Linear ditopic acetylide gold or mercury complexes: Synthesis and photophysic studiesX-ray crystal structure of PPh4[Au(C≡CC5H4N)2]

Article abstract of DOI:10.1016/S0022-328X(03)00442-X

The AlkH alkyne compounds 4-ethynylpyridine (1), 4-ethynylbenzonitrile (2) and (4-ethynylphenyl)(4-pyridyl)acetylene (3) react with [PPh₄][Au(acac)₂] to yield three new linear ditopic bis-alkyne gold(I) compounds [PPh₄][Au(Alk)₂] (for AlkH=1, 1a; for AlkH=2, 2a and for AlkH=3, 3a). The reaction of 1a with an excess of methyl iodide results in the methylation of both N-pyridine atoms. Analogous mercury(II) [Hg(Alk)₂] compounds are obtained by the reaction of the lithium derivatives of 1, 3 and (4-bromophenyl)(4-pyridyl)acetylene (4) with HgCl₂. All these compounds have been characterised by IR and ¹H-NMR spectroscopies and mass spectrometry. The X-ray crystal structure of 1a shows that the gold atom is surrounded by two alkyne ligands in a linear fashion. The reported compounds have been tested as building blocks for the synthesis of molecular polygons by self-assembly. Emission of the compounds was studied and the measured quantum yields were in the range 0.01< Φ <0.04. Room-temperature emission of compounds 1aH and 1a′ exhibits a large Stokes shift, and is assigned to the lower triplet state. Decay times were measured at room temperature in CH₂Cl₂ for 1aH (1.5 μs) and in ethanol at 77 K (149 and 500 μs for compounds 1aH and 1a′, respectively). Room-temperature emission of compounds 3a and 3aH arises from the lower singlet state and phosphorescence is only observed at 77 K. Theoretical calculations on the nature and energy of singlet and triplet states corroborate the assignments.

Full text of DOI:10.1016/S0022-328X(03)00442-X

Journal of Organometallic Chemistry 678 (2003) 82ꢂ89
/
www.elsevier.com/locate/jorganchem
Linear ditopic acetylide gold or mercury complexes: synthesis and
photophysic studies
X-ray crystal structure of PPh4[Au(Cꢀ
/
CC5H4N)2]
Montserrat Ferrer a,*, Laura Rodr´ıguez a, Oriol Rossell a, Fernando Pina b,
Joao C. Lima b, Merce` Font Bardia c, Xavier Solans c
˜
a Departament de Qu´ımica Inorga`nica, Universitat de Barcelona, Mart´ı i Franque`s 1-11, 08028 Barcelona, Spain
b Departamento de Qu´ımica, Centro de Qu´ımica Fina e Biotecnologia, Universidade Nova de Lisboa, Quinta de Torre, 2825 Monte da Caparica,
Portugal
c Departament de Cristal.lografia, Mineralogia i Dipo`sits Minerals, Universitat de Barcelona, Mart´ı i Franque`s s/n, 08028 Barcelona, Spain
Received 9 April 2003; received in revised form 9 May 2003; accepted 9 May 2003
Abstract
The AlkH alkyne compounds 4-ethynylpyridine (1), 4-ethynylbenzonitrile (2) and (4-ethynylphenyl)(4-pyridyl)acetylene (3) react
with [PPh4][Au(acac)2] to yield three new linear ditopic bis-alkyne gold(I) compounds [PPh4][Au(Alk)2] (for AlkHꢀ
/1, 1a; for
AlkHꢀ2, 2a and for AlkHꢀ3, 3a). The reaction of 1a with an excess of methyl iodide results in the methylation of both N-pyridine
/
/
atoms. Analogous mercury(II) [Hg(Alk)2] compounds are obtained by the reaction of the lithium derivatives of 1, 3 and (4-
bromophenyl)(4-pyridyl)acetylene (4) with HgCl2. All these compounds have been characterised by IR and 1H-NMR spectroscopies
and mass spectrometry. The X-ray crystal structure of 1a shows that the gold atom is surrounded by two alkyne ligands in a linear
fashion. The reported compounds have been tested as building blocks for the synthesis of molecular polygons by self-assembly.
