Synthesis, characterisation, supramolecular aggregation and biological activity of phosphine gold(I) complexes with monoanionic thiourea ligands

Article abstract of DOI:10.1016/j.ica.2005.07.046

A series of phosphine gold(I) complexes containing monoanionic thiourea ligands has been synthesised by reaction of the appropriate precursor chloro complex, Ph₃PAuCl, Cy₃PAuCl, dppf(AuCl)₂ [dppf = Fe(η⁵-C₅H₄PPh₂)₂] or dppe(AuCl)₂ (dppe = Ph₂PCH₂CH ₂PPh₂) with the thiourea and Me₃N base in methanol solution. The complexes have been fully characterised by elemental analysis, NMR spectrometry, electrospray mass spectrometry, and in several cases, by single-crystal X-ray diffraction studies. The crystallographic studies show that the ligands coordinate as a thiolate in each case with systematic variations in geometric parameters being readily ascribed to the influence of the N-bound substituents. In four of the structures, discernable supramolecular aggregation patterns are evident, leading to loosely associated dimers or chain motifs, the latter mediated by either Au?S, N-H?N or C-H?O interactions. Cytotoxicity data, against the P388 leukemia cell line, and anti-microbial data are also reported.

Full text of DOI:10.1016/j.ica.2005.07.046

Inorganica Chimica Acta 359 (2006) 204–214
www.elsevier.com/locate/ica
Synthesis, characterisation, supramolecular aggregation and
biological activity of phosphine gold(I) complexes with
monoanionic thiourea ligands
a,
a
b, ,1
*
William Henderson *, Brian K. Nicholson , Edward R.T. Tiekink
a
Department of Chemistry, University of Waikato, Private Bag 3105, Hamilton, New Zealand
b
School of Science, Griffith University, Nathan 4111, Qld, Australia
Received 11 June 2005; accepted 5 July 2005
Available online 23 November 2005
Abstract
A series of phosphine gold(I) complexes containing monoanionic thiourea ligands has been synthesised by reaction of the appropriate
precursor chloro complex, Ph3PAuCl, Cy3PAuCl, dppf(AuCl)2 [dppf = Fe(g5-C5H4PPh2)2] or dppe(AuCl)2 (dppe = Ph2PCH2CH2PPh2)
with the thiourea and Me3N base in methanol solution. The complexes have been fully characterised by elemental analysis, NMR spec-
trometry, electrospray mass spectrometry, and in several cases, by single-crystal X-ray diffraction studies. The crystallographic studies
show that the ligands coordinate as a thiolate in each case with systematic variations in geometric parameters being readily ascribed
to the influence of the N-bound substituents. In four of the structures, discernable supramolecular aggregation patterns are evident, lead-
ing to loosely associated dimers or chain motifs, the latter mediated by either Auꢀ ꢀ ꢀS, N–Hꢀ ꢀ ꢀN or C–Hꢀ ꢀ ꢀO interactions. Cytotoxicity
data, against the P388 leukemia cell line, and anti-microbial data are also reported.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Gold; Phosphine complexes; Thiourea complexes; Cytotoxicity; Anti-microbial activity; Supramolecular aggregation
1. Introduction
complexes also suggest potential applications as sensors,
optical materials, etc. [6]. Finally, there is interest in the
solid-state structures of such compounds through the
formation of Auꢀ ꢀ ꢀAu aurophilic and other interactions
[7–11].
Phosphine gold(I) thiolate complexes of the type
R3PAuSR0 have attracted continued interest in recent
years, as a result of their varied and interesting properties.
Many compounds of this type are biologically active,
indeed the only oral gold–thiolate drug used in the clinic
today for treatment of difficult cases of rheumatoid arthri-
tis, Auranofin, is a phosphine gold(I) thiolate complex. A
range of phosphine gold thiolates has also been shown to
have potential as anti-cancer agents [1–5]. The photophys-
ical properties (luminescence) of phosphine gold thiolate
We are particularly interested in the chemistry of thio-
urea derivatives; these can behave as thiolate-type ligands,
since a substituted thiourea bearing at least one hydrogen,
R1R2NC(=S)NHR3 can exist in a tautomeric thiolate
form, i.e., R1R2C(SH)@NR3. Recently, we have reported
studies on complexes of platinum(II) [12], rhodium(III)
and ruthenium(II) [13] containing deprotonated and mono-
anionic thiourea ligands. The most attractive feature of
such substituted thioureas is their ease of synthesis, being
readily obtained from the amine R1R2NH and isothiocya-
nate R3NCS, allowing the synthesis of a diverse range of
derivatives, with designer properties obtained by varying
the substituents R1, R2 and R3. Gold(I) complexes of true
*
Corresponding authors. Tel.: +64 7 856 2889; fax: +64 7 838 4219.
E-mail addresses: w.henderson@waikato.ac.nz (W. Henderson),
Edward.Tiekink@utsa.edu (E.R.T. Tiekink).
1
Present address: Department of Chemistry, The University of Texas at
San Antonio, Texas 78249-0698, USA.
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.07.046

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
205
trisubstituted thioureas do not appear to have been
described to date, although complexes containing deproto-
nated heterocyclic derivatives that contain the N–C(S)–N
grouping, such as 2-thiouracil and 2-mercaptopyrimidine
and related compounds, are well known [14–20], and
gold(I) phosphine complexes of ligands derived from the
closely related carbonimidothiolates (thiocarbamates)
PhNHC(S)OR have also been described [21]. In this contri-
bution, we describe the syntheses of a range of phosphine
gold(I) complexes of monoanionic thioureas, together with
their structural characterisation and biological activity in a
P388 murine leukemia screen as well as anti-microbial
activity.
ion [Au(PPh3)2]+ (m/z 721) as the base peak in the spec-
trum, and only very weak [M+H]+ ions. However, the
PCy3 complexes did not give the analogous [Au(PCy3)2]+
ion. The high intensity of [Au(PPh3)2]+ arises because it
is cationic, and therefore even though a solution may only
contain a trace of this species, it has high ionisation effi-
ciency relative to a neutral thiourea complex, and hence
dominates the spectrum. Significantly improved spectral
quality was obtained by using a slightly lower cone voltage
(10 V), and by adding a drop of dilute aqueous ammonium
acetate solution to the phosphine gold(I) thiourea complex
solution. This acts as a mild proton donor, encouraging the
formation of [M+H]+ ions. Using this ionisation method,
all of the triphenylphosphine and tricyclohexylphosphine
complexes gave strong [M+H]+ ions. For some of the
PPh3 complexes, strong [Au(PPh3)2]+ ions were still seen,
though for most complexes these were quite weak (ca.
