Diphenyllead(IV) chloride complexes with benzilthiosemicarbazones. The first bis(thiosemicarbazone) derivatives

Article abstract of DOI:10.1021/ic701490j

Reactions of diphenyllead(IV) chloride with benzil bis(thiosemicarbazone) (L¹H₆) and benzil bis(4-methyl-3-thiosemicarbazone) (L¹Me₂H₄) afforded the first complexes containing the diphenyllead(IV) moiety with bis-(thiosemicarbazone) ligands. The new complexes show diverse structural characteristics depending on the ligand and the working conditions. Complexes [PbPh₂Cl(L¹H ₅)]·3H₂O (1) and [PbPh₂Cl(L ¹Me₂H₃)] (3) are mononuclear species in which the ligands are partially deprotonated and the lead atom has a C ₂N₂S₂Cl environment in a distorted pentagonal bipyramid coordination geometry. Complex [PbPh(L¹Me₂H ₂)]₂·2H₂O (4) was also obtained, which contains two lead atoms in a binuclear structure with a C₂N ₂S₃ coordination sphere for each lead atom, since both dideprotonated ligands act as N₂S₂ chelate and as sulfur bridge. Reaction from L¹H₆, in the same conditions in which complex 4 was prepared, gave a mixture of products: the lead (II) complex [Pb(L¹H₄)]₂ (2) and [PbPh₃Cl] _n. Reactions with the cyclic molecules 5-methoxy-5,6-diphenyl-4,5- dihydro-2H-[1,2,4]-triazine-3-thione (L²H₂OCH₃) and 5-methoxy-4-methyl-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-thione (L²MeHOCH₃) were also explored. In all the complexes, the ligands are deprotonated. The complexes [PbPh₂(L²) ₂] (5) and [PbPh₂(L²MeOCH₃) ₂] (7) present the same characteristics. The X-ray structure of 5 shows a distorted octahedral geometry around the lead atom, with the ligand molecules acting as NS chelates, but the nitrogen bonded to the metal is different; one of the triazines shows a novel behavior, since the nitrogen atom of the new imine group formed is the one that is bonded to the lead center, being a good example of linkage isomerism. The complex [PbPh ₂Cl(L²)] (6), which was also isolated, could not be crystallized. All the complexes were characterized by elemental analysis, mass spectrometry, IR and ¹H, ¹³C, and ²⁰⁷Pb NMR spectroscopy and some of them by X-ray diffraction studies.

Full text of DOI:10.1021/ic701490j

Inorg. Chem. 2007, 46, 10434−10443
Diphenyllead(IV) Chloride Complexes with Benzilthiosemicarbazones.
The First Bis(Thiosemicarbazone) Derivatives
David G. Calatayud, Elena Lo´pez-Torres, and M. Antonia Mendiola*
Departamento de Qu´ımica Inorga´nica, UniVersidad Auto´noma de Madrid, Cantoblanco,
28049 Madrid, Spain
Received July 26, 2007
Reactions of diphenyllead(IV) chloride with benzil bis(thiosemicarbazone) (L1H6) and benzil bis(4-methyl-3-
thiosemicarbazone) (L1Me2H4) afforded the first complexes containing the diphenyllead(IV) moiety with bis-
(thiosemicarbazone) ligands. The new complexes show diverse structural characteristics depending on the ligand
and the working conditions. Complexes [PbPh2Cl(L1H5)] 3H2O (1) and [PbPh2Cl(L1Me2H3)] (3) are mononuclear
‚
species in which the ligands are partially deprotonated and the lead atom has a C2N2S2Cl environment in a distorted
pentagonal bipyramid coordination geometry. Complex [PbPh(L1Me2H2)]2·2H2O (4) was also obtained, which contains
two lead atoms in a binuclear structure with a C2N2S3 coordination sphere for each lead atom, since both
dideprotonated ligands act as N2S2 chelate and as sulfur bridge. Reaction from L1H6, in the same conditions in
which complex 4 was prepared, gave a mixture of products: the lead (II) complex [Pb(L1H4)]2 (2) and [PbPh3Cl]n.
Reactions with the cyclic molecules 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-thione (L2H2OCH3) and
5-methoxy-4-methyl-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-thione (L2MeHOCH3) were also explored. In all
the complexes, the ligands are deprotonated. The complexes [PbPh2(L2)2] (5) and [PbPh2(L2MeOCH3)2] (7) present
the same characteristics. The X-ray structure of 5 shows a distorted octahedral geometry around the lead atom,
with the ligand molecules acting as NS chelates, but the nitrogen bonded to the metal is different; one of the
triazines shows a novel behavior, since the nitrogen atom of the new imine group formed is the one that is bonded
to the lead center, being a good example of linkage isomerism. The complex [PbPh2Cl(L2)] (6), which was also
isolated, could not be crystallized. All the complexes were characterized by elemental analysis, mass spectrometry,
IR and 1H, 13C, and 207Pb NMR spectroscopy and some of them by X-ray diffraction studies.
Introduction
compound in nature from inorganic lead has been described.
On the other hand, there is no therapy for organolead
poisoning, the chelating agents used to reduce the burden of
other heavy metals are not effective against organolead.6 Due
to its environmental relevance, a renaissance of interest in
the coordination chemistry of lead has been observed in
recent years.7-14 The Pb-C bonds are rather weak, conse-
quently, organolead(IV) halides decompose at room tem-
The coordination chemistry of diorganolead derivatives
has long been known. However, today only a limited number
of structures of these complexes have been identified.1-4
Lead is one of the most common and important trace metals
in the environment; the past massive use of organolead
compounds in fuel as antiknock agents and the use of
inorganic lead in battery production, have caused a dramatic
increase in the presence of this element in the environment.5
Furthermore, some evidence for formation of alkyllead
(5) Hewitt, C. N.; Metcalfe, P. J. Sci. Total EnViron. 1989, 84, 211.
(6) Scha¨fer, S. G.; Davies, R. L.; Elsenhans, B.; Forth, W.; Schu¨mann,
K. In Toxicology; Marquardt, H., Scha¨fer, S. G., McClellan, R. O.,
Welsch, F., Eds.; Academic Press: San Diego, 1989.
(7) Holloway, C. E.; Melnick, M. Main Group Met. Chem. 1997, 20, 399.
(8) Claudio, E. S.; Godwin, H. A.; Magyar, J. S. Prog. Inorg. Chem. 2003,
51, 1.
(9) Casas, J. S.; Carcia-Tastende, M. S.; Sordo. J.; Taboada, C.; Tubaro,
M.; Traldi, P.; Vidarte, M. J. Rapid Commun. Mass Spectrom. 2004,
18, 1856.
(10) Olafsson, S. N.; Flensburg, C.; Andersenm P. Dalton Trans. 2000,
4360-4368.
(11) Casas, J. S.; Castellano, E. E.; Ellena, J.; Garc´ıa-Tasende, M. S.;
Sa´nchez, A.; Sordo, J.; Vidarte, M. J. Inorg. Chem. 2003, 42, 2584.
* To whom correspondence should be addressed. E-mail:
antonia.mendiola@uam.es.
(1) Harrison, P. G. In ComprehensiVe Organometallic Chemistry; Wilkin-
son, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press: Oxford,
1982; Vol. 2.
(2) Carcelli, M.; Corazzari, G.; Ianelli, S.; Pelizzi, G.; Solinas, C. Inorg.
Chim. Acta 2003, 353, 310.
(3) Parr, J Polyhedron 1997, 16, 551-566.
(4) Sigel, H.; Da, Costa, C. P.; Mart´ın, R. B. Coord. Chem. ReV. 2001,
219, 435-461.
