Synthesis, structural characterization and cytotoxicity of bimetallic chlorogold(I) phosphine complexes employing functionalized phosphinoferrocene carboxamides

Article abstract of DOI:10.1016/j.jorganchem.2013.07.014

Gold(I) phosphine complexes of the general formula [AuCl(Ph ₂PfcCONHY-κP)], where Y is CH₂CO₂Me (7), CH₂CONH₂ (8), CH₂CH₂OH (9), CH(CH₂OH)₂ (10), C(CH₂OH)₃ (11), and CH₂SO₃(HNEt₃) (12), and fc is ferrocene-1, 10-diyl, were prepared from [AuCl(tht)] (tht = tetrahydrothiophene) and the appropriate phosphinoferrocene carboxamides (1-6). The compounds were characterized by spectroscopic and analytical methods, and the molecular structures of 7 and 9 were determined by single-crystal X-ray crystallography. Complexes 7-12 exerted antiproliferative activity against the human ovarian cancer cells in vitro. The IC₅₀ values ranged ca. 0.3-3.7 μM for the A2780 cell line, and 3.1-20 μM for the cisplatin resistant cell line A2780R, with complex 7 being the most cytotoxic against both cell types. IC ₅₀ values for the non-tumorigenic human embryonic kidney (HEK) cells, serving as a measure of a general toxicity, were found in roughly similar ranges, i.e. 0.9-6.8 μM.

Full text of DOI:10.1016/j.jorganchem.2013.07.014

Journal of Organometallic Chemistry 751 (2014) 604e609
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, structural characterization and cytotoxicity of bimetallic
chlorogold(I) phosphine complexes employing functionalized
phosphinoferrocene carboxamides
a
a
a
b
b
ꢀ
ꢀ
ꢀ
Jirí Schulz , Jirí Tauchman , Ivana Císarová , Tina Riedel , Paul J. Dyson ,
a,
ꢀ
*
ꢀ
ꢀ
Petr Stepnicka
a Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, CZ-12840 Prague, Czech Republic
b Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
a r t i c l e i n f o
a b s t r a c t
Article history:
Gold(I) phosphine complexes of the general formula [AuCl(Ph2PfcCONHY-kP)], where Y is CH2CO2Me (7),
Received 12 June 2013
Received in revised form
27 June 2013
CH2CONH2 (8), CH2CH2OH (9), CH(CH2OH)2 (10), C(CH2OH)3 (11), and CH2SO3(HNEt3) (12), and fc is
ferrocene-1,10-diyl, were prepared from [AuCl(tht)] (tht ¼ tetrahydrothiophene) and the appropriate
phosphinoferrocene carboxamides (1e6). The compounds were characterized by spectroscopic and
analytical methods, and the molecular structures of 7 and 9 were determined by single-crystal X-ray
crystallography. Complexes 7e12 exerted antiproliferative activity against the human ovarian cancer
Accepted 5 July 2013
Keywords:
Bioorganometallic chemistry
Gold complexes
Phosphine ligands
Ferrocene ligands
Anticancer activity
X-ray crystallography
cells in vitro. The IC50 values ranged ca. 0.3e3.7
mM for the A2780 cell line, and 3.1e20 mM for the
cisplatin resistant cell line A2780R, with complex 7 being the most cytotoxic against both cell types. IC50
values for the non-tumorigenic human embryonic kidney (HEK) cells, serving as a measure of a general
toxicity, were found in roughly similar ranges, i.e. 0.9e6.8 mM.
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
complexes exhibit potent cytotoxic activity in vitro and antitumor
activity in vivo [11].
Amide linkage represents a chemically and structurally well-
defined way to conjugate diverse molecular moieties. Not surpris-
ingly, therefore, amide linkers have been widely used in the design
of functional phosphine donors that display useful catalytic and
biological properties [1]. During our studies on phosphinoferrocene
carboxamides prepared from 10-(diphenylphosphino)ferrocene-1-
carboxylic acid (Hdpf) [2] and polar functional amines (Scheme 1)
such as aminosulfonic acids [3], amino acid esters [4,5] and
hydroxyamines [6,7], we reasoned that the attached functional
pendants can affect bioavailability of transition metal complexes
prepared from such phosphinoamide ligands (a bulky lipophilic
complex with a hydrophilic tag) or alternatively act as a directing
group. Indeed, transition metalephosphine complexes have been
widely explored in medicinal chemistry [8] and a goldephosphine
complex (auranofin) is used in the clinic to treat arthritis [9]. Aur-
anofin also displays significant cytotoxicity toward a range of
different cancer cells [10], and a large number of gold(I) phosphine
Moreover, there is considerable interest in the biological activity
and medicinal properties of ferrocene-based compounds [12] with
simple ferrocene compounds exhibiting good cytotoxicities in vitro
and tumor growth inhibition in vivo [13]. Jaouen has shown that
appending the ferrocenyl group to biologically active molecules
affords complexes with an increased potency with tumor speci-
ficity possibly due to the combined action of the organic molecule
with Fenton chemistry of the iron centre [14]. There are also
numerous reports describing the cytotoxic effects of bimetallic,
ferrocene-containing compounds including platinum [15],
PPh2
PPh2
Fe
Fe
O
C
O
C
OH
NH FG
Hdpf
* Corresponding author. Fax: þ420 221 951 253.
