Reaction of a heterotopic P,SAs ligand with group 10 metal(ii) complexes: As-S bond cleavage and the formation of two unusual trinuclear structural isomers for Pd and Pt

Article abstract of DOI:10.1039/c2dt12506d

The synthesis of the heterotopic P,SAs ligand, 1-Ph₂AsSC ₆H₄-2-PPh₂ (1) and its reaction with [PdCl ₂(cod)], [PtI₂(cod)] (cod = 1,5-cyclooctadiene) and NiCl₂·6H₂O is reported. Cleavage of the As-S bond of 1 and coordination of the resulting phosphanylthiolato ligand (SC ₆H₄-2-PPh₂)^- (SC₆H ₄-2-PPh₂ = P,S) was observed with formation of [M(P,S)₂] (M = Ni, Pd, Pt). In the case of Pd and Pt, not only the mononuclear complexes [M(P,S)₂] formed, but also the trimers of [MX(P,S)] ([MX{(μ-S-SC₆H₄-2-PPh₂)- κ²S,P}]₃ [M = Pd, X = Cl (2) and M = Pt, X = I (4)]). Formation of 2 and 4 was preceded by the trinuclear isomeric intermediates [(cis-M{(μ-S-SC₆H₄-2-PPh ₂)-κ²S,P}₂)-MX₂-MX{(μ-S- SC₆H₄-2-PPh₂)-κ²S,P}] [M = Pd, X = Cl (3) and M = Pt, X = I (5)]. The crystal structures of 1-5 and a possible reaction mechanism that leads to 2 and 4 are presented.

Full text of DOI:10.1039/c2dt12506d

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PAPER
Reaction of a heterotopic P,SAs ligand with group 10 metal(II) complexes:
As–S bond cleavage and the formation of two unusual trinuclear structural
isomers for Pd and Pt†
Imola Sárosi,a,b Alexandra Hildebrand,b Peter Lönnecke,b Luminiţa Silaghi-Dumitrescu*a and
Evamarie Hey-Hawkins*b
Received 29th December 2011, Accepted 1st February 2012
DOI: 10.1039/c2dt12506d
The synthesis of the heterotopic P,SAs ligand, 1-Ph2AsSC6H4-2-PPh2 (1) and its reaction with
[PdCl2(cod)], [PtI2(cod)] (cod = 1,5-cyclooctadiene) and NiCl2·6H2O is reported. Cleavage of the As–S
bond of 1 and coordination of the resulting phosphanylthiolato ligand (SC6H4-2-PPh2)− (SC6H4-2-PPh2 =
P,S) was observed with formation of [M(P,S)2] (M = Ni, Pd, Pt). In the case of Pd and Pt, not only the
mononuclear complexes [M(P,S)2] formed, but also the trimers of [MX(P,S)] ([MX{(μ-S-SC6H4-2-PPh2)-
κ2S,P}]3 [M = Pd, X = Cl (2) and M = Pt, X = I (4)]). Formation of 2 and 4 was preceded by the
trinuclear isomeric intermediates [(cis-M{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-MX2-MX{(μ-S-SC6H4-2-PPh2)-
κ2S,P}] [M = Pd, X = Cl (3) and M = Pt, X = I (5)]. The crystal structures of 1–5 and a possible reaction
mechanism that leads to 2 and 4 are presented.
could act as a potentially tridentate ligand for a wide range of
metals. Here, the synthesis, spectroscopic characterization and
Introduction
Various derivatives of phosphanyl- and arsanyl thiolates have
been explored as heterotopic ligands in transition metal com-
plexes.1 One of the most prominent E,S (E = P, As) ligands is
HSC6H4-2-EPh2, in which the thiol group is rapidly deproto-
nated and may serve as a versatile donor in phosphanyl- and
arsanyl thiolato complexes.2,3 These mixed-donor (E,S) ligands
tend to form mononuclear metal complexes [M(E,S)2].1,3 On the
other hand, the reaction of the structurally isomeric thioarsines
and thiophosphines EPh2(SPh) (E = P, As)4,5 with metal carbo-
nyls resulted in metal-mediated E–S bond cleavage. Thus, reac-
tions with [Fe(CO)5], [FeCp(CO)2]2 (Cp = C5H5), [Co2(CO)8],
[Co2(μ-HCCH)(CO)6], [Mn2(CO)10] and complexes with mixed
metal centers (Co–Mo) usually lead to a variety of sulfur- and
phosphorus- or arsenic-containing metallacycles.6,7 We now
report the synthesis of heterotopic P,SAs ligand, 1-Ph2AsSC6H4-
2-PPh2 (1), which may not only combine the properties of phe-
nylthio(diphenyl)arsine and 2-diphenylphosphanylbenzenethiol,
but may also exhibit a wide range of possible bonding modes
and may allow the effect of the PPh2 group in the ortho position
on the cleavage of the As–S bond to be studied. Furthermore, 1
reactions of 1 with palladium(II), platinum(II) and nickel(II) com-
plexes are reported.
