Preparation of models and oligomers of metal alkynyls NMR, GPC and X-ray structural characterization of building blocks for the construction of molecular devices

Article abstract of DOI:10.1016/j.jorganchem.2003.08.007

A systematic study has been carried out for the use of the palladium-based Extended One Pot (EOP) synthetic protocol toward the preparation of metal alkynyl oligomers of general formula [- C≡C-Ar-C≡C-M(L)_m -]_n (M=Pt, Pd). Model compounds of type trans-M(PBu ₃)₂(C≡CC₆H₅) ₂ have been prepared by the reaction of tributyltinethynylbenzene with trans-M(PBu₃)₂ Cl₂, in the absence of palladium catalysis, since the presence of catalytic Pd(PPh₃)₄ yields reaction mixtures containing starting material, product and intermediate complex trans-MCl (PBu₃)₂(C≡CC₆H₅). Palladium catalysis has been used for the formation of the bistinacetylide compounds Bu₃Sn-C≡C- Ar-C≡C-SnBu₃ (Ar=C₆ H₄; bis(2,5-n-octyloxy)C₆H₄). Subsequent coupling of these compounds with MCl₂(PBu₃) ₂ in the absence of palladium catalyst yields metal alkynyl oligomers. Comparison of ³¹P-NMR and gel permeation chromatography (GPC) analyses indicates that the GPC technique represents a reliable method to estimate polymer chain lengths for polymers bearing branched aromatic spacers, in spite of the rigid-rod shape of the polymer backbone. Single crystal X-ray determinations of model compounds demonstrate the essential role of side substituents in the aromatic ring to control the supramolecular order and, as a consequence, the optoelectronic properties of materials.

Full text of DOI:10.1016/j.jorganchem.2003.08.007

Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
www.elsevier.com/locate/jorganchem
Preparation of models and oligomers of metal alkynyls
NMR, GPC and X-ray structural characterization of building blocks
for the construction of molecular devices
Alessandra La Groia a, Antonella Ricci a, Mauro Bassetti a, Dante Masi b,
Claudio Bianchini b, Claudio Lo Sterzo c,*
a Istituto CNR di Metodologie Chimiche (IMC-CNR), Sezione Meccanismi di Reazione, Dipartimento di Chimica, Box 34-Roma 62, Universita` ‘La
Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy
b Istituto CNR di Chimica dei Composti Organo Metallici (ICCOM), Area della Ricerca CNR, Via Madonna del Piano snc, 50019 Sesto Fiorentino
(Firenze), Italy
c Dipartimento di Scienze degli Alimenti, Facolta` di Agraria, Universita` degli Studi di Teramo, Via Spagna 1, 64023 Mosciano S. Angelo (Teramo),
Italy
Received 2 June 2003
Abstract
A systematic study has been carried out for the use of the palladium-based Extended One Pot (EOP) synthetic protocol toward
the preparation of metal alkynyl oligomers of general formula [Ã
type trans-M(PBu3)2(CÅCC6H5)2 have been prepared by the reaction of tributyltinethynylbenzene with trans-M(PBu3)2Cl2, in the
absence of palladium catalysis, since the presence of catalytic Pd(PPh3)4 yields reaction mixtures containing starting material,
product and intermediate complex trans-MCl(PBu3)2(CÅCC6H5). Palladium catalysis has been used for the formation of the
bistinacetylide compounds Bu3SnÃCÅCÃArÃCÅCÃSnBu3 (ArꢀC6H4; bis(2,5-n-octyloxy)C6H4). Subsequent coupling of these
/
CÅ
/
CÃ
/
ArÃ
/
CÅ
/
CÃ/M(L)m
Ã
/
]
(Mꢀ
/
Pt, Pd). Model compounds of
n
/
/
/
/
/
/
/
/
/
compounds with MCl2(PBu3)2 in the absence of palladium catalyst yields metal alkynyl oligomers. Comparison of 31P-NMR and gel
permeation chromatography (GPC) analyses indicates that the GPC technique represents a reliable method to estimate polymer
chain lengths for polymers bearing branched aromatic spacers, in spite of the rigid-rod shape of the polymer backbone. Single
crystal X-ray determinations of model compounds demonstrate the essential role of side substituents in the aromatic ring to control
the supramolecular order and, as a consequence, the optoelectronic properties of materials.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Conjugated organometallic polymers; EOP synthesis; Palladium catalysis; Polymetallaaryleneethynylene
1. Introduction
wires. Indeed, the characteristic conjugation path of
these materials allows the motion of either electronic
excitation energy or electrons throughout the whole
polymer chain, ultimately leading to conducting, mag-
netic and photoactive properties [2].
We have recently developed an innovative strategic
route to poly(ethynylaromatic) polymers based on the
preparation of aromatic tributyltinacetylide compounds
and of their in-situ palladium-catalysed coupling with
aromatic halides [3]. This new synthetic protocol, named
Extended One Pot (EOP), essentially consists in a
sequential one-pot multistep synthetic route which
converts aromatic halides into aromatic acetylides,
then into aromatic tributyltinacetylides and finally into
The synthesis of conjugated organic and organome-
tallic oligomers and polymers and the study of their
properties have become a major focus in material
science due to the interesting features of such materials
for innovative optoelectronic applications [1]. Organo-
metallic polymers incorporating transition metal centers
bridged by conjugated polyynes (polymetallaacetylides)
have actually a great potential as photonic or electronic
* Corresponding author.
E-mail address: losterzo@agr.unite.it (C. Lo Sterzo).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.08.007

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
407
Fig. 1. Different uses of the EOP procedure.
poly(ethynylaromatic) polymers, the first and the third
steps being palladium catalyzed. Depending on the
nature of the coupling partners, the EOP synthetic
protocol may be oriented towards the formation of
(aryleneacetylene-co-metallaacetylene) polymers of type
[ÃArÃCÅCÃM(L)m ÃCÅCÃ]n (MꢀPt, Pd).
/
/
/
/
/
/
/
/
either ethynylaromatic homo-polymers [Ã
(Fig. 1, Path b), or ethynylaromatic co-polymers [Ã
CÃArÃCÅCÃAr?Ã]n (Path a1) [4]. The polymeric mate-
rials obtained by EOP method are characterized by
comparable opto-electronic properties with those ex-
hibited by similar materials prepared with conventional
procedures [3b]. Therefore, the EOP synthetic protocol
represents a simplified, well established and reliable
synthetic procedure for the synthesis of an important
class of materials.
/
CÅ
/
CÃ
/
ArÃ
/
]
n
2. Results and discussion
/
CÅ
/
/
/
/
/
/
The synthetic route outlined in path a2 (Fig. 1)
combines the straightforward one-pot Pd-catalyzed pre-
paration of aromatic bistributyltinacetylides (steps 1 and
2) with a transmetalation reaction between metal halides
and the tinacetylide groups, i.e. a metalÃ
/
carbon bond-
formation process (step 3). The successful combination
of these synthetic sequences would provide a novel and
convenient protocol for the synthesis of innovative
materials with a diverse range of technological applica-
tions.
Since metallaacetylide moieties can be prepared by
coupling of metal-halides and trialkyltinacetylides by
palladium catalysis [5], we have focussed our attention
on the possibility of extending the EOP method to the
We envisaged that the encountered difficulties in
obtaining high molecular weight materials in the pre-
paration of organometallic polymers were due to lack of
extended coupling, in particular that the conditions
which led to the aromatic bistributyltinacetylide com-
pounds (steps 1 and 2) were not suitable to perform with
preparation of ethynylaromaticꢁ/ethynylmetallo co-
polymers [ÃCÅCÃArÃCÅCÃM(L)m Ã
/
/
/
/
/
/
/]n, as indicated in
path a2 of Fig. 1. Although the formation of a large
variety of model metallaacetylide compounds as well as
of sophisticated organometallic tethers has been possible
[6], insofar the synthesis of polymeric ethynylated
comparable efficiency the reaction between MÃ
/Cl and
Bu3SnÃCÅCÃ functionalities. These unfavourable cir-
/
/
/
organometallic materials by metalÃ/carbon coupling
cumstances are probably the results of the complex
factors governing the transmetalation process [8]. As a
very preliminary approach we then decided to study the
formation of model compounds of type trans-
under EOP conditions has been limited to the formation
of short oligomers [3a,7]. Some adverse factors have
been limiting the coupling to very few catalytic turn-
overs.
M(PBu3)2(CÅ
/
CC6H5)2 (MꢀPd, 4; Pt, 5), according to
/
In view of the great potential represented by organo-
metallic polymers as advanced materials for innovative
applications [1,2], and of the appealing opportunities
offered by the EOP method, we decided to perform a
systematic study of the reactivity between metal halides
Scheme 1, by the reaction of tributyltinethynylbenzene
(1) with trans-bis(tributylphosphine)palladiumdichlor-
ide, trans-Pd(PBu3)2Cl2 (2), or with trans-bis(tributyl-
phosphine)platinumdichloride, trans-Pt(PBu3)2Cl2 (3),
in the presence of a catalytic amount (5 mol%) of
Pd(PPh3)4. The transformation depicted in Scheme 1
was designed as synthetic probe in order to find the very
(Mꢀ/Pd, Pt) and trialkyltinacetylides, and then to
optimize the conditions for the preparation of poly-