10434 Inorganic Chemistry, Vol. 46, No. 24, 2007
10.1021/ic701490j CCC: $37.00
© 2007 American Chemical Society
Published on Web 10/16/2007

Diphenyllead(IV) Chloride Complexes
Scheme 1
perature, especially when exposed to light, although aryl
derivatives are somewhat more stable than alkyl deriva-
tives.1,15 The decomposition of dialkyllead dihalides involves
a redistribution reaction,
atom provided by one terminal amine in a coordination
polymer.17,18 In the methylmercury derivative, it shows an
original behavior, because it is only bonded to the metal ions
through the sulfur atoms in a binuclear structure.19 However,
the cyclic molecule L2H2OCH3 always acts as a monoanion;
in most of the complexes, it acts as an NS chelate and even
as bridge through the sulfur atom.20,21 As monodentate
through the sulfur atom has only been observed in the
mercury complexes.22 Moreover, the cyclic ligands are
unsymmetrical ambidentate system and can therefore, give
rise to linkage isomerism when they are coordinated in some
of the mentioned ways, but in the dimethyltin(IV) complex
[SnMe2(L2)2], both ligands are bonded by the sulfur and
amine nitrogen atoms.23 In this paper we report the structural
characterization of compounds formed by reaction of thio-
semicarbazone and 4-methyl-3-thiosemicarbazone derivatives
of benzil with diphenyllead(IV) chloride.
2R2PbX2 f R3PbX + RPbX3
followed by reductive elimination of RX from the unstable
monoorganolead derivative:
RPbX3 f PbX2 + RX
These reactions hinder the synthesis of diorganolead(IV)
complexes with anionic ligands; reactions with soft anionic
ligands lead very often to Pb(II) and R3Pb(IV) complexes
instead of to the diorganolead(IV) derivative.14,16
Following our interest in the coordination chemistry of
ligands derived from thiosemicarbazides with toxic metals
ions, we have explored the interaction of diphenyllead(IV)
chloride with ligands derived from thiosemicarbazide and
4-methyl-3-thiosemicarbazide with benzil: The bis(thiosemi-
carbazones) L1H6 and L1Me2H4 and the cyclic molecules
L2H2OCH3 and L2MeHOCH3 (Schemes 1 and 2). In previous
works, we have established the versatile behavior of L1H6,
which depends on the working conditions and the coordina-
tion preferences of the metal ions. In particular, L1H6 acts,
at least, as a N2S2 chelate and the complexes show different
grade of deprotonation, as well as a variety of structures.
Moreover, it can also act as bridge through a sulfur atom
yielding a dimer and even as chelate and bridge via a nitrogen
As far as we know, the reactions between PbPh2Cl2 and
thiosemicarbazones have only been previously investigated
using those [1+1] condensation products.11,12 We present in
this work the first complexes derived from bis(thiosemicar-
bazones). The new complexes were characterized by el-
1
emental analysis, mass spectrometry, IR and H, 13C, and
207Pb NMR spectroscopy and some of them by X-ray
diffraction studies.
Experimental Section
Physical Measurements. Microanalyses were carried out using
a Perkin-Elmer 2400 II CHNS/O Elemental Analyzer. IR spectra
in the 4000-400 cm-1 range were recorded as KBr pellets on a
(12) Casas, J. S.; Castellano, E. E.; Ellena, J.; Garc´ıa-Tasende, M. S.;
Sa´nchez, A.; Sordo, J.; Touceda-Varela, A. Inorg. Chem. Commun.
2004, 7, 1109.
(13) Casas, J. S.; Castellano, E. E.; Ellena, J.; Garc´ıa-Tasende, M. S.;
Sa´nchez, A.; Sordo, J.; Touceda, A. Z. Anorg. Allg. Chem. 2005, 631,
2247.
(14) Casas, J. S.; Castan˜o. M. V.; Cifuentes, M. C.; Garc´ıa-Monteagudo,
J. C.; Sa´nchez, A.; Sordo, J.; Touceda, A. J. Organomet. Chem. 2007,
692, 2234.
(15) Jensen, K. A. In Biological Effects of Organolead Compounds;
Grandjean, P., Grandjean, E. C., Eds.; CRC Press: Boca Raton, FL,
2000.
(17) Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J.; Souto Pe´rez, B. Inorg.
Chem. 2004, 43, 5222-5230 and references therein.
(18) Calatayud, D. G.; Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J.;
Procopio, J. R. Eur. J. Inorg. Chem. 2005, 21, 4401.
(19) Lo´pez-Torres, E.; Calatayud, D. G.; Mendiola, M. A.; Pastor, C. J.;
Procopio, J. R.; Z. Anorg. Allg. Chem. 2006, 632, 2471.
(20) Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J. Inorg. Chem. 2006,
45, 3103 and references therein.
(21) Calatayud, D. G.; Lo´pez-Torres, E.; Mendiola, M. A.; Procopio, J. R.
Z. Anorg. Allg. Chem. 2007, 633, 1925.
(22) Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J. Polyhedron 2006,
25, 1464.
(16) Haupt, H. J.; Huber, F.; Gmehling, J. Z. Anorg. Allg. Chem. 1972,
390, 31.
(23) Lo´pez-Torres, E.; Mendiola, M. A.; Pastor, C. J.; Procopio, J. R. Eur.
J. Inorg. Chem. 2003, 2711.
Inorganic Chemistry, Vol. 46, No. 24, 2007 10435

Calatayud et al.
Scheme 2
Jasco FT/IR-410 spectrophotometer. Fast atom bombardment mass
spectra were recorded on a VG Auto Spec instrument using Cs as
the fast atom and m-nitrobenzylalcohol (mNBA) as the matrix. 1H
and 13C NMR spectra were recorded on a spectrometer Bruker
AMX-300 using CDCl3, CD2Cl2, and DMSO-d6 as solvents and
TMS as internal reference. 207Pb NMR spectra were recorded in
the same spectrometer using CDCl3 and DMSO-d6 as solvents and
using absolutes references.24 13C CP/MAS NMR spectra were
recorded at 298 K in a Bruker AV400WB spectrometer equipped
with a 4 mm MAS NMR probe (magic-angle spinning) and obtained
using cross-polarization pulse sequence. The external magnetic field
was 9.4 T, and the sample was spun at 10-14 kHz, spectrometer
frequencies were set to 100.61 MHz. For the recorded spectra a
contact time of 4 ms were used and recycle delays of 4 s were
used. Chemical shifts are reported relative to TMS, using the CH
group of adamantano as a secondary reference (29.5 ppm).25
Synthesis. All reagents were obtained from standard commercial
sources and were used as received. Methanol, dried Scharlau (max
0.005% H2O), and dried dichloromethane by refluxing with CaH2
were used as solvents.
Benzil Bis(4-methyl-3-thiosemicarbazone),26 L1Me2H4. A solu-
tion of benzil (Bz) (1.503 g, 7.15 mmol) and 10 drops of HCl
(concd) in dry methanol (75 mL) was added to a solution of
4-methyl-3-thiosemicarbazide (4-MeTSC) (1.504 g, 14.30 mmol)
in dry methanol (125 mL) and HCl (concd) (1 mL). The solution
was stirred under reflux for 45 min. After cooling to room
temperature, the pale yellow precipitate formed was filtered off,
washed (cold dry methanol), and dried in vacuo. Yield 60%. Mp
224 °C. FAB+ (m/z): 385.2 ([M + 1]+, 80%), 769.6 ([2M + 1]+,
10%). 1H NMR (DMSO-d6, 300 MHz, 25 °C): δ 9.8 (2H, NH, s),
8.9 (2H, NH, q), 7.7 (4H, Ph, m), 7.4 (6H, Ph, m), 3.0 (6H, CH3,
d).1H NMR (CDCl3, 300 MHz, 25 °C): δ 8.5 (2H, NH, s), 7.8
(2H, NH, q), 7.7 (4H, Ph, m), 7.3 (6H, Ph, m), 3.3 (6H, CH3, d).
13C NMR (DMSO-d6, 300 MHz, 25 °C): δ 178.6 (CS), 140.4 (CN),
133.2, 130.3, 129.1, 126.8 (Ph), 31.5 (CH3); 13C CP/MAS NMR
(300 MHz, 25 °C): δ 177.2 (CS), 139.8 (CN), 130.6, 128.1, 124.7
(Ph), 32.1 (CH3). IR (KBr, cm-1): 3435, 3335(s) [ν(NH)], 1601(w)
[ν(CN)], 1546(s) [δ(HNC)], 845(w) [ν(CS)].
