Aurophilicity-based one-dimensional arrays of gold(I) phenylene-1,3- and -1,4-dithiolates

Article abstract of DOI:10.1021/ic020107i

Phenylene-1,3-dithiol is converted into a trinuclear gold complex by treatment with 1 equiv of {[(Ph₃P)Au]₃O}⁺BF4^-. In the product, the phenylene unit bears one gold thiolate and one di(gold)sulfonium function. These components aggregate into one-dimensional arrays through head-to-tail aurophilic contacts between the two functions. In the association process, the Au-S-Au angle of the sulfonium group is opened up to accommodate the incoming gold atom between its metal centers. A similar mode of aggregation is found for the triply aurated biphenylene-4,4′-dithiol obtained using the tri(gold)oxonium salt with tri(p-tolyl)phosphine ligands. Probably for steric reasons, in this oligomerization process, the gold(I) thiolate unit is attached side-on to the digold sulfonium unit with retention of the small Au-S-Au angle. Under similar reaction conditions, and with the same molar ratio of the components, phenylene-1,4-dithiol is converted into the bis-sulfonium salt: 1,4-{[(p-Tol)₃PAu]₂S}₂C₆ H₄(BF₄)₂, the dications of which also associate into chains. Along the chains, the phenylene spacers alternate with tetranuclear gold clusters which arise from intimate aggregation of pairs of gold atoms. Together with previous findings, the present results show that gold thiolate (-SAuL) and digold sulfonium functions [-S(AuL)₂⁺] in proper orientation at an arene unit (α-ω) can be considered as soldering points which can be used for joining up the molecular units into one-dimensional arrays solely through metal-metal contacts, which appear to be operative even against Coulomb repulsion between cations. The reaction of biphenylene-4,4′-dithiol with 2 equiv of sodium methoxide and [tri-(c-hexyl)phosphine]gold chloride gives only neutral digold dithiolate complex 4 which is not associated owing to the steric bulk of the tri(c-hexyl)phosphine ligands.

Full text of DOI:10.1021/ic020107i

Inorg. Chem. 2002, 41, 3721−3727
Aurophilicity-Based One-Dimensional Arrays of Gold(I) Phenylene-1,3-
and -1,4-dithiolates
Hendrik Ehlich, Annette Schier, and Hubert Schmidbaur*
Anorganisch-chemisches Institut der Technischen UniVersita¨t Mu¨nchen, Lichtenbergstrasse 4,
D-85747 Garching, Germany
Received February 7, 2002
Phenylene-1,3-dithiol is converted into a trinuclear gold complex by treatment with 1 equiv of {[(Ph3P)Au]3O}+BF -.
4
In the product, the phenylene unit bears one gold thiolate and one di(gold)sulfonium function. These components
aggregate into one-dimensional arrays through head-to-tail aurophilic contacts between the two functions. In the
association process, the Au−S−Au angle of the sulfonium group is opened up to accommodate the incoming gold
atom between its metal centers. A similar mode of aggregation is found for the triply aurated biphenylene-4,4′-
dithiol obtained using the tri(gold)oxonium salt with tri(p-tolyl)phosphine ligands. Probably for steric reasons, in this
oligomerization process, the gold(I) thiolate unit is attached side-on to the digold sulfonium unit with retention of
the small Au−S−Au angle. Under similar reaction conditions, and with the same molar ratio of the components,
phenylene-1,4-dithiol is converted into the bis-sulfonium salt: 1,4-{[(p-Tol)3PAu]2S}2C H (BF ) , the dications of
6
4
4 2
which also associate into chains. Along the chains, the phenylene spacers alternate with tetranuclear gold clusters
which arise from intimate aggregation of pairs of gold atoms. Together with previous findings, the present results
show that gold thiolate (−SAuL) and digold sulfonium functions [−S(AuL)2+] in proper orientation at an arene unit
(R−ω) can be considered as “soldering” points which can be used for joining up the molecular units into one-
dimensional arrays solely through metal−metal contacts, which appear to be operative even against Coulomb
repulsion between cations. The reaction of biphenylene-4,4′-dithiol with 2 equiv of sodium methoxide and [tri-
(c-hexyl)phosphine]gold chloride gives only neutral digold dithiolate complex 4 which is not associated owing to the
steric bulk of the tri(c-hexyl)phosphine ligands.
