Synthesis, structure and bactericide activity of (aminophosphane)gold(I) thiolate complexes

Article abstract of DOI:10.1002/ejic.201001195

Reaction of the aminophosphane ligands 2-(diphenylphosphanylamino) pyridine (Ph₂PNHpy, 1) and 3-(diphenylphosphanylamino)-1,2,4-triazole [Ph₂PNH(Htrz), 2] with the gold(I) compound [AuCl(tht)] (tht = tetrahydrothiophene) gave the com

Full text of DOI:10.1002/ejic.201001195

FULL PAPER
DOI: 10.1002/ejic.201001195
Synthesis, Structure and Bactericide Activity of (Aminophosphane)gold(I)
Thiolate Complexes
María F. Fillat,[a] M. Concepción Gimeno,*[b] Antonio Laguna,[b] Encarnación Latorre,[b]
Lourdes Ortego,[b] and M. Dolores Villacampa*[b]
Keywords: Gold / Biological activity / P ligands / Thiols / X-ray diffraction
Reaction of the aminophosphane ligands 2-(diphenylphos-
phanylamino)pyridine (Ph2PNHpy, 1) and 3-(diphenylphos-
phanylamino)-1,2,4-triazole [Ph2PNH(Htrz), 2] with the
gold(I) compound [AuCl(tht)] (tht = tetrahydrothiophene)
spective thiol HSR [HSR = 2-mercaptopyridine (2-HSpy), 2-
thiocytosine (2-HTC) or 6-thioguanine (6-HTG)]. The suscep-
tibility of Enterococcus faecalis ATCC25923, Staphylococcus
aureus ATCC29213 and Escherichia coli TG1 towards the
synthesized gold(I) complexes was evaluated. Some of them
exhibit powerful anti-bacterial activity, being more efficient
against Gram-positive microorganisms. Complexes 7–9 and
11 present excellent activity against E. faecalis, whereas the
highest sensitivity of S. aureus was against complexes 7 and
8. The structures of complexes 4, 5, 8 and 9 were determined
by X-ray structural analysis. None of the four compounds
shows aurophilic interactions between the gold(I) centres in
the crystals. The four complexes possess intermolecular hy-
drogen bonds that lead to supramolecular arrangements.
gave
the
complexes
[AuCl(Ph2PNHpy)]
(3)
and
[AuCl{Ph2PNH(Htrz)}] (4), respectively. A series of new
gold(I) thiolate derivatives were synthesized from the reac-
tions of complex 3 or 4 with 1 equiv. of a deprotonated thiol
ligand. Complexes [Au(SR)(PPh2NHpy)] (5–8) were prepared
by reaction of complex 3 with the corresponding thiol HSR
[HSR = 2-mercaptopyridine (2-HSpy), 2-mercaptonicotinic
acid (2-H2-mna), 2-thiouracil (2-HTU) or 2-thiocytosine (2-
HTC)] in the presence of sodium carbonate or triethylamine.
Complexes [Au(SR){PPh2NH(Htrz)}] (9–11) were prepared by
the treatment of complex 4 with triethylamine and the re-
them very recent and encouraging, made in the fight against
malaria, leishmaniasis and other parasitic diseases with
gold(I) complexes. The article of Jackson-Rosario et al.[6]
reports that Auranofin inhibits the growth of Clostridium
difficile through the formation of auranofin–selenium, thus
interfering in the selenium metabolism and the production
of selenoproteins, and Eiter et al.[7] have reported the strong
activity against Mycobacterium tuberculosis of gold(I) ana-
logues of a platinum antitumour agent.
Herein we report on the synthesis and characterization
of a series of gold(I) thiolate derivatives with two different
aminophosphanes: 2-(diphenylphosphanylamino)pyridine[8]
(Ph2PNHpy) and 3-(diphenylphosphanylamino)-1,2,4-tri-
azole [Ph2PNH(Htrz)]. Aminophosphanes are an important
type of compounds because of the interest in hemilabile li-
gands in coordination chemistry and catalysis, and they are
also suitable for producing metal complexes capable of
forming hydrogen bonds, which is an important topic in
bioinorganic chemistry. Several gold(I) complexes with ami-
nophosphanes have been reported to date,[9] but as far as
we are aware not many with thiolato ligands.[10] The forma-
tion of gold(I) thiolate derivatives with aminophosphane li-
gands can enhance the properties shown by (phosphane)-
gold thiolate compounds and the possibility of forming hy-
drogen bonds, the final objective being the development of
biologically active molecules. The susceptibility of several
Introduction
The chemistry community has shown growing interest in
the synthesis of gold(I) complexes that display biological
properties, mainly anticancer and antibacterial activity, and
in the understanding of their mechanisms of action, as
shown in recent reviews.[1] Among them, derivatives con-
taining the P–Au–S unit have gained considerable attention
in part because they are structurally related to Auranofin
(2,3,4,6-tetra-O-acetyl-β-1-thio-d-glucopyranosato-S)(tri-
ethylphosphane)gold(I), a drug used for the treatment of
rheumatoid arthritis, the antitumour and antimicrobial ac-
tivities of which have been investigated.[1b,1c,2,3] Although
the antimicrobial properties of gold(I) derivatives have been
less investigated than their cytotoxic activities,[3b,3c,3f,4] the
increasing multidrug resistance exhibited by many ubiqui-
tous pathogens points to these compounds as promising al-
ternatives to antibiotic chemotherapy. Some recent articles
have reported important results, for example, the review by
Navarro[5] on antiparasitic agents shows the efforts, some of
[a] Departamento de Bioquímica y Biología Molecular y Celular,
Facultad de Ciencias e Instituto de Biocomputación y Física de
Sistemas Complejos (BIFI), Universidad de Zaragoza,
50009 Zaragoza, Spain
[b] Departamento de Química Inorgánica, Instituto de Ciencia de
Materiales de Aragón, Universidad de Zaragoza – CSIC,
50009 Zaragoza, Spain
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M. C. Gimeno, M. D. Villacampa et al.
