Heterobi- and heterotrimetallic transition metal complexes with carbon-rich bridging units

Article abstract of DOI:10.1021/om0602355

The syntheses of heterobi- and heterotrimetallic complexes based on (2,2′-bipyridine-5-ylethynyl)-ferrocene (3) are described. Complex 3 is accessible by the Pd(II)/Cu(I)-catalyzed Sonogashira cross-coupling of FcC≡CH (1) (Fc = (η⁵-C₅H₄) (η⁵-C₅H₅)Fe) with 5-bromo-2,2′- bipyridine (2). The complexation behavior of 3 was investigated. Treatment of 3 with (nbd)Mo(CO)₄ (4a) (nbd = norbornadiene) at 25 °C, or refluxing 3 with Mn(CO)₅Br (4b), (Me₂S) ₂PtCl₂ (4c), and Ru(bipy)₂Cl ₂·2H₂O (4d) (bipy = 2,2′-bipyridine), respectively, gave the respective heterobimetallic complexes FcC≡C-bipy(ML_n) (5: ML_n = Mo(CO)₄, 6: ML_n = Mn(CO)₃Br, 7: ML_n = PtCl₂, 8: ML_n = [Ru(bipy)₂](PF₆)₂). Heterotrimetallic FcC≡C-bipy{[Pt(μ-σ,π-C≡CSiMe ₃)₂]CuFBF₃} (12) can be obtained by the subsequent reaction of 7 with Me₃SiC≡CH (9) and [Cu(N≡CMe)₄]BF₄ (11), while [FcC≡C-bipy{[Ti] (μ-σ,π-C≡CSiMe₃)₂}M]X (14a: M = Cu, X = PF₆; 14b: M = Ag, X = ClO₄; [Ti] = (η⁵- C₅H₄SiMe₃)₂Ti) were formed by combining 3 with {[Ti](μ-σ,π-C≡CSiMe₃) ₂}MX (13a: MX = Cu(N≡CMe)PF₆,13b: MX = AgOClO ₃). The identity of 3,10, and 14a was confirmed by single-crystal X-ray structural studies. The main characteristic features of 3 and 10 are the almost eclipsed conformation of the ferrocene cyclopentadienyl rings, the linear C_Cp-C≡C-C_bipy moieties, and the coplanarity of both the pyridine and the C₅H₄ rings. The latter structural motif allows an optimal overlap between the π-orbitals of the cyclopentadienyl, ethynyl, and pyridyl rings. However, in 14a the bipy ligand is tilted by 96.9° toward the η⁵-C₅H₄ unit, which most likely is attributable to cell-packing effects. The platinum atom in 10 is held in a somewhat distorted square-planar surrounding. The chelated copper(I) ion in 14a possesses a pseudotetrahedral coordination geometry. Mononuclear 3 exhibits redox peaks in its cyclic voltammogram (E ₀ = 0.10 V, ΔE_P = 194 mV) for the Fe ²⁺/Fe³⁺ redox couple of the Fc unit and for the bipy ligand (E_0.1 = -2.36 V, ΔE_p = 200 mV; E _0.2 = -2.76 V, ΔE_p = 430 mV). Compounds 10, 12, 14a, and 14b additionally show electrode potentials attributed to the respective ML_n building blocks.

Full text of DOI:10.1021/om0602355

Organometallics 2006, 25, 4579-4587
4579
Heterobi- and Heterotrimetallic Transition Metal Complexes with
Carbon-Rich Bridging Units
Rico Packheiser, Bernhard Walfort, and Heinrich Lang*
Lehrstuhl fu¨r Anorganische Chemie, Institut fu¨r Chemie, Fakulta¨t fu¨r Naturwissenschaften, Technische
UniVersita¨t Chemnitz, Strasse der Nationen 62, 09111 Chemnitz, Germany
ReceiVed March 14, 2006
The syntheses of heterobi- and heterotrimetallic complexes based on (2,2′-bipyridine-5-ylethynyl)-
ferrocene (3) are described. Complex 3 is accessible by the Pd(II)/Cu(I)-catalyzed Sonogashira cross-
coupling of FcCtCH (1) (Fc ) (η5-C5H4)(η5-C5H5)Fe) with 5-bromo-2,2′-bipyridine (2). The complexation
behavior of 3 was investigated. Treatment of 3 with (nbd)Mo(CO)4 (4a) (nbd ) norbornadiene) at 25
°C, or refluxing 3 with Mn(CO)5Br (4b), (Me2S)2PtCl2 (4c), and Ru(bipy)2Cl2‚2H2O (4d) (bipy ) 2,2′-
bipyridine), respectively, gave the respective heterobimetallic complexes FcCtC-bipy(MLn) (5: MLn )
Mo(CO)4, 6: MLn ) Mn(CO)3Br, 7: MLn ) PtCl2, 8: MLn ) [Ru(bipy)2](PF6)2). Heterotrimetallic
FcCtC-bipy{[Pt(µ-σ,π-CtCSiMe3)2]CuFBF3} (12) can be obtained by the subsequent reaction of 7
with Me3SiCtCH (9) and [Cu(NtCMe)4]BF4 (11), while [FcCtC-bipy{[Ti](µ-σ,π-CtCSiMe3)2}M]X
(14a: M ) Cu, X ) PF6; 14b: M ) Ag, X ) ClO4; [Ti] ) (η5-C5H4SiMe3)2Ti) were formed by combining
3 with {[Ti](µ-σ,π-CtCSiMe3)2}MX (13a: MX ) Cu(NtCMe)PF6, 13b: MX ) AgOClO3). The identity
of 3, 10, and 14a was confirmed by single-crystal X-ray structural studies. The main characteristic features
of 3 and 10 are the almost eclipsed conformation of the ferrocene cyclopentadienyl rings, the linear
CCp-CtC-Cbipy moieties, and the coplanarity of both the pyridine and the C5H4 rings. The latter structural
motif allows an optimal overlap between the π-orbitals of the cyclopentadienyl, ethynyl, and pyridyl
rings. However, in 14a the bipy ligand is tilted by 96.9° toward the η5-C5H4 unit, which most likely is
attributable to cell-packing effects. The platinum atom in 10 is held in a somewhat distorted square-
planar surrounding. The chelated copper(I) ion in 14a possesses a pseudotetrahedral coordination geometry.
Mononuclear 3 exhibits redox peaks in its cyclic voltammogram (E0 ) 0.10 V, ∆Ep ) 194 mV) for the
Fe2+/Fe3+ redox couple of the Fc unit and for the bipy ligand (E0.1 ) -2.36 V, ∆Ep ) 200 mV; E0.2
)
-2.76 V, ∆Ep ) 430 mV). Compounds 10, 12, 14a, and 14b additionally show electrode potentials
attributed to the respective MLn building blocks.
istry.2 Conjugated pyridines and alkynyl-functionalized bipy-
ridines with an end-capped ferrocene moiety offer the possibility
to function as valuable precursors for the synthesis of diverse
heterometallic complexes.3
We report here the synthesis of (2,2′-bipyridine-5-ylethynyl)-
ferrocene and its complexation behavior toward different
transition metal fragments. The electrochemical and structural
properties of the resulting heterodi- and heterotrimetallic
complexes are discussed as well.
Introduction
The study of homo- and heterometallic transition metal
complexes in which the metal atoms are connected by π-con-
jugated organic and/or inorganic carbon-rich units is an intrigu-
ing area of research, since such species may offer the possibility
to study electronic communication between the redox-active
termini, exhibit nonlinear optical properties, or provide, for
example, cooperative effects in homogeneous catalysis.1 Owing
to the redox chemistry, chemical robustness, and synthetic
versatility, ferrocenyl building blocks have attracted significant
attention as excellent donor groups in transition metal chem-
Results and Discussion
The synthesis of (2,2′-bipyridine-5-ylethynyl)ferrocene (3)
was accomplished by the palladium(II)/copper(I)-catalyzed
Sonogashira cross-coupling of FcCtCH (1) (Fc ) Fe(η5-C5H4)-
(η5-C5H5)) with 5-bromo-2,2′-bipyridine (2) in refluxing diiso-
propylamine (eq 1). After appropriate workup, complex 3 was
obtained as an orange, air-stable solid in 68% yield, which
* To whom correspondence should be addressed. E-mail:
heinrich.lang@chemie.tu-chemnitz.de.
(1) (a) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger, M.; Gladysz, J. A.
J. Am. Chem. Soc. 2000, 122, 810. (b) Jiao, H.; Costuas, K.; Gladysz, J.
A.; Halet, J. F.; Guillemot, M.; Toupet, L.; Paul, F.; Lapinte, C. J. Am.