Results and discussion
The synthesis of 1 starts with the ortho-lithiation of the thiophe-
nol followed by reaction with Ph2PCl.2,8 The mono-lithiation of
the resulting phosphanylarylthiol, HSC6H4-2-PPh2, allowed
introduction of the third donor group through reaction with
Ph2AsCl (Scheme 1).
Crystals of 1 were obtained from a saturated solution of 1 in
diethyl ether. Compound 1 crystallizes in the monoclinic space
group P21/c with two independent molecules in the asymmetric
unit (Table 4). They differ mainly in the orientation of one
phenyl substituent at the arsenic position and, thus, further dis-
cussion will focus on only one molecule (Fig. 1). The phos-
phorus and arsenic atoms are in a slightly distorted trigonal–
pyramidal environment (Table 1). The C–E–C bond angles are
similar to those found in phosphanylarylthiols,9 o-(diphenylphos-
phanyl)thioanisole10 and thioacylsulfanylarsines.11 The P–C
bond lengths are in the expected range.12 The As–S bond length
aFaculty of Chemistry and Chemical Engineering, Babeş-Bolyai
University, Kogalniceanu 1, RO-400084 Cluj-Napoca, Romania.
E-mail: lusi@chem.ubbcluj.ro; Fax: +40 264 590818; Tel: +40 264
593833
bUniversität Leipzig, Institut für Anorganische Chemie, Johannisallee
29, D-04103 Leipzig, Germany. E-mail: hey@uni-leipzig.de; Fax: +49
0341 9739319; Tel: +49 0341 9736151
†CCDC [856663 (1), 856664 (2), 856665 (3), 856666 (4) and 856667
(5)]. For crystallographic data in CIF or other electronic format see DOI:
10.1039/c2dt12506d.
Scheme 1 Synthesis of 1-Ph2AsSC6H4-2-PPh2 (1).
5326 | Dalton Trans., 2012, 41, 5326–5333
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Fig. 1 Molecular structure of 1-Ph2AsS-2-PPh2-C6H4 (1). Only one of
the two independent molecules is shown. Hydrogen atoms are omitted
for clarity.
Fig. 2 Molecular structure of [PdCl{(μ-S-SC6H4-2-PPh2)-κ2S,P}]3 (2).
Hydrogen atoms and solvent molecules are omitted for clarity.
Table 1 Selected bond lengths (pm) and angles (°) in 1
As(1)–S(1)
S(1)–C(13)
P(1)–C(19)
P(1)–C(14)
P(1)–C(25)
226.6(1)
178.4(4)
183.7(4)
183.8(4)
184.3(4)
C(1)–As(1)–C(7)
C(1)–As(1)–S(1)
C(7)–As(1)–S(1)
C(13)–S(1)–As(1)
C(19)–P(1)–C(14)
C(19)–P(1)–C(25)
C(14)–P(1)–C(25)
100.7(5)
99.2(2)
98.3(2)
94.4(2)
102.2(2)
103.2(2)
100.7(2)
53.7, 48.8 and 47.2, which can be attributed to trinuclear palla-
dium complex 3. After 24 h, the peak for symmetric trimer 2
was also visible. Trinuclear complex 3 was isolated as dark
orange crystals from the reaction medium after a reaction time of
4 h. Once re-dissolved, transformation of pristine 3 into trimer 2
commences. At room temperature, full conversion takes approxi-
mately three weeks. During the formation of 2, a signal at δ =
48.6 with a minor intensity rises as well. This peak is character-
istic for the presence of the cis bis-chelate, which has already
been reported in the literature.17 The 31P{1H} NMR spectra of
the reaction medium of the platinum complex after 4 h showed
and the C–S–As bond angle show no remarkable deviations
from other organic arsenic(III) compounds (As–S: 222.8(5) pm13
to 233.0(6) pm;14 C–S–As: 92(1)° to 105.8(2)°).11,15
Palladium(II) and platinum(II) complexes 2–5 were synthesized
by reaction of 1 with [MX2(cod)] (M = Pd, X = Cl; M = Pt, X =
I; cod = 1,5-cyclooctadiene) in a 1 : 1 ratio. Shorter reaction
times (4 h, M = Pd; 1 week, M = Pt) gave the trinuclear com-
