Gram-positive organisms used in these tests. This range is com-
parable to the MIC values recorded against the related bac-
terium, Escherichia coli, for 10, which has itself indicated a
potential in vitro selectivity for Gram-positive bacteria.12 In
general the compounds show no antiviral activity since their
cytotoxicity killed most or all of the BSC-1 cell line used in the
test.
acid (124 mg, 0.805 mmol) and imidazole (600 mg, excess) in
methanol (25 mL) rapidly gave a clear, bright yellow solution.
After heating under reflux for 2 h the mixture was cooled
to room temperature, and the yellow precipitate filtered off,
washed with cold methanol (3 mL), water (5 mL), ethanol
(5 mL) and diethyl ether (2 × 5 mL), and dried. Yield 340 mg
(63%). Found: C, 49.5; H, 3.4; N, 4.2. C28H22N2O2PPtS requires
C, 49.7; H, 3.3; N, 4.1%. Mp 236–239 ЊC. 31P-{1H} NMR, δ 8.4
[s, 1J(PtP) 4196].
Experimental
Materials and methods
[Pd(SC6H4CO2)(PPh3)(py)] 4e. [PdCl2(cod)] (400 mg, 1.40
mmol), triphenylphosphine (366 mg, 1.40 mmol), thiosalicylic
acid (215 mg, 1.40 mmol) and pyridine (1 mL, excess) were
heated under reflux in methanol (30 mL) for 20 min. Evapor-
ation to ca. one-third gave orange crystals, which were filtered
off, washed with cold methanol (5 mL), water (10 mL), and
diethyl ether (10 mL) and vacuum dried to give 700 mg (84%) of
4e. Found: C, 60.0; H, 4.05; N, 2.3. C30H24NO2PPdS requires C,
60.1; H, 4.0; N, 2.3%. Mp 210–216 ЊC. 31P-{1H} NMR, δ 34.9
General experimental procedures and instrumentation were as
described previously.2 Electrospray mass spectra were recorded
in positive-ion mode in MeCN–H2O (1:1 v/v) solution (unless
otherwise stated), and ion assignment was aided by comparison
of experimental and calculated isotope patterns, the latter
obtained using the Isotope program.16 NMR spectra were
recorded in CDCl3 solution unless otherwise stated. The follow-
ing compounds were used as supplied from commercial sources:
pyridine (BDH), 4-methylpyridine (BDH), triphenylphosphine
(Pressure Chemical Co.), thiosalicylic acid (Sigma), 4-picolinic
acid hydrazide (Merck), imidazole (Aldrich). The compounds
[PtCl2(cod)],17 [PdCl2(cod)],18 2a–2d, 12 and 13 were synthesised
by the literature procedures.2 Assays for biological activity
were carried out by Gill Ellis of the Marine Chemistry Group,
University of Canterbury. Reactions were carried out in LR
grade methanol solvent, without exclusion of air.
(s), plus a small peak at δ 26.7 (s). IR, ν(C᎐O) 1592 (vs), 1570
᎐
(vs) cmϪ1
.
[Pt2(SC6H4CO2)2(PPh3)2(NH3)]ؒ1.5MeOH 5ؒ1.5MeOH.
A
mixture of [PtCl2(cod)] (101 mg, 0.270 mmol), PPh3 (71 mg,
0.271 mmol), thiosalicylic acid (41.8 mg, 0.271 mmol) and
conc. NH3 solution (10 drops, excess) in methanol (30 mL) was
heated at reflux for 20 min to give a pale yellow solution, and
the volume reduced to ca. one-third. ESMS showed the form-
Syntheses
ation of [Pt(SC6H4CO2)(PPh3)2] and some [Pt(SC6H4CO2)-
(PPh3)(NH3)], so the reaction was continued for 24 h with fresh
conc. NH3 (1 mL) and additional MeOH (20 mL). ESMS
[Pt(SC6H4CO2)(PPh3)(py)] 4a. A mixture of [PtCl2(cod)]
(605 mg, 1.616 mmol), triphenylphosphine (424 mg, 1.616
mmol), thiosalicylic acid 1 (249 mg, 1.616 mmol) and pyridine
(10 drops, excess) in methanol (30 mL) was heated under reflux
for 20 min giving a bright yellow solution. The volume was
reduced to one-third, refrigerated overnight, and the resulting
bright yellow microcrystals were filtered off, washed with
methanol (5 mL), diethyl ether (20 mL) and dried under
vacuum for 2 h to give 641 mg (58%) of 4a. From a separate
preparation, crystals of the monohydrate suitable for an X-ray
diffraction study were obtained. A sample for elemental
analysis was recrystallised from CH2Cl2–diethyl ether. Mp
230–232 ЊC (decomp.). Found: C, 52.1; H, 3.6; N, 2.1. C30H24-
NO2PPtS requires C, 52.3; H, 3.5; N, 2.0%. 31P-{1H} NMR,
again showed mainly [Pt(SC6H4CO2)(PPh3)2], together with
more [Pt(SC6H4CO2)(PPh3)(NH3)] and [Pt2(SC6H4CO2)2-
(PPh3)2(NH3)]. The volume was reduced to one-third, stored at
Ϫ18 ЊC for 2 days, whereupon some greenish-grey precipitate
was deposited. The solution was filtered and the filtrate allowed
to stand for 5 weeks. A small quantity of yellow plates (28 mg)
formed, and one was characterised as 5 by a single-crystal
X-ray diffraction study. The crystals appear to lose solvent
when air dried. Found: C, 46.7; H, 3.5; N, 1.3. C50H41NO4-
P2Pt2S2ؒ1.5MeOH requires C, 48.1; H, 3.6; N, 1.1%. Mp
decomp. >250 ЊC with gas evolution.
