Solid-state cadmium-113 NMR of three structural isomers of hexadecakis(benzenethiolato)tetrasulfidodecacadmate(4-)

Abstract

Solid-state [sup 113]Cd NMR chemical shift ([delta][sup iso]) and chemical shift anisotropy ([delta][sub ii]) data are reported for crystalline samples of three different compounds containing the [S[sub 4]Cd[sup 10](SPh)[sub 16]][sup 4[minus]] cluster. This cluster is a supertetrahedral fragment of the cubic (sphalerite) CdS lattice and contains two types of CdS[sub 4] coordination, Cd[sup i][l brace]([mu][sub 3]-S)[sub 2]([mu]-SPh)[sub 2][r brace] and Cd[sup o][l brace]([mu]-SPh)[sub 3](SPh)[r brace]. Although the Cd sites in these compounds are all pseudotetrahedral, there are in these three different samples small distortions and variations in the coordination geometry at the Cd atoms, arising from configurational isomerism at ([mu]-SPh) and crystal packing variations at the periphery of the clusters. The chemical shift data reflect these geometrical variations. Chemical shift anisotropies ([delta][sub 33]-[delta][sub 11]) range from 207 to 480 ppm for the pseudotetrahedral CdS[sub 4] coordination. Variations in the chemical shift data correlate principally with S-Cd-S angle variation. Isotropic chemical shifts for Cd[sup o] vary by only 20 ppm, but individual [delta][sub ii] and chemical shift anisotropies ([delta][sub 33]-[delta][sub 11]) are changed by up to 70 ppm for 5[degrees] variations in angles at Cd[sup o]. At Cd[sup i], angle differences of similar magnitude cause [delta][sub iso] values to vary bymore » 46 ppm, [delta][sub ii] values by 80 ppm, and ([delta][sub 33]-[delta][sub 11]) values by 100 ppm. The data and correlations reported will be valuable in the interpretation of [sup 113]Cd NMR chemical shift data for biological and electronic materials based on cadmium sulfide and thiolate clusters. Crystal structure data for (Et[sub 3]NH)[sub 4][S[sub 4]Cd[sub 10](SPh)[sub 16]] are reported. 34 refs., 7 figs., 5 tabs.« less