Importance of C–H⋯π interactions in stabilizing the syn/anti arrangement of pendant alkoxy side arms in two manganese(iv) Schiff base complexes: exploration of catechol oxidase and phenoxazinone synthase like activities

Abstract

Two new octahedral manganese(IV) complexes [Mn(HL¹)(L¹)(NCS)]_n (1) and [Mn(HL²)₂(OH)Cl] (2) [where H₂L¹ = 1-(5-hydroxy-3-oxapentyliminomethyl)-3-ethoxyphenol and H₂L² = 1-(5-hydroxy-3-oxapentyliminomethyl)-4-chlorophenol] have been prepared and characterized. Unconventional C–H⋯π_(SCN) interactions play a key role in stabilizing the unexpected syn arrangement of the ligand pending arms in 1, whereas conventional C–H⋯π_(phe) interactions favour the anti arrangements in 2. The energetic features of these interactions have been studied by DFT calculations and characterized using Bader's theory of atoms in molecules in both complexes. Both complexes exhibit catechol oxidase and phenoxazinone synthase like activities.