Syntheses and structures of dinuclear gold(I) dithiophosphonate complexes and the reaction of the dithiophosphonate complexes with phosphines: Diverse coordination types

Article abstract of DOI:10.1021/ic034114y

The dinuclear gold(I) dithiophosphonate complex, [Au₂(dtp) ₂] (1), where dtp = [S₂P(R)(OR′)]^- with R = p-C₆H₄-OCH₃; R′ = c-C ₅H₉, has been synthesized and its reaction studied with the phosphine ligands PPh₃ and Ph₂P(CH₂) _n-PPh₂ (n = 1-4). Compound 1 contains two gold atoms homobridged by the anionic dithiophosphonate ligand, forming an eight-membered ring complex in a chair form. After the reaction of 1 with diphosphine ligands, the dinuclear open-ring complexes Au₂(dppm)(dtp)₂ (2), Au₂(dppe)(dtp)₂ (3), Au₂(dppp)(dtp) ₂ (4), Au₂(dppb)(dtp)₂ (5) were formed (dppm = diphenylphosphinomethane; dppe = diphenylphosphinoethane; dppp = diphenylphosphinopropane; dppb = diphenylphosphinobutane). The reaction with dppm is stoichiometry-dependent. Thus, when 1 reacts with 2 equiv of dppm, the ionic complex [Au₂(dPPM)₂(dtp)]dtp forms. This dtp counterion was exchanged with tetrafluoroborate to yield [Au ₂(dppm)₂(dtp)]BF₄, the crystallization of which afforded two interconvertible isomers, 6-yellow and 7-white. Reaction of 1 with PPh3 affords the tetracoordinate mononuclear complex [Au(dtp)(PPh ₃)₂] (8). The molecular structures of 1-8 were confirmed by X-ray crystallography and show multiple coordination modes and geometries. The crystal structures of 1 and its reaction products with dppm (2, 6, 7) show short intramolecular Au...Au aurophilic bonding interactions of 2.95-3.10 A while no intermolecular interactions were discernible. However, reaction products of 1 with longer-chain Ph₂P(CH₂) _nPPh₂ ligands, n = 2-4, exhibit structures that lack both intra- and intermolecular Au...Au interactions.

Full text of DOI:10.1021/ic034114y

Inorg. Chem. 2003, 42, 5311−5319
Syntheses and Structures of Dinuclear Gold(I) Dithiophosphonate
Complexes and the Reaction of the Dithiophosphonate Complexes with
Phosphines: Diverse Coordination Types
,§
Angelo Maspero,†,‡ Ibrahim Kani,† Ahmed A. Mohamed,† Mohammad A. Omary,*
,†
Richard J. Staples,| and John P. Fackler, Jr.*
Department of Chemistry and Laboratory for Molecular Structure and Bonding,
Texas A&M UniVersity, P.O. Box 30012 College Station, Texas 77842-3012, Dipartimento di
Scienze Chimiche, Fisiche e Matematiche, UniVersita' dell'Insubria, Via Valleggio 11,
22100 Como, Italy, Department of Chemistry, UniVersity of North Texas, P.O. Box 305070,
Denton, Texas 76203, and Department of Chemistry and Chemical Biology, HarVard UniVersity,
12 Oxford Street, Cambridge, Massachusetts 02138
Received January 31, 2003
The dinuclear gold(I) dithiophosphonate complex, [Au2(dtp)2] (1), where dtp ) [S P(R)(OR′)]- with R ) p-C H -
2
6 4
OCH ; R′) c-C H , has been synthesized and its reaction studied with the phosphine ligands PPh and Ph2P(CH ) -
3
5
9
3
2 n
PPh2 (n ) 1−4). Compound 1 contains two gold atoms homobridged by the anionic dithiophosphonate ligand,
forming an eight-membered ring complex in a chair form. After the reaction of 1 with diphosphine ligands, the
dinuclear open-ring complexes Au2(dppm)(dtp)2 (2), Au2(dppe)(dtp)2 (3), Au2(dppp)(dtp)2 (4), Au2(dppb)(dtp)2 (5)
were formed (dppm ) diphenylphosphinomethane; dppe ) diphenylphosphinoethane; dppp ) diphenylphosphi-
nopropane; dppb ) diphenylphosphinobutane). The reaction with dppm is stoichiometry-dependent. Thus, when 1
reacts with 2 equiv of dppm, the ionic complex [Au2(dppm)2(dtp)]dtp forms. This dtp counterion was exchanged
with tetrafluoroborate to yield [Au (dppm)2(dtp)]BF , the crystallization of which afforded two interconvertible isomers,
2
4
6-yellow and 7-white. Reaction of 1 with PPh3 affords the tetracoordinate mononuclear complex [Au(dtp)(PPh3)2]
(8). The molecular structures of 1−8 were confirmed by X-ray crystallography and show multiple coordination
modes and geometries. The crystal structures of 1 and its reaction products with dppm (2, 6, 7) show short
intramolecular Au‚‚‚Au aurophilic bonding interactions of 2.95−3.10 Å while no intermolecular interactions were
discernible. However, reaction products of 1 with longer-chain Ph2P(CH ) PPh2 ligands, n ) 2−4, exhibit structures
2 n
that lack both intra- and intermolecular Au‚‚‚Au interactions.
Introduction
of this class include dithiophosphates, dithiophosphonates,
and dithiophosphinates. Generally, organophosphor-l,l-dithi-
olate ligands can be synthesized as ammonium salts by
reacting Lawesson’s reagent, [S2P(p-C6H4OMe)]2, with the
Gold(I) thiolate complexes have been used in a variety of
applications in modern technology1 such as photosensitizers
for photographic emulsions2 and luminescence-based chemi-
cal sensors.3 A variety of gold(I) thiolate and phosphine
thiolate complexes of potential application in medicine such
as Auranofin, Solganol, and Myochrysine have been used
for the treatment of rheumatoid arthritis in humans as well
as skin disease in cats and dogs.4-6 Thiophosphorus ligands
represent an important class of S-donor ligands. Members
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* Corresponding author. E-mail: fackler@mail.chem.tamu.edu.
† Texas A&M University.
‡ Universita' dell'Insubria.
§ University of North Texas.
| Harvard University.
