Polyhedral Boranes and Carboranes

New Azido Coumarins as Potential Agents for Fluorescent Labeling and Their “Click” Chemistry Reactions for the Conjugation with closo-Dodecaborate Anion

“…The neutron capture reaction produces high linear energy transfer particles, 4 He (α-particle) and 7 Li, which cause lethal damage to tumour cells through ionization process [ 59 , 60 , 61 , 62 ]. This causes increased interest in the synthesis of conjugates of the closo -dodecaborate anion with various biologically active molecules [ 57 , 58 , 63 , 64 , 65 , 66 ].…”

“…An effective approach to the functionalization of the closo -dodecaborate anion is the opening of its cyclic oxonium derivatives by nucleophiles [ 76 ]. This approach is widely used for the synthesis of its various functional derivatives and attachment to biomolecules [ 64 , 77 , 78 ], and has also been used to modify other polyhedral boron hydrides such as the closo -decaborate anion [ 64 ], nido -carborane [ 79 ], and cobalt and iron bis(dicarbollides) [ 80 ]. In particular, the synthesis of the earlier described coumarin derivatives of the closo -dodecaborate anion is based on the opening of oxonium rings with hydroxy groups at various positions of the coumarin heterocycle [ 72 , 73 , 74 ].…”

Formation and reactivity of a unique M⋯C–H interaction stabilized by carborane cages

“…2–7 The carborane substituents have been widely used to tune ligand properties. Because of the unique electronic effects of carboranes, 8–12 they are often recognized as three-dimensional inorganic benzene analogs. 13,14 Based on this property, many studies have explored compounds such as carborynes (1,2-dehydro- ortho -carboranes), 15 transition metal–carboryne complexes, 16 and o -carborane-fused borirans.…”

The Hammett substituent constant of the dodecaborate dianion inaugurates a non-coordinating, non-basic, and strongly inductively electron-donating group for organic chemistry

“…Obviously, the introduction of protecting groups such as acyl for an amino group, is counterproductive, as it reduces the electron-donor strength, and protonation or peralkylation of an amino group converts it even to an electron-withdrawing substituent (see NMe 3+ in Table 1). We now introduce the dodecaborate group (B 12 H 11 2-, DDB) 16,17 to ll this gap. As can be seen from Table 1, DDB is as strongly electron-donating as oxide and amino, yet without a single of the described drawbacks.…”