CdB10O14(OH)4·H2O with an unprecedented decaborate fundamental building block

Abstract: CdB10O14(OH)4·H2O has been synthesized under boric acid flux condition and characterized by single-crystal X-ray diffraction, infrared spectra, and UV–vis reflectance spectroscopy. It crystallizes in the monoclinic space group P21/n with a =7.7277(8), b =18.95(2), c =9.8616(10)Å, β=91.454(1)°, V =1443.7(3)Å. The structure consists of [B10O16(OH)4] layers of 9-membered borate rings enclosing Cd2+ cations. Adjacent borate layers are interconnected via hydrogen bonding to form a 3D network. It possesses an unprecedented decaborate fundamental building block B10O20. The structure details are discussed together with Sr[B6O9(OH)2]·3H2O, Pb[B8O11(OH)4], Pr[B8O11(OH)5], and Nd[B9O13(OH)4]·H2O, which have correlated FBBs. The band structure calculations show its direct energy band gap of ∼4.68eV, in consistent with the estimated value (4.77eV) from UV–vis. In addition, dielectric constants and refractive indexes are also calculated. [Copyright &y& Elsevier]