Abstract

MKWAKWI, Kwakhanya et al. The coordination behaviour of 2-((E)-(ferf-butylimino)methyl) phenol towards lanthanide nitrate and chloride salts. S.Afr.j.chem. (Online) [online]. 2023, vol.77, pp.36-41. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2023/v77a06.

Five novel complexes were prepared by reacting 2-((E)-(tert-butylimino)methyl)phenol (HL₂) with Ln(NO₃)₃xH₂O (Ln = Gd and Dy ; x = 6 and 5, respectively) and LnCl₃-6H₂O (Ln = Nd, Gd and Dy). The crystal structures of the former two Ln(III) nitrate complexes are isostructural and the coordination sphere is composed of three monodentate HL₂ ligands bonded to the metal centre through the phenolic oxygen atom and three nitrate ions coordinated in a bidentate fashion. Both complexes are nine-coordinate and SHAPE analysis reveals that they adopted a muffin polyhedra geometric type. The average Ln-O_nitrate and Ln-O_phenolate bond lengths are 2.5059 and 2.2816 A, respectively. The complexes derived from the chloride salts exhibited an octahedral geometry with four monodentate Schiff base ligands [Ln-O_phenolate distances range from 2.229(4) to 2.2797(18) A] coordinating in the equatorial positions and two chloride ions [average Ln-Cl bond length is 2.6530 A, and average Cl-Ln-Cl angles is 180^o] in axial positions. The ligand coordinated through the phenolate oxygen with the phenolic proton migrating to the imino nitrogen to give a zwitterionic form of the ligand. There are weak C-H-Cl interactions present and O-H-N hydrogen bonds are also observed in the crystal packing.

Keywords : bidentate; lanthanide; monodentate; Schiff base; zwitterion.

        · text in English     · English ( pdf )