Two New Supramolecular Architectures of Singly Phenoxo‐Bridged Copper(II) and Doubly Phenoxo‐Bridged Manganese(II) Complexes Derived from an Unusual ONOO Donor Hydrazone Ligand: Syntheses, Structural Variations, Cryomagnetic, DFT, and EPR Studies

Abstract

have been synthesized. The new potentially tetradentate ONOO donor hydrazone ligand [LH] has shown considerable metal ion selective phenoxo bridging in 1 and 2. It has coordinated copper(II) ions in its tridentate as well as in tetradentate fashion whereas for manganese(II) ions it solely showed its tetradentate character. In 1 the two adjacent pentacoordinate copper(II) centers are connected by a rare single phenoxo linkage of the hydrazone ligand whereas 2 is a doubly phen-

A versatile salicyl hydrazonic ligand and its metal complexes as antiviral agents

“…Acylhydrazone ligands, in fact, can act as bidentate or tridentate chelating ligands and even as tetradentates, and can coordinate one or more metal centers [1,3,10,11]. Complexes of salicylaldehyde hydrazones with Mn(II), Cu(II), lanthanide(III), Pd(II), and Ni(II) have been previously studied [1][2][3][8][9][10][11] and they represent a challenging topic from the coordination point of view. These ligands typically coordinate to the metal ion through the phenolic and carbonyl oxygens and the imine nitrogen atom.…”

“…Acylhydrazone-based ligands and their transition metal complexes are widely studied in catalysis [1], as building blocks in supramolecular chemistry [2,3], as anticancer agents [4,5], and, particularly interesting for our research, antiviral molecules [6,7]. They are often used to build multinuclear metal complexes since they are versatile ligands and their coordination properties can be easily tuned from an electronic and a steric point of view [8][9][10].…”

“…These ligands typically coordinate to the metal ion through the phenolic and carbonyl oxygens and the imine nitrogen atom. Their degree of deprotonation depends on the reaction conditions and the metal employed and they can give rise to monometallic, bischelated complexes or to multimetallic assemblies held together by intermolecular forces [2,3,12].…”

“…They are often used to build multinuclear metal complexes since they are versatile ligands and their coordination properties can be easily tuned from an electronic and a steric point of view [8][9][10]. Acylhydrazone ligands, in fact, can act as bidentate or tridentate chelating ligands and even as tetradentates, and can coordinate one or more metal centers [1,3,10,11]. Complexes of salicylaldehyde hydrazones with Mn(II), Cu(II), lanthanide(III), Pd(II), and Ni(II) have been previously studied [1][2][3][8][9][10][11] and they represent a challenging topic from the coordination point of view.…”

Synthesis and Structural Characterization of a Double Helical Dinuclear Copper(II) Complex With Tetradentate Biacetyl Bis(benzoylhydrazone)

“…The axial Cu-O5 bond is 2.2883(16) Å which is longer than the equatorial Cu-O ones [1.9062(15) and 2.0402(15) Å], and consistent with analogous systems observed in the literature. [27][28][29][30] The coordination spheres of the copper(II) ions in the complex are best described as a distorted square pyramidal according to the Addison parameter τ values of 0.27 (for Cu1) and 0.25 (for Cu2). The parameter τ is defined as τ = (α-β)/60, α > β, where α and β are the largest angles; with τ = 1 for a regular trigonal bipyrmid and τ = 0 for a regular square pyramid.…”