1,2-dibromo- and 1,2-diiodotetrafluorobenzene as precursors of anionic homo- and heterometallic gold complexes

Article abstract of DOI:10.1021/om8000586

By reaction of LiR and [AuCl(tht)] the new organometallic compounds NBu₄[AuR₂] (R = 2-C₆BrF₄ (1), 2-C₆F₄I (2)) have been prepared. They react with TlPF ₆ in different molar ratios yielding anionic extended chains with the stoichiometrics {NBu₄[Tl₂(AuR₂) ₃]}_n, (R = 2-C₆BrF₄ (3), 2-C ₆F₄I (4)) and {NBu₄[Tl(AuR₂) ₂]}_n (R = 2-C₆BrF₄ (5), 2-C ₆F₄I (6)). The crystal structures of 3 and 4 consist of anionic chains formed by association of loosely bound Au₂Tl ₂ clusters interconnected by [AuR₂]^- anions via unsupported Au...Tl interactions, while 5 shows infinite polymetallic Au/Tl chains with an additional [AuR₂]^- fragment bonded to each Tl^I via unsupported Au...Tl contacts. The heterometallic bromotetrafluorophenyl complexes 3 and 5 display luminescence in the solid state, which is assigned to excited states that appear as result of the interactions between the metal centers. At 77 K different emissions appear in glassy solutions, which are assigned to the presence of oligomers of different length. In the case of the iodotetrafluorophenyl derivatives, in spite of presenting similar structures, complex 4 is weakly luminescent and complex 6 is nonluminescent both in the solid state at room temperature and at 77 K and in glassy solutions. This result is probably a consequence of the heavy-atom effect (HAE) due to the presence of iodine instead of bromine, which in the case of complex 4 provokes a reduction of the intensity if compared with its homologous compound 3 and which in 6 leads to the total quenching of the emission. 2008 American Chemical Society.

Full text of DOI:10.1021/om8000586

Organometallics 2008, 27, 2971–2979
2971
1,2-Dibromo- and 1,2-Diiodotetrafluorobenzene as Precursors of
Anionic Homo- and Heterometallic Gold Complexes
Eduardo J. Ferna´ndez,*,† Antonio Laguna,‡ Tania Lasanta,† Jose´ M. Lo´pez-de-Luzuriaga,†
Manuel Montiel,† and M. Elena Olmos†
Departamento de Qu´ımica, Grupo de S´ıntesis Qu´ımica de La Rioja, UA-CSIC, Complejo Cient´ıfico
Tecnolo´gico, UniVersidad de la Rioja, 26001 Logron˜o, Spain, and Departamento de Qu´ımica Inorga´nica,
Instituto de Ciencia de Materiales de Arago´n, UniVersidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
ReceiVed January 22, 2008
By reaction of LiR and [AuCl(tht)] the new organometallic compounds NBu4[AuR2] (R ) 2-C6BrF4
(1), 2-C6F4I (2)) have been prepared. They react with TlPF6 in different molar ratios yielding anionic
extended chains with the stoichiometries {NBu4[Tl2(AuR2)3]}n (R ) 2-C6BrF4 (3), 2-C6F4I (4)) and
{NBu4[Tl(AuR2)2]}n (R ) 2-C6BrF4 (5), 2-C6F4I (6)). The crystal structures of 3 and 4 consist of anionic
chains formed by association of loosely bound Au2Tl2 clusters interconnected by [AuR2]- anions via
unsupported Au · · · Tl interactions, while 5 shows infinite polymetallic Au/Tl chains with an additional
[AuR2]- fragment bonded to each TlI via unsupported Au · · · Tl contacts. The heterometallic bromotet-
rafluorophenyl complexes 3 and 5 display luminescence in the solid state, which is assigned to excited
states that appear as result of the interactions between the metal centers. At 77 K different emissions
appear in glassy solutions, which are assigned to the presence of oligomers of different length. In the
case of the iodotetrafluorophenyl derivatives, in spite of presenting similar structures, complex 4 is weakly
luminescent and complex 6 is nonluminescent both in the solid state at room temperature and at 77 K
and in glassy solutions. This result is probably a consequence of the heavy-atom effect (HAE) due to the
presence of iodine instead of bromine, which in the case of complex 4 provokes a reduction of the
intensity if compared with its homologous compound 3 and which in 6 leads to the total quenching of
the emission.
the networks and, consequently, to the optical properties
associated with the structure in the solid state or even in solution.
For instance, the reactions of NBu4[AuR2] (R ) C6F5, C6Cl5)
with TlPF6 in the presence of neutral ligands lead to different
dispositions of metals in the metallic chain or different
coordination environments for the metal centers.1,3,5 In all cases
the optical properties of these complexes are in agreement with
those found in the theoretical calculations.
Introduction
The synthesis of supramolecular networks is nowadays one
of the topics that is prompting more attention among the
organometallic or coordination chemists due, among other
factors, to the properties usually associated with those systems.
Our group has contributed with a number of papers in which
the structures and the optical properties associated with
gold-heterometal interactions are studied. In fact, the supramo-
lecular systems reported by us have a very rich structural
diversity and intriguing photoluminescent properties, as well
as, in some cases, potential applications as VOC sensors and
luminescence signaling or, in others, as precursors of organic
derivatives in potential catalytic reactions.1–19
Another interesting characteristic that can be observed in these
systems is the presence of secondary interactions that contribute
to the stability of the polymeric systems in the majority of the
complexes prepared following this strategy. These interactions
usually appear between the heterometal and some of the halogen
atoms of the perhalophenyl groups bonded to gold. In some
cases these interactions occur with the nearest atoms of these
rings, i.e. those placed in the ortho positions, but in others the
interactions appear even with adjacent chains, which produces
a three-dimensional network. For instance, that is the case of
the complex [AuTl(C6Cl5)2]n, in which each thallium center has
up to eight long Tl · · · Cl contacts.6 Presumably, these appear
as a consequence of an electron deficiency at the thallium centers
that is not saturated with neutral ligands.9
Among the reported methods that lead to these systems, one
of the best known, which is employed in our laboratory, is the
linkage of polyatomic anions or electron-rich molecules that
undergo coordination to the binding sites of Lewis acids, leading
to an enormous variety of extended structures.20 Specifically,
in our case, anionic gold precursors (bis(perhalophenyl)aurates)
react with AgX (X ) ClO4, CF3CO2), CuCl, or TlX (X ) NO3,
PF6), which act as Lewis acids, giving rise to extended linear
chains or two- or three-dimensional networks.1–3,5,6,8–14,16,17,19
In those studies, we have shown that the nature of the basic
gold precursors is essential to the disposition that the metal
centers display in the complexes and hence to the structure of
Therefore, it can be concluded from the previous comments
that the steric and electronic properties associated with these
perhalophenyl groups contribute to the metal-metal interactions,
the structures, and, consequently, the optical properties of the
heteronuclear materials.
* To whom correspondence should be addressed. E-mail:
eduardo.fernandez@unirioja.es.
Thus, following our current interest in knowing the different
factors that condition the optical properties of the heteronuclear
materials, we addressed the study to the preparation of new
† Universidad de La Rioja.
‡ Universidad de Zaragoza-CSIC.
10.1021/om8000586 CCC: $40.75
2008 American Chemical Society
Publication on Web 06/06/2008

2972 Organometallics, Vol. 27, No. 13, 2008
Ferna´ndez et al.
homoleptic basic gold precursors and analyzed the influence of
the aryl groups in the structures and optical properties in their
reactions with thallium hexafluorophosphate. In addition, the
number of organometallic homoleptic gold(I) complexes is very
limited, and only five examples of the type NBu4[AuR2] are
known (R ) C6F5, C6Cl5, C6Cl2F3, C6F3H2, FMes).21
Thus, in this paper we report the synthesis of the two new
gold precursors NBu4[Au(2-C6BrF4)2] and NBu4[Au(2-C6F4I)2]
and the study of their reactions with the acid salt TlPF6 in
different molar ratios, which lead in some cases to luminescent
materials.
