New ferrocenyl heterometallic complexes of 2,7-diethynylfluoren-9-one

Article abstract of DOI:10.1016/S0022-328X(02)02069-7

A new series of rigid-rod alkynylferrocenyl precursors with central fluoren-9-one bridge, 2-bromo-7-(2-ferrocenylethynyl)fluoren-9-one (1b), 2-trimethylsilylethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (2) and 2-ethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (3), have been prepared in moderate to good yields. The ferrocenylacetylene complex 3 can provide a direct access to novel heterometallic complexes, trans-[(η⁵-C₅H₅) Fe(η⁵-C₅H₄) C≡CRC≡CPt(PEt₃)₂Ph] (4), trans-[(η⁵-C₅H₅) Fe(η⁵-C₅H₄) C≡CRC≡CPt(PBu₃)₂C≡CRC≡C (η⁵-C₅H₄)Fe(η⁵- C₅H₅)] (5), [(η⁵-C₅H₅)Fe(η⁵- C₅H₄) C≡CRC≡CAu(PPh₃)] (6) and [(η⁵-C₅H₅)Fe(η⁵- C₅H₄)C≡CRC≡CHgMe] (7) (R=fluoren-9-one-2,7-diyl), following the CuI-catalyzed dehydrohalogenation reactions with the appropriate metal chloride compounds. All the new complexes have been characterized by FTIR, ¹H-NMR and UV-vis spectroscopies and fast atom bombardment mass spectrometry. The solid state molecular structures of 3, 5, 6 and 7 have been established by X-ray crystallography. The redox chemistry of these mixed-metal species has been investigated by cyclic voltammetry and oxidation of the ferrocenyl moiety is facilitated by the presence of the heavy metal centre and increased conjugation in the chain through the ethynyl and fluorenone linkage units.

Full text of DOI:10.1016/S0022-328X(02)02069-7

Journal of Organometallic Chemistry 670 (2003) 17Á26
/
www.elsevier.com/locate/jorganchem
New ferrocenyl heterometallic complexes of 2,7-diethynylfluoren-
9-one
Wai-Yeung Wong *, Ka-Yan Ho, Ka-Ho Choi
Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, PR China
Received 18 September 2002; received in revised form 18 October 2002; accepted 18 October 2002
Abstract
A new series of rigid-rod alkynylferrocenyl precursors with central fluoren-9-one bridge, 2-bromo-7-(2-ferrocenylethynyl)fluoren-
9-one (1b), 2-trimethylsilylethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (2) and 2-ethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (3),
have been prepared in moderate to good yields. The ferrocenylacetylene complex 3 can provide a direct access to novel
heterometallic complexes, trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
CPt(PBu3)2CꢀCRCꢀ
C(h5-C5H4)Fe(h5-C5H5)] (5), [(h5-C5H5)Fe(h5-C5H4)Cꢀ
C5H4)CꢀCRCꢀCHgMe] (7) (Rꢁfluoren-9-one-2,7-diyl), following the CuI-catalyzed dehydrohalogenation reactions with the
appropriate metal chloride compounds. All the new complexes have been characterized by FTIR, 1H-NMR and UVÁ
vis
/
CRCꢀ
/
CPt(PEt3)2Ph] (4), trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
/
CRCꢀ
/
/
/
/
CRCꢀ
/
CAu(PPh3)] (6) and [(h5-C5H5)Fe(h5-
/
/
/
/
spectroscopies and fast atom bombardment mass spectrometry. The solid state molecular structures of 3, 5, 6 and 7 have been
established by X-ray crystallography. The redox chemistry of these mixed-metal species has been investigated by cyclic voltammetry
and oxidation of the ferrocenyl moiety is facilitated by the presence of the heavy metal centre and increased conjugation in the chain
through the ethynyl and fluorenone linkage units.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Alkynyl complexes; Ferrocene; Gold; Mercury; Platinum
1. Introduction
termini made feasible by an organic spacer ‘M1Á
M1’, and the effect of another organometallic fragment
‘M2’ in a conjugated organic chain ‘M1ÁspacerÁM2Á
spacerÁM1’ [3]. Several systems where redox active sites
are strongly coupled electronically through the poly-
ynyl fragments have been reported [3]. With this
research framework in mind, much efforts have parti-
cularly been devoted to the synthesis of ferrocene-based
homo- and heterometallic materials with spacers such as
oligoene, oligoyne, thiophene, furan, phenylene, pheny-
leneyne, thienyl ethynyl and furanyl vinyl units [3,4].
Considerable current attention is paid to the organic
and metal-based materials incorporated with fluorene
auxiliaries [5,6]. The ease of modification and knowl-
/
spacerÁ
/
There is an upsurge of interest in the research
community in the molecular design and synthesis of
carbon-rich bi- or multi-metallic assemblies containing
p-conjugated chains [1]. It has been demonstrated that
molecular wires comprising mixed-valence bimetallic
fragments or remote redox-active organometallic build-
ing blocks linked by all-carbon chains could be used in
molecular electronics, optoelectronic devices and che-
mical sensing appliances [2]. Two common models are
being used to evaluate the capability of electronic
communication between two metal centres ‘M1’ at the
/
/
/
/
edge of the structureÁproperty relationship of poly-
fluorene homopolymers and copolymers continue to
make the fluorene-functionalized compounds very at-
/
* Corresponding author. Tel.: ꢀ
7348
E-mail address: rwywong@hkbu.edu.hk (W.-Y. Wong).
/
852-3411-7074; fax: ꢀ852-3411-
/
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 2 0 6 9 - 7

18
W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á26
/
tractive candidates in the development of new functional
materials [5a,5f]. Recently, a comprehensive program
was therefore launched in our laboratory to prepare a
range of organometallic alkynyl compounds containing
fluorenyl linkers [6]. Remarkable results on the impor-
tance of using fluorenyl derivatives in bi- and poly-
metallic species have encouraged us to design new
heterometallic systems featuring this linking unit [5,6].
