PPh(2-C6H4S)2 as a pincer ligand in nickel(II) and palladium(II) complexes - X-ray structure of [Ni{PPh(C6H4S)2}(PPh2Me)], [Pd2(μ-dppe){PPh (C6H4S)2}2] and [Ni{PPh(C6H4S)2}]2

Article abstract of DOI:10.1002/1099-0682(200203)2002:4<826::aid-ejic826>3.0.co;2-m

The phosphanylthiol PPh(2-C₆H₄SH)₂ reacts with the Ni^II and Pd^II complexes [MCl₂L₂] in the presence of NaOEt to give the mononuclear derivatives [M{PPh(C₆H₄S)₂}L] [M = Ni, L = PPh₃ (1), PPh₂Me (2); M = Pd, L = PPh₃ (3)]. The analogous reaction starting with complexes containing bidentate ligands [MX₂(L-L)] produces different results depending on the ligand used. The complexes [M{PPh(C₆H₄S)₂}(dppm)] [M = Ni (4), Pd (5)], with an unligated phosphorus atom in the diphosphane are obtained with bis(diphenylphosphanyl)methane (dppm), while the dinuclear complexes [M₂(μ-dppe){PPh(C₆H₄S)₂}] [M = Ni (6), Pd (7)] are isolated in the case of 1,2-bis(diphenylphosphanyl)-ethane (dppe). With 1,10-phenanthroline (phen), the complexes [M{PPh(C₆H₄S)₂}(phen)] [M = Ni (8), Pd (9)] are obtained, but when 2,2′-bipyridine is used the dinuclear compounds [M{PPh(C₆H₄S)₂}]₂ [M = Ni (10), Pd (11)] are isolated instead. Complexes 10 and 11, which can be obtained starting from NiCl₂ or [PdCl₂(NCPh)₂] respectively, afford complexes 1-7 when treated with the respective phosphanes in the appropriate stoichiometries. The structures of 2, 7 and 10 have been confirmed by X-ray analysis.

Full text of DOI:10.1002/1099-0682(200203)2002:4<826::aid-ejic826>3.0.co;2-m

FULL PAPER
PPh(2-C6H4S)2 as a Pincer Ligand in Nickel(II) and Palladium(II)
Complexes — X-ray Structure of [Ni{PPh(C6H4S)2}(PPh2Me)],
[Pd2(µ-dppe){PPh(C6H4S)2}2] and [Ni{PPh(C6H4S)2}]2
Elena Cerrada,[a] Larry R. Falvello,[a] Michael B. Hursthouse,[b] Mariano Laguna,*[a]
[a]
[a]
´
´
Asuncion Luquın, and Cristina Pozo-Gonzalo
Keywords: Nickel / Palladium / P ligands / S ligands
The phosphanylthiol PPh(2-C6H4SH)2 reacts with the NiII
(7)] are isolated in the case of 1,2-bis(diphenylphosphanyl)-
and PdII complexes [MCl2L2] in the presence of NaOEt to ethane (dppe). With 1,10-phenanthroline (phen), the com-
give the mononuclear derivatives [M{PPh(C6H4S)2}L] [M =
Ni, L = PPh3 (1), PPh2Me (2); M = Pd, L = PPh3 (3)]. The tained, but when 2,2Ј-bipyridine is used the dinuclear com-
analogous reaction starting with complexes containing bi- pounds [M{PPh(C6H4S)2}]2 [M = Ni (10), Pd (11)] are isolated
dentate ligands [MX2(L-L)] produces different results de- instead. Complexes 10 and 11, which can be obtained start-
pending on the ligand used. The complexes ing from NiCl2 or [PdCl2(NCPh)2] respectively, afford com-
[M{PPh(C6H4S)2}(dppm)] [M = Ni (4), Pd (5)], with an unlig- plexes 1−7 when treated with the respective phosphanes in
ated phosphorus atom in the diphosphane are obtained with the appropriate stoichiometries. The structures of 2, 7 and 10
plexes [M{PPh(C6H4S)2}(phen)] [M = Ni (8), Pd (9)] are ob-
bis(diphenylphosphanyl)methane (dppm), while the dinuc-
have been confirmed by X-ray analysis.
lear complexes [M2(µ-dppe){PPh(C6H4S)2}] [M = Ni (6), Pd
Introduction
have been the proligands PR2(CH2SH), PR2(CH2CH2SH)
and PR2(C6H4SH).[10Ϫ16]
Species with more than two donor atoms
—
Transition metal chemistry involving sulfur donor groups
is of current interest because of its relevance in biology, be-
cause of its many industrial applications, and because of its
importance in the area of novel complex synthesis.[1] Thus,
sulfur-ligated transition metal complexes form the inor-
ganic parts of the biologically active centres of some metal-
loproteins and enzymes. Consequently, some of these have
found applications in pharmacology,[2Ϫ4] and industrial
chemistry.[5Ϫ7] As for synthetic chemistry as such, transition
metal thiolate complexes have received special interest be-
cause of their ability to adopt different structures and nuc-
learities.[8]
It is fairly common that these thiolate complexes contain
phosphane moieties which, operating as ancillary ligands,
are able to enhance the properties of interest. For this
reason the chemistry of polydentate ligands with sulfur and
phosphorus donor atoms in their frameworks has attracted
increasing interest, augmented by the observation of un-
usual structures and reactivities in the resulting transition
metal complexes.[9] In this regard, the systems most studied
PR(CH2CH2SH)2, PR(C6H4SH)2, P(CH2CH2SH)3 and
P(C6H4SH)3 — have received much less attention,[17Ϫ20] al-
though they possess intrinsic interest in as much as they
stably occupy three or more coordination sites, thus permit-
ting more specific chemistry to be performed at the re-
maining sites. Such is the case for PPh(C6H4S)22Ϫ, which
possesses a three-donor set ‘‘PS2’’ and can be described as
a
pincer
ligand
similar
to
van
Koten’s[21]
[C6H3(CH2NMe2)2]Ϫ and [2,6-(Ph2PCH2)2C6H3)]Ϫ, Milste-
in’s[22] [C6H3(CH2PBu2)2]Ϫ and [C6H4(CH2PPr2)2] or to
Sellmann’s [bis(2-mercaptophenyl)sulfide2Ϫ].[23]
In this paper we describe some mono- and dinuclear
2Ϫ
complexes of NiII and PdII, with PPh(C6H4S)2 acting as
a pincer ligand in an S,SЈ,P coordination mode, as con-
firmed by the X-ray structures of [Ni{PPh-
(C6H4S)2}(PPh2Me)], [Pd2(µ-dppe){PPh(C6H4S)2}2] and
[Ni{PPh(C6H4S)2}]2.
