Thiosaccharinate binding to palladium(II) and platinum(II): Synthesis and molecular structures of sulfur-bound complexes [M(κ1-tsac) 2(κ2-diphosphane)]

Article abstract of DOI:10.1016/j.ica.2012.12.022

Palladium(II) and platinum(II) thiosaccharinate complexes [M(κ¹-tsac)₂{κ²-Ph ₂P(CH₂)_nPPh₂}] (M = Pd, Pt; n = 1-4) have been prepared, palladium complexes from reaction of [Pd(tsac) ₂]·H₂O with diphosphanes and platinum complexes from addition of thiosaccharin to [PtCl₂{κ²-Ph ₂P(CH₂)_nPPh₂}] in the presence of triethylamine. All complexes have been fully characterized and the crystal structures of [Pd(κ¹-tsac)₂(κ²- dppp)] (n = 3) and [Pt(κ¹-tsac)₂(κ ²-dppm)] (n = 1) have been determined confirming that thiosaccharinate ligands are S-bound. The larger ring complexes (n = 3, 4) are fluxional in solution being attributed to the conformational flexibility of the diphosphane backbones The bis(diphosphane) complexes, [M(κ¹- tsac)₂(κ¹-dppm)₂] (M = Pd, Pt), have also been prepared upon treatment of [Pd(tsac)₂]·H₂O with two equivalents of dppm or addition of thiosaccharin to [Pt(κ²-dppm)₂]Cl₂ in the presence of triethylamine in which the diphosphanes bind in a monodentate fashion. Both are highly fluxional in solution, changes in the ³¹P{¹H} NMR spectra as a function of temperature being interpreted as the exchange of bound and unbound phosphorus atoms.

Full text of DOI:10.1016/j.ica.2012.12.022

Inorganica Chimica Acta 398 (2013) 117–123
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Thiosaccharinate binding to palladium(II) and platinum(II): Synthesis and
molecular structures of sulfur-bound complexes [M(j j
1-tsac)2( 2-diphosphane)]
a
b,
Subhi A. Al-Jibori a, , Mohamed H.S. Al-Jibori , Graeme Hogarth
⇑
⇑
a Department of Chemistry, College of Science, University of Tikrit, Tikrit, Iraq
b Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Palladium(II) and platinum(II) thiosaccharinate complexes [M(
n = 1–4) have been prepared, palladium complexes from reaction of [Pd(tsac)2]ꢀH2O with diphosphanes
and platinum complexes from addition of thiosaccharin to [PtCl2{
2-Ph2P(CH2)nPPh2}] in the presence
of triethylamine. All complexes have been fully characterized and the crystal structures of [Pd(
1-tsac)2
2-dppp)] (n = 3) and [Pt( 1-tsac)2( 2-dppm)] (n = 1) have been determined confirming that thiosaccha-
j j
1-tsac)2{ 2-Ph2P(CH2)nPPh2}] (M = Pd, Pt;
Received 21 September 2012
Received in revised form 6 December 2012
Accepted 7 December 2012
Available online 29 December 2012
j
j
(j
j
j
rinate ligands are S-bound. The larger ring complexes (n = 3, 4) are fluxional in solution being attributed
Keywords:
Platinum
Palladium
Thiosaccharinate
Diphosphane
X-ray crystallography
to the conformational flexibility of the diphosphane backbones The bis(diphosphane) complexes,
[M(
j
1-tsac)2(
j
1-dppm)2] (M = Pd, Pt), have also been prepared upon treatment of [Pd(tsac)2]ꢀH2O with
two equivalents of dppm or addition of thiosaccharin to [Pt(j
2-dppm)2]Cl2 in the presence of triethyl-
amine in which the diphosphanes bind in a monodentate fashion. Both are highly fluxional in solution,
changes in the 31P{1H} NMR spectra as a function of temperature being interpreted as the exchange of
bound and unbound phosphorus atoms.
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
ylphosphino)ferrocene] affords the mono-substituted complexes
[MCl(j j
1-sac)( 2-dppf)] even when a large excess of sodium sac-
Due to the widespread use of saccharin as an artificial sweet-
ener, the coordination chemistry of this cyclic amide has been
widely studied over the past 20 years [1]. Replacement of the car-
bonyl by a thiocarbonyl gives thiosaccharin and while the two
molecules look superficially similar they differ in both their ground
state structures and their ligating properties to metal centers. Thus,
while saccharin (sacH) exists in a single form (amide), thiosaccha-
rin (tsacH) can adopt two tautomeric forms in solution, namely
amide or thiol (Chart 1). Further upon deprotonation the negative
charge remains on nitrogen in saccharinate but is primarily located
on sulfur in thiosaccharinate (Chart 1) [2,3]. This becomes impor-
tant for the coordination chemistry of the two amides since the
thiosaccharinate (tsac) ligand is expected to bind strongly to soft
metal centers via the exocyclic sulfur atom and consequently the
coordination chemistry of thiosaccharinate [4–14] has been shown
to be quite different from that of saccharinate.
charinate is used, and saccharinate is N-bound [18]. By way of
comparison we have now investigated the addition of thiosaccha-
rinate (tsac) to platinum(II) and palladium(II) diphosphane centers
and find that complexes of the type [M(j j
1-tsac)2( 2-diphosphane)]
readily form, whereby the thiosaccharinate ligands are both
S-bound. We report the X-ray crystal structures of two examples
of these and variable temperature NMR studies aimed at elucidat-
ing fluxionality in solution. While this work was in progress
Quinzani and co-workers reported aspects of the palladium chem-
istry described herein [13].
2. Experimental
2.1. General
NMR spectra were recorded on a Bruker AMX400 spectrometer
at University College London and referenced internally to the resid-
ual solvent peak (1H) or externally (31P). IR spectra were recorded
on a Shimadzu FT8400 spectrometer as either KBr or CsI discs. Con-
ductivity measurements were made on a Philips PW9526 conduc-
tivity meter. Metal salts Na2[PdCl4], K2[PtCl4] and diphosphanes
were used as supplied. Thiosaccharin [21], cis-[PtCl2(dmso)2]
[22], [Pt(dppm)2]Cl2 [23] and [Pd(tsac)2]ꢀH2O [12] were prepared
according to literature methods.
In our recent work we have focused on the concurrent binding
of diphosphane and amide ligands at platinum(II) and palla-
dium(II) centers [15–20]. We have recently found that addition
of sodium saccharinate to [MCl2(j2-dppf)] [dppf = 1,10-bis(diphen-
⇑
Corresponding authors.
E-mail addresses: subhi_aljibori@yahoo.com (S.A. Al-Jibori), g.hogarth@ucl.ac.uk
(G. Hogarth).
