The crystal structures of the potassium hydrogen monofluorophosphates, KHPO₃F and K₃[H(PO₃F)₂], and the α modification of RbHPO₃F

Abstract

Three new hydrogen monofluorophosphates, KHPO₃F (I), K₃[H(PO₃F)₂] (II), and α-RbHPO₃F (III), were crystallographically characterized with single crystal X-ray analysis at 180 K. The compound I is monoclinic, space group P2₁ with a = 7.273(1), b = 14.086(3), c = 7.655(2) Å, β = 90.13(3), Z = 8, and R₁ and wR₂ factors of 0.0214 and 0.0395, respectively. II crystallizes in the monoclinic space group C2/c with a = 7.973(3), b = 11.635(4), c = 9.688(4) Å, β = 113.52(4), Z = 4, and R₁ and wR₂ factors of 0.0581 and 0.1615, respectively. III is monoclinic with the P2₁/n space group, a = 7.465(2), b = 15.551(8), c = 7.563(4) Å, β = 105.38(5), Z = 8, and R₁ and wR₂ factors of 0.0365 and 0.0694, respectively. I and III include O–H···O hydrogen bonding between the HPO₃F tetrahedra to form branched spiral chains (I) or tetramers (III), respectively. In the structure of II, dimeric units are formed by a symmetrically disordered hydrogen bond between the PO₃F tetrahedra. Both O and F atoms participate in cation coordination in all three structures, whereas only O atoms are involved in hydrogen bonding.