10.1021/ic034114y CCC: $25.00 © 2003 American Chemical Society
Published on Web 07/31/2003
Inorganic Chemistry, Vol. 42, No. 17, 2003 5311

Maspero et al.
(OR′)]2 (R ) Ph, R′ ) Et; R ) p-C6H4OCH3, R′ ) SiPh3;
R ) Ph, R′ ) C5H9; R ) p-C6H4OMe, R′ ) (1S,5S,2S)-
(-)-menthyl), and R ) Fc, R′ ) (CH2)2O(CH2)2OMe).16
Organophosphor-1,1-dithiolato ligands, which coordinate
to two or more metal atoms, lead to supramolecular associa-
tions. In such cases, the ligand participates in primary bond
formation while additional interactions (such as metal-metal
interactions in d10 elements) may lead to dimeric, trimeric,
or supramolecular association. The presence of metal-metal
interactions was reported in Au(I) complexes17 through
aurophilic metal-metal bonding.18 Homobridged and het-
erobridged Au(I) dimers with dithiolate,19 dithiocarbamate,3,20
and diphosphine21 ligands have been reported. The photo-
physical properties of these complexes are of interest due to
the large polarizability of metal-ligand bonds and the
observation of visible luminescence properties in many d10
closed-shell complexes.22,23
Here we report the synthesis of the dinuclear dithiophos-
phonatogold(I) complex [AuS2P(p-C6H4OCH3)(O-c-C5H9)]2
and its reactions with a series of phosphine ligands that
includes bis(diphenylphosphino)methane (dppm), bis(diphen-
ylphosphino)ethane (dppe), bis(diphenylphosphino)propane
(dppp), bis(diphenylphosphino)butane (dppb), and triphen-
ylphosphine. All compounds have been characterized by
X-ray crystallography, NMR spectroscopy, and chemical
appropriate alcohol in benzene by bubbling NH3(g) through
the solution.7
Dithiophosphonate complexes are known to possess
biologically important properties8 and may also inhibit
hydrocarbon oxidation.9 O-Benzyl and O-allyl dithiophos-
phonates have been used as insecticides10 and nemato-
cides.11,12 Dithiophosphonates of the general formula ArO-
(R)P(S)SH (ArO ) hindered phenolic group, R ) alkoxy,
amino, alkylthio) and their salts are useful as antioxidants
in lubricants and plastics.13 The coordination patterns,
molecular structures, and supramolecular associations in
dithiophosphates, [S2P(OR)2]-, dithiophosphinates, [S2PR2]-,
and related compounds have been reviewed by Haiduc;14
however, only few reports are available on the chemistry of
dithiophosphonates and their complexes. The synthesis and
characterization of dithiphosphonates with some metals such
as Cu(I) and Cr(III) have been reported. The structures of
new copper bis(4-ethoxyphenyl-O-alkyl)dithiophosphonate
and chromium tris(4-ethoxyphenyl-O-methyl, -ethyl, or -iso-
propyl)dithiophosphonate complexes were reported by Haid-
uc et al.15 Our group has reported the first dinuclear Au(I)
dithiophosphonate (dtp) complexes of the type [AuS2PR-
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5312 Inorganic Chemistry, Vol. 42, No. 17, 2003

Dinuclear Gold(I) Dithiophosphonate Complexes
Scheme 1. Reaction Products of 1 with dppm (2), dppe (3), dppp (4), and dppb (5)
analysis. The multiple coordination modes and geometries
in these dinuclear Au(I) complexes and the relationship
between Au‚‚‚Au interactions and the length of the alkyl
chain in the bridging diphosphine ligand are discussed.
products were obtained depending upon the dppm/Au ratio
employed (Scheme 2). With a dppm/Au stoichiometric ratio
of 1:1, a white product characterized as [Au2(dppm)(dtp)2]
(2) was isolated. If the reaction is carried out with an excess
of dppm (dppm/Au > 3:2), a bright yellow solid is obtained
characterized as the cationic complex [Au2(dppm)2(dtp)](dtp).
The cationic complex can be also obtained by reaction of 2
with dppm, suggesting the intermediacy of 2 in the formation
of [Au2(dppm)2(dtp)](dtp). Suspending the cationic complex
in diethyl ether leads to the dissociation of one dppm ligand
with the regeneration of 2.
Results
Synthesis of 1. The reaction of Au(tht)Cl with NH4(dtp)
in dichloromethane at room temperature affords a dull yellow
product characterized as [Au2(dtp)2] (1) (dtp ) S2P(p-C6H4-
OCH3)(O-c-C5H9); tht ) tetrahydrothiophene). The dithio-
phosphonates, due to asymmetry at P, allow the formation
of syn- and anti-geometric isomers of [Au2(dtp)2]. NMR
spectroscopy was used to elucidate the structure of 1 in
solution versus the solid state. The 31P{1H} NMR spectrum
of the synthesized product in CDCl3 at room temperature
shows sharp singlets at 102.8 and 100.9 ppm with a relative
intensity of about 1:1.5. These peaks can be associated with
a mixture of syn- and anti-isomers of 1. This observation is
consistent with the literature.16c In contrast, the solid-state
31P{1H} NMR spectrum of 1 at 293 K shows only one signal
at 95.4 ppm. On the basis of these spectral data, it has been
concluded that only one type of isomer is present in the
crystal, which was later shown by X-ray crystallography as
the anti-isomer (vide infra). 31P{1H} NMR spectra for crystals
of 1 in CDCl3 show sharp singlets at 102.8 and 100.9 ppm.
Reaction of 1 with Phosphines. Compound 1 reacts in
dichloromethane solution with the diphosphine ligands dppm,
dppe, dppp, and dppb to yield the neutral dinuclear com-
plexes Au2(dppm)(dtp)2 (2), Au2(dppe)(dtp)2 (3), Au2(dppp)-
(dtp)2 (4), and Au2(dppb)(dtp)2 (5), respectively; Scheme 1.
The reaction products show that the cyclic eight-membered
ring compound 1 forms open-chain dinuclear structures with
all of the bridged diphosphine ligands used here. The
Au‚‚‚Au intramolecular interaction was maintained only with
the dppm ligand in 2 while the longer methylene chains in
dppe, dppp, and dppb precluded such interaction in 3-5.