0020-1693/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.12.022

118
S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
(br), 132.4, 131.4, 128.8, 127.0, 124.7, 120.1, 25.1 (t, J 18.1 Hz),
18.4; IR(KBr) 3053w, 2920w, 1422s, 1307vs, 1157vs, 1002s, 806s,
696m, 364s cmꢁ1; Elemental Anal. Calc. for PdN2S4P2O4C41H34
S
N
O
SH
N
O
N
O
C
S
C
S
C
S
H
.
H
Found: C, 53.81 (53.60); H, 3.72 (3.69); N, 3.06 (3.05)%. 5: yel-
low–brown solid, 80% yield. 1H NMR: d 8.10–7.40 (m, 28 H, Ar),
2.60 (br, 4H, CH2), 2.00 (brs, J 20.8 Hz, 2H, PCH2); 31P{1H} NMR:
24.7 (s) ppm; 13C{1H} NMR: 185.1, 137.8, 134.1, 133.5 (br), 132.4,
131.4, 131.1 (br), 130.8 (br), 130.4 (br), 128.7 (br), 124.6, 120.1,
26.9 (m), 24.2; IR(KBr) 3057w, 2925w, 1425s, 1309vs, 1157vs,
1000s, 807s, 696m, 365s cmꢁ1; Elemental Anal. Calc. for PdN2S4P2
O4C42H36. Found: C, 54.29 (53.86); H, 3.88 (3.82); N, 3.02 (3.13)%.
O
O
O
O
amide
thiol
saccharin (sacH)
thiosaccharin (tsacH)
Chart 1.
2.2. Preparation of complexes
2.2.4. [Pt(
For 6: A solution of thiosaccharin (tsacH) (0.06 g, 0.307 mmol)
in chloroform (8 cm3) was added to a solution of [PtCl2( 2-dppm)]
j j
1-tsac)2( 2-diphosphane)] (6–9)
2.2.1. [Pt(tsac)2]ꢀH2O (1)
A solution of thiosaccharin (tsacH) (0.04 g, 0.24 mmol) in meth-
j
anol (8 cm3) was added to
a solution of K2[PtCl4] (0.05 g,
(0.10 g, 0.154 mmol) in chloroform (10 cm3). A few drops of trieth-
ylamine were added and the resulting mixture was heated under
reflex for 1 h. This produced a yellow solution was filtered off
and reduced to half volume. Methanol (2 cm3) was added and
the mixture was set a side to evaporate slowly at room tempera-
ture. The yellow crystalline solid thus formed was filtered off and
dried in a vacuum oven (0.12 g, 91%). Other diphosphane com-
0.12 mmol) in water (3 cm3). The orange mixture was heated at re-
flux on a steam bath for 2 h. After cooling to room temperature the
brown solid formed was filtered off, washed with water and dried
in a vacuum oven to give 1 (0.049 g, 70%). 1H NMR (d6-dmso): d
8.50 (d, J 7.0 Hz, 2H), 8.86 (d, J 6.8 Hz, 2H), 7.76 (m, 4H); IR
v/cmꢁ1; IR(KBr) 3085w, 1419s, 1340vs, 1100vs, 1012s, 804vs,
366m cmꢁ1; Elemental Anal. Calc. for PtS4N2O4C14H8ꢀH2O. Found:
C, 27.58 (27.63); H, 1.64 (1.49); N, 4.60 (4.59)%.
plexes [Pt(
j
1-tsac)2(
j
j j j
2-dppe)] (7), [Pt( 1-tsac)2( 2-dppp)] (8) and
[Pt(j
1-tsac)2(
2-dppb)] (9) were prepared and isolated employing
a similar method.
Characterizing data: 6: yellow solid, 91% yield. 1H NMR: d 7.88
(m, 8H, Ar), 7.63 (m, 2H, Ar), 7.52 (m, 4H, Ar), 7.48 (m, 14H, Ar),
4.46 (t, J 10.4, 2H, CH2); 31P{1H} NMR: ꢁ50.4 (s, JPtP 2720 Hz)
ppm; IR(KBr) 3056w, 2920w, 1425s, 1310s, 1157vs, 996s, 804s,
692m, 371s cmꢁ1; Elemental Anal. Calc. for PtN2S4P2O4C39H30-
ꢀ0.5CHCl3. Found: C, 45.76 (46.17); H, 2.94 (2.89); N, 2.70
(2.68)%. 7: yellow solid, 81% yield. 1H NMR: d 8.0–7.4 (m, 28H,
Ar), 2.35 (m, 4H, CH2); 31P{1H} NMR: 45.7 (s, JPtP 3115 Hz) ppm;
IR(KBr) 3055w, 2932w, 1427s, 1311s, 1157vs, 999s, 806s, 694s,
375m cmꢁ1; Elemental Anal. Calc. for PtN2S4P2O4C40H32ꢀCH2Cl2.
Found: C, 45.81 (45.07); H, 3.17 (3.24); N, 2.61 (2.51)%. 8: yellow
solid, 82% yield. 1H NMR: d 7.82 (m, 6H, Ar), 7.67 (d, J 7.6 Hz, 2H,
Ar), 7.47 (t, J 7.6 Hz, 2H, Ar), 7.45–7.25 (m, 18H, Ar), 2.68 (m, 4H,
PCH2), 2.09 (m, 2H, CH2); 31P{1H} NMR: ꢁ3.9 (s, JPtP 2970 Hz)
ppm; IR(KBr) 3053w, 2923w, 1424s, 1307s, 1157vs, 999s, 805s,
2.2.2. [PtCl2(j
2-diphosphane)]
A solution of dppm (0.20 g, 0.52 mmol) in dichloromethane
(5 cm3) was added to cis-[PtCl2(dmso)2] (0.22 g, 0.52 mmol) sus-
pended in dichloromethane (10 cm3). The mixture was heated un-
der reflux for 1 h after which it was filtered hot and the filtrate was
allowed to evaporate slowly at room temperature. The white solid
thus formed was dried under vacuum to give [PtCl2(
(0.17 g, 79%). The complexes [PtCl2(
2-dppe)], [PtCl2(
and [PtCl2(
2-dppb)] were prepared and isolated employing a sim-
ilar method.
j
2-dppm)]
j
2-dppp)]
j
j
2.2.3. [Pd(j j
1-tsac)2( 2-diphosphane)] (2–5)
For 2: A solution of dppm (0.036 g, 0.093 mmol) in chloroform
(5 cm3) was added to [Pd(tsac)2]ꢀH2O (0.05 g, 0.093 mmol) sus-
pended in chloroform (10 cm3). The mixture was heated under re-
flux for 30 min. The brown solution thus formed was filtered and
the filtrate was reduced to half volume. Methanol (2 cm3) was
added to this and the mixture was set a side to evaporate slowly
at room temperature. The yellow crystalline solid thus formed
was filtered off and dried under vacuum (91%). The following
complexes were prepared and isolated by a similar method;
696s, 370m cmꢁ1; Elemental Anal. Calc. for PtN2S4P2O4C41H34
.