Introduction
covalent or coordinative bonding but also through direct
closed-shell interactions between the metal centers (“auro-
philicity”).4 Even though this interaction is generally weak5
and comparable in its energy to hydrogen bonding,6 the effect
is strong enough to have a marked influence on the
configuration, conformation, and oligomerization of almost
all gold(I) compounds.7
Coordinatively unsaturated gold(I) thiolates RSAu are
known to aggregate into oligomers (RSAu)n predominantly
via conventional donor-acceptor bonding,8 but their coor-
dinatively saturated complexes RSAuL still undergo associa-
tion, which arises solely from aurophilic bonding (A, Scheme
Gold(I) thiolates (RSAu) and their complexes (RSAuL)
are well established as versatile precursors and reagents for
a large variety of applications and represent a class of
compounds in gold chemistry which has been studied most
extensively for several decades.1 The properties of the species
are governed by the nature of the substituents R and the
ligands L, and representative examples range from pastelike
oligomeric thiolates (RSAu)n as “liquid golds” for gilding2
to crystalline monomeric complexes derived from tertiary
phosphines and thioglucose for chrysotherapy.3
It is a specific feature of gold(I) complexes that oligo-
merization can not only be accomplished by conventional
(3) Shaw, C. F., III. In Gold-Progress in Chemistry, Biochemistry and
Technology; Schmidbaur, H., Ed.; John Wiley & Sons: Chichester,
U.K., 1999, p 267.
(4) Scherbaum, F.; Grohmann, A.; Huber, B.; Kru¨ger, C.; Schmidbaur,
H. Angew. Chem., Int. Ed. Engl. 1988, 27, 1544.
* To whom correspondence should be addressed. E-mail:
H.Schmidbaur@lrz.tum.de.
(1) Gold-Progress in Chemistry, Biochemistry and Technology; Schmid-
baur, H., Ed.; John Wiley & Sons: Chichester, U.K., 1999.
(2) Landgraf, G. In Gold-Progress in Chemistry, Biochemistry and
Technology; Schmidbaur, H., Ed.; John Wiley & Sons: Chichester,
U.K., 1999, p 146.
(5) Schmidbaur, H. Chem. Soc. ReV. 1995, 391.
(6) Schmidbaur, H. Interdiscip. Sci. ReV. 1992, 17, 213.
(7) (a) Schmidbaur, H. Gold Bull. (London) 1990, 23, 11. (b) Schmidbaur,
H. Gold Bull. (London) 2000, 33, 3.
10.1021/ic020107i CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/14/2002
Inorganic Chemistry, Vol. 41, No. 14, 2002 3721

Ehlich et al.
Scheme 1. Aurophilic Interactions in Gold Thiolates A, Di(gold)sulfonium Salts B and Mixed Gold Thiolate/Di(gold)sulfonium Units C
1).9 In these aggregates, the gold atoms appear in pairs with
intermolecular contacts typically in the range 2.9-3.2 Å.
Note that these distances are close to the metal-metal
separation in metallic gold and well below the sum of the
van der Waals radii (3.65 Å).
Aurophilic bonding is even more efficient in groups with
more than two gold atoms in close contact. Aggregation
between two pairs of gold atoms thus leads to four-atom
clusters in the form of a square, a rhombus, or even a
tetrahedron. Representative examples in the gold(I) thiolate
series are the cation aggregates of di(gold)sulfonium salts10
(B, Scheme 1). Note that this association occurs against
Coulomb repulsion between cationic centers.
In the present account, we report on the preparation and
structural characterization of novel oligomers based on
interactions between mixed gold thiolate/di(gold)sulfonium
units derived from phenylene-1,3/1,4- and biphenylene-4,4′-
dithiols. For this particular combination (C, Scheme 1), the
gold atoms are found to form closed triangles or V-shaped
triatomic units, as shown by X-ray structure analysis of two
representative examples. Owing to the absence of Coulomb
repulsion, the aurophilic bonding is particularly strong and
determines the structure of the aggregates. Phenylene-4,4′-
bis(digoldsulfonium) salts are shown to associate via tetra-
nuclear clusters as already described for the aliphatic
analogues.10
Preparative Studies
Phenylene-1,2-dithiol, its 4-methyl derivative, or related
dithiols are known to react (as their alkali or ammonium
salts) with aurating agents such as (R3E)AuX (E ) P, As; X
-
) halogen) or {[(R3P)Au]3O}+BF4 to give dinuclear or
trinuclear complexes with the gold atoms held in close
(aurophilic) proximity.11-14 Because of the internal (intramo-
lecular) closed-shell interactions, no oligomerization is
observed. It is only upon the loss of phosphine R3P that
further association into tetranuclear clusters takes place.11b,12
Phenylene-1,3-dithiol also affords a dinuclear gold(I) di-
thiolate, but with this substitution pattern, the metal atoms
are separated and sterically protected such that no Au‚‚‚Au
contacts can be maintained.14 Furthermore, dinuclear com-
plexes derived from phenylene-1,2-dithiol can be reacted with
rhodium or iridium complexes to afford heterotrinuclear
compounds containing the (Au2M) cores (M ) Rh, Ir).15
The reaction of phenylene-1,3-dithiol with equimolar
-
quantities of {[(Ph3P)Au]3O}+BF4 in dichloromethane af-
fords high yields (92%) of a trinuclear complex (1, Scheme
2). The product can be crystallized from dichloromethane/
pentane at -20 °C as pale yellow needles which give the
correct elemental analysis. Solutions in CD2Cl2 show only
one broad 31P resonance at 20 °C, but at -55 °C, this signal
(br s 40.5 ppm) is split into two resonances in the intensity
(8) (a) Schro¨ter, I.; Stra¨hle, J. Chem. Ber. 1991, 124, 2161. (b) Wojnowski,
W.; Becker, B.; Sassmannshausen, J.; Peters, E.-M.; Peters, K.; von
Schnering, H. G. Z. Anorg. Allg. Chem. 1994, 620, 1417.
