The preparation and characterisation of platinum and palladium phosphine thiocarbonate complexes M(PR3)2(CS3) and Pt(PR3)2(CSeS2)

Article abstract of DOI:10.1016/S0277-5387(00)00295-3

Reaction of CS₂ with NH₃(liq) gives the (CS₃)^2- dianion which undergoes in situ reaction with MCl₂(PR₃)₂ to give M(PR₃)₂(CS₃). X-ray analysis of four examples (M = Pt, PR₃ = PMe₃, PMe₂Ph, PPh₃, dppp) reveals square planar coordination with the [CS₃]^2- dianion being effectively in the same plane as the coordination sphere. The first example of a [CSeS₂]^2- complex is also reported. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(00)00295-3

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 499–502
The preparation and characterisation of platinum and palladium
phosphine thiocarbonate complexes M(PR3)2(CS3) and
Pt(PR3)2(CSeS2)
*
Steven A. Aucott, Alexandra M.Z. Slawin, J. Derek Woollins
Department of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, UK
Received 15 October 1999; accepted 4 January 2000
Abstract
Reaction of CS2 with NH3(liq) gives the (CS3)2y dianion which undergoes in situ reaction with MCl2(PR3)2 to give M(PR3)2(CS3).
X-ray analysis of four examples (MsPt, PR3sPMe3, PMe2Ph, PPh3, dppp) reveals square planar coordination with the [CS3]2y dianion
being effectively in the same plane as the coordination sphere. The first example of a [CSeS2]2y complex is also reported.
q2000
Elsevier Science Ltd All rights reserved.
Keywords: Platinum; Palladium; Phosphine thiocarbonates
1. Introduction
2. Experimental
2.1. General
Sulfur donor ligands have been investigated by a number
of groups for both academic and industrial reasons including
their use in lubricant additives [1], metal specific coordina-
tion [2] and bioinorganic chemistry [3]. Although there is
a wide range of organosulfur systems [4], and more recently
S–P–N–P–S systems [5–8], there is surprisingly little infor-
mation [9–12] on perhaps the simplest anionicsulfurchelate,
[CS3]2y. We have been interested in the incorporation of
sulfur-rich ligands into complexes for a number of reasons
[13,14], and the thiocarbonate ligand has the attraction of
giving complexes with exocyclic sulfur atoms which could
be important in the formation of molecular metals as a result
of weak interactions to other species in the solid state [15].
There was a recent report on the synthesis of (diphos-
phine)platinum(II) carbonate complexes [16] and this has
prompted us to describe our work on the relatedthiocarbonate
compounds. In this work we describe a facile synthesis of
[CS3]2y together with the formation of a range of
M(PR3)2(CS3) (MsPd, Pt) complexes. The complexes
have been characterised by NMR and vibrational spectros-
copy; in addition, the X-ray structures of selected examples
are reported.
Diethyl ether, petroleum ether (60–808C) and tetrahydro-
furan were purified by reflux over sodium and distillation
under nitrogen. Dichloromethane was heated to reflux over
powdered calcium hydride and distilled under nitrogen.
Chemicals were purchased from Aldrich and Lancaster and
were used as received. The compounds [PdCl2cod] and
[PtCl2cod] [17] were prepared using literature procedures.
Infrared spectra were recorded from KBr discs on a Perkin-
Elmer system 2000 spectrometer; 31P NMR spectra were
recorded on a Jeol FX90Q operating at 36.21 MHz; 1H, 13
C
and 31P NMR spectra were recorded on Bruker instruments
operating at 250, 62.9 and 101.3 MHz, respectively. Fast
atom bombardment mass spectra were obtained by the Swan-
sea Mass Spectrometer service.
2.2. Synthesis of 1–8
Carbon disulfide (5–10 ml) was placed into a Schlenktube
and cooled to y788C. NH3 was bubbled into the cooled CS2
until two distinct layers were formed (ca. 10 min), a clear
2y
bottom layer and a blood red top layer containing the CS3
anion. MCl2(bis-phosphine), MsPd, Pt (100–130 mg) was
added as a solid and the mixture was stirred magnetically for
* Corresponding author. Tel.: q44-1334-463861; fax: q44-1334-
463384; e-mail: jdw3@st-and.ac.uk
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00295-3
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2 h at y788C and then slowly warmed to room temperature
with continual stirring until the excess NH3 had evaporated.
