Luminescence and mesogenic properties in crown-ether-isocyanide or carbene gold(I) complexes: Luminescence in solution, in the solid, in the mesophase, and in the isotropic liquid state

Article abstract of DOI:10.1021/ic701831v

A crown ether isocyanide CNR (R = benzo-15-crown-5) has been synthesized by dehydration of the corresponding formamide. Substitution reactions with the appropriate gold(I) precursors afford the luminescent mononuclear derivatives [AuX(CNR)] (X = Cl, C₆F₅, Br, I), [Au(C₆F ₄OCH₂C₆H₄OC_nH _2n+1-p)(CNR)] (n = 4, 8, 10, 12), and [Au(C₆F ₄OCH₂C₆H₂-3,4,5-(OC _nH_2n+1)₃(CNR)] (n = 4, 8, 12). X-ray diffraction studies of [AuCl(CNR)] show the molecules associated in a tetranuclear manner with an antiparallel orientation and gold-gold distances of 3.420 and 3.427 A (Au...Au...Au angles are 121.2°). These tetranuclear units generate infinite zigzag chains through longer Au...Au distances of 3.746 A and weak C-H...O nonclassic interactions. Nucleophilic attack to the coordinated isocyanide in [AuCl(CNR)] by methanol or a primary amine produces the carbene derivatives [AuCl{C((NHR)(OMe)}] and [AuCl{C(NHR′)(NHR)}] (R′ = Me, n-Bu). The ether crown in these complexes is able to coordinate sodium from NaClO₄, affording the corresponding bimetallic complexes (Na/Au = 1:1). The derivatives containing one alkoxy chain are liquid crystals, displaying a smectic C mesophase (for n > 4), whereas the trialkoxy derivatives display unidentified or smectic C mesophases, depending on the alkyl chain length. After complexation of sodium salts, the mesogenic behavior is lost. All of the derivatives are luminescent at room temperature in the solid state with emission maxima in the range 405-550 nm; they emit at 77 K from 410 to 572 nm. Only the ligand and the fluoroaryl complexes emit in solution at room temperature, but all of the compounds are luminescent at 77 K. Very interestingly, some fluoroaryl derivatives with alkoxy chains are luminescent not only in the solid, and in solution, but also in the mesophase, and in the isotropic liquid at moderate temperatures. These are the first metal complexes ever reported to show luminescence in the isotropic liquid state.

Full text of DOI:10.1021/ic701831v

Inorg. Chem. 2008, 47, 3559-3567
Luminescence and Mesogenic Properties in Crown-Ether-Isocyanide or
Carbene Gold(I) Complexes: Luminescence in Solution, in the Solid, in
the Mesophase, and in the Isotropic Liquid State
Javier Arias, Manuel Bardají, and Pablo Espinet*
IU CINQUIMA/Química Inorgánica, Facultad de Ciencias, UniVersidad de Valladolid,
E-47071 Valladolid, Castilla y León, Spain
Received September 17, 2007
A crown ether isocyanide CNR (R ) benzo-15-crown-5) has been synthesized by dehydration of the corresponding
formamide. Substitution reactions with the appropriate gold(I) precursors afford the luminescent mononuclear
derivatives [AuX(CNR)] (X ) Cl, C6F5, Br, I), [Au(C6F4OCH2C6H4OCnH2n+1-p)(CNR)] (n ) 4, 8, 10, 12), and
[Au(C6F4OCH2C6H2-3,4,5-(OCnH2n+1)3(CNR)] (n ) 4, 8, 12). X-ray diffraction studies of [AuCl(CNR)] show the
molecules associated in a tetranuclear manner with an antiparallel orientation and gold-gold distances of 3.420
and 3.427 Å (Au · · · Au · · · Au angles are 121.2°). These tetranuclear units generate infinite zigzag chains through
longer Au · · · Au distances of 3.746 Å and weak C-H · · · O nonclassic interactions. Nucleophilic attack to the
coordinated isocyanide in [AuCl(CNR)] by methanol or a primary amine produces the carbene derivatives
[AuCl{C((NHR)(OMe)}] and [AuCl{C(NHR′)(NHR)}] (R′ ) Me, n-Bu). The ether crown in these complexes is able
to coordinate sodium from NaClO4, affording the corresponding bimetallic complexes (Na/Au ) 1:1). The derivatives
containing one alkoxy chain are liquid crystals, displaying a smectic C mesophase (for n > 4), whereas the trialkoxy
derivatives display unidentified or smectic C mesophases, depending on the alkyl chain length. After complexation
of sodium salts, the mesogenic behavior is lost. All of the derivatives are luminescent at room temperature in the
solid state with emission maxima in the range 405–550 nm; they emit at 77 K from 410 to 572 nm. Only the ligand
and the fluoroaryl complexes emit in solution at room temperature, but all of the compounds are luminescent at 77
K. Very interestingly, some fluoroaryl derivatives with alkoxy chains are luminescent not only in the solid, and in
solution, but also in the mesophase, and in the isotropic liquid at moderate temperatures. These are the first metal
complexes ever reported to show luminescence in the isotropic liquid state.
Introduction
On the other hand, gold(I) displays typically a linear
geometry, which has been very useful to prepare, after
coordination of promesogenic ligands, calamitic molecules
behaving as liquid crystals. In this context, isonitrile ligands
are most suited because of the high thermal stability of their
complexes and the prolongation of the linearity along the
CN bond.4 Many reported isocyanide gold metallomesogens,
which were not checked for luminescence at the time of
preparation, should probably be luminescent in the solid state
and in solution, but in fact the metallomesogens reportedly
photoluminescent in the solid state or in solution are just a
few lanthanide, palladium, or gold complexes.5 A very
different matter is luminescence in the mesophase, and only
very recently, metallomesogens have been reported to display
this property in the liquid crystal state. These are some
The synthesis of closed-shell gold(I) derivatives has attracted
attention in recent years because of the frequent presence of
short gold-gold distances, which have been attributed to
correlation effects reinforced by relativistic effects and elec-
trostatic contributions.1 Many gold(I) compounds, with or
without gold-gold contacts, are luminescent in the visible
region,1a,2 and some of them have been proposed for applica-
tions as sensors or as light-emitting diodes.3
* Corresponding author e-mail: espinet@qi.uva.es.
(1) (a) Pyykkö, P. Angew. Chem., Int. Ed. 2004, 43, 4412. (b) Runeberg,
N.; Schütz, M.; Werner, H. J. J. Chem. Phys. 1999, 110, 7210.
(2) (a) Roundhill, D. M.; Fackler, J. P., Jr. Optoelectronic Properties of
Inorganic Compounds; Plenum Press: New York, 1998. (b) Schmid-
baur, H. Gold Bull. 2000, 33, 3.
10.1021/ic701831v CCC: $40.75  2008 American Chemical Society
Inorganic Chemistry, Vol. 47, No. 9, 2008 3559
Published on Web 03/18/2008

Arias et al.
Scheme 1
lanthanide-, zinc-, or silver-based columnar metallome-
sogens6 and some noncolumnar gold(I) derivatives from our
group.7 No metallomesogen has been reported to luminesce
above the clearing point, in the isotropic liquid state.
A most relevant property of crown ethers is to coordinate
cations, which has been exploited to detect or extract cations,
for ionic transport, or to prepare stationary phases in
chromatography.8 Although metallomesogens combining
transition metals and crown ethers have been recently
reported, very often the crown cavity is occupied by the metal
providing metallomesogenic character, and it is this oc-
cupancy that induces the mesogenic behavior. In these
complexes, the crown is already coordinated, and it is not
possible to further complex an alkali salt. Moreover, the
coordination is typically facilitated by using crowns with
nitrogen or sulfur atoms replacing some oxygen atoms.6,9
Continuing previous studies on new polyfunctional com-
plexes combining suitable fragments,7,10 in this paper, we
report Au(I) complexes containing a crown isocyanide or
its derived carbene ligands. Within the group of complexes
reported we find the following properties: luminescence,
mesogenic behavior, and coordination to alkaline cations.