(9) (a) Nakamoto, M.; Hiller, W.; Schmidbaur, H. Chem. Ber. 1993, 126,
605. (b) Fackler, J. P., Jr.; Staples, R. J.; Elduque, A.; Grant, T. Acta
Crystallogr. 1994, C50, 520. (c) Narayanaswamy, R.; Young, M. A.;
Parkhurst, E.; Ouelette, M.; Kerr, M. E.; Ho, D. M.; Elder, R. C.;
Bruce, A. E.; Bruce, M. R. M. Inorg. Chem. 1993, 32, 2506. (d) Sladek,
A.; Angermaier, K.; Schmidbaur, H. J. Chem. Soc., Chem. Commun.
1996, 1959.
(10) (a) Sladek, A.; Schmidbaur, H. Chem. Ber. 1995, 128, 907. (b) Wang,
S.; Fackler, J. P., Jr. Inorg. Chem. 1990, 29, 4404. (c) Jones, P. G.;
Weinkauf, A. Z. Kristallogr. 1994, 209, 87. (d) Kuz’mina, L. G.;
Dvortsova, N. V.; Smyslova, E. I.; Grandberg, K. I. Russ. J. Inorg.
Chem. 1992, 37, 1420. (e) Sladek, A.; Schmidbaur, H. Inorg. Chem.
1996, 35, 3268. (f) Lopez-de-Luzuriaga, J. M.; Sladek, A.; Schneider,
W.; Schmidbaur, H. Chem. Ber. 1997, 130, 641. (g) Lopez-de-
Luzuriaga, J. M.; Sladek, A.; Schier, A.; Schmidbaur, H. Inorg. Chem.
1997, 36, 966.
(11) (a) Nakamoto, M.; Koijman, H.; Paul, M.; Hiller, W.; Schmidbaur,
H. Z. Anorg. Allg. Chem. 1993, 619, 1341. (b) Davila, R. M.; Elduque,
A.; Grant, T.; Staples, R. J.; Fackler, J. P., Jr. Inorg. Chem. 1993, 32,
1749. (c) Yip, H. K.; Schier, A.; Riede, J.; Schmidbaur, H. J. Chem.
Soc., Dalton Trans. 1994, 2333.
(12) Nakamoto, M.; Schier, A.; Schmidbaur, H. J. Chem. Soc., Dalton
Trans. 1993, 1347.
(13) Davila, R. M.; Staples, R. J.; Elduque, A.; Harlass, M. M.; Kyle, L.;
Fackler, J. P., Jr. Inorg. Chem. 1994, 33, 5940.
(14) Gimeno, M. C.; Jones, P. G.; Laguna, A.; Laguna, M.; Terroba, R.
Inorg. Chem. 1994, 33, 3932.
(15) del Rio, I.; Terroba, R.; Cerrada, E.; Hursthouse, M. B.; Laguna, M.;
Light, M. E.; Ruiz, A. Eur. J. Inorg. Chem. 2001, 2013.
3722 Inorganic Chemistry, Vol. 41, No. 14, 2002

Aurophilicity-Based 1D Arrays
Scheme 2. Preparation of Complexes 1 and 3
Scheme 4. Preparation of Complex 4
Attempts to this end were successful, however, with
biphenylene-4,4′-dithiol. A trinuclear product (3) was formed
following the stoichiometry shown in Scheme 2. The NMR
spectra show only one 31P resonance at 20 °C, but this signal
(br s 43.2 ppm) also splits (as observed for 1) into two
components at -55 °C (33.2 and 42.3 ppm, intensity ratio
1
1:2). The H and 13C{1H} spectra are as expected (see
Experimental Section).
The crystal structure of product 3 with tri(p-tolyl)phos-
phine ligands shows signs of steric crowding which alters
the interaction between the individual units in the one-
dimensional aggregates (see later). This steric crowding
becomes even more important as the bulk of the phosphine
is increased further. The reaction of biphenylene-4,4′-dithiol
with 2 equiv of sodium methoxide and [tri(c-hexyl)phos-
phine]gold chloride gives only a dinuclear complex (4,
Scheme 4), in which each sulfur atom is associated solely
with one (phosphine)gold unit. The molecules are found to
be monomers in the crystal with no discernible sub-van der
Waals contacts.
