The Crystal Structure of Mercury(I) Bromate.

Structural studies of mercury(I) compounds. I. Structure of mercury(I) nitrite, Hg2(NO2)2

“…The non-bonded Hg-O distances, Hg...O(2) (x-l, y, z)=2.93 (2) and ng...O(1) (x, --½-y, --½+z)= 2.84 (2) A, suggest some interaction, since the van der Waals radius of oxygen is 1.4 A and the closest Hg-Hg distance in solid mercury is estimated to be ~ 3.0 A (Evans, 1978). Similar weak interactions have been noted in HgE(BrO3) 2 (Dorm, 1967) and in HgESO 4 and HgESeO 4 (Dorm, 1969). The bonded -O-Hg-Hg-O system is approximately linear and the molecular unit is planar (deviations from the best plane are all <0.01 A) and centrosymmetric.…”

The crystal structures of two Mercury Perrhenates

“…The deviation of the 0-Hg-Hg angle from the ideal value of 180" is probably due to the packing of the molectiles in the monoclinic cell, while thc angle Re-0-Hg is nonlinear for similar reasons as are put forward to rationalize the angled H,O molecule. Molecular structures were also found for the mcrcury(1) compounds with the dimeric formulas Hg,(N02)2 [23] and Hg,(BrOJ, [24], which also deviate more or less from a linear arrangement. Table 4 Interatomic distances (pm) and selected angles ("1 in Hg,ReO,.…”

The use of neutron resonance scattering in the structure determination of Sm(BrO3)3.9H2O

“…It was mounted with the c axis along the axis of the goniometer head. Initial values of the setting angles were calculated assuming the same cell constants as for Nd(BrO3)3.9HzO (Helmholz, 1939). The correct cell constants were later refined by the method of least-squares from observed 20 angles: a= 11.86 + 0.03 and c = 6.76 + p.02 A.…”

“…(For Sin, resonance occurs at 0.92 A; for Cd it occurs at 0.67 A and on the lower wavelength side of the Cd resonance the neutron flux is extremely low.) At the start of this study, it was thought that this crystal would be isomorphous with Nd(BrO3)3.9H20, whose X-ray structure is non-centrosymmetric (Helmholz, 1939). Later, as no Bijvoet differences could be observed from Sm(BrO3)3.9H20, it was realized that the crystal structure was centrosymmetric and belonged to a different space group, P63/mmc, in the hexagonal system.…”