Relevance of the Electronegativity of Boron in η5‐Coordinating Ligands: Regioselective Monoalkylation and Monoarylation in Cobaltabisdicarbollide [3,3′‐Co(1,2‐C2B9H11)2]− Clusters
- 22 September 2003
- journal article
- Published by Wiley in Chemistry – A European Journal
- Vol. 9 (18), 4311-4323
- https://doi.org/10.1002/chem.200304970
Abstract
Regioselective monoalkylation and monoarylation in cobaltabisdicarbollide clusters has been achieved starting from Cs[8‐I‐3,3′‐Co(1,2‐C2B9H10)(1′,2′‐C2B9H11)] by cross‐coupling reactions between a BI fragment and an appropriate Grignard reagent in the presence of a Pd catalyst and CuI. A considerable number of monoalkylated and monoarylated derivatives have been synthesized, which allowed study of the influence of boron in metallocene‐type ligands and the effect of alkyl and aryl substituents on boron in boron anionic clusters. Experimental data from UV/Vis spectroscopy, E1/2 measurements, and X‐ray diffraction analysis, and supported by EHMO and ab initio analyses, indicate that the participation of metal d orbitals in the HOMO is less than that in typical metallocene complexes. This can be explained in terms of the lower electronegativity of boron compared to carbon. Related to this is the −I character of alkyl groups when bonded to boron in boron anionic clusters, contrary to the common belief that alkyl groups are generally electron‐releasing moieties.This publication has 67 references indexed in Scilit:
- Sequential Nucleophilic−Electrophilic Reactions Selectively Produce Isomerically Pure Nona‐B‐Substituted o‐Carborane DerivativesEuropean Journal of Inorganic Chemistry, 2003
- A Camouflagednido-Carborane Anion: Facile Synthesis of Octa-B-methyl-1,2-dicarba-closo-dodecaborane(12) and Its Deboration ReactionChemistry – A European Journal, 1999
- Cobaltabis(dicarbollide) derivatives as extractants for europium from nuclear wastesChemical Communications, 1998
- Synthesis of Cobaltabis(dicarbollyl) Complexes Incorporating Exocluster SR Substituents and the Improved Synthesis of [3,3‘-Co(1-R-2-R‘-1,2-C2B9H9)2]-DerivativesInorganic Chemistry, 1997
- Dodecamethylcarba-closo-dodecaborate(−) Anion, CB11Me12-Journal of the American Chemical Society, 1996
- New synthetic routes to B-halogenated derivatives of cobalt dicarbollideInorganic Chemistry, 1995
- Iodination Reactions of Icosahedral para-Carborane and the Synthesis of Carborane Derivatives with Boron-Carbon BondsInorganic Chemistry, 1995
- 2,2′,5,5′‐Tetra‐tert‐butyl‐1,1′‐diazaplumbocene— a Stable Azacyclopentadienyl Compound of LeadAngewandte Chemie, 1992
- Two-dimensional boron-11-boron-11 nuclear magnetic resonance spectroscopy as a probe of polyhedral structure: application to boron hydrides, carboranes, metallaboranes, and metallacarboranesJournal of the American Chemical Society, 1984
- Background of the nuclear magnetic resonance antipodal shift induced by substituents; an analogy of the mesomeric effect with borane skeletonsJournal of the Chemical Society, Chemical Communications, 1977