Heterobimetallic platinum-bismuth aggregates derived from [Pt 2(μ-S)2(PPh3)4]

Article abstract of DOI:10.1016/j.ica.2005.07.022

The metalloligand [Pt₂(μ-S)₂(PPh₃) ₄] reacts with Bi(S₂CNEt₂)₃ or Bi(S₂COEt)₃ in methanol to produce the orange cationic adducts [Pt₂(μ-S)₂(PPh₃) ₄Bi(S₂CNEt₂)₂]⁺ and [Pt₂(μ-S)₂(PPh₃)₄Bi(S ₂COEt)₂]⁺, respectively, isolated as their hexafluorophosphate salts. An X-ray structure determination on [Pt ₂(μ-S)₂(PPh₃)₄Bi(S ₂CNEt₂)₂]PF₆ reveals the presence of a six-coordinated bismuth centre with an approximately nido-pentagonal bipyramidal coordination geometry. Fragmentation pathways for both complexes have been probed using electrospray ionisation mass spectrometry; ions [Pt ₂(μ-S)₂(PPh₃)₂Bi(S ₂CXEt_n)₂]⁺ (X = O, n = 1, X = N, n = 2) are formed by selective loss of two PPh₃ ligands, and at higher cone voltages the species [(Ph₃P)PtS₂Bi]⁺ is observed. Ions formed by loss of CS₂ are also observed for the xanthate but not the dithiocarbamate ions.

Full text of DOI:10.1016/j.ica.2005.07.022

Inorganica Chimica Acta 359 (2006) 221–227
www.elsevier.com/locate/ica
Heterobimetallic platinum–bismuth aggregates derived from
[Pt2(l-S)2(PPh3)4]
a,
a
a
,b
*
William Henderson *, Brian K. Nicholson , Hao Zhang , T.S. Andy Hor
a
Department of Chemistry, University of Waikato, Private Bag 3105, Hamilton, New Zealand
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
b
Received 15 June 2005; accepted 16 July 2005
Available online 31 August 2005
Abstract
The metalloligand [Pt2(l-S)2(PPh3)4] reacts with Bi(S2CNEt2)3 or Bi(S2COEt)3 in methanol to produce the orange cationic
adducts [Pt2(l-S)2(PPh3)4Bi(S2CNEt2)2]+ and [Pt2(l-S)2(PPh3)4Bi(S2COEt)2]+, respectively, isolated as their hexafluorophosphate
salts. An X-ray structure determination on [Pt2(l-S)2(PPh3)4Bi(S2CNEt2)2]PF6 reveals the presence of a six-coordinated bismuth
centre with an approximately nido-pentagonal bipyramidal coordination geometry. Fragmentation pathways for both complexes
have been probed using electrospray ionisation mass spectrometry; ions [Pt2(l-S)2(PPh3)2Bi(S2CXEtn)2]+ (X = O, n = 1, X = N,
n = 2) are formed by selective loss of two PPh3 ligands, and at higher cone voltages the species [(Ph3P)PtS2Bi]+ is observed. Ions
formed by loss of CS2 are also observed for the xanthate but not the dithiocarbamate ions.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Platinum complexes; Sulfide complexes; Bismuth complexes; X-ray crystal structure; Electrospray ionisation mass spectrometry
1. Introduction
on a micro-scale, using electrospray ionisation mass
spectrometry (ESI MS). This has been successfully used
in a range of systems [2–8].