The resulting bright orange residue was placed under vacuum
for 1 h then extracted with 3=20 ml portions of dichloro-
methane. The combined extracts were reduced in volume to
approximately 10 ml, and 60–80 petroleum ether (ca. 40 ml)
was added slowly to the stirred solution to precipitate the
product. The bright yellow solid was collected by suction
filtration, washed with a small amount of methanol (5 ml)
and diethyl ether (1 ml), and dried overnight in vacuo. Yield
70–90% based on metal used.
2.4. X-ray crystallography
Details of the structure determination of 1–5 are given in
Table 1. X-ray diffraction measurements were made with
graphite-monochromated Mo Ka X-radiation (ls0.71073
˚
A) using a Siemens SMART diffractometer or with Cu Ka
radiation and a Rigaku AFC7S serial diffractometer. For the
SMART data, intensity data werecollectedusing0.38or0.158
width v steps accumulating area detector frames spanning a
hemisphere of reciprocal space for all structures (data were
integrated using the SAINT [18] program) and for the
Rigaku AFC7S data were collected by v scans over a single
quadrant of reciprocal space. All data were corrected for
Lorentz, polarisation and long-term intensity fluctuations.
Absorption effects were corrected on the basis of multiple
equivalent reflections or by empirical methods. Structures
were solved by direct methods and refined by full-matrix
least-squares against F (teXsan) or F2 (SHELXTL) for all
2.3. Synthesis of 9 and 10
Tetrabutylammonium borohydride (0.144 g, 0.560 mmol)
and elemental selenium (0.022 g, 0.279 mmol) were heated
to 408C under a nitrogen atmosphere in dry thf (50 cm3) for
4 h or until the reaction mixture was colourless. The mixture
was then cooled to y788C (cardice/acetone) and 11.9 cm3
of a 1.78=10y3 M solution of CS2 in thf (0.021 g, 0.276
mmol) was added and the solution stirred for 30 min, result-
ing in a bright red coloured solution. To this was added solid
PtCl2(PMe2Ph)2 (0.151 g, 0.278 mmol) and the mixturewas
stirred for 1 h at y788C and 1 h at room temperature, giving
a bright orange solution containing a light colourless precip-
itate. The precipitate was removed by filtration through celite
and the filtrate was evaporated to dryness leaving an oily dark
orange residue. The crude product was taken up into a small
volume of dichloromethane (1.5–2 cm3) and diethyl ether
(40 cm3) was added with stirring to give an orange precipi-
tate. The product was collected by suction filtration, washed
with ice cold methanol (2 cm3) followed by diethyl ether
(2=5 cm3) and dried in vacuo. Yield 0.091 g, 52%.
data with I)3s(I) with weights
w set equal to
2
2
2
(sc (Fo )q(aP)2qbP]y1
,
where Ps[max(Fo ,0)q
2
2
2Fc ]/3. The parameter x, of the form k[1q0.001xFc 13/
sin(2q)]0.25 was refined for the SMART/SHELXTL [19]
structures; the weighting scheme for theRigaku/teXsan[20]
was as previously reported [21]. All hydrogen atoms were
assigned isotropic displacement parameters and were con-
strained to idealised geometries. Refinements converged to
residuals given in Table 1. High electron densities in the final
difference maps were located close to the heavy metal centre
in all the determinations. In 10 the S/Se disorder of the metal
bonded sites in the [CSeS2]2y was refined using 50% occu-
pancy, using anisotropic refinements with the sulfur and sele-
nium atoms on each site sharing common coordinates. There
was no indication of any contribution from a selenium occu-
pancy for the terminal sulfur atom. All calculations were
made with SHELXTL [19] or teXsan [20].
Table 1
Details of the crystal data and refinements
1
3
4
5
Empirical formula
Formula weight
Crystal system
Space group
C7H18P2PtS3
455.4
monoclinic
P21/c
9.0048(5)
11.0771(6)
15.2897(8)
C17H22P2PtS3
579.6
triclinic
P-1
11.108(1)
11.427(2)
9.053(1)
104.33(1)
110.86(1)
85.27(1)
1040
C37.5H31ClP2PtS3
870.3
triclinic
C28H26P2PtS3
715.7
triclinic
P-1
10.665(1)
12.675(2)
10.505(1)
102.03(1)
103.05(1)
85.55(1)
1352
P-1
˚
a (A)
11.0763(2)
13.6100(2)
13.7719(1)
81.936(1)
86.775(1)
66.92(1)
1891
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
105.32(1)
3
˚
Volume (A )
1471
Z
4
2
2
1.53
4.05
858
2
1.76
12.7*
700
Density (calc.) (g cmy3
)
2.057
10.15
864
1.850
m (mmy1
F(000)
)
16.3 a
560
Independent reflections/observed reflections
Final R1/wR2
2094/1633
0.0662/0.1863
3101/2635
0.050/0.047
5388/4565
0.0374/0.0905
4021/3547
0.047/0.049
a
˚
Cu radiation. Pt(dppp)(CS2Se), space group P21/n, as10.842(1), bs15.713(1), cs15.257(1) A, bs106.37(1)8.
