C-S bond activation of thioethers using (dippe)Pt(NBE)2

Article abstract of DOI:10.1016/j.poly.2012.07.071

The complex (dippe)Pt(NBE)₂ (NBE = norbornene) reacts with thioethers RSR′ upon heating to give C-S oxidative addition products (RSR′ = Ph₂S, PhSMe, PhSallyl, MeSallyl, PhSvinyl, PhCH ₂SMe, PhSCF₃, and dithiane)

Full text of DOI:10.1016/j.poly.2012.07.071

Polyhedron 58 (2013) 99–105
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Polyhedron
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C–S bond activation of thioethers using (dippe)Pt(NBE)2
⇑
Sabuj Kundu, Benjamin E.R. Snyder, Aaron P. Walsh, William W. Brennessel, William D. Jones
Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
a r t i c l e i n f o
a b s t r a c t
The complex (dippe)Pt(NBE)2 (NBE = norbornene) reacts with thioethers RSR0 upon heating to give C–S
oxidative addition products (RSR0 = Ph2S, PhSMe, PhSallyl, MeSallyl, PhSvinyl, PhCH2SMe, PhSCF3, and
dithiane). Continued heating leads to disproportionation and formation of R02 and (dippe)Pt(SR)2 in
several cases.
Article history:
Available online 1 August 2012
This paper is dedicated to the memory and
indomitable spirit of Michelle Millar.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
C–S cleavage
Platinum
Phosphines
Thioethers
1. Introduction
a p-allyl complex as product [23]. In 2004, Delgado reported C–S
addition of acetylenic thioesters to ruthenium(0), giving bridged-
cluster products [24]. C–S cleavage in a sulfoxide via oxidative
addition has also been documented by O’Connor et al. [25]. Chirik
used zirconium(II) to effect thioether oxidative addition to give
Zr(IV) products [26]. More recently, Radius used Ni0(NHC)2 com-
plexes to add to the C–S bond of aryl thioethers [27].
Recently, we described C–S cleavage in thioesters using (dip-
pe)Pt(NBE)2 as a source of a reactive platinum fragment [28]. We
had shown earlier that this species could react with thiophene to
give C–S insertion products [29]. In this paper, we describe C–S
bond cleavage of a variety of thioethers including aryl, alkyl, vinyl,
and allyl sp2 and sp3 hybridized carbon centers.
Cleavage of carbon–sulfur bonds plays an important role in the
desulfurization of petroleum [1], and homogeneous transition me-
tal complexes have been extensively studied as models for the
structures of intermediates involved in the desulfurization [2].
Most of these studies involve C–S cleavage reactions of thiophenes,
benzothiophenes, or dibenzothiophenes, which are among the
more difficult substrates to be desulfurized [3,4]. Applications of
C–S cleavage in organic synthesis have also appeared, but are
somewhat rare [5–8].
Reactions in which the C–S bonds of thioethers are cleaved have
been less commonly examined with transition metals, with many
examples arising from the degradation of macrocyclic or polyden-
tate sulfur-containing ligands [9–15]. For example, reduction of
[Re(TTCN)2]2+ (TTCN = trithiacyclononane) with ascorbic acid leads
to a product in which ethylene has been extruded and a dianionic
SCH2CH2SCH2CH2S ligand is now present [16]. Nucleophilic attack
on a coordinated thiacycle has also been shown to result in C–S
bond cleavage [17–19]. Photochemical cleavage of C–S thioether
bonds has been reported using heteropolytungstates [20], and aer-
obic oxidative cleavage of b-keto-sulfides using a Co(II) complex
has been observed [21], the latter via a radical pathway. Methyl-
sulfur C–S cleavage is also believed to be involved in the latter
steps of conversion of carbon-dioxide to methane by Me-CoM
reductase [22].
2. Results and discussion
2.1. C–S bond activation of diphenyl sulfide
Treatment of (dippe)Pt(NBE)2 (1) with excess diphenyl sulfide
in p-xylene at 140 °C for 7 d afforded complex 2 in good yield
(76%, Eq. (1)). Complex 2 was isolated as off-white solid and char-
acterized by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy and X-ray
crystallography Fig 1. The ortho Pt–phenyl hydrogens appear in the
1H NMR spectrum as a multiplet at d 7.57 with platinum satellites
(JPt–H = 43 Hz).
A few examples of C–S oxidative addition to metal complexes
have been reported as summarized in Scheme 1. In 1998, Komiya
observed the addition of allyl phenyl sulfide to Ru(cot)(cod) to give
ð1Þ
⇑
Corresponding author. Tel.: +1 585 275 5493.
E-mail address: jones@chem.rochester.edu (W.D. Jones).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.07.071

100
S. Kundu et al. / Polyhedron 58 (2013) 99–105
Fig. 2. X-ray structure of complex 3a. Ellipsoids are shown at the 50% probability
level.
4.9 Hz) also with platinum satellites (JPt–H = 56 Hz). These data
are in agreement with the couplings observed previously for the
SMe groups in (dippe)Pt(SMe)2 (d 3.03, d, JPt–H = 44 Hz, JP–H
=
5.6 Hz) [28].
ð2Þ
Scheme 1. Recent examples of thioether C–S cleavage.
