged Heterodinuclear Transition Metal Complexes
1
5
5
˚
Table 1 Crystallographic data
Table 2 Selected bond lengths / A in [ MLn(η -C5H4)CMe2(η -
C9H6)2MLn].
5c
3a
3b
3b
3a
5c
Crystal parameters
Chem. formula
Fw /g molϪ1
C25H21FeMnO3
480.21
C33H40RhIr
731.76
C33H40Ir2
821.05
M(1)-C(11)
M(1)-C(12)
M(1)-C(13)
M(1)-C(14)
M(1)-C(15)
M(1)-C(Cp)
M(1)-C(Ln)
M(2)-C(7)
M(2)-C(8)
M(2)-C(9)
M(2)-C(6)
M(2)-C(1)
M(2)-C(Ln)
C(CO)-O(CO)
C(1)-C(2)
C(1)-C(6)
C(1)-C(9)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(6)-C(7)
2.298(4)
2.198(5)
2.223(5)
2.247(5)
2.267(5)
2.246(5)
2.109(5)
2.207(5)
2.252(5)
2.263(4)
2.344(4)
2.374(4)
2.142(5)
2.31(1)
2.19(1)
2.23(1)
2.241(13)
2.28(1)
2.252(13)
2.11(1)
2.228(9)
2.234(9)
2.260(9)
2.348(9)
2.351(8)
2.14(1)
2.052(3)
2.044(3)
2.031(4)
2.032(4)
2.040(3)
2.040(4)
2.039(4)
2.132(4)
2.142(3)
2.165(3)
2.190(3)
2.209(3)
1.794(4)
1.147(4)
1.427(5)
1.435(5)
1.459(5)
1.364(6)
1.417(8)
1.349(7)
1.427(5)
1.431(6)
1.416(5)
1.426(5)
1.533(5)
1.528(5)
1.538(5)
1.521(4)
1.426(5)
1.431(5)
1.423(5)
1.400(6)
1.430(5)
Crystal system
Space group
monoclinic
C2/c (No. 15)
18.4858(3)
7.36210(10)
30.8651(4)
90
92.1830(10)
90
4197.52(10)
8
triclinic
triclinic
¯
¯
P 1 (No. 2)
P 1 (No. 2)
˚
a /A
7.09700(10)
13.13110(10)
14.4778(2)
89.8590(10)
82.5020(10)
84.0630(10)
1330.41(3)
2
7.09700(10)
13.13110(10)
14.4778(2)
89.8590(10)
82.5020(10)
84.0630(10)
1330.41(3)
2
˚
a)
b)
b /A
˚
c /A
α /°
β /°
γ /°
3
˚
Volume /A
Z
D (calc.) /g cmϪ3
F(000)
1.520
1968
1.317
1.827
720
5.637
2.050
784
10.013
b)
a)
µ (Mo Kα) /mmϪ1
Data collection
2θ range
1.405(7)
1.434(6)
1.456(6)
1.381(8)
1.42(1)
1.428(13)
1.422(13)
1.459(13)
1.393(18)
1.37(2)
4.48Ϫ50.0
Ϫ21 Յ h Յ 19,
Ϫ8 Յ k Յ 8,
Ϫ36 Յ l Յ 31
12477
3675
0.0584
3.12Ϫ55.0
Ϫ9 Յ h Յ 5,
Ϫ17 Յ k Յ 17,
Ϫ18 Յ l Յ 17
10243
6063
0.0334
2.84Ϫ50.0
Ϫ8 Յ h Յ 8,
Ϫ15 Յ k Յ 15,
Ϫ17 Յ l Յ 13
8303
4633
0.0466
Index range
(h, k, l)
1.34(1)
1.36(2)
Data
Indpt. obs. rflns.
R(int)
1.426(8)
1.432(8)
1.409(7)
1.419(6)
1.548(6)
1.542(8)
1.517(7)
1.539(6)
1.402(8)
1.417(8)
1.436(9)
1.37(1)
1.401(16)
1.422(15)
1.410(15)
1.421(13)
1.553(14)
1.513(15)
1.507(14)
1.517(13)
1.464(15)
1.417(16)
1.44(2)
C(7)-C(8)
C(8)-C(9)
Indpt. rflns.
Parameters
Refinement
3675
271
6063
319
4633
318
C(9)-C(10)
C(10)-C(16)
C(10)-C(17)
C(10)-C(11)
C(11)-C(12)
C(11)-C(15)
C(12)-C(13)
C(13)-C(14)
C(14)-C(15)
Ϫ3
˚
∆(ρ) /e·A
0.257 / Ϫ0.614
0.792039
0.457381
1.961 / Ϫ1.138
0.297834
0.136212
1.556 / Ϫ2.801
0.564153
0.241083
Tmax
Tmin
GOF
.
.
1.096
1.013
0.989
a)
R
[%]
4.57 (5.97)b)
9.99 (10.59)b)
3.18 (4.03)b)
7.62 (8.05)b)
4.14 (5.65)b)
9.76 (10.41)b)
wR2 a)[%]
1.39(2)
1.416(16)
1.414(8)
a) RϭΣʈFoΗ-ΗFcʈ / ΣΗFoΗ, wR2ϭ[Σ[w(Fo2ϪFc2)2] / Σ[w(Fo2)]]1/2, [Fo>4σ(Fo)],
b) based on all data.
a) average value, b) average value Ln stands forthe coligand cod or CO.
Crystallographic data for the structures have been deposited with the
Cambridge Crystallographic Data Centre, CCDC231311Ϫ231313.
Copies of the data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(Fax: int. codeϩ(1223)336-033; e-mail for inquiry: fileserv@ccdc.ca-
m.ac.uk).
ligand, the distance between the metal atom and the quar-
terial carbon atom C9 is always longer than the correspond-
ing bond lengths to C7 or C8. Comparing the three struc-
tures, the main difference is found in the conformation of
the bridging ligand. The dihedral angle ϕ (C11-C10-C9-C1)
is the characteristic parameter for the orientation of both
coordination planes in these molecules, and detected as
Due to the small difference in the atom radius between
rhodium and iridium, the structures of the molecules 3a
and 3b are isostructural and isotypic, which means even the
cell dimensions are identical in all three structures. The metal
atoms are η5-coordinated to the five membered ring in the
Cp or in the indenyl part of the bridging ligand. The tend-
ency to a η3 displacement of the metal atom at the indenyl
system is reflected in the difference of bond distances to C1
and C6 in relation to C7, C8 and C9. This elongation of
the metal carbon bond lengths is obtained2) to 5.2, 5.3 and
2.4 % for 3a, 3b and 5c, respectively. The hinge angle given
by the plane angle of the allyl system (C7, C8 and C9) to
the ene-system (C7, C6, C1 and C9) is a further marker for
this displacement. The largest angle is found for complex
3a (7.8°) followed by 5.6° for 3b and only 3.6° for 5c. Most
likely because of some steric interaction of the metal com-
plex fragment with the two methyl groups of the bridging
Table 3 Interplanar angle / ° and distance of the metal atom to the
plane in [1MLn(η5-C5H4)CMe2(η5-C9H6)2MLn].
3b
3a
5c
Є Pl 1ϪPl 2
Є Pl 3ϪPl 4
Є Pl 1ϪPl 5
Є Pl 2ϪPl 6
Pl 1 Ϫ M(1)
Pl 2 Ϫ M(2)
89.1 (0.4)
5.6 (1.3)
5.1 (0.4)
2.6 (0.7)
1.896(5)
1.931(3)
89.8 (0.2)
7.8 (0.6)
4.8 (0.2)
3.8 (0.4)
1.899(2)
1.932(2)
76.7 (0.1)
3.6 (0.5)
3.1 (0.3)
1.642(1)
1.792(1)
Pl 5 Ϫ M(1)
Pl 6 Ϫ M(2)
1.453(5)
1.460(4)
1.449(2)
1.467(2)
1.649(2)
Pl 1: [C11ϪC15]
Pl 2: [C1ϪC9]
Pl 3: [C7ϪC9]
Pl 4: [C1;C6;C7;C9]
Pl 5: [1Ln]
C18;C19;C22;C23 C18;C19;C22;C23 C18 Ϫ C22
C26;C27;C30;C31 C26;C27;C30;C31
2) calculated from the quotient of the middle bond lengths:
Pl 6: [2Ln]
1
1 Ϫ[1/2(M-C1 ϩ M-C6) / /3(M-C7 ϩ M-C8 ϩ M-C9)]
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P. Escarpa Gaede, C. van Wüllen
Figure 2 Molecular structure of 3a, 3b and 5c.
