Synthesis, structures and ligating properties of 2,6-bis(phosphino)thiophenol derivatives

Article abstract of DOI:10.1016/j.ica.2007.08.029

New t-butyl-aryl thioethers where the aryl group is 2,6-bis(phosphino)phenyl have been synthesized. The syntheses were completed via sequential ortho-lithiations of t-butylphenylsulfide, followed by chlorophosphine (ClPR₂) quenches; symmetric (

Full text of DOI:10.1016/j.ica.2007.08.029

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Inorganica Chimica Acta 361 (2008) 1349–1356
www.elsevier.com/locate/ica
Synthesis, structures and ligating properties
of 2,6-bis(phosphino)thiophenol derivatives
1
Aldona Beganskiene , Louis R. Pignotti, Vitalija Baltramiejunaite,
*
Rudy L. Luck, Eugenijus Urnezius
Department of Chemistry, Michigan Technological University, Houghton, MI 49931, USA
Received 4 August 2007; accepted 24 August 2007
Available online 1 September 2007
Abstract
New t-butyl-aryl thioethers where the aryl group is 2,6-bis(phosphino)phenyl have been synthesized. The syntheses were completed
via sequential ortho-lithiations of t-butylphenylsulfide, followed by chlorophosphine (ClPR2) quenches; symmetric (2,6-bis(diph-
enylphosphino)phenyl, (4a)) and unsymmetric (2-diisopropylphosphino-6-diphenylphosphino)phenyl, (4b) aryl groups were obtained.
Treatment of 4a with Li or Na naphthalenide yielded 2,6-bis(diphenylphosphino)thiophenol 5. Reactions of 4a or 5 with NiCl2 Æ 6H2O
yielded nickel bis(phosphinothiophenolate) 6. Compounds 4a,b, 5 and 6 were characterized by 1H and 31P NMR, and by mass-spectrom-
etry. In addition, 4a, 5 and 6 were characterized by single crystal X-ray diffraction methods.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: P,S-Chelating ligands; Nickel o-phosphinotiophenolate; X-ray crystal structures
1. Introduction
at one or both of the metal centers of the binuclear core.
For example, dicopper and diiron complexes supported
by the ligands centered on the structural motif 1 have been
used for modeling of dioxygen activation [6–8]. Structur-
ally analogous bimetallic complexes where ‘‘soft’’ phospho-
rus/sulfur ligands (e.g., 2, Fig. 1) are incorporated into the
ligand design are less common [5]. While less directly rele-
vant to modeling of biological functions, such ligating envi-
ronments may provide access to bimetallic complexes
where the lower oxidation states of the metal centers are
stabilized. Thus, if the same overall geometry of the bime-
tallic complex is retained, a different preference for small
molecule binding and activation may be anticipated. Bridg-
ing thiophenolates flanked by nitrogen donors (2, E = N,
Fig. 1) have been successfully incorporated into the con-
struction of various binucleating macrocyclic ligands
[9,10]. To the best of our knowledge, only one binucleating
ligand fitting the general structural motif 2 where the flank-
ing ligating groups are phosphines, 2,6-bis(diphenyl-phos-
phinomethyl)benzenethiolate, has been reported [11].
(Structurally similar oxygen analogues, phenolates with
Bimetallic transition metal complexes supported by
binucleating l-phenolate ligands (1, Fig. 1) have been
extensively used as synthetic models for mimicking of bio-
logical processes occurring at the bimetallic sites of certain
proteins [1–4]. The binucleating ability of such phenolates
is rendered by the presence of two [O, N] chelating pockets,
formed by flanking the Ph–Oꢀ unit by amine or imine func-
tionalities connected through one- or two-bond ‘‘arms’’ to
the 2- and 6-positions of the phenol ring (1, Fig. 1) [5]. Such
a motif (1) often serves as a platform for more elaborate
polydentate bicompartmental ligands, where the flanking
nitrogens also serve as branching points for additional che-
lating ‘‘arms’’. One attractive feature of such bimetallic
complexes is their ability to bind small molecules or ions
*
Corresponding author. Tel.: +1 906 487 2055; fax: +1 906 487 2061.
