Highly oxidized states of phthalocyaninato terbium(III) multiple-decker complexes showing structural deformations, biradical properties and decreases in magnetic anisotropy.

: Herein we present a comprehensive study of highly oxidized multiple-decker complexes composed of Tb(III) and Cd(II) ions and two to five phthalocyaninato ligands, which are stabilized by electron-donating n -butoxy groups. From X-ray structural analyses, all the complexes become axially compressed upon ligand oxidation, resulting in bowl-shaped distortions of the ligands. In addition, unusual coexistence of square antiprism and square prism geometries around metal ions was observed in +4 e charged species. From paramagnetic 1 H NMR studies on the resulting series of triple, quadruple and quintuple-decker complexes, ligand oxidation leads to a decrease in the magnetic anisotropy, as predicted from theoretical calculations. Unusual paramagnetic shifts were observed in the spectra of the +2 e charged quadruple and quintuple-decker complexes, indicating that those two species are actually unexpected triplet biradicals. Magnetic measurements revealed that the series of complexes show single-molecule magnet properties, which are controlled by the multi-step redox induced structural changes.