Bi-, Tri- and Tetranuclear Rare Earth Metal Complexes with Arylboronic Acids: Synthesis, Structure, and Photoluminescent Properties

Polynuclear complexes of rare earth metals Sc, La, Nd, Sm, Er, Yb with anthracenylboronic acid (AntB(OH)2) and pyrenylboronic acid (PyrB(OH)2) as a ligands were synthesized by reactions of cyclopentadienyl metal complexes LnCp3 with the corresponding arylboronic acid. X-ray structural analysis of Nd, Sm and Er complexes revealed that obtained compounds are dimers, in which each metal atom is coordinated by two terminal Cp ligands and two bridging arylboronic acid fragments. Scandium complex is a tetranuclear compound that contains four anthracenylboronic acid ligands and four Cp-ligands. Lanthanum complex is a trinuclear coordination compound comprising three La3+ cations linked by three bridging anthracenylboronate anions. Photoluminescence spectra of Sc and La derivatives in the solid state showed excimer ligand emission in the region 350–650 nm. The Nd, Er and Yb complexes exhibited NIR metal-centered photoluminescence of the corresponding metal ion.