Synthesis of 13-vertex dimetallacarboranes by electrophilic insertion into 12-vertex ruthenacarboranes

Abstract

The electrophilic insertion of organometallic species into metallacarboranes was studied in detail for the model compound - the 12-vertex closo-ruthenacarborane anion [Cp*Ru(CBH)] (1). Reactions of the anion 1 with the 12-electron cationic species [M(ring)] (M(ring) = RuCp, RuCp* and Co(CMe)) gave the 13-vertex closo-dimetallacarboranes Cp*Ru(CBH)M(ring). Similar reactions of the neutral ruthenacarborane Cp*Ru(MeS-CBH) produce the cationic dimetallacarboranes [Cp*Ru(MeS-CBH)M(ring)]. The symmetrical 13-vertex diruthenacarboranes (CR)Ru(RCBH)Ru(CR) can be prepared by the direct reactions of Tl[7,8-R-7,8-CBH] (R = H and Me) with two equivalents of [CpRu(MeCN)] or [Cp*RuCl]. The insertions of the 14-electron cationic species [M(ring)] (M(ring) = NiCp, NiCp* and Co(CMe)) into 1 gave the 13-vertex dimetallacarboranes Cp*Ru(CBH)M(ring), which have a distorted framework with one open face. The structures of Cp*Ru(CBH)Co(CMe) and Cp*Ru(CBH)NiCp were established by X-ray diffraction. Some of the 13-vertex dimetallacarboranes have two electrons less than required by Wade's rules. This violation is explained by the absence of the appropriate pathway for the distortion of the framework.