Results and Discussion
[a]
´
´
Departamento de Quımica Inorganica, Instituto de Ciencia de
The reaction of a solution of PPh(C6H4SH)2 and sodium
ethoxide with the nickel(II) and palladium(II) species
MCl2L2 (L ϭ monodentate phosphane; step i, Scheme 1),
yields the mononuclear derivatives [M{PPh(C6H4S)2}(L)]
´
Materiales de Aragon, Universidad de Zaragoza-C.S.I.C,
50009 Zaragoza, Spain
E-mail: mlaguna@posta.unizar.es
Department of Chemistry, University of Southampton,
Highfield, Southampton, SO17 1BJ, UK
[b]
826
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0404Ϫ0826 $ 17.50ϩ.50/0 Eur. J. Inorg. Chem. 2002, 826Ϫ833

PPh(2-C6H4S)2 as a Pincer Ligand in Nickel(II) and Palladium(II) Complexes
FULL PAPER
Scheme 1. Synthesis of complexes 1؊11
[M ϭ Ni, L ϭ PPh3 (1), PPh2Me (2); M ϭ Pd, L ϭ PPh3 the diphosphane used. Thus, in the case of bis(diphenylpho-
(3)]. This process can be described as the result of depro- sphanyl)methane (dppm) the mononuclear complexes 4 and
tonation of the starting phosphanylthiol ligand at room 5 are isolated, whereas the dinuclear species 6 and 7 are
temperature, followed by coordination to the metal centre formed when 1,2-bis(diphenylphosphanyl)ethane (dppe) is
with the concomitant dissociation of one monodentate pho- used instead.
sphane. To date the most common synthetic routes to com-
The complexes [M{PPh(C6H4S)2}dppm] [M ϭ Ni (4), Pd
plexes with these ligands have involved electrochemical pro- (5)] show IR spectra similar to those of compounds 1؊3,
cedures[24] or reflux conditions in the presence of NEt3 as with the SϪH vibration absent and the phosphane bands
1
a base. The preparation of 1؊3 occurs under milder condi- present. The H NMR spectra show multiplets in the aro-
tions than those reported for related complexes.
matic region, and broad signals centred at δ ϭ 3.17 (4) and
The IR spectra of complexes 1؊3 do not show the 3.33 (5), even at low temperature, due to the -CH2- group
ν(SϪH) band, which appears at 2495 cmϪ1 in the free li- of dppm. The room temperature 31P NMR spectrum of 4
gand. This fact, and the absence of the SϪH signal in the shows a triplet at δ ϭ 85 assignable to the P atom of the
1H NMR spectrum, indicates the presence of the anionic phosphanylthiolate, although no signal was observed for
form of the ligand. The 1H NMR spectra exhibit multiplets the phosphorus atoms of dppm. A new broad signal ap-
in the aromatic region and, for 2, a doublet at δ ϭ 1.93 due pears in the negative region upon lowering the sample tem-
to the methyl group of the PPh2Me ligand. The 31P NMR perature that could be attributed to the dppm ligand. Deco-
spectra of the complexes show two doublets due to the two alescence occurs at 283 K and a pattern corresponding to
nonequivalent phosphorus atoms. The phosphanylthiolate an AMX spin system becomes well-resolved at 223 K with
resonance, which appears at δ ϭ Ϫ19.4 in the free ligand, the parameters δA ϭ 85.9 (d, JAM ϭ 284 Hz), δM ϭ 18.6
is shifted to about δ ϭ 85 in complexes 1؊3. This downfield (dd, JMX ϭ 77.4 Hz) and δX ϭ Ϫ27.1 (d). The high-field
shift could be considered as being due to the coordination signal at δ ϭ Ϫ27 is indicative of a free P-atom in the di-
of the phosphorus atom to the metal. The second doublet phosphane. At 283 K ∆G϶ has a value of 12.18 kcal/mol.[25]
appears at higher field: δ ϭ 26.0 (1), 9.4 (2) and 22.6 (3). Complex 5 exhibits a similar three-resonance pattern at
The LSIMSϩ mass spectra show the parent peak at m/z ϭ room temperature. The LSIMSϩ spectra show the parent
644 (1), 582 (2) and 692 (3), with appropriate isotope distri- peaks at m/z ϭ 766 (4) and 813 (5) with the appropriate
butions, in agreement with the mononuclear description of isotope distribution, again in agreement with the proposed
the three products. Electrovoltammetry studies show a non- formulation.
reversible one-electron oxidation at 0.412 V only in the case
of [Ni{PPh(C6H4S)2}(L)] (1).
