Preparation and characterisation of neutral double- and monoalkynyl bridged diplatinum complexes

Article abstract of DOI:10.1039/b104783n

The novel acetylide complexes [trans-Pt(C≡CR)₂(PPh₃)₂] [R=(Z)-CMe=CHMe 2a and C(OMe)EtMe 3] have been prepared starting from [trans-Pt{C≡CC(OH)EtMe}₂(PPh₃)₂] 1 by dehydration (2a) and etherification (3) reactions, respectively. The analogous α-hydroxyacetylide, R=C(OH)Ph₂ 4, has been obtained by reaction of [cis-PtCl₂(PPh₃)₂] with HC≡CC(OH)Ph₂ in NEt₂H, in presence of CuI. These bis(acetylide) complexes react with [cis-Pt(C₆F₅)₂(THF)₂] leading to symmetrical diplatinum species [trans,trans-(PPh₃)(C₆F₅)Pt(μ-1κC ^α:η²-C≡CR)(μ-2κC ^α:η²-C=CR)Pt(C₆F₅)- (PPh₃)] [R=C(OH)EtMe 5, (Z)-CMe=CHMe 6, C(OMe)EtMe 7, C(OH)Ph₂ 8] containing a double alkynyl bridging system. Complexes 5 and 7 have been obtained as mixtures of the corresponding RR/SS and RS/SR diastereomers (1:1 molar ratio). Treatment of 4-8 with 2 equivalents of PPh₃ produces bridge splitting to yield the corresponding mixed mononuclear derivatives [trans-Pt(C≡CR)(C₆F₅)(PPh₃) ₂] [R=C(OH)EtMe 9, (Z)-CMe=CHMe 10, C(OMe)-EtMe 11, C(OH)Ph₂ 12]. Treatment of the hydroxyalkynyl complex 9 with HBF₄ in Et₂O also produces the dehydrated enynyl derivative 10. The mononuclear complexes [trans-Pt(C≡CR)₂(PPh₃)₂] (1, 3, 4) react with [cis-Pt(C₆F₅)₂(CO)-(THF)] to afford, under alkynylation of the carbonyl fragment "Pt(C₆F₅)₂(CO)", the μ-η²-acetylide-bridged zwitterionic derivatives [cis,trans-(CO)(C₆F₅)₂Pt(μ-1κC ^α:η²-C≡CR)Pt(C≡CR)(PPh ₃)₂] [R=C(OH)EtMe 13, C(OMe)EtMe 14, C(OH)Ph₂ 15]. On the other hand, while the analogous reaction with the bis-enynyl complex 2a is not clean, the related mixed pentafluorophenyl enynyl complex 10 produces the simple displacement of THF from [cis-Pt(C₆F₅)₂(CO)(THF)] by the alkynyl fragment and formation of the adduct [trans,cis-(PPh₃)₂(C₆F₅) {μ-1κC^α:η²-C^3,4-C≡ C-(Z)-CMe=CHMe}Pt(C₆F₅)₂(CO)] 16. The crystal structures of 7, 8 and 13 have also been determined. For complex 8, the dimer units are linked via unusual intermolecular hydrogen bonds (O-H···F-C) leading to an extended polymeric chain along the crystallographic c axis.

Full text of DOI:10.1039/b104783n

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Preparation and characterisation of neutral double- and mono-
alkynyl bridged diplatinum complexes†
Jesús R. Berenguer,a Juan Forniés,*b Elena Lalinde,*a Antonio Martínb and Blanca Serranoa
a Departamento de Química-Grupo de Síntesis Química de La Rioja, UA-CSIC Universidad de
La Rioja, 26001 Logroño, Spain
b Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-Consejo Superior de
Investigaciones Científicas, 50009 Zaragoza, Spain
Received 31st May 2001, Accepted 25th July 2001
First published as an Advance Article on the web 5th September 2001
᎐
The novel acetylide complexes [trans-Pt(C᎐CR) (PPh ) ] [R = (Z)-CMe᎐CHMe 2a and C(OMe)EtMe 3] have been
᎐
᎐
2
3 2
᎐
prepared starting from [trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 by dehydration (2a) and etherification (3) reactions,
᎐
2
3 2
respectively. The analogous α-hydroxyacetylide, R = C(OH)Ph2 4, has been obtained by reaction of [cis-PtCl2(PPh3)2]
᎐
with HC᎐CC(OH)Ph in NEt H, in presence of CuI. These bis(acetylide) complexes react with [cis-Pt(C F ) (THF) ]
᎐
2
2
6
5
2
2
α
2
α
2
᎐
leading to symmetrical diplatinum species [trans,trans-(PPh )(C F )Pt(µ-1κC :η -C᎐CR)(µ-2κC :η -C᎐CR)Pt(C F )-
᎐
᎐
3
6
5
6
5
(PPh )] [R = C(OH)EtMe 5, (Z)-CMe᎐CHMe 6, C(OMe)EtMe 7, C(OH)Ph 8] containing a double alkynyl bridging
᎐
3
2
system. Complexes 5 and 7 have been obtained as mixtures of the corresponding RR/SS and RS/SR diastereomers
(1 : 1 molar ratio). Treatment of 4–8 with 2 equivalents of PPh3 produces bridge splitting to yield the corresponding
᎐
mixed mononuclear derivatives [trans-Pt(C᎐CR)(C F )(PPh ) ] [R = C(OH)EtMe 9, (Z)-CMe᎐CHMe 10, C(OMe)-
᎐
᎐
6
5
3 2
EtMe 11, C(OH)Ph2 12]. Treatment of the hydroxyalkynyl complex 9 with HBF4 in Et2O also produces the dehydrated
᎐
enynyl derivative 10. The mononuclear complexes [trans-Pt(C᎐CR) (PPh ) ] (1, 3, 4) react with [cis-Pt(C F ) (CO)-
᎐
2
3
2
6
5 2
(THF)] to afford, under alkynylation of the carbonyl fragment “Pt(C6F5)2(CO)”, the µ-η2-acetylide-bridged
α
2
᎐
᎐
zwitterionic derivatives [cis,trans-(CO)(C F ) Pt(µ-1κC :η -C᎐CR)Pt(C᎐CR)(PPh ) ] [R = C(OH)EtMe 13,
᎐
᎐
6
5
2
3 2
C(OMe)EtMe 14, C(OH)Ph2 15]. On the other hand, while the analogous reaction with the bis-enynyl complex 2a is
not clean, the related mixed pentafluorophenyl enynyl complex 10 produces the simple displacement of THF from
[cis-Pt(C6F5)2(CO)(THF)] by the alkynyl fragment and formation of the adduct [trans,cis-(PPh3)2(C6F5){µ-1κCα:η2-
C3,4-C᎐C-(Z)-CMe᎐CHMe}Pt(C F ) (CO)] 16. The crystal structures of 7, 8 and 13 have also been determined.
᎐
᎐
᎐
6
5 2
For complex 8, the dimer units are linked via unusual intermolecular hydrogen bonds (O–H ؒ ؒ ؒ F–C) leading to an
extended polymeric chain along the crystallographic c axis.
The chemistry of alkynyl platinum derivatives has been the
subject of longstanding interest mainly focused on structure,
reactivity and physical properties.1 In recent years, considerable
efforts have been directed towards the preparation of specialty
materials including non-linear optical,2 liquid crystalline3 or
luminescent materials.4 Platinum σ-acetylide (including diynyl
and functionalised ligands) fragments have been employed as
building blocks in the synthesis of macrocycles or branched
materials (dendrimers)5 and conjugated metal-containing
polymers,6 which are particularly attractive due to their
potentially useful photophysical properties. The additional η2-
coordinating capability of these ligands has also been widely
used to construct heteropolymetallic systems1a,b which are
attractive, not only for their structural richness,7 but also for
their interesting emissive properties.4b,c,8 As part of our work in
this area, we have investigated the factors that govern the final
structural disposition of the alkynyl ligands on complexes
substituents. It should be noted that these types of complexes
have also been found as intermediates in the reaction pathway
of carbon–carbon coupling processes leading to free or com-
plexed diynes.10
The most general synthetic approach to these types of com-
plexes employs a preformed bis- (usually cis) or tetra-alkynide
platinum derivative as starting building block,8,11,12 and a
second, coordinatively unsaturated, substrate or a solvento
complex, thus leading to heterometallic and unsymmetrical
final systems. Symmetrical diplatinum complexes stabilized by
a double alkynide bridging system are scarce, probably due to
the lack of adequate precursors. The only examples known
(reported by us) are: the anionic derivatives [(C6F5)2Pt-
2Ϫ
(µ-C᎐CR)]
(R = Ph, But)13 prepared from the dianionic
᎐
᎐
2
mixed species [cis-Pt(C F ) (C᎐CR) ]2Ϫ and the solvate complex
᎐
᎐
6
5
2
2
[cis-Pt(C6F5)2(THF)2] via migration of one σ-alkynyl group
between the two platinum metal centres; and the neutral
1b,9
compounds [trans-Pt(µ-C᎐CR)(C F )(PPh )] (R = Ph, But,
᎐
᎐
stabilised by double alkynide-bridging systems (µ-C᎐CR) .
᎐
᎐
2
6
5
3
2
We have found that the preferred σ/η2 coordination sites,
obviously related to ligand exchange processes, as well as the
final planar or hinged geometries found, are governed by a
tuned balance of electronic and steric effects, which can be
seen from a distinct influence of metals, coligands and alkynyl
SiMe3),14 generated by a redistribution of ligands between
᎐
[trans-Pt(C᎐CR) (PPh ) ] and the corresponding synthon
᎐
2
3 2
“Pt(C6F5)2”. In contrast to this behaviour, we have observed
᎐
that [trans-Pt(C᎐CR) L ] (L = PPh , PEt ) reacts with [cis-
᎐
2
2
3
3
Pt(C6F5)2(CO)(THF)], which contains only one labile co-
ordination site, yielding, through alkynylation of the carbonyl
platinum fragment, formally zwitterionic complexes [cis,trans-
† Electronic supplementary information (ESI) available: tables of
NMR data for 1–16; variable temperature 1H and 19F NMR spectra for
7; molecular structure diagrams for 8ؒCH2Cl2 and the SS isomer of 13.
