Coordination chemistry of neutral quinolyl- and aminophenylcyclopentadiene derivatives

Article abstract of DOI:10.1016/S0022-328X(01)01290-6

The cyclopentadiene and indene derivatives 1-4 being functionalised by a dimethylaniline and quinolyl group, respectively, were treated with metal carbonyl complexes. Whereas cyclopentadienes (C₅R₅H) normally loose one hydrogen atom

Full text of DOI:10.1016/S0022-328X(01)01290-6

Journal of Organometallic Chemistry 641 (2002) 81–89
www.elsevier.com/locate/jorganchem
Coordination chemistry of neutral quinolyl- and
aminophenylcyclopentadiene derivatives
Markus Enders *, Pablo Ferna´ndez, Michael Kaschke, Gerald Kohl, Gunter Ludwig,
Hans Pritzkow, Ralph Rudolph
Anorganisch-Chemisches Institut der Uni6ersita¨t, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany
Received 6 June 2001; accepted 10 August 2001
Dedicated to Professor Rolf Gleiter on the occasion of his 65th birthday
Abstract
The cyclopentadiene and indene derivatives 1–4 being functionalised by a dimethylaniline and quinolyl group, respectively, were
treated with metal carbonyl complexes. Whereas cyclopentadienes (C5R5H) normally loose one hydrogen atom prior or during
metal complex formation, leading to negatively charged cyclopentadienide ligands, the compounds 1–4 are able to act as neutral
ligands without hydrogen loss. Consequently transition metal complexes with coordination of the nitrogen donor and a CꢀC
double bond of the five membered ring have been obtained. In some cases a hydrogen atom is eliminated and the expected
h5-(C5R5) complexes are formed. Reaction of Ru3(CO)12 with 2 leads to the binuclear h6-fulvene complex 8. The octahedral
molybdenum complex 9 and the square planar rhodium(I) complexes 10 and 11 which were obtained from Mo(CO)6 and
[Rh(CO)2Cl]2, respectively, are rare examples of h2-(C5R5H) coordination to metal atoms. © 2002 Elsevier Science B.V. All rights
reserved.
Keywords: N-functionalised cyclopentadienes; Olefin complexes; Carbonyl complexes
1. Introduction
reaction of Ru3(CO)12 with cyclopentadiene, a metal
hydride complex has been identified as an intermediate
compound [2]. Heating of pentabenzylcyclopentadiene
with Fe(CO)5 leads to the formation of two stable
products (h4-C5Bz5H)Fe(CO)3 as well as [(h5-
C5Bz5)Fe(CO)2]2 [3]. h2-Complexes of neutral cyclopen-
tadiene derivatives (C5R6) are very rare, only a handful
compounds have been investigated structurally [4,5].
In this paper, we present the novel synthesis and
molecular structures of metal complexes with function-
alised cyclopentadienes or indenes where two or four
carbon atoms of the five membered ring are interacting
with the metal atom.
Cyclopentadienide ligands, C5R−5 are known to build
stable complexes with most metals of the periodic table.
The preferred ligand properties are based on the ideal
geometry of the six electron p-system, paired with the
negative charge of the ligand. Due to the charge, an
additional stabilisation by electrostatic attraction be-
tween the metal centre and the ligand is achieved. As a
result, the coordination chemistry of anionic C5R5-sys-
tems is much more comprehensive compared to the
neutral cyclopentadienes (C5R5R%). However, com-
pounds of the type (h4-C5R5H)MLn are formed as
intermediates during the synthesis of some cyclopenta-
dienyl complexes.
(h4-C5H6)Fe(CO)3 is very reactive and converts ther-
mally to the dimer [(h5-C5H5)Fe(CO)2]2 [1]. During the
2. Results and discussion
Cyclopentadiene derivatives functionalised by a 8-
quinolyl group or a N,N-dimethylanilinyl group possess
a predefined geometry for the formation of chelate
complexes. A metal atom bound to the nitrogen donor
* Corresponding author. Tel.: +49-6221-562-452; fax: +49-6221-
545-609.
E-mail address: markus.enders@urz.uni-hd.de (M. Enders).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01290-6

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M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
is forced to be close to the butadiene-p-system of the
five membered ring. Therefore the interaction between
the metal atom and a CꢀC double bond becomes easier.
In order to study the coordination behaviour of neutral
substituted cyclopentadienes (C5R5H), the previously
reported ligands 1 [6] and 2 [7] and the new, function-
alised indenes 3 and 4 were treated with metal carbonyl
compounds Fe(CO)5, Ru3(CO)12, Mo(CO)6, or
[Rh(CO)2Cl]2. The syntheses of 3 and 4 are accom-
plished by reaction of 8-lithioquinoline with 1-indanone
and with 2-methyl-1-indanone, respectively. The novel
compounds are formed as single isomers, with the
quaternary carbon atom in the 3-position of the indene.
Therefore a CꢀH···N hydrogen bond which is present in
the cyclopentadienes 1 and 2 is not possible in 3 or 4
(Fig. 1, Scheme 1).
The reaction of Fe(CO)5 or Ru3(CO)12 with cy-
clopentadiene derivatives (C5R5H) normally leads to
the formation of h5-C5R5 metal complexes, although
sometimes h4-C5R5H complexes are isolated. The nitro-
gen functionalised cyclopentadiene derivative 1 (mix-
ture of the isomers 1a and 1b) was treated with Fe(CO)5
in boiling toluene for 48 h in order to obtain a binu-
clear complex comparable to [h5-C5H5Fe(CO)2]2. How-
ever, the IR-spectrum of the reaction mixture shows
three bands caused by a metal tricarbonyl fragment and
no signals for bridging CO groups are present. After
chromatographic workup, the orange coloured,
mononuclear complex 5 was isolated as the only
product in 45% yield, being stable at room temperature
for several weeks. The constitution is revealed by spec-
troscopic data, the mass spectrum shows the fragments
where one or two CO ligands are lost; the third CO
ligand is removed together with two hydrogen atoms
leading to the base peak at m/z=295. The NMR
spectra indicate that the ligand isomer 1b is incorpo-
rated in the complex leading to a molecule with an
average Cs symmetry in solution. The signal for the ring
Fig. 1. Amino substituted cyclopentadienes 1 and 2.