The reaction between 1 and dppm is dependent on the
stoichiometric ratio of the components. Two different
The 31P{1H} NMR spectrum of 2 in CDCl3 at room
temperature shows two sharp signals: a singlet at 100 ppm
associated with the two magnetically equivalent dtp ligands
and a second singlet at 30 ppm associated with two
magnetically equivalent dppm ligands. The spectral features
do not change appreciably on lowering the temperature to
198 K. The NMR data for 2 are consistent with a dinuclear
gold(I) complex with a dppm bridge between two metal
centers, consistent with the X-ray data (vide infra). The
coordination sphere of each Au(I) is saturated by two
monodentate dtp ligands coordinated by only one sulfur atom.
The structure of the cationic complex [Au2(dppm)2(dtp)]-
(dtp) in the solid state and solution was confirmed by NMR
spectroscopy and X-ray crystallography. The crystal structure
of [Au2(dppm)2(dtp)](dtp) is similar to that of [Au2(dppm)2-
(dtp)]BF4 but highly disordered particularly at the dtp
counteranion. The crystal structure of the latter compound
is discussed below. The X-ray structure of [Au2(dppm)2(dtp)]-
(dtp) shows that the two gold(I) centers are held together by
one dtp ligand and two dppm bridges, giving rise to a three-
coordinate environment for each gold(I) center (Scheme 2).
The behavior of the complex in solution is more complex.
NMR spectra suggest a structure in solution different from
that in the solid state. The 31P{1H} NMR spectrum of [Au2-
(dppm)2(dtp)](dtp) in CDCl3 at room temperature shows two
peaks; a sharp singlet at 102.6 ppm due to the dtp ligand,
and a broad band centered at 27.6 ppm due to the dppm
Inorganic Chemistry, Vol. 42, No. 17, 2003 5313

Maspero et al.
Scheme 2. Reaction Pathways of 1 with PPh3 and Different Mole Ratios of dppm
ligand. The presence of only one peak for the dtp ligands
and unresolved signals for the dppm ligands suggests the
presence of a fast ligand-exchange equilibrium in solution.
Consistent with this suggestion, the spectral features of the
cationic complex change drastically upon lowering the
temperature. In fact, the 31P{l H} NMR spectrum in CD2-
C12 at T ) 173 K is in agreement with the solid state
structure with sharp singlets at 29.6, 101.3, and 105.4 ppm.
The resonance at 29.6 ppm is assigned to the two dppm
ligands coordinated to the metal centers. The 101.3 ppm peak
is assigned to a bridging dtp ligand coordinated to the two
gold(I) atoms while the sharp singlet at 105.4 ppm is assigned
to the dtp- counterion (Scheme 2). Consistent with the three-
coordinate arrangement of the cationic complex is its strong
green luminescence at room temperature while the linear
2-coordinate complex 2 shows strong luminescence only at
78 K.23 Details of the luminescence studies for compounds
in this paper will be the subject of a future paper.
the structure denoted as 6-yellow while crystals grown from
CH2Cl2/n-hexane are colorless and have the structure denoted
as 7-white in Scheme 2. The X-ray data show that the dtp
ligand in the isomer 6-yellow is coordinated as a bridge with
each of the two sulfur atoms bonded to a different gold(I)
center. In contrast, the colorless crystals of isomer 7-white
have the dtp ligand coordinated as a chelate with both sulfur
atoms bonded to only one gold(I) atom. The structures shown
in Scheme 2 are also consistent with the NMR data.
Furthermore, we have noticed that heating the white powder
of [Au2(dppm)2(dtp)]BF4 (7-white) converts it to a bright
yellow powder, 6-yellow. While the two isomers 6-yellow
and 7-white are distinguishable in the solid state (the water
content of crystals of 7-white is higher than for crystals of
6-yellow), solutions of both isomers in CDCl3 give essentially
identical 31P{1H} NMR spectra. Compound 7-white rear-
ranges to 6-yellow in solvents such as acetone, THF,
dichloromethane, ethanol, DMSO, acetonitrile, and chloro-
form.
Because of the ionic nature of the compound [Au2(dppm)2-
(dtp)](dtp), we decided to exchange the dtp counterion with
Also illustrated in Scheme 2 is the reaction of 1 with
triphenylphosphine. Thus, addition of 4 equiv of PPh3 to a
solution of 1 in dichloromethane at room temperature leads
to the formation of a stable species characterized as [Au-
(dtp)(PPh3)2] (8). As confirmed by X-ray crystallography,
the gold(I) atom is coordinated by two PPh3 ligands and by
two sulfur atoms of the dtp ligand in a distorted tetrahedral
geometry. The 31P{1H} NMR solid-state spectrum of 8 at
room temperature is in agreement with the X-ray structure
as it shows two sharp singlets at 35.5 (due to the PPh3 ligand)
and 106.6 ppm (due to dtp chelating ligand). The solution
31P{lH} NMR spectrum of 8 (room temperature, CD2Cl2)
shows a peak at 99.0 ppm, assigned to the chelated dtp, and
another signal at 18.4 ppm. This chemical shift is perturbed
by adding PPh3. The 31P{1H} NMR of 8 at room temperature
in CD2Cl2 after adding PPh3 shows two peaks, one at 99.8
ppm due to dtp and the other at 7.0 ppm due to free PPh3.
This confirms that there is an equilibrium between 8 and a
new species [Au(PPh3)(dtp)] in solution. These spectral
-
a more conventional counterion such as BF4 . Thus, reaction
of the bright yellow solid [Au2(dppm)2(dtp)](dtp) with
tetrafluoroboric acid at room temperature in methanol leads
to a white product that is characterized as [Au2(dppm)2(dtp)]-
BF4. The IR spectrum of the white solid shows a broad band
(1070 cm-1) typical of the tetrafluroborate anion absorption.
The 31P{1H} NMR spectrum in CD3OD at room temperature
shows two peaks: a singlet centered at 30.6 ppm assigned
to the dppm and another singlet centered at 101.8 ppm
assigned to the dtp ligand. The solution behavior of [Au2-
(dppm)2(dtp)]BF4 is rather different from that of [Au2-
(dppm)2(dtp)](dtp) as the NMR spectral features do not
change appreciably on lowering the temperature to 178 K.
