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

Systematic Metallaborane Chemistry

“…Given the fact that monocyclopentadienyl metal halides of nearly all the transition metals are known, and boranes coordinated to bases other than H - were commercially available, e.g., BH 3 THF, Kathryn Deck and I decided that the investigation of [Cp*CoCl] 2 (to access the compounds of Grimes 8 ) and [Cp*CrCl] 2 (to look at possible borane analogues of Theopold's organometallic compounds) would make a good thesis project. It did! − She and her contemporary, Yasushi Nishihara, laid a foundation for the development of this theme by the enthusiastic group of talented co-workers who followed.…”

Substitution at boron in molybdaborane frameworks: Synthesis and characterization of isomeric (η5-C5Me5Mo)2B5HnXm (when X=Cl: n=5, 7, 8; m=4, 2, 1 and X=Me: n=6, 7; m=3, 2)

“…Although few reports available on the chlorination of boron on metallaboranes [42][43][44][45], it is not yet clear what factors actually dominates the substitution chemistry. Therefore, it is desirable to have systematic and efficient methods for achieving B-peralkylation or B-perhalogenation of metallaborane compounds.…”

Reactions of the Cobaltaborane 2,4-{(η5-C5Me5)Co}2B3H7with Metal Fragments. Synthesis and Characterization ofnido-1-{(η5-C5Me5)Co}-2-{(CO)3Fe}B3H7andarachno-(η5-C5Me5)(CO)CoB3H7

“…Good yields of single products from simple reactions permit the reaction chemistry to be investigated. We have previously reported some of this chemistry for Co, Cr, and Mo and in the following describe the reactivity of a nido -dicobaltapentaborane with typical metal fragments. Two new metallaboranes are produced in modest to good yield by metal fragment substitution in one case and metal fragment loss in the other.…”