Palladium and platinum pyrimidine-2-thionate complexes with diphosphines

Article abstract of DOI:10.1016/j.poly.2012.05.031

[MCl₂(P-P)] (M = Pd and Pt; P-P = dppe and dppm) reacts with NaC₄H₃SN₂, in a 1:2 molar ratio at room temperature, to give [M(S-C₄H₃SN₂) ₂(dppe)] [M = Pd (1); M = Pt, (2)], [Pd(S-C₄H ₃SN₂)₂(dppm)₂] (3) and trans-[Pt(S-C₄H₃SN₂)₂(dppm)] (5), as well as other by-products such as [Pd₂(S,N-C₄H ₃SN₂)₄] (4) and trans-[Pt(S-C₄H ₃SN₂)₂(PPh₂Me)₂] (6). A possible mechanism for the formation of 6, which requires cleavage of P-C bonds of the dppm ligands, is proposed.

Full text of DOI:10.1016/j.poly.2012.05.031

Polyhedron 43 (2012) 15–21
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Palladium and platinum pyrimidine-2-thionate complexes with diphosphines
b,
Susana Miranda a, Elena Cerrada b, Asunción Luquin b, Aránzazu Mendía a, , Mariano Laguna
⇑
⇑
a Departamento de Química, Área de Química Inorgánica, Facultad de Ciencias, Universidad de Burgos, 09001 Burgos, Spain
b Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Universidad de Zaragoza – C.S.I.C., 50009 Zaragoza, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
[MCl2(P–P)] (M = Pd and Pt; P–P = dppe and dppm) reacts with NaC4H3SN2, in a 1:2 molar ratio at room
temperature, to give [M(S-C4H3SN2)2(dppe)] [M = Pd (1); M = Pt, (2)], [Pd(S-C4H3SN2)2(dppm)2] (3) and
trans-[Pt(S-C4H3SN2)2(dppm)] (5), as well as other by-products such as [Pd2(S,N-C4H3SN2)4] (4) and
trans-[Pt(S-C4H3SN2)2(PPh2Me)2] (6). A possible mechanism for the formation of 6, which requires cleav-
age of P–C bonds of the dppm ligands, is proposed.
Received 25 April 2012
Accepted 17 May 2012
Available online 7 June 2012
Keywords:
Pyrimidine-2-thionate
Palladium
Ó 2012 Elsevier Ltd. All rights reserved.
Platinum
P–C cleavage
Dppm and dppe complexes
1. Introduction
[Pd(S-C4H3SN2)2(dppm)2] (3) was formed together with other by-
products such as [Pd2(S,N-C4H3SN2)4] (4) and trans-[Pt(S-
Complexes containing heterocyclic thionate ligands are still
attracting a great deal of interest as a result of their highly versatile
coordination properties, structures and applications [1–16]. Some
of us have reported this behaviour in palladium chemistry [17],
where pyridine-2-thionate coordinates as an S-monodentate,
C4H3SN2)2(PPh2Me)2] (6).
Formation of PPh2Me from the bis(diphenylphosphine)methane
ligand in trans-[Pt(S-C4H3SN2)2(PPh2Me)2] (6) has been observed in
related pyridine-2-thionate complexes [17] and requires the cleav-
age of a P–C bond in dppm. Some examples of the formation of
PPh2Me by cleavage of coordinated dppm [28–37] include the re-
cently reported complex [Pd2( 2-P,C-PPh2CHPOPh2)(
Cl(PPh2Me)] [38], which contains a l2-PPh2-CH– methanide ligand
l
2-S,N and l2
[Pd2( 2-S,N-C5H4NS)(l2
dinuclear complexes, such as [NaV(l2
(S,N-C5H4NS)(thf)2] [18] and [Ru2(l2
2S,
-j
2S bridging ligand in the same molecule, namely
l
-j
2S-C5H4NS)(
l
2-dppm)(S-C5H4NS)2]. Other
l
l2-dppm)
-
j
2S,
jN-C5H4 NS)3
-j
j
N-C5H4NS)2( 2-S,
l
that could be considered to be an intermediate in the formation of
N-C5H4NS)(S,N-C5H4NS)2](CF3SO3) [19], also show a similarly rich
coordination repertoire. Appealing structures with this ligand have
been reported for metals throughout the periodic table, for example
[Au(S-C5H4NS)2]ClO4 [20], which contains a chain of five gold atoms
with another unit in front of these, or [Pd2(S,N-C5H4NS)4] [21,22]
and [Pt2(S,N-p-MeC5H3NS)4] [23], both of which show similar lan-
tern-type structures to that proposed for [Pt2(S,N-C5H4NS)4].
Although the different coordination modes and structures are inter-
esting, the main motivation for research into these derivatives is
the growing awareness of properties of interest, such as anticarci-
nogenic activity [12,24–26].
6.
2. Results and discussion
The reaction of [MCl2(dppe)] [M = Pd or Pt, dppe = 1,2-
bis(diphenylphospine)ethane] with an ethanolic solution of so-
dium pyrimidine-2-thionate [Na(C4H3SN2)], prepared in situ from
equimolar amounts of pyrimidine-2-thiol (C4H4SN2) and NaOEt
in ethanol, in a 1:2 molar ratio, affords [Pd(S-C4H3SN2)2(dppe)]
(1) and [Pt(S-C4H3SN2)2(dppe)] (2) as yellow solids in good yields
(process i, Scheme 1).