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S.A. Aucott et al. / Polyhedron 19 (2000) 499–502
501
Table 3
3. Results and discussion
31P{1H} NMR (36.2 MHz) and selected IR data for 1–8
The (CS3)2y dianion is well established but not particu-
larly well investigated. Typically the dianion is prepared by
reaction of a base such as KOH with CS2 in an inert solvent
such as dimethylformamide [9]. We have found liquid
ammonia to be a very useful solvent for a range of reactions
[22]. Here we report a simple reaction for the preparation of
(NH4)2(CS3) as well as for a range of M(PR3)2(CS3) com-
plexes (MsPd, Pt). Furthermore, we have determined the
X-ray crystal structures of four Pt(PR3)2(CS3)2 complexes
for comparison with the (CO3)2y complex which was
recently reported [16].
Complex
dP
1J(P–Pt)
(Hz)
n(C_S)
(cmy1
n(M–S)
(cmy1
(ppm)
)
)
1
2
3
4
5
6
7
8
y29.4
5.2
y19.1
17.9
y4.2
y51.7
52.0
2969
3013
3018
3145
2881
2590
1052(vs)
1057(vs)
1060(vs)
1061(vs)
1050(vs)
1047(vs)
1047(vs)
1039(vs)
395(w), 337(w)
385(w), 336(w)
387(w), 339(w)
386(w), 339(w)
387(w), 339(w)
386(w), 338(w)
390(w), 337(w)
375(w), 332(w)
18.6
The new [CS3]2ycomplexes were obtained by reaction of
CS2 with excess NH3(liq) followed by the appropriate
MCl2(PR3)2 species. All of the compounds gave satisfactory
microanalyses and FAB mass spectra (with the expected
isotopomer distributions, Table 2). In 1–8 (Tables 3 and 4)
the n(C_S) vibrations were observed at ca. 1050, and the
n(M–S) all lie close to 337 cmy1 which is in accord with
previous observations for related systems [10]. In the 31P
NMR spectra the platinum complexes have d values which
are ca. 8 ppm to higher frequency than the analogous carbon-
ate complexes [16].
Table 4
31P{1H} NMR (36.2 MHz) and selected IR data for 9 and 10
Complex Chemical shift (ppm) Coupling constant (Hz)
d(PA)
d(PB) 1J(Pt–PA) 1J(Pt–PB) 2J(PA–PB)
9
10
y19.5
y17.8 3005
3028
2886
23
33
2.8
3.4 2865
Table 5
˚
Selected bond lengths (A) and angles (8) for [Pt(PR3){CS3}] complexes
1
The J(31P–195Pt) coupling constants observed for the
PMe3
1
PMe2Ph
3
PPh3
4
dppp
5
Pt(PR3)2(CS3) complexes lie in the range 2590–3145 Hz
for the dppm and PPh3 complexes, respectively and as such
are generally ca. 500 Hz smaller in magnitude than those
observed for the analogous carbonate complexes. The values
observed here are relatively high for sulfur donor systems
though there are few dianionic examples that are directly
comparable.