Emission of the compounds was studied and the measured quantum yields were in the range 0.01B
/
F B0.04. Room-temperature
/
emission of compounds 1aH and 1a? exhibits a large Stokes shift, and is assigned to the lower triplet state. Decay times were
measured at room temperature in CH2Cl2 for 1aH (1.5 ms) and in ethanol at 77 K (149 and 500 ms for compounds 1aH and 1a?,
respectively). Room-temperature emission of compounds 3a and 3aH arises from the lower singlet state and phosphorescence is only
observed at 77 K. Theoretical calculations on the nature and energy of singlet and triplet states corroborate the assignments.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Photoluminescence; Supramolecular; Acetylide; Gold; Mercury
1. Introduction
geometry. Moreover, for these species there is evidence
for ready association into dimers, oligomers and poly-
mers as a result of attractive intermolecular AuÁ Á ÁAu
Recently, the chemistry of metal acetylides has
become the focus of enormous attention with the
emerging interest in their potential applications in the
field of materials science [1]. In particular, two linear
coordinate gold(I) complexes of the type [AuX2]ꢁ (Xꢀ
anionic ligand, such as a substituted alkynyl group) have
potential as building blocks for supramolecular struc-
tures because of their relatively simple molecular
interactions [2]. The strengths for the goldꢂgold inter-
/
actions are comparable with those found in hydrogen
bonds [3] and they seem to be responsible for the
intriguing optical properties of some of these species
[4]. For example, it has been reported that formation of
/
AuÁ Á ÁAu and arylꢂ
/
aryl interactions in the solid state can
lead to the observation of a red-shift in the emission
band compared with that in the solution phase [5].
Here we report the synthesis and characterisation of
the first linear gold ditopic donor complexes. These
species were built of substituted acetylide fragments and
* Corresponding author. Tel.: ꢃ
77-25.
E-mail address: montse.ferrer@qi.ub.es (M. Ferrer).
/
34-93-402-12-74; fax: ꢃ34-93-490-
/
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00442-X

M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
83
were thought to react with ditopic acceptor units such as
cis-(dppp)M(OTf)2 (MꢀPd, Pt) to render molecular
/
polygons. This study has been extended to some
analogous mercury compounds. In addition, the photo-
physical properties of the new species are also discussed.
2. Results and discussion
Scheme 2.
We aimed to construct supramolecular assemblies
resulting from the reaction between metal-containing
ditopic donor units with the well-known ditopic accep-
lene proton in 1, 2 and 3, and the aromatic protons were
unambiguously assigned. The ESMS spectrum of 2a
permitted us to detect the molecular peak at m/z 448.9,
while those corresponding to 1a (m/z 401.1) and 3a (m/z
601.7) were obtained from FABMS experiments. The
geometry of 1a has been confirmed by an X-ray crystal
structure determination.
In an attempt to obtain a gold(III) derivative starting
from 1a, we made it react with an excess of methyl
iodide; however, the isolated compound was the salt 1a?
(Scheme 3) resulting from methylation of both N-
pyridine atoms. The spectroscopic data are close to
those found in 1a and the methyl protons appear at 4.18
ppm in DMSO-d6.
tor fragments cis-(Lꢁ
/
L)M(OTf)2 (Lꢁ
/
Lꢀbidentate li-
/
gand; MꢀPd, Pt) [6]. We focused our attention on gold
/
and mercury complexes, given their preference for
number of coordination two, which is required for
building up molecular polygons such as square or
triangular frameworks [7]. We were also interested in
using acetylide ligands since they could act as base
receptor sites for binding, via the p-tweezer effect, a
variety of Lewis acids [8]. On the other hand, the
presence of unsaturated bonds in the supramolecular
species would permit researchers to carry out photo-
physics studies on them.
Although a number of acetylide gold complexes have
been reported, the vast majority is supported by
arylphosphine ancillary ligands [9]. The latter molecules
were not suitable for our purposes since they are not
able to coordinate simultaneously two metal centres. As
a result, we decided to use the ligands 1, 2, 3 and 4, as
shown in Scheme 1. These ligands exhibit one coordina-
tion site for the metal atom (gold or mercury) while
another (arylnitrile or pyridine unit), at 1808, is free for a
further coordination.
Compounds 1a, 2a and 3a, which can be formally
considered as metal-containing edges, were easily pre-
pared by making [PPh4][Au(acac)2] react with the
corresponding terminal alkyne ligand in dichloro-
methane at room temperature (Scheme 2). Yields were
about 70%. Evidence for the proposed structures is seen
We have extended this type of compounds to mercury
and, thus, the species 1b, 3b and 4b were prepared from
1, 3 and 4, respectively (Scheme 4). The synthetic
procedure consisted of two steps: the first involved the
lithiation with nBuLi of 1, 3 or 4 in THF at ꢁ
78 8C, and
/
the second, the subsequent reaction with HgCl2. Yields
were reasonably good. The characterisation was carried
1
out by IR and H-NMR spectroscopies and FABMS.
