Solvent extraction of microamounts of strontium and barium from water into nitrobenzene using hydrogen dicarbollylcobaltate in the presence of benzo-18-crown-6

Extraction of microamounts of strontium and barium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻¹) in the presence of benzo-18-crown-6 (B18C6, L) has been investigated. The equilibrium data been explained assuming that the complexes HL⁺, ML²⁺, ML₂²⁺ and MHL₂³⁺ (M²⁺ = Sr²⁺, Ba²⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Synthesis and properties of the dissymmetrical dinuclear complex of cobalt(iii) witho-carborane(12) derivatives

Dinuclear dicobaltacarborane with three different carborane fragments, [(C₂B₉H₁₁)Co(C₂B₈H₁₀)Co(C₂B₈H₁₀)]^2–, has been synthesized, and its properties have been studied by means of DTA and IR, UV,¹H and¹¹B NMR spectroscopy techniques. It has been found that at 138 °C this complex undergoes thermal isomerization associated with the migration of a carbon atom in the (CoC₂B₈H₁₀)⁺ fragment to a position with a lower coordination number.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 972–974, May, 1993.     

Strukturelle Untersuchungen an Cs2[B12H12]

Structural Investigations on Cs₂[B₁₂H₁₂] The crystal structure of Cs₂[B₁₂H₁₂] has been determined from X‐ray single‐crystal data collected at room temperature. Dicesium dodecahydro‐closo‐dodecaborate crystallizes as colourless, face‐rich crystals (cubic, Fm 3; a = 1128.12(7) pm; Z = 4). Its synthesis is based on the reaction of Na[BH₄] with BF₃(O(C₂H₅)₂) via the decomposition of Na[B₃H₈] in boiling diglyme, followed by subsequent separations, precipitations (with aqueous CsOH solution) and recrystallizations. The crystal structure is best described as anti‐CaF₂‐type arrangement with the Cs⁺ cations in all tetrahedral interstices of the cubic closest‐packed host lattice of the icosahedral [B₁₂H₁₂]^2–‐cluster dianions. The intramolecular bond lengths are in the range usually found in closo‐hydroborates: 178 pm for the B–B and 112 pm for the B–H distance. Twelve hydrogen atoms belonging to four [B₁₂H₁₂]^2– icosahedra provide an almost perfect cuboctahedral coordination sphere to the Cs⁺ cations, and their distance of 313 pm (12 ×) attests for the salt‐like character of Cs₂[B₁₂H₁₂] according to {(Cs⁺)₂([B₁₂H₁₂]^2–)}. The ¹¹B{¹H}‐NMR data in aqueous (D₂O) solution are δ = –12,70 ppm (¹J_B–H = 125 Hz), and δ = –15,7 ppm (linewidth: δν_1/2 = 295 Hz) for the solid state ¹¹B‐MAS‐NMR.     

Thermal Dehydrogenation of Base‐Stabilized B2H5+ Complexes and Its Role in CH Borylation

Thermally induced dehydrogenation of the H‐bridged cation L₂B₂H₅⁺ (L=Lewis base) is proposed to be the key step in the intramolecular C? H borylation of tertiary amine boranes activated with catalytic amounts of strong “hydridophiles”. Loss of H₂ from L₂B₂H₅⁺ generates the highly reactive cation L₂B₂H₃⁺, which in its sp²‐sp³ diborane(4) form then undergoes either an intramolecular C? H insertion with B? B bond cleavage, or captures BH₃ to produce L₂B₃H₆⁺. The effect of the counterion stability on the outcome of the reaction is illustrated by formation of LBH₂C₆F₅ complexes through disproportionation of L₂B₂H₅⁺ HB(C₆F₅)₃^?.     