408
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
Scheme 1.
basic conditions to obtain efficiently metal acetylide
moieties, and, in perspective, the most suitable condi-
tions to perform step 3 in path a2 (Fig. 1), under EOP
conditions.
Formation of compounds 4, 5 and of the intermediate
monosubstituted trans-bis(tributylphosphine)(phenyla-
31P-NMR spectra of authentic samples [9] of 3, 5 and 7
are shown in traces bꢁd.
/
Since the EOP protocol leading to the ethynylated
organic polymers had been previously observed to
depend critically on both the temperature and the nature
of the solvent [3b], the effect of these parameters on the
reactions reported in Scheme 1 was preliminary ana-
lysed. In spite of the variety of conditions explored
(different solvents, temperatures and reaction times), all
the reaction mixtures contained, invariably and in
comparable amount, the metaldichloride substrate to-
gether with both mono- and bis-ethynylated species. All
cetylide)metalchloride
complexes,
trans-
MCl(PBu3)2(CÅCC6H5) (Mꢀ
/
/
Pd, 6; Pt, 7) can be
conveniently monitored by 31P-NMR spectroscopy.
Trace a in Fig. 2 shows a typical spectroscopic pattern
observed upon monitoring conversion of 3 into 7 and 5,
in the presence of the Pd catalyst. As a reference, the
Fig. 2. (a) 31P-NMR spectrum of crude reaction mixture of 3 with 1, carried out in THF at 70 8C for 20 h. (bꢁ
respectively.
/
d) 31P-NMR of isolated 5, 7 and 3,

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
409
Table 1
Systematic study of reaction of 2 and 3 with 1
our attempts to increase the low conversion of the
starting material either by raising the temperature or
prolonging the reaction time were unsuccessful, mixture
of products being invariably obtained. Even the addi-
tion of a larger amount of Pd catalyst to the reaction
mixture did not improve the yield; in some cases a
reverse effect was observed, in fact [10]. Indeed, it has
not been possible so far to achieve the selective
formation of either mono- (6, 7) or di-substituted (4,
5) products. It is very likely that Pd(PPh3)4 catalyses the
thermodynamic stability of the various species involved.
This hypothesis is in line with the formation of
oligomers, rather than polymers, as occurred to us using
the Pd-catalysed coupling of 2 or 3 with bis(trialk-
ylethynyl)aromatic derivatives to prepare organometal-
lic ethynylated polymers [3a,7]. The same limiting role of
the EOP procedure has also been experienced by
Fratoddi in the preparation of Pt and Pd poly-ynes [11].
The formation of ruthenium acetylides by coupling of
tributyltinacetylides with ruthenium chlorides has been
described by Wolf and co-workers [12], while Lewis and
co-workers has shown that organometallic ethynylated
materials, with a high degree of polymerisation, can be
obtained by the reaction of trimethyltinacetylides with
transformations of 2ꢁ
/
3 into 6ꢁ
/
7 and of 6ꢁ
/
7 into 4ꢁ5 as
/
well as the reverse processes. Therefore, higher tempera-
tures, prolonged reaction times, and higher catalyst
loadings would simply favour an equilibration process
of the various compounds and produce reaction mix-
tures with compositions controlled by the relative
MÃ
/
Cl moieties (Mꢀ/Fe, Ru, Os, Rh, Co, Ni, Pd, Pt),
with no need of Pd catalysis [13]. These reports as well as