5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-
thione, L2H2OCH3.27,28 Selected spectroscopic data: FAB+ (m/
Benzil Bis(thiosemicarbazone), L1H6. It was prepared following
the procedure previously reported.17 Selected spectroscopic data:
1
z): 266 ([M - OCH3]+, 10%), 298 ([M + 1]+, 35%). H NMR
(CDCl3, 300 MHz 25 °C): δ 9.5 (1H, NH, s), 7.6 (2H, Ph, m), 7.4
(2H, Ph, m), 7.3-7.1 (6H, Ph, m), 6.9 (1H, NH, s), 3.4 (3H, OCH3,
s). 13C NMR (CDCl3, 300 MHz, 25 °C): δ 169.7 (CS), 142.4 (CN),
141.7, 133.7, 129.3, 126.5 (Ph), 83.2 (CNOR2), 50.7 (OCH3). 13C
CP/MAS NMR (300 MHz, 25 °C): δ 168.4 (CS), 146.0 143.4
(CN), 132.4, 131.3, 129.8. 127.0 (Ph), 85.4 (CNOR2), 53.4 (OCH3).
IR (KBr,cm-1): 3184(s) and 3131(s) [ν(NH)], 1608(w) [ν(CN)],
1550(s) [δ(NCS)], 846(w) [ν(CS)].
1
FAB+ (m/z): 357 ([M + 1]+, 100%), 714 ([2M + 1]+, 25%). H
NMR (DMSO-d6, 300 MHz, 25 °C): δ 9.8 (2H, NH, s), 8.6 (2H,
1
NH2, s), 8.3 (2H, NH2, s), 7.7 (4H, Ph, m), 7.4 (6H, Ph, m). H
NMR (CDCl3, 300 MHz, 25 °C): δ 8.8 (2H, NH, s), 7.6 (6H, Ph,
m), 7.4 (4H, Ph, m), 6.6 (2H, NH2, s), 6.0 (2H, NH2 s). 13C NMR
(DMSO-d6, 300 MHz, 25 °C): δ 179.1 (CS), 140.5 (CN), 133.1,
130.1, 128.9, 126.8 (Ph). 13C CP/MAS NMR (300 MHz, 25 °C):
δ 181.1 (CS), 142.9 (CN), 133.3, 132.4 130.1 (Ph). IR (KBr, cm-1):
3420, 3386, 3342, 3330, 3210, 3151(s) [ν(NH)], 1608(w) [ν(CN)],
1581(s) [δ(NH2)] and 848(w) [ν(CS)].
5-Methoxy-4-methyl-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-tri-
azine-3-thione, L2MeHOCH3.26 A solution of 4-MeTSC (1.05 g,
(26) Calatayud, D. G.; Escolar, F. J.; Lo´pez-Torres, E.; Mendiola, M. A.
HelV. Chim. Acta, in press.
(24) Harris, R. K.; Becker, E. D.; Cabral De Menezes, S. M.; Goodfellow,
R.; Granger, P. Pure Appl. Chem. 2001, 73, 1795.
(25) Bryce, D. L.; Bernard, G. M.; Gee, M.; Lumsden, M. D.; Eichele, K.;
Wasylishen, R. E. Can. J. Anal. Sci. Spect. 2001, 2, 46 and references
therein.
(27) Arquero, A.; Can˜adas, M.; Mart´ınez-Ripoll, M.; Mendiola, M. A.;.
Rodr´ıguez, A. Tetrahedron 1998, 11271.
(28) Franco, E.; Lo´pez-Torres, E.; Mendiola, M. A.; Sevilla, M. T.
Polyhedron 2000, 19, 441.
10436 Inorganic Chemistry, Vol. 46, No. 24, 2007

Diphenyllead(IV) Chloride Complexes
10 mml) in methanol (40 mL), a solution of 2M HCl (40 mL),
HCl (concd) (1 mL), and a solution of Bz (2.10 g, 10 mmol) in
methanol (200 mL) were added dropwise with strong stirring to
150 mL of methanol. After the completion of the addition of all
the reagents, the mixture was stirred for 4 days. The solution was
concentrated and a crystalline white solid was formed. The
precipitate was filtered off and dried in vacuo. Yield 80%. Mp 136
°C. FAB+(m/z): 280.2 ([M - OCH3]+, 13%), 312.2 ([M + 1]+,
100%), 622.5 ([2M + 1]+, 10%).1H NMR (DMSO-d6, 300 MHz,
25 °C): δ 12.3 (1H, NH, s), 7.5-7.2 (10H, Ph, m), 3.2 (3H, OCH3,
s), 2.9 (3H, NCH3, s). 1H NMR (CDCl3, 300 MHz, 25 °C): δ 9.5
(1H, NH, s), 7.6-7.1 (10H, Ph, m), 3.4 (3H, OCH3, s). 3.1 (3H,
NCH3, s). 13C NMR (DMSO-d6, 300 MHz, 25 °C): δ 171.7 (CS),
141.4 (CN), 139.9, 133.7, 129.3, 128.8, 128.3, 127.9, 126.8, 126.4
(Ph), 87.1 (CNOR2), 51.1 (OCH3), 33.3 (NCH3). 13C CP/MAS NMR
(300 MHz, 25 °C): δ 173.1 (CS), 146.1 (CN), 140.4, 135.1, 129.4,
1268.6, 126.6 (Ph), 87.8 (CNOR2), 52.0 (OCH3), 37.1 (CH3). IR
(KBr, cm-1): 3229(s) [ν(NH)], 1612(w) [ν(CN)], 1511(s) [δ(NCS)],
845(w) [ν(CS)].
[ν(CS)]. Data for [PbPh3Cl]n: IR (KBr, cm-1) 3057(m) [ν(CH)],
1597, 1576, 1496, 1486 1476, 1432 [ν(CC)], 757, 750, 731,720,
699, 691, [δ(CH)op].
[PbPh2Cl(L1Me2H3)] (3). A solution of L1Me2H4 (89 mg, 0.23
mmol) and LiOH·H2O (10 mg, 0.23 mmol) in methanol (25 mL)
was added over a suspension of diphenyllead(IV) chloride (100
mg, 0.23 mmol) in the same solvent (10 mL). The mixture was
stirred for 4 h, and then the yellow solid was filtered off and dried
in vacuo. Yield 77%. Mp 184 °C. Anal. Calcd for PbC30H29N6S2-
Cl: C, 46.20 H, 3.74; N, 10.80; S, 8.20. Found: C, 45.94; H, 3.72;
N, 10.68; S, 8.14. FAB+(m/z): 590.9 ([Pb(L1Me2H3)]+, 30%), 667.0
([PbPh(L1Me2H3)], 20%), 745 ([PbPh2(L1Me2H3)], 25%), 781.1 ([M
+ 1]+, 5%). 1H NMR (300 MHz, CD2Cl2, 25 °C): δ 8.3 (1H, NH,
s), 7.8-6.9 (22H, Ph+NH, m), 3.2 (6H, CH3, d). 13C CP/MAS
NMR (300 MHz, 25 °C): δ 177.8, 175.3 (CS), 167.3, 166.1 (PbPh),
146.4 and 145.6 (CN), 134.2, 132.8, 130.7, 129.9, 127.5 (Ph), 31.7
(CH3). 207Pb NMR (300 MHz, DMSO-d6, 25 °C): δ -196.9. IR-
(KBr, cm-1): 3386, 3340, 3271(s) [ν(NH)], 1543 and 1475(vs)
[thioamide II], 847(w) [ν(CS)].
[PbPh2(L1Me2H2)]2·2H2O (4). A solution of L1Me2H4 (89 mg,
0.23 mmol) and LiOH·H2O (20 mg, 0.48 mmol) in methanol (60
mL) was added over a suspension of diphenyllead(IV) chloride (100
mg, 0.23 mmol) in the same solvent (20 mL). Immediately, an
orange solution was formed, and then the solution was stirred for
6 h. An orange solid was separated by slow evaporation of the
solvent. Yield 53%. Mp 188 °C (dec). Anal. Calcd for Pb2C60-
H60N12S4O2: C, 47.29 H, 3.97; N, 11.03; S, 8.42. Found: C, 47.18;
H, 3.60; N, 10.92; S, 8.39. FAB+ (m/z): 591.2 ([Pb(L1Me2H3)]+,
70%), 667.1 ([PbPh(L1Me2H2)+1]+, 60%), 745.1 ([PbPh2(L1-
Me2H3)]+, 100%), 951.2 ([Pb2Ph2(L1Me2H3)]+, 13%), 1104.4 ([Pb2-
Ph4(L1Me2H)]+, 17%). 13C CP/MAS NMR (300 MHz, 25 °C): δ
176.9, 174.2, 171.3 (CS), 152.6, 146.3 (CN), 135.3, 132.8, 128.7,
127.7, 124.7, 121.8 (Ph), 28.5 (CH3). 207Pb NMR (300 MHz,
DMSO-d6, 25 °C): δ -610.8. IR (KBr, cm-1) 3424, 3384(s) ν(NH);
1560, 1518(s) [ν(CN)] + [thioamide II], 844, 816(w) [ν(CS)].
