Complexes of sterically-hindered diaminophosphinothiolate ligands with Rh(I), Ni(II) and Pd(II)

Article abstract of DOI:10.1016/j.poly.2011.04.041

Two new sterically demanding diaminophosphinothiolate ligands (HL ¹ and HL²) have been prepared and the X-ray crystal structure of the Li salt of HL² has been determined. The complex [Pd(L¹)₂] was fully characterized, but in contrast to other phosphinothiolates, complexes with the M(L)₃ stoichiometry could not be prepared. Reaction of LH¹ with Ni(II) led to cleavage of the arythiolate group and isolation of a thiolate bridged dimer, confirmed by an X-ray crystal structure. The Rh(I) complexes [Rh(nbd)L] (L = L¹, L²) were characterized including an X-ray structure.

Full text of DOI:10.1016/j.poly.2011.04.041

Polyhedron 30 (2011) 1849–1856
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Complexes of sterically-hindered diaminophosphinothiolate ligands with Rh(I),
Ni(II) and Pd(II)
⇑
⇑
Alasdair J. Robbie, Andrew R. Cowley, Michael W. Jones , Jonathan R. Dilworth
Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Two new sterically demanding diaminophosphinothiolate ligands (HL1 and HL2) have been prepared and
the X-ray crystal structure of the Li salt of HL2 has been determined. The complex [Pd(L1)2] was fully char-
acterized, but in contrast to other phosphinothiolates, complexes with the M(L)3 stoichiometry could not
be prepared. Reaction of LH1 with Ni(II) led to cleavage of the arythiolate group and isolation of a thiolate
bridged dimer, confirmed by an X-ray crystal structure. The Rh(I) complexes [Rh(nbd)L] (L = L1, L2) were
characterized including an X-ray structure.
Article history:
Received 28 February 2011
Accepted 17 April 2011
Available online 3 May 2011
Keywords:
PS-ligands
Sterically hindered
X-ray crystal structures
Metal complexes
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
[18]. We here investigate if new complexes with coordinative
unsaturation or novel structures could be generated by increasing
There has been considerable interest in the coordination chem-
istry of multidentate ligands incorporating phosphorus donors in
combination with thiolate, oxide or nitrogen donors. The combina-
tion of phosphorus with sulfur provides particularly versatile
ligands capable of forming complexes with a wide variety of coor-
dination modes. The most widely investigated class are probably
the 2-phosphinoaryl thiolates which are readily available via the
direct lithiation of arene thiolates and reaction with the appropri-
ate phosphine halide [1,2]. Bidentate phosphinothiolates of the
type Ph2PC6H4SH-2 have been shown to be potent ligands, forming
stable complexes with a wide range of metal and metalloid ele-
ments. The dominant structural motif for divalent and trivalent
metal ions with the bidentate ligands are complexes of the types
[M(PS)2] (M = Ni, Pd, Pt) [3–8] and [M(PS)3] (M = Re, Tc, Ru, Rh,
Ir) [9–16]. The topic of phosphinothiolate chemistry in general
was reviewed comprehensively in 2000 [17]. Since that time re-
search has focused on phosphino alkylthiolates and there have
been relatively few reports on the chemistry of the phosphinoaryl-
thiolates. However, some investigations of the chemistry of the
coordinated ligands have been made. In the case of M = Ru, the
anionic Ru(II) complexes [Ru(PS)3]ꢀ can be oxidized in two one
electron steps to give complexes where the sulfur atoms have sig-
nificant thiyl radical character [16]. This confers reactivity and the
complexes can undergo reactions at the coordinated sulfur, such as
CAS bond formation [16] and oxidation with atmospheric oxygen
the steric bulk of the ligand at phosphorus. In the past steric con-
gestion has been introduced adjacent to sulfur using groups such
as Me3Si at the 6-position of the arene thiolate group [19]. How-
ever, this did not change the stoichiometry as complexes of the
type [Fe(PS)3] were formed with both the simple PS ligand and
the sterically hindered analog [19]. We were therefore interested
to see if using very large sterically hindered phosphino substitu-
ents would have any impact on the nature of the complexes
formed. We here report the synthesis and coordination chemistry
of the new 2-diazaphospholiden-2-ylbenzenethiolate proligands
of the type shown in Fig. 1.
2. Experimental
2.1. Materials and instrumentation
All reactions were carried out using standard Schlenk-line tech-
niques under an atmosphere of anhydrous N2. All 1H, 13C{1H} and
31P{1H} NMR spectra were recorded on a Varian Mercury VX 300
spectrometer (1H at 300 MHz, 13C{1H} at 75.5 MHz and 31P{1H} at
121.5 MHz) or a Varian Unity 500 MHz spectrometer (1H at
499.9 MHz, 13C{1H} at 125.7 MHz and 31P{1H} at 202.4 MHz). 1H
and 13C{1H} NMR spectra were referenced internally to the residual
solvent resonance or tetramethylsilane at zero ppm (for 1H NMR)
and 31P{1H} spectra were externally referenced to 85% H3PO4 at
zero ppm. Chemical shift values are quoted in ppm and all coupling
constants are quoted in Hertz (Hz). Signal multiplicities are desig-
nated by s = singlet, d = doublet, dd = doublet of doublets and
m = multiplet, and the abbreviation br = broad.
⇑
Corresponding authors. Tel.: +44 1865285155.
E-mail addresses: michael.jones@chem.ox.ac.uk (M.W. Jones), jonathon.dilworth
@chem.ox.ac.uk (J.R. Dilworth).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.04.041

1850
A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
combined and evaporated to dryness in vacuo yielding an orange/
brown solid (1.8 g, 5.9 mmol, 98%). Anal. Calc. for C16H18N2PCl: C,
63.1; H, 6.0; N, 9.2; Cl, 11.6. Found: C, 63.0; H, 6.5; N, 8.9; Cl,
3
9.8%. 1H NMR (CDCl3): d 7.07 (d, JHAH = 8 Hz, 4H, m-Ph), 6.98
3
4
3
(dd, JHAH = 8 Hz, JHAP = 2 Hz, 4H, o-Ph), 3.83 (d, JHAP = 5 Hz, 4H,
CH2), 2.24 (s, 6H, CH3). 13C{1H} NMR (CDCl3):
d 140.1 (d,
2JCAP = 20 Hz, i-Ph), 131.8 (s, p-Ph), 130.1 (s, m-Ph), 117.2 (d,
2
Fig. 1. Structures of 2-diarylphospholiden-2-yl benzenethiolate proligands.
3JCAP = = 14 Hz, o-Ph), 48.1 (d, JCAP = 10 Hz, CH2N), 20.7 (s, CH3).