1
hydrogen atom is observed at l=4.79 in the H-NMR
spectrum. This value is about 2 ppm at lower field
compared to other (h4-C5R5H)Fe(CO)3 complexes (e.g.
l=2.72 for (h4-C5Bz5H)Fe(CO)3) [8b]. The explana-
tion for this 1H-NMR value is the proximity of the
N-lone pair of the amine substituent, leading to a
CꢀH···N hydrogen bond. We have observed similar
low-field NMR-values for the ligands 2a (l=4.00), 2b
(l=5.77) [7] and 1a (l=3.50) [6]. The three carbonyl
ligands result in one resonance in the 13C-NMR spec-
trum at l=214.0. Single crystals of 5 were grown from
toluene at −30 °C. The result of an X-ray analysis is
shown in Fig. 2.
Scheme 1. Preparation of the indene derivatives 3 and 4.
The iron atom is bound to four carbon atoms of the
C5R5H ring. The ring hydrogen atom H7 lies in an
endo position relative to the metal centre. The carbon
atoms C8, C9, C10 and C11 build a planar diene
system with nearly equidistant bond lengths (1.428–
,
1.437 A). This bond length equilibration is comparable
to other diene Fe(CO)3 complexes [8]. The nitrogen
atom of the dimethylamino group is close to the atom
H7 of the five-membered ring with a distance NꢀH7 of
,
2.38 A. This is considerably smaller than the sum of the
,
van der Waals radii (2.75 A), consequently the interac-
tion can be described as a CꢀH···N hydrogen bond [9].
Similar interactions were observed in the solid state
structures of 1a and 2a [6]. However, the orientation of
the dimethylamino group is not ideal for such an
interaction and the lone pair seems to point beside the
H7 atom (the plane defined by N1, C2 and H7 is not
bisecting the angle C16ꢀN1ꢀC17) (Scheme 2).
,
Fig. 2. Solid state structure of 5. Selected bond lengths (A) and angles
(°): FeꢀC8 2.143(2); FeꢀC9 2.071(2); FeꢀCCO 1.785(2)–1.794(2), CꢀO
1.143(3)–1.148(2); C7ꢀC8 1.529(2); C8ꢀC9 1.432(2); C9ꢀC10 1.428(3);
C10ꢀC11 1.437(2); C11ꢀC7 1.529(2); C7ꢀC1 1.534(2); C7ꢀH7 0.97(2);
N1ꢀH7 2.38; CCOꢀFeꢀCCO 93.1(1)ꢀ102.3(1).

M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
83
Scheme 2. Formation of the iron complexes 5 and 6 with the ligand 1. The quinolyl substituted derivative 2 leads directly to the binuclear complex
7 (analogue to 6).
,
Fig. 3. Solid state structure of 6. Selected bond lengths (A) and angles (°): FeꢀCCp 2.108(1)–2.162(1); FeꢀC19 1.758(2), FeꢀC20 1.928(1), C19ꢀO1
1.143(2), C20ꢀO2 1.180(2), FeꢀFe 2.562(1), CCpꢀCCp 1.426(2)ꢀ1.438(2), C19ꢀFeꢀC20 95.69(6), FeꢀC20ꢀFe 83.28(6), C20ꢀFeꢀC20a 96.72(6),
C19ꢀFeꢀC20a 93.31(6).
with the quinoline functionalised cyclopentadiene 2, a
solution of Fe(CO)5 and 2 in n-heptane was heated to
reflux for 40 h. However, no h4-complex comparable to
5 could be identified. The IR-spectrum shows that the
binuclear compound 7 with bridging CO ligands was
formed directly.
Treatment of 2 with Ru3(CO)12 takes a different
course. A mixture of products formed and analysis by
FD-mass spectrometry revealed the presence of several
bi and trinuclear ruthenium compounds. Purification by
chromatography led to the isolation of the binuclear
complex 8 in 34% yield (Scheme 3).
Brown crystals of the ruthenium compound 8, suit-
able for X-ray diffraction, have been obtained from
toluene at room temperature. The result is shown in
Fig. 4. The former ligand 2 has lost two hydrogen
atoms, one from the cyclopentadiene ring, another from
a CH3 group. The resulting fulvene derivative is coordi-
nated to a diruthenium unit via six carbon atoms and
the nitrogen atom of the quinoline moiety. The bond
Compound 5 is thermally stable and does not convert
to the binuclear complex 6. The derivative (h4-
C5H6)Fe(CO)3, is very reactive and converts thermally
or upon exposure to air to the dimer [(h5-
C5H5)Fe(CO)2]2 [1]. In order to eliminate CO-ligands, a
n-hexane solution of 5 was irradiated with UV-light.
After 24 h small red–brown plates precipitated. The
IR-spectrum indicates the formation of the new com-
pound 6 with terminal and bridging CO ligands. The
mass spectrum reveals the molecular ion of 6 at m/z=
704. Therefore 6 is a binuclear compound analogous to
[h5-C5H5Fe(CO)2]2. The solid state structure of 6 is
shown in Fig. 3.
The arrangement of the ligands and the distances in
6 compared to [h5-C5Me5Fe(CO)2]2 are very similar
[10]. The dimethylaniline substituents are located in
trans positions, the molecule displays a centre of sym-
metry in the middle of the iron–iron bond.
In order to compare the coordination behaviour of
the N,N-dimethylaniline substituted cyclopentadiene 1

84
M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
Scheme 3. Formation of the binuclear compounds 7 and 8.
lengths in the fulvene framework are nearly equalised
Treatment of [Rh(CO)2Cl]2 with the indene ligand 4
as well as with the cyclopentadiene 2 in diethylether at
room temperature lead to the precipitation of the new
complexes 10 and 11, respectively, as yellow powders.
