Preparation, properties, and reactions of metal-containing heterocycles. Part CVIII. A novel generation of rigid, nanoscaled 1,1′-ferrocenediyl-bridged bis(pyridine), bis(bipyridine), and bis(phenanthroline) ligands

Article abstract of DOI:10.1016/S0022-328X(02)01774-6

Four novel, rigid, and conjugated 1,1′-ferrocenediyl-bridged, bis(pyridine), bis(bipyridine), and bis(phenanthroline) ligands 2 and 5-7 have been synthesized by palladium promoted C-C coupling reactions and characterized by ¹H-, ¹³C{¹H}-NMR, FT-IR, and mass spectroscopy as well as by elemental analyses. Ligand 2 was prepared from 5-ethynyl-2,2′-bipyridine and 1,1′-diiodoferrocene, while compounds 5-7 were readily accessible by reactions between pre-constructed ferrocene 4 and 4-bromopyridine, 5-bromo-2,2′-bipyridine, and 3-bromo-1,10-phenanthroline, respectively. Treatment of 1,1′-diiodoferrocene with 1-ethynyl-4-triisopropylsilyl ethynyl-2,5-dipropoxybenzene resulted in the formation of the ferrocene derivative 3. Via a Si-C bond cleavage in 3 in the presence of tetra-n-butylammonium fluoride in THF the intermediate 4 was obtained. Ligand 1.0.5H₂O crystallizes in the triclinic space group P 1 with a=11.2711(10), b=13.3346(12), c=14.0879(14) A , α=105.007(12), β=105.179(11), γ=105.218(10)8, V=1845.7 A³, Z=2, R=0.0640, and wR₂=0.1292.

Full text of DOI:10.1016/S0022-328X(02)01774-6

Journal of Organometallic Chemistry 660 (2002) 78ꢀ84
/
www.elsevier.com/locate/jorganchem
Preparation, properties, and reactions of metal-containing
heterocycles1
Part CVIII. A novel generation of rigid, nanoscaled 1,1?-
ferrocenediyl-bridged bis(pyridine), bis(bipyridine), and
bis(phenanthroline) ligands
Ekkehard Lindner *, Ruifa Zong, Klaus Eichele, Markus Strobele
¨
Institut fur Anorganische Chemie der Unversitat Tubingen, Auf der Morgenstelle 18, D-72076 Tubingen, Germany
¨ ¨ ¨ ¨
Received 23 May 2002; received in revised form 24 June 2002; accepted 5 July 2002
Abstract
Four novel, rigid, and conjugated 1,1?-ferrocenediyl-bridged, bis(pyridine), bis(bipyridine), and bis(phenanthroline) ligands 2 and
5ꢀ7 have been synthesized by palladium promoted CÃ
C coupling reactions and characterized by 1H-, 13C{1H}-NMR, FT-IR, and
mass spectroscopy as well as by elemental analyses. Ligand 2 was prepared from 5-ethynyl-2,2?-bipyridine and 1,1?-diiodoferrocene,
while compounds 5ꢀ7 were readily accessible by reactions between pre-constructed ferrocene 4 and 4-bromopyridine, 5-bromo-2,2?-
bipyridine, and 3-bromo-1,10-phenanthroline, respectively. Treatment of 1,1?-diiodoferrocene with 1-ethynyl-4-triisopropylsilyl
ethynyl-2,5-dipropoxybenzene resulted in the formation of the ferrocene derivative 3. Via a SiÃC bond cleavage in 3 in the presence
0.5H2O crystallizes in the triclinic space
105.179(11), gꢁ105.218(10)8, Vꢁ1845.7
0.1292. # 2002 Elsevier Science B.V. All rights reserved.
/
/
/
/
of tetra-n-butylammonium fluoride in THF the intermediate 4 was obtained. Ligand 1×
/
˚
¯
group P1 with aꢁ
/
11.2711(10), bꢁ
/
13.3346(12), cꢁ
/
14.0879(14) A, aꢁ
/
105.007(12), bꢁ
/
/
/
3
˚
A , Zꢁ
/
2, Rꢁ
/
0.0640, and wR2ꢁ
/
Keywords: Bis(pyridines); Bis(2,2?-bipyridines); Bis(1,10-phenanthrolines); 1,1?-Ferrocene; CÃC coupling reactions; X-ray structure
/
1. Introduction
factors such as hostꢀ/guest interactions [13], the nature
of connectors between the metal centers [14ꢀ
/16],
Due to the potential application in material sciences
as molecular devices and electronic sensors the incor-
poration of redox active metallocenes in supramolecular
structures encounters increasing interest in recent years.
Systems of this type open the possibility to study
electronic communication between metal-based centers
structural rearrangements [16], orbital alignments [17],
orbital orderings [18], and in particular the distance
between the metals [14,19] are influencing the degree of
electronic communication. Therefore, it is important to
construct molecules which guarantee to keep the metals
well separated from each other to rule out through space
electronic communication. Furthermore, it was demon-
strated that the degree of conjugation within the
molecular backbone between the transition metals also
plays an important role [20]. In this investigation we
report on the synthesis of hitherto unknown conjugated
rigid ligand systems which are able to function as
valuable precursors for the access to macrocycles with
the potential to show electronic communication. Build-
ing blocks for the construction of these ligands are
ferrocene, pyridine and its derivatives bipyridine, and
phenanthroline, 1,4-diethynylbenzene, or acetylene.