Most interesting, some complexes behave as liquid crystals
at very moderate temperatures and display luminescence in
solution, in the solid state, in the mesophase, and even in
the isotropic liquid state.
Results and Discussion
Synthesis and Characterization. A crown ether func-
tionalized isocyanide was prepared and used to synthesize
mononuclear gold(I) complexes by substitution of weaker
tetrahydrothiophene (tht) or arsine ligands (Scheme 1).
Nucleophilic attack of the coordinated isocyanide by metha-
nol or by a primary amine afforded gold(I) carbene
complexes.11
(3) (a) Yam, V. W. W.; Chan, C. L.; Li, C. K.; Wong, K. M. C. Coord.
Chem. ReV. 2001, 216–217, 173. (b) Mansour, M. A.; Connick, W. B.;
Lachicotte, R. J.; Gysling, H. J.; Eisenberg, R. J. Am. Chem. Soc.
1998, 120, 1329. (c) Ma, Y.; Che, C. M.; Chao, H. Y.; Zhou, X.;
Chan, W. H.; Shen, J. AdV. Mater. 1999, 11, 852. (d) Fave, C.; Cho,
T. Y.; Hissler, M.; Chen, C. W.; Luh, T. Y.; Wu, C. C.; Réau, R.
J. Am. Chem. Soc. 2003, 125, 9254.
Compounds 1–8 are air-stable solids at room temperature
that were characterized by elemental analysis, IR, and NMR
spectroscopy. The IR spectra of 2–5 show the characteristic
shift upon coordination of ν(CtN), from 2122 cm-1 in the
free ligand 1 to 2218–2229 cm-1. This band disappears in the
carbene complexes 6–8. In the 1H NMR spectra, the crown ether
ligand in the complexes shows a slightly shifted AMX spin
system for the aromatic protons and the methylene resonances
(quite coordination-insensitive). Additionally, the carbene de-
rivative (6) shows two N-H resonances corresponding to the
two possible isomers arising from rotational restriction around
the CdN carbene bond. For 7–8, up to four isomers are possible.
For 7, at least two isomers are observed, while for 8, the broad
signals suggest the presence of several isomers, but no well-
separated resonances are observed.
(4) (a) Espinet, P. Gold Bull. 1999, 32, 127. (b) Benouazzane, M.; Coco,
S.; Espinet, P.; Martín-Alvarez, J. M. J. Mater. Chem. 1995, 5, 441.
(c) Alejos, P.; Coco, S.; Espinet, P. New J. Chem. 1995, 19, 799. (d)
Bayón, R.; Coco, S.; Espinet, P.; Fernández-Mayordomo, C.; Martín-
Alvarez, J. M. Inorg. Chem. 1997, 36, 2329. (e) Benouazzane, M.;
Coco, S.; Espinet, P.; Martín-Alvarez, J. M. J. Mater. Chem. 1999, 9,
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3515. (g) Benouazzane, M.; Coco, S.; Espinet, P.; Martín-Alvarez,
J. M.; Barberá, J. J. Mater. Chem. 2002, 12, 691. (h) Coco, S.;
Fernández-Mayordomo, C.; Falagán, S.; Espinet, P. Inorg. Chim. Acta
2003, 350, 366. (i) Ballesteros, B.; Coco, S.; Espinet, P. Chem. Mater.
2004, 16, 2062. (j) Bartolome´, C.; Carrasco-Rando, M.; Coco, S.;
Cordovilla, C.; Espinet, P.; Martín-Alvarez, J. M. Organometallics
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Skoulios, A.; Weber, P. Chem. Phys. Lett. 1985, 122, 124. Binnemans,
K.; Malykhina, L.; Mironov, V. S.; Haase, W.; Driesen, K.; Van Deun,
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Chem 2001, 2, 680. (c) Nozary, H.; Piguet, C.; Rivera, J. P.; Tissot,
P.; Morgantini, P. Y.; Weber, J.; Bernardinelli, G.; Bünzli, J. C. G.;
Deschenaux, R.; Donnio, R.; Guillon, D. Chem. Mater. 2002, 14, 1075.
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Gessi, A.; Francescangeli, O. Appl. Organomet. Chem. 1999, 13, 565.
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Wendorff, J. H. Angew. Chem., Int. Ed. Engl. 1991, 30, 1375. (b)
Lattermann, G.; Schmidt, S.; Kleppinger, R.; Wendorff, J. H. AdV.
Mater. 1992, 4, 30. (c) Neve, F.; Ghedini, M.; Levelut, A. M.;
Francescangeli, O. Chem. Mater. 1994, 6, 70. (d) Schmidt, S.;
Lattermann, G.; Kleppinger, R.; Wendorff, J. H. Liq. Cryst. 1994, 16,
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Chem. Commun. 2003, 1226. (b) Suárez, S.; Imbert, D.; Gumy, F.;
Piguet, C.; Bünzli, J. C. G. Chem. Mater. 2004, 16, 3257. (c) Cavero,
E.; Uriel, S.; Romero, P.; Serrano, J. L.; Giménez, R. J. Am. Chem.
Soc. 2007, 129, 11608. (d) Barberio, G.; Bellusci, A.; Crispini, A.;
Donnio, B.; Giorgini, L.; Ghedini, M.; La Deda, M.; Pucci, D.; Szerb,
E. I. Chem.sEur. J. 2006, 12, 6738.
(7) Bayón, R.; Coco, S.; Espinet, P. Chem.sEur. J. 2005, 11, 1079.
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C. J. Science 1988, 241, 536. (c) Gokel, G. W. Crown Ethers and
Cryptands; Stoddart, J. F., Ed.; The Royal Society of Chemistry:
Cambridge, U.K., 1991; Monographs in Supramolecular Chemistry
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2004, 104, 2723.
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P.; Laguna, M.; Abad, M. J. Organomet. Chem. 1981, 218, 265. (c)
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Bonati, F.; Minghetti, G. J. Organomet. Chem. 1973, 59, 403.
3560 Inorganic Chemistry, Vol. 47, No. 9, 2008

Crown-Ether-Isocyanide and Carbene Gold(I) Complexes
are within normal ranges for chloro isocyanide gold com-
plexes.12 There are four molecules per unit cell which are
connected by gold-gold bonds: two antiparallel molecules
with a gold-gold interaction at 3.420 Å (Au(1A)-Au(2A)
or Au(1B)-Au(2B)) are connected to a second identical pair
with a Au(1A)-Au(1B) distance of 3.427 Å, giving rise to
a tetranuclear zigzag cluster. Both angles, Au(2A)-Au(1A)-
Au(1B) and Au(1A)-Au(1B)-Au(2B), are 121.2°. The
tetranuclear units are further connected to others, describing
infinite zigzag gold chains, by weak nonclassical C-H · · ·O
bonds (d(H · · ·O) ) 2.702 Å; d(C · · ·O) ) 3.330 Å; C-H· · ·O
angle ) 122.88°) and longer possible gold-gold contacts
at 3.746 Å, with an Au-Au-Au angle of 139°. Although
the zigzag chains in the crystal are packed in such a way
that the crown ether rings would appear to form a channel,
this view is deceptive, as they are about 8.4 Å apart from
each other.
