Are Halocarboranes Suitable for Substitution Reactions? The Case for 3-I-1,2-closo-C2B10H11: Molecular Orbital Calculations, Aryldehalogenation Reactions, 11B NMR Interpretation of closo-Carboranes, and Molecular Structures of 1-Ph-3-Br-1,2-closo-C2B10H10 and 3-Ph-1,2-closo-C2B10H11
摘要:
In this paper, the chemistry of 3-X-1,2-closo-C2B10H11 (X = halogen) derivatives is extended. Molecular orbital and B-11 and C-13 NMR calculations on these species are presented. A qualitative interpretation of the B-11 NMR spectra of closo o-carborane derivatives is also provided. The synthesis of 3-X-1-R-o-carborane (X = I, Br and R = Me, Ph) derivatives is reported, and aryldehalogenation at the B3 position is reported for the first time. The molecular and crystal structures of 1-phenyl-3-bromo-1,2-dicarba-closo-dodecaborane and 3-phenyl-1,2-dicarba-closo-dodecaborane are described.
Retention of the B(3)X (X=Br, I) bond in closo-o-carborane derivatives after nucleophilic attack. The first synthesis of [3-X-7-R-7,8-nido-C2B9H10]− (X=Br, I). Crystal structure of [HNMe3][3-I-7,8-nido-C2B9H11]
The synthesis of new 3-halogeno nido derivatives of o-carborane, [3-X-7-R-7,8-nido-C2B9H10](-) (X=Br, I; R=H, CH3, C6H5) is described, through deboronation of the compounds 3-X-1-R-1,2-closo-C2B10H10, previously synthesised in our laboratory. These nido products have been fully characterised using H-1-, B-11- and C-13-NMR spectroscopies, MALDI-TOF and, for [3-1-7,8-nido-C2B9H11](-) by an X-ray crystallographic study. The influences of the halogen moiety on both the B(3) resonance and that of the bridge proton are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.