The sulfido complex [Pt2(l-S)2(PPh3)4] has been
known for many years to contain highly nucleophilic
sulfide centres that interact with organic and metal-
based electrophiles [1]. By reaction with metal electro-
philes – typically metal salts or coordination complexes
containing labile anionic ligands such as halides – sul-
fide-bridged homo- and heterobimetallic aggregates re-
sult. The ability to attach a wide range of metal
fragments to the {Pt2S2} core has the potential to tailor
the properties of the resulting aggregate, for example to
produce species with unusual structures, or with redox
activity. We have been developing a mass spectrometry-
based approach, whereby the reactivity of [Pt2(l-S)2-
(PPh3)4] and the selenium analogue [Pt2(l-Se)2(PPh3)4]
towards various metal complexes is carried out rapidly,
Relatively little work has been carried out on the
chemistry of main group derivatives of the {Pt2S2} core,
though some heterobimetallic aggregates of lead(II) [9],
indium(III) and gallium(III) [10], and thallium(I) [11]
have been prepared. Some of these derivatives have
novel structures and have been the subject of a theoret-
ical study [12]. The related derivative [Pt2(l-S)2-
(dppf)2] [dppf = 1,10-bis(diphenylphosphino)ferrocene]
also forms thallium(I), indium(III) and lead(II) deriva-
tives [13].
In the area of bismuth chemistry, earlier studies indi-
cated that adducts with this metal can be synthesised.
Reaction of [Pt2(l-S)2(PPh3)4] with BiCl3 gave [Pt2-
(l-S)2(PPh3)4BiCl3] which on metathesis with NH4PF6
produced [Pt2(l-S)2(PPh3)4BiCl2]PF6 [14]. [Pt2(l-S)2-
(PPh3)4- BiCl3] undergoes chloride dissociation followed
by addition of a second equivalent of [Pt2(l-S)2(PPh3)4]
*
Corresponding author. Fax: +64 7 838 4219.
E-mail address: w.henderson@waikato.ac.nz (W. Henderson).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.07.022

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W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
to give the bis-adduct [{Pt2(l-S)2(PPh3)4}2BiCl2]Cl and
other Bi species such as [{Pt2(l-S)2(PPh3)4}2BiCl]Cl2
are detected in solution [15]. Given the strong affinity
of the heavy main group metals (particularly bismuth)
for sulfur ligands, we reasoned that [Pt2(l-S)2(PPh3)4]
should form derivatives with sulfur-ligand bismuth pre-
cursors. Such sulfur-rich derivatives of the {Pt2S2} core
are hitherto unknown, and the utility of bismuth-dithio-
carbamate and -xanthate complexes as precursors to
solid-state bismuth sulfide materials [16] suggests that
the heterobimetallic systems might likewise provide a
potential route to novel mixed-metal-sulfide phases. In
this paper we describe the synthesis and characterisation
of such sulfur-rich heterobimetallic Pt–Bi aggregates,
using our methodology of mass spectrometry-directed
synthesis to screen for promising systems, and to charac-
terise reaction products.
byproduct [Pt(S2CNEt2)(PPh3)2]+ observed. For the
reaction with excess Bi(S2CNEt2)3, ions derived from
the starting bismuth dithiocarbamate complexes were
also seen, namely [Bi(S2CNEt2)2]+ (m/z 505) and [Bi2(S2-
CNEt2)5]+ (m/z 1158), together with a trace of the chloro
complex described above. Fig. 1 shows positive-ion ESI
mass spectra for 1:1 and 1:2 mole ratios of [Pt2-
(l-S)2(PPh3)4] with Bi(S2CNEt2)3, after a reaction time
of 10 min. With a 2:1 mole ratio of [Pt2(l-S)2(PPh3)4] to
Bi(S2CNEt2)3, the adduct [Pt2(l-S)2(PPh3)4Bi(S2C-
NEt2)2]+ again dominated the spectrum, demonstrating
the tendency to form this product species irrespective of
the reaction stoichiometry; no species with two {Pt2S2}
moieties coordinated to a single bismuth were observed
in this experiment. As expected, unreacted [Pt2(l-S)2-
(PPh3)4] was observed (as its [M + H]+ ion), together with
the usual byproduct ion [Pt(S2CNEt2)(PPh3)2]+ and some
minor unidentified species.
