From Mono- to Poly-Substituted Frameworks: A Way of Tuning the Acidic Character of C-c-H in o-Carborane Derivatives
[EN] The incorporation of iodine atoms onto the boron vertices of the o-carborane framework causes, according to spectroscopic data, a uniform increase in the acidic character of the C-c-H (C-c= cluster carbon) vertices, whereas the incorporation of methyl groups onto the boron vertices of the o-carborane framework reduces their acidity. Methyl groups when attached to boron are electron-withdrawing in boron clusters, whereas iodine atoms bonded to boron act as electron donors. This has been proven on B-methyl and B-iodinated o-carboranes with NMR spectroscopy measurements and DFT calculations of natural bond orbital (NBO) charges. which show a Cumulative buildup of positive cluster only tot…
Iodinatedortho-Carboranes as Versatile Building Blocks to Design Intermolecular Interactions in Crystal Lattices
[EN] The crystal structures of numerous iodinated ortho-carboranes have been studied, which has revealed the diversity of intermolecular interactions that these substances can adopt in the solid state. The nature-mostly as it relates to hydrogen and/or halogen bonds-and relative strength of such interactions can be adjusted by selectively introducing substituents onto the cluster, thus enabling the rational design of crystal lattices. In this work we present the newly determined crystal structures of the following iodinated ortho-carboranes: 9-I-1,2-closo-C2B10H11, 4,5,7,8,9,10,11,12-I-8-1,2-closo-C2B10H4, 3,4,5,6,7,8,9,10,11,12-I-10,-1,2-closo-C2B10H2, 1-Me-8,9,10,12-I-4-1,2-closo-C2B10H7,…
Synthesis of quadruped-shaped polyfunctionalized o-carborane synthons
[EN] o-Carborane derivatives with precisely defined patterns of substitution have been prepared from 8,9,10,12-I-4-1,2-closo-C2B10H8 by replacing the iodine atoms, bonded to four adjacent boron vertices in the cluster, with allyl, and subsequently 3-hydroxypropyl groups. The resulting structures, comprising four pendant arms and two reactive vertices located on opposite sides of a central o-carborane core, can be envisaged as versatile precursors for dendritic growth