2.3. C–S bond activation of phenyl- and methyl-allyl sulfides
Reaction of (dippe)Pt(NBE)2 (1) with excess allyl methyl sulfide
or allyl phenyl sulfide in benzene or p-xylene at 100 °C for 20 min
afforded the allyl thiolate complex 4a or 4b in good yield (70%,
Scheme 2), which were isolated and characterized by 1H, 13C{1H},
and 31P{1H} NMR spectroscopy. For 4b, the CH2 appears at d 2.65
as a quartet (JH–H = 7.4 Hz) with platinum satellites (JPt–H = 74 Hz).
A single crystal X-ray structure of 4a is shown in Fig. 3, displaying
a
r-allyl moiety. Further reaction occurs upon heating to 140 °C
for extended periods. Hexa-1,5-diene was identified as the organic
Fig. 1. X-ray structure of complex 2. Ellipsoids are shown at the 50% probability
level.
2.2. C–S bond activation of methyl phenyl sulfide
Similar to diphenyl sulfide, treatment of (dippe)Pt(NBE)2 (1)
with excess methyl phenyl sulfide in p-xylene at 140 °C for 7 d
afforded complex 3a in good yield (88%, Eq. (2)). Complex 3a was
isolated as off-white solid and characterized by 1H, 13C{1H}, and
31P{1H} NMR spectroscopy and X-ray crystallography (Fig. 2). The
same reaction at lower temperature (100 °C) did not afford any
(dippe)Pt(Me)(SPh) even at earlier reaction time, and only product
complex 3a was identified. The ortho phenyl hydrogens appear in
the 1H NMR spectrum as a triplet at d 7.86 with platinum satellites
(JPt–H = 46 Hz). The SMe resonance appears as a doublet (JP–H
=
Scheme 2. Reaction of (dippe)Pt(NBE)2 with RSallyl.

S. Kundu et al. / Polyhedron 58 (2013) 99–105
101
ometric) bibenzyl, observed by 1H NMR spectroscopy and GC–MS in
the reaction mixture, provided evidence that (dippe)Pt(SMe)(CH2-
Ph) was an intermediate in the formation of (dippe)Pt(SMe)2.
ð3Þ
2.6. Activation of phenyl trifluoromethyl sulfide
The reaction of 1 with excess phenyl trifluoromethyl sulfide in
mesitylene at 160 °C was monitored by 31P{1H} and 19F{1H} NMR
spectroscopy over the course of 3 d. Partial conversion of the start-
ing material was observed, and the resulting mixture of products
was complicated. The 19F{1H} NMR spectrum of the reaction mix-
ture contains a resonance with what appear to be platinum satel-
lites, as well as cis and trans couplings to phosphorus. The
19F{1H} NMR spectra of the known complexes (dppe)Pt(CF3)(Br)
and (dppe)Pt(CF3)(OH) in CDCl3 show 3JPt–F couplings on the order
of 580 Hz, trans-3JP–F couplings on the order of 55 Hz, and cis-3JP–F
couplings on the order of 12 Hz [31]. These couplings are similar to
those observed in the 19F{1H} NMR spectrum of the reaction mix-
ture, suggesting that the observed product is (dippe)Pt(SPh)(CF3),
and not (dippe)Pt(SCF3)(Ph) (Eq. (4)). The CF3 group thus appears
to alter the selectivity of C–S activation relative to the analogous
non-fluorinated substrate, PhSCH3.
Fig. 3. X-ray structure of complex 4a. Ellipsoids are shown at the 50% probability
level.
product by GC–MS. Complex 5a was identified by comparison with
literature data [28]. Complex 5b was isolated as off-white solid and
characterized by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy and X-
ray crystallography (Fig. 4).
2.4. C–S bond activation in phenyl vinyl sulfide
Treatment of (dippe)Pt(NBE)2 (1) with excess phenyl vinyl sul-
fide in benzene or p-xylene at 100 °C for 20 min afforded
p-complex
(dippe)Pt(
g
2-CH2CHSPh), 6 ‘(Scheme 3). Further reaction of 6 oc-
curs upon heating to 140 °C. First, vinyl thiolate complex 7 is ob-
served after 5 d. Next, bis-thiolate 5b was formed, and butadiene
was identified as the organic product by GC–MS. Oxidative addition
of a number of aryl vinyl sulfides to [Pt(PPh3)2] has been reported by
g
2-vinyl intermediates were not observed [30].
ð4Þ
Kuniyasu et al., but
2.5. C–S bond activation of benzyl methyl sulfide
The reaction of 1 with excess benzyl methyl sulfide in C6H6 at
140 °C yieldeda complicatedreactionmixturewhichwasmonitored
by 31P{1H} NMR over the course of several days. The complex (dip-
pe)Pt(SMe)(CH2Ph) was not identified by 31P{1H} NMR spectros-
copy. The major product was instead determined to be
(dippe)Pt(SMe)2 (5a) (Eq. (3)). The presence of ꢀ1 mM (sub-stoichi-
2.7. C–S bond activation of dithiane
The reaction of 1 with excess dithiane in mesitylene at 180 °C
was monitored by 31P{1H} NMR spectroscopy over the course of
7 d. Complete conversion of the starting material was observed,
furnishing (dippe)Pt(
j
2-SCH2CH2S) (9) in ꢀ90% yield by 31P{1H}
NMR spectroscopy (Eq. (5)). This product was characterized by
1H, 13C{1H}, 31P{1H}, 1H COSY, and 1H-13C HSQC NMR. 9 almost cer-
tainly forms by the rearrangement of the intermediate (dip-
pe)Pt(j
2-SCH2CH2SCH2CH2) (8). The presence of ethylene in the
reaction mixture, observed directly by GC–MS and 1H NMR spec-
troscopy (d 5.28), provides evidence supporting this claim.
