Abstract

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Dialkyldithiophosphate derivatives of macrocyclic complexes of Pb(II), having N₄S₄ potential donors, of the general formula, [Pb(L){S₂P(OR)₂}₂] where L=macrocyclic ligands L₁, L₂, L₃, L₄ and L₅; R= C₂H_5-, C₃H₇ⁿ or C₃H₇ⁱ have been synthesized from the reaction of [Pb(L)X₂](where X= Cl^-, NO₃^- or CH₃COO^-ˉ) with sodium dialkyldithiophosphate in 1:2 molar ratios in THF. These complexes have been characterized by elemental analysis, molar conductance, molecular weight determinations, IR, ¹H, ¹³C & -³¹P NMR. Molecular weight determinations of these complexes indicate their monomeric nature. Octahedral structures have been proposed on the basis of IR, ¹H, ¹³C & ³¹P NMR, in which four nitrogen atoms of the macrocyclic ring coordinate to the central lead ion square-planar geometry and each dithiophosphate moiety occupies the axial positions binding the central lead ion in a unidentate manner. The antimicrobial activities of these derivatives have been studied by screening them Aspergillus flavus, Fusarium oxysporum, Alternaria alternata and bacteria like Salmonella typhi and Bacillus subtili. Dialkyldithiophosphate derivatives were found to be more fungitoxic and antibacterial than their corresponding macrocylic complexes.

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