The High‐Pressure Borate HP‐(NH₄)B₃O₅

Abstract

The high-pressure ammonium triborate HP-(NH 4 )B 3 O 5 was synthesized in a high-pressure/high-temperature experiment at 3 GPa and 600°C. It crystalizes in the monoclinic space group C2/c (No. 15) with the parameters a = 981.0(2), b = 880.2(2), c = 922.2(2) pm, β = 103.8(1)°, V = 0.7735(3) nm 3 , Z = 8, R 1 = 0.0436, and wR 2 = 0.1059 (all data). The compound is built up from ribbons of interconnected corner-and edge-sharing BO 4 tetrahedra that are linked by planar 2753 groups to form a three-dimensional structure. The ammonium ions are situated in channels, forming four hydrogen bonds to oxygen of the boron oxygen network. The structure is a substitutional variant of the compounds HP-MB 3 O 5 , (M = K, Rb) and HP-Cs 1-x (H 3 O) x B 3 O 5 (x = 0.5-0.7). The collected IR and Raman spectra of HP-(NH 4 )B 3 O 5 show great similarities to the spectra of the analogous phases.through single-crystal X-ray diffraction, IR and Raman spectroscopy. Results and Discussion Crystal StructureThe structure of HP-(NH 4 )B 3 O 5 is depicted in Figure 1 exhibiting great similarities to HP-MB 3 O 5 (M = K, Rb) [3,4] and HP-Cs 1-x (H 3 O) x B 3 O 5 (x = 0.5-0.7) [6] due to a similar boron

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 .…”

Structure, Thermal Behavior, and Vibrational Spectroscopy of the Silver Borate AgB3O5

“…In detail, a special part of the Cs + cations in the compound HP‐Cs 1– x (H 3 O) x B 3 O 5 ( x = 0.5–0.7) were substituted by H 3 O + cations to yield the first borate containing oxonium ions 7. Owing to their comparable ionic radii, the implementation of oxonium, ammonium8 or thallium9 cations led to substitution variants or isotypic phases of HP‐KB 3 O 5 and HP‐RbB 3 O 5 . At this point, several interesting questions opened up: (1) Which chemical composition and which structure type would be adopted with the smaller silver ion Ag + in this series of high‐pressure pseudo‐alkali‐metal borates?…”

The High‐Pressure Polymorph of Ca4Te5O14 and the Mixed‐Valent Compound Ca13TeVI2/3TeIV3.75O15(BO3)4(OH)3

“…Side‐reactions with the boron nitride crucibles under these harsh conditions of pressure and temperature are not uncommon. For example, the formation of HP‐(NH 4 )B 3 O 5 has been observed several times in different chemical reactions although the reaction mixtures employed did not contain any nitrogen source . Also, the formation of the borate‐germanate Ce 6 (BO 4 ) 2 Ge 9 O 22 originated in a side‐reaction in which GeO 2 reacted with the boron nitride crucible in a still unsolved reaction mechanism .…”