31P{1H} NMR (CDCl3): d 138.8 (s). Mass spectrum (ES+): m/
z = 269.1 [LꢀCl]+. High Resolution MS (ES+), found (calc): m/
z = 269.1211 (269.1208), [LꢀCl]+. Selected IR/cmꢀ1 (KBr disk):
Electrospray mass spectrometry was performed on a Micromass
LCT Time of Flight Mass Spectrometer with a ‘Z’ Spray electrospray
source. Probe Electron Impact and Field Ionisation mass spectrom-
etry were performed on a Micromass GCT Time of Flight Mass
Spectrometer, with a heated solid probe. FAB mass spectrometry
was performed on a Fisons Autospec, using dithiothreitol and
dithioerythritol or m-nitrobenzyl alcohol as the matrix. Infra red
spectra were recorded on a Perkin Elmer Paragon 1000 FT-IR spec-
trometer and GRAMS Analyst software by Galactic Industries was
used in conjunction with this. Abbreviations: w = weak, m = med-
ium, s = strong intensity absorption, sh = sharp, and br = broad
peak width. Elemental analyses were measured on an Elementor
varioEL. All measurements were performed by the elemental anal-
ysis department of the Inorganic Chemistry Laboratory, University
of Oxford. The ligand precursor lithium 2-lithiobenzenethiolate/
TMEDA complex was prepared as a solution in hexane and is de-
scribed in the literature [20].
2919 (m, br, mCAH stretch), 1573 (w, mC@C aromatic), 780 (w, mPAN).
2.2.3. Preparation of lithium 2-(1,3-diphenyl-1,3,2-diazaphospholidin-
2-yl)benzenethiolate, Li[L1]
To a suspension of lithium 2-lithio-benzenethiolate/TMEDA
complex (1.65 g, 4.66 mmol) in hexane (20 cm3) at 0 °C, a gently
warmed, clear, orange/brown toluene solution (10 cm3) of
2-chloro-1,3-diphenyl-1,3,2-diazaphospholidine (1.40 g, 5.05 mmol)
was added drop-wise over a period of 3 min. The mixture was stirred
at 0 °C for 5 min, at room temperature for 10 min, and then heated to
50 °C for a further 90 min. The solvent was then removed under
vacuum and the brown solid triturated with hexane (20 cm3). The
solid produced was isolated by filtration, washed with toluene
(2 ꢁ 10 cm3), and hexane (10 cm3) and dried in vacuo producing
an off white solid (1.75 g, the yield is unknown due to the unknown
composition of the solid produced). 1H NMR (CDCl3): d 7.48 (dd,
4
3JHAH = 8 Hz, JHAP = 5 Hz, 1H, CHCS), 7.10–7.20 (m, 8H, o-Ph and
m-Ph), 6.95 (pseudo t, 3JHAH = 7 Hz, 1H, CHCHCS), 6.90 (m, 1H, CHCP),
6.70–6.80 (m, 3H, p-Ph and CHCHCP), 3.85 (m, 2H, NH2a), 3.57 (m,
2H, NH2b), 2.20 (s, 6H, TMEDA-NCH2), 1.92 (s, 18H, TMEDA-NCH3).
2.2. Synthetic work
2.2.1. Preparation of 2-chloro-1,3-diphenyl-1,3,2-diazaphospholidine
2-Chloro-1,3-diphenyl-1,3,2-diazaphospholidine was prepared
in a similar manner to the previously published 2-chloro-1,3-
di(2,4,6-trimethylphenyl)-1,3,2-diazaphospholidine [21]. To a clear,
orange/brown solution of N,N0-diphenylethylenediamine (1.27 g,
6 mmol) in CH2Cl2 (40 cm3), anhydrous degassed triethylamine
(16 cm3, 115 mmol) was added. The solution was cooled to 0 °C,
and phosphorus trichloride (0.52 cm3, 6 mmol) added slowly over
a period of 5 min giving a brown solution with small amounts of a
white precipitate. The solution was stirred at 0 °C for 30 min, then
at room temperature for a further 90 min and then all the volatile
components were removed under vacuum. The orange/brown solid
produced was extracted with thf (3 ꢁ 10 cm3). The thf solutions
were combined and evaporated to dryness in vacuo yielding a brown
free-flowing solid (1.8 g, 5.9 mmol, 98% yield). Anal. Calc. for
2
13C{1H} NMR (CDCl3): d 155.7 (d, JCAP = 31 Hz, CS), 147.8 (d,
1
2JCAP = 17 Hz, i-Ph), 138.7 (d, JCAP = 14 Hz, CP), 135.7 (s, CHCP),
3
130.2 (d, JCAP = 7 Hz, CHCS), 129.5 (s, CHCHCP), 129.3 (s, m-Ph),
3
120.5 (s, CHCHCS), 119.6 (s, p-Ph), 116.4 (d, JCAP = 13 Hz, o-Ph),
2
57.0 (s, TMEDA-NCH2), 46.9 (d, JCAP = 7 Hz, NCH2), 46.1 (s, TME-
DA-NCH3). 31P{1H} NMR (CDCl3): d 89.5 (s, br). Mass spectrum
(ES+): m/z = 349.1 [LꢀLi]+, 317.1 [LꢀLiꢀS]+.
2.2.4. Preparation of lithium 2-(1,3-di-p-tolyl-1,3,2-diazaphospho-
lidin-2-yl)benzenethiolate, Li[L2]
To a suspension of lithium 2-lithio-benzenethiolate/TMEDA
complex (1.6 g, 4.6 mmol) in hexane (20 cm3) at 0 °C, a lightly
warmed, clear, orange/brown toluene solution (10 cm3) of
2-chloro-1,3-di-p-tolyl-1,3,2-diazaphospholidine (1.50 g, 4.9 mmol)
was added drop-wise over a period of 3 min. The mixture was stir-
red at 0 °C for 5 min, at room temperature for 10 min, and then
heated to 50 °C for a further 90 min. The volatiles were removed
under vacuum and the brown solid triturated with hexane
(20 cm3). The solid produced was isolated by filtration, washed
with toluene (2 ꢁ 10 cm3), and hexane (10 cm3) and dried in vacuo
producing an off-white solid (1.67 g, the yield is unknown due to
the unknown composition of the solid produced). 1H NMR (CDCl3):
C
14H14N2PCl: C, 60.8; H, 5.1; N, 10.1; Cl, 12.8. Found: C, 60.8; H,
5.2; N, 10.1; Cl, 10.9%. 1H NMR (d8-Toluene): d 7.11 (pseudo t,
3
JHAH = 8 Hz, 4H, m-Ph), 6.96 (m, 4H, o-Ph), 6.85 (t, JHAH = 7 Hz,
2H, p-Ph), 3.26 and 3.07 (two s, br, 4H, CH2CH2). 13C{1H} NMR
(d8-Toluene): d 143.1 (d, JCAP = 15 Hz, i-Ph), 129.6 (s, o-Ph), 122.1
2
(s, p-Ph), 117.2 (s, br, m-Ph), 47.5 (d, JCAP = 10 Hz, CH2). 31P{1H}
2
NMR (d8-Toluene): d 137.4 (s). Mass spectrum (ES+): m/z = 241.2
[LꢀCl]+. High Resolution MS (ES+), found (calc): m/z = 241.0894
(241.0895), [LꢀCl]+. Selected IR/cmꢀ1 (KBr disk): 3038
3
3
d 7.51 (dd, JHAH = 5 Hz, JHAP = 3 Hz, 1H, CHCS), 7.15–7.25 (d,
3JHAH = 8 Hz, 4H, o-Ph), 6.90–7.10 (m, 6H, m-Ph, CHCP and
CHCHCS), 6.80 (t, 3JHAH = 15 Hz, 1H, CHCHCP), 3.92 (m, 2H, NCH2a),
3.64 (m, 2H, NCH2b), 2.20–2.30 (m, 10H, CCH3 and TMEDA-NCH2),
1.87 (s, 12H, TMEDA-NCH3). 13C{1H} NMR (CDCl3): d 155.7 (d,
(m, mCAH aromatic), 2893 (m, mCAH aliphatic), 1599 (s, mC@C).
