Carbon-rich organometallic materials derived from 4-ethynylphenylferrocene

Article abstract of DOI:10.1016/S0022-328X(03)00706-X

Using 4-ethynylphenylferrocene (1) as the building block, a new series of rigid-rod alkynylferrocenyl precursors consisting of fluoren-9-one unit, 2-bromo-7-(4-ferrocenylphenylethynyl)fluoren-9-one (2a), 2,7-bis (4-ferrocenylphenylethynyl)fluoren-9-one (2b), 2-trimethylsilylethynyl-7- (4-ferrocenylphenylethynyl)fluoren-9-one (3) and 2-ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (4) have been prepared in moderate to good yields. The acetylene complex 4 is a useful precursor for the synthesis of well-defined carbon-rich ferrocenyl heterometallic complexes, trans-[(η⁵-C₅ H₅) Fe(η⁵-C₅H₄) C₆ H₄C≡CRC≡CPt(PEt₃) ₂Ph] (5), trans-[(η⁵-C₅ H₅) Fe(η⁵-C₅H₄) C₆ H₄C≡CRC≡CPt(PBu₃) ₂ C≡CRC≡CC₆H₄ (η⁵- C₅H₄)Fe(η⁵ -C₅ H₅)] (6), trans-[(η⁵ -C₅ H₅)Fe(η⁵-C₅ H₄) C₆H₄C≡CRC≡CM(dppm) ₂ Cl] (M=Ru (7), Os (8)) (R=fluoren-9-one-2,7-diyl). All new complexes have been characterized by FTIR, NMR and UV-Vis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The molecular structures of 1, 2a, 4, 6 and 8 have been determined by single-crystal X-ray studies where an iron-iron through-space distance of nanosized dimension (ca. 42 A?) is observed in the trimetallic molecular rod 6. The electronic absorption, luminescence and electrochemical properties of these carbon-rich molecules were investigated and the data were correlated with the theoretical results obtained by the method of density functional theory.

Full text of DOI:10.1016/S0022-328X(03)00706-X

Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
www.elsevier.com/locate/jorganchem
Carbon-rich organometallic materials derived from
4-ethynylphenylferrocene
Wai-Yeung Wong a,*, Ka-Yan Ho a, Sze-Ling Ho a, Zhenyang Lin b
a Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, China
b Department of Chemistry, Hong Kong University of Science and Technology, Clearwater Bay, Hong Kong, China
Received 7 May 2003
Abstract
Using 4-ethynylphenylferrocene (1) as the building block, a new series of rigid-rod alkynylferrocenyl precursors consisting of
fluoren-9-one unit, 2-bromo-7-(4-ferrocenylphenylethynyl)fluoren-9-one (2a), 2,7-bis(4-ferrocenylphenylethynyl)fluoren-9-one (2b),
2-trimethylsilylethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (3) and 2-ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (4)
have been prepared in moderate to good yields. The acetylene complex 4 is a useful precursor for the synthesis of well-defined
carbon-rich ferrocenyl heterometallic complexes, trans-[(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
C5H5)Fe(h5-C5H4)C6H4Cꢀ CC6H4(h5-C5H4)Fe(h5-C5H5)] (6), trans-[(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
CRCꢀCPt(PBu3)2CꢀCRCꢀ
CRCꢀCM(dppm)2Cl] (MꢀRu (7), Os (8)) (Rꢀfluoren-9-one-2,7-diyl). All new complexes have been characterized by FTIR,
NMR and UVꢁVis spectroscopies and fast atom bombardment mass spectrometry (FABMS). The molecular structures of 1, 2a, 4,
6 and 8 have been determined by single-crystal X-ray studies where an ironꢁiron through-space distance of nanosized dimension (ca.
/
CRCꢀ
/
CPt(PEt3)2Ph] (5), trans-[(h5-
/
/
/
/
/
/
/
/
/
/
˚
42 A) is observed in the trimetallic molecular rod 6. The electronic absorption, luminescence and electrochemical properties of these
carbon-rich molecules were investigated and the data were correlated with the theoretical results obtained by the method of density
functional theory.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Alkynyl complexes; Ferrocene; Fluorenone; Platinum; Osmium
1. Introduction
centers incorporated into their backbone. Although the
first report of the mixed-valence ion of diferrocenylace-
tylene was reported as early as 1974 [4], interest in metal-
capped linear polycarbon chains as models for materi-
ally useful compounds is still very intense and much
research efforts have been devoted to the molecular
design of ferrocene-derived homo- and heterometallic
molecular scaffolds connected by a wide variety of
organic aromatic and heteroaromatic spacers as well
Carbon-rich organometallic compounds containing
rigid, p-conjugated fragments continue to constitute an
important research frontier because of their wide
applications in many areas of materials science [1]. It
has been well documented that molecular wires compris-
ing mixed-valence bimetallic units or remote redox-
active organometallic groups linked by all-carbon chains
could be exploited in molecular electronics, optoelec-
tronic and chemical-sensing devices [2]. Molecular wires
with through-space metal-to-metal distance of up to 40
as oligoacetylenic units [5ꢁ7]. The introduction of a
/
metallocene unit into ‘‘rigid-rod’’ one-dimensional oli-
gomers and polymers may lead to a range of properties
(e.g. redox, optical, electrical and catalytic properties)
that differ from those of conventional organic polymers
[5,6].
˚
˚
A and an effective conjugation pathway of up to 50 A
are also known [3]. Molecules of this type would be
useful models for conducting polymers that have metal
Our research group has recently initiated a program
to develop rational synthetic routes to some well-defined
oligoacetylenic ferrocenyl complexes with bridging units
such as oligothiophenes and functionalized 2,7-fluorenes
* Corresponding author. Tel.: ꢂ
7348.
E-mail address: rwywong@hkbu.edu.hk (W.-Y. Wong).
/
852-3411-7074; fax: ꢂ852-3411-
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00706-X

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W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
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i
Scheme 1. (i) Pd(OAc)2, CuI, PPh3, Pr2NH.
by a series of controlled coupling sequences based on
ethynylferrocene [7]. Our interest in the employment of
these organic linkers in molecular design stems from the
fact that materials derived from them usually possess
intriguing luminescent and physical properties [8].
Alkynyl ligands can offer synthetic versatility and
structural rigidity and have great potentials to allow
electronic communication between redox-active term-
inal end groups through delocalized bonds [6]. X-ray
crystallographic studies of several of these molecules in
trace amount of atmospheric O2 (Scheme 1). We have
been able to minimize the yield of the homocoupling
product 2c (B5%) under almost anaerobic conditions.
/
After conversion of the mono-bromo species 2a to 2-
trimethylsilylethynyl-7-(4-ferrocenylphenylethynyl)fluo-
ren-9-one (3) using the established method [7], desilyla-
tion of 3 with K2CO3 in MeOH readily afforded 2-
ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-9-one (4)
that was used for the build-up of the following multi-
metallic systems. Scheme 2 outlines the synthetic routes
to the various bi- and trimetallic complexes in our study.
The classical dehydrohalogenation reactions between 3
and trans-[Pt(PEt3)2(Ph)Cl] or trans-[Pt(PBu3)2Cl2] led
to new platinum(II) alkynyl complexes trans-[(h5-
the solid state allow an ironꢁ
/iron through-space separa-
˚
tion of up to ca. 34 A to be estimated [7b,7c]. In the
quest for new alkynylferrocene-based materials, it
seemed an attractive goal to us to develop new
molecular architectures based on the more extended
congener, 4-ethynylphenylferrocene (1), and such a
study should represent an interesting extension to the
chemistry of related systems. We report in this paper the
synthesis, characterization as well as photophysical,
redox and structural properties of a new series of
carbon-rich organometallic oligoacetylide complexes
using 1 as the building unit, and molecular orbital
calculations of these molecules, at the B3LYP level of
density functional theory, have been carried out in order
to compare the results with the experimental data.
