Lead(n) complexes with phosphorylthiolato and thiophosphorylthiolato ligands

Article abstract of DOI:10.1039/a908496g

Neutral lead complexes of a series of phosphorylarenethiol and thiophosphorylarenethiol proligands have been synthesised. Compounds [Pb{2-(Ph₂P)C₆H₄S}2] 1, [Pb{2-(Ph₂P)C₆H₄S}2] 2 and [Pb{₂-(Ph₂PO)-6-(MejSi)C₆H₃S} ₂] 3 were obtained by the electrochemical oxidation of a lead anode in a cell containing an acetonitrile solution of the ligand. [Pb{2-(Ph₂P)C₆H₄S] 4, [Pb{2-(Ph₂P)C₆H₄S}2] 5 and [Pb{2,6-(Pb{2-(Ph₂P)C₆H₄S}2] 6 were obtained by addition of the appropriate proligand to a methanol solution of lead acetate. The molecular structures of 3,4 and 5 show the metal in a five-coordinate geometry with the stereochemically active lone pair on Pb(n) in an equatorial position of a trigonal bipyramid. In 3, the metal coordination is supplemented by an additional weak Pb-(η⁶) intermolecular interaction with a phenyl ring from a neighbouring molecule. Compound 6 consists of monomeric neutral molecules with the lead atom in a pseudo trigonal-bipyramidal geometry and additional weak intramolecular coordination with two sulfur atoms. he Royal Society of Chemistry 2000.

Full text of DOI:10.1039/a908496g

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Lead(II) complexes with phosphorylthiolato and thiophosphoryl-
thiolato ligands
Paulo Pérez-Lourido,a Jaime Romero,*b José A. García-Vázquez,b Antonio Sousa,*b
Yifan Zheng,c Jonathan R. Dilworthc and Jon Zubietad
a Departamento de Química Inorgánica, Universidad de Vigo, 36200 Pontevedra, Spain
b Departamento de Química Inorgánica, Universidad de Santiago de Compostela,
15706 Santiago de Compostela, Spain
c Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, UK OXI 3QR
d Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA
Received 25th October 1999, Accepted 12th January 2000
Published on the Web 10th February 2000
Neutral lead complexes of a series of phosphorylarenethiol and thiophosphorylarenethiol proligands have
been synthesised. Compounds [Pb{2-(Ph2P)C6H4S}2] 1, [Pb{2-(Ph2P)-6-(Me3Si)C6H3S}2] 2 and [Pb{2-(Ph2PO)-
6-(Me3Si)C6H3S}2] 3 were obtained by the electrochemical oxidation of a lead anode in a cell containing an
acetonitrile solution of the ligand. [Pb{2-(Ph2P(O)CH2)C6H4S}2] 4, [Pb{2-(Ph2P(S)CH2)C6H4S}2] 5 and [Pb{2,6-
(Ph2P(S)CH2)2C6H3S}2] 6 were obtained by addition of the appropriate proligand to a methanol solution of
lead acetate. The molecular structures of 3, 4 and 5 show the metal in a five-coordinate geometry with the
stereochemically active lone pair on Pb() in an equatorial position of a trigonal bipyramid. In 3, the metal
coordination is supplemented by an additional weak Pb–(η6-C6H6) intermolecular interaction with a phenyl ring
from a neighbouring molecule. Compound 6 consists of monomeric neutral molecules with the lead atom in a
pseudo trigonal-bipyramidal geometry and additional weak intramolecular coordination with two sulfur atoms.
Since the interaction of the toxic metal lead with biological
systems frequently involves bonding to enzyme sulfydryl
groups, lead–thiolate interactions are of some interest in the
design of sequestering agents and several papers have been
dedicated to the design of specific complexing agents.1
Although thiolate complexes of lead() that do not involve
sterically demanding groups have been known for many years,2
structural studies have been hampered by their poor solubility
and lack of suitable crystallinity, probably as a result of the
tendency of thiolate groups to bridge metal centres to yield
polymeric species. Bulky groups close to donor atoms enhance
the lipophilicity and the tendency of compounds to form com-
pounds of low molecular weight. This is illustrated by the X-ray
structure of Pb(SC6H3Pri2-2,6)2 which shows the presence of a
trinuclear structure with the metal in di- and tri-coordinate
Scheme 1
environments.3 An alternative route to low molecular weight
species involves the saturation of the metal coordination sphere
The electrochemical efficiency for the process was in all cases
with donor atoms other than thiolate, and X-ray crystal struc-
tures of molecular lead() complexes with bidentate chelating
ligands such as thiohydroxamate,4 dithiocarbamate,5 thio-
benzoate6 or dithiophosphinate7 have been reported. As a
result of our continuous interest in the chemistry of monomeric
and low molecular weight thiolate metal complexes of main
group elements, we now describe the synthesis and structural
characterisation of lead() complexes with the phosphoryl-
arenethiol and thiophosphorylarenethiol proligands shown in
Scheme 1.