Because it was believed that the liberated dithiocarba-
mate or xanthate ligands might be responsible for the
formation of the mono-platinum byproducts, an exper-
iment was carried out to try and minimise liberation
of the sulfur ligand, by generation of a Bi starting com-
plex with only 2 mol. equiv. of dithiocarbamate per Bi.
Reaction of BiBr3 with 2 equiv. of Bi(S2CNEt2)3 was
firstly carried out, followed by addition of the stoichi-
2. Results and discussion
2.1. Scoping study using ESI mass spectrometry
ESI mass spectrometry has been used to screen the
reactivity of [Pt2(l-S)2(PPh3)4] towards the bismuth
complexes Bi(S2CNEt2)3 and Bi(S2COEt)3, containing
bidentate dithiocarbamate and xanthate donor ligands.
Intensely yellow solutions were rapidly produced, which
showed primarily the adducts [Pt2(l-S)2(PPh3)4Bi-
(S2CNEt2)2]+ (m/z 2008) and [Pt2(l-S)2(PPh3)4Bi-
(S2COEt)2]+ (m/z 1954), respectively. In each case
a significant byproduct was formed, identified by
characteristic m/z values and isotope patterns as the
mononuclear complexes [Pt(S2CNEt2)(PPh3)2]+ and
[Pt(S2COEt)(PPh3)2]+ at m/z 867 and 840, respectively.
For the dithiocarbamate reaction, an additional low
intensity species was identified as the chloro complex
[Pt2(l-S)2(PPh3)4Bi(S2CNEt2)Cl]+ (m/z 1895), most
likely from the presence of chloride-containing impuri-
ties in the bismuth complex(es), whose synthesis
involved dissolution of bismuth(III) nitrate in hydro-
chloric acid, followed by addition of the dithiocarba-
mate or xanthate salt [16].
The formation of the mononuclear species [Pt(S–
S)(PPh3)2]+ (S–S = bidentate dithiocarbamate or xan-
thate) presumably arises from the product cations
[Pt2(l-S)2(PPh3)4M(S–S)2]+; these trinuclear cations
may be susceptible to attack by the liberated dithio li-
gand, causing breakup of the trinuclear aggregate. In
an attempt to minimise the formation of these mononu-
clear byproducts, the reactions of [Pt2(l-S)2(PPh3)4] with
1 and 2 mol. equiv. of Bi(S2CNEt2)3 were monitored by
ESI MS. After 10 min and 16 h reaction times, the ob-
served ions for the different stoichiometries were remark-
ably similar, with [Pt2(l-S)2(PPh3)4Bi(S2CNEt2)2]+ being
the base peak in both cases, and similar amounts of
ometric quantity of [Pt2(l-S)2(PPh3)4] to give
a
{Pt2S2}:Bi ratio of 1:1. However, the ESI mass spectrum
of the resulting reaction mixture again showed a mixture
of the desired {Pt2S2Bi} adduct, and [Pt(S2CNEt2)-
(PPh3)2]+. Slow addition of a solution/suspension of
Bi(S2CNEt2)3 to a stirred suspension of [Pt2(l-S)2
(PPh3)4] in methanol did also not eliminate the forma-
tion of [Pt(S2CNEt2)(PPh3)2]+.
2.2. Macroscopic syntheses and spectroscopic
characterisation
The bismuth adducts [Pt2(l-S)2(PPh3)4Bi(S2CNEt2)2]+
and [Pt2(l-S)2(PPh3)4Bi(S2COEt)2]+ were subsequently
synthesised on the macroscopic scale. Products were iso-
lated by addition of excess NH4PF6 to the filtered reaction
solutions, giving the salts [Pt2(l-S)2(PPh3)4Bi(S2C-
NEt2)2]PF6 (1) and [Pt2(l-S)2(PPh3)4Bi(S2COEt)2]PF6
(2) as bright orange solids. The isolated products con-
tained small traces of the mononuclear platinum-dithio-
late species [Pt(S2CNEt2)(PPh3)2]+.