When the diphosphane 1,2-bis(diphenylphosphanyl)-
ethane (dppe) is used instead of dppm, the dinuclear derivat-
When the same reaction as described in i) is carried out ives [Pd2(µ-dppe){PPh(C6H4S)2}2] [M ϭ Ni (6), Pd (7)] can
1
in the presence of a nickel or palladium complex with a be isolated as air stable solids (step iii, Scheme 1). The H
bidentate phosphane [MCl2(L-L)] (steps ii and iii, NMR spectra in CDCl3 solution display the resonances
Scheme 1), the results obtained are different depending on characteristic of the phosphanyldithiolate ligand in the aro-
Eur. J. Inorg. Chem. 2002, 826Ϫ833
827

M. Laguna et al.
FULL PAPER
matic region, as well as those of the dppe. The 31P NMR
Complexes 10 and 11 react readily with mono- and bi-
spectra reveal AAЈXXЈ systems for both complexes: 6 (δA ϭ dentate phosphanes in dichloromethane in the appropriate
87.46, δX ϭ 22.47, JAAЈ ϭ 21.32, JAX ϭ 234.13, JXXЈ
21.60 Hz), 7 (δA ϭ 84.8, δX ϭ 20.85, JAAЈ ϭ 23.7, JAX
ϭ
ϭ
stoichiometries, to give mixtures of products in which
complexes 1؊9 are the major products, as shown by 1H and
414.2, JXXЈ ϭ 25.1 Hz). This is consistent with a dinuclear 31P NMR spectroscopic data. This fact is in agreement
formulation. The mass spectrum (LSIMSϩ) does not show with the dinuclear formulation of 10 and 11.
the molecular peak for 6 and shows only weak intensity for [M{PPh(C6H4S)2}(bipy)] complexes are again inaccessible
7 (m/z ϭ 1258, 5%).
by this route, and when the corresponding reaction was at-
The reaction of [MCl2(N-N)] [N-N ϭ 2,2Ј-bipyridine tempted the starting materials were recovered unchanged.
(bipy), 1,10-phenanthroline (phen)] with PPh(C6H4SH)2 in
the presence of sodium ethoxide, depends on the N-con-
taining ligand. This ligand remains bound to the metal only
Crystal Structures of [Ni{PPh(C6H4S)2}(PPh2Me)] (2),
[Pd2(µ-dppe){PPh(C6H4S)2}2] (7) and [Ni{PPh(C6H4S)2}]2
(10)
Zubieta et al.[20] have previously reported a complex sim-
in
the
case
of
1,10-phenanthroline,
yielding
[M{PPh(C6H4S)2}(phen)] [M ϭ Ni (8), Pd (9); process iv,
Scheme 1]. Curiously, the nickel complex is soluble in con-
ventional solvents, while the palladium-containing product ilar to 1, and described it as a dinuclear derivative. Because
is not soluble enough, so that no solution data could be the data for complexes 1؊5, and particularly the mass spec-
measured for complex 9. The 31P NMR spectrum of 8 tra, point more to them being mononuclear, we undertook
shows a singlet at δ ϭ 75.4, as a consequence of the coor- the X-ray analysis of one of these complexes, namely
dination of the P atom to the metal centre, meaning that [Ni{PPh(C6H4S)2}(PPh2Me)] (2), which yielded the most
complex 8 is in all likelihood pentacoordinated. With bipy suitable crystals for X-ray studies. Figure 1 shows a view of
present as the auxiliary ligand, the reaction proceeds with the molecule, a mononuclear, distorted square planar trans-
˚
the formation of the dinuclear species [M{PPh(C6H4S)2}]2 P,P and trans-S,S nickel complex with the Ni atom 0.031 A
[M ϭ Ni (10) and Pd (11)].
out of the plane formed by S(1), P(1), S(2) and P(2) (planar
˚
The dinuclear derivatives 10 and 11 can also be obtained within 0.208 A). The main distortion from square-planar
from the reaction between PPh(C6H4SH)2 in NaOEt, and geometry arises from closure of the S(2)ϪNiϪS(1) angle
NiCl2·6H2O or [PdCl2(PhCN)2], in which PhCN serves as [166.22(4)°], and to a much lesser extent, of the angles
1
a leaving group (step v, Scheme 1). The H NMR spectra S(1)ϪNiϪP(2) and S(2)ϪNiϪP(2) [87.05(3)° and 88.66(3)°,
show only signals in the aromatic region, while the 31P respectively] most likely imposed by the rigidity of the phos-
NMR spectra display the expected singlets at δ ϭ 72.7 and phanyldithiolate ligand. The two NiϪP distances are quite
76.9, respectively, due to the equivalent phosphorus donors different from each other. The NiϪP(1) distance of
˚
in each complex. The mass spectra show the molecular 2.2054(8) A is similar to that found for NiϪPPh3 bonds
peaks at m/z ϭ 764 (45%) (10) and 861 (12%) (11), in agree- such as that found in [Ni(S3)PPh3] [S32Ϫ ϭ bis(2-mercapto-
[23]
˚
ment with a dinuclear formulation.
phenyl)sulfide, 2.197(1) A].