Chem. Soc. 2003, 125, 9511. (c) Geiger, W. E. J. Organomet. Chem. 1990,
22, 142. (d) Skibar, W.; Kopacka, H.; Wurst, K.; Salzmann, C.; Ongania,
K.; De Biani, F. F.; Zanello, P.; Bildstein, B. Organometallics 2004, 23,
1024. (e) Hjelm, J.; Handel, R. W.; Hagfeldt, A.; Constable, E. C.;
Housecroft, C. E.; Forster, R. J. Inorg. Chem. 2005, 44, 1073. (f) Long, N.
J. Angew. Chem., Int. Ed. Engl. 1995, 34, 21. (g) Sterzo, C. L.; Stille, J. K.
Organometallics 1990, 9, 687. (h) Bunz, U. H. F.; Enkelmann, V.; Ra¨der,
J. Organometallics 1993, 12, 4745. (i) Wiegelmann, J. E. C.; Bunz, U. H.
F. Organometallics 1993, 12, 3792.
(2) Special issue, “50th Anniversary of the Discovery of Ferrocene”, J.
Organomet. Chem. 2001, 637-639 (Adams, R. D., Ed.), and references
therein.
(3) (a) Lin, J. T.; Wu, J. J.; Li, C. S.; Wen, Y. S.; Lin, K. J.
Organometallics 1996, 15, 5028. (b) Lindner, E.; Zong, R.; Eichele, K.;
Stro¨bele, M. J. Organomet. Chem. 2002, 660, 78. (c) Braga, D.; D’Addario,
D.; Polito, M.; Grepioni, F. Organometallics 2004, 23, 2810.
10.1021/om0602355 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 08/16/2006

4580 Organometallics, Vol. 25, No. 19, 2006
Packheiser et al.
Scheme 1. Synthesis of 10 and 12
Table 1. Synthesis of Heterobimetallic 5-8
dissolves in organic solvents, such as petroleum ether, toluene,
diethyl ether, and dichloromethane.
compd
MLnL′m
MLn
yield [%]a
5
6
7
8
(nbd)Mo(CO)4b (4a)
Mn(CO)5Br (4b)
Mo(CO)4
Mn(CO)3Br
PtCl2
77
59
65
92
(Me2S)2PtCl2 (4c)
Ru(bipy)2Cl2‚2H2Oc (4d)
[Ru(bipy)2](PF6)2
d
a Based on 3. b nbd ) norbornadiene. c bipy ) 2,2′-bipyridine. d Obtained
from the reaction of 3 with 4d followed by treatment of [3‚Ru(bipy)2]Cl2
with NH4PF6.
Treatment of 7 with an excess of Me3SiCtCH (9) in the
presence of catalytic amounts of [CuI] in a 5:1 mixture of
dichloromethane and diisopropylamine produced with concomi-
tant precipitation of [N(iC3H7)2H2]Cl pale red FcCtC-bipy[Pt-
(CtCSiMe3)2] (10), which in a further reaction with [Cu(NtC-
Me)4]BF4 (11) in 1:1 stoichiometry gave deep purple FcCtC-
bipy{[Pt(µ-σ,π-CtCSiMe3)2]CuFBF3} (12) in a 63% overall
yield (Scheme 1).
It also was possible to synthesize heterotrimetallic Fe-Ti-M
complexes with M ) Cu and Ag, respectively (eq 3). Structural
type [FcCtC-bipy{[Ti](µ-σ,π-CtCSiMe3)2}M]X (14a: M )
Cu, X ) PF6; 14b: M ) Ag, X ) ClO4; [Ti] ) (η5-C5H4-
SiMe3)2Ti) molecules are accessible by combining mononuclear
3 with heterobimetallic {[Ti](µ-σ,π-CtCSiMe3)2}MX (13a:
MX ) Cu(NtCMe)PF6, 13b: MX ) AgOClO3) in tetrahy-
drofuran at 25 °C. In 14a and 14b the group 11 metals copper
and silver are chelate-bonded by the organometallic π-tweezer
[Ti](CtCSiMe3)2 and the bipy ligand resulting in tetracoordi-
nation at M. While red 14a and 14b are stable in the solid state,
they slowly start to decompose in solution on exposure to air;
that is, 14b gives elemental silver along with 3 and [Ti](CtC-
SiMe3)2.
The reaction of 3 with (nbd)Mo(CO)4 (4a) (nbd ) norbor-
nadiene) in a mixture of dichloromethane/tetrahydrofuran (ratio
5:1) at 25 °C afforded FcCtC-bipy(Mo(CO)4) (5) upon replace-
ment of nbd by bipy (eq 2, Table 1). Refluxing 3 in the presence
of Mn(CO)5Br (4b), (Me2S)2PtCl2 (4c), or Ru(bipy)2Cl2‚2H2O
(4d) (bipy ) 2,2′-bipyridine) in ethanol or toluene as solvent
produced the respective heterobimetallic complexes FcCtC-
bipy(MLn) (6: MLn ) Mn(CO)3Br (elimination of two carbo-
nyls), 7: MLn ) PtCl2 (loss of SMe2), 8: MLn ) [Ru(bipy)2]-
(PF6)2) (eq 2, Table 1). Complex 8 was formed after subsequent
precipitation with aqueous ammonium hexafluorophosphate.
Complexes 3, 5-8, 10, 12, and 14 were characterized by
elemental analysis, IR, and NMR spectroscopy. ESI-TOF mass
spectrometric experiments were additionally carried out with
7, 10, and 12. The identity of 3, 10, and 14a was further
confirmed by single-crystal X-ray diffraction studies.
Characteristic in the IR spectra of 3 is the CtC stretching
vibration at 2205 cm-1 for the CtC-bipy unit. For all other
species this absorption is observed at almost the same value
(2199-2209 cm-1) (Experimental Section). Further representa-
tive vibrations are νCO (5, 6), νCtC (TiCtCSiMe3: 14a, 14b;
PtCtCSiMe3: 10, 12), νPF (8, 14a), νBF (12), and νClO (14b),
showing the expected patterns; for example, FcCtC-bipy(Mo-
The progress of the complexation of 3 with MLn can nicely
be monitored by the color change upon addition of MLnL′m
(Table 1), whereby the orange solution of 3 turned red (5, 6, 8)
or deep purple (7) during the course of the reaction.

Heterobi- and Heterotrimetallic Transition Metal Complexes
Organometallics, Vol. 25, No. 19, 2006 4581
Figure 1. ORTEP plot (50% probability level) of 3 with the atom-
numbering scheme. Selected bond distances (Å) and angles (deg):
C10-C11, 1.452(5); C11-C12, 1.165(4); C12-C13, 1.447(4); Fe1-
D1, 1.649(6); Fe1-D2, 1.642(6); C10-C11-C12, 176.9(6); C11-
C12-C13, 178.4(8); D1-Fe1-D2, 178.2(3) (D1 ) centroid of
C5H5, D2 ) centroid of C5H4).
and 13b, is the highfield shift of the Me3SiCtC protons from
ca. 0.25 ppm (13) to -0.41 (14a) or -0.29 ppm (14b), which
can be explained by the ring current of the bipy ligand.
A striking feature of 6 and 8 is that they exist as two
enantiomers and, hence, show a doubling of the resonance
signals of the C5H4 CR carbons (6: 72.06 and 72.14 ppm; 8:
72.47, 72.53 ppm).
In the 13C{1H} NMR spectrum of 14b there is coupling to
silver on the alkynyl CR and Câ carbons (TiCRtCâSiMe3) found
at 153.7 ppm (CR) and 138.6 ppm (Câ), with coupling constants
being 15 and 4 Hz, respectively; that is, both alkyne carbon
atoms are bonded to silver (Experimental Section). However,
the expected splitting of the signals into two doublets, due to
the presence of the silver isotopes 107Ag and 109Ag (natural
abundance 107Ag (I ) 1/2) 51.8%, 109Ag (I ) 1/2) 48.2%), is not
observed.8 This also can nicely be seen from 29Si{1H} NMR
studies. The doublet found at -18.4 ppm with 2JSiAg ) 2.0 Hz
can be assigned to the alkynyl-bonded Me3Si groups.
