ChemInform Abstract: HP‐KB₃O₅ Highlights the Structural Diversity of Borates: Corner‐Sharing BO₃/BO₄ Groups in Combination with Edge‐Sharing BO₄ Tetrahedra.

Abstract

The new high pressure compound KB3O5 is prepared from a stoichiometric mixture of K2CO3 and H3BO3 [1.) 900 °C, 12 h; 2.) 3 GPa, 600 °C, 10 min].

Identifying the Molecular Edge Termination of Exfoliated Hexagonal Boron Nitride Nanosheets with Solid-State NMR Spectroscopy and Plane-Wave DFT Calculations

“…The sharp, well-resolved signals with an diso of 1.2 ppm (brown fit) and 2.6 ppm (purple fit) correspond to four-coordinate boron environments, likely coordinated by nitrogen and multiple hydroxyl groups/bridging oxygen atoms. 79,[90][91][92] The relatively small CQ of 1 MHz and low chemical shift confirms there is tetrahedral symmetry at these boron sites. All of the 11 B spectral fits and peak assignments are validated by periodic plane-wave DFT calculations (see below).…”

Toward the Coordination Fingerprint of the Edge-Sharing BO4 Tetrahedra

“…At first, the high-pressure (HP) condition appears to be a key condition to form the B 2 O 6 units. Indeed, the majority of borates with (es-)­BO 4 tetrahedra, discovered by Huppertz et al, were synthesized at HP and high temperature (HT), − with the first one published in 2002 . Similarly, α-Ba 3 [B 10 O 17 (OH) 2 ] was synthesized at HP through hydrothermal reactions at 500 °C and 1000 bar .…”

“…The B–O blocks may be linked to two external nodes [Co 7 B 24 O 42 (OH) 2 ·2H 2 O or BaAlBO 4 ], four external nodes [HP-MB 2 O 4 where M = Ni, β-Fe, and Co, M 4 B 6 O 15 where M = Dy, and Ho, HP-La 3 B 6 O 13 (OH) 6 , α-M 2 B 4 O 9 where M = Y, Sm, Eu, Gd, Tb, and Ho, KZnB 3 O 6 , Ba 4 Na 2 Zn 4 B 18 O 36 , and Li 4 Na 2 CsB 7 O 14 ], or a combination of two nodes from the common edge and two external nodes (α-Ba 3 [B 10 O 17 (OH) 2 ]). The case where all six available nodes are linked to B–O blocks is encountered in HP-CsB 5 O 8 , HP-MB 3 O 5 where M = K, Rb, and Tl, (NH 4 ), Cs 0.4 (H 3 O) 0.6 , and β-CsB 9 O 14 . LT-KSBO is the first material presenting the unique structural feature where no B–O block is linked to the B 2 O 6 unit.…”

Coordination-Directed Structural Modulation and Design of Deep-Ultraviolet Nonlinear Optical Materials

“…The connection between two 6-membered rings has two styles, sharing the edge composed of B–O bonds (edge-sharing) and sharing the B atom of [BO 4 ] tetrahedron (corner-sharing), to form bicyclic pentaborate anions. Modules of bicyclic pentaborate groups in ternary borates, B 5 O 14 in MB 4 O 7 (M = Ca, Sr, and Pb), B 5 O 14 in β-MB 4 O 7 (M = Fe, Co, and Zn), B 5 O 11 in HP-CsB 5 O 8 , B 5 O 13 in HP-CaB 2 O 4 , B 5 O 12 in CaB 2 O 4 , B 5 O 11 in Na 2 B 4 O 7 , B 5 O 10 in α-Na 2 B 6 O 10 , are shown in Figure . − ,− The bicyclic pentaborate groups involve in seven kinds of modules, according to the inorganic crystal structure database. In order to distinguish the edge-sharing and corner-sharing, the shorthand notations were produced based on the representation and the descriptor introduced by Burns et al which take linkage information between borate polyhedra into consideration .…”

“…The boron atom can form two-coordinated linear [BO 2 ], three-coordinated triangular [BO 3 ], or four-coordinated tetrahedral [BO 4– x F x ] ( x = 0–4) in borate crystals. − Then, the B–O/F anionic groups share corners or/and edges with each other to generate 0-dimensional (0D) isolated clusters, 1D infinite chains, 2D layers, and 3D networks. ,, Among such abundant fundamental building blocks, oxygen atoms usually bond with two boron atoms or less. However, there are still oxygen atoms bonding with more than two boron atoms in some borates, such as B 2 O 3 , SrB 6 O 10 ·4H 2 O, MB 4 O 7 (M = Ca, Sr, and Pb), HP-KB 3 O 5 (HP, high-pressure), HP-CsB 5 O 8 , A 3 B 6 O 10 X (A = K, Na, Rb/Na, and K/Na; X = Cl and Br), MB 5 O 7 F 3 (M = Mg, Ca, Sr, Pb, and Cd), and so forth. − Among them, there is no lack of NLO materials with superior performance in UV and deep-UV regions, while it is wondered how the coordination environment of oxygen anions influences electronic structures and NLO effects.…”