close to 0.5 mol FϪ1. This value and the evolution of hydrogen
at the cathode is compatible with the following electrode
processes [eqn. (1) and (2)]:
cathode: 2 R–SH ϩ 2 eϪ → 2 R–SϪ ϩ H2
anode: Pb ϩ 2 R–SϪ → [Pb(R–S)2] ϩ 2eϪ
(1)
(2)
where R–SH represents the phosphorylarenethiol or thio-
phosphorylarenethiol proligand.
Complexes 4, 5 and 6 were obtained in reasonable yields by
stirring the corresponding proligand and lead acetate in a
methanol solution at room temperature for 2 h. Crystalline
yellow solids were formed immediately in all cases. The com-
pounds were recrystallised by slow diffusion of either methanol
or diethyl ether into a CH2Cl2 solution.
The IR spectra of these complexes show no bands attribut-
able to ν(S–H), which in the free ligands appears at 2500–2400
cmϪ1. This indicates that the ligands are in the anionic thiolate
Results and discussion
Lead() phosphinothiolato complexes 1, 2 and 3 were easily
prepared in good yield by oxidation of a lead anode in a cell
containing an acetonitrile solution of the corresponding
proligand and a small amount of tetramethylammonium per-
chlorate as electrolyte. The compounds are air-stable crystalline
yellowish solids, moderately soluble in chloroform, dichloro-
methane and other common organic solvents.
DOI: 10.1039/a908496g
J. Chem. Soc., Dalton Trans., 2000, 769–774
This journal is © The Royal Society of Chemistry 2000
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Fig. 1 1H NMR of compounds [Pb{2-(Ph2P(O)CH2)C6H4S}2] 4,
[Pb{2-(Ph2P(S)CH2)C6H4S}2] 5 and [Pb{2,6-(Ph2P(S)CH2)2C6H3S}2] 6
at 233, 298 and 333 K. * resonance of an impurity of CH2Cl2.
Fig. 2 Molecular structure of [Pb{2-(Ph2PO)-6-(Me3Si)C6H3S}2] 3.
form in the complexes. The spectrum also shows bands in the
aromatic region characteristic of the coordinated phosphoryl-
thiolate ligand. The compounds containing the trimethylsilyl
group show a strong band at 850–840 cmϪ1 corresponding to
ν(Si–C) and those with the P–O group another strong band at
ca. 1130 cmϪ1
.
1
The main features of the H NMR spectra of these com-
plexes are related to the resonances of the SH and CH2
Scheme 2
1
protons. The room-temperature H NMR of these complexes
mechanisms operate in the same sense, their concurrent
existence cannot be dismissed.
show the disappearance of the signal attributable to the SH
hydrogen atom (which in the free proligands appears in the
range δ 5.1–3.9 as doublets as a result of the coupling with
the phosphorus). This again confirms that the ligands are in
the anionic thiolate form in the compounds. As for the CH2
resonances, if the structures of the compounds were rigid in
solution, the methylene protons would be diastereotopic, and
consequently the appearance of the signal should correspond
to an AB system further split by coupling to the phosphorus.
However, the behaviour is far more complicated as these
resonances are temperature dependent, showing that in solu-
tion the compounds are fluxional. This behaviour is summar-
ised in Fig. 1. For compound 4, at room temperature the signal
due to the CH2 group is a doublet due to two equivalent pro-
tons split by phosphorus. The signal broadens at 223 K as the
hydrogens become progressively more inequivalent. By con-
trast for compound 5, the resonance is broad even at 298 K,
broadens further at 223 K and splits into a broad doublet at
the higher temperature of 333 K. This suggests a more rigid
structure for 5. For compound 6, the spectrum shows a broad
The 31P NMR spectra of complexes 1–3 show a single signal
that appear at δ 37.5, 41.6 and 52.8, respectively, and at δ 27.5
and 40.5 for 4 and 5. For compound 6, the spectrum shows two
resonances at δ 40.2 and 36.6 due to the free and coordinated
P᎐S groups, respectively. The 31P NMR spectrum of compound
᎐
6 is temperature independent, showing that the mechanism of
exchange does not involve the exchanging of coordinated and
free P᎐S groups.