E-mail address: urnezius@mtu.edu (E. Urnezius).
Permanent address: Department of General and Inorganic Chemistry,
1
Vilnius University, Naugarduko 24, 03255 Vilnius, Lithuania.
0020-1693/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.08.029

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A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
Fig. 1. Binucleating motifs built around bridging phenolate/thiophenolate ligands.
flanking phosphine arms, have been used as mononucleat-
ing ‘‘pincer’’ ligands [12–15]). Given into account the ubiq-
uitous use of phosphine ligands in coordination chemistry,
the limited use of phosphine-flanked phenolates and thio-
phenolates as binucleating motifs seems rather surprising.
Recently we have reported on the syntheses of symmetric
and unsymetric 2,6-bis(phosphino)phenols (3, Fig. 1), and
on the usage of 2,6-bis(phosphino)phenol core for the con-
struction of a bicompartmental ligand with soft ligating
compartments flanking the bridging phenolate [16,17].
We also succeeded in developing the synthetic procedures
for assembling analogous structural motifs starting with a
thiophenol core, and herein we report on the synthesis of
the 2,6-bis(phosphino)thiophenol derivatives 4a,b and 5,
and on a nickel bis(phoshinothiophenolate) complex 6
(Fig. 1). Structural characterizations of 4a, 5 and 6 are also
reported.
bon disk (3 mm), Ag/AgNO3, and Pt wire and were used as
working, reference, and counter electrodes, respectively.
Measurements were performed in CH2Cl2 containing
0.1 M NBu4PF6 as supporting electrolyte, at 0.1 V/s scan
rate.
2.2. Syntheses
2.2.1. (2,6-Bis(diphenylphosphino)phenyl)(t-butyl)sulfide
(4a)
n-Butyl lithium (1.6 M in hexanes, 3.1 mL, 5.0 mmol) was
slowly added to an ice-cold solution of 2-(t-butylthio)phen-
yldiphenylphosphine (1.75 g, 5.0 mmol) in hexanes (70 mL).
N,N,N0,N0-Tetramethylenediamine (TMEDA) (0.94 mL,
6.8 mmol) was then slowly added (over 15 min). The
reaction mixture was left to stir overnight and allowed to
attain room temperature, leading to the formation of a
pale-yellow suspension. The reaction vessel was ice-cooled,
and a solution of chlorodiphenylphosphine (0.89 mL,
5.0 mmol) in hexanes (5 mL) was slowly added to the stir-
red suspension. The reaction mixture was stirred for 3 h
and hydrolyzed with degassed 5% aqueous NaOH. The
organic phase was separated, the aqueous phase was
extracted with ether (20 mL), the extract was added to
the original organic phase, and the combined organic
phases were dried over MgSO4. Slightly yellow crystals pre-
cipitated on standing at ꢀ28 °C for 3 days. Yield: 1.25 g
(49%). Melting point: 158–160 °C. 1H NMR (C6D6) d:
7.05–6.65 (m, 23H) 1.41 (s, 9H). 31P NMR (C6D6) d:
ꢀ6.4 (s). HRMS (FAB): Calc. for C34H33P2S: 535.1778
(MH+); found: 535.1776.
2. Experimental
2.1. General procedures
Manipulations requiring inert atmospheres were carried
out by using Schlenk techniques or in a dry box under a N2
atmosphere. Solvents were purified before use by distilla-
tion from Na–benzophenone ketyl (ether, THF, hexanes,
benzene) or Na (pyridine) under a N2 atmosphere. Com-
mercially available chlorophosphines ClPR2 were purified
prior to use: ClPPh2 was vacuum distilled, and ClPiPr2
was frozen, degassed and thawed under vacuum (repeated
3 times). t-Butylphenylsulfide and 2-(t-butylthio)phenyldi-
phenylphosphine were obtained via published synthetic
methods [18,19]. Other reagents were obtained from com-
2.2.2. (2-Diisopropylphosphino-6-
diphenylphosphino)phenyl(t-butyl)sulfide (4b)
1
mercial suppliers. H and 31P NMR spectra were recorded
on a Varian INOVA spectrometer operating at 400 and
161 MHz, respectively. Spectra are referenced to tetrame-
thysilane (1H) and 85% H3PO4 (31P) (external reference).
