Exploring Main Group Metal Borosulfates: Similarities and Differences of Two New Borosulfates <i>M</i>[B₂O(SO₄)₃] (<i>M</i> = Sr, Pb)

Abstract

The first strontium borosulfate Sr[B 2 O(SO 4 ) 3 ] and a novel lead borosulfate Pb[B 2 O(SO 4 ) 3 ] were obtained by solvothermal reaction of the respective anhydrous metal chlorides M Cl 2 ( M = Sr, Pb) with H[B(HSO 4 ) 4 ] at 300 °C. The crystal structure of Sr[B 2 O(SO 4 ) 3 ] [ Pnma, Z = 4, a = 1657.38(27) pm, b = 1203.68(19) pm, c = 439.484(8) pm] is isotypic with Ba[B 2 O(SO 4 ) 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[B 2 O(SO 4 ) 3 ] crystallizes in a new structure type [ P 2 1 / 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[B 2 O(SO 4 ) 3 ]. Both structures share the common supergroup Pnmm and basically differ by the orientation of adjacent anionic chains. The coordination surrounding of Pb 2+ 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.