plexes [(cis-M{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-MX2-MX{(μ-S-
SC6H4-2-PPh2)-κ2S,P}] [M = Pd, X = Cl (3); M = Pt, X = I (5)],
while the trimeric trinuclear isomers [MX{(μ-S-SC6H4-2-PPh2)-
κ2S,P}]3 [M = Pd, X = Cl (2); M = Pt, X = I (4)] were obtained
after reaction times of two weeks. The isolated trinuclear iso-
meric products, 2 and 4 or 3 and 5, contain only the P,S-coordi-
nating phosphanylarylthiolato ligand. The eliminated AsPh2
group was observed in the filtrate after isolation of 2–5 by
MS-ESI spectrometry, which showed different oxidized species
of dimerized AsPh2. Scission of the As–S bond has been
observed also in reactions of thioarsines with different metal car-
bonyls, leading to a variety of metal-, sulfur- and arsenic-con-
taining cyclic products.7 The metal-mediated breaking of the
As–S bonds in inorganic molecules, such as As4S4, has received
considerable attention,16 but the cleavage of As–S bonds in
thioarsines has been less explored. The 31P{1H} NMR spectra of
palladium complex 2 showed a singlet at δ = 55.7; for platinum
complex 4 a singlet at δ = 32.5 with the corresponding satellites
(JP,Pt = 3285 Hz) was observed. In both reactions, the formation
of intermediates can be observed by 31P{1H} NMR spec-
troscopy. After 4 h, the reaction mixture of the palladium
complex showed three singlets with the same intensity at δ =
two singlets with corresponding satellites at δ = 50.2 (JP,Pt
=
2646 Hz) and δ = 32.5 (JP,Pt = 3285 Hz); the former can be
assigned to the trans bis-chelate based on the chemical shift and
coupling constants, the latter was found to belong to trimeric
platinum complex 4. After a few days, trans/cis isomerization of
the bis-chelate complex can be observed in solution; the appear-
ance of a signal for the cis isomer at δ = 42.3 (JP,Pt = 2915 Hz) is
accompanied by a decrease of the peak for the trans isomer.
Three additional signals of equal intensity with satellites are
observed at δ = 35.0 (JP,Pt = 3131 Hz), δ = 33.1 (JP,Pt = 3419 Hz)
and δ = 30.3 (JP,Pt = 2989 Hz) for trinuclear complex 5.
Complex 5 was isolated as dark orange crystals. Transformation
into the more stable isomeric symmetric trimer takes place at
room temperature over two weeks. In contrast, the 1 : 1 reaction
of 1 and NiCl2·6 H2O resulted in scission of the As–S bond and
formation of the known complex, trans-[Ni{(SC6H4-2-PPh2)-
κ2S,P}2]18,19 (6), in just a few hours as the only phosphorus-con-
taining compound, even after prolonged standing in solution.
Complexes 2–4 crystallize in the monoclinic space group P21/c
and compound 5 in P21/n with four molecules in the unit cell
(Table 4). They consist of a six-membered M3S3 ring (M = Pd,
Pt), in which the S atoms of the phosphanylthiolato ligand act as
bridges between two metal atoms. In the case of the symmetric
trimeric complexes 2 (Fig. 2) and 4 (Fig. 3), each P atom
additionally binds to one metal center resulting in MSC2P rings.
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 5326–5333 | 5327

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Fig. 3 Molecular structure of [PtI{(μ-S-SC6H4-2-PPh2)-κ2S,P}]3 (4).
Hydrogen atoms and solvent molecules are omitted for clarity.
Fig. 5 Molecular structure of [(cis-Pt{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-
PtI2-PtI{(μ-S-SC6H4-2-PPh2)-κ2S,P}] (5). Hydrogen atoms and solvent
molecules are omitted for clarity.