Scheme 3. Preparation of Complex 2
Structural Studies
Crystals of complex 1 (from dichloromethane/pentane) are
monoclinic, space group P21/c, with Z ) 4 formula units
and 12 dichloromethane molecules in the unit cell. The
asymmetric unit contains one trinuclear cation (Figure 1),
one BF4- counterion, and three solvent molecules [1‚3CH2-
Cl2]. The cations are aggregated in parallel strings oriented
along the c-axis as shown in Figure 2. In the individual
cation, the 1,3-phenylene unit links a (phosphine)gold thiolate
group and a bis[(phosphine)gold]sulfonium group. The three
S-Au-P units are quasilinear [175.5(5), 171.12(4), and
168.39(4)° for Au1, Au2, and Au3, respectively], while the
valencies of the thiolate sulfur atom form an angle of
Au1-S1-C1 104.3(2)° and the sulfonium group is pyra-
midal with angles Au2-S2-C5 108.1(2)°, Au3-S2-C5
103.3(1)°, and Au2-S2-Au3 110.17(5)°. Only the latter of
the three angles is surprising in that it is larger than in
standard di(gold)sulfonium salts which are not associated into
oligomers. In these standard cases [RS(AuL)2]+, a small
Au-S-Au angle of less than 90° brings the gold atoms close
together and allows for aurophilic stabilization.10 (In this
context, note also the small angles in compound 3 described
later).
ratio 2:1 at 36.5 and 42.6 ppm, respectively. Likewise, the
1H and 13C{1H} NMR spectra show the signals of virtually
equivalent phenyl groups at room temperature, which are
separated into two sets at -55 °C. This finding suggests rapid
scrambling of (Ph3P) or (Ph3PAu) units in solution at 20 °C
on the NMR time scale but long residence times of these
units at the two different thiolate/sulfonium functions at low
temperature. This structure has been confirmed in a single-
crystal X-ray diffraction study.
Unexpectedly, treatment of phenylene-1,4-dithiol with tris-
{[tri(p-tolyl)phosphine]-gold(I)}oxonium tetrafluoroborate
under the conditions employed for 1 (molar ratio 1:1) gave
mainly the tetranuclear bis-sulfonium salt (2, Scheme 3).
Compound 2 could be crystallized in pure form. The analyti-
cal and spectroscopic data confirm the proposed composition,
and the structure could be determined (see following
paragraphs and the Experimental Section). The isolated yields
of 2 are low (25%), and the nature of the byproducts is
unclear. The trinuclear complex could not be isolated from,
or detected in, the reaction mixture (Scheme 2).
The reason for the opening of the Au2-S2-Au3 angle
in complex 1 (by as much as ca. 25°) is immediately obvious
from the structure of the polycationic chain (Figure 2). The
gold atom Au1A of the thiolate function of a neighboring
Inorganic Chemistry, Vol. 41, No. 14, 2002 3723

Ehlich et al.
Figure 3. Dication of compound 2 with atomic numbering (ORTEP, 50%
probability ellipsoids).
Figure 1. Cation of compound 1 with atomic numbering (ORTEP, 50%
probability ellipsoids).
Figure 2. Arrangement of the cations of 1 in strings [Au2-Au1A 3.0602-
(2), Au3-Au1A 2.9983(2) Å].
molecule is inserted between the gold atoms Au2 and Au3
of the sulfonium group to give an isosceles triangle of gold
atoms with two new short metal-metal contacts: Au2-
Au1A 3.0602(2) and Au3-Au1A 2.9983(2) Å. The gold
thiolate group S1A-Au1A is thus drawn into the wedge of
the sulfonium group roughly bisecting the Au2-S2-Au3
angle. It appears that through this aggregation the energy
gain from aurophilic bonds is doubled by replacing the single
Au2-Au3 contact by the contacts of both Au2 and Au3 with
the incoming Au1A. This is a new principle of aurophilicity-
based oligomerization.4-7
Figure 4. Aggregation of the cations of 2 into chains through intimate
aurophilic bonding between the gold atoms of the sulfonium groups [Au1-
Au2 3.2091(2), Au1-Au2A 3.1626(2), Au3-Au4 3.1607(2), Au3-Au3A
2.9684(3), Au4-Au4A 3.0471(3) Å; Au2-Au1-Au2A 93.325(6)°, Au1-
Au2-Au1A 86.675(6)°, Au4-Au3-Au3A 90.681(4)°, Au3-Au4-Au4A
89.254(4)°].
It should be noted that, contrary to the situation found for
1, the angles at the sulfonium centers [Au1-S1-Au2 86.66-
(4)°, Au3-S2-Au4 84.29(4)°] remain small upon aggrega-
tion because no insertion of gold atoms into the S(AuP)2
wedges occurs. With the two angles significantly smaller than
90°, the Au-Au distances can be kept within the range of
aurophilic bonding. A bending of all P-Au-S axes [with
angles between 170.83(4)° and 174.60(4)°] also brings all
gold atoms closer together.