Low resolution mass spectrometric measurements were
performed on a Shimadzu QP5050A instrument; high reso-
lution measurements were performed at the Mass Spectro-
metric Facility of Michigan State University (East Lansing,
MI 48824-1319).
To a solution of 2-(t-butylthio)phenyldiphenylphos-
phine (4.82 g, 13.75 mmol) in hexane (130 mL), n-butyl
lithium (8.6 mL, 1.6 M in hexanes, 13.75 mmol) and TME-
DA (2.1 mL, 13.75 mmol) were added successively. The
reaction mixture was stirred at room temperature over-
night, resulting in the formation of a slightly yellow precip-
itate. The reaction vessel was then cooled to 0 °C,
chlorodiisopropylphosphine (2.43 mL, 15.13 mmol) was
added, and the reaction mixture was stirred overnight at
ambient temperature. After filtration and removal of all
volatiles under vacuo, the resulting solid was dissolved in
Cyclic voltammetry of 6 was performed using CHI420
electrochemical analyzer. Standard 3-electrode cell fitted
to operate under air-tight conditions was used. Glassy car-

A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
1351
pentane (100 mL) and placed at ꢀ20 °C. White crystalline
solid 4b deposited slowly (weeks). Yield: 1.62 g (25%), after
accounting for the presence of ꢁ5% of the starting mate-
rial, 2-(t-butylthio)phenyldiphenylphosphine. 1H NMR
(C6D6): d 7.34 (m, 4H); 7.07 (m, 6H); 7.04 (m, 1H); 6.97
(m, 1H); 6.87 (m, 1H); 1.88 (s (br), 2H); 1.64 (s, 9H);
1.12–0.94 (m (br), 12H). 31P NMR (THF): d 3.4 (d),
cases. These programs were utilized using the WinGX
interface [23]. The models were then refined using SHEL-
XL97 [24] first with isotropic and then anisotropic thermal
parameters to convergence. The positions and isotropic
thermal parameters of the different H-atoms were con-
strained according to the specifics arranged in the SHEL-
XL97 program. Complex 4a contained unequal disorder in
the position of the tertiary butyl ligand, complex 5 was
ordered and 6 contained disorder in the THF molecules
of solvation. The disorder was accounted for with the
SHELXL97 program using procedures detailed previously
[25].
4
ꢀ7.2 (d), JPP = 12 Hz. HRMS (FAB): Calc. for
C28H37P2S: 467.2091 (MH+); found: 467.2090.
2.2.3. 2,6-Bis(diphenylphosphino)benzenethiol (5)
To a cold (0 °C) lithium naphthalenide solution, gener-
ated from 0.037 g (5.3 mmol) of lithium and 0.574 g
(4.5 mmol) of naphthalene in 30 mL of THF, was added
a solution of 4a (1.131 g, 2.11 mmol) in 20 mL of THF.
The dark brown reaction mixture was stirred for 3 hours
at 0 °C, and anhydrous HCl (2.5 mL, 2 M solution in ether)
was added. A white precipitate (LiCl) was separated from
the pale yellow solution via filtration. All volatiles were
removed under vacuo (including naphthalene by sublima-
tion), leaving behind 5 as a waxy pale yellow solid, which
crystallized slowly upon standing. It was further purified
by washing with heptane (20 mL). Yield: 0.973 g (96%).