Notably, in 3a and 3b, two n(Cꢀ
/
C) stretches appear,
one corresponding to the alkynyl group directly at-
tached to metal (2094 cmꢁ1 for 3a and 2145 cmꢁ1 for
3b, as reported for the majority of mercury-bisalkynyl
complexes) and another corresponding to the alkynyl
unit unbonded to the metal at 2214 cmꢁ1. This fact
suggests that partial electron density from the metal
atoms is given up to p* molecular orbitals of the alkynyl
groups, this effect being more pronounced for the gold
complex because of the smaller positive charge on the
in the IR spectra, which showed n(Cꢀ
/
C) bands about
20 cmꢁ1
2100 cmꢁ1, shifted to higher frequencies (10ꢂ
/
)
N)
than that of the starting organic ligand. The n(Cꢀ
/
metal atom. The FABMS revealed the Mꢃ
Hꢃ ion
/
1
stretch for 2a appears at 2229 cmꢁ1. H-NMR spectro-
scopy showed the disappearance of the terminal acety-
Scheme 1.
Scheme 3.

84
M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
Table 1
˚
Selected interatomic distances (A) and bond angles (8) of 1a
Auꢁ
Auꢁ
C(1)ꢁ
C(8)ꢁ
C(2)ꢁ
C(9)ꢁ
/
C(1)
1.980(8)
1.983(8)
1.206(10)
1.213(10)
1.420(10)
1.420(10)
/C(8)
/
C(2)
C(9)
C(3)
C(10)
/
/
/
C(1)ꢁ
C(2)ꢁ
C(9)ꢁ
C(8)ꢁ
C(1)ꢁ
/
Auꢁ
C(1)ꢁ
C(8)ꢁ
C(9)ꢁ
C(2)ꢁ
/
C(8)
176.2(2)
177.0(5)
173.2(6)
176.1(8)
177.2(7)
/
/Au
/
/Au
/
/C(10)
Scheme 4.
/
/C(3)
peaks at m/z 405.8, 606.2 and 556.9 for 1b, 3b and 4b,
respectively.
square or triangular entities. Although a great number
of ‘‘organic’’ edges have been employed, only a small
number of metal-containing edges are known [11]. The
In the crystals of 1a, [Au(Cꢀ
/
CC5H4N)2]ꢁ anions and
PPh4ꢃ cations are present. The structure of the gold
compound is shown in Fig. 1; selected bond and angle
parameters are listed in Table 1. As expected, the
synthesis of 1ꢂ
them as gold- or mercury-linkers towards the ditopic
acceptor units (diphosphine)M(OTf)2 (MꢀPd, Pt). In
/3a and 1b, 3b and 4b allowed us to test
/
geometry about the gold(I) centre is linear with C(1)ꢁ
AuꢁC(8) angle of 176.2(2)8 and the angles C(3)ꢁC(2)ꢁ
C(1) and C(8)ꢁC(9)ꢁC(10)ꢀ177.2(7)8 and 176.1(8)8,
respectively, close to the ideal value of 1808 for a rigid-
rod molecule. The goldꢁcarbon distances, AuꢁC(1)
C(8) (1.983(8) A), as well as the
/
most cases, only intractable insoluble materials were
obtained that did not allowed the growing of single
crystals suitable for a structure determination. On the
other hand, when no precipitate was obtained, 31P- and
1H-NMR spectra of the reaction solutions showed very
complex patterns that could not be assigned. Changes in
the reaction conditions, involving variations on the
solution concentration (work at high dilution), tempera-
ture and solvent (common organic solvents, DMSO,
nitromethane, etc.) were performed. However, in no
case we were able to modify the nature of the resulting
products. These results contrast with those obtained by
employing platinum or palladium corners with a wide
variety of ‘‘organic’’ edges [7], where square or trian-
gular entities are isolated in reasonable yields and
structurally characterised. It is currently unclear why
the presence of gold or mercury atoms in the backbone
of the edges prevents the formation of the molecular
polygons.
/
/
/
/
/
/
/
/
˚
˚
(1.980(8) A) and Auꢁ
/
˚
C(2) (1.206(10) A) and
triple bond distances, C(1)ꢁ
/
˚
C(9) (1.213(10) A), are similar to those in related
C(8)ꢁ
/
acetylide complexes [5a,10]. In contrast to most Au(I)
compounds, where there exist short AuÁ Á ÁAu intermo-
lecular contacts, no such short interactions are observed
˚
5.46 A) as the negative charge on it
in 1a (AuÁ Á ÁAuꢀ
/
probably prevents their close approach.
