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• 作者：Colin D. McMillen ; Joseph W. Kolis
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：July 18, 2011
• 年：2011
• 卷：50
• 期：14
• 页码：6809-6813
• 全文大小：786K
• 年卷期：v.50,no.14(July 18, 2011)
• ISSN：1520-510X

文摘

The synthesis and structure of the isostructural acentric compounds Sr₃Be₂B₅O₁₂(OH) (1) and Ba₃Be₂B₅O₁₂(OH) (2) are reported for the first time. These compounds crystallize in the space group R3m, and the unit cell parameters are a = 10.277(15) 脜 and c = 8.484(17) 脜 for 1 and a = 10.5615(15) 脜 and c = 8.8574(18) 脜 for 2. The structures consist of a network of [Be₂B₄O₁₂(OH)] units interwoven with a network consisting of MO₉ polyhedra (M = Sr, Ba) and BO₃ triangles and exemplify how acentric building blocks such as [BO₃]^3-, [BO₄]^5-, and [BeO₄]^6- can be especially suitable to build noncentrosymmetric long-range structures. Both networks are centered on the 3-fold rotation axis and present themselves in alternating fashion along [001]. Acentricity is imparted by the alignment of the polarities of BO₃ and BeO₄ environments. Infrared spectroscopy has been used to confirm the local geometries of B and Be, as well as the presence of hydroxide in the crystal structure. Another interesting feature of these compounds is the presence of disorder involving Be and B at the tetrahedral Be site. The degree of the disorder has been confirmed by observing a noticeable shortening of average Be鈥揙 bond distances.