A dinuclear manganese(III) and a rare pentanuclear manganese(III) compound with a phenol–pyrazole ligand

Reacting Mn(ClO4)2·6H2O and H2phpzEt (H2phpzEt = 5(3)-(2-hydroxyphenyl)-3(5)-ethylpyrazole) in methanol in the presence of sodium hydroxide yields the compound [Mn2(HphpzEt)4(H2O)2](ClO4)2 (1). The pentanuclear [Mn5(μ3-O)2(HphpzEt)3(phpzEt)3(OCH3)(HOCH3)2(O2CPh)] (2) is obtained when performing a similar reaction with Mn(O2CPh)2·2H2O. Compound 1 consists of a symmetric dinuclear manganese(III) cationic unit, [Mn2(HphpzEt)4(H2O)2]2+ with two non-coordinated perchlorate anions. Compound 2 is a rare pentanuclear complex containing all the manganese ions in the oxidation state III and it also has μ3-oxido ligands. Temperature- and field-dependent magnetization studies indicate dominant antiferromagnetic interactions between the manganese(III) ions in both compounds.

A dinuclear and a pentanuclear manganese(III) complexes have been synthesized and characterized. The nuclearity of the compounds is determined by the manganese(II) salt used as starting material.Figure optionsDownload as PowerPoint slideHighlights
► Dinuclear Mn(III) compound with phenyl–pyrazolato bridges is reported.
► Pentanuclear Mn(III) compounds composed of a Mn5O4 cluster are made.
► Extension of the chemistry with the ligand 5(3)-(2-hydroxyphenyl)-3(5)-ethylpyrazole.
► The two new compounds show antiferromagnetic coupling.