Intra- and intermolecular hydrogen bonds in [Ag(PPh3) 3(HL)] complexes [H2L: H2xspa = 3(aryl)-2-sulfanylpropenoic acids; H2cpa = 2-cyclopentylidene-2- sulfanylacetic acid]

Article abstract of DOI:10.1016/j.poly.2010.09.027

Compounds of the type [Ag(PPh₃)₃(HL)] {H ₂xspa=3(aryl)-2-sulfanylpropenoic acids: x = Clp [3-(2-chlorophenyl)- ], -o-mp [3-(2-methoxyphenyl)-], -p-mp [3-(4-methoxyphenyl)-], -o-hp [3-(2-hydroxyphenyl)-], -p-hp [3-(4-hydrox

Full text of DOI:10.1016/j.poly.2010.09.027

Polyhedron 30 (2011) 53–60
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Intra- and intermolecular hydrogen bonds in [Ag(PPh3)3(HL)] complexes [H2L:
H2xspa = 3(aryl)-2-sulfanylpropenoic acids; H2cpa = 2-cyclopentylidene-2-sulfanyl-
acetic acid]
a
Elena Barreiro a, José S. Casas a, María D. Couce b, Agustín Sánchez a, José Sordo a, , José M. Varela ,
⇑
Ezequiel M. Vázquez López b
a Departamento de Química Inorgánica, Facultade de Farmacia, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain
b Departamento de Química Inorgánica, Facultade de Química, Universidade de Vigo, 36310 Vigo, Galicia, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 27 July 2010
Accepted 23 September 2010
Available online 7 October 2010
Compounds of the type [Ag(PPh3)3(HL)] {H2xspa=3(aryl)-2-sulfanylpropenoic acids: x = Clp [3-(2-chloro-
phenyl)-], -o-mp [3-(2-methoxyphenyl)-], -p-mp [3-(4-methoxyphenyl)-], -o-hp [3-(2-hydroxyphenyl)-],
-p-hp [3-(4-hydroxyphenyl-); H2cpa = 2-cyclopentylidene-2-sulfanylacetic acid} were synthesized and
characterised by IR and NMR (1H 13C and 31P) spectroscopy and by FAB mass spectrometry. The crystal
structures of [Ag(PPh3)3(HClpspa)], [Ag(PPh3)3(H-o-mpspa)], [Ag(PPh3)3(H-p-mpspa)] and [Ag(PPh3)3-
(Hcpa)] reveal the presence of discrete molecular units containing an intramolecular O–HÁÁÁS hydrogen
bond between the S atom and one of the O atoms of the COOH group. This intramolecular hydrogen bond
remains in [Ag(PPh3)3(H-o-hpspa)]ÁEtOH and [Ag(PPh3)3(H-p-hpspa)] but in both cases polymeric struc-
tures are built on the basis of O–HÁÁÁO interactions that involve the –OH substituent of the phenyl group of
the sulfanylpropenoate fragment.
Keywords:
Silver(I) complexes
Hydrogen bonds
Sulfanylpropenoic acids
Mercaptopropenoic acids
X-ray structures
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
and to the S atom of the monodeprotonated sulfanylcarboxylic acid
(Hxspa), in which the COOH group remains protonated. In other
The biological activity and medicinal properties of silver [1,2]
and gold [3,4] compounds, together with their technological appli-
cations [5,6], have brought about an increase in interest in the
coordination chemistry of both elements [7].
In a search for new structural features of silver(I), we previously
investigated [8] the reaction of this ion with PPh3 and sulfanylcarb-
oxylic acids such as R–CH@C(SH)–COOH, (hereafter H2xspa).
Whereas the usual proportion of Ag/PPh3 in the synthesized solids
was 1:1, a few crystals of [Ag(PPh3)3(Hfspa)] [H2fspa = 3-(furyl)-2-
sulfanylpropenoic acid] were isolated and these had a higher con-
tent of triphenylphosphine.
The synthesis of this type of compound was later optimised [9],
enabling the preparation of the equivalent [Ag(PPh3)3(Hxspa)]
compounds for which Hxspa are the phenyl- and thienylsulfanyl-
propenoic derivatives. The structure of [Ag(PPh3)3(Hpspa)]
[H2pspa = 3-(phenyl)-2-sulfanylpropenoic acid] was solved by X-
ray diffraction.
silver [8,9] or gold [10,11] compounds, such as [M(PPh3)(Hxspa)],
with a lower content of triphenylphosphine, this COOH group par-
ticipates in intermolecular hydrogen bonding with an equivalent
group of a neighbouring molecule, thus affording the homosynthon
carboxylic acid dimer. However, in the structures of [Ag(PPh3)3-
(Hpspa)] and [Ag(PPh3)3(Hfspa)] the COOH group participates in
an intramolecular O–HÁÁÁS hydrogen bond with the metallated S
atom to give isolated monomers, thus showing the prevalence of
this bond over the carboxylic acid/dimer motif. Tiekink et al. previ-
ously showed for the specific case of (tricyclohexylphos-
phine)gold(I) 2-mercaptobenzoate that both structural motifs can
be present and that the stability of one over the other is solvent-
modulated [12,13].
