Hygroscopic La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O: Insight into the evolution of borate fundamental building blocks

• Published in: Journal of solid state chemistry 2013-10, Vol.206
• Main Authors: Zhao, Biao-Chun, Sun, Wei, Ren, Wei-Jian, Huang, Ya-Xi, Li, Zucheng, Pan, Yuanming, Mi, Jin-Xiao
• Format: Article
• Language: English
• Subjects: ABSORPTION; BORATES; FOURIER TRANSFORMATION; HYGROSCOPICITY; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LANTHANUM; MOLECULAR DYNAMICS METHOD; MONOCLINIC LATTICES; MONOCRYSTALS; NITRATES; NITROGEN OXIDES; ROTATION; SPACE GROUPS; THERMAL ANALYSIS; X RADIATION; X-RAY DIFFRACTION
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2013.07.032

Borates have exceptionally diverse fundamental building blocks (FBBs), but factors controlling the formation of borate FBBs are poorly understood. The title compound La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O crystallizes in the space group P2{sub 1}/n with a=6.5396(12) Å, b=15.550(3) Å, c=10.6719(19) Å, β=90.44(1)° and Z=4 at 173(2) K. Its structure has been refined from single-crystal X-ray diffraction data to R{sub 1}=0.049 (for 2465) and wR{sub 2}=0.173 (for 2459 I>2σ(I)). This structure analysis and first-principles calculations show that the change of the FBB from 3Δ2□ in the title compound to 2Δ3□ in La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O is accompanied by a rotation of the NO{sub 3} group. FTIR, Rietveld and thermal analysis results show that the hygroscopic title compound is partially changed to La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O, with the conversion of [BO{sub 3}] to [BO{sub 3}(H{sub 2}O)] by water absorption. - Graphical abstract: The change of fundamental building blocks from La[B{sub 5}O{sub 8}(OH)]NO{sub 3}·2H{sub 2}O to La[B{sub 5}O{sub 8}(OH)(H{sub 2}O)]NO{sub 3}·2H{sub 2}O is accompanied by a rotation of the NO{sub 3} group . Display Omitted - Highlights: • Synthesis of a new hydrous lanthanum polyborate nitrate. • Single-crystal XRD structure with the 3Δ2⎕ FBB and an oriented NO{sub 3} group. • DFT calculations locate the H positions in three lanthanide polyborate nitrates. • Rietveld, FTIR and DFT results show hygroscopicity changes the FBBs.