ð5Þ
2.8. Synthesis of (dippe)Pt(SPh)(Me)
As mentioned above, the activation of methyl phenyl sulfide by
Scheme 3. Reaction of (dippe)Pt(NBE)2 with PhSCH@CH2.
1 furnishes (dippe)Pt(SCH3)(Ph), not (dippe)Pt(SPh)(CH3). It is

102
S. Kundu et al. / Polyhedron 58 (2013) 99–105
possible that the latter complex is a transient kinetic product,
which thermally rearranges to yield the observed product under
the reaction conditions. To test this hypothesis, (dippe)
Pt(SPh)(CH3) (10) was synthesized from (dippe)Pt(CH3)2 by treat-
ment with PhSH. The mixture containing 10 was held at 140 °C
for 1 d, at which point no rearrangement was observed by
31P{1H} NMR. These data indicate that 10 is not a kinetic product,
and may also be disfavored thermodynamically.
2.9. Activation of allyl methyl sulfide by the complex
(dippe)Pt(SPh)(Ph) – evidence for sulfide metathesis
One observed characteristic of the reactivity of thioethers with
(dippe)Pt(SR)(R0) is the tendency to form the bis-thiolate (dip-
pe)Pt(SR)2 when heated in the presence of excess substrate. The
mechanism for this reaction is proposed to involve an octahedral
Pt(IV) species as a likely intermediate. One deviation from this pat-
tern of reactivity is seen in (dippe)Pt(SPh)(Ph) (2), the activation
product of diphenyl sulfide. Unlike (dippe)Pt(SPh)(g
1-CH2CHCH2)
Fig. 4. X-ray structure of complex 5b. Ellipsoids are shown at the 50% probability
level.
and (dippe)Pt(SPh)(CHCH2), 2 does not proceed to the bis-thiolate
(dippe)Pt(SPh)2. This lack of reactivity may be due to the strength
of the Pt-phenyl bond. Alternatively, the bulk of this complex may
disallow the addition of a second molecule of substrate. It is also
possible that, if a stable intermediate does form, the transition
state associated with reductive elimination of biphenyl has a pro-
hibitively high activation barrier due to geometric constraints
associated with Csp2–Csp2 bond formation.
To test this hypothesis, a less bulky substrate – allyl methyl sul-
fide – was reacted with 2 at 160 °C for 2 d. The reaction was mon-
itored by 31P{1H} NMR spectroscopy, with the expectation that a
mixed bis-thiolate complex (dippe)Pt(SPh)(SMe) and the corre-
sponding cross-linked organic product, allylbenzene, would be
formed. Instead, partial conversion (ꢀ30% by 31P{1H} NMR) of the
starting material to (dippe)Pt(SMe)(Ph) was observed (Scheme 4).
The corresponding organic product, allyl phenyl sulfide, was ob-
served by 1H NMR and GC–MS.
These data are consistent with an octahedral Pt(IV) species (dip-
pe)Pt(SPh)(SMe)(Ph)(
mation of (see Fig.
g
1-CH2CHCH2) as an intermediate in the for-
3
5 for possible geometries). Previous
experiments with thioesters have shown reactivity consistent with
Scheme 4, in which a hydrocarbon is eliminated from PtIV with the
formation of the bis-thiolate [28]. This being the case, it is reason-
able to propose the phenolate and allyl ligands are cis to each other
in the proposed intermediate. The observation of allyl phenyl sul-
fide suggests the allyl ligand is also cis to the phenylthiolate ligand.
Two plausible routes for the formation of a species with this geom-
etry are cis oxidative addition and an SN2-like mechanism seen in
the oxidative addition of methyl iodide to square-planar Pt(II)
complexes [32].
Fig. 5. Potential classical and pericyclic mechanisms for the reductive elimination
of allyl phenyl sulfide from (dippe)Pt(SPh)(SMe)(Ph)(g
1-CH2CHCH2).
ically stable since two platinum–sulfur bonds are formed. It is
possible that the allyl ligand affords a kinetic advantage to the for-
mer pair: allyl phenyl sulfide could form through a reductive elim-
ination involving a 5-membered transition state (Fig. 5). This
transition state could have aromatic character if the plane of the
metallacycle is oriented properly with respect to the LUMO of (dip-
pe)Pt(SPh)(SMe)(Ph)(g
1-CH2CHCH2).
