The preparation and coordination chemistry of R2P(S)NHP(S)R'2 (R and R'= iPr, Ph, Et, OEt or OPh)

Article abstract of DOI:10.1016/S0277-5387(00)00602-1

The preparation of R₂P(S)NHP(S)R'₂ (R and R' = ⁱPr, Ph, Et, OEt or OPh) is reported. Four examples have been characterised crystallographically. The molecules exist with a twisted P=S···P=S arrangement and hydrogen bond in the solid state. The H-bonding is influenced by the nature of the R groups; thus R = alkyl are better donors than R = aryl. Demonstrative metal complexes of zinc, palladium and platinum are also reported. Interestingly, the palladium and platinum complexes show a consistent conformational difference with PdS₂P₂N pseudo-boat conformations and PtS₂P₂N pseudo-chair conformations.

Full text of DOI:10.1016/S0277-5387(00)00602-1

www.elsevier.nl/locate/poly
Polyhedron 20 (2001) 125–134
The preparation and coordination chemistry of R2P(S)NHP(S)R%
2
(R and R%=iPr, Ph, Et, OEt or OPh)
David J. Birdsall, Alexandra M.Z. Slawin, J. Derek Woollins *
Department of Chemistry, Uni6ersity of St Andrews, St Andrews, Fife, Scotland KY16 9ST, UK
Received 25 July 2000; accepted 9 October 2000
Abstract
The preparation of R2P(S)NHP(S)R2% (R and R%=iPr, Ph, Et, OEt or OPh) is reported. Four examples have been characterised
crystallographically. The molecules exist with a twisted PꢀS···PꢀS arrangement and hydrogen bond in the solid state. The
H-bonding is influenced by the nature of the R groups; thus R=alkyl are better donors than R=aryl. Demonstrative metal
complexes of zinc, palladium and platinum are also reported. Interestingly, the palladium and platinum complexes show a
consistent conformational difference with PdS2P2N pseudo-boat conformations and PtS2P2N pseudo-chair conformations. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: Coordination chemistry; X-ray structure; Heterocycle; H-bonding
1. Introduction
2. Experimental
The complexation reactions of dithioimidophosphi-
nates with transition metal centres is currently attract-
ing considerable interest [1–20]. The neutral complexes,
of the type M[N(R2PS)2]2, are formed by deprotonation
2.1. General
Diethyl ether, petroleum ether (60–80°C) and te-
trahydrofuran were purified by reflux over sodium and
distillation under nitrogen. Dichloromethane was
heated to reflux over powdered calcium hydride and
distilled under nitrogen. (PhO)2P(S)Cl was prepared by
a previously reported method [10]. Infrared spectra
were recorded from KBr discs on a Perkin–Elmer
system 2000 spectrometer; 31P NMR spectra on a JEOL
of the R2P(S)NHP(S)R% ligand at the amine NꢁH. The
2
steric control that this ligand system imparts compared
to, for example, acac, has led to research into dithioimi-
dophosphinates with different substituents at phospho-
rus and the ability to tune the metal selectivity of
dithioimidophosphinates by varying the substituents
has led to applications of these systems in metal extrac-
tion processes. A number of these types of ligands,
FX90Q operating at 36.21 MHz; H, 13C and 31P NMR
1
spectra on Bruker instruments operating at 250, 62.9
and 101.3 MHz, respectively. Fast atom bombardment
mass spectra were obtained by the Swansea mass spec-
trometry service.
R2P(S)NHP(S)R%, where R/R%=Ph, EtO and Me have
2
recently been described; palladium and platinum com-
i
plexes derived from Pr2P(S)NHP(S)iPr2 were reported
to have differing MS2P2N ring conformation [21,22].
Here, an extension of this work is reported using un-
symmetric ligand systems, and a comparison of the
steric and electronic characteristics imparted by the
phosphine substituents on ring conformations is
provided.
2.2. Ph2P(S)Cl
Diphenylchlorophosphine (11.1 g, 9 ml, 50.0 mmol)
was stirred overnight with sulfur (1.3 g, 50.0 mmol) in
thf (20 ml). The solvent was removed in vacuo to give
a clear oil (12.6 g; 31P{1H} NMR (CDCl3): l 79.4
ppm).
* Corresponding author. Tel.: +44-1334-463-861; fax: +44-1334-
463-384.
E-mail address: j.d.woollins@st-andrews.ac.uk (J.D. Woollins).
0277-5387/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0277-5387(00)00602-1

126
D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
i
2.3. Pr2P(S)Cl
was removed in vacuo. The product was collected by
filtration and washed with diethyl ether (30 ml). The
K+ salt was then converted back to the free ligand
by stirring in water (25 ml) with the addition of di-
lute HCl (15%, 50ml) and extracted into CH2Cl2 (3×
25 ml). The CH2Cl2 solution was dried over MgSO4
and filtered. The filtrate was reduced to 1 ml and the
pure product was recrystallised using hexane. Yield
4.4 g, 11.52 mmol, 54%. Microanalysis calculated for
C18H25NP2S2: C, 56.5; H, 6.5; N, 3.6. Observed: C,
56.6; H, 6.5; N, 3.5%. FAB (+ve) MS: m/z 381
corresponds to Ph2P(S)NHP(S)iPr2.