See http://www.rsc.org/suppdata/dt/b1/b104783n/
Ϫ
α
2
ϩ
t
᎐
᎐
Pt (C F ) (CO)(µ-κC :η -C᎐CR)Pt (C᎐CR)L ] (R = Ph, Bu ,
᎐
᎐
6
5
2
2
SiMe3)15 with only one alkynyl group connecting the platinum
centres. The alkynyl substituent seems to have an influence on
2926
J. Chem. Soc., Dalton Trans., 2001, 2926–2936
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b104783n

View Article Online
᎐
the final geometry and stability of these dimers. Thus, while
[trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1, which was reported
᎐
2 3 2
2
previously,18 and [trans-Pt{C᎐CC(OH)Ph } (PPh ) ]
4 was
᎐
᎐
the neutral complex [Pt(µ-σ:η -C᎐CPh)(C F )(PPh )] shows a
᎐
᎐
6
5
3
2
2 2 3 2
planar PtC4Pt core, the analogous tert-butyl derivative exhibits
a non-planar structure, as is suggested by variable 19F NMR
data.14 On the other hand, while the η2-acetylenic interaction is
quite stable in the bimetallic zwitterionic derivatives with
R = Ph, But, being inert towards Ph2C2, CO, Py, PPh3 or HBF4,
based on a slight modification of the method reported by
Furlani et al., by refluxing [cis-PtCl2(PPh3)2] for 20 minutes with
᎐
an excess of the corresponding propargyl alcohol (Pt/HC᎐CR
᎐
1 : 14 for 1 and 1 : 2.3 for 4) in NEt2H (≈15 cm3) and in the
presence of catalytic amounts of CuI (Scheme 1, i). The result-
ing white suspensions were evaporated to dryness and treated
with EtOH, affording the final complexes in very high yield
(90% 1, 75% 4). The spontaneous, or induced, dehydration
process of unsaturated hydroxyhydrocarbon ligands is a very
common feature in organometallic chemistry.18b,19 Initial
attempts18b to induce the dehydration process by refluxing
complex 1 in toluene for 1 hour were unsuccessful. However, if
the complex is refluxed in the presence of acidic alumina
(Scheme 1, v), a yellow microcrystalline solid is obtained.
This was identified by NMR spectroscopy (1H, 13C and 31P,
see Experimental and Table S4 in the ESI) as a mixture of
Ϫ
α
2
᎐
the analogous [cis,trans-Pt (C F ) (CO)(µ-κC :η -C᎐CSiMe )-
᎐
6
5
2
3
ϩ
᎐
Pt (C᎐CSiMe )L ] readily interact with alcohols (EtOH, Me-
᎐
3
2
OH) yielding (µ-ethynediyl)(methylalkoxycarbene)diplatinum
16
᎐
species [cis,trans-(CO)(C F ) Pt(–C᎐C–)Pt{C(Me)OR}L ].
᎐
6
5
2
2
All these results prompted us to investigate the effect of
the alkynyl substituents on the course of these reactions and
initially we focused our interest on the α-hydroxyalkynide
᎐
complexes [trans-Pt(C᎐CR) (PPh ) ] [R = C(OH)EtMe 1;
᎐
2
3 2
C(OH)Ph2 4], and on the enyne and methyl-ether analogous
derivatives [R = (Z)-CMe᎐CHMe 2a and C(OMe)EtMe 3,
᎐
respectively], which were formed from 1. Thus, in this paper we
᎐
᎐
᎐
report the synthesis and characterisation of [trans-Pt(C᎐CR) -
[trans-Pt{C᎐C-(Z)-CMe᎐CHMe} (PPh ) ] 2a, [trans-Pt(C᎐C-
᎐ ᎐
2 3 2
᎐
᎐
2
᎐
(PPh3)2] (2–4), and describe their reactions towards the solvate
complexes [cis-Pt(C6F5)2(THF)2] and [cis-Pt(C6F5)2(CO)-
CEt᎐CH ) (PPh ) ] 2b and [trans-Pt{C᎐C-(Z)-CMe᎐CH-
᎐ ᎐ ᎐
2 2 3 2
Me}(C᎐CCEt᎐CH )(PPh ) ] 2c in a ca. molar ratio of 2 : 1 : 1
᎐
᎐
᎐
2
3 2
(THF)], respectively. Several mixed mononuclear complexes
(2a : 2b : 2c). Under these conditions, the two most plausible
forms of H2O elimination within the acetylenic moieties (Me
and Et) seem to be greatly facilitated. In our hands, further
attempts to separate this mixture were unsuccessful. The regio-
selectivity of the water elimination is notably increased using
milder conditions. Thus, the Saytzeff product 2a (in which the
double bond goes mainly towards the most highly substituted
carbon) can be obtained in 73% yield by room temperature
stirring of a solution of 1 in chloroform with HBF4 (two drops
of a 0.1 M solution in Et2O) for only 5 minutes (Scheme 1, ii).
The use of higher amounts of HBF4 or longer reaction times
lead again to mixtures of 2a, 2b and 2c.
᎐
[trans-Pt(C᎐CR)(C F )(PPh ) ] (9–12), obtained from the
᎐
6
5
3 2
symmetrical dimers [trans,trans-(PPh3)(C6F5)Pt(µ-1κCα:η2-
α
2
᎐
᎐
C᎐CR)(µ-2κC :η -C᎐CR)Pt(C F )(PPh )] (5–8) by bridge
᎐
᎐
6
5
3
splitting reactions with PPh3, and some reactivity studies are
also presented. The crystal structures of complexes [trans,trans-
α
2
α
2
᎐
᎐
(PPh )(C F )Pt(µ-1κC :η -C᎐CR)(µ-2κC :η -C᎐CR)Pt(C F )-
᎐
᎐
3
6
5
6
5
(PPh3)] [R = C(OMe)EtMe 7, C(OH)Ph2 8] have also been
included. The preparation of [trans,trans-(PPh3)(C6F5)Pt{µ-
α
2
α
2
᎐
᎐
᎐
1κC :η -C᎐CC(OH)EtMe}{µ-2κC :η -C᎐CC(OH)EtMe}Pt-
᎐
(C6F5)(PPh3)] 5, which reacted with PhSH yielding a very un-
usual thiolate cyclobutenediylidene heterobridged diplatinum
Although the Saytzeff process could lead to several isomers
for 2 (ZZ, EE, ZE), only one set of signals was observed by
ؒ ؒ ؒ
ؒ ؒ ؒ
ؒ ؒ ؒ
complex {cis-(PPh )(C F )Pt[µ
C
C(CEtMeOH) C(C᎐
––
–– ––
᎐
3
6
5
CEtMe)](µ-SPh)Pt(C6F5)(PPh3)} has been included in a pre-
liminary report.17
NMR spectroscopy. The corresponding methoxy derivative
᎐
[trans-Pt{C᎐CC(OMe)EtMe} (PPh ) ] 3 is easily obtained, as a
᎐
2
3 2
white solid, in moderate yield (68%) by refluxing complex 1 in
MeOH for 36 hours (Scheme 1, iii); but, again, the etherifica-
tion process is accelerated in the presence of HBF4 (97% yield,
Scheme 1, iv, see Experimental). The characterisation of com-
plex 1 has been reported previously.17 The remaining complexes
2–4 have been characterised by microanalysis, mass spectra
Results and discussion
᎐
Synthesis of [trans-Pt(C᎐CR) (PPh ) ]
᎐
2
3 2
The preparation of the precursors (1–4) is summarized in
Scheme 1. The synthesis of the bis(alkoxyalkynyl) complexes
᎐
Scheme 1 [Pt] = trans-Pt(PPh3)2. Reagents and conditions: (i) HC᎐CR ϩ CuI (cat), NEt2H, 20 min, reflux; (ii) HBF4 (cat), CHCl3, rt, immediately;
᎐
(iii) MeOH, 36 hours, reflux; (iv) HBF4 (cat), MeOH, 30 min, reflux; (v) Al2O3, toluene, 1 hour.
J. Chem. Soc., Dalton Trans., 2001, 2926–2936
2927

View Article Online
[FABϩ] and IR and NMR (1H, 13C{1H} and 31P{1H}) spec-
troscopy (details are given in the Experimental and Tables S1
and S2 of the ESI). It should be noted that complex 3 (and
also 1), with two stereogenic centres, should be a mixture of dl
and meso diastereomers, but the NMR data show no evidence
confirmed by X-ray crystallography on complex 7. These
dimers have both equivalent metal centres on the RR/SS pair
due to the presence of a C2 axis, but they are inequivalent on the
RS/SR pair. Therefore, three sets of resonances in a 2 : 1 : 1
molar ratio should be expected for both complexes 5 and 7
which are 1 : 1 diastereomeric mixtures. Furthermore, the five
fluorine resonances due to each C6F5 ring (endo and exo on
ortho-F, meta-F and para-F) are non-equivalent for a bent
conformation of the central dimetallacycle. Only for complex 7
(δP 12.9 5, 13.0 7) is the singlet observed in the 31P{1H} NMR
spectrum split at low temperature (Ϫ50 ЊC) into two different
signals of equal intensity [δ 13.5, 13.4 J(PtP) ≈ 3900 Hz],
suggesting that the expected two different resonances for the
RS/SR pair are isochronous. A similar pattern is observed for
for this. The presence of alkynyl ligands is confirmed by the
᎐
presence, in the IR spectra, of a ν(C᎐C) absorption in the range
᎐
2122–2088 cmϪ1. Complex 4 also shows the expected IR
absorption band due to ν(O–H) (3558 cmϪ1), and displays a
1
broad singlet at δ 1.17 in its H NMR spectrum. This signal
disappears upon addition of a drop of D2O and, therefore, is
assigned tentatively to the OH group.