δ 10.0, [s, 1J(PtP) 4146]. IR, ν(C᎐O) 1596(vs), 1575(s, sh) cmϪ1
.
᎐
Crystallography
Crystal data, collection and refinement details are summarised
in Table 7. Non-routine features are as follows.
[Pt(SC6H4CO2)(PPh3)(Mepy)] 4b. Following the method for
4a, yellow crystals (75 mg, 40%) of 4b were obtained starting
from [PtCl2(cod)] (101 mg, 0.269 mmol), triphenylphosphine
(71 mg, 0.269 mmol), thiosalicylic acid (42 mg, 0.269 mmol)
and 4-methylpyridine (10 drops, excess). Mp >230 ЊC
(decomp.). Found: C, 50.5; H, 3.7; N, 1.9. C31H26NO2PPtS
requires C, 53.0; H, 3.7, N, 2.0%. C31H26NO2PPtSؒ2H2O
requires C, 50.4; H, 4.1; N, 1.9%. NMR: 31P-{1H}, δ 9.9 [s,
Structure determination of [Pt(SC6H4CO2)(PPh3)(py)]ؒH2O
4aؒH2O. Data were collected to 56Њ but the higher angle data
were very weak because of the small crystal size, so only the
data below 48Њ were used in the refinement. Refinement was
complicated by disorder of the pyridine ring, which was
modelled as two half-occupied sites with isotropic thermal
parameters. Both disordered components were co-planar,
one displaced upwards and one downwards with respect to
the platinum coordination plane. There was also concomitant
disorder of the carboxylate part of the thiosalicylate ligand, but
this was less pronounced so was absorbed into the aniso-
tropy of the atoms in this region. A penultimate difference map
revealed a double peak assigned as a disordered water of
crystallisation H-bonded to the free O(2) of the thiosalicylate
ligand. Hydrogen atoms were included in their calculated
positions only for the phenyl and thiosalicylate rings.
1J(PtP) 4160]. IR, ν(C᎐O) 1618(s, sh), 1591(vs) cmϪ1
.
᎐
[Pt(SC6H4CO2)(PPh3)(pic)] 4c. A mixture of [PtCl2(cod)]
(300 mg, 0.802 mmol), PPh3 (210 mg, 0.802 mmol), thiosalicylic
acid (124 mg, 0.805 mmol) and 4-picolinic acid hydrazide (pic)
(600 mg, excess) in methanol (20 mL) was heated under reflux
for 20 min giving a clear deep yellow solution. After cooling
and standing overnight yellow microcrystals had formed, which
were filtered off, washed with methanol–water (1:1, 15 mL) and
dried to give 4c (200 mg, 33%). Found: C, 49.2; H, 3.5; N, 5.65.
C31H26N3O3PPtS requires C, 49.9; H, 3.5; N, 5.6%. Mp 230–
234 ЊC. 31P-{1H} NMR, δ 9.8 [s, 1J(PtP) 4201].
Structure determination of [Pt(SC6H4CO2)(PPh3)(XyNC)]ؒ
Me2CO 7ؒMe2CO. The complex was prepared as a mixture
of cis/trans isomers (7 is the major isomer) by the literature
[Pt(SC6H4CO2)(PPh3)(imid)] 4d. A mixture of [PtCl2(cod)]
(300 mg, 0.802 mmol), PPh3 (210 mg, 0.802 mmol), thiosalicylic
J. Chem. Soc., Dalton Trans., 2000, 2753–2760
2759
Henderson, William