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bacteria towards the gold complexes has been evaluated,
and some of them exhibit excellent antimicrobial activities
against two epidemiologically important Gram-positive
bacteria, namely Enterococcus faecalis and Staphylococcus
aureus, and moderate bacteriostatic properties against the
Gram-negative Escherichia coli.
Results and Discussion
Scheme 1.
Synthesis and Characterization
The
ligand
2-(diphenylphosphanylamino)pyridine
(dppap, Ph2PNHpy, 1) was prepared by the reaction of
chlorodiphenylphosphane, 2-aminopyridine and Et3N in
THF as solvent, as described previously by Aucott et al.[8]
The synthesis of the gold(I) complex [AuCl(Ph2PNHpy)] (3)
by the reaction of [AuCl(tht)] and the phosphane ligand 1
in CH2Cl2 was also described in this paper (see Scheme 1).
The new ligand 3-(diphenylphosphanylamino)-1,2,4-tri-
azole [Ph2PNH(Htrz), 2] was synthesized in a way similar
to that for 1 by reaction of chlorodiphenylphosphane, 3-
amino-1,2,4-triazole and Et3N in THF. The 1H NMR spec-
trum shows, apart from the multiplets of the phenyl groups,
a broad singlet for 5-H of the triazole at δ = 8.15 ppm, a
broad signal for HN(Htrz) at δ = 13.04 ppm and another
for the H of the HN–P group at δ = 12.55 ppm. The
Scheme 2.
The gold(I) thiolate complexes 5–11 were prepared by
31P{1H} NMR spectrum shows a singlet at δ = 36.90 ppm. the reaction of the (phosphane)gold(I) chloride 3 or 4 with
The reaction of Ph2PNH(Htrz) (2) with [AuCl(tht)] led to 1 equiv. of the appropriate thiolato ligand (see Schemes 3
the complex [AuCl{Ph2PNH(Htrz)}] (4) (see Scheme 2). and 4). Complexes 5–8 (Scheme 3) were synthesized by the
Complex 4 displays one resonance in its 31P{1H} NMR reaction between the (aminophosphane)gold(I) chloride 3
spectrum at δ = 54.01 ppm, which confirms the coordina- and the respective thiol HSR [HSR = 2-mercaptopyridine
tion to the gold(I) centre through the phosphorus atom. In (2-HSpy) (for 5), 2-mercaptonicotinic acid (2-H2-mna) (for
the IR spectrum the ν(Au–Cl) band characteristic of gold(I) 6), 2-thiouracil (2-HTU) (for 7) or 2-thiocytosine (2-HTC)
coordinated to chloride appears at 316 cm–1. In the ESI+ (for 8)] in the presence of sodium carbonate or triethyl-
1
mass spectrum the fragment [M – Cl]+ is present at m/z (%) amine. The H and 13C{1H} NMR spectra show the ex-
= 465 (100).
pected resonances. A broad singlet was assigned to the
Scheme 3. Reagents: (i) 2-HSPy, K2CO3; (ii) 2-H2-mna, NEt3; (iii) 2-HTU, NEt3; (iv) 2-HTC, NEt3.
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(Aminophosphane)gold(I) Thiolate Complexes
–NH–P– proton, and four separated signals were attributed nal due to the aromatic protons and a broad singlet at δ =
to the pyridine protons of the aminophosphane ligand. 6.49 ppm for the amino group of the 2-thiocytosine. Com-
1
Furthermore, the H NMR spectrum of complex 5 shows plex 11 presents the resonance of the amino group at δ =
four different resonances that were assigned to the 2-thio- 5.97 ppm and two broad singlets corresponding to the NH
pyridine protons. Complex 6 presents three broad signals group and the aromatic proton of the 6-thioguanine. As-
1
attributed to the 2-mercaptonicotinic acid aromatic protons, signments of the signals were made on the basis of 2D H
and in complex 7 one of the doublets corresponding to the COSY and HSQC spectra. Complete spectroscopic data for
2-thiouracil group is overlapped by phenyl protons. The IR ligand 2 and complexes 4 and 9–11 are presented in the
spectrum of solid complex 6 presents an intense carbonyl Exp. Sect. In the ESI+ mass spectra of 9–11 the protonated
stretching band at 1677 cm–1, almost unchanged from that molecular peaks [M + H]+ appear at m/z (%) = 576 (100),
of the free ligand (1675 cm–1 for 2-H2-mna), which suggests 592 (100) and 632 (100), respectively.
that the carboxylic group remains protonated and does not
coordinate to the metal atom. The IR spectrum of solid
Crystallography
compound 7 presents a stretching carbonyl band at
1631 cm–1 (1680 cm–1 in the free ligand), which indicates
that the thiouracil is coordinated to the gold centre through
the sulfur atom in the form of thiolate, and consequently
there is a –C=O bond at the 4-position.[11,12] In the 1H
NMR spectrum of complex 8 a broad singlet at δ =
12.30 ppm was assigned to the NH2 group and one doublet
and one broad signal to the aromatic protons of the 2-thio-
cytosine group. The 31P{1H} NMR spectra of these com-
pounds show single resonances significantly downfield rela-
tive to their precursor (31P{1H} NMR: δ = 53.47 ppm in
complex 3). In addition, the 2D 1H COSY and HSQC spec-
tra were recorded to confirm the proton assignments. Com-
plete spectroscopic data for complexes 5–8 are presented in
the Exp. Sect. In the ESI+ mass spectra of 5–8 the proton-
ated molecular peaks [M + H]+ appear at m/z (%) = 586
(99), 630 (10), 603 (89) and 602 (98), respectively.
