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A new member of the Mn12 family of single-molecule magnets (SMMs) has been prepared and found to be the first of this family to give a 3-D ferromagnetic network. [Mn12O12(O2CC6H4-p-F)16(H2O)4] (2) was prepared by carboxylate substitution on the acetate derivative with p-F-benzoic acid and crystallizes as 2·8MeCN in space group I42m with extensive formation of intermolecular C–H···F hydrogen-bonding. The latter leads to a combination of ferromagnetic (F) and antiferromagnetic (AF) interactions and an overall F network that gives a χMT value at low T that is abnormally high for an S = 10 ground state. 2·8MeCN undergoes solvent loss under vacuum to 2, with a decrease in unit-cell volume of 17%, primarily due to a 13% decrease in the c-axis. The χMT vs T plot for 2 indicates a switch to a net AF network. Exposure to air causes hydration to 2·3H2O, a concomitant increase in unit cell volume, and a switch back to a F network. The same conversion of 2·8MeCN to 2·3H2O can also be accomplished in one step rather ...

A new "offset" analogue of the classical [Mn6O2]-core oxime-bridged single-molecule magnets is introduced with a modified stacking arrangement of the [Mn3O] units. Studies of the magnetic properties reveal antiferromagnetic exchange interactions, a spin S = 4 ground state and population of low-lying excited states. Slow relaxation of the magnetization can be detected, with a corresponding energy barrier of 35.8 K. Interpretation of these features is supported with high-frequency EPR studies, quantifying the easy-axis type magnetic anisotropy, leading to a biaxial system. Redox properties investigated by cyclic and differential pulse voltammetry reveal multiple irreversible redox processes.