2.1. Attempts to obtain molecular polygons
It is well-known that the stoichiometric combination
of 908 corners with linear linking units can lead to
2.2. Photoluminescence studies
The absorption and the luminescence of compounds
1a, 1a? and 3a were carried out in dichloromethane at
room temperature. In the case of compound 1a, the
emission only appears in acidic medium (formation of
compound 1aH takes place upon addition of trifluoro-
acetic acid), while in compound 3a the emission changes
upon acidification, with an increase of the emission
quantum yield and a red-shift in the emission band. In
the case of compound 2a, metal ligand dissociation
takes place in acidic media, and thus the observed
emission is due to the free 2 and protonated ligand. For
compounds 1a and 3a, the stability of their protonated
Fig. 1. ORTEP drawing of the molecular structure and numbering
scheme of 1a.
1
forms 1aH and 3aH was checked by H-NMR.

M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
85
Fig. 2. Absorption and emission spectra of compounds 1aH (A), 1a? (B), 3aH (C) and 3a (D).
The absorption and emission of compound 1aH are
reported in Fig. 2A. The absorption spectrum shows a
band with shape and intensity similar to the free ligand
1, and its very high molar absorption coefficient points
performed in the case of the gold complexes, since the
semi-empirical parameters for the metal atom are not
available. Fortunately this is not a problem in the
particular case of the compounds under study, since
absorption spectra of the free and complexed forms are
identical and new transitions arising from metal com-
plexation were not observed.
to an allowed pꢂ
were reported for other compounds containing the Auꢁ
CꢀCꢁPh moiety [12].
/
p* transition. Similar observations
/
/
/
A common feature of compounds 1aH and 1a? (see
Fig. 2) is a large Stokes shift, suggesting that the
emission is not from the same state populated by direct
light absorption. Other authors have proposed a triplet
as the emissive state for similar gold(I) complexes [13].
In order to understand the origin of the observed
transitions in both complexed and uncomplexed forms,
state diagrams for the free ligands 1, 1H, 1CH3, 3 and
3H were obtained using ZINDO/S semi-empirical pro-
gram (Fig. 3). The same calculations could not be
According to the state diagrams, both protonated and
unprotonated forms of ligand 1 exhibit forbidden low-
lying singlet excited states, as is predicted for the case of
the ligand 1CH3. In the case of ligand 1, the low-lying
singlet (S1) is np* in nature, while in 1H and 1CH3, S1 is
p
xyp*. The pxyp* state arises from the transition of one
electron from a p molecular orbital localised in the triple
bond that is perpendicular to the conjugated p system to
an antibonding orbital of the p conjugated system. It is,
thus, a forbidden transition. These predictions are

86
M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
Fig. 3. State diagrams for compounds 1, 1H, 1CH3, 3 and 3H.
compatible with the experimental observation that the
free ligand 1 does not emit in either protonated or
unprotonated form.
Concerning the analogous to 1a but containing
mercury instead of gold (compound 1b), no emission
was detected in neutral or acidic media.
Upon metal complexation, 1aH and 1a? show a
strongly red-shifted emission, which arises from the
low-lying triplet state T1, pp* in nature, populated
through the enhanced intersystem crossing due to heavy
atom effect. Compound 1a does not emit, and the
reason for that behaviour is not fully understood.
The absorption and emission of compound 1a? exhibit
an identical pattern to 1aH, as could be predicted by the
very close state diagrams of the ligands of both
compounds. In 1a?, both bands are slightly red-shifted
(Fig. 2B) due to the methyl substituent as found in other
similar compounds [14]. In rigid media at low tempera-
ture (ethanol at 77 K), the triplet of compound 1a? has a
longer lifetime (500 ms) than the triplet of 1aH in the
same conditions (149 ms).
The phosphorescence quantum yield of 1aH is Fꢀ
/
0.01. The decay time measured by laser flash photolysis
at room temperature in dichloromethane/trifluoroacetic
acid is 1.5 ms and in low-temperature rigid media
(ethanol at 77 K) is 149 ms, confirming that this emission
is of triplet origin.
Room-temperature solid-state luminescence spec-
trum, i.e., luminescence of the powder, was collected
for compound 1a? and is shown in Fig. 4, together with

M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
87
(3H; Fꢀ0.08). This is a result of the increase in the
/
intersystem crossing due to the heavy atom effect. In this
case, the increase of intersystem crossing is not accom-
panied by the appearance of room-temperature phos-
phorescence. The reason for that is probably the fact
that the triplet is so low in energy that coupling with the
ground state leads to a very efficient non-radiative
deactivation pathway of the triplet. In rigid media, at
low temperature (ethanol at 77 K), the non-radiative
constant becomes significantly less important and phos-
phorescence is clearly observed (decay timeꢀ670 ms).
