Synthese und Strukturen neuer Eisen-Sauerstoff-Alkoxid-Cluster

Structure of a pentamanganese(II)-phenoxide cluster with a central five-coordinate oxide: MnII5(μ-OPh)6(μ3-OPh)2(μ5-O)(Py)6·Py (Py is pyridine)

Polynuclear metal clusters frequently feature geometric structural features not common in traditional coordination chemistry. These structures are of particular interest to bioinorganic chemists studying metallocluster enzymes, which frequently possess remarkably unusual inorganic structures. The structure of the manganese cluster μ₅-oxido-di-μ₃-phenoxido-hexa-μ-phenoxido-hexakis(pyridine-κN)hexamanganese(II) pyridine monosolvate, [Mn₅(C₆H₅O)₈O(C₅H₅N)₆]·C₅H₅N or Mn^II₅(μ-OPh)₆(μ₃-OPh)₂(μ₅-O)(Py)₆·Py, containing an unusual trigonal bipyramidal central oxide, is described. The compound was isolated from a reaction mixture containing bis(trimethylsilylamido)manganese(II) and phenol. The central O atom is presumed to have originated as adventitious water. The molecule crystalizes in a primitive monoclinic crystal system and is presented in the centrosymetric P2/n space group. The molecule possesses crystallographically imposed twofold symmetry, with the central O atom centred on the twofold axis and surrounded by a distorted trigonal bipyramidal arrangement of Mn atoms, which are further bridged by phenoxide ligands, and terminally ligated by pyridine. A pyridine solvent molecule resides nearby, also situated on a crystallographic twofold axis. The cluster is compared to three closely related previously reported structures.

Discrete tetrairon(III) cluster exhibiting a square-planar Fe4(mu4-O) core: structural and magnetic properties

The aerobic reaction of the Schiff-base ligand N-(benzimidazol-2-yl)salicylaldimine (Hbisi) with iron(II) perchlorate in methanol leads to the formation of the remarkable coordination compound [Fe(4)(mu(4)-O)(mu-MeO)(4)(bisi)(4)](ClO(4))(2) x 4 MeOH (1), whose single-crystal X-ray structure reveals the presence of a discrete Fe(III)(4)(mu(4)-O) core. Magnetic and Mossbauer studies both show that the exchange interaction within the square tetranuclear iron(III) unit is dominated by the central bridging mu(4)-oxido ligand, the involvement of the mu-methoxido bridges being negligible.