75.7°, 75.2° and 177.9° for 3a, 3b and 5c, respectively. In
other known structures with the same bridging ligand di-
hedral angles of 177.3° (5a) [11], 172.9° [(η5-
C5H4)CMe2(η5-C9H6)Rh2(C2H4)4] and 75.9° (3a) [7a] are
found. The rotation around the C9-C10 bond thus gives rise
to two rotamers which can be classified as anti (ϕ ഠ 180°)
or gauche (ϕ ഠ 75°). It is not obvious why different com-
pounds have solid state structures which belong to different
rotamer classes. It would be interesting to know whether
this is mainly a crystal packing effect or whether the pro-
pensity for different rotamers is already developed for iso-
lated (i.e. gas phase) molecules.
of the two metal complex fragments. The conformations
found in the molecular structures conforms to the resulted
structures at the minima 1 and 2. The absolute rotation bar-
rier is 23 kJ/mol calculatedly, but there are two other max-
ims of a little bit lower energy barrier. Over all, the curves
are very similar to that of butane, only the energy barriers
are a little bit higher as for the alkane. The hump at 280°
is caused by steric interaction of the indenyl metal complex
fragment with the Cp ring, because it locates over the five
membered ring at this torsion angle.
According to the result, there is no energetic difference
between both conformations 1 and 2 in the gas phase. On
the other hand, no intramolecular interactions can be found
in the solid state. We presume the preference for the chosen
conformation in the crystal structure of each compound is
only controlled by molecular packing in the crystal. From
the energetic height of the rotations barrier we can conclude
that the complexes are very flexible and that the metal me-
tal distance can be modified easily in solution. That is im-
portant, if both metals act in concert with a substrate coor-
dinated to both metals.
Theoretical calculations
We applied quantum chemical density functional calcu-
lations to compute the energy profile associated with a ro-
tation around C9-C10. We chose the two rhodium com-
pounds 2a and 5a as representatives for the gauche and the
anti class, respectively. First a geometry optimization was
performed, starting from the coordinates found in the crys-
tal. This step essentially moves the hydrogen atoms to their
correct positions. Starting from this geometry, the torsion
angle ϕ(C1-C9-C10-C11) was fixed in steps of 10°, relaxing
all other internal coordinates to their optimal values. Figure
2 shows the resulting energy profiles for the two com-
pounds.
There are only small differences between the two curves
which are mostly caused by variable conformations in the
cyclooctadiene rings than by intramolecular interactions
between the two molecule parts. Within a tolerance of 1 kJ/
mol, two minima are found with the same energy at 60 Ϫ
70° (conformation 1 ϭ gauche) and 170 Ϫ 180° (confor-
mation 2 ϭ anti). The third minimum at 320° shows a
higher energy level, the difference is marked by 4 kJ/mol.
This must be attributed to the second gauche conformation
Electrochemical messurements
The electronic interaction between two metal atoms in a
ligand bridged complex can be measured by cyclic voltam-
metry (CV). This has been achieved for symmetric com-
pounds in the literature, mostly for bisferrocenyl species
[12]. In such a CV, two signals are shown, each indicating
a single electron transfer. The potential difference between
these two one-electron-steps corresponds to the strength of
the intermetallic interaction. Depending on the bridging
atoms between the two ferrocenyl moieties, ∆E values were
reported up to 800 mV for a totally delocalisation of the
positive charge in the mixed valence complex. Robin and
Day [13] introduced a classification into three groups of
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Ligand Bridged Heterodinuclear Transition Metal Complexes
Figure 3 Energy of the complexes 2a (full line) and 5a (dotted line) correlated to the torsion angle ϕ C1-C9-C10-C11.
compounds: class I shows none or only weak interaction of
the metal centers corresponding to ∆E values of 0 Ϫ
200 mV, class III species are characterized by a strong π-
delocalisation in the bridging ligand with ∆E values larger
than 500 mV. Complexes showing values between these ex-
tremes possess only partial delocalisation of the unpaired
electron over the two metal moieties. The potential differ-
ence also weakly depends on the solvent, the supporting
electrolyte [14] and the nature of the metals themself, if the
iron atoms were substituted, for instance, by nickel or co-
balt atoms. For a C1 bridging moiety as in the compounds
discussed in this paper, ∆E values between 100 and 150 mV
are expected [12].
In contrast to the symmetric complexes described in the
literature, the homobimetallic species 2a, 3b, 4c and 5d
show two steps in the CV even in the absence of any elec-
tronic interaction due to the unsymmetric structure of the
complexes and the electronic dissimilarity of the Cp and the
indenyl system. Therefore, we can not merely look at the ∆E
value in the bimetallic complexes, but compare the potential
values obtained from the bimetallic compound with those
of the corresponding mononuclear Cp or indenyl species,
respectively (Table 4, all values were referred against ferro-
cene as external standard). This gives us a potential shift
∆E(M) for each metal complex fragment in the bimetallic
compound. The difference between these two ∆E(M) values
is comparable to the original ∆E in symmetric complexes.
This can be illustrated in Figure 4 on the example of com-
pound 5d, where its CV is shown beside those obtained
from ferrocene and [(Ind)FeCp] (Ind ϭ Indenyl, C9H7). The
first oxidation wave of 5d at Ϫ140 mV can be attributed to
the iron center within the indenyl part, the second at
125 mV to that on the Cp part of the linked ligand. The
two redox waves are thus separated by 265 mV. Compared
to the mononuclear reference compounds [(Ind)FeCp] and
ferrocene, the first oxidation is shifted towards lower poten-
tial by 65 mV, while the second is shifted by 70 mV to
higher potential. This totally gives a separation shift of
135 mV for the bimetallic iron species, which is in good
agreement with the expected value of 100 Ϫ 150 mV. Simi-
lar results were obtained looking at the half potentials E1/2
.
The reversibility of the two redox steps in 5d is compar-
able with that in ferrocene indicated by slightly larger po-
tential differences ∆ER between the corresponding oxidative
and reductive current maxima. This fact is very useful in
the case when the iron oxidation is superposed by the
irreversible oxidation of another metal complex fragment.
In this case the reductive peak can be used to calculate
E
1/2 for the iron moiety under the assumption that the ∆ER
values are comparable. Generally we have observed even in
water based systems relatively high ∆ER values compared
to the theoretical value of 58 mV. This is deduced from the
missing compensation of faraday current with the Metrohm
potentiostat that has been used.
The potentials of the mononuclear complexes 2 to 6 are
listed in table 4. The unsubstituted Cp or indenyl species
are used as references for the shift determination ∆E(M) in
the bimetallic compounds 2a to 7b, which are given together
with their measured oxidation potentials in table 5. The val-
ues in this table refer to the E1/2 for the iron containing
moieties, and to Emax for the irreversible oxidations of all
other metal complex fragments. The values ∆Enet in the last
Table 4 E1/2 and potential at the current maxim measured with
50 mV/s.
complex
E1/2 / mV
Emax / mV
CpRh(cod)
(Ind)Rh(cod)
2
75
120
60
CpIr(cod)
(Ind)Ir(cod)
3
CpMn(CO)3
(Ind)Mn(CO)3
4
Cp2Fe
(Ind)FeCp
5
180
190
180
865
780
925
55
0
Ϫ130
Ϫ15
Ϫ75
55
6
Ϫ10
55
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545

P. Escarpa Gaede, C. van Wüllen
Figure 4 CV of 5d (full line), ferrocene (broken line) and (Ind)FeCp
(dotted line) in CH2Cl2 at 100 mV/s.
Figure 5 CV of 6b (full line), 6 (dotted line) and (Ind)Ir(cod)
(broken line) in CH2Cl2 at 100 mV/s.
column is calculated as the differences of both ∆E(M) val-
ues, where ∆Enet ϭ ∆E(2M) Ϫ ∆E(1M), if the metal atom
1M is oxidized at lower potential as 2M, or ∆Enet ϭ ∆E(1M)
Ϫ ∆E(2M) in the opposite case. ∆Enet represents the total
drifts of both redox steps; a positive value is attributed to
an increasing separation of both redox waves as expected,
while a negative difference indicates a decreasing separ-
ation.
A group of complexes shows the expected value around
130 mV for ∆Enet, but much higher values were observed
for species 4a and 6c. A second group of compounds, es-
pecially those with an iridium fragment, shows significantly
smaller differences around 65 to 85 mV. This can be attri-
buted to the metal influence known from the literature by
various peak separations ∆E for different bismetallocenes
with the same bridging ligand [15].
For some complexes, a negative ∆Enet was obtained,
which means that the separation of the peaks decreases.
Thereby both peaks must not necessarily move towards
each other. Some compounds show shifts to lower potential
for both redox steps but while the second shift is much
larger than the first one, which also results in a negative
∆Enet. Figure 5 demonstrates this phenomenon for 6b. Both
metal atoms in 6b were oxidized at a lower potential as
the corresponding mononuclear species. The shift to lower
potential for the iridium centered oxidation is 50 mV higher
than for the iron atom. This unusual behaviour was found
for a number of complexes mainly when a ferrocenyl and a
rhodium or iridium fragment are involved. For interpre-
tation, we suggest a mechanism with an intramolecular
catalytic oxidation step (scheme 3). After the first oxidation
the positive charge is transferred to the second metal atom.
This occurs at a lower potential level than normally re-
quired to oxidize the second metal atom. The first metal
atom is oxidized again as soon as the second metal atom
transferred the electron to it. This phenomenon of catalytic
oxidation is well known for bimolecular systems [16] but is
to our knowledge unprecedented for intramolecular pro-
cesses.