Following our recent report of the synthesis and proper-
ties of 2,7-bis(ferrocenylethynyl)fluoren-9-one and re-
lated species [6e], we report in this contribution the
parallel chemistry of a series of fluorenone-containing
heteronuclear organometallic alkynyl complexes end-
capped with ferrocenyl entity and another transition
metal.
a minor product [6e]. We were able to prevent the
formation of the homocoupling product 1,4-diferroce-
nylbutadiyne under strictly anaerobic conditions. The
mono-bromo species 1b can undergo similar cross-
coupling reaction with trimethylsilylacetylene to give
2-trimethylsilylethynyl-7-(2-ferrocenylethynyl)fluoren-9-
one (2) in good yield, which upon deprotection with
K2CO3 in MeOH affords 2-ethynyl-7-(2-ferrocenylethy-
nyl)fluoren-9-one (3) in high yield. With the free alkyne
unit, compound 3 should be a favourable starting unit to
the synthesis of new hetero-bimetallic and trimetallic
systems. Following the typical dehydrohalogenation
reactions between 3 and trans-[Pt(PEt3)2(Ph)Cl] or
trans-[Pt(PBu3)2Cl2] under the CuIÁi
[6a,6b,6c,6d,7], a convenient route to new platinum(II)
alkynyl complexes trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
CRCꢀ
CPt(PEt3)2Ph] (4) and trans-[(h5-C5H5)Fe(h5-
C5H4)CꢀCRCꢀCPt(PBu3)2CꢀCRCꢀ
C(h5-C5H4)Fe(h5-
C5H5)] (5) (Rꢁfluoren-9-one-2,7-diyl) can be developed.
/
Pr2NH conditions
/
/
2. Results and discussion
/
/
/
/
/
These reaction steps were readily monitored by solution
IR spectroscopy and thin-layer chromatography (TLC).
All the complexes were purified by preparative TLC on
2.1. Synthesis
The reactions pertaining to the synthesis of our
compounds in this study are summarized in Scheme 1.
2-Bromo-7-(2-ferrocenylethynyl)fluoren-9-one (1b) was
prepared in the first step by the Sonogashira coupling
reaction of ethynylferrocene with an excess of 2,7-
dibromofluoren-9-one [6e,7]. Inevitably, this prepara-
tion was accompanied by the isolation of the known
complex 2,7-bis(ferrocenylethynyl)fluoren-9-one (1a) as
silica using a hexaneÁCH2Cl2 mixture as eluent and they
/
were isolated as air-stable orange to red solids in high
purity. Treatment of 3 with Au(PPh3)Cl or MeHgCl in
an excess of basic MeOH produced the alkynylgold(I)
complex [(h5-C5H5)Fe(h5-C5H4)Cꢀ
/
CRCꢀ
(6) and the alkynylmercury(II) complex [(h5-
C5H5)Fe(h5-C5H4)Cꢀ
CRCꢀCHgMe] (7) (Rꢁfluoren-9-
/
CAu(PPh3)]
/
/
/
Scheme 1. (i) Pd(OAc)2, CuI, PPh3, i Pr2NH; (ii) trimethylsilylacetylene, Pd(OAc)2, CuI, PPh3, i Pr2NH; (iii) K2CO3, MeOH; (iv) trans-
[Pt(PEt3)2(Ph)Cl], CuI, i Pr2NH; (v) trans-[Pt(PBu3)2Cl2] (0.5 equiv.), CuI, i Pr2NH; (vi) Au(PPh3)Cl, NaOMe, MeOH; (vii) MeHgCl, NaOMe,
MeOH.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á
/26
19
one-2,7-diyl), which readily precipitated from the solu-
tion mixture [6f,8]. All complexes are soluble in common
organic solvents and have been characterized by satis-
factory microanalysis, fast atom bombardment mass
spectrometry (FABMS), IR and NMR spectroscopies.
Table 1
UVÁvis and electrochemical data for new complexes in CH2Cl2
/
a
b
Complex lmax (nm)
E1/2 (V)
c
1a
1b
2
288 (8.7), 349 (4.7), 493 (0.8)
279 (5.3), 338 (1.8), 472 (0.3)
288 (3.7), 341 (1.3), 467 (0.2)
284 (7.3), 344 (2.3), 474 (0.1)
0.14 (159), ꢁ
0.95
/
d
0.17 (199), ꢁ
/
2.2. Spectroscopic properties
d
0.74
0.13 (80), ꢁ
/
d
All the new compounds display weak to moderate IR
0.77
3
0.17 (159), ꢁ
/
stretching vibrations for the Cꢀ
frequency range 2089Á
2213 cmꢁ1. In general, two
C) bands are observed in the spectra of 2Á7. Those
/C moieties in the
d
0.73
272 sh (1.9), 298 (2.4), 307 (2.4), 368 (2.5), 0.71 d, 0.12 (99)
496 (0.3)
/
4
n(Cꢀ
/
/
5
297 (7.1), 372 (8.2), 494 (1.1)
0.88 d, 0.11
(139)
at the higher frequencies absorb at similar energies in
each case and compare well with the value (ca. 2211
cmꢁ1) found in 1a [6e]. The lower frequency n(Cꢀ
/C)
6
7
297 (6.7), 349 (3.4), 476 (0.3)
289 (7.8), 343 (3.1), 474 (0.4)
0.13 (139)
0.14 (120)
band appears lower in energy for 4 and 5 than that
found in the uncoordinated precursor 3, suggesting the
back-bonding effect of the Pt(II) centre to the acetylide.
a
Extinction coefficients (o ꢂ
/
10ꢁ4 dm3 molꢁ1 cmꢁ1) are shown in
parentheses.
b
Scan rateꢃ
/
100 mV sꢁ1, half-wave potential values E1/2
Epa Epc (in mV) for reversible
ꢃ/
(Epa
ꢀ/
Apparently, the spectral pattern in the n(Cꢀ
/
C) region
Epc)/2 for reversible oxidation, DEpꢃ
/
ꢁ/
for 6 and 7 is a combination of those for their
waves are given in parentheses, where Epa and Epc are the anodic and
cathodic peak potentials, respectively.
homometallic
[(Ph3P)AuCꢀCRCꢀ
[MeHgCꢀCRCꢀ
CHgMe] (2127 cmꢁ1) (Rꢁ
one-2,7-diyl) [6e,6f]. The CꢀC ꢂ
occurs at 3294 cmꢁ1 for 3. In each case, characteristic
n(CꢁO) IR vibration due to the fluorenone unit was also
binuclear
congeners,
1a
and
or
CAu(PPh3)] (2107 cmꢁ1
)
c
/
/
Data from Ref. [6e].