C5H5)Fe(h5-C5H4)C6H4Cꢀ
and
trans-[(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
CPt(PBu3)2CꢀCRCꢀ
CC6H4(h5-C5H4)Fe(h5-C5H5)] (6)
(Rꢀfluoren-9-one-2,7-diyl) in good yields and these
/
CRCꢀ/CPt(PEt3)2Ph]
(5)
/
CRCꢀ
/
/
/
/
products were purified by preparative TLC on silica
[7,8c,8d,8e,8f]. New s-acetylide complexes of Group 8
/
metals
CM(dppm)2Cl] (Mꢀ
one-2,7-diyl) were made by reacting cis-[M(dppm)2Cl2]
(MꢀRu, Os) with NaPF6 to give first the vinylidene
trans-[(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
/
CRCꢀ
/
Ru (7), Os (8)) (Rꢀ
/
fluoren-9-
/
intermediates which can be deprotonated by DBU to
furnish the desired compounds [9] and pure samples of 7
and 8 were obtained in satisfactory yields after passage
of the crude products through a short alumina column.
All new complexes exhibit good air stability and
solubility in common organic solvents. The proposed
formulations of the new complexes were all in accord
with their analytical and spectroscopic (FTIR, NMR
and MS) data and the molecular structures of represen-
tative compounds have been determined unequivocally
by single-crystal X-ray analyses.
2. Results and discussion
2.1. Synthesis
Following an expansion of our previously reported
ferrocenyl metal-acetylide systems [7], the Sonogashira
coupling reaction of 4-ethynylphenylferrocene (1) with
an excess of 2,7-dibromofluoren-9-one gave 2-bromo-7-
(4-ferrocenylphenylethynyl)fluoren-9-one (2a) and 2,7-
bis(4-ferrocenylphenylethynyl)fluoren-9-one (2b) as the
major products, accompanied by the formation of 1,4-
bis(4-ferrocenylphenyl)butadiyne (2c) obtained via si-
multaneous oxidative coupling of 1 in the presence of a
2.2. Spectroscopic properties
All new compounds display weak to moderate n(Cꢀ
/
C) absorptions in their IR spectra and all fluorenone-

W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
/353
343
i
Scheme 2. (i) Trimethylsilylacetylene, Pd(OAc)2, CuI, PPh3, Pr2NH; (ii) K2CO3, MeOH; (iii) trans-[Pt(PEt3)2(Ph)Cl], CuI, Pr2NH; (iv) trans-
i
i
[Pt(PBu3)2Cl2] (0.5 equiv.), CuI, Pr2NH; (v) cis-[M(dppm)2Cl2] (MꢀRu, Os), NaPF6, DBU.
/
containing compounds show n(Cꢂ
about 1720 cmꢃ1. The Cꢀ
C ꢁH stretching band also
occurs at 3302 cmꢃ1 for 4. For 3ꢁ
6, two n(CꢀC) bands
are observed and those at the higher frequencies absorb
at similar energies in each case and compare well with
the value (2213 cmꢃ1) found in 2b. The lower frequency
/
O) vibrations at
these ferrocenyl compounds. Introduction of the plati-
/
/
num(II) segment to 4 causes bathochromic shifts in the
lowest energy bands in 5 and 6, suggesting an enhance-
ment in the extent of p-delocalization through the
platinum centers. A red-shift of about 30 nm is observed
from 4 to 5 and 6 and these results demonstrate that the
conjugation effect is more pronounced in 5 and 6 than in
similar compounds obtained from ethynylferrocene [7c].
The electronic spectra of 7 and 8 are characterized by
/
/
n(Cꢀ
/
C) band appears lower in energy for 5 and 6 than
that found in the uncoordinated precursor 4, in line with
the back-bonding effect of the Pt(II) center to the
acetylide unit. Proton NMR signals typical of mono-
substituted ferrocene and aromatic fluorenone were all
apparent in the new complexes. The simplicity of the IR
the featureless pꢁp* transition bands of the alkynylfer-
/
rocenyl chromophores in the near-UV region accom-
panied by a broader band at 560 and 598 nm for 7 and 8,
respectively. We note that those transitions in the visible
range appear at longer wavelengths for 8 than in the
ruthenium counterpart 7. Because of the significant
contribution from the Group 8 metal d-orbitals to the
HOMOs in these complexes, we consider that the lowest
energy band may be metal-to-ligand charge transfer in
nature (vide infra).
(two n(Cꢀ
/
C) stretching frequencies) and 31P{1H}-NMR
(singlet, with associated Pt satellites) data indicates the
presence of symmetry around the platinum center in 6.
The observation of the room-temperature 31P-NMR
signal as a sharp singlet for each of 5ꢁ8 confirms a trans
/
configuration of the bound phosphine ligands at the
transition metals. The FABMS and elemental analytical
data further support the formulae and composition of
these compounds.
All these fluorenone-containing complexes are lumi-
nescent in CH2Cl2 solutions at room temperature (Table
1) and the emission peaks appear in the range 505ꢁ598
/
nm in the visible region. The luminescence spectra are
virtually invariant of the excitation wavelength used.
Due to their similar structured peak pattern, we consider
that these emission features should have the same origin
in each case. By analogy with 2,7-diethynylfluoren-9-
one which emits at 531 nm in CH2Cl2 [8g], these
luminescence bands probably arise from ligand-dom-
inating emissive states and can be assigned to the
2.3. Electronic absorption and luminescence spectra and
electrochemistry
Table 1 collects the absorption spectral data of our
new complexes recorded in CH2Cl2. For the ferrocenyl
precursors 2ꢁ/4, each of them essentially displays three
main structureless absorption bands between 250 and
400 nm originating from pꢁp* electronic transitions of
/
intraligand pꢁ
/
p* transitions. Comparison of the emis-
the associated organic groups [7]. The broad low-energy
features beyond 400 nm account for the orange colors of
sion spectra of 4 and the platinum complexes (5 and 6)

344
W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
Table 1
Photophysical and redox data for new complexes in CH2Cl2
Complex
lmax (nm) a
lem (nm) b
E1/2 (V) c
2a
2b
2c
3
279 (1.6), 306 (1.6), 349 (1.4), 457 (0.2)
257 (0.6), 304 (0.4), 348 (0.4), 451 (0.3), 490 (0.2)
258 (0.5), 336 (0.7), 449 (0.1)
536
598
0.07 (92), ꢃ
0.06 (86), ꢃ
0.04 (180)
0.09 (97), ꢃ
/
1.56 d
1.58 d
/
ꢁ/
286 (2.3), 311 (2.0), 357 (1.9), 457 (0.3)
240 (3.5), 283 (6.7), 309 (6.2), 354 (5.5), 454 (0.8)
263sh (3.8), 304 (5.3), 330 (3.7), 338 (3.2), 370 (4.6), 488 (0.5)
262 (4.9), 305 (7.5), 378 (10.9), 485 (1.5)
268 (3.0), 320 (1.7), 405 (1.3), 560 (0.2)
302 (3.0), 421 (1.9), 598 (0.4)
526
524
544
545
524
505
/
1.57 d
1.59 d
4
0.10 (96), ꢃ
/
5
0.79 d, 0.07 (107)
0.82 d, 0.06 (158)
0.97 d, 0.08 (100)
6
7
8
0.95 d, 0.07 (107), ꢃ0.11 d
/
10ꢃ4 dm3 molꢃ1 cmꢃ1) are shown in parentheses.
