Diphenyllead(IV) thiosemicarbazonates and pyrazolonates: Synthesis and characterization

Article abstract of DOI:10.1016/j.poly.2009.01.004

Cyclization of thiosemicarbazones derived from β-keto esters and β-keto amides (HTSC) in the presence of diphenyllead(IV) acetate was explored in methanol solution at room temperature and under reflux. All β-keto ester TSCs underwent cyclization to give t

Full text of DOI:10.1016/j.poly.2009.01.004

Polyhedron 28 (2009) 1029–1039
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Polyhedron
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Diphenyllead(IV) thiosemicarbazonates and pyrazolonates:
Synthesis and characterization
b
b
a
José S. Casas a, , Eduardo E. Castellano , Javier Ellena , María S. García-Tasende ,
*
Agustín Sánchez a, , José Sordo , Ángeles Touceda
a
a
*
a Departamento de Química Inorgánica, Facultade de Farmacia, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain
b Instituto de Física de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 369, CEP 13560 Sao Carlos, SP, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
Cyclization of thiosemicarbazones derived from b-keto esters and b-keto amides (HTSC) in the presence
of diphenyllead(IV) acetate was explored in methanol solution at room temperature and under reflux. All
b-keto ester TSCs underwent cyclization to give the corresponding pyrazolone (HL), which, except in one
Received 11 December 2008
Accepted 9 January 2009
Available online 13 February 2009
2+
case, deprotonated and coordinated the PbPh2 moiety to form homoleptic [PbPh2(L)2] or heteroleptic
[PbPh2(OAc)(L)] derivatives. Cyclization did not occur with b-keto amide TSCs and only [PbPh2(TSC)2]
or [PbPh2(OAc)(TSC)] thiosemicarbazonates were isolated. The complexes were characterized by IR spec-
troscopy in the solid state and by 1H, 13C and 207Pb NMR spectroscopy in DMSO–d6 solution, in which they
evolve and decompose with time. Additionally, crystals of p-acetoacetanisidide thiosemicarbazone
(HTSC10), [PbPh2(OAc)(L5)] Á MeOH (HL5 = 2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazolone-1-carbothioa-
mide), [PbPh2Cl(L2)] (HL2 = 2,5-dihydro-5-oxo-3-phenyl-1H-pyrazolone-1-carbothioamide), [PbPh2(OAc)-
(TSC8)] Á 2MeOH (HTSC8 = acetoacetanilide thiosemicarbazone), [PbPh2(OAc)(TSC10)] Á H2O and
[PbPh2(OAc)(TSC11)] Á 0.75MeOH (HTSC11 = o-acetoacetotoluidide) were studied by X-ray crystallogra-
phy. The complexes, monomers or dimers with almost linear C–Pb–C moieties, are compared with the
corresponding derivatives of Pb(II).
Dedicated to Professor Alfredo Mederos on
the occasion of his retirement.
Keywords:
Diphenyllead(IV) complexes
Cyclization
Thiosemicarbazone ligands
Pyrazolone ligands
X-ray diffraction
1H, 13C and 207Pb NMR
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
the deÀprotonated N(2) atom on the C(O)R3 group and the loss of
the R3 anion.
Monothiosemicarbazones (HTSCn) derived from 1,3-dicarbonyl
compounds can undergo chain-to-ring evolution (Scheme 1) [1].
This interesting phenomenon is promoted by certain metal ions
and leads to the formation of 5-pyrazolone (HLn) derivatives, usu-
ally under mild conditions [2]. Several factors influence this reac-
tion, but two of these are decisive for the viability of the process.
The first factor is intrinsic and is related to the nature of the R3
group, with the TSCs derived from b-keto esters being more prone
to cyclization than those obtained from b-keto amides. The second
factor, which is extrinsic, is the identity of the metal promoter.
Thus, ions such as Zn(II) are less effective, with regard to the acti-
vation of the cycle formation, than Cd(II) [3].
The ROÀ groups are better leaving groups than the RNHÀ groups
and, as a result, step (II) ? [III] is more easily accomplished when
the TSCs are derived from b-keto esters. It has also been suggested
that the formation of an N(4)–HÁÁÁN(2) hydrogen bond is possible in
the b-keto amide TSCs, and this intramolecular union can slow
down the nucleophilic attack of N(2) on the carbonyl group [3].
At present, the origin of the influence of the metal ion is less
clear and more experimental evidence is needed to rationalize this
aspect of the reaction. As Zn(II) is a ‘‘borderline” acid and Cd(II) a
‘‘soft” acid according to the HSAB principle of Pearson [4], and tak-
ing into account that the two ions behave differently with respect
to the cyclization – with the former less effective than the latter –
it is possible that the influence of the metal may be related to its
classification according to the HSAB principle.
In order to further explore this possibility, we recently reacted
several HTSCn with Pb(II) ions [2]. In accordance with the ‘‘border-
line” character of this ion [4], only a limited number of TSCs de-
rived from b-keto amides (one of three) underwent cyclization.
In the work described here, we analyzed the evolution of several
HTSCn (see Scheme 3) caused by the Ph2Pb(IV) cation, for which
the same ‘‘borderline” character has been proposed on the grounds
of structural evidence [5]. As far as possible, in order to avoid the
The first factor can be rationalized by considering the proposed
cyclization scheme [Ref. [3], see Scheme 2], in which the process
starts with the complexation of the metal ion by the TSC after
deprotonation. This step is followed by the nucleophilic attack of
* Corresponding authors. Tel.: +34 981 528074; fax: +34 981 547102
(A. Sánchez).
E-mail addresses: sergio.casas@usc.es (J.S. Casas), agustin.sanchez@usc.es
(A. Sánchez).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.01.004

1030
J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
spectra. All spectroscopic measurements were carried out at the
RIAIDT services of the University of Santiago de Compostela.
2.2. Materials
Thiosemicarbazide
(Merck),
N1-ethylthiosemicarbazide
(Merck), methyl acetoacetate (Aldrich), ethyl benzoylacetate
(Aldrich), methyl 4-methoxyacetoacetate (Aldrich), methyl pro-
pionoylacetate (Aldrich), ethyl 2-methylacetoacetate (Aldrich),
ethyl 2-ethylacetoacetate (Aldrich), acetoacetanilide (Merck),
o-acetoacetanisidide (Aldrich), p-acetoacetanisidide (Aldrich),
o-acetoacetotoluidide (Aldrich), silver acetate (Probus), and
diphenyl- lead(IV) chloride (ABCR) were used as received. Diphen-
yllead(IV) acetate was prepared in situ by stirring diphenyllead(IV)
chloride and silver acetate in methanol for 5 h. The resulting AgCl
precipitate was filtered off and the solution containing the organo-
lead(IV) acetate was used immediately in the preparation of the
complexes.
Scheme 1.
2.3. Synthesis of ligands
The thiosemicarbazone ligands derived from b-dicarbonyl com-
pounds (b-keto esters and b-keto amides) were prepared according
to the method described by Jayasree and Aravindakshan [6]. Phys-
ical and analytical properties of HTSCn (n = 1–10) and HLn (n = 1–7)
have been reported elsewhere [3,7]. Recrystallization of HTSC10
from EtOH gave crystals suitable for X-ray analysis.
The synthesis and physical and spectroscopic properties of
HTSC11 are described below.
HTSC11. A mixture of 0-acetoacetotoluidide (1.90 g, 10 mmol)
and thiosemicarbazide (0.90 g, 10 mmol) in ethanol (125 ml) was
heated under reflux for 1 h. The resulting white solid was filtered
off and dried under vacuum. M.p.: 158 °C. Anal. Calc. for
C12H16N4OS: C, 54.5; H, 6.1; N, 21.2; S, 12.1. Found: C, 54.6; H,
6.0; N, 20.8; S, 11.9%. IR (cmÀ1): 3443 s, 3280 s, 3163 m,
1651 s, (C@O); 1600 s, (C@N); 1497 s, 1247 w,
m, 850 w,
(C@S). 1H NMR: 10.43 s, 10.15 s, 9.67 s, 9.44 s [(2),
m
(N–H);
m
m
m(NH–Ph); 1023
m
N(2/4)H]; 8.14 s, 7.67 s, 7.63 s [(2), N(1)H2]; 7.36–7.08 m [(4), H8-
11]; 3.56 s, 3.40 s [(2), C(3)H2]; 2.20 s, 2.17 s [(3), C(12)H3]; 2.03 s,
1.99 s [(3), C(5)H3]. 13C NMR: 178.8 [C(1)]; 167.1 [C(4)]; 149.0
[C(2)]; 136.0–125.1 [C(6–11)]; 46.0 [C(3)]; 17.8 [C(12)]; 16.7 [C(5)].