One question that arises from this experiment is why the
observed products are favored over (dippe)Pt(SPh)(SMe) and allyl-
benzene – the latter pair would appear to be more thermodynam-
3. Conclusions
The reactivity of the Pt(0) complex (dippe)Pt(NBE)2 with a num-
ber thioethers has been examined. Physical characterizations of the
resulting C–S activation products (dippe)Pt(SR)(R0) were carried
out by 1H, 13C{1H}, and 31P{1H} NMR spectroscopy; 1H COSY and
1H–13C HSQC NMR (as needed); as well as X-ray diffraction and
elemental analysis (EA). Both S–Csp2 and S–Csp3 bonds can be
cleaved. Investigation into the mechanism of methyl phenyl sulfide
activation by (dippe)Pt(NBE)2 indicates (dippe)Pt(SPh)(Me) is not
an intermediate in the formation of (dippe)Pt(SMe)(SPh). Instead,
the data indicate the former complex is kinetically and possibly
thermodynamically disfavored. The investigation into the general
mechanism through which bis-thiolates (dippe)Pt(SR)2 form are
Scheme 4. Cleavage of allyl methyl sulfide.

S. Kundu et al. / Polyhedron 58 (2013) 99–105
103
consistent with an octahedral Pt(IV) intermediate. The data also
suggest the metathesis of allyl phenyl sulfide seen in the reaction
of (dippe)Pt(SPh)(Ph) with allyl methyl sulfide could proceed
through an unusual pericyclic mechanism. Further theoretical
studies of this pathway are underway.
18.6 (d, JP–C = 1 Hz), 18.2 (s, JPt–C = 13 Hz), 17.6 (s, JPt–C = 25 Hz),
11.4 (dd, JP–C = 9, 2 Hz). 31P{1H} NMR (162 MHz, C6D6) d 63.88 (d,
JP–P = 4 Hz, JPt–P = 1750 Hz), 59.74 (d, JP–P = 4 Hz, JPt–P = 2790 Hz).
Anal. Calc. for C21H40P2PtS: C, 43.36; H, 6.93. Found: C, 43.32; H,
6.80%.
4.4. Synthesis of (dippe)Pt(SMe)(
g
1-CH2CHCH2) (4a)
4. Experimental
In a J. Young tube, allyl methyl sulfide (30
lL, 0.205 mmol) was
4.1. General procedures and materials
added to 1 (20 mg, 0.031 mmol) dissolved in 0.7 mL C6D6. This
mixture was heated to 100 °C for 20 min, at which point complete
conversion of the starting material was observed by 31P{1H} NMR
spectroscopy. The reaction mixture was placed under vacuum to
remove all volatiles, and the 1H NMR spectrum was recorded. 1H
NMR (400 MHz, C6D6): d 6.84 (m, 1H), 5.11 (m, 1H), 4.85 (m, 1H),
2.81 (d, JP–H = 5 Hz, JPt–H = 46 Hz, 3H), 2.74 (m, 2H overlapping with
SMe), 2.22 (m, 2H), 2.13 (m, 2 H), 1.30 (dd, JP–H = 16, 7 Hz, 6H), 1.05
(dd, JP–H = 15, 7 Hz, 8H), 0.81 (dd, JP–H = 13, 6 Hz, 7H), 0.77 (dd,
JP–H = 13, 6 Hz, 7H). 13C{1H} NMR (125 MHz, C6D6): d 148.2 (d,
JPt–C = 56 Hz, JP–C = 7 Hz), 105.7 (d, JPt–C = 54 Hz, JP–C = 8 Hz), 24.5
(d, JP–C = 21 Hz), 24.4 (dd, JP–C = 30, 17 Hz), 24.3 (d, JP–C = 16 Hz),
Unless otherwise stated, all reactions and manipulations were
carried out in dry glassware using standard Schlenk and glovebox
techniques under an inert atmosphere. Deuterated solvents
(Cambridge Isotope Laboratories) for NMR experiments were dried
over Na/K and distilled under vacuum. All thioethers were
purchased from Aldrich and VWR and used without any further
purification. All other reagent grade chemicals were used without
any further purification. All NMR spectra were recorded on Bruker
Avance 400 and 500 MHz spectrometers. 31P{1H} NMR chemical
shifts (d in ppm) are relative to an external 85% solution of
H3PO4 in the appropriate solvent. 19F{1H} NMR chemical shifts
are relative to internal PhSCF3. Elemental analyses were obtained
from CENTC Elemental Analysis Facility at the University of
Rochester. GC–MS spectra were recorded on SHIMADZU QP2010
23.5 (dd, JP–C = 30, 17 Hz), 20.8 (dd, JP–C = 25, 11 Hz), 19.7 (dP–C
J = 3 Hz), 19.0 (dP–C, J = 3 Hz), 18.2 (d, JP–C = 3 Hz), 18.0 (d, JP–C
3 Hz), 7.3 (dd, JP–C = 8, 2 Hz, JPt–C = 20 Hz). 31P{1H} NMR
(162 MHz, C6D6): d 65.32 (s, JPt–P = 1836 Hz), 61.82 (s, JPt–P
,
=
=
using
a
60 m ꢁ 0.25 mm SPB1701 capillary column. (dippe)
2954 Hz). Continued heating at 140 °C (2 d) led to the formation
of hexa-1,5-diene (d 5.83, td, J = 17, 7 Hz, 2H; 5.10, dd, J = 19,
13 Hz, 6H; 3.01, d, J = 7 Hz, 4H) and (dippe)Pt(SMe)2, 5a, which
has been reported previously [28] (quantitative by 31P NMR
spectroscopy). For 5a, 1H (400 MHz, C6D6): d 3.02 (d, JP–H = 6 Hz,
JPt–H = 43 Hz, 6H), 2.38 (dquint, J = 9, 7 Hz, 4H), 1.24 (dd, J = 16,
7 Hz, 12H), 0.93 (dd, J = 21, 10 Hz, 4H), 0.77 (dd, J = 14, 7 Hz,
12H). 13C{1H} NMR (125 MHz, C6D6): d 25.8 (s, JPt–C = 27 Hz), 25.5
(s, JPt–C = 27 Hz), 23.0 (dd, JP–C = 28, 12 Hz; JPt–C = 68 Hz), 19.9 (s),
18.8 (s, JPt–C = 21 Hz). 31P{1H} NMR (162 MHz, C6D6): d 68.76 (s,
JPt–P = 2681 Hz).