(CO)4) (5) possesses four νCO absorptions at 1810, 1865, 1912,
and 2009 cm-1 4
. Remarkable to note is that due to the
unsymmetrical substituted bipyridine ligand in 10 two CtC
stretching vibrations are observed at 2039 and 2055 cm-1 for
the PtCtCSi units. In 12, these absorptions are shifted to 1961
and 1977 cm-1, confirming the successful complexation of the
alkynyl ligands to a low-valent CuFBF3 moiety. For the FBF3
fragment two vibrations are found at 1053 and 1084 cm-1, which
is typical for the σ-binding of this group to a transition metal
atom.5 Upon complexation of the organometallic π-tweezer
building block [{[Ti](µ-σ,π-CtCSiMe3)2}M]+ (M ) Cu, Ag)
by the bipy ligand in 14a and 14b, the CtC absorption is
somewhat shifted to higher wavenumber when compared with
13a and 13b, respectively.6
Also the NMR spectroscopic properties of 3, 5-8, 10, 12,
and 14 correlate with their formulations as mono-, di-, or
trimetallic complexes (vide supra). The cyclopentadienyl protons
in 3 show an AA′XX′ pattern with centers lying at 4.27 and
4.51 ppm (C5H4) and a singlet at 4.26 ppm (C5H5). The bipy
ligand gives rise to seven signals found between 7.2 and 8.8
ppm with the characteristic coupling pattern.7 The assignment
of these signals was supported by two-dimensional NMR
experiments (Experimental Section). The 13C{1H} NMR spec-
trum of 3 contains the respective carbon signals for Fc (four
signals), CtC (two resonances), and bipy (10 signals) (Experi-
mental Section). The protons and carbon atoms of the FcCtC
entity do not differ significantly in their chemical shifts upon
complexation of the bipy unit in 3 to MLn as given in 5-8, 10,
12, and 14. However, the hydrogen atoms H6 and H6′ located
next to the bipy nitrogen atoms are thereby more influenced
and are shifted by ca. 0.5 ppm to lower field, i.e., 5, 6, 10, and
12 (Experimental Section). In addition, representative Pt-H
couplings with JPtH ) 26 Hz are observed for H6 and H6′ in
ESI-TOF mass spectra for 7 and 10 contain the molecular
ion [M+] (7: m/z ) 630; 10: m/z ) 753) and for 12 [M+ -BF4]
(m/z ) 817). Further characteristic fragments are [M+ - PtCl2]
(7, m/z ) 365), [M2+] (10, m/z ) 1507), and [M+ -BF4 +
FcC2bipyPt(C2SiMe3)2] (12, m/z ) 1570).
Single-crystal X-ray structure analysis was performed for 3,
10, and 14a. A view of the molecules is given in Figure 1 (3),
Figure 2 (10), and Figure 3 (14a), respectively. Selected bond
distances (Å) and angles (deg) are given in the legend of Figures
1-3. The crystal and structure refinement data for 3, 10, and
14a are presented in Table 3 (Experimental Section).
The overall structural features of 3 are similar to those of
related structurally characterized phenylethynyl-functionalized
ferrocenes.3,9 The cyclopentadienyl rings are rotated by 6.2° to
each other, which verifies an almost eclipsed conformation. The
C13-C17, N1 and C18-C22, N2 pyridine rings and the
cyclopentadienyl unit C6-C10 are almost coplanar (dihedral
angle of 5.92(0.20)° for C13-C17, N1/C6-C10 and 0.95(0.20)°
for C13-C17, N1/C18-C22, N2) (Figure 1). This orientation
allows an optimal overlap between the π-orbitals of the
cyclopentadienyl, ethynyl, and pyridyl fragments.
1
10. Complexes 10 and 12 show in their H NMR spectra two
signals for the Me3Si protons, which is attributed to their
unsymmetrical chemical environment (vide supra). Notable in
the 1H NMR spectra of 14a and 14b, when compared with 13a
The asymmetric unit of 10 contains two crystallographically
independent molecules together with one molecule of acetoni-
trile. Geometrical parameters within the FcCtC-bipy unit are
(4) Hermann, W. A.; Thiel, W. R.; Kuchler, J. K. Chem. Ber. 1990, 1953.
(5) Beck, W.; Su¨nkel, K. Chem. ReV. 1988, 88, 1405.
(6) (a) Lang, H.; George, D. S. A.; Rheinwald, G. Coord. Chem. ReV.
2000, 206-207, 101. (b) Lang, H.; Rheinwald, G. J. Prakt. Chem. 1999,
341, 1. (c) Lang, H.; Ko¨hler, K.; Blau, S. Coord. Chem. ReV., 1995, 143,
113.
(7) (a) Grosshenny, V. G.; Romero, F. M.; Ziessel, R. J. Org. Chem.
1997, 62, 1491. (b) Schwab, P. F. H.; Fleischer, F.; Michl, J. J. Org. Chem.
2002, 67, 443.
(8) Yuan, Z.; Dryden, N. H.; Vittal, J. J.; Puddephatt, R. J. Chem. Mater.
1995, 7, 1696.
(9) (a) Ko¨cher, S.; Lang, H. J. Organomet. Chem. 2001, 637-639, 198.
(b) Fink, H.; Long, N. J.; Martin, A. J.; Opromolla, G.; White, A. J. P.;
Williams, D. J.; Zanello, P. Organometallics 1997, 16, 2646. (c) Ingham,
S. L.; Khan, M. S.; Lewis, J.; Long, N. J.; Raithby, P. R. J. Organomet.
Chem. 1994, 470, 153.

4582 Organometallics, Vol. 25, No. 19, 2006
Packheiser et al.
environment (mean deviation of Pt1 from the best plane of N1,
N2, C23, C28 is 0.0089 Å).
Heterotrimetallic 14a shows a pseudotetrahedral coordination
geometry around Cu1 with two η2-coordinated Me3SiCtC
groups (C23-C24, C28-C29) and the chelate-bonded bipy
ligand (N1, N2) (Figure 3). Noteworthy to mention is the
difference between Cu1-N1 (2.225(4) Å) and Cu1-N2 (2.044(4)
Å), which verifies an asymmetrical chelate binding of the
bipyridine ligand to Cu1 (Figure 3). This is, however, not
common for Cu(I)-bipy moieties, in which symmetrical copper-
nitrogen bonds are typical.11 The large dissimilarity between
Cu1-N1 and Cu1-N2 in 14a most probably can be ascribed
to electronic effects resulting from the electron-rich FcCtC unit.
All other structural features of the Ti-Cu organometallic
π-tweezer part are in accordance with this type of early-late
Figure 2. ORTEP plot (50% probability level) of one molecule
of 10 with the atom-numbering scheme (the hydrogen atoms and
one acetonitrile solvent molecule are omitted for clarity). Selected
bond distances (Å) and angles (deg): Pt1-C23, 1.931(8); Pt1-
C28, 1.930(9); Pt1-N1, 2.044(7); Pt1-N2, 2.042(7); C23-C24,
1.214(13); C28-C29, 1.213(13); C24-Si1, 1.807(9); C29-Si2,
1.809(9); C11-C12, 1.190(14); Fe1-D1, 1.634(11); Fe1-D2,
1.630(10); N1-Pt1-N2, 78.5(3); N1-Pt1-C23, 95.9(3); N1-
Pt1-C28, 173.2(3); N2-Pt1-C28, 94.8(3); N2-Pt1-C23, 174.3(3);
C23-Pt1-C28, 90.9(4); Pt1-C23-C24, 174.6(8); C23-C24-Si1,
173.1(8); Pt1-C28-C29, 171.5(8); C28-C29-Si2, 172.9(9); C6-
C11-C12, 177.6(11); C11-C12-C14, 177.0(11); D1-Fe1-D2,
177.8(6) (D1 ) centroid of C5H5, D2 ) centroid of C5H4).
6
complexes. In comparison to mononuclear 3 (Figure 1) the
bipy ligand in 14a is tilted by 96.9° toward the η5-coordinated
C5H4 ring (C6-C10). This orientation is most likely attributed
to cell-packing effects.
Preliminary electrochemical investigations of 3, 10, 12, 14a,
and 14b by cyclic voltammetry demonstrate that the redox
couple Fe2+/Fe3+ of the ferrocene moieties is not significantly
affected by the complexation of bipy by MLn fragments
(Experimental Section, Table 2). Exemplarily, the cyclic vol-
tammograms of 3, 10, 12, and 14a are depicted in Figures 4-6.
Complex 3 shows two reductions that can be assigned to the
bipy ligand at E0,1 ) -2.36 V (∆Ep ) 200 mV) and E0,2
)
-2.76 V (∆Ep ) 430 mV) (Figure 4) (for comparison, free
2,2′-bipyridine: E0 ) -2.77 V (∆Ep ) 340 mV);14 E0 ) Eox
- (Eox - Ered)/2; ∆Ep ) peak diff). In addition, a ferrocene-
based Fe2+/Fe3+ redox couple is found at E0 ) 0.10 V (∆Ep )
194 mV), which is somewhat shifted to a more positive value
when compared with the FcH/FcH+ potential (FcH ) (η5-
C5H5)2Fe, E0 ) 0.00 V (∆Ep ) 150 mV)).12 This displacement
can be interpreted by means of a stronger electron-withdrawing
group present in 3 than in FcH, taken as standard. The oxidation
at Eox ) -0.04 V (Figure 4, inset) results from the second
reduction of the bipy ligand at E0 ) -2.76 V, as could be
evidenced by measuring only to -2.6 V (Figure 4).