Cover Feature: Are the Accompanying Cations of Doping Anions Influential in Conducting Organic Polymers? The Case of the Popular PEDOT (Chem. Eur. J. 63/2019)

Conducting organic polymers (COPs) are made of a conjugated polymer backbone supporting a certain degree of oxidation. These positive charges are compensated by the doping anions that are introduced into the polymer synthesis along with their accompanying cations. In this work, the influence of these cations on the stoichiometry and physicochemical properties of the resulting COPs have been investigated, something that has previously been overlooked, but, as here proven, is highly relevant. As the doping anion, metallacarborane [Co(C₂B₉H₁₁)₂]⁻ was chosen, which acts as a thistle. This anion binds to the accompanying cation with a distinct strength. If the binding strength is weak, the doping anion is more prone to compensate the positive charge of the polymer, and the opposite is also true. Thus, the ability of the doping anion to compensate the positive charges of the polymer can be tuned, and this determines the stoichiometry of the polymer. As the polymer, PEDOT was studied, whereas Cs⁺, Na⁺, K⁺, Li⁺, and H⁺ as cations. Notably, with the [Co(C₂B₉H₁₁)₂]⁻ anions, these cations are grouped into two sets, Cs⁺ and H⁺ in one and Na⁺, K⁺, and Li⁺ in the second, according to the stoichiometry of the COPs: 2:1 EDOT/[Co(C₂B₉H₁₁)₂]⁻ for Cs⁺ and H⁺, and 3:1 EDOT/[Co(C₂B₉H₁₁)₂]⁻ for Na⁺, K⁺, and Li⁺. The distinct stoichiometries are manifested in the physicochemical properties of the COPs, namely in the electrochemical response, electronic conductivity, ionic conductivity, and capacitance.     

Intermolecular dihydrogen‐ and hydrogen‐bonding interactions in diammonium closo‐decahydrodecaborate sesquihydrate

The asymmetric unit of the title salt, 2NH₄⁺·B₁₀H₁₀²⁻·1.5H₂O or (NH₄)₂B₁₀H₁₀·1.5H₂O, (I), contains two B₁₀H₁₀²⁻ anions, four NH₄⁺ cations and three water molecules. (I) was converted to the anhydrous compound (NH₄)₂B₁₀H₁₀, (II), by heating to 343 K and its X‐ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen‐bonding interactions (N—H...O and O—H...O) and two types of dihydrogen‐bonding interactions (N—H...H—B and O—H...H—B). The N—H...H—B dihydrogen bonding forms a two‐dimensional sheet structure, and hydrogen bonding (N—H...O and O—H...O) and O—H...H—B dihydrogen bonding link the respective sheets to form a three‐dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H₂ at a faster rate than (NH₄)₂B₁₂H₁₂ and we believe that this is due to the stronger dihydrogen‐bonding interactions shown in the hydrate (I).     

Solvent extraction of microamounts of yttrium from water into nitrobenzene by using hydrogen dicarbollylcobaltate in the presence of benzo-15-crown-5

Summary Extraction of microamounts of yttrium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of benzo-15-crown-5 (B15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL, YL³⁺, YL and YH_-1L are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Synthesis and structure of 9-hydroxy-1,2-dicarba-closo-dodecaborane(11)

The oxidation of 1,2-C₂B₁₀H₁₂ (1) with 100% nitric acid was studied in two solvents (CH₂C1₂ and CCl₄). Under the action of superacid (CF3SO3H), the compound 9-HO-1,2-C₂B₁₀H₁₁ (2) gives the onium cation 9-H₂O⁺-1,2-C₂B₁₀H₁₁ involved in the salt [9-H₂O⁺-1,2-C₂B₁₀H_n]-CF₃SO₃^?, as demonstrated by ^uB NMR spectroscopy. The experimental and simulated ^uB NMR spectra of the cation 9-H₂O⁺-1,2-C₂B₁₀H₁₁ are in satisfactory agreement with each other. In the presence of a base, compound 2 is transferred from an ethereal solution to an aqueous alkaline solution giving the anion 9-O^?- 1,2-C₂B₁₀H₁₁. The structure of compound 2 was confirmed by ¹H, ¹¹B, ¹¹B¹H, ¹¹B-¹¹B COSY NMR spectroscopy, IR spectroscopy, and gas chromatography mass spectrometry and was additionally established by X-ray diffraction.