Pt(NBE)2 was prepared as previously described [28].
4.2. Synthesis of (dippe)Pt(Ph)(SPh) (2)
In a J-Young tube (dippe)Pt(NBE)2 (20 mg, 0.0309 mmol), diphe-
nyl sulfide (51.6 lL, 0.309 mmol), and p-xylene-d10 (0.5 mL) were
combined and heated at 140 °C for 7 d. The reaction was monitored
by 1H and 31P{1H} NMR spectroscopy. The volatiles were removed
under vacuum and the remaining light yellow liquid (mostly free
diphenyl sulfide) was washed with small quantities of hexane.
Complex 2 was obtained as a light brown solid, still containing
some diphenyl sulfide. Yield: 76%. Crystals of complex 2 were
grown by slow evaporation of the hexane extract. 1H NMR
(500 MHz, C6D6): d 7.56 (m, 2H), 7.30 (m, 3H), 6.93 (m, 5H), 2.24
(m, 2H), 1.91 (m, 2H), 1.37 (m, 6H), 1.04 (m, 4H), 0.89 (m, 6H),
4.5. Synthesis of (dippe)Pt(SPh)(
g
1-CH2CHCH2) (4b)
In a J. Young tube, allyl phenyl sulfide (30
lL, 0.205 mmol) was
added rapidly to 1 (40.7 mg, 0.0631 mmol) dissolved in 1.3 mL
pentane. This mixture was heated to 100 °C for 20 min, at which
point complete conversion of the starting material was observed
by 31P{1H} NMR spectroscopy. The reaction mixture was heated
to 40 °C and held under vacuum for 12 h to remove the excess sul-
fide. Yield: 70%. Assignments in the 1H NMR spectrum of this com-
plex were facilitated with 1H COSY data. Assignments in the
13C{1H} NMR spectrum were facilitated with 1H-13C HSQC data.
For 4b, 1H NMR (400 MHz, C6D6): d 7.97 (d, JH–H = 7 Hz, 2H), 6.97
(t, JH–H = 7 Hz, 1H), 6.86 (m, 1H), 4.95 (d, JH–H = 17 Hz, 1H), 4.77
(d, JH–H = 9 Hz, 1H), 2.64 (quartet, JPt–H = 73 Hz, JP–H = 7 Hz, 2H),
2.15 (dm, JP–H = 64 Hz, JH–H = 8 Hz, 4H), 1.24 (dd, JP–H = 16 Hz,
JH–H = 7 Hz, 6H), 1.01 (dd, JP–H = 16 Hz, JH–H = 7 Hz, 6H), 0.79 (dd,
JP–H = 16 Hz, JH–H = 7 Hz, 8H), d 0.76 (dd, JP–H = 16 Hz, JH–H = 7 Hz,
8H). 13C{1H} NMR (125 MHz, C6D6): d 148.5 (d, JPt–C = 53 Hz,
JP–C = 8 Hz), 135.3 (d, JPt–C = 34 Hz, JP–C = 3 Hz), 126.8 (s), 122.9 (s),
104.9 (d, JPt–C = 49 Hz, JP–C = 7 Hz), 24.6 (m), 23.5 (dd, JP–C = 30,
18 Hz), 20.4 (dd, JP–C = 24, 10 Hz), 19.7 (d, JP–C = 2 Hz), 19.2 (d,
JP–C = 4 Hz), 18.2 (s). Note that the Pt–C coupling in the resonance
at d 23.5 was visible in the 1H–13C HSQC NMR spectrum of 4b.
31P{1H} NMR (162 MHz, C6D6): d 66.4 (s, JPt–P = 1787 Hz), 63.0 (s,
JPt–P = 3170 Hz). Anal. Calc. for C23H42P2PtS: C, 45.46; H, 6.97.