The differences in color and 31P{1H} NMR data between
[Au2(dppm)2(dtp)](dtp) and [Au2(dppm)2(dtp)]BF4 suggest
different X-ray structures. Interestingly, while trying to
crystallize [Au2(dppm)2(dtp)]BF4 from different solvent
combinations, two isomers have been obtained. Crystals
grown from CH2Cl2/diethyl ether are bright yellow and have
5314 Inorganic Chemistry, Vol. 42, No. 17, 2003

Dinuclear Gold(I) Dithiophosphonate Complexes
features change upon lowering the temperature. At 183 K,
broad bands centered at 102.2 and 37.9 ppm are present.
Structures. Compounds 1-8 have been characterized by
single-crystal X-ray crystallography. Table 1 shows the
crystal data for these compounds. Selected bond lengths and
angles are listed in Tables 2-9. Thermal ellipsoid drawings
are shown in Figures 1-8.
Compound 1 crystallizes in the monoclinic space group
P21/c with an inversion center between the two gold atoms.
An ORTEP drawing of 1 is shown in Figure 1 and selected
bond distances and angles are listed in Table 2. The two
linear S-Au-S fragments are parallel; they do not “cross”.
There are numerous examples of dinuclear Au(I) cyclic
complexes where the linear coordination around the gold
center is maintained.19-21,24 Among these, eight-membered
ring Au(I) complexes are the best examples available to
examine the effect of intramolecular Au‚‚‚Au interactions.
However, intermolecular Au‚‚‚Au interactions may or may
n- 25
not exist in complexes such as [Au(dithiolate)]2
with
- 26
2- 27
dithiolate ) S2P(OR)2 , S2C2(CN)2
,
S2PR2,28 S2CS,29
and S2PR(OR),16b with R ) alkyl, n ) 0, 2. Many of which
are known to form polymeric chains with both intra- and
intermolecular Au‚‚‚Au interactions. Compound 1 shows a
typical elongated chair molecular conformation with a short
Au‚‚‚Au interaction, 3.1002(4) Å. This weak Au‚‚‚Au
interaction has been attributed to correlation effects that are
enhanced by relativistic effects, to mixing and hybridization,
or both, between the 6s and 5d orbitals.18,30 Contrary to what
is observed for [AuS2PPh2],28,31 {[Au(i-C3H7)2PS2]2}n,26 and
[PPN]2[Au2(µ2-η2-S2CS)2],29 packing of the dimers in the
unit cell of 1 is not associative. There are no close
intermolecular contacts between gold atoms (the shortest
Au‚‚‚Au distance is 6.814 Å) or between the gold and sulfur
atoms of adjacent molecules.
The two Au(I) atoms in 2 (Figure 2) are bridged by one
dppm ligand. The Au- S and Au-P bond lengths and angles
are typical of phosphine gold(I) thiolate complexes (Table
2).22,32 The two gold atoms are at a separation of 3.0353(3)
Å, well within the range of aurophilic bonding, somewhat
shorter than the distance of 3.351 Å found in [Au2(dppm)-
C12],33 and close to the distances found in [dppm{Au-
(24) (a) Fernandez, E. J.; Lo´pez-de-Luzuriga, J. M.; Monge, M.; Rodriguez,
M. A.; Crespo, M. O.; Gimeno, M. C.; Laguna, A.; Jones, P. G. Inorg.
Chem. 1998, 37, 6002. (b) Davila, M. R.; Eldugue, A.; Grant, T.;
Staples, R. J.; Fackler, J. P., Jr. Inorg. Chem. 1993, 32, 1749. (c) Tang,
S. S.; Chang, C.-P.; Lin, I. J. B.; Liu, L.-S.; Wang, J.-C. Inorg. Chem.
1997, 36, 2294.
(25) Heinrich, D. D.; Wang, J. C.; Fackler, J. P., Jr. Acta Crystallogr. 1990,
C46, 1447.
(26) Lawton, S. L.; Rohrbaugh, W. J.; Kokotailo, G. T. Inorg. Chem. 1972,
11, 2227.
(27) Khan, M. N. I.; Fackler, J. P., Jr.; King, C.; Wang, J. C.; Wang, S.
Inorg. Chem. 1988, 27, 1672.
(28) van Zyl, W. E.; Lo´pez-de-Luzuriga, J. M.; Fackler, J. P., Jr.; Staples,
R. J. Can. J. Chem. 2001, 79, 896.
(29) Vicente, J.; Chicote, M.-T.; Herrero, P. G.; Jones, P. G. J. Chem. Soc.,
Chem. Commun. 1995, 745.
(30) Jiang, Y.; Alvarez, S.; Hoffmann, R. Inorg. Chem. 1985, 24, 749.
(31) Siasios, G.; Tiekink, E. R. T. Z. Kristallogr. 1995, 210, 698.
(32) (a) Davila, R. M.; Staples, R. J.; Eldugue, A.; Harlass, M.; Kyle, L.;
Fackler, J. P., Jr. Inorg. Chem. 1994, 33, 5940. (b) Gimeno, M. C.;
Jones, P. G.; Laguna, A.; Laguna, M.; Terroba, R. Inorg. Chem. 1994,
33, 3932.
Inorganic Chemistry, Vol. 42, No. 17, 2003 5315

Maspero et al.
Figure 1. Thermal ellipsoid drawing of 1 with 50% probability. Hydrogen
atoms are omitted for clarity.
Figure 3. Thermal ellipsoid drawing of 3 with 50% probability. Hydrogen
atoms are omitted for clarity.
Figure 2. Thermal ellipsoid drawing of 2 with 50% probability. Hydrogen
atoms are omitted for clarity.
Figure 4. Thermal ellipsoid drawing of 4 with 50% probability. Hydrogen
atoms are omitted for clarity.
Table 2. Selected Bond Distances (Å) and Angles (deg) of 1
Au(1)-S(2)
2.2973(16) S(2)-P(1)
2.3020(16) S(1)-P(1A)
3.1002(4)
2.0201(19)
2.020(2)
Au(1)-S(1)
Au(1)‚‚‚Au(1A)
S(2)-Au(1)-S(1)
171.49(5) P(1)-S(2)-Au(1)
102.24(8)
S(2)-Au(1)‚‚‚Au(1A) 93.75(4)
P(1A)-S(1)-Au(1)
S(1)-Au(1)‚‚‚Au(1A) 94.75(4)
101.44(8) S(1A)-P(1)-S(2)
116.83(9)
(SSNH2)}2]‚2DMF34 (3.099 Å) and similar com-
pounds.3,30,32,33,35 The torsion angle defined by Au(1)-
P(1)‚‚‚P(2)-Au(2) in 2 is -16.2°.