Neutral [AuCl(CNR)] compounds reported in the literature
display diverse arrays of supramolecular structures including
(a) dimers with short gold-gold distances (e.g., 3.063 Å for
R ) (p-toluenesulfonyl)methyl)13 or 3.336 Å for R )
mesityl);14 (b) monodimensional zigzag chains, typically with
one single gold-gold distance longer than the short one for
complex 2 (e.g., 3.637 Å for R ) Me, 3.564 Å for R ) Et,
and 3.547 Å for R ) Pr),12,14 although in other cases, the
chain is formed with a short and a long gold distance as
found for R ) Cy (3.388 and 3.587 Å);15 (c) bidimensional
polymeric sheets, as reported for 1,1′-diisocyanoferrocene
gold complexes, with gold-gold distances of 3.354 and
3.484 Å.16 The arrangement observed here is somewhat
different from all of these.
In view of the successful synthesis of the C6F5 derivative
3, a promesogenic fluorinated aryl ligand containing one or
three alkoxy chains was used, searching for complexes with
liquid crystal behavior (Scheme 2).4f,4i,5e,7
Complexes 9–10 are air-stable white solids at room
temperature. They were readily characterized by (a) consis-
tent elemental analysis; (b) their characteristic coordinated
isocyanide stretching absorption at ca. 2215 cm-1; (c) an
AA′XX′ spin system in the 19F NMR spectra (with the
deceptive appearance of two doublets centered at ca. -118
and -156 ppm) typical of the Au-C6F4 moiety; and (d) 1H
NMR spectra displaying signals corresponding to one or three
alkoxy chains, the crown ether fragment, a benzyl resonance
at ca. 5.10 ppm, and signals for the remaining aromatic
protons, as assigned in the experimental section.
Figure 1. (Top) Structure of one independent molecule of 2, showing
displacement ellipsoids at the 50% probability level and the atom-numbering
scheme. H atoms have been omitted for clarity. (Center) Extended structure
of 2, showing the tetranuclear zigzag cluster (H atoms omitted for clarity;
displacement ellipsoids at the 50% probability level). (Bottom) View
showing the longer distance connections of two tetranuclear zigzag clusters.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for Complex 2
Au(1)-C(1)
1.920(11)
2.261(2)
1.153(12)
1.400(12)
1.330(10)
1.403(12)
176.5(3)
174.8(8)
175.9(9)
120.0(8)
Au(2)-C(16)
1.925(12)
2.261(3)
1.160(13)
1.379(13)
1.355(10)
1.396(12)
177.3(3)
178.9(9)
178.1(11)
120.3(9)
Au(1)-Cl(1)
C(1)-N(1)
Au(2)-Cl(2)
C(16)-N(2)
N(1)-C(2)
N(2)-C(17)
Complexation of 9–10 (for chain length n ) 8) with
NaClO4 was achieved by the addition of sodium perchlorate
in a ratio of 1:1 15-crown-ether/Na (Scheme 3). Sodium was
C(5)-O(1)
C(20)-O(6)
C(5)-C(6)
C(20)-C(21)
C(1)-Au(1)-Cl(1)
N(1)-C(1)-Au(1)
C(1)-N(1)-C(2)
C(3)-C(2)-N(1)
C(16)-Au(2)-Cl(2)
N(2)-C(16)-Au(2)
C(16)-N(2)-C(17)
C(22)-C(17)-N(2)
(12) Bachman, R. E.; Fioritto, M. S.; Fetics, S. K.; Cocker, T. M. J. Am.
Chem. Soc. 2001, 123, 5376.
The structure of complex 2 shown in Figure 1 was
established by X-ray diffraction. Selected bond lengths and
angles are given in Table 1. Complex 2 crystallizes as two
very similar independent molecules in the asymmetric unit,
labeled Au(1) and Au(2) in Table 1. The C-Au-Cl angles
(176.5(3) and 177.3(3)°) confirm a typical linear geometry
around the gold atom. The Au-Cl and Au-C bond lengths
(13) Elbjeirami, O.; Omary, M. A.; Stender, M.; Balch, A. L. Dalton Trans.
2004, 3173.
(14) Schneider, W.; Angermaier, K.; Sladek, A.; Schmidbaur, H. Z.
Naturforsch., B: Chem. Sci 1996, 51, 790.
(15) White-Morris, R. L.; Olmstead, M. M.; Balch, A. L.; Elbjeirami, O.;
Omary, M. A. Inorg. Chem. 2003, 42, 6741.
(16) Siemeling, U.; Rother, D.; Bruhn, C.; Fink, H.; Weidner, T.; Trager,
F.; Rothenberger, A.; Fenske, D.; Priebe, A.; Maurer, J.; Winter, J.
J. Am. Chem. Soc. 2005, 127, 1102.
Inorganic Chemistry, Vol. 47, No. 9, 2008 3561

Arias et al.
Scheme 2
Scheme 3
Table 2. Optical, Thermal, and Thermodynamic Data for Derivatives 9
and 10
c
derivative
n
transitiona
T/°Cb
∆H/kJ mol-1
9a
4
C-C′d
92.9
102.8
(35)
16.4
43.4
93.6
(21.7)
42.9
77.5
(36.9)
2.23
38.1
54.9
(41.6)
1.4
12.62
27.07
C′-I
(I-SmC)e
SmC-gd
C-C′d
0.169c
0.44
37.77
(-0.499)
0.68
42.24
(-1.35)
0.12c
1.08
4.27
(-1.21)
-0.2
9b
9c
8
C′-I
(I-SmC)
10
C-C′d
C′-I
(I-SmC)
SmC-gd
C-C′d
9d
12
4
C′-I
chosen because its radius fits best the 15-crown ether moiety.8
The complexes are brownish solids at room temperature and
were characterized by elemental analysis and IR and NMR
spectroscopy. They are soluble in CDCl3 (where NaClO4 is
(I-SmC)
10a
C-C′d
C′-C′′d
C′′-I
24.5
75.7
(88.1)
10.6
47.3
55
0.0895
39.3
(-0.06)
0.161c
36.44g
(I-M)
1
M-gd
insoluble), and their H NMR spectra show small shifts of
10b
8
C-SmCe-If
I-SmCe
SmC-gd
C-Me-If
I-M
some aromatic protons and splitting of the methylene crown
ether resonances, due to the descent of symmetry upon
sodium coordination. Their IR spectra show several absorp-
tions around 1100 cm-1 (corresponding to the typical splitting
associated with covalently bonded perchlorate, C2V sym-
metry), as well as combination bands originating from the
crown ether moiety, while no changes are observed in the
CN absorption compared to their precursors. The spectral
data, in conjunction with the solubility of the complexes in
CDCl3, suggest tight association of the perchlorate anions
to the cationic complex, including covalent interactions of
two oxygen atoms of the perchlorate group to Na.
Mesogenic Behavior. Complexes 9–10 displayed mono-
tropic or enantiotropic mesophases upon heating from the
solid state or upon cooling from the isotropic liquid. Optical,
thermal, and thermodynamic data, obtained by optical
microscopy under polarized light (POM) and by differential
scanning calorimetry (DSC), are collected in Table 2. The
smectic C (SmC) mesophases were assigned by optical
microscopy.
The derivatives with one alkoxy chain, 9, are monotropic
liquid crystals. Increasing the alkoxy chain length reduces
the melting temperature. As the isotropic liquid is cooled
down, the material becomes very viscous, and the mesophase
appears very slowly at temperatures close to room temper-
ature, while crystallization is only detected for 9a and 9c,
because of supercooling of the mesophase. Only the transi-
tions between the mesophase and isotropic liquid (and glass-
mesophase for 9b) are observed in the subsequent heating
and cooling cycles of derivatives 9b–9d, and for 9a, only
the glass-isotropic liquid transition is seen. The SmC
mesophases show a sanded Schlieren texture with the point
3.4
0.119c
38.17 g
-0.84
-20.34
10ch
12
31.4
17.2
15.2
M-Cd
a C, C′, C′′ ) crystal, I ) isotropic liquid, g, g′ ) glass, M )
unidentified mesophase. b Data for the first heating scan. c For glass
transitions, the value given is the specific heat capacity change, J/g °C.
d Only observed by DSC. e Only observed by POM. f There are two close
consecutive transitions, and the melting point is not sharp. g Combined
h
enthalpies. Measured at 1 K min-1
.
singularities being very small and blurred (Figure 2). Overall,
the use of the fairly bulky and flexible crown ether fragment
in the ligand apparently results in a reduction of intermo-
lecular attractions, producing lower melting points, less-
ordered mesophases, and shorter mesophase ranges than
found for the related derivatives [AuCl(CNR)] (R ) C6H4OCn-
H2n+1-p: enantiotropic SmA mesophases).17
The derivatives 10 with three alkoxy chains behave as
monotropic (10a) or enantiotropic (10b–10c) liquid crystals.
