Pyrrolidine dithio carbamate (pdtc) cobalt(III) chelate has been used as a coprecipitation matrix for obtaining preconcentration factors of 100 or more for analytical estimation of trace metals in natural waters. This chelate, suitable for bivalent and trivalent ions, crystallizes as dark green crystals in monoclinic space group C2/c with unit cell parametersa = 28.89 å,b = 14.39 å,c = 16.17 å andΒ = 104.2‡. X-ray crystallographic analysis of these crystals reveals that threepdtc are coordinated to a Co03 + atom through their sulphur atoms, the six sulphur atoms forming a distorted octahedra around the metal atom at an average distance of 2.26 å. The thiocarbamate part of the ligands is nearly planar but the pyrrolidine rings are puckered.