330 nm.
100 mV sꢃ1, half-wave potential values E1/2
a
Extinction coefficients (o ꢄ
/
b
c
Excitation wavelengthꢀ
/
Scan rateꢀ
/
ꢀ/(Epa
ꢂ
/
Epc)/2 for reversible ferrocenyl oxidation, DEpꢀ
/
EpaꢃEpc (in mV) for reversible
/
waves are given in parentheses, where Epa and Epc are the anodic and cathodic peak potentials, respectively.
d
Irreversible wave.
reveals a red-shift in the emission maxima which also
corresponds to the bathochromic shift observed in their
absorption spectra.
The electrochemical behavior of our complexes was
studied by cyclic voltammetry in CH2Cl2 at room
temperature and the redox data are listed in Table 1.
In each case, the complex is characterized by one quasi-
reversible oxidation wave due to the ferrocenyl electro-
2.4. Crystal structure analyses
The molecular structures of complexes 1, 2a, 2c, 4, 6
and 8, as shown by X-ray crystallography, are depicted
in Figs. 1ꢁ
along with selected dihedral angles are tabulated in
Tables 2ꢁ7. For 1, each molecule consists of a ferrocene
unit and an acetylene group (C(17)ꢁ
/
6, respectively. Important bond parameters
/
˚
C(18)ꢀ1.174(3) A)
/
/
appended to the phenylene ring in the 1,4-positions. The
structure of 2c possesses a 1,3-butadiyne linear chain
with two ferrocenyl substituents in positions 1 and 4 of
the chain. Each ferrocenyl moiety lies on opposite sides
of the mean plane of the chain and C5H4 rings, with a
phore that is present. An anodic shift of the ferroceneꢁ
/
ferrocenium couple relative to the ferrocene standard is
caused by the unsaturation of the alkynyl units which
makes the removal of electrons more difficult than pure
ferrocene. Each of the complexes 2b and 2c displays only
a single two-electron oxidation for the two ferrocenyl
groups, indicating no detectable electrocommunication
between them. When the conjugation is extended from 4
symmetry center at the mid-point of the C(18)ꢁ
/C(18A)
bond that coincides with the crystallographic center of
˚
symmetry. The C(17)ꢁ
/
C(18) (1.184(8) A) and C(18)ꢁ
/
˚
C(18A) (1.391(14) A) distances are of the order of those
observed in 1,4-diferrocenyl-1,3-butadiyne (1.198(4) and
to 5ꢁ8 after adding an organometallic segment, only a
/
slight negative shift in E1/2 values is observed. Electro-
chemical studies on the mixed-metal complex 6 indicate
˚
1.373(3) A, respectively) [11] and 1,12-bis(ferrocenyl)-
1,3,5,7,9,11-dodecahexane (1.196(9)ꢁ1.224(10) and
1.404(16) A) [6c]. Figs. 2 and 4 show that
/
that there is no ferroceneꢁferrocene interaction through
/
˚
1.347(11)ꢁ
/
the alkynyl-platinum bridge and it only undergoes a
single-step two-electron oxidation involving the conco-
mitant oxidation of the two ferrocenyl subunits at a scan
rate of 100 mV sꢃ1. Non-interacting diferrocenyl
molecules have been reported in some conjugated
organometallic systems [7,10]. Fluorenone-based reduc-
one 4-ferrocenylphenyl unit is attached to one end of 2-
bromo-7-ethynylfluoren-9-one and 2,7-diethynylfluo-
ren-9-one, respectively, for 2a and 4. The acetylide
˚
1.199(3) A.
bonds show normal lengths of 1.161(4)ꢁ
/
For 6, the crystal structure shows a diferrocenyl end-
capped species in which two deprotonated forms of 4 are
covalently bonded to the central Pt(PBu3)2 unit in a
trans geometry to afford a one-dimensional molecular
rod of defined length and the through-space separation
tion waves which span the narrow range of ꢃ
1.59 V are also observed for 2a, 2b, 3 and 4, but they are
absent in the heterometallic complexes 5ꢁ8. Similar
/
1.56 to ꢃ
/
/
phenomenon has been observed for related compounds
derived from ethynylferrocene [7c]. For 5 and 6, another
redox event was detected at higher positive potentials
which can be attributed to the irreversible oxidation of
˚
between Fe(1) and Fe(2) is estimated to be 42 A in the
˚
solid state, which is larger than the value of 34 A found
in the related complex constructed from ethynylferro-
cene. Hence, extension of the dimensions of these metal-
capped molecules from molecular scale to nanoscale
the platinum moiety [Pt(II)0
peak at ꢃ0.11 V is most likely to be due to the
oxidation of Os(II) core in 8.
/Pt(III)]. The potential
/
becomes viable based on this synthetic strategy. The
˚
Pt distance is ca. 21 A. The
corresponding mean Feꢁ
/

W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
/353
345
Fig. 1. A perspective view of 1, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level and hydrogen atoms
are omitted for clarity.
platinum center adopts a square-planar geometry and
˚
P distance is 2.277(3) A. The alkynyl
In each of these alkynylferrocenyl complexes, the
cyclopentadienyl rings of the ferrocenyl group are
essentially planar and exhibit an eclipsed conformation
with deviation angles spanning a narrow range of ca.
the average Ptꢁ
/
bond lengths span the narrow range 1.180(10)ꢁ
/
˚
1.206(11) A, which are comparable to those found in
0.9ꢁ6.88. Variation of the end groups does not have a
/
other analogous complexes [7]. The nearly linear bond
angles around the alkyne units in 6 conform to the rigid
and straight-chain nature of the molecule.
great influence on the bond parameters of the ferrocene
and fluorenone units. Moreover, all the fluorenonediyl
ring systems are planar and the structural parameters
within the ring are normal. There are also no short
intermolecular contacts and p-stacking of fluorenone
units in all these crystal lattices.
The heterometallic complex
8 has the trans-
[Os(dppm)2Cl] fragment bonded to the terminal alkyne
unit of 2-ethynyl-7-(4-ferrocenylphenylethynyl)fluoren-
9-one where the Osꢁ
ligand (Cl(1)ꢁOs(1)ꢁC(33)ꢀ
nation at the osmium(II) center is distorted octahedral
/Cl vector is trans to the alkynyl
/
/
/
174.38(13)8). The coordi-
2.5. Molecular orbital calculations
˚
P distance of 2.3528(16) A, which
with the mean Osꢁ
/
To examine the electronic structures and gain a
deeper insight into the nature of the frontier molecular
orbitals of these carbon-rich organometallic molecules,
we have carried out molecular orbital calculations at the
B3LYP level of density functional theory (DFT) for
complexes 6 and 8 based on their experimental geome-
tries obtained from the X-ray data [12], and the results
compare well with the structural features observed in
other structurally characterized osmium mono-chloro
acetylide complexes such as trans-[(h5-C5H5)Fe(h5-
C5H4)Cꢀ
[(dppm)2ClOsCꢀ
lengths are typical at 1.199(8)ꢁ
/
COs(dppm)2Cl]
[9a]
and
trans-
/
CSiCꢀCH] [9e]. The alkynyl bond
/
˚
1.207(6) A.
/
Fig. 2. A perspective view of 2a, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level and hydrogen
atoms are omitted for clarity.