The latter display very viscous mesophases upon heating that
are rapidly mixed with isotropic liquid. As observed for
derivatives 9, the increase of the alkoxy chain length reduces
the melting temperature. Upon cooling, the mesophase
appears very slowly to give an unidentified mesophase (M)
for 10a and 10c and a SmC phase for 10b. As observed for
derivatives 9, the subsequent heating and cooling cycles only
show the glass-mesophase (for 10a and 10b) and the
mesophase-isotropic liquid transitions (for 10a). Only for
10c are the first heating and cooling cycles kept. The SmC
mesophase shows a sanded Schlieren texture similar to that
(17) Coco, S.; Espinet, P.; Falagán, S.; Martín-Alvarez, J. M. New. J. Chem.
1995, 19, 959.
3562 Inorganic Chemistry, Vol. 47, No. 9, 2008

Crown-Ether-Isocyanide and Carbene Gold(I) Complexes
materials takes several hours or even days, which precludes
the observation of any transition phase by DSC or POM.
Thus, the isotropic liquid is metastable at room temperature
for very long periods.
Luminescence Studies. The emission and excitation
spectra of the free ligand and the gold complexes were
determined in the solid state and in CH2Cl2 solution, at 298
and 77 K. The results are summarized in Table 3. For the
complexes displaying low melting points and liquid crystal
behavior, additional variable-temperature luminescence stud-
ies were undertaken, which are discussed later.
All of the derivatives, including the starting crown ether
isocyanide ligand, emit at 77 and 298 K in the solid state
and in solution at 77 K, but only some of the complexes
emit in CH2Cl2 solution at 298 K. In the solid state, the
emission of the complexes containing fluoroaryls (3, 9d, 10c,
11, and 12) is visible by the naked eye under an UV–vis
chromatography lamp at 298 K. The emission range goes
from 405 to 550 nm (449–550 nm for gold derivatives) at
298 K, and from 410 to 572 nm (450–572 nm for gold
derivatives) at 77 K. The low-temperature emission spectra
are more intense and slightly blue- (for 3, 9d, and 11) or
red-shifted (for 1, 2, and 5), while the excitation spectra are
similar with some small blue (for 4 and 9d) or red (for 1)
shifts. In CH2Cl2 solution at 298 K, only the complexes
containing fluoroaryl (3, 9d, 10c, 11, and 12) emit (at 426
and 450 nm), while all of the gold complexes are luminescent
at 77 K in the range 424–515 nm.
When the excitation and emission spectra at 298 K for
each compound (1, 3, 9d, 10c, 11, and 12) are compared
with those observed at any temperature in the solid state,
the energies are very different. The excitation and emission
spectra of the halo derivatives 2, 4, and 5 in solution at 77
K are also quite different from their corresponding solid-
state spectra at any temperature, but curiously almost
identical to those shown at 298 K by the complexes
containing fluoroaryl. Finally, the excitation and emission
spectra of the fluoroaryl derivatives 3, 9d, 10c, 11, and 12
undergo a red shift upon cooling to 77 K and become quite
similar to the corresponding solid-state spectra at that
temperature.
There are many reports on photoluminescent isocyanide
gold(I) derivatives where the emission has been assigned to
an intraligand-localized π-π* orbital with little Au contribu-
tion, as calculated for [AuClCNPh].20 Other cases are
assigned to a metal-to-ligand charge-transfer (MLCT) transi-
tion; for example, the complexes [AuX(CNCy)] (X ) Cl,
Br, I) show excitation maxima around 270 nm and emission
maxima around 620 nm for any X, due to the formation of
exciplexes, as occurs also for [Au(CN)2]-.15 These are also
plausible explanations for the solution spectra at 77 K of
the halo derivatives 2, 4, and 5 and at 298 K for the fluoroaryl
derivatives 3, 9d, 10c, 11, and 12, which display high-energy
excitation spectra and almost the same emission spectra.
However, the solid-state emission spectra of the complexes
containing fluoroaryls, which are also coincident with their
Figure 2. Polarized optical microscopic image of the SmC sanded Schlieren
texture (100×) observed for 9c at room temperature.
observed for 9. Compound 10c shows a texture different from
that of 10b. In related complexes, the change in molecular
aspect (from distorted rodlike to semidiscotic) associated with
the introduction of two additional alkoxy chains leads to
compounds exhibiting columnar mesophases.18,4e In the case
of 10c, the texture observed is ill-defined, and small angle
X-ray diffraction studies were unsuccessful because of
the short mesophase range and crystallization during expo-
sure to X-rays, so unambiguous mesophase assignment is
not possible. These results show that again the presence of
the crown ether fragment in the complexes reported here
worsens the liquid crystal behavior.
Often, the complexation of alkaline cations with organic
liquid crystals leads to more complicated mesophases
(frequently, calamitic becomes columnar) depending on the
cation and the counteranion, although decreases of me-
sophase stability or a loss of the mesogenic behavior have
been reported as well.19 It was also reported that the addition
of sodium salts to ether crown imine orthopalladated me-
sogens leads to the loss of liquid crystal properties.10 In the
cases discussed here, 11 shows a lower melting point (46.2
°C, 3.60 kJ/mol) than 9b, and the mesogenic behavior on
cooling is lost. The trialkoxy derivative 12 gives, upon
melting, a very viscous nonmesomorphic material. Upon
cooling from the isotropic liquid, crystallization of these
(18) Coco, S.; Espinet, P.; Martín-Alvarez, J. M.; Levelut, A. M. J. Mater.
Chem. 1997, 7, 19.
(19) (a) He, G. X.; Wada, F.; Kikukawa, K.; Shinkai, S.; Matsuda, T. J.
Org. Chem. 1990, 55, 541. (b) Johansson, G.; Percec, V.; Ungar, G.;
Abramic, D. J. Chem. Soc., Perkin Trans. 1 1994, 447. (c) Percec,
V.; Johansson, G.; Ungar, G.; Zhou, J. P. J. Am. Chem. Soc. 1996,
118, 9855. (d) Goodby, J. W.; Mehl, G. H.; Saez, I. M.; Tuffin, R. P.;
Mackenzie, G.; Auzély-Velty, R.; Benvegnu, T.; Plusquellec, D. Chem.
Commun. 1998, 2057. (e) Schröter, J. A.; Tschierske, C.; Wittenberg,
M.; Wendorff, J. H. Angew. Chem., Int. Ed. 1997, 36, 1119. (f)
Leblanc, K.; Berdagué, P.; Rault, J.; Bayle, P. P.; Judeinstein, P. Chem.
Commun. 2000, 1291. (g) Schultz, A.; Laschat, S.; Saipa, A.;
Gießelmann, F.; Nimtz, M.; Schulte, J. L.; Baro, A.; Miehlich, B. AdV.
Funct. Mater. 2004, 14, 163. (h) Steinke, N.; Frey, W.; Baro, A.;
Laschat, S.; Drees, C.; Nimtz, M.; Hägele, C.; Giesselmann, F.
Chem.sEur. J. 2005, 12, 1026.
(20) Gagnon, J.; Drouin, M.; Harvey, P. D. Inorg. Chem. 2001, 40, 6052.