The trans geometry in all complexes is suggested by the
1
magnitude of the J(PtP) coupling constant (2654–2699 Hz, δP
18.6–19.4); and it is confirmed unambiguously by 13C NMR
spectroscopy.20 In particular, the resonance of the acetylenic
carbons [δ Cα/Cβ 112.8/112.9 2a; 111.8/112.8 3; (4 is not
sufficiently soluble), which are easily identified due to the
presence of platinum satellites [1J(PtCα)/2J(PtCβ) 946/244 2a;
939/244 Hz 3], are seen as typical AX2 (X = P) systems. In this
regard, it should be noted that although there are reported
examples of stereospecific syntheses of platinum diacetylide
complexes starting from cis-platinum dichlorides,21a,b or
even cis/trans mixtures,21c usually the presence of metal salts,
including CuI, catalyses the isomerization of the less stable cis-
platinum diacetylides to the corresponding trans-derivatives.5i,22
In the proton spectrum of complex 2a a quartet at δ 4.88 and
a doublet at δ 0.96 [J(HH) = 6 Hz], together with a singlet at
complex 5 in its H NMR spectrum, which exhibits only two
1
different sharp hydroxyl (δ 1.40, 1.38 at 16 ЊC; 1.35, 1.36 at
40 ЊC) and methyl (δ 0.54, 0.49 at 16 ЊC; 0.56, 0.51 at 40 ЊC)
resonances due to the alkynyl C(OH)(CH3)Et groups, even at
high temperature. On cooling, the line shapes of all signals
broaden but at Ϫ50 ЊC only coalescence of the hydroxyl
resonances has been detected.
In contrast, for complex 7 (see Fig. S1 in the ESI) the sharp
OMe resonance observed at high temperature (δ 2.79) broadens
as the temperature is lowered, and coalesces between Ϫ5 and
Ϫ10 ЊC, finally giving, in the low exchange region, the expected
three singlets at δ 3.15 (two CH3 due to the RR/SS isomer) and
at δ 2.63 (CH3) and 2.56 (CH3) (RS/SR), respectively. The
σ/π pairwise intramolecular exchange and fast inversion of the
central ring (for bent systems) are common features for this
type of complex. For both complexes (5 and 7) only broad
resonances are observed in the ortho- and meta-fluorine regions
in their 19F NMR spectra at room temperature. At low tempera-
ture (Ϫ50 ЊC, see Fig. S2 for complex 7, ESI) both derivatives
show patterns confirming the presence of at least two non-
equivalent and rigid C6F5 rings. It should be noted that for
complex 7, even at high temperature (40 ЊC), two different para-
F resonances are clearly seen, suggesting that the diastereomers
do not interconvert. The observed equivalence, seen as broad
signals (40 ЊC for 7 or 16 ЊC for 5), for the resonances due to
ortho-F and meta-F seems to be casual and the exchange
between endo and exo fluorine resonances could be due to an
induced free rotation of the C6F5 rings, because a simple fast
inversion of the central metallacycle, which can not be
excluded, does not reach the C2h symmetry.
For complex 8, a set of five fluorine signals is observed at
Ϫ50 ЊC in accordance with a non-planar formulation, which is
also confirmed by X-ray crystallography. A similar rigid pattern
is found at room temperature, suggesting that the energy barrier
to the free rotation of C6F5 rings and/or to the inversion of the
central dimetallacycle is unusually high. It is noteworthy that
the highest frequency ortho-F resonance displays a somewhat
broad appearance. These 19F NMR patterns and the fact that
the hydroxyl protons have the appearance of a doublet (J = 15
Hz) could suggest the existence in solution of a H ؒ ؒ ؒ ortho-F
interaction between the OH and the C6F5 groups, stabilizing the
bridging system. In support of this, the reaction of complex 8
and PPh3 to give the mononuclear complex 12 (see Scheme 2)
requires the use of an excess of ligand (4 equivalents) for
completion.
δ 1.04 is consistent with the presence of the vinyl fragment
1
(Z)-CMe᎐CHMe. The ZZ stereoisomer is confirmed by a H
᎐
phase-sensitive NOESY spectrum at room temperature, which
shows cross positive peaks correlating the vinyl proton at δ 4.88
with both of the methyl signals. The data for the mixture of 2a,
2b and 2c are included as ESI, the most characteristic being the
presence of a multiplet at δ 4.87 due to vinyl protons in 2a and
2c, and two broad singlets at δ 4.41 and 4.02 due to the non-
equivalent protons of the terminal ᎐CH(a)H(b) unit of the
᎐
C(Et)᎐CH fragment in 2b and 2c.
᎐
2
Reactions with [cis-Pt(C6F5)2(THF)2]
In spite of the presence of a vinyl fragment in 2a or oxygen
atoms in 1, 3 or 4, which could act as donor centres, the
reactions of these complexes with [cis-Pt(C6F5)2(THF)2]2 in
CH2Cl2 take place with rearrangement of the ligands yielding
the symmetrical dimers [trans,trans-(PPh3)(C6F5)Pt(µ-1κCα:η2-
α
2
᎐
᎐
C᎐CR)(µ-2κC :η -C᎐CR)Pt(C F )(PPh )], stabilised by
a
᎐
᎐
6
5
3
double alkynyl bridging system, in high yields (71–90%)
(Scheme 2, i). Spectroscopic data of 5–8 [mass spectra, IR, 31P
1
NMR (Experimental); H, 13C and 19F NMR (Tables S1–S3 in
the ESI)] are in accordance with the proposed formulations
shown in Scheme 2. Complexes 5 and 7 crystallise with CH2Cl2
(5ؒCH2Cl2 and 7ؒ½CH2Cl2) as confirmed by the analytical data,
NMR spectroscopy (1H and 13C) and, in the case of complex 7,
even by X-ray crystallography (see below). For complexes 5, 7
Ϫ1
᎐
and 8 the ν(C᎐C) absorptions (in cm 1975 5, 1986 7, 1995 8)
᎐
᎐
and, particularly, the notable ∆ν(C᎐C) shift relative to the
᎐
corresponding monomers (in cmϪ1 139 5, 124 7, 127 8) are in
agreement with the presence of a σ/π double alkynyl bridging
system.9a–c,13,14 Complex 6 [ν(C᎐C) 2019 cmϪ1] exhibits a lower
The X-ray diffraction studies on 7 and 8 clearly establish the
presence of binuclear structures bridged by two σ/π alkynyl
ligands. Complex 7 (Fig. 1, Table 1) contains two stereocentres
[C(27) and C(27Ј)] on the molecule giving rise to two pairs of
enantiomers (RR/SS and RS/SR), that crystallise together in
the unit cell. The molecule is solved generating half of its atoms
by a C2 axis, thus leading to a disorder on the C(OMe)EtMe
groups. The structure displayed in Fig. 1 corresponds to the
idealised situation for one isomer (SS) and details of the X-ray
crystal structure analyses are also given in Table 2. A view of
the molecular geometry of 8 is shown in Fig. 2 and selected
᎐
᎐
shift (69 cmϪ1), suggesting a weaker η2-platinum acetylenic
interaction. The planar formulation for this complex is sug-
gested by 19F NMR, which displays, even at low temperature
(Ϫ50 ЊC in CDCl3), the typical sharp pattern of three signals in
2 : 1 : 2 ratio due to two equivalent C6F5 groups for which the
plane of coordination is a mirror plane. As expected, due to
the presence of two stereogenic centres, complexes 5 and 7 have
been obtained as non-separable mixtures of diastereomers in
a ca. 1 : 1 molar ratio, for which the non-planar structural
disposition is inferred mainly by 19F NMR spectroscopy and
2928
J. Chem. Soc., Dalton Trans., 2001, 2926–2936

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Scheme 2
᎐
Molecular structure of [trans-Pt{µ-C᎐CC(OH)Ph2}(C6F5)-
᎐
Fig.
2
(PPh3)]2ؒCH2Cl2 (8ؒCH2Cl2). Ellipsoids are drawn at the 50%
probability level. Hydrogen atoms and phenyl groups of the PPh3
ligands have been omitted for clarity.
separation in these compounds [3.359 7, 3.4066(1) Å 8] is con-
᎐
Fig. 1 Molecular structure of [trans-Pt{µ-C᎐CC(OMe)EtMe}(C6F5)-
᎐
siderably shorter than that found in the bis(phenylethynyl)
(PPh3)]2ؒ½CH2Cl2 (7ؒ½CH2Cl2). Ellipsoids are drawn at the 50%
probability level. Hydrogen atoms have been omitted for clarity.
᎐
planar dimer [3.653(1) Å]. The deviations of the Pt–C ᎐C –C
᎐
α
β
skeletons from linearity [at Cα 171.8(6) 7, 166.0(3) 8; at Cβ
᎐
bond distances and angles are given in Table 1. The most
remarkable features of both structures are: i) the bent
structural disposition of the central PtC4Pt dimetallacycle,
152.1(6) 7, 154.9(3)Њ 8] and the C᎐C distances [1.223(9) 7,
᎐
1.237(4) Å 8] are within the usual range found for related σ/π
alkynyl bridged compounds.