Scheme 2.
interference of other factors, we maintained the same experimen-
tal conditions used in the Pb(II) reactions: namely, the same sol-
vent, identical counter-ion (AcOÀ) and similar temperature. As
described below, if there is a direct relationship between cycliza-
tion capacity and acid behaviour in terms of the HSAB principle,
then Ph2Pb(IV) seems to be ‘‘harder” than Pb(II).
2.4. Synthesis of complexes
General procedure [Caution! Organolead(IV) compounds are very
toxic] [8]. A solution of freshly prepared PbPh2(OAc)2 in methanol
was mixed in 1:2 or 1:1 molar ratio with a solution or suspension
of the thiosemicarbazone ligand in the same solvent. The resulting
mixtures were stirred for 6 h at room temperature or under reflux.
The experimental conditions and the complexes obtained are sum-
marized in Table 1. Only the reaction between PbPh2(OAc)2 and
HTSC4 gave unidentified products under all conditions. Details for
each reaction are described in Supplementary data.
2. Experimental
2.1. Physical measurements
Elemental analyses were performed on a Fisons instruments
EA1108CHNS-O microanalyser. Melting points (m.p.), uncorrected,
were determined with a Büchi apparatus. The electrospray mass
spectra of the complexes were measured on a Hewlett–Packard
model LC-MSD 1100 instrument (positive ion mode, 98:2 MeOH/
HCOOH as mobile phase, 20–100 V). IR spectra were recorded from
KBr discs on a Bruker IFS66V FT-IR spectrometer and are reported
in cmÀ1. The 1H, 13C and 207Pb NMR spectra of DMSO–d6 solutions
were recorded on Bruker DPX 250, AMX 300 or AMX 500 instru-
ments; chemical shifts are expressed on the d scale (downfield
shifts positive) relative to tetramethylsilane using the solvent sig-
nal for 1H and 13C NMR spectra and using a saturated solution of
Ph4Pb in CDCl3 (À178 ppm) as the external reference for 207Pb
The analytical, physical and spectroscopic data for the com-
plexes obtained are listed below.
[PbPh2Cl(L2)]. Colour: yellow. M.p.: 191 °C (d). Anal. Calc. for
C22H18N3OSClPb: C, 42.96; H, 2.95; N, 6.83; S, 5.21. Found: C,
42.79; H, 3.10; N, 6.82; S, 5.09%. IR (cmÀ1): 3283 s, 3111 w, 3058
s,
m
(N–H); 1612 s,
m(C@O); 1578 s, m(ring); 1402 s, m(C–N); 922
m, 764 m,
m
(C@S). 1H NMR: 11.80 bs, 9.93 bs [(2) N(1)H2]; 8.03 d
(4) [HoPh2Pb]; 7.63 t (4) [HmPh2Pb]; 7.47 t (2) [HpPh2Pb]; 7.38 m
(2) [C(6,10)H]; 7.28 m (3) [C(7–9)H]; 5.87 s, 5.45 br s [(1) C(3)H].
[PbPh2(L2)2]. Colour: yellow. M.p.: 163 °C (d). Anal. Calc. for
C30H28N6O2S2Pb: C, 46.44; H, 3.64; N, 10.83; S, 8.26. Found: C,
47.45; H, 3.31; N, 10.74; S, 8.78%. MS (electrospray), m/z (%): 161
(100) [(H2B)+HÀ{NH2C(S)}]. IR (cmÀ1): 3295 s, 3160 w, 3118 s,

J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
1031
Scheme 3. Ligands used in this work or obtained by cyclization (see Scheme 1).
3064 w,
918 w, 765 m,
m
(N–H); 1652 s,
m
(C@O); 1369 s,
m
(C–N); 1590 sh,
m
(ring);
[CH3COO]. 13C NMR: 175.5 [C(1)]; 166.5 [C(4)]; 161.0 [Cipso(Ph2Pb)];
143.3 [C(2)]; 136.1 [Co(Ph2Pb)], 2J(13C–207Pb) = 87.2 Hz; 132.9
[Co(Ph2Pb)], 2J(13C–207Pb) = 128.0 Hz; 130.2 [Cm(Ph2Pb)]; 130.0
[Cp(Ph2Pb)]; 130.0–124.7 [C(5–10)]; 86.8, 83.7 [C(3)]; 23.2 [CH3COO].
[PbPh2Cl(TSC3)]. Colour: white. M.p.: 135 °C. Anal. Calc. for
C19H22N3O3SClPb: C, 37.10; H, 3.60; N, 6.83; S, 5.21. Found: C,
37.41; H, 3.60; N, 7.03; S, 5.27%. IR (cmÀ1): 3478 s, 3358 s, 3170
m
(C@S). 1H NMR: 12.19 br s, 9.96 br s [(4) N(1)H2];
7.96 d [HoPh2Pb], 3J(1H–207Pb) = 206.5 Hz; 7.85 s (4) [C(6,10)H];
7.67 t [HmPh2Pb]; 7.63 [HoPh2Pb]; 7.50 t [HpPh2Pb]; 7.45 s (6)
[C(7–9)H]; 7.37 t [HmPh2Pb]; 7.27 t [HpPh2Pb]; 6.06 bs, 5.87 s [(2)
C(3)H]. 13C NMR: 175.8 [C(1)]; 165.9 [C(4)]; 160.9 [Cipso(Ph2Pb)];
143.3 [C(2)]; 135.8 [Co(Ph2Pb)], 2J(13C–207Pb) = 90.0 Hz; 132.9
[Co(Ph2Pb)], 2J(13C–207Pb) = 132.9 Hz; 130.3 [Cm(Ph2Pb)]; 130.2
[Cp(Ph2Pb)]; 130.0–124.5 [C(5–10)]; 86.7 [C(3)].
w, 3053 w,
1453 w, d(OCH2); 1247 w,
m
(N–H); 1725 s,
m
(C@O); 1597 s,
m
(C@N); 1432 s,
m
(C–O); 1014 m, 744 s,
m
(C@S). 1H
[PbPh2(OAc)(L2)]. Colour: yellow. M.p.: 135 °C (d). Anal. Calc. for
C24H21N3O3SPb: C, 45.13; H, 3.31; N, 6.58; S, 5.02. Found: C, 44.62;
H, 3.45; N, 6.18; S, 4.82%. MS (electrospray), m/z (%): 580 (25)
[MÀ(OAc)]; 485 (47) [MÀ(2Ph)] ꢀ [Pb(OAc)(L2)]; 288 (63)
[Pb(L2)]À{(Ph)+(C(S)NH2)}; 242 (22) HL2+Na; 185 (23)
(HL2)+H+NaÀ{C(S)NH2}; 161 (100) (HL2)+HÀ{NH2C(S)}. IR (cmÀ1):
NMR: 7.92 d (4) [Ho(Ph2Pb)], 3J(1H–207Pb) = 110 Hz; 7.55 t (4)
[Hm(Ph2Pb)]; 6.93 s (2) [N(1)H2]; 3.97 s (2) [C(5)H2]; 3.61 s, 3.51 s
[(2) C(3)H2]; 3.60 s (3) [C(7)H3]; 2.91 s (3) [C(6)H3]. 13C NMR:
168.4 [C(4)]; 159.8 [C(2)]; 136.7 [Co(Ph2Pb)], 2J(13C–207Pb) = 88 Hz;
129.9 [Cm(Ph2Pb)]; 129.2 [Cp(Ph2Pb)]; 74.7 [C(5)]; 58.8 [C(6)]; 52,1
[C(7)]; 32.8 [C(3)].
3138 w, 3053 m,
(CH3COO), ( : 169); 1385 s,
754 m,
(C@S). 1H NMR: 12.00–9.00 (2) [N(1)H2]; 8.30–7.00 m
(15) [R1(Ph)+H(Ph2Pb)]; 5.87 s, 5,19 s [(1), C(3)H]; 1.80 s (3)
m(N–H); 1609 s,
m(C@O); 1567 s, 1398 s,
[Pb(L3)2]. See Ref. [2].
m
D
m
m(C–N); 1575 h,
m
(ring); 921 m,
[PbPh2(L3)2]. Colour: beige. M.p.: 121 °C. Anal. Calc. or
C24H26N6O4S2Pb: C, 39.28; H, 3.57; N, 11.45; S, 8.72. Found: C,
37.55; H, 3.73; N, 11.56; S, 9.05%. MS (electrospray), m/z (%): 548
m

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J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
Table 1
Reactions of PbPh2(OAc)2 with HTSCn in MeOH: conditions used and compounds obtained.