᎐
The FAB mass spectra of these compounds show in all cases
the molecular ion [Pb(R–S)2]ϩ (m/z 794, 937, 970, 853, 883 and
1346, respectively, for 1–6) and also the peak associated with
[Pb(R–S)]ϩ formed by loss of one P–S ligand from the initial
species. Yellow crystals of 3–6 suitable for X-ray structure
determinations were obtained by recrystallisation from CH2-
Cl2–MeOH. Attempts to obtain crystals of 1 and 2 suitable for
X-ray studies were unsuccessful, but analytical and spectro-
scopic data confirm the presence of lead() compounds with
two bidentate monoanionic ligands and presumably the
complexes have similar structures to that found for complex 3
(vide infra).
band due to the CH group of the P᎐S group bonded to the
᎐
2
metal, and a doublet at the same shift value as in the free
ligand due to the free P᎐S group. This latter signal is not tem-
᎐
X-Ray crystal structures
perature dependent. By contrast the other CH2 signal splits
into a broad doublet at 333 K, and at 223 K it appears as two
different signals of equal intensity. The signal at lower field is a
broad doublet, but the signal at higher field is a triplet, as the
result of the overlapping of the splitting due to the hydrogen
and phosphorus. This temperature dependence for 6 rules out
the possibility of a fluxional mechanism involving alternate
Molecular structure of [Pb{2-(Ph2PO)-6-(Me3Si)C6H3S}2] 3.
The molecular structure of 3 is shown in Fig. 2 together with
the atom-labelling scheme adopted. Selected bond distances
and angles appear in Table 1. The structure consists of discrete
molecules with the lead atom coordinated by two bidentate
anionic 2-diphenylphosphoryl-6-trimethylsilylbenzenethiolate
ligands through their oxygen and thiolate sulfur atoms. The
overall geometry about the Pb is best described as distorted
ψ-trigonal bipyramidal with the oxygen atoms in axial posi-
tions, with an O(1)–Pb–O(2) bond angle of 174.38(7)Њ, and the
sulfur atoms in equatorial sites, with an S(1)–Pb–S(2) bond
angle of 81.54(2)Њ. The stereochemically active lone pair on the
lead atom presumably occupies the third equatorial position.
Intermolecular interactions within 5 Å with oxygen or sulfur
atoms of any neighbouring molecules do not exist. This con-
trasts with the behaviour of other Pb() complexes with the
coordination of the two P᎐S groups, as in this case the reson-
᎐
ances of both methylene groups would be temperature
dependent. In addition, a dissociative mechanism implies that
the 31P resonances of 6 should be temperature dependent, and
this is not the case (vide infra).
A possible mechanism could be a conformational equi-
librium, which exchanges the methylene hydrogens between
axial and equatorial sites, as shown in Scheme 2.
Another possibility could be a Berry type pseudorotation
using the lead atom as the pivotal centre. Obviously, as both
770
J. Chem. Soc., Dalton Trans., 2000, 769–774

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Table 1 Selected bond distances (Å) and angles (Њ) for [Pb(2-(Ph2PO)-
6-(Me3Si)C6H3S)2] 3
Table 2 Selected bond distances (Å) and angles (Њ) for [Pb{2-(Ph2-
P(O)CH2)C6H4S}2] 4
Pb(1)–O(2)
Pb(1)–S(1)
S(1)–C(13)
P(2)–O(2)
P(1)–O(1)
2.495(2)
2.6439(8)
1.768(3)
1.501(2)
1.506(2)
Pb(1)–O(1)
Pb(1)–S(2)
S(2)–C(39)
P(2)–C(22)
P(1)–C(14)
2.519(2)
2.6462(7)
1.768(3)
1.800(3)
1.808(3)
Pb–S(1)
Pb–O(1)
S(1)–C(11)