Diisopropylchlorophosphine (9 ml, 56.5 mmol) was
stirred overnight with sulfur (1.8 g, 56.3 mmol) in thf
(20 ml). The solvent was removed in vacuo to give a
clear oil (9.6 g; 31P{1H} NMR (CDCl3): l 128.4
ppm).
2.4. Et2P(S)Cl
Diethylchlorophosphine (5.0 g, 40.1 mmol) was
stirred overnight with sulfur (1.2 g, 40.0 mol) in thf
(20 ml). The solvent was removed in vacuo to give a
pale yellow oil (6.3 g; 31P{1H} NMR (CDCl3): l
110.2 ppm).
2.7.1. (PhO)2P(S)NHP(S)iPr2 (2)
Prepared as for 1 using (PhO)2P(S)NH2 (5.7 g, 21.5
mmol) in place of Ph2P(S)NH2. A white product re-
sulted. Yield 5.3 g, 12.9 mmol, 60%. Microanalysis
calculated for C18H23NP2S2O2: C, 51.9; H, 5.6; N,
3.4. Observed: C, 49.8; H, 5.7; N, 3.1%. FAB (+ve)
MS: m/z 411 corresponds to (PhO)2P(S)NHP(S)iPr2.
2.5. Ph2P(S)NH2
NH3 gas was bubbled through
a solution of
Ph2P(S)Cl (6.0 g, 23.8 mmol) in ether and thf (100
ml, 50:50) for 30 min. The mixture was then filtered
and the NH4Cl solid residue was washed thoroughly
with Et2O (3×30 ml). The filtrate was then evapo-
rated to dryness giving a white solid (5.25 g; 31P{1H}
NMR (CDCl3): l 59.7 ppm).
2.7.2. Ph2P(S)NHP(S)Et2 (3)
Prepared as for 1 with NaH (1.5 g, 37.5 mmol,
60% w/w in mineral oil) was added to Ph2P(S)NH2
(4.7 g, 20.2 mmol) and Et2P(S)Cl (3.2 g, 20.2 mmol).
A white product resulted. Yield 4.8 g, 13.6 mmol,
67%. Microanalysis calculated for C16H21NP2S2: C,
54.3; H, 5.9; N, 3.9. Observed: C, 55.0; H, 6.1; N,
3.9%. FAB (+ve) MS: m/z 354 corresponds to
Ph2P(S)NHP(S)Et2.
2.6. (PhO)2P(S)NH2
NH3 gas was bubbled through
a solution of
(PhO)2P(S)Cl (6.0 g, 21.1 mmol) in ether and thf (100
ml, 50:50) for 30 min. The mixture was then filtered
and the NH4Cl solid residue was washed thoroughly
with Et2O (3×30 ml). The filtrate was then evapo-
rated to dryness giving a white solid (5.54 g; 31P{1H}
NMR (CDCl3): l 63.9 ppm).
2.7.3. (PhO)2P(S)NHP(S)Et2 (4)
Prepared as for 1 with NaH (1.2 g, 30 mmol, 60%
w/w in mineral oil) added to (PhO)2P(S)NH2 (4.0 g,
15.0 mmol) and Et2P(S)Cl (2.5 g, 15.9 mmol). A
white product resulted. Yield 4.5 g, 11.6 mmol, 73%.
Microanalysis calculated for C16H21NP2S2O2: C, 49.8;
H, 5.4; N, 3.6. Observed: C, 49.4; H, 5.3; N, 3.5%.
FAB (+ve) MS: m/z 385 corresponds to
(PhO)2P(S)NHP(S)Et2.
2.7. Ph2P(S)NHP(S)iPr2 (1)
Sodium hydride (1.3 g, 32.5 mmol, 60% w/w in
mineral oil) was added slowly, over 45 min, to a
solution of Ph2P(S)NH2 (5.0 g, 21.5 mmol) in thf (50
ml) cooled to −78°C. The mixture was allowed to
warm slowly to room temperature over 2 h. The reac-
tion mixture was cooled to −78°C and a solution of
iPr2P(S)Cl (3.96 g, 21.5 mmol) in thf (25 ml) was
added dropwise over 30 min. The mixture was then
refluxed for 6 h, cooled to room temperature. The
solvent was removed in vacuo, the product was pre-
cipitated with dilute HCl (15%, 50 ml) and the result-
ing slurry extracted into CH2Cl2 (3×25 ml). The
CH2Cl2 solution was dried over MgSO4 and filtered.