The two P-Au-S fragments in 3-5 adopt an anti-
geometry (Figures 3-5). The Au-S distance of ∼3.5-3.8
Å is normal for a secondary Au‚‚‚S interaction. Selected bond
distances and angles for 3-5 are listed in Tables 3-5.
The asymmetric unit of 6-yellow has two independent but
closely similar formula units, the cation of one of which is
Figure 5. Thermal ellipsoid drawing of 5 with 50% probability. Hydrogen
atoms are omitted for clarity.
(33) Schmidbaur, H.; Wohlleben, A.; Wagner, F.; Orama, O.; Huttner, G.
Chem. Ber. 1977, 110, 1748.
(34) Tzeng, B.-C.; Schier, A.; Schmidbaur, H. Inorg. Chem. 1999, 38, 8,
3978.
(35) (a) King, C.; Wang, J.-C.; Khan, M. N. I.; Fackler, J. P., Jr. Inorg.
Chem. 1989, 28, 2145. (b) Hao, L.; Lachicotte, R. J.; Gysling, H. J.;
Eisenberg, R. Inorg. Chem. 1999, 38, 4616.
shown in Figure 6. Both molecules consist of two gold atoms
bridged by two diphosphines and one dtp ligand. They show
short intramolecular gold-gold contacts of 2.9556(6) Å
5316 Inorganic Chemistry, Vol. 42, No. 17, 2003

Dinuclear Gold(I) Dithiophosphonate Complexes
Figure 7. Thermal ellipsoid drawing of the cation of 7-white with 50%
probability. Hydrogen atoms are omitted for clarity.
Figure 6. Thermal ellipsoid drawing of the cation of 6-yellow with 50%
probability. Hydrogen atoms are omitted for clarity.
Table 8. Selected Bond Distances (Å) and Angles (deg) of 7
Table 3. Selected Bond Distances (Å) and Angles (deg) of 2
Au(1)‚‚‚Au(1A)
Au(1)-S(2)
3.0428(8)
2.880(4)
2.841(4)
P(2)-Au(1)
S(1)-P(1A)
2.346(4)
1.983(5)
Au(1)-P(3)
Au(1)-S(1)
Au(1)‚‚‚Au(2)
2.2587(14) Au(2)-P(4)
2.3138(15) Au(2)-S(3)
2.2664(15)
2.3151(17)
2.053(2)
Au(1)-S(1)
P(4)-Au(1)-P(2)
P(2)-Au(1)-S(1)
151.87(14) P(4)-Au(1)-S(1)
91.66(12)
112.84(13)
72.08(11)
3.0353(3)
S(1)-P(1)
S(1)-Au(1)-S(2)
S(1)-Au(1)‚‚‚Au(2) 137.54(8)
P(3)-Au(1)-S(1)
175.08(6)
S(1)-Au(1)‚‚‚Au(2) 91.04(4)
P(4)-Au(2)‚‚‚Au(1) 83.53(4)
P(3)-Au(1) ‚‚‚Au(2) 93.70(4)
P(4)-Au(1)‚‚‚Au(2) 89.77(10)
P(4)-Au(2)-S(3)
176.76(6)
99.37(5)
P(5)-Au(2)-P(3)
171.97(13) S(1)-P(1)-S(2)
115.3(2)
S(3)-Au(2)‚‚‚Au(1)
Table 4. Selected Bond Distances (Å) and Angles (deg) of 3
The coordination of the two dppm ligands to gold constitutes
a boat conformation. The angles at P-Au-P are 154.95-
(9)° and 165.13(9)°. The dihedral angle between P(2)-
Au(1)-P(4) and P(3)-Au(2)-P(5) is 16.1°. The Au-P bond
distances lie in the range 2.300(3)-2.347(3) Å.
Au(1)-P(1)
Au(1)-S(1)
P(2)-O(1)
2.2580(10)
2.3207(10)
1.608(3)
S(1)-P(2)
S(2)-P(2)
O(1)-C(14)
2.0489(16)
1.9450(16)
1.483(5)
P(2)-S(1)-Au(1)
S(1)-P(2)-S(2)
97.50(5)
114.36(13)
P(1)-Au(1)-S(1)
O(1)-P(2)-C(19)
176.52(4)
105.33(16)
The structure of 7-white (Figure 7) is similar to that of
[Au2(PhCS2)(µ-dppm)2]C1.36 The dithiophosphonate is che-
lated to only one center with Au-S ) 2.880(4) and 2.841-
(4) Å. The [Au2(dppm)2]+ unit adopts a boat conformation,
and the P-Au-P angle is shifted from linearity to 151.87-
(14)° at the gold center that is connected to the dtp ligand;
while the angle at the other gold center is 171.97(13)° (Table
8). The coordination around the gold atom coordinated to
dtp is nearly tetrahedral. The Au‚‚‚Au distance is 3.0428(8)
Å, similar to the distance in [Au2(PhCS2)(µ-dppm)2]Cl,
Au‚‚‚Au ) 3.0176(5) Å.
The gold atom in 8 is pseudotetrahedrally coordinated by
the two triphenylphosphines and the chelating dtp ligand
(Figure 8). The angles at P-Au-P and S-Au-S are 138.3-
(2)° and 73.10(19)°, respectively (Table 9). The Au-S bond
distances in the chelate ring, 2.810(6) and 2.829(6) Å, are
similar to those in 6-yellow and 7-white.