In the study reported here we tried to ascertain whether the
structural modification of the R-aryl group on the sulfanylcarboxy-
late ligand could modify the prevalence of the O–HÁÁÁS hydrogen
bond found for the phenyl- and the furyl-derivatives; in particular,
we investigated whether new donor atoms or new substituents on
the aryl ring could produce new synthons [14], thus changing the
structure and the crystal packing of the prepared solids. We se-
lected the ligands H2xspa and H2cpa (see Scheme 1) and prepared
complexes of the type [Ag(PPh3)3(Hxspa)]. The structures
of [Ag(PPh3)3(HClpspa)], [Ag(PPh3)3(H-o-mpspa)], [Ag(PPh3)3-
The structures of the furyl- and phenyl-derivatives show that
the Ag atom is bonded to three P atoms of three PPh3 ligands
⇑
Corresponding author. Tel.: +34 981528074; fax: +34 981547102.
E-mail address: jose.sordo@usc.es (J. Sordo).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.09.027

54
E. Barreiro et al. / Polyhedron 30 (2011) 53–60
Scheme 1.
(H-p-mpspa)], [Ag(PPh3)3(Hcpa)], [Ag(PPh3)3(H-o-hpspa)]ÁEtOH
and [Ag(PPh3)3(H-p-hpspa)] were solved by X-ray diffraction, with
two types of structure found – one containing monomer units and
the other containing hydrogen-bonded polymeric species.
in FAB mode (m-nitrobenzyl alcohol, Xe, 8 eV; ca. 1.28 Â 10À15 J);
ions were identified by DS90 software and the data characterising
the metallated peaks were calculated using the isotope 107Ag. IR
spectra (KBr pellets or Nujol mulls) were recorded on a Bruker
IFS66 V FT-IR spectrophotometer and are reported in the synthesis
section using the following abbreviations: vs = very strong,
s = strong, m = medium, w = weak, sh = shoulder, br = broad. 1H
and 13C NMR spectra were recorded in dmso-d6 and/or CDCl3 at
room temperature on a Bruker AMX 300 spectrometer operating
at 300.14 and 75.40 MHz, respectively, using 5 mm o.d. tubes;
chemical shifts are reported relative to TMS using the solvent sig-
2. Experimental
2.1. Materials and methods
2-Chlorobenzaldehyde, 2-methoxybenzaldehyde, 4-methoxy-
benzaldehyde, cyclopentanone, 2-hydroxybenzaldehyde and
4-hydroxybenzaldehyde (all from Aldrich), triphenylphosphine
(Riedel-de-Haën) and silver nitrate (Prolabo) were all used as
supplied. The 3-(2-aryl)-2-sulfanylpropenoic acids H2Clpspa,
H2-o-mpspa, H2-p-mpspa, H2-o-hpspa and H2-p-hpspa were pre-
pared by condensation of the appropriate aldehyde with rhodanine
[15], subsequent hydrolysis in an alkaline medium and acidificat-
ion with aqueous HCl [16]. For the preparation of 2-cyclopentylid-
ene-2-sulfanylacetic acid, (H2cpa), a ketone (cyclopentanone) was
used in the condensation reaction instead of an aldehyde [17].
Specific experimental conditions for H2Clpspa, H2-o-mpspa and
H2-p-mpspa were described in Ref. [8] and for H2-o-hpspa and
H2-p-hpspa in Ref. [18].
nals (d 1H = 2.50 ppm;
d d
13C = 39.5 ppm for dmso-d6 and
1H = 7.26 ppm; d 13C = 77.0 ppm in CDCl3) as references. The split-
ting of proton resonances in the reported 1H NMR spectra are de-
fined as s = singlet, d = doublet, t = triplet, m = multiplet,
pst = pseudotriplet and br = broad. 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%). All the physical measurements were carried out by
the RIAIDT services of the University of Santiago de Compostela.
2.2. Synthesis of the complexes
[Ag(PPh3)3(NO3)] was prepared according to the literature pro-
cedure [19].
Elemental analyses were performed on a Fisons 1108 microana-
lyser. Melting points were determined with a Büchi apparatus and
are uncorrected. Mass spectra (MS) were recorded on a Kratos
MS50TC spectrometer connected to a DS90 system and operating
The complexes [Ag(PPh3)3(Hxspa)] and [Ag(PPh3)3(Hcpa)] were
obtained by mixing a solution of the appropriate sulfanylcarboxylic
acid in chloroform with a solution of [Ag(PPh3)3(NO3)] and NaOAc
in water. The mixture was shaken for 45 min, the organic phase
was separated and dried with MgSO4, and the CHCl3 was evapo-
rated under vacuum. The crude oily product was treated with 1:1

E. Barreiro et al. / Polyhedron 30 (2011) 53–60
55
hexane/ethanol and the resulting solution was evaporated at room
temperature.
