Ag[B(S2O7)2]: The First Transition Metal Borosulfate Featuring Disulfate Groups

Abstract

Hitherto, the structural diversity of transition metal borosulfates has been limited to B−O−S and B−O−B bridges. Ag[B(S2O7)2] represents the very first transition metal borosulfate featuring S−O−S bridges. The compound was synthesized solvothermally in oleum (65 % SO3) and crystallizes in a new structure type in P21/c (no. 14) with Z=4, a=950.7(4) pm, b=960.1(4) pm, c=1173.0(4) pm and β=98.350(11)°. The crystal structure comprises complex anions [B(S2O7)2]− – consisting of a central boron atom and two chelating disulfate groups – and charge balancing Ag+ ions. Vibrational spectroscopy confirms the presence of S−O−S bridges. A thermal decomposition from Ag[B(S2O7)2] towards Ag[B(SO4)2] was monitored by means of thermogravimetric analysis (TGA) and temperature programmed X-ray diffraction (TPXRD).