Brown-yellow crystals suitable for X-ray diffraction were obtained
from the mother liquor.
Synthesis of the Complexes. The complexes were obtained by
reacting PbPh2Cl2 and each ligand in dry methanol or dried
dichloromethane and in the presence of LiOH·H2O. In every case,
a 1:1 mole ratio was used. In the reactions with the bis-
(thiosemicarbazones), 1:1 and 1:2 ligand/LiOH·H2O mole ratios
were used.
Caution! Lead is a highly toxic cumulatiVe poison, and lead
compounds should be handled carefully.6
[PbPh2Cl(L1H5)]‚3H2O (1). To a solution of L1H6 (75 mg, 0.21
mmol) and LiOH·H2O (9 mg, 0.21 mmol) in methanol (20 mL)
was added a suspension of diphenyllead(IV) chloride (91 mg, 0.21
mmol) in methanol (10 mL). The mixture was stirred for 4 h, and
then the scarce solid was filtered off and dried in vacuo. From the
filtrate, yellow crystals suitable for X-ray analysis were obtained.
Yield 74%. Mp 197 °C. Anal. Calcd for PbC28H31N6S2ClO3: C,
41.70 H, 3.72; N, 10.42; S, 7.94. Found: C, 42.03; H, 3.76; N,
10.47; S, 7.87. FAB+(m/z): 563.1 ([Pb(L1H5)]+, 75%), 639.1
([PbPh(L1H5)]+, 25%). 717.2 ([PbPh2(L1H5)]+, 20%), 753.1 ([M
1
+ 1]+, 5%). H NMR (300 MHz, DMSO-d6, 25 °C): δ 9.1 (1H,
[PbPh2(L2)2] (5). To a solution of L2H2OCH3 (100 mg, 0.33
mmol) and LiOH·H2O (14 mg, 0.33 mmol) in methanol (10 mL)
was added a suspension of diphenyllead(IV) chloride (145 mg, 0.33
mmol) in methanol (20 mL). The mixture was stirred for 4 h at
room temperature. The yellow solid formed was filtered off, washed
with methanol and acetone, and dried in vacuo. Yield 70%. Mp
202 °C. Anal. Calcd for PbC42H30N6S2: C, 56.68; H, 3.37; N, 9.44;
S, 7.19. Found: C, 56.54; H, 3.36; N, 9.34; S, 7.12. FAB+ (m/z):
266.0 ([L2 + 1]+, 15%), 470.9 ([Pb(L2)]+, 25%), 626 ([PbPh2(L2)]+,
NH, s), 8.2-6.9 (20H, Ph, m), 6.3 (4H, NH, s). 13C NMR (DMSO-
d6, 300 MHz, 25 °C): δ 179.5 (CS), 141.0 (CN), 134.3, 133.6,
130.7, 129.3, 127.2 (Ph). 207Pb NMR (300 MHz, DMSO-d6, 25
°C): δ -193.3. 13C CP/MAS NMR (300 MHz, 25 °C): δ 172.2
(CS), 167.1, 162.5 (PhPb), 157.8, 152.2 (CN), 137.8, 133.9, 132.8,
130.9, 129.4, 12.6 (Ph). IR (KBr, cm-1): 3420, 3365, 3343, 3330,
3244, 3151(s) [ν(NH)], 1698, 1607(w) [ν(CN)], 1564, 1507, 1466,
1446(s) [thioamide II], 764(w) [ν(CS)].
1
58%), 813 ([M - Ph]+, 5%), 891.0 ([M + 1]+, 10%). H NMR
This complex was also obtained using DCM as solvent under
reflux for 6 h. The yellow solid was collected by filtration and
dried in vacuo.
(CDCl3, 300 MHz, 25 °C): δ 7.98 (4H, Ph, d), 7.34 (26H, Ph, m),
3J(207Pb-1H) ) 159.49. 13C NMR (CDCl3, 300 MHz, 25 °C): δ
175.1 (CS), 152.9, 156.2 (CN), 134.3, 131.4, 130.4, 129.7, 128.4
[Pb(L1H4)] (2). A solution of L1H6 (75 mg, 0.21 mmol) and
LiOH·H2O (18 mg, 0.42 mmol) in methanol (25 mL) was added
over a suspension of diphenyllead(IV) chloride (91 mg, 0.21 mmol)
in the same solvent (10 mL). The mixture was stirred at room
temperature for 4 h. The scarce yellow solid was filtered off and
the orange filtrate was partially concentrated until an orange-brown
solid (2) was formed. Finally, from the mother liquor afforded a
small amount of yellow crystals suitable for X-ray study that turned
out to be [PbPh3Cl]n. Data for complex 2: Mp 199 °C (dec). Anal.
Calcd for PbC16H14N6S2: C, 34.21; H, 2.49; N, 14.97; S, 11.40.
Found: C, 34.45; H, 2.69; N, 14.64; S, 11.20. FAB+ (m/z): 563
([Pb(L1H5)]+, 5%). 13C CP/MAS NMR (300 MHz, 25 °C): δ 175.9
(CS), 154.7, 150.6 (CN), 138.2, 129.5 (Ph). IR (KBr, cm-1) 3443,
33l3(s) [ν(N-H)], 1565, 1468, 1437(s) [thioamide II], 768(w)
2
(Ph), J(207Pb-13C) ) 109.50. 207Pb NMR (300 MHz, CDCl3, 25
°C) δ -211.58. 207Pb NMR (DMSO-d6, 300 MHz, 25 °C): δ
-315.30. IR (KBr, cm-1): 1578, 1565(w) [ν(CN)], 1499, 1486(s),
[δ(NCS)], 846, 819(w) [ν(CS)]. Recrystallization in acetone gave
yellow crystals suitable for X-ray analysis.
[PbPh2Cl(L2)] (6). To a suspension of L2H2OCH3 (100 mg, 0.33
mmol) and LiOH·H2O (14 mg, 0.33 mmol) in CH2Cl2 (20 mL)
was added a suspension of diphenyllead(IV) chloride (145 mg, 0.33
mmol) in the same solvent (20 mL). The mixture was stirred under
reflux for 12 h. Then, the mixture was filtered off and the filtrate
was partially evaporated until a yellow solid was formed. Yield
41%. Mp 105 °C. Anal. Calcd for PbC27H20N3SCl: C, 49.04; H,
3.03; N, 6.36; S, 4.84. Found: C, 49.47; H, 3.21; N, 6.43; S, 4.90.
Inorganic Chemistry, Vol. 46, No. 24, 2007 10437

Calatayud et al.