[(AgPPh3)]+. IR (cmÀ1): 1714 vs
2862 m, s(CH2); 2949 m, m
a(CH2). NMR (DMSO-d6): 1H, d 12.00
m
(C@O); 1479 s, 1434 vs,
m
(PPh3);
m
(s,br, 1H, C(1)OH), 2.41 (m, 2H, C(4)H2), 1.34 (m, 2H, C(5)H2),
1.23 (m, 2H, C(6)H2), 2.33 (m, 2H, C(7)H2), 7.23, 7.35, 7.39,
7.58 (m, 45H, H(PPh3)); 13C, d 170.1 C(1), 123.6 C(2), 156.4 C(3),
37.8 C(4), 27.3 C(5), 25.0 C(6), 34.9 C(7), 133.3 (d, Co(Ph3),
J = 18.3), 128.9 (d, Cm(Ph3), J = 7.6), 129.7 Cp(Ph3); 31P {1H}, d 5.3
(s), 31.5 (s).
2.2.1. [Ag(PPh3)3(HClpspa)] (1)
H2Clpspa (0.05 g, 0.25 mmol), Ag(PPh3)3(NO3) (0.23 g,
0.25 mmol), NaOAc (0.02 g, 0.25 mmol), CHCl3 (15 cm3), H2O
(25 cm3), yellow crystals. Yield: 72%. M.p.: 158 °C. Anal. Calc. for
C
63H51O2SClP3Ag: C, 68.3; H, 4.7; S, 2.9. Found: C, 68.0; H, 5.0; S,
2.7%. MS (FAB): the main signals for metallated species are at m/
1322 (2%), [M]+; 953 (13), [(AgPPh3)2Clpspa]+; 631 (100),
[Ag(PPh3)2]+ and 369 (54), [(AgPPh3)]+. IR (cmÀ1): 1721 vs,
(C@O); 1280 w, (C–O); 1480 s, 1435 vs, (PPh3). NMR (DMSO-
z
2.2.5. [Ag(PPh3)3(H-o-hpspa)]ÁEtOH (5)
H2-o-hpspa (0.045 g, 0.23 mmol), Ag(PPh3)3(NO3) (0.2 g,
0.23 mmol), NaOAc (0.02 g, 0.23 mmol), CHCl3 (10 cm3), H2O
(20 cm3), orange crystals. M.p.: 95 °C. Anal. Calc. for C65H58O4S-
P3Ag: C, 68.7; H, 5.1; S, 2.8. Found: C, 69.0; H, 4.9; S, 3.0%. MS
(FAB): the main metallated signals are at m/z 935 (3%),
[(AgPPh3)2-o-hpspa]+; 631 (100), [Ag(PPh3)2]+ and 369 (58),
m
m
m
d6): 1H, d 12.5 (s,br, 1H, C(1)OH), 7.86 (s, 1H, C(3)H), 7.54 (d, 1H,
C(6)H), 7.09 (t, 1H, C(7)H), 7.15 (t, 1H, C(8)H), 9.46 (d, 1H,
C(9)H), 7.23, 7.30, 7.40 (m, 45H, H(PPh3)); 13C, d 171.4 C(1),
125.4 C(2), 132.0 C(3), 142.8 C(4), 135.5 C(5), 131.4 C(6), 131.6
C(7) 125.9 C(8), 127.7 C(9),133.2 (d, Co(Ph3), J = 16.8), 128.8 (d,
Cm(Ph3), J = 9.1), 129.8 Cp(Ph3); 31P {1H}, d 7.63 (s), 31.4 (s). NMR
(CDCl3): 1H, d 8.11 (s, 1H, C(3)H), 7.67 (d, 1H, C(6)H), 6.69 (t, 1H,
C(7)H), 6.93 (t, 1H, C(8)H), 9.11 (d, 1H, C(9)H), 7.21, 7.26, 7.36
(m, 45H, H(PPh3)). 13C, d 168.7 C(1), 125.5 C(2), 135.0 C(3), 138.4
C(4), 135.8 C(5), 130.2 C(6), 131.9 C(7) 127.8 C(8), 128.5
C(9),133.6 (d, Co(Ph3), J = 17.2), 128.8 (d, Cm(Ph3), J = 9.5), 129.7
Cp(Ph3).
[(AgPPh3)]+. IR (cm–1): 1719 vs,
m(C@O); 1222 m/1268 m, m(C–O);
1479 vs, 1434 vs,
m
(PPh3). NMR (DMSO-d6): 1H, d 12.50 (s,br, 1H,
C(1)OH), 7.95 (s, 1H, C(3)H), 9.54 (s, 1H, C(5)OH), 6.79 (d, 1H,
C(6)H), 7.00 (pst, 1H, C(7)H), 6.95 (t, 1H, C(8)H), 8.97 (d, 1H,
C(9)H), 7.23, 7.33, 7.58 (m, 45H, H(PPh3)); 13C, d 172.0 C(1),
128.7 C(3), 134.3 C(4), 155.3 C(5), 115.0 C(6), 128.3 C(7) 118.0
C(8), 133.2 (d, Co(Ph3), J = 16.8), 128.8 (d, Cm(Ph3), J = 7.6), 129.7
Cp(Ph3); 31P {1H}, d 6.2 (s), 31.5 (s).
