Synthesis, characterization, and crystal structure of a (mu-oxo)bis(mu-acetato)diiron(III) complex with a dinucleating hexapyridine ligand, 1,2-bis[2-(bis(2-pyridyl)methyl)-6-pyridyl]ethane. The first example of a discrete (mu-oxo)bis(mu-acetato)diiron(III) complex with a dinucleating ligand

A mononucleating tripyridine ligand, 2-(bis(2-pyridyl)methyl)-6-methylpyridine (L(1)), and a dinucleating hexapyridine ligand, 1,2-bis[2-(bis(2-pyridyl)methyl)-6-pyridyl]ethane (L(2)), have been prepared. The reaction of a carbanion of 2,6-lutidine with 2-bromopyridine affords L(1) which is converted to LJ quantitatively by treating with tert-butyllithium and 1,2-dibromoethane. (mu-Oxo)bis(mu-acetato)diiron(III) complexes [Fe-2(O)(OAc)(2)(L(1))(2)](ClO4)(2) (1) and [Fe-2(O)(OAc)(2)L(2)](ClO4)(2) (2) have been synthesized and characterized by means of infrared, UV/vis, mass, and Mossbauer spectroscopies and by measuring magnetic susceptibility and cyclic voltammograms. All the spectral data are consistent with the (mu-oxo)bis(mu-acetato)diiron(III) core structure in both 1 and 2. A relatively strong molecular ion peak at m/z 865 corresponding to [{Fe2O(OAc)(2)L(2)}(ClO4)](+) in a FAB mass spectrum of 2 suggests the stabilization of the (mu-oxo)bis(mu-acetato)diiron(III) core structure by L(2) in a solution state. The compound 2 . DMF . 2-PrOH . H2O, chemical formula C44Cl2Fe2H51N7O16, crystallizes in the monoclinic space group C2/c with a 22.034(6) Angstrom, b = 12.595(5) Angstrom, c = 20.651(7) Angstrom, beta 121.49(2)degrees, and Z = 4. The cation has 2-fold symmetry with the bridging oxygen atom on the 2-fold axis: Fe-(mu-O) = 1.782(5) Angstrom, Fe-O-Fe = 123.6(6)degrees, and Fe ... Fe = 3.142(3) Angstrom. The diiron(III) core structure of 2 seems to be stabilized by encapsulation of the ligand. Compound 2 is the first example of a discrete (mu-oxo)bis(mu-acetato)diiron(III) complex with a dinucleating ligand.