Irreversible wave.
d
/
/
/fluoren-9-
/
/H stretching band also
fully consistent with the IR data. A bathochromic shift
of about 20 nm is observed from 3 to 4 and 5. These
/
observed at around 1720 cmꢁ1. In the 1H-NMR
spectra, proton signals due to the fluorenone and other
organic groups were observed. The ferrocenyl unit also
gives rise to a strong singlet for the C5H5 ring and an
unsymmetrical pair of pseudo triplets for the C5H4 ring,
typical of other monosubstituted ferrocene. For 5, the
symmetrical nature of the complex was confirmed by the
NMR spectral pattern. The room temperature 31P-
NMR signals of the platinum-containing compounds 4
and 5 are detected as a sharp singlet flanked by platinum
satellites, in agreement with a trans configuration of the
bound phosphine ligands. The 31P-NMR resonance for
data may also imply an additional chargeÁtransfer
/
character due to the platinum centre, in line with the
recently reported compounds incorporating oligothie-
nyl-bridging units [7,9]. However, apart from an in-
crease in the molar extinction coefficients, there is no
significant variation in the lowest energy peak from 3 to
6 and 7.
2.3. Electrochemistry
The electrochemical properties of complexes 1Á7 were
/
6 is close to the value encountered for [(Ph3P)AuCꢀ
/
studied in CH2Cl2 at room temperature by means of
cyclic voltammetry and the redox data are collected in
Table 1. In each case, the complex is electroactive and
the cyclic voltammogram is dominated by one quasi-
reversible oxidation wave due to the ferrocenyl electro-
CRCꢀ
/
CAu(PPh3)] (d 43.55) [6f]. The formulae of these
compounds were successfully established by the intense
molecular ion peak in each of the FABMS.
The absorption spectral data of our new complexes
were recorded in CH2Cl2 and the data are given in Table
1. Except for the trimetallic compound 5, each of them
essentially displays three main structureless absorption
bands. As observed for other similar systems, the higher
energy intense bands below 400 nm in the near UV
phore that is present. An anodic shift of the ferroceneÁ
/
ferrocenium couple relative to the ferrocene standard is
caused by the unsaturation of the ethynyl groups which
renders the removal of electrons more difficult. When
the conjugation length is increased from 3 to 4Á7 upon
/
region are likely to arise from pÁ
/
p* electronic transition
capping the end group with an organometallic segment,
oxidation is favoured by the delocalization of charge
of the fluorenone group [6a,6e]. The broad low-energy
features account for the orange to red colors of these
ferrocenyl compounds. Introduction of the platinum(II)
segment in 4 and 5 is found to red-shift the lowest
energy bands and to increase the absorption intensity,
suggesting an enhancement in the extent of p-delocaliza-
tion through the platinum conjugated system that is
along the main chain through a dp0pp interaction
/
which leads to a lowering of the oxidation potentials.
The most significant cathodic shift of ca. 0.06 V (from
0.17 V in 3 to 0.11 V in 5) is noted in the most extended
Feꢂ
/
Ptꢂ
/
Fe complex 5, however, the two ferrocenyl end
groups do not exhibit an observable electronic commu-

20
W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á26
/
nication through the fluorenyl ring system in such case.
Considering the relative peak heights with respect to the
added ferrocene standard in the cyclic voltammogram,
complex 5 only undergoes a single-step two-electron
oxidation involving the concomitant oxidation of the
nated forms of 3 are bonded to a Pt(PBu3)2 unit in a
trans geometry to afford a rigid-rod molecule with an
˚
ironÁ
corresponding mean Feꢂ
platinum centre is square-planar with four ligand groups
in the coordination sphere and the PtꢂP distance is
2.2981(10) A. The alkynyl bond lengths span the narrow
/iron through-space separation of about 34 A. The
˚
/
Pt distance is ca. 17 A. The
two ferrocenyl subunits at a scan rate of 100 mV sꢁ1
Non-interacting diferrocenyl systems have previously
been reported for trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
CPt(PR3)2Cꢀ
C(h5-C5H4)Fe(h5-C5H5)] [10], trans-[Pd-
(PBu3)2{CꢀCC6H4Cꢀ
C(h5-C5H4)Fe(h5-C5H5)}2] [3a]
and C(C4H2S)mCꢀ
trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
CPt(PBu3)2CꢀC(C4H2S)mCꢀ
C(h5-C5H4)Fe(h5-C5H5)]
(mꢃ1Á3) [7]. The E1/2 value is slightly more anodic in 7
.
/
˚
˚
/
range of 1.169(3)Á1.189(3) A, which are comparable to
/
/
those found in the bithienyl-linked analogue [7]. The
nearly linear bond angles around the alkyne units
conform to the rigid and straight-chain nature of the
molecule. There are no short intermolecular contacts or
p-stacking of fluorenone units in the lattice of 5.
/
/
/
/
/
/
/
/
than in 6 because of the higher formal oxidation state of
mercury(II) than that of gold(I), which would hinder the
back-donation to p* in the former case.
Another redox event was also detected at higher
positive potentials in 4 and 5, which was absent in the
remaining complexes. We assign this to the irreversible
The structures of 6 and 7 belong to new heterometallic
compounds in which the isoelectronic fragments
Au(PPh3) and MeHg are each attached to the terminal
alkyne entity of 2-ethynyl-7-(2-ferrocenylethynyl)fluo-
ren-9-one, respectively. Variation of the end groups in
both cases does not have a great influence on the bond
parameters of the fluorenone unit. The geometry about
the Au(I) and Hg(II) centres is essentially linear and the
oxidation of the platinum moiety [Pt(II)0
/Pt(III)].