However, the NiϪP(2) bond
Table 1. Summary of crystallographic data for complexes [Ni{PhP(C6H4S)2}(PPh2Me)] (2), [Pd2(µ-dppe){PPh(C6H4S)2}2] CH2Cl2 (7) and
[Ni{PhP(C6H4S)2}]2 (10)
2
7
10
Empirical formula
Molecular mass
Temperature
C31H26NiP2S2
583.29
295(2) K
Monoclinic
P21/n
9.8082(6)
28.9852(19)
9.9463(6)
90
104.5850(10)
90
C64H52Cl4P4Pd2S4
1427.78
293(2) K
C18H13NiPS2
383.08
301(2) K
Monoclinic
P21/n
16.645(7)
11.073(15)
18.24(3)
90
107.80(8)
90
Crystal system
Space group
Triclinic
¯
P1
˚
a, A
9.648(2)
˚
b, A
10.858(2)
15.054(3)
97.99(3)
˚
c, A
α, deg
β, deg
γ, deg
98.78(3)
100.31(3).
1510.8(5)
1
1.569
1.057
3
˚
V, A
2736.5(3)
4
1.416
3201(7)
8
1.590
1.564
Z
Dc (Mg/m3)
µ, mmϪ1
0.998
Crystal size (mm)
θ range
0.28 ϫ 0.25 ϫ 0.18
1.41 to 25.00°
0.0530, 0.1621
0.252, Ϫ0.425
0.2 ϫ 0.2 ϫ 0.12
2.36 to 25.02°
0.0344, 0.0941
0.821, Ϫ0.720
0.18 ϫ 0.17 ϫ 0.01
2.18 to 22.99°
0.1491, 0.2748
1.215, Ϫ1.133
R1,[a] wR2[b] [I Ͼ 2σ(I)]
3
˚
Residual ρ, e A
[a]
[b]
R1 ϭ ||Fo| Ϫ |Fc|/|Fo|. wR2 ϭ {[w(F2 Ϫ F2 )]/[w(F2o)2]}1/2
.
o
c
828
Eur. J. Inorg. Chem. 2002, 826Ϫ833

PPh(2-C6H4S)2 as a Pincer Ligand in Nickel(II) and Palladium(II) Complexes
FULL PAPER
˚
length of 2.1186(8) A is shorter than the former and shorter
than other Ni-phosphanylthiolate complexes:[26] [Ni(PS)2]
with PS ϭ PPh2(C6H4S) and PPh2[C6H3(SiMe3)S], 2.181(2)
˚
and 2.172(3) A, respectively. The NiϪP(2) bond is similar
to
that
found
in
the
binuclear
compound
[Ni2{P(C6H4S)3}2][27] [2.109(4) A]. This short distance is
again consistent with the constraints imposed by the PS2
˚
˚
ligand. The NiϪS distances, which average 2.1693(8) A, are
in the range reported for terminal nickel-thiolate bonds[23]
and lie in the range found for [Ni(PS)2]:[25,26] PS ϭ
˚
PPh2(C6H4S), 2.180(2); PPh2(C6H3(SiMe3)S), 2.151(3) A.
Moreover, the NiϪS distances are similar to those found
for other phosphanylthiolate derivatives.[28Ϫ30] Complexes
1, 3, 4 and 5 presumably adopt similar mononuclear dis-
positions.
The crystal structure of 7, which includes an interstitial
molecule of CH2Cl2, was also determined by X-ray diffrac-
tion. The structure (Figure 2) displays two Pd-phosphanyl-
thiolate units connected to each other by the dppe ligand.
The geometry around each palladium centre, trans-P,P
and -S,S, is close to square planar, as was the case in 2, and
Figure 1. Compound 2 in the crystal; displacement parameter el-
lipsoids represent 50% probability surfaces; H atoms are omitted
for clarity
˚
Table 2. Selected bond lengths [A] and angles [°] for 2
˚
Table 3. Selected bond lengths [A] and angles [°] for 7·CH2Cl2
Ni(1)ϪP(2)
Ni(1)ϪS(2)
2.1186(8)
2.1630(8)
Ni(1)ϪS(1)
Ni(1)ϪP(1)
2.1756(9)
2.2054(8)
Pd (1)ϪP(1)
Pd(1)ϪS(1)
2.2265(10) Pd(1)ϪS(2)
2.3316(10)
2.3402(11)
2.3137(9)
Pd(1)ϪP(2)
P(2)ϪNi(1)ϪS(2)
P(2)ϪNi(1)ϪS(1)
S(2)ϪNi(1)ϪS(1)
88.66(3)
87.05(3)
166.22(4)
C(4)ϪP(1)ϪNi(1)
C(1)ϪP(1)ϪNi(1)
C(10)ϪP(1)ϪNi(1) 115.74(10)
C(16)ϪS(1)ϪNi(1) 104.97(11)
C(32)ϪP(2)ϪC(21) 115.43(14)
C(32)ϪP(2)ϪNi(1) 109.63(10)
113.55(11)
112.37(12)
P(1)ϪPd(1)ϪS(1) 86.78(4)
P(1)ϪPd(1)ϪS(2) 84.24(4)
S(1)ϪPd(1)ϪS(2) 164.93(3)
P(1)ϪPd(1)ϪP(2) 171.77(3)
S(1)ϪPd(1)ϪP(2) 93.79(4)
S(2)ϪPd(1)ϪP(2) 93.39(4)
C(13)ϪP(1)ϪC(7)
C(6)ϪP(1)ϪPd(1)
C(13)ϪP(1)ϪPd(1) 105.78(10)
C(7)ϪP(1)ϪPd(1) 115.55(10)
C(20)ϪP(2)ϪPd(1) 104.99(10)
C(1)ϪS(1)ϪPd(1) 103.97(11)
108.41(14)
109.03(11)
P(2)ϪNi(1)ϪP(1) 170.41(3)
S(2)ϪNi(1)ϪP(1)
S(1)ϪNi(1)ϪP(1)
C(4)ϪP(1)ϪC(1)
C(4)ϪP(1)ϪC(10) 105.42(13) C(31)ϪS(2)ϪNi(1) 105.83(10)
C(1)ϪP(1)ϪC(10) 103.21(15)
94.18(3)
92.19(3)
105.50(16) C(21)ϪP(2)ϪNi(1) 108.97(10)
C(6)ϪP(1)ϪC(13) 113.20(14) C(18)ϪS(2)ϪPd (1) 101.51(11)
C(6)ϪP(1)ϪC(7) 105.08(13)
Figure 2. Compound 7 in the crystal; displacement parameter ellipsoids represent 50% probability surfaces; H atoms are omitted for clarity
Eur. J. Inorg. Chem. 2002, 826Ϫ833 829