Table 5. Selected Bond Distances (Å) and Angles (deg) of 4
Au(1)-P(1)
Au(2)-P(3)
Au(2)-S(3)
2.247(2)
2.253(3)
2.315(3)
Au(1)-S(1)
S(1)-P(2)
P(2)-O(1)
2.315(2)
2.039(4)
1.589(9)
P(1)-Au(1)-S(1)
P(2)-S(1)-Au(1)
176.45(9)
100.22(13)
P(3)-Au(2)-S(3)
P(4)-S(3)-Au(2)
177.24(10)
102.36(14)
Table 6. Selected Bond Distances (Å) and Angles (deg) of 5
Au(1)-P(1)
Au(1)-S(1)
2.233(3)
2.306(3)
S(1)-P(2)
P(2)-O(1)
2.055(4)
1.594(8)
P(1)-Au(1)-S(1)
O(1)-P(2)-S(1)
175.61(9)
103.3(3)
P(2)-S(1)-Au(1)
C(20)-P(2)-S(1)
98.69(14)
108.0(4)
Table 7. Selected Bond Distances (Å) and Angles (deg) of 6
Au(1)-P(4)
Au(1)-P(2)
Au(1)-S(1)
Au(1)‚‚‚Au(2)
2.307(3)
2.318(3)
2.899(3)
2.9556(6)
Au(2)-P(3)
Au(2)-P(5)
Au(2)-S(2)
S(1)-P(1)
2.300(3)
2.347(3)
2.708(3)
1.992(5)
P(4)-Au(1)-P(2)
P(2)-Au(1)-S(1)
P(2)-Au(1)‚‚‚Au(2)
P(3)-Au(2)-P(5)
P(5)-Au(2)-S(2)
P(5)-Au(2)‚‚‚Au(1)
165.13(9)
83.29(9)
89.87(7)
154.95(9)
86.81(9)
87.47(8)
P(4)-Au(1)-S(1)
P(4)-Au(1)‚‚‚Au(2)
S(1)-Au(1)‚‚‚Au(2)
P(3)-Au(2)-S(2)
P(3)-Au(2)‚‚‚Au(1)
S(2)-Au(2)‚‚‚Au(1)
111.23(9)
94.14(8)
86.24(7)
118.17(9)
92.86(7)
92.79(8)
Discussion
The structural results for the phosphine derivatives of 1
show that each gold atom in 2-5 is two-coordinate and
linearly bonded to a sulfur of the dtp ligand and one of the
P atoms of the bridged diphosphine ligand. Compounds 2-5
show neither sulfur chelation to the Au(I) atoms nor any
discernible intermolecular gold-sulfur interaction. Com-
(Table 7), which is similar to that found in [Au2(S2-
CNEt2)(dppm)2][BH3CN], 2.949(1) Å.21k The Au-S bond
distances, 2.899(3) and 2.708(3) Å, are longer than those in
[Au2(S2CNEt2)(dppm)2][BH3CN] (2.648(3) and 2.703(3) Å).
(36) Wang, J.-C.; Liu, L.-K. Acta Crystallogr. 1994, C50, 704.
Inorganic Chemistry, Vol. 42, No. 17, 2003 5317

Maspero et al.
nate. The characterized gold complexes are diverse in their
coordination types about the gold(I) centers such as tetra-
hedral, distorted trigonal (T-shape) in addition to the known
linear coordination. Some of the isolated complexes show
strong orange, yellow, and green luminescence at room
temperature and at 77 K. Details of the luminescence studies
for compounds in this paper will be the subject of a future
paper.
Experimental Section
Au(tht)Cl was prepared by literature methods.39 Solvents were
dried and distilled under dry oxygen-free nitrogen prior to use; all
other chemicals were obtained from commercial sources and used
as received. All reactions were carried out under an inert atmosphere
using standard Schlenk techniques.40 1H and 31P{ 1H} NMR spectra
were obtained using a Unity Plus 300 spectrometer operating at
300 MHz for proton spectra. The chemical shifts in the 31P{1H}
NMR spectra are reported relative to 85% H3PO4 in D2O.
Figure 8. Thermal ellipsoid drawing of 8 with 50% probability. Hydrogen
atoms are omitted for clarity.
Synthesis of NH4[S2P(p-C6H4OMe)(O-c-C5H9)], NH4(dtp). A
4.46-g (0.011 mmol) sample of Lawesson’s reagent [S2P(µ-C6H4-
OMe)]2 was dissolved in 30 mL of distilled benzene, and 2.2 mL
(2.24 × 10-2 mmol) of C5H9OH was added via a syringe. The
suspension was refluxed at 80 °C for 3 h. The solution was then
cooled in an ice bath for 20 min. Anhydrous NH3 (g) was slowly
bubbled through the solution with vigorous agitation. The white
precipitate was filtered, washed with diethyl ether, and dried under
vacuum; yield 5.4 g (90%). Anal. Calcd for C12H20NO2PS2: C,
47.21; H, 6.56; S, 20.98. Found: C, 46.68; H, 6.26; S, 21.30. 31P-
{1H} NMR (300 MHz, CDCl3): 104.54 ppm (s).
Table 9. Selected Bond Distances (Å) and Angles (deg) of 8
Au(1)-P(3)
Au(1)-S(2)
2.326(4)
2.803(4)
Au(1)-S(1)
Au(1)-P(2)
2.849(5)
2.324(5)
P(3)-Au(1)-P(2)
P(2)-Au(1)-S(1)
P(3)-Au(1)-S(1)
137.70(15)
97.35(15)
112.13(16)
P(3)-Au(1)-S(2)
S(1)-Au(1)-S(2)
102.12(14)
73.17(13)
pounds 6-8 show relatively uncommon coordination num-
bers for gold(I)-sulfur complexes of three, 6-yellow, and
four, 7-white and 8, around the gold atoms. The chelation
of the dtp to one of the gold atoms in 7-white is found to
generate some steric strain and causes the sulfur atoms of
the dtp ligand to be involved in a dynamic process. The
structural result is the observation of 6 and 7.
