Synthesis and structural characterization of an unprecedented nonmetal cation polyborate salt containing two different "isolated" polyborate anions: [H2en]2[B4O5(OH)4][B7O9(OH)5]·3H2O (en = H2NCH2CH2NH2).

ABSTRACT

The nonmetal cation polyborate salt of stoichiometry [H(2)en](2)[B(11)O(18)(OH)]·7H(2)O is obtained from the reaction of 1,2-diaminoethane and boric acid (15 ratio) in H(2)O/MeOH. An X-ray crystallographic study of the product reveals that the polyborate moiety is composed of two isolated hydrated polyborate anions [B(4)O(5)(OH)(4)](2-) and [B(7)O(9)(OH)(5)](2-). The structure is templated by the cations with the anions forming a supramolecular H-bonded network, augmented by additional H-bonds involving the waters of crystallization and the cations.