Analytical and spectroscopic data of both complexes agree with
the proposed stoichiometries (see the Experimental Section).
Their IR spectra show, among others, absorptions at 1612, 1594,
1078, and 817 cm-1 in 1 and 1609, 1587, 1076, and 806 cm-1
in 2, arising from the presence of a pentahalophenyl group
+
bonded to gold(I), and at 880 cm-1 from NBu4 in both of
them. The presence of NBu4+ is also confirmed in their 1H NMR
spectra in CDCl3, which display signals corresponding to the
proton resonances of the cation in this solvent, and even in their
mass (ES+) spectra, in which the parent peak appears at m/z
242. Mass spectra (ES-) show signals corresponding to [Au(2-
C6F4X)2]- (X ) Br (1) at m/z 653 and X ) I (2) at m/z 747)
with the expected isotopic distributions. In addition, the 19F
NMR spectra of both complexes, 1 and 2, show patterns
corresponding to four types of inequivalent fluorine atoms,
which appear as doublets of doublets due to the small value of
the coupling constants between fluorine atoms in positions meta
to gold.23 However, when an halogen in an ortho position
relative to gold is replaced by a different halogen, it produces
a deshielding of the fluorine atoms in a position meta to gold.
When the 19F NMR spectra of complexes 1 and 2 are compared,
this effect can be seen in the position corresponding to the
fluorine atom located in an ortho position with respect to the
bromo or iodo center, and thus, it suffers a shift to lower field
as the electronegativity of the new halogen in an ortho position
decreases.
Results and Discussion
Synthesis and Characterization. The compounds NBu4[Au(2-
C6BrF4)2] (1) and NBu4[Au(2-C6F4I)2] (2) are obtained by
reaction of Li(2-C6F4X) (X ) Br, I) and [AuCl(tht)] following
procedures similar to those reported for analogous complexes.22
(1) Crespo, O.; Ferna´ndez, E. J.; Jones, P. G.; Laguna, A.; Lo´pez-de-
Luzuriaga, J. M.; Mend´ıa, A.; Monge, M.; Olmos, E. Chem. Commun. 1998,
2233.
(2) Ferna´ndez, E. J.; Gimeno, M. C.; Laguna, A.; Lo´pez-de-Luzuriaga,
J. M.; Monge, M.; Pyykko¨, P.; Sundholm, D. J. Am. Chem. Soc. 2000,
122, 7287.
(3) Ferna´ndez, E. J.; Jones, P. G.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.;
Monge, M.; Pe´rez, J.; Olmos, M. E. Inorg. Chem. 2002, 41, 1056.
(4) Ferna´ndez, E. J.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.; Olmos,
M. E.; Pe´rez, J.; Laguna, A. J. Am. Chem. Soc. 2002, 124, 5942.
(5) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Mendiza´bal,
F.; Monge, M.; Olmos, M. E.; Pe´rez, J. Chem. Eur. J. 2003, 9, 456.
(6) Ferna´ndez, E. J.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.; Olmos,
M. E.; Pe´rez, J.; Laguna, A.; Mohamed, A. A.; Fackler; Jr, J. P. J. Am.
Chem. Soc. 2003, 125, 2022.
Both of these compounds are soluble in acetone, tetrahydro-
furan, halogen solvents, and alcohols and insoluble in n-hexane,
diethyl ether, and water. In addition, these complexes slowly
decompose in solution, generating gold mirrors after having been
exposed to light for hours.
(7) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Olmos,
E.; Pe´rez, J. Chem. Commun. 2003, 1760.
Treatment of NBu4[Au(2-C6BrF4)2] (1) with equimolecular
amounts of TlPF6 in tetrahydrofuran and subsequent concentra-
tion under vacuum produces a yellow greenish solid. Addition
of dichloromethane allows the separation of a white solid, which
is separated by filtration and identified as TlPF6. The solution
is concentrated under vacuum and then toluene is added, leading
to the precipitation of NBu4PF6, which is filtered off. Evapora-
tion of the solvent to dryness affords complex 3, which is
isolated as a pale green solid with the stoichiometry {NBu4[Tl2-
{Au(2-C6BrF4)2}3]}n (see eq 1).
(8) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge,
M.; Montiel, M.; Olmos, M. E.; Pe´rez, J. Organometallics 2004, 23, 774.
(9) Ferna´ndez, E. J.; Lo´pez-de-Luzuriaga, J. M.; Monge, M.; Montiel,
M.; Olmos, M. E.; Pe´rez, J.; Laguna, A.; Mendiza´bal, F.; Mohamed, A. A.;
Fackler; Jr., J. P. Inorg. Chem. 2004, 43, 3573.
(10) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Olmos,
M. E.; Pe´rez, J. Dalton Trans. 2004, 1801.
(11) Ferna´ndez, E. J.; Jones, P. G.; Laguna, A.; Lo´pez-de-Luzuriaga,
J. M.; Monge, M.; Montiel, M.; Olmos, M. E.; Pe´rez, J. Z. Naturforsch.
2004, 59b, 1379.
(12) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge,
M.; Montiel, M.; Olmos, M. E. Inorg. Chem. 2005, 44, 1173.
(13) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Montiel,
M.; Olmos, M. E.; Pe´rez, J. Organometallics 2005, 24, 1631.
(14) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Montiel,
M.; Olmos, M. E.; Pe´rez, J. Inorg. Chim. Acta 2005, 358, 4293.
(15) Ferna´ndez, E. J.; Lo´pez-de-Luzuriaga, J. M.; Olmos, M. E.; Pe´rez,
J.; Laguna, A.; Lagunas, M. C. Inorg. Chem. 2005, 44, 6012.
(16) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Montiel,
M.; Olmos, M. E.; Pe´rez, J. Organometallics 2006, 25, 1689.
(17) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge,
M.; Montiel, M.; Olmos, M. E.; Rodr´ıguez-Castillo, M. Organometallics
2006, 25, 3639.
3nNBu4[AuR2] + 3nTlPF6 f {NBu4[Tl2{AuR2}3]}n +
1, 2
3, 4
nTlPF6 + 2nNBu4PF6 (1)
R ) 2-C6BrF4 (1, 3), 2-C6F4I (2, 4)
Complex 3 is stable to air and moisture, luminescent under
ultraviolet radiation, soluble in tetrahydrofuran, acetone, toluene,
and dichloromethane, and insoluble in diethyl ether, alcohols,
or n-hexane. Its IR spectrum shows, among others, absorptions
at 1617, 1595, 1088, and 823 cm-1 arising from the presence
of 2-bromotetrafluorophenyl groups bonded to gold(I) and at
883 cm-1 due to the presence of NBu4+, also confirmed in its
1H NMR spectrum in CDCl3, which displays signals at 3.22
(m, 2H, CH2), 1.65 (m, 2H, CH2), 1.39 (m, 2H, CH2), and 0.98
ppm (t, 3H, CH3). Its 19F NMR spectrum in CDCl3 shows the
resonances corresponding to four types of inequivalent fluorine
atoms at -113.4, -127.8, -158.5, and -160.6 ppm, chemical
shifts similar to those of the starting material (1). Compound 3
dissociates in solution, and it shows a conductivity near to that
(18) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M.; Monge,
M.; Montiel, M.; Olmos, M. E. Inorg. Chem. 2007, 46, 2953.
(19) Ferna´ndez, E. J.; Jones, P. G.; Laguna, A.; Lo´pez-de-Luzuriaga,
J. M.; Monge, M.; Olmos, M. E.; Puelles, R. C. Organometallics 2007, 26,
5931.
