A Family of Mixed-Metal Cyanide Cubes with Alternating Octahedral and Tetrahedral Corners Exhibiting a Variety of Magnetic Behaviors Including Single Molecule Magnetism

A series of structurally related pseudocubic metal cyanide clusters of Re(II) and 3d metal ions
[{MX}4{Re(triphos)(CN)3}4] (M = Mn, Fe, Co, Ni, Zn; X = Cl, I, -OCH3) have been prepared, and their
magnetic and electrochemical properties have been probed to evaluate the effect of changing the identity
of the 3d metal ion. Electrochemistry of the clusters reveals several rhenium-based oxidation and reduction
processes, some of which result in cluster fragmentation. The richest electrochemistry was observed for
the iron congener, which exists as the Re(I)/Fe(III) cluster at the resting potential and exhibits six clear
one-electron reversible redox couples and two, closely spaced one-electron quasi-reversible processes.
The [{MnIICl}4{ReII(triphos)(CN)3}4] complex exhibits single molecule magnetism with a fast tunneling
relaxation process observed at H = 0 determined by micro-SQUID magnetization measurements. A
comparative evaluation of the magnetic properties across the series reveals that the compounds exhibit
antiferromagnetic coupling between the metal ions, except for [{NiIICl}4{ReII(triphos)(CN)3}4] that shows
ferromagnetic behavior. Despite the large ground-state spin value of [{NiIICl}4{ReII(triphos)(CN)3}4] (S =
6), only manganese congeners exhibit SMM behavior to 1.8 K.