which contrasts with the planar structure previously found
The main purpose of the X-ray study on complex 8 was to
check for the presence of hydrogen bond interactions, in
14
for [trans-Pt(C᎐CPh)(C F )(PPh )] . Both planar23 and non-
᎐
᎐
6
5
3
2
planar9a,b,13,24 C4M2 cores have been found previously. The
dihedral angle formed by the corresponding best platinum
coordination planes (47.5 7; 49.26Њ 8) resembles values of
related complexes. ii) In complex 7 the platinum η2-linkages are
clearly symmetric [Pt–C(25Ј) 2.328(6) and Pt–C(26Ј) 2.317(7)
Å], while in complex 8 they are slightly asymmetric [Pt(1)–C(1Ј)
2.339(3) and Pt–C(2Ј) 2.289(3) Å]. This structural feature con-
particular with the ortho-fluorine atoms, aiming to understand
᎐
the unusual stability of this [µ-C᎐CC(OH)Ph ] bridging
᎐
2 2
system. Hydrogen bonds combine the most favourable aspects
of directionality and strength amongst intermolecular inter-
actions and, for this reason, are being widely employed in
supramolecular chemistry and crystal engineering.25,26 Our
interest was also attracted by recent studies27 on the partici-
pation of organic fluorine in hydrogen bonding (X–H ؒ ؒ ؒ F–C
where X = O, N, C), which indicate that fluorine, when
covalently bound to carbon, does not frequently form hydrogen
bonds with conventional hydrogen bond donors. Although this
trasts with the asymmetric η2 interactions previously found in
᎐
[trans-Pt(C᎐CPh)(C F )(PPh )] , with the platinum–C distance
᎐
6
5
3
2
β
being perceptibly shorter than the corresponding Pt–Cα
[2.261(6) vs. 2.362(6) Å] and, accordingly, iii) the Pt ؒ ؒ ؒ Pt
J. Chem. Soc., Dalton Trans., 2001, 2926–2936
2929

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Table 1 Selected bond lengths (Å) and angles (Њ) for complexes
a
7ؒ½CH2Cl2 and 8ؒCH2Cl2
᎐
[trans,trans-Pt{µ-C᎐CC(OMe)MeEt}(C6F5)(PPh3)]2ؒ½CH2Cl2
᎐
(7ؒ½CH2Cl2)
Pt–C(25)
Pt–C(26Ј)
C(26)–C(27)
Pt–C(1)
2.015(6)
2.317(7)
1.489(10) Pt–P
2.063(6) C(25)–C(26)
Pt–C(25Ј)
Pt–PtЈ
2.328(6)
3.359
2.241(2)
1.223(9)
C(25)–Pt–C(1)
C(1)–Pt–P
C(1)–Pt–C(26Ј)
C(25)–Pt–C(25Ј)
C(26)–C(25)–Pt
176.2(3)
C(25)–Pt–P
89.6(2)
108.0(2)
30.5(2)
94.4(2)
91.6(2)
85.4(2)
70.5(3)
171.8(6)
C(1)–Pt–C(25Ј)
C(26Ј)–Pt–C(25Ј)
C(25)–Pt–C(26Ј)
C(25)–C(26)–C(27) 152.1(6)
᎐
[trans,trans-Pt{µ-C᎐CC(OH)Ph2}(C6F5)(PPh3)]2ؒCH2Cl2 (8ؒCH2Cl2)
᎐
Pt(1)–C(1)
Pt(1)–C(1Ј)
C(2)–C(3)
Pt(1)–C(16)
2.015(3)
2.339(3)
1.500(4)
2.072(3)
Pt(1)–C(2Ј)
Pt(1)–Pt(1Ј)
Pt(1)–P(1)
C(1)–C(2)
2.289(3)
3.4066(1)
2.2578(7)
1.237(4)
Fig. 3 Perspective view along the c axis of ¼ of the unit cell (0
< x < 0.25, 0 < y < 1, 0 < z < 1), showing the pattern of O–H ؒ ؒ ؒ F–C
interactions in compound 8ؒCH2Cl2 [O(1)–H(1) 0.84(3) Å, H(1)–F(2Јa)
2.325(7) Å, H(1)–F(1Ј) 2.796(5) Å, O(1)–H(1)–F(2Јa) 158.81Њ, O(1)–
H(1)–F(1Ј) 85.84Њ]. Hydrogen atoms, all the phenyl groups and CH2Cl2
molecules have been omitted for clarity.
C(1)–Pt(1)–C(16)
C(16)–Pt(1)–P(1)
C(1)–Pt(1)–C(2Ј)
C(16)–Pt(1)–C(1Ј) 106.68(10)
C(2)–C(1)–Pt(1) 166.0(3)
a Symmetry transformation used to generate equivalent primed atoms is
Ϫx, y, Ϫz ϩ ½ in 7ؒ½CH2Cl2 and Ϫx ϩ 1, y, Ϫz ϩ ½ in 8ؒCH2Cl2.
175.12(11)
90.44(8)
91.88(10)
C(1)–Pt(1)–P(1)
C(1)–Pt(1)–C(1Ј)
C(1Ј)–Pt(1)–C(2Ј)
C(16)–Pt(1)–C(2Ј)
C(1)–C(2)–C(3)
93.91(8)
69.42(12)
30.98(9)
83.42(10)
154.9(3)
᎐
Pt(C᎐CR)(C F )(PPh )] (R = Ph or SiMe ) requiring 4.5 h (for
᎐
6
5
3
2
3
6) and 48 h (for 7), respectively to go to completion. For com-
plex 8, the reaction is so slow that it requires the use of an excess
of PPh3 ligand. In this case, the initial orange solution was
stirred with 4 equivalents of PPh3 until a colourless solution
was finally obtained (ca. 12 h). In an alternative synthetic pro-
cedure complex 10 could be prepared by controlled dehydration
of compound 9. Thus, the treatment of a solution of 9 in
CH2Cl2 with four drops of HBF4 (0.1 M in Et2O) at room
temperature for 5 min gives rise to an orange solution from
which the vinylacetylide derivative 10 is isolated in a 77% yield.
The terminal coordination of the alkynyl ligand in all com-
is supported by database analysis and theoretical calculations,27
some evidence of weak X–H ؒ ؒ ؒ F–C interactions, both in solu-
tion and the solid state, have been reported.27,28 In complex 8,
the hydroxyl hydrogen atom [H(1)] has been located, using the
Fourier difference maps, at a distance of 0.84(3) Å from the
oxygen atom. In spite of the presence of OH donors and O
acceptors, no hydrogen bond contacts of the type O–H ؒ ؒ ؒ O
have been detected and, contrary to our expectations, the
shortest separation between H(1) and a fluorine atom on a
pentafluorophenyl ring within the molecule [H(1)–ortho-F(1Ј)
2.796(5) Å] is quite long, excluding any intramolecular bonding
interaction.29 However, it is interesting to note that, in the solid,
the OH group acts as a donor towards a meta-fluorine atom of
a C6F5 group from the neighbouring molecule. The dimers are
thus linked by two hydrogen bonds [H(1) ؒ ؒ ؒ F(2Јa) 2.325(7) Å,
O(1)–H(1) ؒ ؒ ؒ F(2Јa) 158.81Њ] giving an extending chain along
the c axis. The hydrogen ؒ ؒ ؒ fluorine separation [2.325(7) Å] is
within the usual range for this type of contact.27–30 A perspec-
plexes 9–12 is confirmed by their IR spectra in which the
᎐
ν(C᎐C) is found shifted to higher wavenumbers (2131–2102
᎐
cmϪ1) in comparison with the C᎐C stretching frequency in
᎐
᎐
the corresponding dimers. Their 31P{1H} spectra exhibit the
expected singlet resonance (δ 19.7–20.1) with a 1J(PtP) coupling
constant (2710–2740 Hz) characteristic of mutually trans
phosphines.20 In the 13C NMR spectra, the Cα resonances
occur as a broad multiplet [δ Cα/J(PtCα) Hz 94.0 9; 106.0 10;
94.7/942 11; 99.9/948 12] probably due to unresolved coupling
to ortho-fluorine nuclei [4J(CαF)] whereas the Cβ resonances
appear, as in complexes 1–4, at higher frequencies [δ Cβ/J(PtCβ)
Hz 117.2/240 9; 114.4/285 10; 114.3/247 11; 115.5/250 12] as a
broad singlet.
tive view of the resulting pattern, showing that each binuclear
entity [trans,trans-(PPh )(C F )Pt{µ-C᎐CC(OH)Ph } Pt(C F )-
᎐
᎐
3
6
5
2
2
6
5
Reactions with [cis-Pt(C6F5)2(CO)(THF)]
(PPh3)] is involved in a total of four (O–H ؒ ؒ ؒ meta-F) inter-
actions is shown in Fig. 3. We tentatively suggest that these
interactions probably do not survive in solution, and this fact
allows the hydroxyl proton a stronger intramolecular inter-
action with the ortho-fluorine [O(1)–H(1) ؒ ؒ ؒ F(1Ј)] atom,
which could be responsible for the observed stability of the
bridging system. A similar proposal has been recently suggested
to explain the hydrolysis reaction of CF2 groups in perfluoro-
There has been growing interest in binuclear transition metal
complexes containing unsaturated hydrocarbon bridges linking
the metal fragments and without metal–metal bonds, due to
their unique chemical and physical properties.31 In this area,
although σ,σ alkynediyl compounds are well known,5a,b,32 bi-
1
2
᎐
nuclear complexes stabilised solely by a µ-η :η -C᎐CR bridging
᎐
group are rare, particularly those containing platinum.1a,b In
this context, we have recently shown that the solvento com-
plex [cis-Pt(C6F5)2(CO)(THF)] ≡ [{Pt}(THF)] containing only a
labile tetrahydrofuran solvent molecule is an excellent precursor
alkyl aqua coordinated complexes, which is extremely facile via
Ϫ
intramolecular O–H ؒ ؒ ؒ F–C bonding, if the counterion [BF4
,
B(ArF)4Ϫ] is unable to participate in hydrogen bonding.30b
to a diverse variety of this type of complex. Thus, whereas the
Reactivity of 5–8 towards PPh3
᎐
reaction between metallaalkynyl compounds ML C᎐CR of type
᎐
n
᎐
᎐
᎐
We have examined the reactivity of the dimers 5–8 towards
PPh3. As shown in Scheme 2, treatment of the bridged com-
cis or trans [Pt(C᎐CR) L ], [Pt(dppe)(C᎐CR) ] or [Au(C᎐CR)L]
᎐ ᎐
2 2 2
᎐
(R = Ph, But; L = PPh3, PEt3) and [{Pt}(THF)] takes place with
plexes 5–7 with PPh3 (2 equivalents) results in bridge splitting
stereo retention but with formal alkynylation of the “Pt(C6F5)2-
Ϫ
1
α
2
ϩ
᎐
᎐
to give the mononuclear complexes [trans-Pt(C F )(C᎐CR)-
(CO)” ≡ {Pt} fragment yielding [{Pt }(µ- κC :η -C᎐CR)M L ]
᎐
᎐
6
5
n
(PPh ) ] [R = C(OH)EtMe 9, (Z)-CMe᎐CHMe 10, C(OMe)-
zwitterionic species,15 the analogous reactions with [trans-
᎐
3
2
᎐
EtMe 11] as white solids. For 6 and 7 the reactions are slower
Pt(C᎐CSiMe ) L ] results in an unexpected rearrangement
᎐
3
2
2
than those previously observed for related dimers [trans-
chemistry, giving rise to a (µ-ethynediyl)(methylalkoxycarbene)-
2930
J. Chem. Soc., Dalton Trans., 2001, 2926–2936

View Article Online
16
᎐
diplatinum species of the type [{Pt}(C᎐C)Pt{C(Me)OR}L ].
resonances are seen, the complex pattern in the ortho-fluorine
᎐
2
Interestingly, the reaction of [{Pt}(THF)] with the hydride
region (2 : 2 : 4 13 or 1 : 1 : 2 : 4 14) is in accordance with the
᎐
alkynylcomplex[trans-Pt(H)(C᎐CPh)(PPh ) ]affordsaµ-phenyl-
presence of two diastereomers for which the coordination plane
᎐
3
2
Ϫ
᎐
ethenylidene diplatinum derivative [{Pt}(µ-C᎐CPhH)Pt(PPh ) ]
of the anionic fragment “cis-Pt (C F ) (CO)(µ-C᎐CR)” is not
᎐
᎐
3
2
6
5 2
containing a platinum–platinum bond.33 In this case, it was
a symmetry plane.
suggested that the initial zwitterionic species [{PtϪ}(µ-1κCα:η2-
C᎐CPh)Pt H(PPh ) ] probably evolves, via cis,cis isomerisation
Under different reaction conditions, low (Ϫ30 ЊC) or
room temperature, the analogous reaction between the enynyl
derivative 2a and [cis-Pt(C6F5)2(CO)(THF)] affords a mixture
of compounds containing the expected [cis,trans-{PtϪ}{µ-
ϩ
᎐
᎐
3
2
and cis H-1,2 addition, to yield the final µ-phenylethenylidene
complex.