Fluorenone-based reduction waves were only encoun-
tered for the precursors 1b, 2 and 3 without the heavy
metal groups, which appear in the narrow range of
mean Pꢂ
of 177.7(8)8 in 6 as well as the Cꢂ
C angle of 178.5(9)8 are indicative
/
Auꢂ
/
C angle of 178.1(3)8 and Auꢂ
/
Cꢂ
/
C angle
/
HgꢂC angle of
/
0.73Á0.77 V.
/
179.0(4)8 and Hgꢂ
of sp hybridization in the metal atom and acetylenic
carbon [6f]. For 6, two independent molecules are
/
Cꢂ
/
2.4. Crystal structure analyses
associated with the asymmetric unit in the unit cell
˚
P bond length of 2.270 A is similar
to those observed in other alkynylgold(I) phosphines
[6f,8d,8e,8f,8g]. The alkynyl bond distances are char-
acteristic of other structurally similar metal acetylides
and the average Auꢂ
/
The molecular structures of complexes 3, 5, 6 and 7,
as determined by X-ray analyses, are depicted in Figs.
1Á/4, respectively. Pertinent bond parameters along with
some dihedral angles are listed in Tables 2Á/5. There are
[6f,8d,8e,8f,8g]. However, no short Au
/
Á Á Á
/
Au intermole-
two independent molecules per asymmetric unit in the
unit cell of 3 and each molecule consists of one ferrocene
unit appended to one end of 2,7-diethynylfluoren-9-one,
cular interactions are observed in the solid state of 6,
presumably because the sterically bulky ferrocenyl and
phenyl groups prevent the close approach of molecules.
We note that the nearest intermolecular contact arises
from the hydrogen bonding interaction between oxygen
leaving a terminal alkyne moiety at the other end. The
˚
1.192(4) A
C(27) bond length
˚
1.174(4) A due to
C(11)ꢂ
whereas the free alkyne C(26)ꢂ
appears slightly shorter at 1.160(5)Á
/
C(12) distance is typical at 1.186(4)Á
/
/
/
of the fluorenone ring and hydrogen on C-8 of the
˚
the libration effect [11]. For 5, there is a centrosymmetry
at the platinum centre and the crystal structure shows a
diferrocenyl end-capped species in which two deproto-
adjacent molecule (O(1B)
˚
H(25B) 2.466 A). Intermolecular Au
are also observed between gold atom and hydrogen
/
Á Á Á
/
H(70A) 2.549 A; O(2A)
/
Á Á Á
/
/
Á Á Á
/H interactions
Fig. 1. A perspective view of one molecule of 3, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á
/26
21
Fig. 2. A perspective view of 5, showing the atomic labelling scheme. Hydrogen atoms were omitted for clarity.
Fig. 3. A perspective view of one molecule of 6, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level.
Fig. 4. A perspective view of 7, showing the atomic labelling scheme. Thermal ellipsoids were drawn at the 25% probability level.
Table 2
˚
Selected bond lengths (A) and angles (8) for complex 3
Molecule 1
Molecule 2
Molecule 1
Molecule 2
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(11)ꢂ
/
C(1)
C(3)
C(5)
C(7)
C(9)
2.054(3)
2.042(3)
2.039(3)
2.060(3)
2.037(3)
1.186(4)
2.034(3)
2.021(3)
2.044(3)
2.042(3)
2.035(3)
1.192(4)
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(26)ꢂ
/
C(2)
C(4)
C(6)
C(8)
C(10)
2.040(3)
2.038(3)
2.049(3)
2.032(3)
2.045(3)
1.160(5)
2.024(3)
2.030(3)
2.031(3)
2.037(3)
2.020(3)
1.174(4)
/
/
/
/
/
/
/
/
/
C(12)
/
C(27)
C(11)ꢂ
/
C(12)ꢂ/C(13)
177.0(3)
178.9(3)
C(24)ꢂ
/
C(26)ꢂ/C(27)
179.1(4)
177.0(4)
Dihedral angles (8) between planes
A and B
B and C
1.6
5.2
2.0
7.8
A and C
5.5
7.7
Planes: A, C(1)ꢂ
C(22)ꢂC(23)ꢂC(24)ꢂ
/
C(2)ꢂ
/
C(3)ꢂ
/
C(4)ꢂ
/
C(5); B, C(6)ꢂ
/
C(7)ꢂ
/
C(8)ꢂ
/
C(9)ꢂ
/
C(10); C, C(13)ꢂ
/
C(14)ꢂ
/
C(15)ꢂ
/
C(16)ꢂ
/
C(17)ꢂ
/
C(18)ꢂ
/
C(19)ꢂ
/
C(20)ꢂ
/
C(21)ꢂ
/
/
/
/
C(25).

22
W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á26
/
Table 3
˚
Selected bond lengths (A) and angles (8) for complex 5
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(11)ꢂ
Pt(1)ꢂC(27)
/
C(1)
C(3)
C(5)
C(7)
C(9)
2.006(4)
2.032(3)
2.026(3)
2.042(2)
2.023(2)
1.189(3)
2.012(2)
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(26)ꢂ
Pt(1)ꢂP(1)
/
C(2)
C(4)
C(6)
C(8)
C(10)
2.021(3)
2.039(3)
2.038(2)
2.043(2)
2.0413(18)
1.169(3)
2.2981(10)
/
/
/
/
/
/
/
/
/
C(12)
/
C(27)
/
/
C(11)ꢂC(12)ꢂ
Pt(1)ꢂC(27)ꢂC(26)
/
/
C(13)
176.8(2)
178.33(18)
C(23)ꢂC(26)ꢂ
P(1)ꢂPt(1)ꢂC(27)
/
/
C(27)
174.7(2)
93.63(6)
/
/
/
/
Dihedral angles (8) between planes
A and B
0.5
A and C
C(10); C, C(13)ꢂ
1.5
B and C
C(19)ꢂC(20)ꢂ
1.2
C(21)ꢂ
Planes: A, C(1)ꢂ
/
C(2)ꢂ
/
C(3)ꢂ
/
C(4)ꢂ
/
C(5); B, C(6)ꢂ
/
C(7)ꢂ
/
C(8)ꢂ
/
C(9)ꢂ
/
/
C(14)ꢂ
/
C(15)ꢂ
/
C(16)ꢂ
/
C(17)ꢂ
/
C(18)ꢂ
/
/
/
/
C(22)ꢂC(23)ꢂC(24)ꢂ
/
/
/
C(25).
