Special _∞¹[OPb₂] Chains and _∞¹[O₂Pb₃] Ribbons Based on OPb₄ Anion-Centered Tetrahedra in Pb₂(O₄Pb₈)(BO₃)₃Br₃ and Pb₂(O₈Pb₁₂)(BO₃)₂Br₆

Abstract

The structures of two new lead-containing oxyborate bromines, Pb2(O4Pb8)(BO3)3Br3 (1) and Pb2(O8Pb12)(BO3)2Br6 (2), are determined by single-crystal X-ray diffraction for the first time. Both of them crystallize in the space group C2/c of the monoclinic crystal system. Although the two compounds have the same type of fundmental building units (FBUs), the OPb4 anion-centered tetrahedra and BO3 triangles, they exhibit different connection modes. Compound 1 consists of single ∞(1)[OPb2] chains, while compound 2 possesses ∞(1)[O2Pb3] ribbons. Interestingly, large Br atoms profoundly influence the conformation of polyions based on the OPb4 anion-centered tetrahedra, resulting in single ∞(1)[OPb2] chains linked up by finite zweier chains with four OPb4 tetrahedra via the opposite edges in compound 1 and ∞(1)[O2Pb3] ribbons with sequential condensation of OPb2 chains in compound 2. A detailed description of the effect of large Br atoms on the conformation of polyions is discussed. IR spectroscopy, UV-vis-NIR diffuse reflectance spectroscopy, and thermal analysis are also performed on the reported materials.