346
W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
Fig. 3. A perspective view of one molecule of 2c, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level
and hydrogen atoms are omitted for clarity.
are compared to those of 4. Fig. 7 shows the contour
plots [13] of the orbitals in the HOMOꢁLUMO region
the chloride, there are p*-antibonding characters be-
tween Os and Cl in the two HOMOs. Therefore, the
/
absorption band corresponding to the HOMOꢁ
transition probably has the MLCT character and the
calculated HOMOꢁLUMO gap (2.69 eV) for 8 is
considerably smaller than that for 4 (3.03 eV). The
three HOMOs in 4 correspond to the 3rd to 5th
/
LUMO
for 4. We found that the three HOMOs for 4 correspond
to those derived from the mixing of the highest occupied
orbitals of the conjugated organic structural unit and
the two Fe(dd)-orbitals. The d-type is defined by viewing
/
the orbitals along the Ctꢁ
each cyclopentadienyl ligand). When the Ctꢁ
is defined as the z-axis, the two dd-orbitals correspond
/
Feꢁ
/Ct axes (Ct: the center of
HOMOs in 8. Likewise, the smaller HOMOꢁ
gap for 6 (3.01 eV) in comparison to 4 can be related to
their observed UVꢁVis data which indicates the possi-
/
LUMO
/
FeꢁCt axis
/
/
2
to the dxy and dx ꢃy orbitals. The LUMOs for 4
2
/
bility of p-conjugation through the platinum unit.
correspond to the p* orbital in the structural unit having
a carbonyl group. Carbonyl groups normally have lower
p* orbitals because of the electronegative oxygen atom.
An orbital correlation diagram shown in Fig. 7 is used
to illustrate the change in the orbital patterns in 6 and 8
upon incorporation of different metal groups to 4. The
frontier orbitals of 6 are derived from the orbital
combinations of the two ferrocenyl-containing alkynyl
ligands. The two HOMOs are contributed from the
highest occupied p-orbitals of the two ligands whereas
the two LUMOs arise from the lowest unoccupied p*-
orbitals of the organic portion in the two ligands. The
two HOMOs of 8 are derived from the mixing of the Os
3. Concluding remarks
This report describes the successful use of 4-ethynyl-
phenylferrocene as the synthon to afford a new family of
luminescent carbon-rich heterometallic complexes in
satisfactory yields. The properties of these compounds
were completely elucidated by spectroscopic, electro-
chemical and X-ray structural techniques. Linear chain
growth in two directions around the central platinum
moiety was demonstrated in the trimetallic compound 6
metal d-orbitals (i.e. dxz and dyz when the Osꢁ
direction is defined as the z-axis) and p-orbitals of the
Os-bonded CꢀC unit. The LUMOs correspond to the
lowest p*-orbitals of the carbonyl-containing conjugate
structural moiety. Because of p-donating properties of
/
Cl bond
by platinumꢁ
/
alkyne bond formation but its cyclic
voltammogram shows only one two-electron ferrocenyl
redox process, indicating that there is no detectable
electrocommunication between the terminal ferrocenyl
groups through the carbon-rich links. The two iron(II)
/
Fig. 4. A perspective view of 4, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level and hydrogen atoms
are omitted for clarity.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
/353
347
Fig. 5. A perspective view of 6, showing the atomic labelling scheme. Hydrogen atoms and labels on the butyl groups are omitted for clarity.
centers at the ferrocenyl termini of 6 show a very long
˚
through-space distance of ca. 42 A and we have been
Table 2
˚
Selected bond lengths (A) and angles (8) for complex 1
able to extend the dimensions of these rigid-rod-like
complexes from the molecular scale to nanoscale which
is essential for the further development of nanoscale
molecular wires and related nanomaterials. Our experi-
mental results show that delocalization of p electrons
continues through the metal center which agree well
with the theoretical calculations. We are currently
extending these promising synthetic routes in the search
for a new series of rigid-rod multimetallic assemblies of
nanosized dimensions.
Fe(1)ꢁ
Fe(1)ꢁ
C(17)ꢁ
/
Cp
1.6504
1.6470
1.174(3)
/C5H4
/
C(18)
C(14)ꢁ
/
C(17)ꢁ
/
C(18)
178.8(2)
Dihedral angles (8) between planes
A and B
A and C
B and C
0.2
38.2
38.0
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
/
C(2)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(14)ꢁ
/
C(5); B, C(6)ꢁ
C(15)ꢁC(16).
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
/
/
C(13)ꢁ
/
/
/
4. Experimental
reported procedures. Infrared spectra were recorded as
CH2Cl2 solutions in a CaF2 cell (0.5 mm path length) on
4.1. General procedures
a PerkinꢁElmer Paragon 1000 PC or Nicolet Magna 550
/
Series II FTIR spectrometer. Proton NMR spectra were
measured in CDCl3 on a Jeol EX270 or a Varian
INOVA 400 MHz FT NMR spectrometer. Chemical
All reactions were carried out under N2 with the use
of standard inert atmosphere and Schlenk techniques,
but no special precautions were taken to exclude oxygen
during work-up. Solvents were pre-dried and distilled
from appropriate drying agents. All chemicals, unless
otherwise stated, were obtained from commercial
sources and used as received. Preparative TLC was
performed on 0.7 mm silica plates (Merck Kieselgel 60
GF254) prepared in our laboratory. The starting com-
shifts were quoted relative to SiMe4 (dꢀ0 ppm).
/
FABMS were recorded on a Finnigan MAT SSQ710
mass spectrometer. Electronic absorption spectra were
obtained with a Hewlett Packard 8453 UVꢁVis spectro-
/
meter and steady-state visible luminescence spectra on a
Photon Technology International (PTI) Alphascan
spectrofluorimeter. Cyclic voltammetry experiments
were done with a Princeton Applied Research (PAR)
model 273A potentiostat, connected to an interfaced
pounds
[Pt(PEt3)2(Ph)Cl] [15], trans-[Pt(PBu3)2Cl2] [16] and
cis-[M(dppm)2Cl2] (MꢀRu, Os) [17] were prepared by
4-ethynylphenylferrocene
[14],
trans-
/
Fig. 6. A perspective view of 8, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level and hydrogen atoms
are omitted for clarity.

348
W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
Table 3
Table 6
Selected bond lengths (A) and angles (8) for complex 6
˚
˚
Selected bond lengths (A) and angles (8) for complex 2a
Fe(1)ꢁ
Fe(1)ꢁ
C(17)ꢁ
Br(1)ꢁC(25)
/
Cp
1.6443
1.6430
Fe(1)ꢁ
Fe(1)ꢁ
Fe(2)ꢁ
Fe(2)ꢁ
C(17)ꢁ
C(32)ꢁ
/
Cp
1.6477
1.6283
/C5H4
/C5H4
/
C(18)
1.188(4)
1.892(3)
/Cp
1.6564
1.6371
/
/C5H4
/
C(18)
1.180(10)
1.206(11)
1.990(8)
2.281(3)
2.272(3)
2.002(6)
1.194(8)
1.190(8)
C(14)ꢁC(17)ꢁ
/
/
C(18)
176.7(3)
177.6(3)
/
C(33)
C(17)ꢁC(18)ꢁ
/
/C(19)
Pt(1)ꢁ
Pt(1)ꢁ
Pt(1)ꢁ
Pt(1)ꢁ
C(58)ꢁ
C(73)ꢁ
/
C(33)
Dihedral angles (8) between planes
/
P(1)
A and B
A and C
A and D
B and C
B and D
C and D
2.5
7.7
8.3
8.0
7.1
4.9
/P(2)
/C(58)
/
C(59)
/
C(74)
C(14)ꢁ
C(17)ꢁ
C(29)ꢁ
Pt(1)ꢁC(33)ꢁ
P(1)ꢁPt(1)ꢁP(2)
Pt(1)ꢁC(58)ꢁC(59)
C(58)ꢁC(59)ꢁ
C(70)ꢁC(73)ꢁ
C(73)ꢁC(74)ꢁ
/
C(17)ꢁ
C(18)ꢁ
C(32)ꢁ
/
C(18)
C(19)
C(33)
179.1(10)
/
/
173.7(9)
174.8(11)
174.8(8)
173.06(8)
176.7(6)
175.9(8)
176.6(8)
177.4(8)
/
/
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
C(21)ꢁC(22)ꢁC(23)ꢁC(24)ꢁ
C(30)ꢁC(31).
