Refinement of the crystal and molecular structure of potassium tetranitritomercurate(II) nitrate by neutron diffraction

Abstract

A neutron diffraction study of the title compound has been carried out. Crystals are orthorhombic, space group Pnma, Z= 4, a= 12.290(6), b= 10.644(1), c= 9.377(1)Å. Full matrix least-square refinements have produced R 0.034. The neutron-diffraction results agree well with results from an earlier X-ray diffraction study. The structure consists of K⁺, [Hg(NO₂)₄]^2–, and (NO₃)^– as discrete ions, with the four nitrite groups co-ordinated to the mercury through both oxygens as bidentate chelates. The arrangement of the eight oxygens about the mercury can be described in terms of a highly distorted square antiprism or alternatively as a highly distorted undecahedron.