Exchange Interactions and Zero-Field Splittings in C-3-Symmetric (Mn6FeIII)-Fe-III: Using Molecular Recognition for the Construction of a Series of High Spin Complexes Based on the Triplesalen Ligand Glaser, Thorsten Glaser Thorsten Heidemeier, Maik Heidemeier Maik Krickemeyer, Erich Krickemeyer Erich Bögge, Hartmut Bögge Hartmut Stammler, Anja Stammler Anja Froehlich, Roland Froehlich Roland Bill, Eckhard Bill Eckhard Schnack, Jürgen Schnack Jürgen The reaction of the tris(tetradentate) triplesalen ligand H(6)talen(t-Bu2), which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn-II salts under aerobic conditions affords, in situ, the trinuclear Mn-III triplesalen complexes [(talen(2)(t-Bu)){Mn-III(solv)(n)}(3)](3+). These can be used as molecular building blocks in the reaction with [Fe(CN)(6)](3-) as a hexaconnector to form the heptanuclear complex [{(talen(2)(t-Bu)){Mn-III(solv)(n)}(3)}(2){Fe-III(CN)(6)}](3+) ([(Mn6FeIII)-Fe-III](3+)). The regular ligand folding observed in the trinuclear triplesalen complexes preorganizes the three metal ions for the reaction of three facially coordinated nitrogen atoms of a hexacyanometallate and provides a driving force for the formation of the heptanuclear complexes [(M6Mc)-M-t](n+) (M-t, terminal metal ion of the triplesalen building block; Me, central metal ion of the hexacyanometallate) by molecular recognition, as has already been demonstrated for the single-molecule magnet [(Mn6CrIII)-Cr-III](3+)center dot [{(talen(2)(t-Bu))(Mn-III(MeOH))(3)}(2){Fe-III(CN)(6)}][Fe-III(CN)(6)] (1) was characterized by single-crystal X-ray diffraction, FTIR, ESI- and MALDI-TOF-MS, Mossbauer spectroscopy, and magnetic measurements. The molecular structure of [(Mn6FeIII)-Fe-III](3+) is overall identical to that of [(Mn6CrIII)-Cr-III](3+) but exhibits a different ligand folding of the Mn-III salen subunits with a helical distortion. The Mossbauer spectra demonstrate a stronger distortion from octahedral symmetry for the central [Fe(CN)(6)](3-) in comparison to the ionic [Fe(CN)(6)](3-). At low temperatures in zero magnetic fields, the Mossbauer spectra show magnetic splittings indicative of slow relaxation of the magnetization on the Mossbauer time scale. Variable-temperature-variable-field and yen versus T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian, consisting of isotropic exchange, zero-field splitting, and Zeeman interaction taking into account the relative orientation of the D tensors. Satisfactory reproduction of the experimental data has been obtained for parameters sets J(Mn-Mn) = -(0.85 +/- 0.15) cm(-1), J(Fe-Mn) = +(0.70 +/- 0.30) cm(-1), and D-Mn = -(3.0 +/- 0.7) cm(-1). Comparing these values to those of [Mn Cr-III(6)III](3+) provides insight into why [(Mn6FeIII)-Fe-III](3+) is not a single-molecule magnet. 48 2 607-620 607-620 American Chemical Society (ACS) 2009 1