Table 4
Selected bond lengths (A) and angles (8) for complex 6
˚
Molecule 1
Molecule 2
Molecule 1
Molecule 2
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(11)ꢂ
Au(1)ꢂ
/
C(1)
C(3)
C(5)
C(7)
C(9)
2.061(12)
2.014(9)
1.941(14)
2.057(11)
1.951(11)
1.965(17)
2.018(7)
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(26)ꢂ
Au(1)ꢂ
/
C(2)
C(4)
C(6)
C(8)
1.962(18)
2.041(10)
2.002(11)
2.058(7)
1.991(14)
1.999(14)
2.104(13)
2.029(9)
/
/
/
2.019(10)
2.108(13)
1.946(10)
1.178(11)
1.970(7)
/
/
/
/
/
C(10)
C(27)
P(1)
2.030(7)
1.161(11)
2.2724(17)
1.995(10)
1.240(11)
2.268(2)
/
C(12)
1.192(10)
1.989(8)
/
/
C(27)
/
C(11)ꢂ
P(1)ꢂAu(1)ꢂ
/
C(12)ꢂ
/
C(13)
175.9(9)
178.7(3)
174.7(7)
177.5(3)
C(20)ꢂC(26)ꢂ
Au(1)ꢂC(27)ꢂ
/
/
C(27)
C(26)
174.6(8)
177.1(8)
175.2(9)
178.3(8)
/
/
C(27)
/
/
Dihedral angles (8) between planes
A and B
B and C
2.5
18.1
3.9
17.8
A and C
19.9
15.9
Planes: A, C(1)ꢂ
C(22)ꢂC(23)ꢂC(24)ꢂ
/
C(2)ꢂ
/
C(3)ꢂ
/
C(4)ꢂ
/
C(5); B, C(6)ꢂ
/
C(7)ꢂ
/
C(8)ꢂ
/
C(9)ꢂ
/
C(10); C, C(13)ꢂ
/
C(14)ꢂ
/
C(15)ꢂ
/
C(16)ꢂ
/
C(17)ꢂ
/
C(18)ꢂ
/
C(19)ꢂ
/
C(20)ꢂ
/
C(21)ꢂ
/
/
/
/
C(25).
Table 5
Selected bond lengths (A) and angles (8) for complex 7
˚
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(11)ꢂ
Hg(1)ꢂ
/
C(1)
C(3)
C(5)
C(7)
C(9)
2.031(10)
2.072(10)
2.057(10)
2.026(10)
2.009(9)
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
Fe(1)ꢂ
C(26)ꢂ
Hg(1)ꢂ
/
C(2)
C(4)
C(6)
C(8)
C(10)
2.054(9)
2.082(10)
2.014(9)
2.043(10)
2.025(8)
1.157(11)
2.041(9)
/
/
/
/
/
/
/
/
/
C(12)
1.222(12)
2.050(10)
/
C(27)
C(28)
/
C(27)
/
C(11)ꢂC(12)ꢂ
C(27)ꢂHg(1)ꢂ
/
/
C(13)
C(28)
177.2(10)
179.0(4)
C(19)ꢂC(26)ꢂ
Hg(1)ꢂC(27)ꢂC(26)
/
/
C(27)
178.9(11)
178.5(9)
/
/
/
/
Dihedral angles (8) between planes
A and B
3.5
A and C
C(10); C, C(13)ꢂ
25.6
B and C
C(18)ꢂC(19)ꢂC(20)ꢂ
22.4
Planes: A, C(1)ꢂ
/
C(2)ꢂ
/
C(3)ꢂ
/
C(4)ꢂ
/
C(5); B, C(6)ꢂ
/
C(7)ꢂ
/
C(8)ꢂ
/
C(9)ꢂ
/
/
C(14)ꢂ
/
C(15)ꢂ
/
C(16)ꢂ
/
C(17)ꢂ
/
/
/
/
C(21)ꢂ
/
C(22)ꢂC(23)ꢂC(24)ꢂ
/
/
/
C(25).
˚
O(1) (3.314 A)
atoms on the phenyl and ferrocenyl units (Au(1A)
H(89A) 3.053; Au(2A) H(44A) 3.187; Au(2A)Á Á Á
Á Á Á
H(2AB) 3.110 A). Likewise, there are no apparent
weak intermolecular Hg Hg interactions or p-stacking
Á Á Á
of the aromatic rings in 7. The closest intermolecular
/
Á Á Á
/
contacts in 7 are attributed to the Hg(1)/
Á Á Á
/
˚
/
/
/
/
and Hg(1)
C(alkyne) bond (Hg(1)ꢂ
longer than the AuꢂC(alkyne) bond in 6 but matches
with those in other known Hg(II) acetylide complexes
/
Á Á Á
/
H(6A) (3.224 A) interactions. The Hgꢂ
/
˚
˚
C(27) 2.050(10) A) appears
/
/
/
/

W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á
/26
23
˚
CH3 bond (2.041(9) A) is comparable to
[12]. The Hgꢂ
/
model 273A potentiostat. A conventional three-elec-
trode configuration consisting of a glassy-carbon work-
those of other related systems [13]. In all cases, the
fluorenonediyl ring system is planar and the cyclopen-
tadienyl rings of the ferrocenyl group are almost parallel
ing electrode, a Pt-wire counter electrode and a AgÁ
/
AgNO3 reference electrode (0.1 M in acetonitrile) was
used. The solvent in all measurements was deoxygenated
CH2Cl2 and the supporting electrolyte was 0.1 M
[Bu4N]PF6. Ferrocene was added as a calibrant after
each set of measurements and all potentials reported
with tilt angles lying in the range 0.5Á3.98.