Ligand
HTSC1
M:L (mol ratio)
T
Compounds
1:2
1:1
1:2
r.t.
r.t.
r.t.
HL1a
HL1a
HTSC2
unidentified product
under reflux
r.t.
under reflux
r.t.
[PbPh2(L2)2]
1:1
1:2
[PbPh2Cl(L2)]
[PbPh2(OAc)(L2)]
[PbPh2Cl(TSC3)]
first fraction, [Pb(L3)2]
second fraction, [PbPh2(L3)2]
[PbPh2Cl(TSC3)]b
unidentified products
HTSC3
under reflux
1:1
1:1 and 1:2
r.t.
r.t.
HTSC4
HTSC5
under reflux
r.t.
1:2
1:1
first fraction, [Pb(L5)2]
second fraction, [PbPh2(L5)2]ÁH2O
under reflux
r.t.
under reflux
[Pb(OAc)(L5)]
unidentified product
first fraction, [Pb(OAc)(L5)]
second fraction, [PbPh2(OAc)(L5)] Á MeOH
[PbPh2(L6)2]c
HTSC6
1:2
1:1
1:2 or 1:1
1:2 or 1:1
1:2
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
[PbPh2(OAc)(L6)]
HTSC7
HTSC8
HTSC9
[PbPh2(OAc)(L7)]c
[PbPh2(OAc)(TSC8)] Á 2MeOHc
[PbPh2(TSC9)2]
1:1
first fraction, [PbPh2(TSC9)2]d
second fraction, [PbPh2(OAc)(TSC9)]e
[PbPh2(OAc)(TSC10)] Á H2Oc
[PbPh2(OAc)(TSC11)] Á 0.75MeOHc
HTSC10
HTSC11
1:2 or 1:1
1:2 or 1:1
r.t.
r.t.
a
The same compound was obtained when the reaction mixture was heated under reflux for 6 h.
The reaction of this ligand under reflux afforded unidentified products when a 1:1 molar ratio was used.
The same compound was obtained when 1:2 or 1:1 molar ratios were heated under reflux for 6 h.
The same compound was obtained when 1:2 or 1:1 (second fraction) molar ratios were heated under reflux for 6 h.
The same compound was obtained when a 1:1 (first fraction) molar ratio was heated under reflux for 6 h.
b
c
d
e
(98) [MÀ(L3)]. IR (cmÀ1): 3277 s, 3094 w, 3055 w,
m
(N–H); 1663 m,
91.8 [C(3)]; 23.1, 21,0 [CH3COO]; 13.1, 9.8 [C(5)]; 6.5, 6.3 [C(6)].
207Pb NMR: À575.3, À871.9.
m
(C@O); 1369 s, m(C–N); 1580 s, 1517 m, m(ring); 903 m, 760 w,
m
(C@S). 1H NMR: 11.59 s, 9.64 s [(4) N(1)H2]; 7.98 d (4) [HoPh2Pb],
[PbPh2(L6)2]. Colour: yellow. M.p.: 184 °C (d). Anal. Calc. for
C26H30N6O2S2Pb: C, 42.79; H, 4.14; N, 11.51; S, 8.78. Found: C,
42.41; H, 4.17; N, 11.28; S, 8.72%. MS (electrospray), m/z (%): 485
(100) [MÀ{L6+C(S)NH2}]; 407 (87) [PbMe(L6)]. IR (cmÀ1): 3414 w,
3J(1H–207Pb) = 208 Hz; 7.57 t (4) [HmPh2Pb]; 7.42 t (2) [HpPh2Pb];
4.60 s (2) [C(3)H]; 4.37 s (4) [C(5)H2]; 3.30 s (6) [C(6)H3]. 13C NMR:
175.7 [C(1)]; 167.3 [C(4)]; 157.6 [C(2)]; 132.7 [Co(Ph2Pb)]; 130.2
[Cm(Ph2Pb)]; 129.6 [Cp(Ph2Pb)]; 81.9 [C(3)]; 68.2 [C(5)]; 58.5 [C(6)].
207Pb NMR: À738.1.
m
(N–H); 1616 s,
m
m
(C@O); 1369 s,
m(C–N); 1586 h, 1518 m, m(ring);
967 m, 748 m,
(C@S). 1H NMR: 11.83 br s, 9.63 s [(4), N(1)H2];
[Pb(L5)2]. Colour: yellow. M.p.: 154 °C (d). Anal. Calc. for
C12H16N6O2S2Pb: C, 26.32; H, 2.94; N, 15.35; S, 11.71. Found: C,
26.14; H, 2.64; N, 15.24; S, 11.50%. 1H NMR: 11.82 s, 9.65 s [(4)
N(1)H2]; 2.08 s (6) [C(5)H3]; 1.61 s (6) [C(6)H3]. 13C NMR: 175.2
[C(1)]; 166.0 [C(4)]; 90.7 [C(3)]; 13.3 [C(5)]; 6.4 [C(6)].
7.87 d (4) [HoPh2Pb]; 7.55 t (4) [HmPh2Pb]; 7.43 m (2) [HpPh2Pb];
2.11 m (4) [C(6)H2]; 2.08 s (6) [C(5)H3]; 0.94 t (6) [C(7)H3]. 13C
NMR: 155.2 [C(2)]; 136.9–128.1 [Co–Cp(Ph2Pb)]; 104.6 [C(3)]; 15.0
[C(6)]; 14.7 [C(7)]; 13.4 [C(5)]. 207Pb NMR: À706.4.
[PbPh2(OAc)(L6)]. Colour: yellow. M.p.: 132 °C. Anal. Calc. for
C21H23N3O3SPb: C, 41.71; H, 3.83; N, 6.93; S, 5.30. Found: C,
41.03; H, 3.62; N, 6.34; S, 5.13%. IR (cmÀ1): 3138 m, 3055 m,
[PbPh2(L5)2] Á H2O. Colour: yellow. M.p.: 175 °C. Anal. Calc. or
C24H28N6O3S2Pb: C, 40.05; H, 3.92; N, 11.67; S, 8.91. Found: C,
40.63; H, 3.80; N, 10.9; S, 8.49%. IR (cmÀ1): 3411 m, 3071 w,
m(N–H); 1611 s,
m
(C@O); 1564 s, 1405 m, : 159);
m
(CH3COO), (
D
m
m
(N–H); 1645 s,
m
(C@O); 1367 s,
m
(C–N); 1576 m, 1518 m,
m
(ring);
1370 h, (C–N); 1585 h, 1521 s,
m
m
(ring); 938 w, 773 w, m(C@S).
992 m, 762 w,
m
(C@S). 1H NMR: 11.75 s, 9.76 s [(4) N(1)H2]; 7.81 (4)
1H NMR: 11.64 s, 9.71 s [(2), N(1)H2]; 7.81 d (4) [HoPh2Pb]; 7.60
m (4) [HmPh2Pb]; 7.46 m (2) [HpPh2Pb]; 2.11 m (2) [C(6)H2]; 2.02
s (3) [C(5)H3]; 1.81 s (3) [CH3COO]; 0.95 t, 0.97 t [(3) C(7)H3].
207Pb NMR: À869.5.
[HoPh2Pb], 3J(1H–207Pb) = 210 Hz; 7.56 (4) [HmPh2Pb]; 7.43 (2)
[HpPh2Pb]; 2.07 s, 2.00 s [(6) C(5)H3]; 1.63 s (6) [C(6)H3].
[Pb(OAc)(L5)]. See Ref. [2].
