Synthesis and structure of dithizonato complexes of antimony(III), copper(II) and tin(IV)

Abstract

In view of the important role of dithizone in trace metal analyses, new structural aspects and approaches used to probe metal complexes of dithizone are of interest. Three X-ray diffraction structures are reported, dichloridobis(dithizonato)tin(IV), dichlorido(dithizonato)antimony(III), and bis(dithizonato)copper(II). During synthesis of the tin complex, auto-oxidation of Sn^IICl₂ to Sn^IV occurred without chloride liberation. The Sb^III complex revealed a unique distorted see-saw geometry which is, as for the other complexes, predicted by DFT molecular orbital calculations. The computed products of the lowest energy reactions are in agreement with experimentally obtained reaction products, which, together with molecular orbital renderings serve as a tool toward prediction of modes of coordination in these complexes. The S–M–N bond angle in the five-membered coordination ring shows a linear relationship with the corresponding metal ionic radii.

Keywords:

• Crystal structure
• dithizone
• tin
• copper
• antimony
• DFT
• orbitals
• ionic radius

Funding

This work has received support from the Norwegian Supercomputing Program (NOTUR) through a grant of computer time [grant number NN4654 K] (JC), the South African National Research Foundation (JC, ML), Central Research Fund of the University of the Free State, Bloemfontein (JC, KGvE) and the University of Pretoria (ML).