Isomery of [Re6S6Br8] and [Re6S5Br9] Units in a Rhenium Cluster Thiobromide: Experimental and Theoretical Approaches

Abstract

The rhenium cluster thiobromide Cs1.95(1)Re6S5.82(3)Br8.19(3), belonging to the solid solution Cs2Re6S6Br8–CsRe6S5Br9, crystallizes in the trigonal system (P31c, a = 10.001(5) A and c = 14.676(5) A). It is built up from [Re6L8i]Br6a cluster units in which sulphur and bromine are randomly distributed on inner position (Li). From the structural refinement performed using single-crystal X-ray diffraction data, the isomers of the [Re6Si6Br2i] and [Re6S5iBr3i] cluster cores present in the structure have been unambiguously determined, due to the non-centro symmetry of the structure. Density functional theory calculations have been performed for all possible di- and tri-substituted isomers in order to confirm experimental analyses. Slight differences between the stability of di-substituted and tri-substituted cluster unit isomers built from Mo6 cluster and Re6 clusters are evidenced.