Table 2 Selected bond lengths (pm) and angles (°) for 2 and 4
2 (M = Pd)
4 (M = Pt)
M(1)–P(1)
M(1)–S(1)
M(1)–S(3)
M(2)–P(2)
M(2)–S(2)
M(2)–S(1)
M(3)–P(3)
M(3)–S(3)
223.0(6)
228.8(6)
242.5(6)
223.4(6)
227.3(5)
237.3(6)
223.4(7)
228.7(6)
240.5(6)
86.1(2)
91.2(2)
86.7(2)
84.4(2)
86.5(2)
222.8(1)
230.2(1)
242.8(1)
223.6(1)
227.3(1)
237.3(1)
223.5(2)
228.8(1)
238.7(1)
86.3(4)
91.1(4)
88.2(4)
81.9(4)
88.1(4)
M(3)–S(2)
P(1)–M(1)–S(1)
S(1)–M(1)–S(3)
P(2)–M(2)–S(2)
S(2)–M(2)–S(1)
P(3)–M(3)–S(3)
S(3)–M(3)–S(2)
C(2)–S(1)–M(1)
C(20)–S(2)–M(2)
C(38)–S(3)–M(3)
M(1)–S(1)–M(2)
M(2)–S(2)–M(3)
M(3)–S(3)–M(1)
93.1(2)
91.6(4)
105.6(8)
105.4(8)
105.3(8)
97.3(2)
105.6(2)
103.9(2)
105.2(2)
105.2(2)
103.8(2)
99.8(4)
109.7(4)
100.4(4)
Fig. 4 Molecular structure of [(cis-Pd{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-
PdCl2-PdCl{(μ-S-SC6H4-2-PPh2)-κ2S,P}] (3). Hydrogen atoms and
solvent molecules are omitted for clarity.
the two other corresponding S–M–S bond angles are larger and
the average value is close to 90°, as expected for a square planar
environment at Pd and Pt. The S–M–S bond angle in the cis bis-
chelates [M(P,S)2] (M = Pd, Pt)17,20 is well below 90° due to the
relatively bulky PPh2 fragments, but in complexes 3 and 5 this
angle exceeds 90° (Table 3), which facilitates the formation of
the M3S3 ring. Each trigonal–pyramidal sulfur atom coordinates
to two metal atoms with one shorter and one longer bond. The
intramolecular M⋯M distances are all greater than 356 pm, indi-
cating no metal–metal bonding.
Every metal atom is thus coordinated by two S, one P and one
terminally bound X atom [X = Cl (2), I (4)] in a distorted square
planar fashion, with the two sulfur atoms in a cis arrangement.
The M3S3 ring has a twist-boat conformation. Complexes 3
(Fig. 4) and 5 (Fig. 5) are built up of three subunits: a cis bis-
chelate M(P,S)2 is connected through the S atoms to an MX(P,S)
and an MX2 unit to form the M3S3 ring. As expected for a
chelate ligand, due to the fixed geometry, the smallest bond
angle at each metal atom is the intrachelate P–M–S angle (Tables
2 and 3), which is in the range found for cis bis-chelates.17,20
Complexes 2 and 4 have a very small S–M–S bond angle, poss-
ibly due to steric constraints in the six-membered ring. However,
The structures of several trinuclear platinum3,21–23 and palla-
dium24,25 complexes with bridging sulfur atoms have been
5328 | Dalton Trans., 2012, 41, 5326–5333
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described, but none of them contain the (SC6H4-2-PPh2)−
ligand. Related structures to 2 and 4 were found in [PtBr{(μ-S-
CH2CH2NMe2)-κ2N,S}]3, with nearly symmetric Pt–S–Pt thio-
lato bridges22 in [Pd{2-CH2-5-MeC6H3C(H)vNNvC(S)
NHEt}]3, in which the S–Pd–S angles were almost identical,25
and in [PtI{(μ-S-SC6H4-2-AsPh2)-κ2S,As}]3 and [PtI{(μ-S-
SC6H4-2-P(Biph)}-κ2S,P}]3 (Biph = 1,1′-biphenyl).23 However,
the distortion of the ring is more pronounced in [PtI{(μ-S-
SC6H4-2-P(Biph))-κ2S,P}]3 due to the greater rigidity introduced
by the biphenyl groups.
3
Ligands containing mixed donors (P,S) are known to form
mononuclear complexes [M(P,S)2].1 Thus, HSC6H4-2-PPh2
reacts with palladium(II) and platinum(II) complexes in the pres-
ence of a base (NEt3), which facilitates the deprotonation of the
S atom, to give the bis-chelates.17,26,27 In the present study,
the reaction of 1 with [PdCl2(cod)] and [PtI2(cod)] resulted in
the formation of trimers. Formation of the bis-chelates seems to
be kinetically more favored, as the 31P{1H} NMR spectra of the
reaction mixture of the Pt complex shows the trans bis-chelate
complex as the major reaction product after 4 h. To facilitate for-
mation of the trinuclear complex, the trans bis-chelate complex
must isomerize to the cis form (Scheme 2A). During the isomeri-
zation process, which could occur through an unbinding–binding
mechanism and in illustration of the hemilabile properties of the
P,S ligand, not only the conversion of the trans bis-chelate into
the cis isomer occurs; the formation of monomeric [MX(P,S)] is
facilitated as well, due to the presence of unconverted
[MX2(cod)] in solution. However, no signal is visible in the
31P{1H} NMR spectrum for [MX(P,S)], that is, the subsequent
formation of trinuclear complexes 3 and 5 is very fast.