3. Results and discussion
3.1. Syntheses and spectroscopic characterizations
Various derivatives of o-(phosphino)thiophenols have
been extensively used in the coordination chemistry of
transition metals [26]. Simple o-phosphinothiophenols con-
taining [P,S] chelating pockets typically function as mono-
nucleating ligands towards metal centers. Since thiolate
ligands are well known to bridge two or more metal centers
[27], a suitably designed thiophenolate ligand where the
sulfur center is an integral part for two adjacent chelating
pockets may function as an attractive binucleating motif.
Thus, bimetallic complexes based on thiophenolates where
the sulfur is shared between two [N,S] chelating pockets are
well known [28]. The flanking donor atoms in such ligands
are separated from the parent thiophenol ring by @CH– or
–CH2– spacers, stemming from both positions ortho to sul-
fur. Analogous binucleating ligands where the flanking
donor groups are phosphorus atoms have received only
limited attention [11].
Thiophenolate ligands with two flanking donor groups
attached directly to the thiophenol ring have not been
reported yet. This is rather surprising as facile ortho-lithia-
tions of the thiophenol ring allow for the introduction of
donor groups at both ortho positions. Thus, sequential
ortho-lithiations of thiophenol, followed by electrophile
quench [29,30] (Eq. (1)) have been used for the syntheses
of o-phosphinothiophenols and related polydentate
ligands. In such
1
Melting point: 153–155 °C. H NMR (C6D6): d 7.31 (m,
3
8H), 7.01 (m, 12 H), 6.97 (dm, 2H, JHH = 8 Hz); 6.65 (t,
3
1H, JHH = 8 Hz), 5.34 (s (br), 1H). 31P NMR (C6D6) d:
ꢀ11.6 (s). HRMS (FAB): Calc. for C30H25P2S: 479.1152
(MH+); found: 479.1154. Crystals suitable for X-ray anal-
ysis were obtained from a solution of 5 in benzene/Et2O
(ꢁ1:1) upon prolonged standing (weeks) at ꢀ28 °C.
2.2.4. Nickel bis(2,6-bis(diphenylphosphino)-
benzenethiolate) (6)
A solution of 4a (0.5 g, 1.0 mmol) in THF (15 mL) was
added to NiCl2 Æ 6H2O (0.12 g, 0.5 mmol), and the resulting
suspension was refluxed overnight. A bright green precipi-
tate (6) formed which was isolated by filtration and dried
1
under vacuo. Yield: 0.23 g (47%). H NMR (C5D5N): d
7.67–6.85 (m). 31P NMR (C5D5N): d 55.3 (s), ꢀ13.0 (s).
The elemental analysis data were consistently low on car-
bon. HRMS (FAB): Calc. for C60H47NiP4S2 (MH+):
1013.1423; found: 1013.1418. Crystals suitable for X-ray
analysis were obtained by slow evaporation of the solution
of 6 in pyridine/THF (ꢁ10/1).
ð1Þ
2.3. X-ray crystallography
ligands, the thiophenolate typically is flanked by a phos-
phine and a silyl (–SiR3) groups, resulting in steric proper-
ties of the ligand which facilitate the formation of
mononuclear complexes. Presently there are no reports of
the synthesis of 2,6-bis(phosphino)thiophenols, although
such compounds should be accessible via appropriate mod-
ifications of the sequence shown as Eq. (1).
