Syntheses, crystal structures and properties of new lead(ii) or bismuth(iii) selenites and tellurite

Abstract

Four new lead(II) or bismuth(III) selenites and a tellurite, namely, Pb₃(TeO₃)Cl₄, Pb₃(SeO₃)₂Br₂, Pb₂Cd₃(SeO₃)₄I₂(H₂O), Pb₂Ge(SeO₃)₄ and BiFe(SeO₃)₃, have been prepared and structurally characterized by single crystal X-ray diffraction (XRD) analyses. These compounds exhibit five different types of structures. The structure of Pb₃(TeO₃)Cl₄ features a three-dimensional (3D) lead(II) chloride network with tellurite anions filling in the 1D tunnels of Pb₄ 4-member rings (MRs) along the c-axis. Pb₃(SeO₃)₂Br₂ contains a 3D network composed of lead(II) selenite layers interconnected by bromide anions. Pb₂Cd₃(SeO₃)₄I₂(H₂O) is a 3D structure based on 2D cadmium(II) selenite layers which are further connected by 1D lead(II) iodide ladder chains with lattice water molecules located at the 1D tunnels of the structure. Pb₂Ge(SeO₃)₄ features a 3D framework constructed by the alternate arrangement of lead(II) selenite layers and germanium(IV) selenite layers in the [100] direction. The structure of BiFe(SeO₃)₃ is built on the 3D anionic framework of ion(III) selenite with the bismuth(III) ions located at its Fe₆Se₆ 12-MR tunnels. Pb₃(TeO₃)Cl₄ (Pna2₁) is polar and BiFe(SeO₃)₃ (P2₁2₁2₁) is noncentrosymmetric. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate that BiFe(SeO₃)₃ exhibits a weak SHG efficiency of about 0.2 × KH₂PO₄ (KDP). Magnetic property measurements for BiFe(SeO₃)₃ show a dominant antiferromagnetic interaction with weak spin-canting at low temperatures. IR, UV-vis and thermogravimetric, as well as electronic structure calculations were also performed.