We confirmed the molecular structures of complexes 4,
5, 8 and 9 (Figures 1, 2, 3 and 4, respectively) by an X-ray
crystallographic study. Selected bond lengths and angles are
shown in Table 1. Complexes 4, 5 and 8 crystallize in the
monoclinic system and complex 9 in the triclinic system.
None of the four compounds shows aurophilic interactions
The reactions of complex 4 with the thiols 2-mercap-
topyridine (2-HSpy), 2-thiocytosine (2-HTC) or 6-thiogu-
anine (6-HTG) and triethylamine led to the complexes 9–
11, respectively (see Scheme 4). The 31P{1H} NMR spectra
show single resonances with the expected downfield shifts
1
compared with their precursor (complex 4). The H NMR
spectra show signals for the protons of the aminophos-
phane ligand and the thiolate group in the appropriate ra-
tio. In the spectrum of complex 9 four signals were assigned
to the protons of the 2-mercaptopyridine. In the spectrum
of complex 10 were identified one doublet and a broad sig-
Figure 1. Structure of complex 4 (50% probability ellipsoids).
Scheme 4. Reagents: (i) 2-HSpy, NEt3; (ii) 2-TC, NEt3; (iii) 6-HTG,
NEt3.
Figure 2. Structure of complex 5 (50% probability ellipsoids).
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between the gold(I) centres in the crystals. The Au atoms Table 1. Selected bond lengths [Å] and angles [°] for complexes 4,
5, 8, and 9.
lie in the almost linear geometry expected for gold(I) deriv-
atives defined by the P atom of the corresponding amino-
phosphane and the chloride (4) or the S atom of the thiol-
ato ligand (5, 8, and 9). The P–Au–Cl bond angle in 4 is
Complex 4
Au(1)–P(1)
Au(1)–Cl(1)
2.223(2)
2.293(2)
P(1)–N(1)
N(1)–C(21)
C(21)–N(1)–P(1)
1.679(7)
1.391(1)
122.4(6)
174.49(8)°, and the P–Au–S bond angles range from P(1)–Au(1)–Cl(1) 174.49(8)
177.26(4)° in 9 to 177.76(2)° in 8.
Complex 5
Au(1)–P(1)
Au(1)–S(1)
P(1)–Au(1)–S(1)
2.251(2)
2.308(2)
177.62(8)
P(1)–N(1)
S(1)–C(31)
C(31)–S(1)–Au(1) 103.4(3)
1.680(7)
1.776(9)
Complex 8
Au(1)–P(1)
Au(1)–S(1)
P(1)–Au(1)–S(1)
2.2464(8)
2.3130(8)
177.76(2)
S(1)–C(1)
P(1)–N(4)
C(1)–S(1)–Au(1)
1.761(3)
1.670(2)
101.27(9)
Complex 9
Au(1)–P(1)
Au(1)–S(1)
P(1)–Au(1)–S(1)
2.2500(11) S(1)–C(1)
2.3035(11) P(1)–N(1)
1.764(5)
1.677(4)
102.93(14)
177.26(4)
C(1)–S(1)–Au(1)
Figure 3. Structure of complex 8 (50% probability ellipsoids).
Figure 5. Molecules of complex 4 organized into dimers through
hydrogen bonds.
with most of the distances found in related complexes with
the same S–Au–P core.[11–22] The longer Au–P distances in
the thiolate derivatives compared with those in complexes
3 [2.2187(11) Å] and 4 [2.223(2) Å] are in agreement with
the higher trans influence of the thiolato ligand compared
Figure 4. Structure of complex 9 (50% probability ellipsoids).
The Au–P [2.223(2) Å] and Au–Cl [2.293(2) Å] bond with the chlorido ligand.
lengths in complex 4 are similar to those found in the
Complexes 5, 8 and 9 possess intermolecular hydrogen
closely related complex 3 [2.2187(11) and 2.2813(12) Å, bonds that lead to supramolecular arrays. In 5 the interac-
respectively].[8] In the lattice of 4 the molecules are orga- tion between neighbouring molecules through the NHP
nized into dimers as a result of hydrogen bonding between proton and the thiopyridine nitrogen atom as proton ac-
the NH–P proton and one nitrogen atom of the triazole ceptor organizes the molecules into chains (Figure 6). In
group of neighbouring molecules in a head-to-tail arrange- 8 a similar interaction through the NHP proton and one
ment (Figure 5) that is reminiscent of the arrangement ob- thiocytosine nitrogen atom as proton acceptor leads to
served in the solid structure of ligand 1 (Ph2PNHpy).[8]
chains that are organized into a 3D structure through hy-
The Au–P and Au–S distances in complexes 5 [2.251(2) drogen bonds between amino protons and DMSO oxygen
and 2.308(2) Å], 8 [2.2464(8) and 2.3130(8) Å] and 9 atoms (solvent of crystallization) as protons acceptors (Fig-
[2.2500(11) and 2.3035(11) Å] are normal and compare well ure 7). In 9 pairs of molecules are formed by interaction of
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(Aminophosphane)gold(I) Thiolate Complexes
the NHP proton and the triazole N atom in a head-to-tail NH group of the triazole ring and the pyridine nitrogen
fashion, similarly to observations with complex 4. These atom (Figure 8). Hydrogen-bond data for complexes 4, 5, 8
pairs are further joined by hydrogen bonding through the and 9 are presented in Table 2.