Scheme 1. Design of functional phosphinoferrocene carboxamides. FG stands for a
functional moiety.
ꢀ
ꢀ
ꢀ
E-mail address: stepnic@natur.cuni.cz (P. Stepnicka).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.07.014

J. Schulz et al. / Journal of Organometallic Chemistry 751 (2014) 604e609
605
palladium [16], ruthenium [9] and gold(I) [11] phosphinoferrocene
complexes. The association of two active metals showed cytotoxic
activities comparable or superior to cisplatin in various cancer cell
lines.
We recently evaluated the cytotoxic properties of Pd(II) and
Pt(II) complexes bearing a phosphinoferrocene carboxamide pos-
sessing 2-hydroxyethyl substituent at the amide nitrogen as
P-monodentate donor [16] and of (h
6-arene)Ru(II) complexes with
phosphinoferrocene amides derived from amino acid esters [17].
This contribution extends our work toward gold(I) complexes and
phosphinoferrocene carboxamides derived from amino acid esters,
aminosulfonates and hydroxyamines.
2. Results and discussion
2.1. Synthesis of the Au(I) complexes 7e12
The neutral gold(I) complexes 7e12 were prepared in
a
straightforward manner by the substitution of the labile tetrahy-
drothiophene (tht) ligand in the precursor complex [AuCl(tht)]
with the stoichiometric amount of the appropriate phosphino-
ferrocene carboxamide 1e6 (Scheme 2). The complexes were iso-
lated in good yields as air-stable, somewhat light sensitive solids
that were characterized by NMR and IR spectroscopy, electrospray
ionization (ESI) mass spectrometry and elemental analysis.
The 1H NMR spectra of 7e12 corroborate the anticipated
structures, as do the 31P NMR spectra, which display resonances in a
narrow range, dP 28.5e28.7, downfield with respect to the free li-
gands. The IR spectra of the complexes show the characteristic
bands due to the amide moieties, i.e. the NH stretching vibrations
and, mainly, the strong amide I and amide II bands at 1625e
1650 cme1 and around 1530 cme1, respectively.
Fig. 1. PLATON plot of the molecular structure of 7 showing the atom labeling scheme
and displacement ellipsoids at the 30% probability level.
of 9 are similar to each other and also compare well to those re-
ported previously for, e.g., (Et2NH2)[ClAuPh2PfcCO2] [18],
[ClAuPh2PfcEPh] (E ¼ S and Se) [19], [ClAuPh2PfcCH2NMe2] and
[ClAuPh2PfcCH2NHMe2]X (X ¼ Cl and ClO4) [20], and for complexes
of the type [ClAuPh2PfcY], where Y is 2- or 3-pyridyl, and CH2(2-
pyridyl) [21]. Likewise, the geometric parameters describing the
amide pendant do not digress significantly from those reported for
uncoordinated amides 1 and 3 and their palladium complexes [4,6].
The ferrocene units in both structurally independent molecules
possess regular geometries, showing only marginal variations in
2.2. Molecular structure of complexes 7 and 9
ꢁ
The molecular structure of 7 is shown in Fig. 1 and the selected
bond parameters are summarized in Table 1. Compound 9 crystal-
lizes with two molecules per the asymmetric unit. A view of
molecule 1 is shown in Fig. 2 with key bond parameters for both
structurally independent molecules given in Table 2. As indicated
by the overlap (Fig. 2), the independent molecules of 9 differ mainly
by the conformation of their polar amide pendants, which seems to
reflect the different roles the molecules have to play in the solid-
state assembly (see below).
the individual FeeC distances (FeeC: 2.022(2)e2.054(2) A for 7;
ꢁ
ꢁ
2.035(5)e2.061(4) A for 9, molecule 1, and 2.025(5)e2.056(4) A for
9, molecule 2) and, accordingly, an insignificant tilting (7: 1.6(1)ꢀ, 9:
ca. 3.5ꢀ). The ferrocene cyclopentadienyl rings in 7 adopt an in-
termediate conformation with
s
¼ ꢁ164.9(2)ꢀ that brings the
substituents in positions 1 and 10 of the ferrocene unit into mutu-
ally opposite positions. On the other hand, the substituents in both
molecules of 9 assume synclinal eclipsed conformations (cf. the
s
angle in Table 2 with the ideal value of 72ꢀ).