The complexes show a single resonance in the 31P–
{1H} NMR spectrum showing coupling to 195Pt
(J = 3023 Hz for 1 and 3087 Hz for 2), and the 1H
NMR spectra shows the expected resonances due to
PPh3 ligands and ethyl groups of the dithiocarbamate
or xanthate ligands. Complex 2 was unstable in chloro-
form solution, undergoing partial decomposition to a
1
species at d 4.2 showing J(PtP) 3361 Hz, assigned to

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
223
Fig. 1. Positive-ion ESI mass spectra for the reaction between [Pt2(l-S)2(PPh3)4] and Bi(S2CNEt2)3 in methanol at a cone voltage of 20 V, after a
reaction time of 10 min: (a) {Pt2S2}:Bi mole ratio = 1:1; and (b) {Pt2S2}:Bi mole ratio = 1:2.
[Pt(S2COEt)(PPh3)2]+, as well as a small peak at d ꢀ5
tentatively assigned as free PPh3. The ESI mass spec-
trum of the chloroform solution, after dilution with
methanol, also showed an enhanced peak due to
[Pt(S2COEt)(PPh3)2]+.
wide range of fragment ions are observed, and all
can be identified. Loss of one and two CS2 from the
parent ion gives low intensity ions at m/z 1878 and
1802, presumably forming ions with Bi-OEt groups.
An ion at m/z 1429 is formed by loss of two PPh3 li-
gands from the parent cation, but interestingly the
ion formed by loss of one PPh3, expected at m/z
1692, was not observed. The corresponding CS2-loss
ion [Pt2S2(PPh3)2Bi(S2COEt)- (OEt)]+ is also observed
as a low intensity ion at m/z 1353. At a cone voltage
of 90 V, the base peak in the spectrum occurs at m/z
992, and analysis of its isotope distribution pattern re-
veals the characteristic pattern of a mono-platinum spe-
cies. This species is tentatively identified as
[(Ph3P)PtS2Bi]+, which gives a good match of calcu-
lated and experimental isotope patterns. The observa-
tion of this species suggests that the {Pt2S2Bi} core
has fragmented by loss of a platinum centre, and that
the Bi–S bonds are strong. Other ions observed in
the spectrum at 90 V are [Pt(S2COEt)(PPh3)2]+ (m/z
840), the (frequently observed) [17] cyclometallated
species [Pt(Ph2PC6H4)(PPh3)]+ (m/z 718), and
[Pt(S2COEt)(PPh3)]+ (m/z 578). Upon allowing the
(pale yellow) analyte solution to stand overnight, it
turned brown and the species observed in the ESI mass
spectrum changed dramatically (Fig. 2(c)) with the base
peak being the mono-platinum species [Pt(S2CO-
Me)(PPh3)2]+ at m/z 826. This is formed by decompo-
sition of the parent cation and exchange of the OEt
OEt
NEt2
+
+
S
Bi
S
S
Bi
S
Ph3P
Ph3P
S
S
S
S
S
S
Ph3P Pt
Ph3P Pt
Ph3P Pt
Ph3P Pt
-
-
PF6
PF6
S
S
Ph3P
Ph3P
OEt
NEt2
2
1
The ESI MS behaviour of complexes 1 and 2 was
investigated using a range of cone voltages to effect
fragmentation; there are similarities and differences be-
tween the two complexes. A freshly prepared solution
of 2 in dichloromethane-methanol at a low cone volt-
age (20 V; Fig. 2(a)) shows predominantly the parent
cation together with a trace of the mononuclear
byproduct [Pt(S2COEt)(PPh3)2]+ as discussed earlier.
