30
H. Chiririwa et al. / Polyhedron 49 (2013) 29–35
tumour cells [17–20]. Auranofin itself has proved cytotoxic against
HeLa cells in vitro and P388 leukaemia cells in vivo [21,22]. Recent
advances in medicinal inorganic chemistry demonstrate significant
prospects for the utilization of Au(I) and Au(III) and their coordina-
tion complexes as drugs, presenting an interesting arena for inor-
ganic chemistry. Significant progress in gold based anticancer
agents has been achieved, based in part on a mechanistic under-
standing of the pharmacological effects of classical antitumor
drugs. There are quite a number of results indicating that gold
coordination compounds might be developed into future drugs,
but it will be a long time before their pharmacological potential
can be realised. It will take even longer to have a suitable candidate
turned into a clinically acceptable drug. The future development of
medicinal inorganic chemistry of Au(I) and Au(III) and their coordi-
nation complexes requires an understanding of the physiological
processing of gold complexes, to provide a rational basis for the de-
sign of new gold-based drugs.
2.3.2. Spectroscopic and analytical data for 1
Yellow powder. Yield: 76%. M.p.: 201–203 °C. Anal. Calc. for C31-
H32Cl2NPPt: C, 52.03; H, 4.51; N, 1.96. Found: C, 52.19; H, 4.74; N,
1.99%. MS (EI, m/z): 678.34, [MÀCl]+. IR (KBr) (
m
max/cmÀ1): 1624 s
m
(C N). 1H NMR (CDCl3): dH (ppm): 8.95 (d, 1H, J = 111.3 Hz) 8.18
(dd, 1H, J = 4.2 Hz, J = 9.0 Hz) 7.90 (m, 2H) 7.60 (m, 10H) 7.18 (m,
4H) 3.01 (m, 2H) 1.24 (d, 6H, J = 6.8 Hz) 0.83 (d, 6H, J = 6.8 Hz).
31P NMR (CDCl3; ppm) 5.83 [J (195Pt–31P): 3661 Hz].
2.3.3. Spectroscopic and analytical data for 2
Light yellow powder. Yield: 65%. M.p.: 180–183 °C. Anal. Calc.
for C26H22Cl2NPPt: C, 48.38; H, 3.44; N, 2.17. Found: C, 48.19; H,
3.12; N, 2.47%. MS (EI, m/z): 609.36, [MÀCl]+. IR (KBr) (mmax
/
cmÀ1): 1632 s (C N). 1H NMR (CDCl3): dH (ppm): 7.79 (m, 1H)
m
7.60 (t, 1H, J = 7.4 Hz) 7.47 (t, 1H, J = 7.4 Hz) 7.07 (t, 1H,
J = 8.6 Hz) 6.90 (t, 1H, J = 7.7 Hz) 6.49 (d, 1H, J = 7.2 Hz) 4.13 (t,
1H, J = 12.8 Hz). 31P NMR (CDCl3; ppm) 8.09 [J
(
195Pt–31P):
Here we report the synthesis and characterisation of novel plat-
inum(II) and gold(I) complexes with iminophosphine ligands and
the examination of their cytotoxic properties.
3668 Hz].
2.3.4. Spectroscopic and analytical data for 3
Yellow powder. Yield: 76%. M.p.: 168–169 °C. Anal. Calc. for C25-
H21Cl2N2PPt: C, 46.45; H, 3.27; N, 4.33. Found: C, 46.19; H, 3.12; N,
4.72%. MS (EI, m/z): 610.91, [MÀCl]+. IR (KBr) (
m
max/cmÀ1): 1630 s
2. Experimental
m
(C N). 1H NMR (CDCl3): dH (ppm): 9.19 (m, 1H) 8.64 (m, 1H)
8.53 (d, 1H, J = 4.3 Hz) 8.05 (dd, 1H, J = 4.1 Hz, J = 6.9 Hz) 7.92 (t,
1H, J = 7.5 Hz) 7.84 (t, 1H, J = 7.4 Hz) 7.60 (m, 2H) 7.41 (m, 3H)
7.09 (m, 5H) 5.80 (d, 2H, J = 18.7 Hz). 31P NMR (CDCl3; ppm) 8.44
[J (195Pt–31P): 3469.9 Hz].
2.1. Materials
All solvents were purified prior to use by standard literature
procedures and were stored under nitrogen in Teflon sealed stor-
age bottles. All reagents were purchased from Aldrich and used
without further purification. The ligands L1–L5 [23], [PtCl2(COD)]
[24,25], [PtCl2(DMSO)2] [26–28] and [Au(tht)Cl] [29] were pre-
pared as described in the literature.