10% relative intensity). The majority of the mononuclear
phosphine gold complexes also gave the cation
[(Ph3PAu)2(monoanionic thiourea)]+. This type of species
presumably has a structure in which both Ph3PAu+ moie-
ties are bound to the thiourea sulfur atom, in comparison
with the range of analogous thiolate species of this type
which are known [22–27]. The observation of such
[M+AuL]+ ions in the spectra of gold(I) thiolate complexes
has been observed previously [18,28]. The cyanothiourea
complex 8 showed, in addition to the ions described above,
a relatively low intensity [2M+H]+ ion (m/z 1164) not
observed for the other complexes, presumably due to the
greater hydrogen bonding potential in this complex.
The ESI mass spectra of the dinuclear dppe and dppf
complexes 11 and 13 are rather different to those of the
mononuclear complexes. Thus, for 11 the base peak was
the [M+2H]2+ ion at m/z 696, where protonation presum-
ably occurs at both thiourea ligands. The dicationic nature
was confirmed by the 0.5 m/z separation of adjacent peaks
in the isotope pattern, the signature of a dication. A second
ion with significant intensity (60%) was the ion
[dppfAu2{SC(NPh)N(CH2CH)2O}]+ at m/z 1169, formed
by loss of a thiourea from the parent [M+H]+ cation
(equivalent to loss of a thiourea monoanion from the par-
ent neutral molecule). It is feasible that this ion has the
same structure as the species [(Ph3PAu)2SR]+ formed in
low intensity for the mononuclear complexes. On increas-
ing the cone voltage to 40 V, a new species, identified
as [dppfAu2{SC(NPh)N(CH2CH2)2O}H]2+ at m/z 585
appeared, formed by loss of a thiourea anion, and proton-
ation. Analogous ions were observed for the dppe complex
12. In both cases, the [M+H]+ and [Au(diphosphine)x]+
(x = 1,2) ions were not observed.
2. Results and discussion
2.1. Synthesis and spectroscopic characterisation of
phosphine gold(I) thiourea complexes
The reactions of the gold(I) phosphine complexes
Ph3PAuCl, Cy3PAuCl (Cy = cyclohexyl) and the bisphos-
phine analogues dppf(AuCl)2 [dppf = Fe(g5-C5H4PPh2)2]
and dppe(AuCl)2 (dppe = Ph2PCH2CH2PPh2) with a range
of trisubstituted thioureas R1R2NC(S)NHR3 in methanol
solution, in the presence of excess trimethylamine base
gave a series of phosphine gold(I) complexes containing
monoanionic thiourea ligands. The complexes were iso-
lated directly from the reaction mixtures generally in
high yields and purities. In a similar manner, the reaction
of the commercially available monoanionic thiourea salt
Na[MeNHC(S)NCN] with Ph3PAuCl and dppe(AuCl)2
(without added base) gave the analogous disubstituted
complexes 8 and 13 in good yield. The complexes synthes-
ised by this general method are shown in Scheme 1, and
contain a range of simple aliphatic, chiral, chromophoric
and functional substituents, illustrating the simplicity of
this approach in changing the properties of the complex.
The complexes have the expected properties for this
class of complex, being stable, and soluble in chlorinated
solvents such as dichloromethane, from which they can
be recrystallised. They show a single resonance in their
31P–{1H} NMR spectra, at ca. d 38 for the PPh3 com-
plexes, and d 56 for the PCy3 complexes. The dinuclear
1
complexes also show single 31P resonances. The H NMR
spectra were also in accord with the proposed structures.
The IR spectra of the complexes show a strong C@N
stretch, generally at about 1560 cmꢁ1. The cyanothiourea
derivatives 8 and 13 showed a lower C@N stretching fre-
quency, at 1534 cmꢁ1 in 8 and 1539 cmꢁ1 in 13, presumably
due to conjugation with the cyano functionality, which
itself appeared at 2159 and 2151 cmꢁ1 in 8 and 13,
respectively.
2.2. Structural studies
Electrospray mass spectrometry (ESI-MS) has been suc-
cessfully used to characterise the new phosphine gold(I)
thiourea complexes. However, initial studies carried out
in methanol solution using a fairly low cone voltage
(20 V) gave, for the triphenylphosphine complexes, the
Single crystals suitable for X-ray crystallography were
obtained for mononuclear complexes 1, 8 and 10, and for
dinuclear species 11 and 12. Selected geometric parameters
for all structures are compiled in Table 1 and the molecular

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W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
R3
N
L
Au
S
C
N
R2
Ph
C
R1
N
Complex
L
R1R2
R3
1
2
PPh3
PPh3
PPh3
PPh3
PPh3
PPh3
PPh3
PPh3
PCy3
PCy3
(CH2CH2)2O
(CH2CH2)2S
(CH2Ph)2
Me2
Ph
PPh2
PPh2
Au
S
NR1R2
Ph
Fe
3
Ph
NR1R2
Au
S
4
Ph
C
5
Me2
p-C6H4NO2
N
6
(CH2)4
Ph
Ph
CN
Ph
Ph
Ph
7
(CH2)5
11, R1R2 = (CH2CH2)2O
8
HMe
9
Me2
10
(CH2CH2)2O
R3
N
Me2N
C
N
N
PPh2
Au
S
NR1R2
N
NR1R2
C
PPh2
Au
S
PPh3
Au
S
C
N
N
O
R3
14
Complex
12
R1R2
R3
(CH2CH2)2O
HMe
Ph
CN
13
Scheme 1. Phosphinegold(I) thiourea complexes described in this work.
structures are illustrated in Figs. 1–5. The molecular struc-
ture of 1 features a linearly coordinated gold centre defined
by S and P donor atoms; this coordination motif is
repeated in all of the remaining structures to be described
herein. An examination of the bond distances associated
with the deprotonated thiourea ligand reveals a number
of interesting observations. First, and foremost, these indi-
cate that this ligand is coordinating as a thiolate ligand.