Rearrangement to the more stable trimeric form, the final ther-
modynamic products 2 and 4, occurs over about three weeks at
room temperature in THF (Scheme 2B). The formation of trans-
Table 3 Selected bond lengths (pm) and angles (°) for 3 and 5
3 (M = Pd)
5 (M = Pt)
M(1)–P(2)
M(1)–P(1)
M(1)–S(1)
M(1)–S(2)
M(2)–P(3)
M(2)–S(3)
M(2)–S(1)
M(3)–S(2)
225.9(2)
227.5(2)
234.6(2)
233.9(2)
222.3(2)
227.6(2)
237.1(2)
228.6(2)
230.7(2)
98.4(7)
85.6(6)
84.1(6)
92.1(6)
87.7(6)
225.3(9)
225.7(8)
235.7(8)
236.1(8)
222.4(9)
228.6(8)
237.8(8)
230.7(8)
231.0(8)
99.9(3)
84.5(3)
88.9(3)
91.9(3)
86.9(3)
M(3)–S(3)
P(2)–M(1)–P(1)
P(2)–M(1)–S(2)
P(1)–M(1)–S(1)
S(2)–M(1)–S(1)
P(3)–M(2)–S(3)
S(3)–M(2)–S(1)
S(2)–M(3)–S(3)
C(2)–S(1)–M(1)
M(1)–S(1)–M(2)
C(20)–S(2)–M(1)
M(3)–S(2)–M(1)
C(38)–S(3)–M(2)
M(2)–S(3)–M(3)
86.1(6)
89.1(6)
84.7(3)
87.3(3)
104.6(2)
92.8(6)
104.6(2)
102.8 (7)
105.0(2)
107.5(7)
104.7(1)
91.4(3)
103.1(1)
103.6(3)
104.6(1)
110.2(3)
Table 4 Crystallographic data for compounds 1–5
1
2
3
4
5
Formula
Mr
Crystal system Monoclinic
Space group
C30H24AsPS
522.44
C54H42Cl3P3Pd3S3·CH2Cl2 C54H42Cl3P3Pd3S3·2CH2Cl2 C54H42I3P3Pt3S3·2CH2Cl2 C54H42I3P3Pt3S3·2.5CHCl3
1390.44
Monoclinic
P21/c
1475.37
Monoclinic
P21/c
2015.79
Monoclinic
P21/c
2144.36
Monoclinic
P21/n
P21/c
a/pm
b/pm
c/pm
α/°
1048.30(2)
987.97(3)
4848.1(1)
90
1963.05(2)
1140.76(1)
2395.33(2)
90
1707.82(4)
1194.68(3)
2835.40(7)
90
2333.81(4)
1144.52(1)
2393.86(4)
90
1421.75(2)
2306.16(3)
2029.71(3)
90
β/°
93.390(2)
90
5.0123(2)
8
96.739(1)
90
5.32697(8)
4
1.734
1.498
100.312(2)
90
5.6916(2)
4
1.722
1.499
112.458(2)
90
5.9093(2)
4
2.266
9.057
105.754(1)
90
6.4050(2)
4
2.224
8.505
γ/°
V/nm3
Z
Dcalcd/g cm−3
1.385
μ(MoKα)/mm–1 1.520
F(000)
2144
2760
2928
0.38 × 0.05 × 0.03
3744
0.27 × 0.11 × 0.09
3988
0.3 × 0.15 × 0.15
Crystal size/
0.4 × 0.4 × 0.07 0.2 × 0.2 × 0.1
mm3
θ range/°
hkl range
2.84–30.51
−14 ≤ h ≤ 10
−14 ≤ k ≤ 14
−60 ≤ l ≤ 69
45 613
2.81–30.51
−21 ≤ h ≤ 28
−15 ≤ k ≤ 16
−34 ≤ l ≤ 29
45 773
2.87–26.37
−21 ≤ h ≤ 21
−14 ≤ k ≤ 14
−35 ≤ l ≤ 35
44 068
2.83–30.51
−32 ≤ h ≤ 33
−16 ≤ k ≤ 16
−34 ≤ l ≤ 34
72 568
2.83–30.51
−20 ≤ h ≤ 20
−32 ≤ k ≤ 32
−28 ≤ l ≤ 28
3988
Refl. collected
Refl. unique
15 249
16 241
11 622
18 027
19 523
[Rint = 0.0457] [Rint = 0.0402]
[Rint = 0.0999]
649
1.080
[Rint = 0.0424]
649
1.025
[Rint = 0.0396]
724
1.040
Param. refined
GoF on F2
595
634
0.809
1.124
R1 [I > 2σ (I)]
R1 = 0.0721
wR2 = 0.1300
R1 = 0.0989
wR2 = 0.1355
1.127 and
−1.000
R1 = 0.0303
wR2 = 0.0486
R1 = 0.0561
wR2 = 0.0511
1.627 and −1.173
R1 = 0.0691
wR2 = 0.1048
R1 = 0.1129
wR2 = 0.1182
2.449 and −0.925
R1 = 0.0347
wR2 = 0.0637
R1 = 0.0478
wR2 = 0.0684
7.210 and −4.345
R1 = 0.0264
wR2 = 0.0462
R1 = 0.0370
wR2 = 0.0493
1.769 and −1.728
R indices (all
data)
Δρfin/e Å–3
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Scheme 2 The possible steps involved in the formation of complexes 2–5.