After crystallisation from dichloromethane–hexane so-
lutions, the structures have been revealed by X-ray
diffraction (see Figs. 6 and 7). In both cases one CꢀC
double bond and the nitrogen atom of the quinoline are
bound to the rhodium atom which is itself in a square
planar environment. The geometry of both compounds
is very similar. The coordination of the nitrogen atom
,
(1.47–1.43 A) and the six carbon atoms lie in a plane
,
(max. deviation C12 0.05 A). The geometry of the
ligand allows the coordination of the quinoline nitrogen
atom to the second ruthenium atom, which is octahe-
drally surrounded by three CO ligands, one ruthenium
atom, the CH2-group of the fulvene and the nitrogen
atom. The deviations from an ideal octahedral arrange-
ment are small and all angles at Ru2 are within a range
of 82.1°–104.6°. A few cases of fulvene coordination to
a diruthenium unit have been reported [11]. However,
the formation of a fulvene complex from a cyclopenta-
diene derivative is unexpected. This reactivity is caused
by the predefined, rigid geometry of 2. When the quin-
oline nitrogen atom is bound to the metal centre, the
cyclopentadiene must be close to the metal complex
fragment and is therefore easily coordinated.
,
with a distance RhꢀN of 2.105(1) and 2.103(4) A brings
the CꢀC double bond of the ligand 2 or 4 in an ideal
position for an interaction with the rhodium metal.
Because of strong interactions of the olefin-p-systems
with the rhodium atoms, the CꢀC double bond lengths
The reactions described so far show, that the func-
tionalised cyclopentadiene 1 may serve as a neutral
ligand (compound 5). However, 1 as well as 2 readily
lose hydrogen, leading to h5-complexes. In order to
favour h2-coordination it is suitable to embed the sec-
ond CꢀC double bond of the cyclopentadiene moiety
into an aromatic system. Consequently the novel, func-
tionalised indenes 3 and 4 were used as ligands and
were treated with metal carbonyl complexes. Reaction
of Mo(CO)6 with 3 leads to the formation of the new
complex 9 (Fig. 5) where a molybdenum atom is octa-
hedrally surrounded by four CO-ligands, one nitrogen
atom and a CꢀC double bond. The maximum deforma-
tion of the bonding angles around the central atom is
only 7° with respect to the ideal 90°. The ring systems
,
are almost planar with maximum deviations of 0.028 A
,
in the indene and 0.072 A in the quinoline system. The
,
Fig. 4. Solid state structure of 8. Selected bond lengths (A) and angles
(°): C9ꢀC11 1.470(6), C11ꢀC12 1.471(6), C12ꢀC13 1.439(7), C13ꢀC14
1.428(6), C14ꢀC15 1.434(7), C15ꢀC11 1.452(6), C12ꢀC16 1.453(6),
Ru1ꢀCCp 2.226(4)–2.312(4), Ru1ꢀCCO 1.859(5), 1.866(5), Ru1ꢀRu2
2.875(1), Ru2ꢀN1 2.252(4), Ru2ꢀC16 2.193(5), Ru2ꢀC22 1.875(5),
Ru2ꢀC23 1.950(5), Ru2ꢀC24 1.929(5), C21ꢀRu1ꢀC20 89.0(2),
N1ꢀRu2ꢀC16 86.6(2), C16ꢀRu2ꢀC22 93.0(2), Ru1ꢀRu2ꢀC16 82.1(1),
Ru1ꢀRu2ꢀC22 82.9(1).
interplanar angle is 50.0°. The CꢀC double bond
C11ꢀC12 is slightly lengthened (1.396(5) A) because of
the interaction with the molybdenum metal. Experi-
ments to transform the h2-indene complex 9 into a
h5-indenyl derivative by prolonged heating, by irradia-
tion or by deprotonation proved unsuccessful.
,

M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
85
lies in endo position relative to Rh1. A possible second
isomer (H11 endo, C15 exo related to rhodium) was
never observed in solution or in the solid state, al-
though it should have a similar or somewhat higher
thermodynamic stability compared to 11. Therefore the
formation of isomer 11 by reaction of the ligand 2a
with [Rh(CO)2Cl]2 must be controlled kinetically and is
a consequence of the preferred conformation of 2a with
a CꢀH···N hydrogen bridge [6].
To our knowledge the compounds 10 and 11 are the
first examples of h2-indene or h2-cyclopentadiene com-
plexes of rhodium which have been characterised by
X-ray diffraction.
3. Conclusions
The donor functionalised cyclopentadiene and indene
derivatives 2–4 are able to act as neutral two electron
p-ligands with additional coordination of the nitrogen
donor. With ligand 1 no h2-coordination was observed,
but the h4-iron complex 5 has been isolated, in which
the nitrogen group is not interacting with the metal
atom. The cyclopentadiene derivatives 1 and 2 may lose
the ring hydrogen atom during complexation reaction
leading to the usual h5-coordinated C5R5-metal com-
plexes. Hydrogen loss is of course more difficult in the
indene derivatives 3 and 4. As a result, we always
obtained h2-coordinated metal complexes with indene
derivatives. However, h5-coordination with function-
alised indenyl derivatives is possible when the ligands
are deprotonated prior to the reaction with metal com-
plex fragments [12,13]. In the rhodium complex 11 the
cyclopentadiene derivative 2 acts as a two p-electron
ligand via a CꢀC double bond. This coordination mode
is very unusual in cyclopentadiene chemistry and only a
few examples are known in the literature, mainly in
binuclear complexes [4,5].
,
Fig. 5. Solid state structure of 9. Selected bond lengths (A) and angles
(°): C11ꢀC12 1.396(5), C12ꢀC13 1.523(5), C13ꢀC14 1.504(5),
C14ꢀC15 1.402(5), C15ꢀC11 1.483(5), C9ꢀC11 1.490(5), Mo1ꢀC12
2.460(4), Mo1ꢀC11 2.489(4), Mo1ꢀC20 1.967(4), Mo1ꢀC21 1.972(4),
Mo1ꢀC22 2.034(4), C20ꢀO1 1.161(4), C21ꢀO2 1.155(5), C22ꢀO3
1.149(4), C23ꢀO4 1.138(5), N1ꢀMo1ꢀC21 95.9(2), N1ꢀMo1ꢀC22
95.0(1), N1ꢀMo1ꢀC23 93.8(2), N1ꢀMo1ꢀC20 173.1(1).
