A spin-frustrated star-shaped heterotetranuclear CrIIIMnII3 species and its magnetic and HF-EPR measurements.

A tetranuclear complex [Cr(III)Mn(II)(3)(PyA)(6)Cl(3)] 1 containing pyridine-2-aldoximato monoanion, PyA, has been structurally and magnetochemically characterized. The compound is a rare example of a tetranuclear star-shaped metal topology containing pyridine-2-aldoximato ligands. Static magnetic studies have demonstrated very weak antiferromagnetic exchange interactions between the paramagnetic centers (S(Cr) = 3/2 and S(Mn) = 5/2) resulting in closely spaced low-lying levels, which undergo splitting and crossing. Preliminary high-field EPR measurements (20 < nu < 388 GHz) indicate the presence of zero-field splitting D of the order of 0.7 cm(-1).