CRYSTAL AND MOLECULAR-STRUCTURE OF TETRAKIS(CYANOMERCURI)METHANE HYDRATE

The crystal structure of tetrakis(cyanomercuri)methane hydrate, C(HgCN)4 · H2O, has been determined from diffractometer X-ray intensity data by means of Patterson and Fourier methods and refined by the least-squares technique based on 911 independent reflections to the index R of 0.058 and Rω of 0.065. Crystals are monoclinic holohedral, space group P21/n with Z 4 formula units in the unit cell of dimensions a 8.520(5), b 13.622(8), c 10.783(6) Å, β 92.48(5)°, Dobs 4.99 g cm-3, Dcalc 4.97 g cm-3. The structure consists of discrete molecules of tetrakis(cyanomercuri)methane and molecules of water of crystallization. The bond angles at the methane carbon atom range from 105(2) to 114(3)° and the mean HgC(methane) bond length is 2.05(3) Å, while the distance of all the four mercury atoms from the geometrical centre of the tetrahedron is 2.053(3) Å. The CHgC bond angles range from 175(3) to 178(2)°. The mean value of the HgC(cyanide) bond length is 2.03 Å. The one OH⋯N hydrogen bond per water molecule is 2.77 Å long. © 1975.