[2ꢀ9]. Basically there is a distinction between two
/
different effects, namely through bond and through
space, or through solvents in solution. The former is
more effective than the latter [10] and the redox
properties can be easily controlled [11,12]. Several
* Corresponding author. Tel.: ꢂ
/
49-7071-2972039; fax: ꢂ49-7071-
/
295306
E-mail address: ekkehard.lindner@uni-tuebingen.de (E. Lindner).
1
Part CVII, see Ref. [1].
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 7 7 4 - 6

E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ
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84
79
2. Results and discussion
cular composition was evidenced by an EI mass
spectrum.
A suitable way for the access of the ligands 5ꢀ7 is the
/
2.1. Design of the polydentate ligands 1 [21,22], 2, and
employment of the pre-constructed 1,1?-ferrocenediylbi-
s(ethynylene) (4). As a first step for the preparation of 4
the ferrocene derivative 3 was synthesized in 55% yield
5ꢀ7
/
Pyridine and its derivatives 2,2?-bipyridine and 1,10-
phenanthroline functionalized at positions 4 [23], 5 or
5,5? [24,25], and 3 or 3,8 [26], respectively, have attracted
great attention. Because of their structural character-
istics they are employed in the investigation of molecular
wires. 5- and 3-Ethynyl substituted 2,2?-bipyridine
[24,27] and 1,10-phenanthroline [28,29], respectively,
are important building blocks for the synthesis of
materials applied in molecular electronics, because the
acetylene moiety is connected to the electron rich
positions of the aromatic amines. Such a unit is expected
to favor through bond electronic communication. Due
to mainly synthetic difficulties, only rather limited
experiments have been carried out with these promising
pyridine derivatives. Incorporation of these building
by a CÃ
cene and 1-ethynyl-4-(triisopropylsilylethynyl)-2,5-di-
propoxybenzene [33] in mixture of THF and
/
C coupling reaction between 1,1?-diiodoferro-
a
diisopropylamine (Scheme 2). The intermediate 3 was
characterized by mass and NMR spectroscopy as well as
by elemental analyses (see Section 4). In a following
reaction the ferrocene derivative 4 was obtained by
cleavage of the triisopropylsilyl substituents from 3 in
the presence of tetra-n-butylammonium fluoride in THF
at 20 8C (Scheme 3). No isolation of 4 is necessary and
the removal of the protecting group is performed prior
to the coupling reaction with 4-bromopyridine, 5-
bromo-2,2?-bipyridine, and 3-bromo-1,10-phenanthro-
line in THFꢀ
of 5ꢀ7 an excess amount of the bromo-N-heterocycles
was applied. After column chromatography with silica
gel and dichloromethaneꢀmethanolꢀTHF, compounds
5ꢀ7 are obtained as orange, air-stable powders in yields
/diisopropylamine. To optimize the yields
/
blocks into the ligands 1, 2, and 5ꢀ7 will make the side
/
chains of the subunits linear and the ferrocene based
ligands symmetric. Here we present the first examples of
ligand systems in which a 1,1?-ferrocenediyl unit is
connected to 2,2?-bipyridine and 1,10-phenanthroline
at position 5 and 3, respectively, via conjugated linkers.
The introduction of propoxy substituents into the para-
position of the phenylene bridges solves the problem of
low solubility.
/
/
/
between 45 and 52%, which are soluble in chlorinated
solvents and THF, but insoluble in acetonitrile, diethyl
ether, or saturated hydrocarbons. The molecular com-
positions of 5ꢀ/7 were confirmed by FD, EI, and FAB
mass spectra.
2.3. NMR and IR spectroscopic characterization of 5ꢀ7
/
2.2. Synthesis of the ligands 2 and 5ꢀ7
/
The polydentate nitrogen ligands 5ꢀ
vocally identified by their 1H- and 13C{1H}-NMR
spectra. Because of the high symmetry of 5ꢀ7 the
/
7 were unequi-
All CÃ
/
C coupling reactions mentioned in Schemes 1ꢀ
/
3
were promoted by either Cl2Pd(PPh3)2/CuI or
/
Pd(PPh3)4 in the presence of organic amines [30]. While
ligand 1 has already been described in an earlier paper
[21], 2 is accessible in 19% yield by reaction of 1,1?-
diiodoferrocene [31] with 5-ethynyl-2,2?-bipyridine [32]
in diisopropylamine as a solvent which concomitantly
functions as a proton acceptor (Scheme 1). The red
bipyridine derivative is thermally and air stable and only
slightly soluble in common organic solvents. Its mole-
protons and carbon atoms in both side chains of the
ferrocene unit do not differ in their chemical shifts. Both
protons in the phenylenes of 5ꢀ7 which are unsymme-
/
trically substituted in the para-position, give rise to each
1
one singlet at ca. 7 ppm in the H-NMR spectra. The
propoxy group is characterized by two triplets resulting
from the protons of the a-methyl and g-methylene
functions and a multiplet which is assigned to the
Scheme 1.

