The borosulfates K₄[BS₄O₁₅(OH)], Ba[B₂S₃O₁₃], and Gd₂[B₂S₆O₂₄]

K₄[BS₄O₁₅(OH)], Ba[B₂S₃O₁₃], and Gd₂[B₂S₆O₂₄] were obtained by a new synthetic approach. The strategy involves initially synthesizing the complex acid H[B(HSO₄)₄] which is subsequently reacted in an open system with anhydrous chlorides of K, Ba, and Gd to the respective borosulfates and a volatile molecule (HCl). Furthermore, protonated borosulfates should be accessible by appropriate stoichiometry of the starting materials, particularly in closed systems, which inhibit deprotonation of H[B(HSO₄)₄] via condensation and dehydration. This approach led to the successful synthesis of the first divalent and trivalent metal borosulfates (Ba[B₂S₃O₁₃] with band-silicate topology and Gd₂[B₂S₆O₂₄] with cyclosilicate topology) and the first hydrogen borosulfate K₄[BS₄O₁₅(OH)]. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)