Found: C, 45.69; H, 6.79%. Continued heating at 140 °C (2 d) led
to the formation of hexa-1,5-diene and (dippe)Pt(SPh)2, 5b (quan-
titative by 31P NMR spectroscopy). For 5b, 1H NMR (400 MHz,
C6D6): d 7.77 (d, JH–H = 7 Hz, 4H), 7.02 (t, JH–H = 7 Hz, 4H), 6.89 (t,
0.74 (m, 12H). 31P{1H} NMR (162 MHz, C6D6) d: 63.94 (s, JPt–P
=
1711 Hz), 59.31 (s, JPt–P = 2986 Hz). Anal. Calc. for C26H42P2PtS: C,
48.51; H, 6.58. Found: C, 48.27; H, 6.68%. 13C {1H} NMR
(125 MHz, C6D6): d 158.8 (dd, JP–C = 108, 10 Hz), 143.3 (dd, JP–C
=
8, 3 Hz), 138.9 (s, JPt–C = 22 Hz), 135.8 (s, JPt–C = 29 Hz), 127.3 (d,
JPt–C = 114 Hz, JP–C = 27 Hz) 126.9 (s), 122.9 (s), 122.0 (s), 24.5 (d,
JP–C = 24 Hz, JPt–C = 14 Hz), 24.0 (d, JP–C = 31 Hz, JPt–C = 43 Hz), 23.7
(dd, JP–C = 29, 17 Hz), 20.9 (dd, JP–C = 25, 10 Hz), 19.2 (d, JP–C
3 Hz), 18.6 (s), 18.3 (s, JPt–C = 12 Hz), 17.5 (s, JPt–C = 28 Hz).
=
4.3. Synthesis of (dippe)Pt(Ph)(SCH3) (3)
In
a
J-Young tube (dippe)Pt(NBE)2 (20 mg, 0.0309 mmol),
L, 0.309 mmol), and p-xylene-d10
methyl phenyl sulfide (36.3
l
(0.5 mL) were combined and heated at 140 °C for 7 d. The reaction
was monitored by 1H and 31P{1H} NMR spectroscopy. The volatiles
were removed under vacuum yielding light brown complex 3
(88%). C rystals of complex 3 were grown by slow evaporation from
a hexane solution. 1H NMR (400 MHz, C6D6): d 7.86 (t, JH–H = 6.8 Hz,
JPt–H = 46 Hz, 2H), 7.29 (t, JH–H = 6.8 Hz, 2H), 7.07 (t, JH–H = 7.2 Hz,
1H), 2.25 (d, JP–H = 5.2 Hz, JPt–H = 56 Hz, 3H), 2.18 (m, 2H), 1.93
(m, 2H), 1.39 (m, 6H), 1.05 (m, 2H), 0.82 (m, 20H). 13C{1H} NMR
(125 MHz, C6D6): d 138.8 (s, JPt–C = 24 Hz), 126.8 (s), 125.0 (s),
122.5 (s), 24.4 (d, JP–C = 25 Hz), 24.0 (d, JP–C = 30 Hz), 23.7 (dd,
JP–C = 17, 9 Hz), 21.3 (dd, JP–C = 15, 11 Hz), 19.0 (d, JP–C = 3 Hz),

104
S. Kundu et al. / Polyhedron 58 (2013) 99–105
JH–H = 7 Hz, 2H), 2.31 (sextet, JPt–H = 13 Hz, JP–H = 7 Hz, 4H), 1.21
0.0631 mmol) in 1.0 mL mesitylene. The reaction was held at
100 °C for 24 h, and then increased over 3 d, at which point some
conversion of the starting material was noted. After 3 d at 160 °C,
the reaction mixture was a dark olive green. The 31P{1H} NMR
spectrum of the reaction mixture was quite complicated after only
minimal conversion of the starting material. The 19F{1H} NMR
spectrum of the reaction mixture is similarly complicated, but it
shows a characteristic resonance (dd, JPt–F = 240 Hz, JP–F = 57 Hz,
JP–F = 22 Hz) 0.78 ppm upfield of the prominent peak due to
PhSCF3. The couplings observed in this resonance suggest (dip-
pe)Pt(SPh)(CF3) was present in the reaction mixture.
(dd, JP–H = 16 Hz, JH–H = 7 Hz, 12H), 0.98 (dd, JP–H = 21 Hz, JH–H
=
9.6 Hz, 4H), 0.80 (dd, JP–H = 14 Hz, JH–H = 7 Hz, 12H). 13C{1H} NMR
(125 MHz, C6D6): d 134.4 (s, JPt–C = 31 Hz), 129.2 (s, JPt–C = 21 Hz),
126.9 (s), 122.4 (s), 25.10 (d, JP–C = 31 Hz, JPt–C = 27 Hz), 22.20 (dd,
JP–C = 29,
11 Hz),
19.36
(s,
JPt–C = 11 Hz),
18.18
67.13 (s,
(s, JPt–C = 21 Hz). 31P{1H} NMR (162 MHz, C6D6):
d
JPt–P = 2765 Hz). Anal. Calc. for C26H42P2PtS2:C, 46.21; H, 6.26.
Found: C, 47.19; H, 6.38.