410
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
use as building blocks for the preparation of the
corresponding organometallic polymers [ÃMÃCÅCÃ
ArÃCÅCÃ]n. To this purpose, an appropriate modifica-
/
/
/
/
/
/
/
tion of the Pd-based EOP synthetic protocol was
designed. The 1,4-bis(tributyltinethynyl)aryl derivatives
13 and 14 were obtained by a conventional EOP
procedure. In the first step (Scheme 2), the Pd-catalysed
coupling between the 1,4-diiodoaryl compounds 8 and 9
(arylꢀC6H4, 8; bis(2,5-n-octyloxy)C6H4, 9) and tribu-
/
tyl(ethynyl)tin (10) gave the 1,4-diethynylaryl derivatives
11 and 12, respectively, together with Bu3SnI as
byproduct. In the following step, the deprotonation of
the acetylide functionalities of 11 and 12 by LDA
allowed the reaction with Bu3SnI to give 13 and 14,
respectively. At this stage, the Pd catalyst used in step 1,
still present and active in the reaction medium, was
removed to allow for the coupling of 13 and 14 with
trans-M(PBu3)2Cl2. Therefore, at the end of step 2
complexes 13 and 14 were isolated and purified from
catalyst residues, and then allowed to react further.
With the aim of obtaining polymeric materials of type
[Ã
/
MÃ
/
CÅ
/
CÃ
/
ArÃ
/
CÅ
/
CÃ
/
]n, the reactions between trans-
Pt(PBu3)2Cl2 and the tin derivatives 13, 14 were
performed using the conditions which were found
suitable for the formation of the di-substituted Pt
compound 5, namely in toluene at 110 8C (entry 18,
Table 1), while trans-Pd(PBu3)2Cl2 was reacted with 13,
14 in dioxane at 70 8C, as for the preparation of the di-
substituted Pd compound 4 (entry 6, Table 1). Polymeric
Scheme 2.
the lack of a clean transformation of 2 and 3 into 4 and
5, respectively, indicate that the Pd catalyst may have an
adverse role in the quantitative conversion of MÃ
tributyltinacetylide moieties into metal acetylide species,
for MꢀPd or Pt.
/
Cl and
/
materials 15ꢁ
heating (9ꢁ27 h), and were separated as brown residues
after cooling at room temperature and partial removal
of the reaction solvent. In the case of the coupling of
trans-M(PBu3)2Cl2 with the unbranched compound 1,4-
bis(tributyltinethynyl)benzene (13) the solid products
/18 (Scheme 3) formed after prolonged
Coupling reactions of 2 and 3 with 1 were then
repeated in the absence of any Pd catalyst. As a result
(Table 1), the selective formation of 6 (entry 4), 7 (entry
16), 4 (entry 6) and 5 (entry 18) was achieved. As
compared to the Pd compounds 6 and 4, more severe
conditions, in terms of temperature and reaction time,
were generally required for the formation of the
corresponding Pt derivatives 7 and 5.
Irrespective of the metal centre, the experimental
conditions for the preparation of the mono-substituted
complexes 6 and 7 (entries 4 and 16) were markedly
different from those leading to the disubstituted com-
plexes 4 and 5 (entries 6 and 18). Interestingly, the use of
an excess of tributyl(phenylethynyl)tin in the synthesis
of the mono-substituted complexes did not produce any
disubstituted complex, which means that, irrespective of
the stoichiometry, the formation of 6 and 7 is inherently
favoured over that of 4 and 5. The discovery of the
appropriate conditions to obtain selectively either
mono- or bis-phenylacetylides represents an appealing
opportunity for the synthesis of different chemical
modules to be used for engineering more elaborate
aggregates.
/
(Pd, 15; Pt, 17) appeared as yellowꢁbrown crispy
/
powders, while the alkyl-branched bis(tributyltin)ethy-
nylaryl derivative 14 formed products 16 (Pd) and 18
(Pt) as brown gummy oils. Since both the mother liquors
of the reactions and the methanol washings were still
intensely coloured, the nature of the dissolved products
was further analysed (vide infra).
The yellow powder obtained from the reaction of 3
]n), is solu-
with 13, ([Ã
/
Pt(PBu3)2PdÃ
/
CÅ
/
CÃ
/
C6H4Ã
/
CCÃ
/
ble in dichloromethane, tetrahydrofuran and chloro-
form. The 31P-NMR spectrum of this material in CDCl3
consists of two singlets at d 7.4 (JPÃPt
3.5 ppm (JPÃPt 2355 Hz) in a relative ratio of 1:1.3. On
the basis of the close similarity between these values and
those shown by 7 and 5, the two signals were attributed
to terminal [Ã
Pt(PBu3)2ÃCÅ
teworthy, the 1:1.3 relative ratio is consistent with the
formation of the oligomeric mixture shown in Fig. 3.
The solution from which 17a was separated and the
rinsing methanol solution were collected and evaporated
ꢀ2366 Hz) and
/
ꢀ
/
/
CÅ
/
CÃ
/
Pt(PBu3)2Cl] and internal [Ã
/
CÅ
/
CÃ
/
/
/
CÃ
/
] phosphorus atoms, respectively. No-
Having established the most suitable protocol for the
formation of the acetylide moieties MÃ
Pd, Pt), we focused our attention towards their potential
/
CÅ
/
CÃ
/
Ar (Mꢀ
/

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
411
Scheme 3.
to give a brown oily residue. Chromatographic separa-
tion of this material afforded Bu3SnCl and a yellow
solid, which was identified as the bimetallic compound
20 (ca. 20%), on the basis of its spectroscopic and
analytical data (Fig. 4).
Similar results were obtained by reacting 3 with 14.
The gummy precipitate obtained upon addition of
methanol to the concentrated reaction solution showed
two signals in the 31P-NMR spectrum. The 1:1 intensity
extended coupling with tributyltinacetylide functional-
ities (dioxane, 70 8C, see entry 6, Table 1). However, the
material isolated contained low oligomers only. In the
case of 15, a 31P{1H}-NMR analysis did not help to
estimate the chain lengths, because the signals of the
terminal and internal phosphorus atoms exhibited very
close chemical shifts, and hence appeared as unresolved
resonances. For this reason, the chain lengths were best
estimated by gel permeation chromatography (GPC)
(vide infra). The characterisation of the products
dissolved in solution after precipitation of oligomers
15 and 16 was more rewarding. In both cases, the
evaporation of the solvent, followed by chromato-
graphic separation, gave 19 and 21 in pure form, which
ratio and the chemical shifts (dꢀ
/
7.6 (JPÃPt
ꢀ2368 Hz)
/
and 3.9 (JPÃPt 2364 Hz)) of these signals were unequi-
ꢀ
/
vocally consistent with the formation of tetramer 18. As
described before, the solution recovered after separation
of the precipitate and the methanol washings were
evaporated to give a solid residue constituted by the
bimetallic compound 22, which was purified by chro-
matography.
were recrystallised from dichlorometaneꢁmethanol to
/
get single crystals suited for X-ray diffraction analyses
(vide infra).
The Pd complex 2 was reacted with either 13 or 14
under appropriate experimental conditions to give
It is worth noting that, despite the use of a precise 1:1
stoichiometry, the reaction between 3 and 13 gave
Fig. 3. Chains of different length of polymer 17a.

412
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
Fig. 4. Binuclear palladium and platinum complexes.
invariably the bismetallic-capped short-chain oligomers
20 and 17a. A similar result was obtained by reacting 3
and 14 and 2 with either 13 or 14 (vide infra). These
results may be explained in two ways: (i) under the
experimental conditions adopted, the tinacetylides 13
and 14 are not as active as expected; (ii) these
tinacetylides undergo appreciable degradation. The
latter hypothesis is more likely as an increase in the
concentration of 13 by 50% resulted in the formation of
the dodecameric product 17b [14]. Although the use of
an excess of the bistinacetylide may represent a draw-
back, it should be considered that this coupling partner
is conveniently accessible in large scale by the use of the
EOP synthetic protocol. Therefore, in consideration of
the importance of polymetallaacetylides in material
science, the overall synthetic route remains of interest.
Evidence for the presence of longer chain lengths in
17b was provided by UV absorption measurements. Fig.
5 shows the UV spectra of oligomers 17a (nꢀ
/
4}5) and
/
17b (nꢀ12), together with those of the corresponding
/
block precursors 3 and 13, and of dimer 20. The lmax
values in the spectra of 17a and b were appreciably
shifted as compared to the binuclear complex 20, and
remarkably shifted as compared to the lmax values of the
starting monomers 3 and 13. Interestingly, the 10 nm red
shift between 17a and b well accounts for the observed
chain elongation in the latter. It may be therefore
concluded that oligomers 17a and b exhibit increased
electronic conjugation, hence they would be featured by
more efficient electron mobility, as compared to the
corresponding precursor.
2.1. X-ray structural analysis of complexes 19 and 21
Single crystals of 19 and 21 suitable for X-ray
diffraction analysis were grown by slow evaporation of
Fig. 5. UVꢁvis spectra in CH2Cl2.
/