The filtrate was reduced to 2 ml and the crude
product precipitated using hexane and collected by
filtration. Excess Ph2P(S)NH2 was removed by stirring
the crude product in MeOH (20 ml) with the addition
of excess of KtBuO (1.5 g, 13.4 mmol). The solvent
2.7.4. (PhO)2P(S)NHP(S)(EtO)2 (5)
Prepared as for 1 with NaH (0.75 g, 15 mmol, 60%
w/w in mineral oil) added to (PhO)2P(S)NH2 (2.0 g,
7.54 mmol) and (EtO)2P(S)Cl (1.4 g, 7.60 mmol). A
white product resulted. Yield 2.6 g, 6.25 mmol, 83%.
Microanalysis calculated for C16H21NP2S2O4: C, 46.0;
H, 5.0; N, 3.4. Observed: C, 45.7; H, 5.5; N, 3.8%.
FAB (+ve) MS: m/z 416 corresponds to
(PhO)2P(S)NHP(S)(OEt)2.
2.7.5. Zn[Ph2P(S)NP(S)iPr2]2 (6)
ZnCl2 (0.018 g, 0.129 mmol) was added to a solu-
tion of 1 (0.100 g, 0.258 mmol) and KtBuO (0.029 g,
0.258 mmol) in methanol (10 ml), and the mixture
was stirred for 3 h. The cloudy white mixture was

D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
127
filtered and the white product collected. Yield 0.068 g,
0.142 mmol, 87%. Microanalysis calculated for
C36H48N2P4S4Zn: C, 52.2; H, 5.8; N, 3.3. Observed: C,
52.7; H, 5.2; N, 3.0%. FAB (+ve) MS: m/z 827
corresponds to Zn[Ph2P(S)NP(S)iPr2]2.
510(m) cm−1. FAB (+ve) MS: m/z 810 corresponds
to Pd[Ph2P(S)NP(S)Et2]2.
2.7.11. Pt[Ph2P(S)NP(S)Et2]2 (12)
KOtBu (0.05 g, 0.424 mmol) and 3 (0.15 g, 0.424
mmol) were added to a solution of PtCl2(cod) (0.08 g,
0.212 mmol) in methanol (2 ml) and stirred for 3 h. A
yellow solid was collected by filtration and recrys-
tallised from CH2Cl2 and methanol. Yield 0.111 g,
0.123 mmol, 58%. Microanalysis calculated for
C32H40N2P4S4Pt·2CH2Cl2: C, 38.1; H, 4.1; N, 2.5. Ob-
served: C, 38.6; H, 4.4; N, 1.7%. 31P{1H} NMR
2.7.6. Pd[Ph2P(S)NP(S)iPr2]2 (7)
KOtBu (0.044 g, 0.392 mmol) and 1 (0.15 g, 0.392
mmol) were added to a solution of PdCl2(cod) (0.056
g, 0.196 mmol) in methanol (2 ml) and stirred for 5 h.
An orange solid was collected by filtration. Yield
0.165 g, 0.190 mmol, 97%. Microanalysis calculated
for C36H48N2P4S4Pd: C, 49.7; H, 5.5; N, 3.2. Ob-
served: C, 49.6; H, 5.7; N, 2.9%. FAB (+ve) MS: m/z
868 corresponds to Pd[Ph2P(S)NP(S)iPr2]2.
2
2
(CDCl3): 54.4, 34.4 ppm, J(31P–31P) 8.8 Hz, J(195Pt–
31P) 95 Hz. FT IR (KBr disc): w(PNP) 1171(s),
767(m); w(PS) 504(bs) cm−1. FAB (+ve) MS: m/z
900 corresponds to Pt[Ph2P(S)NP(S)Et2]2.
2.7.7. Pt[Ph2P(S)NP(S)iPr2]2 (8)
KOtBu (0.044 g, 0.392 mmol) and 1 (0.15 g, 0.392
mmol) were added to a solution of PtCl2(cod) (0.074
g, 0.196 mmol) in methanol (2 ml) and stirred for 5 h.
A yellow solid was collected by filtration. Yield 0.165
g, 0.190 mmol, 97%. Microanalysis calculated for
C36H48N2P4S4Pt: C, 45.1; H, 5.0; N, 2.9. Observed: C,
46.1; H, 4.9; N, 2.7%. FAB (+ve) MS: m/z 957
corresponds to Pt[Ph2P(S)NP(S)iPr2]2.
2.7.12. Pd[(PhO)2P(S)NP(S)Et2]2 (13)
KOtBu (0.045 g, 0.388 mmol) and 4 (0.15 g, 0.388
mmol) were added to a solution of PdCl2(cod) (0.056
g, 0.194 mmol) in methanol (2 ml) and stirred for 2 h.
An orange solid was collected by filtration. Yield
0.166 g, 0.189 mmol, 97%. Microanalysis calculated
for C32H40N2P4S4O4Pd: C, 43.8; H, 4.6; N, 3.0. Ob-
served: C, 44.1; H, 4.5; N, 2.1%. 31P{1H} NMR
2.7.8. Pd[(PhO)2P(S)NP(S)iPr2]2 (9)
(CDCl3): 60.4, 44.3 ppm, J(31P–31P) 13.2 Hz. FT IR
2
KOtBu (0.028 g, 0.25 mmol) and 2 (0.10 g, 0.25
mmol) were added to a solution of PdCl2(cod) (0.036
g, 0.125 mmol) in methanol (2 ml) and stirred for 1 h.