The parent cation remains the dominant base peak
up to a cone voltage of at least 60 V. At higher cone
voltages fragment ions dominate the spectra, as illus-
trated by the spectrum at 90 V shown in Fig. 2(b). A

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W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
Fig. 2. Positive-ion ESI mass spectra of the complex [Pt2(l-S)2(PPh3)4Bi(S2COEt)2]PF6 (2) in dichloromethane-methanol solution: (a) at a cone
voltage of 20 V; (b) at a cone voltage of 90 V; (c) at 20 V after standing the analyte solution overnight. The peak marked * is the cyclometallated
phosphine ion [Pt(Ph2PC6H4)(PPh3)]+.
group of the xanthate ligand with the methanol sol-
vent. Close examination of the spectrum in Fig. 2(b)
reveals that corresponding methoxy analogues are ob-
served as low intensity companions for the majority
of species, but importantly not for [(Ph3P)PtS2Bi]+
(m/z 992) nor [Pt(Ph2PC6H4)(PPh3)]+ (m/z 718), consis-
tent with their formulations.
Overall the major features observed for the dithiocar-
bamate complex 1 at a range of cone voltages are similar
to those of the xanthate complex 2. The base peak at
low to moderate cone voltages (up to 70 V) is the parent
cation, and a trace of the byproduct [Pt(S2CNEt2)-
(PPh3)2]+ was observed at m/z 867. The major fragment
ion, observed as the base peak at 90 V is also the ion
formed by loss of two PPh3 ligands, i.e., [Pt2S2(PPh3)2-
Bi(S2CNEt2)2]+ observed at m/z 1483. At even higher
cone voltages, the species [(Ph3P)PtS2Bi]+ at m/z 992
became prominent, and was the base peak at 110 V.
However, the major difference between the xanthate
and dithiocarbamate systems is that no ions formed by
loss of CS2 were observed from the dithiocarbamate
system.
When the spectrum of 2 was recorded at a very low cone
voltage (3 V), no additional higher m/z ions formed by
addition of methanol were observed. Similarly, addition
of neither pyridine nor 2,20-bipyridine to the sample re-
sulted in additional ions. These observations suggest that
the bismuth centre is effectively coordinatively saturated
and shows no tendency to expand its coordination number.
In contrast, addition of sodium diethyldithiocarbamate to
[Pt2(l-S)2(PPh3)4Bi(S2COEt)2]PF6 2 resulted in immediate
conversion to the bis(dithiocarbamate) [Pt2(l-S)2(PPh3)4-
Bi(S2CNEt2)2]+ as the base peak at m/z 2008.
2.3. X-ray crystal structure of [Pt2(l-S)2(PPh3)4-
Bi(S2CNEt2)2]PF6 (1)
An X-ray structure determination was carried out in
order to determine the coordination geometry around
the bismuth centre in 1. The complex consists of a
BiðS2CNEt2Þ2þ fragment coordinated to the {Pt2S2} core,
generating a BiS6 coordination environment, as illus-
trated in Fig. 3. The complex has the typical trigonal
arrangement of three metals (Pt2Bi) triply-bridged by
two l3-sulfide ligands. All three S–S bidentate ligands
bind to the bismuth centre asymmetrically, with one Bi–
S bond notably shorter than the other. Thus, for the
two dithiocarbamate ligands, short Bi–S distances of
Given that the major initial fragment ion for both
complexes 1 and 2 involves selective loss of two PPh3 li-
gands, it is appropriate to speculate on the nature of this
fragment ion. One possibility is that the chelating dithio
ligands on bismuth have become monodentate, with the
free sulfur donor coordinating to platinum, maintaining
its preferred four-coordination.
˚
2.688(2) and 2.718(2) A compare with longer distances
˚
of 2.910(2) and 2.876(2) A for the same ligand. Addition-
ally, each dithiocarbamate ligand has a shorter and a

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
225
Fig. 4. The coordination geometry around the bismuth centre of 1,
showing the nido-pentagonal bipyramidal geometry with the lone pair
located in an equatorial position located between S(2) and S(3).