In all cases, the handling of the crystals and data collec-
tion was as described previously [20]. Data were first
reduced and corrected for absorption using psi-scans [21]
and then solved using the program SIR-04 [22], which affor-
ded nearly complete solutions for the non-H atoms in all

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A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
Prolonged exposure of 2-(t-butylthio)phenyldiphenyl-
NMR: d ꢀ39.0 (d, JPH = 215 Hz); ꢀ44.9 (d, JPH
227 Hz), resulting in a
=
phosphine to BuLi in the presence of TMEDA (Eq. (2))
resulted in ortho-lithiation of the thiophenyl ring, in accor-
dance with previously reported o-lithiations of some alkyl-
aryl thioethers [19,31]. Quenching such reaction
ð3Þ
decreased yield of 5 (about 80%). The presence of such
byproducts is consistent with previously reported P–C
bond cleavage reactions observed upon subjection of se-
lected phosphines to sodium naphthalenide [33]. Thiophe-
nol 5 is a white, foamy substance, which was isolated in
crystalline form. Oxidations at both phosphorus and sulfur
can be expected for 5, as related compounds containing o-
(phosphino)thiophenol fragments have been reported to
form oxidation products containing P@O and S–S frag-
ments [34,35]. However, thiophenol 5 appears to be rela-
tively stable to aerial oxidation, as no changes were
observed in its 31P NMR spectra when a benzene solution
of 5 was exposed to air and monitored for 5 days. Interest-
ingly, structural analogs of 5, 2,6-bis(phosphino)phenols
are extremely air sensitive [17].
Reactions of the new ligands with Ni(II) sources allowed
for the initial assessment of their coordinating properties.
Ligands containing mixed-donor [P,S] chelating pockets
are well known to form mononuclear complexes of the gen-
eral formula M[P,S]2, particularly when reacted with
Group 8 metal ions [26]. For example, nickel bis(phosphi-
nothiophenolate) complexes are readily formed in reactions
of o-(diphenylphosphino)thioanisole or related chelating
phosphine–thioether ligands with nickel(II) halides, via fac-
ile dealkylations at sulfur [36,37]. Since compounds 4a,b
and 5 have two [P,S] chelating compartments, formation of
ð2Þ
mixtures with chlorophosphines ClPR2 produced t-butyl-
aryl thioethers where the aryl group is symmetrically
(R = Ph, 4a) or unsymmetrically (R = iPr, 4b) substituted
2,6-bis(phosphino)thiophenol. Compound 4a was isolated
by simple crystallization from the reaction mixture.
Compound 4b was not obtained in pure form, as small
quantities of the starting material, 2-(t-butylthio)phenyldi-
phenyl- phosphine (ca. 5%) were always present even after
repeated crystallizations. Both 4a and 4b are white crystal-
line substances, which are quite stable in air (no oxidation
was observed by 31P NMR when benzene solutions of 4a,b
were exposed to air for 1 week). Spectroscopic (NMR)
characterizations of 4a (31P NMR, d ꢀ6.4, (s); H NMR,
d 1.41 (s, 9H)) correspond to Cs symmetry of the molecule,
and analogous spectral features were observed for isostruc-
tural, symmetrically substituted 2,6-bis(phosphino)phenols
[17]. Phosphorus centers in unsymmetrically substituted
2,6-bis(phosphino)thiophenol 4b are weakly coupled
(4JPP = 12 Hz), whereas such coupling was not resolved
in analogous O-protected phenol derivatives [17]. Broad
signals for the iPr groups in the room temperature H
NMR spectrum of 4b (d 1.88, s (br, 2H); 1.12–0.94, (m,
(br, 12H))) suggest that rotation around the P–C bonds
ð4Þ
in the PiPr2 substituent is restricted. Similar 1H NMR spec-
tral patterns were observed in related compounds when the
PiPr2 group is positioned ortho to a relatively bulky substi-
tuent [17,32].
Reactions of 4a with alkali metal (Li or Na) naphthale-
nides followed by acidification of the reaction media pro-
duced thiophenol 5 (Eq. (3)). A better selectivity for S–
C(CH3)3 bond cleavage and higher yields of 5 (>95%) were
observed when lithium was used. When sodium was used,
the reaction mixtures were always contaminated with
minor quantities of products containing P–H bonds 31P
binuclear complexes containing bridging thiolate moieties
may be expected. However, only the mononuclear
bis(phosphinothiophenolate) complex 6 was obtained in
reactions of 4a with NiCl2 Æ 6H2O (Eq. (4)). No formation
of a bimetallic complex was detected when the reaction de-
picted in Eq. (4) was repeated using different ratios of the
reagents (ligand/metal, 2:1, 1:1, and 1:2); 6 was always iso-
lated as a major product. Complex 6 was also obtained
when a THF solution of thiophenol 5 was subjected to
NaOEt and followed by NiCl2 Æ 6H2O (2:1 ratio). Deep
green 6 is soluble in THF, pyridine, and dichloromethane;

A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
1353
Fig. 2. Thermal ellipsoid (30%) plots of 4a and 5. One orientation of the disordered t-Bu group of 4a is shown; cocrystallyzed benzene molecule is omitted
in the plot for 5.