We point out that intramolecular charge transfer has
been well established in the literature [17]. For example
T.J.J. Müller explained the irreversibility of the chromium
oxidation in linked ferrocenyl phenyl tricarbonyl chromium
complexes [Fc-X-(C6H5)Cr(CO)3] in contrast to the rever-
sible oxidation in [(C6H6)Cr(CO)3] by such intramolecular
positive charge transfer from the iron to the chromium
atom [17e]. The other example has been given by Ceccon et
al. with a ferrocenyl indenyl rhodium dicarbonyl complex
[18]. These two examples show that a ferrocenium cation
can interact with a neutral metal complex fragment, if both
are relatively close to each other. The tendency to transfer
one electron to the ferrocenium part in the molecule is very
strong, if electron rich metal complex fragments with rho-
Table 5 Redox potential for compounds 2a to 7b and their poten-
tial shift compared to their correspondent Cp or indenyl complex
with a scan rate of 50 mV/s.
E(1M)
E(2M)
∆E(1M)
∆E(2M)
∆Enet
a)
2a
2b
2c
2d
3a
3b
3c
3d
4a
4b
4d
5a
5b
5c
5d
6a
6b
6c
7a
7b
110
45
45
115
165
875
Ϫ175
30
ϳ220
925
Ϫ220
30
245
Ϫ140
105
155
885
Ϫ200
85
105
1045
45
ϩ35
Ϫ30
Ϫ30
ϩ85
ϩ35
Ϫ55
ϩ65
Ϫ25
ϩ95
ϩ5
ϩ130
ϩ40
Ϫ20
Ϫ40
ϩ60
Ϫ10
Ϫ35
ϩ10
Ϫ10
Ϫ140
Ϫ10
Ϫ25
ϩ95
Ϫ45
Ϫ90
ϩ30
ϩ145
Ϫ90
Ϫ90
ϩ55
Ϫ10
Ϫ15
Ϫ35
ϩ105
Ϫ70
Ϫ35
Ϫ85
ϩ265
Ϫ75
Ϫ85
Ϫ45
a)
ϩ5
a)
b)
b)
ϩ125
ϩ130
ϩ125
160
215
ϳ125
245
155
960
ϳ870
995
40
Ϫ20
Ϫ40
60
ϳ-10
Ϫ35
10
a)
ϩ85
ϩ80
ϩ65
a)
b)
b)
ϩ185
b)
Ϫ50
b)
ϩ140
a)
Ϫ55
Ϫ15
a)
a)
b)
ϩ145
ϩ130
Ϫ25
Ϫ50
ϩ255
a)
a)
a)
a)
ϳ5
ϳ-140
Ϫ65
ϩ55
a)
105
a) ∆E(2M) Ϫ ∆E(1M)
b) ∆E(1M) Ϫ ∆E(2M)
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Ligand Bridged Heterodinuclear Transition Metal Complexes
Figure 7 left: first circle in the CV of 4d in CH2Cl2 at different scan
rates. right: CV of 4d with different scan ranges at 200 mV/s.
Figure 6 first (left) and second (right) cycle in the CV of 5c in
CH2Cl2 at different scan rates.
without reaching the value where the manganese becomes
oxidized, reversibility sustained even after ten cycles. There-
fore, a second chemical reaction forming the compound
dium or iridium are involved, which have similar redox po-
tentials as ferrocene. We could not observe such effects for
the coordination isomers, where the metal complex frag-
ments are exchanged at the two ligand parts and the iron is
bound to the indenyl ring.
2؉
5c2 must be induced from the manganese center then the
iron moiety of the molecule is involved. This transformation
is slow compared to the first reaction, which makes the
manganese oxidation characteristically irreversible and does
not involve the ferrocenyl part of the molecule. Further-
more, a new product wave for oxidation at 0.50 V occurs in
the second cycle together with a small corresponding ca-
thodic step at the back sweep. Such a product wave is not
observed from any other manganese compounds. The inten-
sity of this signal does not change with the scan rate as
usual. In relation to the other signals, this peak increases
with slower scan rates. We suppose that this redox signal
belongs to the product compound 5c2؉/5c22؉, which is
formed by the slow second chemical reaction as we have
Beside this investigations to the intermetallic interactions
in the bimetallic compounds some other interesting aspects
have been observed in the cyclic voltammetry of compound
5c, if the first and second cycle were compared with each
other (figure 6). The redox signal of the ferrocene part of
the molecule is clearly shown at ca. Ϫ0.04 V. In contrast,
the irreversible oxidation of the Mn(CO)3 moiety at 0.90 V
2؉
forming the species 5c1 by an electron transfer followed
by a chemical reaction (EC mechanism) is indicated only
by a shoulder in the CV. In the first cycle the oxidation of
iron appeared to be reversible (Fig. 6, left panel). However,
in a second run, the wave for the iron reduction decreases
comparing to the corresponding oxidative wave, which indi-
cates reduced reversibility. This loss of reversibility increases
with slower scan rates. If the potential is only run to 0.6 V
2؉
discussed above. 5c2 is an unstable species and precipi-
tates on the surface of the electrode preventing any further
redox process on the coated surface. For this reason, we
can’t prove whether the second chemical reaction starts
2ϩ
؉
from the bicationic species 5c1 or the monocationic 5c1
or even from both. A similar behavior is found for the re-
lated compound 6c.
Looking at the CV of the coordination isomer 4d of com-
pound 5c, where the metal complex fragments are ex-
changed between the Cp and indenyl part of the ligand (fig-
ure 7), the intensity of the iron reduction peak in the first
circle already decreases with the scan rate. This must be
interpreted as a increasing reaction rate in the second
chemical step. This interpretation is furthermore supported
by the absence of the new oxidation wave at around 0.5 V
in the second cycle. Only the small hump at the back sweep
of the first cycle indicates the appearance of the analogue
intermediate 4d22؉, which has also a shorter life time as its
isomer 5c22؉. The change in reversibility of the iron oxi-
dation is also demonstrated in dependence of the reversal
potential in that figure 7.
In analogy to the mechanism discussed by Ceccon et al.
[18] for the mentioned similar compound 2-ferrocenyl-inde-
nyl-rhodiumdicarbonyle we propose the reaction scheme
shown in scheme 4. This phenomenon is restricted to mixed
iron manganese compounds and no such observations can
be done for the other Mn(CO)3 complexes 2c, 3c, 4a and 4b.
Scheme 3 mechanism of the catalytical intramolecular oxidation.
Z. Anorg. Allg. Chem. 2006, 541Ϫ552
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547

P. Escarpa Gaede, C. van Wüllen
recorded with the Bruker ARX 200 spectrometer in C6D6 (1H:
200.1 MHz, 13C: 50.3 MHz). [(cod)RhCl]2 [19], [(cod)IrCl]2 [19],
[Mn(CO)5Br] [20], [(fluorene)FeCp]PF6 [21], (C5H5)CMe2(C9H7)
[5] and the complexes 2, 4, 2a [7], and 6, 6a, 7a [11] were prepared
by literature methods. Mass spectra (EI, 70 eV) were recorded with
a modified Varian MAT 311A. The X-ray diffraction structural
˚
analyses were performed with Mo Kα radiation (λ ϭ 0.71073 A,
graphite monochromator) at 293 K using the Siemens SMART
CCD area detector diffractometer. All crystal structures were
solved by using the direct method (SHELXS86) and subsequently
refined by full-matrix least-squares method’s (SHELXL93 [22]).
For all structures the final absorption correction was done by SAD-
ABS. The positions of all hydrogen atoms were calculated with a
fixed thermal parameter. The data for structure refinement of 3b,
3a and 5c are listed in table 1, selected bond lengths are summa-
rized in table 2.
Quantum chemical density functional calculations were performed
with the TURBOMOLE [23] (version 5.5) suite of programs. The
calculations were done with a gradient-corrected exchange-corre-
lation functional (BP86), following the work of Becke [24] and Per-
dew [25]. The matrix elements of the Hartree potential were ob-
tained by a density fitting (also known as RI) procedure [26]. Polar-
ised basis sets of triple-zeta quality in the valence shell (TZVP [27])
were used for the carbon and metal atoms, while the hydrogen
atoms carried polarized double-zeta (SVP [28]) basis sets. For the
Rh atoms, the innermost 28 electrons were replaced by a small-
core scalar-relativistic effective core potential [29].
Scheme 4 Reaction scheme for the electrochemical redox behavior
of 5c.
Conclusion
For the synthesis of heterobimetallic complexes the olefin
(C5H5)CMe2(C9H7) is a very useful compound as a bridg-
ing ligand, because the stepwise deprotonation of the five
membered rings is very selective. A further advantage of
this bridging ligand system is its easy rotation around the
C-C-bonds in the C1-bridge, which impart a good flexibility
in conformation of both metal moieties to each other. This
is important for catalytic reactions where both metal com-
plex fragments interact with the substrate in a concerted
fashion. A number of bimetallic complexes have been syn-
thesized and characterized with the metal complex frag-
ments Rh(cod), Ir(cod), Mn(CO)3 and FeCp. Conformation
analysis for two different complexes has given the same
minimum in energy for the anti and one gauche confor-
mation, which both are found in the solid state.