/
C(2)ꢁ
C(13)ꢁ
C(25)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(29)ꢁ
C(26)ꢁ
/
C(5); B, C(6)ꢁ
C(30)ꢁC(31); D, C(19)ꢁ
C(27)ꢁC(28)ꢁC(29)ꢁ
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
/
/
C(32)
/
/
/
/
/
/
C(20)ꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(60)
C(74)
C(75)
/
/
/
/
Table 4
Selected bond lengths (A) and angles (8) for complex 2c
Dihedral angles (8) between planes
A and B
A and C
˚
0.7
14.9
9.5
Fe(1)ꢁ
Fe(1)ꢁ
C(17)ꢁ
C(18)ꢁ
/
Cp
1.6536
1.6452
A and D
B and C
/C5H4
14.5
8.9
/
C(18)
1.184(8)
1.391(14)
B and D
C and D
/
C(18A)
16.5
80.8
2.9
C(14)ꢁ
/
C(17)ꢁ
/C(18)
178.8(7)
D and E
E and F
Dihedral angles (8) between planes
A and B
A and C
B and C
1.8
9.8
E and G
E and H
10.7
13.2
11.3
14.0
2.7
10.1
F and G
F and H
G and H
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
/
C(2)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(14)ꢁ
/
C(5); B, C(6)ꢁ
C(15)ꢁC(16).
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
/
/
C(13)ꢁ
/
/
/
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
C(21)ꢁC(22)ꢁC(23)ꢁC(24)ꢁ
C(30)ꢁC(31); E, C(60)ꢁC(61)ꢁ
C(67)ꢁC(68)ꢁC(69)ꢁC(70)ꢁC(71)ꢁ
C(78)ꢁC(79)ꢁC(80); G, C(81)ꢁ
C(86)ꢁC(87)ꢁC(88)ꢁC(89)ꢁC(90).
/
C(2)ꢁ
C(13)ꢁ
C(25)ꢁ
C(62)ꢁ
C(72); F, C(75)ꢁ
C(82)ꢁC(83)ꢁC(84)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(14)ꢁ
C(26)ꢁ
C(63)ꢁ
/
C(5); B, C(6)ꢁ
C(15)ꢁC(16); D, C(19)ꢁ
C(27)ꢁC(28)ꢁC(29)ꢁ
C(64)ꢁC(65)ꢁ
C(76)ꢁ
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
/
/
/
/
/
/
C(20)ꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(66)ꢁ
C(77)ꢁ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(85); H,
Table 5
Selected bond lengths (A) and angles (8) for complex 4
˚
/
/
/
/
computer employing PAR 270 electrochemical software.
A conventional three-electrode configuration consisting
of a glassy-carbon working electrode, a Pt-wire counter-
electrode and a Ag/AgNO3 reference electrode (0.1 M in
acetonitrile) was used. The solvent in all measurements
was deoxygenated CH2Cl2 and the supporting electro-
lyte was 0.1 M [Bu4N]PF6. Ferrocene was added as an
internal standard at the end of each experiment and all
potential data reported (vs. Ag/AgNO3) were checked
Fe(1)ꢁ
Fe(1)ꢁ
C(17)ꢁ
C(32)ꢁ
/
Cp
1.6517
1.6514
/C5H4
/
C(18)
1.199(3)
1.161(4)
/
C(33)
C(14)ꢁ
C(17)ꢁ
C(26)ꢁ
/
C(17)ꢁ
C(18)ꢁ
C(32)ꢁ
/
C(18)
C(19)
C(33)
177.2(3)
178.9(3)
178.8(3)
/
/
/
/
Dihedral angles (8) between planes
A and B
A and C
A and D
B and C
B and D
C and D
3.3
7.6
7.6
7.6
6.3
3.1
against the ferroceneꢁferrocenium couple. The number
/
of electrons transferred for each compound was esti-
mated by comparing the peak height of the respective
ferrocene oxidation wave with an equal concentration of
the ferrocene standard added in the same system, in
which one-electron oxidation was assumed. For DFT
calculations at the B3LYP level, the basis set used for C
and H atoms was 6-31G [18] while effective core
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
C(21)ꢁC(22)ꢁC(23)ꢁC(24)ꢁ
C(30)ꢁC(31).
/
C(2)ꢁ
C(13)ꢁ
C(25)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(14)ꢁ
C(26)ꢁ
/
C(5); B, C(6)ꢁ
C(15)ꢁC(16); D, C(19)ꢁ
C(27)ꢁC(28)ꢁC(29)ꢁ
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
/
/
/
/
/
/
C(20)ꢁ
/
/
/
/
/
/
/
/
/
/
/

W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
/353
349
Table 7
Selected bond lengths (A) and angles (8) for complex 8
4.2. Preparations of complexes
˚
Fe(1)ꢁ
Fe(1)ꢁ
C(17)ꢁ
C(32)ꢁ
Os(1)ꢁ
Os(1)ꢁ
Os(1)ꢁ
Os(1)ꢁ
Os(1)ꢁ
Os(1)ꢁ
/
Cp
1.6456
1.6352
1.199(8)
4.2.1. Synthesis of [(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
CRBr] (2a), [(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
CRCꢀ
CC6H4(h5-C5H4)Fe(h5-C5H5)] (2b) and [(h5-
C5H5)Fe(h5-C5H4)C6H4Cꢀ CC6H4(h5-
CCꢀ
C5H4)Fe(h5-C5H5)] (2c) (Rꢀ
fluoren-9-one-2,7-diyl)
/
/C5H4
/
/
/
C(18)
/
C(33)
1.207(6)
/
/
/
C(33)
Cl(1)
P(1)
P(2)
P(3)
P(4)
1.989(4)
/
/
2.4895(13)
2.3311(16)
2.3711(15)
2.3602(15)
2.3487(16)
/
2,7-Dibromofluoren-9-one (50 mg, 0.15 mmol) and 4-
ethynylphenylferrocene (1, 42 mg, 0.15 mmol) in
/
iPr2NHꢁCH2Cl2 (30 cm3, 1:1, v/v) were mixed under
/
/
/
N2 with catalytic amounts of Pd(OAc)2 (1 mg), CuI (1
mg) and PPh3 (2 mg). The mixture was refluxed for a
period of 15 h, after which all volatile components were
removed under reduced pressure. The residue was
redissolved in CH2Cl2 and subsequently subjected to
preparative TLC separation on silica using hexaneꢁ
CH2Cl2 (3:2, v/v) as eluent. Three major orange bands
were obtained from which the products were identified
C(14)ꢁ
C(17)ꢁ
C(28)ꢁ
Os(1)ꢁ
Cl(1)ꢁ
P(1)ꢁOs(1)ꢁ
P(1)ꢁC(46)ꢁ
P(3)ꢁOs(1)ꢁ
P(3)ꢁC(71)ꢁ
/
C(17)ꢁ
C(18)ꢁ
C(32)ꢁ
C(33)ꢁ
/
C(18)
C(19)
C(33)
C(32)
178.5(8)
/
/
176.6(8)
173.7(5)
178.6(4)
174.38(13)
71.52(5)
95.9(2)
/
/
/
/
/
Os(1)ꢁ
/
C(33)
/
/
P(2)
/
/
/
P(2)
/
/
P(4)
71.16(5)
95.9(2)
/
/
P(4)
in descending order as 2c, 2b and 2a (Rfꢀ
0.44, respectively) with respective yields of 10, 28 and
32%. 2a*IR (CH2Cl2): 2213 n(CꢀC), 1723 n(CꢂO)
cmꢃ1. 1H-NMR (CDCl3): d 4.05 (s, 5H, C5H5), 4.37 (t,
2H, JHꢁH 1.9 Hz, C5H4), 4.68 (t, 2H, JHꢁH 1.9 Hz,
C5H4), 7.41 (d, 1H, JHꢁH 7.8 Hz, fluorenone), 7.45 (m,
4H, C6H4), 7.50 (d, 1H, JHꢁH 7.8 Hz, fluorenone),
/0.80, 0.63 and
Dihedral angles (8) between planes
A and B
A and C
A and D
B and C
B and D
C and D
2.6
14.5
53.9
16.6
52.0
68.3
/
/
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
7.62ꢁ
/
7.68 (m, 2H, fluorenone) and 7.78ꢁ7.81 (m, 2H,
/
Planes: A, C(1)ꢁ
C(10); C, C(11)ꢁC(12)ꢁ
C(21)ꢁC(22)ꢁC(23)ꢁC(24)ꢁ
C(30)ꢁC(31).
