Auration of Thiophene and Furan: Structures of the 2-Mono- and 2,2-Diaurated Products

Article abstract of DOI:10.1021/om030575f

Thiophene undergoes electrophilic substitution by (triphenylphosphine)gold(I) tetrafluoroborate in tetrahydrofuran under very mild conditions to give directly the 2,2-diaurated cation {2,2-[(Ph ₃P)Au]₂C₄H₃S}⁺ as the BF₄^- salt. The same product is obtained in a two-step process via the monoaurated 2-[(Ph₃P)Au]C₄H₃S molecule, which adds 1 equiv of [(Ph₃P)-Au]BF₄. Together with the mono- and diaurated furan analogues, which were also prepared via this route, the thiophene compounds have been structurally characterized in single-crystal X-ray studies. The mononuclear complexes of the general formula 2-[(L)Au]C₄H₃E, with L = Ph₃P or Ph ₃As and E = O or S, were all found to have conventional structures with parameters representing classical types of metalated aromatic heterocycles. Crystals of the arsenic analogue, 2-[(Ph₃As)Au]C₄H ₃O, are isomorphous with the Ph₃P complex. The products of the second auration step, with the general formula {2,2-[(L)Au] ₂C₄H₃E}⁺BF₄^- (L = Ph₃P; E = O, S), have the two gold atoms sharing one of the two α-carbon atoms with short intramolecular Au...Au contacts of 2.8134(4) and 2.8461(2) A and small Au-C-Au angles of 82.5(2)° and 84.5(1)°, respectively. The geometry of the five-membered rings suggests that the aromaticity is strongly reduced upon geminal auration at C-1, which renders this carbon atom tetracoordinated. It is particularly noteworthy that the second auration leaves the sulfur or oxygen donor centers untouched. This observation is one of the most remarkable examples of the strong influence of aurophilic bonding.

Full text of DOI:10.1021/om030575f

4922
Organometallics 2003, 22, 4922-4927
Au r a tion of Th iop h en e a n d F u r a n : Str u ctu r es of th e
2-Mon o- a n d 2,2-Dia u r a ted P r od u cts
Keith A. Porter, Annette Schier, and Hubert Schmidbaur*
Anorganisch-chemisches Institut, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4,
D-85747 Garching, Germany
Received August 12, 2003
Thiophene undergoes electrophilic substitution by (triphenylphosphine)gold(I) tetrafluo-
roborate in tetrahydrofuran under very mild conditions to give directly the 2,2-diaurated
-
cation {2,2-[(Ph3P)Au]2C4H3S}+ as the BF4 salt. The same product is obtained in a two-
step process via the monoaurated 2-[(Ph3P)Au]C4H3S molecule, which adds 1 equiv of [(Ph3P)-
Au]BF4. Together with the mono- and diaurated furan analogues, which were also prepared
via this route, the thiophene compounds have been structurally characterized in single-
crystal X-ray studies. The mononuclear complexes of the general formula 2-[(L)Au]C4H3E,
with L ) Ph3P or Ph3As and E ) O or S, were all found to have conventional structures
with parameters representing classical types of metalated aromatic heterocycles. Crystals
of the arsenic analogue, 2-[(Ph3As)Au]C4H3O, are isomorphous with the Ph3P complex. The
-
products of the second auration step, with the general formula {2,2-[(L)Au]2C4H3E}+BF4
(L ) Ph3P; E ) O, S), have the two gold atoms sharing one of the two R-carbon atoms with
short intramolecular Au‚‚‚Au contacts of 2.8134(4) and 2.8461(2) Å and small Au-C-Au
angles of 82.5(2)° and 84.5(1)°, respectively. The geometry of the five-membered rings suggests
that the aromaticity is strongly reduced upon geminal auration at C-1, which renders this
carbon atom tetracoordinated. It is particularly noteworthy that the second auration leaves
the sulfur or oxygen donor centers untouched. This observation is one of the most remarkable
examples of the strong influence of aurophilic bonding.