O(1)–P(1)
P(1)–C(17)
P(1)–C(61)
P(2)–C(31)
2.584(5)
2.523(16)
1.686(18)
1.614(15)
1.77(2)
1.881(13)
1.774(13)
Pb–S(2)
Pb–O(2)
S(2)–C(41)
O(2)–P(2)
P(1)–C(21)
P(2)–C(47)
P(2)–C(51)
2.617(5)
2.599(17)
1.879(16)
1.417(15)
1.78(2)
1.822(14)
1.806(15)
O(2)–Pb(1)–O(1) 174.38(7)
O(1)–Pb(1)–S(1)
O(1)–Pb(1)–S(2)
C(13)–S(l)–Pb(1) 101.41(10)
O(2)–P(2)–C(22) 112.94(13)
O(2)–Pb(1)–S(1)
O(2)–Pb(1)–S(2)
S(1)–Pb(1)–S(2)
C(39)–S(2)–Pb(1)
O(2)–P(2)–C(34)
94.50(5)
81.34(5)
81.54(2)
106.13(10)
116.03(13)
82.14(5)
93.68(6)
S(1)–Pb–S(2)
S(2)–Pb–O(1)
C(41)–S(2)–Pb
O(1)–P(1)–C(17)
C(17)–P(1)–C(21)
C(17)–P(1)–C(61)
O(2)–P(2)–C(47)
C(47)–P(2)–C(31)
C(47)–P(2)–C(51)
94.83(8)
88.3(3)
94.1(5)
114.6(9)
107.3(10)
113.5(9)
112.6(9)
98.6(7)
S(1)–Pb–O(1)
C(11)–S(1)–Pb
P(1)–O(1)–Pb
O(1)–P(1)–C(21)
O(1)–P(1)–C(61)
C(21)–P(1)–C(61)
O(2)–P(2)–C(31)
O(2)–P(2)–C(51)
C(31)–P(2)–C(51)
89.4(3)
96.1(5)
136.2(7)
111.0(7)
106.7(7)
103.1(9)
118.1(7)
111.0(8)
109.7(8)
105.6(6)
Fig. 3 Unit cell of 3 showing the η6 interaction between a phenyl ring
and a lead atom.
same [PbS2O2] core, in which weak intermolecular associations
through oxygen or sulfur atoms are observed.4–8 Probably the
presence of the bulky trimethylsilyl groups in the ligands pre-
vents the metal atom from increasing its coordination number
through this type of intermolecular contact. The same situation
is found in the bis(N-cyclohexylphenylacetothiohydroxamato)-
lead() complex,9 reported as the first monomeric hydroxamato
lead complex as a consequence of the bulkiness of the ligands
employed. However, for the structure of 3, Fig. 3, a phenyl ring
of one molecule is close to the lead atom of other molecule,
leading to a weak Pb–(η6-C6H5) interaction between the lead
electron pair and the phenyl ring. The distances between the
lead atom and the carbon atoms of this phenyl group are in the
range of 3.50–4.15 Å, average value 3.86 Å, with a value of
3.62 Å for the distance to the centre of the ring. This value is
slightly shorter than the sum of the van der Waals radii, 3.70 Å,
when the radius of the phenyl group is considered in the direc-
tion perpendicular to the phenyl ring.10 Interactions of the type
Pb–(η6-C6H5) have also been found in [Pb{S(PPh2)2N}2],11
[Pb{S2P(OPh)2}2]12 and Pb(C6H6)(AlCl)4ؒC6H6.13
Fig. 4 Molecular structure of [Pb{2-(Ph2P(O)CH2)C6H4S}2] 4.
Fig. 5 Molecular structure of [Pb{2-(Ph2P(S)CH2)C6H4S}2] 5.
The Pb–S bond distances, 2.6439(8) and 2.6462(7) Å, are in
the range 2.55–2.72 Å reported for lead complexes of thiolate
ligands where the sulfur donor atom carries a full negative
formal charge.2,14 The Pb–O bond distances, 2.495(2) and
2.519(2) Å, are also normal and similar to those found in other
complexes with the same [PbO2S2] environment.4,8,9
with an O–Pb–O angle of 175.3(5)Њ, and bond angles between
the axial oxygen and sulfur atoms of the equatorial plane in
the range 87.2(3)–92.2(3)Њ, close to the ideal value. The main
source of distortion is the value of the equatorial bond angle
S–Pb–S (94.83(8)Њ) as a result of the small bite angle of the
ligand and the presence of the lone pair situated in this
plane. The Pb–S bond distances of 2.584(5) and 2.617(5) Å
are normal. The Pb-O bond distances, 2.523(16) and
2.599(17) Å are in the range, 2.32–2.74 Å, found for bidentate
oxygen donor ligands.15
Molecular structure of [Pb{2-(Ph2P(O)CH2)C6H4S}2] 4. Fig.