Synthesis of [Au(µ-dtp)]2 (1). A 0.318-g (0.99 mmol) sample
of Au(tht)Cl was dissolved in 15 mL of CH2Cl2, and 0.302 g (0.99
mmol) of NH4[dtp] was added in one portion. The resulting mixture
was stirred for 20 min in the dark at 0 °C, and then the solution
was stirred an additional 2 h under reduced pressure at room
temperature. The NH4Cl salt was filtered, and the volume of the
filtrate was reduced to 2 mL. The product was precipitated by
adding 50 mL of diethyl ether and filtered. The product was washed
with distilled water to remove any NH4Cl residue and dried under
vacuum for 1 h. The dull yellow product was obtained in an 83%
yield (0.396 g). Crystals suitable for X-ray analysis were obtained
by a slow diffusion of n-hexane or diethyl ether into a dichlo-
The packing diagrams of 2-8 show no close aurophilic
intermolecular interactions with Au(I)‚‚‚Au(I) distances well
beyond the normal range for such interactions. The coordina-
tion at each Au(I) center in 2-5 is, as expected, almost linear
with a P-Au-S angle of 176° (Tables 2-8). The gold-
sulfur distances from nonbonded sulfur atoms are found to
be 4.093, 3.827, 3.593, and 3.519 Å in structures 2-5,
respectively. This is longer than the nonbonded Au(I)‚‚‚S
distances found in Au(I)-dithiocarbamate complexes such
as [Au(S2CNEt2)(PPh3)], 3.105 Å.37 The P-S distances are
consistent with a PdS (1.941 Å) double bond for the
noncoordinated S atoms and a PsS (2.048 Å) single bond
for the Au(I)-S bonded sulfur atom of the dtp. The presence
of an intramolecular interaction in 2, Au‚‚‚Au ) 3.0035 Å,
shows that the dppm brings the two Au(I) centers into close
proximity. The average of P-Au and S-Au bond lengths
in 2-8 are ∼2.2 and ∼2.3 Å, respectively. This corresponds
well with the reported values in other phosphine Au(I)
thiolate complexes.38
1
romethane solution of the product. H NMR (300 MHz, CDCl3):
1.67-1.97 (m, 8H, O-c-C5H9), 3.89 (3H, OCH3), 5.42 (s, IH, O-c-
C5H9), 6.99 (d, 2H, m-C6H4OCH3), 8.1 ppm (t, 2H, o-C6H4OCH3).
31P{1H} NMR (300 MHz, CDCl3): 100.9 (s), 102.8 ppm (s). Anal.
Calcd for C24H32Au2O4P2S4: C, 29.75; H, 3.30; S, 13.22. Found:
C, 28.93; H, 3.32; S, 12.42.
Synthesis of Au2(µ-dppm)(dtp)2 (2). To a CH2C12 solution (4
mL) of 1 (107 mg, 0.11 mmol), 43 mg (0.11 mmol) of dppm was
added. The clear yellow solution turned colorless while being stirred
for 5 h at room temperature, after which the solvent was evaporated
under vacuum to 1 mL. The white solid was extracted and washed
with diethyl ether and then dried under vacuum; yield 110 mg
(74%). Crystals suitable for X-ray analysis were obtained by a slow
diffusion of n-hexane or diethyl ether into a dichloromethane
Conclusions
This study demonstrates the facile formation of phosphine
gold(I) dithiophosphonates from the reaction of mono- and
diphosphine ligands with dinuclear gold(I) dithiophospho-
(38) Narayanaswamy, R.; Young, M. A.; Parkhurst, E.; Ouellette, M.; Kerr,
M. E.; Ho, D. M.; Elder, R. C.; Bruce, A. E.; Bruce, M. R. M. Inorg.
Chem, 1993, 32, 2506.
(39) Uso´n, R.; Laguna, A. In Organometallic Syntheses; King, R. B., Eisch,
J. J., Eds.; Elsevier: Amsterdam, 1986; Vol. 3, p 322.
(40) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-SensitiVe
Compounds, 2nd ed.; Wiley: New York, 1986.
(37) Lanfredi, A. M.; Ugozzoli, F.; Asaro, F.; Pellizer, G.; Marsich, N.;
Camus, A. Inorg. Chim. Acta 1992, 192, 271.
5318 Inorganic Chemistry, Vol. 42, No. 17, 2003

Dinuclear Gold(I) Dithiophosphonate Complexes
1
solution of the product. H NMR (300 MHz, CDCl3): 1.63-1.87
for 1 h, and at the end of this period, the white complex was filtered
off, washed with water and methanol, and dried under vacuum.
Anal. Calcd for C62H60Au2BF4O2P5S2: C, 48.43; H, 3.90. Found:
C, 47.90; H, 3.77. Crystals suitable for X-ray analysis were obtained
by a slow diffusion of diethyl ether or n-hexane into a dichlo-
romethane solution of the product to yield, respectively, the yellow
crystals of 6 or the colorless crystals of 7.
Synthesis of [Au(dtp)(PPh3)2] (8). To a solution of 1 (100 mg,
0.10 mmol) in dichloromethane (5 mL), triphenylphosphine (111
mg, 0.42 mmol) was added in one portion under inert atmosphere.
The yellow reaction mixture was stirred for 2 h. At the end of this
period, the colorless solution was dried under vacuum and then
the complex was washed with diethyl ether and dried under vacuum
(80% yield). Anal. Calcd for C48H46AuO2P3S2: C, 57.14; H, 4.56.
Found C, 57.25; H, 4.72. Crystals suitable for X-ray structure
analysis were obtained by a slow evaporation of dichloromethane
solution at 293 K.
X-ray Crystallography. Data were collected using a Bruker
SMART charge-coupled device (CCD) diffractometer equipped
with an LT-3 low-temperature apparatus operating at 213 K. A
suitable crystal was chosen and mounted on a glass fiber using
grease. Data were measured using ω scans of 0.3°/frame for 10 s,
such that a hemisphere was collected. A total of 1271 frames were
collected with a maximum resolution of 0.75 Å. The first 50 frames
were recollected at the end of data collection to monitor for decay.
Cell parameters were retrieved using SMART41 software and refined
using SAINT on all observed reflections. Data reduction was
performed using the SAINT software,42 which corrects for Lp and
decay. Absorption corrections were applied using SADABS.43 The
structures are solved by the direct method using the SHELXS-9744
program and refined by a least-squares method on F2, SHELXL-
97,45 incorporated in SHELXTL V5.10.46
(m, 8H, O-c-C5H9), 4.713 (t, 2H, CH2), 3.88 (3H, O-CH3), 5.29 (s,
1H, O-c-C5H9), 6.96 (d, 2H, m-C6H4OCH3), 7.88 (t, 2H, o-C6H4-
OCH3), 7.37-7.79 ppm (m, 20H, Ph2CH2Ph2). 31P {1H} NMR (300
MHz, CDCl3): 33.17 (s, dppm), 93.12 ppm (s, dtp). Anal. Calcd
for C49H54Au2O4P4S4: C, 43.49; H, 3.99. Found: C, 43.03; H, 4.13.