[Ni{(SC6H4-2-PPh2)-κ2S,P}2] (6) as the only P-containing
reaction product is probably due to the smaller atomic radius
of nickel making it more difficult to accommodate both the
diphenylphosphanylthiolato ligands in a cis conformation. Since
the AsPh2 group is eliminated and does not participate in coordi-
nation to the metal center, the reaction of HSC6H4-2-PPh2 with
[PdCl2(cod)] and [PtI2(cod)] was reinvestigated. The 2 : 1 or 1 : 1
reactions conducted in the presence of NEt3 always led to the
formation of cis and trans bis-chelates. When the deprotonating
agent was excluded from the reaction mixture, exclusive for-
mation of the trinuclear complex was preferred in the reaction
with [PdCl2(cod)], while the reaction with [PtI2(cod)] led to cis-
and trans-[M(P,S)2] complexes as the main reaction products and
traces of trimeric complex 2. However, reactions of [PtI2(cod)]
with HSC6H4-2-AsPh2 or HSC6H4-2-P(Biph) in the presence of
NEt3 resulted in small amounts of the corresponding trimeric
complexes, [PtI{(μ-S-SC6H4-2-AsPh2)-κ2S,As}]3 or [PtI{(μ-S-
SC6H4-2-P(Biph)}-κ2S,P}]3, besides the mononuclear platinum
complexes.3,23 Due to the continuous interconversion of the
metal complexes and their poor solubility in common solvents,
their separation in a pure form proved to be very difficult and
prevented the recording of 13C{1H} NMR spectra.
Conclusions
Reactions of 1 with group 10 metal dihalides occurred with clea-
vage of the As–S bond and coordination of the resulting phos-
phanylthiolato ligand (SC6H4-2-PPh2)−. However, reactions with
5330 | Dalton Trans., 2012, 41, 5326–5333
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Synthesis of 1-Ph2AsSC6H4-2-PPh2 (1)
[MX2(cod)] (M = Pd, X = Cl; M = Pt, X = I) led to trinuclear
complexes [(cis-M{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-MX2-MX{(μ-
S-SC6H4-2-PPh2)-κ2S,P}] [M = Pd, X = Cl (3); M = Pt, X = I
(5)] as the kinetic products, followed by formation of the thermo-
dynamic products [PtI{(μ-S-SC6H4-2-PPh2)-κ2S,P}]3 (M = Pd,
X = Cl (2); M = Pt, X = I (4)). The isomerization process was
observed by 31P{1H} NMR spectroscopy; all the structural
isomers were isolated and characterized by X-ray structure analy-
sis. In contrast, the reaction of 1 with NiCl2·6H2O led only to
the bis-chelate complex, trans-[Ni{(SC6H4-2-PPh2)-κ2S,P}2] (6).
n-Butyllithium (7.72 mL of a 2.2 M solution in n-hexane,
16.98 mmol) was slowly added at 0 °C to a stirred solution of
HSC6H4-2-PPh2 (5.00 g, 16.98 mmol) in toluene (65 mL). The
reaction mixture was stirred for 20 h and allowed to attain room
temperature. A pale yellow suspension formed. The reaction
vessel was cooled to 0 °C and a solution of chlorodiphenylarsine
(2.88 mL, 16.13 mmol) in toluene (5 mL) was slowly added
(over 15 min) to the stirred suspension. The solution was stirred
for 40 h, until the reaction was completed. The organic phase
was separated from the LiCl precipitate by filtration and concen-
trated in vacuo. The oily residue was dissolved in diethyl ether
and layered with n-hexane. 1-Ph2AsSC6H4-2-PPh2 (1) precipi-
tated as a pale yellow solid. Crystals suitable for X-ray structure
analysis were obtained from a saturated diethyl ether solution at
room temperature over one week. Yield: 7.14 g (84.7%). M.
p. 95 °C. Anal. C30H24AsPS (522.44 g mol−1): found (calcd): C
Experimental
All reactions were carried out under nitrogen using standard
Schlenk techniques. Solvents were dried and distilled prior to
use by described procedures or by use of a solvent purification
system (MB SPS-800). PdCl2 and H2[PtCl6]·6H2O were used as
received and Ph2AsCl,28 HSC6H4-2-PPh2,8 [PdCl2(cod)]29 and
[PtI2(cod)]29 were prepared according to the published pro-
cedures. All other reagents were used as received.