An orange solid was collected by filtration. Yield
0.165 g, 0.190 mmol, 97%. Microanalysis calculated
for C36H48N2P4S4O4Pd: C, 46.5; H, 4.7; N, 3.0. Ob-
served: C, 43.8; H, 4.9; N, 2.6%. FAB (+ve) MS: m/z
928 corresponds to Pd[(PhO)2P(S)NP(S)iPr2]2.
(KBr disc): w(PNP) 1185(s), 764(m); w(PS) 588(w),
545(w) cm−1. FAB (+ve) MS: m/z 874 corresponds
to Pd[(PhO)2P(S)NP(S)Et2]2.
2.7.13. Pt[(PhO)2P(S)NP(S)Et2]2 (14)
KOtBu (0.045 g, 0.388 mmol) and 4 (0.15 g, 0.388
mmol) were added to a solution of PtCl2(cod) (0.073
g, 0.194 mmol) in methanol (2 ml) and stirred for 3 h.
A yellow solid was collected by filtration. Yield 0.111
g, 0.058 mmol, 31%. Microanalysis calculated for
C32H40N2P4S4O4Pt: C, 39.8; H, 4.1; N, 2.9. Observed:
C, 39.9; H, 4.1; N, 2.0%. 31P{1H} NMR (CDCl3):
2.7.9. Pt[(PhO)2P(S)NP(S)iPr2]2 (10)
KOtBu (0.042 g, 0.364 mmol) and 2 (0.15 g, 0.364
mmol) were added to a solution of PtCl2(cod) (0.068
g, 0.182 mmol) in methanol (2 ml) and stirred for 6 h.
A yellow solid was collected by filtration (0.143 g,
0.140 mmol, 77% yield). Microanalysis calculated for
C36H48N2P4S4O4Pt: C, 42.4; H, 4.3; N, 2.8. Observed:
C, 42.4; H, 4.6; N, 2.5%. FAB (+ve) MS: m/z 1018
corresponds to Pt[(PhO)2P(S)NP(S)iPr2]2.
2
2
57.8, 36.6 ppm, J(31P–31P) 13.2 Hz, J(195Pt–31P) 87.9
Hz. FT IR (KBr disc): w(PNP) 1186(s), 764(m); w(PS)
588(m), 550(w) cm−1. FAB (+ve) MS: m/z 964 corre-
sponds to Pt[(PhO)2P(S)NP(S)Et2.
2.8. Crystallography
2.7.10. Pd[Ph2P(S)NP(S)Et2]2 (11)
KOtBu (0.050 g, 0.424 mmol) and 3 (0.15 g, 0.424
mmol) was added to a solution of PdCl2(cod) (0.060 g,
0.212 mmol) in methanol (2 ml) and stirred for 2 h.
An orange solid was collected by filtration. Yield
0.165 g, 0.190 mmol, 97%. Microanalysis calculated
for C32H40N2P4S4Pd: C, 47.4; H, 4.9; N, 3.5. Ob-
served: C, 47.6; H, 4.6; N, 3.5%. 31P{1H} NMR
Details of the structure determination are given in
Table 1. X-ray diffraction measurements were made
with graphite-monochromated Mo Ka X-radiation us-
ing a Siemens SMART diffractometer (Ph2P(S)NH2, 8,
9, 10, 13) or with Cu Ka radiation and a Rigaku
AFC7S serial diffractometer 1–4. For the SMART
data, intensity data were collected using 0.3 or 0.15°
width v steps accumulating area detector frames
spanning a hemisphere of reciprocal space for all
2
(CDCl3): 57.3, 36.4 ppm, J(31P–31P) 8.8 Hz. FT IR
(KBr disc): w(PNP) 1190(s), 760(m); w(PS) 518(m),

Table 1
Details of the crystal data and refinements
Compound
Ph2P(S)NH2s
C12H12NPS
1
2
3
4
8
9
10
13
Empirical formula
C18H25NP2S2
C18H25NO2P2S2
C16H21NP2S2
C16H21NO2P2S2 C36H48N2P4-
PtS4
C36H48N2O4P4- C36H48N2O4P4PtS4 C32H40N2O4P4PdS
PdS4
4
Formula weight
Colour/size (mm)
233.26
381.47
413.47
353.42
colourless/0.2
×0.2×0.1
orthorhombic
Pbca
16.420(5)
22.38(1)
10.095(9)
90
90
90
3711(4)
8
1.265
385.41
955.97
931.28
1019.97
875.18
colourless/0.25
×0.15×0.15
triclinic
colourless/0.1
×0.06×0.2
triclinic
colourless/0.1
×0.2×0.2
triclinic
colourless/0.16
×0.08×0.03
monoclinic
P21/n
13.897(4)
8.144(5)
18.488(3)
90
111.45(2)
90
1947(2)
4
yellow/0.14
×0.2×0.3
triclinic
orange/0.17
×0.17×0.2
monoclinic
P21/a
11.2354(10)
15.706(2)
12.4002(11)
90
101.236(2)
90
2146.3(3)
2
yellow/0.03×0.17 orange/0.03×0.2
×0.33
monoclinic
P21/n
9.3798(3)
9.4976.(2)
24.3161(7)
90
99.3640(10)
90
2137.35(10)
2
×0.4
monoclinic
C2/c
26.6745(3)
8.47300(10)
19.5863(3)
90
119.17
90
3865.42(9)
4
1.504
0.899
1792
Crystal system
Space group
(
(
(
(
P1
P1
P1
P1
,
a (A)
9.1420(5)
9.2341(5)
14.8498(8)
85.61(1)
80.27(1)
83.45(1)
1225(1)
4
11.782(3)
16.040(5)
11.689(5)
102.57(3)
96.63(3)
106.08(2)
2035(1)
4
9.223(4)
13.991(2)
8.696(2)
104.91(1)
92.91(3)
98.06(2)
1069.2(6)
2
9.6659(2)
9.9362(2)