α
2
ϩ
᎐
᎐
As one of our main objectives in the present work was to
understand the influence of functionalised alkynyl substituents
on the course of these reactions, we decided to explore the
reactivity of this electrophilic metal building block “cis-
Pt(C6F5)2(CO)” with the bis-alkynyl complexes 1–4 and the
mixed derivatives 9–12. In keeping with previous results,15 com-
plexes 1, 3 and 4 react with [cis-Pt(C6F5)2(CO)(THF)] in CH2Cl2
at room temperature, affording the zwitterionic derivatives
1κC :η -C᎐C-(Z)-CMe᎐CHMe}Pt {C᎐C-(Z)-CMe᎐CHMe}-
᎐ ᎐ ᎐
1
᎐
(PPh3)2] as the main component [δP 16.1, J(PtP) 2519 Hz, 19F
1
and H NMR data are collected in the Experimental section].
However, all attempts to separate this dimer from the mixture
were fruitless. Dehydration reactions of complex 13 were also
attempted using HBF4 or Me3OBF4, but these reactions usually
led to a similar mixture of products and, again, we were not
able to separate the expected pure dimer.
Ϫ
α
2
ϩ
᎐
᎐
[cis,trans-{Pt }(µ-1κC :η -C᎐CR)Pt (C᎐CR)(PPh ) ]
In contrast to this result, only the analogous reaction
᎐
᎐
3
2
᎐
[R = C(OH)EtMe 13, C(OMe)EtMe 14, C(OH)Ph2 15], which
are formed via the expected alkynylation of the carbonyl
platinum fragment “cis-Pt(C6F5)2(CO)” (Scheme 2, iii). It
is interesting to note that the zwitterionic nature of organo-
metallic complexes (zwitterionic metallates) has recently
become an influential factor in the design of cationic metal
catalysts, and may become a fundamental consideration in
the design of mixed valence (donor–acceptor) complexes for
applications in materials science (non-linear optics, molecular
electronics).34 The reactions are immediate and complexes are
isolated as yellow (13) or beige (14, 15) solids in moderate (55%
14) or high yields (86% 13, 81% 15). Spectroscopic data are in
agreement with the formulation shown in Scheme 2 (details are
given in the Experimental section and in Tables S1–S3 in the
ESI). It should be noted that again the NMR spectra of com-
plexes 13 and 14 reveal the presence of two diastereomers in ca.
1 : 1 ratio, in agreement with the presence of two chiral carbon
atoms (Cγ). This fact is also confirmed by a single-crystal X-ray
study on complex 13. However, due to the poor data quality,
the structure analysis is not of a high accuracy. Nevertheless,
the connectivity, shown in Scheme 2, can be established, with the
four expected diastereomers (two pairs of enantiomers) crystal-
between the mixed derivative [trans-Pt{C᎐C-(Z)-CMe᎐CH-
᎐
᎐
Me}(C6F5)(PPh3)2] 10 with [cis-Pt(C6F5)2(CO)(THF)] (Scheme
2, iv) gives a pure product. In this case, the presence of the
vinyl fragment causes a simple displacement of the tetrahydro-
furan molecule affording the adduct [trans,cis-(PPh3)2(C6F5)-
Pt{µ-1κCα:η2C3,4-C᎐C-(Z)-CMe᎐CHMe}Pt(C F ) (CO)] 16.
᎐
᎐
᎐
6
5 2
Complex 16 was isolated as a yellow solid in 61% yield. The IR
spectrum of 16 shows the characteristic ν(CO) (2117 cmϪ1
)
stretching frequency in a similar position to that seen in the
precursor [ν(CO) 2124 cmϪ1], in agreement with the small
changes in the electron density on the platinum centres during
the reaction. The coordination of the vinyl entity causes a small
Ϫ1
shift of the ν(C᎐C) (2083 cm in 16 vs. 2102 cmϪ1 in 10), and
᎐
᎐
is inferred from NMR spectroscopy. Thus, the vinyl proton
(᎐CHMe) is observed as a quartet by coupling to geminal
᎐
methyl protons [δ 1.38, d, J(HH) = 6 Hz] at lower frequencies
(δ 4.46) in relation to 10 (δ 4.86), and displays a platinum proton
coupling [2J(PtH) = 50 Hz] similar to those observed for other
µ-vinyl or η2-alkenyl platinum complexes.35 In the 13C NMR
spectrum the Cγ (δ 123.2) and Cδ (δ 95.52) vinyl resonances are
observed as singlets and also exhibit the expected 195Pt satellites.
The low field signal shows a platinum–carbon coupling (23 Hz)
similar to that seen in 2a and is, therefore, suggested to be
lising together in the unit cell, which causes a disorder located
3
᎐
on the C(OH)EtMe group of the terminal C᎐C–R ligand. An
a J(PtC) coupling. The low frequency resonance displays a
᎐
idealised view of the molecular geometry corresponding to the
SS isomer is given in Fig. S4 in the ESI.
greater coupling [1J(PtC) = 60 Hz] confirming that this frag-
ment is involved in η2 coordination. The chemical shift of
the phosphorus resonance, as well as the J(PtP) coupling con-
stant, in 16 are very similar to those observed in 10 [δ/1J(PtP)
Hz 19.6/2676 16 vs. 19.7/2710 Hz 10] confirming again that a
small structural rearrangement has taken place. The 19F NMR
spectrum confirms the presence of three inequivalent C6F5 rings
(see Table S3 in the ESI for details). Furthermore, as is usual for
other compounds15,16,33,35a in which the “cis-Pt(C6F5)2” frag-
ment is stabilised by different ligands trans to the C6F5 rings,
which induces different energy barriers to the rotation of C6F5
groups, one set of signals displays a marked dependence upon
temperature (see Table S3 in the ESI). It is worth mentioning
that the vinyl fragment on the precursor complex 10 is prochiral
and complex 16 should therefore be obtained as a mixture of
two enantiomers.
The most remarkable spectroscopic feature appears on their
IR spectra, which show the strong ν(CO) absorption (2083–
2096 cmϪ1), along with the two expected and weaker additional
Ϫ1
᎐
ν(C᎐C) bands corresponding to terminal (2133 cm 13, 2130
᎐
cmϪ1 14, not observed for 15) and bridging (1972 cmϪ1 13, 1988
cmϪ1 14, 2005 cmϪ1 15) alkynyl ligands. In agreement with pre-
vious observations,15,16 the simultaneous increase and decrease
of electron density at the platinum centres caused by alkynyl
᎐
ligand migration is reflected in the ν(CO) and terminal ν(C᎐C)
᎐
bands, which are perceptibly shifted to lower and higher
wavenumbers, respectively, in relation to the precursors {ν(CO)
Ϫ1
2124 cmϪ1 for [cis-Pt(C F ) (CO)(THF)]; ν(C᎐C) 2114 cm 1,
᎐
᎐
6
5 2
2110 cmϪ1 3}. In the 31P NMR spectra the magnitude of 1J(PtP)
is still typical of mutually trans phosphine groups, but its value
(≈2510 13, 2563 14, 2547 Hz 15) is slightly smaller when com-
pared to the corresponding precursors in accordance with the
formal positive charge developed on this platinum fragment.20a
The acetylenic carbon resonances are assigned unequivocally
It was previously shown that the reactions of monoalkynyl
t
᎐
platinum complexes [trans-PtX(C᎐CR)(PPh ) ] (R = Ph, Bu
᎐
3
2
or SiMe3; X = Cl or C6F5)15 with [cis-Pt(C6F5)2(CO)(THF)]
yielded complicated mixtures of products, probably due to the
presence of electron withdrawing groups (Cl or C6F5), which
enhance the acidity of the platinum centres and reduce its
alkynylation power. Similarly, the reactions between the alkoxy
(9, 12) and methoxy (11) derivatives with [cis-Pt(C6F5)2-
(CO)(THF)] evolved affording very complex mixtures, which
were not investigated further. However, it should be noted that
complex 16 is clearly detected in the final reaction mixtures
starting from 9 and 11 (in this case 16 is isolated in 37% yield),
only in complex 13. Modest but perceptible upfield shifts are
᎐
observed for the bridged C ᎐C carbon resonances in relation
᎐
α
β
to the precursor 1 {δ Cα/[1J(PtCα)]{2J(PCα)} Hz 94.0(br)/[950]
, 86.5/{16} C᎐Cterm; Cβ/2J(PtCβ) 119.1, 119.0/300
᎐
C᎐C
᎐
᎐
᎐
bridge
C᎐C , 94.8/234 C᎐Cbridge vs. δ Cα/[1J(PtCα)]{2J(PCα)} Hz 98.7/
᎐
᎐
᎐
᎐
term
[955]{15}; Cβ/[2J(PtCβ)]{3J(PCβ)} 115.2/[245]{2}]. The 19F
NMR spectrum of 15 displays the expected two sets of
C6F5 signals (2 : 1 : 2). For 13 and 14, although two para-F
J. Chem. Soc., Dalton Trans., 2001, 2926–2936
2931

View Article Online
thus suggesting that spontaneous dehydration processes also
play a decisive role in the course of these reactions.
(0.05 cm3, 0.36 mmol) at room temperature. The resulting red
solution was filtered through Celites and evaporated to dryness.
Addition of ≈5 cm3 of Et2O caused the precipitation of 2a
(0.07 g, 36%).