1
68.56 (68.96); H 4.60 (4.63)%. H NMR: δ = 7.36 (m, 5 H,
3
aryl-H), 7.20 (m, 16 H, aryl-H), 7.06 (t, JH,H = 7.6 Hz, 1 H,
3
3
aryl-H), 6.99 (t, JH,H = 7.4 Hz, 1 H, aryl-H), 6.65 (d, JH,H
=
7.2 Hz, 1 H, aryl-H). 13C{1H} NMR: δ = 141.44 (d, JC,P = 7.9
Hz), 140.94 (d, JC,P = 28.8 Hz), 140.23, 136.82 (d, JC,P = 11.7
Hz), 134.03 (m), 133.40, 132.84, 129.16, 128.88, 128.49 (m),
127.95, 127.70, 127.46, 127.20. 31P{1H} NMR: δ = −12.5 (s).
IR (cm−1, KBr disks): 3065 (m), 3046 (m), 1478 (m), 1433 (s),
1091 (m), 1038 (m), 1024 (m), 998 (m), 742 (s), 693 (s), 499
(m), 457 (m), 418 (m). MS-EI: m/z = 522 (M+, 7%), 445 (M+ −
Elemental analysis was performed with a VARIO EL-Heraeus
microanalyzer. The melting points were determined in sealed
capillaries and are uncorrected. The IR spectra were recorded on
a Perkin–Elmer System 2000 FTIR spectrometer scanning
1
between 4000 and 400 cm−1 using KBr disks. H (400 MHz),
13C (100 MHz) and 31P NMR (162 MHz) spectra were recorded
at 24 °C in CDCl3 on a Bruker Avance DRX-400 instrument
with TMS as an internal standard (1H NMR) and 85% H3PO4 as
an external standard (31P NMR). The mass spectra were recorded
on a VG12-520 mass spectrometer (EI-MS, 70 eV, 200 °C) and
an FT-ICR-MS Bruker Daltonics ESI mass spectrometer (APEX
II, 7 T). The data for the X-ray structures were collected on a
Gemini diffractometer (Agilent Technologies) with MoKα radi-
ation (λ = 71.073 pm) and ω-scan rotation. Data reduction was
performed with CrysAlisPro including the program SCALE3
ABSPACK for empirical absorption correction (1, 2, 3 and 5)30
and a model based on expressions derived by Clark and Reid31
for the analytical numeric absorption correction using a multifa-
ceted crystal (4). The structures were solved by direct methods
with the program SIR92 (1, 2, 3 and 5) or by Patterson methods
(4) with the program SHELXS-97.32 Anisotropic refinement of
all non-hydrogen atoms was performed with SHELXL-97,
except for the disordered solvent molecules in complex 2. All
hydrogen atoms were calculated on idealized positions using the
riding model. An analysis with SQUEEZE33 revealed a small
cavity (approximately 20 Å3 for the asymmetric unit) in the
structure of 3 that may be occupied to approximately 28% by
water or a similar small molecule. This effect is responsible for
the relatively high residual electron density (2.45 e Å−3) and was
not taken into account. In the structure of 5, two of the CHCl3
molecules are disordered. One of them was difficult to localize
and was treated as threefold disordered; the other is disordered
on a special position (the center of inversion). All 61 restraints
were used to model these two molecules. Structure figures were
generated with ORTEP.34 Thermal ellipsoids are drawn at 50%
probability unless otherwise mentioned. CCDC 856663 (1),
856664 (2), 856665 (3), 856666 (4) and 856667 (5) contain the
supplementary crystallographic data for this paper.
Ph, 18%), 293 (M+ − AsPh2, 95%), 229 (AsPh2 , 26%), 215
+
(M+ − 4Ph, 100%), 183 (M+ − PPh2 − 2Ph, 70%), 152 (AsPh+,
35%), 108 (PPh+, 15%), 77 (Ph+, 35%).