[PbPh2(OAc)(L5)]. Colour: yellow. M.p.: 138 °C (d). Anal. Calc. for
C20H21N3O3SPb: C, 40.67; H, 3.58; N, 7.11; S, 5.43. Found: C, 40.36;
H, 3.95; N, 6.52; S, 5.38%. MS (electrospray), m/z (%): 532 (18)
[M+HÀ(C(S)NH2)]; 485 (93) [M+HÀ{Ph+2CH3}]; 407 (100)
[MÀ{2Ph+2CH3}] ꢀ [Pb(OAc)(L5–2CH3)]. IR (cmÀ1): 3295 m, 3053
[PbPh2(OAc)(L7)]. Colour: yellow. M.p.: 146 °C. Anal. Calc. for
C21H23N3O3SPb: C, 41.71; H, 3.83; N, 6.93; S, 5.30. Found: C,
41.66; H, 3.74; N, 6.95; S, 5.38%. MS (electrospray), m/z (%): 578
(35) [M+HÀ(CH2CH3)]; 546 (100) [MÀ(OAc)]; 407 (18)
[MÀ{2Ph+(NHCH2CH3)] ꢀ [Pb(OAc)(L7–NHCH2CH3)]. IR (cmÀ1):
m,
m(N–H); 1631 s,
m
(C@O); 1559 m, 1401 m,
m(CH3COO), (
D
m:
3437 m, 3052 w,
(CH3COO), ( : 153); 1345m,
776 s,
(C@S). 1H NMR: 12.71 br s (2) [N(1)H2]; 7.81 d (4) [HoPh2Pb],
3J(1H–207Pb) = 208 Hz; 7.56
(4) [HmPh2Pb]; 7.41 (2)
m
(N–H); 1609 s,
m
(C@O); 1568 s, 1415 m,
158); 1368 m,
m(C–N); 1586 h, 1518 m,
m
(ring); 909 w, 750 h,
m
D
m
m
(C–N); 1580 h,
m
(ring); 947 m,
m
(C@S). 1H NMR: 11.72 bs, 9.74 br s [(2) N(1)H2]; 7.84 d (4)
m
[HoPh2Pb], 3J(1H–207Pb) = 204 Hz; 7.55 t (4) [HmPh2Pb]; 7.41 m
(2) [HpPh2Pb]; 2.03 s (3) [C(5)H3]; 1.82 s (3) [CH3COO]; 1.62 s (3)
[C(6)H3]. 13C NMR: 175.2, 174.3, [C(1)]; 167.7 [Cipso(Ph2Pb)]; 166.5,
165.6 [C(4)]; 159.7, 158.2 [C(2)]; 136.1–128.3 [Co–Cp(Ph2Pb)]; 95.5,
m
m
[HpPh2Pb]; 4.70 s (1) [C(3)H]; 3.50 br s (2) [C(5)H2]; 2.06 s (3)
[C(7)H3]; 1.84 s (3) [CH3COO]; 1.11 (3) [C(6)H3]. 13C NMR: 179.6
[CH3COO]; 174.4 [C(1)]; 167.5 [C(4)]; 167.1 [Cipso(Ph2Pb)]; 158.7

J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
1033
[C(2)]; 132.2 [Co(Ph2Pb)]; 130.1 [Cm(Ph2Pb)]; 129.7 [Cp(Ph2Pb)];
86.7 [C(3)]; 23.4 [CH3COO]; overlapped with the signal of DMSO–
d6 [C(5)]; 14.6 [C(6)]; 13.7 [C(7)].
d (4) [Ho(Ph2Pb)], 3J(1H–207Pb) = 113.2 Hz; 7.53 t (4) [Hm(Ph2Pb)],
4J(1H–207Pb) = 58.4 Hz; 7.37 m (2) [Hp(Ph2Pb)]; 7.35–7.05 m (4)
[C(8–11)H]; 4.10 q (0.75) [CH3OH]; 3.16 d (2.25) [CH3OH]; 2.19 s,
2.17 s [(3) C(12)H3]; 2.03 s, 1.98 s [(3) C(5)H3]; 1.74 s (3) [CH3COO].
13C NMR: 176.3 [C(1)]; 167.2 [C(4)]; 160.9 [Cipso(Ph2Pb)]; 157.7
[C(2)]; 136.4–125.2 [C(7–11)]; 136.3 [Co(Ph2Pb)], 2J(13C–207Pb) =
87.2 Hz; 129.6 [Cm(Ph2Pb)]; 128.9 [Cp(Ph2Pb)]; 48.6 [C(3)]; 17.8
[C(12)]; 16.9 [C(5)]. 207Pb NMR: À191.9, À670.9, À862.8.
[PbPh2(OAc)(TSC8)] Á 2MeOH. Colour: yellow. M.p.: 126 °C. Anal.
Calc. for C27H34N4O5SPb: C, 44.19; H, 4.67; N, 7.63; S, 4.37. Found:
C, 44.03; H, 4.62; N, 7.63; S, 4.00%. MS (electrospray), m/z (%): 611
(100) [MÀ(OAc)]; 407 (30) [PbPh2(HCOO)]. IR (cmÀ1): 3424 m,
3358 m, 3277 m, 3172 w, 3132 w, 3057 m,
(C@O); 1597 s, (C@N); 1566 sh, 1330 s,
1552 s, 1246 w, (NH–Ph); 1082 w, 872 w,
10.25, 10.15, 10.04 [(1), N(4)H]; 7.82
m(N–H); 1651 s,
m
m
m
(CH3COO), (
D
m
: 226);
The following crystals, which were suitable for X-ray diffrac-
tometry, were obtained from the mother liquors of the specified
reactions: [PbPh2Cl(L2)] (PbPh2(OAc)2/HTSC2 reaction, 1:1 molar
ratio, room temperature), [PbPh2(OAc)(L5)] Á MeOH (PbPh2(OAc)2/
TSC5 reaction, 1:1 molar ratio, under reflux), [PbPh2(OAc)-
(TSC8)] Á 2MeOH (PbPh2(OAc)2/HTSC8 reaction, 1:1 molar ratio,
room temperature), [PbPh2(OAc)(TSC10)] Á H2O (PbPh2(OAc)2/
HTSC10 reaction, 1:1 molar ratio, room temperature) and [PbPh2-
(OAc)(TSC11)] Á 0.75MeOH (PbPh2(OAc)2/HTSC11 reaction, 1:2
molar ratio, room temperature).
m
m
(C@S). 1H NMR:
d
(4) [HoPh2Pb],
3J(1H–207Pb) = 111.4 Hz; 7.55 (2) [C(7,11)H]; 7.52 t (4) [HmPh2Pb];
7.35 m (2) [HpPh2Pb]; 7.29 (2) [C(8,10)H]; 7.04 (1) [C(9)H]; 7.00 s
(2) [N(1)H2]; 4.09 m (2) [CH3OH]; 3.16 d (6) [CH3OH]; 1.98 s (3)
[C(5)H3]; 1.74 s (3) [CH3COO]. 13C NMR: 167.3 [C(4)]; 160.9 [Cip-
so(Ph2Pb)]; 155.3 [C(2)]; 138.9–119.2 [C7–11]; 136.3 [Co(Ph2Pb)],
2J(13C–207Pb) = 88.5 Hz;
129.6
[Cm(Ph2Pb)],
3J(13C–207Pb) =
111.4 Hz; 128.8 [Cp(Ph2Pb)]; 46.5 [C(3)]; 23.7 [CH3COO]; 18.5,
16.9 [C(3)]. 207Pb NMR: À294.5, À863.3.
[PbPh2(TSC9)2]. Colour: white. M.p.: 181 °C (d). Anal. Calc. for
C36H40N8O4S2Pb: C, 47.00; H, 4.38; N, 12.18; S, 6.97. Found: C,
46.86; H, 4.40; N, 12.12; S, 7.08%. MS (electrospray), m/z (%): 943
(13) [M+Na]; 867 (4) [M+H+NaÀ(Ph)]; 641 (100) [MÀ(TSC9)]. IR
2.5. X-ray crystallography
Crystal data for HTSC10, [PbPh2(OAc)(TSC10)] Á H2O, [PbPh2-
(OAc)(TSC11)] Á 0.75MeOH, [PbPh2Cl(L2)] and [PbPh2(OAc)(L5)] Á
MeOH were collected on a Nonius Kappa CCD (São Carlos Institute
of Physics, University of São Paulo), and data for [PbPh2-
(OAc)(TSC8)] Á 2MeOH were obtained on a Bruker SMART CCD-
1000 (RIAIDT, University of Santiago de Compostela). Structures
were solved using direct methods for the ligand and the Patterson
method for the complexes, followed by normal difference Fourier
techniques and refined using SHELXS-97 [9]. Data were corrected
for absorption by multi-scan [10] or SADABS [11]. All hydrogen atoms
were introduced in calculated positions. Molecular graphics were
obtained with ORTEP-3 [12], PLATON [13] and MERCURY [14]. Experimen-
tal details and crystal and refinement data are listed in Table 2.