empirical absorption corrections (SADABS)29 to be applied using
multiple measurements of symmetry-equivalent reflections (ratio
of minimum to maximum apparent transmission: 0.534941 for
complex 1 and 0.270617 for complex 5). The unit cell parameters
were obtained by full-matrix least-squares refinements of 6865
reflections for complex 1, and 7488 for complex 5. The raw
intensity data frames were integrated with the SAINT program,
which also applied corrections for Lorentz and polarization effects.30
Table 1. Crystallographic Data for Complexes
compound
1
4
5
empirical formula C28H31ClN6O3PbS2
C
60H60N12O2Pb2S4
C
42H30N6PbS2
fw
806.35
298(2)
orthorhombic
Pbca
17.3952(2)
18.4260(2)
18.8946(2)
90
1523.88
150
monoclinic
P21/c
12.8952(2)
9.6592(2)
24.3891(5)
90
103.1671(8)
90
2957.98(10)
2
1.711
5.879
1496
890.03
100(2)
monoclinic
P21/c
14.0427(9)
9.7998(6)
26.4633(18)
90
94.238(2)
90
3631.8(4)
4
T (K)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (°)
The software package SHELXTL version 6.10 was used for space
group determination, structure solution, and refinement.31 The
structures were solved by direct methods (SHELXS-97),32 com-
pleted with difference Fourier syntheses, and refined with full-matrix
â (°)
90
90
γ (°)
V (Å3)
Z
6056.17(12)
8
1.769
13.271
3168
2
least-squares using SHELXL-97 minimizing ω(F0 - Fc2).2,34
D
calcd (Mg/m3)
1.628
10.416
1752
abs coeff (mm-1
)
Weighted R factors (Rw) and all goodness of fit, S, are based on
F2; conventional R factors (R) are based on F.33 All non-hydrogen
atoms were refined with anisotropic displacement parameters. All
scattering factors and anomalous dispersions factors are contained
in the SHELXTL 6.10 program library. The high quality of the
data set allowed that all hydrogen atoms were located by difference
maps and refined isotropically in all complexes. The crystal of
complex 4 was mounted on a glass fiber using perfluoropolyether
oil and cooled rapidly to 150 K in a stream of cold N2 using an
Oxford Cryosystem CRYOSTREAM unit. Diffraction data were
measured using an Enraf-Nonius Kappa CCD difractometer (graphite-
monocromated Mo KR radiation, λ ) 0.71073 Å). Intensity data
were processed using the DENZO-SMN package.34
F(000)
cryst size (mm3) 0.11 × 0.07 × 0.04 0.12 × 0.12 × 0.28 0.12 × 0.08 × 0.05
GOF on F2
1.026
1.0618
33974
7100
1.052
34438
6951
reflns collected 56642
independent
5853
reflns
[R(int) ) 0.0602] [R(int) ) 0.049]
[R(int) ) 0.0406]
R1 ) 0.0243
wR2 ) 0.0588
R1 ) 0.0257
wR2 ) 0.0596
final R indices
[I > 2σ(I)]
R indices
R1 ) 0.0308
wR2 ) 0.0714
R1 ) 0.0452
wR2 ) 0.0793
R1 ) 0.0313
wR2 ) 0.0357
R1 ) 0.0528
wR2 ) 0.0462
(all data)
largest diff. peak 1.544 and -0.660 1.270 and -1.340 1.275 and -0.773
and hole (e.Å-3
)
FAB+ (m/z): 266.0 ([L2 + 1]+, 30%), 472.1 ([Pb(L2)]+, 25%), 626.1
([PbPh2(L2)]+, 40%), 662.1 ([M + 1]+, 5%). 1H NMR (CDCl3, 300
MHz, 25 °C): δ 8.1 (4H, Ph, d), 7.5 (16H, Ph, m), J(207Pb-1H)
3
The structure of complex 4 was solved using the direct-methods
program SIR92b, which located all non-hydrogen atoms of the
complex.35 Subsequent full-matrix least-squares refinement was
carried out using the CRYSTALS program suite.36 Coordinates and
anisotropic thermal parameters of all non-hydrogen atoms were
refined. Examination of a difference Fourier map showed an isolated
peak of electron density, assumed to be the O atom of a molecule
of water. The NH hydrogen atoms were located in a difference
Fourier map and their coordinates and isotropic thermal parameters
subsequently refined. CH hydrogen atoms were positioned geo-
metrically after each cycle refinement. The hydrogen atoms of the
molecule of water could not be located, presumably as a result of
disorder. They have been omitted from the model but included in
calculations of the formula weight, etc.
) 162.1. 13C NMR (CDCl3, 300 MHz, 25 °C): δ 176.4 (CS), 158.5,
153.9 (CN), 136.3, 134.4, 131.9, 131.4, 130.9, 129.8, 28.5 (Ph),
2J(207Pb-13C) ) 113.92. 13C CP/MAS NMR (300 MHz, 25 °C):
δ 173.6 (CS), 157.5, 153.2 (CN), 133.6, 128.9 (Ph). 207Pb NMR
(CDCl3, 300 MHz 25 °C): δ -122.49. IR (KBr, cm-1): 1597,
1563(w) [ν(CN)], 1486, 1472 [δ(NCS)], 843, 817(w) [ν(CS)].
[PbPh2(L2MeOCH3)2] (7). A solution of L2MeHOCH3 (143 mg,
0.46 mmol) and LiOH·H2O (20 mg, 0.48 mmol) in CH2Cl2 (10
mL) was added over a suspension of diphenyllead(IV) chloride (100
mg, 0.23 mmol) in the same solvent (20 mL). The mixture was
stirred for 72 h. Then, the solid was filtered off and the filtrate
was partially evaporated until a yellow oil was formed. After
freezing at -195 °C, a yellow solid was formed. Yield 48%. Mp
106 °C. Anal. Calcd for PbC46H42N6S2O2: C, 56.25; H, 4.31; N,
8.56; S, 6.53. Found: C, 56.51; H, 4.43; N, 8.66; S, 6.59. FAB+
(m/z): 312.0 ([L2MeHOCH3 + 1]+, 85%), 518.0 ([Pb(L2MeOCH3)]+,
10%), 672 ([PbPh2 (L2MeOCH3)]+, 100%), 905.0 ([M - Ph]+,
10%), 983.1.0 ([M + 1]+, 2%). 13C CP/MAS NMR (300 MHz, 25
°C): δ 172.3 (CS), 140.5 (CN), 134.9, 128.5 (Ph), 87.8 (CNOR2),
51.3 (OCH3), 34.1 (NCH3). 207Pb NMR (300 MHz, DMSO, 25
°C): δ -771.56. IR (KBr, cm-1) 1615(w) [ν(CN)], 1564(m)
[δ(NCS)], 849(w) [ν(CS)].
CCDC 631459 for complex 1, 631460 for complex 4, and 631458
for complex 5 contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, U.K.; fax (international) +44-123/336-033; e-mail:
deposit@ccdc.cam.ac.uk].
(29) Sheldrick, G. M. SADABS Version 2.03, Program for Empirical
Absorption Corrections; Universita¨t Go¨ttingen: Go¨ttingen, Germany,
1997-2001.
(30) Sheldrick, G. M. SAINT+NT (Version 6.04) SAX Area-Detector
Integration Program; Bruker AXS: Madison, WI, 1997-2001.
(31) Sheldrick, G. M. SHELXTL (Version 6.10) Structure Determination
Package; Bruker AXS: Madison, WI, 2000.
(32) Sheldrick, G. M. SHELXS-97, Program for Structure Solution, Acta
Crystallogr. Sect. A 1990, 46, 467-473.
(33) Sheldrick, G. M SHELXL-97, Program for Crystal Structure Refine-
ment; Universita¨t Go¨ttingen: Go¨ttingen, Germany, 1997.
(34) Otwinowski, Z.; Monor, W. Processing of X-ray Diffraction data
Collected in Oscillating Mode; Carter, C. W., Sweet, R. M., Eds.;
Academic Press: New York, 1997; Vol. 276.
The reaction was carried out in the same conditions described
above but in methanol at room temperature and under reflux. In
both cases, there was not reaction and the reagents were recovered.
X-ray Crystallography. Crystal data, experimental details, and
refinement results are listed in Table 1. Single crystals of complexes
1 and 4 were isolated from the mother liquor of the reactions, and
crystals of 5 were obtained by recrystallization in acetone.
The crystals of compounds 1 and 5 were mounted on a glass
fiber and transferred to a Bruker SMART 6K CCD area-detector
three-circle diffractometer with a MAC Science Co., Ltd. rotating
anode (Cu KR radiation, λ ) 1.54178 Å) generator equipped with
Goebel mirrors at settings of 50 kV and 110 mA. X-ray data were
collected with a combination of six runs at different æ and 2θ
angles, 3600 frames. The substantial redundancy in data allows
(35) Altomare, A.; Cascarano, C.; Giacovasco, G.;. Guagliarde, A.; Burla,
M. C.; Polidsri, G.; Camalli, M. J. Appl. Crystallogr. 1994, 27, 435.
(36) Betteridge, P. W.; Cooper, J. R.; Cooper, R. I.; Prout, K.; Watkin, D.
J. CRYSTALS issue 12. J. Appl. Crystallogr. 2003, 36, 1487.
10438 Inorganic Chemistry, Vol. 46, No. 24, 2007

Diphenyllead(IV) Chloride Complexes
Results and Discussion
and some additional peaks corresponding to different frag-
ments. The spectrum of 2 only shows peaks corresponding
to fragments containing lead and the thiosemicarbazone,
which confirms the absence of phenyl rings on the coordina-
tion sphere of lead and indicates the reduction to lead(II).