     

Thermal Dehydrogenation of Base‐Stabilized B2H5+ Complexes and Its Role in C?H Borylation

Thermally induced dehydrogenation of the H‐bridged cation L₂B₂H₅⁺ (L=Lewis base) is proposed to be the key step in the intramolecular C H borylation of tertiary amine boranes activated with catalytic amounts of strong “hydridophiles”. Loss of H₂ from L₂B₂H₅⁺ generates the highly reactive cation L₂B₂H₃⁺, which in its sp²‐sp³ diborane(4) form then undergoes either an intramolecular C H insertion with B B bond cleavage, or captures BH₃ to produce L₂B₃H₆⁺. The effect of the counterion stability on the outcome of the reaction is illustrated by formation of LBH₂C₆F₅ complexes through disproportionation of L₂B₂H₅⁺ HB(C₆F₅)₃⁻.     

Theoretical study of the mechanism for C-H bond activation in spin-forbidden reaction between Ti<Superscript>+</Superscript> and C<Subscript>2</Subscript>H<Subscript>4</Subscript>

The mechanism of the spin-forbidden reaction Ti⁺(⁴F, 3d²4s¹) + C₂H₄→TiC₂H₂ ⁺ (²A₂) + H₂ on both doublet and quartet potential energy surfaces has been investigated at the B3LYP level of theory. Crossing points between the potential energy surfaces and the possible spin inversion process are discussed by means of spin-orbit coupling (SOC) calculations. The strength of the SOC between the low-lying quartet state and the doublet state is 59.3 cm⁻¹ in the intermediate complex IM1-⁴B₂. Thus, the changes of its spin multiplicity may occur from the quartet to the doublet surface to form IM1-²A₁, leading to a sig-nificant decrease in the barrier height on the quartet PES. After the insertion intermediate IM2, two distinct reaction paths on the doublet PES have been found, i.e., a stepwise path and a concerted path. The latter is found to be the lowest energy path on the doublet PES to exothermic TiC₂H₂ ⁺(²A₂) + H₂ products, with the active barrier of 4.52 kcal/mol. In other words, this reaction proceeds in the following way: Ti⁺+C₂H₄→⁴IC→IM1-⁴B₂→^4,2ISC→IM1-²A₁→[²TS_ins]→IM2→[²TS_MCTS]→IM5→TiC₂H₂ ⁺(²A₂)+H₂. Supported by ‘Qinglan’ Talent Engineering Funds by Tianshui Normal University.     

Reactions of Icosahedral Carboranes with Iminotris(dimethylamino)Phosphorane HNP(NMe2)3: a Deboronation Intermediate nido-C2B10H12·N(H)P(NMe2)3, Deboronation Reactions and Hydrogen-bonded Closo-carborane Systems

Reactions between the icosahedral carboranes 1,2-C₂B₁₀H₁₂ (1), 1,7-C₂B₁₀H₁₂ (2) and 1,12-C₂B₁₀H₁₂ (3) and the iminophosphorane HNP(NMe₂)₃ (4) are described that have afforded a variety of products whose structures have been characterised by X-ray diffraction. They include the adduct between (1) and (4), C₂B₁₀H₁₂·HNP(NMe₂)₃ (5) the 12-atom 14-skeletal pair supra-icosahedral nido structure of which illustrates an early step in the deboronation of ortho-carborane (1) by Lewis Bases, and the C–H⋯N hydrogen-bonded adducts of meta- and para-carborane with the iminophosphorane, [1,7-C₂B₁₀H₁₂⋯HNP(NMe₂)₃] _n and 1,12-C₂B₁₀H₁₂ 2HNP(NMe₂)₃. The iminophosphorane (4) readily converts ortho-carborane (1) into the nido anion [7,8-C₂B₉H₁₂]⁻ and less readily meta-carborane (2) into the nido-anion [7,9-C₂B₉H₁₂]⁻, which have been isolated from solution as salts of the cations [H₂NP(NMe₂)₃]⁺ or [{(Me₂N)₃PN}₂BNHP(NMe₂)₃]⁺, the latter evidently incorporating a boron atom removed from the carborane cage. Adventitious presence of water in the attempted recrystallization of [{(Me₂N)₃PN}₂BNHP(NMe₂)₃]⁺ [7,8-C₂B₉H₁₂]⁻ led to a salt of the cation [{(Me₂N)₃PNBN(H)P(NMe₂)₃}₂O]²⁺. Other unexpected products isolated from reactions carried out under moist air included the salt [H₂NP(NMe₂) ₃ ⁺ ]₂[CO ₃ ²⁻ ]·2B(OH)₃ (from the reaction between 2 and 4) and the salt 1,12-C₂B₁₀H₁₂·2H₂NP(NMe₂) ₃ ⁺ HCO ₃ ⁻ (from the reaction between 3 and 4).Dedicated to Prof. Brian F.G. Johnson, in recognition of his major contributions to cluster chemistry and warm friendship over the years.     