2.2.2. Preparation of 2-chloro-1,3-di-p-tolyl-1,3,2-diazaphospholidine
To a clear, colorless solution of N-(2-(4-toluidino)ethyl)-4-
methylbenzenamine [22,23] (1.44 g, 6 mmol) and triethylamine
(16 cm3, 0.11 mol) in CH2Cl2 (40 cm3) cooled to 0 °C, phosphorus
trichloride (0.52 cm3, 0.82 g, 6 mmol) was added slowly from a syr-
inge over a period of 3 min. The mixture was stirred at 0 °C for
30 min and then at room temperature for a further 90 min. The vol-
atiles were removed under vacuum, and the resulting yellow solid
was extracted with thf (3 ꢁ 15 cm3). The thf solutions were then
2
2JCAP = 31 Hz, CS), 145.4 (d, JCAP = 16 Hz, i-Ph), 138.7 (d,
3
2JCAP = 14 Hz, CP), 136.2 (s, CHCP), 130.2 (d, JCAP = 8 Hz, CHCS),
129.9 (s, m-Ph), 129.6 (s, CHCHCS), 129.5 (s, p-Ph), 120.5 (s,
3
CHCHCP), 116.6 (d, JCAP = 13 Hz, o-Ph), 57.1 (s, TMEDA-NCH2),
2
47.1 (d, JCAP = 6 Hz, NCH2), 45.9 (s, TMEDA-NCH3), 20.6 (s, CCH3).
31P{1H} NMR (CDCl3): d 94.7 (s, br). Mass spectrum (ES+): m/
z = 377.1 [LꢀLi]+.

A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
1851
2.2.5. Preparation of [Rh(2-(1,3-diphenyl-1,3,2-diazaphospholidin-2-
yl)benzenethiolate)(nbd)], 3
stirred at room temperature for 1 h, during which time no further
change occurred. The solid was isolated by filtration, washed with
methanol (3 cm3) and diethyl ether (2 ꢁ 5 cm3) and dried under
vacuum (0.21 g, 0.26 mmol, 79%). Anal. Calc. for C40H36N4P2PdS2:
C, 59.7; H, 4.5; N, 7.0. Found: C, 59.9; H, 4.9; N, 6.6%. 1H NMR
(CD2Cl2): d 6.50–7.60 (m, 28H, aromatics), 4.02 (m, 4H, CH2N),
3.92 (m, 4H, CH2N). 13C{1H} NMR (CD2Cl2): d 141.2 (virtual t,
2JCAP = 10 Hz, i-Ph), 132.8 (s, CHCHCS), 129.7 (m, CHCHCP and
CHCS), 129.1 (m, m-Ph), 122.7 (m, CHCP), 120.8 (s, p-Ph), 115.8
To a dark red solution of [Rh(nbd)2]+BF4ꢀ (0.25 g, 0.67 mmol) in
CH2Cl2 (20 cm3), the ligand lithium 2-(1,3-diphenyl-1,3,2-diaza-
phospholidin-2-yl)benzenethiolate Li[L1] (0.32 g, 0.67 mmol) was
added forming a dark orange/red solution immediately. The solu-
tion was stirred at room temperature for 1 h, during which time
no change occurred. The volume was reduced to ca. 5 cm3 and pen-
tane (50 cm3) added to precipitate. The solid produced was re-
moved by filtration and the CH2Cl2/pentane solutions evaporated
to dryness producing bright orange/red solid which was washed
with pentane (2 ꢁ 4 cm3) and dried in vacuo (0.26 g, 0.48 mmol,
71%). Anal. Calc. for C27H26N2PRhS: C, 59.6; H, 4.8; N, 5.2. Found:
C, 59.2; H, 5.2; N, 4.8%. 1H NMR (CD2Cl2): d 7.40–7.50 (m, 5H,
o-Ph and CHCS), 7.25–7.3 (m, 4H, m-Ph), 7.00–7.15 (m, 2H, CHCHCP
and CHCHCS), 6.92 (tt, 3JHAH = 7 Hz, 4JHAH = 1 Hz, 2H, p-Ph), 6.76 (tt,
3
(virtual t, JCAP = 10 Hz, o-Ph), 46.2 (s, CH2CH2). 31P{1H} NMR
(CD2Cl2): d 116.7 (s), 104.8 (s). Mass spectrum (ES+): m/z = 805.1
[M+H]+, 811.1 [M+Li]+, 827.1 [M+Na]+. Selected IR/cmꢀ1 (KBr disk):
3058 (w, mCAH aromatic), 2868 (w, mCAH aliphatic), 1597 (s, mC@C).
2.2.8. Attempted synthesis of [Ni(2-(1,3-diphenyl-1,3,2-diazaphos-
pholidin-2-yl)benzenethiolate)2], preparation of Ni2{SC6H4P(NPh)2-
C2H4}2(SPh)2], 6
4
3JHAH = 8 Hz, JHAP = 1 Hz, 1H, CHCP), 5.66 (m, 2H, C@CH), 4.05 (m,
2H, CH2N), 3.85 (m, 2H, CH2N), 3.70 (m, 2H, CHCH2), 3.54 (m, 2H,
To
a clear colorless solution of lithium 2-(1,3-diphenyl-
C@CH), 1.52 (m, 2H, nbd-CH2). 13C{1H} NMR (CD2Cl2): d 155.4 (d,
1,3,2-diazaphospholidin-2-yl)benzenethiolate Li[L1] (0.45 g, ꢂ1.00
mmol) in methanol (10 cm3), [Ni(acac)2]ꢃ4H2O (0.124 g, 0.50 mmol
was added forming a dark brown precipitate immediately. The
solution was stirred at room temperature for 2 h, during which
time no further change occurred. The volume of the solution was
reduced to ca. 3 cm3 in vacuo, the solid isolated by filtration,
washed with diethyl ether (2 ꢁ 5 cm3) and dried under vacuum
(0.27 g, 0.36 mmol, 71%). 1H NMR (CD2Cl2): d 6.60–7.50 (m, 31H,
aromatics), 4.24 (m, CH2N), 4.20 (m, CH2N), 4.02 (m, CH2N), 3.92
(m, CH2N). 31P{1H} NMR (CD2Cl2): d 121.0 (s), 115.1 (s), 107.6 (s).