Inorganic Chemistry, Vol. 47, No. 9, 2008 3563

Arias et al.
Table 3. Excitation and Emission Data (in nm) in the Solid State and in CH2Cl2 Solution for the Isocyanide Ligand 1, the Isocyanide Derivatives 2–5
and 9–12, and the Carbene Derivatives 6–8
solid
298 K
solid
77 K
CH2Cl2
298 K
CH2Cl2
77 K
compd.
λexc
λemis
λexc
λemis
λexc
λemis
λexc
λemis
1
2
3
322
324
354
405
327sh, 342
357 (331)b
410, 438sh
446, 474a
450sh, 516
(450sh, 497)b
440sh, 460, 515sh
572
247,a 281 317
216, 235,a 249
250–315
311
424, 445
436, 462,a 485 321
520
250–320
427sh, 450 312sh, 356 (329)b 506 (429,
454sh, 483)b
425, 447
425, 447
4
5
352
449, 486
550
325
250–310
250–330
360, 396,
412,a 435
362
334
336
356, 401, 411a
6
7
8
9d
518
454
460
357
320
511
445
445
492 (431sh,
455, 485sh)b
450, 470
357
296
296
515
434
434
322
364, 380sh 511
353 (329)b
260–305
426sh, 445 355 (329)b
497 (424,
449, 482)b
425, 450sh, 481
511 (425sh, 498)b
10c
11
342
457
495
345
250–310
250–310
426, 445
411sh, 433 293, 388a
(293, 363a)b
410sh, 433 359 (380)b
344
293, 344a
294, 346a (294, 328)b 435sh, 486
(435sh, 467)b
293, 352a (295, 329)b 435sh, 488
(435sh, 464)b
12
289, 346a
491
250–305
423sh, 488 (513)b
a Most intense peak. b In parentheses: the second excitation or emission spectrum with less intensity.
low-temperature emission spectra, are different and suggest
that the fragment C6F5 might be involved in some molecular
transitions; besides that, a second less-intense spectral pattern
can be observed for these complexes, showing that the
MLCT transitions are still occurring in the solid state and at
77 K, although with much less intensity than the fluoroaryl
related transitions. The coordination of NaClO4 does not
change significantly the spectra of the parent compounds,
except for the trialkoxy derivative in the solid state. In
summary, it seems that the spectra of the fluoroaryl deriva-
tives contain several emissions (centered around 425, 450,
485, and 515 nm) related to different but close excitations,
which can be tentatively assigned to MLCT (high-energy,
less intensity) and LLCT (low-energy, more intensity)
transitions. This explains why the emission maxima observed
depend on the excitation frequency used in these spectra.
On the other hand, the photoluminescence observed for
the halo derivatives 2, 4, and 5 in the solid state could be
explained by association modes in the ground state due to
the presence of Au· · · Au interactions (for instance, zigzag
chains for 2),21 although the existence of different associa-
tions in the excited state (exciplexes) has also been proposed
in related complexes.13
Finally, the N,N-carbene derivatives 7–8 emit in the solid
state around 455 nm, while the N,O-carbene derivative 6
emits at 518 nm; lowering the temperature only produces a
small blue shift. In solution, the carbene derivatives (which
only emit at 77 K) display spectra close to those obtained in
the solid state at 77 K. The luminescence of related
N-heterocyclic carbene gold(I) complexes has been assigned
to ligand-centered transitions.22 In our case, the fact that the
excitation and emission spectra are similar in solution and
in the solid state, and there is a clear difference between the
Figure 3. Emission spectrum of 9d on heating at 25 (highest intensity),
35, 45, 55, 65, and 75 °C with λexc ) 360 nm. Emission intensity in arbitrary
units.
N,N- and the N,O-carbenes, strongly suggests that the
luminescence should be mainly related to a ligand-centered
transition, modified by the gold fragment.
Complexes 9d and 10c, which display different thermal
mesomorphic behavior, were chosen for variable-temperature
monitoring of luminescence. The emission spectra of 9d were
recorded from 25 to 75 °C (heating at 10 °C/min; see
Experimental Section), and a plot of the spectral variation
with temperature is shown in Figure 3. The intensity
decreases when the temperature increases, but the overall
profile of the spectrum is maintained even beyond the
clearing transition to the isotropic liquid state (at 54.9 °C).
Around 75 °C, the emission has fully disappeared. Upon
cooling, including the transition to the liquid crystalline state
at 41.6 °C, the emission is recovered. Therefore the solid-
state emission persists in the liquid crystalline and isotropic
liquid states, although with less intensity.
The emission spectra of 10c versus temperature (heating
at 1 °C/min) similarly show a decrease of intensity upon
heating, but in this case, the shape of the spectrum changes
(Figure 4): a shoulder at ca. 510 nm becomes visible from
the starting broad emission at high temperatures, as if it had
been always there overlapped by the other more intense
bands. Above 39 °C, the emission maximum appears red-
shifted because the intensity of the shoulder has a higher
contribution. At 43 °C, the emission is already centered at
510 nm (remember that the melting point is 31.4 °C, but it
is quite ill-defined and solid, liquid crystal, and liquid
(21) (a) Humphrey, S. M.; Mack, H. G.; Redshaw, C.; Elsegood, M. R. J.;
Young, K. J. H.; Mayerb, H. A.; Kaska, W. C. Dalton Trans. 2005,
439. (b) White-Morris, R. L.; Stender, M.; Tinti, D. S.; Balch, A. L.;
Rios, D.; Attar, S. Inorg. Chem. 2003, 42, 3237.
(22) (a) Zhou, Y.; Chen, W. Organometallics 2007, 26, 2742. (b) Catalano,
V. J.; Malwitz, M. A.; Etogo, A. O. Inorg. Chem. 2004, 43, 5714.
3564 Inorganic Chemistry, Vol. 47, No. 9, 2008

Crown-Ether-Isocyanide and Carbene Gold(I) Complexes
sodium adducts. The fluoroaryl derivatives with alkoxy
chains behave as liquid crystals with fairly low melting and
clearing points and are luminescent in solution, in the solid,
in the mesophase, and in the isotropic liquid at moderate
temperatures.
Experimental Section
Emission and excitation spectra were measured at 298 and 77 K
in the solid state as finely pulverized KBr mixtures, in deoxygenated
CH2Cl2 solutions in quartz tubes, or in the mesophase by means of
a remote fiber optic accessory (and the Mettler FP-82HT hot stage)
with a Perkin-Elmer LS-55 spectrofluorometer. Other technical
details were as previously reported.10 4-Aminobenzo-15-crown-5
(Aldrich) was used as received, and literature methods were used
to prepare [AuX(tht)] (X ) Cl,23 C6F5),24 [AuX(AsPh3)] (X ) Br,
I),25 and HC6F4OCH2C6H4OCnH2n+1-p and HC6F4OCH2C6H2-3,4,5-
(OCnH2n+1)3.26 Only example procedures and IR and NMR data
for n ) 8 are described here, as the syntheses and the IR and NMR
data were similar for the rest of the compounds. Yields and
analytical data are given for all of the compounds. In the 19F NMR
spectra, Fo refers to ortho with respect to the Au substituent.
Figure 4. Emission spectrum of 10c upon cooling from 70 to 30 °C (5 °C
steps) with λexc ) 340 nm (emission intensity in au). The last two more-
intense spectra are at 25 °C (30 min and 1 h later).
apparently coexist up to 42 °C; Table 2), and around 70 °C,
the emission disappears. Upon cooling from 70 to 30 °C (5
°C/min), the emission intensity is recovered and keeps
centered at 510 nm due to hysteresis. About 30 min later,
having reached the temperature of 25 °C, partial crystalliza-
tion occurs (seen by POM) and the most intense emission at
450 nm is recovered. It seems reasonable to assign the intense
emission at 450 nm to the solid state, while a second less-
intense emission at 510 nm (displayed by the solid, liquid,
and liquid crystal states) is the only one surviving in the
isotropic liquid state.