The geometry of the fcPPh2eAueCl moieties (fc ¼ ferrocene-
In the solid state, the molecules of 7 associate into infinite
chains via C]O/HeN hydrogen bonds around the crystallo-
graphic 21 screw axes (Fig. 3). In contrast, the molecules of 9 form
dimers constituted from molecules 1 and 2 via pairs of NeH/Cl
1,10-diyl) in 7 and both crystallographically independent molecules
Ph2
PPh2
P
Au
O
[AuCl(tht)]
– tht
Fe
Fe
Cl
Table 1
a
O
C
ꢁ
Selected distances and angles for 7 (A and deg).
C
Distances
Angles
NH FG
NH FG
AueCl
AueP
2.2976(6)
2.2396(6)
1.643(1)
1.653(1)
1.230(2)
1.350(3)
1.196(3)
1.339(3)
CleAueP
176.91(2)
1.6(1)
:CpP,CpC
FG = CH2CO2Me (1)
CH2CONH2 (2)
FG = CH2CO2Me (7)
CH2CONH2 (8)
FeeCgP
FeeCgC
C11eO1
C11eN
C25eO2
C25eO3
T
ꢁ164.9(2)
122.5(2)
120.9(2)
124.6(2)
74.9(2)
NeC11eO1
C11eNeC24
O2eC25eO3
C11eNeC24eC25
NeC24eC25eO2
CH2CH2OH (3)
CH(CH2OH)2 (4)
C(CH2OH)3 (5)
CH2CH2OH (9)
CH(CH2OH)2 (10)
C(CH2OH)3 (11)
CH2SO3(HNEt3) (12)
ꢁ0.7(3)
CH2SO3(HNEt3) (6)
a
Definitions: CpP and CpC denote the PPh2- and amide-substituted cyclo-
Scheme 2. Preparation of Au(I) complexes 7e12. FG denotes a functional group, tht is
tetrahydrothiophene.
pentadienyl rings, respectively. CgP and CgC stand for the respective ring centroids.
s
¼ C1eCgCeCgPeC6.

606
J. Schulz et al. / Journal of Organometallic Chemistry 751 (2014) 604e609
Fig. 3. Section of the infinite hydrogen-bonded chain in the structure of 7. For clarity,
all CH hydrogens were omitted. The H-bond parameters are as follows: N/H1N/O1i,
i
ꢀ
ꢁ
N1/O1 ¼ 2.875(2) A, angle at H1N ¼ 150 ; i. (ꢁx, ½þy, ½ꢁz).
significant Au/Au (aurophilic) contacts were observed in both
structures [22].
2.3. Cytotoxicity tests
The antiproliferative activity of 7e12 has been studied on the
ovarian cancer cell lines A2780 and A2780cisR, the latter having
acquired resistance to cisplatin, and on human embryonic kidney
cells (HEK), a non-tumorigenic model. IC50 values are summarized
in Table 3. The complexes display high cytotoxicities, with IC50
Fig. 2. (a) PLATON plot of molecule 1 in the structure of 9 showing the atom labeling
scheme and displacement ellipsoids at the 30% probability level. Note: the respective
atomic labels in molecule 2 are obtained by changing the first digit to two. (b) Overlap
of the two structurally independent molecules (molecule 1 in black, molecule 2 in red).
(For interpretation of the references to colour in this figure legend, the reader is
referred to the web version of this article.)
values in the low micromolar region ranging 0.27e3.7
A2780 cell line and 0.94e6.8 M for the HEK cell line.
mM for the
m
The most active complexes are 7 and 9 which contain glycine
ester and hydroxyethyl substituents, respectively. With IC50 values
of 0.27 ꢂ 0.01
m
M (7) and 0.6 ꢂ 0.05
m
M (9) respectively for the
A2780 cell line, and 3.1 ꢂ 0.5
m
M (7) and 6.5 ꢂ 0.5
mM (9) for the
hydrogen bonds (Fig. 4). These dimers further assemble into
infinite ribbons through O22eH2O/O12 interactions while the
other OH group (O12eH1O in molecule 1) forms an intra-
molecular hydrogen bridge toward the amide oxygen O11. No
Table 2
Selected distances and angles for the crystallographically independent molecules in
a
ꢁ
the structure of 9 (A and deg).