M. Laguna et al.
FULL PAPER
˚
[2.3402(11) A] than in other derivatives with this diphos-
phane.[34] The PdϪS bond lengths [average value 2.3227(10)
˚
A] are similar to those found in the complexes mentioned
above and in other bisdithiolene derivatives.[35Ϫ37]
The structure determination of 10 was undertaken in or-
der to establish the chemical connectivity, although it was
clear from the outset that the data would not be of high
quality. The analysis reveals (Figure 3) a dinuclear complex
consisting of two Ni-phosphanyldithiolate units linked by a
double sulfur bridge. Although the accuracy of the struc-
ture determination does not permit a systematic compar-
ison of distances, the NiϪP and NiϪS(terminal) distances
are similar to those found in complex 2; the NiϪS(bridging)
distances are greater than those for NiϪS(terminal) as is
the case in other systems with terminal and bridging sulfur
atoms, such as [Ni(S3)]3 [S32Ϫ ϭ bis(2-mercaptophenyl)sulf-
ide][23] and [Ni2{P(C6H4S)3}2].[27] It is worth noting that the
Figure 3. Compound 10 in the crystal; displacement parameter el-
lipsoids represent 50% probability surfaces; H atoms are omitted
for clarity
˚
NiϪNi distance of 2.714(6) A is rather short, which could
be indicative of some degree of metal-metal interac-
tion.[27,38,39]
˚
Table 4. Selected bond lengths [A] and angles [°] for 10
Experimental Section
Ni(1)ϪP(1)
Ni(1)ϪS(1)
Ni(1)ϪS(4)
Ni(1)ϪS(2)
2.078(10)
2.147(11)
2.215(11)
2.229(10)
2.714(6)
89.0(4)
171.4(4)
99.4(4)
86.9(4)
170.0(4)
84.5(4)
122.1(3)
122.5(3)
51.8(3)
53.2(3)
88.9(4)
Ni(2)ϪP(2)
Ni(2)ϪS(3)
Ni(2)ϪS(4)
Ni(2)ϪS(2)
2.088(10)
2.168(11)
2.201(10)
2.257(10)
General Procedures: All reactions were performed under argon us-
ing standard Schlenk techniques, although the products are air
stable. [MCl2L2] (M ϭ Ni, Pd; L ϭ PPh3, PPh2Me),[40,41] and
Ni(1)ϪNi(2)
[MCl2(L-L)] (M ϭ Ni, Pd; L-L ϭ dppm, dppe,[42,43] bipy, phen[44]
)
P(1)ϪNi(1)ϪS(1)
P(1)ϪNi(1)ϪS(4)
S(1)ϪNi(1)ϪS(4)
P(1)ϪNi(1)ϪS(2)
S(1)ϪNi(1)ϪS(2)
S(4)ϪNi(1)ϪS(2)
P(1)ϪNi(1)ϪNi(2)
S(1)ϪNi(1)ϪNi(2)
S(4)ϪNi(1)ϪNi(2)
S(2)ϪNi(1)ϪNi(2)
P(2)ϪNi(2)ϪS(3)
P(2)ϪNi(2)ϪS(4)
S(3)ϪNi(2)ϪS(4)
P(2)ϪNi(2)ϪS(2)
S(3)ϪNi(2)ϪS(2)
S(4)ϪNi(2)ϪS(2)
P(2)ϪNi(2)ϪNi(1)
S(3)ϪNi(2)ϪNi(1)
S(4)ϪNi(2)ϪNi(1)
S(2)ϪNi(2)ϪNi(1)
C(1)ϪP(1)ϪNi(1)
C(7)ϪP(1)ϪNi(1)
C(13)ϪP(1)ϪNi(1)
C(2)ϪS(1)ϪNi(1)
C(14)ϪS(2)ϪNi(1)
C(14)ϪS(2)ϪNi(2)
Ni(1)ϪS(2)ϪNi(2)
C(19)ϪP(2)ϪNi(2)
C(25)ϪP(2)ϪNi(2)
C(31)ϪP(2)ϪNi(2)
C(20)ϪS(3)ϪNi(2)
C(32)ϪS(4)ϪNi(2)
C(32)ϪS(4)ϪNi(1)
Ni(2)ϪS(4)ϪNi(1)
120.8(3)
52.3(3)
52.3(3)
were prepared by established procedures. All other reagents were
used as supplied. The synthesis of PPh(2-C6H4SH)2 was carried out
using the standard literature procedure.[45] IR spectra were re-
corded on a PerkinϪElmer 883 spectrophotometer, over the range
4000Ϫ200 cmϪ1, using Nujol mulls between polyethylene sheets.