In tr od u ction
tance of 2.759(1) Å and a small Au-C-Au angle of
79.3(3)° are observed,3 the tolyl complex [MeC6H4-
{Au2(Ph2PCH2CH2)2}][BF4], in which two independent
PPh3 groups are replaced by the chelating ligand 1,4-
bis(diphenylphosphine)butane,4 the tetraaurated com-
plexes [{C5H4(AuPPh3)2}Fe{C5H4(AuPPh3)2}][BF4]5 and
[(CH2)2(C6H4-o)2(AuPPh3)4][BF4],6 in which the even
higher accumulation of positive charge within the same
molecule does not affect the stability of the complexes,
and the unusual trinuclear complex [Ph4C5(AuPPh3)3]-
[BF4], in which an additional short Au‚‚‚Au contact is
observed.7
Geminally diaurated ring systems derived from an
aromatic hydrocarbon were first discovered in the 1970s
by the Nesmeyanov school in attempts to introduce gold
substituents into ferrocene.1 It was observed that after
conventional monometalation to give (LAuC5H4)Fe-
(C5H5), with L ) Ph3P, the second ligand-backed elec-
trophile [(L)Au]+ is attached to the same carbon atom
to generate a cationic species of the proposed formula
{1,1-[(L)Au]2C5H4)Fe(C5H5)}+. This unusual substitu-
tion pattern was finally confirmed by single-crystal
X-ray diffraction studies of the BF4 salt.2
-
Of the 1,1-diaurated aromatic systems containing the
C(AuL)2 fragment represented in the literature, no
structural evidence has been presented for the class of
heteroaromatic complexes of this type. The stability of
compounds of this stoichiometry was established with
the synthesis of [C4H3S(AuPPh3)2][BF4]. The character-
ization of this complex, however, was solely by melting
point and elemental analysis.8
In this early structural work it was noted that the
geminal angle Au-C-Au (78°) at the tetracoordinate
ipso carbon atom is much smaller than a tetrahedral
angle and gives rise to an Au‚‚‚Au distance of only 2.77
Å, shorter than the interatomic distance in metallic
gold.2
An early description of the bonding arrangement has
pointed to a three-center two-electron (3c, 2e) bond, but
positive charge delocalization over the cyclopentadienyl
ring, consequently with a loss of aromaticity, is also
conceivable. Similar complexes have subsequently been
prepared and include the trifluorobenzene complex [(µ-
2,4,6-C6F3H2)(AuPPh3)2][ClO4], in which a Au‚‚‚Au dis-
(3) Uso´n, R.; Laguna, A.; Ferna´ndez, E. J .; Media, A.; J ones, P. G.
J . Organomet. Chem. 1988, 350, 129.
(4) Schmidbaur, H.; Inoguchi, Y. Chem Ber. 1980, 113, 1646.
(5) Perevalova, E. G.; Baukova, T. V.; Sazonenko, M. M.; Grandberg,
K. I. Bull. Acad. Sci. USSR, Chem. Ser. 1985, 1726.
(6) Baukova, T. V.; Kuz’mina, L. G.; Oleinikova, N. A.; Lemenovskii,
D. A.; Blumenfel’d, A. L. J . Organomet. Chem. 1997, 530, 27.
(7) Baukova, T. V.; Slovokhotov, Y. L.; Struchkov, Y. T. J . Orga-
nomet. Chem. 1981, 221, 375.
(8) Nesmeyanov, A. N.; Perevalova, E. G.; Afanasova, O. B.; Tol-
staya, M. V.; Grandberg, K. I. Izv. Akad. Nauk SSSR, Ser Khim. 1978,
1118; Bull. Acad. Sci. USSR, Div. Chem. Sci. 1978, 969.
(1) Perevalova, E. G.; Lemonovskii, D. A.; Grandberg, K. I.; Nes-
meyanov, A. N. Dokl. Akad. Nauk SSSR 1972, 93.
(2) Nesmeyanov, A. N.; Perevalova, E. G.; Grandberg, K. I.; Lemen-
ovskii, D. A.; Baukova, T. V.; Afanasova, O. B. J . Organomet. Chem.
1974, 65, 131.
10.1021/om030575f CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/28/2003

Auration of Thiophene and Furan
Organometallics, Vol. 22, No. 24, 2003 4923
The structural and spectroscopic properties of gemi-
nally diaurated heteroarene complexes can be more fully
understood on one hand by considering the influence of
relativistic effects in gold(I) components9 and applying
the isolobal analogy of [AuPR3]+ to H+ on the other.10
Employing these concepts, the solid state structures of
aromatic dinuclear complexes of the type C(AuL)2
should draw parallels to the transition state structures
proposed for proton exchange at arenes and more
generally to the transition state of electrophilic aromatic
substitution.11 We aim to investigate this relationship
by examining heteroarene systems in this work.
