[O2Pb3]2(BO3)Br: An Oxidoborate Oxide Bromide with the ∞1[O2Pb3] Double Chains Based on Edge-sharing OPb4 Tetrahedra

Through extensive research on the PbO / PbBr 2 / B 2 O 3 system, a new single crystal of yellow lead-containing oxyborate bromine, [O 2 Pb 3 ] 2 (BO 3 )Br, was grown from the melt. It crystallizes in the centrosymmetric space group Cmcm (no. 63) of the orthorhombic system with the following unit cell dimensions: a = 9.5748(8) Å, b = 20.841(2) Å, c = 5.7696(5) Å, and Z = 4. The whole structure is characterized by an infinite one-dimensional (1D) ∞ 1 [O 2 Pb 3 ] double chain, which is based on the OPb 4 oxocentered tetrahedra and considered as the derivative of the continuous sheet of OPb 4 tetrahedra from the tetragonal modification of α-PbO. The 1D ∞ 1 [O 2 Pb 3 ] double chains are further bridged by the BO 3 units through common oxygen atoms to form two-dimensional (2D) ∞ 1 [[(O 2 Pb 3 )(BO 3 )] layers, with Br atoms situated between the layers. IR spectroscopy, UV/Vis/NIR diffuse reflectance spectroscopy, and thermal analysis were also performed on the reported material.