Cooperative Effect of Carborane and Pyridine in the Reaction of Carboranyl Alcohols with Thionyl Chloride: Halogenation versus Oxidation

Thionyl chloride (SOCl₂) acts as halogenation reagent in its reaction with 1-[phenyl(hydroxy)methyl]-2-R-1,2-dicarba-closo-dodecaborane 1a,b but unexpectedly behaves as an oxidant for 1-[2′-pyridyl(hydroxy)methyl]-2-R-1,2-dicarba-closo-dodecaboranes 2a,b. The synthesis and characterization of all new compounds, including structure determinations of 1a, 2a, 1-[phenyl(chloro)methyl]-2-methyl-1,2-dicarba-closo-dodecaborane 3a, and 1-[2′-pyridyl(oxo)methyl]-2-methyl-1,2-dicarba-closo-dodecaboranes 4a are reported and the possible pathways are discussed.