Supramolecular Isomerism in a Cadmium Bis(N-Hydroxyethyl, N-isopropyldithiocarbamate) Compound: Physiochemical Characterization of Ball (n = 2) and Chain (n = ∞) Forms of {Cd[S₂CN(iPr)CH₂CH₂OH] ₂•solvent}n

Abstract

Needles of [{Cd[S₂CN(iPr)CH₂CH₂OH] ₂}₃•MeCN]∞ (2) were harvested from a dry acetonitrile solution of Cd[S₂CN(iPr)CH₂CH₂OH] ₂ after one or two days and proved to be a coordination polymer in which all dithiocarbamate ligands are μ₂,κ²-tridentate, bridging two cadmium atoms and simultaneously chelating one of these. If the same solution was allowed to stand for at least several days, 2 is replaced by blocks comprising a supramolecular isomer of 2, dimeric 1, with formula {Cd[S₂CN(iPr)CH₂CH₂OH] ₂}₂•2H₂O•2MeCN, and two ligands coordinating μ₂,κ² as in 2 and the other two purely κ2-chelating. The time dependency correlates with the pivotal role of water in driving the conversion of “chain” 2 to “ball” 1; crystals of 2 could not be isolated from “wet” acetonitrile. When each of 1 and 2 are dissolved in solution, they exhibit comparable spectroscopic attributes (¹H, ¹³C, and ¹¹³Cd NMR and UV/vis), indicating the solution structures are the same. Both 1 and 2 are luminescent in the solid state with 1 being significantly brighter than 2. Greenockite CdS nanoparticles are generated by the thermal decomposition of both 1 and 2.