2.2.2. [Ag(PPh3)3(H-o-mpspa)] (2)
2.2.6. [Ag(PPh3)3(H-p-hpspa)] (6)
H2-o-mpspa (0.11 g, 0.52 mmol), Ag(PPh3)3(NO3) (0.5 g,
0.52 mmol), NaOAc (0.07 g, 0.84 mmol), CHCl3 (20 cm3), H2O
(30 cm3), yellow crystals. Yield 87%. M.p.: 166 °C. Anal. Calc. for
H2-p-hpspa (0.045 g, 0.23 mmol), Ag(PPh3)3(NO3) (0.2 g,
0.23 mmol), NaOAc (0.02 g, 0.23 mmol), CHCl3 (10 cm3), H2O
(20 cm3), yellow crystals. Yield 78%. M.p.: 157 °C. Anal. Calc. for
C64H54O3SP3Ag: C, 69.6; H, 4.7; S, 2.9. Found: C, 69.7; H, 5.0; S,
C63H52O3SP3Ag: C, 69.5; H, 4.7; S, 2.9. Found: C, 69.3; H, 4.9; S,
2.9%. MS (FAB): the main signals for metallated species are at m/
z 1319 (7%), [M]+; 949 (2), [(AgPPh3)2-o-mpspa]+; 631 (100),
[Ag(PPh3)2]+ and 369 (60), [(AgPPh3)]+. IR (cmÀ1): 1715 vs,
2.7%. MS (FAB): the main signals for metallated species are at m/
z 1305 (2%), [M]+; 935 (8), [(AgPPh3)2-p-hpspa]+; 631 (100),
[Ag(PPh3)2]+ and 369 (79), [(AgPPh3)]+. IR (cmÀ1): 1718 vs,
m
m
(C@O); 1241 m,
m(C–O); 2836 w, ms(OCH3); 1479s, 1434 vs,
(PPh3). NMR (DMSO-d6): 1H, d 7.93 (s, 1H, C(3)H), 9.21 (d, 1H,
m
(C@O); 1223 m/1268 m, m(C–O); 1479 s, 1434 vs, m(PPh3). NMR
(DMSO-d6): 1H, d 8.12 (d, 2H, C(5)H, C(9)H), 6.66 (d, 2H, C(6)H,
C(8)H), 9.63 (s,br, 1H, C(7)OH), 7.25, 7.34, 7.42, 7.62 (m, 46H,
C(3)H, H(PPh3)); 13C, d 171.8 C(1), 115.8 C(2), 125.9 C(3), 137.1
C(4), 129.6 C(5) and C(9), 114.5 C(6) and C(8), 156.7 C(7), 133.3
(d, Co(Ph3), J = 18.3), 128.8 (d, Cm(Ph3), J = 9.1), 129.8 Cp(Ph3); 31P
{1H}, d 8.5 (s), 31.5 (s).
C(6)H), 6.71 (t, 1H, C(7)H), 7.16 (pst, 1H, C(8)H), 6.91 (d, 1H,
C(9)H), 3.73 (s, 3H, OCH3), 7.23, 7.32, 7.41, 7.61 (m, 45H,
H(PPh3)); 13C, d 172.0 C(1), 128.3 C(2), 133.2 C(3), 126.4 C(4),
156.8 C(5), 110.3 C(6), 129.3 C(7), 119.3 C(8), 128.8 C(9), 55.4
C(OCH3), 133.3 (d, Co(Ph3), J = 18.3), 128.9 (d, Cm(Ph3), J = 7.6),
129.9 Cp(Ph3); 31P {1H}, d 8.7 (s), 31.5 (s).
2.2.3. [Ag(PPh3)3(H-p-mpspa)] (3)
2.3. Crystallography
H2-p-mpspa (0.05 g, 0.24 mmol), Ag(PPh3)3(NO3) (0.23 g,
0.24 mmol), NaOAc (0.02 g, 0.24 mmol), CHCl3 (10 cm3), H2O
(20 cm3), yellow crystals. Yield 81%. M.p.: 161 °C. Anal. Calc. for
2.3.1. X-ray data collection and reduction
Single crystals of [Ag(PPh3)3(HClpspa)] (1), [Ag(PPh3)3
(H-o-mpspa)] (2), [Ag(PPh3)3(H-p-mpspa)] (3), [Ag(PPh3)3(Hcpa)]
(4), [Ag(PPh3)3(H-o-hpspa)]ÁEtOH (5) and [Ag(PPh3)3(H-p-hpspa)]
(6) were mounted on glass fibres for data collection in a Bruker
C64H54O3SP3Ag: C, 69.6; H, 4.7; S, 2.9. Found: C, 69.3; H, 5.0; S,
2.7%. MS (FAB): the main signals for metallated species are at m/
z 1319 (2%), [M]+; 949 (13), [(AgPPh3)2-p-mpspa]+; 631 (100),
[Ag(PPh3)2]+ and 369 (54), [(AgPPh3)]+. IR (cmÀ1): 1715 vs,
Smart CCD automatic diffractometer at 293 K using Mo K
a radi-
m
m
(C@O); 1252 s,
m
(C–O); 2835 w,
m
s(OCH3); 1479 s, 1434 vs,
ation (k = 0.71073 Å).
(PPh3). NMR (DMSO-d6): 1H, d 12.30 (s,br, 1H, C(1)OH), 7.54 (s,
All crystallographic data were corrected for Lorentz and polari-
sation effects using SAINT [20] and multiscan absorption corrections
were applied using SADABS [21]. The structures were solved by direct
methods and refined by full-matrix least squares on F2 using
SHELX97 [22]. All non-H atoms were refined anisotropically. H atoms
were placed at their ideal positions and refined as riders – except
for the carboxyl hydrogen atoms bound to O(1), which were re-
fined isotropically. Graphics were produced with PLATON and MER-
CURY [23]. The crystal data, experimental details and refinement
results are summarized in Table 1.