12.1797(2)
97.3290(10)
107.6680(10)
109.0580(10)
1019.58(3)
1
,
/
b (A)
,
c (A)
h (°)
i (°)
k (°)
2
3
,
Volume (A )
Z
(
Dcalc (g cm−3
)
1.264
0.361
488
1.245
3.832
808
1.284
3.757
436
1.314
4.095
808
1.557
3.830
480
1.441
0.815
960
1.585
3.666
1024
v (mm−1
F(000)
)
4.167
1488
125
134
Independent
5440/4018
6051/3065
3185/1611
3160/1172
3139/1365
2920/2838
3075/1831
3077/2554
2766/2450
reflections/observed
reflections
Final R1/wR2
0.472/0.1322
0.056/0.039
3.22
0.116/0.108
7.13
0.046/0.030
2.32
0.057/0.045
2.33
0.0236/0.0605
0.960
0.1071/0.1377
0.869
0.0343/0.0762
0.945
0.0305/0.0897
0.881
Goodness-of-fit on F2 0.972
Largest difference
0.476/−0.416
0.29, −0.28
0.82, −0.47
0.22, −0.19
0.25, −0.32
0.936, −0.695 0.325, −0.319 0.889, −0.635
0.533, −0.197
−3
,
peak/hole (e A
)

D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
129
structures (data were integrated using the SAINT pro-
gram) and for the Rigaku AFC7S data collections by v
scans over a single quadrant of reciprocal space. All
data were corrected for Lorentz, polarisation and long-
term intensity fluctuations. Absorption effects were cor-
rected on the basis of multiple equivalent reflections or
by semi-empirical methods. Structures were solved by
direct methods and refined by full-matrix least-squares
The amine and halide are ‘clipped’ together with
sodium hydride in thf. Silvestru and co-workers re-
cently reported the use of BuLi for this reaction [17]
but we have found that NaH is more convenient, less
costly and allows for the reactions to be more readily
scaled up.
n
The addition of HCl reprotonates the unreacted
sodium salt of the thiophosphoryl amine as well as the
producing the desired product. This is shown in the 31P
NMR spectra of the crude ligands, as signals for both
product and amine are present. Pure samples of the
ligands were obtained via the production of the K+
salts of the ligands and recrystallisations from CH2Cl2/
diethyl ether.
against F (TEX (SHELXTL). All hydrogen
SAN) or F2
atoms were assigned isotropic displacement parameters
and were constrained to idealised geometries. One of
the phenyl rings in 2 displayed some disorder, otherwise
the refinements were entirely straightforward. Refine-
ments converged to residuals given in Table 1. All
calculations were made with SHELXTL [23] or TE
[24].
XSAN
Selected 31P NMR data for 1–5 are given in Table 2.
The AX 31P NMR spectra of the unsymmetric ligands
can be confidently assigned by comparison with chemi-
cal shifts of the symmetric ligands reported here and
3. Results and discussion
1
previously. The H NMR spectra, FAB+ mass spectra
and elemental analyses were satisfactory for all com-
pounds. The solid state IR spectra of the ligands show
w(PS), w(PNP) and w(NꢁH) peaks in the expected re-
gions. Selected IR data are given in Table 2.
3.1. Ligand synthesis
The syntheses of the dithioimidophosphinate and
dithioimidophosphonates ligands, general formula
Since the structure of Ph2P(S)NH2 has not been
reported, we give details here for comparison with 1–4.
In the structure of Ph2P(S)NH2 there are two indepen-
dent molecules that hydrogen bond together to form a
dimer-pair which links to an adjacent dimer pair. The
remaining N(1)ꢁH(1b) does not H-bond but points
directly towards the centre of a phenyl ring of an
adjacent molecule (Fig. 1, Table 3). There are, in princi-
pal, two possible tautomeric arrangements of 1–4. Sin-
gle-crystal X-ray diffraction studies carried out on 1
(Fig. 2), 2 (Fig. 3), 3 (Fig. 5) and 4 (Fig. 4), however,
show that all these systems adopt the same tautomeric
arrangement with the proton bound to N in all cases.