The electronic intermetallic interaction in these com-
plexes has been investigated by electrochemical measure-
ments. In general we presume that a weak electronic inter-
metallic communication can be established in all com-
pounds. The effect of this interaction varies in the cyclic
voltammetries of the heterobimetallic complexes. Some
species show an increase of the potential separation (posi-
tive ∆E), which we call the “normal effect“, but some com-
pounds behave opposite to that (negative ∆E), named the
“unusual effect“. This “unusual effect” is interpreted as an
intramolecular catalytic oxidation. This is the first case in
which such an intramolecular catalytic oxidation is ob-
served.
The electrochemical measurements were performed on a Metrohm
VA693 with a three-electrode configuration in methylene chloride
with scan rates from 50 to 200 mV/s. The supporting electrolyte
was tetrabutylammonium tetrafluoroborate (TBAB) 0.1 M. A Ag/
AgCl/KClaq half cell was used as reference electrode, which was
separated from the sample cell by a second integrated electrolyte
(saturated LiCl in ethanol) to avoid large liquid junction and con-
tamination of the non aqueous cell. A glass frit and a glass mem-
brane separate the electrolytes from each other. A polished Plati-
num disk electrode with a 2 mm diameter was used as the working
electrode, a Pt-wire as the auxiliary electrode. All potentials were
referred to ferrocene-ferrocenium, the value for which was obtained
by subsequent measurement under the same conditions.
Synthesis of [(C9H7)CMe2(η5-C5H4)Ir(cod)] (3): 0.65 ml butyl-
lithium (1.6 mol/l) were added to a solution of 220 mg (0.99 mmol)
(C5H5)CMe2(C9H7) in 20 ml diethyl ether and stirred at room tem-
perature. After 2 h a THF solution of 338 mg (0.5 mmol) [Ir(-
cod)Cl]2 was added and the orange reaction mixture was stirred for
another 2 hours. The solvent was removed in vacuo. The residue
was filtered through a short column of Al2O3. With hexane, 287 mg
(0.55 mmol, 55 %) of [(C9H7)CMe2(η5-C5H4)Ir(cod)] were isolated
as a colorless solid. M(C21H25Ir) ϭ 521.71 g/mol; C: 57.98 (calc.
57.55); H: 5.83 % (5.60) %.
NMR (C6D6) δH ϭ 4.62 (2 H, t, J(HH) 2 Hz, HCp), 4.90 (2 H, t, J(HH)
2 Hz, HCp), 5.97 (1 H, t, J(HH) 2.2 Hz, H2), 2.99 (2 H, d, J(HH) 2.2 Hz,
H3), 1.71 (6H, s, HMe), 7.57 (1 H, d, J(HH) 8 Hz, H7), 7.19 (1 H, d, J(HH)
8 Hz, H6), 7.24 (1 H, m, H5), 7.00 (1 H, m, H4), 3.85 (4 H, br m, Hcod), 2.25
(4 H, m, Hcod), 1.98 (4 H, m, Hcod). δC ϭ 153.0 (C1), 145.8 (C8), 144.1 (C9),
127.5 (C2), 126.0, 124.4, 124.2, 122.7, 113.2 (C5H4), 81.8 (2 C, C5H4), 81.0
(2 C, C5H4), 37.1 (C3), 36.5 (C10), 30.0 (2 C, CMe), 46.5 (4 C, Ccod), 34.4 (4 C,
Ccod). MS (120 °C, EI) m/z ϭ 522 (Mϩ, 100 %), 412 (MϪcodϪH2, 20 %),
405 (MϪIndϪH2, 65 %), 363 (M-CMe2IndϪH2, 40 %).
Experimental Section
Synthesis of [(C9H7)CMe2(η5-C5H4)FeCp] (5): 220 mg
(0.99 mmol) (C5H5)CMe2(C9H7) were dissolved in 20 ml THF in a
100 ml flask and deprotonated with 0.65 ml BuLi (1.6 mol/l) at
room temperature. In another flask the “CpFe” reagent was pre-
Reactions were carried out under nitrogen using conventional
Schlenk techniques. All solvents were dried over sodium / benzo-
phenone and freshly distilled prior to use. The NMR spectra were
548
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Ligand Bridged Heterodinuclear Transition Metal Complexes
pared from 430 mg (0.99 mmol) [CpFe(fluorene)]PF6 and 0.65 ml
BuLi in THF. After 1 h stirring, this blue THF solution was added
at 0 °C to the yellow solution in the first flask and the resulting
reaction mixture was refluxed for 16 h. The solvent was removed
and the residue extracted with pentane / diethyl ether (1:1). Before
the product was isolated by chromatography over a short column
of Al2O3 with hexane, fluorene and ferrocene were removed by sub-
limation at 40 °C. 144 mg (0.42 mmol, 42 %) of [(C9H7)CMe2(η5-
Synthesis of [Rh(cod)(η5-C5H4)CMe2(η5-C9H6)FeCp] (2d):
110 mg (0.25 mmol) of 2 were deprotonated by 0.2 ml BuLi in
20 ml THF. The blue solution prepared from 180 mg (0.42 mmol)
[CpFe(fluorene)]PF6 and 0.3 ml BuLi was added at 0 °C after 1 h.
The reaction mixture was refluxed for 16 h and the solvent was
removed. The residue was extracted by pentane / diethyl ether (1:1).
The oily product 2d was eluted from the chromatographic column
with pentane / diethyl ether as a dark red band after fluorene and
ferrocene in the first two fractions, respectively. Yield: 132 mg
(0.24 mmol, 95 %). M(C30H33FeRh) ϭ 552.33 g/mol; C: 65.48
(calc. 65.24); H: 6.21 (6.02) %.
C5H4)FeCp] were obtained as
a
yellow orange solid.
M(C22H22Fe) ϭ 342.26 g/mol; C: 77.41 (calc. 77.20); H: 6.55
(6.48) %.
NMR (C6D6) δH ϭ 4.92 (2 H, m, C5H4), 4.85 (1 H, m, C5H4), 4.70 (1 H, m,
C5H4), 4.67 (1 H, dd, J(HH) 2.7 ϩ 0.7 Hz, H2), 3.82 (1 H, d, J(HH) 2.7 Hz,
H3), 2.00 (6 H, br s, HMe), 7.72 (1 H, m, H7), 7.39 (1 H, m, H4), 6.82 (1 H,
m, H6), 6.77 (1 H, H5), 3.94 (4 H, m, HRhcod), 2.27 (4 H, m, Hcod), 1.98 (4 H,
m, Hcod), 3.71 (5H, s, CCp). δC ϭ 130.4, 129.8, 123.1, 123.0, 120.5 (C5H4,
J(RhC) 4 Hz), 94.3 (C8), 88.6 (C9), 85.4 (C1), 85.8 (2 C5H4, J(RhC) 3.8 Hz),
85.0 (C5H4, J(RhC) 3.7 Hz), 84.7 (C5H4, J(RhC) 3.7 Hz), 70.7 (C2), 60.3
(C3), 36.7 (C10), 32.4 (2 CMe), 63.0 (4C, J(RhC) 14 Hz, CRhcod), 32.9 (4 C,
CRhcod), 69.3 (5 CCp). MS (140 °C, EI) m/z ϭ 552 (Mϩ, 90 %), 444 (MϪcod,
100 %), 378 (MϪcodϪCpH, 20 %), 323 (MϪcodϪFeCp, 50 %).
NMR (C6D6) δH ϭ 4.05 (2 H, t, J(HH) 2 Hz, C5H4), 3.96 (2 H, t, J(HH)
2 Hz, C5H4), 5.76 (1 H, t, J(HH) 2 Hz, H2), 2.92 (2 H, d, J(HH) 2 Hz, H3),
1.74 (6H, s, HMe), 7.64 (1 H, d, J(HH) 8 Hz, H7), 7.24 (1 H, d, J(HH) 8 Hz,
H4), 7.20 (1 H, t, J(HH) 8 Hz, H5), 7.05 (1 H, t, J(HH) 8 Hz, H6), 4.06 (5 H,
s, CCp). δC ϭ 154.1 (C1), 145.9 (C8), 144.2 (C9), 127.3 (C2), 125.9, 124.3,
124.2, 122.6, 100.4 (C5H4), 67.2 (2 C, C5H4), 67.1 (2 C, C5H4), 36.9 (C3),
36.2 (C10), 28.2 (2 C, CMe), 68.5 (5 C, CCp). MS (100 °C, EI) m/z ϭ 342 (Mϩ,
90 %), 227 (MϪInd, 100 %), 186 (Cp2Fe, 15 %), 121 (M-CpCMe2Ind, 20 %).
Synthesis of [Rh(cod)(η5-C5H4)CMe2(η5-C9H6)Ir(cod)] (2b):
0.4 ml butyllithium (1.3 mol/l) were added to a solution of 253 mg
(0.59 mmol) of 2 in 20 ml THF and stirred at room temperature.
After 2 h stirring, 190 mg (0.28 mmol) [Ir(cod)Cl]2 were added and
stirred for another 8 hours. After removing the solvent, the reaction
mixture was chromatographed on Al2O3. A small amount of educt
was obtained first with pure hexane, before 331 mg (0.45 mmol,
78 %) of 2b were isolated with a hexane / diethyl ether (1:1) mixture
as a pale yellow solid. M(C33H40RhIr) ϭ 731.79 g/mol; C: 53.88
(calc. 54.16); H: 5.32 (5.51) %.
