An unusual direct conversion of metallaboranes to metallacarbaboranes and the isolation of a novel isoarachno twelve-vertex cluster compound

Abstract

Reaction of [6-(η⁵-C₅Me₅)-nido-6-RhB₉H₁₃] with RNC (R = Et, Me) in toluene at room temperature quickly gave a high yield of the bis(ligand) adducts [6,9-(RNC)₂-6-(η⁵-C₅Me₅)-arachno-6-RhB₉H₁₁] which, on being heated in boiling toluene, undergo carbon incorporation to yield one- and two-carbon, eleven-vertex closo-type metallacarbaborane species rather than a reduction of RNC, whereas reaction of the isoelectronic cluster compound [6-(η⁶-C₆Me₆)-8-(OMe)-nido-6-RuB₉H₁₂] with MeNC traps an unprecedented intermediate twelve-vertex isoarachno-{RuCNB₉} cluster type that has four-, five-, and six-membered open faces.