There is some evidence for some delocalization of p-elec-
tron density over the thiolate ligand but this is restricted
as there are significant twists in the bonds describing the
Au–thiolate residue, as indicated by the values of the rele-
vant torsion angles collected in Table 1, and also within the
thiolate ligand itself. Thus, while the formally S–C1@N2–
C11 residue is essentially planar, this is not extended to
the N1-containing portion of the thiolate. In keeping with
this, the C1@N2 bond distance is significantly shorter than
the C1–N1 bond distance consistent with significant local-
ization of p-electron density in the C1@N2 bond. In terms
of angles, the S1–C1–N2 angle is at least 10ꢁ greater than

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
207
Table 1
Selected bond distances (A) and angles (ꢁ) for 1, 8, 10, 11 and 12 Æ CH2Cl2
a
a
˚
Parameter
1
8
10
11
12 Æ CH2Cl2
Au–S1
Au–P1
S1–C1
C1–N1
C1–N2
2.3115(7)
2.2628(6)
1.772(3)
1.383(3)
1.287(3)
2.3075(15)
2.2674(15)
1.746(7)
1.336(8)
1.331(9)
2.3044(4)
2.2701(4)
1.7765(18)
1.384(2)
2.3112(12), 2.3009(12)
2.2546(11), 2.2561(11)
1.776(4), 1.782(4)
1.361(5), 1.374(5)
1.282(5), 1.270(5)
2.3066(14), 2.2782(15)
2.2638(13), 2.2530(13)
1.772(5), 1.768(7)
1.386(7), 1.365(8)
1.276(7), 1.272(9)
1.282(2)
S1–Au–P1
Au–S1–C1
S1–C1–N1
S1–C1–N2
N1–C1–N2
169.29(2)
172.83(6)
167.340(16)
110.21(6)
113.41(13)
128.53(14)
117.95(16)
170.43(4), 169.32(4)
107.39(16), 106.85(15)
114.9(3), 113.7(3)
127.3(4), 127.6(4)
117.8(4), 118.5(4)
166.67(5), 169.91(5)
108.82(18), 108.9(2)
114.1(4), 112.8(5)
127.7(4), 128.3(5)
118.2(5), 119.0(6)
109.92(9)
114.21(18)
128.4(2)
108.7(2)
114.4(5)
128.1(5)
117.4(6)
117.3(2)
Au/S1/C1/N1
Au/S1/C1/N2
S1/C1/N1/C2
S1/C1/N2/C11
a
161.00(17)
ꢁ21.8(3)
ꢁ40.3(3)
ꢁ12.7(4)
ꢁ146.1(4)
36.5(6)
ꢁ151.94(11)
31.99(19)
38.3(2)
152.4(3), 143.9(3)
ꢁ26.0(4), ꢁ40.6(5)
ꢁ1.2(8), ꢁ31.9(6)
ꢁ9.3(7), ꢁ5.9(7)
148.3(4), 175.7(5)
ꢁ28.2(6), ꢁ2.8(8)
26.2(7), ꢁ7.9(12)
ꢁ5.3(9), ꢁ9.5(12)
ꢁ179.9(5)
ꢁ4.0(9)
9.7(3)
Two independent molecules comprise the asymmetric unit. Parameters for the second independent molecule follow those listed for the first.
Fig. 1. Molecular structure of Ph3PAuSC(@NPh)N(CH2CH2)2O (1) showing the atomic numbering scheme.
Fig. 2. Molecular structure of Ph3PAuSC(@NCN)N(H)Me (8) showing
Fig. 3. Molecular structure of Cy3PAuSC(@NPh)N(CH2CH2)2O (10)
the atomic numbering scheme.
showing the atomic numbering scheme.
Fig. 1, the thiolate ligand is orientated so as to place the
aromatic ring in proximity to the Au atom. The distance
between the Au atom and the centroid of the aromatic ring
the other angles subtended at the C1 atom, with the nar-
rowest of these being the S1–C1–N1 angle, i.e., opposite
the formal N@C double bond. As can be seen from

208
W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
Fig. 6. Supramolecular aggregation leading to dimer formation via
Auꢀ ꢀ ꢀS interactions in the structure of Ph3PAuSC(@NPh)N(CH2CH2)2O
(1); H atoms have been omitted for clarity.
having the identical N1- and N2-bound groups as in 1,
are essentially in agreement with those of 1. Here, the
Auꢀ ꢀ ꢀring centroid separation involving the C11–C16 ring
Fig. 4. Molecular structure of dppf[AuSC(@NPh)N(CH2CH2)2O]2 (11)
showing the atomic numbering scheme.
˚
is 3.58 A, suggesting a weaker interaction compared to that
˚
is 3.4449(18) A. However, it is noted that the Auꢀ ꢀ ꢀC sep-
in 1, an observation ascribed to the greater steric bulk of
the cyclohexylphosphine ligand. Thus, whereas the longest
Auꢀ ꢀ ꢀC separation involving the aromatic ring in 1 was
arations are far from symmetric as they span a range
˚
3.160(3)–4.204(5) A, possibly reflecting the constraints of
˚
the S1–C1–N2 angle. The molecular structure of 8 is in
essential agreement with that just described. It is notewor-
thy that the disparity in the C–N1, N2 distances apparent
in 1 no longer seem to pertain in 8. Also, noteworthy is
the observation that the C–S distance is significantly
shorter in 8 compared to 1. These variations coupled with
the planarity within the thiolate ligand, Table 1, suggests
significantly more delocalization over the central chromo-
phore of the thiolate ligand, a feature that can be ascribed
to the electron-withdrawing nature of the cyanide group.
