Two New Mixed Metal Borates Made of Mg(B6O7(OH)6)2 and B8O14(OH)4 Cluster Units

Abstract

Two new mixed metal borates, Li2[Mg(B6O7(OH)6)2]·2H2O (1) and Li4Ca2[B8O12(OH)4]2·3H2O (2) have been made under solvothermal conditions and characterized by FT-IR spectroscopy, powder X-ray diffraction, single crystal X-ray diffraction and thermogravimetric analysis, respectively. Crystal data for 1: triclinic, \({P_{\bar 1}}\), a = 6.9415(4) A, b = 9.1626(5) A, c = 9.4540(6) A, α = 71.697(6)o, β = 88.431(5)o, γ = 68.409(5)o, Z = 1. Crystal data for 2: monoclinic, C2/c, a = 19.8507(5) A, b = 6.7560(2) A, c = 20.0454(5) A, β = 93.985(2)o, Z = 4. In structure 1, the structural building unit (SBU), sandwich type [Mg(B6O7(OH)6)2]2−, connects adjacent six same ones to form a 2-D layer via Li-based polyhedra in the bc plane and further link by hydrogen bonding to form 3-D supramolecular network. In the structure 2, the SBUs, [B8O14(OH)4]8−, link together to produce a 2-D layer with 13-membered ring (MR) windows along the bc-plane. Such layers are further linked by Li-based polyhedra to form a 3-D framework.