L. V. Goeva

Synthesis and derivatization of the 2-amino-closo-decaborate anion [2-B10H9NH3]-

Abstract A novel high-yield method of synthesis of the [2-B10H9NH3]− anion was elaborated. The method proposed includes reaction of the closo-decaborate anion with acetonitrile in the presence of acid, followed by hydrolysis of the formed nitrilium derivative [2-B10H9NCMe]− first to the acetamide derivative [2-B10H9NH2COMe]− and then to the amine. The crystal molecular structure of (Bu4N)[2-B10H9NHC(OH)Me] was determined by single crystal X-ray diffraction method. In the solid state, the acetamide derivative exists in the O-protonated tautomeric form and has a Z-configuration where the NH proton and the OH group are trans around the CN bond. The reaction of the [2-B10H9NH3]− anion with aromatic aldehydes in methanol in the presence of catalytic amounts of alkali gives N-protonated Schiff bases [2-B10H9NHCHR]− (R=C6H5, C6H4-2-OMe, C6H4-4-NHCOMe). Reduction of the Schiff bases with NaBH4 in aqueous methanol gives the corresponding monoalkylamino derivatives [2-B10H9NH2CH2R]− (R=C6H5, C6H4-2-OMe, C6H4-4-NHCOMe). The approach developed can be used in the synthesis of functional derivatives of the closo-decaborate anion for applications in nuclear medicine.

Specific interactions in metal salts and complexes with cluster boron anions BnHn2− (n = 6, 10, 12)

Specific interactions that appear in metal salts and complexes with cluster boron anions BnHn2− (n = 6, 10, 12) have been discussed. These interactions, as well as chemical bonds, involve vertices, edges, or faces of boron polyhedra. Specific interactions have a considerable effect on the structure of compounds, making a significant contribution to the formation of the unit cell and forming supramolecular assemblies. Compounds containing BnHn2− cluster anions shed new light onto the nature of specific interactions owing to their many-center character and great variety.

Coordination compounds of electron-deficient boron cluster anions BnHn2− (n = 6, 10, 12)

This survey concerns the coordination ability of BnHn2− (n = 6, 10, 12) boron cluster anions and their derivatives in complex formation. Boron cluster anions form four types of compounds: salts of organic cations and alkali-metal cations, including Cat2BnHn, where specific interactions can be observed between a cation Cat and a boron cluster anion; salts of protonated anions CatB6H7 and CatB10H11, analogues of Cat[MBnHn] complexes, where an extra hydrogen atom appears bound with the BBB face of a boron polyhedron and performs as a hard acceptor; metal complexes with outer-sphere boron cluster anions where specific ligand-ligand interactions may be observed between a boron cluster anion and an inner-sphere ligand; and true metal complexes with boron cluster anions that enter the inner coordination sphere. The last case characterizes closo-hydroborate anions as polydentate ligands whose denticity can vary widely under the effect of substituents or other ligands in the complex.

Redox, complexation, and substitution reactions in [Cu2B10H10]-2,2′-bipyridylamine-CH3CN system

Reaction of [Cu2B10H10] with 2,2′-bipyridylamine (bpa) in acetonitrile was studied. A redox reaction was found to proceed in reaction solution at ambient temperature. Copper coordination compounds with the metal of different oxidation states—[Cu2I(bpa)2B10H10] · 2NCCH3, [Cu4II(bpa)4(OH)4][Cu2I(B10H10)3] · nNCCH3, [CuII(bpa)2(NCCH3)2](2-B10H9bpa)2 · 2H2O, [Cu2II(bpa)2(OH)2B10H10], and [(Cu2II(bpa)2(CO3)2] · H2O—were isolated under various reaction conditions. The compounds were characterized by IR spectroscopy, X-ray crystallography, and elemental analysis.

Aminoguanidinium closo-Borates and Their Reactions with Copper(II) Salts in Aqueous Solutions

Aminoguanidinium hexa-, deca-, and dodecaborates of (AguH)2BnHn· xH2O (Agu = (CN4H6), n= 6, 10, 12; x= 1, 2) composition were synthesized and studied by elemental analysis, magnetic susceptibility, and IR spectroscopy methods. Their reactions with copper(II) salts in aqueous solutions were investigated. A cation–anion interaction was shown to occur in aminoguanidinium closo-borates and to increase in the series B12< B10< B6. Depending on the closo-anion (BnH2–n), the reactions of aminoguanidinium closo-borates with copper(II) salts in aqueous solutions yield either complex compounds (n= 10, 12) or metallic copper (n= 6).

Copper(I) coordination compounds with closo-dodecaborate anion

Copper(I) complexes with a closo-dodecaborate anion were synthesized: Cat[CuB12H12], where Cat = Cs+, Ph4P+, Ph4As+, or RxNH4−x+ (R = Me, Et, Pr, or Bu; x = 3 or 4). The complexes were synthesized from the copper(II)-closo-dodecaborate-sulfur dioxide (sodium sulfite) system. The structure of [Cu2(NCCH3)4B12H12] was determined using X-ray crystallography.

Interactions of sodium liquid glass with triethylammonium decahydro-closo-decaborate (Et3NH)2B10H10

Reactions of sodium silicates of liquid glass (LG) with closo-triethylammonium decaborate (Et3NH)2B10H10 were studied over a wide range of component ratios LG/(Et3NH)2B10H10 of 95/5, 85/15, 70/30, 60/40, 50/50, 40/60, and 26/74 wt/wt. IR spectroscopy showed that the introduction of anion into the LG gives rise to the formation of a three-dimensionally branched system of multicenter bonds:

Behavior of dodecahydro-closo-dodecaborate anion B12H122− in reaction with Au(Ph3P)Cl

B - H^{\delta - } \cdots H^{\delta + } - O - H^{\delta + } \cdots O^{\delta - } - Si

Multicenter interactions in lead(II) coordination compounds with BnHn2− = 6, 10, 12) cluster anions and their derivatives

and

The Mechanism of Acid-Catalyzed Nucleophilic Substitution in Decahydro-closo-Decaborate(2–) Anions

B - H^{\delta - } \cdots H^{\delta + } - O \cdots H - O - H \cdots O^{\delta - } - Si