Fig. 3. Molecular structure of the cation [Pt2(l-S)2(PPh3)4Bi(S2C-
NEt2)2]+ of (1) showing the atom numbering scheme. Only the ipso
carbon atoms of the triphenylphosphine ligands are shown for clarity.
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) for [Pt2(l-S)2(PPh3)4Bi(S2C-
NEt2)2]PF6 (1)
˚
longer C–S bond, for example 1.720(8) and 1.753(8) A;
Pt(1)–P(3)
Pt(1)–S(1)
Pt(2)–P(1)
Pt(2)–S(1)
Bi(1)–S(1)
Bi(1)–S(3)
Bi(1)–S(5)
C(11)–S(3)
C(21)–S(5)
C(11)–N(11)
2.2794(18)
2.3588(17)
2.2990(18)
2.3633(17)
2.7341(18)
2.910(2)
2.876(2)
1.722(8)
1.720(8)
1.317(10)
Pt(1)–P(4)
Pt(1)–S(2)
Pt(2)–P(2)
Pt(2)–S(2)
Bi(1)–S(2)
Bi(1)–S(4)
Bi(1)–S(6)
C(11)–S(4)
C(21)–S(6)
C(21)–N(21)
2.3116(18)
2.3465(17)
2.2831(19)
2.3606(17)
2.9587(19)
2.688(2)
2.718(2)
1.743(8)
1.753(8)
1.335(10)
the sulfur with the shorter C–S bond is the one coordinat-
ing with the longer Bi–S bond in each case. Taken to-
gether, these indicate primary coordination of the
bismuth to two dithiocarbamate sulfur donors, and
weaker interactions to the other two dithiocarbamate sul-
furs. By comparison, in Bi(S2CNEt2)3, are three short pri-
˚
mary Bi–S bonds in the range 2.595(5)–2.775(5) A, and
three secondary Bi–S bonds that are longer at 2.956(5)–
˚
2.964(4) A [18,19]. This appears to be a general feature
P(1)–Pt(2)–P(2)
S(1)–Pt(2)–S(2)
Pt(1)–S(1)–Pt(2)
Pt(1)–S(1)–Bi(1)
Pt(2)–S(1)–Bi(1)
S(1)–Bi(1)–S(2)
S(5)–Bi(1)–S(6)
S(5)–C(21)–S(6)
99.87(7)
81.10(6)
97.79(6)
91.69(6)
82.23(5)
65.16(5)
64.28(6)
118.1(5)
P(3)–Pt(1)–P(4)
S(1)–Pt(1)–S(2)
Pt(1)–S(2)–Pt(2)
Pt(1)–S(2)–Bi(1)
Pt(2)–S(2)–Bi(1)
S(3)–Bi(1)–S(4)
S(3)–C(11)–S(4)
99.29(7)
81.49(6)
88.13(6)
86.53(5)
77.54(5)
64.24(6)
118.8(5)
in bismuth dithiocarbamate compounds [20]. Likewise
for the coordination of the {Pt2S2} metalloligand, un-
equal and relatively long Bi–S bond distances of
˚
2.7341(18) and 2.9587(19) A are also observed. The same
asymmetry is seen in the previously characterised [Pt2(l-
S)2(PPh3)4BiCl3] which has Bi–S bond distances of
+
˚
˚
2.639(3) and 2.884(3) A, and in [Pt2(l-S)2(PPh3)4BiCl2]
[2.626(7) and 2.758(7) A]. Bite angles for all three S–S li-
gands are around 65ꢁ, for example, the metalloligand bite
angle S(1)–Bi(1)–S(2) is 65.16(5)ꢁ, which compares with
66.6(1)ꢁ in [Pt2(l-S)2(PPh3)4BiCl3] and 70.1(2)ꢁ in
[Pt2(l-S)2(PPh3)4BiCl2]PF6 [14].
reported for the first time, extending the (relatively small)
list of main group adducts of this system. As was also the
case with some of our other recent studies, electrospray
ionisation mass spectrometry is a powerful technique
for reaction screening and product characterisation.
