σ-Hole halogen bonding interactions in a mixed valence cobalt(iii/ii) complex and anti-electrostatic hydrogen bonding interaction in a cobalt(iii) complex: a theoretical insight

Abstract

A mixed valence cobalt(III/II) complex, [(μ_1,3-OAc)₂{(SCN)Co^III(L¹)}₂Co^II]·H₂O (1), and an ionic coordination complex of cobalt(III), [Co^III(L²)₂][Co^III(L²)(N₃)₃] (2), have been synthesized and characterized {H₂L¹ = N,N′-bis(5-bromosalicylidene)-2,2-dimethyl-1,3-propanediamine and HL² = N(5-bromosalicylidene)-2,2-dimethyl-1,3-propanediamine}. Energetic features of the supramolecular interactions involved in both complexes have been studied through DFT calculations, which indicate that the trinuclear structure of complex 1 has been stabilized via σ-hole halogen bonding interactions in the solid state. On the other hand, counterintuitive anion⋯anion interactions are present in the solid state structure of complex 2, which have been stabilized through anti-electrostatic H-bonds (AEHB). The dissociation scan plot for the AEHB dimer has showed the existence of a significantly high energetic barrier.