Resu lts a n d Discu ssion
Dir ect Au r a tion of Heter oa r en es. Two examples
of mononuclear heteroaryl gold(I) complexes have been
synthesized by the reaction of lithiated aromatic het-
erocycles12 with (triphenylphosphine)gold chloride in the
molar ratio 1:1 in tetrahydrofuran (eq 1).13
F igu r e 1. Molecular structure of compound 1 (ORTEP
drawing with 50% probability ellipsoids, H atoms omitted
for clarity). Selected bond lengths [Å] and angles [deg]:
Au1-C1 2.038(3), Au1-P1 2.2781(8), Au1‚‚‚Au1′ 3.977(1);
C1-Au1-P1 178.22(9).
identified in this study. The crystals were found to be
isomorphous with those of 2. The structure showed no
anomalies.
The thiophene (1) and furan (2) derivatives were
isolated as air- and moisture-stable crystalline solids in
60% and 50% yields, respectively. Positive ion fast atom
bombardment (FAB) mass spectrometry reveals molec-
ular cations [M]+ for 1 and 2 at m/z ) 542 and 526 amu.
High-intensity peaks with m/z ) 1000 and 984 for 1 and
2, respectively, are also observed and are key features
of both spectra. These mass peaks correspond to the
adducts [C4H3S(AuPPh3)2]+ and [C4H3O(AuPPh3)2]+.
Although such clustering, which results in dinuclear
units, is commonly observed in ion-molecule reactions
in the gaseous state, it shows an interesting parallel to
the solution chemistry of arylgold complexes (vide
infra).2,6
Proton NMR spectroscopy of 1 confirms the aromatic
nature of the thiophene ligand with an overlap of the
thiophene and phenyl resonances between 7.12 and 7.66
ppm. This conclusion is also supported by 13C NMR
spectroscopy, where the thiophene carbon resonance
signals appear in the aromatic region 126.9-133.3 ppm.
The 31P{1H} NMR spectrum exhibits a single peak at
δP 44.3, which is in the field typical of P-Au-Ar bound
species.14 The furan derivative 2 shows NMR spectro-
scopic data similar to 1, although the proton NMR
spectral resonances occur more upfield, in the range
6.28-7.27 ppm. For the 13C NMR of compound 2, the
spectral range broadens, with signals observed between
108.3 and 144.4 ppm. The geminally disubstituted
carbon is not observed in either compound. The arsenic
analogue of 2, 2-[(Ph3As)Au]C4H3O (2a ), has also been
Crystals of C4H3SAu(PPh3), 1 (from dichloromethane/
pentane at 5 °C), are triclinic, space group P1h, with Z
) 2 molecules in the unit cell (Figure 1). The gold atom
is bound directly to the R-carbon of the thiophene
heteroarene and has the usual two-coordinate environ-
ment of P(1)-Au(1)-C(11) 178.22(9)°, Au(1)-P(1)
2.2781(8) Å, and Au(1)-C(11) 2.038(3) Å. For compari-
son, the data for the reference compound PhAu(PPh3)
are 175.5(2)°, 2.296(2) Å, and 2.045(6) Å.15 The thiophene
ring is planar, with the gold atom lying within this plane
as shown by the dihedral angles C(11)-S(1)-C(14)-
C(13) 0.0(4)° and Au(1)-C(11)-C(12)-C(13) 179.6(3)°.
The two molecules per unit cell are organized in pairs
with a slightly offset head-to-tail arrangement. The
closest intermolecular approach is an Au‚‚‚S distance
of 3.977 Å. There are no discernible intermolecular
aurophilic contacts between the molecules on account
of the large triphenylphosphine ligands shielding the
gold atoms.
Crystals of C4H3OAu(PPh3) (2) are triclinic, space
group P1h, with Z ) 2 molecules in the unit cell (Figure
2). The lattice is free of solvent. The distances Au-P
2.2823(8) Å and Au-C 2.032(3) Å and the angle P-Au-C
178.1(1)° are consistent with the thiophene derivative
1 and can be considered normal for an arylgold complex
of a triarylphosphine. The two molecules per unit cell
are oriented antiparallel to each other, and there are
no discernible intermolecular aurophilic or Au‚‚‚O in-
teractions.
Dia u r a ted Heter oa r en es. Tetrafluoroborate salts of
diaurated aromatic ligands can be synthesized by treat-
(9) Schmidbaur, H. Chem. Soc. Rev. (London) 1995, 391.
(10) Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1982, 21, 711.
