Crystal Structure of Cupric Fluoride Dihydrate at 298°K

Abstract

A neutron determination of the crystal structure of cupric fluoride dihydrate at 298°K has been made. The structure consists of puckered sheets of nearly square CuF₂O₂ groups, linked together by hydrogen bonds of 2.715±6 A, with the sheets connected by longer Cu–F bonds to form distorted octahedra around the Cu²⁺ ions. Dimensions within the octahedra are, two Cu–O distances of 1.941±5, two Cu–F of 1.898±8 and two Cu–F of 2.465±6 A. The long F–Cu–F axis is inclined at 7½° from the normal to the plane containing the remaining CuF₂O₂ group of the octahedron. The Cu–O bonds bisect the H–O–H angle of 115.5±0.4°. The O–H bond is 0.980±7 A and the O–H···F angle is 164.9±0.7°. The amplitudes of thermal displacement of the atoms along various directions are given. The nuclear scattering length of fluorine is revised to 0.529±13 (10^—12 cm).