R2P(S)NHP(S)R%, were performed using a method pre-
2
viously reported for related systems. A list of ligands
prepared is shown in Table 2. The reaction scheme for
the ligand preparation is shown in Eq. (1).
,
The PꢁS bond lengths in 1 (1.936(2) and 1.948(2) A) are
typical for PꢀS double bond distances, whilst the PꢁN
,
bonds (1.675(5) and 1.703(5) A) are both ‘single’. Simi-
larly in 2, 3 and 4 the PꢀS bond lengths reflect the
double bond nature of the PꢀS group, whilst the PꢁN
bond lengths are single in character (Table 3). Com-
pounds 1–4 all adopt conformations in the solid state
(1)
Table 2
R2P(E)NHP(E%)R2 ligands 1–5 with selected 31P NMR and IR data (cm−1
)
No
Formula R2P(S)NHP(S)R2%
l (ppm) R, R%
2J(31P–31P) (Hz)
w(NH)
l(NH)
w(PNP)
w(PS)
1
2
3
4
5
Ph2P(S)NHP(S)iPr2
100.0, 51.5
94.6, 51.5
84.5, 51.2
81.3, 52.3
60.4, 51.8
30.8
30.8
26.4
26.4
21.9
3206
3041
3128
3026
3028
1437
1489
1437
1488
1490
935, 907, 880
964, 921, 902
921 (broad)
932, 918, 896
935, 926, 894
624, 613
625, 609
622, 612
623, 612
635, 612
(PhO)2P(S)NHP(S)iPr2
Ph2P(S)NHP(S)Et2
(PhO)2P(S)NHP(S)Et2
(PhO)2P(S)NHP(S)(OEt)2

130
D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
Fig. 1. Solid state structure of Ph2P(S)NH2 showing (A) the hydrogen bonding (B) the packing in the lattice.
Table 3
,
Selected bond lengths (A) and angles (°) for Ph2P(S)NH2 and 1–4
a
Ph2P(S)NH2
1
2
3
4
P(1)ꢁS(1)
P(2)ꢁS(2)
P(1)ꢁN(1)
N(1)ꢁP(2)
H···S
1.9553[9]
1.9656(8)
1.660(2)
1.654[2]
2.48–2.57
3.45–3.55
1.936(2) [1.939(2)]
1.948(2) [1.931(3)]
1.675(5) [1.686(5)]
1.703(5) [1.667(5)]
2.43(1) [2.71(1)]
3.46(1) [3.61(1)]
1.880(6)
1.946(6)
1.655(9)
1.71(1)
3.02(1)
3.33(1)
1.936(2)
1.948(2)
1.684(5)
1.678(4)
2.33(1)
1.888(3)
1.944(3)
1.660(5)
1.691(6)
2.70(1)
N···S
3.42(1)
3.28(1)
S(1)ꢁP(1)ꢁN(1)
N(1)ꢁP(2)ꢁS(2)
P(1)ꢁN(1)ꢁP(2)
N(1)ꢁH···S(1)
118.37(9)
119.10[8]
116.5(2) [113.0(2)]
113.3(2) [117.0(2)]
129.5(3) [129.5(3)]
159(1) [172(1)]
119.2(5)
109.6(4)
133.0(7)
102(1)
114.4(2)
109.0(2)
132.1(3)
141(1)
118.5(3)
106.5(2)
131.5(4)
124(1)
156–176
a Ph2P(S)NH2 and 1 have two independent molecules in the crystallographic unit cell. The molecules are labelled following the numbering
scheme in Figs. 1 and 2, respectively.
with the PꢀS groups rotated with respect to the PꢁNꢁP
plane with the S(1)ꢁP(1)···P(2)ꢁS(2) ‘torsion’ angle be-
ing 108, 155, 174 and 153°, respectively. As is the case
for the methyl and phenyl analogues, the anti/gauche
conformation is associated with chain-like and dimer
packing of the molecules in the crystalline material.
Compounds 1 and 4 form chains in the solid state,
whilst 2 and 3 form dimers similar to the solid state
structure reported for Ph2P(S)NHP(S)Ph2. There is an
NꢁH···S hydrogen bond in all the systems; which has
the effect of lengthening the PꢀS bond lengths for the
hydrogen bonded S atoms. The hydrogen bonding in all
these ligands occurs through the PꢀS group with alkyl
phosphine substituents. The alkyl groups H-bond pref-
erentially since they are less sterically demanding and
better electron donor groups than the phenoxy and
Fig. 2. Solid state structure of 1.

D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
131
phenyl phosphine substituents present on the opposite
PꢀS group. The PꢀS groups which do not H-bond
demonstrate the effect of the R groups on bond length.
,
In 2 (R=OPh) the PꢀS bond length is 1.880(6) A. In 1
,
(R=Ph) the PꢀS is significantly longer at 1.936(2) A.