Synthesis of [PdCl{(μ-S-SC6H4-2-PPh2)-κ2S,P}]3 (2)
A THF solution (10 mL) of [PdCl2(cod)] (41 mg, 0.143 mmol)
was added to a stirred solution of 1 (75 mg, 0.143 mmol) in
THF (15 mL). The resulting solution was stirred for two weeks.
A pale orange precipitate formed, which was isolated and
washed with methanol. Recrystallization from a two-layer
solvent system (dichloromethane–n-hexane) afforded complex 2
as pale orange crystals in two days at room temperature.
Yield: 23.5 mg (12.6%). M.p. 285 °C (decomp.). Anal.
C54H42P3S3Pd3Cl3 (1305.65
g
mol−1): found (calcd for
C54H42P3S3Pd3Cl3 + CH2Cl2): C 47.16 (47.50); H 3.27 (3.19);
S 7.33 (6.92)%. 1H NMR: δ = 7.87 (d, JH,H = 8 Hz, 3 H,
3
3
aryl-H), 7.76 (q, JH,H = 7.4 Hz, 12 H, aryl-H), 7.37 (m, 21 H,
3
3
aryl-H), 7.13 (t, JH,H = 6.7 Hz, 3 H, aryl-H), 7.04 (t, JH,H
=
8.4 Hz, 3 H, aryl-H). 31P{1H} NMR: δ = 55.7 (s). MS-ESI:
m/z = 1320.80 [M + O]+. The eliminated AsPh2 group was
observed in the filtrate by ESI-MS as (Ph2AsO)2: m/z = 491.00
[M + H]+.
Synthesis of [(cis-Pd{(μ-S-SC6H4-2-PPh2)-κ2S,P}2)-PdCl2-PdCl-
{(μ-S-SC6H4-2-PPh2)-κ2S,P}] (3)
A THF solution (10 mL) of [PdCl2(cod)] (41 mg, 0.143 mmol)
was added to a stirred solution of 1 (75 mg, 0.143 mmol) in
THF (15 mL). The resulting solution was stirred for 4 hours and
then concentrated. A red–orange precipitate formed, which was
This journal is © The Royal Society of Chemistry 2012
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View Article Online
isolated and washed with methanol. Recrystallization from a
two-layer solvent system (dichloromethane–n-hexane) afforded
complex 3 as dark orange crystals in a few hours at room tempe-
rature. 31P{1H} NMR: δ = 53.7 (s), 48.8 (s), 47.2 (s). MS-ESI:
m/z = 1270.82 [M − Cl]+.
Acknowledgements
I. S. acknowledges financial support provided by programs co-
financed by the Sectoral Operational Program Human Resources
Development, Contract POSDRU 6/1.5/S/3, “Doctoral studies:
through science towards society” and from the Deutscher Akade-
mischer Austausch Dienst (DAAD scholarship for I. S., SOE
programme). Support from the EU-COSTAction CM0802 PhoS-
ciNet is gratefully acknowledged. We thank Umicore for a gener-
ous donation of PdCl2 and H2[PtCl6]·6H2O and Chemetall
GmbH for kindly providing n-butyllithium.
Synthesis of [PtI{(μ-S-SC6H4-2-PPh2)-κ2S,P}]3 (4)
The compound was synthesized as described for complex 2.
Compound 1 (77 mg, 0.147 mmol) was dissolved in THF
(15 mL) and [PtI2(cod)] (82 mg, 0.147 mmol) in THF (10 mL)
was added to the solution, which was stirred for two weeks. A
yellow solid formed and was separated by filtration and washed
with methanol. Recrystallization from a two-layer solvent system
(dichloromethane–n-hexane) gave complex 4 as pale orange
crystals over one week at room temperature. Yield: 46.9 mg
(17.3%). M.p. 354 °C. Anal. C54H42P3S3Pt3I3 (1845.97 g
mol−1): found (calcd): C 34.78 (35.13); H 2.44 (2.29); S 5.50
Notes and references
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1
3
(5.21)%. H NMR: δ = 7.91 (d, JH,H = 7.4 Hz, 3 H, aryl-H),
3
7.69 (q, JH,H = 7.6 Hz, 12 H, aryl-H), 7.29 (m, 21 H, aryl-H),
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SC6H4-2-PPh2)-κ2S,P}] (5)
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1717.7 [M − I]+.
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1
(calcd): C 66.59 (66.90); H 4.66 (4.43); S 10.08 (9.94)%. H
3
NMR: δ = 7.66 (q, JH,H = 6 Hz, 8 H, aryl-H), 7.46 (m, 6 H,
aryl-H), 7.35 (t, 3JH,H = 7.4 Hz, 8 H, aryl-H), 7.16 (t, 3JH,H = 7.4
3
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This journal is © The Royal Society of Chemistry 2012
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