4.6. Synthesis of (dippe)Pt(SPh)(CHCH2) (7)
In a J. Young tube, phenyl vinyl sulfide (30 lL, 0.230 mmol) was
added rapidly to solution of 1 (40.7 mg, 0.0631 mmol) in 1.3 mL
4.9. Synthesis of (dippe)Pt(2-SCH2CH2S) (9)
pentane. This mixture was heated to 100 °C for 20 min, at which
point complete conversion of the starting material to (dippe)Pt(g2
-
In a J. Young tube, dithiane (40 mg, 0.333 mmol) was added to a
solution of 1 (40.7 mg, 0.0631 mmol) in 1.0 mL mesitylene. The
reaction mixture was held at 180 °C for 1 week, at which point it
was dark orange. Total conversion of the starting material was ob-
served by 31P{1H} NMR spectroscopy. The 31P{1H} NMR data indi-
cated a symmetric structure, and were not consistent with the
CH2CHSPh) (6) was observed by 31P{1H} NMR spectroscopy. 1H
NMR (400 MHz, C6D6): d 7.92 (d, JH–H = 8 Hz, 2H), 7.20 (t, JH–H
=
7 Hz, 2H), 6.95 (t, JH–H = 7 Hz, 1H), 3.82 (m, JPt–H = 62 Hz, 1H),
2.74 (m, JPt–H = 50 Hz, 1H), 2.35 (m, JPt–H = 53 Hz, 1H), 1.80 (m,
4H), 1.16 (m, 8H), 0.99 (m, 10H), 0.81 (m, 10H). 13C{1H} NMR
(125 MHz, C6D6): d 149.1 (dd, JP–C = 13, 2 Hz, JPt–C = 74 Hz), 128.6
asymmetric product (dippe)Pt(j
2-SCH2CH2SCH2CH2) (8). 1H NMR
and GC–MS spectra showed the presence of ethylene in the reac-
tion mixture (s, d 5.28). The reaction mixture was then heated to
40 °C and held under vacuum for 2 d to remove solvent. Sublima-
tion of a considerable portion of the excess dithiane was observed,
(s), 125.6 (s), 123.2 (s), 33.2 (dt, JP–C = 41 Hz, JP–C = 5 Hz, JPt–C
=
242 Hz), 26.6 (dt, JP–C = 22, 4 Hz), 25.9 (ddd, JP–C = 30, 14, 4 Hz),
24.4 (dd, JP–C = 25, 15 Hz), 23.7 (dd, JP–C = 25, 15 Hz), 18.2–19.6
(m). 31P{1H} NMR (162 MHz, C6D6): d 78.20 (d, JP–P = 58 Hz,
JPt–P = 3253 Hz), 75.14 (d, JP–P = 58 Hz, JPt–P = 3098 Hz). Anal. Calc.
for C22H40P2PtS: C, 44.51; H, 6.79. Found: C, 44.46; H, 6.75%.
Volatiles were stripped from the reaction mixture, and the result-
ing solids were heated to 40 °C and held under vacuum for 12 h to
remove excess sulfide. The solids were re-dissolved in C6D6 and the
resulting solution was heated to 140 °C for 5 d, yielding 7 in a near
quantitative yield by 31P{1H} NMR spectroscopy. 1H NMR
(400 MHz, C6D6): d 7.95 (d, JH–H = 8 Hz, 2H), 7.73 (m, 1H; obscured
but the product (dippe)Pt(j
2-SCH2CH2S) (9) could not be obtained
in pure form. Yield: 48%. For 9, 1H NMR (400 MHz, C6D6): d 3.07 (s,
JPt–H = 44 Hz, 4H), 2.15 (m, 4H), 1.25 (dd, JP–H = 17 Hz, JH–H = 7 Hz,
12H), 0.98 (m, 4H), 0.74 (dd, JP–H = 14 Hz, JH–H = 7 Hz, 12H).
13C{1H} NMR (125 MHz, C6D6): d 39.1 (d, JPt–C = 8.3 Hz, JP–C
9.6 Hz), 26.1 (d, JPt–C = 28.5 Hz, JP–C = 31.5 Hz), 22.2 (d, JP–C
=
=
10.6 Hz),18.9 (s, JPt–C = 12.2 Hz), 18.2 (s, JPt–C = 20.5 Hz). 31P{1H}
NMR (162 MHz, C6D6): d 72.1 (s, JPt–P = 2661 Hz). Anal. Calc. for
C16H36P2PtS2: C, 34.97; H, 6.60. Found: C, 34.73; H, 6.25%.
by resonance at d 7.71), 7.20 (t, JH–H = 7.3 Hz, 2H), 7.00 (t, JH–H
=
7 Hz, 1H), 6.33 (ddd, JP–H = 21 Hz, JH–H = 12, 3 Hz, JPt–H = 114 Hz,
1H), 5.55 (ddd, JP–H = 19, 10, 3 Hz, JPt–H = 150 Hz, 1H), 2.13 (dm,
JP–H = 52 Hz, JP–H = 2 Hz, JH–H = 7 Hz, 4H), 1.29 (dd, JP–H = 16 Hz,
JH–H = 7, 6H), 0.99 (dd, JP–H = 16 Hz, JH–H = 7, 6H), 0.82 (dd, JP–
H = 13 Hz, JH–H = 7, 6H), 0.71 (dd, JP–H = 14 Hz, JH–H = 7, 6H).
