Neutron diffraction study of sodium thiosulphate pentahydrate, Na2S2O3.5H2O

Abstract

A single-crystal neutron-diffraction investigation of sodium thiosulphate pentahydrate, Na2S203.5H20, has been made with three sets of zonal data. The structure was refined by least-squares techniques, with individual temperature factors, to an R value of 8.2%. The geometry of the $203 group and sodium-oxygen framework agree with those of X-ray studies. The positional parameters of some of the atoms differ from those p3stulated from the X-ray and nuclear magnetic resonance studies. The O-H and H-H bond distances and the H-O-H valence angle of all the five water molecules were found to be normal. The hydrogen-bond scheme falls into four classes: two strong water-thiosulphate oxygen, two weak water-thiosulphate oxygen, two water-water, and three water-sulphur hydrogen bonds. From the geometry of its surroundings one of the hydrogen atoms H(9) may be regarded as not participating in hydrogen bonding.

An X-ray diffraction study of sodium thiosulphate pentahydrate, Na2S2O3.5H2O

“…E1 Saffar (1968) has reported the positional parameters of H atoms deduced from his NMR studies. Padmanabhan et al (1971) refined the abovementioned crystal structure from two-dimensional neutron diffraction data and they basically confirmed the hydrogen-bonding scheme as proposed by Taylor &Beevers (1952) andEl Saffar (1968), with the exception of atom H(9). Baur (1972) suggests that this disagreement needs clarification.…”

“…to 0.13. At this stage, unlike Padmanabhan et al (1971), we found evidence of extinction and the 25 severely extinctionaffected reflexions were corrected for extinction effects (Aydin Uraz & Arma~an, 1975) as described by Zachariasen (1967) and Killean, Lawrence & Sharma (1972). With these extinction-corrected structure amplitudes in two cycles of isotropic refinement, R and R, reduced to 0.10 and 0.11 respectively.…”

“…Monoclinic, °space groupP2Jc, a = 5.941,b =21.570, c = 7.525 A,/~ = 103°55 ', Z = 4 (Taylor & Beevers, 1952;Padmanabhan et al, 1971). The linear absorption coefficient for Cu Ka radiation was found to be 59.7 cm -1.…”

A neutron diffraction study of barium thiosulphate monohydrate, BaS2O3.H2O

“…The geometry and bonding in the SzO]-ion (Table 6) are similar to those observed in two other ionic thiosulphates, MgSzO3.6H20 (Baggio, Amzel & Becka, 1969) and NazSzO3.5H20 (Padmanabhan et al, 1971). Thus the bond angles subtended at the central sulphur atom, which range from 108.1 (2) ° to 110.9 (2) °, reveal only slight distortions from ideal tetrahedral symmetry, and the bond lengths indicate considerable zc bonding character in both S-O and S-S bonds.…”

The crystal structure of Cs2S2O3·H2O

“…Typically, hydrogen bonding networks involving all water molecules in O-H···O and O-H···S bonds with S 2 O 3 2− anions are observed [7]. So far several crystal structures of alkali metal thiosulfate hydrates are well characterized and the hydrogen bonding systems therein have been discussed: K 2 [13][14][15][16]. A detailed classification of the hydrogen bonds is available for Na 2 S 2 O 3 ·5H 2 O.…”