m-Carborane as a Novel Core for Periphery-Decorated Macromolecules

Abstract

Closo m-C2B10H12 can perform as a novel core of globular periphery-decorated macromolecules. To do this, a new class of di and tetrabranched m-carborane derivatives has been synthesized by a judicious choice of the synthetic procedure, starting with 9,10-I2-1,7-closo-C2B10H10. The 2a-NPA (sum of the natural charges of the two bonded atoms) value for a bond, which is defined as the sum of the NPA charges of the two bonded atoms, matches the order of electrophilic reaction at the different cluster bonds of the icosahedral o-and m- carboranes that lead to the formation of B-I bonds. As for m-carborane, most of the 2a-NPA values of B-H vertexes are positive, and their functionalization is more challenging. The synthesis and full characterization of dibranched 9,10-R2-1,7-closo-carborane (R = CH2CHCH2, HO(CH2)3, Cl(CH2)3, TsO(CH2)3, C6H5COO(CH2)3, C6H5COO(CH2)3, N3(CH2)3, CH3CHCH, and C6H5C2N3(CH2)3) compounds as well as the tetrabranched 9,10-R2-1,7-R2-closo-C2B10H8 (R = CH2CHCH2, HO(CH2)3) are presented. The X-ray diffraction of 9,10-(HO(CH2)3)2-1,7-closo-C2B10H10 and 9,10-(CH3CHCH)2-1,7-closo-C2B10H10, as well as their Hirshfeld surface analysis and decomposed fingerprint plots, are described. These new reported tetrabranched m-carborane derivatives provide a sort of novel core for the synthesis of 3D radially grown periphery-decorated macromolecules that are different to the 2D radially grown core of the tetrabranched o-carborane framework.

Synthesis of mono- and polyfunctional organosilicon derivatives of polyhedral carboranes for the preparation of hybrid polymer materials

“…22 Due to their aromaticity, carboranes demonstrate remarkably high thermal and chemical stability and exceptional hydrophobic characteristics. Moreover, the synthetic availability of carborane derivatives greatly contributes to their use in various fields of applications, 23,24 especially in the creation of new materials with desired properties [25][26][27][28][29][30][31][32][33][34] such as boronated polysiloxanes. [35][36][37] The incorporation of icosahedral carborane polyhedra in siloxanes introduces unconventional properties in the resultant supramolecular structures.…”

Catalytic Cage BH Functionalization of Carboranes via “Cage Walking” Strategy

“…20 In m-carborane molecules, 10 B−H vertices can be divided into four groups and their electron densities follow the order B(9,10) > B(5,12) > B (4,6,8,11) > B(2,3) (Chart 1). 21,22 A cage-walking was observed when B(9)-Br-m-carborane was treated with a solution of [XPhosPd 0 ] at 80 °C, leading to the formation of cage B(2)-, B(4)-, B(5)-, and B(9)-Br-m-carboranes. 20 The [XPhosPd(m-carborane)] + intermediate B with a vacant coordination site was suspected to be responsible for the activation of an adjacent B−H bond and subsequent cagewalking (Scheme 4).…”

Noncatalytic Bromination of Icosahedral Dicarboranes: The Key Role of Anionic Bromine Clusters Facilitating Br Atom Insertion into the B–H σ-Bond

“…Practical interest in B-halogenated carboranes has remained limited because of the reduced reactivity of the halogen atom . Recently, however, techniques have been developed that allow the creation of B–N and B–C bonds by cross-coupling according to the reactions of Kumada, , Suzuki, − and Heck − (see also refs and ). This approach opens up opportunities for the synthesis of new compounds with useful properties, including biologically active compounds. ,, …”