SYNTHESIS AND CRYSTAL STRUCTURE OF TWO NEW TETRAFLUOROBORATE CRYSTALLOHYDRATES M(BF4)2·3H2O, M = Sr, Ba

Low-temperature modification of Ba(BF4)2(H2O)3

“…It is noteworthy that at 280 K the LT modification remains unchanged, with significantly enlarged unit-cell parameters (Table 2). At 300 K, an orthorhombic cell was indexed with 100% of all observed reflections and with similar lattice parameters as given by Charkin et al (2023). Thus, we can conclude that the ordered oC Ð mP phase transition of Ba(BF 4 ) 2 (H 2 O) 3 (accompanied by twinning of the monoclinic LT phase) occurs between 280 and 300 K.…”

“…Ba-F bond lengths range from 2.698 (7) to 3.035 (8) A ˚, and Ba-O bond lengths from 2.777 (9) to 2.821 (8) A ˚(for ordered water molecules). The spread of Ba-F distances in LT-Ba(BF 4 ) 2 (H 2 O) 3 is greater than for the to 2.843 (17) A ˚; Charkin et al, 2023]. The B-F distances in LT-Ba(BF 4 ) 2 (H 2 O) 3 are in normal ranges, 1.352 (12)-1.406 (16) A ˚.…”

“…The RT unit cell in space group C222 1 with a = 7.1763 (6) A ˚, b = 18.052 (2) A ˚, c = 7.1631 (6) A ˚ (Charkin et al, 2023) is related to the LT mP unit cell in P2 1 by the transformation -a, -c, 1/2a + 1/2b, suggesting a translationengleiche symmetry relationship of index 2 (Mu ¨ller, 2013). Considering the significant difference in crystal density for both modifications (2.59 g cm-3 for the RT modification at 300 K, 2.63 g cm À3 for the LT modification at 280 K, and 2.59 g cm À3 at 150 K), it can be assumed that the formation of a structure with more effective packing is the driving force of the observed phase transition.…”

Search and Synthesis of New Fluorine-Containing Borates of Mono- And Divalent Metals

“…Для их синтеза используется преимущественно ампульные методы синтеза. Нами получены [2] два новых фторобората, M(BF4)23H2O, M = Sr, Ba методом выпаривания раствора. Кроме того, мы представляем сравнительно новый способ получения фтороборатов одновалентных металлов путем фторирования боратов с использованием NH4BF4 в открытых условиях при невысоких температурах, до 120 °C.…”