The spectra of complexes 1 and 3 show the same fragmenta-
tion pattern, so they might present similar structures. The
same situation is observed in the spectra of complexes 5 and
7, so very close structures are expected. The FAB+ mass
spectrum of 4 shows a different fragmentation pattern and
the molecular mass peak is not observed, but a peak at 1104.4
uma appears corresponding to [Pb2Ph4(L1Me2H)]+, which
suggests a binuclear structure.
IR Spectroscopy. The Experimental Section lists the main
IR bands of the ligands and their complexes. The absence
of any bands in the 2600-2800 cm-1 region in all complexes
suggests the absence of any thiol tautomer.38 The spectra
also show the bands corresponding to the PbPh2 moieties,
except in complex 2.
Synthesis of the Complexes. All the reactions were
performed by mixing a suspension of PbPh2Cl2 with a
solution of the corresponding ligand in the same solvent in
a 1:1 ratio, except the reaction with L2MeHOCH3, in which
a 1:2 ratio was necessary. Reactions were carried out in dry
methanol or DCM previously dried due to the presence of
water in the solvents leading to the partial decomposition of
the complexes. The best results were obtained working in
the presence of basic media. The variation of the ratio ligand/
lithium hydroxide, gave two kind of complexes: working
in a 1:1 ratio, complexes 1 and 3 are obtained, in which the
monodeprotonated ligand has displaced one of the two
chlorides from the coordination sphere of the metal. How-
ever, complex 4, with the ligands acting as dianion by the
loss of the two hydrogens of the acidic amine group, is
isolated working in a 1:2 ratio. Complexes 1 and 4 are the
first diphenyllead(IV) complexes containing a bis(thiosemi-
carbazone) ligand that have been structurally characterized.
The reaction of PbPh2Cl2 with L1H6 in the presence of 2
mol of LiOH·H2O gave several compounds. In the first
compound formed (2), the dideprotonated ligand has dis-
placed both chlorides and the phenyl groups from the
coordination sphere of the metal, giving a complex whose
empirical formula corresponds to [Pb(L1H4)]. Its analytical
data and spectroscopic characteristics correspond to the
complex obtained by reaction of lead (II) nitrate with benzil
bis(thiosemicarbazone), whose MALDI spectrum showed a
peak at 770.2 amu corresponding to [Pb2(L1H4)]+.37 The
crystal structure of the cadmium complex with the same
empirical formula consists of a binuclear compound with
the ligand acting as N2S2 chelate and sulfur bridge.17
Therefore, the same structure could be expected for the lead
complex. From the mother liquor, an unexpected compound
without L1H6 [PbClPh3]n is isolated. The former seems likely
to have been originated from a phenyl transfer, since it is
known that the organolead(IV) compounds undergo dispro-
portionation reactions and transfer of the organic group
yielding Pb(II) complexes.13,33 The phenyl transfer reactions
seem to be favored in the presence of basic media and when
terminal NH2 groups are present in the thiosemicarbazone
ligand.
In the spectra of complexes from the open-chain ligands
(1-4), the number of bands corresponding to ν(N-H)
vibrations has decreased owing to deprotonation and dis-
placement, probably due to the intermolecular hydrogen
bonding having been modified. The shifts observed in the
bands assigned to ν(CN) and ν(CS) are consistent with both
groups bonded to the lead atom in all the complexes.
In the complexes from the triazine ligands (5-7), there
are no bands in the 3000-3300 cm-1 region, indicating the
absence of N-H bonds. In all the complexes, the coordina-
tion through the sulfur atom can be observed in a decrease
of the ν(CS) frequency. In addition, in complexes from L2H2-
OCH3 (5 and 6), a new signal attributable to a CN double
bond, due to the loss of a methanol molecule in each ligand,
is observed in the IR spectra.
1
NMR Spectroscopy. The H NMR spectra of all the
complexes indicate that the ligands are deprotonated. Spectra
of complexes 1 and 3 show the loss of one hydrogen atom
from one of the acidic amine groups. However, the spectrum
of complex 4 agrees with both L1Me2H4 molecules being
dideprotonated and they have displaced the two chloride
atoms from the coordination sphere of each metal. In the
13C NMR spectrum of complex 1, the signals lie at the same
position than in the free L1H6. 207Pb NMR spectra in DMSO
of complexes 1 and 3 show one signal at -193.3 and -196.9
ppm, respectively. These values suggest that both complexes
have the same coordination number in DMSO solution and
they agree with a coordination number lower than six.39
Therefore, some Pb-L bonds could break in DMSO solution.
However, the spectrum of complex 4 shows a signal in the
range expected for a coordination number of six.40
In the reactions with the cyclic molecules, the solvent used
is an important factor: the analytical data of the two
complexes from L2H2OCH3 indicate the loss of a methanol
molecule, although they show different formula depending
on the solvent. In methanol, a 1:2 complex (5) is obtained,
while working in DCM only one deprotonated ligand has
displaced one of the two chlorides from the coordination
sphere of the metal, giving a complex whose empirical
formula is [PbPh2Cl(L2)] (6). An even greater importance is
observed in the reaction with L2MeHOCH3, which progresses
only working in DCM giving complex 7.
1
In the H NMR spectrum of complex 5, there are no
signals corresponding to the methoxy group and the N-H,
The FAB+ mass spectra of complexes 1, 3, 5, 6, and 7
show the molecular mass peaks, which show the appropriate
isotope distribution patterns, confirming the proposed formula
(38) Fenton, D. E.; Cook, D. H. J. Chem. Soc., Chem. Commun. 1977,
714.
(39) Schu¨merman, M.; Huber, F. J. Organomet. Chem. 1997, 530, 121-
130.
(40) Weber, D.; Hausner, S. H.; Eisengra¨ber-Pabst, A.; Yun, S.; Krause-
Bauer, J. A.; Zimmer, H. Inorg. Chim. Acta 2004, 357, 125 and
references therein.
(37) Lo´pez-Torres, E.; Ph.D. Thesis, Universidad Auto´noma de Madrid,
Spain, 2004.
Inorganic Chemistry, Vol. 46, No. 24, 2007 10439

Calatayud et al.
Figure 1. Molecular structure of complex [PbPh2Cl(L1H5)]‚3H2O (1), with thermal ellipsoids shown at 50% probability. Selected bond lengths (Å) and
angles (deg): Pb(1)-C(17) 2.190(4), Pb(1)-C(23) 2.193(4), Pb(1)-N(3) 2.584(4), Pb(1)-Cl(1) 2.6645(11), Pb(1)-S(1) 2.7056(11), Pb(1)-N(4) 2.757(4),
Pb(1)-S(2) 2.9810(11), C(1)-N(2) 1.330(6), C(1)-N(1) 1.335(6), C(1)-S(1) 1.743(5), C(2)-N(3) 1.304(6), C(2)-C(3) 1.488(6), C(3)-N(4) 1.294(6),
C(4)-N(6) 1.322(6), C(4)-N(5) 1.362(6), C(4)-S(2) 1.693(4), N(2)-N(3) 1.375(5), N(4)-N(5) 1.365(5). C(17)-Pb(1)-C(23) 168.25(17), C(17)-Pb(1)-
N(3) 94.40(14), C(23)-Pb(1)-N(3) 83.12(14), C(17)-Pb(1)-Cl(1) 92.16(12), C(23)-Pb(1)-Cl(1) 94.97(13), N(3)-Pb(1)-Cl(1), 154.45(9), C(17)-Pb(1)-
S(1) 96.31(12), C(23)-Pb(1)-S(1) 93.49(12), N(3)-Pb(1)-S(1) 68.74(8), Cl(1)-Pb(1)-S(1) 86.01(4), C(17)-Pb(1)-N(4) 75.76(14), C(23)-Pb(1)-N(4)
93.09(14), N(3)-Pb(1)-N(4) 61.13(11), Cl(1)-Pb(1)-N(4), 144.30(8), S(1)-Pb(1)-N(4) 128.12(8), C(17)-Pb(1)-S(2) 87.42(12), C(23)-Pb(1)-S(2)
84.46(4), S(1)-Pb(1)-S(2) 169.90(3), N(4)-Pb(1)-S(2) 61.89(8).
in agreement with the deprotonation of the ligand. The
spectrum of complex 6 is very similar to that of complex 5,
so the ligand has also lost the methoxy group and the amine
nitrogen atom. The coupling constants corresponding to the
organometallic moiety 3J(207Pb-1H) are 159 and 162.1 MHz,
respectively. These values are smaller than those for a
coordination number of six, suggesting that in solution the
coordination number is five or even four.11-13 The 207Pb
chemical shifts are also coherent with a coordination number
smaller than six,39 suggesting that some bonds have been
broken in solution.
complex 6 in CDCl3 shows a signal at -122.5 ppm, which
is in the range of a coordination number of four. These NMR
data indicate that one of the Pb-L bonds must be broken in
solution, as happened in the organotin derivatives with this
ligand.23 The signal in the spectrum of complex 7 (-771.6
ppm) is the highest observed in our compounds and agrees
with the solvent being coordinated to the lead atom.