The methylene C(6) group of the cyclopentanone fragment in 4
is affected by disorder. The disorder was modelled by the refine-
ment of the occupancy factor of two equivalent groups, which con-
verged to values close to 50%. This value was fixed in the last stage
of the refinement.
1H, C(3)H), 8.26 (d, 2H, C(5)H, C(9)H), 6.71 (d, 2H, C(6)H, C(8)H),
3.71 (s, 3H, OCH3), 7.20, 7.29, 7.38 (m, 45H, H(PPh3)); 13C, d
171.5 C(1), 128.6 C(2), 132.1 C(3), 130.5 C(4), 132.0 C(5) and
C(9), 112.9 C(6) and C(8), 158.1 C(7), 54.9 C(OCH3), 133.3 (d,
Co(Ph3), J = 16.8), 128.8 (d, Cm(Ph3), J = 7.6), 129.8 Cp(Ph3); 31P
{1H}, d 9.0 (s), 31.5 (s).
2.2.4. [Ag(PPh3)3(Hcpa)] (4)
H2cpa (0.04 g, 0.25 mmol), Ag(PPh3)3(NO3) (0.25 g, 0.25 mmol),
NaOAc (0.025 g, 0.30 mmol), CHCl3 (12 cm3), H2O (25 cm3), brown
crystals. Yield 86%. M.p.: 165 °C. Anal. Calc. for C61H54O2SP3Ag: C,
69.6; H, 5.2; S, 3.1. Found: C, 69.5; H, 5.2; S, 3.0%. MS (FAB): the
main signals for metallated species are at m/z 1265 (2%), [M]+;
987 (16), [(AgPPh3)2cpa]+; 631(100), [Ag(PPh3)2]+ and 369 (77),

56
E. Barreiro et al. / Polyhedron 30 (2011) 53–60
Table 1
Crystal data for [Ag(PPh3)3(HClpspa)] (1), [Ag(PPh3)3(H-o-mpspa)] (2), [Ag(PPh3)3(H-p-mpspa)] (3), [Ag(PPh3)3(Hcpa)] (4), [Ag(PPh3)3(H-o-hpspa)]ÁEtOH (5) and [Ag(PPh3)3(H-p-
hpspa)] (6).
Compound
[Ag(PPh3)3(HClpspa)] (1)
[Ag(PPh3)3(H-o-
mpspa)] (2)
[Ag(PPh3)3(H-p-
mpspa)] (3)
[Ag(PPh3)3(Hcpa)]
(4)
[Ag(PPh3)3(H-o-
hpspa)]ÁEtOH (5)
[Ag(PPh3)3(H-p-
hpspa)] (6)
Empirical
formula
M
Crystal system
Space group
a (Å)
C
63H51AgClO2P3S
C64H54AgO3P3S
C64H54AgO3P3S
C61H54AgO2P3S
C65H58AgO4P3S
C63H52AgO3P3S
1108.33
triclinic
P1
1103.91
triclinic
1103.91
monoclinic
P2(1)/c
13.9439(8)
14.2274(8)
27.3290(16)
90
94.7890(10)
90
5402.7(5)
4
1051.88
triclinic
1135.95
monoclinic
P2(1)/c
17.869(2)
14.0708(15)
25.1300(18)
90
117.555(5)
90
5601.7(10)
4
1089.89
monoclinic
Pn
12.1826(11)
13.1205(12)
16.9022(15)
90
96.647(2)
90
2683.5(4)
2
ꢀ
ꢀ
P1
P1
11.5572(8)
11.8894(8)
12.5549(8)
105.4010(10)
108.0270(10)
109.5150(10)
1409.14(16)
1
12.6746(11)
12.8038(11)
18.9780(15)
89.482(2)
88.158(2)
61.678(2)
2709.7(4)
2
13.4899(10)
13.7625(10)
14.2879(11)
79.58(2)
89.744(2)
86.997(2)
2604.9(4)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc. (Mg/m3)
1.306
0.569
1.353
0.545
1.357
0.547
1.340
0.562
1.347
0.531
1.349
0.550
V (mmÀ1
)
Crystal size
0.38 Â 0.27 Â 0.07
0.26 Â 0.23 Â 0.15
0.05 Â 0.21 Â 0.36 0.20 Â 0.16 Â 0.10
0.26 Â 0.14 Â 0.12
0.30 Â 0.20 Â 0.19
(mm3)
h Range for data 1.87–28.02
collection (°)
1.81–28.10
1.47–28.17
1.45–28.05
1.68–28.04
1.55–28.07
Index ranges
À13 6 h 6 15À13 6 k 6 15 À16 6 h 6 16
À18 6 h 6 18,
À18 6 k 6 18,
À36 6 l 6 20
29166
À17 6 h 6 17,
À16 6 k 6 18,
À13 6 l 6 18
14281
À23 6 h 6 15
À17 6 k 6 18
À32 6 l 6 33
27587
À16 6 h 6 16
À16 6 k 6 17
À16 6 l 6 22
15840
À16 6 l 6 13
À16 6 k 6 16,
À25 6 l 6 16
15893
Reflections
collected
9169
Unique
reflections, R
Final R1, wR2
[I > 2r(I)]
Final R indices
7558[R(int) = 0.0202]
0.0474, 0.1275
0.0568, 0.1328
1.085 and –0.719
11111[R(int) = 0.0685] 12047
[R(int) = 0.0681]
9996[R(int) = 0.0557] 12042[R(int) = 0.1179] 9022[R(int) = 0.0827]
0.0567, 0.0841
0.1310, 0.0994
0.730 and –0.908
0.0524, 0.0841
0.1732, 0.1039
0.990 and –0.445
0.0488, 0.0673
0.1969, 0.0873
0.425 and –0.281
0.0445, 0.0535
0.2982, 0.0931
0.332 and –0.343
0.0440, 0.0562
0.1087, 0.0695
0.480 and –0.340
(all data)
Largest diff.
