Synthesis and characterization of triphenylphosphinesilver(I) sulfanylcarboxylates of types [(AgPPh3)(HL)] and [Ag(PPh 3)3(HL)]

Article abstract of DOI:10.1002/zaac.200700005

Compounds of types [(AgPPh₃)(HL)] and [Ag(PPh₃) ₃(HL)] {H₂L = H₂xspa: x = p (3-phenyl-), t [3-(2-thienyl)-], f [3-(2-furyl)-]; spa = 2-sulfanylpropenoato} were synthesized and characterized by IR, ₁H, ₁₃C and ₃₁P NMR spectroscopy and FAB mass spectrometry. The structures of [(AgPPh ₃)(Htspa)] (2) and [Ag(PPh₃)₃(Hpspa)] (4) were determined by X-ray diffractometry. Complex 2 has a supramolecular structure based on hydrogen bonding between dinuclear units which can be seen as formed by Ag(PPh₃)(Htspa) monomers connected by Ag-S bonds, the metal atom in each monomer being O,S-chelated. Complex 4 has a mononuclear structure with Ag-S and Ag-P bonds and an intramolecular hydrogen bond.

Full text of DOI:10.1002/zaac.200700005

DOI: 10.1002/zaac.200700005
Synthesis and Characterization of Triphenylphosphinesilver(I)
Sulfanylcarboxylates of Types [(AgPPh3)(HL)] and [Ag(PPh3)3(HL)]
a
a
b
a
a,
a
´
´
´
´
´
´
Elena Barreiro , Jose S. Casas , Marıa D. Couce , Agustın Sanchez , Jose Sordo *, Jose M. Varela , and
b
´
´
Ezequiel M. Vazquez-Lopez
a
´
´
Santiago de Compostela / Spain, Departamento de Quımica Inorganica, Facultade de Farmacia, Universidade de Santiago de
Compostela
b
´
´
Vigo / Spain, Departamento de Quımica Inorganica, Facultade de Ciencias, Universidade de Vigo
Received January 3rd, 2007.
Dedicated to Professor Joachim Strähle on the Occasion of this 70th Birthday
Abstract.
Compounds
of
types
[(AgPPh3)(HL)]
and
formed by Ag(PPh3)(Htspa) monomers connected by Ag-S bonds,
the metal atom in each monomer being O,S-chelated. Complex 4
has a mononuclear structure with Ag-S and Ag-P bonds and an
intramolecular hydrogen bond.
[Ag(PPh3)3(HL)] {H2L ϭ H2xspa: x ϭ p (3-phenyl-), t [3-(2-thi-
enyl)-], f [3-(2-furyl)-]; spa ϭ 2-sulfanylpropenoato} were synthesi-
zed and characterized by IR, H, 13C and 31P NMR spectroscopy
1
and FAB mass spectrometry. The structures of [(AgPPh3)(Htspa)]
(2) and [Ag(PPh3)3(Hpspa)] (4) were determined by X-ray diffrac-
tometry. Complex 2 has a supramolecular structure based on
hydrogen bonding between dinuclear units which can be seen as
Keywords: Silver complexes; Sulfanylpropenoato ligands; Tri-
phenylphosphine; X-ray diffraction
Introduction
Interest in the coordination chemistry and structures of thi-
olate complexes of silver(I) and gold(I) [1] has increased in
recent years, in part due to the medicinal activities of these
compounds: namely, the antiarthritic, [2] antitumoral [3] or
antimicrobial activities [4] of the gold compounds and the
antibacterial activities of the silver compounds [5]. For
these latter, the kind of atom coordinated to the metal and
the ease with which the ligand is exchanged with biologi-
cally relevant ligands are both significant determinants of
activity [6].
Scheme 1
In a previous paper [7] we described the novel structures
of several complexes synthesized by reacting a 3-aryl-2-sul-
fanylpropenoic acid (H2L) with triphenylphosphine,
AgNO3 and NaOH under heterogeneous conditions [8]. As
well as several complexes of type [(AgPPh3)2L] we also ob-
tained [(AgPPh3)(Hpspa)] (1; H2pspa ϭ 3-phenyl-2-sulfan-
ylpropenoic acid) and [Ag(PPh3)3(Hfspa)] [6; H2fspa ϭ 3-
(2-furyl)-2-sulfanylpropenoic acid]. X-ray crystallography
showed that [(AgPPh3)(Hpspa)] monomers are linked by
pairs of Ag-S bonds to form dimers that are in turn linked
in chains by hydrogen bonds between their carboxyl groups.
By contrast, in [Ag(PPh3)3(Hfspa)] the monomers are dis-
crete and the carboxyl groups form intramolecular O-H···S
hydrogen bonds.
Here we report optimized syntheses of 1, 6 and anal-
ogous triphenylphosphinesilver(I) complexes of the
sulfanylpropenoic acids shown in Scheme 1, together with
the crystal structures of [(AgPPh3)(Htspa)] (2) and
[Ag(PPh3)3(Hpspa)] (4).