13C CP/MAS NMR spectra were also recorded for all the
complexes. The shifts observed confirm the N2S2 coordina-
tion for both open-chain ligands. In addition, the number of
signals agrees with the asymmetry proposed in complexes 1
and 3, in which the ligands has only displaced one chloride
ion, or in those in which the ligands also act as bridge through
the sulfur atoms, complexes 2 and 4.
The spectra of all L2H2OCH3 derivatives support the loss
of a methanol molecule. In all the complexes obtained from
the cyclic ligands, the shifts observed in the thioamide carbon
confirm that the sulfur atom is bonded to the lead.
Solid-State Structures. Crystallographic data for the
structures solved are given in Table 1. The structures of
complexes 1 and 3 are, as far as we know, the first examples
of organolead(IV) complexes containing a bis(thiosemicar-
bazone), and they state the importance of the substitution in
The changes observed in the 13C NMR spectra of
complexes 5 and 6 with respect to the free L2H2OCH3 agree
with a NS coordination of the ligand; the presence of several
signals in the range of the imine carbons in the spectrum of
complex 5 suggests two kinds of coordination modes for the
2
ligands. The values of J(207Pb-13C) are 109.5 and 113.9
MHz, respectively, close to those observed in a coordination
number of five. The 207Pb NMR shift for complex 5 was
observed at -211 or at -315 ppm in CDCl3 or DMSO
solution, respectively. These values are also coherent with a
coordination number smaller than six and with the DMSO
coordinated to the lead atom. The 207Pb NMR spectrum of
10440 Inorganic Chemistry, Vol. 46, No. 24, 2007

Diphenyllead(IV) Chloride Complexes
the terminal amine group. The structure of 5 is the first
complex containing two triazine thione ligands showing
linkage isomerism.
The crystal structure of complex 1 is made up of [PbPh2-
Cl(L1H5)] units with three molecules of water held together
in the crystal packing by hydrogen bonds. The molecular
structure of 1 is shown together with the numbering scheme
and selected bond lengths and angles in Figure 1. The
coordination sphere of the lead atom is formed by the two
sulfur atoms and the two imine nitrogen atoms from the
benzil bis(thiosemicarbazonate) ligand, one Cl, and two
phenyl groups. The geometry around the metal can be
described as a distorted pentagonal bipyramid with the phenyl
groups being axial, whose C-Pb-C angle, 168.27(17)°,
differs from the ideal 180°, and the lead atom on the
equatorial plane defined by S, N, N, S, and Cl. In all the
complexes previously published, this ligand can be consid-
ered planar,17 but in this complex is strongly twisted, with
one sulfur atom above the least-squares plane and the other
under, which could be induced by the presence of chloride
and phenyls bonded to the lead atom. The pseudomacrocyclic
coordination mode of the ligand affords three five-membered
chelate rings. The asymmetric behavior of the thiosemicar-
bazone branches, due to the presence of the hydrogen atom
of a secondary amine in only one thiosemicarbazone moiety,
is reflected on the values of the bond distances of the ligand
backbone. In addition, two different Pb-S distances are
observed. The one corresponding to the neutral branch,
2.9810(11) Å is longer than the anionic one, 2.7056(11) Å,
suggesting that the neutral is less basic than the deprotonated
one or the presence of an additional electrostatic attraction
in the anionic part of the ligand. Similar differences between
both arms are observed in the Pb-N bonds; one distance in
the neutral one is 0.173 Å longer than in the anionic one.
The C(1)-S(1) distance in the deprotonated thiosemicarba-
zone is 0.05 Å larger than in the non-deprotonated one and
is consistent with a bond order close to one. This difference
is the greatest observed in complexes from L1H6.18 The
C(3)-N(4) and C(2)-N(3) distances show the same differ-
ences. These data confirm there is extensive conjugation
within the ligand, which is greater in the deprotonated
thiosemicarbazone branch. The Pb-Cl distance, 2.6645(11)
Å, is shorter than in other thiosemicarbazones complex with
close geometry.11 Remaining bond distances and angles are
similar to those found in related complexes and do not
deserve further comments. Finally, the molecules are held
together in the crystal packing through an extended network
of intermolecular hydrogen bonds involving the primary
amine groups, S(2) and N(2) atoms, and the oxygen atom
from the water molecules (see Figure 2 and Table 2) and
through π-π interactions between the phenyl groups.
Figure 3 shows the molecular structure, numbering, and
selected bond lengths and angles of the adduct 4. The
compound is a centrosymmetric dimer in which each lead
atom is coordinated to two sulfur and two nitrogen atoms of
the benzil bis(thiosemicarbazonate), two phenyl carbon
atoms, and also to one of the sulfur atoms of a second bis-
(thiosemicarbazonate) ligand. The coordination geometry of
Figure 2. Plot including the hydrogen bonds in complex 1.
Table 2. Hydrogen Bonds (Å, deg) in Complex 1a
D-H‚‚‚A
d(D-H)
d(H‚‚‚A) d(D‚‚‚A)
(DHA)
N(1)-H(1A)‚‚‚S(2)#1 0.86
N(1)-H(1B)‚‚‚O(1)#1 0.86
N(6)-H(6B)‚‚‚N(2)#2 0.86
2.52
2.36
2.24
2.40(3)
3.380(4)
3.080(6)
3.073(5)
3.110(7)
173.6
142.0
164.5
140(4)
N(5)-H(5)‚‚‚O(2)#3
0.862(19)
a Symmetry transformations used to generate equivalent atoms: #1 -x
+ 3/2, y - 1/2, z; #2 -x + 3/2, y + 1/2, z; #3 x + 1/2, y, -z + 1/2.
the metal may be regarded as a distorted pentagonal
bipyramid in which the axial positions are occupied by the
phenyl ligands with a deviation from the linearity of the
C-Pb-C angle of only 5°. As in complex 1, the ligand is
twisted, although the distortion in this case is much smaller
since there is no chloride bonded to the metal. The Pb-S
bonds, 2.8040(12) and 2.8006(12) Å, are intermediate
between those observed in the thiosemicarbazone and thi-
osemicarbazonate branches in complex 1. The C(1)-S(1)
distance (sulfur bridge) is longer than the corresponding to
the monodentate sulfur atom and both are larger than in the
free ligand (1.676(3) Å).26 The weakening of this bond allows
an additional bond with another lead atom to form the
dimeric unit. The C-N distances are longer than in L1-
26
Me2H4 and similar to that distance observed in the
thiosemicarbazonate branch in complex 1. Bond lengths
agree with a considerable electronic delocalization through
the 4-methyl-3-thiosemicarbazonate backbones, which is
Inorganic Chemistry, Vol. 46, No. 24, 2007 10441

Calatayud et al.