4 shows the molecular structure of 4 and the atomic numbering
scheme adopted. Selected bond distances and angles are con-
tained in Table 2. The compound is monomeric with no
interactions between neighbouring molecules. The structure is
similar to that of 3, with two anionic ligands coordinated
through the thiolate sulfur atoms and the oxygen atoms of the
phosphinyl group to the metal. The environment around the
lead atom is again a pseudo-trigonal bipyramid with the oxygen
atoms in axial positions, and the sulfur atoms and the lone pair
in the equatorial positions. This geometry is slightly distorted
Molecular structure of [Pb{2-(Ph2P(S)CH2)C6H4S}2] 5. The
molecular structure of 5 is shown in Fig. 5, and selected bond
distances and angles appear in Table 3. The structure shows
disorder within the P᎐S group with a distinct peak for each of
᎐
two independent sulfur atoms. The compound is monomeric
with the lead atom coordinated to the sulfur atoms of two aniso-
J. Chem. Soc., Dalton Trans., 2000, 769–774
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Table 3 Selected bond distances (Å) and angles (Њ) for [Pb{2-(Ph2-
P(S)CH2)C6H3S}2] 5
Table 4 Selected bond distances (Å) and angles (Њ) for [Pb{2,6-(Ph2-
P(S)CH2)2C6H3S}2] 6
Pb–S(1)
Pb–S(4Ј)
Pb–S(3Ј)
P(1)–C(31)
P(1)–S(4Ј)
P(2)–C(47)
P(2)–S(3Ј)
2.550(5)
2.885(12)
3.088(14)
1.901(11)
1.989(14)
1.74(2)
Pb–S(2)
Pb–S(4)
Pb–S(3)
P(1)–S(4)
P(2)–C(51)
P(2)–C(61)
P(2)–S(3)
2.617(6)
2.950(12)
3.151(9)
1.973(13)
1.694(12)
1.771(12)
2.003(10)
Pb–S(2)
Pb–S(01)
Pb–S(02)
S(01)–P(1)
S(03)–P(3)
P(1)–C(31)
P(1)–C(17)
P(2)–C(41)
S(1)–C(11)
2.659(7)
2.953(8)
3.370(8)
1.929(10)
1.909(11)
1.827(18)
1.84(2)
Pb–S(1)
Pb–S(04)
Pb–S(03)
S(02)–P(2)
S(04)–P(4)
P(1)–C(21)
P(2)–C(18)
P(2)–C(51)
S(2)–C(01)
2.690(6)
3.020(6)
3.386(7)
1.987(9)
1.975(7)
1.84(2)
1.76(2)
1.82(2)
1.889(19)
1.978(17)
1.81(3)
1.66(2)
S(1)–Pb–S(2)
S(2)–Pb–S(4Ј)
S(2)–Pb–S(4)
S(1)–Pb–S(3Ј)
S(2)–Pb–S(3Ј)
C(17)–P(1)–C(31)
C(31)–P(1)–C(21)
C(31)–P(1)–S(4)
94.90(9)
88.8(4)
105.8(4)
85.5(4)
84.0(3)
94.2(6)
93.7(5)
131.9(7)
S(1)–Pb–S(4Ј)
S(1)–Pb–S(4)
91.2(3)
96.1(3)
171.7(3)
18.3(4)
169.9(5)
106.6(7)
118.6(7)
107.7(6)
S(4Ј)–Pb–S(3Ј)
S(4Ј)–Pb–S(4)
S(4)–Pb–S(3Ј)
C(17)–P(1)–C(21)
C(17)–P(1)–S(4)
C(21)–P(1)–S(4)
S(2)–Pb–S(1)
85.09(10)
95.0(2)
S(2)–Pb–S(01)
S(2)–Pb–S(04)
98.1(2)
95.4(2)
S(1)–Pb–S(01)
S(1)–Pb–S(04)
P(1)–S(01)–Pb
C(31)–P(1)–C(21)
C(21)–P(1)–C(17)
C(21)–P(1)–S(01)
C(18)–P(2)–C(41)
C(11)–S(1)–Pb
98.55(19)
114.6(4)
108.1(10)
110.9(9)
108.3(8)
110.1(11)
98.8(7)
S(01)–Pb–S(04)
P(4)–S(04)–Pb
C(31)–P(1)–C(17)
C(31)–P(1)–S(01)
C(17)–P(1)–S(01)
C(18)–P(2)–C(51)
C(01)–S(2)–Pb
161.60(8)
113.8(3)
106.4(9)
109.9(7)
113.1(6)
104.4(7)
98.3(6)
longer than a covalent Pb–S bond but significantly shorter than
the sum of van der Waals radii, ca. 3.80 Å.17
Experimental
All manipulations were carried out under an inert atmosphere
of dry nitrogen. Lead (Aldrich Chemie) was used in rod form.
