Synthesis, spectroscopy and cyclic voltammetry of new iron(III) complexes with 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex): X-ray crystallographic identification of [Fe(MPz3Hex)2]ClO4 · 2H2O with an indication for unusual rotation about the azomethine double bond on complexation with iron(III) |