Molecule 1
Molecule 2
Au1eCl1
Au1eP1
2.297(1)
2.227(1)
174.96(4)
1.643(2)
1.659(2)
3.4(3)
ꢁ74.7(4)
1.248(6)
1.335(7)
121.3(5)
1.413(7)
71.3(6)
Au2eCl2
Au2eP2
2.297(1)
2.227(1)
177.96(5)
1.642(2)
1.648(3)
3.4(3)
ꢁ76.8(4)
1.237(8)
1.338(8)
120.1(7)
1.327(9)
175.0(5)
Cl1eAu1eP1
Cl2eAu2eP2
FeeCgP
FeeCgP
FeeCgC
FeeCgC
:CpP,CpC
T1
:CpP,CpC
s2
C111eO11
C111eN1
N1eC111eO11
C125eO12
N1eC124eC125eO12
C211eO21
C211eN2
N2eC211eO21
C225eO22
N2eC224eC225eO22
Fig. 4. Depiction of the OeH/O and NeH/Cl interactions in the structure of 9. For
clarity, only the NH and OH hydrogens and the pivotal atoms from the benzene rings
are shown. Hydrogen bond parameters are as follows: N1eH1N/Cl2i,
i
i
N1/Cl2i ¼ 3.324(4) A, angle at H1N ¼ 147 ; N2eH2N/Cl1 , N2/Cl1 ¼ 3.454(4) A,
ꢀ
ꢁ
ꢁ
a
Definitions: CpP and CpC denote the PPh2- and amide-substituted cyclo-
angle at H2N ¼ 141 ; O12eH1O/O11, O12/O11 ¼ 2.748(5) A, angle at H1O ¼ 159 ;
ꢀ
ꢀ
ꢁ
pentadienyl rings, respectively. CgP and CgC are their respective centroids.
O22eH2O/O12ii, O22/O12ii ¼ 2.840(7) A, angle at H2O ¼ 148 ; symmetry codes: i.
ꢀ
ꢁ
s
n ¼ Cn01eCgCneCgPneCn06 (n indicates the molecule).
(ꢁx, 1 ꢁ y, 1 ꢁ z), ii. (ꢁx, 2 ꢁ y, 1 ꢁ z).

J. Schulz et al. / Journal of Organometallic Chemistry 751 (2014) 604e609
607
Table 3
4. Experimental
IC50 values for A2780 and cisplatin resistant A2780R ovarian cancer cells and for
non-tumorigenic HEK cells (exposure: 72 h).
4.1. Materials and methods
Compound
IC50 (A2780) [
m
M] IC50 (A2780R) [
m
M] IC50 (HEK) [mM]
All syntheses were performed under argon atmosphere with an
exclusion of the direct day light. Compound [AuCl(tht)] [26] and
phosphinoferrocene ligands 1, 2 [4], 3 [6], 4, 5 [7], and 6 [3] were
prepared according to the literature procedures. Anhydrous CH2Cl2
(SigmaeAldrich) and other solvents (Lachner) were used as
received.
7
8
9
10
11
12
0.27 ꢂ 0.01
3.7 ꢂ 0.2
0.60 ꢂ 0.05
1.5 ꢂ 0.4
1.2 ꢂ 0.3
3.4 ꢂ 0.4
4.3 ꢂ 0.5
1.3 ꢂ 0.5
3.1 ꢂ 0.5
20.0 ꢂ 0.1
6.5 ꢂ 0.5
10.5 ꢂ 1.3
20.3 ꢂ 0.2
10.6 ꢂ 0.4
18 ꢂ 1
0.94 ꢂ 0.07
6.8 ꢂ 0.3
3 ꢂ 1
4.3 ꢂ 0.7
4.6 ꢂ 0.4
5.3 ꢂ 0.3
n.a.
Cisplatin Ref. [23]
Auranofin Ref. [23]
1H NMR spectra were recorded on a Varian UNITY Inova 400
1.5 ꢂ 0.3
n.a.
spectrometer (1H, 399.95 MHz and 31P{1H}, 161.90 MHz) at 298 K.
Chemical shifts (d/ppm) are given relative to internal tetrame-
thylsilane (1H) or to external 85% aqueous H3PO4 (31P). ESI-MS were
recorded on a Bruker Esquire 3000 spectrometer using samples
dissolved in methanol. The formulations of the observed ionic
species were confirmed by a comparison of the theoretical
and experimentally determined isotopic patterns. Infrared spectra
were recorded in Nujol mulls with an FT IR Nicolet Magna 760
instrument.
cisplatin resistant cell line, these complexes are more cytotoxic
than the reference drug cisplatin [23]. The other compounds
exhibit comparable cytotoxicities to cisplatin in A2780 cells as well
and marginally lower cytotoxicites in the cisplatin resistant cell
line.
