Structural characterisation of a series of acetylide-functionalised oligopyridines and the synthesis, characterisation and optical spectroscopy of platinum di-ynes and poly-ynes containing oligopyridyl linker groups in the backbone

Article abstract of DOI:10.1039/b110658a

A series of trimethylsilyl-protected bis(ethynyl)oligopyridine derivatives Me₃SiC≡C-R-C≡C-SiMe₃ (R = 2,2′-bipyridine-5,5′-diyl (1a), 2,2′-bipyridine-6,6′-diyl (2a), 2,2′:6′,2″-terpyridine-6,6″-diyl (3a), 4′-phenyl-2,2′:6′,2″-terpyrid

Full text of DOI:10.1039/b110658a

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Structural characterisation of a series of acetylide-functionalised
oligopyridines and the synthesis, characterisation and optical
spectroscopy of platinum di-ynes and poly-ynes containing
oligopyridyl linker groups in the backbone
Muhammad S. Khan,*a Muna R. A. Al-Mandhary,a Mohammed K. Al-Suti,a
Abdul Khader Hisahm,a Paul R. Raithby,*b Birte Ahrens,b Mary F. Mahon,b Louise Male,b
Elisabeth A. Marseglia,*c Emilio Tedesco,c Richard H. Friend,c Anna Köhler,*c Neil Feederd
and Simon J. Teate
a Department of Chemistry, College of Science, Sultan Qaboos University,
P.O. Box 36 Al Khod 123, Sultanate of Oman
b Department of Chemistry, University of Bath, Claverton Down, Bath, UK BA2 7AY
c Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, UK CB3 0HE
d University Chemical Laboratory, University of Cambridge, Lensfield Road, Cambridge,
UK CB2 1EW
e CLRC Daresbury Laboratory, Daresbury, Warrington, UK WA4 4AD
Received 20th November 2001, Accepted 15th January 2002
First published as an Advance Article on the web 26th February 2002
᎐
᎐
᎐
A series of trimethylsilyl-protected bis(ethynyl)oligopyridine derivatives Me SiC᎐C–R–C᎐C–SiMe
᎐
3
3
(R = 2,2Ј-bipyridine-5,5Ј-diyl (1a), 2,2Ј-bipyridine-6,6Ј-diyl (2a), 2,2Ј:6Ј,2Љ-terpyridine-6,6Љ-diyl (3a),
4Ј-phenyl-2,2Ј:6Ј,2Љ-terpyridine-6,6Љ-diyl (4a)) has been synthesised and 2a–4a have been characterised
᎐
᎐
by single crystal X-ray crystallography. The corresponding terminal di-ynes H–C᎐C–R–C᎐CH (1b–4b) and
᎐
᎐
᎐
᎐
their dinuclear platinum() complexes trans-[(Et P) (Ph)Pt–C᎐C–R–C᎐C–Pt(Ph)(Et P) ] (1M–4M) have been
᎐
᎐
3
2
3
2
characterised spectroscopically and by single-crystal X-ray crystallography for 2M. Novel platinum() poly-yne
n
᎐
᎐
polymers trans-[Pt(PBu ) –C᎐C–R–C᎐C–] (1P–4P) containing the oligopyridyl linker groups in the backbone
᎐
᎐
3
2
n
have been synthesised by the CuI-catalysed dehydrohalogenation polycondensation reaction of 1b–4b and trans-
[(Bu3P)2PtCl2] in Pri2NH–CH2Cl2. The polymeric materials exhibit decreasing thermal stability with increasing
number of pyridine units in the linker group. In the absorption and phosphorescence spectra, the platinum()
poly-yne and di-yne complexes 1P, 1M show red shifts whereas the complexes 2P–3P, 2M–3M show blue shifts
of the S1 and T1 states. At room temperature, the phosphoresence spectra indicate some excimer formation
whereas at 10 K, only intra-chain emission occurs. The results of the photophysical studies are compared
with those obtained for other platinum()-containing poly-ynes and related organometallic polymers.
spin deposited in thick layers.9 Metal-containing poly-ynes are
Introduction
also potential candidates as low-dimensional conductors10 and
The last decade has witnessed a great deal of interest in the
scientific community towards organometallic polymers that
contain transition metals in the main chain.1 Among the variety
of organometallic polymers, conjugated metal-containing poly-
non-linear optical materials.11
Within this framework, we have been working on the design,
synthesis, chemistry and photophysics of ‘rigid-rod’ plat-
inum() poly-ynes. The conjugation of the ligand continues
through metal centres along the polymer chain since there is
mixing of π* ligand states and the lowest unoccupied metal 6p
states.2,12 The inclusion of platinum() in the polymer chain
introduces sufficient spin–orbit coupling to allow light emission
from the triplet excited state of the conjugated ligand.13–15 For
commercial exploitation of these materials and for controlled
application-oriented synthesis, a thorough understanding of
the structure–property relationship is necessary such that suit-
able modifications of the chemical structures may fine-tune the
electronic properties of the polymers.
We have recently investigated two series of platinum()-
containing poly-ynes. In one series the conjugated spacer R is
based on phenylene derivatives where little donor–acceptor
interaction occurs between the phenylene ring and platinum
centres along the rigid backbone of the organometallic poly-
mers.16 In the second series the spacer unit is based on electron-
rich oligothienyl rings which act as electron donors and the
platinum moieties act as electron acceptors.14,17 In an extension
᎐
᎐
ynes trans-[(L) M–C᎐C–R–C᎐C–] (M = group 8 or 10 metal,
᎐
᎐
x
∞
L = phosphine, x = 4 for group 8, 2 for group 10 metals; R = one
of a number of aromatic/heteroaromatic spacer groups) con-
stitute a particularly important class of new materials for basic
and applied research, since the various acetylide-functionalised
ligands can be easily synthesized and the alkynyl ligands can
be readily incorporated into metal-containing polymers. These
materials show a wide variety of properties useful for appli-
cation in modern technology. For example, the metal-contain-
ing poly-ynes provide model systems for the study of some of
the photophysical processes that occur in conjugated organic
polymers,2 are used in optoelectronic devices such as light
emitting diodes (LEDs),3 lasers,4 photocells,5 and field-effect
transistors (FETs).6 Group 10 metal-containing polymers with
a rigid conjugated backbone also show interesting alignment
properties in magnetic and electric fields,7 fast and reproducible
response to relative humidity variations in surface acoustic
wave (SAW) sensors,8 and molecular orientation even when
1358
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
This journal is © The Royal Society of Chemistry 2002
DOI: 10.1039/b110658a

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to this work, we have investigated a series of platinum() di-
ynes and poly-ynes with oligopyridyl linker groups in the back-
bone; the di-ynes can be considered as the molecular models
and building blocks for the high molecular weight poly-ynes.
The aim of the investigation is to establish in what way the
insertion of an oligopyridyl spacer unit affects the optical and
electronic properties of the platinum() poly-ynes compared to
related organometallic polymers.
A few recent reports have concerned the incorporation of
pyridine and its derivatives into conjugated polymeric frame-
works.18 Compared to benzene or thiophene, pyridine is
electron-deficient; consequently, the derived polymers have
increased electron affinity and improved electron-transporting
properties.19 The increase in the number of pyridine units may
enhance the electron-accepting ability of the polymers making
the oligopyridyl-containing polymers more suited for appli-
cation in electronic devices. It was therefore envisaged that
oligopyridines would constitute an interesting class of new
spacer units in the novel platinum() poly-yne systems. There is
also considerable interest in the solid-state structures of the
polymeric materials because of evidence for interchain inter-
actions that influence their electronic properties. In this context
an analysis of the intermolecular interactions in the crystal
structures of the ligand systems and of the model complexes
may lead to a better understanding of the interactions in the
polymers.20 Bearing these concepts in mind we set out to syn-
thesize a series of bis(acetylide)-functionalised oligopyridines
which can give dimeric and polymeric platinum() complexes.
Here, we report the structural characterization of a series of
bis(trimethylsilylethynyl)oligopyridine ligands 2a–4a and the
synthesis, characterisation and optoelectronic properties of a
series of platinum() poly-ynes containing oligopyridyl linker
groups. The synthesis and characterisation of related dimeric
model complexes are also reported. The crystal structure of a
selected diplatinum complex 2M is also described.
Scheme 1
n
᎐
trans-[Pt(PBu ) {C᎐C–RЈ} ] (RЈ
= 2,2Ј-bipyridine-4-yl or
᎐
3
2
2
2,2Ј:6Ј,2Љ-terpyridine -4-yl) have been reported previously.22
n
᎐
The corresponding polymers trans-[Pt(PBu ) –C᎐C–R–
C᎐C–] (1P–4P) were prepared by the reaction of one equiv-
᎐
3
2
᎐
᎐
n
alent of trans-[(Bu3P)2PtCl2] with the appropriate di-yne under
similar reaction conditions. Purification of the dimers 1M–4M
was accomplished by silica column chromatography while the
polymers 1P–4P were purified by alumina column chrom-
atography followed by precipitation from dichloromethane
solution into methanol.
Results and discussion
Syntheses
Spectroscopic characterisation
The bis(ethynyl)oligopyridine ligands were synthesised by a
sequence of coupling and proto-desilylation reactions. The tri-
methylsilyl-protected ligand precursors 1a–4a were synthesised
by adopting improved procedures21 for the palladium-catalyzed
coupling of trimethysilylethyne with dibromo-substituted oligo-
pyridines (Scheme 1). The protected di-ynes are indefinitely
stable towards light and air and were fully characterised by IR,
NMR (1H and 13C) spectroscopy, EI mass spectrometry as well
as by satisfactory elemental analyses and single crystal X-ray
crystallography for 2a–4a.