Again, the N2-bound organic residue is orientated so as
to be close to the Au atom, consistent with a Auꢀ ꢀ ꢀp inter-
4.204(5) A, for Auꢀ ꢀ ꢀC14, and the longest comparable sep-
˚
aration in 10 was 4.333(2) A. Similar coordination geome-
tries are found in the dinuclear gold compounds 11 and 12.
Two independent ‘‘half’’ molecules comprise the asym-
metric unit in 11. Each of the molecules is situated on a
crystallographic centre of inversion, i.e., the Fe atom is sit-
ꢀ
uated on a site of symmetry, 1. Only one molecule is illus-
trated in Fig. 4 as the second independent molecule is
essentially identical, at least in terms of its molecular geom-
etry. The major difference in the geometric parameters
describing the two molecules is found in the planarity of
the thiolate ligands, i.e., the thiolate ligand for molecule
a is essentially planar compared to a twisted conformation
in molecule b. The distance between the Au atom and the
˚
˚
action; Auꢀ ꢀ ꢀC11 is 3.166(6) A and Auꢀ ꢀ ꢀN3 is 3.331(6) A.
The geometric features of the molecular structure of 10,
Fig. 5. Molecular structure of dppe[AuSC(@NPh)N(CH2CH2)2O]2 (12) showing the atomic numbering scheme.

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
209
˚
˚
C11–C16 ring centroid for molecule a is 3.3482(18) A; this
of 2.995(8) A, and an angle subtended at H of 147ꢁ, for
symmetry operation ii: ꢁ1/2 ꢁ x, ꢁ1/2 + y, 1/2 ꢁ z. In
10, the molecules pack via hydrophobic interactions, with
close association, as found in 1, most likely precluded
owing to the steric bulk of the cyclohexylphosphine
ligands. In 11, the independent molecules are connected
via C–Hꢀ ꢀ ꢀO interactions as to form a chain arrangement
as shown in Fig. 8. Thus, the H12a atoms of molecule
a are connected to O1b atoms of molecule b with
˚
is significantly longer at 3.504(2) A for the molecule b. The
conformation of each of the independent molecules, as a
result of the crystallographic symmetry, is trans. Two inde-
pendent molecules are also found in the crystal structure of
12. In this case, two molecules, each disposed about a crys-
tallographic centre of inversion as well as a dichlorometh-
ane molecule of solvation comprise the asymmetric unit so
that the ratio of dinuclear complex to solvent is 1:1; only
one independent molecule is shown in Fig. 5. In terms of
molecular geometry, the major conformational difference
between the independent molecules in 12, as for 11, is
found in the planarity of the thiolate ligands, see Table 1.
The distances between the Au atoms and the respective ring
˚
centroids of the C11–C16 rings are 3.281(3) and 3.286(5) A,
respectively. The bond distances defining the thiolate mol-
ecules in dinuclear 11 and 12 resemble those found in
mononuclear 1 and 10, i.e., indicating localization of p-
electron density in the S–C–N2–C portion of the ligand.
Recognisable supramolecular association patterns are
discernable in several of the crystal structures, just
described. In the crystal structure of 1, molecules associate
via the formation of [Auꢀ ꢀ ꢀS]2 rectangles so that Auꢀ ꢀ ꢀS1i is
˚
3.4211(7) A for symmetry operation i: ꢁx, ꢁy, ꢁz; this
association is represented in Fig. 6. In 8, rather than the
formation of the expected [S–C–N–H]2 synthon, molecules
associate via N–Hꢀ ꢀ ꢀNC interactions so as to form a chain
motif, as illustrated in Fig. 7. The parameters associated
ii
ii
˚
with this interaction are N1–Hꢀ ꢀ ꢀN3 of 2.22 A, N1ꢀ ꢀ ꢀN3
Fig. 7. Supramolecular aggregation leading to a chain motif mediated by
N–Hꢀ ꢀ ꢀN interactions in the structure of Ph3PAuSC(@NCN)N(H)Me (8);
non-participating H atoms have been omitted for clarity.
Fig. 8. Supramolecular aggregation leading to a chain motif mediated by
C–Hꢀ ꢀ ꢀO interactions in the structure of dppf[AuSC(@NPh)N(CH2-
CH2)2O]2 (11); non-participating H atoms have been omitted for clarity.

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W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
iii
C12a–Hꢀ ꢀ ꢀO1biii of 2.45 A, C12aꢀ ꢀ ꢀO1b of 3.370(5) A
and an angle of 165ꢁ subtended at H for symmetry opera-
tion iii: ꢁx, ꢁ1 ꢁ y, ꢁz. Finally, in the crystal structure of
12, two distinct supramolecular motifs are observed. A
chain motif, mediated via weak [Auꢀ ꢀ ꢀS]2 interactions, akin
to those observed in 1 are found. The magnitude of the
individual Auꢀ ꢀ ꢀS interactions is somewhat longer than
2.3. Biological activity of phosphinegold(I) thiourea
complexes
˚
˚
Because many gold(I) thiolate complexes have been
found to show potential and actual anti-cancer activity
[1,2], a selection of the phosphine gold(I) thiourea com-
plexes described in this paper has been screened for activity
against P388 murine leukemia cells. The antimicrobial
activity of the same complexes was also assayed, against
three bacteria and three fungi. Data are summarised in
Table 2. The complexes generally have moderate to low
cytotoxicity, though the compounds with greatest activity
appear to be those with small, hydrophobic alkyl substitu-
ents in the R1 and R2 positions, Scheme 1. All complexes
displayed very low or no antimicrobial activity, the most
activity being obtained for the tricyclohexylphosphine
complex 9.