All other reagents were used as supplied. Syntheses of ligands
2-(Ph2P)C6H4SH, 2-(Ph2P)-6-(Me3Si)C6H3SH and 2-(Ph2PO)-
6-(Me3Si)C6H3SH were carried out using minor modifications
of the standard literature procedures.18 2-(Ph2P(O)CH2)C6H4-
SH and 2-(Ph2P(S)CH2)C6H4SH proligands were prepared
following a similar method described for the synthesis of 2,6-
(Ph2P(S)CH2)2C6H3SH.19
Elemental analyses were performed using a Carlo-Erba EA
microanalyser. IR spectra were recorded as KBr mulls on a
Bruker IFS-66V. FAB mass spectra were recorded on a Kratos-
MS-50T connected to a DS90 data system, using 3-nitrobenzyl
alcohol (3-NBA) as matrix material. 1H and 13C NMR spectra
were recorded on a Bruker AMX 300 MHz instrument against
TMS as internal standard and 31P in a Bruker 500 MHz, against
H3PO4 (85%), using CDCl3 as a solvent in all cases.
Fig. 6 Molecular structure of [Pb{2,6-(Ph2P(S)CH2)2C6H3S}2] 6.
bidentate chelate ligands. The arrangement of the four sulfur
atoms around the metal atoms is ψ-trigonal bipyramidal with a
Preparation of the complexes
vacant equatorial site, and the two sulfur atoms of the P᎐S
᎐
Complexes 1–3 were obtained using an electrochemical pro-
cedure. An acetonitrile solution of the ligand containing about
15 mg of tetramethylammonium perchlorate as a support
electrolyte was electrolysed using a platinum wire as the cathode
and a metal plate as the sacrificial anode. Applied voltages of
10–15 V allowed sufficient current flow for smooth dissolution
of the metal. During electrolysis, nitrogen was bubbled through
the solution to provide an inert atmosphere and also to stir the
reaction mixture.
groups in axial positions, (S(4Ј)–P–S(3Ј) 171.7(3)Њ). The thiolate
sulfur atoms are in the equatorial plane (S(1)–Pb–S(2)
94.90(9)Њ) together with the lone pair of the metal. Two differ-
ent S–Pb bond lengths are observed in the compound. The
shortest length corresponds to the anionic thiolate sulfur atoms
and the values, 2.550(5) and 2.617(6) Å, are similar to those
observed for 3 and 4, and in the range for the observed for
primary interactions in Pb() complexes with terminal mono-
or di-thiolate ligands, 2.554(4)–2.696(3) Å.14,16
[Pb{2-(Ph2P)C6H4S}2] 1. Electrochemical oxidation of a lead
anode in a solution of 2-diphenylphosphinobenzenethiol,
2-(Ph2P)C6H4SH, (0.230 g, 0.782 mmol) in acetonitrile (50 cm3),
at 10 V and 10 mA for 2 h caused 75 mg of lead to be dissolved,
Ef = 0.48 mol FϪ1. During the electrolysis hydrogen was evolved
at the cathode and at the end of the electrolysis a yellow solid
appeared at the bottom of the vessel. The solid was filtered off,
washed with acetonitrile and diethyl ether and dried in vacuo
(0.21g, 73%). Anal. Calc. for C36H28PbP2S2: C, 54.5; H, 3.5; S,
8.1. Found: C, 53.4, H, 3.3; S, 8.0%. IR (KBr, cmϪ1): 1570m,
1482m, 1433s, 1416m, 1241s, 1091m, 738s, 692s; 525s. 1H NMR
(CDCl3 ppm): δ 7.6–6.5 (m, 28 H). 31P NMR (CDCl3): δ 37.5.
Molecular structure of [Pb{2,6-(Ph2P(S)CH2)2C6H3S}2] 6.