peak and hole
(e.ÅÀ3
)
Flack parameter
À0.02(2)
nylpropenoato complexes [8,9] and in [Ag(PPh3)3(Hmna)]
(H2mna = 2-sulfanylnicotinic acid) [24] and [Ag(PPh3)3(Hmba)]
3. Results and discussion
3.1. Synthesis
The synthesis of the complexes was carried out in a heteroge-
neous medium (chloroform/water) by using the appropriate H2L li-
gand, [Ag(PPh3)3(NO3)] and NaOAc. The crude, oily product
obtained after agitation, separation and drying of the organic phase
and the elimination of the organic solvent was treated with 1:1
hexane/ethanol. The resulting solution was evaporated at room
temperature. As well as the [M]+ peak, the FAB+ mass spectra of
the compounds all show signals for fragments with different
PPh3 contents, which implies easy cleavage of the Ag–P bonds.
Some cleavage of the Ag–S bonds was also evident.
3.2. Spectroscopy
The IR spectra of the complexes are all similar and provide evi-
dence for deprotonation of the SH group in all cases due to the ab-
sence of a m
(SH) band, which is located near to 2565 cmÀ1 in the
spectra of the free ligands. Furthermore, the positions of the COOH
vibrations are slightly shifted with respect to the position in the
spectra of the free ligands and d(OH) in the complexes overlaps
the PPh3 vibrations.
The 1H NMR spectra do not contain any SH signal and the pres-
ence of a signal at about 12.5 ppm is attributable to the COOH
group. In the 13C NMR spectra the shift of the C(3) signals to higher
field is in keeping with the persistence of the S-coordination ob-
served in the solid state [8–10]. The C(1) signal lies at positions
close to those previously found in the spectra of equivalent sulfa-
Fig. 1. The crystal structure of [Ag(PPh3)3(HClpspa)] (1) together with the
numbering scheme (for clarity only the Cipso of the phenyl triphenylphosphine ring
is indicated).

E. Barreiro et al. / Polyhedron 30 (2011) 53–60
57
(H2mba = 2-sulfanylbenzoic acid) [25]. The room temperature
3.3. X-ray studies
31P{1H} NMR spectra show a singlet at 5.3–9.0 ppm and this is
due to the coordinated PPh3 ligand; a weak singlet near to
31.5 ppm indicates the formation of triphenylphosphine oxide
[26] generated by the oxidation of some of the released triphenyl-
phosphine. The same phenomenon was previously found for
[Ag(PPh3)3(Hfspa)] [9].
3.3.1. Molecular structure
The Ag atom in 1 (Fig. 1) is coordinated to three P atoms from
three PPh3 ligands and to the S atom of the HClpspa moiety, with
the angles (Table 2) around the silver atom showing that the
coordination polyhedron can be described as
a distorted
Fig. 2. (a) The crystal structure of [Ag(PPh3)3(H-o-hpspa)]ÁCH3OH (5) (the phenylphosphine ring and the methanol molecule have been omitted). (b) A view of the crystal
structure of (5).

58
E. Barreiro et al. / Polyhedron 30 (2011) 53–60
tetrahedron. Similar distorted AgSP3 kernels are present in 2–4,
(Table 2; Figs. S1–S3), [Ag(PPh3)3(Hfspa)] [8] [H2fspa = 3-(2-fur-
yl)-2-sulfanylpropenoic acid], [Ag(PPh3)3(Hpspa)] [9], [Ag(PPh3)3-
(Hmna)] [24], [Ag(PPh3)3(Hmba)] [25], [Ag(PPh3)3(La)] [La =
4-(methylthio)-2-thioxo-1,3-dithiole-2-thiolate] [27] and [Ag- (PPh3)3
(Lb)] [Lb = 1,2-dicyano-1-(methylthio)ethene-2-thiolate] [27]. In
these complexes the structural parameters of the kernel do not
differ significantly; the Ag–S distance ranges from 2.5766(16) Å
in 4 to 2.6524(17) in 1 and the Ag–P distance ranges from
2.5164(12) Å in 2 to 2.6495(8)Å in the La derivative. 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 ([Ag(PPh3)3(Hfspa)]). The Hpspa
and Hmna derivatives are also only slightly distorted.