that observed in 1, i.e., Auꢀ ꢀ ꢀS1iv is 3.8771(16) A for sym-
˚
metry operation iv: ꢁx, ꢁ1 ꢁ y, 1 ꢁ z, nevertheless, a dis-
cernable supramolecular motif, i.e., a linear chain, is
apparent as represented in Fig. 9(a). Similar supramolecu-
lar aggregation is not observed for the second independent
molecule in 12 as the solvent CH2Cl2 molecules are associ-
ated with the S atoms, thereby blocking these off for anal-
ogous [Auꢀ ꢀ ꢀS]2 association as found between molecules of
v
˚
a. Thus, the C100–Hꢀ ꢀ ꢀS1b separation is 2.82 A, C100–
v
˚
Hꢀ ꢀ ꢀS1b is 3.725(19) A and the angle at H is 153ꢁ for sym-
metry operation v: 1 ꢁ x, 1 ꢁ y, 1 ꢁ z. Despite this avenue
for aggregation being precluded, i.e., Auꢀ ꢀ ꢀS interactions, a
chain motif is still apparent, akin to that observed in 11
and as shown in Fig. 9(b). Thus, molecules of b form a
3. Experimental
3.1. General
chain via the following interactions: C512–Hꢀ ꢀ ꢀO1bvi is
vi
2.58 A, C512 ꢀ ꢀ ꢀO1b is 3.451(10) A with an angle of
155ꢁ subtended at H for symmetry operation vi: ꢁ1 ꢁ x,
1 ꢁ y, ꢁz.
1H, 13C–{1H} and 31P–{1H} NMR spectra were
recorded on a Bruker AC300P spectrometer in CDCl3
unless otherwise stated. Elemental analyses were obtained
˚
˚
Fig. 9. Supramolecular aggregation leading to chain motifs in the structure of dppe[AuSC(@NPh)N(CH2CH2)2O]2 (12), (a) via Auꢀ ꢀ ꢀS interactions
between molecules of a, and (b) via C–Hꢀ ꢀ ꢀO interactions between molecules of b; non-participating H atoms and solvent CH2Cl2 molecules have been
omitted for clarity.

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
211
Table 2
3.2. Synthesis of phosphinegold(I) monoanionic thiourea
complexes – general method
In vitro cytotoxicity and antimicrobial/antifungal activity data for the
phosphine gold(I) thiourea complexes
Complex
IC50(lM)a
Antimicrobial activityb,c
The precursor phosphinegold chloride complex
[Ph3PAuCl, Cy3PAuCl, dppe(AuCl)2 or dppf(AuCl)2] and
the thiourea (1 mole equivalent per gold) were suspended
in methanol (20–25 mL), at which time the starting materi-
als often dissolved to give a clear solution. The mixture was
warmed to ca. 60 ꢁC, aqueous trimethylamine (2–3 mL,
excess) added, and the mixture heated to reflux for a few
minutes. Water (10–30 mL) was then added, the mixture
cooled to room temperature, and the solid product filtered
off, washed with water (2 · 10mL) and dried under
vacuum.
Ec
Bs
Pa
Ca
Tm
Cr
1
1
2
4.2
1.5
5.8
2
2
1
3
2
2
3
1
1
3
1
1
1
1
3
4
1.6
1
1
1
3
1
3
2
2
4
6
<1.5
<1.4
1.8
6.0
5.3
9.9
31.1
42.0
7
9
1
3
2
10
11
12
13
14
a
The following complexes were synthesised by this
method.
The concentration of sample in lM required to reduce the cell growth
of the P388 leukemia cell line (ATCC CCL 46) by 50%.
b
3.2.1. Ph3PAuSC(@NPh)N(CH2CH2)2O (1)
Inhibition zone as excess radius (mm) from a 6 mm (diameter) disc
containing 2 lg of sample. No entry indicates lack of activity.
Ph3PAuCl
(400 mg,
0.809 mmol)
with
PhN-
c
Ec, Escherichia coli; Bs, Bacillus subtilis; Pa, Pseudomonas aeruginosa;
HC(S)N(CH2CH2)2O (180 mg, 0.811 mmol) gave white
microcrystals of 1 (480 mg, 87%). M.p. 168–178 ꢁC. Anal.
Calc. for C29H28N2AuOPS: C, 51.2; H, 4.15; N, 4.1.
Found: C, 51.3; H, 4.1; N, 4.1%. 31P–{1H} NMR, d 38.4
Ca, Candida albicans; Tm, Trichophyton mentagrophytes; and Cr, Clado-
sporium resinae.
1
(s). H NMR, d 7.54–6.40 (m, Ph), 3.87 (m, CH2O), 3.37
(m, CH2N). ESI-MS, m/z 681 [M+H]+ (100%), 721
[Au(PPh3)2]+ (10%), 1139 [(Ph3PAu)2SC(NPh)N(CH2-
CH2)2O]+ (5%). IR mmax 1556 cmꢁ1 (s).
by the Campbell Microanalytical Laboratory at the Uni-
versity of Otago, Dunedin, New Zealand.
ESI mass spectra were recorded on a VG Platform II
instrument in positive-ion mode, using methanol as the
mobile phase. Several drops of a dilute ammonium acetate
solution (concentration ca. 1 g Lꢁ1) were added to the ana-
lyte solution to aid in protonation. Spectra were recorded
at a low cone voltage (10 V) to minimise fragmentation.
Infrared spectra were recorded as KBr disks on a Bio-
Rad FTS40 spectrophotometer. Melting points were deter-
mined on a Reichert-Jung hotstage apparatus and are
uncorrected.
All reactions were carried out in laboratory reagent
grade methanol without further purification. Dichloro-
methane and diethyl ether were purified by distillation
from calcium hydride and sodium-benzophenone ketyl,
respectively.
The complexes Ph3PAuCl [29], Cy3PAuCl [30],
dppf(AuCl)2 [31], and dppe(AuCl)2 [32] were prepared by
the literature methods. The thioureas PhNHC(S)-
N(CH2CH2)2O, PhNHC(S)N(CH2Ph)2, PhNHC(S)NMe2,
and Me2NC6H4N@NC6H4NHC(S)N(CH2CH2)2O were
prepared from the appropriate isothiocyanate and amine,
as described previously [12]. The sodium salt
Na[MeNHC(S)NCN] (Aldrich) and aqueous trimethyla-
mine (BDH, 25–30% w/v) were used as supplied.