Found: C, 49.05 (48.61); H, 3.39 (3.41); N, 2.79 (2.72)%. 9: yel-
low–brown solid, 80% yield. 1H NMR: d 7.90–7.30 (m, 28H, Ar),
2.72 (br, 4H, CH2), 1.98 (brd, J 21.3 Hz, 4H, CH2); 31P{1H} NMR:
11.0 (s, JPtP 3102 Hz) ppm; IR(KBr) 3059w, 2935w, 1429s, 1307s,
1157vs, 995s, 807s, 694s, 374m cmꢁ1; Elemental Anal. Calc. for
PtN2S4P2O4C42H36. Found: C, 49.56 (48.53); H, 3.54 (3.43); N, 2.75
(2.66)%.
[Pd(
[Pd(
j
j
1-tsac)2(
1-tsac)2(
j
j
2-dppe)] (3), [Pd(
2-dppb)] (5).
j j
1-tsac)2( 2-dppp)] (4) and
Characterizing data: 2: yellow solid, 91% yield. 1H NMR: d 7.80–
7.40 (m, 28 H, Ar), 4.23 (t, J 12.0, 2H, CH2); 31P{1H} NMR: ꢁ40.6 (s)
ppm. 13C{1H} NMR: 184.5, 138.2, 134.2, 133.4 (t, J 6.0 Hz), 132.6,
132.3, 132.2, 129.4 (t, J 6.0 Hz), 126.9 (t, J 24.1 Hz), 125.1, 120.3,
42.8 (t, J 25.6 Hz); IR(KBr) 3058w, 2923w, 1427s, 1318vs, 1159vs,
1000s, 804s, 698m, 367s cmꢁ1; Elemental Anal. Calc. for PdN2S4P2
O4C39H30. Found: C, 52.80 (52.42); H, 3.38 (3.31); N, 3.16 (3.16)%.
3: white solid, 82% yield. 1H NMR: d 7.94–7.42 (m, 28 H, Ar),
2.43 (m, 4H, CH2); 31P{1H} NMR: 61.7 (s) ppm; 13C{1H} NMR:
185.6, 137.7, 134.2 (d, J 2.0 Hz), 133.7 (d, J 10.6 Hz), 132.3, 132.1,
131.3, 129.1 (d, J 12.0 Hz), 127.0, 126.7, 124.6, 119.9, 27.5 (dd, J
30.2, 13.6 Hz); IR(KBr) 3055w, 2918w, 1423s, 1311vs, 1157vs,
1001s, 808s, 694m, 363s cmꢁ1; Elemental Anal. Calc. for PdN2S4P2
O4C40H32ꢀCH2Cl2. Found: C, 49.93 (50.73); H, 3.45 (3.43); N, 2.84
(2.96)%. 4: yellow solid, 88% yield. 1H NMR: d 7.93–7.40 (m, 28
H, Ar), 2.62 (br, 4H, PCH2), 2.06 (br, 2H, CH2); 31P{1H} NMR: 7.9
(s) ppm; 13C{1H} NMR: 185.8, 137.7, 134.3 (d, J 1.5 Hz), 133.5
2.2.5. [Pd(tsac)2(
solution of dppm (0.072 g, 0.186 mmol) in chloroform
j
1-dppm)2] (10)
A
(10 cm3) was added to [Pd(tsac)2]ꢀH2O (0.05 g, 0.093 mmol) sus-
pended in chloroform (10 cm3). The mixture was heated under re-
flux for 30 min. The brown solution thus formed was filtered and
reduced to half volume. Methanol (2 cm3) was added and the mix-
ture was set aside to evaporate slowly at room temperature. The
pale yellow crystalline solid thus formed was filtered off and dried
under vacuum (79%). 10: pale yellow solid, 79% yield. 1H NMR (d8-
toluene): 293 K d 8.10–6.40 (m, 48 H, Ar), 3.66 (br, 4H, CH2); 373 K
d 7.63 (br, 8H), 7.46 (br, 2H), 7.27 (d, J 6.7 Hz, 2H), 7.08–6.90 (ob-
scured by solvent), 6.85 (m, 4H), 3.39 (br, 4H); 31P{1H} NMR: 243 K
26.4 (s – small), 18.2 (br), ꢁ30.8 (br), ꢁ40.7 (s – medium) ppm;
IR(KBr) 3060w, 2927w, 1431s, 1313vs, 1159vs, 1000s, 809s,
696m, 363s cmꢁ1; Elemental Anal. Calc. for PdN2S4P4O4C64H52
.
Found: C, 60.45 (59.83); H, 4.09 (4.07); N, 2.20 (2.20)%.

S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
119
2.2.6. [Pt(
A solution of thiosaccharin (tsacH) (0.084 g, 0.425 mmol) in
chloroform (10 cm3) was added to a solution of [Pt( 2-dppm)2]Cl2
j
1-tsac)2(
j
1-dppm)2] (11)
H2O (1), can be prepared in 70% yield as a brown solid upon addi-
tion of thiosaccharin to a refluxing methanol solution of K2[PtCl4].
It has limited solubility in common organic solvents but is readily
soluble in dmso giving an orange solution which is indefinitely sta-
ble. The structure of these complexes remains unknown. On the
basis of spectroscopic data, [Pd(tsac)2]ꢀH2O has been proposed to
contain a single metal center ligated by a pair of N,S-chelating thio-
saccharinate ligands (A), however, Quinzani has pointed out that a
dimeric structure with four bridging thiosaccharinate (B) cannot be
ruled out [13] and nor can a polymeric structure (C) with bridging
thiosaccharinate ligands (Chart 2).
At other metal centers each of these coordination modes have
been found for the thiosaccharinate ligand. For example,
[Cd(tsac)2(py)3] contains one monodentate S-bound and one che-
lating N,S-thiosaccharinate ligand, the bite-angle in the latter being
57.99(6)° [4], while interestingly closely related [Cd(tsac)2(H2O)]
contains polymeric chains of four co-ordinate S,O-bridged cad-
mium centers [11]. It may be that the three complexes discussed
here, namely [Pd(tsac)2]ꢀH2O, [Pd(tsac)2] and [Pd(tsac)2]ꢀH2O (1)
each have different molecular structures. Quinzani and co-workers
have argued for a chelating N,S-ligation in [Pd(tsac)2]ꢀH2O on the
basis of IR data [13], but the same authors point out that
[Cd(tsac)2(py)3] and [Cd(tsac)2(H2O)] have very similar IR data
the main difference being the ‘‘splitting’’ of some peaks in the spec-
trum of [Cd(tsac)2(py)3] resulting from the two different thiosac-
charinate coordination modes within the same molecule [4].
