Cadmium coordination chemistry related to chelate therapy

Abstract

Various aspects of the coordination chemistry of cadmium in its dithiocarbamate complexes, which are known to affect the in vivo distribution of this toxic metal ion have been examined. Under appropriate conditions, solid complexes of the composition Cd(DTC) 2 have been obtained as reaction products with seven dithiocarbamates. The general properties, octanol/water partition coefficients, mass spectra, 1H, 13C and 113Cd NMR spectra and infrared spectra have been obtained. The molecular structure of the Cd{S 2CN(n-C 4H 9) 2} 2 complex has been determined. This compound forms monoclinic crystals C2/ c a= 23.577(7), b=16.877(8), c=16.209(9) Å, β= 126.93(3) o, V=5156(8) Å 3, Z=8, density=1.343 g cm− 3. For the structure determination: λ(Mo Kα)= 0.71073 Å, μ=1.076 mm −1, F(000)=2160, T= 296 K and R=0.064 for 1330 observed reflections. The Cd ion is coordinated to four S atoms at distances ranging from 2.513(5) to 2.601(7) Å and to a fifth one at the much longer distance of 2.888(5) Å. Two of the short metal-sulphur distances are realized by the S atoms of one of the chelate moieties whilst the S atoms of the other moiety realize one short and the longest [2.888(5) Å] metal sulphur distance. The other short bond is subtended to a sulphur atom of an asymmetry-related ligand. The coordination polyhedron can be described as either a very distorted tetragonal pyramid or a very distorted trigonal bi-pyramid. The shortest CdCd distance is 3.772(6) Å.