Investigation of some new main group metal complexes of hydrazine and 2‐mercaptopyridine‐3‐carboxylic acid mixed–ligands

Abstract

Synthesis of some new coordination complexes of main group metals (Ba, Ca, Mg, Sr, and Pb) with 2‐mercaptopyridine‐3‐carboxylic acid (H2Mpc) and hydrazine mixed ligands and their characterization through various chemical and spectral analyses are described in this article. With the help of analytical data obtained from mass, elemental (CHNS), hydrazine content, and metal content analysis, the molecular formulae of the complexes have been proposed as [Ba(N2H4)2(HMpc)H2O], [Ca(N2H4)2(HMpc)(H2O)2], [Sr(N2H4)(HMpc)(H2O)3], [Mg(N2H4)4(HMpc)].4H2O and [Pb(N2H4)5(HMpc)2]. The vibrational (FT‐IR and Raman) spectral data exposes that the 2‐mercaptopyridine‐3‐carboxylic acid coordinates with metal ion via both carboxylate‐O and thiolate‐S in the mode of bi‐dentate dianion while the hydrazine acts as bridging bi‐dentate. On thermal decomposition, these complexes dehydrate to give metal 2‐mercaptopyridine‐3‐carboxylate intermediates, which on further decomposition (heating upto 750°C) give the metal carbonates in the cases of Ba, Ca and Sr, and metal oxides for Mg and Pb. The in vitro antibacterial and antifungal activity of the ligand and its complexes are studied against five bacteria (Bacillus cereus, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli) and four fungi (Candida albicans, Aspergillus niger, Aspergillus fumigatus, and Penicilium variance).