The same trend is displayed in 4 (R=OPh) and 3
(R=Ph), where PꢀS bond lengths are 1.888(3) and
1.936(2) A, respectively. The OPh group tends to be
,
slightly more electron withdrawing than Ph, leading to
a more electropositive phosphorus. This has the effect
of shortening the PꢀS bond as seen in these examples.
Crystals of 5 suitable for X-ray diffraction experi-
ments were never grown successfully.
3.2. Tetrahedral complexes of R2P(S)NHP(S)R%
2
Fig. 3. Solid state structure of 2.
Fig. 4. Solid state structure of 4.
Fig. 5. Solid state structure of 3.
The reaction of a 2:1 molar ratio of 1 with ZnCl2 in
the presence of KtBuO led to the formation of a neutral
complex with the formula ZnL2, where L=
Ph2P(S)NP(S)iPr2 (Eq. (2) and Table 4).
(2)
High purity material was isolated in good yield. The
1
complex was characterised by a combination of H, 31P
NMR, IR, mass spectrometry and elemental analysis. All
gave satisfactory results. The 31P NMR spectrum of 6
displays two doublets at 67.8 and 34.3 ppm. The upfield
shift of ꢀ25 ppm from the free ligand is consistent with
deprotonation upon complexation. The IR spectrum
supports this conclusion with loss of the w(NꢁH) stretch-
ing band, w(PꢁS) in the complex (527 and 510 cm−1
)
shows a reduced PꢁS bond order from the free ligand
(where w(P=S) is 624 and 613 cm−1). The w(PNP) in the
complex (1232 and 651 cm−1) shows an increase in bond
order over the free ligand (w(PNP)=935 cm−1). Selected
IR data for 6 is given in Table 4.
3.3. Square-planar complexes of R2P(S)NHP(S)R%
2
PdCl2(cod) and PtCl2(cod) were reacted in a 1:2 molar
ratio with 1–4 in order to produce bis imidophosphinate
complexes (Eq. (3), where M=Pt or Pd and Table 4).
Reactions were carried out in methanol with KtBuO used
to deprotonate the ligand.
(3)

132
D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
Table 4
31P NMR and IR data for 7–14
Formula M[R2PA(S)NPX(S)R2% ]2
w(PNP) (cm−1
)
w(PS) (cm−1
)
l (ppm)
2J(31P–31P) (Hz) 1J(195Pt–31P) (Hz)
PA
PX
PA%
–
PX%
–
Zn[Ph2P(S)NP(S)iPr2]2 (6)
Pd[Ph2P(S)NP(S)iPr2]2 (7)
Pt[Ph2P(S)NP(S)iPr2]2 (8)
Pd[(PhO)2P(S)NP(S)iPr2]2 (9)
Pt[(PhO)2P(S)NP(S)iPr2]2 (10)
Pd[Ph2P(S)NP(S)Et2]2 (11)
Pt[Ph2P(S)NP(S)Et2]2 (12)
Pd[(PhO)2P(S)NP(S)Et2]2 (13)
Pt[(PhO)2P(S)NP(S)Et2]2 (14)
1232, 651
1191, 750
1220, 745
1192, 767
1193, 767
1190, 760
1171, 767
1185, 764
1186, 764
527, 510
530, 518
525, 508
535, 502
582, 568
518, 510
504 (broad)
588, 545
588, 550
34.3 67.8
17.8
–
–
–
37.1 69.3 36.8 69.0 12.8
31.9 64.9 32.4 65.3 14.7
12.8
14.7
12.2
7.6
8.8
12.2
15.3
N/A
N/A
a
a
45.2 74.1 45.3 73.8
36.9 70.9 37.5 70.7
36.3 57.4 36.1 57.2
9.8
7.3
8.8
N/A
N/A
a
a
N/A
103.8
N/A
N/A
a
36.1 56.3 33.3 56.7 10.9
45.7 62.3 46.1 62.1 16.5
N/A
N/A
b
b
38.2 59.7
12.8
N/A 92.2
a Satellites observed but unresolved.
b Only one isomer observed.
complexes. Selected bond lengths and angles for 8, 9,
10 and 13 are given in Table 5.
The complexes were characterised by a combination
1
of H, 31P NMR, IR, mass spectrometry and elemen-
tal analysis. All gave satisfactory results. The com-
The solid state structures of the 9 (Fig. 8) and 10
(Fig. 9) illustrate the ability of the ligand system to
adopt different ring geometries; both complexes con-
tain the same ligand, [(PhO)2P(S)NP(S)iPr2]−. In 9 the
PdS2P2N rings adopt a pseudo-boat confirmation,
whilst in 10 the PtS2P2N rings adopt pseudo-chair
confirmations. Variation in ring geometries have been
previously reported [21,22] for Pt and Pd complexes
with the general formula M[(iPr2PS)2N]2. The confor-
mational differences of the MS2P2N rings do not ap-
pear to have dramatic effects on the bond lengths,
although there are a number of noticeable angular
changes. Whilst S(1)ꢁPtꢁS(2) is 89.94(4)° in 10, the
equivalent angle is enlarged to 99.61(5)° in 9. The
plexes
formed
with
unsymmetrical
ligands
R2P(S)NHP(S)R%2 offer the potential for the formation
of cis and trans isomers if the metal adopts a square-
planar geometry. The 31P NMR spectrum of 7 is con-
sistent with the production of both species and clearly
shows two sets of doublets with equal 2J(31P–31P)
coupling of 12.8 Hz. The free ligand 6 has a higher
2J(31P–31P) coupling of 30.8 Hz, which correlates
with the increase in electron density on each phos-
phorus atom before the ligand is deprotonated. Se-
lected 31P NMR data for 7–14 are given in Table 5.