(cmÀ1): 3439 w, 3408 w, 3338 m, 3301 m, 3189 m, 3051 m,
m
(N–
(NH–Ph);
(C@S). 1H NMR: 10.08 br s,
H); 1675 s,
m(C@O); 1602 s, m(C@N); 1542 s, 1254 s, m
1434m, d(OCH3); 1046 m, 897 w,
m
9.80 br s, 9.52 br s, 9.28 s [(2) N(4)H]; 8.00–7.00 m (10) [H(Ph2Pb)];
7.80–6.80 m (8) [C(8–11)H]; 3.81 s (6) [C(12)H3]; 2.15 s, 1.98 s, 1.94 s
[(6) C(5)H3]. 207Pb NMR: À294.5.
[PbPh2(OAc)(TSC9)]. Colour: white. M.p.: 162 °C (d). Anal. Calc.
for C26H28N4O4SPb: C, 44.63; H, 4.03; N, 8.01; S, 4.58. Found: C,
44.44; H, 4.26; N, 7.83; S, 4.41%. MS (electrospray) m/z (%): 641
(100) [MÀ(OAc)]; 518 (42) [MÀ{(OAc)+Ph+OCH3+CH3}]; 285 (55)
[PbPh]. IR (cmÀ1): 3437 w, 3404 m, 3380 m, 3300 m, 3189 m,
m
(N–H); 1674 s,
: 251); 1544 s, 1257 s,
897 w,
(C@S). 1H NMR: 9.55 br s, 9.29 br s [(1) N(4)H]; 7.88 m
m
(C@O); 1602 s,
m(C@N); 1581 s, 1330, m(CH3COO),
(D
m
m(NH–Ph); 1433 m, d(OCH3); 1024 m,
3. Results and discussion
m
(1) [C(11)H]; 7.80 d (4) [Ho(Ph2Pb)], 3J(1H–207Pb) = 112 Hz; 7.51 t
(4) [Hm(Ph2Pb)]; 7.35 t (2) [Hp(Ph2Pb)]; 7.03 m (2) [C(8,9)H]; 6.88
m (1) [C(10)H]; 3.81 s (3) [C(12)H3]; 3.83 s, 3.73 s, 3.63 s, 3.38 s
[(2) C(3)H2]; 2.00 s, 1.96 s [(3) C(5)H3]; 1.74 s (3) [CH3COO]. 13C
NMR: 166.9 [C(4)]; 160.6 [Cipso(Ph2Pb)]; 154.4 [C(2)]; 149–110 [C7–
11]; 136.1 [Co(Ph2Pb)], 2J(13C–207Pb) = 86.5 Hz; 129.3 [Cm(Ph2Pb)],
3J(13C–207Pb) = 111.2 Hz; 128.6 [Cp(Ph2Pb)]; 55.6 [C(12)H3]; 46.2
[C(3)]; 16.9 [C(5)]. 207Pb NMR: À294.5.
3.1. Syntheses and physical properties of the complexes
Diphenyllead(IV) reacts with TSCs derived from b-keto esters
through cyclization processes similar to those induced by Pb(II).
Differences in the complexes obtained (Table 1) can be related to
the apparently slightly higher tendency of PbPh22+ to form hetero-
leptic [PbPh2(OAc)(L)] compounds instead of the homoleptic
2+
[PbPh2(OAc)(TSC10)] Á H2O. Colour: yellow. M.p.: 148 °C. Anal.
Calc. for C26H30N4O5SPb: C, 43.51; H, 4.21; N, 7.81; S, 4.47. Found:
C, 43.99; H, 4.44; N, 7.69; S, 4.45%. MS (electrospray). m/z (%): 641
(100) [MÀ(OAc)]; 485 (32) [PbPh3(HCOO)+H]. IR (cmÀ1): 3410 m,
[PbPh2(L)2] type, suggesting a somewhat lower affinity of PbPh2
for the pyrazolonate anion than the Pb(II) cation. This lower affin-
ity is particularly evident in the reaction with HTSC1, which leads
to free pyrazolone (HL1) with the organometallic cation under all
of the conditions tested, whereas with Pb(II) the [Pb(L1)2] complex
is formed. However, the dephenylation reactions in which the
3351 m, 3284 m, 3052 m,
m
(N–H); 1646 s,
(CH3COO), ( : 249); 1552 s, 1237 s,
(NH–Ph); 1434 m, d(OCH3); 1032 m, 836 m,
(C@S). 1H NMR:
m(C@O); 1604 s,
m
m
(C@N); 1580 s, 1331 m,
m
Dm
2+
organometallic cation take part, which transform PbPh2 into
m
10.20 s, 9.90 s [(1) N(4)H]; 7.82 d (4) [Ho(Ph2Pb)], 3J(1H–207Pb) =
112.8 Hz; 7.52 t (4) [Hm(Ph2Pb)], 4J(1H–207Pb) = 58.4 Hz; 7.40 m
(2) [C(7,11)H]; 7.37 m (2) [Hp(Ph2Pb)]; 6.86 d (2) [C(8,10)H]; 3.70 s
(3) [C(12)H3]; 1.98 s, 1.96 s [(3) C(5)H3]; 1.73 s (3) [CH3COO]. 13C
NMR: 178.2 [C(1)]; 166.7 [C(4)]; 155.3–113.8 [C(7–11)]; 136.2
[Co(Ph2Pb)]; 129.7 [Cm(Ph2Pb)]; 129.0 [Cp(Ph2Pb)]; 55.2 [C(12)];
46.3 [C(3)]. 207Pb NMR: À294.3.
Pb(II), paradoxically contribute most to the differences between
the products obtained when these TSCs are cyclized in the pres-
2+
ence of PbPh2 and Pb(II) cations. Although these dephenylation
processes can give rise to lead(II) pyrazolonates, very often these
reactions are incomplete and lead to mixed compounds that are
very difficult to separate and identify. Similar but fully evolved
+
processes have previously been observed for the PbPh3 and
2+
[PbPh2(OAc)(TSC11)] Á 0.75MeOH. Colour: yellow. M.p.: 132 °C.
Anal. Calc. for C26.75H31N4O3.75SPb: C, 45.39; H, 4.41; N, 7.92; S,
4.53. Found: C, 44.83; H, 4.65; N, 7.53; S, 4.17%. MS (electrospray).
m/z (%): 625 (100) [MÀ(OAc)]. IR (cmÀ1): 3432 m, 3368 w, 3267 m,
PbMe2 cations in the presence of ferrocenyl TSCs [15] and these
results were related to the weakness of the Pb–C bonds [16]. It is
worth noting that, in some cases, a minimal amount of the hetero-
leptic complexes containing ClÀ ligands were also isolated, proba-
bly because the PbPh2(OAc)2 used in the reaction was
contaminated with some PbPh2Cl2 used in the synthesis of the for-
mer species (see Section 2).
3157 m, 3053 m,
m
(N–H); 1642 s,
(CH3COO), ( : 248); 1535 s, 1248 w,
(C@S). 1H NMR: 10.15 br s, 9.64 br s, 9.42 s [(1) N(4)H]; 7.82
m
(C@O); 1602 h,
m(C@N); 1577 s,
1329 s,
850 w,
m
m
D
m
m
(NH–Ph); 1016 m,

Table 2
Crystallographic data for ligand and complexes.