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
413
Fig. 7. ORTEP of complexes 19 and 21 showing the unit cell. The
tributylphosphine groups have been omitted for clarity.
dichloromethaneꢁmethanol solutions at room tempera-
/
ture. The molecular structures of both complexes 19 and
21 are shown in Fig. 6. Selected bond distances and
angles for 21 are listed in Table 2.
In either case, the crystal structure consists of a
bimetallic capped 1,4-benzenediyl unit in which the
two PdII atoms are square-planarly coordinated by
two trans tributylphosphines and by trans chlorine and
acetylide moieties. The benzenediyl unit in 21 is
decorated in positions 2,5 by octyloxy arms. Compound
21 contains half molecule in the asymmetric unit. In Fig.
6 is shown the complete molecule in which the butyl
groups have been partially omitted for clarity. Because
of the low quality of the experimental data, the butyl
groups in the structure of 19 are not well defined. For
this reason, only the structural data of 21 will be
discussed and the rough data of 19 will be used just to
confirm the connectivity in this compound.
Fig. 6. ORTEP drawings of binuclear complexes 19 and 21. Butyl
groups have been omitted for clarity.
Table 2
˚
Selected bond distances (A) and angles (8) for 21
Bond distances
Pd(1)Ã
Pd(1)Ã
Pd(1)Ã
Pd(1)Ã
C(25)Ã
C(26)Ã
C(27)Ã
C(27)Ã
O(1)Ã
/
C(25)
1.938(10)
2.306(3)
2.307(3)
2.334(2)
1.199(12)
1.437(13)
1.374(13)
1.386(13)
1.368(12)
/P(1)
/P(2)
/Cl(1)
/
C(26)
C(27)
C(28)
C(29)
/
/
In both compounds, the CÅ
/
C separations (1.199(12)
˚
/
˚
˚
A in 21, 1.19(4) A and 1.18(4) A in 19) and the PdÃ
/C
/
C(29)
˚
˚
˚
separations (1.938(10) A in 21, 1.98(4) A and 1.95(4) A
in 19) are typical for metal-s-acetylide moieties [15,16].
On the other hand, a partial conjugation within the
Bond angles
C(25)ÃPd(1)Ã
C(25)ÃPd(1)Ã
P(1)ÃPd(1)Ã
C(25)Ã
P(1)ÃPd(1)Ã
P(2)ÃPd(1)Ã
C(26)Ã
C(25)Ã
C(28)Ã
C(28)Ã
C(29)Ã
/
/
P(1)
85.4(3)
84.8(3)
/
/P(2)
/
/
P(2)
169.09(10)
178.9(3)
95.11(10)
95.56(10)
179.2(10)
174.1(12)
116.7(9)
121.7(9)
121.6(10)
molecule of 21 is put in evidence by the CÅ
distances, which are longer than typical CÅC bonds and
by the C26ÃC27 bonds which are shorter than typical
CÃC bonds.
The aromatic rings in 19 and 21 are essentially
coplanar with the PÃPdÃP axes, and the angle
179.2(10)8 in 21 for the fragment PdÃCÅC confirms
the linear geometry of the bis(acetylide) complexes [17].
/C bond
/
Pd(1)Ã
/Cl(1)
/
/
/
Cl(1)
/
/
/
Cl(1)
/
/
C(25)Ã
C(26)Ã
C(27)Ã
C(27)Ã
C(27)Ã
/
Pd(1)
/
/
C(27)
C(29)
C(26)
C(26)
/
/
/
/
/
/
/
/
/
/

414
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
The slight deformation of the square-planar geometry
around the palladium centres (P(1)ÃPd(1)ÃCl(1)
95.11(10)8 and P(2)ÃPd(1)ÃCl(1) 95.56(10)8 in 21 [17]
molecules. In contrast, all the molecules composing the
unit cell of 21 are well defined, perfectly layered along
planes and aligned to each other.
/
/
/
/
The octyloxy side chains are laterally extended, with
the two oxygen atoms and all the carbon atoms of the
chains perfectly coplanar with the carbon atoms of the
benzene ring. Within the same plane, the metal-chloride
terminus of one molecule is oriented towards the
midpoint of the octyloxy side chains of the preceding
and following molecules. The octyloxy side chains are
perfectly aligned between different horizontal planes
and stacked in an interdigitated fashion. The aromatic
rings between the planes are staggered, probably in
consequence of the steric hindrance of the butyl groups.
The crystal structure of 21, which represents a model
molecule of an organometallic ethynylated polymer,
sheds light on the key role of the side chains in
controlling the orientation of the molecules. In parti-
may be due to a repulsive interaction between the Cl and
the phosphine ligands.
While the intrinsic structural features of 19 and 21 are
comparable to those reported for several analogous
compounds [15,16c,18], it is worth highlighting the
mutual orientation of the different molecular units in
the cell (Fig. 7, the H atoms and the PBu3 groups have
been omitted for clarity). Indeed, complex 19, contain-
ing an unsubstituted phenyl ring as spacer between the
acetylenic groups, shows two very different orientations
of the molecules in the unit cell. In particular, a molecule
is diagonally oriented with respect to the planes of two
perfectly aligned molecules. The plane of the benzene
ring of this diagonally-interposed molecule is almost
perpendicular to the benzene planes of the surrounding
Table 3
Yields and molecular weights for polymers and model complexes

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
415
cular, the structure of 21 provides support to previous
reports according to which rigid-rod polymers can form
highly crystalline layered solids when functionalised
with long aliphatic side chains [19], with influence on
their (opto)electronic properties [20]. The supramolecu-
lar order of rigid-rod side-branched structures has been
previously figured out by means of STM data [21] or
deduced from X-ray powder diffraction data [22]. To the
best of our knowledge, the structure of 21 is the first
example of a single crystal X-ray determination showing
the ordinate supramolecular assembling of long-chain
decorated compounds.
3. Conclusions
The coupling of bistributyltinacetylides with MÃ
moieties (MꢀPd, Pt) does not take place efficiently in
/
Cl
/
the presence of Pd(PPh3)4, leading to an equilibration
mixture of different products. In the absence of the Pd
catalyst, however, the selective formation of short
oligomers occurs, yet much harsher conditions are
required. Since tinacetylides are easily accessible by the
EOP protocol, the overall synthetic procedure shows a
great potential for the preparation of metal acetylide
polymers.
The combined use of 31P-NMR and GPC techniques
has allowed to understand the limits as well as the
reliability of both techniques in the estimation of
polymer chain length for rigid rod-like materials. In
particular we have offered a point of reconciliation to
the widely debated opportunity of using GPC techni-
ques in the molecular weight calculation for this class of
materials.
The structural features of complexes 19 and 21,
studied by single crystal X-ray analysis, have demon-
strated that with the proper choice of side substituents it
is possible to control the supramolecular order, and in
perspective, the electronic and optical properties of
materials that are strongly influenced by solid-state
arrangement.
2.2. Molecular weight determinations of products 15ꢁ22
/
The molecular weight of materials obtained from the
coupling of 1,4-bis[(tributyltin)ethynyl]benzene (13) or
1,4-bis[(tributyltin)ethynyl]-2,5-di(octyloxy)benzene (14)
with trans-Pd(PBu3)2Cl2 (2) and trans-Pt(PBu3)2Cl2 (3)
were estimated by GPC, using polystyrene standards for
the calibration, and by 31P-NMR spectroscopy. In Table
3 are reported the molecular weight, the molecular
weight distribution and the degree of polymerisation
of the different materials obtained; the Table also
contains the degree of polymerisation as estimated by
NMR integration of the terminal vs. internal relative
intensities of the signals.
It is worth mentioning that the determination of the
molecular weight of rigid-rod materials via GPC, is
commonly considered unreliable. In fact, using ran-
domly coiled polystyrene as calibration standard, the
molecular weight of rigid-rod materials may be greatly
overestimated [23]. For this reason, the determination of
the chain length by integration of the NMR signals of
the internal vs. external groups is considered as much
more reliable. A comparison of the chain lengths
obtained from either 31P-NMR or GPC analysis on
17a and b showed the expected discrepancy. The GPC
technique overestimated the molecular weights of 17a
and b because the rigid rod shape of these molecules
magnify their hydrodynamic volume with respect to that
of the polystyrene standard of analogous molecular
weights. In contrast, the 31P-NMR and GPC (Mn) data
for 18, bearing two octyloxy substituents, were perfectly
coincident, thus indicating that the two long side-
substituents mask somehow the rigid rod structure of
the polymer backbone and make the overall structure of
18 and 16 more similar to random coil polystyrene
standards [23c]. The effect of the octyloxy arms is also
evident by comparing the molecular weights of 21 and
22 obtained from 31P-NMR and GPC analyses (Mn/
MW ratio in Table 3). In the case of 19 and 20,
containing an unsubstituted benzene ring, the discre-
pancy between Mn determined by GPC and the actual
MW is apparently higher as compared to the octyloxy-
arm containing 21 and 22.
4. Experimental
4.1. General procedures
Elemental analysis were performed by the Servizio
Microanalisi of the Dipartimento di Chimica of Uni-
versita` di Roma ‘La Sapienza’. IR spectra were recorded
on a Nicolet FT 510 instrument in the solvent subtrac-
tion mode, using a 0.1 mm CsI cell or polyethylene disk.
UV spectra were recorded on a PerkinꢁElmer Lambda
/
18 spectrophotometer. H-, 13C- and 31P-NMR spectra
were recorded on a Bruker AC300P spectrometer at 300,
75 and 121 MHz, respectively. Chemical shifts (ppm) are
1
1
reported in d values relative to Me4Si; for H-NMR,
CHCl3 (d 7.24) and for 13C-NMR, CDCl3 (d 77.0) were
used as internal standard. The 31P-NMR chemical shifts
are relative to 85% H3PO4. Molecular weights were
determined (relative to polystyrene standard) on a
PerkinꢁElmer GPC equipped with a set of Waters
/
Styragel columns (HT 6 200K-10M, HT 5 50K-4M,
HT 4 5K-600K, HT 3 500K-30K), and a UV detector.
Tetrahydrofuran (THF) (HPLC grade; Aldrich) was the
eluent (flow rate: 1 ml minꢂ1). Mass spectra were
obtained on a Fisons Instruments VG-Platform Bench-
top LC-MS (positive ion electrospray mass spectra,
ESPꢃ) spectrometer.