The presence of the phosphineeAueCl moiety has a strong in-
fluence on biological activity. Compared to (h
6-arene)Ru(II) com-
plexes containing the phosphinoferrocene amino acid ester
conjugates as P-monodentate donors reported previously [17],
replacement of the p-cymene ruthenium complex by the AueCl
moiety leads to a more than 100-fold higher activity. This change is
not unexpected as arene ruthenium phosphine complexes tend not
to be very cytotoxic [24] and taken together these data indicate that
the AueCl unit exerts a greater influence on the overall cytotoxicity
that the phosphinoferrocene fragment. This is in accordance with
our recent study showing that phosphinoferrocene carboxamide
bearing a hydroxyethyl substituent (ligand 3) and palladium(II) and
platinum(II) bis(phosphine) complexes derived thereof resulted in
4.2. Preparation of [AuCl(Ph2PfcCONHCH2CO2Me-kP)] (7)
A solution of ligand 1 (97 mg, 0.20 mmol) in dichloromethane
(2 mL) was added to solid [AuCl(tht)] (64 mg, 0.20 mmol). The
resultant yellow solution was stirred at room temperature for
60 min and filtered into pentane (80 mL). The mixture was allowed
to stand overnight at ꢁ18 ꢀC before the resulting precipitate was
filtered off, washed with cold pentane and dried in vacuo to give 7
as a yellow solid. Yield: 138 mg, 96%. Crystals suitable for X-ray
analysis were obtained by slow diffusion of hexane into a toluene
solution of 7 at room temperature. 1H NMR (CDCl3):
d 3.75 (s, 3H,
OMe), 4.17 (d, 3JHH ¼ 6.0 Hz, 2H, NHCH2), 4.18 (virtual t, J z 2 Hz, 2H,
fc), 4.49 (virtual q, J z 2 Hz, 2H, fc), 4.74 (virtual q, J z 2 Hz, 2H, fc),
4.91 (virtual t, J z 2 Hz, 2H, fc), 6.59 (t, 3JHH ¼ 6.0 Hz, 1H, NHCH2),
negligible cytotoxicity (IC50 > 200
mM) or IC50 values in a moderate
micromolar range, respectively [16].
Compounds possessing the highly polar amidoamine and
amidosulfonate moieties (8 and 12) exert higher IC50 values.
Finally, exchanging the hydroxyethyl substituent by a bulkier
substituent (such as CH(CH2OH)2 in 10 and C(CH2OH)3 in 11) leads
to an at least two-fold increase of IC50 values for the A2780 and
A2780cisR cell lines but not for HEK cells, which might imply that
the bulkiness of the substituent plays a significant role in deter-
mining the biological activity in cancer cells but not in non-
cancerous cells.
7.43e7.62 (m, 10H, PPh2). 31P{1H} NMR (CDCl3):
d 28.6 (s). IR
(Nujol): nNH 3360 m, nCO 1751 vs, amide I 1648 vs, amide II
1533 s cmꢁ1. MS (ESIþ): m/z 756 ([M þ K]þ), 740 ([M þ Na]þ), 682
([M ꢁ Cl]þ). Anal. Calcd. for C26H24NO3PClFeAu: C 43.51, H 3.37, N
1.95%. Found: C 43.22, H 3.34, N 1.77%.
4.3. Preparation of [AuCl(Ph2PfcCONHCH2CONH2-kP)] (8)
Complex 8 was prepared similarly from 2 (94 mg, 0.20 mmol)
3. Conclusions
and [AuCl(tht)] (64 mg, 0.20 mmol) and isolated as a yellow solid.
3
Yield: 133 mg, 92%. 1H NMR (CDCl3):
d
4.08 (d, JHH ¼ 4.2 Hz, 2H,
A series of bimetallic complexes comprising phosphinoferro-
cene carboxamides coordinated via the phosphine group to AuCl
fragment have been prepared and evaluated for their cytotoxicity
against human ovarian cancer cells. The particular combination of
molecular fragments with different biological activity and physi-
cochemical properties (e.g., solubility and hydrophobicity) results
in highly cytotoxic species, with the role of AueCl being dominant
with respect to the low IC50 values (N.B. Our previous study dealing
with ligand 3, the corresponding phosphine oxide and sulfide, and
its Pd(II) and Pt(II) complexes revealed that the uncoordinated
ferrocene derivatives are practically not cytotoxic [16]). Neverthe-
less, the two different metal containing units constituting com-
plexes 7e12 presumably exert different effects on the cells, e.g.,
broad acting Fenton chemistry from the ferrocene [14] and, mainly,
inhibition of various enzymes by the highly reactive gold(I) unit
[25]. Unfortunately, the compounds do not display significant drug
selectivity although it may be possible to improve the selectivity by
modulating the steric bulk of the substituent at the carboxamide
moiety.