(20) (a) Hawthorne, M. F.; Zheng, Z. Acc. Chem. Res. 1997, 30, 267.
(b) Hawthorne, M. F. Pure Appl. Chem. 1994, 66, 245. (c) Wuest, J. D.
Acc. Chem. Res. 1999, 32, 81. (d) Vaugeois, J.; Simard, M.; Wuest, J. D.
Coord. Chem. ReV. 1995, 95, 55.
(21) (a) Laguna, A.; Gimeno, M. C. Trends Organomet. Chem. 1994,
1, 231. (b) Schmidbaur, H.; Grohmann, A.; Olmos, M. E.; Schier, A. In
The Chemistry of Organic DeriVatiVes of Gold and SilVer; Patai, S.,
Rappaport, Z., Eds.; Wiley: Chichester, U.K., 1999; pp 227-331. (c)
Schmidbaur, H.; Grohmann, A.; Olmos, M. E. In The Chemistry of Organic
DeriVatiVes of Gold and SilVer; Schmidbaur, H., Ed.; Wiley: Chichester,
U.K., 1999; pp 648-746. (d) Ferna´ndez, E. J.; Laguna, A.; Olmos, M. E.
AdV. Organomet. Chem. 2005, 52, 77.
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16, 5416.

Anionic Homo- and Heterometallic Gold Complexes
Organometallics, Vol. 27, No. 13, 2008 2973
of univalent 1:1 electrolytes (112 Ω-1 cm2 mol-1), whereas
that corresponding to its gold starting material is 108 Ω-1 cm2
mol-1
.
Similarly, NBu4[Au(2-C6F4I)2] (2) reacts with TlPF6 in
tetrahydrofuran, leading to the analogous product {NBu4[Tl2-
{Au(2-C6F4I)2}3]}n (4), which, after precipitation and separation
of TlPF6 and NBu4PF6 with toluene, is isolated from the solution
by precipitation with dichloromethane. Its IR spectrum shows,
among others, absorptions at 1614, 1588, 1080, and 806 cm-1
arising from the presence of 2-iodotetrafluorophenyl groups
bonded to gold(I) and at 886 cm-1 due to the presence of
NBu4+, also confirmed in its 19F and 1H NMR spectra in CDCl3,
which display signals at shifts similar to those described for 2.
The molar conductivities of both the gold precursor 2 and
complex 4 in acetone solution are similar (126 Ω-1 cm2 mol-1
for 4 and 117 Ω-1 cm2 mol-1 for 2), in accordance with the
presence of ionic species in solution. In addition, peaks
corresponding to [Au(2-C6F4I)2]-, [NBu4]+, or Tl+ are detected
in their mass spectra (electrospray), indicating the breaking of
the Au · · · Tl interactions in solution.
Interestingly, when the reaction of the gold precursor 1 or 2
with TlPF6 is carried out in the appropriate molar ratio (3:2) to
obtain complex 3 or 4, respectively, a new compound of
stoichiometry {NBu4[Tl{Au(2-C6F4X)2}2]}n (X ) Br (5), I (6)),
instead of the expected species, is obtained, and the unreacted
part of the starting products is recovered. Thus, when 1 or 2 is
treated with TlPF6, in a 2:1 molar ratio, complex 5 or 6,
respectively, is obtained (eq 2). Apparently, an increase in the
amount of gold in the reaction (from 50% to 60%, considering
only the metals) involves the synthesis of products with a higher
percentage of this metal (from 60% to 66%).
Figure 1. Structure of the anion of complex 3 (30% probability
level) with the labeling scheme of the atom positions. H atoms are
omitted for clarity.
887 cm-1, respectively. In addition, its elemental analyses are
in accordance with the theoretical ones (see the Experimental
Section).
On the other hand, as has been previously reported,1,3,5,9–11
neutral polymeric Au/Tl systems of the type {Tl[AuR2]}n react
with O-, N-, or S-donor ligands, such as tetrahydrofuran,
acetylacetone, 1,10-phenanthroline, and 2,2′- and 4,4′-bipyridine,
incorporating the new ligands in the coordination sphere of the
thallium centers. With monodentate or bidentate chelate ligands
1D polymers built up via Au · · · Tl interactions (similar to the
starting products) are obtained, but the presence of bridging
ligands, such as 4,4′-bipy, or secondary thallium · · · halogen
interactions between adjacent chains leads to two- or three-
dimensional polymers. The strength of the Au · · · Tl interaction
has been calculated to be about 276 kJ mol-1, with an 80%
ionic and a 20% van der Waals contribution.5
2nNBu4[AuR2] + nTlPF6 f {NBu4 [Tl{AuR2}2]}n (2)
1, 2
5, 6
R ) 2-C6BrF4 (1, 5), 2-C6F4I (2, 6)
In contrast, when similar reactions are carried out starting
from 3-6 and an excess of acetone, tetrahydrofuran, or toluene
(used as solvents), the starting Au/Tl complexes 3-6 are
recovered unaltered.
Complexes {NBu4[Tl{Au(2-C6F4X)2}2]}n (X ) Br (5), I (6))
can be alternatively be synthesized by treatment of {NBu4[Tl2-
{Au(2-C6F4X)2}3]}n (X ) Br (3), I (4)), respectively, with an
equimolecular amount of NBu4[Au(2-C6F4X)2] (X ) Br (1), I
(2)) (see eq 3).
These results seem to indicate that the donor capability of
one [Au(C6X5)2]- unit is not enough to neutralize the acidity
of a Tl+ center, and it requires additional electronic density
sources, such as covalent or van der Waals interactions. Thus,
in neutral Au/Tl systems, covalent bonds with O-, N-, or S-donor
ligands or Tl · · · X interactions are needed to neutralize the Tl(I)
centers, while in the case of 3-6, the additional [AuR2]- units
act as electron donor moieties against the still acidic Tl+ centers.
{NBu4[Tl2{AuR2}3]}n + nNBu4[AuR2] f
3, 4
1, 2
2{NBu4[Tl{AuR2}]}n (3)
5, 6
R ) 2-C6BrF4 (1, 3, 5), 2-C6F4I (2, 4, 6)
The compound {NBu4[Tl{Au(2-C6BrF4)2}2]}n (5) is isolated
as a yellow solid, which is stable to air and moisture. Its IR
spectrum shows, among others, absorptions at 1613, 1595, 1083,
and 822 cm-1 arising from the presence of 2-bromotetrafluo-
rophenyl groups bonded to gold(I) and at 879 cm-1 due to the
Crystal Structures. Single crystals of complexes 3 and 4
suitable for X-ray diffraction studies were obtained by slow
diffusion of n-hexane into a saturated solution of the complex
in a mixture of toluene and THF (2:1). They can be described
as infinite chains formed via unsupported Au · · · Tl interactions
which have incorporated an additional [Au(2-C6F4X)2]- (X )
Br (3), I (4)) fragment per thallium to the chain, which act as
bridging metallo ligands (Figures 1 and 2). Thus, the anionic
chains can also be seen as an association of loosely bound
butterfly Au2Tl2 clusters that are joined together by an anionic
[Au(2-C6F4X)2]- fragment also via new Au · · · Tl unsupported
interactions. The tetranuclear Au2Tl2 units are similar to those
present in the crystal structures of the discrete loosely bound
butterfly clusters [Au2Tl2(C6Cl5)4] · L (L ) Me2CdO, PhMeCdO,
acacH)4,15 or [Au2Tl2(C6Cl5)4(bipy)] · acacH15 or in the anionic
1
presence of NBu4+, which is also confirmed in its H NMR
spectrum in CDCl3. Its 19F NMR spectrum in CDCl3 shows
resonances corresponding to four types of inequivalent fluorine
atoms at positions similar to those in complex 1. Its molar
conductivity in acetone solution is 132 Ω-1 cm2 mol-1, which
confirms that this compound dissociates in solution.