416
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
Solvents, including those used for NMR and chro-
matography, were thoroughly degassed before use.
Chromatographic separations were performed with
2. Approximately 10 g of Celite was added to the
reaction mixture, and the solvent was removed under
vacuum. The residue was chromatographed on alumina.
After removal of Bu3SnCl by hexane, elution with
70ꢁ230 mesh silica gel (Merck).
/
All manipulations were carried out with Schlenk type
equipment under an atmosphere of argon on a dual
manifold/argon-vacuum system. Liquids transferred by
syringe or cannula. Solvents were dried (THF over
hexaneꢁbenzene 9:1 produced a first band containing
/
the unreacted complex 2 [25]. In spite of accuracy in
executing the chromatographic separation, the second
band eluted was a mixture of di- (4) and mono-
substituted (6) products. A third fraction eluted and
collected, after removal of the solvent, gave pure mono-
substituted complex (6).
sodiumꢁpotassium alloy, toluene and dioxane over
/
sodium), and argon-saturated prior to use; DMF was
distilled from CaH2 under reduced pressure.
trans-Pd(PBu)3PdCl2 (2) [24,25] and trans-
Pt(PBu)3PtCl2 (3) [25,26] were prepared according to
published procedures. 1,4-Bis[(tributyltin)ethynyl]ben-
zene (13) and 1,4-bis[(tributyltin)ethynyl]-2,5-di(octylox-
y)benzene (14) were prepared following our previously
described procedure [3a].
4.2.1. trans-[Pd(PBu3)2(CÅ
13C-NMR (CDCl3): d 13.8 (Ã
13.6 Hz), 24.5 (dd, JCÃP
(CH2)3Ã), 111.8 (t, JCÃP
(ÃCꢀC ÃPh), 124.9, 128.0 (Ar), 128.6 (C1), 130.7 (Ar).
/
CÃ
/
C6H5)2] (4)
/
CH3), 22.8 (dd, JCÃP
ꢀ
/
ꢀ
/
6.8 Hz), 26.6 (br) (PÃ
/
/
ꢀ
/
17.0 Hz, ÃC ÅCÃPh), 113.4
/
/
/
/
/
/
Other chemicals were purchased from Aldrich and
used as received unless otherwise specified.
Legend for 13C-NMR spectra:
31P-NMR (CDCl3): d 11.2. MS (15 V, ESPꢃ): 510 (Mꢃ
/
Hꢂ
/
PBu3)ꢃ. Spectroscopic properties are in agreement
with reported data [27].
4.2.2. trans-[PdCl(PBu3)2(CÅ
1H-NMR (CDCl3): d 0.90 (t, Jꢀ
1.42 (sx, Jꢀ7.0 Hz, 12H, ÃCH2ÃCH2Ã
12H, ÃCH2ÃCH2ÃCH3), 1.91 (m, 12H, PCH2Ã
7.25 (m, 5H, ArÃ
H). 13C-NMR (CDCl3): d 13.7 (Ã
CH3), 22.8 (dd, JCÃP 13.6 Hz), 24.3 (dd, JCÃP 6.8
Hz), 26.3 (dd, JCÃP 18.1 Hz) (PÃ(CH2)3Ã), 96.2 (t,
JCÃP 15.8 Hz, ÃC ÅCÃPh), 105.7 (t, JCÃP 5.7 Hz, Ã
CÅC Ã
Ph), 125.4, 127.9 (Ar), 128.3 (C1), 130.5 (Ar). 31P-
/
CÃ
/
C6H5)] (6)
/
7.0 Hz, 18H, Ã
/
CH3),
/
/
/
/CH3), 1.55 (m,
/
/
/
/
), 7.08ꢁ
/
/
/
ꢀ
/
ꢀ
/
ꢀ
/
/
/
ꢀ
/
/
/
/
ꢀ
/
/
/
/
NMR (CDCl3): d 10.4. IR (CH2Cl2, cmꢂ1): 2963 (s),
2932 (s), 2903 (w), 2874 (s), 2116 (s) (nCÅC), 1595 (m),
1485 (m), 1465 (m), 1411 (w), 1379 (w), 1343 (w), 1304
(w). lmax (CH2Cl2): 273 nm. Anal. Calc. for
C32H59ClP2Pd: C, 59.35; H, 9.18. Found: C, 59.27; H,
9.27%. MS (15 V, ESPꢃ): 653 (Mꢃ
/
Li)ꢃ, 612 (Mꢂ
/
Cl)ꢃ. Spectroscopic and analytical properties are in
agreement with reported data [28].
4.3. Coupling of trans-
dichlorobis(tributylphosphine)platinum(II) (3) with
tributyl(phenylethynyl)tin
A Schlenk tube was loaded with trans-Pt(PBu3)2PtCl2
(3) (0.050 g, 0.075 mmol) and Pd(PPh3)4 (0.005 g, 0.004
mmol). After three cycles of vacuum/argon, were added
4.2. Coupling of trans-
dichlorobis(tributylphosphine)palladium(II) (2) with
tributyl(phenylethynyl)tin
by syringe Bu3SnCÅ
/
CPh (0.058 g, 0.15 mmol) and THF
(20 ml). After 20 h stirring at 70 8C, 31P-NMR analysis
showed the presence of two compounds, in addition to
3. Approximately 10 g of Celite was added to the
reaction mixture, and the solvent was removed under
vacuum. The residue was chromatographed on a silica
gel column. After removal of Bu3SnCl by hexane,
A Schlenk tube was loaded with trans-(PBu3)2PdCl2
(2) (0.050 g, 0.086 mmol) and Pd(PPh3)4 (0.005 g, 0.004
mmol). After three cycles of vacuum/argon, were added
by syringe Bu3SnCÅ
/
CPh (0.070 g, 0.17 mmol) and THF
(20 ml). After 20 h stirring at 70 8C, 31P-NMR analysis
showed the presence of two compounds, in addition to
elution with hexaneꢁdichlorometane 9:1 produced a
first band containing the unreacted complex 3 [25].
Then, further elution with the same solvent mixture
/

