Substituted arenethiolate complexes Cd(SC6H4X-4)2 (X = H (la), F (lb), CH3 (lc), Br (le), Cl (le)), which have been shown to be structurally nonmolecular in the solid state, require polar coordinating solvents such as DMF for dissolution. The 113Cd NMR spectrum of la at 224 Κ shows a major line at δcd 593.1 ppm, diagnostic of cadmium surrounded by four thiolate ligands, and a minor (5%) line at 130 ppm ascribed to cadmium with {Cd(SPh)(DMF)n}+ coordination. With increasing temperature, only the major line is observed, broadening and then narrowing to a line at 458 ppm, at 341 K. Compounds 1b-e give similar spectra. The temperature-dependent 13C NMR spectra reveal the presence of rapidly interchanging bridging and terminal SAr ligands. The 113Cd NMR spectral changes are interpreted in terms of the dynamics of interconversions between aggregated and deaggregated cadmium species. The preferred structural model for the aggregated species formed at low temperatures involves adamantanoid cages {octahedro-(µ-SAr)6-tetrahedro-Cd4} linked through vertices by bridging thiolates, in the same manner as occurs in the various crystal structures. Ligand disproportionation equilibria such as 18Cd(SAr)2(s) + DMF → [Cd16(SAr)34− (DMF)2]2− + [(DMF)mCd(µ-SAr)2Cd(DMF)m]2+ account for the coordinative dissolution, the low solution conductivity, and the high δCd and low δcd resonances. Various alternative vertex-linked polyadamantanoid aggregates of different sizes are postulated to exist in solution. To account for the changes in the 113Cd NMR spectra, it is proposed that with temperature increase, smaller vertex-linked species with different sizes and degrees of solvent coordination are formed, in a cascade of increasingly rapid deaggregation reactions. An alternative structural model for the low-temperature aggregates, involving fused adamantanoid cages, is judged to be less plausible. Addition of small amounts of halide (Cl−, Br−, I−) to solutions of Cd(SAr)2 in DMF causes changes to the 113Cd NMR spectra consistent with coordinated solvent being replaced by halide. © 1990, American Chemical Society. All rights reserved.