For heterobimetallic 10 two redox waves are observed for
the bipy ligand at E0,1 ) -1.59 V (∆Ep ) 120 mV) and E0,2
)
Figure 3. ORTEP plot (30% probability level) of 14a with the
atom-numbering scheme (the hydrogen atoms, the PF6- counterion,
and the distortion of one Me3Si group are omitted for clarity).
Selected bond distances (Å) and angles (deg): Cu1-N1, 2.225(4);
Cu1-N2, 2.044(4); Cu1-C23, 2.085(4); Cu1-C24, 2.198(5);
Cu1-C28, 2.089(4); Cu1-C29, 2.202(5); Ti1-C23, 2.105(5); Ti1-
C28, 2.118(5); C23-C24, 1.230(6); C28-C29, 1.227(6); C24-
Si1, 1.853(5); C29-Si2, 1.853(5); Ti1-D3, 2.051(5); Ti1-D4,
2.040(5); C11-C12, 1.195(7); Fe1-D1, 1.640(8); Fe1-D2, 1.628(6);
Ti1-Cu1, 2.9908(9); C23-Ti1-C28, 88.48(17); Ti1-C23-C24,
169.5(4); Ti1-C28-C29, 167.6(4); C23-C24-Si1, 162.6(4);
C28-C29-Si2, 161.7(4); N1-Cu1-N2, 76.45(15); C6-C11-
C12, 178.2(6); C11-C12-C14, 177.2(6); D1-Fe1-D2, 178.6(5)
(D1 ) centroid of C5H5; D2 ) centroid of C5H4; D3, D4 )
centroids of C5H4SiMe3).
-2.24 V (∆Ep ) 130 mV) in the cyclic voltammogram (Figure
5, top), which is typical for chelate-bonded bipy ligands in
platinum transition metal chemistry.15 The cyclic voltammogram
of 10 also exhibits, as 3, a reversible oxidation wave for the
(11) (a) Reger, D. L.; Collins, J. E.; Huff, M. F.; Rheingold, A. L.; Yap,
G. P. A. Organometallics 1995, 14, 5475. (b) Munakata, M.; Kitagawa, S.;
Shimono, H.; Masuda, H. Inorg. Chem. 1991, 30, 2610. (c) Masuda, H.;
Yamamoto, N.; Taga, T.; Machida, K.; Kitagawa, S.; Munakata, M. J.
Organomet. Chem. 1987, 322, 121. (d) Engelhardt, L. M.; Pakawatchai,
C.; White, A. H.; Healy, P. C. J. Chem. Soc., Dalton Trans. 1985, 125. (e)
Martens, C. F.; Schenning, A. P. H. J.; Feiters, M. C.; Heck, J.; Beurskens,
G.; Beurskens, P. T.; Steinwender, E.; Nolte, R. J. M. Inorg. Chem. 1993,
32, 3029. (f) Martens, C. F.; Schenning, A. P. H. J.; Feiters, M. C.;
Beurskens, G.; Smits, J. M. M.; Beurskens, P. T.; Smeets, W. J. J.; Spek,
A. L.; Nolte, R. J. M. Supramol. Chem. 1996, 8, 31.
(12) Ferrocene/ferrocenium redox couple: Gritzner, G.; Kuta, J. Pure
Appl. Chem. 1984, 56, 461.
(13) A conversion of given electrode potentials to the standard normal
hydrogen electrode is possible: Strehlow, H.; Knoche, W.; Schneider, H.
Ber. Bunsen-Ges. Phys. Chem. 1973, 77, 760.
(14) (a) Al-Anber, M.; Vatsadze, S.; Holze, R.; Thiel, W. R.; Lang, H.
J. Chem. Soc., Dalton Trans. 2005, 3632. (b) Vatsadze, S.; Al-Anber, M.;
Thiel, W. R.; Lang, H.; Holze, R. J. Solid State Electrochem. 2005, 9, 764.
(15) (a) Vogler, C.; Schwederski, B.; Klein, A.; Kaim, W. J. Organomet.
Chem. 1992, 436, 367. (b) Bratermann, P. S.; Song, J. I.; Wimmer, F. M.;
Wimmer, S.; Kaim, W. Inorg. Chem. 1992, 31, 5084. (c) Osella, D.; Milone,
L.; Nervi, C.; Ravera, M. J. Organomet. Chem. 1995, 488, 1. (d) Wetzold,
N. Diploma Thesis, TU Chemnitz, 2003.
comparable to those of 3 (Figures 1 and 2). The (bipy)Pt(CtC-
SiMe3)2 entity has values for metrical parameters similar to those
reported previously in comparable complexes.10 The platinum
atom Pt1 is held in a somewhat distorted square-planar
(10) (a) Lang, H.; del Villar, A.; Rheinwald, G. J. Organomet. Chem.
1999, 587, 284. (b) Chan, S. C.; Chan, M. C. W.; Wang, Y.; Che, C. M.;
Cheung, K. K.; Zhu, N. Chem. Eur. J. 2001, 7, 4180. (c) Adams, C. J.;
James, S. L.; Liu, X.; Raithby, P. R.; Yellowlees, L. J. J. Chem. Soc., Dalton
Trans. 2000, 63.

Heterobi- and Heterotrimetallic Transition Metal Complexes
Organometallics, Vol. 25, No. 19, 2006 4583
Table 2. Electrochemical Data of 3, 10, 12, 14a, and 14ba
Fe2+/Fe3+ E0/V
(∆Ep mV)
bipy/bipy•-b E0 (Ep,red)/V
(∆Ep/mV)
bipy•-/bipy2-b E0/V
(∆Ep/mV)
E0/V
(∆Ep/mV)
compd
M+/Mc Ep,ox/V
Ep,red/V
3
10
12
14a
14b
0.10 (194)
0.17 (130)
0.16 (120)
0.12 (150)
0.13 (145)
-2.36 (200)
-1.59 (120)
-1.60 (130)
-2.67
-2.76 (430)
-2.24 (130)
-2.23 (120)
-1.82
-1.45
-1.26
-1.33
-1.39 (120)
-2.66
a In tetrahydrofuran. b For electrode potentials of free bipy see ref 14. c M ) Cu and Ag, respectively.
Table 3. Crystal and Intensity Collection Data for 3, 10 and 14a
3
10
14a
fw
364.22
794.79
1089.60
chemical formula
cryst syst
space group
a (Å)
b (Å)
c (Å)
C22H16FeN2
orthorhombic
Pna21
23.915(2)
6.8674(6)
10.0743(9)
90
90
90
1654.6(3)
1.462
752
C34H37FeN3PtSi2
triclinic
P1h
C48H60CuFeN2PSi4Ti
monoclinic
P21/c
18.6503(10)
16.8592(9)
19.1245(10)
90
116.716(1)
90
5371.4(5)
1.347
7.0881(6)
15.1536(13)
17.1405(15)
65.152(2)
88.468(2)
84.486(2)
1662.7(2)
1.587
R (deg)
â (deg)
γ (deg)
V (Å3)
F
calc (g cm-3
F(000)
)
788
2256
cryst dimens (mm3)
Z
0.35 × 0.25 × 0.05
0.4 × 0.4 × 0.2
0. 5 × 0.4 × 0.2
4
2
4
max., min. transmn
absorp coeff (µ, mm-1
scan range (deg)
index ranges
0.9999, 0.2233
0.917
0.9999, 0.5609
4.737
0.9999, 0.7818
0.977
)
1.70 to 26.41
0 e h e 29
0 e k e 8
-12 e l e 12
14 578
1.51 to 26.39
-8 e h e 8
-16 e k e 18
0 e l e 21
25 409
1.22 to 26.46
-23 e h e 20
0 e k e 21
0 e l e 23
57 721
total no. of reflns
no. of unique reflns
R(int)
3392
0.0649
6767
0.0482
11 427
0.0931
no. of data/restraints/params
goodness-of-fit on F2
R1,a wR2a [I g 2σ(I)]
R1,a wR2a (all data)
3392/1/226
1.031
0.0396, 0.0820
0.0677, 0.0918
0.262, -0.274
6767/0/377
1.118
0.0611, 0.1598
0.0643, 0.1628
7.803, -3.869
11 025/405/693
1.011
0.0641, 0.1424
0.1308, 0.1715
0.784, -0.426
max., min. peak in final
Fourier map (e Å-3
)
2
4
2
a R1 ) [∑(|Fo| - |Fc|)/∑|Fo|); wR2 ) [∑(w(Fo2 - Fc )2)/∑(wFo )]1/2. S ) [∑w(Fo2 - Fc )2]/(n - p)1/2. n ) number of reflections, p ) parameters used.
