Mn(3)(OAc)(6).CH(3)CN: a porous dehydrated manganese(II) acetate

The crystal structure of a new form of dehydrated manganese(II) acetate, poly[[hexa-mu(3)-acetato-trimanganese(II)] acetonitrile solvate], {[Mn(3)(CH(3)COO)(6)].CH(3)CN}(n), (I), reveals a three-dimensional polymeric structure based on an {Mn(3)} trimer. The {Mn(3)} asymmetric unit contains three crystallographically independent Mn positions, comprising a seven-coordinate center sharing a mirror plane with a six-coordinate center, and another six-coordinate atom located on an inversion center. Two of the four crystallographically independent acetate (OAc) ligands, as well as the acetonitrile solvent molecule, are also located on the mirror plane. The Mn atoms are connected by a mixture of Mn-O-Mn and Mn-OCO-Mn bridging modes, giving rise to face- and corner-sharing interactions between manganese polyhedra within the trimers, and edge- and corner-sharing connections between the trimers. The network contains substantial pores which are tightly filled by crystallographically located acetonitrile molecules. This structure represents the first porous structurally characterized phase of anhydrous manganese(II) acetate and as such it is compared with the closely related densely packed anhydrous manganese(II) acetate phase, solvent-free beta-Mn(OAc)(2).