Results and Discussion
Synthesis and mass spectrometry
´
* Prof. Dr. Jose Sordo
´
´
Departamento de Quımica Inorganica
Facultade de Farmacia
Universidade de Santiago de Compostela
E-15782 Santiago de Compostela, Galicia, Spain
E-mail: qijsordo@usc.es
We initially tried to prepare the [(AgPPh3)(Hxspa)] com-
plexes by reacting silver nitrate and triphenylphosphine
with the appropriate sulfanylcarboxylic acid under the het-
erogeneous conditions described in ref. 8 for 1 [see Scheme 2,
Z. Anorg. Allg. Chem. 2007, 633, 795Ϫ801
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E. Barreiro, J. S. Casas, M. D. Couce, A. Sanchez, J. Sordo, J. M. Varela, E. M. Vazquez-Lopez
Scheme 2 Reaction schemes
reaction (1)] [7]. A solution of H2xspa and a 56 % excess of
triphenylphosphine in chloroform was added to a solution
of silver nitrate and NaOAc in water, and the mixture was
shaken for 20 minutes. The organic phase was separated
using a separation funnel and dried with MgSO4, and the
CHCl3 was evaporated under vacuum. The crude oily prod-
uct was treated with 1:1 hexane/ethanol, and the resulting
solid was dried in vacuo and crystallized from acetone. With
H2pspa and H2tspa this procedure afforded the desired
complexes 1 and 2, respectively, but with H2fspa it afforded
[Ag(PPh3)3(Hfspa)] (6) and the dinuclear complex
[(AgPPh3)2(fspa)], as previously described [7]. By contrast,
addition of PPh3 in 1:1 mole ratio to a suspension of the
appropriate [Ag(Hxspa)] complex in ethanol afforded all
three complexes of type [(AgPPh3)(Hxspa)], 1, 2 and 3
[Scheme 2, reaction (2)].
Figure 1 Molecular structure of [(AgPPh3)(Htspa)] (2)
monomer being O, S-chelated (although the Ag(n)-O(n1)
distance is indicative of only a weak interaction [10]). The
core of the dimer is a planar Ag2S2 ring in which the S
atoms both bridge asymmetrically between the two silver(I)
ions [Ag(1)-S(11) ϭ 2.666(2), Ag(2)-S(11) ϭ 2.541(3),
˚
Ag(1)-S(21) ϭ 2.524(3), Ag(2)-S(21) ϭ 2.670(2) A]. Details
of the coordination spheres around the silver atoms are
listed in Table 1 together with bond lengths and angles for
the Htspa moieties.
The silver(I) atom has a distorted tetrahedral environ-
ment, being bound to the two sulfanyl S atoms, the tri-
phenylphosphine P atom [Ag(1)-P(1) ϭ 2.408(2), Ag(2)-
[Ag(PPh3)3(Hpspa)] (4) and [Ag(PPh3)3(Hfspa)] (6) were
obtained by mixing a solution of the appropriate sulfanyl-
˚
P(2) ϭ 2.410(2) A] and one of the carboxylate O atoms
˚
carboxylic acid in chloroform with
a solution of
[Ag(1)-O(11) ϭ 2.573(6), Ag(2)-O(21) ϭ 2.575(6) A]. The
[Ag(PPh3)3(NO3)] and NaOAc in water [Scheme 2, reaction
(3)], with work-up as for reaction 1. With H2tspa, however,
this procedure afforded a high yield of compound 2. A simi-
lar process, in which a compound with a lower phosphine
content than the precursor was obtained, has been de-
scribed by Nomiya et al., [9] who interpreted it as showing
the presence of several species with different phosphine con-
tents in solution, the species isolated being determined by
its concentration and solubility. To obtain [Ag(PPh3)3(Ht-
spa)] (5), a solution of [Ag(Htspa)] in ethanol was reacted
with PPh3 in 1:3 mole ratio [Scheme 2, reaction (4)]. The
solid formed was filtered off, washed with ether and dried
in vacuo. With [Ag(Hpspa)] and [Ag(Hfspa)] this procedure
gave good yields of 4 and 6.
five-membered chelate ring AgC2SO is essentially planar
[rms ϭ 0.4695 and 0.4912 for the least-squares planes de-
fined by Ag(1)O(11)C(11)C(12)S(11) and Ag(2)-
O(21)C(21)C(22)S(21), respectively], and so too is the entire
Htspa moiety, the planes of the thiophene rings making
angles of only 2.6(4)° [C(14)-S(12)] and 3.2(3)° [C(24)-S(22)]
with the corresponding AgC2SO plane. The Ag(1)···Ag(2)
˚
distance, 3.0520(7) A, though longer than in metallic silver
˚
[2.889(6) A], is shorter than twice the van der Waals radius
˚
˚
of this metal (3.44 A), [11] shorter than the 3.1283(19) A
found in the analogous compound [(AgPPh3)(Hpspa)] (1)
˚
[7], and shorter than the 3.1300(3) A found in
{[Ag(PPh3)(SPh)]4} [12], on the basis of which a significant
Ag-Ag bonding interaction was argued.
As well as the [M]ϩ peak, the FABϩ mass spectra of com-
pounds 1-6 all show signals for fragments with different
PPh3 contents, which implies easy cleavage of the Ag-P
bonds. Some cleavage of Ag-S bonds is also evident.