(11) J ones, W.; Boissel, P.; Chivarino, B.; Crestoni, M. E.; Fornarini,
S.; Lemaire, J .; Maitre, P. Angew. Chem., Int. Ed. 2003, 42, 2057.
(12) Chadwick, D. J .; Willbe, C. J . Chem. Soc., Perkin Trans. 1 1977,
887.
(13) Bonati, F.; Burini, A.; Pietroni, B. R.; Galassi, R. Gazz. Chim.
Ital. 1993, 123, 691.
(14) Porter, K. A.; Schier, A.; Schmidbaur, H. Special Publication-
Royal Society of Chemistry (Perspectives in Organometallic Chemistry)
2003, 287, 74.

4924 Organometallics, Vol. 22, No. 24, 2003
Porter et al.
F igu r e 2. Molecular structure of compound 2 (ORTEP
drawing with 50% probability ellipsoids, H atoms omitted
for clarity). Selected bond lengths [Å] and angles [deg]
(corresponding values for compound 2a in square brack-
ets): Au1-C1 2.032(3) [2.028(3)], Au1-P1 2.2823(8)
[Au1-As1 2.3882(3)]; C1-Au1-P1 178.1(1) [C1-Au1-As1
177.8(1)].
F igu r e 3. Molecular structure of the cation of compound
3 (ORTEP drawing with 50% probability ellipsoids, H
atoms and S/C disorder omitted for clarity). Selected bond
lengths [Å] and angles [deg]: Au1-C1 2.135(7), Au1-P1
2.273(2), Au1‚‚‚Au2 2.8134(4), Au2-C1 2.133(6), Au2-P2
2.274(2); C1-Au1-P1 175.6(2), C1-Au1‚‚‚Au2 48.7(2), P1-
Au1-Au2 134.64(5), C1-Au2-P2 176.3(2), C1-Au2‚‚‚Au1
48.8(2), P2-Au2‚‚‚Au1 134.90(5), Au1-C1-Au2 82.5(2).
ment of an aryl(triorganophosphine)gold(I) complex with
HBF4, by replacement of mercury in organomercury
compounds, or by the direct addition of [(R3P)Au]BF4
formed in situ from AgBF4 and R3PAuCl (eqs 2-4).1-8
Preparative efforts directed at the synthesis of gemi-
nally diaurated heteroarenes in this work focused
initially on the last of these three synthetic pathways,
but direct auration of thiophene with [(Ph3P)Au]+ was
also considered. Experimental results have shown that
thiophene can indeed be diaurated directly by [(Ph3P)-
Au]BF4 in tetrahydrofuran even at -60 °C. After a
simple workup, the yield was 44% (eq 5).
resonances is observed. The signal of the disubstituted
carbon atom is also not detected.
Crystals of [C4H3S(AuPPh3)2][BF4], 3 (from dichloro-
methane/pentane at 20 °C), are triclinic, space group
P1h, with Z ) 2 molecules in the unit cell (Figure 3). The
lattice contains half a dichloromethane molecule. The
two gold atoms share the same R-thiophene carbon atom
as a common bonding partner, resulting in a short
Au‚‚‚Au distance of 2.8134(4) Å, which is shorter than
that of metallic gold (2.88 Å). The Au(1)-C(1)-Au(2)
angle of 82.5(2)° is significantly smaller than the normal
tetrahedral angle and agrees with those reported for the
ferrocenyl complex [C5H5FeC5H4(AuPPh3)2][BF4]2 and
the trifluorophenyl complex [C6H2F3(AuPPh3)2][ClO4]3
of 78(1)° and 79.3(3)°, respectively. The plane of the
triangle Au(1)-C(1)-Au(2) is approximately perpen-
dicular to that defined by the thiophene ring. The
thiophene ring is disordered at sulfur and carbon, where
the atoms are located in split positions in a ratio of ca.
50:50. The gold centers retain the usual linear two-
coordination environment.
The diaurated thiophene complex 3 and furan com-
plex 4 were also prepared via the two-step route as air-
and moisture-stable crystalline solids in 63% (mp 163-
164 °C) and 50% (mp >147 °C (dec)) yields, by the
addition of [(Ph3P)Au]BF4 to the arene complexes 1 and
2, respectively (eq 6).
Crystals of [C4H3O(AuPPh3)2][BF4], 4, are orthorhom-
bic, space group Pnma with Z ) 4 molecules in the unit
cell (Figure 4). The lattice contains no solvent molecules.