Figure 4. Cyclic voltammogram of 3 in tetrahydrofuran at 25 °C, [nBu4N]PF6 supporting electrolyte (0.1 M), scan rate ) 100 mV s-1. All
potentials are referenced to the FcH/FcH+ redox couple (FcH ) (η5-C5H5)2Fe) with E0 ) 0.00 V (∆Ep ) 150 mV).12,13
ferrocene moiety at E0 ) 0.17 V (∆Ep ) 130 mV), showing
that this unit is more difficult to oxidize than 3 and FcH, taken
as standard (vide supra).12 Under the conditions of the measure-
ment, however, platinum reductions could not be observed.15
Complexation of [CuFBF3] as given in 12 does not influence
the oxidation or reduction potentials of the FcCtC-bipy[Pt-
(CtCSiMe3)2] moiety (Fe2+/Fe3+: E0 ) 0.16 V (∆Ep ) 120
mV); bipy: E0,1 ) -1.60 V (∆Ep ) 130 mV), E0,2 ) -2.23 V
(∆Ep ) 120 mV)). The coordinated copper(I) ion gives rise to
an irreversible reduction wave at Ep,red ) -1.82 V (Figure 5,

4584 Organometallics, Vol. 25, No. 19, 2006
Packheiser et al.
Ep,red ) -1.45 V, and the reduction process bipy/bipy- at Ep,red
) -2.67 V (Figure 6). The reduction of copper(I) to copper(0)
is typical in Ti-Cu organometallic π-tweezer chemistry, imply-
ing that in such complexes the reduction occurs initially at the
Cu(I) ion, resulting in fragmentation of the respective complexes
(vide supra).16 However, when the cyclic voltammogram of 14a
is measured only between -0.4 and -1.6 V (Figure 6, inset),
the cathodic reduction of Cu(I) is followed by reoxidation of
Cu(0) (E0 ) -1.39 V, ∆Ep ) 120 mV) obviously without any
change of the chemical identity of the molecule involved. In
contrast, this is not the case for isostructural 14b, where instead
of copper(I) a silver(I) center is present. Next to the redox
couples Fe2+/Fe3+ (E0 ) 0.13 V, ∆Ep ) 145 mV) and bipy/
bipy- (Ep,red ) -2.66 V) an irreversible reduction peak for Ag-
(I)/Ag(0) is found at Ep,red ) -1.26 V; that is, no reoxidation
peak is observed. In the second run the only observable
potentials are those typical for free FcCtC-bipy and [Ti](CtC-
SiMe3)2,16 indicating that 14b fragmented into the starting
materials (vide supra).
Conclusion
A straightforward synthesis method for the preparation of
heterobi- and heterotrimetallic transition metal complexes of
structural type FcCtC-bipy(MLn) (MLn ) Mo(CO)4, Mn-
(CO)3Br, PtCl2, Pt(CtCSiMe3)2, [Ru(bipy)2](PF6)2), FcCtC-
bipy{[Pt(µ-σ,π-CtCSiMe3)2]CuFBF3}, and [FcCtC-bipy{[Ti]-
(µ-σ,π-CtCSiMe3)2}M]X (M ) Cu, X ) PF6; M ) Ag, X )
ClO4; [Ti] ) (η5-C5H4SiMe3)2Ti) is reported. In the latter species
different early-late transition metals are connected via π-con-
jugated carbon-rich bridging units. Electrochemical studies show
that the ferrocenyl moiety in FcCtC-bipy is not significantly
affected by the complexation of the bipy unit by MLn fragments.
Complexation of the organometallic π-tweezers [Pt(µ-σ,π-CtC-
SiMe3)2]CuFBF3 and {[Ti](µ-σ,π-CtCSiMe3)2}M+ (M ) Cu,
Ag) by the bipy ligand induces a cationic shift of the respective
redox peaks for Fe2+/Fe3+, indicating that in the heterotrimetallic
complexes the ferrocene unit is more difficult to oxidize and,
hence, the heterobimetallic Pt-Cu and Ti-M building blocks
are acting as electron-withdrawing groups. The use of the newly
synthesized heterometallic complexes as multicomponent cata-
lysts is subjected to further studies, since it was found that in
heterobimetallic titanium-M π-tweezer complexes the ap-
propriate metals show synergetic and cooperative effects.
Figure 5. Cyclic voltammograms of 10 (top) and 12 (bottom) in
tetrahydrofuran at 25 °C, [nBu4N]PF6 supporting electrolyte (0.1
M), scan rate ) 100 mV s-1. All potentials are referenced to the
FcH/FcH+ redox couple (FcH ) (η5-C5H5)2Fe) with E0 ) 0.00 V
(∆Ep ) 150 mV).12,13
bottom). This observation may imply that the copper(I) reduction
occurs initially, resulting in fragmentation of FcCtC-bipy{[Pt-
(µ-σ,π-CtCSiMe3)2]CuFBF3} (12). A similar phenomenon was
found for other organometallic π-tweezers, i.e., {[Ti](µ-σ,π-
CtCR)2}CuX (X ) singly bonded inorganic or organic
group).16 A comparison of 7, 10, and 12 is not possible, because
7 is not soluble in tetrahydrofuran and dichloromethane solu-
tions, respectively.
Heterotrimetallic[FcCtC-bipy{[Ti](µ-σ,π-CtCSiMe3)2}Cu]-
PF6 (14a) gives a cyclic voltammogram as shown in Figure 6.
The relevant electrode potentials are for the iron(II) ion, E0
) 0.12 V (∆Ep ) 150 mV), the reduction of the copper ion at
Figure 6. Cyclic voltammogram of 14a in tetrahydrofuran at 25 °C, [nBu4N]PF6 supporting electrolyte (0.1 M), scan rate ) 100 mV s-1
All potentials are referenced to the FcH/FcH+ redox couple (FcH ) (η5-C5H5)2Fe) with E0 ) 0.00 V (∆Ep ) 150 mV).12,13
.

Heterobi- and Heterotrimetallic Transition Metal Complexes
Organometallics, Vol. 25, No. 19, 2006 4585
68% based on 2). Mp: 163 °C. IR (KBr, cm-1): 2205 (m), ν(Ct
C). H NMR (CDCl3): δ 4.26 (s, 5 H, C5H5), 4.27 (pt, JHH ) 1.9
Hz, 2 H, Hâ/C5H4), 4.51 (pt, JHH ) 1.9 Hz, 2 H, HR/C5H4), 7.29
4. Experimental Section
1
General Data. All reactions were carried out under an atmo-
sphere of nitrogen using standard Schlenk techniques. Tetrahydro-
furan, diethyl ether, and n-hexane were purified by distillation from
sodium/benzophenone ketyl; dichloromethane was purified by
distillation from calcium hydride. Celite (purified and annealed,
Erg. B.6, Riedel de Haen) was used for filtrations.
3
3
4
(ddd, JH5′H4′ ) 7.8 Hz, JH5′H6′ ) 4.8 Hz, JH5′H3′ ) 1 Hz, 1 H,
3
3
4
H5′), 7.80 (ddd, JH4′H3′ ) JH4′H5′ ) 7.8 Hz, JH4′H6′ ) 1.8 Hz, 1
3
4
H, H4′), 7.91 (dd, JH4H3 ) 8.5 Hz, JH4H6 ) 2.4 Hz, 1 H, H4),
3
5
8.38 (dd, JH3H4 ) 8.5 Hz, JH3H6 ) 0.6 Hz, 1 H, H3), 8.41 (ddd,
3JH3′H4′ ) 7.8 Hz, 4JH3′H5′ ) 1 Hz, 5JH3′H6′ ) 1 Hz, 1 H, H3′), 8.67
Instruments. Infrared spectra were recorded with a Perkin-Elmer
Spectrum 1000 FT-IR spectrometer. 1H NMR spectra were recorded
with a Bruker Avance 250 spectrometer operating at 250.130 MHz
in the Fourier transform mode; 13C{1H} NMR spectra were recorded
at 62.860 MHz. Chemical shifts are reported in δ units (parts per
million) downfield from tetramethylsilane with the solvent as
reference signal (1H NMR: CDCl3 (99.8%), δ ) 7.26; (CD3)2CO
(99.9%), δ ) 2.05; CD3CN (99.8%), δ ) 1.94. 13C{1H} NMR:
CDCl3 (99.8%), δ ) 77.16; (CD3)2CO (99.9%), δ ) 29.84, 206.26).