The dinuclear units are associated in chains by hydrogen
bonds between their COOH groups [1.156(5), 1.475(6),
˚
2.608(8) A, 164.6(4)° for O(22)-H(22)...O(21)#1 and
˚
0.938(5), 1.800(6), 2.678(7) A, 154.6(4)° for O(12)-
H(12)...O(11)#2; #1 ϭ Ϫxϩ1,Ϫy,Ϫz; #2 ϭ Ϫx,Ϫyϩ1,Ϫz]
(Fig. 2). In both cases the C(n1)-O(n1) bond length is in the
Complexes of type [(AgPPh3)(Hxspa)] (1, 2 and 3)
˚
range 1.21-1.25 A and the C(n1)-O(n2) distance in the range
˚
Crystals of compound 2 consist of [(AgPPh3)(Htspa)]2 units
that can be seen as formed by [(AgPPh3)(Htspa)] monomers
connected by Ag-S bonds (Fig. 1), the metal atom in each
1.31-1.35 A (Table 1); these ranges are respectively typical
of CϭO and C-O bonds in an unambiguously ordered car-
boxylic acid dimer [13], and their proximity to those found
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Z. Anorg. Allg. Chem. 2007, 795Ϫ801

Triphenylphosphinesilver(I) Sulfanylcarboxylates
˚
length, and differs appreciably from both 1 and 2 as regards
Table 1 Selected interatomic distances /A and angles /° in
[(AgPPh3)(Htspa)] (2)
˚
its Ag-O bond length [2.343(3) A in the pyOS derivative,
˚
˚
2.599(6) A in 1, 2.573(6) and 2.575(6) A in 2]. The Ag-Ag
(a) Ag environment
˚
˚
bond is shortest in 2 [3.0520(7) A as against 3.1283(19) A
in 1 and 3.2472(11) A in the pyOS derivative]. However, the
˚
Ag(1)-P(1)
Ag(1)-S(11)
Ag(1)-O(11)
Ag(1)-S(21)
Ag(2)-P(2)
Ag(2)-O(21)
Ag(2)-S(11)
Ag(2)-S(21)
Ag(1)-Ag(2)
2.408(2)
2.541(3)
2.573(6)
2.669(2)
2.410(2)
2.575(6)
2.666(2)
2.525(3)
3.0520(7)
P(1)-Ag(1)-S(21)
P(1)-Ag(1)-O(11)
S(11)-Ag(1)-O(11)
P(1)-Ag(1)-S(11)
S(21)-Ag(1)-S(11)
O(21)-Ag(2)-S(11)
P(1)-Ag(1)-Ag(2)
S(21)-Ag(1)-Ag(2)
O(21)-Ag(2)-Ag(1)
S(11)-Ag(1)-Ag(2)
P(2)-Ag(2)-S(11)
P(2)-Ag(2)-O(21)
S(11)-Ag(2)-O(21)
P(2)-Ag(2)-S(21)
S(11)-Ag(2)-S(21)
O(21)-Ag(2)-S(21)
P(2)-Ag(2)-Ag(1)
S(11)-Ag(2)-Ag(1)
O(11)-Ag(1)-Ag(2)
S(21)-Ag(2)-Ag(1)
113.58(9)
113.21(15)
72.85(14)
133.95(8)
107.88(9)
108.10(15)
156.73(7)
51.84(6)
most significant difference between the pyOS derivative and
the other two compounds is that whereas the dinuclear
units of the former are isolated, those of 1 and 2 are linked
in chains by hydrogen bonds.
In previous work [15] we synthesized and determined the
structure of the triphenylphosphinegold(1) sulfanylprop-
enoate [Au(PPh3)(Hfspa)]. Although 1 and 2 are stoichio-
metrically similar to this gold compound, and have similar
M-S and M-P bond lengths, they dimerize through Ag-S
bonds, whereas the gold compound dimerizes through π-
stacking interactions between triphenylphosphine phenyl
rings and through hydrogen bonds between COOH groups.
The IR spectra of the free H2xspa ligands show ν(S-H)
bands at 2567 cmϪ1 (H2pspa), 2563 cmϪ1 (H2tspa) and
2568 cmϪ1 (H2fspa). In keeping with the deprotonation and
coordination of the sulfanyl S, these bands are absent from
the spectra of the complexes [(AgPPh3)(Hxspa)]. The
COOH vibrations ν(CϭO), δ(OH) and ν(C-O), which are
respectively located at 1670, 1416 and 1266 cmϪ1 in the
spectrum of H2pspa, at 1665, 1408 and 1270 cmϪ1 in that
of H2tspa, and at 1673, 1417 and 1266 cmϪ1 in that of
H2fspa, are only slightly shifted by the formation of the
complexes, which is in keeping with the small magnitude of
the structural changes undergone by this group in com-
pounds 1 and 2. In general, the similarity between the IR
spectrum of 3 and those of 1 and 2 suggests that the coordi-
nation mode of the Hxspa fragment in 3 is similar to that
determined by X-ray crystallography in 1 and 2.