Mass spectrum (ES+): m/z = 757.1 [M+H]+. Selected IR/cmꢀ1 (KBr
2
1JCAP = 41 Hz, CAP), 143.4 (d, JCAP = 11 Hz, i-Ph), 139.3 (dd,
2
2JCAP = 41 Hz, JCARh = 10 Hz, CAS), 132.7 (s, CHCHCS), 130.0 (s,
2
CHCHCP), 129.5 (s, CHCS), 129.1 (s, m-Ph), 122.4 (d, JCAP = 5 Hz,
3
CHCP), 120.5 (s, p-Ph), 116.5 (d, JCAP = 9 Hz, o-Ph), 91.8 (dd,
1
2JCAP = 13 Hz, JCARh = 4 Hz, C@C), 67.7 (s, nbd-CH2), 59.1 (m,
3
C@C), 53.1 (d, JCAP = 8 Hz, CCH2), 46.5 (s, CH2CH2). 31P{1H} NMR
1
(CD2Cl2): d 118.5 (d, JPARh = 224 Hz). Mass spectrum (ES+): m/
z = 545.1 [M+H]+, 551.1 [M+Li]+, 567.1 [M+Na]+, 583.1 [M+K]+.
2.2.6. Preparation of [Rh(2-(1,3-di-p-tolyl-1,3,2-diazaphospholidin-2-
yl)benzenethiolate)(nbd)], 4
disk): 3058 (w,
mCAH aromatic), 2865 (w, mCAH aliphatic), 1597 (s, mC@C).
To a dark red solution of [Rh(nbd)2]+BF4ꢀ (0.25 g, 0.67 mmol) in
CH2Cl2 (20 cm3), the ligand lithium 2-(1,3-di-p-tolyl-1,3,2-diaza-
phospholidin-2-yl)benzenethiolate Li[L2] (0.335 g, 0.67 mmol)
was added forming a dark orange/red solution immediately. The
solution was stirred at room temperature for 1 h, during which
time no change occurred. A small amount of solid was removed
by filtration, and the resulting clear bright orange/red solution
was evaporated to dryness producing bright orange/red solid
which was washed with pentane (2 ꢁ 4 cm3) and dried under vac-
uum (0.38 g, 0.66 mmol, 99%). Anal. Calc. for C29H30N2PRhS: C,
60.8; H, 5.3; N, 4.9. Found: C, 60.4; H, 5.0; N, 5.0%. 1H NMR
2.3. Crystallographic methods
X-ray crystal structures were determined by mounting a single
crystal encased in perfluoropolyether oil on a glass fiber and then
cooling rapidly to 150 K in a stream of cold N2 using an Oxford
Cryosystems CRYOSTREAM unit [24]. Diffraction data was subse-
quently measured at 150 K using an Enraf-Nonius KappaCCD
diffractometer (graphite-monochromated Mo K
a radiation, k =
0.71073 Å) over the range of 5.0 6 h 6 27.5°. Intensity data were
processed using the DENZO-SMN package [25]. The structures
were solved using the direct-methods program SIR92 [26], which
located all non-hydrogen atoms of the complexes. Subsequent
full-matrix least-squares refinement on F was carried out using
the CRYSTALS program suite [27]. Absorption correction was semi-
empirical from equivalent reflections. Hydrogen atoms were posi-
tioned geometrically after each cycle of refinement. A 3-term
Chebychev polynomial weighting scheme was applied. Crystal data
and structure refinement parameters are included in Table 1.
4
(CD2Cl2): d 7.35–7.45 (dd, 3JH AH = 8 Hz, JHAP = 4 Hz, 1H, CHCS),
7.34 (dd, 3JHAH = 8 Hz, 4JHAP = 1 Hz, 4H, o-Ph), 7.09 (d, 3JHAH = 8 Hz,
4H, m-Ph), 7.00–7.10 (m, 2H, CHCHCP and CHCHCS), 6.74 (tt,
4
3JHAH = 7 Hz, JHAP = 2 Hz, 1H, CHCP), 5.66 (m, 2H, C@CH), 4.00
(m, 2H, CH2N), 3.80 (m, 2H, CH2N), 3.72 (m, 2H, CHCH2), 3.56 (m,
2H, C@CH), 2.28 (s, 6H, CH3) 1.55 (m, 2H, nbd-CH2). 13C{1H} NMR
1
2
(CD2Cl2): d 155.4 (d, JCAP = 33 Hz, CAP), 141.0 (d, JCAP = 11 Hz,
2
2
i-Ph), 139.4 (dd, JCAP = 32 Hz, JCARh = 9 Hz, CAS), 132.8 (d,
4JCARh = 2 Hz CHCHCS), 129.6 (m, m-Ph, CHCHCP and CHCS), 122.3
2
3
(d, JCAP = 6 Hz, CHCP), 116.4 (d, JCAP = 8 Hz, o-Ph), 113.2 (s,
2
1
p-Ph), 91.7 (dd, JCAP = 12 Hz, JCARh = 4 Hz, C@C), 67.6 (d,
2.4. Results and discussion
4JCAP = 4 Hz, nbd-CH2), 58.9 (d, JCAP = 10 Hz, C@C), 53.1 (obscured
2
by solvent, CCH2), 46.6 (s, CH2CH2), 20.4 (s, CH3). 31P{1H} NMR
The lithium salts of the new ligands were prepared using a
modification of the published route for 2-diaryphosphinothiolate
ligands via the ortho-lithiation of thiophenol [20] and reaction with
the appropriate 2-chloro-1,3-diaryl-1,3,2-diazaphospholidine [21]
in a 2:1 toluene–hexane mixture. The lithium salts were isolated
as air-sensitive white solids and incorporated 1.5 equivalents of
TMEDA (N,N,N0,N0-tetramethylethylenediamine) which was pres-
ent from the solution of lithium 2-lithiobenzenethiolate/TMEDA
complex precursor used. For the salt with aryl = 4-tolyl (L2), crys-
tals suitable for an X-ray structure determination were obtained
upon standing the mother liquor at room temperature overnight.
An ORTEP representation of the structure is shown in Fig. 2 and
selected bond lengths and angles displayed in Table 2.
1
(CD2Cl2): d 115.1 (d, JPARh = 224 Hz). Mass spectrum (ES+): m/
z = 573.1 [M+H]+, 579.1 [M+Li]+, 595.2 [M+Na]+, 611.1 [M+K]+. High
Resolution MS (ES+), found (calc): m/z = 573.0988 (573.1001), [M]+.