Figure 6. Hydrogen-bonding interactions between molecules of complex 5 (arrangement in chains).
Figure 7. 3D structure of molecules of complex 8 formed by hydrogen-bonding interactions (DMSO solvent molecules are involved in
the arrangement).
Figure 8. Hydrogen bonding between pairs of molecules of complex 9.
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Table 2. Hydrogen-bond data for complexes 4, 5, 8, and 9.
D–H···A
d(D–H) [Å]
d(H···A) [Å]
d(D···A) [Å]
Ͻ(DHA) [°]
Complex 4[a]
N(3)–H(3A)···O(1)#1
N(1)–H(1A)···N(2)#2
0.86
0.90
1.91
2.21
2.745(9)
2.821(10)
161.8
124.2
Complex 5[b]
N(1)–H(1)···N(3)#1
Complex 8[c]
0.88
2.09
2.973(10)
177.1
N(3)–H(11)···O(2)
N(3)–H(1)···O(2)#1
N(4)–H(0)···N(1)#2
0.84(3)
0.83(3)
0.83(3)
2.26(3)
2.11(3)
2.06(3)
3.035(3)
2.919(3)
2.881(3)
154(3)
164(3)
176(3)
Complex 9[d]
N(1)–H(1)···N(2)#1
N(3)–H(3A)···N(5)#2
0.77(5)
0.88
2.09(5)
1.91
2.854(5)
2.783(5)
172(5)
170.6
[a] #1: x + 1, y, z; #2: –x + 1, –y + 2, –z + 1. [b] #1: x, y – 1, z. [c] #1: –x, –y + 1, –z + 1; #2: x, y – 1, z. [d] #1: –x + 1, –y + 2, –z;
#2: –x + 1, –y + 1, –z + 1.
many of these microorganisms are resistant to one or more
antibiotics, there is increasing interest in the development
of alternative forms of bacterial control. Because antibiotic
Antimicrobial Activity
The susceptibility of E. faecalis ATCC25923, S. aureus concentrations used in clinical practice usually range be-
ATCC29213 and E. coli TG1 to gold(I) complexes was tween 5 and 50 μm, our results suggest that some of the
evaluated by the Kirby–Bauer disk-diffusion test using the compounds reported in this work might have potential ap-
broad-spectrum antibiotic kanamicin as control. The sol- plications in the impairment of the proliferation of E. fae-
vent used to dissolve the complexes (DMSO) and the li- calis and S. aureus. In contrast, the efficiency of gold(I)
gands 1 and 2 did not inhibit bacterial growth, which indi- complexes against the Gram-negative E. coli TG1 strain
cates that the metal was responsible for the observed activi- was lower, although complexes 8–10 still displayed moder-
ties.
ate bacteriostatic properties. This is in good agreement with
Complexes 3 and 7–11 presented semiquantitative anti- previous studies indicating that gold(I) complexes are, in
microbial activities similar to controls in the disk-diffusion general, less active against Gram-negative than against
tests (not shown), whereas complexes 4–6 exhibited no ac- Gram-positive bacteria.[3b,4d] The lower susceptibility could
tivity against any of the microorganisms tested. Minimum be attributed to the structural differences in the cell walls
inhibitory concentrations (MICs) and minimal bactericidal of those types of microorganisms.[3b,4d] Further studies to
concentrations (MBCs) were determined for complexes dis- identify new bacterial targets as well as the mechanisms dis-
playing significant activity (Table 3). The results show that played by the gold(I) complexes should be performed in
complexes 7–9 and 11 present excellent activity against E. order to outline their potential chemotherapeutic proper-
faecalis, whereas the highest sensitivity of S. aureus was ties.
against complexes 7 and 8.
Table 3. Antimicrobial activities evaluated as minimum inhibitory
concentrations [μm] and minimum bactericidal concentrations [μm].
Conclusions
E. faecalis
MIC MBC
S. aureus
E. coli
MIC MBC
A series of new gold(I) thiolate derivatives with amino-
phosphanes as auxiliary ligands have been synthesized and
characterized. The aminophosphane ligand allows the for-
mation of hydrogen bonding, which is of great importance
in bioinorganic chemistry and can help to produce more
active compounds. The crystal structures of some of the
complexes reveal the formation of supramolecular arrays
through hydrogen bonding, and 2D and 3D motifs have
been found. Some of them exhibit good/satisfactory anti-
MIC
MBC
3
10
5
5
30
50
20
Ͼ50
5
5
40
30
30
Ͼ50
Ͼ50
Ͼ50
50
Ͼ50
Ͼ50
–
7
Ͼ100 Ͼ100
8
30
50
50
–
100
Ͼ100
Ͼ100
9
5
15
5
Ͼ50
Ͼ50
30
10
11
Kanamicin
100
Ͼ100 Ͼ100
50
50
Enterococci and Streptococcus sp. are capable of infecting bacterial activity, being more efficient against Gram-posi-
humans, companion animals and livestock.[23,24] Entero- tive microorganisms. Complexes 7–9 and 11 present excel-
cocci are normal gastrointestinal flora of dairy cows and lent activity against E. faecalis, whereas the highest sensitiv-
cattle, but are also opportunistic pathogens that can cause ity of S. aureus was against complexes 7 and 8. The excel-
intramammary infection (IMI), also known as mastitis, lent activity shown by some of the complexes leads to the
often aggravated by the presence of S. aureus.[25] Because possibility of further biological studies.