91.71(15)
56.04(5)
113.55(9)
112.53(16)
108.10(15)
131.86(6)
108.48(9)
73.78(14)
155.56(7)
52.24(6)
89.41(14)
56.24(6)
(b) Htspa
O(11)-C(11)
O(12)-C(11)
O(21)-C(21)
O(22)-C(21)
C(12)-C(11)
C(12)-C(13)
C(13)-C(14)
C(22)-C(21)
C(23)-C(22)
C(23)-C(24)
1.219(10)
1.310(10)
1.227(11)
1.312(11)
1.482(11)
1.348(10)
1.439(10)
1.490(11)
1.349(10)
1.425(10)
O(11)-C(11)-O(12)
O(11)-C(11)-C(12)
O(12)-C(11)-C(12)
C(13)-C(12)-C(11)
C(13)-C(12)-S(11)
C(11)-C(12)-S(11)
O(21)-C(21)-O(22)
O(21)-C(21)-C(22)
O(22)-C(21)-C(22)
C(23)-C(22)-C(21)
C(23)-C(22)-S(21)
C(21)-C(22)-S(21)
119.9(10)
124.6(9)
115.5(9)
118.3(9)
124.0(7)
117.7(7)
122.8(10)
122.2(10)
114.9(9)
117.1(9)
122.7(8)
120.2(7)
Of the three H2xspa ligands, only H2pspa had a 1H NMR
spectrum in which it was possible to identify the SH signal,
which appeared at 5.22 ppm. The absence of this signal
from the spectrum of 1, and the fact that all three
[(AgPPh3)(Hxspa)] complexes have a C(3)H signal lying up-
field of its position in the corresponding ligand (7.73 ppm
in H2pspa, 8.18 ppm in H2tspa, and 7.60 ppm in H2fspa),
suggest that the S-coordination observed in the solid state
persists in solution [7, 15Ϫ17]. S-coordination is further
corroborated by the 13C NMR spectra, in which the C(3)
signals of the complexes, like their C(3)H signals, lie upfield
of their positions in the corresponding ligands (145.6 ppm
in H2pspa, 140.8 ppm in H2tspa, 132.0 ppm in H2fspa).
However, it is not clear whether both Ag-S bonds persist,
i.e. whether the dimers remain intact in solution. By con-
trast, it does seem fairly clear that the weak Ag-O bond is
lost in solution: in the 13C NMR spectra of the complexes
the C(1) signal lies only slightly downfield of its position in
the free ligand (167.1 ppm in H2pspa, 166.6 ppm in H2tspa,
and 166.4 ppm in H2fspa) and is close to the equivalent
signal of the analogous gold complex [15] and of the corre-
sponding [Ag(PPh3)3(Hxspa)] complex (vide infra). The per-
sistence of the Ag-PPh3 bond is testified to by the position
of the ipso C of the phenyl rings, which is located at
Figure 2 Hydrogen bonding in [(AgPPh3)(Htspa)] (2)
in an unperturbed hydrogen-bonded carboxylic acid dimer
testifies to the weakness of the Ag-O interaction.
Other structures based on an Ag2S2 core in which each
Ag atom has a distorted tetrahedral OPS2 coordination
polyhedron are those of compound
1
[7] and
[Ag(pyOS)(PPh3)]2 [14] (H2pyOS ϭ 1-hydroxypyridine-2-
thione). In comparison with compound 1, compound 2 has
a more symmetric Ag2S2 ring, a longer Ag-P bond, and a
shorter Ag-O bond. [Ag(pyOS)(PPh3)]2 is more similar to 1
than to 2 as regards its Ag2S2 ring geometry and Ag-P bond
Z. Anorg. Allg. Chem. 2007, 795Ϫ801
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E. Barreiro, J. S. Casas, M. D. Couce, A. Sanchez, J. Sordo, J. M. Varela, E. M. Vazquez-Lopez
˚
Table 2 Selected interatomic distances /A and angles /° in
[Ag(PPh3)3(Hpspa)] (4)
(a) Ag environment
Ag-P(2)
Ag-P(1)
Ag-P(3)
Ag-S
2.5255(19)
2.588(2)
2.6032(18)
2.609(2)
P(2)-Ag-P(1)
P(2)-Ag-P(3)
P(1)-Ag-P(3)
P(2)-Ag-S
P(1)-Ag-S
P(3)-Ag-S
114.91(6)
115.35(6)
103.03(6)
116.37(7)
103.50(7)
101.79(7)
(b) Hpspa
O(1)-C(1)
O(2)-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
1.311(15)
1.205(15)
1.541(14)
1.362(11)
1.413(11)
O(1)-C(1)-O(2)
O(1)-C(1)-C(2)
O(2)-C(1)-C(2)
C(3)-C(2)-C(1)
C(3)-C(2)-S
122.8(10)
126.2(10)
111.0(9)
114.6(7)
125.7(5)
119.5(6)
C(1)-C(2)-S
Figure 3 Molecular structure of [Ag(PPh3)3(Hpspa)] (4) (for
clarity, triphenylphosphine phenyl rings have been omitted)
ton constitutes an intermolecular hydrogen bond that links
the monomers in chains. In 4, however, the only hydrogen
bond is an intramolecular bond between COOH and the S
136.4 ppm in free PPh3 [18], and by the room temperature
31P{1H} NMR signal at around 12 ppm, close to its posi-
tion in the spectra of other 1:1 triphenylphosphinesilver
complexes with S-Ag-P fragments [19].
˚
atom [O(1)-H(1)...S: 0.824(11), 2.221(2), 2.830(9) A,
131.0(6)°]. The geometrical parameters of this bond, like
those of the COOH group, are close to those previously
found in 6 [7], although the e.s.d.s are larger in 4.
The IR spectra of the three [Ag(PPh3)3(Hxspa)] com-
plexes are all similar, suggesting that 5 has a similar solid
state structure to those identified for 4 and 6 [7] by X-ray
diffraction. In all three spectra, deprotonation of the SH
group is reflected by the absence of a ν(SH) band. The posi-
tions of the COOH vibrations differ from those of the
[(AgPPh3)(Hxspa)] complexes; in particular, δ(OH) now
overlaps the PPh3 vibrations, doubtless partly because of
the difference between the hydrogen bonds in which this
group takes part in the two sets of complexes.
