Templated synthesis of Ni(ii) complexes of unsymmetrical Schiff base ligands derived from 1, 3-diamino-2-propanol: structural diversity and magnetic properties. (14th February 2022)

• Record Type: Journal Article
• Authors: Bhunia, Pradip; Maity, Souvik; Mayans, Júlia; Ghosh, Ashutosh
• Is Part Of: New journal of chemistry. Volume 46:Number 9(2022)
• Page Start: 4363
• Page End: 4372
• Publication Date: 2022-02-14
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/d1nj05638g
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : A Ferromagnetically coupled tetranuclear, an antiferromagnetically coupled hexanuclear and a mononuclear Ni(II) complex of new unsymmetrical Schiff base ligands derived from 1, 3-diamino-2-propanol have been obtained with a slight change in the carbonyl compounds. Abstract : An attempt at the synthesis of complexes of unsymmetrical Schiff base ligands derived from 1, 3-diamino-2-propanol, o -hydroxyacetophenone and salicylaldehyde or o -vanillin by a Ni(ii ) templated method resulted in the isolation of mononuclear [NiL 1 ] (1 ) and tetranuclear [Ni4 L 2 2 (μ3 -OCH3 )2 (H2 O)2 ]·10CH3 OH (2 ) where H3 L 1 = N -(α-methylsalicylidene)– N ′-(salicylidene)–1, 3-diamino-2-propanol, and H3 L 2 = N -(3-methoxysalicylidene)– N ′-(α-methylsalicylidene)–1, 3-diamino-2-propanol. Complex 1 on reaction with Ni(NO3 )2 yielded a hexa-nuclear complex, [Ni2 Ni4 L 1 2 L 3 2 (NO3 )2 ]·23CH3 OH (3 ). Ligand H2 L 3 was formed in situ by partial hydrolysis of H3 L 1 during the synthesis of 3 . Single crystal X-ray diffraction studies revealed a square planar geometry of Ni(ii ) in complex 1 and a hexa-coordinated distorted octahedral geometry of all four Ni(ii ) centres, forming a defective dicubane core in complex 2 . In hexa-nuclear complex 3, two square planar Ni(ii ) centres are connected to a distorted cubane core, formed by four octahedral Ni(ii ). Temperature dependent molar magnetic susceptibility measurements illustrated overall ferromagnetic coupling among the Ni(ii ) in complex 2 with exchange coupling parameters, J 1 = 10.9(2) cm −1, J 2 = −3.1(1) cm −1, J 3 = 13.8(8) cm −1 and g = 2.200(1) and predominating anti-ferromagnetic coupling interactions among the four paramagnetic Ni(ii ) in the cubane core of complex 3 with exchange coupling parameters, J 1 = −1.99(1) cm −1, J 2 = 2.00(1) cm −1, J 3 = −1.93(1) cm −1 and g = 2.359(1). Cyclic voltammetry measurements showed quasi-reversible and irreversible Ni(ii )/Ni(i ) couples for complexes 1 and 2, respectively, whereas complex 3 showed one irreversible and one quasi reversible reduction process for the octahedral and square planar Ni(ii ) centres, respectively.