The abbreviation pt in the 1H NMR spectra corresponds to a
pseudotriplet. Cyclic voltammograms were recorded in a dried cell
purged with purified argon. A platinum wire served as working
electrode, and a platinum wire was used as counter electrode. A
saturated calomel electrode in a separate compartment served as
reference electrode. For ease of comparison, all electrode potentials
are converted using the redox potential of the ferrocene-ferroce-
nium couple FcH/FcH+ (FcH ) (η5-C5H5)2Fe, E0 ) 0.00 V)12,13
as reference. Electrolyte solutions were prepared from tetrahydro-
furan and [nBu4N]PF6 (Fluka, dried in oil-pump vacuum). The
respective organometallic complexes were added at c ) 1.0 mM.
Cyclic voltammograms were recorded in negative-going direction
at the starting potentials using a Voltalab 3.1 potentiostat (Radi-
ometer) equipped with a DEA 101 digital electrochemical analyzer
and an IMT 102 electrochemical interface. Melting points were
determined using analytically pure samples, sealed off in nitrogen-
purged capillaries on a Gallenkamp MFB 595 010 M melting point
apparatus. Microanalyses were performed by the Institute of Organic
Chemistry, Chemnitz, University of Technology, and partly by the
Institute of Organic Chemistry, University of Heidelberg.
Reagents. Ethynylferrocene,17 5-bromo-2,2′-bipyridine,18 (nbd)-
Mo(CO)4,19 Mn(CO)5Br,20 (bipy)2RuCl2‚2H2O,21 [{[Ti](µ-σ,π-CtC-
SiMe3)2}Cu(NtCMe)]PF6,22 {[Ti](µ-σ,π-CtCSiMe3)2}AgOClO3,23
(Et2S)2PtCl2,24 and Me3SiCtCH25 were prepared according to
published procedures. All other chemicals were purchased by
commercial suppliers and were used without further purification.
Synthesis of Fc-CtC-bipy (3). 5-Bromo-2,2′-bipyridine (2) (200
mg, 0.85 mmol) and ethynylferrocene (1) (220 mg, 1.05 mmol)
were dissolved in 30 mL of degassed diisopropylamine. To this
solution were added [Pd(PPh3)2Cl2] (50 mg) and [CuI] (25 mg).
The resulting suspension was heated at reflux for 8 h. After cooling
to 25 °C it was filtered through a pad of Celite. The filtrate was
evaporated to dryness, and the residue was subjected to column
chromatography (silica gel). A 10:1 petroleum ether/diethyl ether
mixture was used as eluent. Complex 3 was isolated from the second
fraction on removal of all volatiles in an oil pump vacuum.
Crystallization from a 5:1 petroleum ether/diethyl ether mixture at
25 °C gave orange, single crystals of 3. Yield: 210 mg (0.58 mmol,
3
4
5
(ddd, JH6′H5′ ) 4.8 Hz, JH6′H4′ ) 1.8 Hz, JH6′H3′ ) 1 Hz, 1 H,
H6′), 8.77 (dd, JH6H4 ) 2.4 Hz, JH6H3 ) 0.6 Hz, 1 H, H6). 13C-
{1H} NMR (CDCl3): δ 64.5 (Ci/C5H4), 69.3 (Câ/C5H4), 70.2 (C5H5),
71.7 (CR/C5H4), 83.0 (Fc-CtC-bipy), 93.3 (Fc-CtC-bipy), 120.4
(C3/bipy), 121.1 (C5/bipy), 121.3 (C3′/bipy), 123.8 (C5′/bipy),
137.0 (C4′/bipy), 139.1 (C4/bipy), 149.3 (C6′/bipy), 151.5 (C6/
bipy), 154.2 (C2/bipy), 155.7 (C2′/bipy). Anal. Calc for C22H16-
FeN2 (364.23): C, 72.55; H, 4.43; N, 7.69. Found: C, 72.23; H,
4.46; N, 7.50.
4
5
Synthesis of Fc-CtC-bipy[Mo(CO)4] (5). (nbd)Mo(CO)4 (4a)
(80 mg, 0.27 mmol) was dissolved in a mixture of 25 mL of
dichloromethane and 5 mL of THF. To this solution was added 3
(90 mg, 0.25 mmol) in one portion. After a few minutes the color
of the reaction mixture turned from yellow to deep red. Stirring
was continued for 15 h at 25 °C. Afterward the solvent was reduced
in volume to 5 mL and the product was precipitated with diethyl
ether. The precipitate was washed twice with 10 mL portions of
diethyl ether and dried in an oil pump vacuum. Complex 5 was
obtained as a red solid. Yield: 110 mg (0.19 mmol, 77% based on
3). Mp: 183 °C (dec). IR (KBr, cm-1): 2208 (m), ν(CtC); 2009
(s), 1912 (s), 1865 (s), 1810 (s) ν(CO). 1H NMR (CDCl3): δ 4.31
(s, 5 H, C5H5), 4.36 (pt, JHH ) 1.9 Hz, 2 H, Hâ/C5H4), 4.60 (pt,
3
3
JHH ) 1.9 Hz, 2 H, HR/C5H4), 7.38 (dd, JH5′H4′ ) 7.8 Hz, JH5′H6′
) 5.2 Hz, 1 H, H5′), 7.89-7.96 (m, 2 H, H4, H4′), 8.03 (d, 3JH3H4
3
) 8.4 Hz, 1 H, H3), 8.08 (d, JH3′H4′ ) 8 Hz, 1 H, H3′), 9.13 (d,
3JH6′H5′ ) 5.2 Hz, 1 H, H6′), 9.19 (d, JH6H4 ) 2 Hz, 1 H, H6).
4
13C{1H} NMR (CDCl3): δ 63.2 (Ci/C5H4), 69.9 (Câ/C5H4), 70.4
(C5H5), 72.1 (CR/C5H4), 81.4 (Fc-CtC-bipy), 97.7 (Fc-CtC-bipy),
121.4 (bipy), 122.1 (bipy), 123.4 (bipy), 125.1 (bipy), 137.4 (bipy),
138.7 (bipy), 152.1 (bipy), 153.2 (bipy), 154.4 (bipy), 154.5 (bipy),
204.8 (CO), 223.0 (CO). Anal. Calc for C26H16O4FeN2Mo
(572.2): C, 54.58; H, 2.82; N, 4.90. Found: C, 54.46; H, 3.11; N,
4.66.
Synthesis of Fc-CtC-bipy[Mn(CO)3Br] (6). Mn(CO)5Br (4b)
(70 mg, 0.255 mmol) and 3 (85 mg, 0.233 mmol) were dissolved
in 20 mL of ethanol, and the solution was heated at reflux for 30
min, whereby the color changed from orange to dark red. After
cooling the reaction mixture to 25 °C the solvent was reduced in
volume to 5 mL, and 15 mL of diethyl ether was added. On cooling
the resulting solution to -30 °C, complex 6 precipitated. The
obtained solid material was washed twice with 10 mL portions of
diethyl ether and dried in an oil pump vacuum. Complex 6 was
obtained as a red-brown solid. Yield: 80 mg (0.137 mmol, 59%
based on 3). Mp: 175 °C (dec). IR (KBr, cm-1): 2208 (w), ν(Ct
C); 1914 (s), 1932 (s), 2024 (s), ν(CO). 1H NMR (CDCl3): δ 4.31
(s, 5 H, C5H5), 4.37 (pt, JHH ) 1.9 Hz, 2 H, Hâ/C5H4), 4.60 (pt,
JHH ) 1.9 Hz, 2 H, HR/C5H4), 7.48 (dd,3JH5′H4′ ) 7.8 Hz, 3JH5′H6′
)
(16) Stein, T.; Lang, H.; Holze, R. J. Electroanal. Chem. 2002, 520,
163, and references therein.
(17) Polin, J.; Schottenberger, H. Org. Synth. 1996, 13, 262.
(18) Schwab, P. F. H.; Fleischer, F.; Michl, J. J. Org. Chem. 2002, 67,
443.
(19) Werner, H.; Prinz, R. Chem. Ber. 1967, 100(1), 265.
(20) Reimer, K. J.; Shaver, A. Inorg. Synth. 1990, 28, 154.
(21) Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg. Chem. 1978, 17,
3335.
(22) Janssen, M. D.; Herres, M.; Zsolnai, L.; Spek, A. L.; Grove, D.
M.; Lang, H.; van Koten, G. Inorg. Chem. 1996, 35, 2476.
(23) Lang, H.; Herres, M.; Zsolnai, L. Organometallics 1993, 12, 5008.
(24) Fekl, U.; Zahl, A.; van Eldik, R. Organometallics 1999, 18, 4156.
(25) Brandsma, L. PreparatiVe Acetylenic Chemistry; Elsevier-Verlag:
Amsterdam 1988; p 114.