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(Aminophosphane)gold(I) Thiolate Complexes
Synthesis of [AuCl{Ph2PNH(Htrz)}] (4): Ph2PNH(Htrz) (2; 0.134 g,
0.5 mmol) was added to a dichloromethane solution (20 mL) of
[AuCl(tht)] (0.160 g, 0.5 mmol). The reaction mixture was stirred
for 1 h, concentrated to around 5 mL, and addition of hexane
(15 mL) led to complex 4 as a white solid. Yield: 0.209 g, 83.50%.
1H NMR: δ = 13.44 (br. s, 1 H, NH triazole), 9.07 (br. s, 1 H, NH-
P), 8.26 (br. s, 1 H, 5-H), 7.70 (m, 4 H, Ph-H), 7.60 (m, 6 H, Ph-
H) ppm. 31P{1H} NMR: δ = 54.01 (s, 1 P, PPh2) ppm. 13C{1H}
Experimental Section
Instrumentation: IR spectra were recorded in the range 4000–
200 cm–1 with a Perkin–Elmer Spectrum 100 spectrophotometer on
solid samples by using an ATR accessory. C, H and N analyses
were carried out with a Perkin–Elmer 2400 Series 2 microanalyser.
Mass spectra were recorded with a VG Austopec by using the ESI
technique. NMR spectra were recorded in [D6]DMSO solution,
most of them with a Bruker ARX 400 spectrometer; some of the
13C{1H} NMR spectra were recorded with a Bruker ARX 300
spectrometer. Chemical shifts are cited relative to SiMe4 (1H, 13C,
external) and 85% H3PO4 (31P, external). Unfortunately, in the
13C{1H} NMR spectra of several complexes we did not observe all
of the signals expected, probably as a consequence of the poor
solubility of the complexes.
Starting Materials: The phosphane ligand Ph2PNHpy (1)[8] and the
starting materials [AuCl(tht)][26] and [AuCl(Ph2PNHpy)][8] (3) were
prepared by applying published procedures. All other chemicals
used were commercially available and used without further purifi-
cation.
2
NMR: δ = 132.74 (d, JP-C = 15.60 Hz, Cortho, PPh2), 132.54 (s,
3
C
para, PPh2), 129.54 (d, JP-C = 12.30 Hz, Cmeta, PPh2) ppm. MS
(ESI+): m/z (%) = 465 (100) [M – Cl]+, 929 (62) [(M – Cl)2 – H]+.
C14H13AuClN4P (500.67): calcd. C 33.58, H 2.62, N 11.19; found
C 33.56, H 2.55, N 10.93.
Synthesis of [Au(Spy)(Ph2PNHpy)] (5): [AuCl(Ph2PNHpy)] (3;
0.102 g, 0.20 mmol) and 2-mercaptopyridine (2-HSpy; 0.022 g,
0.20 mmol) were added to a suspension of K2CO3 (0.014 g,
0.1 mmol) in dichloromethane (20 mL), and the mixture was stirred
for 3 h. The suspension was filtered to remove the KCl formed.
Concentration of the solution to approximately 5 mL and addition
of hexane gave complex 5 as a white solid. Yield: 0.060 g, 51.2%.
1H NMR: δ = 8.81 (br. s, 1 H, NH), 8.19 (m, 1 H, 6Ј-H), 8.06 (m,
1 H, 6-H), 7.79 (m, 4 H, Ph-H), 7.59 (m, 7 H, Ph-H, 4-H), 7.39
Antibacterial Assays: The antibacterial activities of the gold(I) com-
plexes were tested against the Gram-positive strains E. faecalis
ATCC25923 and S. aureus ATCC29213 and the Gram-negative E.
coli TG1. Cells were grown in Luria–Bertani liquid broth or agar
medium at 37 °C. Semiquantitative bioassays were performed by
using the Kirby–Bauer disk-diffusion test. Whatman paper disks
loaded with 4ϫ10–8 mol of each complex dissolved in DMSO were
placed on LB plates containing 200 μL of 8ϫ108 CFU/mL of E.
faecalis, 4ϫ108 CFU/mL of S. aureus or 4ϫ108 CFU/mL of E.
coli cells. Disks loaded with the same concentration of kanamycin
were used as controls. Then the plates were incubated at 37Ϯ2 °C
overnight, and the inhibition diameters were measured. For quanti-
tative determination of the susceptibility to gold(I) complexes,
minimum inhibitory concentrations (MICs) were calculated by
using the broth dilution method. Stock solutions of each complex
in DMSO were prepared at a concentration of 8 mm. Luria–Bertani
liquid broth (2 mL) was supplemented with serial dilutions of the
gold(I) complexes and inoculated with the appropriate bacterial
strain (100 μL) at the CFU/mL indicated above. The tubes were
incubated at 37 °C for 24 h. The MIC is defined as the lowest con-
centration of antimicrobial agent that inhibits visible growth. Mini-
mal bactericidal concentrations (MBCs) were evaluated by streak-
ing in LB plates cells (200 μL) from cultures that in the presence
of gold(I) complexes did not show apparent growth. The presence
of bacterial colonies was monitored after incubation at 37 °C over-
night. All the disk-diffusion tests and MIC and MBC bioassays
were repeated three times.