Extraction Experiments. Measurements on the extraction
ability of a sodium salt (picrate) from aqueous solutions were
carried out for selected compounds. The extraction efficiency
is low (ranging from 2 to 12%) and decreases in the order
[AuCl(CNR)] > CNR > [Au(CNR)(C6F4OCH2C6H4OC8H17-
p] > [Au(C6F5)(CNR)]. The crown ether isocyanide ligand
is not a good extractor, but its ability is similar to that found
for crown ether imines under the same conditions (7% in 40
min). Coordination to the Au-Cl fragment increases slightly
the extraction power, but the coordination to Au-fluoroaryl
diminishes it. This effect is opposite that of the coordination
of a crown ether imine to palladium, which improved
dramatically the extraction efficiency (up to 86% in 12
min!).10 Due to the poor extracting properties observed, no
further extraction experiments were undertaken.
Synthesis of the Formamide R-NHCHO and the Isocyanide
R-NC (1) (R ) Benzo-15-crown-5). R-NHCHO and R-NC (1)
were prepared by adapting the general method of Ugi et al.27 Yield
of R-NHCHO: 1.075 g (98%). Anal. Calcd (%): C, 57.87; H, 6.80;
N, 4.50. Found: C, 57.89; H, 6.41; N, 4.55. 1H NMR: 3.74 (s, 8H,
O-CH2-CH2-O), 3.89 (m, 4H, Ph-O-CH2-CH2-O), 4.10 (m, 4H, Ph-
O-CH2-CH2-O). Cis isomer (59%): 6.76 (d, J(HH) ) 8.6 Hz, 1H,
Ph), 6.87 (dd, J(HH) ) 8.6 and 2.2 Hz, 1H, Ph), 7.29 (d, J(HH) )
2.2 Hz, 1H, Ph), 7.73 (brs, 1H, NH), 8.30 (d, J(HH) ) 1.3 Hz, 1H,
CHO). Trans isomer (41%): 6.59 (d, J(HH) ) 2.2 Hz, 1H, Ph),
6.63 (dd, J(HH) ) 8.5 and 2.2 Hz, 1H, Ph), 6.82 (d, J(HH) ) 8.5
Hz, 1H, Ph), 7.90 (d, J(HH) ) 11.2 Hz, 1H, NH), 8.51 (d, 1H,
CHO). Yield of 1: 1.236 g (87%). Anal. Calcd (%): C, 61.42; H,
1
6.53; N, 4.78. Found: C, 61.32; H, 6.31; N, 5.39. H NMR: 3.75
(s, 8H, O-CH2-CH2-O), 3.90 (m, 4H, Ph-O-CH2-CH2-O), 4.11 (t,
4H, J(HH) ) 4.4 Hz, Ph-O-CH2-CH2-O), 6.77 (d, J(HH) ) 8.3
Hz, 1H, Ph), 6.84 (d, J(HH) ) 2.2 Hz, 1H, Ph), 6.95 (dd, J(HH)
) 8.3 and 2.2 Hz, 1H, Ph). IR (CH2Cl2): 2122 ν(CtN) cm-1
.
[AuX(CNR)] (R ) Benzo-15-crown-5; X ) Cl (2), C6F5
(3), Br (4), I (5)). To a dichloromethane solution (20 mL) of
[AuXL] (0.1 mmol; L ) tht; X ) Cl, 32 mg; C6F5, 45 mg; L )
AsPh3; X ) Br, 58 mg; I, 70 mg)28 was added the stoichiometric
amount of the isocyanide 1 (29 mg, 0.1 mmol). The solution was
stirred for about 1 h and concentrated to ca. 2 mL. The addition of
diethyl ether (20 mL) afforded complexes 2–5 as white or yellow
(5) solids, which were washed with diethyl ether (2 × 5 mL). Yield
of 2: 47 mg, 89%. Anal. Calcd (%): C, 38.37; H, 2.91; N, 2.13.
Found: C, 38.18; H, 2.58; N, 1.75. 1H NMR: 3.76 (s, 8H, O-CH2-
CH2-O), 3.93 (m, 4H, Ph-O-CH2-CH2-O), 4.16 (m, 4H, Ph-O-CH2-
CH2-O), 6.87 (d, J(HH) ) 8.6 Hz, 1H, Ph), 6.97 (d, J(HH) ) 2.2
Hz, 1H, Ph), 7.14 (dd, J(HH) ) 8.6 and 2.4 Hz, 1H, Ph). IR
(CH2Cl2): 2221 ν(CtN) cm-1. Yield of 3: 41 mg, 63%. Anal. Calcd
(%): C, 34,27; H, 3.64; N, 2.66. Found: C, 33.96; H, 3.26; N, 2.65.
Conclusions
A crown ether functionalized isocyanide, CNR, proves to
be an excellent ligand toward gold(I) and allows for the
preparation of a variety of neutral [AuX(CNR)] derivatives.
The X-ray diffraction structure of [AuCl(CNR)] shows the
molecules associated by aurophilic interactions in tetranuclear
units, which further organize in a zigzag chain through
possible longer-distance interactions between the end gold
atoms of these units, combined with weak nonclassical
C-H · · · O bonds. Nucleophilic attack to the coordinated
isocyanide by methanol or primary amines affords carbene
derivatives. The complexes show photoluminescence in the
solid state with emission maxima in the range 449–550 nm
(450–572 nm at 77 K) and in CH2Cl2 solutions from 426 to
450 nm (424–515 nm at 77 K). These derivatives can further
coordinate alkaline cations, as observed by changes in the
NMR spectra, extraction experiments, and isolation of the
(23) Usón, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85.
(24) Usón, R.; Laguna, A.; Vicente, J. Chem. Commun. 1976, 353.
(25) McAuliff, C. A.; Parish, R. V.; Randal, P. D. J. Chem. Soc., Dalton
Trans. 1979, 1730.
(26) Mitsunobu, O. Synthesis 1981, 1, 1.
(27) Weber, W. P.; Gokel, G. W.; Ugi, I. K. Angew. Chem., Int. Ed. Engl.
1972, 11, 530.
(28) Schmidbaur, H.; Wohlleben, A.; Wagner, F.; Orama, O.; Huttner, G.
Chem. Ber. 1977, 110, 1748.
Inorganic Chemistry, Vol. 47, No. 9, 2008 3565

Arias et al.
1H NMR: 3.75 (s, 8H, O-CH2-CH2-O), 3.91 (m, 4H, Ph-O-CH2-
CH2-O), 4.15 (m, 4H, Ph-O-CH2-CH2-O), 6.86 (d, J(HH) ) 8.6
Hz, 1H, Ph), 7.0 (d, J(HH) ) 2.4 Hz, 1H, Ph), 7.14 (dd, J(HH) )
8.4 and 2.4 Hz, 1H, Ph). 19F NMR: -116.42 (m, 2F, Fo), -157.97
Table 4. Details of Crystal Data and Structure Refinement for Complex 2
compound
2
empirical formula
fw
C15H19AuClNO5
525.73
(m, 1F, Fp), -162.84 (m, 2F, Fm). IR (CH2Cl2): 2216 ν(CtN) cm-1
.
temp (K)
296(2)
wavelength (Å)
cryst syst
space group
unit cell dim.: a (Å)
b (Å)
0.71073
Yield of 4: 42 mg, 74%. Anal. Calcd (%): C, 31.59; H, 3.35; N,
triclinic
1
2.46. Found: C, 31.57; H, 3.11; N, 2.76. H NMR: 3.76 (s, 8H,
j
P1
O-CH2-CH2-O), 3.93 (m, 4H, Ph-O-CH2-CH2-O), 4.16 (m, 4H, Ph-
O-CH2-CH2-O), 6.86 (d, J(HH) ) 8.8 Hz, 1H, Ph), 6.96 (d, J(HH)
) 2.2 Hz, 1H, Ph), 7.14 (dd, J(HH) ) 8.8 and 2.2 Hz, 1H, Ph). IR
(CH2Cl2): 2229 ν(CtN) cm-1. Yield of 5: 46 mg, 45%. Anal. Calcd
(%): C, 29.19; H, 3.1; N, 2.27. Found: C, 29.32; H, 2.83; N, 2.12.