/
3. Concluding remarks
were quoted with reference to the ferroceneÁ
/ferroce-
A new class of heterometallic bis- and poly(alkynyl)
complexes end-capped with a ferrocenyl moiety and
another transition metal (e.g. platinum, gold and
mercury) have been prepared in good yields. These
compounds were fully characterized by spectroscopic,
electrochemical and structural methods. Our results
show that delocalization of p electrons continues
through the metal centre to different extent and the
conjugation is greater for the Pt(II) complexes than the
Au(I) and Hg(II) species. The production of the
nium couple (taken as E1/2 0.17 V relative to AgÁ
ꢃ
/
ꢀ
/
/
AgNO3). The number of electrons transferred for each
compound was estimated 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.
4.2. Preparations of complexes
trimetallic acetylide complex 5 with a metalÁ
/metal
4.2.1. Synthesis of [(h5-C5H5)Fe(h5-C5H4)Cꢀ
(Rꢁfluoren-9-one-2,7-diyl) (1b)
2,7-Dibromofluoren-9-one (50 mg, 0.15 mmol) and
/CRBr]
through-space distance of over 3 nm provides us an
opportunity to investigate novel materials of nano-sized
dimensions and we are currently extending these pro-
mising synthetic paths in the search for a new series of
diacetylenic-based materials and other oligomeric
homologues of longer chain length and more repeat
units.
/
ethynylferrocene (32 mg, 0.15 mmol) in iPr2NHꢂ
/
CH2Cl2 (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 allowed to reflux 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
4. Experimental
preparative TLC separation on silica using hexaneÁ
CH2Cl2 (2:1, v/v) as eluent. The orange product 1b
(Rfꢃ0.37) was obtained in 45% yield (32 mg), accom-
panied by 20% of the known compound 2,7-bis(ferro-
/
4.1. General procedures
/
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 predried and distilled
from appropriate drying agents [14]. 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-
pounds ethynylferrocene [15], trans-[Pt(PEt3)2(Ph)Cl]
[16] and trans-[Pt(PBu3)2Cl2] [17] were prepared by the
reported procedures. Infrared spectra were recorded as
CH2Cl2 solutions in a CaF2 cell (0.5 mm path length) on
cenylethynyl)fluoren-9-one
(1a)
(Rfꢃ
/
0.27).
O) cmꢁ1
IR
1H-
(CH2Cl2): 2213 n(CꢀC), 1721 n(Cꢁ
/
/
.
NMR (CDCl3): d 4.25 (s, 5H, C5H5), 4.27 (t, 2H,
JHꢂH 1.8 Hz, C5H4), 4.52 (t, 2H, JHꢂH 1.8 Hz,
C5H4), 7.38 (d, 1H, JHꢂH 7.8 Hz, fluorenone), 7.45
(d, 1H, JHꢂH 7.8 Hz, fluorenone), 7.57Á7.63 (m, 2H,
ꢃ
/
ꢃ
/
ꢃ
/
ꢃ
/
/
fluorenone) and 7.74Á7.76 (m, 2H, fluorenone).
/
FABMS: m/z 468 (Mꢀ). Anal. Found: C, 64.02; H,
3.10. Calc. for C25H15BrFeO: C, 64.28; H, 3.24%.
4.2.2. Synthesis of [(h5-C5H5)Fe(h5-C5H4)Cꢀ
CSiMe3] (Rꢁfluoren-9-one-2,7-diyl) (2)
/
CRCꢀ
/
/
A mixture of 1b (46 mg, 0.10 mmol), Me3SiCꢀ
/
CH (20
i
a PerkinÁ/Elmer Paragon 1000 PC or Nicolet Magna 550
g, 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
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
shifts were quoted relative to SiMe4 (d 0). Fast atom
bombardment mass spectra were recorded on a Finni-
gan MAT SSQ710 mass spectrometer. Electronic ab-
sorption spectra were obtained with a Hewlett Packard
preparative TLC (Rfꢃ
v/v) as eluent to yield 2 as an orange solid (46 mg, 95%).
IR (CH2Cl2): 2213, 2153 n(CꢀC), 1721 n(Cꢁ
O) cmꢁ1
/
0.30) using hexaneÁCH2Cl2 (2:1,
/
8453 UVÁ/vis spectrometer. Cyclic voltammetry experi-
ments were done with a Princeton Applied Research
/
/
.

24
W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á26
/
1H-NMR (CDCl3): d 0.27 (s, 9H, Me), 4.26 (s, 5H,
C5H5), 4.28 (t, 2H, JHꢂH 1.2 Hz, C5H4), 4.52 (t, 2H,
JHꢂH 1.2 Hz, C5H4), 7.46 (d, 1H, JHꢂH 7.6 Hz,
fluorenone), 7.47 (d, 1H, JHꢂH 7.6 Hz, fluorenone),
7.78 (m, 2H,
Stirring was continued for 18 h and evaporation of the
volatile components left behind a reddish residue,
purification of which was accomplished by preparative
ꢃ
/
ꢃ
/
ꢃ
/
ꢃ
/
TLC using hexaneÁ
the red band (Rfꢃ0.24) was obtained product 5 and a
pure sample was isolated in 56% yield (24 mg) after
recrystallization from a hexaneÁCH2Cl2 mixture. IR
(CH2Cl2): 2213, 2092 n(CꢀC), 1716 n(Cꢁ
NMR (CDCl3): d 0.88Á0.96 (m, 18H, CH3), 1.44Á
(m, 12H, CH2CH3), 1.58Á1.61 (m, 12H, PCH2CH2),
2.12Á2.14 (m, 12H, PCH2), 4.26 (m, 14H, C5H5ꢀC5H4),
4.52 (t, 4H, JHꢂH 1.2 Hz, C5H4), 7.36Á7.41 (m, 6H,
fluorenone), 7.53Á7.56 (m, 4H, fluorenone) and 7.72 (m,
2H, fluorenone). 31P{1H}-NMR (CDCl3):
4.37
(1JPtꢂP 2316 Hz). FABMS: m/z 1422 (Mꢀ). Anal.