Crystals of compound 3 (from dichloromethane/pentane)
are monoclinic, space group P21/n with Z ) 4 formula units
in the unit cell. One of the sulfur atoms (S2) at the ends of
the biphenylene unit bears only one gold atom (Au3), while
the other (S1) represents a sulfonium center bearing two gold
atoms (Au1, Au2, Figure 5). Owing to the small angle
Au1-S1-Au2 of only 79.83(3)° the two gold atoms are in
close proximity [Au1-Au2 3.0039(2) Å] certainly associated
with aurophilic bonding. The two phenylene rings are not
coplanar and form a dihedral angle of 40.3(5)°.
Crystals of compound 2 (from dichloromethane/pentane)
contain 8 formula units and 8 molecules of dichloromethane
in the unit cell (monoclinic, space group C2/c). The asym-
metric unit therefore has one tetranuclear dication (Figure
3), two tetrafluoroborate counterions, and one solvent
molecule [2‚CH2Cl2]. The dications are aggregated into
chains through intimate aurophilic bonding between the gold
atoms of the sulfonium groups (Figure 4). At either end of
the phenylene centerpiece, the gold atoms of two neighboring
dications form tetranuclear units with short Au-Au dis-
tances:
Au1-Au2 3.2091(2), Au1-Au2A 3.1626(2), Au3-Au4
3.1607(2), Au3-Au3A 2.9684(3), and Au4-Au4A
3.0471(3) Å. At one end, the gold atoms are related by a
center of inversion with complementary Au-Au-Au angles
of 93.325(6)° (at Au1) and 86.675(6)° (at Au2), while the
gold atoms at the other end are related by a 2-fold axis and
form a trapezoid only slightly distorted from a rectangle with
angles of 90.681(4)° at Au3 and 89.254(4)° at Au4.
These trinuclear units are lined up head-to-tail to form
strings along the b axis as shown in Figure 6. The connec-
tivity in the resulting polycation is solely based on aurophilic
bonding between the gold atom Au3 of the thiolate group
3724 Inorganic Chemistry, Vol. 41, No. 14, 2002

Aurophilicity-Based 1D Arrays
Figure 7. Structure of the cation of compound 4. [ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity; Au1-P1 2.279-
(1), Au1-S1 2.310(1) Å, Au1-P1-S1 175.70(4)°].
Figure 5. Structure of the cation of compound 3 [ORTEP drawing with
50% probability ellipsoids, H-atoms omitted for clarity; Au1-Au2 3.0039-
(2) Å].
between the neutral thiolate and the cationic sulfonium
groups, while for the tetranuclear units the interaction relies
on direct contacts between sulfonium groups overruling
Coulomb repulsion. This Coulomb repulsion is avoided in
the trinuclear complexes, like 1 or 3, where each sulfonium
function interacts with a thiolate function, suggesting that
the sulfonium/sulfonium and thiolate/thiolate modes are the
less favorable combinations as compared to two sulfonium/
thiolate combinations.
A cartoon can be used to illustrate the overall structural
pattern in compound 1: a procession of animals (camels,
donkeys, etc.) each of which holds on with his jaws to the
tail of the preceding companion.
The molecular geometry of the components is readjusted
such that an optimum of metal-metal contacts can be
achieved. Compromises with steric effects of the ligands lead
to specific preferences for either various Au-Au-Au
isosceles triangles (V-shaped units) in the triatomic case (1,
3) or square, rectangular, or rhombic arrangements in the
tetra-atomic case (2 and examples in the literature).
Solvation of the aggregates in polar solvents leads to
disintegration to give ionic, monomeric units, for which
ligand scrambling can be detected at room temperature by
NMR methods. The process is reversible, and upon crystal-
lization, the self-assembly of the cations leads to the
formation of the one-dimensional systems.
Figure 6. Head-to-tail alignment of trinuclear units of 3 [Au3-Au2B
3.2530(2) Å, S1B-Au2B-P2B 170.80(4)°, Au3-Au2B-Au1B 91.045-
(6)°].
and one of the two gold atoms (Au2B) of the sulfonium
center of a neighboring molecule: Au3-Au2B 3.2530(2)
Å. The two quasilinear triatomic units S2-Au3-P3 and
S1B-Au2B-P2B form a dihedral angle of P3-Au3-
Au2B-P2B ) 88.7° representing a “crossed swords”
orientation which is required to minimize steric repulsion
between the bulky phosphine groups. There is also a
significant bending of S1B-Au2B-P2B [170.80(4)°] as-
sisting in the approach of Au2B and Au3. On the other
hand, the angle Au3-Au2B-Au1B, although only 91.045-
(6)°, is too large to bring Au3 and Au1B close enough for
a bonding interaction. The tetrafluoroborate counterions have
no close contacts to atoms of the neighboring polycation
strings.
Crystals of compound 4 are monoclinic, space group P21/
n, with Z ) 2 formula units and four molecules of di-
chloromethane in the unit cell. The two halves of the indi-
vidual dinuclear molecules and the two solvent molecules
are related by a center of inversion located in the middle of
the C4-C4A linkage of the biphenylene unit (Figure 7).
