R.B. Sutton and W. Henderson
Inorganica Chimica Acta 506 (2020) 119557
, 162 MHz) s, −53.2 ppm, J(PtP)
92%). 31P{ H} NMR (DMSO‑d
1
1
(
6
3307 Hz.
4.4. Synthesis of crude [Pt
2
(µ
2
-S)
2
(PTA)
4
]
A
modified literature method for the synthesis of [Pt
(PPh ] was used [19]. A mixture of cis-[PtCl (PTA) ] (0.418 g,
S·9H O (0.86 g, 3.5 mmol) in a benzene suspension
10 mL) was continually stirred for 48 h. The suspended solids collected
2 2
(µ -
S)
0
(
2
3
)
4
2
2
.72 mmol) and Na
2
2
in the bottom of the flask, as a light brown paste. After collection of the
solid by filtration and washing with benzene (5 mL), no further pur-
3
1
ification attempts were made. The solid was dried under vacuum.
P
1
1
{
2
H} NMR (D O): s, −54.3 ppm, J(PtP) 2616 Hz.
In a repeated synthesis, the solid was collected by filtration, and
attempted purification was investigated, to preferentially dissolve the
present sodium salts in MeOH. This led to the partial decomposition of
[
2 2 2 4
Pt (µ -S) (PTA) ] while in solution.
Fig. 7. Part of the positive-ion ESI mass spectrum of [Pt
2
2 2 4
(μ -S) (PTA) ] formed
4
.5. Attempted synthesis of [Pt
2 2 2 4
(µ -S) (PTA) ] using a sulfide exchange
via ligand exchange between [Pt
2 2 2 2
(μ -S) (cod) ] and PTA. Capillary exit voltage
column
150 V, MeOH/water (2:5) solution.
A small column was prepared from a glass pasteur pipette con-
taining a small plug of glass wool and Dowex® 1X8 beads (4 cm deep).
The column was washed with distilled water (15 mL) followed by
methanol (15 mL). The eluent was discarded. A solution of Na S·9H O
(200 mg) in methanol (10 mL) was passed down the column (producing
a colour change from orange to brown). The column was further wa-
shed with methanol until a fresh sample of the eluate was clear when
tested with a drop of aqueous lead nitrate solution. If the eluent formed
a black precipitate of PbS, further washing was needed (washing with
10 mL of methanol was needed).
[
Pt
2
(µ
2
-S)
2
(PTA)
(µ -S)
4
] have been explored, with varying degrees of success.
(PTA) ] can be synthesised, it was not possible to
While [Pt
2
2
2
4
obtain it in a pure state, with PTA-oxide and -sulfide observed ubiqui-
tously in these systems. Accordingly, the current study employed
spectroscopic tools, since it was considered that elemental analyses
were not appropriate. However, the combination of ESI mass spectro-
metry, coupled with P{ H} NMR spectroscopy, is a powerful set of
tools for investigating this chemistry. This study suggests that while
PTA offers some attractive features, it is not the best choice of water-
2
2
3
1
1
solubilising ligand in {Pt
profitably directed towards water-soluble analogues of PPh
in this context, sulfonated triphenylphosphine ligands have been shown
to find considerable utility [42].
2
S
2
} chemistry. Instead, studies might be
itself, and
A solution of cis-[PtCl (PTA) ] (0.01 g, 0.02 mmol) in methanol
2
2
3
(15 mL) was passed down the column, followed by methanol (15 mL).
The eluate was collected and evaporated to dryness using a rotary
evaporator, producing a white solid that was shown by ESI MS to
2
+
31
1
1
contain [Pt
3
(µ
3
-S)
2
(PTA)
6
]
.
2
P{ H} NMR (D O): s, −60.3 ppm, J
2+
4. Experimental
(PtP) 3041 Hz. ESI MS: m/z 795.78, [M]
.
4.1. Materials
2 3 2 4
4.6. Synthesis of [Pt (µ -S) (PTA) Rh(cod)]Cl
Sodium sulfide nonahydrate (Aldrich) and Dowex® 1X8 ion ex-
2 3
A modified literature method [33] for the synthesis of [Pt (µ -
change resin beads (BDH) were used as supplied from commercial
sources. The following compounds were prepared by the literature
2 3 4 2 2 2 4
S) (PPh ) Rh(cod)]Cl was used: crude [Pt (µ -S) (PTA) ] (0.054 g,
0.05 mmol) was reacted with [RhCl(cod)] (0.0123 g, 0.02 mmol) using
2
procedures: PTA [18], [RhCl(cod)]
2
[43], [PtCl
2
(cod)] [44] and
methanol (60 mL) in place of THF. After stirring for 1 h, the resulting
[
Pt (µ -S) (PPh ] [21]. Reactions were carried out in LR grade sol-
2
2
2
3
)
4
mixture was filtered to remove some precipitate. The maroon filtrate
vents, without regard for exclusion of air or moisture unless otherwise
stated.
was evaporated to dryness using a rotary evaporator, resulting in the
3
1
1
deposition of [Pt (µ -S) (PTA) Rh(cod)]Cl as a maroon solid. P{ H}
2
3
2
4
1
2
NMR (D O): s, −56.8 ppm, J(PtP) 2965 Hz. ESI MS: m/z 1293.08,
+
4.2. Instrumentation
[M]
.
Unless otherwise stated, 31P{ H} NMR spectra were recorded at
1
4.7. Attempted synthesis of [Pt (µ -S) (PTA) ] via ligand exchange
2
2
2
4
1
13
1
21.5 MHz on a Bruker Avance DRX 300 spectrometer. H and C NMR
spectra were recorded on a Bruker Avance DRX 400 MHz spectrometer.
ESI mass spectra were recorded on Bruker MicrOTOF instrument with
the Skimmer 1 Voltage a third that of the Capillary Exit Voltage (CEV).
Spectra routinely used a CEV of 150 V. Samples were diluted with
2 2 2 3 4
A mixture of [Pt (µ -S) (PPh ) ] (0.04 g, 0.026 mmol) and PTA
(0.016, 0.106 mmol) in distilled water (20 mL) and toluene (20 mL)
were stirred continuously for 7 days in a capped glass vial. The spar-
ingly soluble, orange [Pt (µ -S) (PPh ) ] floated in the aqueous phase
2
2
2
3 4
−1
methanol prior to analysis, and injected with a flow rate of 180 µL h
and around the phase boundary. The reaction was simultaneously re-
by means of a syringe pump. Mass spectra data processing software
used to generate figures and calculated isotope patterns was mMass
version 5.5.0 [45,46].
peated with [Pt (µ -S) (PPh ) ] to PTA molar ratios of 1:1, 1:2 and 1:3.
The phases were allowed to separate, before samples of the aqueous
phase were taken for positive-ion ESI MS analysis
2
2
2
3 4
4.3. Synthesis of cis-[PtCl
2
(PTA)
2
]
4.8. Synthesis of PTA sulfide
The complex was prepared using the literature method [22], from
PtCl (cod)] (0.967 g, 2.5 mmol) and PTA (0.813 g, 5.1 mmol); the
reaction was performed under a nitrogen atmosphere. Yield 1.38 g
PTA sulfide was first synthesised by Daigle and Pepperman in 1975
[47], through reaction of PTA with elemental sulfur, though the pro-
duct was only characterised by IR. A modification of this method is used
[
2
6
Sutton, Ryan B.
