Ban+2Znn(BO3)n(B2O5)Fn (n = 1, 2): new members of the zincoborate fluoride series with two kinds of isolated B–O units
Two new members of zincoborate fluoride series Ban+2Znn(BO3)n(B2O5)Fn (n = 1, 2), namely, Ba3Zn(BO3)(B2O5)F and Ba4Zn2(BO3)2(B2O5)F2 were firstly synthesized as high-quality single crystals via a high-temperature solution method by adjusting the molar ratios of reactants. They were structurally determined by single-crystal X-ray diffraction and their structures can be regarded as three dimensional (3D) framework stacking of 2∞[Zn2B6O16]10− layers for Ba3Zn(BO3)(B2O5)F and 2∞[Zn2B4O8O5/2O1/3]17/3− layers for Ba4Zn2(BO3)2(B2O5)F2. To the best of our knowledge, the two title compounds are the first examples of two kinds of isolated B–O groups that coexist in one zincoborate halide. The structure comparisons were carried out among all the available anhydrous-zincoborates, and it is interesting to conclude that about 80% of zincoborates contain isolated B–O clusters and notably the molar ratio of cation/boron (A/B) affects the polymerization of isolated B–O configuration. What's more, the first-principles calculations, infrared spectra, and UV-vis-NIR diffuse reflectance spectra of title compounds have also been performed.