Systematic characterisation of the platinum() di-ynes and
poly-ynes was achieved by spectroscopic methods (IR, H, 13C
1
and 31P NMR). The IR spectra of the Pt() di-ynes and poly-
ynes show a single sharp νC᎐C absorption at around 2095 cmϪ1
᎐
consistent with a trans-configuration of the acetylenic units
around the Pt() centre. The νC᎐C values for the terminal di-ynes
1b–4b (2107 cmϪ1) are mu᎐ch lower than those of the
trimethylsilyl-substituted di-ynes 1a–4a (2157–2159 cmϪ1). The
᎐
fact that terminal ethynes (HC᎐C–R) have lower νC᎐C frequencies
᎐
᎐
Ϫ1
᎐
Conversion of the protected ligand precursors into their ter-
minal di-ynes 1b–4b was accomplished by smooth removal of
the trimethylsilyl protecting groups with dilute aqueous KOH
in MeOH–THF (Scheme 1). The products were purified by
silica column chromatography and characterised by elemental
analyses and by IR, NMR (1H and 13C) spectroscopy and mass
spectrometry. The terminal di-ynes are relatively stable at low
temperature in the absence of light and air; however, in the
presence of light and/or air they undergo a slow colour change.
Long storage times at ambient temperature and under aerobic
condition led to the formation of some insoluble material
(<5%), which was presumed to be a polymerisation product.
The synthesis of the platinum() di-yne complexes is outlined
in Scheme 2 and that of the platinum() poly-yne polymers is
outlined in Scheme 3. The reaction of each of the di-ynes with
two equivalents of the platinum complex trans-[Pt(Ph)(PEt3)2-
Cl], in CH2Cl2–NHPri2, in the presence of CuI, at room
temperature, readily affords the dimeric complexes trans-
than their protected counterparts RC᎐C–R (by about 50 cm
᎐
in this case) is well established.23 Furthermore, the platinum()-
containing compounds display lower νC᎐C values than those in
the corresponding trimethyl-substituted or terminal di-ynes.
This may be attributed to either metal-yne π-back bonding or
the Mδϩ–CδϪ polarity.24 The 1H and 13C NMR spectra of all the
compounds exhibit the expected signals for the systems includ-
ing resonances for the acetylenic carbons. The single resonance
in the 31P NMR spectra of all the platinum() dimers and
polymers confirms the trans arrangement of the phosphine
ligands. From the 31P{1H} NMR spectral data, it is clearly seen
1
that the JPt–P coupling constants for the di-ynes 1M–4M are
larger than those of the poly-ynes 1P–4P by about 300 Hz.
The mass spectrometric results confirm the molecular
assignments for the organic ligands and the platinum() di-yne
complexes. The weight-average molecular weights (Mw) of the
poly-ynes 1P–4P indicate high degree of polymerisation. The
number average molecular weight (Mn) values are in the range
of 60000 to 87000 g molϪ1, corresponding to between 75 and 91
repeating units per chain. The polydispersity (Mw/Mn) varies
᎐
᎐
[(Et P) (Ph)Pt–C᎐C–R–C᎐C–Pt(Ph)(Et P) ] (1M–4M), in good
᎐
᎐
3
2
3
2
yields. The related mono-nuclear Pt() σ-acetylide complexes
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
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Scheme 2
Scheme 3
between 1.3 and 1.8. The molecular weights should be viewed
tion to the red compared to the monopyridine analogues by
with caution in view of the difficulties associated with utilizing
gel permeation chromatography (GPC) for rigid-rod polymers.
GPC does not give absolute values of molecular weights but
provides a measure of hydrodynamic volume. Rod-like poly-
mers in solution possess very different hydrodynamic properties
than flexible polymers. Therefore, calibration of the GPC with
PS standards is likely to inflate the values of the molecular
weights of the poly-ynes to some extent. However, the lack of
discernable resonances that could be attributed to end groups in
the NMR spectra provides support for the view that there is
high degree of polymerization in these poly-ynes.
0.1 and 0.2 eV, respectively, while for 2P–4P and 2M–4M, the
onset of absorption is blue-shifted compared to the pyridine
analogues by 0.3 and 0.1 eV, respectively.
We note that even in the fully conjugated platinum() poly-
ynes containing pyridine-2,5-diyl12b or 2,2Ј-bipyridine-5,5Ј-diyl
(1P), the onset of absorption is not as low as in the analogous
n
᎐
᎐
platinum() poly-ynes trans-[Pt(PBu ) –C᎐C–R–C᎐C–] (R =
᎐
᎐
3
2
n
thiophene-2,5-diyl; 2,2Ј-bithiophene-5,5Ј-diyl).14 This suggests
stronger donor–acceptor interactions in the platinum() poly-
ynes containing thiophene spacers than for pyridine spacers.
Comparing the poly-ynes with their corresponding di-yne
complexes, we find the onset of absorption in 1P is 0.2 eV lower
than in 1M consistent with the extended conjugation in the
poly-yne compared to the di-yne complex. Similarly, the onset
of absorption in 2P–4P is 0.1 eV lower than in 2M–4M because
even in these kinked poly-ynes, a conjugated segment is still
longer than in the di-yne complexes. In the di-yne complexes,
the conjugation extends only from one oligopyridine ring to
the end-capping phenylene while the poly-yne is conjugated
from one oligopyridine ring over the platinum site to another
oligopyridine ring where the conjugation then terminates.The
spectral shapes of 1P and 1M are very similar to those of the
pyridine analogues and the first absorption band at 3–3.5 eV
is more intense than the higher-lying bands at and above 4 eV.
Optical spectroscopy
Fig. 1 shows the thin film absorption spectra of the platinum()
di-yne complexes 1M–4M and the corresponding poly-yne
complexes 1P–4P. We compare these spectra to those reported
for analogous platinum() di-yne and poly-yne (R = pyridine-
2,5-diyl) with an onset of absorption at 3.3 eV (376 nm) and
3.0 eV (413 nm), respectively.12b In 1P and 1M, the alkynyl
groups are at the 5,5Ј-positions and the compounds are fully
conjugated, while in 2P–4P and 2M–4M, the alkynyl groups
occur at the 6,6Ј- or 6,6Љ-positions hindering conjugation
between the pyridine rings. Correspondingly, for 1P and 1M the
addition of a second pyridine ring shifts the onset of absorp-
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J. Chem. Soc., Dalton Trans., 2002, 1358–1368

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vibrational peak of the phosphorescence band is 0.6 eV below
the onset of absorption as for the fully conjugated Pt-poly-
ynes,14,15 even though these compounds have their conjugation
disrupted by the unfavourable disposition of the alkynyl
groups. The reduced conjugation shifts the phosphorescence
band to the blue by 0.3 eV compared to the linear bipyridine-
containing analogues, so that the 0–0 vibrational peaks of the
10 K emissions are located around 2.68 eV (462 nm). In this
class of materials, this is the highest energy at which phosphor-
escence has been observed so far and correspondingly, accord-
ing to the energy gap law, it should be associated with the lowest
rate of non-radiative decay from the T1 state at 10 K. Com-
pared to linear bipyridine or p-phenylene-containing analogues,
he non-radiative decay rate should be reduced by a factor of 10.15
For Pt-poly-ynes and di-ynes with a T1 state at 2.2 eV or
higher the lifetime of the T1 emission is around or above 100
µs.15 This long lifetime allows for temperature-activated dif-
fusion of the T1 excitation to lower energy sites such as aggre-
gate sites or excimer sites which are only weakly emissive.26
From Fig. 2, there is some evidence for such diffusion. For
example, for 3P, the spectrum at 10 K has a well-resolved
vibronic structure with most weight in the 0–0 vibrational peak
at 2.69 eV. This spectral shape is characteristic of Pt-poly-
ynes.12b,15 In contrast, at room temperature the emission is
broad and unstructured. The 0–0 vibrational peak has dis-
appeared, and the emission is now centred further red at 2.2 eV.
This broad, unstructured, red-shifted low-intensity emission is
characteristic of an aggregate or excimer site.26 Similar progres-
sions occur for 1P, 2P and, to a weaker extent, for 2M and 3M.
In summary, using linear and kinked oligopyridine spacers in
the polymer backbone we obtain both red and blue shifts,
respectively, of the S1 and T1 states in platinum() di-yne and
poly-yne complexes. The blue shifts are associated with a loss of
oscillator strength in the first absorption band. The high energy
of the T1 state obtained by using the non-linear linkage in
the oligopyridine is expected to be associated with a low non-
radiative decay rate from the T1 state. This is desirable for
applications that harvest the T1 state for light emission.27–29
Fig.
1
The absorption spectra of films of the Pt() poly-yne
complexes 1P–4P (solid lines) and corresponding Pt() di-yne
complexes 1M–4M (dotted lines). The spectra are normalised to unity
at the peak of the first absorption band and they are displaced on the
vertical axis for clarity.
The first absorption band is mainly due to the π–π* transition
in the organic system, possibly with some admixture of metal
d orbitals which may alter the overall energy of the tran-
sition.12b,25 Consequently, the intensity of the first band is
reduced in comparison to the higher-lying bands when the
conjugation is interrupted by the kinked-spacers in 2P–4P.
The even shorter conjugation length in the di-yne complexes
2M–4M further reduces the relative intensity of the first band.
The photoluminescence (PL) spectra of the platinum()
di-yne complexes 1M–3M and poly-yne complexes 1P–3P,
measured at 300, 200, 100, 50 and 10 K are shown in Fig. 2. We
find the two emission bands with the 0–0 vibrational peaks of
the 10 K emissions at 2.91 eV (426 nm) and 2.18 eV (569 nm)
for 1P and at 3.10 eV (400 nm) and 2.22 eV (559 nm) for 1M.
