The First Structurally Characterized Trinuclear Dipicolinato Manganese Complex and its Conversion into a Mononuclear Species by Ligand Substitution

The novel complex [Mn 3 (pdc) 3 (bpy) 3 (H 2 O) 2 ] ( 1 ) (H 2 pdc = 2,6‐pyridinedicarboxylic acid, also known as 2,6‐dipicolinic acid; bpy = 2,2′‐bipyridine), has been obtained from the reaction of polymeric [MnK 2 (pdc) 2 (H 2 O) 7 ] n ( 2 ) with bpy, and is the first example of a structurally characterized, trinuclear Mn complex incorporating dipicolinato ligands. All the Mn II centers are seven‐coordinate in severely distorted pentagonal‐bipyramidal geometries. The conversion of 1 to mononuclear [Mn(pdc)(bpy)(Him) 2 ] ( 3 ) (Him = imidazole), which is the first seven‐coordinate Mn complex with a Him ligand, has also been achieved by substitution of the labile ligand in 1 by Him. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)