parameters can be compared with those of thioxoketones [28–
30] but a more relevant comparison can be made with the O–HÁÁÁS
intramolecular hydrogen bond present in 3-thioxo-2-pyridinecarb-
oxylic acid [30,31] or with that present in some forms of
[Au(Pcy3)(2-Hmba)] [13]. These latter compounds contain a –
C(S)–CH–COOH fragment instead of C(S)–COOH, but in all cases a
COOH group and an S atom are involved and similar SÁÁÁO distances,
slightly longer SÁÁÁH distances and narrower O–HÁÁÁS angles are
found in the complexes reported here. The formation of this intra-
molecular bond is possible due to (or the bond is responsible for)
the appropriate position of the COOH group with respect to the S
atom. For the complexes included in this paper, the angle between
the S–C(2)–C(3)–C(4) and the C(1)–O(1)–O(2) planes range from
11(2)° in 1 to 3(2)° in 4.
Another common structural feature is the intramolecular
hydrogen bond between the COOH group and the S atom. The geo-
metrical parameters of this bond are shown in Table 3; the values
are all similar to each other and also to those previously described
for [Ag(PPh3)3(Hfspa)] [8] and [Ag(PPh3)3(Hpspa)] [9]. These
3.3.2. Crystal packing
Compounds 1–4 consist of discrete molecular units that are
packed by very weak C–HÁÁÁO and C–HÁÁÁ
p interactions. In com-
pound 1, the asymmetric molecules of [Ag(PPh3)3(HClpspa)], in a
Fig. 3. (a) The crystal structure of [Ag(PPh3)3(H-p-hpspa)] (6) together with the numbering scheme. (b) A view of the polymeric structure of (6).

E. Barreiro et al. / Polyhedron 30 (2011) 53–60
59
Table 2
Selected interatomic distances (Å) and angles (°) for complexes [Ag(PPh3)3(HClpspa)] (1), [Ag(PPh3)3(H-o-mpspa)] (2), [Ag(PPh3)3(H-p-mpspa)] (3), [Ag(PPh3)3(Hcpa)] (4),
[Ag(PPh3)3(H-o-hpspa)].EtOH (5) and [Ag(PPh3)3(H-p-hpspa)] (6).
1
2
3
4
5
6
(a) Ag environment
Ag–P(2)
Ag–P(1)
Ag–P(3)
Ag–S
2.5438(17)
2.5792(19)
2.6403(16)
2.6524(17)
2.5915(12)
2.6224(12)
2.5164(12)
2.6241(12)
2.5533(12)
2.6433(12)
2.5994(11)
2.6062(13)
2.5614(18)
2.5829(16)
2.6300(17)
2.5766(16)
2.5710(18)
2.5800(17)
2.5657(19)
2.6692(15)
2.5363(18)
2.5995(18)
2.5351(16)
2.6311(17)
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
115.51(5)
109.03(6)
112.14(6)
111.69(6)
110.15(6)
96.79(5)
108.33(4)
112.44(4)
116.00(4)
95.26(4)
106.55(4)
116.12(4)
111.23(4)
114.75(4)
110.71(4)
115.52(4)
104.23(4)
99.42(4)
112.11(6)
112.38(5)
110.09(5)
113.75(6)
108.70(6)
99.05(6)
112.26(6)
111.48(6)
116.21(6)
100.43(6)
102.20(6)
112.79(6)
113.12(5)
110.52(6)
114.75(6)
104.90(6)
88.23(5)
123.54(6)
(b) H2xspa
O(1)–C(1)
O(2)–C(1)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
1.348(11)
1.208(11)
1.486(12)
1.360(10)
1.477(11)
1.328(5)
1.191(5)
1.518(6)
1.342(5)
1.457(6)
1.308(8)
1.160(6)
1.535(8)
1.378(7)
1.472(7)
1.341(9)
1.159(9)
1.513(10)
1.363(8)
1.524(8)
1.329(7)
1.191(7)
1.501(9)
1.375(7)
1.458(8)
1.323(7)
1.204(7)
1.503(9)
1.350(7)
1.458(8)
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
119.0(9)
114.6(8)
126.4(8)
112.5(7)
131.2(6)
116.2(5)
119.5(5)
114.5(4)
126.0(5)
114.7(4)
129.6(4)
115.5(3)
118.9(8)
113.9(7)
127.1(7)
112.9(5)
128.0(5)
119.2(5)
120.3(9)
108.8(8)
131.0(9)
115.5(7)
124.5(6)
119.9(6)
125.8(8)
113.4(7)
125.8(8)
113.4(6)
128.9(6)
117.7(5)
118.8(7)
114.9(6)
126.2(7)
116.2(6)
127.7(5)
116.1(5)
C(1)–C(2)–S
conformational enantiomer, are packed in the non-centrosymmet-
ric space group P1 (No. 1). The intermolecular interactions are
likely able to induce head-to-head aggregates in compounds 2–4
and, consequently, both conformational enantiomers are present
in centrosymmetric (achiral) crystals. In contrast, [Ag(PPh3)3(H-o-
hpspa)]ÁEtOH (5) and [Ag(PPh3)3(H-p-hpspa)] (6) contain an addi-
tional OH group that can participate in intermolecular hydrogen
bonding to form polymeric structures.