The R-position of the furan ring is diaurated, yielding
a monocation of crystallographically imposed mirror
symmetry. The Au(1)-C(1)-Au(1A) angle of 84.5(1)° is
similar to the angle observed in 3 of 82.5(2)°. The
intramolecular Au‚‚‚Au distance is 2.8461(2) Å, with the
Au(1)-C(1)-Au(1A) triangle perpendicular to the thio-
phene ring and the usual linear two-coordinate environ-
ment of the gold atoms: P(1)-Au(1)-C(1) 176.1(1),
Au(1)-P(1) 2.2719(8), and Au(1)-C(1) 2.117(3) Å.
The Au-C distances of 2.135(7) and 2.133(6) Å in 3
and 2.117(3) Å in 4 are significantly longer than those
found in the 2c,2e-bonded precursors, 1 and 2, at
2.038(3) and 2.032(3) Å, respectively. Typically, 2c,2e
bonds between gold and aryl groups are reported in the
range ca. 2.04-2.08 Å. The compound PhAu(PPh3)
exhibits an Au-C bond benchmark distance of
2.045(6) Å.15
The 31P{1H} NMR spectrum of 3 at room temperature
exhibits a sharp singlet at δP 36.7, indicating that in
solution the triphenylphosphine gold(I) units are in
identical stereochemical environments. The 13C NMR
spectrum reveals all the expected resonance signals for
the thiophene and triphenylphosphine ligands; however
the disubstituted carbon is not observed.
The furan derivative 4 exhibits a single resonance at
δP 36.6 for the equivalent triphenylphosphine gold(I)
units at 25 °C. Further evidence for the equivalence of
the triphenylphosphine gold(I) units is provided by the
13C NMR spectrum, where only one set of phenyl
(15) Hong, X.; Cheung, K. K.; Guo, C. X.; Che, C. M. J . Chem. Soc.,
Dalton Trans. 1994, 1867.

Auration of Thiophene and Furan
Organometallics, Vol. 22, No. 24, 2003 4925
Sch em e 1
Ta ble 1. C-C a n d C-Heter oa tom Bon d Dista n ces (Å) w ith in th e Mon o- a n d Dia u r a ted Heter oa r en es 1-4
Sch em e 2
the incoming electrophile are both σ-bound to a single
carbon atom which is in an sp3-hybrid state16-18 (Scheme
2). With the [AuPPh3]+ unit isolobal with H+,10 gemi-
nally diaurated arenes are analogues representing
stable crystalline intermediates in electrophilic aromatic
substitution reactions. The structures observed for 3 and
4 are representative examples for the substitution
process at heteroarenes.
F igu r e 4. Molecular structure of the cation of compound
4 (ORTEP drawing with 50% probability ellipsoids, H
atoms omitted for clarity). Selected bond lengths [Å] and
Exp er im en ta l Section
angles [deg]: Au1-C1 2.117(3), Au1-P1 2.2719(8),
All experiments were carried out under an atmosphere of
purified nitrogen. All solvents were distilled from an appropri-
ate drying agent and were stored under nitrogen over molec-
ular sieves (4 Å). Mass spectra were recorded on a Finnigan
Au1‚‚‚Au1A 2.8461(2); C1-Au1-P1 176.1(1), C1-Au1‚‚‚
Au1A 47.77(7), P1-Au1‚‚‚Au1A 134.85(2), Au1-C1-Au1A
84.5(1).
MAT 90 spectrometer using FAB as an ionization method.
NMR spectra were obtained at room temperature on J EOL-
By examination of the C-C and C-heteroatom bond
400 or J EOL-270 spectrometers. Chemical shifts are reported
lengths in the heteroarene rings of 3 and 4, it is evident
in δ (ppm) values relative to the residual solvent resonance
that there is only partial charge delocalization over the
ring with loss of aromaticity (Scheme 1).
(1H, 13C). 31P{1H} NMR spectra are referenced to external
aqueous H3PO4 (85%).
2-[(Tr ip h en ylp h osp h in e)gold ]th iop h en e, 1.13 Mp: 165-
167 °C (lit.13 168-171 °C). MS (FAB): m/z 458.5 (100%) [Ph3-
PAu]+, 542.4 (35%) [M]+, 720.1 (20%) [Ph3PAuPPh3]+, 999.6
(9.3%) [C4H3S(AuPPh3)2]+. Anal. Calcd for C22H18AuPS
(542.39): C, 48.71; H, 3.34. Found: C, 48.73; H, 3.28.