The compound {NBu4[Tl{Au(2-C6F4I)2}2]}n (6) is isolated
as a yellow solid stable to air and moisture, with a very low
solubility in the usual solvents, which makes its characterization
difficult. However, the presence of fragments such as [Au(2-
C6F4I)2]- and NBu4 is pointed out in its IR spectrum, which
polymer [Tl2{Au(C6Cl5)2}3]- 13 and also resemble the Au2Ag2
+
n
displays absorptions at 1642, 1575, 1070, and 804 cm-1 and at
fragments observed in [Au2Ag2(C6F5)4L2]n (L ) neutral

2974 Organometallics, Vol. 27, No. 13, 2008
Ferna´ndez et al.
Figure 2. Structure of the anion of complex 4 (30% probability level) with the labeling scheme of the atom positions. H atoms are omitted
for clarity.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for Complex 3a
Au(1)-C(1)
Au(1)-C(11)
Au(2)-C(21)
Au(2)-C(31)
Au(3)-C(51)
Au(3)-C(41)
2.050(9)
2.053(9)
2.061(9)
2.070(9)
2.027(10)
2.038(10)
Au(1)-Tl(2)#1
Au(1)-Tl(1)
Au(2)-Tl(2)
Au(2)-Tl(1)
Au(3)-Tl(2)
Au(3)-Tl(1)
3.0127(5)
3.0355(5)
3.0832(5)
3.1247(5)
3.0924(5)
3.1021(5)
C(1)-Au(1)-C(11)
Tl(2)#1-Au(1)-Tl(1)
C(21)-Au(2)-C(31)
Tl(2)-Au(2)-Tl(1)
C(51)-Au(3)-C(41)
Tl(2)-Au(3)-Tl(1)
178.3(3)
169.408(17)
175.0(3)
85.622(13)
175.1(4)
85.854(13)
Au(1)-Tl(1)-Au(3)
Au(1)-Tl(1)-Au(2)
Au(3)-Tl(1)-Au(2)
Au(1)#2-Tl(2)-Au(2)
Au(1)#2-Tl(2)-Au(3)
Au(2)-Tl(2)-Au(3)
122.993(15)
138.145(16)
90.719(13)
151.924(16)
112.319(15)
91.685(13)
a Symmetry transformations used to generate equivalent atoms: (#1) x + 1/2, y, -z + 1/2; (#2) x - 1/2, y, -z + 1/2.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for Complex 4a
Au(1)-C(1)
Au(2)-C(11)
Au(2)-C(21)
Au(3)-C(31)
Au(3)-C(41)
Au(4)-C(51)
2.061(12)
2.034(11)
2.044(12)
2.048(13)
2.097(11)
2.066(12)
Au(1)-Tl(1)
Tl(1)-Au(3)
Tl(1)-Au(2)
Au(2)-Tl(2)
Tl(2)-Au(4)
Tl(2)-Au(3)
3.3644(6)
3.0682(7)
3.4659(8)
3.1213(6)
2.9956(5)
3.0791(7)
C(1)-Au(1)-C(1)#1
Tl(1)#1-Au(1)-Tl(1)
C(11)-Au(2)-C(21)
Tl(2)-Au(2)-Tl(1)
C(31)-Au(3)-C(41)
Tl(1)-Au(3)-Tl(2)
C(51)#2-Au(4)-C(51)
180.0(5)
180.00(3)
173.4(4)
82.320(16)
168.8(4)
89.91(2)
Tl(2)-Au(4)-Tl(2)#2
Au(3)-Tl(1)-Au(1)
Au(3)-Tl(1)-Au(2)
Au(1)-Tl(1)-Au(2)
Au(4)-Tl(2)-Au(3)
Au(4)-Tl(2)-Au(2)
Au(3)-Tl(2)-Au(2)
180.0
108.41(2)
87.567(18)
162.75(2)
120.568(19)
145.38(2)
93.877(17)
180.000(2)
a Symmetry transformations used to generate equivalent atoms: (#1) -x, -y, -z; (#2) -x + 1, -y, -z + 1.
ligand).2,17,24 However, in the latter the Au2M2 units are more
planar than in the thallium complexes and associate through
Au · · · Au interactions instead of via Au · · · M contacts. In
complex 3 the Au-Tl distances within the tetranuclear units
are of the same order, lying in the range 3.0832(5)-3.1247(5)
Å, and are close to those found in similar Au2Tl2 units4,13,15
but slightly longer than the Au-Tl interactions that join the
Au2Tl2 fragments and the bridging bis(perhalophenyl)aurate(I)
anions (3.0127(5) and 3.0355(5) Å). The latter compare well
with those observed in most of the polymeric species with
unsupported Au · · · Tl interactions.1,3,5,6,8–11,13 In contrast, the
Au-Tl lengths in 4 are more dissimilar, both within the Au2Tl2
cores (3.0682(7)-3.4659(8) Å) and between the tetranuclear
units and the [Au(C6F4I)2]- fragments (2.9956(5) and 3.3644(6)
Å), the longest one being of the same order as the Au-Tl
distances found in the pentachlorophenyl derivatives [{Tl2-
(THF)2(µ-4,4′-bipy)}{Au(C6Cl5)2}2]n (3.4800(3) Å) or [{Tl-
(2,2′-bipy)}{Au(C6Cl5)2}]n (3.4899(6) Å).11 The presence of
aurophilic interactions within the clusters can be ruled out, since
the shortest metal-metal distance between gold(I) centers
(Au(2)-Au(3) ) 4.431 (3), 4.530 Å (4)) is longer than twice
its van der Waals radius (3.32 Å).
The bond lengths and angles within the tetranuclear units are,
in general, similar to those found in the Au2Tl2 loosely bound
clusters previously reported,4,13,15 with Au-C distances ranging
between 2.027(10) and 2.070(9) Å in 3 and between 2.034(11)
(24) (a) Uso´n, R.; Laguna, A.; Laguna, M.; Jones, P. G.; Sheldrick, G. M.
Chem. Commun. 1981, 1097. (b) Uso´n, R.; Laguna, A.; Laguna, M.;
Manzano, B. R.; Jones, P. G.; Sheldrick, G. M. J. Chem. Soc., Dalton Trans.
1984, 285.

Anionic Homo- and Heterometallic Gold Complexes
Organometallics, Vol. 27, No. 13, 2008 2975
Figure 3. Polymetallic chain of complexes (a) 3 and (b) 4 with the [Au(C6F4X)2]- anions acting as bridging metallo ligands: (yellow) gold;
(blue) thallium.
and 2.097(11) Å in 4 and the Au-C bond lengths corresponding
to the bridging [Au(C6F4X)2]- fragments lying within these
ranges (see Tables 1 and 2). As in the anionic polymer
{NBu4[Tl2{Au(C6Cl5)2}{µ-Au(C6Cl5)2}2]}n,13 the gold(I) centers
of the tetranuclear units in 4 display a more distorted linear
environment (C-Au-C ) 168.8(4), 173.4(4)°) than in the
previous examples (C-Au-C ) 173.7(2)-178.0(2)°)4,15 or
than in 3 (C-Au-C ) 175.0(3), 175.1(4)°), while the
[Au(C6BrF4)2]- fragments that join two Au2Tl2 units contain
perfectly linear two-coordinate gold atoms (if the intermetallic
interactions are not considered). The M-M′-M angles within
the Au2Tl2 units (see Tables 1 and 2) compare well with those
13
found in complex {NBu4[Tl2{Au(C6Cl5)2}{µ-Au(C6Cl5)2}2]}n
and differ slightly from those observed in the loosely bound
butterfly Au2Tl2 clusters previously described,4,15 showing wider
Tl-Au-Tl and narrower Au-Tl-Au angles, which avoids the
formation of Tl · · · Tl interactions (Tl-Tl: 4.219 (3) and 4.530
Å (4)) that are present in discrete Au2Tl2 clusters (Tl-Tl:
3.6027(6)-3.7152(4) Å).4,15
The coordination sphere of the Tl atoms in these two
complexes is almost planar (sum of Au-Tl-Au angles of Tl(I)
of 351.9 and 355.9° (3) or 359.8 and 358.7° (4)) with a nearly
T-shape environment for Tl1 in 4 (see Table 2). Thus, the
stereoactivity of the inert pair, usually stereochemically active,25
is not apparent in these cases. The main difference between these
two structures is the disposition of the tetranuclear units in the
polymeric chain, which form an angle of about 70° in 3 while
they are nearly parallel in 4, as shown in Figure 3.
