C−C Plasticity in Boron Chemistry: Modulation of the Cc···CcDistance in Mixed Pyrrolyl/Dicarbollide Complexes

Abstract

The single, double, and triple bond distances are well defined in conventional organic compounds. Cluster boron chemistry, in particular the o-carboranes, provides the possibility to modulate the C−C distance in an almost continuous way within the same family of compounds. As an example, mixed pyrrolyl/dicarbollide sandwich cobalt complexes derived from closo-[3-Co(η5-NC4H4)-1,2-C2B9H11] (1) display a continuous range of Cc···Cc distances between 1.640(7) for the parent compound and 1.919(6) for closo-[3-Co(η5-NC4H4)-1,2-(SCH3)2-1,2-C2B9H9] (5). Here, Cc represents the cluster carbon atom. The Cc···Cc modulation was achieved merely by modifying the substituents on the carbon of the cluster compound. The complexes studied were synthesized by reaction of the appropriate closo cluster, e.g., 1,2-(SCH3)2-1,2-C2B10H10 with a suspension of K[NC4H4] and anhydrous CoCl2. The new compounds are closo-[3-Co(η5-NC4H4)-1,2-(SCH3)2-1,2-C2B9H9] (5), closo-[3-Co(η5-NC4H4)-1,2-(SC6H5)2-1,2-C2B9H9] (6), and closo-[3-Co(η5-...