Dinuclear Copper(II) Complexes of a Macrocyclic Compartmental Ligand in Two Isomeric Forms. Exogenous Ion Effect upon Ligand Isomerism

Abstract

Abstract A dinucleating compartmental ligand derived from the cyclic [2:1:1] condensation of 2,6-diformyl-4-methylphenol, 1,3-propanediamine, and diethylenetriamine (dien) assumes two isomeric forms in the dinuclear copper(II) complexes, [Cu2(La)](ClO4)2·2H2O (1) and [Cu2(Lb)(AcO)]BPh4 (2). Complex 1 has the ligand in the usual condensation with a trimethylene chain (–(CH2)3–) and a 3-azapentamethylene chain (–(CH2)2NH(CH2)2–) between two azomethine nitrogen atoms; the nitrogen atom of the 3-azapentamethylene chain is free from coordination. Complex 2 has the ligand in an unusual condensation with dien: The central amino nitrogen of dien is further involved in the condensation with one C=N linkage to form an imidazolidine ring. An acetate ion bridges two copper ions to form a μ-acetato-di(μ-phenolato) dinuclear core with a saddle-like shape. The origin for the unusual condensation in 2 is considered and the physicochemical properties of 1 and 2 are examined.