Extraction of microamounts of yttrium from water into nitrobenzene using hydrogen dicarbollylcobaltate in the presence of 15-crown-5

Summary Extraction of microamounts of yttrium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of 15-crown-5 (15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL_2,⁺, YL³⁺, YL_2,³⁺and YH_-1L_2,²⁺are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Molecular fragmentations: Part II. Structures and energies of molecular fragments derived from formamide and its molecular cation

Molecular geometries and heats of formation have been calculated, using MINDO/3, for mass spectral fragment pairs (A⁺ + B) derived from formamide. There are five stable isomeric forms of the molecular ion: [H₂NC(OH)]⁺, (H₃NCO)⁺, [HNC(OH₂)]⁺, [NCH(OH₂)]⁺, and (NCOH₃)⁺ (in order of increasing

, but no isomer (H₂NCHO)⁺. There are three isomeric forms of (M—H)⁺: (H₂NCO)⁺ (HNCOH)⁺, and (NCOH₂)⁺: the only stable form of (M—2H)⁺ is (NCOH)⁺. Other (A/B)⁺ fragment pairs calculated are (CO/NH₃)⁺, (HCO/NH₂)⁺, (H₂O/HCN)⁺, (H₂O/HNC)⁺ [HO^. + (HCNH)⁺], and [HO^. + (H₂NC)⁺]. The structure of the doubly charged ion M²⁺ is also reported.     

New Complexes of Ditopic Ligands with “d” and/or “s” Metal Ions

Abstract

The asymmetric compartmental macrocycles containing one N₂O₂ or N₃O₂ Schiff base and one O₂O₃ or O₂O₄ crown-ether like chamber, have been obtained by condensation reaction of the formyl precursors 3,3′-(3-oxapentane-1, 5-diyldioxy) bis (2-hydroxybenzaldehyde) or 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)-bis(2-hydroxybenzaldehyde) with ethyl ethylenediamine (H₂L_A, H₂L_C), 1,5-diamino-3-azamethylpentane(H₂L_B, H₂L_D), also in the presence of metal ions as templating agents. These ditopic ligands, with dissimilar coordination sites, have been designed and used for the selective complexation of “d” and/or “s” metal ions, respectively into the Schiff base and the crown ether chamber. The selectivity of these processes strongly depends on the size and on the donor atom sets of the sites. The possibility to obtain mononuclear M(L)·nH₂O (M = Ni²⁺, Cu²⁺, Co²⁺), Mn(L)(CH₃COO)·nH₂O or Na(L) and hetero-dinuclear MNa(L)(CH₃COO) (M = Ni²⁺, Cu²⁺, Co²⁺) and MnNa(L)(CH₃COO)₂·nH₂O complexes has been successfully tested. The ligands and complexes have been characterized by ir, nmr, mass spectrometry and magnetic susceptibility measurements.