The higher energy emission is fluorescence from the same sing-
let excited state as the first band in the absorption spectra, and
is denoted S1. We attribute the lower energy band to phosphor-
escence from a triplet excited state T1 for the following reasons.
The lower energy band has been assigned previously to phos-
phorescence in related poly-ynes and di-ynes on the basis of
lifetime and photoinduced absorption measurements.12a,15,25 It
was shown that for Pt-poly-ynes with many different spacers R
the 0–0 vibrational peak of the phosphorescence always occurs
0.7 eV below the 0–0 vibrational peak of the fluorescence.14,15,25
For 1P, the low energy band is 0.7 eV below the fluorescence,
and the 10 K spectrum shows a well-resolved vibronic struc-
ture and a spectral shape similar to the phosphorescence in
related compounds.12b,25 For 1M, the phosphorescence band
is at almost the same energy as in 1P in agreement with anal-
ogous compounds.15 The extended conjugation in the linear
bipyridine-containing compounds shifts the phosphorescence
to the red by 0.18 eV compared to the pyridine containing
analogues.
Thermal characterisation
Unlike the platinum() poly-ynes containing phenylene and
thienylene spacers, these materials did not exhibit discernable
glass transitions.14,16 A clear trend of decreasing decomposition
temperature was observed as the number of pyridine units was
increased from two to three. The differential thermal analysis
(DTA) data varied from material to material: the decom-
position peak was an exotherm for 1P and 2P, an endotherm
for 3P, and was too broad to a clearly discernable result in 4P.
A minor endotherm was also present in 1P at 151 ЊC; sim-
ilar endotherms were observed in thienylene and phenylene
analogues at somewhat higher temperatures.14,16 The thermo-
gravimetric (TG) data also showed variation. The mass loss in
3P was particularly sharp and over 50% of the sample mass was
lost as the temperature rose from 170 to 250 ЊC. Onset of
decomposition in 4P was difficult to establish, in that mass loss
began almost immediately in most samples tested, and occurred
over a broad range of temperature. Decomposition onset was
defined as a mass loss of 2%. The results are shown in Table 1.
Structural characterisation
Contents of the unit cell. The four structures reported show
a range of packing arrangements within the unit cell, some
employing the symmetry of the crystal lattice. 6,6Ј-Bis(2-
trimethylsilyl-1-ethynyl)-2,2Ј-bipyridine, 2a, crystallised with
two half molecules in the asymmetric unit. The central carbon–
carbon bond connecting the pyridine rings in each of the two
molecules lies on an inversion centre. The trimethylsilyl group
of one of these molecules shows disorder, the SiMe3 group was
refined over two sites with partial occupancies summing to
For the kinked bi and terpyridine-containing compounds 2P,
3P, 2M and 3M we observe no fluorescence band but only the
phosphorescence band. It is interesting to note that the 0–0
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
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Table 1 Results of thermal analysis; temperatures in ЊC
Compound
T decomp (onset)
T decomp (peak) DTG
T decomp (peak) DTA
1P
2P
3P
4P
274
287
169
—
325
343
236
212
326
344
234
—
Fig. 2 The photoluminescence spectra of films of the Pt() poly-ynes 1P–3P (a–c) and the corresponding Pt() di-yne complexes 1M–3M (d–f )
plotted on a logarithmic scale. All of the photoluminescence spectra give the correct relative intensities at 300 K, 200 K, 100 K, 50 K and 10 K.
unity. 6,6Љ-Bis(2-trimethylsilyl-1-ethynyl)-2,2Ј:6Ј,2Љ-terpyridine,
3a, crystallised with one molecule and 6,6Љ-bis(2-trimethyl-
silyl-1-ethynyl)-4Ј-phenyl-2,2Ј:6Ј,2Љ-terpyridine, 4a, with two
independent but structurally similar molecules in the asym-
metric unit. In contrast to the bis-trimethylsilyl derivative,
᎐
᎐
trans-[(Et P) (Ph)Pt–C᎐C–(2,2Ј-bipyridine-6,6Ј-diyl)–C᎐C–Pt-
᎐
᎐
3
2
(Ph)(PEt3)2] 2M crystallises with one independent molecule in
the asymmetric unit.
Fig. 3 The molecular structure of one of the two independent half
molecules of 2a (with the symmetry related half ). Only one orientation
of the disordered trimethylsilyl fragment is shown for clarity.
Molecular constitution. The molecular structures of the
compounds 2a–4a and 2M are shown in Figs. 3–6, respectively,
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J. Chem. Soc., Dalton Trans., 2002, 1358–1368

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Fig. 4 The molecular structure of 3a showing the atom numbering scheme adopted.
Fig. 5 The molecular structure of one of the two independent molecules of 4a showing the atom numbering scheme.
Fig. 6 The molecular structure of 2M showing the atom numbering scheme.
Table 2 Selected bond lengths [Å] and angles [Њ] for 2a Table 3 Selected bond lengths [Å] and angles [Њ] for 3a
N(1)–C(6)
C(4)–C(5)
C(7)–C(7)#1
N(11)–C(17)
C(15)–C(16)
1.341(4)
1.195(4)
1.482(7)
1.346(4)
1.457(4)
N(1)–C(7)
C(5)–C(6)
N(11)–C(16)
C(14)–C(15)
C(17)–C(17)#2
1.344(4)
1.457(4)
1.346(4)
1.199(4)
1.485(7)
C(4)–C(5)
1.206(3)
1.343(3)
1.494(3)
1.343(3)
1.338(3)
1.453(3)
C(5)–C(6)
N(1)–C(6)
N(2)–C(11)
C(15)–C(16)
N(3)–C(16)
C(21)–C(22)
1.457(3)
N(1)–C(10)
C(10)–C(11)
N(2)–C(15)
N(3)–C(20)
C(20)–C(21)
1.345(3)
1.343(3)
1.489(3)
1.347(3)
1.199(3)
C(6)–N(1)–C(7)
C(4)–C(5)–C(6)
C(14)–C(15)–C(16)
117.7(3)
178.9(3)
178.2(4)
C(5)–C(4)–Si(1)
C(16)–N(11)–C(17)
C(15)–C(14)–Si(11)
177.5(3)
117.3(3)
175.5(4)
C(5)–C(4)–Si(1)
171.6(2)
117.43(18)
118.0(2)
177.8(3)
C(4)–C(5)–C(6)
C(11)–N(2)–C(15) 117.72(19)
C(21)–C(22)–Si(2) 177.2(3)
176.6(2)
C(10)–N(1)–C(6)
C(20)–N(3)–C(16)
C(22)–C(21)–C(20)
Symmetry transformations used to generate equivalent atoms: #1 Ϫx ϩ
1, Ϫy ϩ 1, Ϫz ϩ 2; #2 Ϫx ϩ 2, Ϫy ϩ 2, Ϫz ϩ 2.
pyridine (117.3(2), 118.5(1)Њ).31 The carbon–carbon bonds
between the pyridine rings in 2a–4a (1.482(7)–1.496(6) Å) are
typical for a single bond between sp2-hybridized carbons, as in
quaterpyridine (1.485(2), 1.482(3) Å),31 in ph-A-bipy (1.496(6)
Å)30 or in terpy (1.474(9)–1.479(9) Å).32 The carbon–carbon
bonds between the sp2-hybridized pyridine ring and the
sp-hybridized ethynyl group are shorter (1.447(7)–1.457(4) Å in
2a–4a). These bond lengths are also in good correspondence
with those in ph-A-bipy (1.438(5) Å).30 The carbon–carbon
triple bonds in 2a–4a correspond to the expected value
and selected intramolecular bond parameters are listed in
Tables 2–5.
The nitrogen–carbon bond lengths in 2a, 3a and 4a are in the
range of 1.331(3)–1.351(5) Å. These bond lengths are similar to
those in 6,6Ј-bis(2-phenyl-1-ethynyl)-2,2Ј-bipyridine (= ph-A-
bipy), (1.337(4) and 1.351(4) Å),30 or in 2,2Ј:6Ј,2Љ:6Љ,2ٞ-
quaterpyridine (1.333(2)–1.340(2) Å).31 The C–N–C angles in
2a–4a (116.9(4), 117.7(3)Њ) are equivalent to those in the
uncoordinated ph-A-bipy compound (117.6(3)Њ)30 or in quater-
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
1363

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Table 4 Selected bond lengths [Å] and angles [Њ] for 4a
4a are slightly folded with respect to the N–p-C axis: the
dihedral angle between the two planes (N–o/m/p-C) in 4a are
3.5(4) and 2.8(4)Њ, cf. 0.8(3)Њ in 3a, the mean deviations from the
pyridine ring plane are 0.018 and 0.015 Å in 4a, cf. 0.007 Å in 3.
