Synthesis, Crystal Structure, Vibrational Spectroscopy and Thermal Behavior of the First Alkali Metal Hydrated Hexaborate:K2[B6O9(OH)2]

✍ Scribed by Hong-Juan Li; Zhi-Hong Liu; Li-Mei Sun

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 72 KB
• Volume: 25
• Category: Article
• ISSN: 0256-7660
• DOI: 10.1002/cjoc.200790211

✦ Synopsis

New hydrated potassium hexaborate K 2 [B 6 O 9 (OH) 2 ] has been synthesized under mild solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR, Raman spectra and DTA-TG. It crystallizes in the monoclinic system with space group P2 1 /n, a＝0.9036(2) nm, b＝0.66052( 18) nm, c＝1.5997(4) nm, β＝91.862(4)°, V＝0.9543(4) nm 3 and Z＝4. Its crystal structure consists of K-O polyhedra and 1-D stepped polyborate chains constructed by new [B 6 O 9 (OH) 2 ] 2-fundamental building blocks. 1-D polyborate chains contain 3,8-membered boron rings. Adjacent chains are further linked via H-bonding interactions into 2-D layers. The K ＋ cations reside not only between the layers but also in the 8-membered boron rings of the chains, compensating the negative charges of the borate chains and holding the layers together into the 3-D structure through bonding with oxygen atoms of the chains.