Synthesis of [Ir(cod)(η5-C5H4)CMe2(η5-C9H6)Rh(cod)] (3a):
0.14 ml butyllithium (1.5 mol/l) were added to a solution of 111 mg
(0.21 mmol) of 3 in 20 ml THF and stirred at room temperature.
After 2 h stirring, 52 mg (0.11 mmol) [Rh(cod)Cl]2 were added to
the red reaction mixture and stirred for another 2 hours. After re-
moving the solvent, the reaction mixture was chromatographed on
Al2O3. With pure hexane 145 mg (0.20 mmol, 94 %) of 3a were
obtained as a pale yellow solid. M(C33H40RhIr) ϭ 731.79 g/mol;
C: 53.98 (calc. 54.16); H: 5.72 (5.51) %.
NMR (C6D6) δH ϭ 4.82 (2 H, t, J(HH) 2 Hz, C5H4), 4.63 (1 H, m, C5H4),
4.57 (1 H, m, C5H4), 5.90 (1 H, dd, J(HH) 2.8 ϩ 2 Hz, H2), 4.72 (1 H, dd,
J(HH) 2.8 ϩ 0.6 Hz, H3), 1.76 (3 H, s, HMe), 1.64 (3 H, s, HMe), 7.50 (1 H,
m, H7), 7.16 Ϫ 7.0 (3 H, m, H4Ϫ6), 4.07 (2 H, br m, HRhcod), 4.02 (2 H, br
m, HRhcod), 3.83 (4 H, br m, HIrcod), 2.20 (4 H, m, Hcod), 1.98 Ϫ 1.65 (12 H,
m, Hcod). δC ϭ 122.7, 122.4, 120.6, 120.4, 114.1 (C5H4), 109.6 (C8), 108.8
(C9), 106.5 (C1, J(RhC) 4 Hz), 93.1 (C2, J(RhC) 5 Hz), 73.1 (C3, J(RhC)
5 Hz), 82.1 (C5H4), 81.9 (C5H4), 80.2 (C5H4), 80.1 (C5H4), 36.6 (C10), 31.2
(CMe), 29.8 (CMe), 68.5 (2 C, J(RhC) 13.6 Hz, CRhcod), 68.2 (2 C, J(RhC)
13.4 Hz, CRhcod), 32.1 (2 C, CRhcod), 31.3 (2 C, CRhcod), 46.5 (4 CIrcod), 34.5
(2 CIrcod), 34.4 (2 CIrcod). MS (150 °C, EI) m/z ϭ 732 (Mϩ, 4 %), 622
(MϪcodϪH2, 100 %), 407 (MϪ(Ind)Rh(cod), 20 %).
NMR (C6D6) δH ϭ 4.91 (2 H, m, C5H4), 4.65 (1 H, m, C5H4), 4.53 (1 H, m,
C5H4), 5.78 (1 H, d, J(HH) 2.8 Hz, H2), 4.72 (1 H, d, J(HH) 2.8 Hz, H3),
1.80 (3 H, s, HMe), 1.73 (3 H, s, HMe), 7.42 (1 H, m, H7), 7.16 Ϫ 7.0 (3 H,
m, H4-6), 3.99 (4 H, br m, HRhcod), 3.93 (4 H, br m, HIrcod), 2.24 (8 H, m,
Hcod), 1.96 Ϫ 1.70 (8 H, m, Hcod). δC ϭ 123.5, 123.3, 121.8, 121.7, 120.8
(C5H4, J(RhC) 4 Hz), 109.6 (C8), 108.9 (C9), 101.7 (C1), 86.0 (C5H4, J(RhC)
3.8 Hz), 85.9 (C5H4, J(RhC) 3.8 Hz), 85.5 (C5H4, J(RhC) 3.6 Hz), 84.5
(C5H4, J(RhC) 3.7 Hz), 84.8 (C2), 69.5 (C3), 36.6 (C10), 31.5 (CMe), 30.3
(CMe), 63.0 (4C, J(RhC) 14 Hz, CRhcod), 32.9 (4C, CRhcod), 51.2 (2 C, CIrcod),
50.9 (2 C, CIrcod), 33.6 (2 C, CIrcod), 32.9 (2 C, CIrcod). MS (150 °C, EI)
m/z ϭ 732 (Mϩ, 50 %), 622 (MϪcodϪH2, 100 %), 415 ((Ind)Ir(cod)ϪH,
45 %), 317 (MϪ(Ind)Ir(cod), 34 %).
Synthesis of [Ir(cod)(η5-C5H4)CMe2(η5-C9H6)Ir(cod)] (3b):
1.3 ml butyllithium (1.6 mol/l) were dropped to a THF solution of
220 mg (0.99 mmol) (C5H5)CMe2(C9H7) in 20 ml diethyl ether and
stirred for 4 h at room temperature. 672 mg (1 mmol) [Ir(cod)Cl]2
were added and the orange reaction mixture was stirred for another
6 hours. After the solvent was removed in vacuo, the reaction mix-
ture was filtered through a short column of Al2O3. 509 mg
(0.62 mmol, 62 %) of [Ir(cod)(η5-Cp)CMe2(η5-C9H6)Ir(cod)] 3b
could be isolated as a white solid with hexane. M(C33H40Ir2) ϭ
821.10 g/mol; C: 48.36 (calc. 48.27); H: 4.98 (4.91) %.
Synthesis of [Rh(cod)(η5-C5H4)CMe2(η5-C9H6)Mn(CO)3] (2c):
0.16 ml butyllithium (1.6 mol/l) were added to a solution of 110 mg
(0.25 mmol) of 2 in 20 ml THF and stirred at room temperature.
After 3 h stirring, 80 mg (0.29 mmol) [Mn(CO)5Br] were added.
The orange solution was stirred for another hour then refluxed for
another 6 h. After changing the solvent to pentane / diethyl ether
the reaction mixture was first filtered through Al2O3 to remove the
by-product [Mn2(CO)10] and some unreacted starting material as
the first two yellow bands. The third fraction was chromatographed
again on a long column of Al2O3. 10 mg (0.0175 mmol, 7 %) of 2c
could be isolated as an orange solid with a hexane / benzene mix-
ture. M(C28H28RhMnO3) ϭ 570.36 g/mol; C: 59.14 (calc. 58.96);
H: 4.69 (4.95) %.
NMR (C6D6) δH ϭ 4.81 (2 H, t, J(HH) 2 Hz, C5H4), 4.60 (1 H, t, J(HH)
2 Hz, C5H4), 4.52 (1 H, t, J(HH) 2 Hz, C5H4), 5.76 (1 H, d, J(HH) 2.7 Hz,
H2), 4.71 (1 H, dd, J(HH) 2.7 ϩ 0.6 Hz, H3), 1.67 (3 H, s, HMe), 1.74 (3 H,
s, HMe), 7.48 (1 H, m, H7), 7.1 Ϫ 6.9 (3 H, m, H4Ϫ6), 3.96 (4 H, br m, Hcod),
3.82 (4 H, br m, Hcod), 2.23 (4 H, m, Hcod), 1.95 (4 H, m, Hcod), 1.9 Ϫ 1.6
(8 H, m, Hcod). δC ϭ123.6, 123.3, 121.8, 121.7, 114.1 (C5H4), 109.6 (C8),
108.8 (C9), 100.6 (C1), 84.8 (C2), 82.13 (C5H4), 82.08 (C5H4), 80.1 (C5H4),
80.0 (C5H4), 69.6 (C3), 36.3 (C10), 31.2 (CMe), 29.2 (CMe), 46.5 (4 C, Ccod),
34.5 (2 C, Ccod), 34.3 (2 C, Ccod), 51.2 (2 C, Ccod), 51.0 (2 C, Ccod), 33.6
(2 C, Ccod), 32.9 (2 C, Ccod). MS (150 °C, EI) m/z ϭ 820 (Mϩ, 100 %), 710
(MϪcodϪH2, 70 %), 413 (MϪIr(cod)2, 75 %), 407 (MϪ(Ind)Ir(cod), 45 %).
NMR (C6D6) δH ϭ 4.98 (2 H, m, C5H4), 4.64 (1 H, m, C5H4), 4.60 (1 H, m,
C5H4), 4.42 (1 H, d, J(HH) 2.4 Hz, H2), 4.47 (1 H, d, J(HH) 2.4 Hz, H3),
1.81 (3 H, s, HMe), 1.76 (3 H, s, HMe), 7.43 (1 H, d, J(HH) 8.4 Hz, H7), 7.00
(1 H, d, J(HH) 8.4 Hz, H4), 6.73 (1 H, t, J(HH) 8.4 Hz, H6), 6.58 (1 H, t,
J(HH) 8.4 Hz, H5), 3.93 (4 H, br s, HRhcod), 2.23 (4 H, m, Hcod), 1.93 (4 H,
m, Hcod). δC ϭ 127.3, 126.5, 125.4, 124.9, 118.7 (C5H4, J(RhC) 4 Hz), 104.3
(C8), 103.2 (C9), 102.0 (C1), 85.8 (C5H4, J(RhC) 3.8 Hz), 85.5 (C5H4, J(RhC)
3.8 Hz), 85.2 (C5H4, J(RhC) 3.6 Hz), 84.8 (C5H4, J(RhC) 3.7 Hz), 89.5 (C2),
69.1 (C3), 36.3 (C10), 33.3 (CMe), 32.0 (CMe), 63.2 (2 C, J(RhC) 13.5 Hz,
CRhcod), 63.1 (2 C, J(RhC) 13.5 Hz, CRhcod), 32.7 (4 C, CRhcod). MS (160 °C,
EI) m/z ϭ 570 (Mϩ, 50 %), 486 (MϪ3 CO, 70 %), 406 (MϪcodϪ2 CO,
30 %), 378 (MϪcodϪ3 CO, 10 %), 323 (MϪcodϪMn(CO)3, 100 %).