Synthesis of Au2(µ-dppe)(dtp)2 (3). To a CH2Cl2 solution (10
mL) of 1 (100 mg, 0.103 mmol) was added dppe (81.99 mg, 0.107
mmol). The reaction mixture was stirred for 3 h at room temper-
ature. The solvent was concentrated under vacuum, and hexane was
added (30 mL). The white solid was filtered off, washed with
hexane, and dried under vacuum; yield 122.7 mg (81%). Crystals
suitable for X-ray analysis were obtained by a slow diffusion of
n-hexane or diethyl ether into a dichloromethane solution of the
1
product. H NMR (300 MHz, CDCl3): 1.78-1.92 (m, 8H, O-c-
C5H9), 2.79 (t, 4H, CH2), 3.83 (3H, O-CH3), 5.25 (s, 1H, O-c-
C5H9), 6.87 (d, 2H, m-C6H4OCH3), 8.14 (t, 2H, o0C6H4OCH3),
7.23-7.74 ppm (m, 20H, Ph2PCH2CH2PPh2). 31P{1H} NMR (300
MHz, CDCl3): 21.95 (s, dppe), 99.50 ppm (s, dtp).
Synthesis of Au2(µ-dppp)(dtp)2 (4). To a CH2Cl2 solution (10
mL) of 1 (100 mg, 0.103 mmol) was added dppp (85.1 mg, 0.107
mmol). After stirring for 3 h at room temperature, the solvent was
reduced under vacuum and a white precipitate formed by addition
of hexane (30 mL). The solid was filtered off, washed with hexanes,
and dried under vacuum; yield 108 mg (76%). Crystals suitable
for X-ray analysis were obtained by a slow diffusion of n-hexane
or diethyl ether into a dichloromethane solution of the product. 1H
NMR (300 MHz, CDCl3): 1.75-1.92 (m, 8H, O-c-C5H9), 2.83 (t,
2H, CH2), 1.92 (m, 2H, CH2), 3.83 (3H, O-CH3), 5.25 (s, 1H, O-c-
C5H9), 6.89 (d, 2H, m-C6H4OCH3), 8.08 (t, 2H, o-C6H4OCH3),
7.46-7.70 ppm (m 20H, Ph2CH2Ph2). 31P{1H} NMR (300 MHz,
CDCl3): 31.24 (s, dppp), 99.25 ppm (s, dtp).
Synthesis of Au2(µ-dppb)(dtp)2 (5). To a CH2C12 solution (10
mL) of 1 (100 mg, 0.10 mmol) was added dppb (88 mg, 0.21
mmol). The reaction was allowed to stir for 3 h at room temperature.
The solvent was concentrated under vacuum, and the product was
isolated upon addition of hexane (30 mL). The solid was filtered
off, washed with hexane, and dried under vacuum; yield 131 mg
(91%). Crystals suitable for X-ray analysis were obtained by a slow
diffusion of n-hexane or diethyl ether into a dichloromethane
Structures 1, 2, and 5-7 and were solved in the monoclinic space
group P21/c and 3 and 4 were solved in the triclinic space group
P-1 by analysis of systematic absences. The structure of 8 was
solved in the triclinic space group P1h. All non-hydrogen atoms were
refined anisotropically. Hydrogen atoms were calculated by geo-
metrical methods and refined as a riding model. The crystal used
for the diffraction study showed no decomposition during data
collection. All thermal ellipsoid drawings are at 50% probability.
Cyclopentanes and the counteranions (BF4-) were disordered.
1
solution of the product. H NMR (300 MHz, CDCl3): 1.76-1.89
(m 8H, O-c-C5H9), 2.41 (t, 4H, CH2), 1.92 (m, 4H, CH2), 3.82 (3H,
O-CH3), 5.25 (s, 1H, O-c-C5H9), 6.89 (d, 2H, m-C6H4OCH3), 8.10
(t, 2H, o-C6H4OCH3), 7.44-7.65 ppm (m, 20H, Ph2CH2Ph2). 31P-
{lH} NMR (300 MHz, CDCl3): 32.74 (s, dppb), 99.45 ppm (s,
dtp).
Synthesis of [Au2(µ-dppm)2(µ-dtp)](dtp). Complex 1 (100 mg;
0.10 mmol) was dissolved in 4 mL of dichloromethane, and bis-
(diphenylphosphino)methane (84 mg, 0.22 mmol) was added and
stirred under inert atmosphere. The reaction mixture was stirred
for 3 h, after which the solvent was evaporated to dryness. The
bright yellow product was treated with diethyl ether, filtered off,
and dried under reduced pressure (90% yield). Anal. Calcd for
C74H76Au2O4P6S4: C, 51.15; H, 4.38; S. 7.37. Found C, 51.12; H,
4.37; S, 7.22. Crystals suitable for X-ray structural analysis were
obtained by a slow evaporation of an acetonitrile solution of 2 at
293 K.
Acknowledgment. The Robert A. Welch Foundation of
Houston, TX is acknowledged for financial support of this
work to J.P.F. and M.A.O. The CCD-based X-ray diffrac-
tometer at Harvard University was purchased through the
NIH Grant I SlO 1RR1 1937-01.
Supporting Information Available: X-ray crystallographic
files, in CIF format, for complexes 1-8. This material is available
free of charge via the Internet at http://pubs.acs.org.
IC034114Y
(41) SMART V 5.050 (NT) Software for the CCD Detector System; Bruker
Analytical X-ray Systems, Madison, WI, 1998.
(42) SAINT V 5.01 (NT) Software for the CCD Detector System; Bruker
Analytical X-ray Systems, Madison, WI, 1998.
(43) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(44) Sheldrick, G. M. SHELXS-97, Program for the Solution of Crystal
Structure; University of Go¨ttingen, Germany, 1990.
(45) Sheldrick, G. M. SHELXL-97. Program for the Refinement of Crystal
Structure; University of Go¨ttingen, Germany, 1997.
Synthesis of [Au2(dppm)2(dtp)](BF4), 6-yellow and 7-white.
Complex [Au2(µ-dppm)2(µ-dtp)](dtp) (0.053 g, 3.5 × 10-5 mol)
was dissolved in methanol (4 mL), and fluoroboric acid in water
(60 µL of a 48 wt % solution) was added under stirring. In few
minutes, a white complex formed. The reaction mixture was stirred
(46) SHELXTL 5.10 (PC Version). Program Library for Structure Solution
and Molecular Graphics; Bruker Analytical X-ray Systems, Madison,
WI, 1998.
Inorganic Chemistry, Vol. 42, No. 17, 2003 5319