The separation of minor actinides from high level liquid waste (HLLW) belongs to the principal challenges in current nuclear treatment. A derivative based on two cobalt bis(dicarbollide) (1−) ions covalently bound to the N,N′-di-n-octyl diglycolyl amide platform via diethyleneglycol chain with the formula {[(N,N′-(8-(OCH2 CH2)2-1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Co)(N,N′-n-C8H17)NCOCH2]2O}Na2 (TODGA-COSAN), dissolved in low polar mixture of hexyl methyl ketone and n-dodecane, was used as an extractant for efficient Am(III)/Eu(III) separation from PUREX HLLW. Am(III) could be selectively stripped from loaded organic phase by using a stripping agent composed from 0.05 M DTPA and 1 M citric acid as a buffer and 1 M NaNO3 at pH 3.0. Separation factor between europium and americium of 13 was achieved. The europium remaining in the organic phase could be consecutively effectively stripped by using solution of ammonium citrate or ammonium citrate with ammonium DTPA at pH~7.

Abstract The separation of minor actinides from high-level waste (HLW) remains a difficult problem. A wide series of compounds based on two cobalt bis(dicarbollide) ions [(1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Co(III)]− (1) covalently bonded to a diglycolyl amide platform via diethyleneglycol connectors was prepared by reaction of the diglycolic acid dichloride with various ammonium derivatives of the ion 1 with the aim to develop new class of extractants for trivalent radionuclides from acidic waste solutions. The extractants of general formulation [{(N,N-(8-CH2-CH2O)2-1,2-C2B9H10)(1′,2′-C2B9H11)-3,3′-Co)(N,N′-R)NCOCH2}2-O]Na2 differed in substitution on the amidic nitrogen (by e.g. butyl-, hexyl-, octyl-, t-octyl-, dodecyl-, benzyl-groups). Compounds were characterized by combination of 11B, 1H and 13C NMR spectroscopy, ESI-MS, HPLC, and TLC RF. The purity of all species was better than 98%. Most of the compounds proved to be very efficient extraction agents and enabled effective extraction of europium(III) and americium(III) from nitric acid solutions. The recovery of the trivalent radionuclides from the loaded organic phase was possible by using ammonium citrate or even better by using solution of ammonium citrate and ammonium DTPA (diethylenetriamine pentaacetate).

Ionic diamides composed of a N,N'-dialkyl diglycolyl complexing group and two cobalt bis(dicarbollide)(1-) anions were synthesized with the aim to develop efficient extraction agents for liquid-liquid extraction of polyvalent cations, i.e. lanthanides and actinides from high-level activity nuclear waste. Compounds of general formulation [{(N,N-(8-CH2-CH2O)(2)-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co)(N',N'-R)NCOCH2}(2)O]Na-2, where R = n-C4H9, n-C8H17, n-C12H25 and 1-C6H4-4-CH3 (1-4), were prepared and characterized by combination of B-11 H-1, C-13 NMR spectroscopy, ESI-MS, HPLC and other techniques. Effects of different nitrogen substitution in the structures of 1- 4 on the extraction properties were tested. The study resulted in the observation that the compounds are significantly (2-3 orders in magnitude) more efficient extractants for Eu(III) and Am(III) than synergic mixtures of organic N, N'-tetra n-octyl diglycolic acid diamide (TODGA) and chlorinated cobalt bis(dicarbollide) at the same concentrations of both groups. Low polar mixtures of n-dodecane (D) and hexyl methyl ketone (HMK) can be applied as an auxiliary solvent for extraction, replacing thus the polar and less environmentally friendly nitro-, fluoro- and chloro-solvents used in the current dicarbollide liquid-liquid extraction process. (C) 2010 Elsevier B.V. All rights reserved.

Compounds were synthesized with the aim to develop efficient extraction agents for liquid-liquid extraction of polyvalent cations, i.e. lanthanides and actinides from high-level activity nuclear waste. Compounds of general formulation [(8-CMPO-(CH 2 -CH 2 O) 2 -1,2-C 2 B 9 H 10 )(1′,2′-C 2 B 9 H 11 )-3,3′-Co(III)] - with different phosphorus and nitrogen substitution (CMPO= 2 R, 3 R P(O)-(CH 2 ) n C(O)N 1 R, 1 R= t -octyl, H, Ph, 2 R=Ph, n -octyl, 3 R=Ph, n =1,2)-( 4a to 4e ), were prepared and characterized by combination of 11 B NMR, 1 H high field NMR, ESI-M.S., HPLC and other techniques. Molecular structure of the sodium complex of ligand 4a ( 1 R= t -octyl, 2 R= 3 R=Ph, n =1) was determined by single crystal X-ray diffraction analysis. Effect of several modifications in the structure of 4a–4e on the extraction properties was outlined. The study resulted in the definition of ionic ligand with enhanced extraction efficiency for 4a,b ( t -octyl and H on the amidic nitrogen atom) and a better solubility of 4a and 4d ( 1 R= t -octyl, 2 R= n -Oct, 3 R=Ph, n =1) in less polar solvents. Low polar mixtures of hydrogenated tetrapropylene (TPH) hexyl methyl ketone (HMK) can be applied as an auxiliary solvent for 4a , selected for detailed studies, replacing thus the polar and less environmentally friendly nitro-, fluoro- and chloro- solvents used in the current dicarbollide liquid-liquid extraction process. Results of the fission products separation from the simulated PUREX feed using 4a are presented inclusive procedures for Eu 3+ stripping.

