Diphenyllead(IV) Chloride Complexes with Benzilthiosemicarbazones. The First Bis(Thiosemicarbazone) Derivatives David G. Calatayud, Elena Lo ´ pez-Torres, and M. Antonia Mendiola* Departamento de Quı ´mica Inorga ´ nica, UniVersidad Auto ´ noma de Madrid, Cantoblanco, 28049 Madrid, Spain Received July 26, 2007 Reactions of diphenyllead(IV) chloride with benzil bis(thiosemicarbazone) (L 1 H 6 ) and benzil bis(4-methyl-3- thiosemicarbazone) (L 1 Me 2 H 4 ) 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 [PbPh 2 Cl(L 1 H 5 )]‚3H 2 O(1) and [PbPh 2 Cl(L 1 Me 2 H 3 )] (3) are mononuclear species in which the ligands are partially deprotonated and the lead atom has a C 2 N 2 S 2 Cl environment in a distorted pentagonal bipyramid coordination geometry. Complex [PbPh(L 1 Me 2 H 2 )] 2 ·2H 2 O(4) was also obtained, which contains two lead atoms in a binuclear structure with a C 2 N 2 S 3 coordination sphere for each lead atom, since both dideprotonated ligands act as N 2 S 2 chelate and as sulfur bridge. Reaction from L 1 H 6 , in the same conditions in which complex 4 was prepared, gave a mixture of products: the lead (II) complex [Pb(L 1 H 4 )] 2 (2) and [PbPh 3 Cl] n . Reactions with the cyclic molecules 5-methoxy-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-thione (L 2 H 2 OCH 3 ) and 5-methoxy-4-methyl-5,6-diphenyl-4,5-dihydro-2H-[1,2,4]-triazine-3-thione (L 2 MeHOCH 3 ) were also explored. In all the complexes, the ligands are deprotonated. The complexes [PbPh 2 (L 2 ) 2 ](5) and [PbPh 2 (L 2 MeOCH 3 ) 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 2 Cl(L 2 )] (6), which was also isolated, could not be crystallized. All the complexes were characterized by elemental analysis, mass spectrometry, IR and 1 H, 13 C, and 207 Pb NMR spectroscopy and some of them by X-ray diffraction studies. Introduction 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 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- * 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.; Martı ´n, R. B. Coord. Chem. ReV. 2001, 219, 435-461. (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.; Garcı ´a-Tasende, M. S.; Sa ´nchez, A.; Sordo, J.; Vidarte, M. J. Inorg. Chem. 2003, 42, 2584. Inorg. Chem. 2007, 46, 10434-10443 10434 Inorganic Chemistry, Vol. 46, No. 24, 2007 10.1021/ic701490j CCC: $37.00 © 2007 American Chemical Society Published on Web 10/16/2007