title: Synthesis, characterization, and thermodynamics of some new unsymmetrical Schiff bases of salicylaldehyde with 3,4-diaminopyridine and their cobalt(III) complexes.
abstract: Some new Schiff bases derived from 3,4-diaminopyridine (3,4-DAP) and their new unsymmetrical Co(III) five coordinate complexes described as [Co(Chel)(L)]ClO4⋅H2O where (Chel) is the deprotonated form of a series of unsymmetric ligands containing 3,4-diaminopyridine (3,4-DAP) and substituted salicylaldehyde moieties and a new Co(III) six coordinate Co(III) complex, were synthesized and characterized by (1)H NMR, IR, UV-Vis, and elemental analysis. For the new synthesized five coordinate complexes, the formation constants of the interaction of the Co(III) Schiff bases with various donors were measured spectrophotometrically. The trend of the formation constants of the five coordinate Co(III) Schiff base complexes toward a given phosphine is as follow: 5-H>5-Br and the formation constants trend of these donors are as follow: PBu3>PPh2Me. Furthermore the adduct formation of the five coordinate [Co(3,4-Salpyr)(PBu3)] ClO4⋅H2O, with aromatic amines shows the following binding trend: Im>2-MeIm>2-EtIm>BzIm. The trend of the formation constants of Co(III) Schiff base complexes toward a given donor according to the phosphine axial ligand is as follow: PBu3>PPh2Me.
authors.affiliation: Chemistry Department, College of Sciences, Shiraz University, Shiraz 71454, Islamic Republic of Iran. Electronic address: mozaffarasadi@yahoo.com.
authors.forename: Mozaffar
authors.initials: M
authors.lastname: Asadi
authors.affiliation: Chemistry Department, College of Sciences, Shiraz University, Shiraz 71454, Islamic Republic of Iran; International Branch, Shiraz University of Medical Sciences, Shiraz, Islamic Republic of Iran.
authors.forename: Susan
authors.initials: S
authors.lastname: Torabi
authors.affiliation: Chemistry Department, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Islamic Republic of Iran.
authors.forename: Khosro
authors.initials: K
authors.lastname: Mohammadi
mesh_terms: D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry*; D000077770:Amifampridine; D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012545:Schiff Bases / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics
chemical_list: D000447:Aldehydes; D056831:Coordination Complexes; D012545:Schiff Bases; C013243:salicylaldehyde; D003035:Cobalt; D015761:4-Aminopyridine; D000077770:Amifampridine
keywords: Cobalt(III); Formation constants; Thermodynamic free energy change; Unsymmetrical Schiff base