Various calix[4]arene and resorc[4]arene ionic compounds substituted by cobalt bis(dicarbollide) anions (1) have been prepared for the first time. From tBu-calix[4]arene (A) the complete series of mono-, di-, tri- and tetrasubstituted derivatives bearing one to four cluster anions on the lower rim (3-6) have been obtained in the form of their alkali-metal salts by O-alkylation with the 1-dioxane derivative [8-O(CH2CH2)2O(+)-1,2-C2B9H10)-(1',2'-C2B9H11)-3,3'-Co] (2), all of which are syn or cone isomers. In contrast, disubstitution of the dipropyl ether of tBu-calix[4]arene (B) led to a mixture of the cone and 1,3-alternate conformers 7a and 7b, respectively. Starting from tetrapropoxy-calix[4]arene functionalised at the upper rim by carboxylic acid groups in distal positions (C) and an amino-bridged derivative [8,8'--H2N<(1,2-C2B9H10)2-3,3'-Co] (8), calix[4]arene 9, disubstituted at the upper rim, was obtained as the main product along with the monosubstituted species 10. Di- and tetrasubstituted ionic products (11-15) were also obtained from resorcarene-based cavitands by O-alkylation with the 1-dioxane derivative 2. A pair of regioisomeric disubstitution products, 11a,b, was isolated in the case of the hydroxy cavitand D, while E, functionalised by hydroxymethyl groups on the wide rim, and F, bearing hydroxy groups on the alkylidene bridges, gave the 1,3-di- (12 and 14) and the tetrasubstituted compounds (13 and 15), respectively. The molecular structure of the electroneutral dicaesium complex of the dianion 4 was determined by single-crystal X-ray diffraction analysis. The two Cs+ cations are found in different coordination spheres in the structure of Cs24. Coordination of the Na+ cation by the diethylene glycol chain and one calixarene lower rim oxygen atom was found in the crystal structure of the Na complex of the monoanion 3.

New anion derivatives of the closo-decaborate [B10H10]2- bearing amine or phosphine groups were tested for the extraction of radioactive cesium cations in acidic medium. The technique used is the liquid-liquid extraction based on the complexation of Cs+ by these anions to form neutral compounds which are extracted by organic solvents (diluents) of medium polarity. Promising results were obtained with the anion [1-(C6H5CH2)2(C6H5)NB10H9]- (3) soluble in many organic solvents. The most efficient diluent for the extraction is nitrobenzene. Using hydrochloric acid or sulfuric acid in the aqueous medium instead of nitric acid does not significantly affect the efficiency of Cs+ extraction.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The equimolar reaction of 1-SH-2-R-1,2-closo-C2B10H10(R=Me, H, Ph) with KOH in ethanol produces the thiolate species [1-S-2-R-1,2-closo-C2B10H10]-. These react with iodine to give the disulfide bridged dicluster (1-S-2-R-1,2-closo-C2B10H10)2(R=H, Me, Ph) compounds as analytically pure, white and air-stable solids in high yield. Synthesis of monothioether bridged species is synthetically more difficult. In fact three procedures have been tested to obtain the thioether bridged dicluster compounds (2-R-1,2-closo-C2B10H10)2S (R=Me, H, Ph) but only (2-Me-1,2-closo-C2B10H10)2S was successfully synthesized and characterized. Attempts to produce mixed compounds (1-R-1,2-closo-C2B10H10)S(1-R'-1,2-closo-C2B10H10), R not=R', were unsuccessful. Deboronation reaction of this dicarboranylthioether lead, depending on the reaction conditions, to monoanionic [(2-Me-1,2-closo-C2B10H10)S(8-Me-7,8-nido-C2B9H10)]- or dianionic [(8-Me-7,8-nido-C2B9H10)2S]2- sulfur bridge anions. Deboronation of carboranyl disulfides gave the corresponding dianionic [(7-S-8-R-7,8-nido-C2B9H10)2]2-(R=H, Me, Ph) species. This reaction was very dependent, however, on the reaction conditions. With slight variation of the reaction conditions, splitting of the S-S bond leading to the thiolate species with retention of the closo cluster was also found. Carboranyl disulfides (1-S-2-R-1,2-closo-C2B10H10)2(R=H, Me, Ph) do not lead to thiosulfinates R-S(O)-S-R' by oxidation with H2O2 or I2 as organic disulfides do. This behaviour is attributed to the presence of the sulfur atom directly bonded to the carbon cluster that produces electronic transfer from the filled orbitals on the sulfur atom into the cage LUMO (largely located on the cage Cc-Cc bond). This causes a depletion of electron density on the sulfur, thence impairing sulfur oxidation, and facilitating S-S breaking. Crystal structures of monothioethers (2-Me-1,2-closo-C2B10H10)2S, [NMe4][(2-Me-1,2-closo-C2B10H10)S(8-Me-7,8-nido-C2B9H10)](the first example reported in the literature of a two cluster compound incorporating the closo C2B10 and the nido[C2B9]- moieties linked by a one member spacer) and disulfides (1-S-1,2-closo-C2B10H11)2, (1-S-2-Me-1,2-closo-C2B10H10)2, (1-S-2-Ph-1,2-closo-C2B10H10)2 are reported which support the behaviour of these species.