As a result of our ongoing research in this field [17,24–27], here-
in we present new results obtained by treating pyrimidine-2-thio-
nate (C4H3SN2) with [MCl2(P–P)] (M = Pd and Pt; P–P = dppe and
dppm) derivatives in a 2:1 ratio. In most cases the corresponding
[M(S-C4H3SN2)2(P–P)] (1, 2, 5) complex was obtained, whereas
Complexes 1 and 2 show resonances due to the diphosphine
and a simple pattern (one doublet and one triplet) for the pyrimi-
dine-2-thionate ligand in their 1H NMR spectra. Both complexes
show a single resonance at d = 58.87 (1) and 45.80 ppm (2) in their
31P{1H} NMR spectra (in CDCl3). The presence of only one pair of
platinum satellites (1JP–Pt = 3057.6 Hz) for complex 2 points to a
mononuclear structure in solution. In the mass spectra, the base
peaks at m/z 615 for 1 and m/z 704 for 2, which correspond to
[Pd(S-C4H3SN2)(dppe)]+ and [Pt(S-C4H3SN2)(dppe)]+ fragments,
⇑
Corresponding authors.
E-mail addresses: amendia@ubu.es (A. Mendía), mlaguna@unizar.es (M. Laguna).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.05.031

16
S. Miranda et al. / Polyhedron 43 (2012) 15–21
N
N
N
N
N
N
N
Ph2
P
MePh2P
S
Ph2
P
S
S
S
S
Pt
N
S
N
Pt
M
PPh2Me
P
P
Ph2
Ph2
(6)
N
N
N
(5)
vi
M = Pd (1), Pt (2)
v
i
N
N
N
N
Ph2
N
N
S
N
S
N
S
Cl
P
N
ii
N
S
P
Pd
P
M
1/2
Ph2P
Ph2P Pd PPh2
+ 1/4
N
Pd
S
Pd
N
Cl
PPh
P
PPh2
S
N
S
Ph2
S
N
N
2 PPh2= dppm, dppe
N
N
N
(3)
N
(4)
N
N
N
iv
iii
Scheme 1. (i, ii, v) 2 NaC4H3SN2; (iii) 2 dppm; (iv) 4 PTA; (vi) NaC4H3SN2.
respectively, are in accordance with the proposed formula (loss of
one C4H3SN2 unit from the mononuclear species). In addition, the
IR spectrum shows two bands at 361 (m) and 337 (m) cmꢀ1 for 1
in low yield (6% based on platinum). As noted in the introduction,
theunusual formation of PPh2Me derivative 6 was also foundina sim-
ilar reaction involving pyridine-2-thionate [17].
and 359 (m) and 327 (m) cmꢀ1 for 2 assigned to
m
(M–S), as would
[Pt(S-C4H3SN2)2(dppm)] (5) shows a single resonance at
be expected for two mutually cis thionate ligands. The X-ray struc-
ture of 1 (see below) confirms this disposition. Similar reactions in
a 1:1 ratio afford complexes 1 and 2 together with unreacted start-
ing materials.
d = ꢀ49.4 ppm in the 31P{1H} NMR spectrum in CDCl3, thereby sug-
gesting a chelating coordination of the diphosphine ligand. Like-
wise, the presence of only a single pair of platinum satellites (1JP–
Pt = 2800.0 Hz) points to a mononuclear structure for 5 in solution.
Complex 6 was identified as trans-[Pt(S-C4H3SN2)2(PPh2Me)2] by
comparing its NMR and mass spectra with those for the product
obtained in 82% yield starting from cis-[PtCl2(PPh2Me)2]. It displays
a singlet at 7.15 ppm in the 31P{1H} NMR spectrum in CD2Cl2 with
only one system of platinum satellites (1JP–Pt = 2731.0 Hz). In addi-
tion to the corresponding resonances for the pyrimidine-2-thio-
nate ligand and the phenyl groups of the dppm molecule, a
pseudo-triplet signal at 2.09 ppm, with a small coupling constant
(2JH–P = 3.4 Hz), is observed in the 1H NMR spectrum. This signal
appears as a singlet with two satellites (3JH–Pt = 27.0 Hz) in the
1H{31P} NMR spectrum and can thus be assigned to the methyl
groups of the two PPh2Me ligands in the trans position as a result
of virtual coupling. The LSIMS+ mass spectrum, which shows frag-
ments at m/z (%) 506 (25) and 707 (100) assignable to [Pt(S-
C4H3SN2)(PPh2Me)]+ and [Pt(S-C4H3SN2)(PPh2Me)2]+, respectively,
points in a similar direction. The IR spectroscopic data of both sol-
ids in Nujol mull allowed us to identify the mutually cis S-C4H3SN2
Changing the diphospine to 1,10-bis(diphenylphospine)methane
(dppm) instead of 1,2-bis(diphenylphospine)ethane (dppe) gave
more complicated results. Thus, treatment of [PdCl2(dppm)] with
an ethanolic solution of Na(C4H3SN2), in a 1:2 molar ratio, afforded
trans-[Pd(S-C4H3SN2)2(dppm)2] (3) (process ii, Scheme 1) rather
than the expected cis-[Pd(S-C4H3SN2)2(dppm)] or more compli-
cated structures obtained with pyridine-2-thionate [17]. Complex
3 shows two doublets at 27.07 and ꢀ24.90 ppm (2JP–P = 75.4 Hz)
in its 31P{1H} NMR spectrum, thus indicating the non-equivalence
of the two P atoms, the latter of which does not coordinate. Inte-
gration of the 1H NMR resonances of the pyrimidine-2-thionate
groups and the methylene protons of the dppm ligand shows a
1:1 ratio for both ligands. In addition, the single m(Pd–S) vibration
observed at 343 (m) cmꢀ1 in the IR spectrum of 3 points to a trans
disposition of the sulfur ligands. All these findings were confirmed
by the X-ray structure of this complex (see below).