/
C(2)ꢁ
C(13)ꢁ
C(25)ꢁ
/
C(3)ꢁ
/
C(4)ꢁ
C(14)ꢁ
C(26)ꢁ
/
C(5); B, C(6)ꢁ
C(15)ꢁC(16); D, C(19)ꢁ
C(27)ꢁC(28)ꢁC(29)ꢁ
/
C(7)ꢁ
/
C(8)ꢁ
/
C(9)ꢁ
/
fluorenone) ppm. FABMS: m/z 544 [Mꢂ]. Anal.
Found: C, 68.44; H, 3.29. Calc. for C31H19BrFeO: C,
/
/
/
/
/
/
C(20)ꢁ
/
/
/
/
/
/
/
/
/
/
/
68.54; H, 3.53%. 2b*
n(Cꢂ
O) cmꢃ1 1H-NMR (CDCl3): d 4.18 (s, 10H,
C5H5), 4.48 (m, 4H, C5H4), 4.80 (m, 4H, C5H4) and
7.26ꢁ7.80 (m, 14H, fluorenoneꢂC6H4) ppm. FABMS:
m/z 748 [Mꢂ]. Anal. Found: C, 78.48; H, 4.29. Calc. for
C49H32Fe2O: C, 78.63; H, 4.31%. 2c*IR (CH2Cl2):
2147 n(Cꢀ
C) cmꢃ1. 1H-NMR (CDCl3): d 4.07 (m, 10H,
C5H5), 4.34 (m, 4H, C5H4), 4.68 (m, 4H, C5H4) and
/
IR (CH2Cl2): 2213 n(Cꢀ/C), 1721
/
.
potentials with a LanL2DZ basis set [19] were employed
for Br, Cl, Fe, Os and P atoms. Polarization functions
/
/
were added for Br (zdꢀ
/
0.389), Cl (zdꢀ
/0.514) and P
(zdꢀ0.340). For simplicity, PBu3 was modeled by PMe3
/
/
and the phenyl groups of the dppm were replaced by H
atoms in the calculations.
/
Fig. 7. Contour plots of the highest occupied (HOMO) and the lowest unoccupied molecular orbitals (LUMO) for 4, 6 and 8. In the calculations, the
PBu3 ligands were modeled by PMe3 groups whereas the phenyl rings of dppm were modeled by H atoms.

350
W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
7.43ꢁ
/
7.55 (m, 8H, C6H4) ppm. FABMS: m/z 570 [Mꢂ].
Anal. Found: C, 75.58; H, 4.50. Calc. for C36H26Fe2: C,
75.82; H, 4.60%.
subsequent purification by silica TLC (Rfꢀ
/
0.44) using
hexaneꢁCH2Cl2 (3:2, v/v) as eluent readily led to the
/
isolation of the title compound 5 as a red crystalline
solid in 53% yield (16 mg). IR (CH2Cl2): 2209, 2089
4.2.2. Synthesis of [(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
/
n(Cꢀ
1.05ꢁ
4.05 (s, 5H, C5H5), 4.36 (t, 2H, JHꢁH
4.68 (t, 2H, JHꢁH 1.8 Hz, C5H4), 6.81 (t, 1H, JHꢁH
8.1 Hz, Hpara of Ph), 6.97 (t, 2H, JHꢁH 8.1 Hz, Hmeta
of Ph), 7.31ꢁ7.51 (m, 9H, fluorenoneꢂC6H4ꢂHortho of
Ph), 7.56ꢁ7.62 (m, 2H, fluorenone) and 7.77 (m, 1H,
fluorenone) ppm. 31P{1H}-NMR (CDCl3): d 11.12
(1JPtꢁP 2630 Hz) ppm. FABMS: m/z 996 [Mꢂ].
/
C), 1717 n(Cꢂ
/
O) cmꢃ1 1H-NMR (CDCl3): d
.
CRCꢀ
/
CSiMe3] (Rꢀ
/
fluoren-9-one-2,7-diyl) (3)
/
1.14 (m, 18H, CH3), 1.72ꢁ
/1.79 (m, 12H, CH2),
A mixture of 2a (54 mg, 0.10 mmol), Me3SiCꢀ
/
CH (20
ꢀ
/
1.8 Hz, C5H4),
mg, 0.20 mmol) and freshly distilled Pr2NH (15 cm3)
combined with catalytic quantities of Pd(OAc)2 (1.5
mg), CuI (1.5 mg) and PPh3 (3 mg) in CH2Cl2 (15 cm3)
were allowed to reflux for 17 h. The red residue obtained
by removing the volatile components in vacuo was
redissolved in CH2Cl2. Upon filtration through a short
silica pad, the filtrate was concentrated and purified by
ꢀ
/
ꢀ
/
i
ꢀ
/
/
/
/
/
ꢀ
/
Anal. Found: C, 61.30; H, 5.25. Calc. for
C51H54FeOP2Pt: C, 61.51; H, 5.47%.
preparative TLC (Rfꢀ
v/v) as eluent to yield 3 as an orange-red solid (51 mg,
91%). IR (CH2Cl2): 2204, 2157 n(CꢀC), 1721 n(CꢂO)
cmꢃ1. H-NMR (CDCl3): d 0.27 (s, 9H, Me), 4.05 (s,
5H, C5H5), 4.37 (t, 2H, JHꢁH 2.0 Hz, C5H4), 4.68 (t,
2.0 Hz, C5H4), 7.46 (m, 4H, C6H4), 7.48 (d,
8.0 Hz, fluorenone), 7.51 (d, 1H, JHꢁH 8.0
1.6, 8.0 Hz,
1.6, 8.0 Hz, fluor-
/
0.38) using hexaneꢁCH2Cl2 (4:1,
/
/
/
4.2.5. Synthesis of trans-[(h5-C5H5)Fe(h5-
1
C5H4)C6H4Cꢀ
/
CRCꢀ
/
CPt(PBu3)2Cꢀ
/
CRCꢀ
/
CC6H4(h5-
fluoren-9-one-2,7-diyl) (6)
ꢀ
/
C5H4)Fe(h5-C5H5)] (Rꢀ
The compound trans-[Pt(PBu3)2Cl2] (20 mg, 0.03
/
2H, JHꢁH
1H, JHꢁH
ꢀ
/
ꢀ
/
ꢀ
/
mmol) and two molar equivalents of 4 (29 mg, 0.06
i
Hz, fluorenone), 7.60 (dd, 1H, JHꢁH
ꢀ
/
mmol) were stirred in a mixture of Pr2NHꢁ
/
CH2Cl2 (30
fluorenone), 7.66 (dd, 1H, JHꢁH
ꢀ
/
cm3, 1:1, v/v) at r.t. in the presence of CuI (1.5 mg).