Fig. 6 shows the molecular structure of 6. Selected bond dis-
tances and angles appear in Table 4. The compound consists
of monomeric neutral molecules with the metal coordinated
by two bidentate monoanionic ligands. The geometry of
the primary coordination sphere around the metal is pseudo-
bipyramidal with two anionic thiolate sulfur atoms in equa-
torial positions, bond angle S(2)–Pb–S(1) 85.09(10)Њ and Pb–S
bond distance 2.674(7) Å (average value), and two P᎐S groups
᎐
in axial positions, (S(01)–Pb–S(04) 161.60(8)Њ), Pb–S bond
distances 2.986 Å (average). These bond distances are normal
and similar to those found in 5. Significant secondary intra-
molecular interactions with S(02) and S(03) are observed. These
secondary Pb–S bond distances, 3.370(8) and 3.386(7) Å, are
[Pb{2-(Ph2P)-6-(Me3Si)C6H3S}2] 2. A similar experiment (12
V, 10 mA, 2 h) with lead as anode and 0.273 g (0.746 mmol) of
772
J. Chem. Soc., Dalton Trans., 2000, 769–774

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Table 5 Summary of crystallographic data for [Pb{2-(Ph2PO)-6-(Me3Si)C6H3S}2] 3, [Pb{2-(Ph2P(O)CH2)C6H4S}2] 4, [Pb{2-(Ph2P(S)CH2)C6H4S}2]
5 and [Pb{2,6-(Ph2P(S)CH2)2C6H3S}2] 6
3
4
5
6
Chemical formula
Formula weight
T/K
C42H44O2P2S2Si2Pb
970.20
150(2)
C38H32O2P2S2Pb
853.88
150(2)
C38H32P2S4Pb
886.01
150(2)
C64H54P4S6Pb
1346.52
293(2)
Crystal system
Space group
Monoclinic
P21/n
Monoclinic
Cc
Monoclinic
Cc
Monoclinic
Cc
a/Å
b/Å
c/Å
11.417(2)
24.1217(3)
15.8139(2)
106.6110(1)
4173.40(7)
4
14.6460(10)
15.5010(10)
15.4290(10)
99.583(2)
3453.9(4)
4
15.5560(10)
15.6120(10)
15.0520(10)
100.455(2)
3594.8(4)
4
16.212(3)
14.4198(10)
25.146(3)
92.014(14)
5874.9(14)
4
β/Њ
V/Å3
Z
µ/mmϪ1
4.311
5.131
5.041
3.234
Reflections collected
Independent reflections
Data/restraints/parameters
Ra
26969
9852
9852/0/455
0.0268
0.0608
6487
6712
5678
3674 (0.0367)
3674/2/420
0.0337
3804 (0.0342)
3804/68/369
0.0475
5678 (0.00)
5678/2/676
0.0362
b
wR2
0.852
0.1164
0.0849
a R = Σ(|Fo| Ϫ |Fc|)/Σ|Fo|. b wR2 = [(Σw(|Fo| Ϫ |Fc|)2/Σw|Fo|2]1/2
.
2-(Ph2P)-6-(Me3Si)C6H3SH in 50 cm3 of acetonitrile, dissolved
80 mg of lead, Ef = 0.52 mol FϪ1. As the reaction proceeds the
solution changed from colourless to yellow. At the end of the
electrolysis the yellow solid deposited in the cell was recovered,
washed with cool acetonitrile and diethyl ether and dried in
vacuo (0.30 g, 86%). Anal. Calc. for C42H44PbP2S2Si2: C, 53.8;
H, 4.7; S, 6.8. Found: C, 53.6; H, 4.6; S, 6.4%. IR (KBr, cmϪ1):
3053m, 2949m, 2893m, 1554m, 1483m, 1434m, 1355s, 1245m,
1086m, 850s, 746s, 692s, 530s. 1H NMR (CDCl3): δ 7.7–6.6 (m,
26 H), 0.30 (s, 18H). 31P NMR (CDCl3): δ 41.6.
scopy and elemental analysis. Anal. Calc. for C38H32P2S4Pb: C,
51.5; H, 3.6; S, 14.5. Found: C, 50.7; H, 3.0; S, 14.2%. IR (KBr,
cmϪ1) 3052m, 2898m, 1582m, 1462w, 1435m, 1104s, 830m,
1
747m, 699s, 599m. H NMR (CDCl3): δ 7.9 (complex m, 8H),
7.8 (m, 2H), 7.5 (m, 10H), 7.4 (m, 2H), 7.1 (t, 2H), 6.7 (t, 2H),
6.5 (d, 2H), 4.65 (d, JPH = 12.4 Hz, CH2P, 4H). 13C NMR
(CDCl3): δ 142–126, 39.7 (d, JPC = 51.7 Hz, CH2P). 31P NMR
(CDCl3): δ 40.5.
[Pb{2,6-(Ph2P(S)CH2)2C6H3S}2] 6. To a methanol solution of
2,6-(Ph2P(S)CH2)2C6H3SH (0.33 g, 0.588 mmol) was added 0.1
g (0.29 mmol) of lead acetate. The mixture was stirred for 4 h,
the yellow solid formed was filtered off, and washed with
methanol and diethyl ether. Yield 0.28 g (72%). Anal. Calc. for
C64H54P4S6Pb: C, 57.1; H, 4.0; S, 14.3. Found: C, 56.4; H, 4.2;
S, 13.6%. 1H NMR (CDCl3): δ 7.9–6.8 (m, Ph, 23H), 3.69
(d, JPH = 13.3 Hz, CH2P, 4H). 31P NMR (CDCl3): δ 40.2, 36.6.
