Synthesis, characterisation, reactivity and X-ray crystal structure of a mixed-ligand η1-salicylaldehyde complex of Mn (III)

Abstract A tridentate ligand L has been synthesised from salicylaldehyde and 1-dimethylamino-2-propylamine. It undergoes partial hydrolysis to regenerate salicylaldehyde in methanolic KOH solution. Reaction of manganese (II) acetate with this solution, followed by addition of sodium thiocyanate, produces a dark brown complex [Mn (L) (NCS){ o - (CHO)C 6 H 4 O}] (1), which has been crystallographically characterised. Coordination of Mn is Jahn–Teller distorted octahedral by L, salicylaldehyde, and thiocyanate. The coordinated aldehyde group reacts with 2-aminoethanol and with 2-aminophenol to give mononuclear neutral Mn (III) complexes 2 and 3, respectively, with mixed Schiff-base ligands, [Mn (L) (L′)]. Complexes 1 and 2 are high-spin, while 3 is low-spin.