Synthesis of [Ir(cod(η5-C5H4)CMe2(η5-C9H6)Mn(CO)3] (3c):
0.22 ml butyllithium (1.6 mol/l) were given to a solution of 180 mg
(0.34 mmol) of 3 in 20 ml THF and stirred at room temperature.
After 2 h stirring, 100 mg (0.36 mmol) [Mn(CO)5Br] were added.
Z. Anorg. Allg. Chem. 2006, 541Ϫ552
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
zaac.wiley-vch.de
549

P. Escarpa Gaede, C. van Wüllen
The orange solution was stirred for another hour followed by re-
fluxing for another 6 h. After changing the solvent to pentane /
diethyl ether the reaction mixture was first filtered through Al2O3
to remove the by-product [Mn2(CO)10] as the bright yellow band.
After chromatography of the second fraction on a longer column
of Al2O3, 121 mg (0.18 mmol, 54 %) of 3c were isolated as an yel-
low solid with a hexane / diethyl ether mixture (10 % diethyl ether).
M(C28H28IrMnO3) ϭ 659.68 g/mol; C: 50.74 (calc. 50.98); H:
4.55 (4.28) %.
yellow solid in 75 % yield. M(C28H28IrMnO3) ϭ 659.68 g/mol; C:
50.82 (calc. 50.98); H: 4.35 (4.28) %.
NMR (C6D6) δH ϭ 4.34 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 4.23 (1 H, td,
J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.74 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.65
(1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 5.57 (1 H, d, J(HH) 2.6 Hz, H2), 4.68
(1 H, dd, J(HH) 2.6 ϩ 0.6 Hz, H3), 1.49 (3 H, s, HMe), 1.42 (3 H, s, HMe),
7.28 (1 H, m, H7), 7.05 Ϫ 6.90 (3 H, m, H4Ϫ6), 3.85 (4 H, m, Hcod), 1.77
(8 H, m, Hcod). δC ϭ 225.9 (3 CCO), 123.5, 123.9, 122.0, 120.9, 115.7 (C5H4),
108.6 (C8), 109.8 (C9), 99.7 (C1), 84.9 (C2), 69.9 (C3), 84.4 (C5H4), 84.3
(C5H4), 79.5 (C5H4), 79.2 (C5H4), 35.8 (C10), 30.7 (CMe), 28.6 (CMe), 51.5 (4
Ccod) 33.6 (2 C, Ccod), 32.7 (2 C, Ccod). MS (150 °C, EI) m/z ϭ 660 (Mϩ,
85 %), 576 (MϪ3 CO; 100 %), 524 (MϪcodϪCO, 10 %), 496 (MϪcodϪ2
CO, 25 %), 468 (MϪcodϪ3 CO, 15 %), 413 (MϪcodϪMn(CO)3, 30 %).
NMR (C6D6) δH ϭ 4.90 (2 H, t, J(HH) 2 Hz, C5H4), 4.57 (2 H, t, J(HH)
2 Hz, C5H4), 4.42 (1 H, d, J(HH) 2.4 Hz, H2), 4.46 (1 H, d, J(HH) 2.4 Hz,
H3), 1.75 (3 H, s, HMe), 1.69 (3 H, s, HMe), 7.42 (1 H, d, J(HH) 8 Hz, H7),
7.0 Ϫ 7.16 (3 H, m, H4Ϫ6), 3.80 (4 H, br s, Hcod), 2.20 (4 H, m, Hcod), 1.94
(4 H, m, Hcod). δC ϭ 126.6, 126.5, 125.5, 124.9, 112.0 (C5H4), 104.4 (C8),
104.0 (C9), 102.0 (C1), 82.9 (C5H4), 82.7 (C5H4), 80.6 (C5H4), 80.0 (C5H4),
89.7 (C2), 69.2 (C3), 35.5 (C10), 32.5 (CMe), 31.8 (CMe), 46.6 (4 Ccod), 34.3 (4
Synthesis of [Mn(CO)3(η5-C5H4)CMe2(η5-C9H6)FeCp] (4d): Re-
action was carried out in analogy to 3d. 65 % yield of 4d were
obtained
after
chromatography
as
a
yellow
solid.
M(C25H21FeMnO3) ϭ 480.22 g/mol; C: 62.81 (calc. 62.54); H:
4.62 (4.41) %.
C
cod). MS (160 °C, EI) m/z ϭ 660 (Mϩ, 55 %), 576 (MϪ3 CO; 100 %), 496
(MϪcodϪ2 CO, 4 %), 413 (MϪcodϪMn(CO)3, 30 %), 363
(CpIr(cod)Ϫ3 H, 10 %).
NMR (C6D6) δH ϭ 7.55 (1 H, m, H7), 7.33 (1 H, m, H4), 6.78 (1 H, m, H6),
6.74 (1 H, H5), 4.33 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 4.18 (1 H, td,
J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.75 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.67
(1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 4.65 (1 H, dd, J(HH) 2.7 ϩ 0.7 Hz,
H2), 3.66 (1 H, d, J(HH) 2.7 Hz, H3), 1.84 (3 H, s, HMe), 1.67 (3 H, s, HMe),
3.60 (5 H, s, CCp). δC ϭ 129.9, 129.7, 123.6, 123.2, 115.6 (C5H4), 93.3 (C8),
88.6 (C9), 85.2 (C1), 85.0 (C5H4), 84.3 (C5H4), 79.3 (C5H4), 79.4 (C5H4), 70.3
(C2), 69.3 (5 CCp), 60.7 (C3), 35.0 (C10), 31.8 (CMe), 31.4 (CMe). MS (140 °C,
EI) m/z ϭ 480 (Mϩ, 85 %), 396 (MϪ3 CO, 100 %), 330 (MϪ3 COϪCpH,
15 %), 276 (MϪCpϪMn(CO)3, 60 %).
Synthesis of [Ir(cod)(η5-C5H4)CMe2(η5-C9H6)FeCp] (3d):
230 mg (0.44 mmol) of 3 were deprotonated by 0.3 ml BuLi in
20 ml THF. The blue solution prepared from 200 mg (0.46 mmol)
[CpFe(fluorene)]PF6 and 0.3 ml BuLi was added at 0 °C after 1 h.
The reaction mixture was refluxed for 16 h before the solvent was
removed. The solid was extracted with pentane / diethyl ether (1:1).
Fluorene and ferrocene were removed by sublimation at 50 °C be-
fore the residue was filtered over Al2O3 with pentane. After some
educt 3, the oily product 3d (145 mg, 0.23 mmol, 51 %) was eluted
secondly as a dark red band with pentane / diethyl ether.
M(C30H33FeIr) ϭ 641.65 g/mol; C: 55.97 (calc. 56.16); H: 4.98
(5.18) %.
Synthesis of [CpFe(η5-C5H4)CMe2(η5-C9H6)Rh(cod)] (5a):
0.4 ml butyllithium (1.6 mol/l) were dropped to a solution of
171 mg (0.50 mmol) of
5 in 20 ml THF. After 2 h 123 mg
(0.25 mmol) [Rh(cod)Cl]2 were added to the reaction mixture and
stirred for another 6 hours. After removing the solvent, the reaction
mixture was chromatographed on Al2O3. The orange-yellow band
containing 229 mg (0.41 mmol, 83 %) of 5a was eluted with pen-
tane after the yellow fraction of unreacted starting material.
M(C20H23Rh) ϭ 366.30 g/mol; C: 65.31 (calc. 65.58); H: 6.47 %
(6.33) %.
NMR (C6D6) δH ϭ 4.85 (2 H, t, J(HH) 2 Hz, C5H4), 4.61 (2 H, t, J(HH)
2 Hz, C5H4), 4.67 (1 H, dd, J(HH) 2.6 ϩ 0.6 Hz, H2), 3.79 (1 H, d, J(HH)
2.6 Hz, H3), 1.94 (3 H, s, HMe), 1.93 (3 H, s, HMe), 7.70 (1 H, m, H7), 7.35
(1 H, m, H4), 6.81 (1 H, m, H6), 6.77 (1 H, H5), 3.81 (4 H, m, Hcod), 2.20
(4 H, m, Hcod), 1.98 (4 H, m, Hcod), 3.67 (5 H, s, CCp). δC ϭ 130.4, 129.8,
123.2, 123.0, 114.0 (C5H4), 93.3 (C8), 88.6 (C9), 85.3 (C1), 81.9 (C5H4), 81.8
(C5H4), 80.5 (C5H4), 80.1 (C5H4), 70.8 (C2), 60.3 (C3), 35.5 (C10), 32.2 (CMe),
32.0 (CMe), 46.5 (2 Ccod), 46.4 (2 Ccod), 34.5 (2 Ccod), 34.4 (2 Ccod), 69.3 (5
CCp). MS (140 °C, EI) m/z ϭ 642 (Mϩ, 100 %), 627 (MϪMe, 15 %), 532
(MϪcodϪH2, 25 %), 413 (MϪcodϪFeCp, 20 %).