3
(m, 2 H, 4Ј-H, 5Ј-H), 7.04 (d, JH-H = 8.0 Hz, 1 H, 3-H), 6.87 (m,
2 H, 5-H, 3Ј-H) ppm. 31P{1H} NMR: δ = 59.76 (s, 1 P, PPh2) ppm.
13C{1H} NMR (300 MHz): δ = 167.49 (s, C-2Ј), 155.77 (s, C-2),
148.97 (s, C-6Ј), 147.70 (s, C-6), 138.40 (s, C-4), 135.74 (s, C-4Ј),
2
133.72 (s, Cipso, PPh2), 132.80 (d, JP-C = 16.08 Hz, Cortho, PPh2),
3
132.27 (s, Cpara, PPh2), 129.59 (d, JP-C = 11.83 Hz, Cmeta, PPh2),
126.64 (s, C-5Ј), 118.35 (s, C-3Ј), 116.63 (s, C-5), 112.46 (s, C-3)
ppm. MS (ESI+): m/z (%) = 586 (99) [M + H]+. C22H19AuN3PS
(585.41): calcd. C 45.14, H 3.27, N 7.18, S 5.48; found C 45.34, H
3.13, N 7.33, S 5.12.
Synthesis of [Au(Hmna)(Ph2PNHpy)] (6): 2-Mercaptonicotinic acid
(2-H2-mna; 0.031 g, 0.20 mmol) and NEt3 (0.025 g, 0.034 mL,
0.25 mmol) were added to a dichloromethane solution (20 mL) of
[AuCl(Ph2PNHpy)] (3; 0.102 g, 0.20 mmol). The reaction was
stirred at room temperature for 18 h. After that, the mixture was
washed with a saturated aqueous NaHCO3 solution (50 mL) to
remove the triethylamine hydrochloride, and the organic phase was
dried with Na2SO4. Concentration of the solution to approximately
5 mL and addition of hexane gave complex 6 as a white solid.
Yield: 0.089 g, 70.7%. 1H NMR: δ = 14.45 (br. s, 1 H, COOH),
9.03 (br. s, 1 H, NH), 8.21 (m, 1 H, 6Ј-H), 7.93 (m, 1 H, 6-H), 7.75
(m, 4 H, Ph-H), 7.58 (m, 1 H, 4-H), 7.55 (m, 6 H, Ph-H), 7.38 (m,
1 H, 4Ј-H), 7.07 (m, 2 H, 3-H, 5Ј-H), 6.84 (m, 1 H, 5-H) ppm.
31P{1H} NMR: δ = 59.16 (s, 1 P, PPh2) ppm. 13C{1H} NMR: δ =
2
155.21 (s, C-2), 148.02 (s, C-6), 138.06 (s, C-4), 132.23 (d, JP-C
=
Synthesis of Ph2PNH(Htrz) (2): Et3N (2.3 g, 3.16 mL, 23 mmol)
was added to a solution of 3-amino-1,2,4-triazole (1.68 g, 20 mmol)
in THF (60 mL) under argon, and then the mixture was cooled to
0 °C. Neat chlorodiphenylphosphane (4.41 g, 3.6 mL, 20 mmol)
was added dropwise to this mixture. The mixture was allowed to
warm to room temperature and stirred for 24 h, after which time
it was filtered to remove the triethylamine hydrochloride precipi-
tate. The precipitate was washed with THF (2ϫ20 mL). The wash-
ings and the filtrate were combined and concentrated to dryness
under reduced pressure to leave a white solid. The solid was re-
moved from the flask, washed with diethyl ether (2ϫ10 mL) and
12.70 Hz, Cortho, PPh2), 131.83 (s, Cpara, PPh2), 129.45 (m, Cipso
,
PPh2), 129.09 (m, Cmeta, PPh2), 116.20 (s, C-5), 112.12 (s, C-3) ppm.
MS (ESI+): m/z (%) = 630 (10) [M + H]+. C23H19AuN3O2PS
(629.42): calcd. C 43.89, H 3.04, N 6.68, S 5.09; found C 43.53, H
3.11, N 6.87, S 4.75.
Synthesis of [Au(SR)(Ph2PNHpy)] [R = TU (7), TC (8)]: NEt3
(0.025 g, 0.034 mL 0.25 mmol) was added to
a solution of
[AuCl(Ph2PNHpy)] (3; 0.102 g, 0.20 mmol) and 2-thiouracil (2-
HTU; 0.026 g, 0.20 mmol) or 2-thiocytosine (2-HTC; 0.025 g,
0.20 mmol) in dichloromethane (20 mL), and the mixture was
stirred for 18 h. Complexes 7 and 8 precipitated as white solids and
were filtered off.