In light of the stoichiometry of the reaction, the formation of
trans-[Pd(S-C4H3SN2)2(dppm)2] (3) requires a low yield (less than
50%; experimental yield: 41%) and the formation of additional
products (process ii, Scheme 1). The remaining complex should
correspond to [Pd2(S,N-C4H3SN2)4] (4), which is indeed isolated
in low yield from the mother liquor. The analyses and mass spec-
trum (LSIMS+) correspond to those reported for this complex
[39], with 1H NMR resonances at 8.13 and 6.63 ppm as broad sig-
nals in 2:1 ratio. The mass spectrum shows signals at m/z 658
(25%) [Pd2(C4H3SN2)4]+ and 545 (30%) [Pd2(C4H3SN2)3]+. [Pd2(S,N-
C4H3SN2)4] (4) reacts with 1,10-bis(diphenylphospine)methane
(dppm) (process iii, Scheme 1) or 1,3,5-triaza-7-phosphadaman-
tane (PTA) in an NMR tube to give trans-[Pd(S-C4H3SN2)2(dppm)2]
(3) or previous reported trans-[Pd(S-C4H3SN2)2(PTA)2] [27] (pro-
cess iv, Scheme 1)) respectively, as deduced from their 1H and
31P{1H} NMR spectra.
groups in 5 [353(m), 328(m),
in 6 [349(m), (Pt–S)].
m(Pt–S)] and their trans counterparts
m
The reaction of [PtCl2(dppm)] with an ethanolic solution of
Na(C4H3SN2), in a 1:1 molar ratio, affords [Pt(S-C4H3SN2)2(PPh
2Me)2] (6) (process vi, Scheme 1) instead of the expected product
[PtCl(S-C4H3SN2)(dppm)]. As noted above and in the introduction,
the formation of 6 is noteworthy as it mimics the reactivity ob-
served when using pyridine-2-thionate, which gives [Pt(S-
C5H4SN)2(PPh2Me)2] [17]. The transformation of dppm into the
phosphine PPh2Me occurs preferably with
a dppm/thionate
(pyrimidine-2-thionate or pyridine-2 thionate) ratio of 1:1. The
mother liquor of the latter preparation of 6 shows a mixture in
the 31P{1H} NMR spectrum, with the main signal centred at
32.4 ppm as a singlet with no platinum satellites. The 1H NMR
spectrum displays two multiplets at 7.75 and 7.40 ppm, respec-
tively, which can be assigned to the aromatic protons, one quintu-
plet at 4.04 ppm for a –CH2– group, and one triplet at 1.31 ppm
for a –CH3 group. The 1H{31P} NMR spectrum differs in that the
quintuplet is now a quadruplet whose four signals integrate
The reaction of [PtCl2(dppm)] with an ethanolic solution of
Na(C4H3SN2), in a 1:2 molar ratio, affords [Pt(S-C4H3SN2)2(dppm)]
(5) (process v, Scheme 1) in good yield, with [Pt(S-C4H3
SN2)2(PPh2Me)2] (6) being isolated as a secondary reaction product

S. Miranda et al. / Polyhedron 43 (2012) 15–21
17
4:6:2:3. All these data agree with the presence of free [OP-
Ph2(OCH2CH3)] in the reaction solution [38].
The preparation of 6 by this method (35% yield) requires a
recrystallisation step as the LSIMS+ shows other ions assignable
to [Pt(C4H3SN2)(PPh2OCH2CH3)(PPh2Me)]+ (m/z 736, 30%) and
[Pt(C4H3SN2)(PPh2OCH2CH3)2]+ (m/z 766, 25%) in addition to those
expected for [Pt(S-C4H3SN2)2(PPh2Me)2] (6). The presence of
PPh2(OCH2CH3) in the solid, and that of [OPPh2(OCH2CH3)] in the
mother liquor, probably as a result of oxidation of the former, sug-
gests that these species play a role in the reaction mechanism. The
formation of PPh2Me by base-promoted cleavage of a P–C bond in
dppm complexes has been reported previously [32–37].
The formation of [Pt(S-C4H3SN2)2(PPh2Me)2] (6) or [Pt(S-
C5H4SN)2(PPh2Me)2] [17] requires the cleavage of two dppm mol-
ecules and only takes place when one equivalent of NaC4H3SN2
or NaC5H4SN is added to [PtCl2(dppm)]. Taken together, these find-
ings suggest that the process should progress via a dinuclear com-
plex with dppm and 2-thionate ligands similar to previously
isolated 2-thiolpyridine palladium derivatives [17] (Scheme 2).
Fig. 1. Structure of the two independent molecules in complex 1. Thermal
ellipsoids are drawn at the 50% probability level and H atoms have been omitted
for clarity. Selected bond lengths [Å] and angles [°] #1ꢀx + 1, y, ꢀz + 1/2; #2ꢀx + 2, y,
ꢀz + 1/2: Pd(1)–P(1)#1 2.2554(18), Pd(1)–P(1) 2.2554(18), Pd(1)–S(1) 2.3834(18),
Pd(1)–S(1)#1 2.3834(18), Pd(2)–P(2) 2.2698(17), Pd(2)–P(2)#2 2.2698(17), Pd(2)–
S(2) 2.3803(18), Pd(2)–S(2)#2 2.3803(18), P(1)#1–Pd(1)–P(1) 85.15(9), P(1)#1–
Pd(1)–S(1) 175.03(7), P(1)–Pd(1)–S(1) 90.71(7), P(1)#1–Pd(1)–S(1)#1 90.71(7),
P(1)–Pd(1)–S(1)#1 175.03(7), S(1)–Pd(1)–S(1)#1 93.55(10), P(2)–Pd(2)–P(2)#2
84.46(9), P(2)–Pd(2)–S(2) 175.89(6), P(2)#2–Pd(2)–S(2) 92.49(7), P(2)–Pd(2)–
S(2)#2 92.49(7), P(2)#2–Pd(2)–S(2)#2 175.89(6), S(2)–Pd(2)–S(2)#2 90.69(10).