HTSC10
[PbPh2(OAc)(TSC8)] Á 2MeOH
[PbPh2(OAc)(TSC10)] Á H2O
[PbPh2(OAc)(TSC11)] Á 0.75MeOH
[PbPh2(OAc)(L5)] Á MeOH
[PbPh2Cl(L2)]
Empirical formula
Molecular weight
T (K)
C12H16N4O2S
280.35
140(2)
C27H34N4O5PbS
733.83
293(2)
C26H30N4O5PbS
717.79
140(2)
C26.75H31N4O3.75PbS
707.81
120(2)
C21H25N3O4SPb
622.69
120(2)
C22H18ClN3OPbS
615.09
120(2)
k (Å)
0.71073
triclinic
P1
0.71073
orthorhombic
Pna21
19.539(4)
9.7859(18)
14.957(3)
90
90
90
2859.9(9)
4
1.704
0.71073
monoclinic
P21/n
10.0550(2)
18.7710(6)
15.0200(4)
90
95.7340(10)
90
2820.73(13)
4
0.71073
orthorhombic
Pna21
19.4506(4)
10.0005(2)
14.9527(2)
90
0.71073
0.71073
monoclínico
P21/n
9.6303(8)
14.3190(10)
97.727(4)
90
15.9170(10)
90
2175.0(3)
4
Crystal system
Space group
a (Å)
b (Å)
c (Å)
triclínico
ꢀ
ꢀ
P1
4.864(6)
8.815(7)
16.657(15)
102.12(5)
90.76(7)
102.87(13)
679.40(12)
2
7.68970(10)
11.7006(2)
12.7776(3)
96.8530(10)
105.8530(10)
90.4740(10)
1097.02(3)
2
a
(°)
b (°)
90
90
c
(°)
V (Å3)
2908.54(9)
4
1.616
Z
Dcalc (Mg/m3)
1.370
0.242
1.690
6.096
1.885
7.817
1.878
7.994
l
(mmÀ1
)
6.015
5.908
F(000)
296
1448
1408
1390
604
1176
Crystal size (mm)
h range(°)
h; k; l range
Max. and Min. transmission
Measured reflections
Unique reflections
Rint
0.60 Â 0.40 Â 0.12
1.25–24.99
À3, 5; À10, 10; À19, 19
0.9715–0.8682
3086
0.27 Â 0.13 Â 0.11
2.33–28.28
0, 26; 0, 12; À9, 19
0.407–0.516
16806
0.06 Â 0.04 Â 0.02
1.74–25.00
À11, 11; À22, 22; À17, 17
0.715–0.544
16655
0.18 Â 0.17 Â 0.12
2.29–24.99
À23, 22; À11, 11; À17, 17
0.5374–0.4161
23250
0.30 Â 0.11 Â 0.05
3.20–27.53
À9, 9; À15, 15; 0, 16
0.6772–0.3730
10112
0.11 Â 0.08 Â 0.07
3.43–25.00
À11, 11; À15, 17; À18, 18
0.6046–0.4734
9774
2124
0.0749
4985
0.0392
4964
0.0659
5021
0.0748
5020
0.0683
3816
0.0958
R1 (I > 2rI)
0.1069
0.0258
0.0808
0.0438
0.0299
0.0512
wR2 (I > 2
rI)
0.2681
0.0492
0.1941
0.1142
0.0677
0.1148
Goodness-of-fit
1.038
1.054
1.204
1.077
1.072
1.021
Deposit no.
712077
712078
712079
712080
712081
712082

J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
1035
Table 4
Regarding the reactions of diphenyllead(IV) acetate with TSCs
Hydrogen bonds (Å, °) in ligand and complexes.
derived from b-keto amides, cyclization did not occur in any case
and only thiosemicarbazonates were isolated. Note that Pb(II)
forms the corresponding pyrazolonate with HTSC8, although not
with HTSC9 or HTSC10 [2]. Thus, if there is a relationship between
cyclization and ‘‘soft” character, then PbPh22+, although a ‘‘border-
line” ion, might be a little ‘‘harder” than Pb(II).
The complexes are all solids and are mostly yellow in colour.
The complexes are insoluble in water, soluble in DMSO and DMF
but only sparingly soluble in ethanol and acetone.
D–HÁÁÁA
HL10a
d(D–H)
d(HÁÁÁA)
d(DÁÁÁA)
<(DHA)
N(1)–H(1A)ÁÁÁN(3)
N(1)–H(1B)ÁÁÁSi
N(4)–H(4)ÁÁÁO(1)ii
0.88
0.88
0.88
2.27
2.66
2.02
2.638(11)
3.537(8)
2.884(10)
105.1
175.9
168.7
[PbPh2(OAc)(TSC8)] Á 2MeOHb
N(1)–H(1B)ÁÁÁO(4)i
N(4)–H(4)ÁÁÁO(2)ii
0.86
0.86
0.82
0.82
2.34
2.01
1.86
2.03
3.188(8)
2.843(6)
2.679(6)
2.841(9)
166.7
163.9
172.1
170.8
O(4)–H(4A)ÁÁÁO(3)
O(5)–H(5)ÁÁÁO(4)iii
3.2. X-ray studies
[PbPh2(OAc)(TSC10)] Á H2Oc
N(1)–H(1B)ÁÁÁO(1W)i
N(4)–H(4)ÁÁÁO(4)i
0.88
0.88
0.80
2.00
1.95
2.13
2.88(2)
2.827(19)
2.755(19)
173.6
174.1
136.1
3.2.1. HTSC10
O(1W)–H(12W)ÁÁÁO(3)ii
The atomic numbering scheme for this TSC ligand is shown in
Fig. 1 and selected bonds lengths and angles are listed in Table 3.
The structure shows some disorder that affects the atoms of the
ring [C(7), C(8), C(10) and C(11)], which are delocalized between
two equally populated positions.
The thiosemicarbazone chain adopts the E configuration around
the C(2)–N(3) and C(1)–N(2) bonds with the sulfur atom trans to
the N–N bond. The bonds lengths and angles are similar to those
previously found for this type of compound [17]. The atoms of
the molecule are distributed in two planes, SN(1)C(1)N(2)-
N(3)C(2)C(5)C(3) [rms = 0.0668] and C(4)N(4)C(6)C(7)C(8)C(9)-
[PbPh2(OAc)(TSC11)] Á 0.75MeOHd
N(1)–H(1A)ÁÁÁN(3)
N(1)–H(1B)ÁÁÁO(1S)i
O(1S)–H(1S)ÁÁÁO(2)
N(4)–H(4)ÁÁÁO(3)ii
0.88
2.34
2.07
1.92
1.95
2.645(13)
2.903(14)
2.712(13)
2.782(11)
100.7
156.8
157.8
156.1
0.88
0.84
0.88
[PbPh2Cl(L2)]e
N(1)–H(1A)ÁÁÁO
0.88
0.88
1.94
2.50
2.650(11)
3.355(9)
136.4
165.4
N(1)–H(1B)ÁÁÁClii
[PbPh2(OAc)(L5)] Á MeOHf
N(1)–H(1A)ÁÁÁO(1)
0.88
0.88
0.84
1.93
1.92
1.95
2.633(4)
2.783(5)
2.718(4)
135.6
166.9
151.1
N(1)–H(1B)ÁÁÁO(1S)ii
O(1S)–H(1S)ÁÁÁO(1)
C(10)C(11) [rms = 0.0976] which form
a dihedral angle of
a
76.94(0.42)°.
i: Àx + 1, Ày + 1, Àz; ii: x + 1, y, z.
b
c
d
e
f
i: Àx + 1/2, y À 1/2, z + 1/2; ii: Àx + 1/2, y À 1/2, z À 1/2; iii: x À 1/2, Ày + 3/2, z.
i: x À 1/2, Ày + 1/2, z À 1/2; ii: x, y, z + 1.
i: Àx À 1/2, y + 1/2, zÀ1/2; ii: Àx À 1/2, y + 1/2, z + 1/2.
ii: Àx + 3/2, y + 1/2, Àz + 1/2.
There is an intermolecular hydrogen bond [N(1)–H(1A)ÁÁÁN(3)]
that limits the free rotation of the –N(1)H2 group around the
N(1)–C(1) bond (see below) and there is also a weak intermolecu-
lar N(1)–H(1B)ÁÁÁSi interaction that associates the molecules into
pairs. Another intramolecular hydrogen bond [N(4)–H(4)ÁÁÁO(1)ii]
connects the pairs to give parallel chains along the a axis (Table
4, Fig. 1S).
ii: Àx, Ày, Àz + 1.
numbering schemes. Selected bonds lengths and angles are listed
in Table 5. The three structures include solvent molecules (MeOH
or H2O) in the lattice. In [PbPh2(OAc)(NSC10)] Á H2O, the water mol-
ecule is disordered over two positions with occupancies of
0.75:0.25. Only the molecule in the high-occupancy position has
been included in Table 4. This disorder is probably responsible for
the low quality of the collected data.
3.2.2. Complexes
The molecular structures of the complexes [PbPh2(OAc)-
(TSC8)] Á 2MeOH, [PbPh2(OAc)(TSC10)] Á H2O and [PbPh2(OAc)-
(TSC11)] Á 0.75MeOH are shown in Figs. 2–4 together with the
Fig. 1. Molecular structure of HTSC10
.
Table 3
Bond distances (Å) and angles (°) for HTSC10
.
S–C(1)
1.693(9)
C(1)–N(2)–N(3)
C(2)–N(3)–N(2)
N(1)–C(1)–N(2)
N(1)–C(1)–S(1)
N(2)–C(1)–S(1)
N(3)–C(2)–C(3)
C(2)–C(3)–C(4)
O(1)–C(4)–C(3)
118.6(7)
117.5(7)
117.3(8)
124.2(7)
118.6(7)
115.0(7)
111.3(7)
120.7(8)
O(1)–C(4)
N(1)–C(1)
N(2)–N(3)
N(2)–C(1)
N(3)–C(2)
C(2)–C(3)
C(3)–C(4)
1.239(10)
1.323(10)
1.403(10)
1.360(11)
1.295(11)
1.509(12)
1.545(11)
Fig. 2. Molecular structure of [PbPh2(OAc)(TSC8)] Á 2MeOH.

