Diphenyllead(IV) Chloride Complexes with Benzilthiosemicarbazones. The First Bis(Thiosemicarbazone) Derivatives

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.