Palladium complexes with hexamethyl tetraazacyclotetradecadiene (L) and isomers of its reduced form (‘tet-a’ & ‘tet-b’): synthesis, characterization and antimicrobial studies

The hexamethyl tetraazacyclotetradecadiene dihydroperchlorate Me 6 [14]diene. 2HClO 4 (L·2HClO 4 ) on reduction produced two isomeric C- chiral ligands ‘tet-a’ and ‘tet-b’. Reactions of these isomeric ligands with PdCl 2 produced square planar tetrachlorodipalladium(II) complexes, [PdL′][PdCl 4 ] (L′ = ‘tet-a’ or ‘tet-b’). Similar reactions of L·2HClO 4 with different palladium(II) salts, K 2 Pd(SCN) 4 , K 2 PdBr 4 and K 2 PdI 4 produced octahedral palladium(IV) thiocyanato, bromido and iodido complexes. Tetrachlorodipalladium(II) complex of isomeric ligands [PdL′][PdCl 4 ] underwent substitution reactions with KCNS and KNO 2 to form tetrathiocyanato dipalladium(II) and tetranitrodipalladium(II) complexes, [PdL′][Pd(NCS) 4 ] and [PdL′][Pd(NO 2 ) 4 ] respectively. However the same tetrachloro complexes underwent axial addition reactions with KBr and KI to form dibromidopalladium(IV) dibromide and diiodidopalladium(IV) diiodide complexes, [PdL′][PdBr 2 ]Br 2 and [PdL′][PdI 2 ]I 2 respectively. The complexes were characterized on the basis of elemental, spectroscopic, magnetochemical and conductometric analysis. The antibacterial and antifungal activities of the ligands and their complexes have been investigated towards different gram positive and gram negative bacteria and fungi.