Synthesis of Divalent Europium Borate via in Situ Reductive Techniques

A new
divalent europium borate, Eu­[B8O11(OH)4], was synthesized by two different in situ reductive methodologies
starting with a trivalent europium starting material in a molten boric
acid flux. The two in situ reductive techniques employed were the
use of HI as a source of H2 gas and the use of a Zn amalgam
as a reductive, reactive surface. While both of these are known reductive
techniques, the title compound was synthesized in both air and water
which demonstrates that strict anaerobic conditions need not be employed
in conjunction with these reductive methodologies. Herein, we report
on the structure, spectroscopy, and synthetic methodologies relevant
to Eu­[B8O11(OH)4]. We also report
on a europium doping study of the isostructural compound Sr­[B8O11(OH)4] where the amount of doped
Eu2+ ranges from 2.5 to 11%.