Schiff bases derived from S-alkyl esters of thiosemicarbazides have received considerable attention mainly due to variety of applications as well as their transition metal complexes [1-3]. Nitrogen-, sulfur- and oxygen-donor systems pertain to both biological and chemical properties [4]. A tridentate N2O isothiosemicarbazone donor ligands can act as neutral, monoanionic and dianionic forms. 1 2 Here in we report two new Ni(II) (1) and Mn(IV) (2) complexes of 1-(2-hydroxyphenyl)ethanone S-alyllisothiosemicarbazone hydrobromide (H2L.HBr) (Scheme 1). The complexes have been characterized by elemental analysis, IR and UV–Vis spectroscopy and X-ray analysis. Scheme 1 Complex 1 is the first example of the dimmer compounds in isothiosemicarbazones in which two NiL moieties are connected to each other via piperazine molecule. 2 reveals a distorted octahedral geometry in which Mn(IV) is surrounded by two dianionic tridentate ligand (L2-). The H2L acts as a binegatively tridentate ligand and coordinates to the metal via the azomethine nitrogen, the thioamide nitrogen and the phenolate oxygen atoms.

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