Dihydrogen Bonds in Salts of Boron Cluster Anions [BnHn]2− with Protonated Heterocyclic Organic Bases

Dihydrogen bonds attract much attention as unconventional hydrogen bonds between strong donors of H-bonding and polyhedral (car)borane cages with delocalized charge density. Salts of closo-borate anions [B10H10]2− and [B12H12]2− with protonated organic ligands 2,2’-dipyridylamine (BPA), 1,10-phenanthroline (Phen), and rhodamine 6G (Rh6G) were selectively synthesized to investigate N−H...H−B intermolecular bonding. It was found that the salts contain monoprotonated and/or diprotonated N-containing cations at different ratios. Protonation of the ligands can be implemented in an acidic medium or in water because of hydrolysis of metal cations resulting in the release of H3O+ cations into the reaction solution. Six novel compounds were characterized by X-ray diffraction and FT-IR spectroscopy. It was found that strong dihydrogen bonds manifest themselves in FT-IR spectra that allows one to use this technique even in the absence of crystallographic data

Silver and Copper Complexes with closo-Polyhedral Borane, Carborane and Metallacarborane Anions: Synthesis and X-ray Structure

Synthesis and structure of silver and copper salts and complexes with polyhedral boron hydride anions, including closo-decaborate [B10H10]2−, closo-dodecaborate [B12H12]2−, 1-carba-closo- decaborate [1-CB9H10]−, carba-closo-dodecaborate [CB11H12]−, and cobalt bis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− anions and their derivatives, are reviewed. The complexes demonstrate a wide variety of structural types, relating to both the metal coordination environment and coordination modes of boron hydride anions. The latter can range from strong coordination via the polyhedron triangular face including formation of 3c-2e MHB bonds in the case of the [B10H10]2− dianion, the structure of which contains two four-coordinated boron atoms, to very weak M…H interactions with the hydride atoms in the case of bulky [3,3′-Co(1,2-C2B9H11)2]− monoanion

Evaluation of ferromagnetic #uids and suspensions for the site-speci"c radiofrequency-induced hyperthermia of MX11 sarcoma cells in vitro

Abstract Seventeen di!erent ferromagnetic #uids and suspensions were prepared and evaluated for application in radiofrequency-induced hyperthermia. Speci"c power absorption rates were measured at 0.88 MHz to range from 0 to 240 W per gram of iron for di!erent preparations. Survival of MX11 cells mixed with ferro#uids and subjected to radiofrequency was much lower than with RF without ferro#uid or ferro#uid alone

Nucleophilic Substitution Reactions in the [B3H8]− Anion in the Presence of Lewis Acids

As a result of our study on the interaction between the octahydrotriborate anion with nucleophiles (Nu = THF, Ph3P, Ph2P-(CH2)2-PPh2 (dppe), Ph3As, Et3N, PhNH2, C5H5N, CH3CN, Ph2CHCN)) in the presence of a wide range of Lewis acids (Ti(IV), Hf(IV), Zr(IV), Al, Cu(I), Zn, Mn(II), Co(II) halides and iodine), a number of substituted derivatives of the octahydrotriborate anion [B3H7Nu] are obtained. It is found that the use of TiCl4, AlCl3, ZrCl4, HfCl4, CuCl and iodine leads to the highest product yields. In this case, it is most likely that the reaction proceeds through the formation of an intermediate [B3H7-HMXnx], which was detected by NMR spectroscopy. The structures of [Ph3P·B3H7] and [PhNH2·B3H7] were determined by X-ray diffraction

Theoretical QTAIM, ELI-D, and Hirshfeld Surface Analysis of the Cu–(H)B Interaction in [Cu₂(<i>bipy</i>)₂B₁₀H₁₀]

Interaction of [Cu₂B₁₀H₁₀] with 2,2′-bipyridine (<i>bipy</i>) afforded a novel binuclear discrete complex of the [Cu₂(<i>bipy</i>)₂B₁₀H₁₀] composition. Two copper­(I) atoms coordinate a bridge boron cage through an apical edge and a triangular BBB face situated at its opposite apical vertices to form four 3c2e (CuHB) and one 2c2e Cu–B bonds. The charge density model was obtained by density functional theory calculations of isolated molecule and crystal. The resultant densities were analyzed using the quantum theory of atoms in molecules (QTAIM) and electron localizability indicator (ELI-D). The geometry and the topological parameters of copper­(I) coordination environment were found to be sensitive to crystal-field effect. An annulus of flat electron density ρ­(<i>r</i>) and small ∇²ρ­(<i>r</i>) is formed at dianion faces. As a result, some of the expected B–B, Cu–B, or Cu–H bond critical points are absent. The topological instability in the region of multicentered bonds is observed. The Cu–B bonding was found to be presumably electrostatic in nature, which could be the reason of topological isomerism for copper­(I) decaborates. The results show that an unambiguous real-space criterion for multicentered bonding between transition metals and polyhedral boron anions is not yet given. The molecular graph for this class of compounds does not provide a definitive picture of the chemical boding and can be complemented with other descriptors, such as virial graphs and the ELI-D distribution

Theoretical QTAIM, ELI-D, and Hirshfeld Surface Analysis of the Cu–(H)B Interaction in [Cu₂(<i>bipy</i>)₂B₁₀H₁₀]

Interaction of [Cu₂B₁₀H₁₀] with 2,2′-bipyridine (<i>bipy</i>) afforded a novel binuclear discrete complex of the [Cu₂(<i>bipy</i>)₂B₁₀H₁₀] composition. Two copper­(I) atoms coordinate a bridge boron cage through an apical edge and a triangular BBB face situated at its opposite apical vertices to form four 3c2e (CuHB) and one 2c2e Cu–B bonds. The charge density model was obtained by density functional theory calculations of isolated molecule and crystal. The resultant densities were analyzed using the quantum theory of atoms in molecules (QTAIM) and electron localizability indicator (ELI-D). The geometry and the topological parameters of copper­(I) coordination environment were found to be sensitive to crystal-field effect. An annulus of flat electron density ρ­(<i>r</i>) and small ∇²ρ­(<i>r</i>) is formed at dianion faces. As a result, some of the expected B–B, Cu–B, or Cu–H bond critical points are absent. The topological instability in the region of multicentered bonds is observed. The Cu–B bonding was found to be presumably electrostatic in nature, which could be the reason of topological isomerism for copper­(I) decaborates. The results show that an unambiguous real-space criterion for multicentered bonding between transition metals and polyhedral boron anions is not yet given. The molecular graph for this class of compounds does not provide a definitive picture of the chemical boding and can be complemented with other descriptors, such as virial graphs and the ELI-D distribution