80
E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ
/
84
Scheme 2.
protons of the b-CH2 unit. In CDCl3 or CD2Cl2, the
cyclopentadienyl protons in 5ꢀ7 reveal an AA?XX?
pattern with centers lying between 4.6 and 4.4 ppm.
adjacent to the nitrogen atoms. Carbon atoms next to
the alkyne moieties give rise to 13C signals at 131.8 (5),
120.6 (6), and 119.3 ppm (7).
/
A characteristic absorption in the IR spectra (KBr) of
7 at about 2210 cmꢃ1 corresponds to the CÅ
stretching vibration of the alkyne functions.
The a-protons in the N-heterocycles exhibit the largest
chemical shifts at 8.5, 8.8, and 9.2 ppm in the H-NMR
1
2, and 5ꢀ
/
/C
spectra of 5, 6, and 7, respectively. All other resonances
are summarized in Section 4.
Each ligand is provided with two alkyne moieties as
connectors. Hence four different chemical shifts are
2.4. X-ray crystal structure of ligand 1
found in the 13C{1H}-NMR spectra of 5ꢀ
7 located
between 82 and 94 ppm. Six well resolved singlets are
/
Although the preparation of ligand 1 has already been
reported [21,22], its structure is still unknown. Ligand 1
¯
crystallizes in the triclinic space group P1: The asym-
metric unit contains two crystallographically indepen-
dent molecules A and B of 1 and a molecule of water,
observed for the phenylene carbon atoms in the regions
153ꢀ
115.7 ppm (C1 and C4). Three 13C resonances between
73 and 66 ppm in the spectra of the ligands 5ꢀ7 are
/
154 (C Ã
/
OC3H7), 116.4ꢀ
/
116.8 (CÃ
/
H), and 111.7ꢀ
/
/
which is hydrogen bonded to N(1) and N(4), with OÃ
/
N
attributed to the cyclopentadienyl carbon atoms. In
contrast to dialkylsubstituted 1,1?-ferrocenes the ipso-C
atoms resonate at higher field than the other carbon
atoms. The assignment of the carbon atoms was
supported by a DEPT-135 experiment, because in the
above-mentioned region also the 13C signals of the a-
carbon atoms of the propoxy groups can be observed.
˚
distances of 2.773 and 2.916 A, respectively. Selected
distances and angles are listed in Table 1. An ORTEP plot
of A and B with atom labeling is depicted in Fig. 1. The
iron ring-centroid distances Fe(1)Ã
/
Cp(center) and
˚
Cp(center) are 1.66 and 1.67/1.64 A, respectively.
Fe(2)Ã
/
Between the pyridine units the average nitrogenÃ
/
nitro-
˚
gen distance was found to be 3.96 A. While the two
cyclopentadienyl rings in A and B are nearly parallel
The 13C part of the N-heterocycles in 5ꢀ
7 shows the
/
expected signals for the different carbon atoms and the
largest downfield shifts are ascribed to the carbon atoms
with angles of dꢁ
the resulting dihedral angles (tilt angle a) are found to
/
176.78 (ring centerꢀ
/
ironꢀ
/
ring center),
Scheme 3.

E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ
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84
81
Table 1
Selected bond lengths (A) and angles (8) for 1×0.5H2O
1 are separated by distances of 3.78 (molecule A) and
˚
3.85 A (molecule B). A significant deviation from
˚
coplanarity is observed, as revealed by tilt angles of
5.89(46)/5.60(49) (A) and 17.12(63)/29.20(49)8 (B) be-
tween the cyclopentadienyl ring and the pyridines. The
Molecule A Molecule B
Distances
N(1)ÃN(2)
N(3)ÃN(4)
FeÃcenter Cp(1)
FeÃcenter Cp(2)
Center Py(1)Ãcenter Py(2)
3.929(16)
torsion angles of ꢃ
/
3.4 and 1.308 defined by C(8)Ã
/
C(1)Ã
/
4.006(16)
1.67
1.64
C(13)ÃC(20) and C(32)Ã
/
/
C(25)ÃC(37)ÃC(44), indicate a
/
/
1.66
1.66
3.78
nearly eclipsed structure of 1 in the solid state. It is of
interest that the two side chains of 1 point roughly to the
same direction, which is similar to our previous ob-
servation in the crystal structure of 1,1?-bis(3-pyridy-
3.85
Bond angles
dꢁ(CpÃFeÃCp)
176.7
176.7
lethynyl)ferrocene [21]. This is attributed either to pꢀp
/
Interplanar angles
aꢁCp(1)ÃCp(2)
Py(1)ÃPy(2)
interactions between the two side chains [34] or to
crystal packing forces. Crystal data and structure
refinement are given in Table 2.
4.04(47)
5.16(47)
5.60(49)
5.89(46)
4.60(85)
15.85(49)
17.12(63)
29.20(49)
CpÃPy
Torsion angles
C(6)ÃCp(1)ÃCp(2)ÃC(18)
C(30)ÃCp(1)ÃCp(2)ÃC(42)
C(8)ÃC(1)ÃC(13)ÃC(20)
C(32)ÃC(25)ÃC(37)ÃC(45)
Centers Py(1)ÃCp(1)ÃCp(2)ÃPy(2)
ꢃ0.3
ꢃ3.4
ꢃ3.4
3. Conclusion
ꢃ0.8
1.3
0.3
In order to connect two N-heterocycles with two
cyclopentadienyl rings of a 1,1?-ferrocene entity with
acetylene or para-phenylene ethynylene linkers, two
synthetic strategies have been developed and discussed.