Selected IR/cmꢀ1 (KBr disk): 3035 (w, mCAH aromatic), 2989, 2919,
2855 (w, mCAH aliphatic), 1616 (w, mC@C).
2.2.7. Preparation of [Pd(2-(1,3-diphenyl-1,3,2-diazaphospholidin-2-
yl)benzenethiolate)2], 5
To a clear dark brown solution of Na2PdCl4 (0.10 g, 0.33 mmol)
in methanol (7 cm3), lithium 2-(1,3-diphenyl-1,3,2-diazaphosphol-
idin-2-yl)benzenethiolate Li[L1] (0.35 g, ꢂ0.73 mmol) was added
forming an orange precipitate immediately. The solution was

1852
A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
Table 1
Summary of the crystallographic parameters for compounds Li[L2], 3, 5 and 6.
Crystal identification
Li[L2]
3
5
6
Chemical formula
Formula weight
Crystal system
Space group
a (Å)
C
62H92ClLi3N10P2S2
C27H26N2PRhS
544.46
monoclinic
P21/c
9.5787(2)
14.1261(3)
18.0712(5)
90
105.0861(9)
90
2360.94(10)
4
1.532
0.898
1112
C42H40Cl4N4P2PdS2
975.10
C158H142Cl4N12Ni6P6S12
3273.44
1159.84
orthorhombic
Aba2
27.4303(3)
22.1492(2)
11.0717(2)
90
triclinic
triclinic
ꢀ
ꢀ
P1
P1
9.5532(4)
9.6527(4)
11.2342(5)
89.7843(18)
80.4544(19)
89.4097(19)
1021.55(8)
1
10.8756(2)
15.7082(3)
24.2802(5)
106.3675(10)
93.7148(9)
109.4812(8)
3693.75(13)
2
b (Å)
c (Å)
a
(°)
b (°)
(°)
90
90
c
Cell volume (Å3)
Z
6726.71(15)
4
1.145
0.210
2488
Dcalc (Mg/m3)
1.585
0.934
496
1.472
1692
1.113
Absorption coefficient (mmꢀ1
F(0 0 0)
)
Crystal size (mm)
Description of crystal
Transmission coefficients (minimum, maximum)
Index ranges
0.10 ꢁ 0.24 ꢁ 0.36
Pale-yellow tablet
0.93, 0.98
0 6 h 6 35,
0 6 k 6 28,
0 6 l 6 14
61 092
0.08 ꢁ 0.24 ꢁ 0.24
Orange–red fragment
0.81, 0.93
ꢀ12 6 h 6 12,
0 6 k 6 18,
0 6 l 6 23
17 222
0.08 ꢁ 0.28 ꢁ 0.32
Orange-yellow plate
0.74, 0.93
ꢀ12 6 h 6 12,
ꢀ12 6 k 6 12,
0 6 l 6 14
14 614
0.14 ꢁ 0.18 ꢁ 0.18
dark-brown fragment
0.82, 0.86
ꢀ14 6 h 6 14,
ꢀ20 6 k 6 20,
ꢀ30 6 l 6 31
48 110
Reflections measured
Unique reflections
Rint
7661
0.053
5564
0.034
4653
0.047
16 773
0.049
Observed reflections (I > 3
r(I))
6248
4067
3226
10 163
Parameters refined
363
305
250
964
Goodness of fit
1.0822
1.1131
1.1138
1.0901
R
0.0365
0.0279
0.0340
0.0409
wR
0.0415
ꢀ0.30, 0.40
0.0304
ꢀ0.61, 0.61
0.0368
ꢀ0.54, 0.38
0.0488
ꢀ0.42, 0.52
Residual electron density (minimum, maximum) (e Åꢀ3
)
The six-membered assembly of three Li+ ions, one Clꢀ ion and
two of the sulfur atoms of the 1,3,2-diazaphospholidin-2-ylben-
zenethiolate unit is located on a crystallographic twofold axis
of symmetry. The Li3ClS2 ring is appreciably non-planar, with
the sulfur atoms displaced by 0.67 Å from the plane of the lith-
ium and chloride ions. The PAN bond lengths of 1.7209(19) and
1.7402(17) Å are at the upper range of values expected for a
PAN single bond [28]. The five-membered 1,3,2-diazaphospholi-
dine ring has similar geometry to the previously published plat-
inum-1,3,2-diazaphospholidine complex [29], and the bond
angles around the phosphorus atom are similar to the literature
values [29]. The P(1)AC(6) bond length at 1.843(2) Å is consis-
tent with the value of 1.8251(15) Å for the cyclic lithium salt,
[{(Me3Si)2CH}P(C6H4-2-S){Li(tmeda)}]{Li(tmeda)}, synthesized by
Clegg and co-workers [30]. This indicates that the long PACl
bond observed in the solid state structure of compounds similar
to the ligand precursor is a result of the bonding between phos-
phorus and chlorine atoms and not as a result of the presence of
the 1,3,2-diazaphospholidine ring.
The 1H NMR spectrum for Li[L2]ꢃ0.5LiClꢃ1.5TMEDA in CDCl3
shows the presence of 1.5 equivalents of TMEDA for each PS unit
in accord with the stoichiometry of the X-ray structure. However,
the fact that the TMEDA protons are observed as two sharp singlets
in the 1H NMR spectrum and the carbons as two sharp singlets in
the 13C suggests that the TMEDA molecules are magnetically
equivalent. This indicates that it is unlikely that the solid state
structure is preserved in the solution state or that there is a rapid
fluxional process. All of the other 1H NMR resonances for L1 and L2
are consistent with the observed solid state structure shown in
Fig. 2. The 31P NMR spectrum for Li[L2]ꢃ0.5LiClꢃ1.5TMEDA shows
a broad singlet at 94.7 ppm (cf. 89.5 ppm for L1) which is in the
same region as the previously published compound 1,2,3-
triphenyl-1,3,2-diazaphospholidine (83.2 ppm) [31]. The broad
nature of the 31P NMR peak could be due to the fluxional coordina-
tion/dissociation of the lithium and TMEDA in solution and the
Fig. 2. ORTEP representation (50% probability ellipsoids) of the molecular structure
of the LiCl/TMEDA adduct of the proligand Li[L2]. Hydrogen atoms have been
omitted for clarity.
Table 2
Selected bond distances (Å) and angles (°) for Li[L2]ꢃ0.5LiClꢃ1.5TMEDA.