1H NMR: 3.76 (s, 8H, O-CH2-CH2-O), 3.93 (m, 4H, Ph-O-CH2-
CH2-O), 4.16 (m, 4H, Ph-O-CH2-CH2-O), 6.86 (d, J(HH) ) 10.5
Hz, 1H, Ph), 6.96 (d, J(HH) ) 2.6 Hz, 1H, Ph), 7.13 (dd, J(HH)
8.4334(15)
9.4916(16)
21.699(4)
84.300(3)
79.043(3)
88.603(3)
1696.8(5)
4
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
vol. (Å3)
Z
density (calcd) (Mg/m3)
2.058
8.850
1008
abs coeff (mm-1
F(000)
)
) 10.5 and 2.6 Hz, 1H, Ph). IR (CH2Cl2): 2218 ν(CtN) cm-1
.
[AuCl{C(NHR)(OMe)}] (6) (R ) Benzo-15-crown-5). A
methanol suspension (20 mL) of [AuCl(CNR)] (0.2 g, 0.38 mmol)
in a Schlenk flask protected from light was refluxed for 24 h. The
mixture was cooled, and the unreacted derivative was filtered. The
clear solution was concentrated, diethyl ether added, and the mixture
evaporated to dryness to afford derivative 6 as a brownish solid.
Yield: 112 mg, 53%. Anal. Calcd (%): C, 34.45; H, 4.16; N, 2.51.
Found: C, 34.68; H, 4.15; N, 2.42. 1H NMR: 3.76 (s, 16H, O-CH2-
CH2-O), 3.90 (s, 8H, Ph-O-CH2-CH2-O), 4.10 (s, 8H, Ph-O-CH2-
CH2-O). There are two isomers at ca. 2.5:1 molar ratio. Isomer a:
4.24 (s, MeO), 6.74 (d, J(HH) ) 8.5 Hz, Ph), 7.01 (dd, J(HH) )
8.5 and 2.4 Hz, Ph), 7.17 (d, J(HH) ) 2.4 Hz, Ph), 10.58 (brs,
NH-Ph). Isomer b: 4.26 (s, MeO), 6.78 (d, J(HH) ) 8.6 Hz, Ph),
6.93 (d, J(HH) ) 2.4 Hz, Ph), 7.17 (dd, J(HH) ) 8.6 and 2.4 Hz,
Ph), 10.53 (brs, NH-Ph).
[AuCl{C(NHMe)(NHR)}] (7) (R ) Benzo-15-crown-5). To a
dichloromethane solution (20 mL) of [AuCl(CNR)] (2; 0.256 g,
0.48 mmol) in a Schlenk flask was added NH2Me (84 µL, 0.97
mmol). The solution was stirred protected from light until the
infrared absorption of the isocyanide disappeared (around 30 min).
Then, it was filtered through kiesselgur (some gold decomposition),
concentrated, and precipitated by the addition of diethyl ether to
give a derivative, 7, as a white solid. Yield: 163 mg, 60%. Anal.
Calcd (%): C, 34.51; H, 4.34; N, 5.03. Found: C, 34.52; H, 4.19;
N, 5.04. 1H NMR: 3.74–4.12 (m, 16H, CH2-O), 6.65 (d, J(HH) )
8.5 Hz, 1H, Ph), 6.74 (dd, J(HH) ) 8.5 and 1.9 Hz, 1H, Ph), 6.81
(d, J(HH) ) 1.9 Hz, 1H, Ph), 9.02 (brs, 1H, NH-Ph). There are
two isomers: 3.20 (s, MeN) and 7.99 (brs, NH-Me), 3.21 (s, MeN)
and 8.00 (brs, NH-Me).
cryst habit
cryst size (mm)
Θ range for data colln
index ranges
reflns collected
ind. reflns
max. and min. trans.
data/restraints/params
GOF on F2
plate
0.39 × 0.17 × 0.04
0.96 to 23.30°
-9 e h e 7, -10 e k e 9, -24 e l e 23
7956
4878 [R(int) ) 0.0393]
1.0000 and 0.3439
4878/0/415
1.005
final R indices [I > 2σ(I)] R1 ) 0.0434, wR2 ) 0.1185
R indices (all data)
R1 ) 0.0531, wR2 ) 0.1312
) 1.307 and -2.297
larg. diff. peak hole (e.Å-3
isocyanide 1 (0.1003 g; 0.342 mmol) was added and the reaction stirred
for 30 min. Then, the solution was evaporated to dryness and the
residue recrystallized from ethanol at -18 °C to obtain derivatives
9–10 as white solids. Yield of 9a: 81 mg, 29%. Anal. Calcd (%): C,
47.01; H, 4.19; N, 1.71. Found: C, 47.21; H, 3.83; N, 1.64. Yield of
9b: 155 mg, 52%. Anal. Calcd (%): C, 49.49; H, 4.85; N, 1.60. Found:
C, 49.41; H, 4.82; N, 1.53. Yield of 9c: 116 mg, 18%. Anal. Calcd
(%): C, 50.62; H, 5.14; N, 1.55. Found: C, 50.98; H, 5.14; N, 1.48.
Yield of 9d: 121 mg, 38%. Anal. Calcd (%): C, 51.67; H, 5.42; N,
1.51. Found: C, 51.54; H, 5.36; N, 1.42. Yield of 10a: 154 mg, 47%.
Anal. Calcd (%): C, 49.95; H, 5.24; N, 1.46. Found: C, 49.68; H,
5.20; N, 1.24. Yield of 10b: 162 mg, 42%. Anal. Calcd (%): C, 55.27;
H, 6.60; N, 1.24. Found: C, 55.39; H, 6.36; N, 1.30. Yield of 10c: 53
mg, 12%. Anal. Calcd (%): C, 59.20; H, 7.61; N, 1.08. Found: C,
1
59.37; H, 7.62; N, 1.04. H NMR of 9b: 0.95–1.81 (m, 15H, CH3-
CH2-C), 3.76 (m, 8H, O-CH2-CH2-O), 3.91–3.98 (m, 6H, Ph-O-CH2-
CH2-O + C-CH2-CH2-O), 4.16 (m, 4H, Ph-O-CH2-CH2-O), 5.10 (s,
2H, Ph-CH2-O-Ph), 6.86 (d, J(HH) ) 8.5 Hz, 1H, Ph-crown), 6.87
(d, 2H, J(HH) ) 8.6 Hz, Ph), 6.96 (d, J(HH) ) 2.2 Hz, 1H, Ph-crown),
7.13 (dd, J(HH) ) 8.5 and 2.2 Hz, 1H, Ph-crown), 7.34 (d, 2H, J(HH)
) 8.6 Hz, Ph). 19F NMR: -118.1 (m, N ) 18.1 Hz, Fo), -156.4 (m,
[AuCl{C(NHnBu)(NHR)}] (8) (R ) Benzo-15-crown-5). The
preparation of 8 was the same as for 7, but with NH2Bu in place
of NH2Me. Yield: 38 mg, 16%. Anal. Calcd (%): C, 38.11; H, 5.05;
N, 4.68. Found: C, 37.76; H, 4.77; N, 4.79. 1H NMR: 0.92 (t, J(HH)
) 7.0 Hz, 3H, CH3), 1.26–1.78 (m, 4H, CH2-C), 3.75–4.11 (m,
18H, CH2-O + CH2-N), 6.55–6.91 (m, 3H, Ph), 8.59 (brs, 1H, NH-
CH2), 10.11 (brs, 1H, NH-Ph).