PhNHC(S)N(CH2CH2)2S, PhNHC(S)N(CH2)4, PhNHC-
(S)N(CH2)5, and p-O2NC6H4NHC(S)NMe2 were prepared
by reaction of an ether solution of PhNCS with, respec-
tively, thiomorpholine (Aldrich), pyrrolidine (BDH), piper-
idine (BDH) or p-nitroaniline (BDH). Melting points:
PhNHC(S)N(CH2CH2)2S 159–162 ꢁC, PhNHC(S)N(CH2)4
119–120 ꢁC, PhNHC(S)N(CH2)5 97–98 ꢁC.
3.2.2. Ph3PAuSC(@NPh)N(CH2CH2)2S (2)
Ph3PAuCl
(300 mg,
0.607 mmol)
with
PhN-
HC(S)N(CH2CH2)2S (145 mg, 0.609 mmol) gave a white
powder of 2 (360 mg, 85%). M.p. 148–152 ꢁC. Anal. Calc.
for C29H28N2AuPS2: C, 50.0; H, 4.05; N, 4.0. Found: C,
50.0; H, 3.9; N, 4.01%. 31P–{1H} NMR, d 38.4 (s). H
1
NMR, d 7.55–6.40 (m, Ph), 4.24 (m, CH2), 2.72 (m,
CH2). ESI-MS, m/z 697 [M+H]+ (100%), 721 [Au(PPh3)2]+
(15%), 1155 [(Ph3PAu)2SC(NPh)N(CH2CH2)2S]+ (5%). IR
mmax 1560 cmꢁ1 (s).
3.2.3. Ph3PAuSC(@NPh)N(CH2Ph)2 (3)
Ph3PAuCl (300 mg, 0.607 mmol) with PhNH-
C(S)N(CH2Ph)2 (201 mg, 0.605 mmol) gave white micro-
crystals of 3 (444 mg, 93%). M.p. 54–58 ꢁC. Anal. Calc.
for C39H34N2AuPS: C, 59.2; H, 4.3; N, 3.5. Found: C,
59.3; H, 4.2; N, 3.7%. 31P–{1H} NMR, d 38.2 (s). 1H
NMR, d 7.53–6.43 (m, Ph), 4.99 (s, CH2). ESI-MS, m/z
721 [Au(PPh3)2]+ (10%), 791 [M+H]+ (100%), 1249
[(Ph3PAu)2SC(NPh)N(CH2Ph)2]+
1560 cmꢁ1 (s).
(2%).
IR
mmax
3.2.4. Ph3PAuSC(@NPh)NMe2 (4)
Ph3PAuCl (200 mg, 0.404 mmol) with PhNHC(S)NMe2
(73 mg, 0.406 mmol) gave white microcrystals of 4 (220 mg,
85%). M.p. 76–79 ꢁC. Anal. Calc. for C27H26N2AuPS: C,
50.8; H, 4.1; N, 4.4. Found: C, 49.9; H, 4.0; N, 4.3%.
31P–{1H} NMR, d 38.4 (s). 1H NMR, d 7.51–6.38 (m,
Ph), 3.29 (s, Me). ESI-MS, m/z 639 [M+H]+ (100%), 721

212
W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
[Au(PPh3)2]+ (5%), 1097 [(Ph3PAu)2SC(NPh)NMe2]+
3.2.10. dppf[AuSC(@NPh)N(CH2CH2)2O]2 (11)
(5%). IR mmax 1560 cmꢁ1 (s).
The complex dppf(AuCl)2 (200 mg, 0.196 mmol) with
PhNHC(S)N(CH2CH2)2O (87 mg, 0.392 mmol) gave an
orange powder of 11 (220 mg, 81%). M.p. 197–202 ꢁC.
Anal. Calc. for C56H54N4Au2FeO2P2S2: C, 48.35; H, 3.9;
N, 4.0. Found: C, 48.3; H, 3.8; N, 4.0%. 31P–{1H}
NMR, d 32.7 (s). 1H NMR, d 7.50–6.42 (m, Ph), 4.55
(s, FeC5H4), 4.04 (s, FeC5H4), 3.87 (s, CH2O), 3.77 (s,
CH2N). ESI-MS, m/z 696 [M+2H]2+ (100%), 1169 [dpp-
3.2.5. Ph3PAuSC(@NC6H4NO2-p)NMe2 (5)
Ph3PAuCl (200 mg, 0.404 mmol) with p-O2NC6-
H4NHC(S)NMe2 (91 mg, 0.404 mmol) gave bright-yellow
microcrystals of 5 (230 mg, 83%). M.p. 144–146 ꢁC. Anal.
Calc. for C27H25N3AuO2PS: C, 47.4; H, 3.7; N, 6.15.
Found: C, 47.5; H, 3.6; N, 6.2%. 31P–{1H} NMR, d 38.1
1
(s). H NMR, d 7.64–6.70 (m, Ph), 3.31 (s, NMe2). ESI-
fAu2{SC(NPh)N(CH2CH2)2O}]+
1567 cmꢁ1 (s).
(60%).
IR
mmax
MS, m/z 684 [M+H]+ (100%), 721 [Au(PPh3)2]+ (18%),
1142 [(Ph3PAu)2SC(NC6H4NO2-p)NMe2]+ (5%). IR mmax
1560 cmꢁ1 (s).
3.2.11. dppe[AuSC(@NPh)N(CH2CH2)2O]2 (12)
The complex dppe(AuCl)2 (200 mg, 0.232 mmol) with
PhNHC(S)N(CH2CH2)2O (103 mg, 0.464 mmol) gave a
white powder of 12 (230 mg, 80%). M.p. 160–166 ꢁC. Anal.