2-[(Tr ip h en ylp h osp h in e)gold ]fu r a n , 2.13 Mp: 157-158
°C (lit.13 159-160 °C). MS (FAB): m/z 458.5 (100%) [Ph3PAu]+,
526.4 (25%) [M]+, 720.1 (22%) [Ph3PAuPPh3]+, 983.6 (7.3%)
[C4H3O(AuPPh3)2]+. Anal. Calcd for C22H18AuOP (526.32): C,
50.21; H, 3.45. Found: C, 50.32; H, 3.44.
2-[(Tr ip h en yla r sin e)gold ]fu r a n , 2a . Furan (0.10 g, 1.5
mmol) was dissolved in tetrahydrofuran (10 mL), and a 1.6 M
solution of butyllithium in hexane (1.0 mL, 1.6 mmol) was
added. After stirring overnight, (triphenylarsine)gold chloride
(0.53 g, 1.0 mmol) was added as a solid, and the resulting
solution was stirred for a further 1 h. The solvent was removed
From the resonance structures attributed to 4, a
lengthening of the C(1)-C(2) and C(1)-O distances is
expected on going from a mono- to a diaurated het-
eroarene system, with concomitant shortening of C(2)-
C(3), C(3)-C(4), and C(4)-O. The solid state structure
of complex 4 reveals that the C(1)-C(2) and C(1)-O
bond distances become longer by 0.021 and 0.014 Å,
respectively, relative to those observed in compound 2,
and the C(2)-C(3) and C(4)-O bonds become shorter
by 0.018 Å. C(3)-C(4) remains virtually unchanged
(Table 1).
Con clu sion
Electrophilic aromatic substitution reactions occur-
ring at an sp2 carbon center by an addition-elimination
mechanism result in the formation of an “arenonium”
ion comprised of one arene molecule and one electro-
phile. For the hydrogen exchange reactions, it is pos-
tulated that the hydrogen atom being substituted and
(16) Lowry, T. H., Richardson, K. S., Eds. Mechanisms and Theory
in Organic Chemistry; 3rd ed.; Donnelley: New York, 1987.
(17) Isaacs, N. S. Reactive Intermediates in Organic Chemistry;
Wiley: London, 1975.
(18) Olah, G. A.; Kuhn, S. J . J . Am. Chem. Soc. 1958, 80, 6535.

4926 Organometallics, Vol. 22, No. 24, 2003
Ta ble 2. Cr ysta l Da ta , Da ta Collection , a n d Str u ctu r e Refin em en t
Porter et al.
1
2
2a
Crystal Data
formula
Mr
cryst syst
space group
a (Å)
C
22H18AuPS
C22H18AuOP
526.30
triclinic
P1h
7.3914(1)
11.2957(2)
11.4679(2)
91.282(1)
93.823(1)
103.301(1)
929.0(1)
1.881
C22H18AsAuO
570.25
triclinic
P1h
7.3555(1)
11.3778(2)
11.6508(2)
91.870(1)
93.605(1)
102.582(1)
948.7(1)
1.996
542.36
triclinic
P1h
7.7165(1)
11.2820(2)
11.5188(2)
92.328(1)
105.206(1)
95.120(1)
961.7(1)
1.873
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
F
calc (g cm-3
Z
)
2
2
2
F(000)
520
78.42
504
80.10
540
94.90
µ(Mo KR) (cm-1
)
Data Collection
T (°C)
-130
-130
-130
no. of measd reflns
no. of unique reflns
abs corr
23 069
23 453
23 725
3712 [Rint ) 0.035]
DELABS
3604 [Rint ) 0.030]
DELABS
3684 [Rint ) 0.026]
DELABS
T
min/Tmax
0.416/0.803
0.438/0.814
0.508/0.844
Refinement
no. of refined params
226
226
226
final R values [I g 2σ(I)]
R1
0.0225
0.0576
1.229/-1.441
0.0219
0.0578
1.302/-1.579
0.0192
0.0481