NHCH2), 4.26 (br s, 2H, fc), 4.41 (br s, 2H, fc), 4.70 (br s, 2H, fc), 4.86
(br s, 2H, fc), 6.65, 6.24, 6.85 (3 ꢃ br s, 1H, NH), 7.43e7.62 (m, 10H,
PPh2). 31P{1H} NMR (CDCl3):
d 28.5 (s). IR (Nujol): nNH 3338 s,
amide I 1683 vs, amide I 1644 vs, amide II 1534 s cmꢁ1. MS (ESIþ):
m/z 741 ([M þ K]þ), 725 ([M þ Na]þ), 705 ([M ꢁ HCl þ K]þ),
689 ([M ꢁ HCl þ Na]þ), 667 ([M ꢁ Cl]þ). Anal. Calcd. for C25H23
N2O2PClFeAu∙0.3CH2Cl2: C 41.73, H 3.27, N 3.85%. Found: C 41.68, H
3.28, N 3.63%. The content of clathrated solvent was verified by 1H
NMR spectroscopy.
4.4. Preparation of [AuCl(Ph2PfcCONHCH2CH2OH-kP)] (9)
Ligand 3 (92 mg, 0.2 mmol) and [AuCl(tht)] (64 mg, 0.2 mmol)
were mixed in dichloromethane (5 mL) and the resulting solution
was stirred at room temperature for 1 h. Then, it was concentrated
under vacuum and precipitated by addition of hexanes (5 mL). The
suspension was cooled to ꢁ18 ꢀC overnight before the precipitate
was filtered off, washed with diethyl ether (2 ꢃ 5 mL) and dried
under vacuum. A subsequent crystallization by slow diffusion of

608
J. Schulz et al. / Journal of Organometallic Chemistry 751 (2014) 604e609
¼ 109.404(1)ꢀ;
ꢁ
b
hexanes into ethyl acetate solution of 9 afforded the gold(I) com-
a ¼ 19.2763(5), b ¼ 9.8191(2), c ¼ 13.5833(4) A;
3
plex as orange crystals. Yield 113 mg (82%). 1H NMR (CDCl3):
d
3.11
V ¼ 2425.0(1) A , Z ¼ 4, Dcalc ¼ 1.97 g mLꢁ1
.
ꢁ
3
(t, JHH ¼ 5.4 Hz, 1H, OH), 3.63 (virtual q, JHH ¼ 5.0 Hz, 2H, CH2O),
3.84 (virtual t, JHH ¼ 5.0 Hz, 2H, NHCH2), 4.14 (virtual t, J z 2 Hz, 2H,
fc), 4.27e4.28 (m, 2H, fc), 4.70e4.71 (m, 2H, fc), 4.93 (virtual t,
Full-set diffraction data (ꢂh ꢂ k ꢂ l) were recorded with an Apex
2 (Bruker) diffractometer equipped with Cryostream Cooler (Ox-
ford Cryosystems) using graphite-monochromated Mo Ka radiation
3
ꢁ
J z 2 Hz, 2H, fc), 6.64 (t, JHH ¼ 5.0 Hz, 1H, NHCH2), 7.48e7.62 (m,
(l
¼ 0.71073 A) at 150(2) K. The data were corrected for absorption
10H, PPh2). 31P{1H} NMR (CDCl3):
d
28.6 (s). IR (Nujol): nNH 3361 m,
(m
¼ 6.85 mme1) using a numerical method as incorporated in the
amide I 1624 s, amide II 1534 vs cmꢁ1. MS (ESIþ): m/z 712
([M þ Na]þ), 676 ([M ꢁ HCl þ Na]þ), 654 ([M ꢁ Cl]þ). MS (ESIꢁ): m/z
689 ([M ꢁ H]ꢁ). Anal. Calcd. for C25H24PFeO2NClAu: C 43.53, H 3.51,
N 2.03%. Found: C 43.24, H 3.51, N 1.91%.
diffractometer software. A total of 41,939 diffractions was recorded
(
qmax ¼ 27.5ꢀ, data completeness ¼ 100%), from which 5562 were
unique (Rint ¼ 2.87%), and 5078 were observed according to the
I > 2s(I) criterion.