Complexes of type [Ag(PPh3)3(Hxspa)] (4, 5 and 6)
Crystals of compound
4
consist of discrete
[Ag(PPh3)3(Hpspa)] units. Figure 3 shows the molecular
structure, and the most significant structural parameters are
listed in Table 2. The Ag atom is coordinated to three PPh3
ligands and to the S atom of the Htspa moiety. The angles
around the silver atom are those of a distorted tetrahedron.
˚
˚
The Ag-P distances [2.588(2), 2.5255(19) and 2.6032(18) A]
1
are longer than in 1 [2.369(3) A], 2 [2.408(2), 2.410(2) A]
In the H and 13C NMR spectra the absence of any SH
˚
and other complexes with only a single PPh3 ligand, but the
Ag-S bond length, 2.609(2) A, is within the range found in
signal and the shift of the C(3)H and C(3) signals to higher
field are, as in the case of the [(AgPPh3)(Hxspa)] complexes,
in keeping with the persistence of the S-coordination ob-
˚
1 and 2. In other monomeric complexes in which X-ray
crystallography has shown distorted tetrahedral AgSP3 ker-
nels, {[Ag(PPh3)3(Hfspa)] (6) [7], [Ag(PPh3)3(Hmna)] [20]
(H2mna ϭ 2-sulfanylnicotinic acid), [Ag(PPh3)3(Hmba)] [9]
(H2mba ϭ 2-sulfanylbenzoic acid), [Ag(PPh3)3(La)] [La ϭ
4-(methylthio)-2-thioxo-1,3-dithiole-2-thiolate] [21] and
[Ag(PPh3)3(Lb)] [Lb ϭ 1,2-dicyano-1-(methylthio)ethene-2-
thiolate] [21]}, the Ag-S distance ranges from the
1
served in the solid state [7, 15Ϫ17]. The H spectra show a
signal at about 12.5 ppm that is attributable to OH, and in
the 13C spectra the C(1) signal lies at positions close to
those previously found in the spectra of 1-3,
[Ag(PPh3)3(Hmba)] [9] and [Ag(PPh3)3(Hmna)] [20]. The
room temperature 31P{1H} NMR signals at 2.4-6.9 ppm are
likewise close to the positions of this signal in
2.5898(9) A found in [Ag(PPh3)3(La)] to the 2.6406(12) A of
[Ag(PPh3)3(Lb)]; the Ag-P distance ranges from
[Ag(PPh3)3(Hmba)] [9] and [Ag(PPh3)3(Hmna)] [20]. No 31
P
˚
˚
signal due to free PPh3 was observed but to explore further
the possible dissociation of the phosphine ligand, low-tem-
perature 31P{1H} NMR experiments were carried out. The
spectrum of 4 consists of two doublets centred at 5.16 and
2.58 ppm, both of which are split by 31P couplings with
109Ag and 107Ag isotopes, indicating the presence of Ag-P
˚
˚
2.5255(19) A in 4 to 2.6495(8) A in the La derivative; and
the angles around the metal range from 95.89(4)° to
121.82(4)° in the most distorted structure (the Lb derivative)
and from 103.68(3)° to 116.23(3)° in the least distorted
(compound 1). Like 1, compound 4 and the Hmna deriva-
tive exhibit only slight distortion.
1
bonds. The J(31P-109/107Ag) and δ values (see experimental
In other structurally characterized complexes of the
H2xspa ligands in which the COOH group remains pro-
tonated, such as [Au(PPh3)(Hfspa)] [15], 1 [7] or 2, the pro-
part) suggest that the low field doublet is due to compound
4 [22, 23] and the high-field one to [Ag(PPh3)2(Hpspa)] [22].
The cleavage of Ag-P bonds is confirmed by the presence
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Z. Anorg. Allg. Chem. 2007, 795Ϫ801

Triphenylphosphinesilver(I) Sulfanylcarboxylates
using 5 mm o.d. tubes; chemical shifts are reported relative to TMS
of a singlet at 28.91 ppm due to triphenylphosphine oxide
generated by the oxidation of the triphenylphosphine re-
leased. A low-intensity broad doublet at 8.5 ppm may be
due to a small amount of [(AgPPh3)(Hpspa)] (see below).
The low-temperature 31P{1H} NMR spectrum of 1, ob-
tained in the same experimental conditions, showed a single
doublet centred at 8.49 ppm and split by the 31P-Ag coup-
ling indicating that only one species with an Ag-P bond is
1
using the solvent signals (δ H ϭ 2.50 ppm; δ 13C ϭ 39.5 ppm) as
reference. 31P NMR spectra were recorded in dmso-d6 at
202.46 MHz on a Bruker AMX 500 spectrometer using 5 mm o.d.
tubes and are reported relative to external neat H3PO4 (85 %). Low
temperature 31P{1H}experiments were carried out at 183.0 K using
CD2Cl2 as solvent (temperature was controlled with the thermal
unit of the AMX500). All the physical measurements were carried
out by the RIAIDT services of the University of Santiago de Com-
postela.
1
present. According to its J(31P-109/107Ag) value [22], this
species are compound 1. Again, a weak singlet at 28.91 ppm
indicates the formation of triphenylphosphine oxide [24].