Figure 4. Structure of the anion of complex 5 (30% probability
level) with the labeling scheme of the atom positions. H atoms are
omitted for clarity.
P(O)(OMe)2]2}Tl29 (3.537 Å) and, considering the van der
Waals radii of bromine (1.85 Å) and iodine (1.98 Å),30 are
stronger than the Tl · · · Br contacts in 3, which seem to have an
important effect on the optical properties of these products (see
below).
The crystal structure of complex 5 was also determined from
single crystals obtained by slow diffusion of n-hexane into a
saturated solution of the complex in a mixture of toluene and
THF (2:1). It can be seen as an infinite polymetallic Au/Tl chain
formed via unsupported Au · · · Tl interactions in which each
thallium(I) center binds a terminal [Au(C6BrF4)2]- fragment also
via a Au · · · Tl contact (see Figures 4 and 5), thus forming
anionic chains which run parallel to the crystallographic x axis.
The separations between the metals that form the polymetallic
chain, of 3.0054(4) and 3.0216(4) Å, are slightly longer than
the intermetallic distance between thallium and the terminal
[Au(C6BrF4)2]- group (2.9354(6) Å), and all of them lie within
the range of Au-Tl distances observed in most of the polymeric
species with unsupported Au · · · Tl interactions (Table 3).1,3,5,6,8–11
As in the case of complex 4, as well as in the related
complexes {NBu4[Tl2{Au(C6Cl5)2}{µ-Au(C6Cl5)2}2]}n, {NBu4[Tl-
{Au(3,5-C6Cl2F3)2}2]}n, and {NBu4[Tl{Au(C6Cl5)2}{Au(3,5-
C6Cl2F3)2}]}n,13 the Au(I) atoms of the main chain display a
perfectly linear (if the intermetallic interactions are not taken
into account) or square-planar environment (if they are consid-
Finally, it is worth noting that the thallium(I) centers maintain
interactions with some of the heavier halogens. Thus, in 3 there
are two Tl · · · Br contacts of 3.3924(13) and 3.4587(11) Å for
Tl2 · · · Br42 and Tl1 · · · Br22, respectively, shorter than in
[Tl(1,4-dioxane)][TlBr4] (3.564 Å)26 or in Tl2[fac-Os(CO)Br2F3]
(3.294-3.540 Å)27 and identical to the shortest contact in [Tl(η6-
toluene)2](Br6CB11H6) (3.393 and 3.592 Å),28 where the bromine
atoms act as bridges between two thallium centers, thus forming
a dimer. There are also two Tl · · · I interactions of 3.4749(11)
and 3.4701(15) Å in complex 4 for Tl1 · · · I32 and Tl2 · · · I42,
respectively, which are shorter than in {C5Me5RhI[µ2-
(25) Kristiansson, O. Eur. J. Inorg. Chem. 2002, 2355.
(26) Marsh, R. E.; Herbstein, F. H. Acta Crystallogr., Sect. B: Struct.
Crystallogr., Cryst. Chem. 1988, 44, 77.
(27) Bernhardt, E.; Preetz, W. Z. Anorg. Allg. Chem. 1998, 624–694.
(28) Mathur, R. S.; Drovetskaya, T.; Reed, C. A. Acta Crystallogr., Sect.
C: Cryst. Struct. Commun 1997, 53, 881.
(29) Valderrama, M.; Scotti, M.; Campos, P.; Werner, H.; Mu¨ller, G.
Chem. Ber. 1990, 123, 1005.
(30) Source: http://www.webelements.com/.

2976 Organometallics, Vol. 27, No. 13, 2008
Ferna´ndez et al.
Figure 5. Polymetallic chain of complex 5 with the [Au(C6BrF4)2]- anions acting as terminal metallo ligands: (yellow) gold; (blue) thallium.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Complex 5a
energy below 350 nm and a maximum at 291 nm. In addition,
other heterometallic gold-thallium complexes with the related
aryl group C6F5 also show UV-vis spectra with similar features
and with high-energy bands between 250 and 325 nm and a
maximum absorption at 275 nm, which were said to have a
similar origin.14 In addition, as we have noted above in Synthesis
and Characterization, neither the spectroscopic data (NMR, MS)
nor the molar conductivity measurements indicate association
between the different ionic counterparts in solution.
Au(1)-C(1)
Au(1)-C(11)
Au(2)-C(21)
Au(3)-C(31)
2.072(13)
2.079(12)
2.091(15)
2.067(15)
Au(1)-Tl
Tl-Au(2)
Tl-Au(3)
2.9354(6)
3.0054(4)
3.0216(4)
C(1)-Au(1)-C(11)
173.8(4)
Au(1)-Tl-Au(2) 113.323(17)
Au(1)-Tl-Au(3) 98.505(16)
180.000(19) Au(2)-Tl-Au(3) 145.637(17)
C(31)-Au(3)-C(31)#2 180.000(2) Tl-Au(3)-Tl#2 180.0
C(21)-Au(2)-C(21)#1 180.000(2)
Tl#1-Au(2)-Tl
The absence of low-energy emissions in solution for these
types of heteronuclear extended systems is not rare.31 In fact,
the only exceptions to this behavior appear in systems that show
TlI-TlI interactions in the solid state.4,8,14,15 In our case,
complex 3 is the one that shows the thallium centers at a shorter
distance (4.291 Å), although they are far from the sum of their
van der Waals radii. Thus, from these comments, it seems likely
that the gold-thallium interactions are the main contributors
to the emissive excited states.
Nevertheless, taking the structural data into account, we
cannot establish a relationship between the metal-metal dis-
tances and the emission energies for both complexes. For
instance, the shortest Au-Tl distance in complex 5 (2.9354(7)
Å) does not lead to the lowest energy emission. In addition,
previous TD-DFT calculations carried out for related hetero-
nuclear gold-thallium complexes point out the anionic [AuR2]-
fragments as the origin of the electronic transitions with a high
contribution of the perhalophenyl groups.3,5,6 Therefore, the
emitting states responsible for the luminescence in the solid state
for these complexes are likely to arise from a mixture of metal
(gold) to metal (thallium) charge transfer (MMCT) and ligand
(perhalophenyl) to metal (gold-thallium) charge transfer (LMCT).
a Symmetry transformations used to generate equivalent atoms: (#1)
-x, -y + 1, -z + 1; (#2) -x + 1, -y + 1, -z + 1.
ered), while those present in the terminal [Au(C6BrF4)2]- units
show a C-Au-C angle of 173.8(4)°.
If the intermetallic contacts are considered, the coordination
sphere of the Tl atoms in this complex is, as in 3 and 4, almost
planar (sum of Au-Tl-Au angles of 357.5°) with a distorted-
trigonal-planar environment. Again, the inert electron pair in
Tl(I) seems to be stereochemically nonactive in this case, which
is not the usual case.
Finally, there are intramolecular Tl · · · Br interactions of
3.3722(19) Å, even shorter than in complex 3, as well as
intermolecular contacts of 3.4455(21) Å between the thallium
centers of a chain and a bromine atom of an adjacent polymer,
which probably contribute to the stability of the system.