/
Fig. 4. Solution (dashed line) and solid (solid line) emission spectra of
compound 1a?.
3. Experimental
the emission spectrum collected in solution. The emis-
sion of the powder is strongly red-shifted and presents a
shape that is completely different from what is observed
in solution, suggesting a strong interaction between the
All manipulations were performed under prepurified
N2 using standard Schlenk techniques. All solvents were
distilled from appropriate drying agents. Infrared spec-
tra were recorded on an FT-IR 520 Nicolet spectro-
monomers and extended pꢂp interactions.
/
photometer. 31P{1H}-NMR (d (85% H3PO4)ꢀ
0.0 ppm)
/
The state diagram for ligand 3, presents a low-lying
pp* singlet state in both protonated and unprotonated
forms. This is in good agreement with the observation of
fluorescence emission for both forms, being the emission
of the protonated form (450 nm) red-shifted with respect
to the unprotonated (328 nm) and presenting a higher
fluorescence quantum yield. Complexation induces
small shifts in the emission but does not induce the
appearance of a new phosphorescence band at room
temperature such as the observed with the previous
compounds. The absorption and emission spectra of
compound 3aH are presented in Fig. 2C. The shoulder
observed in the absorption spectrum of compound 3aH
could be due to the lower energy singlet (ca. 400 nm),
predicted by the state diagram, whose low energy can be
explained by increasing conjugation in the p system of
this compound. The luminescence is broader and blue-
shifted in comparison with compounds 1aH and 1a?.
The Stokes shift is now much smaller and its singlet
assignment is straightforward. Time-correlated single
photon counting was used to measure the fluorescence
decay of compound 3aH. The decays collected at several
emission wavelengths are always best-fitted with a sum
of two exponentials whose origin is still unclear. Despite
the attribution of other authors of similar bi-exponential
behaviour to the presence of monomers and excimers,
we have no evidence for excimer formation in this case
[15]. The average decay time measured is 2.2 ns.
1
and H-NMR spectra were obtained on a Bruker DXR
250 and Varian 200 spectrometers. Elemental analyses
of C, H and N were carried out at the Institut de Bio-
Orga`nica in Barcelona. FABMS and electrospray mass
spectra were recorded on a Fisons VG Quattro spectro-
meter. Absorption spectra were recorded in a Perkinꢂ
/
Elmer Lambda 6 spectrophotometer, and fluorescence
emission on a SPEX F111 Fluorolog spectrofluorimeter.
Total luminescence quantum yields were measured
relatively to quinine sulphate in 1 N H2SO4, Fꢀ0.54.
/
Luminescence decays were obtained with an applied
photophysics laser flash photolysis equipment pumped
by an Nd:YAG laser (Spectra Physics) with excitation at
355 nm [17] and a SPEX Fluorolog F2121, with
excitation at 355 nm. The emission mode was used to
obtain the luminescence decays. Compounds 4-ethynyl-
pyridine [18], 4-ethynylbenzonitrile [19], (4-bromophe-
nyl)(4-pyridyl)acetylene
[20],
(4-ethynylphenyl)(4-
pyridyl)acetylene [20] and [PPh4][Au(acac)2] [21] were
prepared as described previously.
Energy of the states were obtained performing single
point calculations with ZINDO/S-CI (99 singly excited
configurations) on geometries optimised with PM3. Both
semi-empirical programs used belong to the package
HyperchemTM, release 6.01 for Windows, Copyright#
2000 Hypercube, Inc.
Despite the fact that fluorescence is rarely observed in
the case of transition metal complexes, it is clearly
observed for compounds 3a and 3aH. The radiative rate
constant of the low-lying (strongly allowed) pp* state
competes in magnitude with the intersystem crossing
rate constant, even after complexation with the metal
[16]. However, complexation does affect the fluores-
cence quantum yield, i.e., the complexed form (3aH;
3.1. Synthesis of [PPh4][Au(Cꢀ
/
CC5H4N)2] (1a)
Solid 4-ethynylpyridine (1) (0.17 g, 1.64 mmol) was
added to a CH2Cl2 (40 ml) solution of [PPh4][Au(acac)2]
(0.3 g, 0.41 mmol) at room temperature. After 30 min of
stirring, the reaction mixture was filtered through Celite,
concentrated to 5 ml under vacuum and diethylether
was added (20 ml). During all the manipulations, the
solution was protected from the light in order to avoid
Fꢀ0.02) has a lower quantum yield than the free ligand
/

88
M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ89
/
decomposition. A pale pink solid was obtained in 70%
yield. IR (KBr, cmꢁ1), n(CꢀC): 2106. 1H-NMR (298 K,
acetone-d6, d ppm): 7.11 (d, JHꢁH 5.9 Hz, 4H, Hb-pyr),
5.9 Hz, 4H,
3.5. Syntheses of [Hg(Cꢀ
/
CC6H4Cꢀ
/
CC5H4N)2] (3b)
/
and [Hg(C6H4CꢀCC5H4N)2] (4b)
/
ꢀ
/
7.56ꢂ
/
7.92 (m, 20H, PPh4ꢃ), 8.33 (d, JHꢁH
ꢀ
/
Details of synthesis of 1b also apply to 3b and 4b.
