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

摘要

Four new lead(ii) or bismuth(iii) selenites and a tellurite, namely, Pb _3(TeO _3)Cl _4, Pb _3(SeO _3) _2Br _2, Pb _2Cd _3(SeO _3) _4I _2(H _2O), Pb _2Ge(SeO _3) _4 and BiFe(SeO _3) _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 Pb _3(TeO _3)Cl _4 features a three-dimensional (3D) lead(ii) chloride network with tellurite anions filling in the 1D tunnels of Pb 4 4-member rings (MRs) along the c-axis. Pb _3(SeO _3) _2Br _2 contains a 3D network composed of lead(ii) selenite layers interconnected by bromide anions. Pb _2Cd _3(SeO _3) _4I _2(H _2O) 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. Pb _2Ge(SeO _3) _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(SeO _3) _3 is built on the 3D anionic framework of ion(iii) selenite with the bismuth(iii) ions located at its Fe _6Se _6 12-MR tunnels. Pb _3(TeO _3)Cl _4 (Pna2 _1) is polar and BiFe(SeO _3) _3 (P2 _12 _12 _1) is noncentrosymmetric. Powder second-harmonic generation (SHG) measurements using 1064 nm radiation indicate that BiFe(SeO _3) _3 exhibits a weak SHG efficiency of about 0.2 × KH _2PO _4 (KDP). Magnetic property measurements for BiFe(SeO _3) _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.