1036
J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
Fig. 3. Molecular structure of [PbPh2(OAc)(TSC10)] Á H2O.
Fig. 4. Molecular structure of [PbPh2(OAc)(TSC11)] Á 0.75MeOH (methanol have
As can be seen from the figures, in all three heteroleptic com-
plexes the diphenyllead(IV) cation is bound to a TSCÀ ligand and
to an anisobidentate acetate. The thiosemicarbazonate interacts
via its S, N(2) and O(1) donor atoms, with the last interaction prob-
ably being a weak one. Similarly, one of the lead–acetate bonds
[Pb–O(3)] seems to be even weaker than Pb–O(1) judging by the
bond distance (cf. 2.83–2.77 Å). If these weak Pb–O bonds are ta-
ken into account, then lead has a pentagonal bipyramidal coordi-
nation, with the donor atoms of both TSCÀ and AcOÀ ligands
equatorial and the carbon atom of the phenyl groups apical.
The deprotonation and coordination of the thiosemicarbazonate
to the metal give rise to some changes with respect to the structure
of the free YNSC8 and YNSC10 ligands [7a]. In both cases the bond-
ing to the metal increases the carbon–sulfur bond distances, sug-
gesting a thione to thiol evolution of the thioamide group. Also,
in order to achieve the coordination of O(4) along with that of S
and N(2), the ligands must change its conformation about the
C(2)@N(3) bond in the free state from E to Z.
been omitted for clarity).
The most conspicuous characteristic of these structures is the
N(2),S-coordination mode adopted by the TSCÀ anion in place of
the more usual N(3),S-coordination (see, e.g. Ref. [7b]). This leads
to a four-membered chelate ring (see Figs. 2–4) instead of the
five-membered ring that is formed when the thiosemicarbazonate
binds in the usual N(3),S-mode. The N(2),S-coordination, initially
observed in
a dimethylthallium complex [18], is now well
documented in more than thirty structures [19] and has been the
subject of some experimental and theoretical discussion [20].
Nevertheless, in the present context, the relevance of the
[PbPh2(OAc)(TSCn)] structures resides not in the unusual character
of the coordination mode of the TSCÀ ligand, but in the fact that the
involvement of the electron pair of N(2) in the bonding to the me-
tal prevents its participation in the nucleophilic attack on the
Table 5
Selected bond distances (Å) and angles (°) for thiosemicarbazonate complexes.
Bonda
[PbPh2(OAc)(TSC8)] Á 2MeOH
[PbPh2(OAc)(TSC10)] Á H2O
[PbPh2(OAc)(TSC11)] Á 0.75MeOH
Pb–C1
Pb–C2
Pb–O2
Pb–N2
Pb–S
Pb–O1
Pb–O3
S–C
2.185(5)
2.186(6)
2.419(4)
2.423(4)
2.6134(16)
2.617(4)
2.831(4)
1.736(7)
2.172(18)
2.164(17)
2.403(10)
2.473(16)
2.620(5)
2.647(12)
2.793(11)
1.736(18)
2.188(9)
2.188(10)
2.456(6)
2.445(7)
2.638(2)
2.634(6)
2.772(8)
1.737(9)
C(14)–Pb–C(20)
N(2)–Pb–S
O(2)–Pb–S
N(2)–Pb–O(1)
O(1)–Pb–O(3
O(2)–Pb–O(3)
154.3(2)
63.5(3)
77.79(10)
74.3(3)
96.09(13)
48.54(13)
C(21)–Pb–C(15)
N(2)–Pb–S(1)
N(2)–Pb–O(1)
O(4)–Pb–S(1)
O(3)–Pb–O(1)
O(3)–Pb–O(3)
157.5(7)
62.5(4)
73.4(5)
78.6(3)
96.3(4)
49.5(4)
C(21)–Pb–C(31)
N(2)–Pb–S
O(3)–Pb–S
O(3)–Pb–O(2)
O(1)–Pb–O(2)
N(2)–Pb–O(1)
157.7(4)
60.8(2)
80.14(18)
49.1(2)
92.8(2)
77.4(3)
a
S
1
2
3
O
2
N
Pb
O
2
1
O

J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
1037
C(O)R3 group and the subsequent ring formation (see Section 1, the
(II) ? [III] evolution).
It is interesting to compare these structures with that of
[Zn(NSC9)2] [7b]. In the zinc complex the ligand behaves in the
more usual way and exhibits N(3),S-coordination; there is also an
N(4)–HÁÁÁN(2) hydrogen bond that involves the N(2) electron pair
and the O(1) atom is located away from the metal centre, making
any Zn–O(1) interaction impossible. Thus, it seems that, as sug-
gested previously [21], small differences in weak interactions or
in the steric requirements of the packing may determine which
of the N(2),S- or N(3),S-coordination modes is adopted.
In the three complexes an intermolecular [N(4)–H(4)ÁÁÁOacetate
]
hydrogen bond (Table 4) associates the molecules into chains;
other bonds involving the solvent molecules (MeOH or H2O) link
these chains to form a layered network (Figs. 2S–7S).
Fig. 6. Asymmetric unit of [PbPh2Cl(L2)].
With respect to the complexes containing the cyclized ligand,
the arrangement of the dimers of [PbPh2(OAc)(L5)] Á MeOH is
shown in Fig. 5 and the asymmetric unit of [PbPh2Cl(L2)] is repre-
sented in Fig. 6. Both figures include a numbering scheme in keep-
ing with that used above for the uncyclized ligands. Selected bond
lengths and angles are listed in Table 6.
In the former complex, the metallic atom is coordinated to the S
and N(3) atoms of the monodeprotonated pyrazolone, to one oxy-
gen atom of the acetate group [Pb–O(2) = 2.343(3) Å] and, more
weakly, to the O(3)i (i = x, Ày + 1, Àz) atom belonging to an acetate
from a neighbouring molecule [Pb–O(3)i = 2.721(4) Å]. Thus, the
acetate is bis-monodentate and bridges between the two diphenyl-
lead(IV) units to give the dimeric arrangement displayed in Fig. 5.
The intramolecular PbÁÁÁO(3) distance in the monomer (3.08 Å) is
too long to represent a significant interaction.
The geometry around the metal is distorted octahedral and the
pyrazolonate shows, in comparison to the free ligand [22], the ex-
pected structural evolution [2]. The intermolecular hydrogen
bonds N(1)–H(1B)ÁÁÁO(1S)ii and O(1S)–H(1S)ÁÁÁO(1), involving the
solvent molecule and the amino and carbonyl groups of the LÀ li-
gand (see Table 4), link the dimers to form a chain (Figs. 8S and 9S).
In [PbPh2Cl(L2)] (Fig. 6) the monodeprotonated pyrazolone is
N(3),S-coordinated to one diphenyllead(IV) cation and O(1)-bound
to another, bridging between the metal centres and connecting the
molecules to form a chain (Figs. 10S and 11S). The Pb–O(1)i dis-
tance [2.581(7) Å] is shorter than that in [Pb(L7)2] [2.727(3) Å]
[2], in which two intermolecular PbÁÁÁO(1)x interactions also exist
but the repulsive effect of a stereochemically active lone electron
pair on Pb(II) also hinders the intermolecular approach. It is
remarkable that the adopted structure contains only bridging pyr-
azolonates but not bridging chlorides, thus confirming the signifi-
cant affinity of the diphenyllead(IV) cation with the oxygen donor
centres.
Table 6
Selected bond distances (Å) and angles (°) for pyrazolonate complexes.