Two of the ligands used for the preparation of the solid samples, i.e., to H₂L_A and H₂L_B, have been employed to study complexation reactions of Co(II) and Na(I) in solution. In order to obtain information on the ligand preorganization effect toward the complex stabilities, a simpler open chain parent compound of H₂L_B (H₂L_E) has been also prepared and studied. FT-IR spectra show that H₂L_A is unable to complex Na⁺ in DMSO while the complexation reactions of Na⁺ by H₂L_B and of Co²⁺ by H₂L_A take place with slow kinetics. Therefore, thermodynamic data have been obtained only for the systems Co²⁺/H₂L_B and Co²⁺/H₂L_E. The thermodynamic parameters obtained for the complexation reactions show that the pre-organization of the donor atoms in H₂L_B does not add a significant contribution to the stabilities of the complexes. Both H₂L_B and H₂L_E form in DMSO 1:1, 1:2 and 1:3 = M:L complexes with very similar stabilities and almost equal enthalpies of formation. Physico-chemical studies suggest besides that the slow reaction of Na⁺ with H₂L_B is probably due to the formation of a 1:1 complex where the metal cation, initially occupying the O₃ cage of the ligand, slowly binds also the oxygens of the phenolic moieties. Spectral and calorimetric data on solutions containing H₂L_B and different Co²⁺: Na⁺ ratios evidence that in DMSO no stable heterodinuclear complexes form when the neutral ligand is considered.     

Coordination polymers constructed from an asymmetric dicarboxylate and N-donors: preparation,characterization, and properties

Two new coordination polymers with an asymmetric dicarboxylate and 4,4′-bipyridine ligand, {[Co(bpy)(H₂O)₄]·(cpa)·0.5H₂O}_n (1) and {[Ag(cpa)(bpy)][Ag(bpy)]·4H₂O}_n (2) (H₂cpa = 4-(2-carboxyethyl)benzoic acid, bpy = 4,4′-bipyridine), have been hydrothermally synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffraction. Compound 1 displays a linear chain with guest molecule (cpa)^2? ions existing in the structure. Compound 2 contains two independent units, [Ag(cpa)(bpy)]^– (A) and [Ag(bpy)]⁺ (B), which form a 1-D + 1-D structure. A shows a 1-D chain structure bearing hooks formed by the carboxylates and organized into a tubular structure by hydrogen-bonding interactions. B has linear chains formed from Ag⁺ and bpy. The A and B chains co-crystallize with waters of crystallization to provide two linear [Ag(bpy)]⁺ chains embedded in the tubular structure formed by A via π…π stacking contacts. In 1 and 2, hydrogen-bonding and π…π stacking interactions connect the discrete 1-D chains into 3-D supramolecular structures. The fluorescent properties, TG analysis, and X-ray powder diffraction patterns for 1 and 2 were also measured.     

Darstellung und schwingungsspektroskopische Untersuchung von [H3B?Se?Se?BH3]2− und [H3B-μ2-Se(B2H5)]− Kristallstruktur und theoretische Untersuchung der Molekülstruktur von [H3B-μ2-Se(B2H5)]−

Synthesis and Vibrational Spectroscopic Investigation of [H₃B? Se? Se? BH₃]^2? and [H₃B-μ₂-Se(B₂H₅)]^? Crystal Structure and Theoretical Investigation of the Molecular Structure of [H₃B-μ₂-Se(B₂H₅)]^? M₂[H₃B? Se? Se? BH₃] 1 is produced by the reaction between elemental selenium and MBH₄ (1 : 1) in triglyme (diglyme), under dehydrogenation. 1 reacts with an excess of B₂H₆ to give M[H₃B-μ₂-Se(B₂H₅)] 2 which is also formed in the reaction of THF · BH₃ with 1 . These reactions proceed under cleavage of the Se? Se bond and hydrogen evolution. [(C₆H₅)₄]Br reacts with Na · 2 to form [(C₆H₅)₄P] · 2 which crystallizes in the tetragonal space group I4 (Nr. 82). An X-ray structure determination failed because of disordering of the cation and anion. ¹¹B, ⁷⁷Se NMR shifts and ¹J(¹¹B¹H) coupling constants as well as IR- and Raman spectroscopic investigations convey further structural information. Structural data of 2 have been calculated by SCF methods. The anion of 2 may be viewed either as an adduct of Se with B₃H₈^?, or as a bridge substituted selena derivative of B₂H₆.     

