A Diferrous Single‐Molecule Magnet

The diferrous complex [Fe2(acpypentO)(NCO)3] (1),(acpypentO– = the anion of 1,5-bis[2-pyridyl(1-ethylimino)]pentane-3-ol) was studied by spectroscopic (dual-mode X-band EPR and 57Fe-Mossbauer) and magnetic (AC magnetic susceptibility) techniques. Complex 1 (A. K. Boudalis et al., Inorg. Chem.2004, 43, 1574) was previously shown to exhibit an intramolecular ferromagnetic coupling with important single-ion anisotropies with marked differences in the single-ion electronic parameters of the two iron sites. In this contribution, additional studies are carried out to probe its dynamic magnetic properties. Mossbauer spectra recorded at liquid helium temperatures indicate slow paramagnetic relaxati…

A Nonanuclear Iron(II) Single-Molecule Magnet

A family of enneanuclear iron(II) single-molecule magnets.

Complexes [Fe 9 (X) 2 -(02CMe)8{(2-py) 2 CO 2 } 4 ] (X - = OH (1), N 3 - (2), and NCO- (3)) have been prepared by a route previously employed for the synthesis of analogous Co 9 and Ni 9 complexes, involving hydroxide substitution by pseudohalides (N 3 - , NCO-). As indicated by DC magnetic susceptibility measurements, this substitution induced higher ferromagnetic couplings in complexes 2 and 3, leading to higher ground spin states compared to that of 1. Variable-field experiments have shown that the ground state is not well isolated from excited states, as a result of which it cannot be unambiguously determined. AC susceptometry has revealed out-of-phase signals, which suggests that these…