Pentanuclear and Octanuclear Manganese Helices

Abstract

Abstract Two helical manganese complexes, [Mn 5 (L) 3 (μ 3 ‐O)(NO 3 )(OMe) 2 (MeOH)](NO 3 ) · 4MeOH · H 2 O ( 1 ) and [Mn 8 (L) 6 (μ 3 ‐Cl) 2 ]Cl 2 · 3C 2 H 4 Cl 2 · 60H 2 O · 2DMF ( 2 , DMF = N , N ‐dimethylformamide), were obtained by the reaction of the multidentate polypyridine ligand 2,6‐bis[5‐(2‐pyridinyl)‐1 H ‐pyrazole‐3‐yl]‐pyridine (H 2 L) with manganese nitrate and chloride, respectively. The compounds were characterized by elemental analyses and single‐crystal X‐ray structural analyses. The pentanuclear complex 1 is composed of three ligands and five manganese ions with μ 3 ‐oxido bridges, whereas the octanuclear complex 2 is constructed from six ligands and eight manganese ions with two μ 3 ‐chlorido bridges. Both compounds have helix‐type structures. The manganese ions in 1 are present in a mixture of +2 and +3 valence states, whereas 2 is homovalent and contains only +2 ions. The magnetic properties of both compounds were investigated in the temperature range 1.8–300 K, and antiferromagnetic interactions between the manganese ions are dominant in both complexes.