5.4 Hz, 1 H, H5′), 7.86-8.06 (m, 4 H, H3, H3′, H4, H4′), 9.23 (d,
4
3JH6′H5′ ) 5.4 Hz, 1 H, H6′), 9.26 (d, JH6H4 ) 1.2 Hz, 1 H, H6).
13C{1H} NMR (CDCl3): δ 63.0 (Ci/C5H4), 70.0 (Câ/C5H4), 70.4
(C5H5), 72.1 (CR/C5H4), 72.1 (CR/C5H4), 81.3 (Fc-CtC-bipy), 98.2
(Fc-CtC-bipy), 121.8 (bipy), 122.4 (bipy), 124.2 (bipy), 126.1
(bipy), 138.3 (bipy), 139.7 (bipy), 152.9 (bipy), 153.8 (bipy), 155.3
(bipy), 155.3 (bipy). Anal. Calc for C25H16BrFeMnN2O3 (583.1):
C, 51.50; H, 2.77; N, 4.80. Found: C, 51.37; H, 3.29; N, 4.49.
Synthesis of Fc-CtC-bipy(PtCl2) (7). A toluene solution (30
mL) containing 3 (100 mg, 0.275 mmol) and (Me2S)2PtCl2 (4c)
(100 mg, 0.256 mmol) was heated to reflux for 18 h. The reaction
solution was decanted, and the precipitated dark purple solid was

4586 Organometallics, Vol. 25, No. 19, 2006
Packheiser et al.
4
5
washed twice with 20 mL portions of diethyl ether and dried in an
oil pump vacuum. Yield: 70 mg (0.111 mmol, 43% based on 4c).
Mp: 210 °C (dec). IR (KBr, cm-1): 2199 (m), ν(CtC). ESI-MS
[m/z (rel int)]: [M+] 630.0 (55), [M+ - PtCl2] 365 (100). Anal.
Calc for C22H16Cl2FeN2Pt (630.2): C, 41.93; H, 2.56; N, 4.44.
Found: C, 42.29; H, 2.57; N, 4.30. (Due to insolubility in common
3JH6′H5′ ) 5.2 Hz, 1 H, H6′), 9.01 (dd, JH6H4 ) 2 Hz, JH6H3 ) 1
Hz, H6). ESI-MS [m/z (rel int)]: [M+ - BF4] 817 (85), [M+
BF4+Fc-CtC-bipy[Pt(CtCSiMe3)2] 1570 (100). Anal. Calc for
C32H34BCuF4FeN2PtSi2 (904.08): C, 42.51; H, 3.79; N, 3.10.
Found: C, 42.31; H, 3.88; N, 4.16.
-
Synthesis of [Fc-CtC-bipy{[Ti](µ-σ,π-CtCSiMe3)2}Cu]PF6
(14a). [{[Ti](µ-σ,π-CtCSiMe3)2}Cu(NtCCH3)]PF6 (13a) (145
mg, 0.19 mmol) was dissolved in 30 mL of THF, and complex 3
(70 mg, 0.19 mmol) was added in one portion. After 3 h of stirring
at 25 °C the color of the reaction mixture was red. The solution
was filtered through a pad of Celite, and all volatiles were removed
in an oil pump vacuum. The remaining red solid was washed twice
with 15 mL portions of n-hexane and was dried in an oil pump
vacuum. Single crystals of the title compound, suitable for X-ray
structure analysis, could be obtained by slow diffusion of n-hexane
into a dichloromethane solution containing 14a at 0 °C. Yield: 160
mg (0.147 mmol, 78% based on 13a). Mp: 215 °C (dec). IR (KBr,
cm-1): 2210 (w), ν(FcCtC); 1925 (w), ν(TiCtC); 839 (s), ν(PF).
1H NMR ((CD3)2CO): δ -0.41 (s, 18 H, SiMe3), 0.32 (s, 9 H,
SiMe3), 0.34 (s, 9 H, SiMe3), 4.28 (s, 5 H, C5H5 [Fc]), 4.41 (pt,
JHH ) 1.9 Hz, Hâ/C5H4 [Fc]), 4.61 (pt, JHH ) 1.9 Hz, HR/C5H4
1
NMR solvents, no H NMR spectrum of 7 could be recorded.)
Synthesis of [Fc-CtC-bipy{Ru(bipy)2}](PF6)2 (8). An ethan-
olic solution (20 mL) containing 3 (100 mg, 0.27 mmol) and Ru-
(bipy)2Cl2‚2H2O (4d) (142 mg, 0.27 mmol) was heated at reflux
for 12 h. The resulting red solution was cooled to 0 °C, and a
saturated aqueous solution of ammonium hexafluorophosphate (125
mg, 0.77 mmol) was added. The immediately formed red precipitate
was filtered, washed successively with water (10 mL), ethanol (10
mL), and diethyl ether (20 mL), and finally dried in an oil pump
vacuum to give 265 mg (0.248 mmol, 92% based on 4d) of the
title complex. Mp: 220 °C (dec). IR (KBr, cm-1): 2201 (w), ν(Ct
C); 840 (s), ν(P-F). 1H NMR ((CD3)2CO): δ 4.19 (s, 5 H, C5H5),
4.35 (pt, JHH ) 1.9 Hz, 2 H, Hâ/C5H4), 4.46 (pt, JHH ) 1.9 Hz, 2
H, HR/C5H4), 7.53-7.62 (m, 5 H, bipy), 7.96-7.99 (m, 2 H, bipy),
8.01-8.11 (m, 3 H, bipy), 8.15-8.25 (m, 7 H, bipy), 8.75-8.83
(m, 6 H, bipy). 13C{1H} NMR ((CD3)2CO): δ 63.5 (Ci/C5H4), 70.7
(Câ/C5H4), 70.9 (C5H5), 72.47 (CR/C5H4), 72.53 (CR′/C5H4), 81.4
(Fc-CtC-bipy), 98.1 (Fc-CtC-bipy), 124.9 (bipy), 125.3 (bipy),
125.4 (bipy), 125.5 (bipy), 125.6 (bipy), 128.7(bipy), 128.8 (bipy),
138.9 (bipy), 139.0 (bipy), 140.3 (bipy), 152.5 (bipy), 152.67 (bipy),
152.7 (bipy), 152.8 (bipy), 153.0 (bipy), 153.7 (bipy), 156.3 (bipy),
157.7 (bipy), 157.9 (bipy), 158.01 (bipy), 158.04 (bipy), 158.1
3
[Fc]), 6.54-6.60 (m, 8 H, C5H4), 7.88 (ddd, JH5′H4′ ) 7.6 Hz,
3JH5′H6′ ) 4.5 Hz, JH5′H3′ ) 1 Hz, 1 H, H5′), 8.33-8.40 (m, 2 H,
4
3
3
H4, H4′), 8.80 (d, JH3H4 ) 8.4 Hz, 1 H, H3), 8.82 (d, JH3′H4′
)
8.2 Hz, 1 H, H3′), 8.86 (dd, 4JH6H4 ) 2 Hz, 5JH6H3 ) 0.8 Hz, 1 H,
3
4
5
H6), 8.94 (ddd, JH6′H5′ ) 4.5 Hz, JH6′H4′ ) 1.7 Hz, JH6′H3′ ) 0.8
Hz, 1 H, H6′). 13C{1H} NMR ((CD3)2CO): δ -0.6 (SiMe3), 0.2
(SiMe3), 0.3 (SiMe3), 64.0 (Ci/C5H4 [Fc]), 70.7 (Câ/C5H4 [Fc]), 71.0
(C5H5 [Fc]), 72.7 (CR/C5H4 [Fc]), 81.8 (Fc-CtC-bipy), 97.5 (Fc-
CtC-bipy), 116.6 (CH/C5H4), 116.7 (CH/C5H4), 117.8 (CH/C5H4),
118.1 (CH/C5H4), 123.4 (bipy), 124.0 (bipy), 124.8 (Ci/C5H4), 125.0
(Ci/C5H4), 125.1 (bipy), 128.0 (bipy), 133.6 (CtCSi), 141.1 (bipy),
142.3 bipy), 149.9 (bipy), 151.2 (bipy), 151.5 (bipy), 152.0 (bipy),
167.0 (TiCtC). 31P{1H} NMR ((CD3)2CO): δ -145.2 (septet, 1JP-F
) 708 Hz, PF6). Anal. Calc for C48H60CuF6FeN2PSi4Ti (1089.6):
C, 52.91; H, 5.55; N, 2.57. Found: C, 52.62; H, 5.67; N, 2.78.
1
(bipy). 31P{1H} NMR (d6-acetone): δ -145.2 (septet, JPF ) 708
Hz, PF6). Anal. Calc for C42H32F12FeN6P2Ru (1067.6): C, 47.25;
H, 3.02; N, 7.87. Found: C, 46.45; H, 3.21; N, 8.00.