[(AgPPh3)(Hpspa)] (1). Prepared from [Ag(Hpspa)] (0.048 g,
0.17 mmol) and PPh3 (0.044 g, 0.17 mmol) in ethanol (8 cm3); yield
78 %. Yellow solid, m.p. 155 °C. Anal.: found, C 59.2, H 4.0, S
5.7 %; calc. for C27H22O2SPAg, C 59.0, H 4.0, S 5.8 %. The syn-
thesis of this compound by reaction 1 (see Scheme 2), its spectro-
scopic data and its structure have been described elsewhere [7]. Low
temperature 31P{1H}: δ 8.49 (d), {1J(31P-109/107Ag) ϭ 405.5/
352.4 Hz, 28.91(s)}.
Conclusion
The synthesis of complexes of types [(AgPPh3)(Hxspa)] and
[Ag(PPh3)3(Hxspa)], where the Hxspa ligands are defined
in Scheme 1, was optimized through the use of appropriate
precursors. X-ray crystallography of [(AgPPh3)(Htspa)] (2)
and [Ag(PPh3)3(Hpspa)] (4) showed that in 2 the COOH
group forms intermolecular hydrogen bonds linking its di-
mers in chains, while in the discrete monomers of 4 it forms
an intramolecular hydrogen bond with the sulfanyl S atom.
[(AgPPh3)(Htspa)] (2). Preparation from [Ag(Htspa)] (0.100 g,
0.34 mmol) and PPh3 (0.089 g, 0.34 mmol) in ethanol (15 cm3) (re-
action 2 in Scheme 2) afforded an 83 % yield as an orange solid.
Preparation by adding a solution of H2tspa (0.04 g, 0.21 mmol)
in CHCl3 (12 cm3) to [Ag(PPh3)3(NO3)] (0.20 g, 0.21 mmol) and
NaOAc (0.025 g, 0.30 mmol) in H2O (25 cm3) (reaction 3) afforded
an 80 % yield as orange crystals. Preparation by addition of a solu-
tion of H2tspa (0.750 g, 4.0 mmol) and PPh3 (1.660 g, 6.3 mmol) in
CHCl3 (33 cm3) to a solution of AgNO3 (0.690 g, 4.0 mmol) and
NaOAc (0.550 g, 6.7 mmol) in H2O (66 cm3) (reaction 1) afforded
a 60 % yield as orange crystals. M.p.: 118 °C. Anal.: found, C 54.0,
H 3.7, S 11.2 %; calc. for C25H20O2S2PAg, C 54.0, H 3.6, S 11.5 %.
Crystals suitable for the X-ray diffraction studies were grown from
an acetone solution.
Experimental Section
Material and methods
Thiophene-2-carboxaldehyde,
furfural-2-carboxaldehyde
and
rhodanine (all from Aldrich), benzaldehyde (from Probus), tri-
phenylphosphine (from Riedel-de-Hae¨) and silver nitrate (from
Prolabo) were all used as supplied. The 3-aryl-2-sulfanylpropenoic
acids H2pspa, H2tspa and H2fspa were prepared by condensation
of the appropriate aldehyde with rhodanine, subsequent alkaline
hydrolysis of the 5-substituted rhodanine so obtained, and acidifi-
cation with aqueous HCl [25, 26]. Specific experimental conditions
for H2pspa, H2tspa and H2fspa have been described in refs. [7]
and [15].
MS (FAB): the main metallated signals are at m/z 925 (33 %),
[(AgPPh3)2tspa]ϩ; 631 (67), [Ag(PPh3)2]ϩ; 555 (2), [M]ϩ and 369 (100),
[(AgPPh3)]ϩ. IR (cmϪ1): 1634 vs, ν(CϭO); 1434 s, δ(OH); 1264 s, ν(C-O);
1479 m, 1435 s, ν(PPh3). NMR (dmso-d6): 1H, δ 12.42 (ws, 1H, C(1)OH),
7.92 (s, 1H, C(3)H), 7.05 (t, 1H, C(6)H), 7.18-7.42 (m, 17H, C(5)H, C(7)H,
H(Ph3)); 13C, δ 170.5 C(1), 125.8 C(2), 131.4 C(3), 142.0 C(4), 131.3 C(5),
126.6 C(6), 128.5 C(7), 132.6 (d, Ci(Ph3), J ϭ 20.1), 133.2 (d, Co(Ph3), J ϭ
17.2), 128.8 (d, Cm(Ph3), J ϭ 9.2),130.0 Cp(Ph3); 31P {1H}, δ 11.5 (s).
Complexes of type [Ag(Hxspa)] [27] were prepared by adding a
solution of AgNO3 and Et3N in 1:1 mole ratio in acetonitrile to a
solution of the appropriate sulfanylcarboxylic acid in ethanol, or
by adding a suspension of Ag2O in water to an aqueous solution
of NaOH and the appropriate sulfanylcarboxylic acid (1:4:2
Ag2O:NaOH:H2xspa mole ratio). [Ag(PPh3)3(NO3)] was prepared
in accordance with the literature [28].
[(AgPPh3)(Hfspa)] (3). Prepared from [Ag(Hfspa)] (0.100 g,
0.36 mmol) and PPh3 (0.090 g, 0.36 mmol) in ethanol (15 cm3);
yield 80 %. Orange solid, m.p. 169 °C. Anal.: found, C 55.3, H 4.1,
S 6.1 %; calc. for C25H20O3SPAg, C 55.7, H 3.8, S 6.0 %.