NMR (C6D6) δH ϭ 4.02 (2 H, m, C5H4), 3.90 (2 H, m, C5H4), 5.74 (1 H, dd,
J(HH) 2.8 ϩ 2 Hz, H2), 4.46 (1 H, dd, J(HH) 2.8 ϩ 0.6 Hz, H3), 1.76 (3 H,
s, HMe), 1.65 (3 H, s, HMe), 7.51 (1 H, d, J(HH) 8 Hz, H7), 7.06 (3 H, m,
H4Ϫ6), 4.03 (4 H, br m, HRhcod), 1.90Ϫ1.60 (8 H, m, Hcod), 4.02 (5 H, s,
CCp). δC ϭ 68.7 (5 CCp), 122.5, 122.2, 120.6, 120.3, 112.3 (C8, J(RhC)
1.9 Hz), 113.5 (C9, J(RhC) 1.8 Hz), 107.9 (C1, J(RhC) 4 Hz), 101.3 (C5H4),
93.1 (C2, J(RhC) 5 Hz), 72.9 (C3, J(RhC) 5 Hz), 67.9 (C5H4), 67.3 (C5H4),
66.8 (C5H4), 66.7 (C5H4), 36.1 (C10), 29.7 (CMe), 29.5 (CMe), 68.3 (2 C,
J(RhC) 13.8 Hz, Ccod), 68.1 (2 C, J(RhC) 13.8 Hz, Ccod), 32.0 (2 C, Ccod),
31.3 (2 C, Ccod). MS (150 °C, EI) m/z ϭ 552 (Mϩ, 50 %), 444 (MϪcod,
100 %), 378 (MϪcod-CpH, 20 %), 323 (MϪcodϪCpFe, 60 %).
Synthesis of [Mn(CO)3(η5-C5H4)CMe2(η5-C9H6)Rh(cod)] (4a):
When 0.14 ml butyllithium (1.5 mol/l) were added to a solution of
55 mg (0.15 mmol) of 4 in 20 ml THF, the solution color changed
immediately from yellow to red. After 2 h stirring 40 mg
(0.08 mmol) [Rh(cod)Cl]2 were added to the red reaction mixture
and stirred for another 4 hours. After removing the solvent, the
residue was chromatographed on Al2O3. With hexane / diethyl
ether 65 mg (0.11 mmol, 73 %) of 4a were obtained as a yellow
solid. M(C28H28RhMnO3) ϭ 570.36 g/mol; C: 59.33 (calc. 58.96);
H: 5.11 (4.95) %.
Synthesis of [CpFe(η5-C5H4)CMe2(η5-C9H6)Ir(cod)] (5b): Reac-
tion was carried out in analogy to 5a. A yellow solid (48 % yield)
of 5b was obtained. M(C30H33FeIr) ϭ 641.65 g/mol; C: 55.88 (calc.
56.16); H: 5.08 (5.18) %.
NMR (C6D6) δH ϭ 4.02 (5 H, s, CCp), 4.00 (4 H, m, C5H4), 5.60 (1 H, d,
J(HH) 2.7 Hz, H2), 4.66 (1 H, dd, J(HH) 2.7 ϩ 0.7 Hz, H3), 1.68 (3 H, s,
HMe), 1.75 (3 H, s, HMe), 7.48 (1 H, m, H7), 7.10 Ϫ 6.90 (3 H, m, H4Ϫ6),
3.85Ϫ3.95 (4 H, m, Hcod), 1.90Ϫ1.85 (8 H, m, Hcod). δC ϭ 68.7 (5 CCp),
123.4, 123.2, 121.8, 121.7, 115.7 (C5H4), 108.6 (C8), 109.8 (C9), 101.9 (C1),
101.3 (C5H4), 84.7 (C2), 70.3 (C3), 67.0 (C5H4), 67.3 (C5H4), 66.8 (C5H4),
66.5 (C5H4), 36.8 (C10), 29.6 (CMe), 29.5 (CMe), 50.7 (2 Ccod), 50.9 (2 Ccod),
33.6 (2 C, Ccod), 32.8 (2 C, Ccod). MS (150 °C, EI) m/z ϭ 642 (Mϩ, 100 %),
534 (MϪcod, 40 %), 413 (MϪcodϪCpFe, 30 %).
NMR (C6D6) δH ϭ 4.39 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 4.27 (1 H, td,
J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.74 (1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 3.65
(1 H, td, J(HH) 2.8 ϩ 1.7 Hz, C5H4), 5.73 (1 H, dd, J(HH) 2.9 ϩ 2 Hz, H2),
4.48 (1 H, dd, J(HH) 2.9 ϩ 0.6 Hz, H3), 1.53 (3 H, s, HMe), 1.39 (3 H, s,
HMe), 7.28 (1 H, m, H7), 7.05 (3 H, m, H4Ϫ6), 3.93 (4 H, m, HRhcod), 1.18
(4 H, m, Hcod), 1.35 (4 H, m, Hcod). δC ϭ 225.9 (3 CCO), 123.0, 122.5, 120.8,
119.7, 113.7 (C5H4), 113.7 (C8, J(RhC) 2.6 Hz), 112.3 (C9, J(RhC) 1.8 Hz),
105.4 (C1, J(RhC) 4 Hz), 92.7 (C2, J(RhC) 5 Hz), 73.4 (C3, J(RhC) 5 Hz),
84.9 (C5H4), 84.3 (C5H4), 79.5 (C5H4), 79.2 (C5H4), 35.9 (C10), 30.8 (CMe),
28.5 (CMe), 68.5 (2 C, J(RhC) 13.2 Hz, Ccod), 68.8 (2 C, J(RhC) 13.5 Hz,
Ccod), 32.0 (2 C, Ccod), 31.1 (2 C, Ccod). MS (150 °C, EI) m/z ϭ 570 (Mϩ,
50 %), 486 (MϪ3CO, 30 %), 434 (MϪcodϪCO, 40 %), 406 (MϪcodϪ2 CO,
100 %), 378 (MϪcodϪ3 CO, 30), 323 (MϪcodϪMn(CO)3, 90 %).
Synthesis of [CpFe(η5-C5H4)CMe2(η5-C9H6)Mn(CO)3] (5c):
0.3 ml butyllithium (1.6 mol/l) were given to a solution of 165 mg
(0.48 mmol) of 5 in 20 ml THF and stirred at room temperature.
After 2 h stirring, 132 mg (0.48 mmol) [Mn(CO)5Br] were added.
The orange solution was stirred for another hour followed by re-
fluxing for another 10 h. After changing the solvent to pentane /
Synthesis of [Mn(CO)3(η5-C5H4)CMe2(η5-C9H6)Ir(cod)] (4b):
Reaction was carried out in analogy to 4a. 4b was obtained as a
550
zaac.wiley-vch.de
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2006, 541Ϫ552

Ligand Bridged Heterodinuclear Transition Metal Complexes
4.11 (1 H, m, H3), 5.82 (1 H, t, J(HH) 2 Hz, H2Ј), 2.96 (2 H, d, J(HH) 2 Hz,
H3Ј), 1.80 / 1.68 (each 3 H, s, HMe), 1.70 (6 H, s, HMeЈ). δC ϭ 225.8 (3 CCO),
153.9 (C1Ј), 145.9 (C8Ј), 144.1 (C9Ј), 126.5, 126.4, 125.9, 125.4, 124.9, 124.4,
124.3, 122.7, 105.7 (C8), 104.0 (C9), 102.1 (C1), 100.4 (C5H4Ј), 99.6 (C5H4),
89.7 (C2), 68.9 (C3), 67.1 Ϫ 70.0 (8 C5H4), 37.1 (C3Ј), 36.3 (C10), 35.2 (C10Ј),
28.7 / 28.6 (2 CMe), 31.6 / 31.0 (2 CMe). MS (130 °C, EI) m/z ϭ 636 (Mϩ,
100 %), 552 (MϪ3 CO, 20 %), 521 (MϪInd, 20 %), 396 (MϪ3
COϪIndCMe2, 100 %), 276 (MϪIndϪIndMn(CO)3, 80 %).
diethyl ether, the reaction mixture was first filtered through Al2O3
to remove the byproduct [Mn2(CO)10] as the bright yellow band.
After chromatography of the second fraction on a long column of
Al2O3, 180 mg (0.37 mmol, 78 %) of 5c were isolated as a yellow
solid with a hexane / diethyl ether mixture (10 % diethyl ether).
M(C25H21FeMnO3) ϭ 480.22 g/mol; C: 62.61 (calc. 62.54); H:
4.52 (4.41) %.
