Mechanism for hydrolysis of double six-membered ring tetraborate anion |
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| Authors: | Hongxia Zhou Fayan Zhu Hongyan Liu Wenqian Zhang Yongquan Zhou Chunhui Fang |
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| Institution: | 1. Qinghai Provincial Key Laboratory of New Light Alloys, Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming, Qinghai University, Xining, China;2. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China;3. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, China
Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Chinese Academy of Sciences, Xining, China |
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| Abstract: | B4O5(OH)42?] is a representative borate anion with a double six-membered ring structure, but there is limited knowledge about the hydrolysis mechanisms of B4O5(OH)42?]. Density functional theory-based calculations show that the tetraborate ion undergoes three-step hydrolysis to form B(OH)4?] and an ring intermediate, B3O2(OH)6?]. Other new structures, such as linear trimer, branched tetraborate, analogous linear tetraborate, are observed, but they are not stable in neutral systems and change to ring structures. B3O2(OH)6?] hydrolyzes to B(OH)4?] and B(OH)3] in the last two steps. The structure of borate anion and the coordination environment of the bridge oxygen atom control the hydrolysis process. B4O5(OH)42?] always participates in the hydrolysis reaction, even with a decrease in concentration. B3O3(OH)4?], B(OH)4?], and B(OH)3] have different roles in “water-poor” and “water-rich” zones. Concentration and pH of solution are the key factors that affect the distribution of borate ions. |
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| Keywords: | DFT hydrolysis mechanism polymerization tetraborate anion |
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