For [Pt(tsac)2]ꢀH2O the IR spectrum is quite simple, being indic-
ative of the adoption of a high symmetry structure and on this ba-
sis we rule out a polymeric structure. The 1H NMR spectrum is also
very simple suggesting the existence of a single isomeric form. In
related work we have recently crystallographically characterized
a related palladium complex containing 2-acetylamino-5-mer-
capto-1,3,4-thiadiazole (amtaH) ligands [26] which adopts a pad-
j
(0.22 g, 0.22 mmol) in chloroform (10 cm3). A few drops of trieth-
ylamine were added and the resulting mixture was heated under
reflex for 1 h. This produced a yellow solution which was filtered
and reduced to half volume. Methanol (2 cm3) was added and
the mixture was set aside to evaporate slowly at room tempera-
ture. The pale yellow crystalline solid thus formed was filtered
off and dried in a vacuum oven (85%). 11: pale yellow solid, 85%
yield. 1H NMR: d 7.57 (d, J 7.60 Hz, 4H, Ar), 7.50–6.80 (m, 44 H,
Ar), 3.46 (br, 4H, CH2); 31P{1H} NMR: 253 K 18.1 (br), ꢁ30.4 (br)
ppm; 298 K 16.8 (vbr), ꢁ28.1 (vbr) ppm; 333 K ꢁ23.3 (vbr) ppm;
IR(KBr) 3053w, 2932w, 1431s, 1313vs, 1159vs, 994s, 800s, 694s,
378m cmꢁ1; Elemental Anal. Calc. for PtN2S4P4O4C64H52ꢀ0.5CH2Cl2.
Found: C, 55.42 (55.00); H, 3.79 (3.66); N: 2.00 (1.97)%.
2.3. X-ray crystallography
Single crystals were mounted on glass fibers and all geometric
and intensity data were taken from these samples using a Bruker
SMART APEX CCD diffractometer using graphite-monochromated
Mo Ka radiation (k = 0.71073 Å) at 150 2 K (4) and 293 2 K
(6). Data reduction was carried out with SAINT PLUS and absorption
correction applied using the programme SADABS [24]. Structures
were solved by direct-methods (for 4) or Patterson methods (for
6) and developed using alternating cycles of least-squares refine-
ment and difference-Fourier synthesis. The majority of non-
hydrogen atoms were refined with anisotropic displacement
parameters. The exception to this was the disordered solvent mol-
ecules associated with 6 which were refined anisotropically and
hydrogen atoms were excluded. All other hydrogen atoms were
placed in calculated positions (riding model). Hydrogen atoms
were not placed on solvent of crystallization in structure due to
disorder problems with these atoms. Structure solution used
SHELXTL PLUS V6.10 program package [25].
dlewheel structure of the formula, [Pd2(l-amta)4], in which the
four amta ligands bridge the metal center via an N,S-coordination
mode as shown for B (Chart 2). We therefore tentatively suggest
that [Pt(tsac)2]ꢀH2O adopts a related bimetallic structure with the
water molecules being either bound to the vacant coordination
sites trans to the metal–metal vector, or as water of crystallization.
2.3.1. Crystallographic data
[Pd(
j
1-tsac)2(
j
2-dppp)] (4). MeOH: yellow block, size 0.26 ꢂ
0.24 ꢂ 0.21 mm, triclinic, space group P 1 bar, a = 10.9755(5) Å,
b = 11.1596(6) Å, c = 18.1144(9) Å,
= 82.693(1)°, V = 2089.9(2) Å3, Z = 2, dcalc = 1.499 g/cm3,
0.767 mmꢁ1, F(000) = 960, final R indices [F2 > 2
] R1 = 0.036,
a = 75.397(1)°, b = 77.504(1)°,
3.2. Synthesis of thiosaccharinate complexes [M(j -
1-tsac)2(j2
diphosphane)] (2–9)
c
l =
r
wR2 = 0.101, R indices (all data) R1 = 0.043, wR2 = 0.110. [Pt(j1
-
Treatment of equimolar amounts of [Pd(tsac)2]ꢀH2O with
diphosphanes, Ph2P(CH2)nPPh2 (n = 1–4), in chloroform afforded
tsac)2(
j
2-dppm)] (6).0.5CHCl3ꢀ2MeOHꢀH2O: yellow block, size
0.36 ꢂ 0.24 ꢂ 0.23 mm, monoclinic, space group C2/c, a =
mixed ligand complexes [Pd(j j
1-tsac)2( 2-diphosphane)] (2–5) in
29.031(5) Å, b = 20.477(4) Å, c = 15.281(3) Å, b = 105.325(3)°,
good yields (80–91%) as air stable yellow solids (Scheme 1). While
V = 8761(3) Å3, Z = 8, dcalc = 1.691 g/cm3,
l
= 3.610 mm–1, F(000) =
this manuscript was in progress, Quinzani and co-workers inde-
4448, final R indices [F2 > 2
r] R1 = 0.043, wR2 = 0.111, R indices (all
pendently reported the synthesis of [Pd(
and [Pd(
1-tsac)2( 2-dppe)] (3) along with [Pd(
using the same synthetic procedure [13].
j
1-tsac)2(
j
2-dppm)] (2)
data) R1 = 0.059, wR2 = 0.120.
j
j
j
1-tsac)2(PPh3)2]
3. Results and discussion
While the reaction of [Pd(tsac)2]ꢀH2O with diphosphanes gave
clean products, this method did not work so well with [Pt(tsac)2]
ꢀH2O (1), treatment with diphosphanes leading to a mixture of
3.1. Synthesis of [Pt(tsac)2]ꢀH2O (1)
products which included the desired [Pt(j -
1-tsac)2(j2
With the aim of preparing complexes of the type [M(tsac)2
(diphosphane)] and given the commercial availability of a range
of diphosphanes, then a simple approach seemed be the addition
of the latter to [M(tsac)2] (M = Pt, Pd). Baran and co-workers have
previously reported the synthesis of [Pd(tsac)2]ꢀH2O formed upon
treatment of Na2[PdCl4] with thiosaccharin in methanol [12], while
very recently Quinzani and co-workers reported formation of
[Pd(tsac)2] upon addition of thiosaccharin to [Pd(acac)2] in MeCN
[13]. Somewhat surprisingly the platinum analogue, [Pt(tsac)2],
has not been previously reported. The aqua complex, [Pt(tsac)2]ꢀ
diphosphane)] complexes. The reason for this is not clear but might
be related to the stronger platinum–nitrogen versus palladium–
nitrogen interactions in [M(tsac)2]ꢀH2O. In order to alleviate
lengthy separation and purification procedures we sought an
alternative synthetic route. The diphosphane complexes,
[PtCl2{j
2-Ph2P(CH2)nPPh2}] (n = 1–4) were readily prepared upon
addition of diphosphanes to cis-[PtCl2(dmso)2] and treatment with
thiosaccharin in chloroform in the presence of triethylamine gave
the desired [Pt(
as air-stable pale yellow solids (Scheme 2).