0.480/-0.479
wR2a
F
fin(max/min) (e Å-3
)
3‚0.5CH2Cl2
4
Crystal Data
formula
Mr
cryst syst
space group
a (Å)
C
40.5H34Au2BClF4P2S
C40H33Au2BF4OP2
1130.87
triclinic
P1h
1072.35
orthorhombic
Pnma
17.3338(2)
21.1912(2)
9.9489(1)
90
9.7420(2)
14.6798(4)
15.5339(4)
69.960(1)
84.387(1)
73.773(2)
2003.9(1)
1.874
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
90
90
3654.5(1)
1.949
4
F
calc (g cm-3
Z
)
2
F(000)
1078
75.58
2040
81.59
µ(Mo KR) (cm-1
)
Data Collection
-130
T (°C)
-130
no. of measured reflns
no. of unique reflns
abs corr
60 748
98 116
7712 [Rint ) 0.053]
DELABS
4094 [Rint ) 0.045]
DELABS
T
min/Tmax
0.553/0.862
0.463/0.825
Refinement
497
refined params
238
final R values [I g2 σ(I)]
R1
0.0412
0.0843
1.230/-1.808
0.0221
0.0512
1.142/-0.644
wR2a
F
fin(max/min) (e Å-3
)
wR2) {[∑w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2; w ) 1/[σ2(Fo2) + (ap)2 + bp]; p ) (Fo + 2Fc2)/3; a ) 0.0297 (1), 0.0317 (2), 0.018 (2a ), 0.0268
a
2
2
(3‚0.5CH2Cl2), 0.0187 (4); b ) 1.20 (1), 0.68 (2), 0.81 (2a ), 8.90 (3‚0.5CH2Cl2), 6.59 (4).
under vacuum and the residue taken up in dichloromethane
and extracted with water (10 mL). The organic phase was dried
over MgSO4, the solvent reduced in volume (ca. 2 mL), and
the product precipitated with n-pentane. Yield: 0.20 g, 35%.
Mp: 108-109 °C. NMR (CD2Cl2, RT): 13C{1H} 144.4 (s, Cfuran),
133.5 (s, m-Cphenyl), 132.7 (s, ipso-Cphenyl), 130.9 (s, p-Cphenyl),
[C4H3O(AuAsPh3)2]+. Anal. Calcd for C22H18AsAuO (570.27):
C, 46.34; H, 3.18. Found: C, 46.45; H, 3.11.
2,2-Bis[(t r ip h en ylp h osp h in e)gold ]t h iop h en e Tet r a -
flu or obor a te, 3. Meth od A. A solution of [Ph3PAu]BF4
(prepared from Ph3PAuCl (0.25 g, 0.51 mmol) and AgBF4 (0.01
g, 0.51 mmol) in 10 mL of THF) was added to a solution of
thiophene (0.02 g, 0.25 mmol) in 5 mL of THF at -60 °C. The
reaction mixture was stirred for 2 h at -60 °C and was allowed
to warm to room temperature, where it was stirred for another
1 h. The solvent was removed under vacuum, the product was
1
129.5 (s, o-Cphenyl), 118.2 (s, Cfuran), 108.1 (s, Cfuran); H 7.69-
7.24 (m, 16 H, Hfuran and Hphenyl), 6.47 (m, 1H, Hfuran), 6.38 (m,
1H, Hfuran). MS (FAB): m/z 502.4 (100%) [Ph3AsAu]+, 569.3
(36%) [M]+, 807.9 (26%) [Ph3AsAuAsPh3]+, 1071.4 (19%)

Auration of Thiophene and Furan
Organometallics, Vol. 22, No. 24, 2003 4927
dissolved in dichloromethane, and this solution was filtered
to remove any remaining insoluble material. The solvent was
reduced in volume (ca. 2 mL), and the product was precipitated
on addition of diethyl ether. Yield: 0.14 g, 44%.
(m, 1 H, Hfuran), 7.33-7.67 (m, 30 H, Hphenyl), 8.16 (m, 1 H,
H
furan), 8.29 (m, 1 H, Hfuran). MS (FAB): m/z 458.1 (76%) [Ph3-
PAu]+, 719.4 (94%) [Ph3PAuPPh3]+, 982.6 (100%) [C4H3O-
(AuPPh3)2]+. Anal. Calcd for C40H33Au2P2BF4O (1072.38): C,
44.80; H, 3.10. Found: C, 44.66; H, 3.11.
