Exploring CH···Azide interactions in Co(III) Schiff base complexes: Synthesis, crystal structures, and theoretical insights

Abstract

This study presents the synthesis, crystal structures, and theoretical analysis of three new Co(III) Schiff-base complexes. The complexes, [Co(L¹)(bzan)(N₃)] (1), [Co(L²)(bzan)(N₃)] (2), and [Co(L³)(PTZ)(N₃)] (3) [where, HL¹ = 1-((2-(dimethylamino)ethylimino)methyl)naphthalen-2-ol, HL² = 2-(-(2-(diethylamino)ethylimino)methyl)-4,6-dibromophenol, Hbzan = 1-benzoylacetone, HL³ = 2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-chlorophenol, HPTZ = 5-(2-pyridyl)tetrazole], were synthesized using Schiff base ligands (HL¹-HL³) and azide ligands, yielding mononuclear octahedral structures. Detailed Hirshfeld surface analysis revealed the importance of N···H interactions involving the azide ligands, in addition to C···H and H···H interactions. DFT calculations further explored the electronic structures and the nature of the noncovalent interactions within the complexes. The findings indicate that CH···N₃ interactions play a crucial role in the self-assembly of these complexes, forming 1D polymeric chains. The study highlights the importance of these interactions in stabilizing the crystal structures and offers insights into the role of noncovalent forces in the design of new coordination complexes.