j j
1-tsac)2( 2-diphosphane)] (6–9) in good yields

120
S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
O
O
M
O
O
S
N
S
S
N
N
S
S
M
N
S
O
O
S
S
S
N
S
O
O
4
M
M
M
O
O
A
B
C
Chart 2.
26.9, m). While all signals in the 13C{1H} NMR spectra of 2–4 are
sharp, in 5 (dppb) there is considerable broadening of some of
the signals associated with the phenyl signals of the diphosphane.
Thus there are six sharp signals between 140 and 120 ppm associ-
ated with the thiosaccharinate ligands, but four very broad signals
associated with the diphosphane. This difference is also reflected in
the 1H NMR spectra of the complexes. Thus for 2 and 3 all signals
are sharp at room temperature and in line with what is expected
(the high field multiplet in 3 is a classic A2B2X2 signal). For the
dppp complex 4 some signals are sharp but others are broadened,
while at room temperature the majority of signals in 5 are broad.
We associate the sharp signals in each case with the thiosacchari-
nate ligands suggesting that these moieties are not participating in
the fluxional process. Cooling both samples to 243 K results in fur-
ther broadening of the signals associated with the diphosphanes,
while upon warming to 323 K the spectra sharpen significantly.
We have been hampered in fully elucidating the thermodynamic
parameters for this process due to the relatively temperature win-
dow of CDCl3. Nevertheless it seems apparent that it is associated
with a simple flexing of the methylene backbones of the dppp and
dppb ligands respectively.
O
Ph2
P
N
S
O
S
Ph2P(CH2)nPPh2
CHCl3
Pd(tsac)2.H2O
n(H2C)
Pd
S
P
Ph2
N
S
O
2-5; n = 1, 2, 3 ,4
O
Scheme 1.
O
Ph2
P
Ph2
N
S
O
P
S
Cl
Cl
2 tsacH, NEt3
CHCl3
n(H2C)
Pt
n(H2C)
Pt
S
P
Ph2
P
Ph2
N
S
O
6-9; n = 1, 2, 3 ,4
O
Scheme 2.
NMR data for the platinum complexes 6–9 are broadly similar
to the analogous palladium complexes, being somewhat more
complicated due to coupling to platinum. Thus the room tempera-
ture 31P{1H} NMR spectrum in each case shows a singlet with plat-
inum satellites, JPtP coupling constants varying between 2720 and
3115 Hz. As seen with the palladium chemistry, chemical shifts
are highly dependent upon ring size. Thus the dppm complex 6
is seen at ꢁ50.4 ppm while addition of another methylene group
shifts the signal to lower field by near 100 ppm, the dppe complex
7 resonating at 45.7 ppm. The 1H NMR spectra are also similar to
the palladium complexes. Most notably the room temperature
spectrum of 9 (dppb) displays a series of sharp resonances associ-
ated with the thiosaccharinate ligands but broad resonances for
the diphosphane. At higher field, two broad, but well-defined, res-
onances at d 2.73 and 1.98 are seen for the methylene protons, the
latter being a doublet (JPH 21.3 Hz) attributed to the phosphorus-
bound methylene groups. Upon cooling to 223 K, the aromatic res-
onances sharpen significantly and now four broad resonances are
seen for the methylene backbone; again indicative of diphosphane
fluxionality. The 31P{1H} NMR spectrum also broadens consider-
ably at this temperature but JPtP remains approximately the same
(3102 Hz at 313 K, 3079 Hz at 233 K). We did not record the
13C{1H} NMR spectra for the platinum complexes.
Characterization of all thiosaccharinate complexes was rela-
tively straightforward. All palladium complexes showed a singlet
resonance in the 31P{1H} NMR spectrum, consistent with the for-
mation of bis(thiosaccharinate) complexes. The chemical shift of
this signal was found to be highly dependent upon the ring size
of the diphosphane. Thus the dppm complex 2 (n = 1) appeared
at ꢁ40.6 ppm, while for
3 (n = 2) the singlet appeared at
61.7 ppm. We note that our 31P{1H} NMR data are quite different
to that reported by Quinzani (2: 10.42, 3: 120.44 ppm) [13]. The
reasons for this are not clear. We recorded all our NMR spectra
for the diphosphane complexes in CDCl3, while Quinzani recorded
all NMR spectra of 3 in d6-DMSO and also reported that it was an
acetonitrile adduct. Thus the differences we see for 3 may relate
to the solvent, although such a large change is unexpected. For 2
the difference is even harder to reconcile as both spectra are re-
corded in CDCl3. In the 13C{1H} NMR spectrum all show a low field
singlet between 184.59 and 185.79 ppm associated with the car-
bon atom between the thiol-sulfur and nitrogen atoms. This com-
pares well with a value of 189.69 ppm found in [Pd(tsac)2]ꢀH2O
[12]. All other signals expected for the thiosaccharinate ligands
are also observed in the aromatic region of the spectrum but exact
assignment is hampered somewhat by the coincidence of the phe-
nyl carbons of the diphosphane ligands. The diphosphane back-
bones are easily differentiated as they appear at relatively high
field. For 2 (dppm) a simple triplet is observed at 42.76 (J
25.7 Hz), while in 3 the two methylene groups appear as a pseudo
doublet of doublets at 27.50 (J 30.2, 13.6 Hz). For both 4 and 5 the
phosphorus and non-phosphorus bound methylene groups are eas-
ily differentiated, the latter appearing as singlets (4: 18.44, 5:
24.18) and the former as multiplets (4: 25.13, t, J 18.1 Hz, 5:
IR spectra have been widely used to characterize thiosacchari-
nate complexes [3–14]. For all complexes 2–9 the most important
bands related to vibrations of the five-membered ring of the thio-
saccharinate anions are located between 1500 and 400 cmꢁ1. In
particular the presence of
1003 cmꢁ1) and (NS) (800–822 cmꢁ1) vibrations clearly reflect
the coordination of the ligand through its thiocarboxylic sulfur
atom. Thus the (CS) stretching frequency has shifted from
1037 cmꢁ1 in free thiosaccharin to 995–1002 cmꢁ1 in the
m m(CS) (994–
(CN) (1416–1431 cmꢁ1),
m
m

S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
121
complexes, reflecting the weakening of the carbon–sulfur bond [2].
