Carbaboranes as Pharmacophores: Properties, Synthesis, and Application Strategies

C-arylation and C-heteroarylation of icosahedral carboranes via their copper(I) derivatives

Carborane radical anions: spectroscopic and electronic properties of a carborane radical anion with a 2n + 3 skeletal electron count

Intramolecular electronic interactions were investigated in five series of 12-, 10-, and 6-vertex closo -boranes and hydrocarbons (benzene, acetylene, bicyclo[2.2.2]octane, and cubane) substituted with triple-bonded groups Y≡Z (C≡CR, C≡N, C≡O, and N≡N). Structural data (single crystal X-ray crystallography), spectroscopic properties (UV, IR, and NMR), chemical behavior (dediazoniation reactions), and electronic structure calculations (hybridization and π bond order) are all in agreement that the degree of electronic conjugation between the cluster and the Y≡Z substituent is lowest for the 12-vertex closo -borane and highest for the 6-vertex analog.

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Investigations of electronic interactions between closo-boranes and triple-bonded substituents

Energetic polymers containing nitro, nitrato, and azido groups release high energy during combustion and thereby increase the performance of the systems. A number of energetic polymers have been found suitable for use as binders in high-performance propellant and explosive formulations. This review describes the synthetic and application aspects of various modern energetic polymers for explosive formulations and propellants.

New directions in the area of modern energetic polymers: An overview

Isomerization of neobarenes into barenes via dianions of neodicarbadodecaboranes(14)

1.

Neobarenes are isomerized to barenes via the dianions of the dicarbadodecaboranes (14), in which connection the isomerization must be regarded as being a three-step process: a) reduction, b) isomerization of the dianion, and c) oxidation.




2.

The dianions of the dicarbadodecaboranes (14) form barenes when treated with oxidizing agents.




3.

The rapid addition of two equivalents of the metal occurs when the neobarenes are treated with alkali metals in liquid ammonia, with the formation of the adduct (m-B10H10C2RR′)2M, which is easily isomerized to the adduct (o-B10H10C2RR′)2M.




4.

The transfer of two electrons to the barene or neobarene nucleus occurs when the barenes or neobarenes are treated with aromatic anion-radicals of the type of naphthalenesodium in tetrahydrofuran solution, with the formation of the dianions.

Isomerization of neobarenes to barenes

1.

In a study of the comparative reactivity, it was shown that the acidity of the C-H bonds, the electron-acceptor effects of the ring, the ease of electrophilic, radical, and exchange halogenation, the stability of the carboranyl anion, the rate of nucleophilic substitution, the electron affinity of the carborane system, and the rate of cleavage of the C-C bonds in carbonyl derivatives under the action of nucleophilic reagents decrease in the series of o-, m-, and p-carboranes, and the stability to the action of strong bases and oxidizing agents increases.




2.

1-p-Carboranecarboxylic and 1,12-p-carboranedicarboxylic acids were produced by carbonization of mono- and dilithium derivatives of p-carboranes.




3.

In the electrophilic halogenation of p-carborane, 2-bromo-p-carborane, and 2-chloro-p-carborane were produced.




4.

In the photochlorination of p-carborane, decachloro-p-carborane, p-B10C10C2H2, was produced.




5.

The value of the dissociation constant (pK a =3.64) in 50% alcohol was determined for 1-p-carboranecarboxylic acid.




6.

The value of the equilibrium acidity (pK a =29.8–29.9 in the McEwen scale) was determined for p-carborane.




7.

α-Ketones of the p-carborane series undergo cleavage of the C-C bond under the action of bases.




8.

The thermal isomerization of m-carborane to p-carborane is an equilibrium reaction.

The comparative reactivity of ortho-, meta-, and para-carboranes

Preparation of B-hydroxybarenes by the action of nitric acid on barenes

1.

Unsymmetrical mercury derivatives of the barenes and neobarenes form stable complexes with o-phenanthroline, o-RCB10H10CHgCl·C12H8N2 and m-RCB10H10CHgX·C12H8N2.




2.

Bis(barenylmethyl)mercury and chloromercurimethylbarene give stable complexes with o-phenanthroline o-HCB10H10CCH2)2Hg·C12H8N2 and o-HCB10H10CCH2HgCl·C12H8N2.

L. S. Podvisotskaya

Papers

Isomerization of neobarenes into barenes via dianions of neodicarbadodecaboranes(14)

Isomerization of neobarenes to barenes

The comparative reactivity of ortho-, meta-, and para-carboranes

Preparation of B-hydroxybarenes by the action of nitric acid on barenes

Complexes of mercury derivatives of barenes and neobarenes with o-phenanthroline