3b: IR (KBr, cmꢁ1) n(Cꢀ
C): 2214 (NC5H4C ꢀC),
2145 (C ꢀ
CHg). 1H-NMR (298 K, CDCl3, d ppm): 7.37
(d, JHꢁH 5.7 Hz, 4H, Hb-pyr), 7.49 (s, br, 8H, C6H4),
8.61 (d, JHꢁH 5.7 Hz, 4H, Ha-pyr), FABMS [Mꢃ
Hꢃ];
Ha-pyr). FABMS [Mꢁ]; m/z: Calc.: 401.0; Found: 401.1.
Anal. Calc.: C, 61.59; H, 3.80; N, 3.80. Found: C, 61.61;
H, 3.84; N, 3.82%.
/
/
/
ꢀ
/
ꢀ
/
/
m/z Calc.: 605.6; Found: 606.2. Anal. Calc.: C, 59.54; H,
2.65; N, 4.63. Found: C, 59.57; H, 2.69; N, 4.67%.
3.2. Syntheses of [PPh4][Au(Cꢀ
/
CC6H4CN)2] (2a)
1
C): 2214. H-NMR (298 K,
4b: IR (KBr, cmꢁ1) n(Cꢀ
DMSO-d6, d ppm): 7.40 (s, br, 8H, C6H4), 7.52 (s, 4H,
/
and [PPh4][Au(CꢀCC6H4CꢀCC5H4N)2] (3a)
/
/
Hꢃ]; m/z
Details of synthesis of 1a also apply to 2a and 3a.
2a: IR (KBr, cmꢁ1), n(Cꢀ
N): 2229, n(CꢀC): 2106.
1H-NMR (298 K, CDCl3, d ppm): 7.22 (m, 4H, Hm),
Hb-pyr), 8.48 (s, 4H, Ha-pyr). FABMS [Mꢃ
/
/
/
Calc.: 557.5; Found: 556.9. Anal. Calc.: C, 56.05; H,
2.87; N, 5.03. Found: C, 56.07; H, 2.90; N, 5.06%.
7.34ꢂ
7.45 (m, 20H, PPh4ꢃ), 7.63 (m, 4H, Ho). ESMS
/
[Mꢁ]; m/z: Calc.: 448.9; Found: 448.9. Anal. Calc.: C,
63.93; H, 3.55; N, 3.52. Found: C, 63.97; H, 3.60; N,
3.57%.
3.6. X-ray structure determination of 1a
A prismatic crystal (0.1ꢄ
/
0.1ꢄ
0.2 mm3) was selected
and mounted on a MAR345 diffractometer with an
image plate detector. Unit cell parameters were deter-
/
3a: IR (KBr, cmꢁ1), n(Cꢀ
/
C): 2214 (NC5H4C ꢀ
/
C),
1
CAu). H-NMR (298 K, acetone-d6, d ppm):
2094 (C ꢀ
/
7.27 (m, 4H, Hm, AA?XX? spin system), 7.38 (m, 4H,
Ho, AA?XX? spin system), 7.44 (dd, 4H, Hb-pyr, AA?XX?
mined from automatic centring of 8588 reflections (38B
u B318) and refined by least-squares method. Intensities
were collected with graphite monochromatised MoꢂKa
radiation. 11 197 reflections were measured in the range
1.7085u 528.828. 6435 of which were non-equivalent
by symmetry (Rint (on I)ꢀ0.023). 5373 reflections were
assumed as observed applying the condition I ꢀ2s(I).
/
/
spin system), 7.84ꢂ
8.04 (m, 20H, PPh4ꢃ), 8.58 (dd, 4H,
/
/
Ha-pyr, AA?XX? spin system). FABMS [Mꢁ]; m/z Calc.:
601.0; Found: 601.7. Anal. Calc.: C, 68.91; H, 3.82; N,
2.98. Found: C, 68.95; H, 3.88; N, 2.99%.
/
/
/
/
Lorentz polarisation and absorption corrections were
made. Numerical details have been collected in Table 2.