,
Fig. 6. Solid state structure of 10. Selected bond lengths (A) and
angles (°): C1ꢀC10 1.485(2), C10ꢀC11 1.431(2), C11ꢀC12 1.530(2),
C12ꢀC13 1.505(2), C13ꢀC14 1.404(2), C14ꢀC10 1.486(2), Rh1ꢀN1
2.105(1), Rh1ꢀCl1 2.349(1), Rh1ꢀC10 2.157(2), Rh1ꢀC11 2.157(2),
Rh1ꢀC20 1.841(2), C20ꢀO1 1.141(2), N1ꢀRh1ꢀCl1 90.9(1),
Cl1ꢀRh1ꢀC20 87.2(1), Rh1ꢀC20ꢀO1 177.6(2).
,
,
are raised to 1.431(2) A (10) and 1.428(6) A (11),
respectively. The CO acceptor ligands lie in trans posi-
tions relative to the quinoline nitrogen atoms. The
quinoline rings as well as the indene and the cyclopen-
tadiene are almost planar (max. deviation from the best
,
Fig. 7. Solid state structure of 11. Selected bond lengths (A) and
angles (°): C1ꢀC10 1.487(6), C10ꢀC11 1.517(6), C11ꢀC12 1.520(6),
C12ꢀC13 1.337(6), C13ꢀC14 1.490(7), C14ꢀC10 1.428(6), Rh1ꢀN1
2.103(4), Rh1ꢀCl1 2.353(1), Rh1ꢀC10 2.164(4), Rh1ꢀC14 2.191(4),
Rh1ꢀC19 1.841(5), C19ꢀO1 1.139(6), N1ꢀRh1ꢀCl1 91.3(1),
Cl1ꢀRh1ꢀC19 86.4(2), Rh1ꢀC19ꢀO1 175.9(5).
,
plane 0.06 A). The interplanar angles are 58.0° (10) and
55.0° (11). In compound 11 the atom C15 (CH3 group)

86
M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
4. Experimental
4.1. General remarks
88.86, H 5.39, N 5.75. Found: C 87.55, H 5.52, N
5.92%.
4.3. 1-(8-Quinolyl)-2-methyl-indene (4)
All experiments were carried out under an atmo-
sphere of dry nitrogen. Solvents were dried by using
standard procedures and distilled prior to use. The
following compounds were prepared according to liter-
ature procedures: 1-(2-N,N-dimethylaminophenyl)-
2,3,4,5,-tetramethyl-cyclopentadiene (1) [6], 2,3,4,5-
tetramethyl-1-(8-quinolyl)-cyclopentadiene (2) [7], 8-
bromoquinoline [14], tetracarbonyldi-m-chlorodirhodi-
um(I) [15]. All other reagents were used as purchased.
NMR: Bruker AC 200 and Bruker DRX 200 (200.13
and 50.32 MHz for 1H and 13C, respectively), the
1H-NMR spectra were calibrated using signals of resid-
ual protons from the solvent referenced to SiMe4. The
13C spectral chemical shifts are reported relative to the
13C triplet of the deuterated solvent (CDCl3: 77.0 ppm,
C6D6: 128.0 ppm). IR: Bruker IFS 28. MS: VG Micro-
mass 7070 H, Finnigan MAT 8230 and JEOL JMS-700.
The procedure was repeated in an analogous manner
to 3. Scale: 3.50 g (16.8 mmol) of 8-bromoquinoline,
6.70 ml (16.8 mmol) of a 2.5 M solution of n-BuLi in
hexane, 2.45 g (16.8 mmol) of 2-methyl-1-indanone.
The purification of the resulting crude oil is achieved by
distillation. The ligand 4 was obtained as the third
fraction of the distillation at 150–160 °C/10−2 mbar as
a yellow viscous oil, yield 1.50 g (5.8 mmol, 35%).
2
1H-NMR (CDCl3): l=2.07 (CH3); 3.52 (d, J(H,H)=
22.6 Hz, 1H, CH2) 3.73 (d, 2J(H,H)=22.6 Hz, 1H,
CH2); 6.79–6.89 (m, 1H, Haromat.); 7.10–7.18 (m, 2H,
Haromat.); 7.38–7.50 (m, 2H, Haromat.); 7.58–7.75 (m,
3
4
2H, Haromat.); 7.88 (dd, J(H,H)=7.6 Hz, J(H,H)=
3
2.2 Hz, 1H, Haromat.); 8.24 (dd, 1 H, J(H,H)=8.3 Hz,
4J(H,H)=1.8 Hz, Haromat.); 8.93 (dd, J(H2,H3)=4.3
3
Hz, 4J(H2,H4)=1.8 Hz, 1H, H2). 13C{1H}-NMR
(CDCl3): l=15.3 (Cp CH3); 43.3 (CH2); 119.8, 121.0,
123.2, 123.7, 125.8, 126.3, 127.6, 131.0, 136.4, 150.0
(CHaromat.); 128.7, 135.2, 137.2, 142.2, 142.6, 146.7,
147.4 (quart. Caromat.). EIMS; m/z (%): 257 (100) [M+],
242 (44) [M+−CH3], 130 (17) [C10H1+0].