Figure 3. Molecular structure of complex [PbPh2(L1Me2H2)]2·2H2O (4), with thermal ellipsoids shown at 40% probability. Selected bond lengths (Å) and
angles (deg): Pb(1)-S(1) 2.8046(12), Pb(1)-S(1)#1 3.2577(11), Pb(1)-N(2) 2.443(4), Pb(1)-N(3) 2.429(4), Pb(1)-S(2) 2.8006(12), Pb(1)-C(19) 2.185(5),
Pb(1)-C(25) 2.199(5), S(1)-C(1) 1.740(5), C(1)-N(1) 1.323(6), C(1)-N(5) 1.355(6), C(2)-C(3) 1.496(6), C(3)-N(3) 1.309(6), C(4)-N(4) 1.339(6),
C(4)-S(2) 1.721(5), C(4)-N(6) 1.354(6), C(5)-N(5) 1.452(7), C(18)-N(6) 1.449(7), N(1)-N(2) 1.375(5), N(3)-N(4) 1.357(5). S(1)-Pb(1)-S(1)# 67.27(4),
S(1)-Pb(1)-N(2) 69.31(9), S(1)-Pb(1)-N(2) 136.26(9), S(1)-Pb(1)-N(3) 137.08(9), S(1)#-Pb(1)-N(3) 155.40(9), N(2)-Pb(1)-N(3) 68.34(12), S(1)-
Pb(1)-S(2) 151.95(3), S(1)#-Pb(1)-S(2) 84.87(3), N(2)-Pb(1)-S(2) 138.73(9), N(3)-Pb(1)-S(2), 70.58(9), S(1)-Pb(1)-C(19) 87.37(11), S(1)#-Pb(1)-
C(19) 88.77(12), N(2)-Pb(1)-C(19) 94.29(15), N(3)-Pb(1)- C(19) 89.11(14), S(2)-Pb(1)-C(19) 88.83(12), S(1)-Pb(1)-C(25) 93.89(12), S(1)#-Pb(1)-
C(25) 86.94(12). Symmetry transformations used to generate equivalent atoms: #1, -x + 1, -y + 1, -z + 1.
Figure 4. Molecular structure of complex [PbPh2(L2)2] (5), with thermal ellipsoids shown at 50% probability. Selected bond lengths (Å) and angles (deg):
Pb(1)-C(37) 2.189(2), Pb(1)-C(31) 2.194(2), Pb(1)-S(1) 2.5763(6), Pb(1)-S(2) 2.5868(6), Pb(1)-N(1) 2.795(2), Pb(1)-N(4) 2.805(2), C(1)-N(2) 1.342(3),
C(1)-N(1) 1.348(3), C(1)-S(1) 1.751(3), C(2)-N(1) 1.331(3), C(2)-C(3) 1.412(3), C(3)-N(3) 1.345(3), N(2)-N(3) 1.337(3), N(4)-N(5) 1.337(3). C(37)-
Pb(1)-C(31) 120.13(9), C(37)-Pb(1)-S(1) 116.11(6), C(31)-Pb(1)-S(1) 104.01(7), C(37)-Pb(1)-S(2) 110.81(6), C(31)-Pb(1)-S(2) 113.63(6), S(1)-
Pb(1)-S(2) 87.447(18), C(37)-Pb(1)-N(1) 84.29(7), C(31)-Pb(1)-N(1) 80.46(8, S(1)-Pb(1)-N(1) 58.85(5), S(2)-Pb(1)-N(1) 146.16(5), C(37)-Pb(1)-
N(4) 88.56(7), C(31)-Pb(1)-N(4) 82.74(8), S(1)-Pb(1)-N(4) 143.95(4), S(2)-Pb(1)-N(4) 58.20(5), N(1)-Pb(1)-N(4) 155.20(6).
enhanced upon deprotonation. There is π stacking between
the aromatic rings, as well as an O-H‚‚‚S hydrogen bond
between the oxygen atom and one of the sulfur atoms,
O(1)‚‚‚S(2) at 3.302(7) Å, while the NH group does not
appear to participate in this kind of interaction.
The crystal structure of complex 5 consists of discrete
molecules of [PbPh2(L2)2]. A perspective view of the
complex together with the atom labeling scheme and selected
bond angles and distances are given in Figure 4. Within the
complex, the lead(IV) ion is hexacoordinated in a strongly
distorted octahedral arrangement, four of the coordination
positions belonging to the NS deprotonated ligands and the
two remaining positions in the octahedral geometry are
occupied by two phenyl groups with a C-Pb-C angle of
120.13(9)°. This value is intermediate between the ideal value
for the cis (90°) and the trans isomer (180°), a similar
situation to that found in similar tin complexes (122-155°),
which suggests that the geometry of the complex can be
described as a distorted trapezoidal bipyramid41 in which the
equatorial plane is formed by the sulfur and nitrogen atoms
and the axial position are occupied by the two phenyl groups.
Another possibility is to consider the compound as a bicapped
(41) Ng, S. W.; Wei, C.; Das, V. G. K.; Mak, T. C. W. J. Organomet.
Chem. 1987, 334, 295.
10442 Inorganic Chemistry, Vol. 46, No. 24, 2007

Diphenyllead(IV) Chloride Complexes
tetrahedron defined by the carbon and sulfur atoms, with
four tetrahedral angles close to the ideal value angles
distorted by the influence of the capping atoms.42,43
Cl2 in the presence of basic medium. In all the complexes
the ligands act as anions. In the complexes containing the
open-chain ligands, these act at least as an N2S2 chelate. In
complexes 1 and 3, the lead atom is heptacoordinated with
a C2N2S2Cl environment in a monomeric structure. Moreover,
complex 4 shows a binuclear structure in which each lead
atom has a C2N2S3 environment with the ligand acting as a
N2S2 chelate and sulfur bridge. The data of complex 2 suggest
a binuclear structure with the dideprotonated ligand acting
as N2S2 chelate and sulfur bridge. The cyclic ligand deriva-
tives are mononuclear complexes with the ligand acting as
bidentate NS. Complexes 5-7 show that the ligands are
deprotonated with a distorted octahedral geometry around
the lead atom. In addition, complex 5 shows linkage
isomerism since one of the ligands is bonded through the
amine nitrogen, while in the other one, the nitrogen involved
in the coordination is the new imine group, behavior observed
for the first time in this ligand. In the absence of crystal-
lographic data for complex 6, its analytical data and
spectroscopic characteristics are consistent with a five-
coordinate lead atom in a monomeric structure.
The four positions occupied by the ligand are through the
amine nitrogen atom N(4), the new imine nitrogen N(1), and
the sulfur atoms S(1) and S(2). This behavior is a good
example of linkage isomerism and it is observed for the first
time in 1,2,4-triazine-3-thione ligands. The coordination
mode of the ligands gives rise to two four-membered chelate
rings. Each triazine, including the sulfur atom, can be
considered planar, with maximun deviations of 0.019 and
0.015 Å for N(2) and C(18), respectively. Bond lengths in
the complex agree well with an imine-thione form of the
ligand, as does the NMR spectroscopy, but with considerable
electronic delocalization through the triazine ring, owing to
the deprotonation of the ligand. As a consequence of this
delocalization, all the C-N bonds have almost the same
length (Figure 4). The thione bonds are longer than in the
precursor molecule (1.628 Å in L2H2OCH3) and are inter-
mediate between the theoretical C-S single and double
bonds,44 as is also the case with the N-N bonds. Both
S-C-N angles are also modified, but they do not reflect
the different nitrogen atoms involved in the coordination.
The Pb-S distances are very similar and quite shorter than
in the open-chain complexes. In contrast, due to the small
bite of the triazines, the Pb-N distances are quite long and
in the limit range of this kind of bonds.
Acknowledgment. We thank Ce´sar J. Pastor and Manuela
E. Medina of “Servicio Interdepartamental de Investigacio´n
de la Universidad Auto´noma de Madrid”(SIDI) (Spain) and
Dr. Andrew R. Cowley of University of Oxford (United
Kingdom) for the X-ray diffraction measurements. We thank
Prof. Dr. Mauro Carcelli of Universita´ di Parma, who kindly
provided us with diphenyllead(IV) chloride. We also thank
to DGICYT for financial support (Project CT2005-07788/
BQU) and Universidad Auto´noma de Madrid for a grant to
David G. Calatayud.
Conclusions
The reactions were carried out in different conditions, but
the best results were obtained using methanol or dried CH2-
(42) Lockart, T. P.; Calabrese, J. C.; Davidson, F. Organometallics, 1987,
6, 2479.
Supporting Information Available: Crystallographic data in
CIF format. This material is available free of charge via the Internet
at http://pubs.acs.org.
(43) Chandrasekhar, V.; Day, R. O.; Holmes, J. M.; Holmes, R. R. Inorg.
Chem. 1988, 27, 958.
(44) Sutton, L. E. Tables of Interatomic Distances and Configuration in
Molecules and Ions, supplement; The Chemical Society: London,
1965.
IC701490J
Inorganic Chemistry, Vol. 46, No. 24, 2007 10443