2.3.5. Spectroscopic and analytical data for 4
Dark yellow powder. Yield: 72%. M.p.: 198–199 °C. Anal. Calc.
for C24H20Cl2NOPPt: C, 48.83; H, 3.77; N, 2.28. Found: C, 48.69;
H, 3.52; N, 2.52%. MS (EI, m/z): 599.91, [MÀCl]+. IR (KBr) (mmax
/
cmÀ1): 1633 s (C N). 1H NMR (CDCl3): dH (ppm): 9.06 (m, 1H)
m
8.02 (m, 1H) 7.88 (td, 2H, J = 7.4 Hz, J = 19.3 Hz) 7.60 (t, 2H,
J = 7.2 Hz) 7.49 (t, 4H, J = 6.4 Hz) 7.22 (ddd, 6H, J = 15.4 Hz,
J = 23.5 Hz, J = 30.5 Hz) 6.55 (m, 2H) 5.80 (d, 2H, J = 13.0 Hz). 31P
NMR (CDCl3; ppm) 5.66 [J (195Pt–31P): 3777.6 Hz].
2.2. Physical measurements
1H NMR spectra were recorded in DMSO-d6 at room tempera-
ture on either a Varian Mercury-300 or a Varian Unity-400 spec-
trometer operating at 300.13 and 75.5 MHz or 400.13 and
100.6 MHz. Chemical shifts are reported relative to TMS on delta
(d) scale in parts per million (ppm). The splitting of proton reso-
nances in the reported 1H NMR spectra are defined as s = singlet,
d = doublet, t = triplet, m = multiplet, w = weak and br broad. Melt-
ing points were determined on a Reichert-Jung Thermovar hot-
stage microscope and are uncorrected. Infrared spectra (KBr
pellets) were recorded on a Thermo Nicolete FT-IR instrument
and are reported using the following abbreviation: s = strong,
m = medium, strong and br = broad. Microanalyses were deter-
mined using a Fisons EA 1108 CHNO-S instrument. Mass spectra
(MS) were recorded on a Waters atmosphere pressure ionization
quadruple time-of-flight (API Q-TOF) Ultima (electronspray ioniza-
tion (ESI), 70 eV) and/or SA VG70-SEQ (Fast atom bombardment
(FAB), 7 kV) instrument.
2.3.6. Spectroscopic and analytical data for 5
Pale yellow powder. Yield: 72%. M.p.: 201–203 °C. Anal. Calc. for
C
24H20Cl2NPPtS: C, 44.25; H, 3.09; N, 2.15; S, 4.92. Found: C, 44.19;
H, 3.12; N, 2.42; S, 5.03%. MS (EI, m/z): 616.01, [MÀCl]+. IR (KBr)
(m m
max/cmÀ1): 1631 s (C N). 1H NMR (CDCl3): dH (ppm): 8.73 (s,
1H) 7.86 (m, 1H) 7.60 (m, 1H) 7.44 (m, 1H) 7.24 (dd, 1H,
J = 1.2 Hz, J = 5.1 Hz) 7.06 (ddd, 1H, J = 1.6 Hz, J = 7.2 Hz,
J = 10.6 Hz) 6.77 (dd, 1H, J = 3.4 Hz, J = 5.1 Hz) 6.50 (dd, 1H,
J = 1.0 Hz, J = 3.4 Hz) 4.77 (t, 1H, J = 7.4 Hz). 31P NMR (CDCl3;
ppm) 8.06 [J (195Pt–31P): 3758.5 Hz].
2.3.7. General procedure for the preparation of gold(I) complexes (6–
9)
To the appropriate ligand (L1, L3–L5) in dry CH2Cl2 (10 ml) was
added [Au(tht)Cl] also in dry CH2Cl2 (10 ml) in a ratio of 1:0.9. The
reaction was allowed to stir at room temperature for ca 2 h before
reducing the solvent to ca 5 ml and precipitating out the products
with hexane, filtering under gravity and washing the precipitate
with dry Et2O and drying under vacuum for 4 h.
2.3. Synthesis
2.3.1. General procedure for the preparation of platinum(II) complexes
(1–5)
2.3.8. Spectroscopic and analytical data for 6
To a solution of the appropriate ligand (L1–L5) in dry CH2Cl2
(10 ml) was added an equimolar amount of [PtCl2(COD)] or PtCl2
(DMSO)2] dissolved in dry CH2Cl2 (10 ml). The reaction was allowed
to stir at room temperature for 4 h before reducing the solvent to ca
5 mland precipitating theproductsusinghexane. Theproducts were
filtered, washed with Et2O and dried under vacuum.
Pale yellow powder. Yield: 73%. M.p.: 200–201 °C. Anal. Calc. for
C
31H32AuClNP: C, 54.60; H, 4.73; N, 2.05. Found: C, 54.88; H, 4.57;
N, 1.97%. MS (EI, m/z): 449.31, [MÀClÀAu]+. IR (KBr) (
m
max/cmÀ1):
1628 s m
(C N). 1H NMR (CDCl3): dH (ppm): 8.90 (s, 1H) 8.41 (dd,
1H, J = 4.5 Hz, J = 7.2 Hz, ArH) 7.60 (t, 1H, J = 7.5 Hz, ArH) 7.41 (m,
11H, ArH) 6.94 (m, 3H, ArH) 6.79 (dd, 1H, J = 7.8 Hz, J = 13.2 Hz)