Li(1)ACl(1)
Li(1)AS(1)
Li(2)AS(1)
S(1)AC(1)
2.259(3)
2.474(3)
2.483(2)
1.7575(19)
S(1)AC(1)
P(1)AC(6)
P(1)AN(2)
1.843(2)
1.7209(19)
1.7402(17)
S(1)ALi(2)AS(1)
Li(1)AS(1)ALi(2)
S(1)ALi(2)ACl(1)
Li(1)AP(1)AN(2)
123.45(17)
108.77(11)
125.36(13)
114.82(16)
N(1)AP(1)AN(2)
N(1)AP(1)AC(6)
N(1)AP(1)AN(2)
118.40(8)
120.79(8)
91.88(10)

A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
1853
inherent fluxionality of the five-membered diazaphospholidine
ring. Attempts to remove the LiCl by recrystallization were not suc-
cessful and only uncharacterizable solids were obtained which did
not react cleanly with the precursor complexes. The initial solid
obtained from the ligand synthesis was therefore reacted without
further purification. Previously, especially with the extremely ver-
satile 2-(diphenylphosphino)benzenethiolate ligand (DPPTH), the
bidentate phosphinothiolate ligands readily and cleanly formed
complexes with a range of transition metals. However, the ligands
HL1 and HL2 (or their lithium salts), when reacted with any of the
ruthenium, tungsten or rhenium precursors used successfully for
DPPTH, formed intractable mixtures that could not be character-
ized. This suggests that in contrast to all other aromatic phosphino-
thiolates investigated the octahedral complexes [M(PS)3] are not
accessible with these very large phosphine substituents. We
therefore turned our attention to metals that formed square planar
complexes with [M(PS)2] stoichiometries (Scheme 1).
side being directed towards the aryl ring. They appear as complex
multiplets due to couplings to the geminal and vicinal protons and
phosphorus. The asymmetric P,S-donor set results in the C@CH
protons at opposite ends of the nbd ligand being inequivalent as
the two carbon atoms to which they are attached are trans to dif-
ferent donor atoms. This results in the nbd protons appearing as
four multiplets (eight protons). Finally, the 14 aromatic protons
are observed between 6.76 and 7.50 ppm as expected. The 13C
NMR showed the expected 10 resonances all of which have been
assigned and are consistent with the structure. Upon recrystalliza-
tion of 3 by layering a CH2Cl2 solution with pentane, an orange–red
polycrystalline aggregate was produced. This was cut to give a
plate-like fragment which was used for X-ray structure determina-
tion. An ORTEP representation of the structure is shown in Fig. 3
and selected bond lengths and angles are presented in Table 3.
The X-ray crystal structure shows that the PAN bond lengths are
indicative of single bonds at 1.705(2) and 1.696(2) Å for P(1)AN(1)
and P(1)AN(2), respectively. The RhASACACAP chelate ring is
essentially planar with the sum of the internal angles at 539.86°
(cf. 540° for a planar pentagon). The Rh(1)AP(1) bond length of
2.2066(6) Å is similar to the published values for the known
compounds [Rh(cod)(S,P-SC2B10H10PPh2)], A at 2.2615(9) Å, and
2.4.1. Synthesis and structural behavior of [Rh(L1)(nbd)]BF4 (3) and
[Rh(L2)(nbd)]BF4 (4)
The reaction of approximately one equivalent of the ligand lith-
ium 2-(1,3-diphenyl-1,3,2-diazaphospholidin-2-yl)benzenethiol-
ate L1 or L2 with [Rh(nbd)2)]+BF4 (nbd = norbornadiene) in
ꢀ
[{Rh(S,P-l-SC2B10H10PPh2)(CO)}2], B at 2.224(3) Å [32]. Similarly,
the Rh(1)AS(1) bond length of 2.3071(7) Å is comparable to those
reported for A and B at 2.295(1) and 2.349(3) Å, respectively [32].
As anticipated, the analytical and spectroscopic data for 4 were
similar to the closely related complex 3. Unfortunately, we were
unable to grow crystals of 4 suitable for X-ray crystallographic
analysis. There was no evidence for a complex of the type
[Rh(PS)2]ꢀ even with the use of an excess of the lithium salt of
the ligand.
CH2Cl2 at room temperature produced a bright red solution almost
immediately. After the volume was reduced to ca. 5 cm3, pentane
was added producing a small amount of an orange precipitate. This
solid was removed by filtration and the resulting clear bright red
solution evaporated to dryness. The red colored solid produced
was washed with pentane and dried under vacuum, giving 3 and
4 as orange/red microcrystalline solids in 71% and 99% yields,
respectively. The elemental analysis was consistent with the for-
mulation [Rh(L1)(nbd)]. The positive electrospray mass spectrum
for 3 shows a series of peaks with the most intense peaks at m/
z = 545.1, 551.1, 567.1 and 583.1 which correspond to [M+H]+,
[M+Li]+, [M+Na]+ and [M+K]+, respectively. The 1H NMR spectrum
of 3 shows that the complex formed contains one anionic diaza-
phospholidin-2-yl-benzenethiolate ligand and one nbd ligand as
expected. As observed for the free ligand, the four CH2N protons
appear as two complex multiplets. One is due to the protons on
one side of the five-membered PANACACAN ring facing the nbd
ligand and the other mulitplet due to the two protons on the other
2.4.2. Synthesis and structural behavior of [Pd(L1)2] (5)
The addition of approximately two equivalents of the ligand
lithium 2-(1,3-diphenyl-1,3,2-diazaphospholidin-2-yl)benzenethi-
olate (from HL1) to Na2PdCl4 in methanol at room temperature pro-
duced an orange precipitate almost immediately. The solution was
stirred at room temperature for 1 h, during which time no further
change occurred. The solid was isolated by filtration, washed with
methanol and ether and dried under vacuum. The product was
obtained as an orange solid in good yield (79%). The elemental
analysis of the sample was in good agreement with the values
expected for the proposed structure. The IR spectrum showed
peaks at 3058, 2868 and 1597 cmꢀ1 assigned to
CAH(aliphatic) and C@C, respectively. Finally, as seen for com-
mCAH(aromatic),
m
m
plexes 3 and 4, the positive electrospray mass spectrum showed
a series of peaks with the most intense peaks at m/z = 805.1,
Scheme 1. Reagents/conditions: (a) [Rh(nbd)2]BF4, CH2Cl2, rt (b) Na2PdCl4, MeOH,
rt (c) Ni(acac)2ꢃ4H2O, MeOH, rt.
Fig. 3. ORTEP representation (50% probability ellipsoids) of the X-ray crystal
structure of [Rh(L1)(nbd)] 3 with hydrogen atoms omitted for clarity.

1854
A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
Table 3
Selected bond distances (Å) and angles (°) for 3.
Rh(1)AS(1)
Rh(1)AP(1)
P(1)AN(1)
N(1)AC(7)
2.3071(7)
2.2066(6)
1.705(2)
1.462(3)
S(1)AC(1)
P(1)AC(6)
P(1)AN(2)
N(2)AC(8)
1.770(3)
1.808(3)
1.696(2)
1.467(3)
S(1)ARh(1)AP(2)
Rh(1)AS(1)AC(1)
Rh(1)AP(1)AC(6)
87.49(2)
105.50(9)
109.41(8)
Rh(1)AP(1)AN(1)
Rh(1)AP(1)AN(2)
N(1)AP(1)AN(2)
118.40(8)
120.79(8)
91.88(10)
811.1 and 827.1 which correspond to [M+H]+, [M+Li]+ and [M+Na]+.
