Abstract:
Hg(18-Crown-6)C12 and Cd(18-Crown-6)C12 are isostructura1, space group
Cl~ Z = 2. For the mercury compound, a = 10.444(2) A° , b = 11. 468(1) A° ,
c = 7.754(1) A° , a = 90.06(1)°, B = 82.20(1)°, Y = 90.07(1)°, Dobs = 1.87,
Dca1c = 1.93, V = 920.05 13, R = 4.66%. For the cadmium compound,
000
a = 10.374(1) A, b = 11.419(2) A, c = 7.729(1) A, a = 89.95(1)°,
B = 81.86(2)°, Y = 89.99(1)°, Dobs = 1.61, Dcalc = 1.64, V = 906.4613,
R = 3.95%. The mercury and cadmium ions exhibit hexagonal bipyramidal
coordination, with the metal ion located on a centre of symmetry in the
plane of the oxygen atoms. The main differences between the two structures
are an increase in the metal-oxygen distance and a reduction in the metalchloride
distance when the central ion changes from Cd2+ to Hg2+. These
differences may be explained in terms of the differences in hardness or
softness of the metal ions and the donor atoms.