/CH2Cl2 (2:1, v/v) as eluent. From
7.58Á
/
7.62 (m, 2H, fluorenone) and 7.74Á
/
/
fluorenone). FABMS: m/z 484 (Mꢀ). Anal. Found: C,
74.10; H, 4.69. Calc. for C30H24FeOSi: C, 74.38; H,
4.99%.
/
1
/
/
O) cmꢁ1. H-
/
/1.49
4.2.3. Synthesis of [(h5-C5H5)Fe(h5-C5H4)Cꢀ
CH] (Rꢁfluoren-9-one-2,7-diyl) (3)
/
CRCꢀ
/
/
/
/
/
To a solution of 2 (24 mg, 0.05 mmol) in Et2O (10
cm3) was added K2CO3 (7 mg, 0.05 mmol) in MeOH (15
cm3). The mixture was stirred at room temperature (r.t.)
for 24 h. After evaporation of the solvent, the crude
product was dissolved in CH2Cl2 and chromatographed
ꢃ
/
/
/
d
ꢃ
/
Found: C, 65.52; H, 5.68. Calc. for C78H84Fe2O2P2Pt:
C, 65.87; H, 5.95%.
on silica plates (Rfꢃ
(2:1, v/v) to afford pure 3 as a red powder in 92% yield
(19 mg). IR (CH2Cl2): 3294 n(ꢀCH), 2209, 2106 n(Cꢀ
O) cmꢁ1. H-NMR (CDCl3): d 3.19 (s,
CH), 4.30 (m, 7H, C5H5ꢀC5H4), 4.56 (t, 2H,
1.8 Hz, C5H4), 7.48 (d, 2H, JHꢂH 7.2 Hz,
7.63 (m, 2H, fluorenone) and 7.76 (m,
/
0.25) eluting with hexaneÁCH2Cl2
/
/
/
1
C), 1721 n(Cꢁ
1H, Cꢀ
JHꢂH
fluorenone), 7.58Á
/
4.2.6. Synthesis of [(h5-C5H5)Fe(h5-C5H4)Cꢀ
CAu(PPh3)] (Rꢁfluoren-9-one-2,7-diyl) (6)
/
CRCꢀ
/
/
/
/
ꢃ
/
ꢃ
/
Au(PPh3)Cl (30 mg, 0.06 mmol) in MeOH (15 cm3)
was mixed with compound 3 (25 mg, 0.06 mmol) in
CH2Cl2 (5 cm3). To this solution mixture was added 3
cm3 of basic MeOH (0.60 mmol, prepared by dissolving
0.20 g of NaOH in 25 cm3 of MeOH). Within a few
minutes, a red solid precipitated from the homogeneous
solution. After stirring for 2 h, the solid was collected by
filtration, washed with MeOH and air-dried to furnish
an analytically pure sample of 6 in very high yield (47
/
2H, fluorenone). FABMS: m/z 412 (Mꢀ). Anal. Found:
C, 78.35; H, 3.68. Calc. for C27H16FeO: C, 78.66; H,
3.91%.
4.2.4. Synthesis of trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
fluoren-9-one-2,7-diyl) (4)
/
CRCꢀ
/
CPt(PEt3)2Ph] (Rꢁ
/
Compound 3 (82 mg, 0.20 mmol) and trans-
[Pt(PEt3)2(Ph)Cl] (113 mg, 0.20 mmol) were dissolved
i
in Pr2NH (15 cm3) and CH2Cl2 (15 cm3). After the
addition of CuI (1.5 mg), the red solution was stirred at
r.t. over 18 h. Concentration of the solution and
mg, 90%). IR (CH2Cl2): 2213, 2111 n(Cꢀ
O) cmꢁ1. 1H-NMR (CDCl3): d 4.26 (s, 5H, C5H5), 4.27
(t, 2H, JHꢂH 1.8 Hz, C5H4), 4.52 (t, 2H, JHꢂH 1.8
Hz, C5H4) and 7.41Á Ph).
/
C), 1719 n(Cꢁ
/
ꢃ
/
ꢃ
/
subsequent purification by silica TLC (Rfꢃ
hexaneÁCH2Cl2 (2:1, v/v) as eluent readily led to the
isolation of the title product 4 as a redÁorange crystal-
line solid in 56% yield (103 mg). IR (CH2Cl2): 2209,
2089 n(CꢀC), 1717 n(Cꢁ
O) cmꢁ1. 1H-NMR (CDCl3): d
1.08Á1.12 (m, 18H, CH3), 1.73Á1.77 (m, 12H, CH2),
4.25 (m, 7H, C5H5ꢀC5H4), 4.51 (t, 2H, JHꢂH 1.8 Hz,
C5H4), 6.81 (t, 1H, JHꢂH 7.2 Hz, Hpara of Ph), 6.97 (t,
2H, JHꢂH 7.2 Hz, Hmeta of Ph), 7.33 (t, 2H, JHꢂH 7.2
Hz, Hortho of Ph), 7.40 (m, 3H, fluorenone), 7.53Á7.55
(m, 2H, fluorenone) and 7.72 (m, 1H, fluorenone).
/
0.38) using
/
7.78 (m, 21H, fluorenoneꢀ
/
31P{1H}-NMR (CDCl3): d 43.19. FABMS: m/z 870
(Mꢀ). Anal. Found: C, 61.88; H, 3.28. Calc. for
C45H30AuFeOP: C, 62.09; H, 3.47%.
/
/
/
/
/
/
/
ꢃ
/
4.2.7. Synthesis of [(h5-C5H5)Fe(h5-C5H4)Cꢀ
CHgMe] (Rꢁfluoren-9-one-2,7-diyl) (7)
/
CRCꢀ
/
ꢃ
/
/
ꢃ
/
ꢃ
/
Addition of an excess of basic MeOH (0.50 mmol) to
a mixture of MeHgCl (13 mg, 0.05 mmol) in MeOH (15
cm3) and 3 (21 mg, 0.05 mmol) in CH2Cl2 (5 cm3) at r.t.
led to the precipitation of the desired product 7 as a fine
red powder. The solvents were decanted after 2 h and
the red solid was air-dried to give 52% yield (16 mg) of 7.