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
417
allowed the separation of a second and a third bands,
which were collected and, after removal of the solvent,
gave di- (5) and mono-substituted (7) products, respec-
tively.
Found: C, 57.32; H, 9.43%. Spectroscopic and analytical
properties are in agreement with reported data [31].
4.4.2. trans-1,4-[PdCl(PBu3)2CÅ
(OC8H17)2 (21)
Dark orange needles crystals. H-NMR (CDCl3): d
0.88 (t, Jꢀ7.1 Hz, 36H, P(CH2)3ÃCH3), 0.89 (t, Jꢀ7.6
Hz, 6H, ÃO(CH2)7ÃCH3), 1.21ꢁ1.72 (m, 72H, PÃCH2Ã
(CH2)2ÃCH3ꢃ OCH2Ã(CH2)6ÃCH3), 1.92 (m, 24H,
PÃCH2Ã), 3.83 (t, Jꢀ6.7 Hz, 4H, ÃOÃCH2Ã), 6.65 (s,
2H, ArÃ
H). 13C-NMR (CDCl3): d 13.7 (P(CH2)3CH3),
13.9 (ÃOCH2Ã(CH2)6ÃCH3), 22.6 (dd, JCÃP 12.6, 14.4
Hz, PÃ(CH2)3Ã OCH2Ã(CH2)6ÃCH3), 24.3 (dd,
JCÃP 7.2 Hz, PÃ(CH2)3Ã), 25.9 (ÃOCH2Ã(CH2)6Ã
CH3), 26.3 (PÃ(CH2)3Ã), 29.2, 29.4, 29.5, 31.7 (Ã
OCH2Ã(CH2)6ÃCH3), 69.0 (ÃOÃCH2Ã), 100.3 (t,
JCÃP 16.2 Hz, ÃCÅC ÃPdÃ), 101.8 (t, JCÃP 5.4 Hz,
C ÅCÃPdÃ
), 115.3 (C1), 116.8 (C3), 152.6 (C2). 31P-
/C]2C6H2-2,5-
1
4.3.1. trans-[Pt(PBu3)2(CÅ
1H-NMR (CDCl3): d 0.91 (t, Jꢀ
1.43 (sx, Jꢀ7.0 Hz, 12H, ÃCH2ÃCH2Ã
12H, ÃCH2ÃCH2ÃCH3), 2.12 (m, 12H, PCH2Ã
7.27 (m, 10H, ArÃ
H). 13C-NMR (CDCl3): d 13.8 (Ã
CH3), 23.9 (dd, JCÃP 16.2, 18.0 Hz), 24.4 (dd,
JCÃP 5.4, 7.2 Hz), 26.6 (dd, JCÃP 10.8, 12.6 Hz)
(PÃ(CH2)3Ã), 108.0 (t, JCÃP 14.4 Hz, ÃC ÅCÃPh),
108.8 (ÃCꢀC ÃPh), 124.7, 127.8 (Ar), 129.1 (C1),
130.7 (Ar). 31P-NMR (CDCl3): d 3.7 (JPÃPt
2359
/
CÃ
/
C6H5)2] (5)
7.3 Hz, 18H, Ã
CH3), 1.59 (m,
), 7.06ꢁ
/
/
/
/
/
CH3),
/
/
/
/
/
/
/
/
/
/
/
Ã
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ꢀ
/
/
/
/
ꢀ
/
ꢀ
/
ꢀ
/
/
/
ꢃ
/
Ã
/
/
/
/
/
ꢀ
/
/
/
/
ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
ꢀ
/
Hz). IR (CH2Cl2, cmꢂ1): 2964 (s), 2934 (s), 2903 (w),
2873 (s), 2101 (s) (nCꢀC), 1593 (m), 1485 (m), 1465 (m),
1379 (w). lmax (CH2Cl2): 327 nm. Anal. Calc. for
C40H64P2Pt: C, 59.91; H, 8.04. Found: C, 59.76; H,
/
/
/
/
/
ꢀ
/
/
/
/
/
ꢀ
/
Ã
/
/
/
/
NMR (CDCl3): d 10.3. IR (CH2Cl2, cmꢂ1): 2973 (s),
2946 (s), 2884 (s), 2842 (m), 2864 (s), 2305 (s), 2110 (m)
(nCÅC), 1494 (m), 1466 (m), 1379 (w). lmax (CH2Cl2): 344
nm. Anal. Calc. for C72H144Cl2O2P4Pd2: C, 60.32; H,
9.85. Found: C, 60.56; H, 10.11%.
8.07%. MS (15 V, ESPꢃ): 803 (MꢃH)ꢃ. Spectroscopic
/
and analytical properties are in agreement with reported
data [27,29].
4.3.2. trans-[PtCl(PBu3)2(CÅ
1H-NMR (CDCl3): d 0.91 (t, Jꢀ
1.45 (sx, Jꢀ7.2 Hz, 12H, ÃCH2ÃCH2Ã
12H, ÃCH2ÃCH2ÃCH3), 1.99 (m, 12H, PCH2Ã
7.28 (m, 5H, ArÃ
H) 13C-NMR (CDCl3): d 13.8 (Ã
CH3), 21.9 (dd, JCÃP 16.2, 18.0 Hz), 24.3 (dd,
JCÃP 5.4, 7.2 Hz), 26.0 (dd, JCÃP 9.0, 10.8 Hz) (PÃ
(CH2)3Ã), 82.9 (t, JCÃP 14.6 Hz, ÃC ÅCÃPh), 101.0 (t,
JCÃP 2.4 Hz, ÃCÅC ÃPh), 125.0, 127.9 (Ar), 128.9
2373
/
CÃ
/
C6H5)] (7)
7.2 Hz, 18H, Ã
CH3), 1.60 (m,
), 7.07ꢁ
4.4.3. trans-1,4-[PtCl(PBu3)2CÅ
Yellow crystalline solid. 1H-NMR (CDCl3): d 0.89 (t,
Jꢀ7.0 Hz, 36H, ÃCH3), 1.41 (sx, Jꢀ7.0 Hz, 24H, Ã
CH2ÃCH2ÃCH3), 1.54 (m, 24H, ÃCH2ÃCH2ÃCH3),
1.97 (m, 24H, PÃCH2Ã), 7.05 (s, 4H, ArÃ
H). 13C-
NMR (CDCl3): d 13.7 (ÃCH3), 21.9 (dd, JCÃP 17.1
Hz), 24.3 (dd, JCÃP 6.1, 7.3 Hz), 26.1 (PÃ(CH2)3Ã),
83.5 (t, JCÃP 14.6 Hz, ÃCÅC ÃPtÃ), 101.3 (t, JCÃP
2.4 Hz, ÃC ÅCÃPtÃ
), 125.6 (C1), 130.3 (C2). 31P-NMR
(CDCl3): d 7.4 (JPÃPt
2366 Hz). IR (CH2Cl2, cmꢂ1):
2964 (s), 2933 (s), 2875 (s), 2119 (s) (nCÅC), 1499 (m),
1465 (m). lmax (CH2Cl2): 348 nm. Anal. Calc. for
C58H112Cl2P4Pt2: C, 49.96; H, 8.10. Found: C, 49.78;
H, 8.20%. Spectroscopic and analytical properties are in
agreement with reported data [31,32].
/
C]2C6H4 (20)
/
/
CH3),
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ꢀ
/
/
ꢀ
/
ꢀ
/
ꢀ
/
/
ꢀ
/
/
/
/
ꢀ
/
/
/
/
ꢀ
/
/
/
/
/
ꢀ
/
ꢀ
/
/
/
/
/
/
/
/
(C1), 130.7 (Ar). 31P-NMR (CDCl3): d 7.5 (JPÃPt
ꢀ
/
ꢀ
/
Hz). IR (CH2Cl2, cmꢂ1): 2964 (s), 2933 (s), 2933 (s),
2874 (s), 2119 (s) (nCÅC), 1593 (m). lmax (CH2Cl2): 287
nm. Anal. Calc. for C32H59ClP2Pt: C, 52.20; H, 8.08.
Found: C, 52.38; H, 8.28%. MS (15 V, ESPꢃ): 742 (Mꢃ
/
Li)ꢃ. Spectroscopic and analytical properties are in
agreement with reported data [30].
4.4.4. trans-1,4-[PtCl(PBu3)2CÅ
(OC8H17)2 (22)
Yellow crystalline solid. 1H-NMR (CDCl3): d 0.88 (t,
Jꢀ7.0 Hz, 42H, P(CH2)3ÃCH3ꢃ O(CH2)7ÃCH3),
1.23ꢁ1.74 (m, 72H, PÃCH2Ã(CH2)2ÃCH3ꢃ OCH2Ã
(CH2)6ÃCH3), 2.01 (m, 24H, PÃCH2Ã), 3.83 (t, Jꢀ7.0
Hz, 4H, ÃOÃCH2Ã), 6.64 (s, 2H, ArÃ
H). 13C-NMR
(CDCl3): d 13.8 (P(CH2)3CH3), 14.1 (ÃOCH2Ã(CH2)6Ã
CH3), 21.8 (dd, JCÃP 17.0 Hz, PÃ(CH2)3Ã), 22.7 (Ã
OCH2Ã(CH2)6ÃCH3), 24.3 (dd, JCÃP 6.8 Hz, PÃ
(CH2)3Ã), 26.0 (ÃOCH2Ã(CH2)6ÃCH3), 26.1 (PÃ
(CH2)3Ã), 29.3, 29.5, 29.7, 31.9 (ÃOCH2Ã(CH2)6Ã
CH3), 69.1 (ÃOÃCH2Ã), 86.4 (t, JCÃP 15.8 Hz, ÃCÅ
C ÃPtÃ), 97.2 (t, JCÃP 2.3 Hz, ÃC ÅCÃPtÃ), 116.0
(C1), 117.0 (C3), 152.9 (C2). 31P-NMR (CDCl3): d 7.6
(JPÃPt
2368 Hz) IR (CH2Cl2, cmꢂ1): 2963 (s), 2933 (s),
/
C]2C6H2-2,5-
4.4. Characterization of bimetallic complexes
4.4.1. trans-1,4-[PdCl(PBu3)2CÅ
Pale yellow needles crystals. 1H-NMR (CDCl3): d
0.89 (t, Jꢀ7.0 Hz, 36H, ÃCH3), 1.41 (sx, Jꢀ7.0 Hz,
24H, ÃCH2ÃCH2ÃCH3), 1.54 (m, 24H, ÃCH2ÃCH2Ã
CH3), 1.90 (br, 24H, PÃCH2Ã), 7.07 (s, 4H, ArÃH).
13C-NMR (CDCl3): d 13.5 (Ã
CH3), 22.5 (dd, JCÃP
13.6 Hz), 24.1 (dd, JCÃP 6.8 Hz), 26.1 (PÃ(CH2)3Ã
96.7 (t, JCÃP 15.8 Hz, ÃCÅC ÃPdÃ), 105.7 (t, JCÃP
5.7 Hz, ÃC ÅCÃPdÃ
), 124.7 (C1), 129.9 (C2). 31P-NMR
/
C]2C6H4 (19)
/
/
/
Ã
/
/
/
/
/
/
/
Ã
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
ꢀ
/
ꢀ
/
/
/
/
ꢀ
/
/
/
),
/
/
ꢀ
/
/
ꢀ
/
/
/
/
/
ꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
(CDCl3): d 10.4. IR (CH2Cl2, cmꢂ1): 2971 (s), 2941 (w),
2879 (s), 2836 (m), 2686 (s), 2306 (s), 2115 (m) (nCÅC),
1464 (w), 1420 (w), 1379 (w). lmax (CH2Cl2): 308 nm.
Anal. Calc. for C58H112Cl2P4Pd2: C, 57.23; H, 9.27.
/
/
/
ꢀ
/
/
/
/
/
ꢀ
/
/
/
/
/
ꢀ
/

