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

Abstract

The crystal structure of the low-temperature modification of Ba(BF4)2(H2O)3, barium bis(tetrafluoridoborate) trihydrate, was determined at 150 K. In contrast to the room-temperature modification, which crystallizes in the space group C2221 [a = 7.1763 (6), b = 18.052 (2), c = 7.1631 (6) Å, V = 927.93 (15) Å3 at 300 K, Z = 4; Charkin et al. (2023). J. Struct. Chem. 64, 253–261], the low-temperature phase is monoclinic, space group P21 [a = 7.0550 (4), b = 7.1706 (3), c = 9.4182 (6) Å, β = 109.295 (7) o , V = 449.68 (5) Å3, Z = 2]. The structure of the low-temperature modification of Ba(BF4)2(H2O)3 features O—H...F and O—H...O hydrogen bonding between water molecules and BF4 − anions. One of the coordinating water molecules in the low-temperature modification is disordered over two sets of sites.