The structure was solved by direct methods (SHELXS97 [27])
and refined by full-matrix least-squares routine based on F2
(SHELXL97 [27]). The non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogens bonding to car-
bon atoms were included in their calculated positions and refined
as riding atoms with Uiso(H) assigned to 1.2 or 1.5Ueq(C). The NH
hydrogens were identified on a difference Fourier map and refined
as riding atoms with Uiso(H) ¼ 1.2Ueq(N). The refinement converged
4.5. Preparation of [AuCl(Ph2PfcCONHCH(CH2OH)2-kP)] (10)
Complex 10 was prepared similarly to 9 starting from 4 (98 mg,
0.2 mmol) and [AuCl(tht)] (64 mg, 0.2 mmol), and was isolated as a
yellow powder. Yield 130 mg (90%). 1H NMR (CDCl3):
d 3.30 (br t,
3JHH ¼ 5.2 Hz, 2H, OH), 3.86e3.96 (m, 4H, CH2O), 4.09e4.15 (m, 1H,
NHCH), 4.16 (virtual t, J z 2 Hz, 2H, fc), 4.34e4.36 (m, 2H, fc), 4.69e
4.71 (m, 2H, fc), 4.87 (virtual t, J z 2 Hz, 2H, fc), 6.67 (d,
3JHH ¼ 7.0 Hz, 1H, NHCH), 7.44e7.59 (m, 10 H, PPh2). 31P{1H}
(D/s
ꢄ 0.002, 308 parameters) to R ¼ 1.66% for the observed, and
R ¼ 2.02%, wR ¼ 3.52% for all diffractions. The final difference map
displayed no peaks of chemical significance
(
Drmax
¼
1.20,
NMR (CDCl3):
d 28.6 (s). IR (Nujol): nNH 3343 m, amide I 1633 s,
ꢁꢁ3
amide II 1537 s cmꢁ1. MS (ESIþ): m/z 742 ([M þ Na]þ), 706
([M ꢁ HCl þ Na]þ), 684 ([M ꢁ Cl]þ). MS (ESIꢁ): m/z 718 ([M ꢁ H]ꢁ).
Anal. Calcd. for C26H26PFeO3NClAu: C 43.39, H 3.64, N 1.95%. Found:
C 43.16, H 3.58, N 1.78%.
Drmin ¼ ꢁ0.56 e A ).
Crystal data for 9: C25H24AuClFeNO2P, M ¼ 689.7, orange prism
(0.18 ꢃ 0.25 ꢃ 0.25 mm3), triclinic, space group Pe1 (no. 2),
¼ 72.424(1)ꢀ,
ꢁ
a ¼ 10.6818(2), b ¼ 12.6034(2), c ¼ 19.7850(4) A;
a
3
ꢀ
ꢁ
b
¼ 89.3664(9)ꢀ,
g
¼ 68.673(1) ; V ¼ 2350.69(7) A , Z ¼ 4,
Dcalc ¼ 1.95 g mLꢁ1
.
4.6. Preparation of [AuCl(Ph2PfcCONHC(CH2OH)3-kP)] (11)
The diffraction data were recorded similarly and were corrected
for absorption (
m
¼ 7.06 mme1) by an integration method included
Starting from 5 (104 mg, 0.2 mmol) and [AuCl(tht)] (64 mg,
in the diffractometer software. A total of 45,773 diffractions was
collected (qmax ¼ 27.5ꢀ, data completeness ¼ 99.8%), from which
10,782 were unique (Rint ¼ 5.51%), and 8121 were observed ac-
0.2 mmol), the above procedure afforded 11 as a yellow powder.
3
Yield 131 mg (87%). 1H NMR (CDCl3):
d
3.75 (d, JHH ¼ 4.5 Hz, 6H,
CH2O), 4.00 (unresolved t, 3H, OH), 4.17 (virtual t, J z 2 Hz, 2H, fc),
4.36e4.38 (m, 2H, fc), 4.69e4.70 (m, 2H, fc), 4.78 (virtual t, J z 2 Hz,
2H, fc), 6.88 (s, 1H, NHC), 7.44e7.59 (m, 10 H, PPh2). 31P{1H} NMR
cording to the I > 2s(I) criterion.
The refinement performed similarly to that of 7 converged (D/
s
ꢄ 0.001, 577 parameters) to R ¼ 3.43% for the observed, and
(CDCl3):
II 1525
d 28.5 (s). IR (Nujol): nNH 3373 s, amide I 1636 s, amide
R ¼ 5.53%, wR ¼ 8.12% for all diffractions. The final difference map
s
cmꢁ1
.
MS (ESIþ): m/z 772 ([M
þ
Na]þ), 736
displayed no peaks of chemical significance; the largest residual
([M ꢁ HCl þ Na]þ), 714 ([M ꢁ Cl]þ). MS (ESIꢁ): m/z 748 ([M ꢁ H]ꢁ).
