The first magnesium, manganese, cobalt, nickel, and zinc borosulfates were synthesized employing solvothermal conditions starting from the superacid H[B(HSO)] and the respective metal powders (Mg, Ni, Zn) or oxides (MnO, CoO). α- M[BO(SO)] ( M = Mg, Mn, Co, Ni, Zn) crystallize isotypically in a new structure type in P3̅ (No. 147) with Z = 1, a = 793.59(4)-810.86(9) pm, and c = 743.98(4)-775.09(9) pm. The oligomeric anion comprises unprecedented dimeric open-branched quadruple tetrahedra { oB, 4 t}[BO(SO)], which are connected via MO dimers to give a three-dimensional network. Upon mild heating, we observed a phase change from α-Mg[BO(SO)] to β-Mg[BO(SO)], yielding a further new structure type in P3̅ (No. 147) with Z = 3, a = 1391.96(6) pm, and c = 748.54(3) pm. The reaction of MgB with SO yields Mg[B(SO)] crystallizing in C2/ c with Z = 4, a = 1744.28(10) pm, b = 531.45(3) pm, c = 1429.06(8) pm, and β = 126.323(2)° showing phyllosilicate topology. UV/vis spectroscopy on α- TM[BO(SO)] ( TM = Co, Ni) confirms the valence state of the TM and reveals that borosulfates are weakly coordinating host structures. Structure relationships between the presented crystal structures and similar borophosphates are shown. The results of vibrational spectroscopy as well as magnetic and thermal measurement investigations are discussed.

The very first thorough investigation of the rare earth borosulfates RE2[B2(SO4)6] with RE = Y, La–Nd, Sm, Eu and Tb–Lu focusses on synthetic aspects and especially optical properties.

Increaseds ynthetic control in borosulfate chemistry leads to the accesso fv arious new compounds. Herein, the polymorphism of phyllosilicate-analogous borosulfates is unraveled by adjustingt he oleum (65 %S O 3)c ontent.T he new polymorphs b-Mg[B 2 (SO 4) 4 ]a nd a-Co[B 2 (SO 4) 4 ]b oth consisto fs imilarl ayers of alternating borate and sulfate tetrahedra, but differ in the position of octahedrally coordinated cations. The a-modificationc omprises cations between the layers, whereas in the b-modification cations are embedded within the layers. With this new synthetica pproach, phase-pure compounds of the respective polymorphs a-Mg[B 2 (SO 4) 4 ]a nd b-Co[B 2 (SO 4) 4 ]w ere also achieved. Tanabe-Sugano analysiso ft he Co 2 + polymorphs reveal weak ligand field splitting and give insights into the coordinationb ehavior of the two-dimensional borosulfate anions fort he first time.D FT calculations confirmed previous in silico experiments and enabled an assignment of the polymorphs by comparing the total electronic energies. The compounds are characterized by single-crystal XRD, PXRD, FTIR, and UV/Vis/ NIR spectroscopy,t hermogravimetric analysis (TGA), and density functional theory (DFT) calculations.

Various different possible connection patterns of sulfate and borate tetrahedra enable a vast structural diversity in borosulfates, a rather new class of silicate-analogous compounds. Here we unravel a direct relationship from S−O−S to B−O−S to B− O−B bridges for the first time in borosulfate chemistry. Solvothermal synthesis in pure oleum (65% SO 3 ) yielded the first alkaline earth metal borosulfate comprising S−O−S bridges: Ba[B(S 2 O 7 ) 2 ] 2 (I2/a, Z = 4, a = 1160.77(9) pm, b = 891.44(7) pm, c = 2130.26(19) pm, β = 104.0341(17)°) contains molecular [B(S 2 O 7 ) 2 ] − anions of a central boron atom and two chelating disulfate groups. By using equal amounts of sulfuric acid and oleum solely B−O−S bridges were obtained in Ba[B 2 (SO 4 ) 4 ] (Pnna, Z = 4, a = 1279.08(18) pm, b = 1280.0(2) pm, c = 731.70(11) pm) featuring one-dimensional ∞ 1 [B(SO 4 ) 4/2 ] − chains. The thermal analysis on Ba[B(S 2 O 7 ) 2 ] 2 revealed the conversion from S−O−S bridges to B−O−S bridges in Ba[B 2 (SO 4 ) 4 ] and to B−O−B bridges in Ba[B 2 O(SO 4 ) 3 ] by a successive release of SO 3 . Thus, BaO−B 2 O 3 −SO 3 is the first quaternary system for borosulfates uniting all three possible connection patterns enabling us to understand the fascinating but systematic chemistry in such systems. Both new compounds were also characterized by means of X-ray powder diffraction, electrostatic calculations, and infrared spectroscopy assisted by density functional theory (DFT).

The first strontium borosulfate Sr[B2O(SO4)3] and a novel lead borosulfate Pb[B2O(SO4)3] were obtained by solvothermal reaction of the respective anhydrous metal chlorides MCl2 (M = Sr, Pb) with H[B(HSO4)4] at 300 °C. The crystal structure of Sr[B2O(SO4)3] [Pnma, Z = 4, a = 1657.38(27) pm, b = 1203.68(19) pm, c = 439.484(8) pm] is isotypic with Ba[B2O(SO4)3] and consists of chains, built up by three membered rings of two borate tetrahedra and a sulfate tetrahedron. These rings are further connected via corner‐sharing sulfate tetrahedra and hence can be classified as loop branched zweier double chains. Pb[B2O(SO4)3] crystallizes in a new structure type [P21/m, Z = 2, a = 440.00(2) pm, b = 1210.19(5) pm, c = 860.43(4) pm, β = 103.587(2) °] closely related to Sr[B2O(SO4)3]. Both structures share the common supergroup Pnmm and basically differ by the orientation of adjacent anionic chains. The coordination surrounding of Pb2+ indicates a lone pair activity and DFT calculations confirmed a weak polarizability. Moreover, the compounds were characterized by electrostatic calculations, vibrational spectroscopy and thermal analysis and broaden the structural and chemical diversity of borosulfates.