N ) 18.1 Hz, Fm). IR (CH2Cl2): 2215 ν(CtN) cm-1. H NMR of
1
10b: 0.86–1.81 (m, 45H, CH3-CH2-C), 3.76 (s, 8H, O-CH2-CH2-O),
3.92–3.99 (m, 10H, Ph-O-CH2-CH2-O + C-CH2-CH2-O), 4.15 (m,
4H, Ph-O-CH2-CH2-O), 5.08 (s, 2H, Ph-CH2-O-Ph), 6.64 (s, 2H, Ph),
6.87 (d, J(HH) ) 8.8 Hz, 1H, Ph-crown), 6.97 (d, J(HH) ) 2.2 Hz,
2H, Ph-crown), 7.14 (dd, 2H, J(HH) ) 8.8 and 2.2 Hz, Ph-crown).
19F NMR: -118.0 (m, N ) 18.1 Hz, Fo), -156.4 (m, N ) 18.1 Hz,
[Au(C6F4OCH2C6H4OCnH2n+1-p)(CNR)] (n ) 4 (9a), 8 (9b),
10 (9c), 12 (9d)) and [Au(C6F4OCH2C6H2-3,4,5-(OCnH2n+1)3-
(CNR)] (n ) 4 (10a), 8 (10b), 12 (10c); R ) benzo-15-crown-5).
A solution of nBuLi in hexane (0.214 mL, 0.342 mmol) was added to
a solution of the corresponding tetrafluoro derivative (0.342 mmol;
HC6F4OCH2C6H4OCnH2n+1-p or HC6F4OCH2C6H2-3,4,5-(OCnH2n+1)3)
in dried diethyl ether at -78 °C under nitrogen. After the reaction
was stirred for 1 h at -50 °C, [AuCl(tht)] (0.1096 g; 0.342 mmol)
was added at -78 °C, and the reaction mixture was slowly brought to
room temperature. A drop of water was added, and the solution was
filtered in the air through anhydrous MgSO4 and kiesselgur. The
Fm). IR (CH2Cl2): 2215 ν(CtN) cm-1
.
General Procedure for Complexation with NaClO4. Caution!
Perchlorate salts of metal complexes with organic ligands are
potentially explosiVe; howeVer, in this case, the perchlorate anion
is not bonded to Au and is not expected to be problematic. To an
acetonitrile (for derivative 9b) or acetonitrile-dichloromethane
solution (for complex 10b) was added the stoichiometric amount
of NaClO4. The resulting clear solution was stirred for 10 min and
3566 Inorganic Chemistry, Vol. 47, No. 9, 2008

Crown-Ether-Isocyanide and Carbene Gold(I) Complexes
then concentrated to dryness to give a brownish solid. Yield of 11:
SADABS).31 The structure was refined anisotropically on F2.32 All
non-hydrogen atomic positions were located in difference Fourier
maps and refined anisotropically. The hydrogen atoms were placed
in their geometrically generated positions.
Extraction Experiments. To a dichloromethane solution (10
mL) of the extracting gold compound (5 × 10-4 M) was added an
aqueous solution of sodium picrate (10 mL, 5 × 10-5 M) prepared
in situ by mixing solutions of picric acid and sodium hydroxide.
The mixture was vigorously stirred, and samples were taken every
5 min to monitor the diminution of sodium picrate concentration
in the aqueous phase by UV–vis spectroscopy (λ ) 356 nm), until
successive determinations showed no variation. This was taken as
indication that equilibrium had been reached.
43 mg, 70%. Anal. Calcd (%): C, 43.41; H, 4.25; N, 1.41. Found:
1
C, 43.55; H, 4.13; N, 1.51. H NMR: 0.95–1.81 (m, 15H, CH3-
CH2-C), 3.75–3.80 (m, 8H, O-CH2-CH2-O), 3.91–3.98 (m, 6H, Ph-
O-CH2-CH2-O + C-CH2-CH2-O), 4.27 (m, 4H, Ph-O-CH2-CH2-
O), 5.10 (s, 2H, Ph-CH2-O-Ph), 6.86 (d, J(HH) ) 8.5 Hz, 1H, Ph-
crown), 6.97 (d, 2H, J(HH) ) 8.6 Hz, Ph), 7.08 (d, J(HH) ) 2.2
Hz, 1H, Ph-crown), 7.18 (dd, J(HH) ) 8.5 and 2.2 Hz, 1H, Ph-
crown), 7.34 (d, 2H, J(HH) ) 8.6 Hz, Ph). 19F NMR: -117.8 (m,
N ) 18.1 Hz, Fo), -156.4 (m, N ) 18.1 Hz, Fm). IR (CH2Cl2):
-
2215 ν(CtN) cm-1. IR (Nujol): 2213 ν(CtN), 1080, 623 ν(ClO4
)
cm-1. Yield of 12: 68 mg, 67%. Anal. Calcd (%): C, 49.86; H,
5.95; N, 1.12. Found: C, 50.40; H, 5.52; N, 0.77. 1H NMR:
0.86–1.81 (m, 45H, CH3-CH2-C), 3.74–3.79 (m, 8H, O-CH2-CH2-
O), 3.94–3.99 (m, 10H, Ph-O-CH2-CH2-O + C-CH2-CH2-O), 4.27
(m, 4H, Ph-O-CH2-CH2-O), 5.07 (s, 2H, Ph-CH2-O-Ph), 6.64 (s,
2H, Ph), 6.98 (d, J(HH) ) 8.8 Hz, 1H, Ph-crown), 7.10 (d, J(HH)
) 2.2 Hz, 2H, Ph-crown), 7.20 (dd, 2H, J(HH) ) 8.8 and 2.2 Hz,
Ph-crown). 19F NMR: -117.7 (m, N ) 18.1 Hz, Fo), -156.4 (m,
N ) 18.1 Hz, Fm). IR (CH2Cl2): 2215 ν(CtN) cm-1. IR (Nujol):
Acknowledgment. We thank the Spanish Comisión In-
terministerial de Ciencia y Tecnología (Project CTQ2005-
08729) and the Junta de Castilla y León (Project VA099A05)
for financial support, and M. Moraleja and V. Valderrey for
experimental assistance. J.A. thanks the Ministerio de
Edución y Ciencia (Spain) for a grant.
2213 ν(CtN), 1080, 623 ν(ClO4-) cm-1
.
Crystal Structure Determination of 2. The crystal was mounted
on a glass fiber and transferred to the Bruker SMART CCD
diffractometer. Crystal data and details of data collection and
structure refinement are given in Table 4. Cell parameters were
retrieved using SMART29 software and refined with SAINT30 on
all observed reflections. Data reduction was performed with the
SAINT software and corrected for Lorentz and polarization effects.
Absorption corrections were based on multiple scans (program
Supporting Information Available: A Crystallographic Informa-
tion File, containing structural data for 2, is provided. This material is
available free of charge via the Internet at http://pubs.acs.org.
IC701831V
(30) SAINT V6.02, integration software; Bruker Analytical X-ray Instru-
ments Inc.: Madison, WI, 1999.
(31) Sheldrick, G. M. SADABS: A program for absorption correction with
the Siemens SMART system; University of Göttingen: Göttingen,
Germany, 1996.
(29) SMART V5.051, software for the CCD Detector System; Bruker
(32) SHELXTL program system Version 5.1; Bruker Analytical X-ray
Instruments Inc.: Madison, WI, 1998.
Analytical X-ray Instruments Inc.: Madison, WI, 1998.
Inorganic Chemistry, Vol. 47, No. 9, 2008 3567