4.2. 1-(8-Quinolyl)-indene (3)
A solution of 10.4 g (50 mmol) of 8-bromoquinoline
in 100 ml of THF was cooled to −100 °C and 20 ml
of a 2.5 M solution of n-butyllithium in hexane (50
mmol) was added with stirring within 15 min. After
stirring for another 15 min at −80 °C, a solution of
6.6 g (50 mmol) of 1-indanone in 30 ml of THF was
added dropwise. The mixture was allowed to warm to
room temperature (r.t.) and was then heated at reflux
for 3 h. After cooling down, some ice and HCl were
added up to pH 1, and the mixture was stirred for 30
min. After separation of the phases the aqueous one
was subsequently alkalised with aqueous NH3 up to pH
9 and extracted with diethylether. The combined or-
ganic layers were evaporated to dryness in vacuum. The
crude product was treated with concentrated HCl up to
pH 0 and was then heated at reflux for 2 h. After
neutralisation with aqueous NH3, extraction of the
aqueous layer with diethylether and evaporation of the
solvent, 3 was obtained as a white solid, yield 6.6 g (27
4.4. Tricarbonyl[p4-1-(2-N,N-dimethylaminophenyl)-
2,3,4,5-tetramethylcyclopentadiene]iron (5)
A solution of 0.40 g (1.66 mmol) of 1 and 0.32 g
(1.63 mmol) of Fe(CO)5 was refluxed for 16 h. The
resulting orange–red solution was cooled to r.t., con-
centrated and purified by column chromatography on
Al2O3–5% H2O using toluene as eluent. The resulting
red brown main fraction was concentrated in vacuum
and cooled to −30 °C. Orange red crystals of 5 (0.28
g, 0.73 mmol, 45%) were formed, which were suited for
X-ray crystallographic studies, m.p. 73 °C. IR (hexane)
1
w˜(CO) (cm−1)=1952 (s), 1961 (s), 2032 (s). H-NMR
(CDCl3): l=1.34 (s, 6H, Cp CH3); 1.83 (s, 6H, Cp
CH3); 2.41 (s, 6H, N CH3); 4.79 (s, 1H, Cp H); 6.64 (d,
3J=7.5 Hz, 1H, Haromat.); 6.99–7.10 (m, 2H, Haromat.);
7.27–7.38 (m, 1H, Haromat.). 13C{1H}-NMR (CDCl3):
l=14.5, 14.8 (Cp CH3); 45.6 (N CH3); 64.7, 74.0, 101.3
(quart. CCp); 117.6, 121.6, 125.0, 126.0, 139.0, 153.0
(Caromat.); 214.0 (CO). EIMS; m/z (%): 353 (35) [M+−
CO], 325 (8) [M+−2CO], 295 (100) [M+−3CO−2H],
280 (11) [M+−3CO−2H−CH3], 241 (7) [1+], 28 (6)
[CO+].
1
mmol, 55%), m.p. 108 °C. H-NMR (CDCl3): l=3.69
3
3
(d, J(H,H)=2.0 Hz, 2H, CH2); 6.80 (t, J(H,H)=2.0
Hz, 1H, CH); 7.12–7.26 (m, 3H); 7.41 (dd,
3J(H2,H3)=4.2 Hz, 3J(H3,H4)=8.3 Hz, 1H, H3); 7.55–
7.64 (m, 2H); 7.81–7.88 (m, 2H); 8.21 (dd, 3J(H3,H4)=
8.3 Hz, 4J(H2,H4)=1.8 Hz, 1H, H4); 8.92 (dd,
3J(H2,H3)=4.2 Hz, 4J(H2,H4)=1.8 Hz, 1H, H2).
13C{1H}-NMR (CDCl3): l=38.8 (CH2); 121.0, 121.2,
123.8, 124.5, 125.8, 126.3, 127.8, 130.0, 133.5, 136.1,
150.0 (CH); 128.6, 135.9, 143.7, 144.0, 145.6, 146.7
(quart. C). EIMS; m/z (%): 243 (65) [M+], 242 (100)
[M+−H]. EIHRMS: Calc. for C18H13N: 243.1048;
Found: 243.1038. Anal. Calc. C18H13N (243.31): C
4.5 Bis{dicarbonyl-p5-[1-(2-N,N-dimethylamino-
phenyl)-2,3,4,5-tetramethylcyclopentadienyl]iron} (6)
A solution of 130 mg (0.34 mmol) of 5 in 50 ml of
hexane was irradiated (150 W high-pressure mercury

M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
87
lamp). After 24 h brown crystals precipitated. The
solution was removed with a syringe and the crystals
dried in vacuum; yield 70 mg (0.10 mmol, 59%) of 6,
m.p. 277 °C. IR (CH2Cl2) w˜(CO) (cm−1): 1923.0 (s);
mmol) of Mo(CO)6 in 50 ml of toluene was refluxed for
16 h. The resulting orange solution was cooled to r.t.
and concentrated in vacuum. Cooling to −30 °C re-
sulted 684 mg (1.52 mmol, 37%) of 9 as small yellow–
orange crystals, m.p. 180 °C (decomposition). IR
(toluene) w˜(CO) (hexane) (cm−1): 1880.3 (m), 1931.6
1
1762.1 (s). H-NMR (CDCl3): l=1.70 (s, 12 Cp CH3),
1.93 (s, 12 Cp CH3); 2.57 (s, 12 H, N CH3); 7.10 (t,
3J(H, H)=7.9 Hz, 4H, Haromat.); 7.32–7.37 (m, 4H,
Haromat.); 7.66–7.71 (m, 2H, Haromat.). 13C{1H}-NMR
(CD2Cl2): l=8.0, 9.2 (Cp CH3); 41.9 (N CH3); 92.9,
101.1, 116.9, 120.8, 128.1, 133.1 (CHaromat.). EIMS; m/z
(%): 704 (6) [M+]; 592 (2) [M+−2CO−Fe]; 536 (1)
[(1ꢀH)2Fe+]; 352 (20) [1Fe(CO)+2 ]; 324 (37) [1FeCO+];
294 [100, (1ꢀH)FeꢀH+]. Anal. Calc. C38H44N2O4Fe2
(704.47): C 64.72, H 6.30, N 3.98. Found: C 64.13, H
6.32, N 3.92%.