Calc. for C48H50N4Au2O2P2S2: C, 46.7; H, 4.1; N, 4.5.
Found: C, 46.2; H, 3.9; N, 4.4%. 31P–{1H} NMR, d 36.3
3.2.6. Ph3PAuSC(@NPh)N(CH2)4 (6)
Ph3PAuCl (150 mg, 0.303 mmol) with PhNH-
C(S)N(CH2)4 (63 mg, 0.306 mmol) gave white microcrys-
tals of 6 (190 mg, 95%). M.p. 168–172 ꢁC. Anal. Calc. for
C29H28N2AuPS: C, 52.4; H, 4.25; N, 4.2. Found: C, 52.4
1
(s). H NMR, d 7.57–6.36 (m, Ph), 3.86 (m, CH2O), 3.78
H, 4.3; N, 4.1%. 31P–{1H} NMR, d 38.5 (s). H NMR, d
(m, CH2N), 2.26 (s, CH2). ESI-MS, m/z 618 [M+2H]2+
(100%), 1013 [dppeAu2{SC(NPh)N(CH2CH2)2O}]+ (60%).
IR mmax 1559 cmꢁ1 (s).
1
3
7.51–6.33 (m, Ph), 3.76 [t, NCH2, J(HH) 6.7], 1.94 (m,
CH2). ESI-MS, m/z 665 [M+H]+ (100%), 721 [Au(PPh3)2]+
(4%), 1123 [(Ph3PAu)2SC(NPh)N(CH2)4]+ (4%). IR mmax
1540 cmꢁ1 (s).
3.2.12. Ph3PAuSC(@NC6H4N@NC6H4NMe2)
N(CH2CH2)2O (14)
Ph3PAuCl (150 mg, 0.303 mmol) with Me2NC6H4N@
NC6H4NHC(S)N(CH2CH2)2O (114 mg, 0.312 mmol) gave
bright-orange microcrystals of 14 (230 mg, 92%). M.p.
196–200 ꢁC. Anal. Calc. for C37H37N5AuOPS: C, 53.7; H,
4.5; N, 8.5. Found: C, 53.8; H, 4.6; N, 8.5%. 31P–{1H}
3.2.7. Ph3PAuSC(@NPh)N(CH2)5 (7)
Ph3PAuCl (150 mg, 0.303 mmol) with PhNH-
C(S)N(CH2)5 (67 mg, 0.305 mmol) gave a white powder
of 7 (183 mg, 89%). M.p. 132–135 ꢁC. Anal. Calc. for
C30H30N2AuPS: C, 53.1; H, 4.5; N, 4.1. Found: C, 53.1;
1
H, 4.4; N, 4.1%. 31P–{1H} NMR, d 38.4 (s). H NMR, d
1
NMR, d 38.1 (s). H NMR, d 7.72–6.75 (m, Ph), 3.91 (m,
CH2O), 3.79 (m, CH2N), 3.09 (s, NMe2). ESI-MS, m/z
721 [Au(PPh3)2]+ (65%), 828 [M+H]+ (100%). IR mmax
1540 cmꢁ1 (s).
7.52–6.41 (m, Ph), 3.86 (s, br), 1.65 (s, br). ESI-MS, m/z
679 [M+H]+ (100%), 721 [Au(PPh3)2]+ (8%), 1137
[(Ph3PAu)2SC(NPh)N(CH2)5]+ (5%). IR mmax 1558 cmꢁ1
(s).
3.3. Synthesis of Ph3PAuSC(@NCN)NHMe (8)
3.2.8. Cy3PAuSC(@NPh)NMe2 (9)
A suspension of Ph3PAuCl (200 mg, 0.404 mmol) and
Na[MeNHC(S)NCN] (60 mg, 0.438 mmol) in methanol
(15 mL) was stirred at room temperature for 48 h. To the
white suspension was added water (20 mL), and the white
solid filtered off, washed with water (10 mL) and petroleum
spirits (10 mL) and dried under vacuum to give 8 (200 mg,
87%). M.p. 158–160 ꢁC. Anal. Calc. for C21H19N3AuPS: C,
44.0; H, 3.3; N, 7.3. Found: C, 44.0; H, 3.2; N, 7.4%. 31P–
{1H} NMR, d 37.3 (s). 1H NMR, d 7.65–7.45 (m, Ph), 5.97
(s, br, NH), 2.91 [d, Me, J(HH) 4.7]. ESI-MS, m/z 574
[M+H]+ (100%), 721 [Au(PPh3)2]+ (90%), 1032
[(Ph3PAu)2SC(NCN)NHMe]+ (5%), 1164 [2M+H]+
Cy3PAuCl (250 mg, 0.488 mmol) with PhNHC(S)NMe2
(100 mg, 0.556 mmol) gave a white powder of 9 (266 mg,
83%). M.p. 131–133 ꢁC. Anal. Calc. for C27H44N2AuPS:
C, 49.4; H, 6.75; N, 4.3. Found: C, 49.1; H, 6.9; N, 4.2%.
31P–{1H} NMR, d 55.9 (s). 1H NMR, d 7.28–6.81 (m,
Ph), 3.28 (s, NMe2), 1.81–1.26 (m, Cy). ESI-MS, m/z 657
[M+H]+ (100%), 1133 [(Cy3PAu)2SC(NPh)NMe2]+ (3%).
IR mmax 1558 cmꢁ1 (s).
3.2.9. Cy3PAuSC(@NPh)N(CH2CH2)2O (10)
Cy3PAuCl (200 mg, 0.390 mmol) with PhNH-
C(S)N(CH2CH2)2O (87 mg, 0.392 mmol) gave a white
powder of 10 (270 mg, 99%). M.p. 214–218 ꢁC. Anal. Calc.
for C29H46N2AuOPS: C, 49.85; H, 6.6; N, 4.0. Found: C,
49.6; H, 6.8; N, 4.2%. 31P–{1H} NMR, d 56.4 (s). 1H
NMR, d 7.28–6.81 (m, Ph), 3.87 (m, CH2O), 3.76 (m,
CH2N), 1.84–1.27 (m, Cy). ESI-MS, m/z 699 [M+H]+
(100%), 1175 [(Cy3PAu)2SC(NPh)N(CH2CH2)2O]+ (3%).