Anal. Calcd. for C27H28PFeO4NClAu: C 43.25, H 3.76, N 1.87%. Found:
C 43.79, H 3.72, N 1.77%.
electron density peaks were detected in vicinity of the Au atoms
ꢁꢁ3
(
Drmax ¼ 1.41, Drmin ¼ ꢁ2.34 e A ).
4.9. Antiproliferative assays
4.7. Preparation of (HNEt3)[AuCl(Ph2PfcCONHCH2SO3-kP)] (12)
Human A2780 and A2780cisR cells were obtained from the Eu-
ropean Centre of Cell Cultures (ECACC, Salisbury, UK). All cell culture
reagents were obtained from Gibco-BRL (Basel, Switzerland). Cells
were grown in RPMI 1640 medium containing 10% fetal bovine
Complex 12 was obtained similarly from 6 (122 mg, 0.2 mmol)
and [AuCl(tht)] (64 mg, 0.2 mmol) and isolated as a yellow powder.
The precipitate obtained by filtration tends to retain solvents. The
complex was therefore dissolved in a small amount of dichloro-
methane (3 mL), carefully evaporated to dryness at reduced pres-
sure and dried under vacuum. Yield 155 mg (92%). 1H NMR (CDCl3):
serum (FBS) and antibiotics (100 IU/mL penicillin and 100 mg/mL
streptomycin (Gibco)) and kept in a CO2 incubator with 5% CO2 and
100% relative humidity at 37 ꢀC. Stock solutions of the complexes (in
DMSO) were diluted in complete medium to the required concen-
tration. DMSO at comparable concentrations did not show any ef-
fects on cell cytotoxicity.
For cytotoxicity screening, the cells were grown in 96-well cell
culture plates (SPL Lifesciences) at a density of 20e25 ꢃ 103 cells
per well. The culture medium was replaced with fresh medium
containing the complexes at concentrations varying from 0 to
d
1.34 (t, 3JHH ¼ 7.3 Hz, 9H, CH3 of Et3NHþ), 3.16 (q, 3JHH ¼ 7.3 Hz, 6H,
CH2 of Et3NHþ), 4.38 (virtual t, J z 2 Hz, 2H, fc), 4.44e4.48 (m, 4H,
fc and NHCH2), 4.75 (virtual t, J z 2 Hz, 2H, fc), 4.83 (virtual q,
3
J z 2 Hz, 2H, fc), 6.80 (br t, JHH z 6.3 Hz, 1H, NHCH2), 7.44e7.60
(m, 10 H, PPh2). 31P{1H} NMR (CDCl3):
d 28.7 (s). IR (Nujol): nNH
3281m, amide I 1648s, amide II 1537 s cmꢁ1. MS (ESIþ): m/z 800
([ClAu(Ph2PfcCONHCH2SO3)
þ
Na
þ
K]þ), 784 ([ClAu(Ph2Pfc
CONHCH2SO3) þ 2Na]þ), 726 ([M ꢁ Cl þ Na]þ). MS (ESIꢁ): m/z 738
30
was determined using the MTT test.
dimethyl-2-thiazoyl)-2,5-diphenyltetrazolium bromide (MTT,
m
M, with an exposure time of 72 h. Thereafter, cell survival
([ClAu(Ph2PfcCONHCH2SO3)]ꢁ). Anal. Calcd. for C30H37PFeO4N2
-
A
solution of 3-(4,5-
SAuCl: C 42.85, H 4.44, N 3.33%. Found: C 41.89, H 4.46, N 3.14%.
Merck; 5 mg mLꢁ1 in PBS; 20
mL per 200 mL of medium) was added
4.8. X-ray crystallography
to each well and incubation was continued for 2 h at 37 ꢀC. Then
the cell culture supernatants were removed, the cell layer was
dissolved in DMSO, and absorbance at 590 nm was measured in a
96-well microplate reader (Spectramax M5e, Molecular Devices,
Crystal data for 7: C26H24AuClFeNO3P, M ¼ 717.7, orange prism,
0.10 ꢃ 0.11 ꢃ 0.27 mm3, monoclinic, space group P21/c (no. 14),

J. Schulz et al. / Journal of Organometallic Chemistry 751 (2014) 604e609
609
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Appendix A. Supplementary material
_
[14] E. Hillard, A. Vessieres, F. Le Bideau, D. Plazuk, D. Spera, M. Huché, G. Jaouen,
CCDC 943699 and 943700 contain the supplementary crystal-
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ccdc.cam.ac.uk/data_request/cif.
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