1
(s), 2028.1 (m). H-NMR (CD2Cl2): l=3.84 (m, 2H,
3
3
CH2); 5.82 (dd, J(H,H)=1.6 Hz, J(H,H)=2.4 Hz,
1H, CH); 7.24–7.33 (m, 2H, Haromat.); 7.38–7.46 (m,
2H, Haromat.); 7.56 (dd, 3J(H5,H6)=7.2 Hz,
3
3J(H6,H7)=8.2 Hz, 1H, H6); 7.69 (dd, J(H6,H7)=8.2
4
Hz, J(H5,H7)=1.5 Hz, 1H, H7); 7.94–8.01 (m, 2H,
3
4
Haromat.); 8.20 (dd, J(H3,H4)=8.2 Hz, J(H2,H4)=1.6
Hz, 1H, H4); 8.77 (dd, 3J(H2,H3)=4.8 Hz, 4J(H2,H4)=
1.6 Hz, 1H, H2). 13C {1H}-NMR (CD2Cl2): l=43.2
(CH2); 94.7, 121.1, 122.0, 125.3, 126.8, 126.9, 127.1,
127.5, 127.9, 138.2, 154.2 (CH); 110.3, 129.7, 138.8,
143.2, 145.4, 149.8 (quart. C); 209.5, 213.2, 218.1, 221.8
(CO). FDMS; m/z (%): 453 (100) [M+]; 243 (15) [3+].
FDHRMS: Calc. for C22H13NO4Mo: 452.9899; Found:
452.9957. Anal. Calc. C22H13NO4Mo (451.29): C 58.56,
H 2.90, N 3.10; Found: C 58.38, H 2.97, N 3.00%.
4.6. Bis{dicarbonyl-p5-[1-(8-quinolyl)-
2,3,4,5-tetramethylcyclopentadienyl]iron} (7)
A solution of 0.272 mg (1.09 mmol) of 2 and 380 mg
(1.94 mmol) of ironpentacarbonyl in 50 ml of n-hep-
tane was heated at reflux for 40 h. After cooling to r.t.
a violet precipitate of 7 formed and was collected by
filtration. Isolated yield 259 mg (0.36 mmol, 66%). IR
(toluene) w˜(CO) (cm−1): 1760.7 (s), 1922.6 (s). 1H-
NMR (C6D6): l=1.69 (s, 6H, CH3), 1.72 (s, 6H, CH3),
6.72 (m, 1H), 7.45 (m, 2H), 7.54 (m, 1H), 8.55 (m, 1H),
8.75 (m, 1H). EIMS; m/z (%): 720 (0.7) [M+], 662 (0.9)
[M+−2CO], 552 (45) [Fe(2ꢀH)+2 ], 304 (100) [Fe(2ꢀH)+].
4.9. Carbonylchloro-1,2-p2-[1-(8-quinolyl)-2-methyl-
indene]rhodium(I) (10)
A total of 220 mg (0.57 mmol) of tetracarbonyldi-m-
chlorodirhodium(I) was added to a solution of 300 mg
(1.17 mmol) of 4 in 30 ml of diethylether. A yellow
precipitate was formed immediately. The resulting sus-
pension was stirred for 16 h at r.t. and then suction
filtered through a frit. The collected yellow solid was
washed two times with 5 ml of diethylether and dried in
vacuum; yield 290 mg (0.68 mmol, 58%), m.p. 254 °C
(decomposition). IR (THF) w˜(CO) (cm−1): 2020 (vs,
4.7. Binuclear rutheniumcomplex 8
A mixture of 900 mg (4.2 mmol) of Ru3(CO)12 and
631 mg (2.5 mmol) of 2 in 70 mg of toluene was heated
at reflux for 16 h, the resulting solution was purified by
column chromatography on Al2O3–5% H2O using tolu-
ene as eluent. The solution was concentrated and 8
crystallised at r.t.: Yield: 423 mg (0.7 mmol, 34%). IR
(toluene) w˜(CO) (cm−1): 1903 (s), 1962 (s), 1977 (s),
1
wCꢁO). H-NMR (CDCl3): l=1.70 (s, 3H, CH3); 3.35
2
2
(d, J(H,H)=21.4 Hz, 1H, CH2), 3.74 (d, J(H,H)=
21.4 Hz, 1H, CH2); 7.30–7.38 (m, 3H, Haromat.); 7.55
1
2046 (s). H-NMR (C6D6): l 1.48 (s, 3H, CH3); 1.89 (s,
(dd, J(H3,H2)=5.0 Hz, J(H3,H4)=8.3 Hz, 1H, H3);
7.67 (dd, 3J(H,H)=7.2, 3J(H,H)=8.2 Hz, 1H, H6);
7.80–7.94 (m, 3H, Haromat.); 8.37 (dd, 3J(H,H)=8.4
Hz, 4J(H,H)=1.5 Hz, 1H, Haromat.); 9.29 (dd,
3J(H2,H3)=5.0 Hz, 4J(H2,H4)=1.2 Hz, 1H, H2).
13C{1H}-NMR (CDCl3): l=22.3 (CH3); 51.2 (CH2);
3
3
3
3H, CH3); 2.19 (s, 3H, CH3); 5.98 (dd, J(H3,H2)=5.4
3
3
Hz, J(H3,H4)=8.1 Hz, 1H, H3); 6.78 (dd, J(H,H)=
7.1 Hz, 3J(H,H)=8.1 Hz, 1H, H6); 6.91 (dd,
3J(H,H)=8.0 Hz, J(H,H)=1.8 Hz, 1H, Haromat.); 7.01
4
3
4
(dd, J(H,H)=8.0 Hz, J(H,H)=1.7 Hz, 1H, Haromat.);
7.10–7.16 (m, 1H, Haromat.); 9.07 (dd, J(H2,H3)=5.2
3
1
87.7 (d, J(Rh,C)=14.0 Hz, quart. Cindenyl); 93.2 (d,
Hz, 4J(H2,H4)=1.7 Hz, 1H, H2). 13C{1H}-NMR
(C6D6): l= −4.4 (CH2); 9.5, 11.7, 13.1 (CH3); 82.4,
88.1, 95.5, 99.1, 101.6 (quart. CCp); 119.5, 125.9, 129.7,
134.0, 139.8, 158.2 (CHquinoline); 189.1, 198.5, 209.5,
212.0 (CO). FDMS; m/z (%): 591 (100) [M+].