IR mmax 1560 cmꢁ1 (s).
(10%). IR mmax 2159 (s) and 1534 (s) cmꢁ1
.
3.4. Synthesis of dppe[AuSC(@NCN)NHMe]2 (13)
A suspension of dppe(AuCl)2 (200 mg, 0.231 mmol) and
Na[MeNHC(S)NCN] (70 mg, 0.511 mmol) in methanol
(25 mL) was stirred at room temperature, rapidly giving a
clear colourless solution, which then deposited a white

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
213
Table 3
Crystallographic data and refinement details for 1, 8, 10, 11 and 12 Æ CH2Cl2
Complex
1
8
10
11
12 Æ CH2Cl2
Formula
Molecular weight
T/K
C29H28AuN2OPS
680.53
223
C21H19AuN3PS
573.39
168
C29H46AuN2OPS
698.67
223
C56H54Au2FeN4O2P2S2
1390.88
223
C48H50Au2N4O2P2S2 Æ CH2Cl2
1319.84
223
Crystal system
triclinic
monoclinic
P21/n
8.155(2)
14.290(3)
17.431(4)
90
92.865(3)
90
2028.8(8)
4
triclinic
monoclinic
P21/n
22.7135(13)
9.7423(5)
24.2348(13)
90
110.312(1)
90
5029.2(5)
4
triclinic
ꢀ
ꢀ
ꢀ
Space group
P1
P1
P1
˚
a (A)
8.8802(5)
12.5815(7)
13.1321(7)
111.443(1)
107.180(1)
92.425(1)
1285.94(12)
2
10.2467(5)
11.0923(6)
13.5082(7)
80.747(1)
71.612(1)
84.415(1)
1436.21(13)
2
11.6971(7)
11.9933(8)
19.0573(12)
81.529(1)
72.568(1)
74.016(2)
2446.0(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Dcalc (g cmꢁ3
)
1.758
1.877
1.616
1.837
1.792
Number of unique reflections
Number of observed
reflections [I > 2r(I)]
R [I > 2r(I)]
7338
6780
4124
3810
8075
7707
14667
10547
14013
10575
0.024
0.039
0.017
0.039
0.045
a, b for weighting scheme
wR (all data)
0.029, 0
0.059
0.045, 15.279
0.097
0.019, 0.262
0.041
0.040, 0
0.085
0.041, 5.092
0.109
solid after several minutes. The suspension was stirred at
room temperature for 24 h, water (20 mL) added, and the
white solid filtered off, washed with water (10 mL) and
diethyl ether (10 mL) and dried under vacuum to give 13
(165 mg, 70%). M.p. 185–188 ꢁC. Anal. Calc. for
C32H32N6Au2P2S2: C, 37.7; H, 3.2; N, 8.2. Found: C,
38.2; H, 2.9; N, 8.2%. 31P–{1H} NMR, d 37.3 (s). 1H
NMR, d 7.83–7.23 (m, Ph), 6.0 (s, br, NH), 2.99 (m,
the cell growth of the P388 leukemia cell line (ATCC
CCL 46) by 50%. The sample of interest was incubated
for 72 h with the P388 Murine Leukemia cells. IC50
values were determined by measurement of the absor-
bance values when the yellow dye MTT tetrazolium is
reduced by healthy cells to the purple dye MTT
formazan.
The antimicrobial assays were carried out by measuring
the inhibition zone as an excess radius (mm) from a 6 mm
diameter filter paper disk containing 2 lg of sample, which
was placed on a seeded agar plate containing the organism
tested.
Me). IR mmax 2151 (s) and 1539 (s) cmꢁ1
.
3.5. Crystallography
Intensity data for 1 and 10–12 were measured at 223 K
(168 K for 8) on a Bruker SMART CCD (Siemens
SMART CCD for 8) employing Mo Ka radiation so that
4. Supplementary material
h
max = 30.0ꢁ (26.4ꢁ for 8). The structures were solved by
Crystallographic data (excluding structure factors) for
the structures described in this paper have been deposited
with the Cambridge Crystallographic Data Centre, CCDC
Nos. 273865–273869. Copies of the data can be obtained
free of charge on application to The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223
336 033; deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
heavy-atom methods [33] (SHELXS-97 [34] for 8) and refine-
ment (anisotropic displacement parameters, hydrogen
atoms in the riding model approximation and a weighting
2
scheme of the form w ¼ 1=½r2ðF o2Þ þ ðaPÞ þ bPꢂ for
P ¼ ðF 2o þ 2F 2cÞ=3) was on F2 [35]. Complex 12 was charac-
terised as its 1:1 CH2Cl2 solvate. Data manipulation was
with teXsan [36] and crystallographic diagrams were drawn
using ORTEP-II [37]. Crystallographic data and final
refinement details are given in Table 3.
Acknowledgements
3.6. Biological assays
We thank the University of Waikato and the National
University of Singapore (NUS) for support of this work.
We also thank Dr. Ralph Thomson for recording the
NMR spectra, and Sarah Devoy for technical assistance.
Professor Ward Robinson and Jan Wikaira (University
of Canterbury, New Zealand) are thanked for collection
of the X-ray data set of 8. The State Government of
Queensland is thanked for the award of a Smart Returns
Fellowship to E.R.T.T.
Assays were carried out by the commercial service
offered by the Marine Chemistry Group, Department
of Chemistry, Canterbury University, New Zealand.
Samples were dissolved in 3:1 methanol–dichloromethane
prior to testing. Cytotoxicity assays were carried out by
determining, by means of a twofold dilution series, the
concentration of sample in ng mLꢁ1 required to reduce

214
W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 204–214
[19] J.D.E.T. Wilton-Ely, A. Schier, N.W. Mitzel, S. Nogai, H. Schmid-
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