1
dried in vacuo. Yield: 4.88 g, 91%. H NMR: δ = 13.04 (br. s, 1 H,
NH, Htrz), 12.55 (br. s, 1 H, NH-P), 8.15 (br. s, 1 H, 5-H), 7.50
(m, 4 H, Ph), 7.40 (m, 6 H, Ph) ppm. 31P{1H} NMR: δ = 36.90 (s,
1 P, PPh2) ppm. C14N4H13P (268.25): calcd. C 62.68, H 4.88, N
20.89; found C 62.47, H 4.61, N 20.79.
1
Complex 7: Yield: 0.106 g, 87.9%. H NMR: δ = 8.84 (br. s, 1 H,
NH-P), 8.06 (m, 1 H, 6-H), 7.70 (m, 12 H, Ph-H, 4-H, 6Ј-H), 7.03
3
3
(d, JH-H = 10.8 Hz, 1 H, 3-H), 6.86 (m, 1 H, 5-H), 5.88 (d, JH-H
Eur. J. Inorg. Chem. 2011, 1487–1495
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1493

M. C. Gimeno, M. D. Villacampa et al.
FULL PAPER
Table 4. Details of data collection and structure refinement for complexes 4, 5, 8 and 9.
4·(C2H5)2O
5
8·(CH3)2SO
9
Empirical formula
Crystal habit
Crystal size [mm]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C18H23AuClN4OP
colourless plate
0.32ϫ0.10ϫ0.04
monoclinic
P21/c
10.3917(16)
14.868(2)
12.0632(17)
90
93.236(3)
90
2039.9(5)
4
C22H19AuN3PS
colourless plate
0.12ϫ0.08ϫ0.08
monoclinic
P21/n
14.6562(2)
9.1092(12)
15.613(2)
90
90.334(3)
90
2084.4(5)
4
C23H25AuN5OPS2
colourless plate
0.21ϫ0.10ϫ0.08
monoclinic
C2/c
35.493(7)
9.0951(18)
15.231(3)
90
91.46(3)
90
4977.5(17)
8
C19H17AuN5PS
colourless plate
0.12ϫ0.08ϫ0.04
triclinic
¯
P1
9.4778(12)
9.5204(12)
12.1498(15)
73.194(2)
72.239(2)
84.879(2)
999.4(2)
2
γ [°]
U [Å3]
Z
Dcalcd. [Mgm–3]
M
1.872
574.79
1112
1.865
585.40
1128
1.814
679.54
2656
1.912
575.37
552
F(000)
T [°C]
2θmax [°]
–173
54
7.436
0.4439–0.1995
12554
4437
0.0741
0.0510
0.1211
4437
237
0
1.031
2.699/–2.991
–173
54
7.247
0.5948–0.4767
12909
4521
0.0773
0.0534
0.01077
4521
253
0
1.017
2.166/–1.189
–173
52
6.169
0.6381–0.3574
37189
4876
0.0296
0.0172
0.0400
4876
312
0
1.055
1.190/–0.552
–173
54
7.558
0.7520–0.5641
8963
μ(Mo-Kα) [mm–1]
Transmission
No. of refl. measured
No. of unique refl.
Rint
4309
0.0375
0.0301
0.0718
4309
247
0
R [FϾ4σ(F)]
wR2 (F2, all refl.)
No. of refl. used
No. of parameters
No. of restraints
S
1.045
1.545/–1.574
Max./min. Δρ [eÅ–3]
= 8.8 Hz, 1 H, 5Ј-H) ppm. 31P{1H} NMR: δ = 57.49 (s, 1 P, PPh2) ppm. 13C{1H} NMR (300 MHz): δ = 148.95 (s, C-6Ј), 135.85 (s, C-
2
ppm. 13C{1H} NMR: δ = 155.56 (s, C-2), 147.72 (s, C-6), 138.43 4Ј), 132.80 (d, JP-C = 15.98 Hz, Cortho, Ph), 132.26 (s, Cpara, Ph),
1
2
3
(s, C-4), 132.94 (d, JP-C = 83.3 Hz, Cipso,PPh2), 132.86 (d, JP-C
=
=
129.47 (d, JP-C = 11.91 Hz, Cmeta, Ph), 126.71 (s, C-5Ј), 118.35 (s,
3
21.2 Hz, Cortho, Ph), 132.37 (s, Cpara, Ph), 129.61 (d, JP-C
C-3Ј) ppm. MS (ESI+): m/z (%) H]+.
=
576 (100) [M
+
15.40 Hz, Cmeta, Ph), 116.63 (s, C-5), 112.41 (s, C-3) ppm. MS
(ESI+): m/z (%) = 603 (89) [M + H]+. C21H18AuN4OPS (602.40):
calcd. C 41.87, H 3.01, N 9.30, S 5.32; found C 41.79, H 3.29, N
9.45, S 5.47.
C19H17AuN5PS (575.38): calcd. C 39.66, H 2.98, N 12.17, S 5.57;
found C 39.29, H 2.96, N 12.31, S 5.19.
Complex 10: Yield: 0.095 g, 80.3%. 1H NMR: δ = 13.30 (br. s, 1
H, NH, Htrz), 8.94 (br. s, 1 H, NH-P), 8.12 (s, 1 H, 5-H), 7.85 (m,
4 H, Ph), 7.74 (m, 1 H, 6Ј-H), 7.56 (m, 6 H, Ph), 6.49 (br. s, 2 H,
1
Complex 8: Yield: 0.097 g, 81.4%. H NMR: δ = 12.30 (br. s, 2 H,
3
NH2), 8.83 (br. s, 1 H, NH), 8.06 (m, 1 H, 6-H), 7.78 (m, 4 H, Ph-
NH2), 6.02 (d, JH-H = 5.73 Hz, 1 H, 5Ј-H) ppm. 31P{1H} NMR:
H), 7.59 (m, 8 H, Ph-H, 4-H, 6Ј-H), 7.03 (d, 3JH-H = 8.40 Hz, 1 H, δ = 63.05 (s, 1 P, PPh2) ppm. 13C{1H} NMR (300 MHz): δ = 163.09
3-H), 6.86 (m, 1 H, 5-H), 5.86 (d, 3JH-H = 7.20 Hz, 1 H, 5Ј-H) ppm.