Fig. 3. Thermal ellipsoid (30%) plots of compound 6.
Table 1
Summary of crystallographic data for 4a, 5 and 6
Compound
4a
5 Æ C6H6
6 Æ 2 THF
Formula
Formula weight
C34H32P2S
534.6
C36H30P2S
556.6
C68H62NiO2P4S2
1157.88
ꢀ
ꢀ
Space group
P1
P21/n
10.187(1)
9.672(2)
31.27(1)
90
97.65(2)
90
3053.6(12)
4
1.211
0.234
293(2)
0.71073
P1
˚
a (A)
9.523(1)
9.806(2)
˚
b (A)
12.370(3)
12.940(3)
93.09(2)
100.54(2)
93.56(2)
1492.4(5)
2
1.19
11.817(3)
14.765(4)
81.45(2)
73.13(2)
67.73(2)
1513.7(6)
2
1.27
0.539
293(2)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
Z
qcalc (g/cm3)
l (MoKa mmꢀ1
T (K)
)
0.236
293(2)
0.71069
˚
k (A)
0.71073
h Range (°)
1.60–22.47
3887/2384
R1 = 0.047, wR2 = 0.097c
R1 = 0.120, wR2 = 0.117
0.295, ꢀ0.176
1.029
2.04–22.47
3957/2942
R1 = 0.038, wR2 = 0.093d
R1 = 0.068, wR2 = 0.105
0.258, ꢀ0.212
1.03
1.44–22.47
3851/2035
R1 = 0.058, wR2 = 0.096e
R1 = 0.183, wR2 = 0.122
0.299, ꢀ0.31
1.003
Measured/independent reflections
Final R indices [I > 2r(I)]a,b
R indices (all data)
Largest difference peak and hole
Goodness-of-fit on F2
P
P
a
b
c
R1 ¼ jjF oj ꢀ jF cjj= jF oj.
P
P
2
2 1=2
wR2 ¼ ½ ½wðF 2o ꢀ F c2Þ ꢂ= ½wðF 2oÞ ꢂꢂ
.
2
2
2
2
2
w ¼ 1=½ ðF oÞ þ ð0:0402PÞ þ 0:7299Pꢂ where P ¼ ðF o þ 2ðF cÞ Þ=3.
2
d
e
2
2
w ¼ 1=½ ðF oÞ þ ð0:0477PÞ þ 1:2231Pꢂ.
2
2
2
w ¼ 1=½ ðF oÞ þ ð0:0387PÞ þ 0:1973Pꢂ.
it decomposes in acetonitrile. The 31P NMR chemical shift
value for nickel-coordinated phosphorus centers in 6 (d
55.3, s) closely resembles those observed for other nickel
bis(2-diphenylphosphinothiophenolates) (d 56.1 [36], 52.6
[38]). The shift value for the uncoordinated phosphine in
6 (d ꢀ13.0) is close to that for the free ligand 5 (d ꢀ11.6).

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A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
In contrast, ligand 4b does not afford bis(phosphino-
3.1.1. Structural characterizations of 4a, 5, and 6
thiophenolate) complexes analogous to 6 upon exposure
to nickel(II) halides. Instead, such reactions produced a
poorly soluble, and as-yet uncharacterized, NMR-silent
orange powder.
Compounds 4a, 5 and 6 were characterized by single
crystal X-ray diffraction methods. Their molecular struc-
tures are depicted in Figs. 2 and 3, crystallographic data
are summarized in Table 1, and bond lengths and angles
are listed in Table 2.