1H and 31P NMR spectra were measured on a Varian UNITY 300
or Bruker 300 spectrometer in CDCl3 or CD2Cl2 solution; chemical
shifts are quoted relative to SiMe4 (1H) or H3PO4 (external, 31P).
The C, H N and S analyses were performed with a PerkinϪElmer
109.7(12)
117.4(13)
110.2(11)
106.6(14)
102.1(11)
112.3(12)
74.5(3)
109.9(11)
115.1(11)
106.6(11)
105.2(13)
101.5(11)
111.7(11)
75.8(3)
2400 microanalyser. Mass spectra were recorded on
Autospec, by liquid secondary ion mass spectrometry (LSIMSϩ)
using nitrobenzyl alcohol as matrix and a cesium gun.
a VG
88.5(4)
167.9(4)
172.2(4)
98.8(4)
84.2(4)
124.3(3)
Preparation of the Phosphanyldithiolate Complexes [Ni{PPh-
(C6H4S)2}PPh3] (1), [Ni{PPh(C6H4S)2}PPh2Me] (2), and
[Pd{PPh(C6H4S)2}PPh3] (3): A solution of 0.1  NaOEt (3 mL,
0.3 mmol)
and
[NiCl2(PPh3)2]
(0.098 g,
0.15 mmol),
[NiCl2(PPh2Me)2] (0.079 g, 0.15 mmol) or [PdCl2(PPh3)2] (0.105 g,
0.15 mmol) was added, over a period of 10 minutes, to a suspension
of PPh(C6H4SH)2 (0.048 g, 0.15 mmol) in 10 mL of ethanol. After
5 h of stirring, green (1,2) or brown (3) solids precipitated; these
were filtered off, washed with ethanol and dried in vacuo.
˚
the Pd atom lies out of the plane by 0.167 A, with the main
deviations due to contraction of the S(2)ϪPdϪS(1)
[164.93(3)°], S(1)ϪPdϪP(1) [86.78(4)°], and S(2)ϪPdϪP(1)
[84.24(4)°] angles. The two PdϪP distances are different
from each other, as in 2. The PdϪP(phosphanylthiolate)
1: Yield: 73 mg (75%). C36H28NiP2S2 (645.4): calcd. C 66.99, H
bond [Pd(1)ϪP(1) ϭ 2.2265(10) A] is shorter than that in 4.37, S 9.93; found C 66.45, H 4.20, S 9.50. 1H NMR (CDCl3):
˚
˚
δ ϭ 6.69 (m, 2 H, Ph), 7.18 (m, 2 H, Ph), 7.62Ϫ7.26 (m, 24 H, Ph).
31P{1H} NMR (CDCl3): δ ϭ 86.2 (d, JP-P ϭ 270 Hz), 26 (d). MS:
m/z (%) ϭ 644 (100) [M]ϩ.
PdϪP(dppe) [Pd(1)ϪP(2) ϭ 2.3402(10) A]. This reinforces
the notion that the shorter bond distance from Pd to the
phosphanylthiolate phosphorus atom results from con-
straints imposed by the ligand. Accordingly, several systems
with palladium coordinated by less restrictive P,S ligands
2: Yield: 62 mg (70%). C31H26NiP2S2 (583.3): calcd. C 63.83, H
1
4.49, S 10.99; found C 63.42, H 4.21, S 10.38. H NMR (CDCl3):
δ ϭ 1.93 (d, 2JP-H ϭ 8.3 Hz, 3 H, Me), 7.0 (m, 2 H), 7.64Ϫ7.22 (m,
21 H, Ph). 31P{1H} NMR (CDCl3): δ ϭ 87.4 (d, JP-P ϭ 280 Hz), 9.4
(d). MS: m/z (%) ϭ 582 (100) [M]ϩ, 382 (60) [M Ϫ PPh2Me]ϩ.
3: Yield: 94 mg (90%). C36H28P2PdS2 (693.1): calcd. C 62.38, H
4.07, S 9.25; found C 61.95, H 4.21, S 8.69. 1H NMR (CDCl3):
show
larger
PdϪP
distances,
such
as
in
trans-
cis-
[31]
˚
[Pd{PPh2(CH2CH2S)}Cl(PPh3)] [2.280(2) A],
[32]
˚
[Pd{PPh2(C6H4S)}2]
[2.291(1)
A]
or
˚
[33]
[Pd{PPh2(C6H4S)}2] [2.2845(8) and 2.2802(8) A].
The
PdϪP bonds involving the dppe ligand are slightly longer δ ϭ 6.99 (m, 2 H, Ph), 7.21 (m, 2 H, Ph), 7.62Ϫ7.27 (m, 24 H, Ph).
830 Eur. J. Inorg. Chem. 2002, 826Ϫ833

PPh(2-C6H4S)2 as a Pincer Ligand in Nickel(II) and Palladium(II) Complexes
FULL PAPER
31P{1H} NMR (CDCl3): δ ϭ 85.2 (d, JP-P ϭ 406 Hz), 22.6 (d). MS: δ ϭ 6.99 (m, 4 H), 7.22 (m, 4 H), 7.49Ϫ7.19 (m, 10 H), 7.56 (m, 4
m/z (%) ϭ 692 (100) [M]ϩ, 430 (55) [M Ϫ PPh3]ϩ.
H), 7.76 (m, 4 H, Ph). 31P{1H} NMR (CD2Cl2): δ ϭ 72.7 (s). MS:
m/z (%) ϭ 764 (65) [M]ϩ.