Bonda
[PbPh2Cl(L2)]b
[PbPh2(OAc)(L5)] Á MeOHc
Pb–C(5)
Pb–C(6)
Pb–N(3)
Pb–S
Pb–O(2)
Pb–O(3)i
Pb–Oi
2.173(13)
2.171(12)
2.562(8)
2.686(3)
–
2.178(4)
2.166(4)
2.516(3)
2.7031(10)
2.343(3)
2.721(4)
–
–
2.581(7)
2.625(3)
1.704(11)
Pb–Cl
C–S
–
1.710(4)
C(31)–Pb–C(21)
N(3)–Pb–Oi
N(3)–Pb–S
Oi–Pb–Cl
164.6(4)
104.5(2)
70.35(18)
101.07(18)
84.15(9)
C(15)–Pb–C(9)
162.67(16)
72.72(8)
106.48(12)
70.33(8)
O(2)–Pb–S
O(2)–Pb–O(3)i
N(3)–Pb–S
Cl–Pb–S
N(3)–Pb–O(3)i
110.36(12)
a
2
3
C
C
4
3
N
C
C5
O
2
N
X
Pb
1
C
1
S
N
C
6
X= O, Cl
.
b
c
i: Àx + 3/2, y À 1/2, Àz + 1/2.
i: Àx, Ày + 1, Àz.
Fig. 5. Dimers of [PbPh2(OAc)(L5)] Á MeOH.

1038
J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
Once again the metal has octahedral coordination, with the
allation; (iii) the C(2) signal is displaced to lower field (by between
6 and 16 ppm) upon complexation, probably due to the bonding of
N(3) to the lead atom [7b].
main distortion caused by the C(21)–Pb–C(31) angle, which is
164.6(4)° rather than 180°, and the short N(3),S-bite of the ligand
[N(3)–Pb–S = 70.35(18)°], which clearly differs from the ideal 90°.
In the crystal lattice, the chains interact via the N(1)–H(1B)ÁÁÁClii
intermolecular hydrogen bond (Table 4) to give a layered arrange-
ment (Figs. 10S and 11S).
In cases where the signals of the organometallic moiety did not
overlap with the aromatic proton signals of the ligand, and there-
fore could be located, they showed chemical shifts that were very
similar in all the complexes and also 3J(1H–207Pb) values close to
112 Hz. In the 13C NMR spectra the 2J(13C–207Pb) coupling constants
are between 87 and 88 Hz. These values are lower than those ob-
tained for diphenyllead compounds with CN = 6 and even lower
than those with CN = 5 [24,25], which suggests that in these com-
pounds CN = 4. This low CN is also supported by the 207Pb chemical
shift (d = À294 ppm), which is identical in all compounds and is dis-
placed to lower field by almost 200 ppm with respect to the values
reported for other diphenyllead complexes with CN 6 or 5 [24,25].
All of these data suggest that the solid state structures of the
complexes [PbPh2(OAc)(TSCn)] (n = 8, 10 and 11), in which the me-
tal exhibits a CN = 7, are modified in DMSO solution to form species
in which the diphenyllead is probably only bound to the TSCÀ an-
ion via its S and N(3) atoms. If this is the case, it must be concluded
that the NMR parameters of the diorganolead moiety are sensitive,
as can been expected, to the CN of the metal and to the identity of
the donor atoms, but is rather insensitive to the donor strength of
these atoms.
3.3. IR spectroscopy
The most significant IR bands of the complexes are listed in Sec-
tion 2 and were assigned according to a previous study [2].
In the spectra of the thiosemicarbazonates [PbPh2(OAc)(TSCn)]
and [PbPh2(TSCn)2], the
m(C@N) vibration remains close to its posi-
tion in the spectra of the free ligands, which is consistent with N(3)
not participating in the coordination to the metal. However, the
(C@S) vibration is shifted to lower wavenumbers, as one would
m
expect if there is a thione to thiol evolution due to the formation
of a Pb–S bond. Thus, in this type of complex the TSCÀ ligand is
probably N(2),S-bound. The acetate mas(COO) and ms(COO) vibration
modes lie at positions in keeping with a general anisobidentate
OAcÀ coordination [23].
In the pyrazolonate complexes the position of the band associ-
ated with the m(C@S) changes upon metallation to lower wave-
number with respect to the free HLn, suggesting the coordination
of the sulfur atom to the metal in all of these pyrazolone com-
In the pyrazolonate complexes, the main changes in the 1H and
13C NMR spectra of the pyrazolone moiety regarding the free HLn
ligands are: (i) the absence of the signal associated with the
N(3)H group; (ii) the slight shielding of C(1) and (iii) the significant
deshielding of C(2). The former modification is a consequence of
the deprotonation of the ligand and the latter two suggest that
the S,N(3)–Pb bonding is retained in DMSO solution.
plexes. The behaviour of the m(C@N) mode is similar in all deriva-
tives (a shift to higher wavenumber with respect to the free
pyrazolone) and this is consistent with the coordination of N(3)
as in [PbPh2(OAc)(L5)] Á MeOH and [PbPh2Cl(L2)]. As indicated pre-
viously [7b], coordination of the oxygen atom of the carbonyl
group to the metal cannot be confirmed by the modification of
The values of the 3J(1H–207Pb) constants, in cases where they
could be observed, are in the range 204–210 Hz and this is consis-
tent with a CN of 6 or higher [24]. The limited availability of 207Pb
chemical shift data precludes any general conclusions, but this
parameter in the cases of [PbPh2(L3)2] (À738.1) and [PbPh2(L6)2]
(À706.4) also suggests a CN of 6 or higher [25–27]. However, the
chemical shift value in [PbPh2(OAc)(L6)] (À869.5) indicates that
during the acquisition of the spectrum this complex evolved to
give diphenyllead acetate. The complex [PbPh2(OAc)(L5)] shows
two signals, one at À575 and another at À871.9, and this under-
went a partial or total displacement of the AcOÀ ligand in solution
to give a new complex with a lower CN and PbPh2(OAc)2.
the band associated with m(C@O) because this mode is also sensi-
tive to the metallation of N(3) and to the changes in the hydrogen
bonding interactions involving the carbonyl group. Thus, in
[PbPh2(OAc)(L5)] Á MeOH this signal is shifted by approximately
30 cmÀ1 to lower wavenumbers with respect to its position in
HL5, although the X-ray study showed (Fig. 5) that the C@O group
is not involved in the coordination to the metal. However, in
[PbPh2Cl(L2)], in which an O(1)–Pb bond exists,
m(C@O) was shifted
to lower wavenumbers compared to the corresponding absorption
in HL2 and this shift was only marginally larger (ca. 40 cmÀ1).
As far as the acetate ligand in the heteroleptic [PbPh2(OAc)(Ln)]
complexes is concerned, the value of
Dm (@[mas(COO)– ms(COO)])
(150–170 cmÀ1) suggests a coordination behaviour similar to that
described for [PbPh2(OAc)(L5)] [23].
Acknowledgements
We thank the Secretariat General for Research and Develop-
ment of the Xunta de Galicia (Spain) and the Spanish Ministry of
Science and Technology for financial support under Projects PGI-
DIT03PXIC20306PN, CTQ2006-11805-BQU and BQU2002-04524-
C02-01.
3.4. 1H, 13C and 207Pb NMR spectra
The 1H, 13C and 207Pb NMR data for the complexes in DMSO–d6
solution are included in Section 2. The corresponding data for the
ligands HTSCn (n = 1–10) and HLn (n = 1–7) have been published
previously [3,7]. In cases where a long acquisition time was neces-
sary to obtain a spectrum, some of the complexes decomposed to
give a black precipitate (possibly PbS), benzene (as shown by
new signals at 7.35 and 128.3 ppm in the 1H and 13C NMR spectra,
respectively) and, in the case of heteroleptic complexes, diphenyl-
lead acetate (according to the observed 207Pb NMR signal at
À863 ppm). This phenomenon was not explored further.
Appendix A. Supplementary data
CCDC 712077, 712078, 712079, 712080, 712081 and 712082
contains the supplementary crystallographic data for HTSC10
,
[PbPh2(OAc)(TSC8)]Á2MeOH, [PbPh2(OAc)(TSC10)]ÁH2O, [PbPh2-
(OAc)(TSC11)]Á0.75MeOH, [PbPh2(OAc)(L5)]ÁMeOH and [PbPh2-
Cl(L2)], respectively. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.poly.2009.01.004.
In the 1H and 13C NMR spectra of the thiosemicarbazonate com-
plexes the signals belonging to the TSCÀ moiety change with re-
spect to those of the free ligand in the expected way: (i) that of
the N(2)H group disappears due to deprotonation; (ii) the two
bands associated with the –N(1)H2 group [2] evolve to give a broad
signal, in accordance with the free rotation of this group around
the N(1)–C(S) bond as a result of the HTSC deprotonation and met-

J.S. Casas et al. / Polyhedron 28 (2009) 1029–1039
1039
[13] A.L. Spek, PLATON 99,
A
Multipurpose Crystallographic Tool, University of
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