Synthesis and characterization of four new manganese(III) complexes and amino acid (L-aspartic acid, L-asparagine, L-glutamic acid, L-glutamine) Schiff bases

Abstract

New series of manganese(III) complexes and amino acid Schiff bases have been prepared from 2-hydroxy-1-naphthaldehyde and α-amino acids [L-aspartic acid (Asp), L-asparagine (Asn), L-glutamic acid (Glu) and L-glutamine (Gln)]. The structures of the ligands and manganese complexes were identified using elemental analyses, i.r, electronic spectra, 1H-n.m.r spectra, magnetic moment measurements and thermogravimetric analyses (t.g.a). The results suggest that H2L1: [N-(2-hydroxy-1-naphthylidene) aspartic acid] and H2L3: [N-(2-hydroxy-1-naphthylidene)glutamic acid] Schiff bases behave as trianionic tetradentate species and coordinate to Mn(III) ion according to the general formula [MnL] · xH2O complexes. But, H2L2: [N-(2-hydroxy-1-naphthylidene) asparagine] and H2L4: [N-(2-hydroxy-1-naphthylidene)glutamine] Schiff bases behave as dianionic tridentate and coordinate to Mn(III) ion in the general formula for [MnL(OOCH3)] · xH2O complexes.