This dinuclear species could then afford a l2-C,P methanide in ba-
sic medium [28,37,38,40]. After oxidation of the free PPh2, the
nucleophilic addition of OCH2CH3 to P could result in the formation
of [OPPh2(OCH2CH3)] and the carbanion PPh2–CH2 by cleavage of
the P–C bond. Subsequent protonation would produce the PPh2Me
derivative 6. The proposed mechanism contains similarities to that
proposed by Pringle and co-workers [37], and some of us in the re-
cent
characterisation
of
[Pd2(l2-P,C-PPh2CHPOPh2)(l2-
dppm)Cl(PPh2Me)] [38].
Pd–S and Pd–P bond lengths are similar to those reported in re-
lated phosphine–pyrimidine complexes [42–44]. The disposition
The structures of palladium and platinum complexes 1, 3, 5 and
6 were determined by single-crystal X-ray structure analyses. The
ORTEP drawings and crystal packing diagrams are displayed in
Figs. 1–5.
of both molecules leads to
p–p interactions between two phenyl
rings of the dppe ligand of each molecule (closest centroid. . .cen-
troid distance: 4.0024 Å; interplanar angle: 3.31°; perpendicular
distances of 3.443 Å with slippage of 3.542 Å). The structure of this
compound has been published recently as a unique molecule with
different unit cell dimensions (a = 8.5596(6), b = 1.5787(8),
c = 35.291(3) Å) and crystal system and space group (monoclinic,
P21/n) [42].
The structure of the dichloromethane solvate of complex 3 con-
tains a centrosymmetric monomer [Pd(S-C4H3SN2)2(dppm)2] in
which the two dppm bisphosphine ligands are connected to the
palladium centre through one phosphorus atom in a terminal
The chloroform solvate of complex 1 contains two nearly iden-
tical centrosymmetric molecules in the asymmetric unit cell. The
bisphosphine dppe ligand is coordinated to the metallic centre in
a chelate fashion and the two pyrimidine-2-thionato ligands,
which coordinate via their sulfur atoms, are in an anti configura-
tion. The structure of both molecules is similar to that reported
previously for [Pd(S-C5H4NS)2(dppe)], which contains a pyridine-
2-thionate ligand [41]. The geometry around the two Pd centres
is distorted square planar with essentially identical bisphosphine
bite angles [P–Pd(1)–P 85.15(9)° and P–Pd(2)–P 84.46(9)°]. The
P(O)Ph2
PPh2
Ph2P
N
Ph2P
N
N
S
Pt
N
S
Pt
Pt
N
N
Pt
S
S
N
N
Ph2P
PPh2
Ph2P
PPh2
CH2
P(O)Ph2
P(O)Ph2OEt
N
Ph2P
Ph2P
N
N
N
S
Pt
S
Pt
N
Pt
PPh2
Pt
N
S
S
N
N
PPh2
H2C
Ph2(O)P
Scheme 2. Proposed mechanism for the formation of 6.

18
S. Miranda et al. / Polyhedron 43 (2012) 15–21
176.57(4)° and P(2)–Pt–S(1) 177.39(4)°]. The main distortion arises
due to narrowing of the P–Pt–P angle to 73.68(4)° due to the small
bite angle of the diphosphine. The metal centre deviates from the
plane of the five atoms by 0.0122 Å. The Pt–P distances of
2.2671(10) and 2.2697(10) Å are similar to those found in related
complexes with a chelating dppm ligand and sulfur donor ligands
[17,45–49]. The Pt–S bond lengths of 2.3520(10) and 2.3400(10) Å
are in the range of other Pt derivatives with pyrimidine-2-thionato
as a terminal ligand [41,42,50–52]. In addition, it can be seen
(Fig. 4) that the packing of individual molecules is influenced by
long inter-phenyl ring interactions in the unit cell (closest cen-
troid. . .centroid distances of 4.297 Å, interplanar angle of 0.02°,
perpendicular distances of 3.325 Å with slippage of 2.723 Å). This
structure has previously been reported [42] as a centrosymmetric
molecule with slight differences in the crystal dimensions since
complex 5 is a dichloromethane solvate.
Complex 6 is a centrosymmetric monomer with two methyldi-
phenylphosphine molecules and two pyrimidine-2-thionato li-
gands in the trans position. The structure is analogous to that
previously reported by us with pyridine-2-thionato as a ligand
[17]. The platinum centre displays a distorted square-planar geom-
etry with P–Pt–S angles of 95.70(4)° [P(1)#1–Pt(1)–S(1)#1] and
84.30(4)° [P(1)–Pt(1)–S(1)#1]. The Pt–S and Pt–P distances of
2.3380(12) and 2.3137(11) Å, respectively, are slightly shorter than
those observed in the previously reported derivative but are in the
same range as those for pyrimidine-2-thionato platinum com-
plexes with P-donor ligands [24,42].
Fig. 2. Structure of complex 3. Thermal ellipsoids are drawn at the 50% probability
level and H atoms have been omitted for clarity. Selected bond lengths [Å] and
#
angles [°] ꢀx + 1, ꢀy + 1, ꢀz + 1: Pd(1)–S(1) 2.3346(9), Pd(1)–P(1) 2.3435(9),
S(1)#1–Pd(1)–S(1) 180.00(1), S(1)#1–Pd(1)–P(1) 86.09(3), S(1)–Pd(1)–P(1)
93.91(3), S(1)#1–Pd(1)–P(1)#1 93.91(3), S(1)–Pd(1)–P(1)#1, 86.09(3), P(1)–Pd(1)–
P(1)#1 180.0, C(7)–P(1)–Pd(1) 113.85(12).