The geometry about the bismuth centre is approxi-
mately nido-pentagonal bipyramidal, with the stereo-
chemically-active lone pair located between S(2) and
S(3) as illustrated in Fig. 4. The S(2)–Bi(1)–S(3) bond
angle is 127.47(5)ꢁ. In Bi(S2CNEt2)3 the bismuth geom-
etry is a pentagonal bipyramid with the lone pair in an
axial position. The dihedral angle between the two plat-
inum coordination planes is 152.1ꢁ, considerably larger
than angles of 130.7(2)ꢁ and 128.8(3)ꢁ in [Pt2(l-
S)2(PPh3)4BiCl2]+ and [Pt2(l-S)2(PPh3)4BiCl3], respec-
tively (see Table 1).
3. Experimental
3.1. Methods and instrumentation
General instrumental details were as described in re-
cent papers from these laboratories [2–8]. NMR spectra
were recorded on freshly-prepared solutions, on a Bru-
ker AC300P spectrometer [1H 300.13 MHz, 31P
121.51 MHz] in CDCl3 solution. Microanalytical data
were obtained from the Campbell Microanalytical Lab-
oratory, University of Otago, New Zealand.
2.4. Conclusions
Two new sulfur-rich adducts of the {Pt2S2} metalloli-
gand system with bismuth dithiolate complexes have been
Electrospray mass spectra were recorded using posi-
tive-ion mode on a VG Platform II instrument, using

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W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
methanol as the mobile phase and solvent. Survey reac-
tions were carried out by dissolving [Pt2(l-S)2(PPh3)4]
and the bismuth compound (ca. 0.5 mg of each) in meth-
anol (2 mL), shaking to effect reaction, centrifuging if
necessary, followed by recording the positive-ion ESI
mass spectrum using a cone voltage of 20 V. Stoichiom-
etric ESI MS-monitored reactions were carried out by
dissolving [Pt2(l-S)2(PPh3)4] (25 mg) and the appropri-
ate quantity of Bi(S2CNEt2)3 in methanol with stirring,
to give a dissolved solids concentration of about
1 mg mLꢀ1. Assignment of all ions was assisted by use
of the ISOTOPE simulation program [21].
tion was filtered, and to the filtrate was added NH4PF6
(300 mg, 1.84 mmol), resulting in formation of an orange
precipitate. After stirring for 10 min, water (10 mL) was
added, and the product filtered, washed successively with
water (10 mL), ethanol (5 mL) and petroleum spirits
(5 mL), and dried under vacuum to give 2 (230 mg,
55%) as a bright orange solid. Anal. Calc. for C78H70Bi-
F6O2P5Pt2S6 requires C, 44.6; H, 3.4. Found: C, 44.6; H,
3.4%. ESI MS: m/z 1954 [M]+, 100%, together with a
trace of [Pt(S2COEt)(PPh3)2]+ at m/z 840. 31P–{1H}
1
NMR, d 17.3 [s, J(PtP) 3087]; a freshly prepared solu-
tion showed solely 2, but on standing for ca. 2 h, addi-
tional peaks due to [Pt(S2COEt)- (PPh3)2]+ and PPh3
1
3.2. Materials
were observed (refer text). H NMR, d 7.30–7.08 (m,
Ph), 4.61 (m, CH2), 1.42 (m, CH3).
Reactions were carried out in LR grade methanol,
without exclusion of air. Products were recrystallised
from dichloromethane and diethyl ether that were dried
and distilled (from CaH2 and sodium-benzophenone ke-
tyl, respectively) under a nitrogen atmosphere prior to
use. Petroleum spirits refers to the fraction having boil-
ing range 60–80 ꢁC.