Pt–P(1)
Pt–P(2)
Pt–S(1)
Pt–S(2)
S(1)–C(1)
S(2)–C(1)
S(3)–C(1)
2.263(3)
2.2669(4) 2.265(3) 2.280(2)
2.265(3) 2.303(2)
2.263(3)
2.266(3)
2.47(3)
2.346(3)
1.76(1)
1.71(1)
1.64(1)
2.342(4)
2.354(4)
1.70(2)
1.756(12) 1.71(1)
1.655(12) 1.67(1)
2.336(3) 2.358(2)
2.349(4) 2.337(2)
1.69(1)
1.731(8)
1.762(7)
1.630(7)
X-ray analysis of four Pt(PR3)2(CS3) complexes reveals
(Table 5, Fig. 1) the expected square planar geometry at
platinum. The Pt–S distances appear independent of the trans
S(1)–Pt–S(2)
P(1)–Pt–P(2)
73.8(2)
98.7(1)
S(1)–C(1)–S(3) 127.7(8)
S(2)–C(1)–S(3) 123.1(9)
S(1)–C(1)–S(2) 109.2(7)
73.3(1)
95.4(1)
125.4(8) 126.9(5)
124.1(8) 125.6(5)
110.5(7) 107.5(4)
73.74(7)
98.99(6)
73.6(1)
93.2(1)
125..7(6)
126.1(6)
108.1(5)
88.6(3)
89.7(3)
˚
phosphine (range 2.336(3)–2.358(2) A), though as
expected the Pt–P distances vary with the nature of the phos-
phine, with the PPh3 complex having the longest Pt–P bond
length. Interestingly, in Pt(dppp)(CS3) (5) the Pt–P bond
Pt–S(1)–C(1)
Pt–S(2)–C(1)
89.3(4)
87.6(5)
88.6(4)
87.6(5)
89.3(2)
89.2(3)
˚
lengths (2.263(3), 2.266(3) A) are substantiallylongerthan
˚
those [16] in Pt(dppp)(CO3) (2.216(5), 2.2149(5) A).
Table 2
Microanalytical data (expected values in parentheses) and mass spectral
data for 1–8
Complex
C
H
m/z
1 [Pt(PMe3)2{CS3}]
2 [Pt(PEt3)2{CS3}]
3 [Pt(PMe2Ph)2{CS3}]
4 [Pt(PPh3)2{CS3}]
5 [Pt(dppp){CS3}]
6 [Pt(dppm){CS3}]
7 [Pd(dppe){CS3}]
8 [Pd(PEt3)2{CS3}]
9 [Pt(PMe2Ph)2{CS2Se}]
10 [Pt(dppp){CS2Se}]
18.6 (18.5)
29.4 (28.9)
36.7 (36.2)
53.9 (53.7)
46.6 (47.0)
44.9 (45.4)
52.6 (52.9)
32.8 (34.6)
32.4 (32.6)
44.4 (44.0)
3.9 (4.0)
5.4 (5.6)
3.9 (3.8)
3.8 (3.7)
3.4 (3.7)
3.3 (3.2)
3.7 (3.9)
6.6 (6.7)
3.6 (3.5)
3.2 (3.4)
455
540
580
828
715
688
611
451
627
763
Fig. 1. The X-ray structure of Pt(PPh3)2(CS3) (4).
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S.A. Aucott et al. / Polyhedron 19 (2000) 499–502
This is presumably a consequence of the greater electrone-
gativity of the carbonate ligand that enables the dppp to
behave as a better s donor; the same effect would alsoexplain
ac.uk or www:http://www.ccdc.cam.ac.uk. Any request to
CCDC for this materialshouldquotethefullliteraturecitation
and the reference number 135551–135554.
1
the difference in the J(31P–195Pt) coupling constants. The
S–Pt–S angle in 5 (73.6(1)8) is significantly less strained
than the O–Pt–O angle (65.3(5)8) in the carbonate complex
[16]. The C–S bond lengths in the [CS3]2y ligand are longer
for the coordinated sulfur atoms than for the exocyclic sulfur
which is as anticipated. Within the PtS2C rings the Pt–S–C
and S–C–S angles are in the range 87.6(5)–89.7(3)8 and
107.5(4)–110.5(7)8, respectively, reflecting the ability that
sulfur has to adapt to greater angular distortion. In all of the
structures the (CS3)2y ligand is effectively coplanar withthe
Acknowledgements
We are grateful to the JREI for an equipment grant.
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solid state for any of the structures.
We have also developed a synthesis of the previously
unknown [CS2Se]2y dianion according to Scheme 1. We
made no attempt to isolate the [Bu4N]2[CS2Se] but used it
in situ to form complexes 9 and 10. The NMR of 9 and 10
are the expected AB type with 1J(31P–195Pt) couplings which
are appropriate for the trans coordination of sulfur or sele-
nium. Although very similar, the d values can be assigned to
phosphorus trans to sulfur and selenium by comparison with
the d values/coupling constants in complexes 3 and 5. The
X-ray diffraction studies on 10 clearly indicate the presence
of a 50% disordered [CS2Se]2y group with the selenium
being bound to the platinum; however, no meaningful bond
lengths and angles can be derived because of the disorder.
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Supplementary data
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Scheme 1. Synthesis of platinum (II) selenodithiocarbonate complexes.
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