The stretching vibration of the SO2 group produces intense IR bands
icantly upon changing the diphosphane and are fully consistent
with the resonance structures shown in Schemes 1 and 2.
at 1307–1317 cmꢁ1 and 1159 cmꢁ1 corresponding to
m(SO2)asy and
Closer inspection of the dppp complex 4 allows us to better
understand the likely fluxional process observed in solution by
NMR spectroscopy. Thus in the solid-state (Fig. 1) the six-membered
PdP2C3 ring adopts a chair configuration with the central methylene
unit being orientated upwards (as shown). This should allow for a
relatively low energy interconversion to a boat form whereby the
central unit inverts. This can easily occur within the ligand sphere
of the complex and requires no change in orientation of the two thio-
saccharinate ligands. The latter are likely to be fixed even in solution
since rotation about either the palladium–sulfur or carbon–sulfur
bonds is anticipated to have a high activation barrier. The dppb li-
gand can likewise interconvert between related ring conformations,
while dppe and dppm complexes are more rigid as expected.
m
(SO2)sy respectively. These bands are seen at lower wavenumbers
than in thiosaccharin (1373 and 1153 cmꢁ1). Further evidence for
the S-bonded thiosaccharinate anion comes from the far IR, a med-
ium to strong band at 355–378 cmꢁ1 being assigned to
m
(M–S). The
coordinated diphosphanes are evident from the appearance of
(CH) at 2918–2935 cmꢁ1 and (M–P) at 692–698 cmꢁ1
m
m
.
3.3. Solid-state structures of [Pd(
[Pt(
1-tsac)2( 2-dppm)] (6)
j j
1-tsac)2( 2-dppp)] (4) and
j
j
In order to confirm the thiosaccharinate binding mode in these
complexes we carried out the X-ray crystal structures of two rep-
The solid-state structure of the platinum complex [Pt(j
1-tsac)2
resentative examples, namely [Pd(
j j
1-tsac)2( 2-dppp)] (4) and
1-tsac)2( 2-dppm)] (6), the results of which are summarized
j
(j
2-dppm)] (6) is generally similar to the related palladium com-
[Pt(
j
0
plex 2. Platinum-phosphorus [2.234(1) and 2.261(1) ÅA] and
in Figs. 1 and 2 and Table 1. Fortuitously, Quinzani and co-workers
0
platinum–sulfur [2.335(1) and 2.373(1) ÅA] distances are within
the expected ranges and the diphosphane bite-angle of 73.82(5)°
is only slightly larger than those found in 2. However, the diphos-
phane bite-angle is not relayed to the two thiolate ligands, the
S–Pt–S angle of 86.21(4)° being smaller than any of the related
parameters seen at palladium. The main difference between 6
and the palladium structures is seen in the relative orientations
of the two thiosaccharinate ligands. Thus, while all three palladium
complexes are characterized by an up-down (anti) relative
arrangement, with both ring systems being placed approximately
perpendicular to the PdS2P2 plane, in 6 one ring (containing S(2))
lies in this position (angle between planes 74.0°), while the second
lies approximately in the PtS2P2 plane (angle between planes 5.7°).
This also leads to quite different bond angles at sulfur varying from
112.7(2)° in the parallel ring to a more normal 103.1(2)° in that
lying perpendicular to the plane.
characterized two different palladium complexes, namely
[Pd(
and [Pd(
j
1-tsac)2(
j
2-dppm)] (2) (two molecules in asymmetric unit)
j
1-tsac)2( 2-dppe)] (3) [13], thus allowing us to make
j
some simple comparisons between changes in the metal and
diphosphane backbone. In all complexes of this type the S-bonded
thiosaccharinate ligands lie cis to one another and the coordination
geometry at the metal center is approximately square planar.
0
Within the palladium series, the Pd–P (2.238–2.284 ÅA) and Pd–S
0
(2.367–2.402 ÅA) distances vary only slightly as a result of the dif-
ferent diphosphane ligands. As expected, more major differences
are seen in the P–Pd–P bite-angles which increase upon sequential
addition of a methylene unit [2: 73.23(4), 72.84; 3: 84.86(5); 4:
90.75(2)°] and this has a less pronounced and less systematic effect
on the S–Pd–S bond angles [2: 90.93(4), 93.15; 3: 94.71(5); 4:
87.97(2)°]. For 4, the flexible dppp ligand results in the opening
of the P–Pd–P angle and concomitant closing of the of the S–Pd–S
angle. All three complexes show the same general feature of thio-
saccharinate ligands being orientated relatively up and down (anti)
with respect to the PdS2P2 plane, presumably in order to reduce ad-
verse steric interactions and this is effected by the relatively acute
Pd–S–C angles subtended at the thiolate sulfur [4: Pd(1)–S(1)–C(1)
99.11(9), Pd(1)–S(2)–C(2) 101.26(9)°] being similar to those for 2
[96.8(1)–100.0(1)°] and 3 [97.0(2) and 97.5(2)°]. Bond lengths
and angles within the thiosaccharinate ligands do not vary signif-
3.4. Synthesis of thiosaccharinate complexes [M(j j
1-tsac)2( 1-dppm)2]
(10–11)
Treatment of [Pd(tsac)2]ꢀH2O with two equivalents of dppm
gave the bis(diphosphane) complex [Pd(
1-tsac)2( 1-dppm)2]
(10), while the analogous platinum complex, [Pt(
1-tsac)2
1-dppm)2] (11), was prepared upon treatment of [Pt(dppm)2]Cl2
j
j
j
(j
0
Fig. 1. Two views of the molecular structure of [Pd(j j
1-tsac)2( 2-dppp)] (4) with selected bond lengths (ÅA) and angles (°); Pd(1)–P(1) 2.2827(7), Pd(1)–P(2) 2.2844(7), Pd(1)–
S(1) 2.3673(6), Pd(1)–S(2) 2.3742(6), S(1)–C(1) 1.703(3), S(2)–C(2) 1.697(3), S(3)–O(1) 1.436(2), S(3)–O(2) 1.440(2), S(3)–N(1) 1.663(2), S(3)–C(4) 1.768(3), S(4)–O(4)
1.443(2), S(4)–O(3) 1.443(2), S(4)–N(2) 1.643(2), S(4)–C(10) 1.767(3), P(1)–Pd(1)–P(2) 90.75(2), S(1)–Pd(1)–S(2) 87.97(2), P(1)–Pd(1)–S(1) 178.81(2), P(2)–Pd(1)–S(2)
174.85(2), Pd(1)–S(1)–C(1) 99.11(9), Pd(1)–S(2)–C(2) 101.36(9).