Concluding remarks
᎐
In conclusion, the presence of functionalised (vinyl, OH or
OMe) alkynyl substituents on bis-alkynyl platinum precursors
seems to have little influence on the course of the reactions with
[cis-Pt(C6F5)2(THF)2] (redistribution of ligands with final for-
mation of symmetrical dimers) or [cis-Pt(C6F5)2(CO)(THF)]
(formal alkynylation and final stereo retention around Pt
Other reactions of [trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 in
᎐
2
3 2
᎐
toluene. A white suspension of [trans-Pt{C᎐CC(OH)EtMe} -
᎐
2
(PPh3)2] 1 (0.20 g, 0.22 mmol) in 20 cm3 of toluene was refluxed
for 1 h. The resulting solution was evaporated to ca. 5 cm3,
recovering 0.14 g (71%) of unaltered starting material 1. A
mixture of 0.45 g (0.49 mmol) of [trans-Pt{C᎐CC(OH)-
᎐
᎐
centres). In contrast to this in the analogous reactions of mixed
EtMe}2(PPh3)2] 1 and 0.1 g (0.98 mmol) of Al2O3 was refluxed
for 1 h and the resulting yellow solution was evaporated to
dryness. Addition of Et2O (ca. 5 cm3) afforded 0.32 g of a
᎐
[trans-Pt(C F )(C᎐CR)(PPh ) ] (9–12) with [cis-Pt(C F ) (CO)-
᎐
6
5
3
2
6
5 2
(THF)] only the presence of a good coordination entity [(Z)-
CMe᎐CHMe] on the alkynyl ligand allows the formation of a
yellow solid which was identified by NMR (1H, 13C, and 31P) as
᎐
᎐
stable binuclear complex (16).
a mixture of 2a, [trans-Pt(C᎐CCEt᎐CH ) (PPh ) ] 2b and
᎐
᎐
2
2
3 2
᎐
᎐
[trans-Pt{C᎐C-(Z)-CMe=CHMe}(C᎐CCEt᎐CH )(PPh ) ] 2c
᎐
᎐
᎐
2
3 2
(74%). Further attempts to separate this mixture by standard
recrystallization methods were unsuccessful (Found: C, 65.89;
H, 5.14%. C48H44P2Pt requires Mϩ 877; C, 65.67; H, 5.05%);
δP(CDCl3) 18.6 [s, J(PPt) 2689], 18.7 [s, J(PPt) 2674 Hz]; m/z
(% intensity) 877 (Mϩ, 9), 719 ([Pt(PPh3)2]ϩ, 68).
Experimental
General
All manipulations were carried out under a nitrogen atmos-
phere, except for the synthesis of complexes 1–4 and 9–12.
Solvents (hexane, alkanes) were dried by standard procedures
᎐
[trans-Pt{C᎐CC(OMe)EtMe} (PPh ) ] 3. 0.10 g (0.11 mmol)
᎐
2
3 2
᎐
and distilled under dry N before use. NEt H, HC᎐CC(OH)-
᎐
2
2
᎐
of [trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 were refluxed for
᎐
2
3 2
᎐
EtMe and HC᎐CC(OH)Ph were used as received. NMR
36 h in 15 cm3 of MeOH. Evaporation of the resulting yellow
solution to ca. 5 cm3 caused the precipitation of complex 3 as
a white solid (0.07 g, 68%) (Found: C, 63.37; H, 5.23%.
᎐
2
spectra were recorded on a Bruker ARX-300 spectrometer
and the 1H phase-sensitive NOESY spectrum was recorded
following the literature methods.36 Chemical shifts are reported
in ppm relative to external standards (SiMe4, CFCl3 and 85%
H3PO4) and all coupling constants are given in Hz. IR spectra
were obtained on Perkin-Elmer 883 or Perkin-Elmer FT-IR
Spectrum 1000 spectrometers using Nujol mulls between poly-
ethylene sheets. Elemental analyses were carried out with a
Perkin-Elmer 2400 CHNS/O or Carlo Erba EA1110 CHNS-O
microanalyzers. Mass spectra were recorded on a VG Autospec
double-focusing mass spectrometer operating in the FABϩ
mode, except for complex 12 (HP-5989B mass spectrometer
using the ESϩ technique). [cis-Pt(C6F5)2(THF)2]37a and [cis-
Pt(C6F5)2(CO)(THF)]37b were prepared by published methods.
1H, 19F and 13C{1H} NMR data for all the complexes reported
in this paper have been provided as ESI.
C50H52O2P2Pt requires C, 63.75; H, 5.56%); νmax/cmϪ1 (C᎐C)
᎐
᎐
2110m; δP(CDCl3) 19.2 [s, J(PPt) 2699 Hz]; m/z (% intensity)
941 (Mϩ, 5), 912 (Mϩ Ϫ CH3OH ϩ 3H, 23). Complex 3 was
also obtained, as a white solid, by addition of two drops of a
0.1 M solution of HBF4 in Et2O (0.10 cm3, 0.01 mmol) to a
suspension of 1 (0.3 g, 0.33 mmol) in 25 cm3 of MeOH, and
refluxing the mixture for 30 min. Evaporation of the resulting
colourless solution to ca. 5 cm3 caused the precipitation of 3
(0.3 g, 97%).
᎐
[trans-Pt{C᎐CC(OH)Ph } (PPh ) ] 4. Complex
4
was
᎐
2
2
3 2
obtained following the same method described for complex 1,
but starting with 0.5 g (0.63 mmol) of [cis-PtCl2(PPh3)2], 0.02 g
(0.1 mmol) of CuI and 0.29 g (1.47 mmol) of HC᎐C(OH)-
᎐
᎐
Ph2 (0.54 g, 75%), (Found: C, 69.76; H, 4.78%. C66H52O2P2Pt
Preparations
requires C, 69.89; H, 4.62%); νmax/cmϪ1 (OH), 3558s, (C᎐C)
᎐
᎐
᎐
2122s; δP(CDCl3) 19.4 [s, J(PPt) 2654 Hz]; m/z (% intensity)
[trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1. The synthesis of this
᎐
2
3 2
1117 (Mϩ Ϫ OH, 27).
complex has been carried out as described previously by
Furlani et al.18 with slight modifications. 0.02 g (0.1 mmol) of
3
᎐
᎐
[trans-Pt(ꢀ-C᎐CR)(C F )(PPh )]
[R ؍ C(OH)EtMe
5,
CuI and 2 cm of HC᎐CC(OH)EtMe (17.6 mmol) were added
᎐
6
5
3
2
᎐
(Z )-CMe᎐CHMe 6, C(OMe)EtMe 7, C(OH)Ph 8]. A colour-
to a white suspension of [cis-PtCl2(PPh3)2] (1.00 g, 1.26 mmol)
in 15 cm3 of NEt2H, and the mixture was stirred at reflux for 20
min. The resulting white suspension was evaporated to dryness
and the solid residue treated with ≈5 cm3 of EtOH to yield 1
as a white solid (1.04 g, 90%) (Found: C, 63.02; H, 5.56%.
᎐
2
᎐
less solution of [trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 (0.4 g,
᎐
2
3 2
0.44 mmol) in 20 cm3 of CH2Cl2 was treated with 0.295 g
(0.44 mmol) of [cis-Pt(C6F5)2(THF)2] at room temperature.
The mixture was stirred for 20 min and the resulting orange
solution was evaporated to dryness. Treatment of the residue
with ca. 5 cm3 of EtOH caused the precipitation of 5 as a white
solid. Complexes 6–8 were prepared similarly as white (7)
or beige (6, 8) solids, except for complex 8. For complex 8 the
initial stirring of the mixture was for only 2 min and the
C48H48O2P2Pt requires C, 63.08; H, 5.29%); νmax/cmϪ1 (OH)
᎐
3601m, (C᎐C) 2114m; δ (CDCl ) 19.1 [s, J(PPt) 2685 Hz]; m/z
᎐
P
3
(% intensity) 913 (Mϩ, 5), 896 (Mϩ Ϫ H2O ϩ H, 23).
᎐
[trans-Pt{C᎐C-(Z )-CMe᎐CHMe} (PPh ) ] 2a. A colourless
᎐
᎐
2
3 2
᎐
solution of [trans-Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 (0.20 g, 0.22
final residue was treated with hexane: 0.15 g (0.17 mmol) of
᎐
2
3 2
mmol) in 5 cm3 of CHCl3 was treated, at room temperature,
with two drops of a 0.1 M solution of HBF4 in Et2O (0.10 cm3,
0.01 mmol). The mixture was stirred for 5 min, evaporated
to dryness and treated with 2 cm3 of EtOH to afford 2a as a
yellow solid (0.14 g, 73%) (Found: C, 65.59; H, 4.46%. C48-
[trans-Pt{C᎐C-(Z)-CMe᎐CHMe} (PPh ) ] 2a and 0.115
g
᎐
᎐
᎐
2
3 2
(0.17 mmol) of [cis-Pt(C6F5)2(THF)2] for 6; 0.18 g (0.19 mmol)
᎐
of [trans-Pt{C᎐CC(OMe)EtMe} (PPh ) ] 3 and 0.13 g (0.19
᎐
2
3 2
mmol) of [cis-Pt(C6F5)2(THF)2] for 7; 0.15 g (0.13 mmol) of
᎐
[trans-Pt{C᎐CC(OH)Ph } (PPh ) ] 4 and 0.09 g (0.13 mmol)
᎐
2
2
3 2
H44P2Pt requires C, 65.67; H, 5.05%); νmax/cmϪ1 (C᎐C) 2088m;
of [cis-Pt(C6F5)2(THF)2] for 8. Complexes 5 and 7 crystallise
with one or half a molecule of CH2Cl2, respectively, as observed
by 1H and 13C{1H} NMR spectroscopy in CDCl3.
᎐
᎐
δP(CDCl3) 18.6 [s, J(PPt) 2689 Hz]; m/z (% intensity) 878
(Mϩ ϩ H, 25).
Complex 2a was also obtained, as a yellow solid, by treat-
ment of 15 cm3 of a white toluene suspension of 1 (0.19 g,
0.21 mmol) with one drop of a 54% solution of HBF4 in Et2O
Complex 5. Yield 0.67 g, 90%; (Found: C, 48.30; H, 3.33%.