The first one is featured by pre-constructed terminal
Table 2
Crystal data and structure refinement for 1×0.5H2O
Empirical formula
Formula weight
Temperature (K)
C48H34Fe2N4O
794.49
298(2)
0.71073
Triclinic
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
¯
P1/
/
˚
a (A)
11.2711(10)
13.3346(12)
14.0879(14)
105.007(12)
105.179(11)
105.218(10)
1845.7(3)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
3
˚
V (A )
Z
Dcalc (g cmꢃ3
)
1.430
0.830
Absorption coefficient (mmꢃ1
F(000)
)
820
0.46ꢄ0.22ꢄ0.02
Crystal size (mm3)
u Range for data collection (8) 2.11ꢀ
/
24.94
Limiting indices
ꢃ135h 513, ꢃ155k 515,
ꢃ165l 516
8518
Reflections collected
Unique reflections
3535 [Rintꢁ0.0966]
54.7%
Full-matrix least-square on F2
3535/0/504
Completeness to uꢁ24.94
Refinement methods
Data/restraints/parameters
Final R indices [I ꢀ2s(I)]
R indices (all data)
Fig. 1. ORTEP plot of the two independent molecules A and B of 1 and
of the water molecule, indicating the numbering scheme. In this
projection the water molecule is located nearly above molecule B.
Probabilities are drawn at the 20% level.
R1ꢁ0.0640, wR2ꢁ0.1292
R1ꢁ0.1609, wR2ꢁ0.1617
0.791
Goodness-of-fit on F2
Largest difference peak and hole 0.980 and ꢃ0.373
be 4.04(47) and 4.60(85)8. The dihedral angles between
the pyridine rings in A and B show values of 5.16(47)
and 15.85(49)8, respectively. The pyridine ring centers of
ꢃ3
˚
(e A
)
R1ꢁa jjFojꢃjFcjj/ja jFoj. wR2 ꢁ[a [w(Fo2 ꢃFc2)2]=a [w(Fo2)2]]0:5
:/

82
E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ84
/
ethynyl-N-heterocycles, while the second one refers to
the pre-organized 1,1?-ferrocenediylbis(acetylene) deri-
vative 4. Both of the approaches have been successively
solvents were removed in vacuo and the residue was
treated with 100 ml of a 1:1 mixture of water and
CHCl3. The organic extract was dried over MgSO4.
Column chromatography was conducted with silica gel
applied for the synthesis of the ligands 2 and 5ꢀ7,
/
respectively. The parallel arrangement of the side chains
in the crystal structure of 1 is expected to play a role in
the formation of transition metal complexes. The
complexation of the nitrogen functionalized bidentate
and tetradentate ligands and electronic communication
of their complexes are under investigation.
and 0ꢀ5% MeOH in CH2Cl2. Yield: 105 mg (19%), air
/
stable, red powder, m.p. ꢀ
/
260 8C (dec.). 1H-NMR
2.1 Hz, 2H, H-6), 8.50
4
8.53 (d, JHH
(CD2Cl2): dꢁ
/
ꢁ
/
3
(ddd, JHH
4
4.8, JHH
5
1.7, JHH
ꢁ
/
ꢁ
/
ꢁ0.7 Hz, 2H, H-6?),
/
3
8.20 (ddd, JHH
4
5
ꢁ
/
8.0, JHH
ꢁ
/
1.0, JHH
8.2 Hz, 2H, H-3), 7.69 (dd,
2.1 Hz, 2H, H-4), 7.55 (ddd,
ꢁ
/
1.0 Hz, 2H,
3
H-3?), 8.18 (d, JHH
ꢁ
/
4
8.2, JHH
3JHH
3JHH
ꢁ
/
ꢁ
/
3
7.7, JHH
4
ꢁ
/
ꢁ
/
7.7, JHH
ꢁ1.7 Hz, 2H, H-4?), 7.12
/
3
4
5
4. Experimental
(ddd, JHH
4.62 (m [36], 4H, C4H4C), 4.40 (m [37], 4H, C4H4C). EI-
MS (70 eV, 200 8C): m/z 542.0 [Mꢂ], 241.9 [(Mꢃ
Fe)/
2]ꢂ. IR (KBr, cmꢃ1): n(CÅ
C)ꢁ2207. Anal. Found: C,
/
ꢁ
/
7.5, JHH
ꢁ
/
4.8, JHH
ꢁ
/
1.2 Hz, 2H, H-5?),
4.1. General procedures
/
/
/
All reactions and manipulations were carried out
under an atmosphere of Ar by use of standard Schlenk
techniques except otherwise noted. Amines were dried
by NaOH or CaH2 and distilled, degassed, and stored
under Ar. THF was distilled from sodium benzophe-
73.99; H, 3.83; N, 10.18. Calc. for C34H22FeN4×
0.1CH2Cl2 (550.91): C, 74.34; H, 4.06; N, 10.17%.