Optical Properties. In addition to the interesting structures,
some of the complexes display a brilliant luminescence when
they are irradiated with UV light in solid state, but others are
weakly luminescent or even are not luminescent, in spite of
having similar structures. Thus, the bromoaryl complexes
{NBu4[Tl2(Au(2-C6BrF4)2)3]}n (3) and {NBu4[Tl(Au(2-C6Br-
F4)2)2]}n (5) display a strong luminescence at room temperature
at 500 nm (excitation at 400 nm) for 3 and 520 nm (excitation
at 420 nm) for 5, respectively, independent of the excitation
wavelengths. At 77 K in the solid state the emissions red-shift,
appearing at 515 nm (excitation at 400 nm) and 560 nm
(excitation at 475 nm), respectively (see Figure 6). In addition,
the lifetimes of both complexes in the solid state at room
temperature display a monoexponential decay with values of
10.5 µs (R2 ) 0.993) (3) and 10.9 µs (R2 ) 0.991) (5), in
accordance with phosphorescent processes.
Both complexes lose these emissions when they are dissolved,
recovering them when the solvent is evaporated. Instead, in
dilute tetrahydrofuran solutions weak emissions at 425 nm,
whicharealsoobservedintheprecursorgoldcomplexNBu4[Au(2-
C6BrF4)2] (1), appear. Therefore, these new emissions are likely
to be due to ππ* transitions located in the perhalophenyl rings.
In accordance with this, the UV-vis spectra of these hetero-
metallic complexes and the gold precursor in deoxygenated
tetrahydrofuran show similar features with absorptions of high
In the case of frozen dilute solutions at 77 K, both products
display similar emissions. Glassy EtOH/MeOH (4:1; 5 × 10-4
M) solutions of both complexes show emissions at 425 and 490
nm by excitation at 310-360 nm, the first one appearing as a
shoulder of the less energetic emission (see Figure 7).
This 425 nm band also appears in the precursor NBu4[Au(2-
C6BrF4)2] (1) under the same conditions. Consequently, similarly
to what happened in solution at room temperature, it is likely
to be due to ππ* transitions located in the perhalophenyl rings.
In contrast, the low-energy emission can be assigned to a smaller
oligomer that appears in both complexes as a consequence of
the rapid cooling of the solutions. Similar results are obtained
when the solutions are prepared with THF as solvent at 77 K;
therefore, the formation of exciplexes with the solvent in the
excited state can be ruled out. Another plausible explanation
could arise from the Br · · · Tl interaction that appears in both
crystal structures, which could lead to an LMCT transition for
the low-energy emissions. Nevertheless, the different lengths
of the Au · · · Tl interactions observed in both complexes do not
seem to influence the excited states responsible for the emissions.
(31) (a) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga, J. M. Gold
Bull. 2001, 34 (1), 14. (b) Ferna´ndez, E. J.; Laguna, A.; Lo´pez-de-Luzuriaga,
J. M. Coord. Chem. ReV. 2005, 249, 1423. (c) Ferna´ndez, E. J.; Laguna,
A.; Lo´pez-de-Luzuriaga, J. M. Dalton Trans. 2007, 1969.
In the case of the complexes {NBu4[Tl2(Au(2-C6F4I)2)3]}n
(4) and {NBu4[Tl(Au(2-C6F4I)2)2]}n (6) and in spite of the
similarity of the stoichiometries to those of the aforementioned

Anionic Homo- and Heterometallic Gold Complexes
Organometallics, Vol. 27, No. 13, 2008 2977
Figure 6. Corrected excitation and emission spectra of complexes 3 (left) and 5 (right) at room temperature (black line) and at 77 K (red
line).
3 and 5. Neither does the precursor NBu4[Au(2-C6F4I)2] (2),
which does not display any luminescence in solution at room
temperature or at 77 K. This fact or even the absence of
luminescence for complex 6 is likely to be due to an iodide
heavy-atom effect (HAE), which in the case of complex 4
provokes a reduction of the intensity if compared with the
homologous complex 3 and that in complex 6 leads to the total
quenching of the emission. In fact, recently, Omary et al.
reported a study about the influence of the heavy-atom effect
on the luminescence of the adducts of the 1-halonaphthalene
series with perfluoro-o-phenylenemercury.33 In this paper it was
suggested that the synergy of the internal iodide HAE with the
external mercury HAE led to quenching vs unsubstituted
naphthalene, due to a larger nonradiative decay rate constant
(knr) at room temperature. This was in contrast to the situation
in the bromo and chloro analogues, where this synergy led to
an enhancement vs unsubstituted naphthalene due to a larger
Figure 7. Corrected excitation and emission spectra of complex 3
in glassy EtOH/MeOH (4:1) solution at 77 K.
radiative decay rate constant (kr) at room temperature.
complexes 3 and 5, each shows a very different optical behavior.
Thus, complex 4 is weakly luminescent in the solid state and
complex 6 does not display any emission. For example, complex
4 shows an emission at 555 nm (excitation at 450 nm) in the
solid state, which is independent of the excitation wavelength
and the temperature (emission at 555 nm at 77 K).
The interesting rigidochromism in the solid state is assigned
by some authors to a rigidity in the structure that prevents the
decrease of the metal-metal distances when the temperature is
lowered.32 In this case, it is worth noting that the structure
displays short TlI-I contacts that probably contribute to shorten
the Au-Tl distances, which is difficult when the temperature
is lowered.
As before, the emission at 555 nm disappears when the
measurements are carried out in solution at room temperature
and it is regenerated when the solvent is evaporated, which is
indicative of the influence of the metal-metal interactions in
the excited state. Both complexes display similar UV-vis
spectra, which is interpreted as a dissociation into the cationic
and anionic counterparts provoked by the solvent. In frozen THF
or EtOH/MeOH (4:1) at 77 K it displays an emission at 495
nm (excitation at 365 nm) that is likely to be attributed to
oligomers formed as a consequence of the cooling of the
solutions.
Experimental Section
Instrumentation. Infrared spectra were recorded in the 4000-200
cm-1 range on a Nicolet Nexus FT-IR instrument using Nujol mulls
between polyethylene sheets. C, H, N analyses were carried out
with a Perkin-Elmer 240C microanalyzer. Mass spectra were
recorded on a HP5989B API-Electrospray spectrometer. 1H and
19F NMR spectra were recorded on a Bruker ARX 300 spectrometer
in CDCl3 or THF-d8 solutions. Chemical shifts are quoted relative
to SiMe4 (1H, external) and CFCl3 (19F, external). Excitation and
emission spectra were recorded with a Jobin-Yvon Horiba Fluorolog
3-22 Tau-3 spectrofluorimeter. Phosphorescence lifetimes were
recorded with a Fluoromax phosphorimeter accessory containing
a UV xenon flash tube with a flash rate between 0.05 and 25 Hz.
The lifetime data were fitted using the Jobin-Yvon software package
and the Origin 6.1 program.
General Comments. Thallium(I) hexafluorophosphate,
o-C6Br2F4, and o-C6BrF4I are commercially available and were
purchased from Aldrich. Solvents were freshly distilled under argon
prior to use, and all the reactions were carried out under argon.
Synthesis of NBu4[Au(2-C6BrF4)2] (1). To a diethyl ether
solution of Li(2-C6BrF4) (30 mmol) at 203 K was added [Au-
Cl(tht)]34 (3.20 g, 10 mmol). After 1 h of stirring, NBu4Br (4 g,
12.5 mmol) was added and the reaction mixture was stirred at 203
K for 40 min. After 8-10 h of stirring at room temperature, a white
solid was separated by filtration and washed with water (3 × 5
mL), diethyl ether (3 × 5 mL), and n-hexane (3 × 5 mL). The
solid was solved in dichloromethane and the solution concentrated
In contrast, interestingly, this complex in solution does not
show emissions in the blue region, as in the case of complexes
(32) (a) Wrighton, M.; Morse, D. L. J. Am. Chem. Soc. 1974, 96, 998.