122
S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
0
Fig. 2. Two views of the molecular structure of [Pt(
j
1-tsac)2(
j
2-dppm)] (6) with selected bond lengths (ÅA) and angles (°); Pt(1)–P(2) 2.2438(13), Pt(1)–P(1) 2.2613(13), Pt(1)–
S(1) 2.3353(13), Pt(1)–S(2) 2.3728(12), S(1)–C(1) 1.698(5), S(2)–C(2) 1.714(5), S(3)–O(1) 1.424(4), S(3)–O(2) 1.434(4), S(3)–N(1) 1.653(4), S(3)–C(5) 1.758(5), S(4)–O(3)
1.430(4), S(4)–O(4) 1.433(4), S(4)–N(2) 1.645(4), S(4)–C(11) 1.765(5), P(1)–Pt(1)–P(2) 73.82(5), S(1)–Pt(1)–S(2) 86.21(4), P(1)–Pt(1)–S(2) 168.04(5), P(2)–Pt(1)–S(1)
177.95(5), Pt(1)–S(1)–C(1) 112.7(2), Pt(1)–S(2)–C(2) 103.1(2).
O
O
S
N
Ph2
P
Ph2P
Ph2P
S
2 dppm
CHCl3
2 tsacH, NEt3
CHCl3
M
[Pt(dppm)2]Cl2
[Pd(tsac)2].H2O
S
P
Ph2
N
S
10 M = Pd, 11 M = Pt
O
O
Scheme 3.
with thiosaccharin in the presence of triethylamine (Scheme 3).
Both are air-stable lemon yellow solids with relatively poor solu-
bility in common organic solvents. Quinzani has previously re-
ported the preparation of 10 [13].
Characterization as the bis(diphosphane) complexes was made
primarily on the basis of elemental analysis data. NMR data for
both 10 and 11 are complex and highly temperature dependent.
Quinzani and co-workers do not give NMR data for 10 in the exper-
imental section of his paper but say that ‘‘31P{1H} NMR spectra
show two signals centered at 34 and 15 ppm’’ [13]. For 10 we can-
not see any significant resonances in the 31P{1H} NMR spectrum at
room temperature. At 243 K two very broad resonances are seen at
attribute to bound and unbound phosphorus atoms respectively.
We were unable to identify any platinum satellites for these sig-
nals. Upon warming both broaden such that at room temperature
we see two broad resonances at 16.85 and ꢁ28.07, while at
333 K all signals have collapsed to give a broad resonance at
ꢁ23.23 ppm. This indicates that bound and unbound phosphorus
atoms are interconverting. The 1H NMR spectrum at 253 K in CDCl3
shows a series of broad resonances in the aromatic region but a
single broad resonance at d 3.48 associated with the two methy-
lene groups. Upon warming the latter signal broadens but does
not change significantly even at 373 K (d8-toluene: d 3.39). More
informative are the changes in the aromatic region. At 373 K (d8-
toluene) three sharp resonances are seen being attributed to the
thiosaccharinate ligand (one resonance is hidden) while other res-
onances associated with the diphosphane appear as broad singlets.
Upon cooling, little changes occur to the thiosaccharinate reso-
nances but the phosphane signals broaden considerably. The poor
solubility in toluene precludes the accumulation of data at lower
temperatures in this solvent but in CDCl3 the aromatic region of
the spectrum again continues to broaden down to 253 K.
18.12 and ꢁ30.79 ppm together with
a sharp singlet at
ꢁ40.74 ppm. The two broad resonances are in an approximate
1:1 ratio and are assigned to bound and unbound phosphorus
atoms respectively, while the sharp high field signal (ca. 0.5%) is
attributed to [Pd(j
1-tsac)2(dppm)] (2). We do not observe a signal
at ca. ꢁ22 ppm which we might expect for free dppm. 1H NMR
spectra of 10 are difficult to interpret at all temperatures. At
243 K a number of very broad resonances are observed between
d 8.0 – 6.8 and between d 3.9 – 3.0 there is another broad feature
with some fine structure. Upon warming changes occur to both re-
gions but each remains broad and difficult to interpret. Some more
insight can be gleaned from the platinum complex and we have re-
We attribute these observations to the interconversion of bound
and unbound phosphorus atoms within the complex. We believe
that the thiosaccharinate ligands remain essentially unchanged
throughout and the NMR spectra show that both are always equiv-
alent. Shaw and co-workers have previously prepared and exam-
ined by NMR spectroscopy a series of related organyl complexes,
corded a series of 31P{1H} NMR spectra for [Pt( 1-tsac)2(j1
j -
dppm)2] (11) in both CDCl3 and d8-toluene (in both solubility is rel-
atively poor) over the range 373 – 253 K. At 253 K in CDCl3 we ob-
serve two broad singlets at 18.06 and ꢁ30.37 ppm which we
[PtR2(
and anti) differing in the relative orientations of the organyl ligands
j
1-dppm)2] [27]. These exist as a mixture of isomers (syn

S.A. Al-Jibori et al. / Inorganica Chimica Acta 398 (2013) 117–123
123
Ph2
P
facilitated by a significant ring-strain in the chelate form. This is
not unique to thiosaccharinate and has been observed previously
by Shaw and co-workers for related alkyl and aryl complexes [27].
Ph2
P
Ph2
R
R
Ph2P
Ph2P
R
R
P
+
M
M
M
P
P
P
Ph2
Ph2
Ph2
Appendix A. Supplementary material
R
S
R
Ph2
P
Ph2
P
Ph2
P
S
Ph2P
Ph2P
CCDC 882531 and 882532 contain the supplementary crystallo-
graphic data for 4 and 6. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif. Supplementary data associated
with this article can be found, in the online version, at http://
dx.doi.org/10.1016/j.ica.2012.12.022.
+
M
S
R
S
P
P
P
Ph2
Ph2
Ph2
R
Scheme 4.
References
with respect to one another which are in equilibrium with [PtR2(-
j
2-dppm)] and free dppm (Scheme 4).
[1] E.J. Baran, V.T. Yilmaz, Coord. Chem. Rev. 2006 (1980) 250.
[2] M.M. Branda, N.J. Castellani, S.H. Tarulli, O.V. Quinzani, E.J. Baran, R.H.
Contreras, Int. J. Quantum. Chem. 89 (2002) 525.
[3] G. Jovanovski, A. Cahil, O. Grupce, L. Pejov, J. Mol. Struct. 784 (2006) 7.
