Synthesis, spectral and structural studies of 1-ethoxycarbonyl-piperazine-4-carbodithioate and its Co(III), Zn(II) and Cd(II) complexes

The new complexes [Co(ecpzdtc)3] (2) [Zn(ecpzdtc)2(py)] (3) and [Cd(ecpzdtc)2(py)]·H2O (4) have been synthesized from sodium 1-ethoxycarbonyl-piperazine-4-carbodithioate [(Na+(ecpzdtc)−]. The ligand and the complexes have been characterized by elemental analyses, IR, magnetic susceptibility and single crystal X-ray data. The [Zn(ecpzdtc)2(py)] and [Cd(ecpzdtc)2(py)]·H2O complexes contain pyridine as the co-ligand. [Co(ecpzdtc)3] (2) crystallizes in the monoclinic system, whereas [Zn(ecpzdtc)2(py)] (3) and [Cd(ecpzdtc)2(py)]·H2O (4) crystallize in the triclinic system. The sulfur donor sites of the bidentate ligand chelate the metal center, forming a four-membered CS2M ring. The cobalt complex has a distorted octahedral geometry, the zinc complex is almost between trigonal bipyramidal and square pyramidal, whereas the cadmium complex is square pyramidal. The crystal structures of all the complexes are stabilized by various types of inter and intramolecular hydrogen bonding.

Graphical abstractNew complexes [Co(ecpzdtc)3] (2), [Zn(ecpzdtc)2(py)] (3) and [Cd(ecpzdtc)2(py)]·H2O (4) have been synthesized from sodium 1-ethoxycarbonyl-piperazine-4-carbodithioate [Na+(ecpzdtc)−]. In the presence of the carbodithioate ligand, Co(II) is converted to Co(III) by aerial oxidation, forming a distorted octahedral tris carbodithioate Co(III) complex. Four coordinate bis complexes of Zn(II) and Cd(II) further react with pyridine forming five coordinate ternary complexes. The zinc complex is almost between trigonal bipyramidal and square pyramidal, whereas the cadmium complex is square pyramidal.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► 1-Ethoxycarbonyl-piperazine-4-carbodithioate forms Co(III), Zn(II) and Cd(II) complexes. ► By aerial oxidation Co(II) is converted to Co(III) forming a tris carbodithioate Co(III) complex. ► Zn(II) and Cd(II) carbodithioates further react with pyridine forming five coordinate ternary complexes. ► The crystal structures are stabilized by various types of hydrogen bonding.