Observation of novel oxygen⋯oxygen interaction in supramolecular assembly of cobalt(iii) Schiff base complexes: a combined experimental and computational study

Abstract

Two mononuclear cobalt(iii) Schiff base complexes with azide [Co(L)(N3)(L′)] (1) and [Co(L)(N3)(L″)] (2) {where HL = 1-((2-(diethylamino)ethylimino)methyl)naphthalene-2-ol, HL′ = 2-hydroxy-1-naphthaldehyde and HL″ = acetylacetone} have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopy and single crystal X-ray diffraction studies. Both complexes show mononuclear structures with azide as terminal coligand. Structural features have been examined in detail that reveal the formation of interesting supramolecular networks generated through non-covalent forces including hydrogen bonding, C-H⋯H-C and C-H/π interactions. These interactions have been studied energetically by means of theoretical DFT calculations. We have also analyzed the unexpected O⋯O interactions observed in one complex between the oxygen atoms of the coordinated aldehyde groups using several computational tools, including Bader's "atoms-in-molecules" (AIM) and natural bond orbital (NBO) analyses.