3. Conclusions
In conclusion, we have show that the chemistry with pyrimi-
dine-2-thionate, NaC4H3SN2, and [MCl2(P–P)] derivatives (M = Pd,
Pt and P–P = dppe and dppm) differs slightly from that shown with
pyridine-2-thionate, NaC5H4SN. However, the formation of PPh2Me
derivatives
[Pt(S-C4H3SN2)2(PPh2Me)2]
(6)
and
[Pt(S-
C5H4SN)2(PPh2Me)2] from [PtCl2(dppm)] and both thionates, in a
1:1 ratio, appears to be a general reaction that occurs in good yield
(based on dppm) and which requires cleavage of the P–C bond of
the two starting diphosphine ligands.
Fig. 3. ORTEP plot (50% thermal ellipsoids) of the X-ray crystal structure of complex
5. H atoms have been omitted for clarity. Selected bond lengths [Å] and angles [°]:
Pt(1)–P(2) 2.2671(10), Pt(1)–P(1) 2.2697(10), Pt(1)–S(1) 2.3400(10), Pt(1)–S(2)
2.3520(10), S(1)–C(1) 1.747(4), S(2)–C(5) 1.750(4), P(2)–Pt(1)–P(1) 73.68(4), P(2)–
Pt(1)–S(1) 177.39(4), P(1)–Pt(1)–S(1) 103.80(4), P(2)–Pt(1)–S(2) 103.42(4), P(1)–
Pt(1)–S(2) 176.57(4), S(1)–Pt(1)–S(2) 79.12(4).
4. Experimental
4.1. General procedures and materials
4.1.1. Chemicals
Pyrimidine-2-thione (C4H4SN2) (Aldrich), Na (Aldrich), dppm,
dppe or PPh2Me (Aldrich) were used as received. Platinum and
PdCl2 were procured from INCOMETAL, S.A. Reagent grade diethyl
ether, hexane or dichloromethane were dried using standard pro-
cedures and freshly distiled immediately before use. Absolute eth-
anol was deoxygenated with an N2 purge. The complexes
[PtCl2(dppm)], [PtCl2(dppe)], [PdCl2(dppm)] and [PdCl2(dppe)]
were prepared by adding the appropriate diphosphine ligand to a
solution of [PtCl2(COD)] or [PdCl2(NCPh)2]. These two reagents
were prepared by literature routes or slight variations thereof
[53,54]. All starting manipulations were carried out under a nitro-
gen atmosphere using a Schlenk line and syringe techniques.
disposition (Pd1–P1 bond length of 2.3435(9) Å). The second phos-
phorus atom of the bisphosphine is too far from the metallic centre
to interact (P2–Pd1 distance of 4.354 Å), although it displays short
interactions with the solvent molecule (P. . .H–C = 2.961 Å) that
could be considered to be of the hydrogen bonding type. The two
pyrimidine-2-thionato ligands coordinate via their sulfur atoms
in an anti configuration are nearly perpendicular to the Pd-dppm
plane (dihedral angle: 85.1°). The Pd–S and Pd–P distances of
2.3346(9) and 2.3435(9) Å, respectively, are similar to those found
in complex 1 and are in the range of previously reported phos-
phine–palladium derivatives with pyridine-2-thionate as a termi-
nal ligand [17,27,41].
The basic structural unit of the dichloromethane solvate of com-
plex 5 is a monomer [Pt(S-C4H3SN2)2(dppm)] similar to that of
(bisdiphenylphosphinemethane)bis(pyridine-2-thionato)plati-
num(II) [17]. Similarly to a previously reported Pt complex, the two
pyrimidine-2-thionato ligands are in a syn configuration, although
in this case one of the ligands is nearly coplanar with the PtS2P2
plane (dihedral angle: 1.6°). The metal centre has a distorted
square-planar geometry with similar P–Pt–S angles [P(1)–Pt–S(2)
4.1.2. Physical measurements
1H and 31P NMR spectra were recorded on a Varian Unity
300 MHz or INOVA 400 MHz for 1H and 121.4 MHz or 161.9 MHz
for 31P, in CDCl3 or CD2Cl2 solutions; 1H chemical shifts are quoted
relative to tetramethylsilane (internal reference) and H3PO4
respectively (external references). IR spectra were recorded on a
Perkin Elmer 843 (range 4000–200 cmꢀ1) and/or a Nicolet Impact

S. Miranda et al. / Polyhedron 43 (2012) 15–21
19
Fig. 4. View of the packing in the unit cell.
(c ꢁ 5.10ꢀ4 M). The C, H, N and S analyses were performed with a
LECO CHNS 932 microanalyser. Mass spectra were recorded on a
VG Autospec, by LSIMS+ using nitrobenzylalcohol as matrix. The
X-ray intensity data were collected with a Bruker-Smart CCD or
Bruker-Smart Apex CCD diffractometer with graphite-monochro-
mated radiation Mo Ka (k = 0.71073 Å).
4.1.3. Syntheses
4.1.3.1. Preparation of [M(S-C4H3SN2)2(dppe)] M = Pd (1) and Pt
(2). NaC4H3SN2 (0.49 mmol)—prepared in situ from NaEtO 0.1 M
(4.9 mL, 0.49 mmol) and C4H4SN2 (55.60 mg, 0.49 mmol) in abso-
lute CH3CH2OH (20 mL)—was added to
a
suspension of
[PdCl2(dppe)] (143 mg, 0.25 mmol) or [PtCl2(dppe)] (150 mg,
0.25 mmol) in absolute ethanol (20 mL) under inert atmosphere
conditions. A pale or deep bright yellow solution was formed
immediately and the white solid in suspension remained mixed.