Stirring was continued for 18 h and evaporation of the
volatile components left behind a reddish residue,
purification of which was accomplished by preparative
enone), 7.76 (m, 1H, fluorenone) and 7.81 (m, 1H,
fluorenone) ppm. FABMS: m/z 560 [Mꢂ]. Anal.
Found: C, 77.01; H, 4.89. Calc. for C36H28FeOSi: C,
77.14; H, 5.03%.
TLC eluting with hexaneꢁ
red band (Rfꢀ0.30) was obtained product 6 and a pure
sample of it was isolated in 46% (43 mg) after
recrystallization from a hexaneꢁCH2Cl2 mixture. IR
(CH2Cl2): 2213, 2093 n(CꢀC), 1718 n(Cꢂ
NMR (CDCl3): d 0.93ꢁ0.96 (m, 18H, CH3), 1.42ꢁ
(m, 12H, CH2CH3), 1.59 (m, 12H, PCH2CH2), 2.12ꢁ
2.14 (m, 12H, PCH2), 4.05 (s, 10H, C5H5), 4.36 (t, 4H,
JHꢁH 2.0 Hz, C5H4), 4.68 (t, 4H, JHꢁH 2.0 Hz,
C5H4), 7.38 (m, 4H, fluorenone), 7.43ꢁ7.46 (m, 10H,
fluorenoneꢂC6H4), 7.55 (m, 2H, fluorenone), 7.61ꢁ7.63
(m, 2H, fluorenone) and 7.77 (m, 2H, fluorenone) ppm.
/
CH2Cl2 (3:2, v/v). From the
/
4.2.3. Synthesis of [(h5-C5H5)Fe(h5-C5H4)C6H4Cꢀ
CRCꢀCH] (Rꢀfluoren-9-one-2,7-diyl) (4)
To a solution of 3 (28 mg, 0.05 mmol) in Et2O (10
cm3) was added K2CO3 (7 mg, 0.05 mmol) in MeOH (15
cm3). The mixture was stirred for 24 h at room
temperature (r.t.). After evaporation of the solvent, the
crude product was dissolved in CH2Cl2 and chromato-
/
/
/
/
1
/
/
O) cmꢃ1. H-
/
/1.51
/
ꢀ
/
ꢀ
/
graphed on silica plates (Rfꢀ
CH2Cl2 (3:2, v/v) to afford pure 4 as an orange powder
in 82% yield (20 mg). IR (CH2Cl2): 3302 n(ꢀCH), 2204,
2104 n(CꢀC), 1721 n(Cꢂ
O) cmꢃ1. 1H-NMR (CDCl3): d
3.19 (s, 1H, CꢀCH), 4.05 (s, 5H, C5H5), 4.37 (t, 2H,
JHꢁH 2.0 Hz, C5H4), 4.68 (t, 2H, JHꢁH 2.0 Hz,
C5H4), 7.46 (m, 4H, C6H4), 7.49ꢁ7.55 (m, 2H, fluor-
enone), 7.64 (dd, 1H, JHꢁH 1.6, 8.0 Hz, fluorenone),
7.67 (dd, 1H, JHꢁH 1.6, 8.0 Hz, fluorenone), 7.78 (m,
/
0.33) eluting with hexaneꢁ
/
/
/
/
/
/
/
31P{1H}-NMR (CDCl3): d 4.40 (1JPtꢁP
ꢀ2368 Hz).
/
/
FABMS: m/z 1574 [Mꢂ]. Anal. Found: C, 68.53; H,
ꢀ
/
ꢀ
/
5.70. Calc. for C90H92Fe2O2P2Pt: C, 68.66; H, 5.89%.
/
ꢀ
/
4.2.6. Synthesis of trans-[(h5-C5H5)Fe(h5-
ꢀ
/
C5H4)C6H4Cꢀ
one-2,7-diyl) (7)
mixture of
/
CRCꢀ
/
CRu(dppm)2Cl] (Rꢀ
/
fluoren-9-
1H, fluorenone) and 7.82 (m, 1H, fluorenone) ppm.
FABMS: m/z 488 [Mꢂ]. Anal. Found: C, 81.02; H,
4.05. Calc. for C33H20FeO: C, 81.16; H, 4.13%.
A
4 (24 mg, 0.05 mmol), cis-
[Ru(dppm)2Cl2] (47 mg, 0.05 mmol) and NaPF6 (17
mg, 0.10 mmol) in CH2Cl2 (20 cm3) were stirred for 4 h
at r.t. The resulting red solution was filtered through a
short pad of Celite to remove any excess NaPF6 and
NaCl byproduct, and DBU (7.6 mg, 0.05 mmol) was
then added. After stirring for 2 h, the solvent was
removed in vacuo and the solid was washed with diethyl
ether (20 cm3). The residue was redissolved in CH2Cl2
and filtration through a short alumina column using
pure CH2Cl2 as eluent afforded the title complex as a
4.2.4. Synthesis of trans-[(h5-C5H5)Fe(h5-
C5H4)C6H4Cꢀ
one-2,7-diyl) (5)
/
CRCꢀ
/
CPt(PEt3)2Ph] (Rꢀfluoren-9-
/
Compound 4 (15 mg, 0.03 mmol) and trans-
[Pt(PEt3)2(Ph)Cl] (17 mg, 0.03 mmol) were dissolved in
iPr2NH (15 cm3) and CH2Cl2 (10 cm3). After the
addition of CuI (2 mg), the red solution was stirred at
r.t. over 18 h. Concentration of the solution and

W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ
/353
351
Table 8
Summary of crystal structure data for complexes 1, 2a, 2c, 4, 6 and 8
1
2a
2c
4
6
8×
/
2CH2Cl2×/CH3OH
Empirical formula
Molecular weight
Crystal size (mm3)
C
286.14
18H14Fe
C31H19BrFeO
543.22
C36H26Fe2
570.27
C33H20FeO
488.34
C90H92Fe2O2P2Pt C86H71Cl5FeO2OsP4
1574.37 1683.61
0.30ꢄ0.22ꢄ 0.31ꢄ0.19ꢄ
0.12
triclinic
0.28ꢄ
/0.17ꢄ
/
0.29ꢄ
/
0.20ꢄ
/
0.34ꢄ/0.09ꢄ
/
0.35ꢄ/0.33ꢄ
/
/
/
/
/0.15
0.10
orthorhombic
P212121
0.14
monoclinic
P21/n
0.07
monoclinic
P21/n
0.18
monoclinic
P21/n
Crystal system
Space group
Unit cell dimensions
triclinic
¯
P1
¯
P1
˚
a (A)
9.8097(5)
10.7905(6)
12.7294(7)
10.4702(8)
19.6271(14)
12.3843(9)
7.887(2)
16.013(5)
10.629(3)
10.3811(10)
19.817(2)
12.4389(13)
10.8831(11)
13.2049(14)
28.812(3)
90.289(2)
97.798(2)
110.819(2)
3828.1(7)
1.366
11.465(5)
11.465(5)
30.058(13)
92.271(5)
92.271(5)
107.46(8)
3761(3)
1.487
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
114.6180(10)
102.399(5)
113.262(2)
3
˚
U (A )
1347.43(13)
1.411
4
2313.6(3)
1.560
4
1311.1(7)
1.444
2
2350.9(4)
1.380
4
Dcalc (g cmꢃ3
)
Z
2
2.286
1616
2
2.192
1700
m(Moꢁ
F(0 0 0)
u range (8)
/
Ka) (mmꢃ1
)
1.100
592
2.402
1096
1.130
588
0.666
1008
2.47ꢁ
/
27.51
2.08ꢁ
/
27.54
2.34ꢁ/24.99
2.06ꢁ
/
27.50
1.43ꢁ
/
25.00
1.86ꢁ28.41
/
Reflections collected
Unique reflections
Rint
7861
3023
13 582
5114
0.0307
3266
307
5943
2225
13 826
5315
0.0321
3403
397
19 144
13 211
0.0476
5911
22 406
16 491
0.0389
11 062
892
0.0179
2s(I)] 2843
229
0.0690
1342
172
Observed reflections [I ꢁ
No. of parameters
/
874
R1, wR2 [I ꢁ
/
2s(I)]
0.0234, 0.0642
0.0252, 0.0658
1.040
0.0354, 0.0824
0.0653, 0.0921
0.940
0.0736, 0.1775 0.0370, 0.0889 0.0650, 0.1489
0.1167, 0.2191 0.0688, 0.1017 0.1656, 0.1945
0.0433, 0.0958
0.0770, 0.1075
0.800
R1, wR2 (all data)
Goodness-of-fit on F2
Residual extrema in final diff.