418
A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
/
2874 (s), 2114 (m) (nCÅC), 1606 (m), 1494 (m), 1466 (m).
lmax (CH2Cl2): 395 nm. Anal. Calc. for
C74H144Cl2O2P4Pt2: C, 53.84; H, 8.79. Found: C,
53.51; H, 8.72%.
hours (70 8C, 8 h for 2 in dioxane, 110 8C, 26 h for 3 in
toluene). After cooling to room temperature, the reac-
tion mixture was concentrated to a minimum volume,
and then diluted with methanol until a solid precipitate
was obtained, which was washed repeatedly with
methanol and dried under vacuum.
4.5. General preparation of polymers
4.5.1. trans-1,4-[Pd(PBu3)2Ã
/
CÅ
Coffee-brown solid. H-NMR (CDCl3): d 0.89 (br,
18H, ÃCH3), 1.42 (br, 12H, ÃCH2ÃCH2ÃCH3), 1.54
(br, 12H, ÃCH2ÃCH2ÃCH3), 1.90 (br, 12H, PCH2Ã),
7.07 (br, 4H, ArÃ
CH3), 22.8, 24.4, 26.4 (PÃ
/
CÃ
/
C6H4Ã
/
CÅ
/
C]n (15)
A Schlenk tube was loaded with the metal complexes
2 or 3 and an equivalent amount of the distannyl
compounds 13 or 14. After three cycles of vacuum/
argon, solvent (dioxane for palladium complex 2 and
toluene for platinum complex 3) was added by syringe.
The reaction mixture was heated to reflux for several
1
/
/
/
/
/
/
/
/
/
H). 13C-NMR (CDCl3): d 13.8 (Ã
/
/
(CH2)3Ã
/
), 106.1 (Ã
/
C Å
/
C Ã/),
131.2 (m, Ar). 31P-NMR (CDCl3): d 10.6 (br). IR
(CH2Cl2, cmꢂ1): 2970 (w), 2943 (w), 2885 (w), 2843 (w),
2304 (s), 2112 (w) (nCÅC), 1598 (w), 1464 (w), 1414 (w),
1379 (w). lmax (CH2Cl2): 315 nm. Spectroscopic and
analytical properties are in agreement with reported
data [31,33].
Table 4
Crystal data and structure refinement
Identification code
19
21
Empirical formula
Formula weight
Temperature (K)
C
58H112Cl2P4Pd2
C74H144Cl2O2P4Pt2
1473.47
293(2)
4.5.2. trans-1,4-[Pd(PBu3)2Ã
(OC8H17)2)ÃCÅC]n (16)
Dark brown sticky oil. 1H-NMR (CDCl3): d 0.86 (br,
24H, P(CH2)3ÃCH3ꢃ O(CH2)7ÃCH3), 1.26ꢁ2.03 (m,
60H, P(CH2)3CH3ꢃ OCH2(CH2)6CH3), 3.85 (br, 4H,
OÃCH2Ã), 6.70 (br, 2H, ArÃ
H). 13C-NMR (CDCl3):
d 13.9 (P(CH2)3CH3), 14.1 (ÃOCH2Ã(CH2)6ÃCH3),
22.7ꢁ31.9 (PÃ(CH2)3ÃCH3ꢃ OCH2Ã(CH2)6ÃCH3),
69.1 (ÃOÃCH2Ã), 106.6 (ÃC ÅC Ã), 115.8 (C1), 117.4
/
CÅ
/
CÃ
/
C6H2(2,5-
1217.06
293(2)
1.54180
Monoclinic
C2/c
/
/
˚
Wavelength (A)
0.71073
Triclinic
¯
P1
/
/
Ã
/
/
/
Crystal system
Space group
Unit cell dimensions
/
Ã
/
/
Ã
/
/
/
/
˚
a (A)
35.332(5)
16.502(7)
13.006(3)
12.228(6)
12.960(2)
15.898(2)
101.048(12)
99.05(2)
113.791(17)
2184.0(12)
1
/
/
/
˚
b (A)
/
/
/
/
Ã
/
/
/
˚
c (A)
/
/
/
/
/
/
a (8)
b (8)
(C3), 152.7 (C2). 31P-NMR (CDCl3): d 10.3 (br,
terminal), 11.3 (br, internal). IR (CH2Cl2, cmꢂ1): 2882
(w), 2845 (w), 2684 (s), 2305 (s), 2097 (w) (nCÅC), 1605
(m), 1493 (w), 1467 (w). lmax (CH2Cl2): 374 nm.
113.16(3)
g (8)
3
V (A )
˚
6972(4)
4
1.159
Z
Dcalc (g cmꢂ3
)
1.120
0.582
Absorption coefficient 5.949
(mmꢂ1
4.5.3. trans-1,4-[Pt(PBu3)2Ã
/
CÅ
brown solid. H-NMR (CDCl3): d 0.89 (br,
CH3), 1.42 (br, 12H, ÃCH2ÃCH2ÃCH3), 1.56
(br, 12H, ÃCH2ÃCH2ÃCH3), 2.10 (br, 12H, PCH2Ã),
7.07 (br, 4H, ArÃ
H). 13C-NMR (CDCl3): d 13.8 (Ã
CH3), 23.9 (dd, JCÃP 18.0 Hz, JCÃP 16.2 Hz), 24.4
(dd, JCÃP 7.2 Hz), 26.3 (P(CH2)3CH3), 109.4 (ÃC Å
C Ã
), 125.5 (C1), 130.3 (C2). 31P-NMR (CDCl3): d 3.5
(JPÃPt 2366 Hz, term-
/
CÃ
/
C6H4Ã
/
CÅ
/
C]n (17)
)
1
F(000)
2584
0.50ꢄ
2.72ꢁ55.07
790
Yellowꢁ
/
Crystal size (mm3)
u Range for data
collection (8)
/0.50ꢄ/0.08
0.60ꢄ
/
0.45ꢄ0.08
/
18H, Ã
/
/
/
/
/
2.01ꢁ22.97
/
/
/
/
/
/
/
Index ranges
ꢂ
/
375
135
175
8714
/
h 5
k 5
l 517
/
37,
ꢂ
/
135
145
05l 5
6045
/
h 5
k 5
17
/
13,
ꢀ
/
ꢀ
/
ꢂ
/
/
/
2
ꢂ
/
/
/
13,
ꢂ
/
/
/
ꢂ/
/
/
ꢀ
/
/
/
Reflections collected
Independent
reflections
/
4386 [Rint
ꢀ/
0.3405]
6045 [Rint
ꢀ/0.0000]
ꢀ
/
2355 Hz, internal), 7.4 (JPÃPt
ꢀ
/
inal). IR (CH2Cl2, cmꢂ1): 2964 (s), 2933 (s), 2874 (s),
2098 (s) (nCÅC), 1597 (m), 1499 (m), 1465 (m). lmax
(CH2Cl2): 364 nm. Spectroscopic and analytical proper-
ties are in agreement with reported data [32b,34].
Completeness to
100.0%
99.7%
uꢀ/55.078
Max/min transmission 0.6639/0.1549
0.9576/0.7213
Refinement method
Full-matrix least-
squares on F2
4386/0/145
Data/restraints/
parameters
Goodness-of-fit on F2 1.347
6045/39/222
1.013
4.5.4. trans-1,4-[Pt(PBu3)2Ã
(OC8H17)2)ÃCÅC]n (18)
Dark brown sticky oil. 1H-NMR (CDCl3): d 0.89 (br,
24H, P(CH2)3ÃCH3ꢃ O(CH2)7ÃCH3), 1.23ꢁ2.21 (m,
60H, P(CH2)3CH3ꢃ OCH2(CH2)6CH3), 3.85 (br, 4H,
OÃCH2Ã), 6.64, 6.68 (ArÃ
H). 13C-NMR (CDCl3): d
13.8 (P(CH2)3CH3), 14.0 (ÃOCH2Ã(CH2)6ÃCH3),
21.5ꢁ31.9 (PÃ(CH2)3ÃCH3ꢃ OCH2Ã(CH2)6ÃCH3),
/
CÅ
/
CÃ/C6H2(2,5-
/
/
Final R indices
[I ꢁ2s(I)]
R indices (all data)
R1ꢀ
0.4718
R1ꢀ0.2913, wR2ꢀ
0.5342
Largest difference peak 1.387 and ꢂ
/0.2076, wR2ꢀ
/
R1ꢀ
0.1844
R1ꢀ0.1430, wR2ꢀ
0.2235
0.686 and ꢂ
/
0.0741, wR2ꢀ
/
/
/
/
Ã
/
/
/
/
/
/
/
/
Ã
/
Ã
/
/
/
/
/0.771
/
0.4553
ꢂ3
˚
/
/
/
and hole (e A
)
/
/
/
/
Ã
/
/
/