(b) Wang, S.; Garzo´n, G.; King, C.; Wang, J. C.; Fackler, J. P., Jr Inorg.
Chem. 1989, 28, 4623. (c) Itokazu, M. K.; Polo, A. S.; Iha, N. Y. M. J.
Photochem. Photobiol. A: Chem. 2003, 160, 27.
(33) Elbjeirami, O.; Burress, C. M.; Gabba¨ı, F. P.; Omary, M. A. J.
Phys. Chem. C 2007, 111, 9522.
(34) Uso´n, R.; Laguna, A. Organomet. Synth. 1989, 3, 322.

2978 Organometallics, Vol. 27, No. 13, 2008
Ferna´ndez et al.
Table 4. Details of Data Collection and Structure Refinement for Complexes 3-5
3
4
5
chem formula
cryst habit
cryst size/mm
cryst syst
C52H36Au3Br6F24NTl2
green plate
0.3 × 0.1 × 0.08
orthorhombic
Pbca
C52H36Au3F24I6NTl2
green prism
C40H36Au2Br4F16NTl
yellow prism
0.75 × 0.5 × 0.25
triclinic
0.15 × 0.1 × 0.1
triclinic
j
j
P1
space group
P1
a/Å
b/Å
c/Å
19.3225(1)
25.5870(2)
25.6821(2)
90
90
90
12 697.35(15)
82
2.731
13.7380(2)
15.2812(2)
18.1752(3)
102.704(1)
104.618(1)
96.847(1)
3539.44(9)
2
11.5160(2)
13.9090(3)
16.5790(4)
109.171(1)
96.968(1)
104.685(1)
2364.76(9)
2
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
Dc/g cm-3
2.713
2.461
Mr
F(000)
2609.92
9440
2891.86
2576
1752.64
1612
T/°C
-100
-100
-100
2θmax/deg
54
54
56
µ(Μo KR)/mm-1
no. of rflns measd
no. of unique rflns
Rint
15.851
182 931
13 383
0.0671
0.0427
0.1128
13 383
811
73
13.446
56 203
14 892
0.0572
0.0549
0.1640
14 892
797
13.061
33 734
11 049
0.0901
0.0658
0.1819
11 049
580
R(F > 2σ(F))a
Rw(F2, all rflns)b
no. of rflns used
no. of params
no. of restraints
Sc
86
1.032
1.967
58
1.027
3.914
1.020
1.788
max residual electron density/e Å-3
2
2 2
2
2
a R(F) ) ∑||Fo| - |Fc||/∑|Fo|. b Rw(F2) ) [∑{w(Fo - Fc ) }/∑{w(Fo2)2}]0.5; w-1 ) σ2(Fo2) + (aP)2 + bP, where P ) [Fo + 2Fc ]/3 and a and b
2
2 2
are constants adjusted by the program. c S ) [∑{w(Fo - Fc ) }/(n - p)]0.5, where n is the number of data and p is the number of parameters.
under vacuum. Finally, the addition of n-hexane (20 mL) led to
the precipitation of product 1 as a white solid. Yield: 90%. Anal.
Calcd for 1 (C28H36AuBr2F8N): C, 37.56; H, 4.05; N, 1.56. Found:
evaporated to dryness, and complex 3 was obtained as a pale green
solid, after washing with hexane (3 × 5 mL). Yield: 83%. Anal.
Calcd for 3 (C52H36Au3Br6F24NTl2): C, 23.93; H, 1.39; N, 0.54.
1
1
C, 36.48; H, 4.12; N, 1.50. H NMR (75.5 MHz, CDCl3, ppm): δ
Found: C, 24.07; H, 1.44; N, 0.52. H NMR (75.5 MHz, THF-d8,
3.05 (m, 2H, CH2), 1.48 (m, 2H, CH2), 1.31 (m, 2H, CH2), 0.91 (t,
3H, CH3). 19F NMR (282.4 MHz, CDCl3, ppm): δ -114.6 (dd,
1F, F1, 3J(F1-F2) ) 33.9 Hz, 5J(F1-F4) ) 13.4 Hz), -127.7 (dd,
ppm): δ 3.22 (m, 2H, CH2), 1.65 (m, 2H, CH2), 1.39 (m, 2H, CH2),
0.98 (t, 3H, CH3). 19F NMR (282.4 MHz, THF-d8, ppm): δ -113.4
(dd, 1F, F1, 3J(F1-F2) ) 33.0 Hz, 5J(F1-F4) ) 13.2 Hz), -127.8
(dd, 1F, F4, 3J(F4-F3) ) 20.6 Hz), -158.5 (dd, 1F, F2, 3J(F2-F3)
) 19.9 Hz), -160.6 (dd, 1F, F3). ES(+): m/z (%) 242 [NBu4]+
(100), 205 [Tl]+ (30). ES(-): m/z (%) 653 [Au(2-C6BrF4)2]- (100).
3
3
1F, F4, J(F4-F3) ) 21.3 Hz), -158.3 (dd, 1F, F2, J(F2-F3) )
19.7 Hz), -160.3 (dd, 1F, F3). ES(+): m/z (%) 242 [NBu4]+ (100).
ES(-): m/z (%) 653 [Au(2-C6BrF4)2]- (100). FT-IR (Nujol): ν(2-
C6BrF4) at 1612, 1594, 1078, and 817 cm-1, ν(NBu4+ C-N st) at
FT-IR (Nujol): ν(2-C6BrF4) at 1617, 1595, 1088, and 823 cm-1
,
880 cm-1
.
+
ν(NBu4 C-N st) at 883 cm-1
.
Synthesis of NBu4[Au(2-C6F4I)2] (2). To a diethyl ether solution
of Li(2-C6F4I) (30 mmol) at 203 K was added [AuCl(tht)] (3.20 g,
10 mmol). After 1 h of stirring, NBu4Br (4 g, 12.5 mmol) was
added and the reaction mixture was stirred at 203 K for 40 min.
After 20 h of stirring at room temperature, a solid was separated
by filtration and washed with water (3 × 5 mL), diethyl ether (3 ×
5 mL), and n-hexane (3 × 5 mL). The solid was dissolved in
dichloromethane and the solution concentrated under vacuum.
Finally, the addition of n-hexane (20 mL) led to the precipitation
of product 2 as an ocher solid. Yield: 93%. Anal. Calcd for 2
(C28H36AuI2F8N): C, 33.99; H, 3.67; N, 1.42. Found: C, 34.16; H,
3.56; N, 1.32. 1H NMR (75.5 MHz, CDCl3, ppm): δ 3.13 (m, 2H,
CH2), 1.56 (m, 2H, CH2), 1.35 (m, 2H, CH2), 0.94 (t, 3H, CH3).