As above, the IR spectrum of 7 is indicative of a
complex in which the ligand is deprotonated. w(PꢁS)
in the complex (530 and 518 cm−1) shows a reduced
PꢁS bond order from the free ligand, whilst the
w(PNP) in the complex (1191 and 750 cm−1) shows
an increase in bond order over the free ligand. This
trend is reflected across the series of complexes. Se-
lected IR data for 7–14 are given in Table 4. The 31P
NMR spectrum of 8 displays two pairs of doublets
Table 5
,
Selected bond lengths (A) and angles (°) for 8, 9, 10 and 13
2
with equal J(31P–31P) coupling constants of 14.7 Hz.
8
9
10 13
Although the assignment of each isomer is not possi-
ble, there is again an upfield shift of ꢀ25 ppm of
the signal upon complexation. As observed for
Pt[N(Ph2PS)2]2 and Pd[N(Ph2PS)2]2, the upfield shift
for the Pt complex is ꢀ5 ppm greater than that for
the Pd complex with the same ligand.
M(1)ꢁS(1)
M(1)ꢁS(2)
S(1)ꢁP(1)
P(1)ꢁN(1)
N(1)ꢁP(2)
P(2)ꢁS(2)
2.3333(10) 2.336(2) 2.3408(12) 2.3413(6)
2.3432(10) 2.359(2) 2.3386(12) 2.3502(7)
2.0309(14) 2.008(2) 1.992(2)
1.9906(9)
1.558(2)
1.602(2)
2.0228(9)
1.591(4)
1.587(3)
1.551(5) 1.552(4)
1.615(5) 1.605(4)
2.0366(14) 2.041(2) 2.042(2)
The solid state structure of 8 (Fig. 7) reveals the
predicted square-planar geometry at the Pt centre.
The trans isomer crystallised preferentially but both
the cis and trans isomer were detected in solution by
31P NMR. The PtS2P2N rings in 8 adopt the pseudo-
chair conformation similar to previously reported
S(1)ꢁM(1)ꢁS(2)
M(1)ꢁS(1)ꢁP(1) 103.40(5)
S(1)ꢁP(1)ꢁN(1) 119.41(13) 121.4(2) 121.0(2)
P(1)ꢁN(1)ꢁP(2) 133.4(2) 123.9(3) 131.4(3)
N(1)ꢁP(2)ꢁS(2) 117.26(14) 113.9(2) 116.6(2)
P(2)ꢁS(2)ꢁM(1) 103.54(5) 105.45(8) 103.52(6)
90.93(4)
99.61(5) 89.94(4)
106.31(9) 94.77(6)
91.03(3)
99.43(3)
121.11(8)
132.82(13)
117.48(8)
98.81(3)

D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
133
Fig. 6. 31P NMR spectrum of 13.
P(1)ꢁN(1)ꢁP(2) angle in 10 [131.4(3)°] is also signifi-
cantly larger than in 9 [123.9(3)°].
phorus has alkyl substituents we note that the palla-
dium complex adopts a pseudo-boat conformation,
whilst the platinum complex adopts a pseudo-chair
conformation.
The solid state structure of 13 (Fig. 10) again dis-
plays the expected square-planar Pd centre, with the
PdS2P2N rings both adopting the pseudo-chair confor-
mation. Interestingly, when both cis and trans isomers
were seen in solution (Fig. 6) it is the trans isomer that
has been isolated in all the single crystals studied in
X-ray diffraction experiments. It is of interest to note
that in all of the published palladium and platinum
examples of imidophosphinates, when even one phos-
4. Conclusions
The R2P(S)NHP(S)R% ligand system can be readily
2
synthesised in good yields. The variation of R and R%
leads to differing conformations in the solid state.
When forming complexes it is clear that the dithioimi-
Fig. 8. Solid state structure of 9.
Fig. 7. Solid state structure of 8.

134
D.J. Birdsall et al. / Polyhedron 20 (2001) 125–134
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
Acknowledgements
We are grateful to the JREI for equipment grants.
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5. Supplementary material
Atomic coordinates, thermal parameters and bond
lengths and angles have been deposited at the Cam-
bridge Crystallographic Data Centre (CCDC), CCDC
nos. 147233–147241. Any request to CCDC for this
material should quote the full literature citation and the
reference number. Copies of this information may be
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.