[Ni{PPh(C6H4S)2}(dppm)] (4) and [Pd{PPh(C6H4S)2}(dppm)] (5): A
solution of 0.1  NaOEt (3 mL, 0.3 mmol) and either [NiCl2dppm]
(0.077 g, 0.15 mmol) or [PdCl2dppm] (0.084 g, 0.15 mmol) was ad-
ded, over a period of 10 minutes, to a suspension of PPh(C6H4SH)2
(0.048 g, 0.15 mmol) in 10 mL of ethanol. Green (4) or orange (5)
solids precipitated immediately, and were filtered off, washed with
ethanol and dried in vacuo.
11: Yield: 56 mg (87%). C36H26P2Pd2S4 (861.6): calcd. C 50.18, H
3.04, S 14.88; found 50.45, H 3.14, S 15.26. 1H NMR (CD2Cl2):
δ ϭ 7.61Ϫ7.17 (m). 31P{1H} NMR (CD2Cl2): δ ϭ 76.9 (s). MS:
m/z (%) ϭ 861 (15) [M]ϩ.
b) A 0.1  solution of NaOEt (3 mL, 0.3 mmol) was added, over
a period of 10 minutes, to a suspension of PPh(C6H4SH)2 (0.048 g,
0.15 mmol) in 10 mL of ethanol. Then, [NiCl2·bipy] (0.042 g,
0.15 mmol) or [PdCl2·bipy] (0.050 g, 0.15 mmol) was added. After
stirring overnight green (10) or brown (11) solids precipitated,
which were filtered off, washed with ethanol and dried in vacuo.
Yields: 10: 42 mg (73%); 11: 55 mg (85%).
4: Yield: 80 mg (70%). C43H35NiP3S2 (767.5): calcd. C 67.29, H
4.59, S 8.35; found C 66.96, H 4.35, S 7.85. 1H NMR (CDCl3):
δ ϭ 3.17 (br. s, 2 H, CH2), 6.95 (m, 2 H), 7.45Ϫ7.14 (m, 29 H, Ph),
7.54 (m, 2 H, Ph). 31P{1H} NMR (CD2Cl2): δ ϭ (Ϫ50 °C): δA
85.9 (d, JAM ϭ 284 Hz), δM ϭ 18.6 (dd, JMX ϭ 77.4 Hz), δX
ϭ
ϭ
Ϫ27.1 (d). MS: m/z (%) ϭ 766 (100) [M]ϩ, 383 (70) [M Ϫ dppm]ϩ.
5: Yield: 107 mg (88%). C43H35P3PdS2 (815.2): calcd. 63.35, H 4.3,
S 7.85; found C 62.94, H 3.92, S 7.71. 1H NMR (CDCl3): δ ϭ 3.33
(br. s, 2 H, CH2), 6.95 (m, 2 H, Ph), 7.71Ϫ7.15 (m, 31 H, Ph).
31P{1H} NMR (CDCl3): δ ϭ 83.2 (d, JP-P ϭ 399 Hz), 11.3 (d),
Ϫ26.1 (br. s,). MS: m/z (%) ϭ 813 (100) [M]ϩ, 430 (70) [M Ϫ
dppm]ϩ.
Reaction of [Ni{PPh(C6H4S)2}]2 (10) and [Pd{PPh(C6H4S)2}]2 (11)
with Ligands: 0.1 mmol of L (Lϭ PPh3, PPh2Me, dppm, or phen),
or 0.05 mmol of dppe was added to
[Ni{PPh(C6H4S)2}]2 (10; 0.076 g,
a
suspension of
0.05 mmol) or
[Pd{PPh(C6H4S)2}]2 (11; 0.086 g, 0.05 mmol) in dichloromethane
(30 mL) and stirred for 6 hours to give clear solutions. Partial evap-
oration of the solvents and addition of ethanol (20 mL) afford com-
plexes 1؊8. Complex [Pd{PPh(C6H4S)2}(phen)] (9) was obtained
as a brown insoluble solid from dichloromethane.
[Ni2(µ-dppe){PPh(C6H4S)2}2] (6) and [Pd2(µ-dppe){PPh(C6H4S)2}2]
(7): The procedure followed was similar to that described for 4 and
5, using [NiCl2dppe] (0.078 g, 0.15 mmol) or [PdCl2dppe] (0.085 g,
0.15 mmol). Green (6) or brown (7) solids precipitated from the
reaction media, and were filtered off and washed with EtOH.
6: Yield: 123 mg (70%). C62H50Ni2P4S4 (1164.6): calcd. C 63.94, H
X-ray
Crystallography:
Single
crystals
of
[Ni{PPh-
(C6H4S)2}(PPh2Me)] (2) and of [Pd2(µ-dppe){PPh(C6H4S)2}2]
CH2Cl2 (7) were grown by slow diffusion of hexane into dichloro-
methane solutions of the complexes. Data collection[46] at low tem-
perature was carried out on a Bruker SMART diffractometer for 2
and on a NoniusϪKappaCCD diffractometer for 7. Crystal para-
meters and experimental details are summarised in Table 1. The
structures were solved by direct methods for 2[47] and for 7,[48] and
refined on F02 by full-matrix least-squares using the program
SHELXL-97.[49] Data were corrected for absorption using SAD-
ABS[50] for 2 and SORTAV[51] for 7. All hydrogen atoms were in-
cluded at idealised positions. Selected bond lengths and angles are
given in Table 2 and 3. The details of the crystal structures have
been deposited at the Cambridge Crystallographic Data Center as
supplementary publication nos. CCDC-162696, CCDC-162697
and CCDC-162698 for complexes 2, 7 and 10 respectively. Copies
of the data can be obtained free of charge on application to the
CCDC, 12 Union Road, Cambridge UK CB2 1EZ [E-mail:
deposit@ccdc.cam.ac.uk, Fax: (internat.) ϩ44-1223/336-033].