[Pb{2-(Ph2PO)-6-(Me3Si)C6H3S}2] 3. Electrolysis of an
acetonitrile solution (50 cm3) containing 2-(Ph2PO)-6-(Me3Si)-
C6H3SH (0.214 g, 0.560 mmol) using a current of 10 mA, (12 V)
for 1.5 h caused the dissolution of 58 mg of lead (Ef = 0.50 mol
F
Ϫ1) to produce a yellow crystalline solid. The solid was washed
with acetonitrile and diethyl ether and dried in vacuo (0.22 g,
82%). Anal. Calc. for C42H44PbP2O2S2Si2: C, 52.0; H, 4.5; S, 6.6.
Found: C, 51.2; H, 4.3; S, 6.5%. IR (KBr, cmϪ1): 3055m, 2952m,
2895m, 1556m, 1438s, 1353s, 1242s, 1130s, 1065m, 845s, 748s,
X-Ray crystal structure determinations
Data collection. Intensity data were collected on a CAD4
diffractometer for compound 3 and on an Enraf-Nonius
DIP2000 image-plate diffractometer for 4–6, with mono-
chromated Mo-Kα radiation (λ = 0.71073 Å) in all cases. The
images were processed with the Denzo and Scalepak programs
for the latter compounds.20
1
692s. H NMR (CDCl3): δ 7.7–6.7 (m, 26H), 0.40 (s, 18H). 31P
(CDCl3): δ 52.8. Crystals suitable for X-ray studies were
obtained by crystallisation from CH2Cl2–MeOH.
[Pb{2-(Ph2P(O)CH2)C6H4S}2] 4. To a solution of 2-(Ph2P-
(O)CH2)C6H4SH (0.10 g, 0.31 mmol) in 20 ml of methanol
was added a solution of lead acetate (0.05 g, 0.154 mmol) in
methanol (15 ml). The solution was stirred at room temperature
for 2 h to give a bright yellow solid, which was filtered off,
washed with methanol, diethyl ether and dried in vacuo (0.105
g, 81%). Crystals suitable for X-ray studies were obtained by
crystallisation from CH2Cl2–diethyl ether and identified by
spectroscopy and elemental analysis. Anal. Calc. for C38H32P2-
S2O2Pb: C, 53.4; H, 3.7; S, 7.5. Found: C, 52.0; H, 3.24; S, 6.7%.
IR (KBr, cmϪ1) 3053m, 2920m, 1582m, 1462m, 1436m, 1383m,
Structure analysis and refinement. The structures were solved
2
via direct methods21 and refined on Fo by full-matrix least-
squares methods.22 All non-hydrogen atoms were refined
anisotropically. The hydrogen atoms were included in idealised
positions with Uiso free to refine. The weighting scheme gave
satisfactorily agreement analysis. Sources of scattering factors
were as in ref. 18. Details of the structure determination are
listed in Table 5.
CCDC reference number 186/1802.
See http://www.rsc.org/suppdata/dt/a9/a908496g/ for crystal-
lographic files in .cif format.
1
1225w, 1136s, 1094m, 835s, 749m, 722s, 629m, 534s. H NMR
(CDCl3): δ 7.85 (t, 8H), 7.55 (m, 14H), 7.05 (t, 2H), 6.7 (t, 2H),
6.5 (t, 2H), 4.35 (d, JPH = 12.6 Hz, CH2P, 4H). 13C NMR
(CDCl3): δ 141–125, 36.6 (d, JPC = 57.5 Hz, CH2P). 31P NMR
(CDCl3): δ 27.5.
Acknowledgements
We thank the Xunta de Galicia (Spain), (Xuga 20910B93 and
Xuga 20316B96), for financial support.
[Pb{2-(Ph2P(S)CH2)C6H4S}2] 5. The same procedure as for 4
was used for the synthesis of this compound. A solution of lead
acetate (0.20 g, 0.588 mmol) in 25 ml of methanol was added to
2-(Ph2P(S)CH2)C6H4SH (0.094 g, 0.290 mmol), in 20 ml of
methanol. It was stirred for 2 h to give a yellow solid (0.23 g,
89%). Crystals suitable for X-ray studies were obtained by
crystallisation from CH2Cl2–MeOH and identified by spectro-
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