The two phenylene groups are coplanar with a dihedral
angle of 180°. With standard bond distances and bond angles
S1-Au1-P1 175.70(4)° and Au1-S1-C1 103.1(1)°, the
molecular geometries show no anomalies.
Regardless of these structural details, and expressed in a
simple picture, it appears that both gold thiolate and gold
sulfonium functions are “sticky” and readily “glued” or
“soldered” together through metal clustering.
Experimental Section
All experiments were routinely carried out in an atmosphere of
dry and pure nitrogen. Solvents were dried and saturated with
nitrogen, and glassware was oven-dried and filled with nitrogen.
Standard equipment was used throughout. Sodium ethanethio-
late,16 1,4-bis(ethylsulfanyl)benzene,17 [tri(c-hexyl)phosphine]gold
chloride,18 and tris[(triphenylphosphine)gold(I)]oxonium tetrafluo-
roborate and its tri(p-tolyl)phosphine analogue were obtained
following literature procedures.19 Phenylene-1,4-dithiol and biphe-
Conclusions
The present study has shown that partial or complete
auration of phenylene-1,3- and -1,4-dithiol or biphenylene-
4,4′-dithiol leads to trinuclear mono- (1, 3) or tetranuclear
disulfonium salts (2). The cations of these salts are found to
aggregate in one-dimensional coordination arrays through
head-to-tail aurophilic bonding (Figures 2, 4, and 6). For
the trinuclear units, the metal-metal contacts are established
(16) Kubicki, M. M.; Oudet, P.; Martin, C.; Barre, C. J. Chem. Soc., Dalton
Trans. 1995, 3699.
(17) Testaferri, L.; Tingoli, M.; Tiecco, M. J. Org. Chem. 1980, 45, 4376.
(18) Al-Sa’ddy, A. K.; McAuliffe, C. A.; Parish, R. P.; Sandbank, J. A.
Inorg. Synth. 1985, 23, 191.
Inorganic Chemistry, Vol. 41, No. 14, 2002 3725

Ehlich et al.
Table 1. Crystal Data, Data Collection, and Structure Refinement.
1‚3CH2Cl2
2‚CH2Cl2
3
4‚2CH2Cl2
Crystal Data
C91H90Au4B2Cl2F8P4S2
2404.02
monoclinic
C2/c
43.3854(3)
23.5896(1)
18.3088(1)
90
108.309(1)
90
17789.4(2)
1.795
b
formula
Mr
cryst syst
space group
a (Å)
b (Å)
c (Å)
C63H55Au3BCl6F4P3S2
1859.51
monoclinic
P21/c
12.8733(1)
28.1979(3)
17.6585(1)
90
93.521(1)
90
6398.0(1)
1.930
C75H71Au3BF4P3S2
1807.06b
monoclinic
P21/n
21.8506(2)
14.2848(1)
23.2992(2)
90
C50H78Au2Cl4P2S2
1340.92
monoclinic
P21/n
9.7574(1)
11.7033(1)
23.7344(3)
90
101.336(1)
90
2657.5(1)
1.676
R (deg)
â (deg)
γ (deg)
V (Å3)
97.115(1)
90
7216.4(1)
F
calcd (g cm-3
Z
)
1.663b
4
8
9280
68.17
4
2
1332
58.87
F(000)
3560
73.04
3504[b]
µ(Mo KR) (cm-1
)
62.59[b]
Data Collection
-130
T (°C)
-130
-130
-130
measured reflns
unique reflns
abs corr
91405
228263
204962
15702
79730
13154 [Rint ) 0.0446]
DELABS
0.385/0.788
19624 [Rint ) 0.0440]
none
5732 [Rint ) 0.0370]
none
DELABS
0.356/0.772
Tmin/Tmax
Refinement
1018
refined params
739
793
271
Final R Values [I > 2σ(I)]
0.0360
R1
0.0337
0.0796
0.0354
0.0801
0.0302
0.0713
wR2a
0.0903
(shift/error)max
F
<0.001
2.177/-1661
<0.001
1.620/-1.705
<0.001
1.898/-1.322
<0.001
0.909/-1.360
fin(max/min) (e Å-3
)
2
2
2
2
2
2
a wR2 ) {[∑w(Fo - Fc )2]/∑[w(Fo )2]}1/2; w ) 1/[σ2(Fo ) + (ap)2 + bp]; p ) (Fo + 2Fc )/3; a ) 0.0260 (1‚3CH2Cl2), 0.0518 (2‚CH2Cl2), 0.340 (3),
0.0250 (4‚2CH2Cl2); b ) 32.60 (1‚3CH2Cl2), 88.03 (2‚CH2Cl2), 15.51 (3), 6.87 (4‚2CH2Cl2). b Values correspond to solvent free unit (see Experimental
Section).
nylene-4,4′-dithiol20 were prepared in modified procedures as
described. Phenylene-1,3-dithiol and all other reagents are com-
mercially available.
containing the dithiol is separated and dried with sodium sulfate.