After stirring for 48 h at room temperature, the solvent of yellow
solution was removed partially to concentrate the suspension to
ca. 5 mL. The solid was filtered off and washed with absolute
ethanol.
Fig. 5. Molecular structure of complex 6. Thermal ellipsoids are drawn at the 50%
probability level and H atoms have been omitted for clarity. Selected bond lengths
#
[Å] and angles [°] ꢀx + 1, ꢀy + 2, ꢀz: Pt(1)–P(1)#1 2.3137(11), Pt(1)–P(1)
2.3137(11), Pt(1)–S(1)#1 2.3380(12), Pt(1)–S(1) 2.3380(12), S(1)–C(14) 1.747(4),
P(1)#1–Pt(1)–P(1) 180.0, P(1)#1–Pt(1)–S(1)#1 95.70(4), P(1)–Pt(1)–S(1)#1
84.30(4), P(1)#1–Pt(1)–S(1) 84.30(4), P(1)–Pt(1)–S(1) 95.70(4), S(1)#1–Pt(1)–S(1)
180.00(5).
4.1.3.2. [Pd(S-C4H3SN2)2(dppe)] (1). Yellow solid in 82% yield. Anal.
Calc. for C34H30PdN4P2S2: C, 56.16; H, 4.16; N, 7.70; S, 8.82. Found:
C, 56.29; H, 4.42; N, 7.50; S, 9.18%. KM
(X
ꢀ1 cm2 molꢀ1): 1.26. IR (Nu-
jol mull, cmꢀ1): (C4H3SN2) 1557 (vs), 1527 (vs)
m
(C@C + C@N); 1188
(P–S); 361 (m), 337 (Pd–S). 1H NMR (d, in CDCl3):
7.88 (d, JH–H = 4.5 Hz, 4H, C4H3SN2), 7.84 (m, 8H, Ph), 7.37 (m,
p
(s), 1172 (vs)
m
410 FTIR (range 4000–400 cmꢀ1) spectrophotometer using Nujol
mulls between polyethylene sheets. Conductivity measurements
were performed at 298 K using a Crison 522 conductimeter
3
3
3
12H, Ph), 6.40 (t, JH–H = 4.5 Hz, 2H, C4H3SN2), 2.37 (d, JH–
P = 21.0 Hz, 4H, –CH2–, dppe). 1H{31P} NMR (d, in CDCl3): 2.37 (s,

20
S. Miranda et al. / Polyhedron 43 (2012) 15–21
2H, –CH2–, dppe). 31P{1H} NMR (d, in CDCl3): 58.87 (s). MS-LSIMS+
(m/z): 615 ([Pd(C4H3SN2)(dppe)]+, 100%).
4.1.3.5. Preparation of [Pt(S-C4H3SN2)2(dppm)] (5). NaC4H3SN2
(0.31 mmol)—prepared in situ from NaEtO 0.1 M (3.1 mL,
0.31 mmol) and C4H4SN2 (35.02 mg, 0.310 mmol) in absolute
CH3CH2OH (20 mL)—was added to a suspension of [PtCl2(dppm)]
(101 mg, 0.16 mmol) in absolute CH3CH2OH (20 mL) under inert
atmosphere conditions. A pale bright yellow solution was formed
immediately and the white solid in suspension remained mixed
with a pale yellow solid. After stirring for 24 h at room tempera-
ture, the solvent was removed partially to concentrate the suspen-
sion to ca. 5 mL. The solid was filtered off and washed with
absolute ethanol to produce a pale yellow crystalline solid in 80%
yield. Anal. Calc. for C33H28PtN4P2S2: C, 49.43; H, 3.52; N, 6.99; S,
8.00. Found: C, 49.08; H, 3.62; N, 6.95; S, 7.98%. KM
4.1.3.3. [Pt(S-C4H3SN2)2(dppe)] (2). Pale yellow crystalline solid in
88% yield. Anal. Calc. for C34H30PtN4P2S2: C, 50.06; H, 3.71; N,
6.87; S, 7.86. Found: C, 50.01; H, 3.76; N, 7.14; S, 7.44%. KM
(X
ꢀ1 cm2 molꢀ1): 0.72. IR (Nujol mull, cmꢀ1): (C4H3SN2) 1561
(vs), 1538 (vs)
(m), 327 (m)
m(C@C + C@N); 1186 (vs), 1176 (vs) m(C@S); 359
m
(Pt–S). 1H NMR (d, in CDCl3): 7.84 (m, 8H, Ph),
3
7.34 (m, 16H, C4H3SN2, Ph), 6.39 (t, JH–H = 4.8 Hz, 2H, C4H3SN2),
2
2.27 (d, JH–P = 18.0 Hz, 4H, –CH2–, dppe). 1H{31P} NMR (d, in
CDCl3): 2.27 (s, JH–Pt = 43.5 Hz, 4H, –CH2–, dppe). 31P{1H} NMR
3
1
(d, in CDCl3): 45.8 (s, JP–Pt = 3057.6 Hz). MS-LSIMS+ (m/z): 704
([Pt(C4H3SN2)(dppe)]+, 100%).
(X
ꢀ1 cm2 molꢀ1): 0.46. IR (Nujol mull, cmꢀ1): (C4H3SN2) 1558
(vs), 1540 (vs) (C@C + C@N); 1183 (vs), 1174 (vs) (C@S); 353
(m), 328 (m)
(Pt–S). 1H NMR (d, in CDCl3): 7.88 (m, 8H, Ph),
m
m
4.1.3.4.