4.2.2. 1,1?-Bis{[2,5-dipropoxy-4-
(triisopropylsilylethynyl)phenyl]ethynyl}ferrocene (3)
To a solution of 1,1?-diiodoferrocene (642 mg, 1.47
mmol) and 1-ethynyl-4-(triisopropylsilyl)ethynyl-2,5-di-
propoxybenzene (1245 mg, 3.1 mmol) in a mixture of
none ketyl prior to use. Column chromatography (30ꢄ
5 cm) was conducted using either activated silica gel,
0.063ꢀ0.200 mm (Merck), or neutral Al2O3 (Merck) as
/
/
reported in the specific sections describing the synthesis
of the compounds. IR data were obtained with a Bruker
IFS 48 FT-IR spectrometer. EI mass spectra were taken
on a Finnigan MAT TSQ 70 (200 8C) instrument while
FD and FAB mass spectra were recorded on a Finnigan
Et3Nꢀdiisopropylamine (50/20 ml), Pd(PPh3)2Cl2 (102
/
mg, 0.15 mmol) and CuI (108 mg, 0.57 mmol) were
added. The mixture was refluxed at 80 8C for 2 days
followed by removal of the solvents under vacuum. The
residue was extracted with Et2O (4ꢄ100 ml) and the
/
1
MAT 711A (8 kV) instrument, modified by AMD. H-
organic layer was dried over MgSO4. After removal of
the solvent by a rotation evaporator, the residue was
and 13C{1H}-NMR spectra were recorded at 25 8C on a
Bruker DRX 250 spectrometer operating at 250.13 and
62.90 MHz, respectively. 1H and 13C chemical shifts
were measured relative to partially deuterated solvent
peaks and to deuterated solvent peaks, respectively,
which are reported relative to Me4Si. Elemental analyses
were carried out with an Elementar Vario EL analyzer.
1,1?-Diiodoferrocene [31], 5-bromo-2,2?-bipyridine
[35], 5-ethynyl-2,2?-bipyrdine [32], and 3-bromo-1,10-
phenanthroline [26] were synthesized according to
literature methods. A highly selective method similar
to a recent publication is applied for the preparation of
1-ethynyl-4-triisopropylsilylethynyl-2,5-dipropoxyben-
zene [33], which was purified by column chromatogra-
subjected to column chromatography (Al2O3, 0ꢀ5%
/
Et2O in n-C6H14). The desired ferrocene derivative 3
was isolated in the third fraction. Yield: 798 mg (55%),
orange, air-stable powder, m.p. 149 8C. 1H-NMR
(CDCl3): dꢁ/6.92 (s, 2H, C6H2), 6.88 (s, 2H, C6H2),
4.57 (m [36], 4H, C4H4C), 4.35 (m [37], 4H, C4H4C),
3
3.96 (t, JHH
3JHH
6.4 Hz, 4H, OCH2CH2CH3), 1.85 (m, 8H,
OCH2CH2CH3), 1.15 (s, 42H, SiC9H21), 1.03 (m, 12H,
OCH2CH2CH3). 13C{1H}-NMR (CDCl3): dꢁ
154.29,
ꢁ
/
6.4 Hz, 4H, OCH2CH2CH3), 3.85 (t,
ꢁ
/
/
153.15 (C-2 and C-5, C6H2), 117.52, 116.19 (C-3 and C-
6, C6H2), 114.59, 113.35 (C-1 and C-4, C6H2), 103.06,
96.00 (C Å
/
C Ã
/
SiC9H21), 92.87, 82.69 (C Å
/
C Ã/C5H4),
phy with neutral Al2O3 and 0ꢀ
/
1% Et2O in n-C6H14.
73.00 (C4H4C), 71.44 (C4H4C), 71.05, 70.60
(OCH2CH2CH3), 66.64 (C4H4C), 22.74, 22.61
(OCH2CH2CH3), 18.64, 11.30 (SiC9H21), 10.62, 10.57
(OCH2CH2CH3). EI-MS (70 eV, 200 8C): m/z 978.5
4.2. Preparation of the intermediates 3 and 4 and of the
ligands 2, 5ꢀ
/
7
[Mꢂ]. IR (KBr, cmꢃ1): n(CÅ
/
C)ꢁ2150. Anal. Found:
/
4.2.1. Synthesis of 1,1?-bis(2,2?-bipyridine-5-yl-
ethynyl)ferrocene (2)
C, 73.50; H, 7.94. Calc. for C60H82FeO4Si2 (979.32): C,
73.59; H, 8.44%.