This is probably due to the phenyl ring attached to the pyridine
ring in para position in 4a. The dihedral angles between the
phenyl ring plane and the plane of the pyridine ring are 31.35(12)
and 30.68(12)Њ. This twist reduces the steric interactions between
the hydrogen atoms attached to the phenyl-and pyridine ring
and is notably larger than in 4Ј-phenyl-2,2Ј:6Ј,2Љ-terpyridine
(10.9Њ) or the corresponding Ni2ϩ complex (16.7, 17.8Њ).35
N(1)–C(1)
N(2)–C(6)
1.344(5)
1.338(5)
1.338(5)
1.343(5)
1.337(5)
1.344(5)
1.449(6)
1.492(6)
1.447(7)
1.208(6)
1.491(6)
N(1)–C(5)
1.347(5)
1.343(5)
1.351(5)
1.343(5)
1.349(5)
1.345(5)
1.496(6)
1.480(6)
1.204(6)
1.486(6)
1.451(7)
N(2)–C(10)
N(3)–C(21)
N(4)–C(32)
N(5)–C(37)
N(6)–C(52)
C(1)–C(6)
C(8)–C(11)
C(22)–C(23)
C(39)–C(42)
C(52)–C(55)
N(3)–C(17)
N(4)–C(36)
N(5)–C(41)
N(6)–C(48)
C(5)–C(22)
C(10)–C(17)
C(21)–C(24)
C(24)–C(25)
C(32)–C(37)
Crystal packing. From the nature of the molecules 2a to 4a
one could expect to find C–H ؒ ؒ ؒ N hydrogen bonds or π ؒ ؒ ؒ π
interactions in the crystal packing. However, with C ؒ ؒ ؒ N dis-
tances in the range of 3.522(6)–3.774(6) Å and the C–H ؒ ؒ ؒ N
angles generally below 150Њ (see Table 6) the assumption of a
hydrogen bond, even a non-classical, is, at least, arguable. A
proposed upper value for C ؒ ؒ ؒ N distances for this type of
hydrogen bond is 3.5 Å,36 cf. sum of the van der Waals radii
3.25 Å.37 On the other hand, as the resulting hydrogen bonding
motifs are meaningful, we favour the concept of hydrogen
bonds over pure van der Waals interactions in the most cases.
Except for 2a π ؒ ؒ ؒ π interactions were present in the crystal
packing (interlayer distances smaller than 3.5 Å).38
C(36)–C(53)
C(53)–C(54)
1.445(7)
1.203(6)
117.3(3)
116.9(4)
117.0(3)
176.0(5)
178.9(6)
177.3(6)
176.4(5)
C(41)–C(48)
C(55)–C(56)
1.495(6)
1.212(6)
117.8(3)
117.6(4)
117.6(3)
176.3(4)
177.3(5)
178.0(5)
175.1(5)
C(1)–N(1)–C(5)
C(17)–N(3)–C(21)
C(41)–N(5)–C(37)
C(23)–C(22)–C(5)
C(25)–C(24)–C(21)
C(54)–C(53)–C(36)
C(56)–C(55)–C(52)
C(6)–N(2)–C(10)
C(36)–N(4)–C(32)
C(48)–N(6)–C(52)
C(22)–C(23)–Si(1)
C(24)–C(25)–Si(2)
C(53)–C(54)–Si(3)
C(55)–C(56)–Si(4)
Table 5 Selected bond lengths [Å] and angles [Њ] for 2M
Pt(1)–P(1)
Pt(1)–C(1)
Pt(2)–P(3)
Pt(2)–C(14)
C(1)–C(2)
C(2)–C(3)
C(3)–N(1)
C(3)–C(4)
C(4)–C(5)
C(5)–C(6)
C(6)–C(7)
N(1)–C(7)
C(7)–C(8)
2.291(2)
2.022(9)
2.292(3)
Pt(1)–P(2)
Pt(1)–C(21)
Pt(2)–P(4)
2.287(2)
2.074(9)
2.286(3)
The molecules in 2a form criss-crossed, interlinked layers
perpendicular to (0 0 1). Within the layers weak C–H ؒ ؒ ؒ N
hydrogen bonds are present (N ؒ ؒ ؒ H 2.80, 2.91 Å). The com-
bination of those two hydrogen bonds forms a chain, motif
2.026(10)
1.199(13)
1.433(13)
1.352(13)
1.387(15)
1.384(14)
1.396(15)
1.386(13)
1.357(11)
1.498(13)
Pt(2)–C(31)
C(13)–C(14)
C(12)–C(13)
C(12)–N(2)
C(11)–C(12)
C(10)–C(11)
C(9)–C(10)
C(8)–C(9)
2.086(10)
1.195(14)
1.452(12)
1.354(12)
1.398(14)
1.377(13)
1.375(14)
1.387(13)
1.356(11)
2
C2 (8).39 The smallest interlayer distance between parallel
aromatic systems within one of the layers perpendicular to
(0 0 1) is 5.581(12) Å.
In 3a the shortest C ؒ ؒ ؒ N distance of 3.624(3) Å (angle
160.2Њ) is in direction of the stacks parallel to (1 0 0). Those
stacks also show small interplanar distances of 2.397(5) Å.
Between neighbouring stacks only weak forces are present. The
interplanar distance of 5.838(5) Å shows no indication of
π ؒ ؒ ؒ π interactions. On the other hand, two stacks could be
considered to be linked by weak C–H ؒ ؒ ؒ N hydrogen bonds
(CMe ؒ ؒ ؒ N 3.683(3) Å, CPh ؒ ؒ ؒ N 3.761(4) Å, angles 131.7 and
N(2)–C(8)
(1.195(4)–1.212(6) Å, cf. 1.189(5) Å in ph-A-bipy).30 The
ethynyl groups in 2a–4a show the expected linear arrangement
᎐
᎐
(C–C᎐C 176.0(5)–178.9(6)Њ, Si–C᎐C 171.6(2)–178.0(5)Њ, cf.
᎐
᎐
175.5(4), 180.0(4)Њ in ph-A-bipy.
2
The bond parameters within the organic spacer groups in
the diplatinum complex 2M does not show any significant
differences from those in the organic precursors. The Pt–
C(acetylenic) distances lie in the range 2.022(9)–2.026(10) Å,
which is within the range of values, 1.96(2)–2.05(2) Å, found in
related platinum di-yne complexes when the spacer group con-
sists of one or two thiophene rings.17 However, the distances are
consistently longer than the Pt–C(acetylenic) distances of
149.4Њ). These hydrogen bonds show ring motifs [N1: R2 (26)
2
and R2 (12), respectively]. The combination of these hydrogen
2
bonds results in the motif R2 (13).
In 4a the combination of π ؒ ؒ ؒ π interactions and weak
non-conventional hydrogen bonds results in a zigzag ribbon
arrangement parallel to the plane with trace (1 1 0) on the a/b-
plane. Within this ribbon small interplanar distances of
3.297(9) and 3.302(10) Å between symmetry related phenyl
rings of the two independent molecules could be found. Add-
itionally, those dimers are stabilised by C–H ؒ ؒ ؒ N hydrogen
bonds [C ؒ ؒ ؒ N 3.593(6), 3.554(6) Å, angles 148.9, 143.4Њ,
1.940(19) and 1.947(17)
Å
in the cis-complex [Pt(C-
t
33
᎐
᎐CC H Me) ( Bu bipy)].
The Pt–C(Ph) distances, range
᎐
6
4
2
2
2.074(9)–2.086(10) Å, and the Pt–P(phosphine) distances, range
2.286(7)–2.292(3) Å, are also quite similar to those observed in
the thiophene derivatives.17
2
motif R2 (20)]. Between two dimers additional, weak, non-
conventional hydrogen bonds are present, linking molecules
that are not related by symmetry [C ؒ ؒ ؒ N 3.522(6), 3.774(6) Å,
2
angles 129.8, 157.1Њ, combined motif R2 (18)].
Molecular conformation. 2a, 3a and 4a, and the metal
complex, 2M, showed the expected transoid conformation
for uncoordinated oligopyridines (torsion angles N–C–C–N
162.2(4)–180.0Њ).
In the crystal structure of 2M weak C–H ؒ ؒ ؒ N hydrogen
bonds are also observed (Table 6). However, the presence of the
bulky platinum-phosphine groups prevents π ؒ ؒ ؒ π interactions
from occurring.
The bipyridine moiety in the two independent molecules in
᎐
2a is exactly coplanar due to symmetry. The Si–C᎐C– groups lie
᎐
nearly within the bipyridine planes, Si deviation 0.217(8) and
Ϫ0.141(8) Å. The pyridine rings in the terpyridine moiety of 3a
are also twisted in respect of each other, showing dihedral
angles of 14.75(14) and 2.49(16)Њ. These dihedral angles differ
significantly from those in terpyridine (5.1, 7.2Њ).34 As in 2a,
Experimental
General procedures
All reactions were performed under a dry nitrogen atmosphere
using standard Schlenk or glove box techniques. Solvents were
pre-dried and distilled before use by standard procedures.40
All chemicals, except where stated otherwise, were obtained
from Sigma Aldrich and used as received. The com-
᎐
both Si–C᎐C– lie nearly within the plane of the attached
᎐
pyridine rings (Si deviation 0.223(6) and 0.278(6) Å). The
terpyridine moieties in the two independent molecules in 4a
show similar dihedral angles as in 3a (17.8(2), 3.1(2) and
15.0(2), 2.7(2)Њ). In contrast to 3a, the middle pyridine rings in
pounds
trans-[(Ph)(PEt3)2PtCl],41
trans-[(PBun )2PtCl2],42
3
6,6Ј-dibromo-2,2Ј-bipyridine,43 5,5Ј-dibromo-2,2Ј-bipyridine,44
1364
J. Chem. Soc., Dalton Trans., 2002, 1358–1368

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Table 6 C–H ؒ ؒ ؒ N hydrogen bonds and contacts, not corrected
Structure
Bond
D–H/Å
H ؒ ؒ ؒ A/Å
D ؒ ؒ ؒ A/Å
D–H ؒ ؒ ؒ A/Њ
2a
2a
C20–H20 ؒ ؒ ؒ N1
C10–H10 ؒ ؒ ؒ N11i
0.95
0.95
2.80
2.91
3.619(4)
3.660(4)
144.8
137.0
3a
3a
3a
C8–H8 ؒ ؒ ؒ N1ii
C13–H13 ؒ ؒ ؒ N1iii
C3–H3 ؒ ؒ ؒ N3iii
0.95
0.95
0.98
2.72
2.98
2.88
3.624(3)
3.683(3)
3.761(4)
160.2
131.7
149.4
4a
4a
4a
4a
C14–H14 ؒ ؒ ؒ N1iv
C45–H45 ؒ ؒ ؒ N6v
C34–H34 ؒ ؒ ؒ N1ii
C50–H50 ؒ ؒ ؒ N3ii
0.95
0.95
0.95
0.95
2.75
2.75
2.84
2.88
3.593(6)
3.554(6)
3.522(6)
3.774(6)
148.9
143.4
129.8
157.1
2M
2M
C43–H43b ؒ ؒ ؒ N1vi
C62–H62b ؒ ؒ ؒ N1vii
0.99
0.98
2.92
2.77
3.878(7)
3.375(7)
164.2
120.7
Symmetry operators: i 1 ϩ x, y, z; ii x Ϫ 1, y, z; iii 1 Ϫ x, 1 Ϫ y, 1 Ϫ z; iv Ϫ1 Ϫ x, 1 Ϫ y, 1 Ϫ z; v Ϫx, Ϫy, 1 Ϫ z; vi x, y ϩ 1, z, vii x, y Ϫ 1, z.