The structures of the Ag(PPh3)3(H-o-hpspa) and Ag(PPh3)3(H-p-
hpspa) units present in 5 and 6 are respectively shown in Figs. 2a
and 3a and selected bond distances and angles for these com-
pounds are given in Table 2. Note the presence in 6 of two shorter
Ag–P bond distances and the narrowest and the widest tetrahedral
angles of the compounds described in this paper. The CO2H group
in 5 is involved in the intramolecular O–HÁÁÁhydrogen bond and in
an intermolecular hydrogen bond. In the latter interaction, the O(2)
atom of the carboxylic acid group and the OH group of the ethanol
molecule are involved in a moderate hydrogen bond [O(1E)–
H(1E)ÁÁÁO(2) = 0.97, 1.97, 2.717(6) Å, 132.3°]. Besides, the O atom
also behaves as a hydrogen bond acceptor with the –OH group of
y + 1/2,Àz À 1/2]. On the basis of these two bonds, each ethanol
molecule bridges two neighbouring [Ag(PPh3)3(H-o-hpspa)] units
to give rise to chains running along the b axis, as depicted in
Fig. 2b.
The orientation of the OH group in the phenyl ring of the
H-p-hpspa ligand allows this kind of interaction to be established
directly between the molecules of 6 through hydrogen bonding
between the former group and the carboxylic acid oxygen
[O(30)–H(30)ÁÁÁO(2)#1 = 0.82, 1.98, 2.777(6) Å, 163.3°], #1 = xÀ1/2,
Ày+1, zÀ1/2, a situation that results in chains as shown in Fig. 3b.
The structural parameters of the O–HÁÁÁO hydrogen bond pres-
ent in 5 and 6, when compared with those described previously
for systems in which equivalent –OH groups were involved
[32,33], reveal longer OÁÁÁO distances and narrower O–HÁÁÁO angles
in this case. As far as the structural parameters of the COOH group
are concerned, differences can be observed that are related with
the type of hydrogen bond in which the group is involved. More
marked differences between the two C–O distances are observed
when the group is involved in the O–HÁÁÁS intramolecular hydrogen
bond and less marked differences are found in 5, 6 and other
complexes in which the carboxylic acid dimer synthon is present
[10–13].
the
phenyl
ring
of
the
H-o-hpspa
ligand
[O(3)–
H(3)ÁÁÁ(1E)#1 = 0.843(5), 2.018(3), 2.685(6) Å, 135.4(4)°; #1 = Àx,
4. Conclusions
Table 3
Structural parameters involved in the intramolecular hydrogen bond O–HÁ Á ÁS present
The synthesis and the structural study of complexes of the type
[Ag(PPh3)3(Hxspa)] [where H2xspa = R–CH@C(SH)–COOH] and
[Ag(PPh3)3(Hcpa)] [where H2cpa = C5H8@C(SH)–COOH] enabled
the identification of two classes of structures. One type of structure
is present in [Ag(PPh3)3(HClpspa)] (1), [Ag(PPh3)3(H-o-mpspa)] (2),
[Ag(PPh3)3(H-p-mpspa)] (3) and [Ag(PPh3)3(Hcpa)] (4) and this
contains an intramolecular O–HÁÁÁS hydrogen bond between the S
atom and one of the O atoms of the COOH group. The introduction
of –OH substituents in the phenyl ring in [Ag(PPh3)3(H-o-
hpspa)]ÁEtOH (5ÁEtOH) and [Ag(PPh3)3(H-p-hpspa)] (6) leads to
the formation of an intermolecular O–HÁÁÁO hydrogen bond involv-
ing the new –OH group and one of the O atoms of the COOH group.
The formation of this bond gives rise to polymeric structures and is
in [Ag(PPh3)3(HL)] complexes.
Compound d(O–H)
d(HÁÁÁS)
d(OÁÁÁS)
<(OHS)
Angle (°)
between the
planes
C(1)–O(1)–
O(2)/S–C(2)–
C(3)–C(4)
(1)
(2)
(3)
(4)
(5)
(6)
0.82
0.84
0.67(6)
2.26
2.23
2.38(7)
2.851(7) 129.6
2.848(3) 130.5
2.924(7) 139(9)
11(2)
8.0(6)
3.7(9)
0.841(8) 2.1819(18) 2.834(7) 134.4(4) 3(2)
0.82
0.82
2.25
2.25
2.858(5) 130.8
2.853(5) 130.1
5.8(3)
6.7(8)

60
E. Barreiro et al. / Polyhedron 30 (2011) 53–60
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compatible with the presence of the O–HÁÁÁS intramolecular hydro-
gen bond, which is also present in these compounds.
[11] E. Barreiro, J.S. Casas, M.D. Couce, A. Sánchez, J. Sordo, J.M. Varela, E.M.
Vázquez-López, J. Inorg. Biochem. 102 (2008) 184.
Acknowledgements
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We thank the Spanish Ministry of Science and Technology for
financial support under projects BQU2002-04524-C02-01 and
BQU2002-04524C02-02.
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Appendix A. Supplementary data
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CCDC 785399, 785400, 785401, 785402, 785403 and 785404
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge via http://www.ccdc.
cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
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