1
4.32, S 11.01; found C 63.55, H 4.15, S 10.52. H NMR (CDCl3):
δ ϭ 2.74 (br. s, 4 H, CH2ϪCH2), 7.61Ϫ6.66 (m, 46 H, Ph). 31P{1H}
NMR (CDCl3): AAЈXXЈ: δA ϭ δAЈϭ 87.46, δX ϭ δXЈϭ 22.47,
JAAЈ ϭ 21.32 Hz, JAX ϭ 234.13 Hz, JAXЈ ϭ JAЈX ϭ 0 Hz, JXXЈ
ϭ
21.60 Hz. MS: m/z (%) ϭ 780 (30) [M Ϫ Ni(PPh(C6H4S)2]ϩ.
7: Yield: 123 mg (65%). C62H50P4Pd2S4 (1260.0): calcd. C 59.09, H
3.99, S 10.17; found C 58.82, H 3.81, S 9.85. 1H NMR (CDCl3):
δ ϭ 3.33 (br. s, 4 H, CH2ϪCH2), 7.0 (m, 4 H), 7.61Ϫ7.17 (m, 42
H, Ph). 31P{1H} NMR (CDCl3): AAЈXXЈ: δA ϭ δAЈ ϭ 84.8, δX
ϭ
δXЈ ϭ 20.85, JAAЈ ϭ 23.7 Hz, JAX ϭ 414.2 Hz, JAXЈ ϭ JAЈX ϭ 0 Hz,
JXXЈϭ 25.1 Hz. MS: m/z (%) ϭ 1258 (5) [M]ϩ, 780 (30) [M Ϫ
Ni(PPh(C6H4S)2]ϩ.
[Ni{PPh(C6H4S)2}(phen)] (8) and [Pd{PPh(C6H4S)2}(phen)] (9): A
0.1  solution of NaOEt (3 mL, 0.3 mmol) was added over a period
of 10 minutes to
a suspension of PPh(C6H4SH)2 (0.048 g,
0.15 mmol) in 10 mL of ethanol, and then [NiCl2phen] (0.046 g,
0.15 mmol) or [PdCl2phen] (0.054 g, 0.15 mmol) was added. After
stirring overnight brown solids precipitated, which were filtered off,
washed with ethanol and dried in vacuo.
8: Yield: 55 mg (65%). C30H21N2NiPS2 (563.3): calcd. C 64.06, H
3.76, N 4.98, S 11.40; found C 63.65, H 3.35, N 4.52, S 10.98. H
NMR (CDCl3): δ ϭ 7.58Ϫ6.79 (m, 14 H, Ph), 7.62 (m, 2 H, phen),
7.78 (s, 2 H, phen), 8.23 (m, 2 H, phen), 9.72 (m, 1 H, phen).
31P{1H} NMR (CDCl3): δ ϭ 4.5(s). MS: m/z (%) ϭ 562 (5) [M]ϩ,
780 (30) [M Ϫ Ni(PPh(C6H4S)2]ϩ.
9: Yield: 64 mg (70%). C30H21PPdN2S2 (611.0): calcd. C 58.97, H
3.46, N 4.58, S 10.49; found C 58.75, H 3.5, N 4.35, S 11.05.
A very thin plate-like crystal of 10, suffering from severe aniso-
tropic mosaicity, was used for X-ray measurements. An initial, slow
reflection search yielded 12 reflections, which were indexed to a
primitive monoclinic cell.[52] Preliminary data collection between
26 and 32° (2θ) was used in an attempt to obtain better reflections
for cell determination and for ψ-scans, but the results were not
satisfactory. The positions of 13 reflections with lower values of 2θ
were used to calculate the unit cell parameters reported. Accurate
centring of reflections in the higher 2θ range was rendered difficult
because of the mosaic spread of the crystal. As for the ψ-scans, in
addition to producing low signal-to-noise ratios, they also suffered
from the effects of mosaicity; this compromises the validity of the
absorption corrections so obtained, and so absorption corrections
were not applied.
1
[Ni{PPh(C6H4S)2}]2 (10) and [Pd{PPh(C6H4S)2}]2 (11): a) Follow-
ing the same procedure as described for the previous complexes,
using NiCl2·6H2O (0.036 g, 0.15 mmol) or [PdCl2(PhCN)2]
(0.057 g, 0.15 mmol), afforded green or brown solids which precip-
itated from their respective reaction media and were filtered off and
washed with EtOH.
Intensity data were gathered in the 2θ range of 4.0Ϫ46.0°. Omega-
scans were used, with the ω scan speed set for each reflection on
the basis of a preliminary measurement made at a speed of 4°/min.
10: Yield: 40 mg (70%). C36H26Ni2P2S4 (766.2): calcd. C 56.43, H The weakest data were gathered at the slowest speed; no reflection
3.42, S 16.73; found C 56.10, H 3.21, S, 16.25. 1H NMR (CD2Cl2): was skipped on the basis of a poor showing on the initial scan. The
Eur. J. Inorg. Chem. 2002, 826Ϫ833
831

M. Laguna et al.
FULL PAPER
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Acknowledgments
We thank the Spanish Directorate General for Higher Education
and Scientific Research Grants PB98-0542 and PB98-1593 for fin-
ancial support. M.B.H. thanks the Engineering and Physical Sci-
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thank Dr. Milagros Tomas and Dr. Antonio Martın for assistance
with the X-ray data collection.
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