4.10. Synthesis of (dippe)Pt(Me)2
Complex (dippe)Pt(Me)2 was prepared according to the proce-
dure outlined in Bassan et al. [33]. In a J. Young tube, dippe
(17 lL, 0.061 mmol) was added to (cod)Pt(Me)2 (20 mg,
13C{1H} NMR (125 MHz, C6D6): d 156.4 (dd, JP–C = 107 Hz, JP–C
=
10 Hz), 136.1 (d, JPt–C = 31 Hz, JP–C = 3 Hz), 128.6 (s), 127.2 (s),
123.2 (s), 120.0 (s), 24.6 (d, JPt–C = 15 Hz, JP–C = 24 Hz), 24.0 (d,
JPt–C = 41 Hz, JP–C = 32 Hz), 23.5 (dd, JP–C = 25, 10 Hz), 20.8 (dd,
JPt–C = 57 Hz, JP–C = 25, 10 Hz), 19.2 (m), 18.2 (s, JPt–C = 13), 17.9 (s,
0.060 mmol) in 0.9 mL Et2O. The reaction sat at room temperature
for 10 min, at which point total conversion of the starting material
was observed by 31P{1H} and 1H NMR spectroscopy.
JPt–C = 28). 31P{1H} NMR (162 MHz, C6D6):
d 64.9 (s, JPt–P =
4.11. Synthesis of (dippe)Pt(SPh)(Me) (10)
1706 Hz), 61.4 (s, JPt–P = 3005 Hz). Anal. Calc. for C22H40P2PtSꢂ½C6-
H6: C, 47.46; H, 6.85. Found: C, 47.40; H, 6.66%.
In a J. Young tube, thiophenol (7.8 lL, 0.076 mmol) was added
to a solution of (dippe)Pt(Me)2 (30 mg, 0.0631 mmol) in 0.9 mL
C6H6. The reaction mixture was held at 100 °C for 2 d, at which
point complete conversion of the starting material was observed
by 31P{1H} NMR spectroscopy. The volatiles were stripped from
the reaction mixture under vacuum, and the remaining off-white
solid was dissolved in C6D6. For 10, 1H NMR (400 MHz, C6D6): d
4.7. Activation of benzyl methyl sulfide
In a 20 mL vial, benzyl methyl sulfide (35 lL, 0.257 mmol) was
added to a stirred solution of 1 (19.7 mg, 0.0305 mmol) in 1.0 mL
C6D6. The reaction was held at 160 °C on a heating block for 3 d,
at which point approximately 75% conversion of the starting mate-
rial was observed by 31P{1H} NMR spectroscopy. The major product
was (dippe)Pt(SMe)2 (5a), previously characterized [28]. The 1H
NMR spectrum of the reaction mixture shows a characteristic
sharp peak at d 2.15 due to the aliphatic protons of bibenzyl. The
presence of this species was also confirmed by GC–MS. By compar-
ing the chromatogram with a standard, it was determined that the
reaction mixture contained ꢀ1 mM bibenzyl.
7.96 (d, JH–H = 7 Hz, 2H), 7.18 (t, JH–H = 7 Hz, 2H), 6.96 (t, JH–H
=
7 Hz, 1H), 2.21 (dm, JP–H = 133 Hz, JH–H = 7 Hz, 4H), 1.45 (dd,
JP–H = 16 Hz, JP–H = 7 Hz, 6H), 1.09 (dd, JP–H = 16 Hz, JP–H = 7 Hz,
7H), 0.99 (dd, JP–H = 13 Hz, JP–H = 7 Hz, 8H), 0.86 (dd, JP–H = 14 Hz,
JP–H = 7 Hz, 7H). 13C{1H} NMR (125 MHz, C6D6): d 144.7 (dd,
JP–C = 7, 3 Hz), 136.0 (d, JPt–C = 30 Hz, JP–C = 3 Hz), 127.4 (s), 123.1
(s), 24.7 (d, JP–C = 24 Hz), 24.5 (d, JP–C = 31 Hz), 24.1 (dd, JP–C = 29,
17 Hz), 20.6 (dd, JP–C = 24, 10 Hz), 19.1 (d, JP–C = 4 Hz), 19.0
(d, JP–C = 3 Hz), 18.2 (s, JPt–C = 14 Hz), 18.0 (s, JPt–C = 26 Hz), 0.2
(dd, JP–C = 89, 8 Hz, JPt–C = 860 Hz). 31P{1H} NMR (162 MHz, C6D6):
4.8. Activation of phenyl trifluoromethyl sulfide
In a J. Young tube, phenyl trifluoromethyl sulfide (30
lL,
d 71.5 (d, JP–P = 18 Hz, JPt–P = 1779 Hz), 68.1 (s, JP–P = 18 Hz, JPt–P =
0.210 mmol) was added rapidly to a solution of 1 (40.7 mg,
3075 Hz).

S. Kundu et al. / Polyhedron 58 (2013) 99–105
105
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Acknowledgments
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Acknowledgment is made to the National Science Foundation
(CHE-1012405) for support of this work. The Center for Enabling
New Technologies through Catalysis (CENTC) Elemental Analysis
Facility is also acknowledged for use of its analytical facility
(CHE-0650456).
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Appendix A. Supplementary data
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CCDC 889623-889627 contains the supplementary crystallo-
graphic data for 2, 3, 4a, 5a, and 10. These data can be obtained free
of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at http://dx.doi.org/
10.1016/j.poly.2012.07.071.
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