6,6Љ-dibromo-2,2Ј:6Ј,2Љ-terpyridine, and 6,6Љ-dibromo-4Ј-phen-
yl-2,2Ј:6Ј,2Љ-terpyridine45 were prepared via literature pro-
cedures. The NMR spectra were recorded on a Bruker WM-250
or AM-400 spectrometer in CDCl3. The 1H and 13C{1H} NMR
spectra were referenced to solvent resonances and 31P{1H}
NMR spectra were referenced to external trimethylphosphite.
Infrared spectra were recorded as CH2Cl2 solutions, in a NaCl
cell, on a Perkin-Elmer 1710 FT-IR spectrometer, mass spectra
on a Kratos MS 890 spectrometer by the electron impact (EI)
and fast atom bombardment (FAB) techniques. Microanalyses
were performed in the University Chemical Laboratory,
University of Cambridge. Preparative TLC was carried out on
commercial Merck plates with a 0.25 mm layer of silica. Col-
umn chromatography was performed either on Kieselgel 60
(230–400 mesh) silica gel or alumina (Brockman Grade II–III).
Thermal characterizations
Thermal analysis (DTA, and TG) of 1P–4P was performed
simultaneously in a Stanton-Redcroft model STA-780 Simul-
taneous Thermal Analyser under flowing N2. Sample masses
were ∼1 mg packed with ∼2 mg Al2O3 in open Inconel crucibles.
The reference crucible contained Al2O3. Samples were heated
at 10 ЊC minϪ1 to 465 ЊC. The thermocouple readings were
calibrated using a series of DTA standard materials: KNO3,
In, Sn, Ag2SO4 and K2SO4 as well as Pb and Al as secondary
standards, using the same heating rates as the samples.
Molecular weight measurements
Molar masses were determined by GPC47 using two PL Gel 30
cm, 5 µm mixed C columns at 30 ЊC running in THF at 1 cm3
minϪ1 with a Roth Mocel 200 high precision pump. A DAWN
DSP (Wyatt Technology) Multi-Angle Laser Light Scattering
(MALLS) apparatus with 18 detectors and auxiliary Viscotek
model 200 differential refractometer/viscometer detectors was
used to calculate the molecular weights (referred to GPC LS).
Optical characterisation
Thin films of the poly-ynes 1P–4P and of the dinuclear com-
plexes 1M–4M were spun from dichloromethane solution onto
quartz substrates using a conventional photoresist spin-coater.
Films were typically 100–150 nm in thickness as measured on a
Dektak profilometer. The optical absorption was measured
with a Hewlett-Packard ultraviolet-visible (UV-VIS) spectro-
meter. Measurements of photoluminescence (PL) were made
with the sample in a continuous-flow Helium cryostat. The
temperature was controlled with an Oxford-Intelligent tem-
perature controller-4 (ITC-4) and a calibrated silicon diode
adjacent to the sample. For PL measurements, excitation was
provided by the UV lines (334–365 nm) of a continuous wave
(CW) Argon ion laser. Typical intensities used were a few mW
mmϪ2. The emission spectra were recorded using a spectrograph
with an optical fibre input coupled to a cooled charge coupled
device (CCD) array (Oriel Instaspec IV).
Ligand synthesis
Bis(trimethylsilylethynyl)oligopyridines 1a–4a were prepared
by following a general procedure outlined below for 1a.
5,5Ј-Bis(trimethylsilylethynyl)-2,2Ј-bipyridine (1a). To a sol-
ution of 5,5Ј-dibromo-2,2Ј-bipyridine (2.0 g, 6.37 mmol) in
diisopropylamine–THF (60 cm3, 1 :1 v/v) under nitrogen was
added a catalytic mixture of CuI (15 mg), Pd(OAc)2 (16 mg)
and PPh3 (50 mg). The solution was stirred for 20 min at 50 ЊC
and then trimethylsilylethyne (2.24 cm3, 15.92 mmol) was added
and the mixture stirred for another 20 min. The temperature
was then raised to 75 ЊC and the reaction left under reflux with
stirring for 20 h. The completion of the reaction was deter-
mined by silica TLC and IR spectroscopy. The solution was
allowed to cool to room temperature, filtered and the solvent
mixture was removed. The residue was subjected to silica col-
umn chromatography using hexane–CH2Cl2 (1 :2, v/v) as eluent
X-Ray crystallography
For crystal data, see Table 7. Data collection and reduction:
the crystals were mounted in inert oil on a glass fibre. Data
were measured using Cu-Kα radiation (λ = 1.54178 Å) with a
Stoe STADI4 diffractometer (2a), or Mo-Kα radiation (λ =
0.71073 Å) with a Nonius Kappa area detector (3a, 4a), or a
Bruker AXS SMART CCD area detector on Station 9.8 of the
CLRC Daresbury Laboratory (2M), all fitted with an Oxford
Cryostream low-temperature attachment. Structure solution
and refinement: structures were solved by direct methods and
subjected to full-matrix least-squares refinement on F 2 (pro-
gram SHELXL-97).46 All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were included using rigid
methyl groups or a riding model.
to afford 1a as pale yellow needles (1.77 g, 80% yield). IR
(CH2Cl2): ν/cmϪ1 2159 (–C᎐C–). H NMR (250 MHz, CDCl ):
1
᎐
᎐
3
δ 8.70 (dd, J = 2.0, 0.7 Hz, 2H, H6,6Ј), 8.34 (t, J = 8.2, 0.76 Hz,
2H, H3,3Ј), 7.84 (dd, J = 8.1, 2.1 Hz, 2H, H4,4Ј), 0.27 (s, 18H,
SiMe3 × 2). 13C NMR (100 MHz, CDCl3): δ 154.18 (C2,2Ј),
152.04 (C6,6Ј), 139.73 (C3,3Ј), 120.44 (C4,4Ј), 120.32 (C5,5Ј), 101.75,
ϩ
᎐
99.42 (C᎐C), Ϫ0.18 (SiMe ). EI-mass spectrum: m/z 349 (M ).
᎐
3
Calc. for C20H24Si2N2: C, 68.94; H, 6.94; N, 8.04. Found: C,
68.88; H, 6.91; N, 7.98%.
CCDC reference numbers 174647–174650.
See http://www.rsc.org/suppdata/dt/b1/b110658a/ for crystal-
lographic data in CIF or other electronic format.
6,6Ј-Bis(trimethylsilylethynyl)-2,2Ј-bipyridine (2a). Off-white
1
solid (72% yield). IR (CH2Cl2): ν/cmϪ12159 cmϪ1 (–C᎐C–). H
᎐
᎐
NMR (250 MHz, CDCl3): δ 8.40 (2H, dd, J = 8.0, 1.0 Hz, H3,3Ј),
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
1365

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Table 7 Crystallographic data
Compound
2a
3a
4a
2M
Formula
Mr
Crystal habit
Crystal size/mm
Crystal system
Space group
C20H24N2Si2
348.59
Colourless block
0.40 × 0.30 × 0.20
Monoclinic
P21/c
C25H27N3Si2
425.68
Colourless prism
0.28 × 0.16 × 0.07
Triclinic
¯
P1
C31H31N3Si2
501.77
Colourless plate
0.20 × 0.18 × 0.06
Triclinic
¯
P1
C50H76N2P4Pt2
1219.19
Yellow needle
0.10 × 0.02 × 0.01
Monoclinic
P21/c
a/Å
b/Å
c/Å
α/Њ
11.024(3)
10.645(4)
17.768(4)
90
92.68(3)
90
2082.8(11)
4
1.556
6.3543(8)
10.844(2)
17.722(4)
84.891(8)
86.268(10)
82.049(10)
1202.8(4)
2
11.389(6)
13.353(11)
19.540(16)
94.69(3)
99.71(5)
90.48(5)
2918(4)
4
23.540(7)
9.389(3)
25.662(7)
90
116.005(14)
90
5097(3)
4
5.642
β/Њ
γ/Њ
U/Å3
Z
µ/mmϪ1
0.163
0.145
T /ЊC
2θmax/Њ
Ϫ93
110
Ϫ123
55
Ϫ93
45
Ϫ123
50
Wavelength/Å
No. of reflections measured
Independent
Rint
Parameters
Restraints
wR2 (F 2, all refl.)