[4] S.H. Tarulli, O.V. Quinzani, E.J. Baran, O.E. Piro, Z. Anorg, Allg. Chem. 628 (2002)
751.
[5] S.H. Tarulli, O.V. Quinzani, E.J. Baran, O.E. Piro, E.E. Castellano, J. Mol. Struct.
656 (2003) 161.
[6] S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.E. Castellano, E.J. Baran, Z. Anorg. Allg.
Chem. 2003 (1975) 629.
[7] M. Dennehy, G.P. Telleria, S.H. Turulli, O.V. Quinzani, S.D. Mandolesi, J.A. Guida,
G.A. Echeverria, O.E. Piro, E.C. Castellano, Inorg. Chim. Acta 360 (2007) 3169.
[8] M. Dennehy, R.M. Ferullo, O.V. Quinzani, S.D. Mandolesi, N. Castellani, M.
Jennings, Polyhedron 27 (2008) 2243.
[9] M. Dennehy, G.P. Telleria, O.V. Quinzani, G.A. Echeverria, O.E. Piro, E.C.
Castellano, Inorg. Chim. Acta 362 (2009) 2900.
[10] M. Dennehy, O.V. Quinzani, A. Grandos, A.R. Burrow, Polyhedron 29 (2010)
1344.
[11] S.H. Tarulli, O.V. Quinzani, O.E. Piro, E.J. Baran, E.E. Castellano, Monatsh. Chem.
132 (2001) 779.
[12] M. Vieites, D. Gambino, M. Gonzalez, H. Cerecetto, S.H. Tarulli, O.V. Quinzani,
E.J. Baran, J. Coord. Chem. 59 (2006) 101.
[13] S.H. Tarulli, O.V. Quinzani, S.D. Mandolesi, J.A. Guida, G.V. Echeverria, O.E. Piro,
E.E. Castellano, Z. Anorg, Allg. Chem. 645 (2009) 1604.
[14] M. Dennehy, O.V. Quinzani, S.D. Mandolesi, R.A. Burrow, J. Mol. Struct. 998
(2011) 119.
[15] S.A. Al-Jibori, I.A. Al-Nassiri, L.J. Al-Hayaly, T.A.K. Al-Allaf, Transition Met.
Chem. 27 (2002) 191.
[16] O.H. Amin, L.J. Al-Hayaly, S.A. Al-Jibori, T.A.K. Al-Allaf, Polyhedron 2004 (2013)
23.
[17] S.A. Al-Jibori, A.S.S. Al-Zaubi, M.Y. Mohammed, T.A.K. Al-Allaf, Transition Met.
Chem. 32 (2007) 281.
[18] S.A. Al-Jibori, A.I. Abdullah, T.A.K. Al-Allaf, Transition Met. Chem. 19 (2007)
1334.
[19] S.A. Al-Jibori, A I.A. Al-Nassiry, G. Hogarth, L. Salassa, Inorg. Chim. Acta 398
(2013) 46.
[20] S.A. Al-Jibori, T.F. Khaleel, S.A.O. Ahmed, L.J. Al-Hayaly, K. Merzweiler, C.
Wagner, G. Hogarth, Polyhedron 41 (2012) 20.
For 10 and 11, the bulk of the thiosaccharinate ligands preclude
formation of the syn-isomer and hence only a single isomer (anti
up-down arrangement at sulfur). The position of the equilibrium
has been found to be highly dependent upon the nature of the
organyl ligands. Thus with CH2R (R = Ph, But) no bis(diphosphane)
complex was observed, while for 1-naphthyl the equilibrium lies
strongly over to the bis(diphosphane) complex (K = 78 dm3 molꢁ1
)
[27]. We propose a similar equilibrium for 10 and 11 lying over to
the right hand side. For 11 we cannot estimate the equilibrium
constant as we do not see [Pt(
perature. For 10, we estimate an equilibrium constant of 20 dm3
molꢁ1 1-tsac)2( 1-dppm)2/[Pd( 1-tsac)2
at 243 K {K = Pd(
2-dppm)]2 as we could not see free dppm in the spectrum}. There
is a large error on this value and it should be treated with caution
but it is of a similar magnitude to that found for [PtPh2(
1-dppm)2]
j j
1-tsac)2( 2-dppm)] (7) at any tem-
j
j
j
(
j
j
[27]. Shaw also notes that the time to reach equilibrium varies
from minutes to days. For both 10 and 11 equilibrium is estab-
lished rapidly.
4. Summary
In this contribution we have shown that [MCl2(
phane)] complexes react with Na(sac) to afford mono-substituted
N-bound complexes [MCl(
1-sac)( 2-diphosphane)] as the major
products and even in the presence of excess Na(sac) the disubsti-
tuted complexes are not generated [19]. In contrast, [M(
1-tsac)2
2-diphosphane)] are isolated when either [Pd(tsac)2].H2O is
reacted with diphosphanes or when Na(tsac) is added to [PtCl2
2-diphosphane)] and in all the thiosaccharinate ligands are
j
2-diphos-
j
j
j
(j
(j
[21] J.R. Meadow, J.C. Cavaguol, J. Org. Chem. 16 (1951) 1582.
[22] J.H. Price, A.N. Williamson, R.F. Schamm, B.B. Wagland, Inorg. Chem. 11 (1972)
1280.
[23] B.T. Sterenberg, H.A. Jenkins, R.J. Puddephatt, Organometallics 18 (1999) 219.
[24] SMART and SAINT+ software for CCDC diffractometers, version 6.1, Bruker AXS,
Madison, WI, 2000.
[25] G.M. Sheldrick, SHELXTL PLUS, version 6.1, Bruker AXS, Madison, WI, 2000.
[26] S.A. Al-Jibori, E.G.H. Al-Saraj, N. Hollingsworth, G. Hogarth, Polyhedron 44
(2012) 210.
[27] F.S.M. Hassan, D.M. MacEwan, P.G. Pringle, B.L. Shaw, J. Chem. Soc., Dalton
Trans. (1985) 1501.
S-bound. In this mode the two thiosaccharinate ligands can adopt
a relative anti-arrangement resulting in a significant reduction in
adverse steric interaction as opposed to unobserved N-bound iso-
mer. With the small bite-angle diphosphane, bis(diphenylphos-
phino)methane (dppm) [28], the bis(saccharinate) complexes
react further to yield [M(j j
1-tsac)2( 1-dppm)2] in which the two
diphosphanes are monodentate. This is quite different from the
behavior observed for other diphosphanes (where no further reac-
tion takes place) and the opening of the chelate ring is probably
[28] R.J. Puddephatt, Chem. Soc. Rev. (1983) 99.