The 31P NMR spectrum of 5 in CD2Cl2 showed two distinct phos-
phorus environments. The two peaks were both singlets and were
observed at 116.7 and 104.8 ppm in a 1:3 ratio (from the inte-
grated intensity). These two peaks have been tentatively assigned
to the cis and trans isomers of the product. Due to the steric
requirements of the ligand, it is expected that the major product
is the trans isomer. The two isomers would be expected to have
significantly different 31P chemical shifts as the cis isomer has
the two phosphorus atoms bound trans to an anionic sulfur atom,
and the trans isomer has the two phosphorus atoms bound trans to
each other. The alternative possibility, of an unbound phosphorus
is unlikely as the chemical shift in the 31P NMR spectrum would
be closer to the free ligand (ca. 90 ppm) not the observed signal
at 116.7 ppm.
Fig. 4. ORTEP view (50% probability ellipsoids) of the X-ray crystal structure of
[Pd(L1)2] 5 with hydrogen atoms and solvent omitted for clarity.
Table 4
Selected bond distances (Å) and angles (°) for [Pd(L1)2] 5.
Pd(1)AS(1)
Pd(1)AP(1)
P(1)AN(1)
N(1)AC(7)
C(7)AC(8)
2.3072(8)
2.2852(7)
1.695(3)
1.474(4)
1.512(4)
S(1)AC(1)
P(1)AC(6)
P(1)AN(2)
N(2)AC(8)
C(1)AC(6)
1.764(3)
1.802(3)
1.688(3)
1.477(4)
1.396(4)
The 1H NMR of the solid was, as expected, relatively complex,
with the aromatic region appearing as a large multiplet. The dis-
tinctive resonances corresponding to the CH2N protons appeared
as broad multiplets at 4.02 and 3.92 ppm, with the ratio of the inte-
grated intensity of these peaks approximately 1:7 relative to the
aromatic region as anticipated. The complex is not particularly sol-
uble, thus obtaining a good quality 13C spectrum was difficult. The
problem was compounded by both the fact that three of the ex-
pected 11 peaks are due to quaternary carbons, and also that any
carbon coupled to phosphorus is expected to appear as a virtual
multiplet due to the presence of two phosphorus atoms coordi-
nated to the palladium center. For these reasons it was not possible
to resolve the quaternary carbon peaks from the baseline. Seven
peaks were identified and assigned to the CH carbons of the aro-
matic rings, and a further peak at 46.2 ppm to the CH2N carbon
atoms. The 13C spectrum only appears to show the presence of
one species, although its possible that the second product has a
coincidental 13C spectrum, or that the peaks are so weak that they
cannot be distinguished from the baseline. Recrystallization of 5 by
layering a CH2Cl2 solution with pentane produced orange-yellow
plates suitable for a X-ray structure analysis (Fig. 4 with selected
bond lengths/angles are presented in Table 4).
S(1)APd(1)AP(2)
Pd(1)AS(1)AC(1)
Pd(1)AP(1)AC(6)
Pd(1)AP(1)AN(1)
87.84(3)
S(1)AC(1)AC(6)
C(1)AC(6)AP(1)
N(1)AP(1)AN(2)
Pd(1)AP(1)AN(2)
123.2(2)
117.0(2)
92.52(12)
118.09(9)
104.73(10)
106.94(10)
121.78(9)
Interestingly, measurements of the unit-cell parameters of the
crystals as a function of temperature showed a marked discontinu-
ity indicative of a phase change. This appeared to be reversible, but
exhibited a considerable degree of hysteresis. The two phases are
structurally similar, but the high-temperature phase contained dis-
order of the solvent of crystallization and of the phenyl ring,
C(15)AC(20).
2.4.3. Synthesis and structural behavior of cis- and trans-[Ni2{SC6H4-
P(NPh)2C2H4}2(SPh)2] (6)
In contrast to the reactions discussed above, the addition of half
an equivalent of [Ni(acac)2]ꢃ4H2O to a solution of the ligand
lithium 2-(1,3-diphenyl-1,3,2-diazaphospholidin-2-yl)benzenethi-
olate (Li[L1]) in methanol at room temperature did not immedi-
ately produce a pure compound. Although the ES(+) MS spectrum
of the product showed exclusively the ion at m/z = 757.1 corre-
sponding to [Ni(L1)2+H+], the NMR solution spectra were complex
and could not be assigned. It appeared that the initial solid formed
is a mixture containing at least some neutral bis(ligand) Ni(II) com-
plex. Recrystallization of the crude solid above by layering a CH2Cl2
solution with pentane produced a dark brown polycrystalline
aggregate. This was cut to give a fragment which was suitable for
X-ray structure analysis. The X-ray crystal structure found that
the structure was not in fact monometallic but incorporated two
NiL1 units bridged by two thiophenolates. An assembly of this
complex with both ligands on the same side (designated cis) or
on opposing sides (designated trans) was noted from the crystal
structure and explained the complex nature of the NMR spectra.
The asymmetric unit of the crystal contains a molecule of the trans
isomer (Fig. 5) of the dimeric complex located on a crystallographic
center of inversion, together with a molecule of the cis isomer
(Fig. 6) located on a site with no crystallographic symmetry, and
As expected for a d8 transition metal complex, complex 5 adopts
a square planar geometry and the steric constraints of the ligand
do not prevent the coordination of two PS ligands in a trans
configuration. In fact, the palladium ion lies on a crystallographic
center of inversion, which implies that the coordination geometry
of the metal is planar. Furthermore, the two five-membered
PdAPACACAS chelate rings are essentially planar with the sum
of the internal angles at 539.71° (cf. 540° for a planar pentagon).
The X-ray crystal structure also shows PAN bond lengths indicative
of single bonds at 1.695(3) and 1.688(3) Å for P(1)AN(1) and
P(1)AN(2) respectively, in close agreement to the values obtained
for Li[L2]ꢃ0.5LiClꢃ1.5TMEDA. The Pd(1)AP(1) bond length of
2.2852(7) Å is similar to the published values for the known com-
pounds [Pd{1-(diphenylphosphino)butane-2-thiolato}2] at 2.297 Å
(average) and [Pd{1-(diphenylphosphino-3-benzyloxy)-propane-
2-thiolato}2] at 2.281 Å (average) [5,8]. Despite the apparent obser-
vation of two isomers in solution by 31P NMR, the crystals isolated
were only of the trans form.