Synthesis of {Fe[(η5-C5H4)CMe2(η5-C9H6)Ir(cod)]2} (7b): Reac-
tion was carried out in analogy to 7a [11]. The yellow solid of 7b
was obtained in 61 % yield. M(C50H56FeIr2) ϭ 1097.26 g/mol; C:
54.97 (calc. 54.73); H: 5.32 (5.14) %.
NMR (C6D6) δH ϭ 7.42 (1 H, dd, J(HH) 8 ϩ 0.7 Hz, H7), 6.71 (1 H, dt,
J(HH) 8 ϩ 0.7 Hz, H4), 6.71 (1 H, td, J(HH) 8 ϩ 0.7 Hz, H6), 6.57 (1 H, td,
J(HH) 8 ϩ 0.7 Hz, H5), 4.06 (2 H, m, C5H4), 3.98 (2 H, m, C5H4), 4.31 (1 H,
d, J(HH) 3 Hz, H2), 4.35 (1 H, d, J(HH) 3 Hz, H3), 1.81 (3 H, s, HMe), 1.67
(3 H, s, HMe), 3.99 (5 H, s, CCp). δC ϭ 126.5, 126.4, 125.4, 124.9, 99.6 (C5H4),
105.7 (C8), 104.0 (C9), 102.1 (C1), 89.7 (C2), 68.7 (C3), 68.9 (5 CCp), 67.7
(C5H4), 67.6 (C5H4), 67.4 (C5H4), 66.7 (C5H4), 35.0 (C10), 31.6 (CMe), 30.9
(CMe), 225.8 (3 CCO). MS (130 °C, EI) m/z ϭ 480 (Mϩ, 20 %), 424 (MϪ2
CO, 20 %), 396 (MϪ3 CO, 90 %), 227 (MϪIndMn(CO)3, 100 %).
NMR (C6D6) δH ϭ 7.50 (2 H, d, J(HH) 8 Hz, H7), 7.0 Ϫ 7.16 (6 H, m,
H4Ϫ6), 4.05Ϫ3.88 (16 H, m, C5H4,cod), 5.68 (1 H, t, J(HH) 2.4 Hz, H2), 4.64
(1 H, d, J(HH) 2.4 Hz, H3), 1.72 / 1.71 / 1.62 / 1.39 (each 3 H, s, HMe), 1.90 /
1.78 (each 8 H, m, Hcod). δC ϭ 123.4, 123.2, 121.8, 121.7, 101.5 (2 C5H4),
109.5 (2 C8), 108.5 (2 C9), 102.0 (2 C1), 84.7 (2 C2), 69.4 (2 C3), 67.8Ϫ68.2
(8 C5H4), 36.0 (2 C10), 29.8 / 29.8 / 29.7 / 29.6 (4 CMe), 50.9 (4 Ccod), 51.0 (4
Ccod), 33.7 (4 C, Ccod), 32.9 (4 C, Ccod). MS (170 °C, EI) m/z ϭ 1096 (Mϩ,
100 %), 986 (MϪcodϪH2, 20 %), 878 (MϪ2 codϪH2), 682
(MϪ(Ind)Ir(cod), 10 %), 413 (30 %), 267 (50 %).
Synthesis of [CpFe(η5-C5H4)CMe2(η5-C9H6)FeCp] (5d): 2.0 ml
butyllithium (1.6 mol/l) were dropped to a solution of 330 mg
(1.49 mmol) (C5H5)CMe2(C9H7) in 20 ml diethyl ether and stirred
at room temperature. After 4 h stirring, the blue THF solution pre-
pared from 1.35 g (3.1 mmol) [CpFe(fluorene)]PF6 and 2.0 ml BuLi
was added. The reaction mixture was refluxed for 16 h before the
solution was concentrated to 1 ml. The reaction mixture was
quenched with 10 ml pentane and filtered over 1 cm of Al2O3. Flu-
orene and ferrocene were removed from the dried filtrate by subli-
mation at 50 °C. The residue was filtered again with pentane over
6 cm of Al2O3. 478 mg (0.74 mmol, 50 %) of [CpFe(η5-
C5H4)CMe2(η5-C9H6)FeCp] 5d were isolated as a deep red solid.
M(C27H26Fe2) ϭ 642.19 g/mol; C 70.22 (calc. 70.16); H: 5.74
(5.67) %.
Synthesis of {Fe[(η5-C5H4)CMe2(η5-C9H6)Mn(CO)3]2} (7c): Re-
action was carried out in analogy to 6c with the double stoichio-
metric amount of base and manganese reagent. 7c could not be
isolated from by-products by chromatography. MS (170 °C, EI)
m/z ϭ 774 (Mϩ, 20 %), 718 (MϪ2 CO, 30).
Supporting material: Full Crystallographic data, ORTEP diagram
for the structural analysis of the compounds 3a, 3b and 5c and the
CV of all species are available.
Acknowledgement. We like to thank the Deutsche Forschungsge-
meinschaft (DFG) and the Graduiertenkolleg “Synthetische, mecha-
nistische und reaktionstechnische Aspekte von Metallkatalysatoren”
for financial support.
NMR (C6D6) δH ϭ 7.72 (1 H, m, H7), 7.37 (1 H, m, H4), 6.81 (1 H, dt,
J(HH) 5 ϩ 1.5 Hz, H6), 6.78 (1 H, dt, J(HH) 5 ϩ 1.5 Hz, H5), 4.05 (2 H, m,
C5H4), 3.93 (2 H, m, C5H4), 4.65 (1 H, dd, J(HH) 2.7 ϩ 0.7 Hz, H2), 3.67
(1 H, d, J(HH) 2.7 Hz, H3), 2.02 (3 H, s, HMe), 1.90 (3 H, s, HMe), 3.70 (5 H,
s, CCp), 4.05 (5 H, s, C5H4). δC ϭ 130.4, 129.8, 123.0, 122.9, 101.3 (C5H4),
94.4 (C8), 88.6 (C9), 85.1 (C1), 67.1 (C5H4), 67.2 (C5H4), 67.1 (C5H4), 66.7
(C5H4), 70.8 (C2), 69.2 (5 C5H4), 68.7 (5 CCp), 60.2 (C3), 35.0 (C10), 31.6
(CMe), 31.1 (CMe). MS (140 °C, EI) m/z ϭ 462 (Mϩ, 100 %), 447 (MϪMe,
70 %), 276 (MϪFeCp2, 60 %), 261 (MϪFeCp2ϪMe, 20 %).
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of
[(C9H7)CMe2(η5-C5H4)Fe(η5-C5H4)CMe2(η5-
C9H6)Ir(cod)] (6b): Reaction was carried out in analogy to 6a [11].
66 % yield of 6b was obtained as a yellow solid. M(C42H45FeIr) ϭ
797.87 g/mol; C: 66.47 (calc. 66.22); H: 5.44 (5.68) %.
NMR: δH, (C6D6): 4.08 (8 H, m, C5H4), 5.82 (1 H, t, J(HH) 2.4 Hz, H2),
5.64 (1 H, t, J(HH) 2 Hz, H2Ј), 4.67 (1 H, d, J(HH) 2.4 Hz, H3), 2.96 (2 H,
d, J(HH) 2 Hz, H3Ј), 1.76 (6 H, s, HMeЈ), 1.71 / 1.74 (each 3 H, s, HMe), 7.60
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7.16 Ϫ 7.0 (5 H, m, H4ЈϪ6Ј,4Ϫ5), 3.98 (4 H, m, Hcod), 1.90 / 1.78 (each 4 H,
m, Hcod). δC ϭ 67.0 Ϫ 68.5 (4 C5H4), 145.9 (C8Ј), 144.2 (C9Ј), 125.9, 124.3,
124.2, 123.4, 123.2, 122.7, 121.8, 121.7, 115.7 (C5H4), 102.0 (C5H4), 108.8
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Synthesis
of
[(C9H7)CMe2(η5-C5H4)Fe(η5-C5H4)CMe2(η5-
C9H6)Mn(CO)3] (6c): Reaction was carried out in analogy to 5c
using 130 mg (0.26 mmol) of 6, 0.2 ml butyllithium (1.6 mol/l) and
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could be isolated by chromatography in the second fraction as a
yellow solid with a hexane / diethyl ether mixture (10 % diethyl
ether). M(C37H33FeMnO3) ϭ 636.44 g/mol; C: 69.71 (calc. 69.83);
H: 5.14 (5.23) %.
NMR (C6D6) δH ϭ 7.60 (1 H, d, J(HH) 8 Hz, H7Ј), 7.42 (1 H, d, J(HH)
8 Hz, H7), 7.24 (1 H, m, H4Ј) 6.68 (1 H, tt, J(HH) 8 ϩ 1 Hz, H5), 6.62 (1 H,
td, J(HH) 8 ϩ 1 Hz, H6), 7.0 Ϫ 7.16 (3 H, m, H4,5ЈϪ6Ј), 4.34 (2 H, m, C5H4),
4.04 (4 H, m, C5H4), 3.97 (2 H, m, C5H4), 3.88 (1 H, t, J(HH) 1.7 Hz, H2),
Z. Anorg. Allg. Chem. 2006, 541Ϫ552
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
zaac.wiley-vch.de
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