A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ
/420
419
69.1 (Ã
/
OÃ
/
CH2Ã
/
), 97.3, 105.3 (Ã
/
C Å
/
C Ã
/
), 117.0 (C1),
117.1 (C3), 152.9 (C2). 31P-NMR (CDCl3): d 3.9
Acknowledgements
(JPÃPt
ꢀ
/
2364 Hz, internal), 7.6 (JPÃPt
ꢀ
/
2368 Hz, term-
This work was supported by the Consiglio Nazionale
delle Ricerche (C.N.R. Roma), with the ‘Progetto
Finalizzato C.N.R.-Materiali Speciali per Tecnologie
Avanzate II’, contract no. 97.00946.PF34, and the
‘Progetto Finalizzato C.N.R.-Materiali e Dispositivi
inal). IR (CH2Cl2, cmꢂ1): 2965 (s), 2935 (s), 2875 (s),
2096 (s) (nCÅC), 1494 (m), 1466 (m). lmax (CH2Cl2): 395
nm.
per l’Elettronica
97.01350.PF48.
a
Stato Solido’, contract no.
4.6. X-ray diffraction studies
A summary of crystal and intensity data for com-
pounds 19 and 21 is presented in Table 4.
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A. La Groia et al. / Journal of Organometallic Chemistry 683 (2003) 406ꢁ420
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