The structure was solved by direct methods, using
SHELXS computer program [22] and refined by the full-
matrix least-squares method with the SHELX93 computer
program [23] using 6435 reflections (very negative
3.3. Synthesis of [Au(CꢀCC5H4NCH3)2]I (1a?)
/
CH3I (0.12 ml, 1.9 mmol) was added dropwise to an
acetone (15 ml) solution of 1a (0.14 g, 0.19 mmol) at
room temperature. After 45 min of stirring, a yellow
solid was obtained in 65% yield. IR (KBr, cmꢁ1), n(Cꢀ
/
1
intensities were not assumed). The function minimised
was Sw½½Fo½2ꢁ
C): 2109. H-NMR (298 K, DMSO-d6, d ppm): 4.18 (s,
6H, CH3), 7.79 (d, JHꢁH 6.5 Hz, 4H, Hb-pyr), 8.68 (d,
JHꢁH
6.5 Hz, 4H, Ha-pyr). FABMS [Mꢃ]; m/z Calc.:
2 2
/
½Fc½ ½ , where wꢀ
/
[s2(I)ꢃ(0.0607P)2
/
ꢀ
/
ꢃ
/
2.4230P]ꢁ1, and Pꢀ
/
(½Fo½2ꢃ2½Fc½2)/3, f, f? and f??
/
ꢀ
/
were taken from International Tables of X-ray Crystal-
lography [24]. 22H atoms were located from a difference
synthesis and refined with an overall isotropic tempera-
ture factor. 6H atoms were computed and refined, using
a riding model, with an isotropic temperature factor
equal to 1.2 times the equivalent temperature factor of
the atom which is linked.
431.0; Found: 431.6. Anal. Calc.: C, 86.04; H, 6.09; N,
5.02. Found: C, 86.08; H, 6.12; N, 5.08%.
3.4. Synthesis of [Hg(Cꢀ
/
CC5H4N)2] (1b)
To a precooled (ꢁ78 8C) solution of 4-ethynylpyr-
/
idine (1) (0.11 g, 1.11 mmol) in THF (20 ml) was added
dropwise nBuLi (0.10 ml, 1.11 mmol). The solution
turned pale yellow immediately. After 30 min of stirring,
solid HgCl2 (0.10 g, 0.37 mmol) was added. The mixture
was stirred for 1 h at room temperature and then
concentrated to 5 ml. A white solid was obtained after
the addition of ethanol (20 ml) in 62% yield. IR (KBr,
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 200097 for compound 1a.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
cmꢁ1), n(Cꢀ
ppm): 7.33 (d, JHꢁH
JHꢁH 11.9 Hz, 4H, Ha-pyr). FABMS [Mꢃ
/
C): 2150. 1H-NMR (298 K, CDCl3, d
11.9 Hz, 4H, Hb-pyr), 8.58 (d,
Hꢃ]; m/z
ꢀ
/
ꢀ
/
/
Cambridge CB2 1EZ, UK (Fax: ꢃ44-1223-336033; e-
/
Calc.: 405.6; Found: 405.8. Anal. Calc.: C, 41.52; H,
1.98; N, 6.92. Found: C, 41.55; H, 2.01; N, 6.97%.
mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.
ac.uk).

M. Ferrer et al. / Journal of Organometallic Chemistry 678 (2003) 82ꢂ
/89
89
[3] (a) B.C. Tzeng, A. Schier, H. Schmidbaur, Inorg. Chem. 38 (1999)
3978;
Table 2
Crystal data and details of the structure determination of 1a
(b) C. Hollatz, A. Schier, H. Schmidbaur, J. Am. Chem. Soc. 119
(1997) 8115.
Empirical formula
Formula weight
Temperature (K)
C38H28AuN2P
740.56
293(2)
[4] C. King, J.C. Wang, M.N.I. Kham, J.P. Fackler, Jr., Inorg.
Chem. 28 (1989) 2145.
˚
Wavelength (A)
[5] (a) M.J. Irwin, J.J. Vittal, R.J. Puddephatt, Organometallics 16
(1997) 3541;
0.71069
triclinic
¯
P1
Crystal system
Space group
Unit cell dimensions
(b) V.W.W. Yam, K.K.W. Lo, Chem. Soc. Rev. 28 (1999) 323;
(c) W.J. Hunks, M.A. MacDonals, M.C. Jennings, R.J. Pudde-
phatt, Organometallics 19 (2000) 5063.