MS (FAB): the main metallated signals are at m/z 908 (40 %),
[(AgPPh3)2fspa]ϩ; 631 (72), [Ag(PPh3)2]ϩ; 539 (3), [M]ϩ and 369 (100),
[(AgPPh3)]ϩ. IR (cmϪ1): 1639 vs, ν(CϭO); 1435 s, δ(OH); 1255 vs, ν(C-O);
1478 s, 1435 s, ν(PPh3). NMR (dmso-d6): 1H, δ 12.50 (ws, 1H, C(1)OH), 7.49
(d, 1H, C(5)H), 6.46 (t, 1H, C(6)H) 7.63 (d, 1H, C(7)H), 7.20-7.44 (m,16H,
C(3)H, H(Ph3)); 13C, δ 170.1 C(1), 123.0 C(2), 128.5 C(3), 153.1 C(4), 113.4
C(5), 111.9 C(6), 142.3 C(7), 132.0 (d, Ci(Ph3), J ϭ 23.6), 133.2 (d, Co(Ph3),
J ϭ 17.2), 128.7 (d, Cm(Ph3), J ϭ 9.8), 130.1 Cp(Ph3); 31P {1H}, δ 13.3 (s).
Elemental analyses were performed with a Fisons 1108 microana-
lyser. Melting points were determined with a Büchi apparatus and
are uncorrected. Mass spectra (MS) were recorded on a Hewlett
Packard HP 5972-A spectrometer connected to a DS90 system and
operating in E.I. mode (70 ev, 250 °C) and on a Kratos MS50TC
spectrometer connected to a DS90 system and operating in FAB
mode (m-nitrobenzyl alcohol, Xe, 8 eV; ca. 1.28x10Ϫ15 J); ions were
identified by DS90 software and the data characterizing the metal-
lated peaks were calculated assuming the Ag isotope to be 107Ag.
IR spectra (KBr pellets or Nujol mulls) were recorded on a Bruker
IFS66V FT-IR spectrometer and are reported in the synthesis sec-
tion using the following abbreviations: vs ϭ very strong, s ϭ strong,
[Ag(PPh3)3(Hpspa)] (4). Preparation from [Ag(Hpspa)] (0.05 g,
0.18 mmol) and PPh3 (0.140 g, 0.54 mmol) in ethanol (10 cm3) (re-
action 4) afforded a 70 % yield as a yellow solid. Preparation by
addition of a solution of H2pspa (0.02 g, 0.10 mmol) in CHCl3
(8 cm3) to [Ag(PPh3)3(NO3)] (0.10 g, 0.10 mmol) and NaOAc
(0.014 g, 0.25 mmol) in H2O (16 cm3) (reaction 3) afforded an 85 %
yield as yellow crystals. M.p.: 155 °C. Anal.: found, C 70.4, H 4.9,
S 2.9 %; calc. for C63H52O2SP3Ag, C 70.5, H 4.9, S 3.0 %. Crystals
suitable for X-ray diffractometry were grown from a 1:1 ethanol/
hexane solution.
1
m ϭ medium, w ϭ weak, sh ϭ shoulder, br ϭ broad. H and 13C
NMR spectra were recorded in dmso-d6 at room temperature on a
Bruker AMX 300 operating at 300.14 and 75.40 MHz, respectively,
Z. Anorg. Allg. Chem. 2007, 795Ϫ801
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
799

´
´
´
E. Barreiro, J. S. Casas, M. D. Couce, A. Sanchez, J. Sordo, J. M. Varela, E. M. Vazquez-Lopez
MS (FAB): the main metallated signals are at m/z 1288 (3 %), [M]ϩ; 918
(14), [(AgPPh3)2pspa]ϩ; 631 (100), [Ag(PPh3)2]ϩ and 369 (95), [(AgPPh3)]ϩ.
IR (cmϪ1): 1720 s, ν(CϭO); 1434 s, δ(OH); 1291 w, ν(C-O); 1434 s, 1478 s,
ν(PPh3). NMR (dmso-d6): 1H, δ 12.45 (ws, 1H, C(1)OH), 7.53 (s, 1H,
C(3)H), 8.29 (d, 2H, C(5)H, C(9)H), 7.21, 7.30, 7.39 (m, 48H, C(6)H, C(8)H,
C(7)H, H(PPh3)); 13C, δ 171.2 C(1), 128.5 C(2), 138.6 C(3), 137.8 C(4), 131.2
C(5) and C(9), 127.4 C(6) and C(8), 126.6 C(7), 133.0 (d, Co(Ph3), J ϭ 17.2),
128.6 (d, Cm(Ph3), J ϭ 8.0), 129.6 Cp(Ph3); 31P {1H}: δ 5.8 (s). Low tempera-
ture 31P{1H}: δ 5.16 (d), {1J(31P-109/107Ag) ϭ 257.5/223.1 Hz}, δ 2.58 (d),
{1J(31P-109/107Ag) ϭ 318.4/276.0 Hz}, 8.5 (d, br), 28.91 (s).