To a solution of 1,1?-diiodoferrocene (440 mg, 1.0
mmol) and 5-ethynyl-2,2?-bipyridine (400 mg, 2.2 mmol)
in diisopropylamine (20 ml), Pd(PPh3)2Cl2 (28 mg, 0.04
mmol) and CuI (19 mg, 0.1 mmol) were added. The
mixture was refluxed at 80 8C for 2 days. Then the
4.2.3. General procedure for the preparation of the
ligands 5ꢀ7
/
To a solution of 3 (980 mg, 1.0 mmol) in THF (50 ml)
two equivalents of tetra-n-butylammonium fluoride

E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ
/
84
83
3
7.80 (ddd, JHH
3
7.8, JHH
4
7.8, JHH
(520 mg, 2.0 mmol) were added at 20 8C. The solution
was stirred for 2 h at the same temperature. Then a 50%
excess of 4-bromopyrydine hydrochloride, 5-bromo-
2,2?-bipyridine, and 3-bromo-1,10-phenanthroline, re-
spectively, diisopropylamine (20 ml) (and in the case of
phenanthroline also 20 ml of n-propylamine) as well as
Pd(PPh3)Cl2 (35 mg, 0.05 mmol) and CuI (20 mg, 0.1
mmol) were added. In the case of phenanthroline
additional Pd(PPh3)4 was used as a catalyst. The oil-
bath temperature was controlled at 80 8C, and the
mixture was stirred for 2 days. After cooling down to
room temperature (r.t.), the solvents were removed
under vacuum and a concd. aq. NH4Cl solution (50
ml) was added. The residue was extracted at least four
times, each with 50 ml of CH2Cl2. The organic extract
was washed with 200 ml of an aq. NaCl solution and
finally it was dried over MgSO4. After removal of the
solvents, the residue was ready for column chromato-
graphy using silica gel and CH2Cl2. The product was
ꢁ
/
ꢁ
/
ꢁ
/
1.7 Hz, 2H,
H-4?), 7.30 (ddd, 3JHH
ꢁ
/
7.5, 3JHH
ꢁ
/
4.8, 4JHH
ꢁ1.1 Hz,
/
2H, H-5? in C10H7N2), 6.99 (s, 2H, C6H2), 6.93 (s, 2H,
C6H2), 4.59 (m [36], 4H, C4H4C), 4.37 (m [37], 4H,
3
C4H4C); 3.99 (t, JHH
ꢁ6.44 Hz, 4H, OCH2CH2CH3),
/
3
3.94 (t, JHH
8H, OCH2CH2CH3), 1.13 (t, JHH
OCH2CH2CH3), 1.11 (t, 3JHH
OCH2CH2CH3). 13C{1H}-NMR (CDCl3): dꢁ
ꢁ6.44 Hz, 4H, OCH2CH2CH3), 1.88 (m,
/
3
ꢁ
/
7.38 Hz, 6H,
7.38 Hz, 6H,
155.43,
ꢁ
/
/
154.57 (C-2 and C-2?, C10H7N2), 153.73, 153.38 (C-2
and C-5, C6H2), 151.52, 149.22 (C-6 and C-6?,
C10H7N2), 139.09, 136.90 (C-4 and C-4?, C10H7N2),
123.82, 121.26 (C-3 and C-3?, C10H7N2), 120.58 (C-5,
C10H7N2), 120.30 (C-5?, C10H7N2), 116.70, 116.59 (C-3
and C-6, C6H2), 115.23, 112.40 (C-1 and C-4, C6H2),
93.33, 91.47, 90.35, 82.76 (C Å
/
C Ã
/
C6H2Ã
/
C Å
/C), 72.93,
71.52 (C4H4C), 70.99, 70.90 (OCH2CH2CH3), 66.77
(C4H4C), 22.74 (OCH2CH2CH3), 10.67, 10.59
(OCH2CH2CH3). EI-MS (70 eV, 200 8C): m/z 974.3
eluted by a solvent mixture of MeOH (0ꢀ
/
5%), THF
[Mꢂ], 460.1 [(Mꢃ
C)ꢁ
Calc. for C62H54FeN4O4 (974.98): C, 76.38; H, 5.58; N,
/
Fe)/2ꢂ
/
1]ꢂ. IR (KBr, cmꢃ1): n(CÅ
/
(10ꢀ50%), and CH2Cl2. Recrystallization from CH2Cl2
/
/
2216. Anal. Found: C, 76.01; H, 5.94; N, 5.20.
and n-pentane gave spectroscopically pure products.
5.75%.
4.2.3.1. 1,1?-Bis{[4-(4-pyridylethynyl)-2,5-
dipropoxyphenyl]ethynyl}ferrocene (5). Initial weight:
4-bromopyridiniumchloride (580 mg, 3.0 mmol). Yield:
1
427 mg (52%), orange powder, m.p. 161 8C. H-NMR
4.2.3.3. 1,1?-Bis{[4-(1,10-phenanthroline-3-yl-ethynyl)-
2,5-dipropoxy-phenyl]ethynyl}ferrocene (7). Initial
weights: 3-bromo-1,10-phenanthroline (780 mg, 3.0
mmol), Pd(PPh3)4 (140 mg, 0.12 mmol), Pd(PPh3)2Cl2
(14 mg, 0.02 mmol), and CuI (15 mg, 0.08 mmol). Prior
to chromatography the copper complex was extracted
with a 2% solution of KCN in water (100 ml).
