Pseudohalide‐Controlled Assemblies of Copper–Schiff Base Complexes with an Encapsulated Sodium Ion: Synthesis, Crystal Structure, and Computational Studies

Three new hetero‐bimetallic coordination complexes [Na(Cu II L 1 ) 2 ](ClO 4 ) · 0.5H 2 O ( 1 ), [Na(Cu II L 2 ) 2 ][Cu I 2 (μ 1,3 ‐NCS) 3 ] n ( 2 ), and {[Na(Cu II L 3 ) 2 ](μ 1,5 ‐dca)} n ( 3 ; dca = dicyanamide) have been synthesized by using different Schiff base ligands [e.g., L 1 H 2 = N , N′ ‐bis(3‐methoxysalicylidenimino)‐1,3‐diaminopentane, L 2 H 2 = N , N′ ‐bis(3‐ethoxysalicylidenimino)‐1,3‐diaminopropane, and L 3 H 2 = N , N′ ‐bis(5‐bromo‐3‐methoxysalicylidenimino)‐1,3‐diaminopropane] in the presence of pseudohalide coligands N 3 – , SCN – , and N(CN) 2 – (dca), respectively. The ligands and the complexes have been characterized by microanalytical and spectroscopic techniques. The structures of the complexes, determined by single‐crystal X‐ray diffraction studies, show that in all cases a trinuclear Na(Cu II L ) 2 unit is formed, but of different configurations. 1 does not include N 3 – anions. In contrast, in 2 , SCN – extrudes partial in situ reduction of Cu II to lead to the formation of an infinite [Cu I 2 (μ 1,3 ‐NCS) 3 ] n anionic chain; and in 3 , N(CN) 2 – bridges the metal–ligand assemblies to form a 1D polymeric chain. ESI‐MS, UV/Vis spectroscopy, and cyclic voltammetry were performed to investigate the solution‐state behavior of the complexes. Theoretical calculations of the optimized geometries of the complexes were carried out at the BLYP/DNP level to determine their relative stabilities from the HOMO–LUMO gap and chemical softness values.