/
31P{1H}-NMR (CDCl3): d 11.04 (1JPtꢂP
ꢃ2636 Hz).
/
FABMS: m/z 920 (Mꢀ). Anal. Found: C, 58.44; H,
5.58. Calc. for C45H50FeOP2Pt: C, 58.76; H, 5.48%.
4.2.5. Synthesis of trans-[(h5-C5H5)Fe(h5-C5H4)Cꢀ
CRCꢀCPt(PBu3)2CꢀCRCꢀ
C(h5-C5H4)Fe(h5-C5H5)]
(Rꢁfluoren-9-one-2,7-diyl) (5)
/
IR (CH2Cl2): 2210, 2134 n(Cꢀ
1H-NMR (CDCl3): d 0.73 (s, 3H, JHgꢂH
Me), 4.25 (s, 5H, C5H5), 4.27 (t, 2H, JHꢂH
C5H4), 4.52 (t, 2H, JHꢂH 1.9 Hz, C5H4), 7.43Á
2H, fluorenone), 7.56Á7.61 (m, 2H, fluorenone) and
7.72Á7.77 (m, 2H, fluorenone). Anal. Found: C, 53.49;
H, 2.80. Calc. for C28H18FeHgO: C, 53.65; H, 2.89%.
/
C), 1717 n(Cꢁ
/
O) cmꢁ1
148.0 Hz,
1.9 Hz,
7.50 (m,
.
2
ꢃ
/
/
/
/
ꢃ
/
/
ꢃ
/
/
The compound trans-[Pt(PBu3)2Cl2] (20 mg, 0.03
/
mmol) and two molar equivalents of 3 (25 mg, 0.06
mmol) were stirred in a mixture of iPr2NHÁ
/
/
CH2Cl2 (30
cm3, 1:1, v/v) at r.t. in the presence of CuI (1.5 mg).

W.-Y. Wong et al. / Journal of Organometallic Chemistry 670 (2003) 17Á
/26
25
Table 6
Summary of crystal structure data for complexes 3, 5, 6and 7
3
5
6
7
Empirical formula
Molecular weight
Crystal size (mm3)
Crystal system
C
27H16FeO
412.25
0.32ꢂ
C78H84Fe2O2P2Pt
1422.18
C45H30AuFeOP
870.48
C28H18FeHgO
626.86
/0.19ꢂ/0.15
0.30ꢂ/0.20ꢂ/0.14
0.22ꢂ
/
0.13ꢂ
/
0.07
0.23ꢂ
/
0.09ꢂ0.07
/
Monoclinic
P21/c
Monoclinic
¯
Triclinic
¯
P1/
Monoclinic
P21/c
Space group
˚
/
P1/
/
a (A)
˚
11.6923(9)
28.279(2)
11.6327(10)
10.087(2)
10.493(2)
16.921(3)
88.46(3)
75.55(3)
81.47(3)
1715.2(6)
1.377
9.7888(5)
12.6542(6)
14.9629(7)
88.4880(10)
74.9320(10)
86.0330(10)
1785.37(15)
1.619
12.3155(10)
9.9751(8)
17.0672(13)
b (A)
˚
c (A)
a (8)
b (8)
g (8)
U (A )
Dcalc (g cmꢁ3
95.763(2)
95.901(2)
3
˚
3826.9(5)
1.431
8
2085.6(3)
1.996
4
)
Z
1
2.543
728
2
4.589
856
m (MoÁ
F(0 0 0)
u range (8)
/
Ka) (mmꢁ1
)
0.803
1696
8.066
1200
1.75Á
/27.54
1.96Á
/
27.50
1.41Á/25.00
2.37Á25.00
/
Reflections collected
Unique reflections
Rint
22 617
8584
0.0579
4153
523
10 051
7335
0.0321
6486
385
8901
7488
10 143
3648
0.0611
2213
281
0.0131
6620
883
Observed reflections [I ꢀ2s(I)]
No. of parameters
/
R1, wR2 [I ꢀ
R1, wR2 (all data)
Goodness-of-fit on F2
/
2s(I)]
0.0441, 0.0787
0.1116, 0.0939
0.826
0.0481, 0.1271
0.0530, 0.1306
1.001
0.0328, 0.0864
0.0378, 0.0901
0.920
0.0429, 0.0854
0.0831, 0.0954
0.898
ꢁ3
˚
Residual extrema in final diff. map (e A
)
0.393 to ꢁ0.363
/
2.108 to ꢁ1.646
/
1.217 to ꢁ0.708
/
1.337 to ꢁ0.841
/
5. Crystallography
bond lengths and angles) for the structural analysis
has been deposited with the Cambridge Crystallographic
Single crystals of 3, 5, 6 and 7 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 6. The
diffraction experiments were carried out at room
temperature on a Bruker Axs SMART 1000 CCD
Centre (Deposition No. 193382Á193385). 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).
area-detector diffractometer using graphite-monochro-
˚
mated Mo-Ka radiation (lꢃ0.71073 A). At the end of
/
Acknowledgements
data collection, no crystal decay was observed. The
collected frames were processed with the software SAINT
[18a], and an absorption correction was applied (SA-
DABS) [18b] to the collected reflections. The structures
were solved by direct methods (for 3, 6 and 7) and
Patterson method (for 5), and expanded by difference
Fourier syntheses using the software SHELTXL [19].
Structure refinements were made on F2 by the full-
matrix least-squares technique. In each case, all the non-
hydrogen atoms were refined with anisotropic displace-
ment parameters. The hydrogen atoms were placed in
their ideal positions and not refined.
Financial support from the Faculty Research Grants
of Hong Kong Baptist University (FRG/00-01/II-57) is
gratefully acknowledged.
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