Toluene is distilled off in vacuo, and the product is obtained as a
pale yellow solid (2.88 g, 78%). The analytical results are in
agreement with the data given in the literature.20d
Phenylene-1,4-dithiol. A solution of 1,4-bis(ethylsulfanyl)-
benzene (0.85 g, 4.29 mmol) in HMPA (7.5 mL) is treated with
sodium (0.51 g, 22.0 mmol) at room temperature for 24 h. After
separation from the remaining sodium the reaction mixture is poured
into ice water (50 mL) containing concentrated hydrochloric acid
(5 mL). After extracting twice with diethyl ether (each 25 mL),
the united organic extracts are washed twice with water (each 100
mL) and dried with sodium sulfate. The diethyl ether is removed
in vacuo to leave the phenylene-1,4-dithiol as a pale yellow solid
(372 mg, 61%). The analytical data agree with those given in the
literature.20a
Biphenylene-4, 4′-dithiol. Biphenylene-4,4′-disulfonyl dichloride
(5.96 g, 16.97 mmol) is dissolved in a hot toluene-water mixture
(70 and 48 mL, respectively). Then, at 70 °C and with vigorous
stirring, 16.10 g (0.136 mol) of tin filings is added, followed by
dropwise addition of concentrated hydrochloric acid (27 mL, 0.27
mol) within 0.5 h while increasing the temperature to 85 °C. After
the addition of the acid, the mixture is kept at 85 °C for an additional
2 h. Subsequently, more toluene is added to improve phase
separation. After cooling to room temperature, the toluene layer
Phenylene-1-bis[(triphenylphosphine)gold(I)]sulfonio-3-
[(triphenylphosphine)gold(I)]thiolate Tetrafluoroborate, 1. A
solution of tris[(triphenylphosphine)gold(I)]oxonium tetrafluorobo-
rate (281 mg, 0.19 mmol) in dichloromethane (5 mL) is treated
with a solution of phenylene-1,3-dithiol (27 mg, 0.19 mmol) in
CH2Cl2 (2 mL) and a small quantity of NaBF4 at 20 °C for 1 h.
The precipitate is filtered off, and the product is crystallized from
the filtrate upon addition of pentane and cooling to -20 °C; the
pale yellow crystals are dried in a vacuum (280 mg, 92% yield).
C60H49Au3BF4P3S2 (1604.80) Calcd: C, 44.91; H, 3.08; Au,
36.82%. Found: C, 44.80; H, 3.48; Au, 37.40%. NMR (CD2Cl2,
20 °C): 31P{1H} 40.5, br s (-55 °C: 36.5, s, 2 P; 42.6, s, 1 P); 1H
7.27-7.84, m, 45 H, Ph; 7.88, t, J ) 1.73 Hz, 1 H, C6H4; 7.23, dd,
J ) 7.92, and 1.73 Hz, 2 H, C6H4; 6.85, t, J ) 7.92 Hz, 1 H, C6H4;
13C{1H} 129.1, 129.9, 132.7, and 134.5, with J ) 7.3, 11.9, 0, and
14.5 Hz, respectively, for C6H5; 128.2, 128.4, 136.4, and 139.8,
all s, for C6H4(S)2.
Phenylene-1,4-bis{bis[(tri(p-tolyl)phosphine)gold(I)]sulfo-
nium} Bis(tetrafluoroborate), 2. Following the procedure de-
scribed for 1, the product is obtained from the oxonium salt (138
mg, 0.086 mmol) and phenylene-1,4-dithiol (12.2 mg, 0.086 mmol)
in a total of 7 mL of CH2Cl2 as colorless crystals (50 mg, 25%
yield).
(19) (a) Nesmeyanov, A. N.; Perevalova, E. G.; Struchkov, Y. T.; Antipin,
M. Y.; Grandberg, K. I.; Dyadchenko, V. P. J. Organomet. Chem.
1980, 201, 343. (b) Yang, Y.; Ramamoorthy, V.; Sharp, P. R. Inorg.
Chem. 1993, 32, 1946.
(20) (a) Maiolo, F.; Testaferri L.; Tiecco, M.; Tingoli, M. J. Org. Chem.
1981, 46, 3070. (b) Testaferri, L.; Tiecco, M.; Tingoli, M.; Chianelli,
D.; Montanucci, M. Tetrahedron 1982, 38, 3687. (c) Zheltov, A. Ya.;
Avramenko, E. N.; Stepanov, B. I. Russ. J. Org. Chem. 1980, 16,
342. (d) Alov, E. M.; Nikiforov, A. V.; Novikov, S. E.; Kobylinskii,
D. B.; Moskvichev, Yu. A.; Kryukova, G. G.; Yasinskii, O. A.;
Budanov, N. A. Russ. J. Org. Chem. 1998, 34, 1160.