19F NMR (282.4 MHz, CDCl3, ppm): δ -113.2 (dd, 1F, F4,
3J(F4-F3) ) 22.5 Hz, 5J(F4-F1) ) 13.7 Hz), -115.0 (dd, 1F, F1,
3J(F1-F2) ) 33.8 Hz), -157.6 (dd, 1F, F2, 3J(F2-F3) ) 19.2 Hz),
-160.4 (dd, 1F, F3). ES(+): m/z (%) 242 [NBu4]+ (100). ES(-):
m/z (%) 747 [Au(2-C6F4I)2]- (100). FT-IR (Nujol): ν(2-C6F4I) at
Synthesis of {NBu4[Tl2{Au(2-C6F4I)2}3]}n (4). To a solution of
NBu4[Au(2-C6F4I)2] (2; 0.148 g, 0.15 mmol) in tetrahydrofuran (15
mL) was added TlPF6 (0.052 g, 0.15 mmol). After 2 h of stirring,
the solution was concentrated under vacuum and toluene added to
precipitate a white solid (TlPF6 and the NBu4PF6), which was
filtered off. Concentration of the solution and addition of dichlo-
romethane (5 mL) led to precipitation of compound 4, which was
isolated as a yellow greenish solid after washing with dichlo-
romethane (3 × 5 mL). Yield: 56%. Anal. Calcd for 4
(C52H36Au3F24I6NTl2): C, 21.60; H, 1.25; N, 0.48. Found: C, 21.77;
H, 1.22; N, 0.54. 1H NMR (75.5 MHz, THF-d8, ppm): δ 3.22 (m,
2H, CH2), 1.65 (m, 2H, CH2), 1.39 (m, 2H, CH2), 0.97 (t, 3H, CH3).
19F NMR (282.4 MHz, THF-d8, ppm): δ -113.4 (dd, 1F, F4,
3J(F4-F3) ) 22.0 Hz, 5J(F4-F1) ) 13.8 Hz), -113.7 (dd, 1F, F1,
3J(F1-F2) ) 32.2 Hz), -157.7 (dd, 1F, F2, 3J(F2-F3) ) 18.9 Hz),
-160.2 (dd, 1F, F3). ES(+): m/z (%) 242 [NBu4]+ (100), 205 [Tl]+
(40). ES(-): m/z (%) 747 [Au(2-C6F4I)2]- (100). FT-IR (Nujol):
ν(2-C6F4I) at 1614, 1588, 1080, and 806 cm-1, ν(NBu4+ C-N st)
1609, 1587, 1076, and 806 cm-1, ν(NBu4+ C-N st) at 880 cm-1
.
at 886 cm-1
.
Synthesis of {NBu4[Tl2{Au(2-C6BrF4)2}3]}n (3). To a solution
of NBu4[Au(2-C6BrF4)2] (1; 0.134 g, 0.15 mmol) in tetrahydrofuran
(15 mL) was added TlPF6 (0.052 g, 0.15 mmol). After 30 min of
stirring, the solution was concentrated under vacuum to ca. 5 mL.
Addition of toluene (15 mL) led to precipitation of TlPF6 and
NBu4PF6, which were separated by filtration. The filtrate was
Synthesis of {NBu4[Tl{Au(2-C6BrF4)2}2]}n (5). Method 1. To
a solution of TlPF6 (0.035 g, 0.1 mmol) in tetrahydrofuran (15 mL)
was added NBu4[Au(2-C6BrF4)2] (1) (0.179 g, 0.2 mmol), and the
solution turned pale yellow. After 45 min of stirring, the solution
was concentrated under vacuum and a green oil appeared. Addition

Anionic Homo- and Heterometallic Gold Complexes
Organometallics, Vol. 27, No. 13, 2008 2979
of isopropyl alcohol (5 mL) led to the precipitation of compound
5, which was isolated as a yellow solid after washing with isopropyl
alcohol (3 × 5 mL). Yield: 85%.
1.87; N, 0.72. Found: C, 24.88; H, 1.91; N, 0.76. ES(+): m/z (%)
242 [NBu4]+ (100), 205 [Tl]+ (20). ES(-): m/z (%) 747 [Au(2-
C6F4I)2]- (100). FT-IR (Nujol): ν(2-C6F4I) at 1642, 1575, 1070,
+
and 804 cm-1, ν(NBu4 C-N st) at 887 cm-1
.
Method 2. To a solution of {NBu4[Tl2{Au(2-C6BrF4)2}3]}n (3;
0.261 g, 0.1 mmol) in tetrahydrofuran (15 mL) was added
NBu4[Au(2-C6BrF4)2] (1; 0.090 g, 0.1 mmol), and the solution
turned pale yellow. After 45 min of stirring, the solvent was partially
evaporated under vacuum and isopropyl alcohol was added to
precipitate compound 5, which was isolated as a yellow solid after
washing with isopropyl alcohol (3 × 5 mL). Yield: 73%. Anal.
Calcd for 5 (C40H36Au2Br4F16NTl): C, 27.41; H, 2.07; N, 0.80.
Crystallography. Crystals were mounted in inert oil on glass
fibers and transferred to the cold gas stream of a Nonius Kappa
CCD diffractometer equipped with an Oxford Instruments low-
temperature attachment. Data were collected using monochromated
Mo KR radiation (λ ) 0.710 73 Å), with scan types ω and φ and
numerical absorption corrections (based on multiple scans). The
structures were solved by direct methods and refined on F2 using
the program SHELXL-97.35 All non-hydrogen atoms were refined
anisotropically. In complex 3 the halogen atoms in ortho positions
of one of the perhalophenyl rings are disordered with a 50%
occupancy in each position (Br(2) and F(6) or F(2) and Br(6)).
Hydrogen atoms were included using a riding model. Further details
of the data collection and refinement are given in Table 4. Selected
bond lengths and angles are collected in Tables 1–3, and crystal
structures of complexes 3-5 are given in Figures 1–5.
1
Found: C, 27.61; H, 2.17; N, 0.87. H NMR (75.5 MHz, THF-d8,
ppm): δ 3.23 (m, 2H, CH2), 1.65 (m, 2H, CH2), 1.39 (m, 2H, CH2),
0.98 (t, 3H, CH3). 19F NMR (282.4 MHz, THF-d8, ppm): δ -113.4
(dd, 1F, F1, 3J(F1-F2) ) 33.8 Hz, 5J(F1-F4) ) 13.5 Hz), -128.2
(dd, 1F, F4, 3J(F4-F3) ) 20.9 Hz), -159.1 (dd, 1F, F2, 3J(F2-F3)
) 20.0 Hz), -161.7 (dd, 1F, F3). ES(+): m/z (%) 242 [NBu4]+
(100), 205 [Tl]+ (50). ES(-): m/z (%) 653 [Au(2-C6BrF4)2]- (100).
FT-IR (Nujol): ν(2-C6BrF4) at 1613, 1595, 1083, and 822 cm-1
,
+
ν(NBu4 C-N st) at 879 cm-1
.
Acknowledgment. This work was supported by the
DGI(MEC)/FEDER (No. CTQ2007-67273-C02-02). M.M.
and T.L. thank the CAR for a grant and a Colabora contract,
respectively. We thank Prof. Mohammad Omary for helpful
discussions.
Synthesis of {NBu4[Tl{Au(2-C6F4I)2}2]}n (6). Method 1. To a
solution of TlPF6 (0.035 g, 0.1 mmol) in tetrahydrofuran (15 mL)
was added NBu4[Au(2-C6F4I)2] (2; 0.198 g, 0.2 mmol). The solution
turned yellow, and a solid started to precipitate. After 2 h of stirring
the precipitation of compound 6 was complete and the complex
was separated as a yellow solid by filtration and washed with
tetrahydrofuran (3 × 5 mL). Yield: 95%.
Supporting Information Available: CIF files giving X-ray
crystallographic data for the structural characterization of complexes
3-5. This material is available free of charge via the Internet at
http://pubs.acs.org.
Method 2. To a solution of {NBu4[Tl2{Au(2-C6F4I)2}3]}n (4;
0.289 g, 0.1 mmol) in tetrahydrofuran (15 mL) was added
NBu4[Au(2-C6F4I2] (2; 0.099 g, 0.1 mmol). The solution im-
mediately turned yellow and a solid started to appear. After 2 h of
stirring to complete the precipitation of 6, the yellow solid was
isolated by filtration and washed with tetrahydrofuran (3 × 5 mL).
Yield: 88%. Anal. Calcd for 6 (C40H36Au2F16I4NTl): C, 24.76; H,
OM8000586
(35) Sheldrick, G. M. SHELXL-97, A Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.