C60F10H48O2P2Pt2ؒCH2Cl2 requires C, 47.95; H, 3.30%. CH2Cl2
observed in the 1H and 13C{1H} NMR spectra in CDCl3);
2932
J. Chem. Soc., Dalton Trans., 2001, 2926–2936

View Article Online
νmax/cmϪ1 (OH) 3579m, (C᎐C) 1975m, (C F )
792s;
[cis,trans-(OC)(C F ) Pt{ꢀ-C᎐CC(OH)EtMe}Pt{C᎐CC-
᎐
᎐
᎐
᎐
᎐
᎐
6
5
X-sensitive
6
5 2
δP(CDCl3) 12.9 [s, J(PPt) 3895 Hz]; m/z (% intensity) 1345
(OH)EtMe}(PPh3)2] 13. A colourless solution of [trans-
3
(Mϩ Ϫ C2R, 9).
Pt{C᎐CC(OH)EtMe} (PPh ) ] 1 (0.17 g, 0.19 mmol) in 20 cm
᎐
᎐
2
3 2
Complex 6. Yield 0.17 g, 71%; (Found: C, 50.82; H, 3.67%.
of CH2Cl2 was treated with 0.12 g (0.19 mmol) of [cis-
Pt(C6F5)2(CO)(THF)] at room temperature. The mixture was
stirred for 10 min and the resulting yellow solution evaporated
to a small volume (ca. 1 cm3). Treatment of the residue with
ca. 5 cm3 of EtOH caused the precipitation of 13 as a pale-
yellow solid (0.24 g, 86%) (Found: C, 49.45; H, 3.20%.
C61F10H48O3P2Pt2 requires C, 49.80; H, 3.29%); νmax/cmϪ1 (OH)
C60F10H44P2Pt2 requires C, 51.22; H, 3.15%); νmax/cmϪ1 (C᎐C)
᎐
᎐
2019m, (C6F5)X-sensitive 793s; δP(CDCl3) 13.4 [s, J(PPt) 4047 Hz];
m/z (% intensity) 1405 (Mϩ Ϫ H, 2).
Complex 7. Yield 0.22 g, 75%; (Found: C, 50.01; H, 3.60%.
C62F10H52O2P2Pt2ؒ½CH2Cl2 requires C, 49.63; H, 3.53%.
CH2Cl2 observed in the 1H and 13C{1H} NMR spectra in
CDCl3); νmax/cmϪ1 (C᎐C) 1986m, (C F )X-sensitive 788s; δP(CDCl3)
3565m,br, (CO) 2093s, (C᎐C) 2133w, 1972w, (C F )X-sensitive 799s,
᎐
᎐
᎐
᎐
6
5
6
5
13.0 [s, J(PPt) 3954]; at Ϫ50 ЊC 13.5, 13.4 [s, J(PPt) ≈ 3900 Hz];
m/z (% intensity) 1470 (Mϩ, 2); 1439 (Mϩ Ϫ MeOH ϩ H, 3).
Complex 8. Yield 0.15 g, 71%; (Found: C, 55.88; H, 2.79%.
785m; δP(CDCl3) 17.31 (s), 17.22 (s), 17.19 (s) (2 : 1 : 1)
[J(PPt) ≈ 2510 Hz]; m/z (% intensity) 1081 ([Pt2(PPh3)2(C6F5)]ϩ,
6); 897 ([Pt(C2R)2(PPh3)2]ϩ Ϫ OH ϩ H, 35); 816 ([Pt(C2R)-
(PPh3)2]ϩ, 16); 719 ([Pt(PPh3)2]ϩ, 100).
C78F10H52O2P2Pt2 requires C, 56.32; H, 3.15%); νmax/cmϪ1 (OH)
᎐
3577s,br, (C᎐C) 1995m,br, (C F )
789s; δP(CDCl3) 10.6
᎐
6
5
X-sensitive
[s, J(PPt) 4040 Hz]; m/z (% intensity) 1644 (Mϩ Ϫ OH Ϫ H, 2).
[cis,trans-(OC)(C F ) Pt(ꢀ-C᎐CR)Pt(C᎐CR)(PPh ) ] [R ؍
᎐
᎐
᎐
᎐
6
5
2
3 2
C(OMe)EtMe 14, C(OH)Ph2 15]. A pale-yellow solution of
᎐
[trans-Pt{C᎐CC(OMe)EtMe} (PPh ) ] 3 (0.15 g, 0.16 mmol)
᎐
2
3 2
᎐
[trans-Pt{C᎐CC(OH)EtMe}(C F )(PPh ) ] 9. An orange
᎐
6
5
3 2
in 20 cm3 of CH2Cl2 was treated with 0.10 g (0.16 mmol) of
[cis-Pt(C6F5)2(CO)(THF)] and the mixture stirred for 1 min.
Evaporation of the resulting orange solution to dryness and
addition of 5 cm3 of MeOH to the solid residue afforded 14
as a beige solid. Complex 15 was obtained, as a beige solid,
᎐
solution of [trans-Pt{µ-C᎐CC(OH)EtMe}(C F )(PPh )]
5
᎐
6
5
3
2
(0.20 g, 0.13 mmol) in 15 cm3 of CH2Cl2 was treated with 0.07 g
(0.28 mmol) of PPh3 to immediately give a colourless solution.
The mixture was stirred for 1 h at room temperature, evapor-
ated to dryness and the residue was treated with ca. 5 cm3
of hexane to give 9 as a white solid (0.21 g, 83%) (Found: C,
in a similar way starting from 0.20 g (0.18 mmol) of [trans-
᎐
Pt{C᎐CC(OH)Ph } (PPh ) ] 4 and 0.11 g (0.18 mmol) of [cis-
᎐
2
2
3 2
58.42; H, 3.66%. C48F5H39OP2Pt requires C, 58.59; H, 3.99%);
Pt(C6F5)2(CO)(THF)], with 5 min stirring and 5 cm3 of hexane
for the treatment of the final solid residue.
νmax/cmϪ1 (OH), 3596m, (C᎐C) 2131m, (C F )
790m;
᎐
᎐
6
5
X-sensitive
δP(CDCl3) 20.1 [s, J(PPt) 2729 Hz]; m/z (% intensity) 983
(Mϩ, 3), 965 (Mϩ Ϫ H2O, 17).
Complex 14. Yield 0.13 g, 55%; (Found: C, 50.37; H, 3.18%.
C63F10H52O3P2Pt2 requires C, 50.47; H, 3.50%); νmax/cmϪ1 (CO)
᎐
2083s, (C᎐C) 2130w, 1988w, (C6F5)X-sensitive 799s, 790s;
᎐
᎐
[trans-Pt{C᎐C-(Z )-CMe᎐CHMe}(C F )(PPh ) ] 10. The
᎐
᎐
6
5
3 2
δP(CDCl3) 18.0 [s, J(PPt) 2563 Hz]; m/z (% intensity)
912 ([Pt(C2R)2(PPh3)2]ϩ Ϫ OMe ϩ 2H, 40); 831 ([Pt(C2R)-
(PPh3)2]ϩ ϩ H, 9); 719 ([Pt(PPh3)2]ϩ, 70).
addition, at room temperature, of four drops of a 0.1 M solu-
tion of HBF4 in Et2O (0.2 cm3, 0.02 mmol) to a colourless
᎐
solution of [trans-Pt{C᎐CC(OH)EtMe}(C F )(PPh )] 9 (0.13
᎐
6
5
3
2
Complex 15. Yield 0.25 g, 81%; (Found: C, 55.89; H, 2.79%.
g, 0.13 mmol) in 5 cm3 of CHCl3 immediately gave an orange
solution that was stirred for 5 min. Evaporation of the mixture
to dryness and treatment of the residue with hexane (ca. 5 cm3)
yielded 10 as a white solid (0.10 g, 77%) (Found: C, 59.42; H,
C79F10H52O3P2Pt2 requires C, 56.10; H, 3.10%); νmax/cmϪ1 (OH)
᎐
3562s,br, (CO) 2096s, (C᎐C) 2005m, (C F )
800s,br;
᎐
6
5
X-sensitive
δP(CDCl3) 17.3 [s, J(PPt) 2547 Hz]; m/z (% intensity) 1117
([Pt(C2R)2(PPh3)2]ϩ Ϫ OH, 18); 926 ([Pt(C2R)(PPh3)2]ϩ, 16);
719 ([Pt(PPh3)2]ϩ, 69).
3.27%. C48F5H37P2Pt requires C, 59.69; H, 3.86%); νmax/cmϪ1
᎐
(C᎐C) 2102m, (C F )
796m; δP(CDCl3) 19.7 [s, J(PPt)
᎐
6
5
X-sensitive
2710 Hz]; m/z 967 (Mϩ ϩ 2H, 18). Complex 10 was also
᎐
Reaction of [trans-Pt{C᎐C-(Z )-CMe᎐CHMe} (PPh ) ] 2a
with [cis-Pt(C6F5)2(CO)(THF)]. 0.11 g (0.17 mmol) of [cis-
Pt(C6F5)2(CO)(THF)] were added at room temperature to a
᎐
᎐
2
3 2
obtained by addition, at room temperature, of 0.07 g (0.28
᎐
mmol) of PPh over an orange solution of [trans-Pt{µ-C᎐C-
᎐
3
(Z)-CMe᎐CHMe}(C F )(PPh )] 6 (0.2 g, 0.14 mmol) in 10 cm3
᎐
6
5
3
2
᎐
solution of [trans-Pt{C᎐C-(Z)-CMe᎐CHMe} (PPh ) ] 2a (0.15
᎐
᎐
2
3 2
g, 0.17 mmol) in 20 cm3 of CH2Cl2. The mixture was stirred for
5 minutes and the resulting red solution evaporated to ca. 1 cm3.
Addition of ca. 5 cm3 of hexane afforded a pale-orange solid
(0.13 g), which was identified by NMR (1H, 19F and 31P) as a
mixture of complexes containing [cis,trans-(OC)(C6F5)2Pt-
of CH2Cl2. The mixture was stirred for 4.5 h to give a colourless
solution which was evaporated to dryness. Addition of Et2O
(ca. 3 cm3) to the solid residue yielded 10 as a white solid
(0.12 g, 44%).