Preparation
of
trans-[Pd(S-C4H3SN2)2(dppm)2]
m
3
(3). NaC4H3SN2 (0.36 mmol)—prepared in situ from NaEtO 0.1 M
(3.6 mL, 0.36 mmol) and C4H4SN2 (40.0 mg, 0.36 mmol) in absolute
CH3CH2OH (20 mL)—was added to a suspension of [PdCl2(dppm)]
(100 mg, 0.18 mmol) in absolute CH3CH2OH (20 mL) under inert
atmosphere conditions. An orange solution with a yellow solid in
suspension was formed immediately and the starting white solid
in suspension is going gradually to disappear. After stirring for
24 h at room temperature, the yellow solid was filtered off and
washed with absolute ethanol to produce an intense yellow crys-
talline solid 3 in 41% yield. Anal. Calc. for C58H50PdN4P4S2: C,
63.47; H, 4.59; N, 5.1; S, 5.84. Found: C, 63.08; H, 4.62; N, 4.95;
7.60 (d, JH–H = 5.0 Hz, 4H, C4H3SN2), 7.29 (m, 12H, Ph), 6.26 (t,
2
3JH–H = 5.0 Hz, 2H, C4H3SN2), 4.23 (t, JH–P = 10.0 Hz, 2H, –CH2–,
3
dppm). 1H{31P} NMR (d, in CDCl3): 4.23 (s, JH–Pt = 60.0 Hz, 2H, –
1
CH2–, dppm). 31P{1H} NMR (d, in CDCl3): ꢀ49.4 (s, JP–Pt
=
2800.0 Hz). MS-LSIMS+ (m/z): 690 [Pt(C4H3SN2)(dppm)]+, 100%].
From the mother liquor by evaporation to dryness and washing
with hexane a pale yellow complex was obtained. It was character-
ised by elemental analysis, 1H and 31P NMR as compound 6 in 6%
yield.
S, 5.98%. KM
(C4H3SN2) 1556 (vs), 1528 (vs)
(C@S); 343 (m)
(Pd–S). 1H NMR (d, in CDCl3): 7.90 (d, JH–
(
X
ꢀ1 cm2 molꢀ1): 1.3 IR (Nujol mull, cmꢀ1):
(C@C + C@N); 1172 (vs), 1157 (s)
4.1.3.6. Preparation of trans-[Pt(S-C4H3SN2)2(PPh2Me)2] (6). Na
C4H3SN2 (0.44 mmol)—prepared in situ from NaEtO 0.1 M (4.4 mL,
0.44 mmol) and C4H4SN2 (50.0 mg, 0.44 mmol) in absolute
m
3
m
m
H = 4.9 Hz, 4H, C4H3SN2), 7.76 (m, 16H, Ph), 7.24 (m, 24H, Ph),
CH3CH2OH (20 mL)—was added to
a
suspension of cis-
3
6.53 (t, JH–H = 4.9 Hz, 2H, C4H3SN2), 3.49 (br, 4H, –CH2–, dppm).
[PtCl2(PPh2Me)2] (135 mg, 0.20 mmol) in absolute CH3CH2OH
(20 mL) under inert atmosphere conditions. A pale bright yellow
solution was formed and it became totally clear in 15 min. After
stirring for 1 h at room temperature, the solution was concentrated
to ca. 5 mL under vacuum and the pale yellow solid precipitate was
isolated by filtration, washed with absolute ethanol (3 mL) and ob-
tained in 82% yield. Anal. Calc. for C34H32PtN4P2S2: C, 49.93; H, 3.94;
N, 6.85; S, 7.84. Found: C, 49.60; H, 4.13; N, 6.74; S, 8.11%. KM
1H{31P} NMR (d, in CDCl3): 3.49 (s, –CH2–, dppm). 31P{1H} NMR
2
2
(d, in CDCl3): 27.07 (d, JP–P = 75.4 Hz, dppm), ꢀ24.90 (d, JP–
P = 75.4 Hz, dppm). MS-LSIMS+ (m/z): 601 ([Pd(C4H3SN2)(dppm)]+,
100%).
From the mother liquor by addition of 40 mL of hexane a new
crop of complex 3 with other component 4 were isolated. Pure
complex [Pd2(S,N-C4H3SN2)4] (4) was isolated in 10% yield by
evaporation to 5 mL of the remaining solution. Anal. Calc. for
(X
ꢀ1 cm2 molꢀ1): acetone, 1.7. IR (Nujol mull, cmꢀ1): (C4H3SN2)
C
16H12Pd2N8S4: C, 29.23; H, 1.84; N, 17.04; S, 19.51. Found: C,
1558 (s), 1535 (s) m(C@C + C@N); 1178 (s), 1176 (s) m(C@S); 349
3
29.20; H, 1.90; N, 17.12; S, 19.37%. 1H NMR (d, in CDCl3): 8.13 (s,
br, 8H, C4H3SN2), 6.63 (s, br, 4H, C4H3SN2). MS-LSIMS+ (m/z): 658
([Pd2(C4H3SN2)4]+, 25%), 545 ([Pd2(C4H3SN2)3]+, 30%).
(m)
m
(Pt–S). 1H NMR (d, in CDCl3): 7.92 (d, JH–H = 4.70 Hz, 4H,
3
C4H3SN2), 7.68 (m, 8H, Ph), 7.24 (m, 12H, Ph), 6.51 (t, JH–H
4.70 Hz, 2H, C4H3SN2), 2.09 (t, JH–P = 3.40 Hz, JH–Pt = 27.0 Hz, 6H,
=
2
3
Table 1
Summary of crystallographic data for complexes 1, 3, 5 and 6.