The following materials were used as supplied from
commercial sources: bismuth(III) nitrate pentahydrate
(Ajax Laboratory Chemicals, NSW, Australia), bismuth-
(III) bromide (Aldrich), sodium diethyldithiocarbamate
(Aldrich), ammonium hexafluorophosphate (Aldrich).
The complexes [Pt2(l-S)2(PPh3)4] [22] Bi(S2CNEt2)3 [16]
and Bi(S2COEt)3 [16] were prepared by the literature
procedures.
3.5. X-ray crystal structure of [Pt2(l-S)2(PPh3)4-
Bi(S2CNEt2)2]PF6 (1)
Crystals of the complex were obtained by diffusion of
diethyl ether into a dichloromethane solution of the
complex at 20 ꢁC. The complex crystallises with one
molecule of dichloromethane per mole of compound.
3.5.1. Crystal data
C83H82BiCl2F6N2P5Pt2S6, Mr 2238.78, monoclinic,
space group P21/c, Z = 4, a = 17.9813(3), b =
˚
18.9953(2), c = 25.2965(4) A, b = 103.602(1)ꢁ, V =
3
8397.9(2) A , Dcalc = 1.771 g cmꢀ3, l(Mo Ka) = 5.780
˚
mmꢀ1, size 0.38 · 0.28 · 0.22 mm3, Tmax,min = 0.3628,
0.2174, F(000) = 4368, T = 82(2) K. Total data 49576,
unique data 17097 (Rint = 0.0393), 1.17ꢁ < h < 26.39ꢁ,
3.3. Synthesis of [Pt2(l-S)2(PPh3)4Bi(S2CNEt2)2]PF6
(1)
R1(I > 2r(I)) = 0.0436, wR2 (all data)ꢀ=3 0.1143, GoF =
˚
1.075, residual De + 3.801/ꢀ1.745 e A
.
The complex [Pt2(l-S)2(PPh3)4] (300 mg, 0.200 mmol)
and Bi(S2CNEt2)3 (130 mg, 0.200 mmol) were stirred in
methanol (40 mL) for 15 min giving a slightly cloudy or-
ange solution. The solution was filtered, and to the fil-
trate was added NH4PF6 (300 mg, 1.84 mmol), with
stirring. After stirring for 30 min, the resulting orange
solid was filtered, washed successively with water
(10 mL), cold methanol (5 mL) and petroleum spirits
(5 mL) and dried under vacuum to give 1 (220 mg,
51%). Anal. Calc. for C82H80N2BiF6P5Pt2S6 requires
C, 45.7; H, 3.7; N, 1.3. Found: C, 45.5; H, 3.75; N,
1.4%. ESI MS: m/z 2008 [M]+, 100%, together with a
trace of [Pt(S2CNEt2)(PPh3)2]+ at m/z 867. 31P–{1H}
Acknowledgements
We thank the University of Waikato and the National
University of Singapore (NUS) for financial support of
this work and Dr. Tania Groutso (University of Auck-
land) for collection of the X-ray data set,
W.H. and T.S.A.H. thank the Asia:NZ Foundation for
a travel grant, facilitating exchange visits. W.H. thanks
Pat Gread and Dr. Ralph Thomson for technical support.
1
Appendix A. Supplementary data
NMR, d 20.3 [s, J(PtP) 3023].
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre, CCDC No.
271354. Copies of this information can be obtained free
of charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44 1223 336033; de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk). Supplementary data associated with this article
3.4. Synthesis of [Pt2(l-S)2(PPh3)4Bi(S2COEt)2]PF6
(2)
The complex [Pt2(l-S)2(PPh3)4] (300 mg, 0.200 mmol)
and Bi(S2COEt)3 (114 mg, 0.200 mmol) were stirred in a
mixture of methanol (30 mL) and ethanol (30 mL) for
1 h. giving a slightly cloudy orange solution. The solu-

W. Henderson et al. / Inorganica Chimica Acta 359 (2006) 221–227
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