Recrystallization was carried out with CHCl3 and n-
3
8.50 (d, JHH
(CDCl3): dꢁ
/
ꢁ5.0 Hz, 4H, H-a, C5H4N),
/
3
7.34 (d, JHH
C6H2), 6.91 (s, 2H, C6H2), 4.57 (m [36], 4H, C4H4C),
ꢁ
/
5.0 Hz, 4H, H-b, C5H4N), 6.96 (s, 2H,
3
4.36 (m [37], 4H, C4H4C), 3.95 (t, JHH
ꢁ6.1 Hz, 4H,
/
OCH2CH2CH3), 3.91 (t, 3JHH
OCH2CH2CH3), 1.86 (m, 8H, OCH2CH2CH3), 1.10
ꢁ/6.4 Hz, 4H,
C6H14. Yield: 521 mg (51%), orange powder, m.p.
172 8C. 1H-NMR (CD2Cl2): dꢁ
(m, 12H, OCH2CH2CH3). 13C{1H}-NMR (CDCl3):
/
ꢁ2.0
/
4
9.13 (d, JHH
3
4
dꢁ
/
153.90, 153.28 (C-2 and C-5, C6H2), 149.66 (C-a,
Hz, 2H, H-2, C12H7N2), 9.04 (dd, JHH
ꢁ
ꢁ
/
4.3, JHH
2.0 Hz, 2H,
8.0, JHH 1.7 Hz,
ꢁ
/
C5H4N), 131.57 (C-g, C5H4N), 125.27 (C-b, C5H4N),
116.81, 116.50 (C-3 and C-6, C6H2), 115.74, 111.70 (C-1
1.7 Hz, 2H, H-9, C12H7N2), 8.10 (d, 4JHH
/
3
H-4, C12H7N2), 8.01 (dd, JHH
4
ꢁ
/
ꢁ
/
3
3
and C-4, C6H2), 93.58, 91.60, 90.77, 82.61 (C Å
/
C Ã
/
2H, H-7, C12H7N2), 7.53 (dd, JHH
ꢁ
/
8.0, JHH
ꢁ4.3
/
C6H2ÃC ÅC), 72.93 (C4H4C), 71.50 (C4H4C), 70.94,
/
/
Hz, 2H, H-8, C12H7N2), 7.47 (s, 4H, H-5 and H-6,
C12H7N2), 6.96 (s, 2H, H-3 or 6, C6H2), 6.81 (s, 2H, H-3
or 6, C6H2), 4.58 (m [36], 4H, C4H4C), 4.38 (m [37], 4H,
70.79 (OCH2CH2CH3), 66.62 (C4H4C), 22.67, 22.62
(OCH2CH2CH3), 10.60, 10.50 (OCH2CH2CH3). FD-
MS (30 8C): m/z (%) 817.6 (7), 818.6 (4), 819.6 (100),
820.6 (60), 821.6 (21), 822.6 (5) [Mꢂ]. IR (KBr, cmꢃ1):
3
C4H4C), 3.96 (t, JHH
ꢁ6.4 Hz, 4H, OCH2CH2CH3),
/
3
3.93 (t, JHH
8H, OCH2CH2CH3), 1.19 (t, JHH
OCH2CH2CH3), 1.15 (t, 3JHH
OCH2CH2CH3). 13C{1H}-NMR (CD2Cl2): dꢁ
ꢁ6.4 Hz, 4H, OCH2CH2CH3), 1.91 (m,
/
3
n(CÅ
/
C)ꢁ
/
2213. Anal. Found: C, 75.85; H, 5.41; N, 3.28.
ꢁ
/
7.4 Hz, 6H,
7.5 Hz, 6H,
154.05,
Calc. for C52H48FeN2O4 (820.80): C, 76.09; H, 5.89; N,
3.41%.
ꢁ
/
/
153.44 (C-2 and C-5 in C6H2), 151.85 (C-2), 150.38 (C-
9), 145.93 (C-1a), 144.48 (C-10a), 137.44 (C-4), 135.92
(C-7), 128.94 (C-6a), 127.80 (C-4a), 127.16, 126.07 (C-5
and C-6), 123.12 (C-8), 119.96 (C-3, C12H7N2), 116.97,
116.38 (C-3 and C-6, C6H2), 115.68, 112.37 (C-1 and C-
4.2.3.2. 1,1?-Bis{[4-(2,2?-bipyridine-5-ylethynyl)-2,5-
dipropoxy-phenyl]ethynyl}ferrocene (6). Initial weight:
5-bromo-2,2?-bipyridine (700 mg, 3.0 mmol). Yield: 440
mg (45%), orange powder, m.p. 165 8C. 1H-NMR
4
5
(CDCl3): dꢁ
/
8.80 (dd, JHH
ꢁ
/
2.2, JHH
ꢁ
/
0.8 Hz, 2H,
4, C6H2), 92.73, 91.72, 90.87, 83.89 (C Å
/
C Ã
/
C6H2Ã
/
C Å
/
3
H-6), 8.67 (ddd, JHH
4
4.7, JHH
5
ꢁ
/
ꢁ/1.7, JHH
ꢁ
/
0.9 Hz
1.0, 5JHH
1.0
0.8 Hz, 2H,
C), 72.91 (C4H4C), 71.24 (OCH2CH2CH3), 71.05
(C4H4C), 71.02 (OCH2CH2CH3), 68.18 (C4H4C),
23.10 (OCH2CH2CH3), 23.07 (OCH2CH2CH3), 10.77
(OCH2CH2CH3), 10.75 (OCH2CH2CH3). FAB-MS
2H, H-6?), 8.40 (ddd, 3JHH
ꢁ
/
8.0, 4JHH
ꢁ
8.2, JHH
/
ꢁ
/
3
5
Hz 2H, H-3?), 8.37 (dd, JHH
ꢁ
/
ꢁ
/
3
H-3), 7.92 (dd, JHH
4
8.2, JHH
ꢁ
/
ꢁ2.2 Hz, 2H, H-4),
/

84
E. Lindner et al. / Journal of Organometallic Chemistry 660 (2002) 78ꢀ84
/
(NBA, 50 8C): m/z 1023.1 [Mꢂ]. IR (KBr, cmꢃ1):
[4] M. Buda, J. Moutet, E. Saint-Aman, A. De Cian, J. Fischer, R.