A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
1855
Table 5
Selected bond distances (Å) and angles (°) for 6.
trans
cis
Ni(1)AS(1)
Ni(1)AP(1)
Ni(1)AS(3)
Ni(1)AS(4)
Ni(2)AS(2)
Ni(2)AP(2)
Ni(2)AS(3)
Ni(2)AS(4)
Ni(1)ꢃ ꢃ ꢃNi(2)
2.1660(9)
2.1414(8)
2.2042(9)
2.2520(8)
2.1659(9)
2.1572(9)
2.2037(8)
2.2540(9)
3.1284(11)
Ni(3)AS(5)
Ni(3)AP(3)
Ni(3)AS(6)
Ni(3)AS(16)
Ni(13)AS(5)a
Ni(13)AP(3)a
Ni(13)AS(16)
Ni(13)AS(6)
Ni(3)ꢃ ꢃ ꢃNi(13)
2.1004(12)
2.0864(12)
2.1979(17)
2.2369(16)
2.2391(12)
2.2550(12)
2.2026(17)
2.2374(17)
3.1337(5)
S(1)ANi(1)AP(1)
S(1)ANi(1)AS(3)
P(1)ANi(1)AS(3)
S(1)ANi(1)AS(4)
P(1)ANi(1)AS(4)
S(3)ANi(1)AS(4)
S(2)ANi(2)AP(2)
S(2)ANi(2)AS(3)
P(2)ANi(2)AS(3)
S(2)ANi(2)AS(4)
P(2)ANi(2)AS(4)
S(3)ANi(2)AS(4)
Ni(1)AS(3)ANi(2)
Ni(1)AS(6)ANi(2)
^Between NiS2 planes
^Between Ni2S planes
89.88(3)
169.82(3)
100.03(3)
87.17(3)
175.11(3)
82.78(3)
90.02(4)
164.52(4)
101.51(3)
86.38(3)
174.68(4)
82.75(3)
90.62(3)
88.13(3)
48.0
S(5)ANi(3)AP(3)
S(5)ANi(3)AS(6)
P(3)ANi(3)AS(6)
93.69(5)
168.00(6)
97.56(6)
89.42(5)
174.53(7)
79.04(6)
85.62(4)
169.79(7)
100.18(6)
93.88(5)
170.00(7)
78.93(6)
89.17(6)
89.60(6)
40.8
S(5)ANi(3)AS(16)
P(3)ANi(3)AS(16)
S(6)ANi(3)AS(16)
S(5)aANi(13)AP(3)a
S(5)aANi(13)AS(16)
P(3)aANi(13)AS(16)
S(5)aANi(13)AS(6)
P(3)aANi(13)AS(6)
S(6)ANi(13)AS(16)
Ni(3)AS(6)ANi(13)
Ni(13)AS(16)ANi(3)
^Between NiS2 planes
^Between Ni2S planes
Fig. 5. ORTEP view (50% probability ellipsoids) of the X-ray crystal structure of
‘trans’-[Ni2{SC6H4P(NPh)2C2H4}2(SPh)2] 6 with hydrogen atoms and solvent omitted
for clarity.
52.4
43.2
a
Related to asymmetric unit by inversion, symmetry operator ꢀx, ꢀy, 1 ꢀ z.
The large thermal parameters of some of the N-phenyl carbon
atoms of both isomers suggest that there may be unresolved disor-
der of these groups. Attempts to model this did not lead to any
improvement in the agreement with the X-ray data and were
abandoned. An attempt was also made to refine the structure in
the space group P1 but this failed to reach convergence and the dis-
order was still clearly apparent, suggesting the original assignment
of symmetry to be correct. The cis isomer and solvent do not exhi-
bit any resolvable disorder. Geometric restraints were applied to
the disordered phenyl groups: the CAC bond lengths were re-
strained to 1.39(2) Å and the CACAC angles to 120(2)°. Similarity
restraints were applied to the thermal parameters of directly-
bonded pairs of disordered carbon atoms. In both metal sites, the
nickel, phosphorus and bridging sulfur atoms are all approximately
coplanar in a square planar coordination geometry. For the Ni(1)
site of the cis complex the S atom of the PS-ligand approximately
lies on the same plane. However, for the Ni(2) site, this atom lies
Fig. 6. ORTEP view (50% probability ellipsoids) of the X-ray crystal structure of ‘cis’-
[Ni2{SC6H4P(NPh)2C2H4}2(SPh)2] 6 with hydrogen atoms and solvent omitted for
clarity.
0.48 Å away from the NiP(Sbridge)2 plane. The geometry of the
1,3,2-diazaphospholidine ligand in these complexes is very similar
to that seen in the X-ray crystal structures of 3 and 5. The average
NiASdiazaphospholidine bond length of 2.168 Å is similar to the
literature values for [Ni(Ph2PCH2CH2S)2] [34] (2.174(1) Å) and
[Ni(Me2PCH2CH2S)2] [3,35] (2.177(1) Å). The average NiAP bond
length is also in good agreement with these known compounds
at 2.160 Å (mean; cf. 2.186(1) Å [34] ([Ni(Ph2PCH2CH2S)2]) and
2.166(1) Å [3] ([Ni(Me2PCH2CH2S)2])).
a
molecule of CH2Cl2 (see Table
5 for selected geometric
parameters).
The NiS2Ni units of both the cis and trans isomers are nonplanar
with two possible geometries for the Ni(SPh)2Ni unit. The bridging
S atoms lie further still from this plane and both S-phenyl groups
occupy ‘equatorial’ positions in both of the two possible Ni(SPh)2Ni
positions for the trans isomer. In contrast, in the cis isomer one of
the S-phenyl groups occupies an axial position. The presence of the
bridging thiophenolate groups indicates that partial decomposition
of the ligands through PAC bond cleavage has occurred. This deg-
radation of the ligand may be due to the presence of water of crys-
tallization in the [Ni(acac)2]ꢃ4H2O starting material, although
reactions of PAN ligands catalyzed by nickel have been reported
[33]. For example, the reaction of Ph2PN(Li)Ph with [NiCl2(PPh3)2]
produced the dimer [{Ni(N,N-PhNPPh2NPh)(Ph2P)]}2], which was
characterized by X-ray crystallography [33]. We conclude that in
this instance the PAN bonds are cleaved during recrystallization,
followed by hydrolytic loss of P to give thiophenol, but the details
of the mechanism are unknown.
3. Conclusions
Two sterically demanding PS-ligands have been prepared and
reacted with several transition metal precursor complexes. The
resultant complexes were characterized in the solid and solution
states. It appears that increasing bulk at phosphorus prevented for-
mation of octahedral M(PS)3 type complexes, but square planar
complexes of the type M(PS)2 and LM(PS) were isolated and char-
acterized. Attempts to prepare nickel(II) complexes led to PAC
bond cleavage and formation of thiophenolate bridged complexes.

1856
A.J. Robbie et al. / Polyhedron 30 (2011) 1849–1856
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Appendix A. Supplementary data
CCDC 767739, 767740, 767741 and 767742 contain the supple-
mentary crystallographic data for Li[L2], 3, 5 and 6. This data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
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