A fano-profile study of the predissociation of the 3pπ D1Πu+ state of H2

The predissociation of H₂ molecules in the 3pπ D ¹Π_u⁺ state has been studied by Fano-profile analysis of the R(0) and R(1) lines from υ = 3 to υ = 11. The predissociation probabilities have been measured. Strong indication of the opening of a new channel of dissociation is reported. Coupling with the B^υB?¹Σ_u⁺ state may be responsible for this.     

Extraction of cesium by the nitrobenzene solution of hydrogen bis-1,2-dicarbollylcobaltate in the presence of 15-crown-5

Extraction of microamounts of cesium by the nitrobenzene solution of H⁺ bis-1,2-dicarbollylcobaltate (H⁺B⁻) in the presence of 15-crown-5 (15C5, L) has been investigated. The equilibrium data have been explained assuming the complexes HL⁺, HL₂ ⁺, CsL⁺ and CsL₂ ⁺ to be extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

The Liquid Junction Potential in Potentiometric Titrations. IX. The Calculation of Potentials Across Liquid Junctions of the Type, AY|AY+BY z(B)+HY+ A y L, for Emf Cells where Strong or Weak Complexes are Formed, Respectively, at [Y−] = C mol⋅L−1, Constant and −log 10[H+]≤ 7

In the present part, potential functions are derived for the calculation of the total potential anomalies, Δ E _B and Δ E _H, for Emf cells where strong or weak complexes are formed, respectively. A weak or strong electrolyte is considered to be used as complexing agent (A _y L), respectively, at the experimental condition, [Y^?] = C mol?L^?1, constant. The cells have indicator electrodes reversible to B ^z(B)+ (cell B) and H⁺ ions (cell H), respectively. The system, HY–BY _z(B)-A _Y L-AY and the protolysis of the acids HL and H₂L in the ionic medium (A⁺, Y^?) are studied. Here, y = |z _L |. Moreover, some useful Emf titrations are suggested for the experimental determination of the slope functions SL(H, L^?), SL (H, L^2?) and SL(H, HL^?). The usefulness of the derived potential functions is established using the H⁺-acetate^? (CH₃COO^?) system as an example.     

A family of mixed-ligand oxovanadium(V) complexes incorporating tridentate ONO donor hydrazone ligands derived from acetylhydrazide and 2-hydroxybenzaldehyde/2-hydroxyacetophenone

In the title family the tridentate ONO donor ligands are the fully deprotonated forms of acetylhydrazones of 2-hydroxybenzaldehyde (H₂L¹) and 2-hydroxyacetophenone (H₂L²) (general abbreviation H₂L), while bidentate mononegative OO donor ligands are the deprotonated salicylaldehyde (Hsal), vanillin (Hvan) and monodeprotonated 1,2-ethanediol (H₂ed) (general abbreviation HB). The reaction of V^IVO(acac)₂ with H₂L and Hsal or Hvan in equimolar ratio in MeOH afforded the complexes of the type [V^VO(L)(B)], (1)–(4). The reaction of V^IVO(acac)₂ with H₂L¹ (in an equimolar ratio) and an excess of H₂ed in MeOH yielded the complex [V^VO(L¹)(Hed)], (5) but the similar reaction with H₂L² ligand failed to produce such a type of complex. Complexes have been characterized by elemental analyses and by i.r., n.m.r. and u.v.-vis. spectroscopies. All the complexes are diamagnetic and display only LMCT bands. ¹H-n.m.r. spectral data indicate that complexes (1)–(4) exist in two isomeric forms [(1A), (1B); (2A), (2B); (3A), (3B) and (4A), (4B)] in different ratios in CDCI₃ solution. Complexes (1)–(4) display a quasi-reversible one electron reduction peak in the −0.06 to +0.05 V versuss.c.e. region in CH₂CI₂ solution and (5) displays an irreversible reduction peak at −0.46 V versuss.c.e. in DMF solution. The trend in the redox potential values has been correlated with the basicity of both the primary and auxiliary ligands.