Ziessel, Inorg. Chem. 37 (1998) 4146.
n(CÅ
Calc. for C66H54FeN4O4×
H, 5.07; N, 5.18%.
/
C)ꢁ/2202. Anal. Found: C, 73.46; H, 5.45; N, 5.19.
[5] N. Sachsinger, C.D. Hall, J. Organomet. Chem. 531 (1997) 61.
[6] C.D. Hall, T. Truong, S.C. Nyburg, J. Organomet. Chem. 547
(1997) 281.
/
0.5CHCl3 (1082.71): C, 73.72;
[7] B. Konig, M. Nimtz, H. Zieg, Tetrahedron 51 (1995) 6267.
¨
[8] I.R. Butler, Organometallics 11 (1992) 74.
4.3. Crystallographic analysis
[9] I.R. Butler, J.L. Roustan, Can. J. Chem. 68 (1990) 2212.
[10] M. Schmittel, H. Ammon, C. Wohrle, Chem. Ber. 128 (1995) 845.
¨
Single crystals of compound 1 suitable for an X-ray
structure determination were obtained by slow evapora-
tion of a CH2Cl2 and MeOH (commercial product,
containing somewhat water) solution (1:1) at r.t. A red
crystal was transferred to a glass capillary and measured
on a Stoe IPDS diffractometer, using graphite-mono-
[11] J.D. Carr, S.J. Coles, M.B. Hursthouse, M.E. Light, E.L. Munro,
J.H.R. Tucker, J. Westwood, Organometallics 19 (2000) 3312.
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(2000) 1008.
[15] O. Lavastre, J. Plass, P. Bachmann, S. Guesmi, C. Moinet, P.H.
Dixneuf, Organometllics 16 (1997) 184.
chromated MoꢀKa radiation. The structure was solved
/
by direct methods with SHELXS [38] and refined by least-
squares methods based on F2 using SHELXL-97 [39]. The
non-hydrogen atoms were refined anisotropically and
the hydrogen atoms were included in calculated posi-
tions, except for the hydrogen atoms of the water
molecule. They were located in the difference electron
density map and refined isotropically.
[16] D. Osella, L. Milone, C. Nervi, M. Ravera, J. Organomet. Chem.
488 (1995) 1.
[17] J.V. Ortega, B. Hong, S. Ghosal, J.C. Hemminger, B. Breedlove,
C.P. Kubiak, Inorg. Chem. 38 (1999) 5102.
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(1997) 11191.
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Commun. (1994) 2655.
[20] J. Seth, V. Palaniappan, R.W. Wagner, T.E. Johnson, J.S.
Lindsey, D.F. Bocian, J. Am. Chem. Soc. 118 (1996) 11194.
[21] E. Lindner, R.F. Zong, K. Eichele, Phosphorus Sulfur Silicon 169
(2001) 219.
5. Supplementary material
Crystallographic data for the structure reported in
this paper have been deposited with the Cambridge
Crystallographic Data Center, CCDC no. 185968 for
ligand 1. Copies of the data may be obtained free of
charge on application to The Director, CCDC, 12
[22] W.M. Xue, F.E. Kuhn, E. Herdtweck, Q.C. Li, Eur. J. Inorg.
¨
Chem. (2001) 213.
[23] C.J. Kuehl, S.D. Huang, P.J. Stang, J. Am. Chem. Soc. 123 (2001)
9634.
[24] A. Khatyr, R. Ziessel, J. Org. Chem. 65 (2000) 7814.
[25] P.F.H. Schwab, F. Fleischer, J. Michl, J. Org. Chem. 67 (2002)
443.
Union Road, Cambridge, CB2 1EZ, UK (Fax: ꢂ44-
/
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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(1995) 3489.
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[28] M. Schmittel, C. Michel, A. Wiegrefe, V. Kalsani, Synthesis 10
(2001) 1561.
Acknowledgements
[29] P.J. Connors, D. Tzalis, Jr., A.L. Dunnick, Y. Tor, Inorg. Chem.
37 (1998) 1121.
Support of this research by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie is
gratefully acknowledged. The Degussa AG is thanked
for supplying starting materials. Dipl.-Chem. H.-P. Jing,
[30] K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett. 50
(1975) 4467.
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Institut fur Anorganische Chemie, Universitat Tubin-
¨
¨
¨
gen, is thanked for his help in checking the quality of the
single crystal used in this research.
¨
¨
Chem. Soc. 123 (2001) 5651.
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¨
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