0.849
0.773 to
0.930
0.250 to
0.930
1.278 to
0.195 to
0.399 to
1.070 to
ꢃ3
˚
map (e A
)
ꢃ
/
0.215
ꢃ
/
0.500
ꢃ
/
1.044
ꢃ
/
0.312
ꢃ
/
0.785
ꢃ/0.710
1
reddish-brown solid in 42% yield (29 mg) after recrys-
tallization from an evaporated hexaneꢁCH2Cl2 solution
at r.t. IR (CH2Cl2): 2066 n(CꢀC), 1715 n(Cꢂ
O) cmꢃ1
1H-NMR (CDCl3): d 4.05 (s, 5H, C5H5), 4.36 (m, 2H,
C5H4), 4.68 (m, 2H, C5H4), 4.93 (m, 4H, CH2), 7.09ꢁ
7.20 (m, 30H, fluorenone) and 7.27ꢁ7.46 (m, 20H,
5.60
C), 1715 n(Cꢂ
5H, C5H5), 4.36 (m, 2H, C5H4), 4.68 (m, 2H, C5H4),
5.48 (m, 4H, CH2), 7.09ꢁ7.20 (m, 30H, fluorenone) and
7.27ꢁ
7.46 (m, 20H, fluorenone) ppm. 31P{1H}-NMR
(CDCl3): d ꢃ
48.00 ppm. FABMS: m/z 1482 [Mꢂ].
/
O) cmꢃ1. H-NMR (CDCl3): d 4.06 (s,
/
/
/
.
/
/
/
/
/
Anal. Found: C, 67.02; H, 3.99. Calc. for
C83H63ClFeOOsP4: C, 67.28; H, 4.29%.
fluorenone) ppm. 31P{1H}-NMR (CDCl3): d ꢃ
/
ppm. FABMS: m/z 1394 [Mꢂ]. Anal. Found: C,
71.44; H, 4.38. Calc. for C83H63ClFeOP4Ru: C, 71.58;
H, 4.56%.
5. Crystallography
4.2.7. Synthesis of trans-[(h5-C5H5)Fe(h5-
Single crystals of 1, 2a, 2c, 4, 6 and 8 suitable for X-
ray crystallographic analyses were chosen and mounted
on a glass fiber using epoxy resin. Crystal data and other
experimental details are summarized in Table 8. The
diffraction experiments were carried out at r.t. on a
Bruker Axs SMART 1000 CCD area-detector diffract-
C5H4)C6H4Cꢀ
/
CRCꢀ
/
COs(dppm)2Cl] (Rꢀfluoren-9-
/
one-2,7-diyl) (8)
cis-[Os(dppm)2Cl2] (52 mg, 0.05 mmol) was added to
a solution of 4 (24 mg, 0.05 mmol) in CH2Cl2 (20 cm3) in
the presence of NaPF6 (17 mg, 0.10 mmol) and the
mixture was stirred for 4 h. The resultant vinylidene
solution was filtered and DBU (7.6 mg, 0.05 mmol) was
added to give a deep green solution. After the solution
was stirred for a further 2 h, the solvent was evaporated
off and the residue was washed with diethyl ether (20
cm3). The crude solid was then dissolved in CH2Cl2 and
filtered through a short alumina column eluting with the
same solvent. A greenish-red crystalline solid of 8 was
ometer using graphite-monochromated Moꢁ
/
Ka radia-
˚
0.71073 A). At the end of data collection, no
tion (lꢀ
/
crystal decay was observed. The collected frames were
processed with the software SAINT [20a] and an absorp-
tion correction (SADABS) was applied to the collected
reflections [20b]. The structures were solved by direct
methods (for 1, 2a, 2c and 8) and Patterson method (for
4 and 6), and expanded by difference Fourier syntheses
using the software SHELTXL [21]. Structure refinements
collected in 53% yield (39 mg). IR (CH2Cl2): 2062 n(Cꢀ
/

352
W.-Y. Wong et al. / Journal of Organometallic Chemistry 683 (2003) 341ꢁ353
/
were made on F2 by the full-matrix least-squares
technique. In each case, all the non-hydrogen atoms
were refined with anisotropic displacement parameters.
The hydrogen atoms were placed in their ideal positions
and not refined.
[5] (a) K.R. Justin Thomas, J.T. Lin, K.-J. Lin, Organometallics 18
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(b) R.D. Adams, B. Qu, M.D. Smith, T.A. Albright, Organome-
tallics 21 (2002) 2970;
6. Supplementary material
(c) R.D. Adams, B. Qu, M.D. Smith, Organometallics 21 (2002)
3867;
Crystallographic data (comprising hydrogen atom
coordinates, thermal parameters and full tables of
bond lengths and angles) for the structural analysis
have been deposited with the Cambridge Crystallo-
(d) R.D. Adams, B. Qu, M.D. Smith, Organometallics 21 (2002)
4847;
(e) N.J. Long, A.J. Martin, R. Vilar, A.J.P. White, D.J. Williams,
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graphic Centre (Deposition Nos. 209514ꢁ209519).
/
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: ꢂ44-1223-336-033;
/
(h) O. Lavastre, E. Even, P.H. Dixneuf, A. Pacreau, J.-P. Vairon,
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Acknowledgements
[7] (a) W.-Y. Wong, G.-L. Lu, K.-F. Ng, C.-K. Wong, K.-H. Choi, J.
Financial support from the Faculty Research Grants
of Hong Kong Baptist University (FRG/00-01/II-57) is
gratefully acknowledged.
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