31P{1H} NMR: δ = 57.91 (s, 1 P, PPh2) ppm. 13C{1H} NMR: δ =
162.53 (s, C-2Ј), 155.32 (s, C-2), 147.22 (s, C-6), 137.77 (s, C-4),
133.15 (d, 1JP-C = 60.30 Hz, Cipso, Ph), 132.41 (d, 2JP-C = 16.30 Hz,
(s, C-2Ј), 133.69 (d, JP-C = 62.73 Hz, Cipso, Ph), 132.92 (d, JP-C
=
=
1
2
3
16.13 Hz, Cortho, Ph), 132.11 (s, Cpara, Ph), 129.35 (d, JP-C
11.99 Hz, Cmeta, Ph), 99.89 (m, C-5Ј) ppm. MS (ESI+): m/z (%) =
592 (100) [M + H]+. C18H17AuN7PS (591.38): calcd. C 36.56, H
2.90, N 16.58, S 5.42; found C 36.60, H 3.18, N 16.36, S 5.88.
Cortho, Ph), 131.60 (s, Cpara, Ph), 128.98 (d, 3JP-C = 11.80 Hz, Cmeta
,
Ph), 115.96 (s, C-5), 111.89 (s, C-3) ppm. MS (ESI+): m/z (%) =
602 (98) [M + H]+. C21H19AuN5PS (601.41): calcd. C 41.94, H
3.18, N 11.64, S 5.33; found C 41.96, H 3.02, N 11.55, S 5.35.
Complex 11: Yield: 0.106 g, 83.9%. 1H NMR: δ = 13.30, 12.34 (br.
s, 2 H, NH, TG, Htrz), 8.85 (br. s, 1 H, NH-P), 8.17 (br. s, 1 H, 5-
H), 7.93 (m, 4 H, Ph), 7.76 (br. s, 1 H, 8Ј-H), 7.57 (m, 6 H, Ph),
5.97 (br. s, 2 H, NH2) ppm. 31P{1H} NMR: δ = 62.44 (s, 1 P, PPh2)
Synthesis of [Au(SR){Ph2PNH(Htrz)}] [R = py (9), TC (10), TG
(11)]: Et3N (0.025 g, 0.034 mL, 0.25 mmol) was added to a dichlo-
romethane solution (20 mL) of [AuCl{Ph2PNH(Htrz)}] (4; 0.102 g,
0.20 mmol) and 2-mercaptopyridine (2-HSpy; 0.022 g, 0.20 mmol)
or 2-thiocytosine (2-TC; 0.025 g, 0.20 mmol) or 6-thioguanine (6-
HTG; 0.033 g, 0.20 mmol), and the mixture was stirred for 18 h.
Complexes 9, 10 or 11 precipitated as white solids and were filtered
off.
1
ppm. 13C{1H} NMR (300 MHz): δ = 133.66 (d, JP-C = 54.59 Hz,
2
Cipso, PPh2), 133.06 (d, J = 19.83 Hz, Cortho, Ph), 132.06 (s, Cpara
,
Ph), 129.29 (d, J = 11.91 Hz, Cmeta, Ph) ppm. MS (ESI+): m/z (%)
= 632 (100) [M + H]+. C19H17AuN9PS (631.40): calcd. C 36.14, H
2.71, N 19.97, S 5.08; found C 35.94, H 2.63, N 20.16, S 5.34.
Crystal Structure Determinations: Data were recorded with a
Bruker Smart 1000 CCD (4, 5, 9) or Oxford Diffraction Xcalibur
(8) diffractometer. The crystals were mounted in inert oil on glass
1
Complex 9: Yield: 0.087 g, 76%. H NMR: δ = 13.39 (br. s, 1 H,
NH, Htrz), 9.04 (br. s, 1 H, NH-P), 8.20 (m, 2 H, 5-H, 6Ј-H), 7.80 fibres and transferred to the cold gas stream of the diffractometer.
(m, 4 H, Ph-H), 7.59 (m, 6 H, Ph-H), 7.42 (m, 2 H, 4Ј-H, 5Ј-H), Data were collected by using monochromated Mo-Kα radiation (λ
6.89 (m, 1 H, 3Ј-H) ppm. 31P{1H} NMR: δ = 63.03 (s, 1 P, PPh2)
= 0.71073 Å) in ω-scans. Absorption corrections based on multiple
1494
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 1487–1495

(Aminophosphane)gold(I) Thiolate Complexes
scans were applied by using the SADABS program.[27] The struc-
tures were solved by direct methods and refined on F2 by using
the SHELXL-97 program.[28] All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were included by using a riding
model. Further crystal data are given in Table 4. CCDC-783693
(4), -783694 (5), -783695 (8) and -783696 (9) contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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Received: November 12, 2010
Published Online: February 15, 2011
Eur. J. Inorg. Chem. 2011, 1487–1495
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1495