1J(Rh,C)=13.0 Hz, quart. Cindenyl); 121.6, 122.1 (d,
J=1.0 Hz), 125.1, 126.3, 126.9, 127.1, 128.0, 128.1,
138.6, 150.4 (CHaromat.); 129.0, 137.7, 141.1, 148.3 (d,
J=1.5 Hz), 149.9 (d, J=1.0 Hz) (quart. Caromat.); 184.6
1
(d, J(Rh,C)=74.0 Hz, CO). EIMS; m/z (%): 423 (14)
[M+], 395 (4) [M+−CO], 359 (100) [M+−CO−Cl],
257 (36) [4+], 242 (10) [4+ꢀCH3], 127 (11) [C9H5N+].
Anal. Calc. C20H15ClNORh (423.70): C 56.70, H 3.57,
N 3.31; Found C 56.74, H 3.83, N 3.39%.
4.8. Tetracarbonyl[p2-1-(8-quinolyl)indene]molybdenum
(9)
A solution of 1.0 g (4.1 mmol) of 3 and 1.1 g (4.1

88
M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
4.10. Carbonylchloro-1,2-p2-(1-(8-quinolyl)-2,3,4,5-
tetramethylcyclopenta-1,3-diene)rhodium(I) (11)
H3); 7.57–7.65 (m, 1H, H6); 7.69–7.75 (m, 2H, H5, H7);
3
4
8.27 (dd, J(H4,H3)=8.3 Hz, J(H4,H2)=1.6 Hz, 1H,
H4); 9.21 (ddd, 3J(H2,H3)=5.0 Hz, 3J(H2,H4)=1.5 Hz,
3J(H2,Rh)=1.1 Hz, 1H, H2). 13C{1H}-NMR (CDCl3):
A total of 170 mg (0.87 mmol) of 2 was added to a
solution of 218 mg (0.44 mmol) of tetracarbonyldi-m-
chlorodirhodium(I) in 20 ml of diethylether. After 6 h
of stirring a bright yellow precipitate formed and was
separated from the solution by filtration, washed two
times with 5 ml of diethylether and dried in vacuum;
yield 190 mg (0.46 mmol, 53%) of 11, m.p. 176 °C
(decomposition). IR (toluene) w˜(CO) (cm−1): 2016 (vs).
2
l=10.9, 11.5, 14.4 (CH3); 18.6 (d, J(Rh,C)=2.3 Hz,
1
CH3); 49.8 (CHCp); 95.8 (d, J(Rh,C)=11.9 Hz, quart.
1
CCp); 96.9 (d, J(Rh,C)=16.9 Hz, quart. CCp); 121.9,
125.5, 127.4, 128.2, 138.4, 150.0 (CHquinoline); 128.8,
139.0, 140.3, 144.1, 149.4 (quart. C); 184.3 (d,
1J(Rh,C)=74.0 Hz, CO). EIMS; m/z (%): 387 (26)
[M+−CO]; 372 (26) [M+−CO−CH3], 351 (17) [M+
−CO−HCl], 336 (19) [M+−CO−HCl−CH3], 249
(11) [HCpQ+], 175.5 (71), [M2+ −CO−HCl], 167 (23),
154 (15), 129 (18) [C9H7N+], 36 (17) [HCl+], 28 (100)
[CO+]. Anal. Calc. C19H19ClNORh (415,73): C 54.89,
H 4.61, N 3.37. Found C 54.34, H 4.63, N 3.29%.
3
1H-NMR (CDCl3): l=1.40 (d, J(Rh,H)=0.8 Hz, 3H,
3
CH3); 1.61 (d, J(H,H)=7.5 Hz, 3H, CH3); 1.69 (m,
5J(H,H)=1.0 Hz, 3H, CH3); 1.96 (m, 5J(H,H)=1.0
3
Hz, 3H, CH3); 3.22 (q, J(H,H)=7.6 Hz, 1H, CHCp);
3
3
7.46 (dd, J(H3,H2)=5.0 Hz, J(H3,H4)=8.3 Hz, 1H,
Table 1
Crystal data and structure refinement details for 5, 6, 8, 9, 10, 11
5
6
8
9
10
11
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
Unit cell dimensions
C20H23FeNO3
381.24
203
C38H44Fe2N2O4
704.45
173
C23H17NO5Ru2
589.52
203
Monoclinic
P2(1)/a
C
451.27
203
Monoclinic
P2(1)/n
22H13MoNO4 C20H15ClNORh
C19H19ClNORh
415.71
203
Monoclinic
P2(1)/c
423.69
173
Triclinic
Triclinic
Triclinic
(
(
(
P1
P1
P1
,
a (A)
8.006(4)
10.706(5)
11.893(6)
77.11(3)
85.07(3)
80.02(3)
977.5(8)
2
8.7334(1)
9.0432(1)
12.5867(2)
69.811(1)
82.044(1)
61.964(1)
823.17(2)
1
9.731(5)
14.572(7)
14.913(8)
90
92.66(3)
90
2112(2)
4
1.854
1.465
7.207(7)
16.327(16)
15.803(16)
90
96.63(8)
90
1847(3)
4
1.623
8.2253(1)
8.5890(1)
13.0312(2)
101.873(1)
99.484(1)
108.593(1)
827.14(2)
2
8.562(4)
13.613(7)
14.721(7)
90
94.83(3)
90
1709(1)
4
1.615
1.158
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Dcalc (g cm−3
Absorption coefficient
(mm−1
F(000)
)
1.295
0.788
1.421
0.925
1.701
1.199
0.739
)
400
370
1160
904
424
840
Crystal size (mm)
Theta range for data
collection (°)
0.60×0.55×0.25 0.53×0.28×0.10
0.40×0.40×0.40 0.6×0.25×0.20 0.38×0.22×0.18
0.50×0.50×0.08
2.04–28.00°
1.76–33.00°
1.72–28.28°
1.95–30.00°
1.80–25.00°
1.65–28.30°
Index ranges
−125h59,
−155k516,
05l518
6631
−115h511,
−105k511,
05l516
−135h513,
05k520,
05l520
6136
−85h58,
05k519,
05l518
3254
−105h510,
−115k511,
05l517
−115h511,
05k517,
05l519
4128
Reflections collected
11 070
12 131
Independent reflections
6631
4012
6136
3254
4007
4128
[Rint=0.025]
[Rint=0.0291]
Absorption correction
Psi-scan
Semi-empirical from None
equivalents
Psi-scan
Semi-empirical from Psi-scan
equivalents
Max./min. transmission
1.000, 0.914
0.862, 0.757
4012/0/296
1.074
0.999, 0.845
3254/0/305
1.033
0.8621, 0.7319
4007/0/277
1.064
1.000, 0.597
4128/0/285
1.026
Data/restraints/parameters 6631/0/318
6136/0/317
1.045
Goodness-of-fit on F2
1.026
Final R indices [I\2|(I)] R1=0.0403,
wR2=0.1020
R1=0.0288,
wR2=0.0769
R1=0.0329,
wR2=0.0785
0.435 and
−0.189
R1=0.0458,
wR2=0.1146
R1=0.0692,
wR2=0.1259
0.729 and
−1.617
R1=0.0336,
wR2=0.0805
R1=0.0449,
wR2=0.0858
0.337 and
−0.870
R1=0.0210,
wR2=0.0555
R1=0.0220,
wR2=0.0561
0.694 and
R1=0.0432,
wR2=0.1050
R1=0.0747,
wR2=0.1167
1.079 and
−0.551
R indices (all data)
R1=0.0591,
wR2=0.1101
0.348 and
−0.456
Largest differential peak
−3
,
and hole (e A
)
−0.374

M. Enders et al. / Journal of Organometallic Chemistry 641 (2002) 81–89
89
[2] A.P. Humphries, S.A.R. Knox, J. Chem. Soc. Chem. Commun.