R1[F > 2σ(F)]
GoF
1.54178
4267
2016
0.017
223
18
0.142
0.052
1.079
0.71073
7566
5373
0.041
277
14
0.1248
0.056
0.71073
13311
7470
0.064
649
0.68980
26831
9734
0.069
535
0
0
0.209
0.070
1.024
0.1508
0.0611
1.286
0.937
7.74 (2H, t, J = 7.80 Hz, H4,4Ј), 7.45 (2H, dd, J = 7.7, 1.0 Hz,
H5,5Ј), 0.28 (18H, s, SiMe3 × 2). 13C NMR (100 MHz, CDCl3):
to column chromatography on silica using hexane–CH2Cl2
(1 :1, v/v) as eluent to afford a white solid identified as 1b
(0.31 g, 76%). IR(CH2Cl2): ν/cmϪ1 3300 (C᎐C–H), 2107 (–C᎐
᎐
1
᎐
᎐
δ 155.70 (C2,2Ј), 142.34 (C6,6Ј), 136.91 (C3,3Ј), 127.77 (C4,4Ј),
᎐
᎐
121.09 (C5,5Ј), 103.95, 94.51 (C᎐C), Ϫ0.31 (SiMe ). EI-mass
C–). H NMR (250 MHz, CDCl3) δ: 8.74 (dd, J = 2.0 Hz, 2H,
H6,6Ј), 8.36 (t, J = 8.2 Hz, 2H, H3,3Ј), 7.88 (dd, J = 8.2, 2.1 Hz,
᎐
3
spectrum: m/z 348 (Mϩ). Calc. for C20H24Si2N2: C, 68.94; H,
2H, H4,4Ј), 3.16 (s, 2H, C᎐NC–H). 13C NMR (100 MHz,
᎐
6.94; N, 8.04. Found: C, 69.10; H, 6.89; N, 8.07%.
᎐
CDCl3): δ 155.66 (C2,2Ј), 152.30 (C6,6Ј), 140.60 (C3,3Ј), 120.79
᎐
6,6Љ-Bis(trimethylsilylethynyl)-2,2Ј:6Ј,2Љ-terpyridine (3a). Off-
(C4,4Ј), 120.42 (C5,5Ј), 83.14 (C᎐C). EI-mass spectrum: m/z 204
᎐
1
white solid (75% yield). IR (CH2Cl2): ν/cmϪ1 2159 (–C᎐C–). H
(Mϩ). Calc. for C14H8N2: C, 82.33; H, 3.95; N, 13.72. Found:
C, 82.29; H, 3.98; N, 13.69%.
᎐
᎐
NMR (250 MHz, CDCl3): δ 8.53 (dd, J = 8.0, 0.9 Hz, 2H, H3,3Љ),
8.51 (d, J = 7.8 Hz, 2H, H3Ј,5Ј), 7.92 (t, J = 7.8 Hz, 1H, H4Ј), 7.78
(t, 2H, J = 8.0 Hz, H4,4Љ), 7.49 (dd, 2H, J = 7.8, 0.9 Hz, H5,5Љ),
0.28 (s, 18H, SiMe3 × 2). 13C NMR (100 MHz, CDCl3): δ 156.29
6,6Ј-Bis(ethynyl)-2,2Ј-bipyridine (2b). White solid, 60% yield.
1
IR (CH2Cl2): ν/cmϪ1 2107 (–C᎐C–), 3299 (C᎐C–H). H NMR
᎐
᎐
᎐
᎐
(C2Ј,6Ј), 154.38 (C2Љ,2), 142.30 (C6Љ,6), 137.67 (C4Ј), 136.69 (C4Љ,4),
(250 MHz, CDCl3) δ: 8.46 (dd, 2H, J = 8.0, 0.99 Hz, H3,3Ј), 7.76
᎐
127.41 (C5Љ,5), 121.67 (C5), 120.42 (C3,3Љ), 103.84, 94.34 (C᎐C),
᎐
(t, 2H, J = 7.81 Hz, H4,4Ј), 7.50 (dd, 2H, J = 7.68, 1.03 Hz, H5,5Ј),
Ϫ0.10 (SiMe3). EI-mass spectrum: m/z 426 (Mϩ). Calc. for
C25H27N3Si2: C, 70.57; H, 6.40; N, 9.88. Found: C, 70.42; H,
6.48; N, 9.91%.
3.16 (s, 2H, C᎐C–H). 13C NMR (100 MHz, CDCl3): δ 155.66
᎐
᎐
(C2,2Ј), 141.60 (C6,6Ј), 137.11 (C3,3Ј), 127.79 (C4,4Ј), 121.32 (C5,5Ј),
ϩ
᎐
82.94 (C᎐C). EI-mass spectrum: m/z 204 (M ). Calc. for
᎐
C14H8N2: C, 82.33; H, 3.95; N, 13.72. Found: C, 82.28; H, 3.99;
N, 13.76%.
6,6Љ-Bis(trimethylsilylethynyl)-4Ј-phenyl-2,2Ј:6Ј,2Љ-terpyridine
(4a). White solid (90% yield). IR (CH2Cl2): ν/cmϪ1 2159
1
᎐
(–C᎐C–). H NMR (250 MHz, CDCl ): δ 8.74 (s, 2H, H3Ј,5Ј),
᎐
3
6,6Љ-Bis(ethynyl)-2,2Ј:6Ј,2Љ-terpyridine (3b). White solid, 65%
8.56 (dd, J = 8.0, 1.0 Hz, 2H, H3,3Љ), 7.88 (td, J = 6.7, 1.6 Hz, 2H,
Hortho for Ph), 7.80 (t, J = 8.0 Hz, 2H, H4,4Љ), 7.50(dd, J = 8.0, 1.0
Hz, 2H, H5,5Љ), 7.4–7.5 (m, 3H, Hmeta and para for Ph), 0.39 (s, 18H,
SiMe3 × 2). 13C NMR (100 MHz, CDCl3): δ 156.41 (C2Ј,6Ј),
155.00 (C2Љ2), 150.43 (C4Ј), 142.33 (C6Љ,6), 138.42 (Cpara for Ph),
1
yield. IR(CH2Cl2): ν/cmϪ1 3298 (C᎐C–H), 2105 (–C᎐C–). H
᎐
᎐
᎐
᎐
NMR (250 MHz, CDCl3): δ 8.56 (dd, J = 8.0, 1.0 Hz, 2H, H3,3Љ),
8.54 (d, 2H, J = 7.9 Hz, H3Ј,5Ј), 7.95 (t, J = 7.9 Hz, 1H, H4Ј), 7.81
(t, 2H, J = 8.0 Hz, H4,4Љ), 7.51 (2H, dd, J = 7.8, 0.9 Hz, H5,5Љ), 3.2
ϩ
᎐
(s, 2H, C᎐C–H). EI-mass spectrum: m/z 28 (M ). Calc. for
᎐
136.80 (C4Љ,4), 128.79 (Cortho for Ph), 127.56 (C5Љ5), 127.35 (Cmeta
C19H11N3: C, 81.12; H, 3.94; N, 14.94. Found: C, 81.09; H, 3.99;
N, 14.98%.
᎐
for Ph), 121.08 (C5Ј), 120.77 (C3,3Љ), 103.96, 94.47 (C᎐C), Ϫ0.30
᎐
(CH3). EI-mass spectrum: m/z 501 (Mϩ). Calc. for C31H31N3-
Si2: C, 74.22; H, 6.23; N, 8.38. Found: C, 74.19; H, 6.27;
N, 8.29%.
6,6Љ-Bis(ethynyl)-4Ј-phenyl-2,2Ј:6Ј,2Љ-terpyridine (4b). White
solid, 85% yield. IR(CH2Cl2): ν/cmϪ1 3298 (C᎐C–H), 2106 (–C᎐
᎐
᎐
Bis(ethynyl)oligopyridines 1b–4b were prepared by the
general procedure outlined below for 1b.
᎐
᎐
1
C–). H NMR (250 MHz, CDCl3): δ 8.75 (s, 2H, H3Ј,5Ј), 8.61
(dd, J = 8.0, 1.0 Hz, 2H, H3,3Љ), 7.86 (td, 2H, J = 6.7, 1.6 Hz,
Hortho for Ph), 7.83 (2H, t, J = 8.0 Hz, H4,4Љ), 7.52 (2H, dd, J =
8.0, 1.0 Hz, H5,5Љ), 7.46–7.44 (3H, m, Hmeta and para for Ph), 3.20 (s
5,5Ј-Bis(ethynyl)-2,2Ј-bipyridine (1b). 5,5Ј-Bis(trimethylsilyl-
ethynyl)-2,2Ј-bipyridine (1a) (0.696 g, 2.0 mmol) was proto-
desilylated in THF–methanol (50 cm3, 4 :1, v/v) using aqueous
KOH (0.36 g, 6.6 mmol in 1 cm3 water). The reaction mixture
was stirred at room temperature for 2 h during which time IR
and TLC showed that all protected compound had been con-
verted to the terminal alkyne. The solvent mixture was then
removed and the residue was dissolved in CH2Cl2 and subjected
2H, C᎐C–H). 13C NMR (100 MHz, CDCl3): δ 156.61 (C2Ј,6Ј),
᎐
᎐
155.02 (C2Љ,2), 150.63 (C4Ј), 141.66 (C6Љ,6), 138.33 (Cpara for Ph),
136.98 (C4Љ,4), 128.94 (Cortho for Ph), 127.61 (C5Љ, 5), 127.46 (Cmeta
᎐
for Ph), 121.19 (C5Ј), 119.69 (C3,3Љ), 83.12 (C᎐C). EI-mass spec-
᎐
trum: m/z 357 (Mϩ). Calc. for C25H15N3: C, 84.01; H, 4.23; N,
11.76. Found: C, 83.92; H, 4.18; N, 11.81%.
1366
J. Chem. Soc., Dalton Trans., 2002, 1358–1368

View Online
Complex preparations
(C Ph), 136.10 (C4Љ,4), 128.70, 127.20 (C Ph), 125.82 (C5Љ,5),
᎐
121.30(C5Ј), 118.77 (C3,3Љ), 116.54, 111.46 (C᎐C), 15.11 (t,
᎐
The di-yne complexes 1M–4M were synthesized by the general
procedure outlined below for 1M.