Table
3
Crystal data for [(AgPPh3)(Htspa)] (2) and
[Ag(PPh3)3(Hpspa)] (4)
Compound
[(AgPPh3)(Htspa)] 2
[Ag(PPh3)3(Hpspa)] 4
Empirical formula
M
T/K
C50H40Ag2O4P2S4
1110.74
C63H52AgO2P3S
1073.89
293(2)
293(2)
Crystal system
Space group
triclinic
P1
monoclinic
P21/n
¯
˚
a /A
11.0031(11)
14.9722(14)
15.3097(14)
71.792(2)
77.729(2)
87.451(2)
2340.5(4)
2
13.6411(9)
20.2541(13)
23.8222(12)
[Ag(PPh3)3(Htspa)] (5). Prepared from [Ag(Htspa)] (0.06 g,
0.20 mmol) and PPh3 (0.16 g, 0.61 mmol) in ethanol (20 cm3); yield
73 %. Yellow solid, m.p. 75 °C. Anal.: found, C 67.6, H 4.5, S
5.8 %; calc. for C61H50O2S2P3Ag, C 67.8, H 4.7, S 5.9 %.
˚
b /A
˚
c /A
α/°
β/°
γ/°
123.160(3)
MS (FAB): the main metallated signals are at m/z 1294 (3 %),
[(AgPPh3)3tspa]ϩ; 925 (21), [(AgPPh3)2tspa]ϩ; 631 (100), [Ag(PPh3)2]ϩ; 555
(2) [(AgPPh3)(Htspa)]ϩ and 369 (90), [(AgPPh3)]ϩ. IR (cmϪ1): 1717 s, ν(Cϭ
O); 1434 vs, br, δ(OH); 1288 w, ν(C-O); 1479 s, 1434 vs, br, ν(PPh3). NMR
(dmso-d6): 1H, δ 12.35 (ws, 1H, C(1)OH), 7.93 (s, 1H, C(3)H), 7.06 (m, 1H,
C(6)H), 7.22, 7.33, 7.41 (m, 47H, C(5)H, C(7)H, H(Ph3)); 13C, δ 170.6 C(1),
125.7 C(2), 131.9 C(3), 142.5 C(4), 130.4 C(5), 127.1 C(6), 129.3 C(7), 133.2
(d, Co(Ph3), J ϭ 15.5), 128.7 (d, Cm(Ph3), J ϭ 10.3),129.7 Cp(Ph3); 31P {1H},
δ 2.4 (s).
3
˚
V/A
5509.9(6)
4
Z
Dc /Mg. MϪ3
1.576
1.295
µ/mmϪ1
1.128
0.533
Crystal size /mm
θ Range for data collection /° 1.43-28.02
Index ranges
0.34 x 0.12 x 0.06
0.08 x 0.14 x 0.29
1.43-28.02
Ϫ17Յ h Յ17
Ϫ25Յ k Յ26
Ϫ31Յ l Յ31
29715
Ϫ7Յ h Յ14,
Ϫ19Յ k Յ19,
Ϫ19Յ l Յ20
12258
Reflections collected
Unique reflections, R
Final R1, wR2 [I>2 σ (I)]
(All data)
8729 [R(int) ϭ 0.0440] 12218[R(int) ϭ 0.0731]
[Ag(PPh3)3(Hfspa)] (6). Preparation from [Ag(Hfspa)] (0.05 g,
0.18 mmol) and PPh3 (0.135 g 0.54 mmol) in ethanol (10 cm3) (re-
action 4) afforded a 78 % yield as a brown solid. Preparation by
addition of a solution of H2fspa (0.04 g, 0.26 mmol) in CHCl3
(12 cm3) to [Ag(PPh3)3(NO3)] (0.25 g, 0.26 mmol) and NaOAc
(0.025 g, 0.30 mmol) in H2O (25 cm3) afforded an 80 % yield as
brown crystals. M.p. 153 °C. Anal.: found: C 68.6, H 4.6, S 2.8 %;
calc. for C61H50O3SP3Ag, C 68.9, H 4.7, S 3.0 %. The structure of
6 has been previously described [7].
MS (FAB): the main metallated signals are at m/z 1279 (3 %), [M]ϩ; 908
(15), [(AgPPh3)2fspa]ϩ; 631 (100), [Ag(PPh3)2]ϩ and 369 (71), [(AgPPh3)]ϩ.
IR (cmϪ1): 1720 vs, ν(CϭO); 1434 vs, br, δ(OH); 1292 m, ν(C-O); 1479 s,
1434 vs, br, ν(PPh3). NMR (dmso-d6): 1H, δ 12.30 (ws, 1H, C(1)OH), 7.48
(s, 1H, C(3)H), 7.54 (d, 1H, C(5)H), 6.47 (t, 1H, C(6)H) 7.65 (d, 1H, C(7)H),
7.25, 7.35, 7.41 (m, 45H, H(Ph3)); 13C, δ 170.9 C(1), 121.1 C(2), 128.7 C(3),
154.0 C(4), 112.1 C(5), 111.8 C(6), 141.7 C(7), 133.2 (d, Co(Ph3), J ϭ 18.3),
128.8 (d, Cm(Ph3), J ϭ 9.1), 129.7 Cp(Ph3); 31P {1H}, δ 6.9 (s), 31.4 (s).
0.0436, 0.0535
0.1928, 0.0743
0.0574, 0.1640
0.1909, 0.1921
Acknowledgements. We thank the Spanish Ministry of Science and
Technology for financial support under projects BQU2002-04524-
CO2-01 and BQU2002-04524-CO2-02, and the Xunta the Galicia,
Spain, for support under projects PGIDIT03PXIC20306PN and
PGIDIT03PXIC30103PN.
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