Meth od B. A solution of [Ph3PAu]BF4 (prepared from Ph3-
PAuCl (0.13 g, 0.26 mmol) and AgBF4 (0.05 g, 0.26 mmol) in
10 mL of THF) was added to a solution of 1 (0.14 g, 0.26 mmol)
in 10 mL of THF at -60 °C. The reaction mixture was stirred
for 30 min at -60 °C and was allowed to warm to room
temperature, where it was stirred for another 30 min. The
solvent was removed under vacuum, the product was dissolved
in dichloromethane, and this solution was filtered to remove
any remaining insoluble material. The solvent was reduced
in volume to ca. 2 mL and the product precipitated on addition
of diethyl ether. Yield: 0.17 g, 63%. Mp: 163-164 °C. NMR
(CD2Cl2, RT): 31P{1H} 36.7 (s); 13C{1H} 157.2 (s, Cthiophene),
148.7 (s, Cthiophene), 134.4 (d, J ) 14.0 Hz, m-Cphenyl), 132.7 (s,
p-Cphenyl), 131.6 (s, Cthiophene), 129.9 (d, J ) 11.9 Hz, o-Cphenyl),
X-r a y Cr ysta llogr a p h y. Specimens of suitable quality and
size were mounted on the ends of quartz fibers in F06206R
oil and used for intensity data collection on a Nonius DIP2020
diffractometer, employing graphite-monochromated Mo KR
radiation. The structures were solved by a combination of
direct methods (SHELXS-97) and difference Fourier syntheses
and refined by full matrix least-squares calculations on F2
(SHELXL-97). The thermal motion was treated anisotropically
for all non-hydrogen atoms. All hydrogen atoms were calcu-
lated and allowed to ride on their parent atoms with fixed
isotropic contributions. The sulfur/C2 atoms in the cation of
compound 3 were disordered and refined in split positions with
sof’s of 50:50. Sof refinement of the solvent molecule in
compound 3 led to a value of 0.50, with which it was included
into the refinement. Further information on crystal data, data
collection, and structure refinement are summarized in Table
2. Important interatomic distances and angles are shown in
the corresponding figure captions. Anisotropic thermal pa-
rameters and complete lists of interatomic distances and
angles have been deposited with the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
U.K. The data are available on request on quoting CCDC
217209-217213.
1
128.7 (d, J ) 59.2 Hz, ipso-Cphenyl); H 5.32 (s, CH2Cl2, 1 H),
7.33-7.57 (m, 30 H, Hphenyl), 7.85 (t, J ) 3.9 Hz, 1 H, Hthiophene),
8.34 (d, J ) 3.5 Hz, 1 H, Hthiophene), 8.50 (d, J ) 4.7 Hz, 1 H,
H
thiophene). MS (FAB): m/z 458.1 (81%) [Ph3PAu]+, 719.3 (70%)
[Ph3PAuPPh3]+, 998.4 (100%) [C4H3S(AuPPh3)2]+. Anal. Calcd
for C40H33Au2P2BF4S (1088.45): C, 44.14; H, 3.06. Found: C,
44.04; H, 3.00.
2,2-Bis[(tr ip h en ylp h osp h in e)gold ]fu r a n Tetr a flu or o-
bor a te, 4. A solution of [Ph3PAu]BF4 (prepared from Ph3-
PAuCl (0.19 g, 0.39 mmol) and AgBF4 (0.076 g, 0.39 mmol) in
10 mL of THF) was added to a solution of 2 (0.15 g, 0.28 mmol)
in 10 mL of THF at -60 °C. The reaction mixture was stirred
for 30 min at -60 °C and for an additional 30 min at room
temperature. The solvent was removed under vacuum, and the
residual product was dissolved in dichloromethane and was
filtered to remove the insoluble impurities. The solvent was
reduced in volume to ca. 2 mL, and the product was precipi-
tated by the addition of diethyl ether. Yield: 0.15 g, 50%. Mp:
>147 °C (dec). NMR (CD2Cl2, RT): 31P{1H} 36.6 (s); 13C{1H}
162.5 (s, Cfuran), 154.5 (s, Cfuran), 134.3 (d, J ) 14.0 Hz,
m-Cphenyl), 132.7 (s, p-Cphenyl), 129.9 (d, J ) 11.0 Hz, o-Cphenyl),
128.6 (d, J ) 59.0 Hz, ipso-Cphenyl), 111.7 (s, Cfuran); 1H 6.89
Ack n ow led gm en t. This work was generously sup-
ported by Deutsche Forschungsgemeinschaft, Fonds der
Chemischen Industrie, and Volkswagenstiftung. Dona-
tions of chemicals by Heraeus GmbH and Degussa AG
are gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data as CIF files. This material is available free of charge via
the Internet at http://pubs.acs.org.
OM030575F