PCH2CH3), 8.06 (CH3). 31P{1H} NMR (101.3 MHz, CDCl3):
1
δ Ϫ131.12, JPt–P = 2659 Hz. FAB-MS: 1373 (Mϩ). Calc. for
C61H83N3P4Pt2: C, 53.38; H, 6.09; N, 3.06. Found: C, 53.65;
H, 5.98; N, 3.03%.
᎐
᎐
᎐
trans-[(Ph)(Et P) Pt–C᎐C–R–C᎐C–Pt(PEt ) (Ph)] (R ؍ 2,2Ј-
᎐
3
2
3 2
bipyridine-5,5Ј-diyl, 1M). To a stirred solution trans-[(PEt3)2(Ph)-
PtCl] (0.543 g, 1.0 mmol) and 5,5Ј-bis(ethynyl)-2,2Ј-bipyridine
(1b) (0.102 g, 0.50 mmol) in CH2Cl2–iPr2NH (50 cm3, 1 : 1 v/v)
under nitrogen was added a catalytic amount (∼5 mg) of CuI.
The yellow solution was stirred at room temperature for 15 h,
after which all volatile components were removed under
reduced pressure. The residue was dissolved in CH2Cl2 and
passed through a silica column eluting with hexane–CH2Cl2
(1 : 1, v/v). Removal of the solvents in vacuo gave the title com-
plex as off-white solid (0.43 g, 70%). IR (CH2Cl2): ν/cmϪ1 2093
Polymer preparations
The poly-yne complexes 1P–4P were synthesized by the general
procedure outlined below for 1P.
᎐
᎐
᎐
trans-[–(Bu P) Pt–C᎐C–R–C᎐C–] (R ؍ 2,2Ј-bipyridine-5,5Ј-
᎐
3
2
n
diyl, 1P). CuI (5 mg) was added to a mixture of trans-[Pt-
(PBun )2Cl2] (0.670 g, 1.0 mmol) and 1b (0.204 g, 1 mmol) in
3
Pri2NH–CH2Cl2 (50 cm3, 1 : 1 v/v). The solution was stirred at
room temperature for 15 h, after which all volatile components
were removed under reduced pressure. The residue was dis-
solved in CH2Cl2 and passed through a short alumina column.
After removal of the solvent by a rotary evaporator, an off-
white film was obtained readily which was then washed with
methanol to give the polymer 1P in 85% isolated yield (0.680 g).
Further purification can be accomplished by precipitating the
1
᎐
(–C᎐C–). H NMR (250 MHz, CDCl ): δ 8.57 (d, 2H, J = 7.8,
᎐
3
0.99 Hz, H6,6Ј), 8.18 (dd, 2H, J = 8.2, 0.76 Hz, H3,3Ј), 7.60 (dd,
2H, J = 8.2, 2.1 Hz, H4,4Ј), 7.31 (t, 4H, J = 7.7 Hz, Hortho Ph), 6.95
(t, 4H, J = 7.4 Hz, Hmeta Ph), 6.80(t, 4H, J = 7.3 Hz, Hpara Ph),
1.75 (m, 24H, PCH2), 1.10 [(t, 36H, P(CH2)CH3)]. 13C NMR
(100 MHz, CDCl3): δ 155.80 (C2,2Ј), 151.46 (C6,6Ј), 139.02 (C3,3Ј),
137.94–121.37 (C Ph), 120.14 (C4,4Ј), 119.80 (C5,5Ј), 117.13,
107.41 (C᎐C), 15.08 (PCH CH ), 8.00 (CH ).). 31P{1H} NMR
᎐
polymer from dichloromethane solution in methanol. IR
᎐
2
3
3
1
(CH2Cl2): ν/cmϪ1 2096 (–C᎐C–). H NMR (250 MHz, CDCl ):
1
᎐
(101.3 MHz, CDCl3): δ Ϫ131.17, JPt–P = 2677 Hz. FAB-MS:
1219 (Mϩ). Calc. for C50H76N2P4Pt2: C, 49.25; H, 6.28; N, 2.30.
Found: C, 49.18; H, 6.34; N, 2.28%.
᎐
3
δ 8.54 (s, 2H, H6,6Ј), 8.18 (d, 2H, J = 7.2 Hz, H3,3Ј), 7.50 (d, 2H,
J = 7.2 Hz, H4,4Ј), 2.13 [m,12H, PCH2(CH2)2(CH3)], 1.64
[(br s, 12H, PCH2(CH2)2(CH3)], 1.44 [(sextet,12H, PCH2-
(CH2)2(CH3)], 0.91 [(t, 18H, P(CH2)3CH3]. 13C NMR (100
MHz, CDCl3): δ 154.86 (C2,2Ј), 151.42 (C6,6Ј), 138.06 (C3,3Ј),
᎐
᎐
᎐
trans-[(Ph)(Et P) Pt–C᎐C–R–C᎐C–Pt(PEt ) (Ph)] (R ؍ 2,2Ј-
᎐
3
2
3 2
bipyridine-6,6Ј-diyl, 2M). Pale yellow solid (70% yield). IR
(CH2Cl2): ν/cmϪ1 2095 (–C᎐C–). H NMR (250 MHz, CDCl ):
1
᎐
᎐
120.61 (C4,4Ј), 120.30 (C5,5Ј), 116.68, 108.40 (C᎐C), 28.72–23.71
᎐
3
᎐
(PCH2CH2CH2CH3), 13.78 (CH3). 31P{1H} NMR (101.3 MHz,
CDCl3): δ Ϫ137.87, 1JPt–P = 2353 Hz. Calc. for (C38H60N2P2Pt)n:
C, 56.91; H, 7.54; N, 3.49. Found: C, 57.02; H, 7.67; N, 3.52%.
δ 8.22 (d, 2H, J = 7.8, 0.99 Hz, H3,3Ј), 7.56 (t, 2H, J = 7.81 Hz,
H4,4Ј), 7. 33 (d, 4H, J = 7.0 Hz, Hortho for Ph), 7.16 (d, 2H, J =
7.6 Hz, H5,5Ј), 6.87 (t, 4H, J = 7.4 Hz, Hmeta Ph), 6.80(t, 2H, J =
7.4 Hz, HparaPh), 1.79 (m, 24H, PCH2), 1.12 [(t, 36H,
P(CH2)CH3)]. 13C NMR (100 MHz, CDCl3): δ 155.93 (C2,2Ј),
146.72 (C6,6Ј), 139.13 (C3,3Ј), 135.83 (C Ph), 127.32 (C4,4Ј), 125.67
GPC (THF): Mn = 68,900 g molϪ1 (n = 86), Mw = 89570 g molϪ1
polydispersity = 1.3.
,
᎐
᎐
᎐
᎐
trans-[–(Bu P) Pt–C᎐C–R–C᎐C–] (R ؍ 2,2Ј-bipyridine-6,6Ј-
(C Ph), 121.29 (d, C5,5Ј), 118.13 (C Ph), 117.47, 110.40 (C᎐C),
᎐
3
2
n
᎐
diyl, 2P). Off-white solid (85% yield). IR (CH2Cl2): ν/cmϪ1 2095
13.62 (PCH2CH3), 8.20(CH3)). 31P{1H} NMR (101.3 MHz,
(–C᎐C–). 1H NMR (250 MHz, CDCl3): δ 8.33 (d, 2H, J =
CDCl3): δ Ϫ131.10, JPt–P = 2657 Hz. FAB-MS: 1219 (Mϩ).
1
᎐
᎐
7.0 Hz, H3,3Ј), 7.27 (t, 2H, J = 7.0 Hz, H4,4Ј), 6.98 (d, 2H, J =
Calc. for C50H76N2P4Pt2: C, 49.25; H, 6.28; N, 2.30. Found: C,
49.18; H, 6.34; N, 2.26%.
7.6 Hz, H5,5Ј), 2.09 [m, 12H, PCH2(CH2)2(CH3)], 1.55 [m, 12H,
PCH2(CH2)2(CH3)], 1.40 [m, 12H, PCH2(CH2)2(CH3)], 0.90 [(t,
18H, P(CH2)3CH3]. 13C NMR (100 MHz, CDCl3): δ 155.86
(C2,2Ј), 146.42 (C6,6Ј), 135.69 (C3,3Ј), 125.61 (C4,4Ј), 121.05 (C5,5Ј),
᎐
᎐
᎐
trans-[(Ph)(Et P) Pt–C᎐C–R–C᎐C–Pt(PEt ) (Ph)] (R ؍ 2,2Ј:
᎐
3
2
3 2
6Ј,2Љ-terpyridine-6,6Љ-diyl, 3M). Off-white compound (65%
yield). IR (CH2Cl2): ν/cmϪ1 2096 (–C᎐C–). H NMR (250 MHz,
1
᎐
᎐
116.47, 110.24 (C᎐C), 29.72–22.71 (PCH CH CH CH ), 14.13
᎐
᎐
2
2
2
3
(CH3). 31P{1H} NMR (101.3 MHz, CDCl3): δ Ϫ138.07, 1JPt–P
=
CDCl3): δ 8.48 (d, 2H, J = 7.8Hz, H3,3Љ), 8.35 (dd, 2H, J = 7.7,
0.7 Hz, H3Ј,5Ј), 7.86 (t,1H, J = 7.8 Hz, H4Ј), 7.63 (t, 2H, J =
7.80 Hz, H4,4Љ), 7.33 (dd, 2H, J = 7.7, 0.7 Hz, H5,5Љ), 7.21 (dd, 4H,
J = 7.6, 0.7 Hz, Hortho for Ph), 6.97 (t, 4H, J = 7.4 Hz, Hmeta for
Ph), 6.80 (t, 2H, J = 7.4 Hz, Hpara for Ph), 1.82 (m, 24H, PCH2),
1.11 [(t, 36H, P(CH2)CH3)]. 13C NMR (100 MHz, CDCl3):
δ 156.24 (C2Ј,6Ј), 155.59 (C2Љ,2), 146.94 (C6Љ,6), 139.08 (C4Ј), 136.77
2357 Hz. Calc. for (C38H60N2P2Pt)n: C, 56.91; H, 7.54; N, 3.49.
Found: C, 56.82; H, 7.61; N, 3.51%. GPC (THF): Mn = 60100 g
molϪ1 (n = 75), Mw = 102,170 g molϪ1, polydispersity = 1.7.
