On the crystal chemistry of salt hydrates. V. The determination of the crystal structure of CuSO4.3H2O (bonattite)

Abstract

CuSO4.3HzO crystallizes in space group Cc with a= 5.592, b= 13.029, c=7.341 A, B= 97°3 ', Z=4. The structure has been determined from Patterson and Fourier syntheses using three-dimensional data collected on a precession camera with Mo Ke radiation. The structure was refined by the method of least squares. The final R value for 936 observed structure factors is 0.069. The coordination polyhedra around the Cu2+ ions do not share any edges or corners with each other; they are connected by hydrogen bonds and via linking sulfate groups. The square planar coordination around the copper ion consists of three water oxygen atoms and one sulfate oxygen atom at an average distance of 1.96/~. Two more sulfate oxygen atoms at 2.40 and 2.45 A, complete the distorted octahedral coordination. The average S-O bond length in the sulfate tetrahedron is 1.472 A. The positions of the hydrogen atoms were not determined experimentally; they were calculated theoretically assuming that the hydrogen atoms are in positions of least electrostatic energy. Only four of the six crystallographically nonequivalent hydrogen atoms are involved in normal hydrogen bonds.

On the crystal chemistry of salt hydrates. VI. The crystal structures of disodium hydrogen orthoarsenate heptahydrate and of disodium hydrogen orthophosphate heptahydrate

“…This shows that the common assumption (Cruickshank, 1961) that the average P-O distance in tetrahedral groups is constant, is not strictly true. This is in contrast to the case of the sulfate group for which the average value of the S-O bond length of 1.473 A (Baur, 1964) has since been confirmed by numerous new determinations (one example is CuSO4.3 H20 with S-O = 1.472 A, Zahrobsky & Baur, 1968). Similarly there are unexplained, but significant, differences in individual P-O distances.…”

“…This is part six of a series of papers on the crystal chemistry of salt hydrates. The previous paper in the series is by Zahrobsky & Baur (1968).…”

Crystallographic studies of metal–nucleotide base complexes. IV. Tetraaquo-(9-methyladenine)copper(II) sulphate monohydrate

“…The preference for water molecules rather than the sulphate ion in equatorial positions has also been found in the tri-and pentahydrate of CuSO4 (Zahrobsky & Baur, 1968;Bacon & Curry, 1962 …”

The relationship between the structures of Cu(II) complexes and their chemical transformations

“…In the dehydration of CuSO~ 9 5 HzO under the experimental conditions applied here, the first definite intermediate formed was CuSO4 " 3 H20. In the coordination polyhedron of Cu(II) in CuSO4 " 3 H20, the distance the copper from the oxygen of two coordinated water molecules is longer than that from the oxygen of the third coordinated water molecule, this one forming two hydrogen-bonds to oxygen atoms from the sulphate groups [13]. It has been suggested that in the thermal decomposition process this compound is formed first in the amorphous form, and then undergoes recrystallization [10].…”