(1973) 326.
5. Crystal structure determinations of 5, 6, 8, 9, 10, 11
[3] W.M. Tsai, M.D. Rausch, R.D. Rogers, Organometetallics 15
(1996) 2591.
Crystal data are compiled in Table 1. Intensity data
were collected for 5, 8, 9, and 11 on a Siemens–Stoe
AED2 diffractometer (Mo–Ka radiation, ꢀ-scan, T=
−70 °C) and for 6 and 10 on a Bruker AXS CCD area
detector (Mo–Ka radiation, ꢀ-scan, T= −100 °C).
The structures were solved by direct methods [16] and
refined by least-squares methods based on F2 using all
measured reflections with anisotropic temperature fac-
tors for all non-hydrogen atoms [16]. Hydrogen atoms
were located in difference Fourier maps and refined
isotropically, except those of the methyl groups in 8,
which were treated as part of a rigid group.
[4] Mononuclear h2-cyclopentadiene complexes, investigated by X-
ray crystallography: (a) A.L. Rheingold, G. Wu, R.F. Heck,
Inorg. Chim. Acta, 131 (1987) 147;
(b) T. Hosokawa, C. Calvo, H.B. Lee, P.M. Maitlis, J. Am.
Chem. Soc. 95 (1973) 4914.
[5] Binuclear h2,h2-cyclopentadiene complexes, investigated by X-
ray crystallography: (a) G. Huttner, V. Bejenke, H.D. Mu¨ller,
Cryst. Struct. Commun. 5 (1976) 437;
(b) S. Pasynkiewicz, W. Buckowicz, J. Poplawska, A. Pi-
etrzykowski, J. Zachara, J. Organomet. Chem. 490 (1995) 189;
(c) M. Akita, R. Hua, S. Nakanishi, M. Tanaka, Y. Morooka,
Organometallics 16 (1997) 5572;
(d) S. Pasynkiewicz, A. Pietrzykowski, L. Bukowska, L.
Jerzykiewicz, J. Organomet. Chem. 585 (1999) 308.
[6] M. Enders, G. Ludwig, H. Pritzkow, Organometallics 20 (2001)
827.
6. Supplementary material
[7] M. Enders, R. Rudolph, H. Pritzkow, Chem. Ber. 129 (1996)
459.
[8] (a) L.S. Luh, U.B. Elke, L.K. Liu, Organometallics 14 (1995)
440;
(b) W. Tsai, M.D. Rausch, R.D. Rogers, Organometallics 15
(1996) 2591.
[9] (a) A. Bondi, J. Phys. Chem. 68 (1964) 441;
(b) M. Mascal, Chem. Commun. (1998) 303;
(c) R. Taylor, O. Kennard, J. Am. Chem. Soc. 104 (1982)
5063.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 164703–164708 for com-
pounds 5–11, respectively. Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax:
+44-1223-336033;
e-mail:
deposit@ccdc.
cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
[10] R.G. Teller, J.M. Williams, Inorg. Chem. 19 (1980) 2770.
[11] (a) U. Behrens, E. Weiss, J. Organomet. Chem. 96 (1975)
435;
Acknowledgements
(b) S. To¨fke, E.T.K. Haupt, U. Behrens, Chem. Ber. 119 (1986)
96;
(c) M.V. Capparelli, Y. De Sanctis, A.J. Arce, Acta Crystalogr.
Sect. C 51 (1995) 1118.
[12] M. Enders, G. Ludwig, unpublished results.
[13] S. Mihan, D. Lilge, P. De Lange, G. Schweier, M. Schneider, U.
Rief, U. Handrich, J. Hack, M. Enders, G. Ludwig, R. Rudolph,
PCT Int. Appl., WO 0112641, 2001.
This work was supported by the Deutsche
Forschungsgemeinschaft (SFB 247) and by the Anor-
ganisch-Chemisches Institut der Universita¨t. G.K.
thanks the Landesgraduiertenfo¨rderung Baden-Wu¨rt-
temberg for a scholarship.
[14] J. Mirek, Roczniki Chem. 34 (1960) 1599 (Chem. Abstr. 55
(1961) 22314g).
[15] P.E. Cattermale, A.G. Osborne, Inorg. Synth. 17 (1977) 115.
[16] G.M. Sheldrick, SHELXTL, V5.10 NT, Bruker AXS, Wi/USA,
1998.
References
[1] R.K. Kochhar, R. Petitt, J. Organomet. Chem. 6 (1966) 272.