᎐
᎐
᎐
trans-[–(Bu P) Pt–C᎐C–R–C᎐C–] (R ؍ 2,2Ј:6Ј,2Љterpyridine
᎐
3
2
n
6,6Љ-diyl, 3P). Off-white product (80% yield). IR (CH2Cl2):
1
ν/cmϪ1 2095 (–C᎐C–). H NMR (250 MHz, CDCl ): δ 8.49 (d,
᎐
(C4Љ,4), 127.84 (C5Љ,5), 127.31–125.92 (C Ph), 121.87 (C5Ј), 120.80
᎐
3
᎐
2H, J = 7.8 Hz, H3Ј,3Љ), 8.37 (d, 2H, J = 7.8 Hz, H3Ј,5Љ), 7.84 (t,
1H, J = 7.8 Hz, H4Ј), 7.65 (t, 2H, J = 7.80 Hz, H4,4Љ), 7.18 (d, 2H,
J = 7.4 Hz, H5,5Љ), 2.25 [m, 12H, PCH2(CH2)2(CH3)], 1.67 [m,
12H, PCH2(CH2)2(CH3)], 1.49 [m, 12H, PCH2(CH2)2(CH3)],
0.93 [(t, 18H, P(CH2)3CH3]. 13C NMR (100 MHz, CDCl3):
δ 155.76 (C2Ј,6Ј), 155.44 (C2Љ,2), 146.70 (C6Љ,6), 137.00 (C4Љ), 136.07
(C4Љ,4), 125.86 (C5Љ,5), 120.99 (C5Ј), 120.19 (C3,3Љ), 116.81, 110.43
(C3,3Љ), 116.60, 111.37 (C᎐C), 15.16 (t, PCH CH ), 7.87 (CH ).
᎐
2
3
3
31P{1H} NMR (101.3 MHz, CDCl3): δ Ϫ131.27, JPt–P = 2659
Hz. FAB-MS: 1297 (Mϩ). Calc. for C55H79N3P4Pt2: C, 50.96;
H, 6.14; N, 3.24. Found: C, 51.13; H, 6.21; N, 3.27%.
1
᎐
᎐
᎐
trans-[(Ph)(Et P) Pt–C᎐C–R–C᎐C–Pt(PEt ) (Ph)] (R ؍ 4Ј-
᎐
3
2
3 2
phenyl-2,2Ј:6Ј,2Љ-terpyridine-6,6Љ-diyl, 4M). White solid (55%
yield). IR (CH2Cl2): ν/cmϪ1 2095 (–C᎐C–). 1H NMR (250
(C᎐C), 28.14–24.26 (PCH CH CH CH ), 13.85 (CH ). 31P{1H}
᎐
᎐
᎐
᎐
2
2
2
3
3
NMR (101.3 MHz, CDCl3): δ Ϫ138.28, 1JPt–P = 2350 Hz. Calc.
for (C43H63N3P2Pt)n: C, 58.75; H, 7.22; N, 4.78. Found: C,
58.86; H, 7.33; N, 4.81%. GPC (THF): Mn = 72100 g molϪ1
(n = 82), Mw = 129780 g molϪ1, polydispersity = 1.8.
MHz, CDCl3): δ 8.81 (s, 2H, H3Ј,5Ј), 8.40(dd, 2H, J = 7.8, 0.9
Hz, H3,3Љ), 7.89 (td, 2H, J = 8.0, 1.5 Hz, Hortho for Ј-Ph), 7.66
(t, 2H, J = 7.8 Hz, H4,4Љ), 7.48 (tt, 2H, J = 7.0, 1.3 Hz, Hmeta
for 4Ј-Ph), 7.42 (tt, 1H, J = 7.2, 1.3 Hz, Hpara for 4Ј-Ph), 7.34
(d, 2H, J = 7.8 Hz, H5,5Љ), 7.23 [(dd, 4H, J = 7.7, 1.32 Hz,
Hortho for Pt(Ph)], 6.97 [(t, 4H, J = 8.0 Hz, Hmeta for Pt(Ph)],
6.79 [(t, 2H, J = 7.2 Hz, Hpara for Pt(Ph)], 1.8 (m, 2H, PCH2),
1.12 [(t, 36H, P(CH2)CH3)]. 13C NMR (100 MHz, CDCl3):
δ 156.13 (C2Ј,6Ј), 155.67 (C2Љ,2), 149.20 (C6Љ,6), 146.89 (C4Ј), 139.27
᎐
᎐
᎐
trans-[–(Bu P) Pt–C᎐C–R–C᎐C–] (R ؍ 4Ј-phenyl-2,2Ј:6Ј,2Љ-
᎐
3
2
n
terpyridine-6,6Љ-diyl, 4P). Off-white product, 70% yield. IR
1
(CH2Cl2): ν/cmϪ1 2095 (–C᎐C–). H NMR (250 MHz, CDCl ):):
᎐
᎐
3
δ 8.76 (s, 2H, H3Ј,5Љ), 8.43 (d, 2H, J = 7.8 Hz, H3,3Ј), 7.84 (d, 2H,
J. Chem. Soc., Dalton Trans., 2002, 1358–1368
1367

View Online
16 M. S. Khan, M. R. A. Al-Mandhary, T. C. Corcoran, M. K. Al-Suti,
J = 7.1 Hz, Hortho for Ph), 7.67 (t, 2H, J = 7.7 Hz, H4,4Љ), 7.49 (t,
2H, J = 7.1 Hz, Hmeta for Ph), 7.44 (t, 1H, J = 7.0 Hz, Hpara for
Ph), 7.24 (d, 2H, J = 7.7 Hz, H5,5Ј), 2.24 [m, 12H, PCH2-
(CH2)2(CH3)], 1.65 [(br s, 12H, PCH2(CH2)2(CH3)], 1.47 [(sex-
tet, 12H, PCH2(CH2)2(CH3)], 0.87 [(t, 18H, P(CH2)3CH3]. 13C
NMR (100 MHz, CDCl3): δ 156.07 (C2Ј,6Ј), 155.82 (C2Љ,2), 149.75
(C6Љ,6), 146.75 (C4Ј), 139.39 (C Ph), 136.08 (C4Љ,4), 128.70 (C Ph),
J. P. Attfield, W. I. F. David, R. H. Friend, N. Feeder, A. Köhler,
E. A. Marseglia, P. R. Raithby, K. Shankland, C. C. Tang and
E. Tedesco, in preparation.
17 J. Lewis, N. J. Long, P. R. Raithby, G. P. Shield, W.-Y. Wong and
M. Younus, J. Chem. Soc., Dalton Trans., 1997, 4283.
18 (a) T. Yamamoto, T. Maruyama, Z.-H. Zhou, T. Ito, T. Fukuda,
Y. Toneda, F. Begum, T. keda, S. Sasaki, H. Takezoe, A. Fukuda and
K. Kubata, J. Am. Chem. Soc., 1994, 116, 4832; (b) C. Wang,
M. Kilitziraki, J. A. H. MacBride, M. R. Bryce, L. E. Horsburgh,
A. E. Sheridan, A. P. Monkman and D. W. Samuel, Adv. Mater.,
2000, 12, 217; (c) A. P. Davey, S. Elliott, O. O’Conor and W. Blau,
J. Chem. Soc., Chem. Commun., 1995, 1433; (d ) D. A. M. Egbe and
E. Klemm, Macromol. Chem. Phys., 1998, 199, 2683; (e) M.
Al-Higari, E. Birckner, B. Heise and E. Klemm, J. Polym. Sci.:
Pt. A: Polym. Chem., 1999, 37, 4442.
127.35 (C Ph), 126.02 (C5Љ,5), 119.05 (C5Ј), 117.47 (C3,3Љ), 116. 78,
᎐
109.48 (C᎐C), 29.71–24.15 (PCH CH CH CH ), 13.83 (CH ).
᎐
2
2
2
3
3
31P{1H} NMR (101.3 MHz, CDCl3): δ Ϫ137.58, 1JPt–P = 2357 Hz.
Calc. for (C49H67N3P2Pt)n: C, 61.61; H, 7.07; N, 4.40. Found: C,
61.87; H, 6.97; N, 4.37%. GPC (THF): Mn = 86800 (n = 91),
g molϪ1 (n = 82), Mw = 156240 g molϪ1, polydispersity = 1.8.
19 T. Yamamoto, K. Sugiyama, T. Kushida, T. Inoue and T. Kanbara,
J. Am. Chem. Soc., 1996, 118, 3930.
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We gratefully acknowledge Sultan Qaboos University (SQU)
Research Grant No. IG/SCI/CHEM/02/02. M. S. K. acknow-
ledges EPSRC, UK for a Visiting Fellowship and SQU for a
research leave. The award of a DAAD grant (Gemeinsames
Hochschulsonderprogramm III von Bund und LÄndern) (to
B. A.) is gratefully acknowledged. A. K. thanks Peterhouse,
Cambridge for a Research Fellowship and the Royal Society
for a University Research Fellowship. The support of the
EPSRC for project funding and for the purchase of the X-ray
diffractometers is gratefully acknowledged.
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