Synthesis of Fc-CtC-bipy[Pt(CtCSiMe3)2] (10). To 7 (50 mg,
0.079 mmol) suspended in 50 mL of dichloromethane and 10 mL
of diisopropylamine were added trimethylsilylacetylene (50 mg,
0.51 mmol) and [CuI] (1 mg, 0.005 mmol). The reaction mixture
was stirred for 15 h at 25 °C. After filtration through alumina the
solvent was reduced in volume to 3 mL and 10 was precipitated
by addition of n-hexane (20 mL), washed twice with n-hexane (10
mL), and dried in an oil pump vacuum. Complex 10 was obtained
as a pale red solid. Single crystals suitable for X-ray structure
determination were grown by distillation of petroleum ether into
an acetonitrile solution containing 10 at 25 °C. Yield: 50 mg (0.063
mmol, 84% based on 7). Mp: 195 °C (dec). IR (KBr, cm-1): 2204
(m), ν(FcCtC); 2055 (m), 2039 (m), ν(PtCtC). 1H NMR
(CDCl3): δ 0.24 (s, 9 H, SiMe3), 0.31 (s, 9 H, SiMe3), 4.25 (s, 5
Synthesis of [Fc-CtC-bipy{[Ti](µ-σ,π-CtCSiMe3)2}Ag]ClO4
(14b). {[Ti](µ-σ,π-CtCSiMe3)2}AgOClO3 (13b) (140 mg, 0.196
mmol) was dissolved in 30 mL of THF, and 3 (72 mg, 0.196 mmol)
was added in one portion. After 2 h of stirring at 25 °C the color
of the reaction mixture was red. The solution was filtered through
a pad of Celite, and all volatiles were removed in an oil pump
vacuum. The remaining red solid was washed twice with 15 mL
portions of n-hexane and afterward was dried in an oil pump
vacuum. Yield: 155 mg (0.143 mmol, 73% based on 13b). Mp:
135 °C (dec). IR (KBr, cm-1): 2208 (m), ν(FcCtC); 1953 (w),
H, C5H5), 4.35 (pt, JHH ) 1.9 Hz, 2 H, Hâ/C5H4), 4.53 (pt, JHH
)
1
1.9 Hz, 2 H, HR/C5H4), 7.46 (m, 1 H, H5′), 8.07-8.13 (m, 4 H,
ν(TiCtC); 1088 (s), ν(ClO). H NMR (CDCl3): δ -0.29 (s, 18
3
H3, H3′, H4, H4′), 9.51 (bs, JPtH ) 26 Hz, 2 H, H6, H6′). ESI-
H, SiMe3), 0.29 (s, 18 H, SiMe3), (s, 5 H, C5H5 [Fc]), 4.33 (pt, JHH
) 1.9 Hz, 2 H, Hâ/C5H4 [Fc]), 4.58 (pt, JHH ) 1.9 Hz, 2 H, HR/
C5H4 [Fc]), 6.46 (pt, JHH ) 2.3 Hz, 4 H, C5H4), 6.51 (pt, JHH ) 2.3
Hz, 4 H, C5H4), 7.62 (ddd, 3JH5′H4′ ) 7.8 Hz, 3JH5′H6′ ) 5 Hz, 4JH5′H3′
MS [m/z (rel int)]: [M+] 753 (100), [M2+] 1507 (40). Anal. Calc
for C32H34FeN2PtSi2‚1/4 CH2Cl2 (774.96): C, 49.98; H, 4.49; N,
3.61. Found: C, 50.07; H, 4.60; N, 3.47.
3
4
) 1 Hz, 1 H, H5′), 8.18 (dd, JH4H3 ) 8.4 Hz, JH4H6 ) 2.2 Hz, 1
Synthesis of {Fc-CtC-bipy[Pt(µ-σ,π-CtCSiMe3)2]Cu}BF4
(12). To 10 (50 mg, 0.063 mmol) dissolved in 30 mL of THF was
added [Cu(CH3CtN)4]BF4 (11) (20 mg, 0.063 mmol) in one
portion. Upon 12 h of stirring at 25 °C, the color of the reaction
mixture changed from red to purple. The solvent was reduced in
volume (5 mL), and 12 was precipitated upon addition of n-hexane
(20 mL), washed twice with n-hexane (10 mL), and dried in an
oil-pump vacuum. Trimetallic 12 was obtained as a purple solid.
Yield: 55 mg (0.061 mmol, 97% based on 10). Mp: 188 °C (dec).
IR (KBr, cm-1): 2207 (m), ν(FcCtC); 1977 (m), 1961 (m),
3
3
4
H, H4), 8.19 (ddd, JH4′H3′ ) JH4′H5′ ) 7.8 Hz, JH4′H6′ ) 1.8 Hz,
1 H, H4′), 8.51-8.56 (m, 3 H, H3, H3′, H6), 8.60 (d, 3JH6′H5′ ) 5
Hz, 1 H, H6′). 13C{1H} NMR (CDCl3): δ -0.06 (SiMe3), 0.15
(SiMe3), 63.4 (Ci/C5H4, Fc), 69.8 (Câ/C5H4 [Fc]), 70.3 (C5H5 [Fc]),
71.9 (CR/C5H4 [Fc]), 81.5 (Fc-CtC-bipy), 96.7 (Fc-CtC-bipy),
117.4 (CH/C5H4), 119.2 (CH/C5H4), 123.5 (bipy), 123.6 (Ci/C5H4),
124.2 (bipy), 126.0 (bipy), 126.2 (bipy), 138.6 (d, JCAg ) 4.3 Hz,
CtCSi), 140.4 (bipy), 141.7 bipy), 149.7 (bipy), 150.4 (bipy), 151.6
(bipy), 151.6 (bipy), 153.7 (d, JCAg ) 14.9 Hz, TiCtC). 29Si{1H}
2
1
NMR (CDCl3): δ -18.4 (d, JAgSi ) 2 Hz, CtCSiMe3), -5.1
(C5H4SiMe3). Anal. Calc for C48H60AgClFeN2OSi4Ti (1080.3): C,
52.97; H, 5.56; N, 2.57. Found: C, 52.82; H, 5.70; N, 2.45.
ν(PtCtC); 1084 (s), 1053 (s), ν(BF). H NMR (CD3CN): δ 0.31
(s, 9 H, SiMe3), 0.37 (s, 9 H, SiMe3), 4.31 (s, 5 H, C5H5), 4.44 (pt,
JHH ) 1.9 Hz, 2 H, Hâ/C5H4), 4.61 (pt, JHH ) 1.9 Hz, 2 H, HR/
3
3
4
C5H4), 7.71 (ddd, JH5′H4′ ) 7.3 Hz, JH5′H6′ ) 5.2 Hz, JH5′H3′
)
Crystal Structure Determinations. Crystal data for 3, 10, and
14a are presented in Table 3. All data were collected on a Bruker
Smart CCD 1k diffractometer at 203(2) K (3), 178(2) K (10), or
1.8 Hz, 1 H, H5′), 8.19-8.25 (m, 3 H, H3, H3′, H4), 8.27 (ddd,
3JH4′H3′ ) JH4′H5′ ) 8 Hz, JH4′H6′ ) 1.4 Hz, 1 H, H4′), 8.97 (d,
3
4

Heterobi- and Heterotrimetallic Transition Metal Complexes
Organometallics, Vol. 25, No. 19, 2006 4587
298 K (14a) using oil-coated, shock-cooled crystals26 using Mo
KR radiation (λ ) 0.71073 Å). The structures were solved by direct
methods using SHELXS-9727 and refined by full-matrix least-
squares procedures on F2 using SHELXL-97.28 All non-hydrogen
atoms were refined anisotropically, and a riding model was
employed in the refinement of the hydrogen atom positions. In 14a
the PF6 counterion and one Me3Si group are disordered and have
been refined to split occupancies of 0.54/0.46 (PF6) and 0.61/0.39
(SiMe3), respectively.
Acknowledgment. We are grateful to the Deutsche
Forschungsgemeinschaft for financial support.
Supporting Information Available: Tables of atomic coordi-
nates, bond lengths, angles, torsion angles, and anisotropic displace-
ment parameters for 3, 10, and 14a. This material is available free
of charge via the Internet at http://pubs.acs.org.
(26) (a) Kottke, T.; Stalke, D. J. Appl. Crystallogr. 1993, 26, 615. (b)
Kottke, T. Lagow, R. J.; Stalke, D. J. Appl. Crystallogr. 1996, 29, 465. (c)
Stalke, D. Chem. Soc. ReV. 1998, 27, 171.
(27) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
(28) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen, 1997.
OM0602355