᎐
᎐
᎐
[trans-Pt(C᎐CR)(C F )(PPh ) ] {R ؍ C(OMe)EtMe 11, C-
{µ-C᎐C-(Z)-CMe᎐CHMe}Pt{C᎐C-(Z)-CMe᎐CHMe}(PPh )]
᎐ ᎐ ᎐
3 2
᎐
᎐
6
5
3
2
᎐
(OH)Ph2 12}. A pale-yellow solution of [trans-Pt{µ-C᎐CC-
as the main species. Further attempts to separate this product
pure from the mixture by standard recrystallization methods
were unsuccessful and the complex was tentatively charac-
terised by multinuclear NMR (1H, 19F and 31P) δH(CDCl3) 5.05
(q, –CMe᎐CHMe), 4.84 (q, –CMe᎐CHMe); δ (CDCl ) Ϫ117.3
[dd, J(Pt–ortho-F) = 382, 2 ortho-F], Ϫ118.2 [dd, J(Pt–ortho-
F) = 382, 2 ortho-F], Ϫ161.3 (t, 1 para-F), Ϫ161.9 (t, 1 para-F),
Ϫ164.3 (m, 2 meta-F), Ϫ165.0 (m, 2 meta-F); δP(CDCl3) 16.1
[s, J(PPt) 2519 Hz].
᎐
(OMe)EtMe}(C6F5)(PPh3)]2 7 (0.15 g, 0.10 mmol) in 15 cm3 of
CH2Cl2 was treated with 0.05 g (0.20 mmol) of PPh3 and the
mixture was stirred at room temperature for 2 days. Evapor-
ation of the resulting solution to dryness and addition of 5 cm3
of MeOH to the residue afforded 11 as a white solid. Complex
᎐
᎐
F
3
3
3
12 was obtained (white solid) in a similar way starting from
0.13 g (0.08 mmol) of [trans-Pt{µ-C᎐CC(OH)Ph }(C F )-
(PPh3)]2 8 and 0.08 g (0.32 mmol) of PPh3, with 12 h of stirring
and 5 cm3 of cold absolute EtOH for the treatment of the final
solid residue.
᎐
᎐
2
6
5
᎐
[trans,cis-(PPh ) (C F )Pt{ꢀ-C᎐C-(Z )-CMe᎐CHMe}Pt(C -
᎐
᎐
3
2
6
5
6
Complex 11. Yield 0.17 g, 85%; (Found: C, 58.67; H, 3.68%.
F5)2(CO)] 16. 0.06 g (0.10 mmol) of [cis-Pt(C6F5)2(CO)(THF)]
were added at room temperature to an orange solution of
C49F5H41OP2Pt requires C, 58.98; H, 4.14%); νmax/cmϪ1 (C᎐C)
᎐
᎐
᎐
2124m, (C6F5)X-sensitive 790m; δP(CDCl3) 20.0 [s, J(PPt) 2740 Hz];
[trans-Pt{C᎐C-(Z)-CMe᎐CHMe}(C F )(PPh ) ] 10 (0.10 g,
᎐
᎐
6
5
3 2
m/z (% intensity) 997 (Mϩ, 3).
0.10 mmol) in 20 cm3 of CH2Cl2. The mixture was stirred for
5 minutes and the resulting deep orange solution evaporated to
dryness. Addition of ca. 5 cm3 of a Et2O–hexane mixture (1 : 5)
afforded 16 as a yellow solid (0.09 g, 61%), (Found: C, 47.84; H,
2.48%. C61F15H37OP2Pt2 requires C, 48.10; H, 2.45%); νmax/cmϪ1
Complex 12. Yield 0.14 g, 81%; (Found: C, 62.30; H, 4.02%.
C57F5H41OP2Pt requires C, 62.58; H, 3.78%); νmax/cmϪ1 (OH)
᎐
3551s, (C᎐C) 2122m, (C F )
790m; δP(CDCl3) 19.7 [s,
᎐
6
5
X-sensitive
J(PPt) 2710 Hz]; m/z (% intensity) 1077 (Mϩ Ϫ OH ϩ H, 40).
J. Chem. Soc., Dalton Trans., 2001, 2926–2936
2933

View Article Online
Table 2 Crystal data and structure refinement parameters for 7ؒ½CH2Cl2 and 8ؒCH2Cl2
7ؒ½CH2Cl2
8ؒCH2Cl2
Empirical formula
Molecular mass
Temperature/K
Wavelength/Å
Crystal system
Space group
C62H58F10O2P2Pt2ؒ½CH2Cl2
1519.60
173(1)
0.71073
Monoclinic
C2/c
27.468(6)
C78H52F10O2P2Pt2ؒCH2Cl2
1748.24
173(2)
0.71073
Monoclinic
C2/c
24.0550(4)
a/Å
b/Å
c/Å
10.055(2)
23.037(5)
13.5280(2)
20.3500(3)
β/Њ
115.56(3)
5740(2)
91.303(1)
6620.5(2)
Volume/Å3
Z
4
4
Absorption coefficient/mmϪ1
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [I > 2σ(I )]
R indices (all data)a
5.047
5178
5037 [R(int) = 0.053]
5029/6/375
4.429
7849
7849 [R(int) = 0.0000]
7849/0/442
1.355
R1 = 0.0273, wR2 = 0.0594
R1 = 0.0363, wR2 = 0.0620
1.094
R1 = 0.0326, wR2 = 0.0763
R1 = 0.0543, wR2 = 0.0988
4
a wR2 = [Σw(Fo2 Ϫ Fc2)2/ΣwFo ]0.5; R1 = Σ||Fo| Ϫ |Fc||/Σ|Fo|.
᎐
(CO) 2117vs, (C᎐C) 2083s, (C F )
796s,br; δP(CDCl3)
solutions of the complexes at room temperature, were mounted
on the end of a quartz fiber and held in place with fluorinated
oil. X-Ray intensity data were collected, at 173 K, using
Siemens STOE/AED2 four circle and Nonius Kappa CCD
diffractometers for 7ؒ½CH2Cl2 and 8, respectively. In both
cases no decay of the crystal was observed over the period of
data collection. For complex 7ؒ½CH2Cl2 an absorption correc-
tion was applied based on 504 azimuthal scan data and the
structure was solved by Patterson and Fourier methods and
refined by full-matrix least squares on F 2 using the SHELXL-
93 program.38 For complex 8, images were processed using the
DENZO and SCALEPACK suite of programs.39 The structure
was solved by Patterson and Fourier methods using the DIR-
DIF92 program40 and refined by full-matrix least squares on
F 2 using the SHELXL-97 program.41 In both cases, all non-
hydrogen atoms were assigned anisotropic displacement
parameters and, for 8ؒCH2Cl2, refined without positional con-
straints. The methyl and methoxy fragments of the acetylide
ligands in 7ؒ½CH2Cl2 are disordered over two sets of positions
with populations 0.55/0.45 in such a way that their positions are
interchanged. The interatomic distances of the –C(OMe)EtMe
fragment were constrained. The hydrogen atoms were con-
strained to idealised geometries and assigned anisotropic dis-
placement parameters 1.2 times the Uiso value of their attached
carbon atoms (1.5 times for the methyl hydrogen atoms),
except for H(1) in 8ؒCH2Cl2, which was located from Fourier
difference maps and refined isotropically without any restraints.
CCDC reference numbers 165089 and 165090.
᎐
6
5
X-sensitive
19.6 [s, J(PPt) 2676 Hz]; m/z (% intensity) 965 ([Pt(C2R)-
(C6F5)(PPh3)2]ϩ, 5); 886 ([Pt(C6F5)(PPh3)2]ϩ, 7); 718 ([Pt-
(PPh3)2]ϩ Ϫ H, 25).
᎐
Reaction of [trans-Pt{C᎐CC(OH)EtMe}(C F )(PPh ) ] 9 with
[cis-Pt(C6F5)2(CO)(THF)]. A colourless solution of [trans-
᎐
6
5
3 2
᎐
Pt{C᎐CC(OH)EtMe}(C F )(PPh ) ] 9 (0.15 g, 0.15 mmol) in
᎐
6
5
3 2
20 cm3 of CH2Cl2 was treated with an equimolar amount of
[cis-Pt(C6F5)2(CO)(THF)] (0.09 g, 0.15 mmol) and the mixture
was stirred for 30 min. NMR spectra of the resulting yellow
solution showed a complex mixture of products also containing
complex 16. No pure product could be isolated from this
mixture by standard work-up.
᎐
Reaction of [trans-Pt{C᎐CC(OMe)EtMe}(C F )(PPh ) ] 11
with [cis-Pt(C6F5)2(CO)(THF)]. 0.10 g (0.16 mmol) of [cis-
Pt(C6F5)2(CO)(THF)] were added to a yellow solution of [trans-
᎐
6
5
3 2
᎐
Pt{C᎐CC(OMe)EtMe}(C F )(PPh ) ] 11 (0.16 g, 0.16 mmol)
᎐
6
5
3 2
in 20 cm3 of CH2Cl2. The mixture was stirred for 30 min and
the resulting orange solution evaporated to ca. 1 cm3. Addition
of ca. 5 cm3 of a Et2O–hexane mixture (1 : 5) afforded 16 as a
yellow solid (0.09 g, 37%).
᎐
Reaction of [trans-Pt{C᎐CC(OH)Ph }(C F )(PPh ) ] 12 with
[cis-Pt(C6F5)2(CO)(THF)].
{C᎐CC(OH)Ph }(C F )(PPh ) ] 12 (0.09 g, 0.08 mmol) in
᎐
2
6
5
3 2
A
suspension of [trans-Pt-
᎐
᎐
2
6
5
3 2
20 cm3 of CH2Cl2 was treated with 0.11 g (0.17 mmol) of
[cis-Pt(C6F5)2(CO)(THF)] to immediately give a dark green
solution. Its 31P NMR spectrum showed that it was a mixture
containing mainly a product with a singlet at δ 18.3. The solu-
tion was evaporated to dryness and the residue thus obtained
was treated with a mixture of Et2O–hexane (1 : 5) to yield the
starting substrate 12 as a brown solid in a 18% yield (16 mg).
Evaporation of the filtrate and subsequent treatment of the
solid residue with hexane and PriOH rendered two new frac-
tions (12 and 7 mg), which were identified by 31P NMR as
mixtures of the mononuclear complex 12 and the product with
the signal at δ 18.3, which we were not able to isolate and
identify.
See http://www.rsc.org/suppdata/dt/b1/b104783n/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
Financial support was provided by the Dirección General de
Investigación Científica y Técnica, (Spain, Projects PB98-1595-
C02-01,02) and the University of La Rioja (Project API-00/
B17). We also thank Dr E. Urriolabeitia of the University of
1
Zaragoza (Spain) for the recording of the H phase-sensitive
NOESY spectrum.
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