/
˚
a (A)
10.8070(10)
12.7260(10)
13.8840(10)
106.260(10)
107.717 (10)
109.210 (10)
1556.6(2)
2
˚
[6] P.J. Stang, D.H. Cao, J. Am. Chem. Soc. 116 (1994) 4981.
[7] (a) P.J. Stang, Chem. Eur. J. 4 (1998) 19;
(b) M. Fujita, Chem. Soc. Rev. 27 (1998) 417.
[8] (a) J. Manna, C.J. Kuehl, J.A. Whiteford, P.J. Stang, D.C.
Muddiman, S.A. Hofstadler, R.D. Smith, J. Am. Chem. Soc. 119
(1997) 11611;
b (A)
˚
c (A)
a (8)
b (8)
g (8)
3
˚
V (A )
(b) J.A. Whiteford, P.J. Stang, S.D. Huang, Inorg. Chem. 37
(1998) 5595.
Z
Dcalc (mg mꢁ3
)
1.580
4.806
728
Absorption coefficient (mmꢁ1
F(0 0 0)
)
[9] A. Grohmann, H. Schmidbaur, in: E.W. Abel, F.G.A. Stone, G.
Wilkinson (Eds.), Comprehensive Organometallic Chemistry, vol.
Crystal size (mm3)
0.1ꢄ
/
0.1ꢄ
28.82
h 514, ꢁ
1851 517
/
0.2
3, Pergamon Press, Oxford, 1995, pp. 1ꢂ56.
/
[10] (a) B.C. Tzeng, W.C. Lo, C.M. Che, S.M. Peng, Chem. Commun.
(1996) 181.;
Theta range for data collection (8) 1.70ꢂ
Index ranges
/
05
ꢁ/
/
/
/175
/
k 5
/
16,
(b) C.M. Che, H.K. Yip, W.C. Lo, S.M. Peng, Polyhedron 13
(1994) 887;
/
/
Reflections collected/unique
Refinement method
11 197/6435 [Rint
Full-matrix least-squares on F2
ꢀ/
0.0234]
(c) W. Lu, H.F. Xiang, N. Zhu, C.M. Che, Organometallics 21
(2002) 2343;
Data/restraints/parameters
Goodness-of-fit on F2
6435/0/467
1.131
(d) C.M. Che, H.Y. Chao, V.M. Miskowski, Y. Li, K.K. Cheung,
J. Am. Chem. Soc. 123 (2001) 4985;
Final R indices [I ꢀ
R indices (all data)
/
2s(I)]
R1ꢀ
R1ꢀ
0.790 and ꢁ
/
0.0401, wR2ꢀ
0.0549, wR2ꢀ
0.624
/
0.1040
0.1209
/
/
See, for example
[11] (a) B. Olenyyuk, A. Fechtenkotter, P.J. Stang, J. Chem. Soc.
¨
Largest difference peak and hole
ꢁ3
/
˚
(e A
)
Dalton Trans. (1998) 1707.;
(b) S.-S. Sun, A.J. Lees, Inorg. Chem. 40 (2001) 3154.
[12] V.W.-W. Yam, K.K.-W. Lo, K.M.-C. Wong, J. Organomet.
Chem. 578 (1999) 3.
Acknowledgements
This work was supported by the DGICYT (Project
BQU2000-0644) and the CIRIT (Project 1999 SGR
00045). L.R. is indebted to the Universitat de Barcelona
for a scholarship. We are indebted to Prof. J.S. de Melo
from Departamento de Qu´ımica, Faculdade de Cieˆncias
e Tecnologia, of the Universidade de Coimbra for
lifetime measurements.
[13] H. Xiao, K.-K. Cheung, C.M. Che, J. Chem. Soc. Dalton Trans.
(1996) 3699.
[14] E.C. Constable, A.M.W. Cargill Thompson, J. Chem. Soc.
Dalton Trans. (1994) 1409.
[15] S.-S. Sun, A.J. Lees, Coord. Chem. Rev. 230 (2002) 171.
[16] A.J. Lees, Chem. Rev. 87 (1987) 711.
[17] J.S. de Melo, L.M. Silva, M. Kuroda, J. Chem. Phys. 115 (2001)
5625.
[18] L.D. Ciana, A. Haim, J. Heterocycl. Chem. 21 (1984) 607.
[19] S. Takahashi, Y. Kuroyama, K. Sonogashira, N. Hagihara,
Synthesis (1980) 627 (we have used Pd(PPh3)4 as a catalyst
instead of [PdCl2(PPh3)2]).
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/