This review systematizes data on the coordination ability of mono- and disubstituted derivatives of boron cluster anions and carboranes in complexation with transition metals. Boron clusters anions [B_nH_n]^2–, monocarborane anions [CB_nH_n–1]^–, and dicarboranes [C₂B_nH_n–2] (with non-functionalized carbon atoms) (n = 10, 12) containing the B–X exo-polyhedral bonds (X = N, O, S, Hal) are discussed. Synthesis and structural features of complexes known to date are described. The effect of complexing metal and substituent attached to the boron cage on the composition and structures of the final complexes is analyzed. It has been established that substituted derivatives of boron cluster anions and carboranes can act as both ligands and counterions. A complexing agent can coordinate substituted derivatives of the boron cluster anions due to three-center two-electron 3c2e MHB bonds, by the substituent functional groups, or a mixed type of coordination can be realized, through the BH groups of the boron cage and the substituent. As for B-substituted carboranes, complexes with coordinated substituents or salts with non-coordinated carborane derivatives have been isolated; compounds with MHB bonding are not characteristic of carboranes.

The study deals with reactions of the closo-decaborate anion [B10H10]2−with a number of nucleophiles (cyclic ethers and thioethers, N,N-substituted amides, and nitriles) in the presence of Lewis...

The interaction of (Bu₄N)₂[2-B₁₀H₉OН] with nickel(II) chloride in the presence of nitrogen-containing ligands, in particular, 1,10-phenanthroline, 2,2'-bipyridylamine, 2,2'-bipyridyl, and 2,6-diaminopyridine, has been studied. It has been shown that nickel(II) complexes containing the [2-B₁₀H₉OH]^2– anion as a counterion are formed in the course of the reactions. The synthesized compounds have been investigated by elemental analysis, IR spectroscopy and X-ray diffraction.

The interaction of the [B10H9O2C4H8]−, [B10H9OC4H8]−, and [B10H9OC5H10]−anions with negatively charged N-nucleophiles has been studied. It has been shown that such reactions yield doubly charged...

The reaction between the 1,4-dioxane derivative of the closo-decaborate anion [2-B₁₀H₉O(CH₂)₄O]^– with cyanide, hydrophthalate, and hydroiminoacetate ions has been studied. Alkali metal salts (K, Na, and Cs) of the closo-decaborate anion derivatives with pendant groups –NHCH₂CH₂NH₂-, –OOC(o-C₆H₄)COOH-, –OOCCH₂NHCH₂COOH-, –OCH₂CH₂OH-, –CN-, –SCN-, and –SH- have been isolated. All compounds have been shown to have extremely low cytotoxicity (CT₅₀ ~ 1000 μg/mL). It has been found that compounds Na₂[B₁₀H₉O(CH₂)₂O(CH₂)₂SCN] and Na₂[B₁₀H₉O(CH₂)₂O(CH₂)₂CN] exhibit activity and selectivity in vitro against the modern strain of SARS-CoV-2 coronavirus (IC₅₀ 312 and 625 μg/mL, respectively). In relation to influenza A virus and rabies virus, the compounds show weak antiviral activity at high concentrations (1250 μg/mL), i.e. show no selective effect on the reproduction of these viruses.

The reactions of 1,4-dioxane derivative of closo-decaborate anion with hydrazine and a number of polyamines (tetraethylenepentamine, triethylenetetramine, tris(2-aminoethyl)amine,...