Both metal-based and sulfur-based electrochemical oxi-
dations have been reported for Ni[P,S]2 complexes. Metal-
based (Ni(II)/Ni(III)) oxidation (0.67 V versus Ag/Ag+) is
reversible [36], while thiolate–thiyl conversion proceeds
irreversibly at lover potential (0.26 V) [39]. Investigation
of 6 by cyclic voltammetry displayed an irreversible oxida-
tion peak at around 0.38 V (versus Ag/AgNO3). We have
assigned it to oxidation at sulfur, based on comparisons
to similar thiolate–thiyl conversions reported for related
Ni[P,S]2 complex [39].
Single crystals of thioether 4a suitable for X-ray analysis
were obtained by crystallization directly from the reaction
mixture. ORTEP-3 drawing of 4a is shown in Fig. 2. The
molecule adopts a conformation where the PPh2 and tert-
butylthio substituents are rotated around the bonds con-
necting the heteroatoms to the central phenyl ring to
minimize the steric interactions among the tBu group and
the phenyl rings. Atom P6 is displaced from the plane of
the central phenyl ring (torsion angle S1–C1–C6–P6 is
7.33°) whereas atoms P2 and S1 are essentially in that plane.
Single crystals of thiophenol 5 were obtained by low temper-
ature (ꢀ28 °C) crystallization from a benzene/Et2O (ꢁ1:1)
solution. The compound crystallizes with one molecule of
benzene per thiophenol in the lattice. The bond distances
and angles in 4a and 5 (Table 2) are unremarkable.
Table 2
Selected bond lengths and angles for compounds 4a, 5 and 6
˚
Bond lengths (A) and angles (°) 4a
5
6
Thiophenolate 6 was crystallized from a pyridine/THF
(ꢁ9:1) solution. The complex crystallizes with two mole-
cules of THF in the lattice. The metal center is in a
square-planar geometry, with thiolate and phosphine
donors from the two opposing [P,S] ligands located in a
trans arrangement (Fig. 3). Analogous geometries have
been reported for other divalent nickel Ni[P,S]2 compounds
[36,38–40]. Nickel–sulfur and nickel–phosphorus distances
in 6 are within the range of analogous distances (2.15–
C1–S1
C2–P2
C6–P6
S1–C11
S1–Ni1
P2–Ni1
1.780(4)
1.775(3)
1.840(2)
1.845(3)
1.752(6)
1.801(6)
1.823(6)
1.853(4)
1.850(4)
1.880(4)
2.1628(17)
2.1633(17)
S1–C1–C2
S1–C1–C6
C1–S1–C11
C1–C2–P2
C1–C6–P6
S1–Ni1–P2
C1–S1–Ni1
C2–P2–Ni1
119.1(3)
120.1(3)
105.38(18)
118.7(3)
118.6(3)
120.02(19) 120.7(5)
118.9(2) 119.4(5)
˚
2.18 A) reported for other structurally characterized
120.04(19) 112.2(5)
119.75(19) 117.7(5)
87.57(6)
Ni[P,S]2 complexes [36,38,40]. Thiolate and PPh2 groups
(both nickel-coordinated and free) in 6 are displaced into
the opposite sides of the plane of the central phenyl ring
(torsion angles S1–C1–C2–P2 and S1–C1–C6–P6 are
106.1(2)
107.2(2)
Fig. 4. Packing of 6 in the crystalline lattice (grey spheres represent nickel, sulfur, and phosphorus).

A. Beganskiene et al. / Inorganica Chimica Acta 361 (2008) 1349–1356
1355
1EZ, UK; fax: (+44) 1223 336 033; or e-mail: deposit@
ccdc.cam.ac.uk.
Acknowledgements
Council for International Exchange of Scholars is
acknowledged for the Fulbright Visiting Scholar Grant
(A.B.). Acknowledgement is made to the Donors of the
American Chemical Society Petroleum Research fund, for
partial support of this research.
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