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Two‐Dimensional Uranyl Borates: From Conventional to Extreme Synthetic Conditions
Author(s) -
Hao Yucheng,
Kegler Philip,
AlbrechtSchmitt Thomas E.,
Wang Shuao,
Dong Qiang,
Alekseev Evgeny V.
Publication year - 2020
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201901239
Subject(s) - uranyl , chemistry , boron , crystallography , hydrothermal synthesis , hydrothermal circulation , crystal structure , ion , organic chemistry , seismology , geology
A systematic investigation of uranyl borates under different synthetic conditions resulted in five new 2D compounds, namely, (H 3 O)[(UO 2 )(BO 3 )], Li[(UO 2 )(BO 3 )] · (H 2 O), α‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ], β‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] and K 2.5 [(UO 2 ) 5 (BO 3 ) 2 O 2.5 (OH) 1.5 ] · (H 2 O) 2.5 . (H 3 O)[(UO 2 )(BO 3 )] and Li[(UO 2 )(BO 3 )] · (H 2 O) were obtained from hydrothermal reactions at 220 °C using the same mineralizer. Both materials possess the uranophane sheet topology with different symmetry of the unit cells. In the structure of (H 3 O)[(UO 2 )(BO 3 )] and Li[(UO 2 )(BO 3 )] · (H 2 O), UO 7 pentagonal bipyramids share edges and vertexes with four BO 3 planar triangles. α‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] and β‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] are polytypes. α‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] was synthesized from a high‐temperature solid‐state reaction under ambient pressure; whereas β‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] was obtained from a high‐temperature/high‐pressure (HT/HP) reaction. Both structures have an identical anion topology, but β‐K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] crystallizes in space group with higher symmetry. In K 2.5 [(UO 2 ) 5 (BO 3 ) 2 O 2.5 (OH) 1.5 ] · (H 2 O) 2.5 , which was obtained from a hydrothermal reaction, UO 7 polyhedra share vertexes and edges with two independent BO 3 triangles, forming the most complex uranyl borate layers among all five compounds. The different synthetic routes, novel topologies, thermal behavior and Raman spectra are discussed.