MAIN GROUP METAL HALIDE-COMPLEXES WITH STERICALLY HINDERED THIOUREAS .12. CRYSTALLOGRAPHIC STUDIES OF LEAD(II) AND CADMIUM(II) THIOCYANATE COMPLEXES WITH 1,3-DIMETHYL-2(3H)-IMIDAZOLETHIONE

The complex, Pb(NCS)2(dmit)2, has been previously reported (dmit = 1,3-dimethyl-2(3H)-imidazolethione). A new complex, Cd(NCS)2(dmit)2, has also been synthesized and characterized. Single crystal X-ray structural studies were completed for both complexes. Cell parameters for [Pb(NCS)2(dmit)2]: space group C2/c, a = 11.118(2), b=14.121(4), c = 12.970(3) angstrom, beta = 108.29(2)-degrees, Z = 4, V = 1933.4 angstrom3, D(c) = 1.895 g/cm3 , D0 = 1.93 g/cm3 (lambda = 0.71073 angstrom), R = 0.030; [Cd(NCS)2(dmit)2]: space group C2/c, a = 10.911(2), b = 14.172(2), c = 12.471(2) angstrom, beta = 107.54(1)-degrees, Z = 4, V = 1838.7 angstrom3, D(c) = 1.752 g/cm3 , D0 = 1.75 g/cm3 (lambda = 0.71073 angstrom), R = 0.031. Both complexes are isostructural polymers comprised of zigzag chains Of MS4N2 distorted octahedra sharing common edges through almost perfectly linear bridging SCN groups displaced cis to each other relative to the central metal atom. Thiourea ligands are displaced trans to each other. Comparative bond distances show the formulation of these complexes to be more accurately stated as M(NCS)2(dmit)2. There is no clear evidence for the lone pair of electrons through systematic distortions in the lead structure although there are greater observed deviations from 90-degrees in the local site symmetry about Pb than about Cd.