Oxime-functionalized diazamesocyclic derivates and their metal complexes: Effect of the ligand backbones and anions on the generation of novel monomeric and mono-μ-Cl dimeric Cu II complexes

Abstract

Two oxime-functionalized diazamesocyclic derivates, namely, N, N′-bis(acetophenoneoxime)-1,4-diazacycloheptane (H 2 L 1) and N, N′-bis(acetophenonoxime)-1,5-diazacyclooctane (H 2 L 2), have been prepared and characterized. Both ligands (obtained in the hydrochloride form) can form stable metal complexes with Cu II and Ni II salts, the crystal structures of which were determined by X-ray diffraction technique. The reactions of H 2 L 1 with Cu(ClO 4) 2 and Ni(ClO 4) 2 afford a penta-coordinated mononuclear complex [Cu(H 2 L 1)Cl] · ClO 4 ( 1) and a four-coordinated monomeric [Ni(H L 1)] · ClO 4 ( 2), in which the ligand is monodeprotonated. The ligand H 2 L 2 also forms a quite similar mononuclear [Ni(H L 2)] · ClO 4 complex with Ni(ClO 4) 2, according to our previous work. However, reactions of different Cu II salts [Cu(ClO 4) 2, CuCl 2 and Cu(NO 3) 2 for 3, and CuSO 4 for 4] with H 2 L 2 in the presence of NaClO 4 yield two unusual mono-μ-Cl dinuclear Cu II complexes [Cu 2(H L 2) 2Cl] · (ClO 4) ( 3), and [Cu 2(H 2 L 2)(H L 2)Cl] · (ClO 4) 2 · (H 2O)( 4). These results indicate that the resultant Cu II complexes ( 1, 3 and 4) are sensitive to the backbones of diazamesocycles and even auxiliary anions.