New dinuclear cobalt (ΙΙ, ΙΙΙ) and tetranuclear manganese (ΙΙΙ) complexes assembled by a polydentate Schiff-base ligand: synthesis, structure and magnetic properties

• Two first-row transition metal complexes are reported.
• 1 and 2 consist of tetranuclear manganese and binuclear cobalt.
• Dominant antiferromagnetic interactions between manganese ions were observed for 1.
• Static magnetic measurement for 2 confirms its mixed valence CoΙΙ/CoΙΙΙ nature.

The reactions of 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L) and Mn(ClO4)2·6H2O or Co(SCN)2·3H2O in the presence of triethylamine in methanol led to the formation of two new complexes [MnΙΙΙ4(HL)2(H2L)2(CH3OH)4]·4CH3OH·(ClO4)2 (1) and [CoΙΙCoΙΙΙ(H2L)2(CH3OH)(SCN)]·1.5CH3OH·1.5H2O (2), respectively. According to structural data and magnetic properties tetranuclear complex 1 contains four homo-valence manganese (ΙΙΙ) atoms, while in the binuclear complex 2 composed of hetero-valence bi- and trivalent cobalt (ΙΙ, ΙΙΙ) atoms. Weak antiferromagnetic exchange interactions between neighboring manganese ions in 1 have place. χMT for 2 was fitted using a model of isolated cobalt (ΙΙ) ion with zero-field splitting parameters and the study confirms its mixed valence CoΙΙ/CoΙΙΙ nature. No slow magnetic relaxation effects were observed for both complexes in the absence of an applied dc magnetic field.

Homo-valence tetranuclear manganese and hetero-valence binuclear cobalt complexes with the formula [MnΙΙΙ4(HL)2(H2L)2(CH3OH)4]·4CH3OH·(ClO4)2 (1) and [CoΙΙCoΙΙΙ(H2L)2(CH3OH)(SCN)]·1.5CH3OH·1.5H2O (2) have been structurally and magnetically characterized.Figure optionsDownload as PowerPoint slide