1
3
5
6
Empirical formula
Formula weight
Crystal system
Space group
Z
C
36H32Cl6N4P2PdS2
C60H54Cl4N4P4PdS2
1267.27
C34H30Cl2N4P2PtS2
886.67
C34H32N4P2PtS2
817.79
monoclinic
P21/n
965.82
monoclinic
P2/c
triclinic
triclinic
ꢀ
ꢀ
P1
P1
4
1
2
2
a (Å)
b (Å)
c (Å)
16.8779(18)
8.7458(9)
28.288(3)
90
96.596(2)
90
10.7991(10)
12.0761(11)
12.9680(11)
100.906(2)
96.652(2)
115.9600(10)
1454.8(2)
1.447
9.0965(8)
11.6472(10)
16.8694(14)
82.882(2)
79.736(2)
76.6890(10)
1705.0(3)
1.727
8.8880(11)
11.7165(15)
15.706(2)
90.00
101.897(2)
90.00
a
(°)
b (°)
c
(°)
V (Å3)
4148.0(8)
1.547
1600.4(4)
1.697
Dcalc (mg mꢀ3
)
Crystal size (mm)
T (K)
0.40 ꢂ 0.20 ꢂ 0.10
0.20 ꢂ 0.10 ꢂ 0.10
0.28 ꢂ 0.213 ꢂ 0.07
0.30 ꢂ 0.20 ꢂ 0.15
298(2)
293(2)
298(2)
293(2)
Rint
0.0738
0.0455
0.0335
0.0543
R1(Fo)a, wR2(Fo
)
(I > 2
r)
0.0684, 0.1910
0.0989, 0.2127
759065
0.0407, 0.1097
0.0560, 0.1340
759066
0.0327, 0.0657
0.0421, 0.0693
759067
0.0255, 0.0654
0.0365, 0.0691
759068
2
b
R1(Fo), wR2(Fo2) (all data)
CCDC No.
a
R1(F) =
-
R
||Fo|ꢀ|Fc||/
R|Fo|.
b
2
R2 (F2) = [
R
[
-
(Fo ꢀFc2)2]/ [w(Fo2)2]1/2, wꢀ1 = [r2 (Fo2)+( P)2+bp], where P = [max (Fo2, 0)+2Fc2)]/3.
R a

S. Miranda et al. / Polyhedron 43 (2012) 15–21
21
3
–CH3). 1H{31P} NMR (d, in CD2Cl2): 2.09 (s, JH–Pt = 27.0 Hz, 6H, –
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CH3). 31P{1H} NMR (d, in CD2Cl2): 7.15 (s, JP–Pt = 2731.0 Hz). MS-
1
FAB+ (m/z): 506 ([Pt(C4H3SN2)(PPh2Me)]+, 25%), 707 ([Pt(C4
H3SN2)(PPh2Me)2]+, 100%). NaC4H3SN2 (0.155 mmol)—prepared
in situ from NaEtO 0.1 M (1.55 mL, 0.155 mmol) and C4H4SN2
(17.52 mg, 0.165 mmol) in absolute CH3CH2OH (20 mL)—was
added to a suspension of [PtCl2(dppm)] (101 mg, 0.16 mmol) in
absolute CH3CH2OH (20 mL) under inert atmosphere conditions. A
pale bright yellow solution was formed and it became totally clear
in 15 min. After stirring for 1 h at room temperature, the solution
was concentrated to ca. 3 mL under vacuum and the pale yellow so-
lid precipitate was isolated by filtration. Recrystallisation in dichlo-
romethane-ethanol affords 6 in 35% yield.
4.2. X-ray structure determinations of 1, 3, 5, and 6
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151.
Pale yellow 1 and 3, yellow 5 and 6 suitable for X-ray diffrac-
tion, were grown by slow diffusion of hexane or ether into a CH2Cl2
solution of 3 and 5 or into CHCl3 for 1 and 6. A crystal of each com-
pound was mounted on a glass fibre with inert oil and centred in a
Bruker-Smart CCD area-detector diffractometer with graphite-
monochromated Mo K
a radiation (l = 0.7107 Å) [55] for data col-
lection at 298 K for 1 and 5, and 293 K for 3 and 6. Intensities were
integrated [56] from several series of exposures, each exposure
covering 0.3° in
x, and the total data set being a sphere. Absorption
corrections were applied, based on multiple and symmetry-equiv-
alent measurements [57]. The structures were solved by direct
methods and by Patterson in the case of complex 3 and refined
by least squares on weighted F2 values for all reflections [58–60].
All non-hydrogen atoms were assigned anisotropic displacement
parameters and refined without positional constraints. All hydro-
gen atoms were constrained to ideal geometries and refined with
fixed isotropic displacement parameters. A summary of the funda-
mental crystal and refinement data of the compounds is given in
Table 1.
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Acknowledgements
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Financial support from MICINN Spain and FEDER (BQU2008-
08099-CO3-01) and JCyL—Spain—(BU15/03) is gratefully
acknowledged.
[46] P.C.B. Page, S.S. Klair, M.P. Brown, M.M. Harding, C.S. Smith, S.J. Maginn, S.
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Appendix A. Supplementary data
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Tetrahedron 48 (1992) 5933.
[51] D.M.L. Goodgame, A.M.Z. Slawin, D.J. Williams, P.W. Zard, Inorg. Chim. Acta
148 (1988) 5.
CCDC 759065–759068 contain the supplementary crystallo-
graphic data for 1, 3, 5, and 6. 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.
[52] B.-C. Tzeng, W.-F. Fu, C.-M. Che, H.-Y. Chao, K.-K. Cheung, S.-M. Peng, J. Chem.
Soc., Dalton Trans. (1999) 1017.
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[54] G.K. Anderson, M. Lin, Inorg. Synth. 28 (1990) 60.
[55] SMART diffractometer control software, Bruker Analytical X-Ray Instruments
Inc., Madison, WI, 2000.
[56] SAINT integration software, Siemens Analytical X-Ray Instruments Inc.,
Madison, WI, 2000.
[57] G.M. Sheldrick, SADABS, Empirical Absorption Program, University of Göttingen,
Göttingen, Germany, 1996.
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