Molecular structure and spectral properties of mono- and dinuclear complexes formed by manganese(II), 2,6-dimethoxybenzoate and 2,2′-bipyridine or 2-methylpyrazine

• Published in: Inorganica Chimica Acta 1995, Vol.236 (1), p.149-154
• Main Authors: Glowiak, Tadeusz, Kozlowski, Henryk, Erre, Liliana Strinna, Micera, Giovanni
• Format: Article
• Language: English
• Subjects: Carboxylate complexes; Crystal structures; Dinuclear complexes; Manganese complexes; Ternary complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/0020-1693(95)04638-P

The adducts formed by reaction of [Mn(dmb) 2(H 2O) 3] n · nH 2O, dmb = 2,6-dimethoxybenzoato(1−), with 2,2′-bipyridine (bpy) or 2-methylpyrazine (2-Mepz) were isolated in the solid state and characterized by single crystal X-ray diffraction, IR and EPR spectroscopy, and thermogravimetry. The adduct [Mn 2(dmb) 4*bpy) 2(H 2O) 2]·bpy crystallizes in the monoclinic space group P2 1/ n, with a = 15.983(4), b = 11.048(4), c = 17.682(4) A ̊ , β = 97.66(3)°, V = 3094.4(16) A ̊ 3, Z = 2 and D calc = 1.415 g cm −3 . The complex exhibits a dinuclear structure where two manganese(II) atoms share two carboxylate groups adopting a rather uncommon single-atom bridging mode. The coordination at each metal nucleus is completed by a further carboxylate group, acting as a monodentate donor, a water molecule and a chelating bidentate bipyridine molecule. The crystals of the adduct [Mn(dmb) 2(2-Mepz) 2(H 2O) 2] are monoclinic, space group P2 1/ n, with a = 8.024(3), b = 10.314(3), c = 18.289(4) A ̊ , β = 94.72(3)°, V = 1508.5(8) A ̊ 3, Z = 2 and D calc = 1.412 g cm −3 . The compound is mononuclear and consists of hexacoordinate ions bound to trans-pairs of monodentate carboxylates, water molecules and nitrogenous base molecules. The bpy adduct exhibits EPR spectra distinctive of magnetically coupled dimanganese(II) units.