C90H88Au4B2F8P4S2 (2319.20) Calcd: C, 46.61; H, 3.82; Au,
33.97%. Found: C, 47.55; H, 4.01; Au, 34.11%. NMR (CD2Cl2,
20 °C): 31P{1H} 35.9, s; 1H 2.37, 36 H, Me; 7.19-7.36, m, 52 H,
C6H4/5
;
13C{1H} 21.6, s, Me; 126.0, 130.6, 134.4, and 143.4, with
J ) 60.7, 12.3, 13.8, and 0 Hz, respectively, for C6H4(Tol); 133.0,
3726 Inorganic Chemistry, Vol. 41, No. 14, 2002

Aurophilicity-Based 1D Arrays
s, 4 C; 135.0, s, 2 C, for C6H4(S2). MS (FAB) m/z 1144.7 (18.7%)
[M - 2(AuPTol3)].
Structure Determinations. 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 diffracto-
meter, 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 placed in idealized calculated positions and
allowed to ride on their corresponding carbon atoms with fixed
isotropic contributions. Crystals of compound 3 contained some
additional disordered and unidentified solvent in the lattice, which
was not included in the refinement but was taken care of by the
“SQUEEZE” procedure (from PLATON). The volume occupied
by the solvent is 677 Å3; the number of electrons per unit cell
deduced by SQUEEZE is 14. Further information on crystal data,
data collection, and structure refinement are summarized in Table
1. Important interatomic distances and angles are shown in the
corresponding figure captions. Thermal parameters and tables of
interatomic distances and angles have been deposited with the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, U.K. The data are available on request on quoting
CCDS 183445-183448.
Biphenylene-4-{bis[(tri(p-tolyl)phosphine)gold(I)]sulfonio}-4′-
[(tri(p-tolyl)phosphine)gold(I)thiolate] Tetrafluoroborate, 3. A
solution of the oxonium salt (100 mg, 0.062 mmol) in dichlo-
romethane (5 mL) is treated with a solution of the dithiol (13.6
mg, 0.062 mmol) in 2 mL of CH2Cl2 and a small amount of NaBF4
with stirring at 20 °C for 1 h. The precipitate is filtered off, and
the product is crystallized from dichloromethane/pentane at -20
°C (57 mg, 51% yield).
C75H71Au3BF4P3S2 (1807.14) Calcd: C, 49.85; H, 3.96; Au,
32.70%. Found: C, 51.06; H, 4.13; Au, 32.12%. NMR (CD2Cl2,
20 °C): 31P{1H} 43.2, br s; [-55 °C: 33.2 (s, 1 P) and 42.3 (s, 2
1
P)]; H 2.39, s, 27 H, Me; 7.10-7.80, m, 44 H, C6H4; 13C{1H}
21.25, s, Me; 125.8, 130.5, 134.3, and 143.5, with J ) 58.6, 8.3,
10.9, and 0 Hz, respectively, for C6H4(Tol); 126.7, 133.1, 137.1,
and 138.6, all s, for (C6H4)2(S)2. MS(FAB): m/e ) 1219.6 (12.0%)
[M - Au(PTol3)]+.
Biphenylene-4,4′-bis{[tri(c-hexyl)phosphine]gold(I)}-
thiolate, 4. A solution of the biphenylene-4, 4′-dithiol (11 mg, 0.049
mmol) in dichloromethane (2 mL) is treated with a solution of
sodium methoxide (6 mg, 0.098 mmol) in 2 mL of methanol. The
resulting solution is united with a solution of [tri(c-hexyl)phosphine]-
gold chloride (50 mg, 0.098 mmol) in dichloromethane (2 mL) with
stirring at 20 °C for 1 h. The volatiles are removed in vacuo, and
the residue is extracted with 4 mL of dichloromethane. The product
crystallizes upon addition of pentane and cooling to -20 °C (50
mg, 88% yield).
C48H74Au2P2S2 (1171.12) Calcd: C, 49.23; H, 6.37; Au, 33.64%.
Found: C, 48.72; H, 6.23; Au, 33.37%. NMR (CD2Cl2, 20 °C):
31P{1H} 57.9, s; 1H 1.10-2.70, m, 66 H, C6H11, 7.25 and 7.47, d,
J ) 8.38, 8 H, (C6H4)2S2; 13C{1H} 30.83, s; 25.96, 27.07, and 33.35,
with J ) 1.6, 11.9, and 28.0 Hz, C6H11; 125.7, 132.3, 135.5, and
142.0, all s, for (C6H4)2(S)2. MS(FAB): m/e ) 1170.7 (37.1%)
[M]+.
Acknowledgment. This work was supported by Fonds
der Chemischen Industrie, Deutsche Forschungsgemein-
schaft, Volkswagenstiftung, Deutscher Akademischer Aus-
tauschdienst, Degussa AG, and Heraeus GmbH.
Supporting Information Available: Atomic coordinates, bond
lengths and angles, atomic displacement parameters, hydrogen
coordinates, and torsion angles (CIF).
IC020107I
Inorganic Chemistry, Vol. 41, No. 14, 2002 3727