Substitution on Metallaboranes at Boron. Syntheses of <i>closo</i>-1-X-[2,3,4-(η⁵-C₅Me₅)₃(μ-H)₂Co₃B₂H], X = Cl and OH, and <i>closo</i>-1,5-Cl₂-[2,3,4-(η⁵-C₅Me₅)₃(μ-H)₂Co₃B₂] from <i>closo</i>-[2,3,4-(η⁵-C₅Me₅)₃(μ-H)₂Co₃B₂H₂]

Abstract

The reaction of closo-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2H2], 1, with metal chlorides results in the formation of either closo-1-Cl-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2H], 2, or closo-1,5-Cl2-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2], 3, depending on chlorination reagent. Hydrolysis of 1, yields closo-1-OH-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2H], 4. Isolated yields of 2 and 4 are modest to good, and all compounds have been characterized spectroscopically as simple substitution derivatives of 1. The substituent effects have been probed by 11B NMR measurements and compared with those for other substituted borane and metallaborane clusters. The observation of an enhanced antipodal effect shows that 1 possesses a characteristic property of a five-atom closo cage suggesting delocalized cluster bonding that includes both the boron and metal centers.