The influence of weakly coordinating anions with different shapes and substituents has been studied to get the overoxidation resistance limit of the material, ORL. The anions utilized are derivatives of [Co(C2B9H11)2]−, [B12H12]2− and [B12H11NH3]−. The following tendencies have been established (1) boron cluster monoanions are to date the anions that offer the highest stability to overoxidation of PPy doped materials (2) the ORL stability of the material can not be attributed only to the shape of the cluster (3) monoanionic clusters are far superior than dianionic to get an ORL rise (4) cluster charge density reduction results in ORL rise as has been observed in [Co(C2B9H11)2]− after incorporation of electron-withdrawing substituents with no electron back-donation (5) globular, rigid and large monoanions are less suitable for enhanced ORL values than elongated and non-rigid species (6) adequate anion's substitution produce a rise in the ORL of the material, thus polyether side-arms are beneficial with [Co(C2B9H11)2]−, whereas, T-shaped methylaryl groups are appealing in [B12H11NH3]− based materials, respectively, (7) substituents on the anions usually imply higher difficulty in the materials' growth. The high boron contents in these materials has permitted to learn on the fate of the doping anions during the overoxidation process. There is a built-up of the concentration of the doping anion in the electrolyte near surface area, whereas, a depletion is observed in the nearest inner layers.

The compounds with a single and double -CH2C6H4CH2- spacer, [CpFeC3B8H10-NH-CH2C6H4CH2-NH-C3B8H10FeCp] and [CpFeC3B8H10-N-(CH2C6H4CH2)(2)-N-C3B8H10FeCp], represent the first example of designed shaping by extremely stable cyclopentadienyl-ferratricarbollide (CpFeTCB) cages into rigid molecular constructions approaching linear arrangement. (c) 2005 Elsevier B.V. All rights reserved.

Reactions between high purity FeCl2 and the anion [nido-7-(tBuHN)-7,8,9-C3B8H10)](-) (1(-)) have been used for efficient syntheses of the twelve-vertex double-cluster metallatricarbollide complexes of the para,para (p,p) type [closo-9,9'-(RHN)(2)-commo-2,2'-Fe-II-1,7,9-(C3B8H10)-1',7',9'-(C3B8H10)] (2) (2a, R = tBu and 2b, R = H) (yields 42-45% for 2a). Compound 2b, which contains two reactive amino substituents conveniently attached to the tricarbollide subclusters in p-positions with respect to the metal center, was prepared via facile cleavage of the tBu substituent in 2a either by AlCl3 or by thermal means. The structure of 2b constitutes a good setting for the synthesis of building blocks for constructing linear metallatricarbollide rods of high stability. Two isomeric compounds of the para,meto (p,m) type 3, [closo-9,10'-(RHN)(2)-commo-2,2'-Fe-1,7,9-(C3B8H10)-1',7', 10'-(C3B8H10)] (where R = tBu 3a and/or H 3b), were isolated in smaller yields from reactions of high purity FeCl2 with 1(-) at higher temperatures. Also reported is the characterization of the m,m-type complex, [closo-10,10'-(tBuHN)(2)-commo-2,2'-Fe-II-1,7,10-(C3B8H10)-1',7',10'-(C3B8H10)] (4a), and the two zwitterionic species of the new 7-L-7,8,10-C3B8H10 type (6) [L = Me3N 6a and tBu(Me)HN 6b] isolated in moderate yields from the reaction of reagent grade FeCl2 with 1(-). The molecular structures of 2b, 3a, and 6b were determined by single-crystal X-ray diffraction studies. Multinuclear (H-1 and B-11), two-dimensional [B-11-B-11]-COSY, and H-1{B-11(selective)} magnetic resonance measurements enabled complete assignments of all resonances for all compounds and are in excellent agreement with the structures proposed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Deprotonation of the eleven-vertex tricarbaborane zwitterions 7-L-nido-7,8,9-C(3)B(8)H(10) [1: L = H(3)N (1a), tBuH(2)N (1b), Me(2)HN (1c)], followed by reactions with metal reagents [FeI(2), NiCl(2), and Ni(C(5)H(5))(2)] at higher temperatures and in situ acidification, led to the 7 --> 8 rearrangement of the N-substituted cage carbon atom to yield a series of 8-amino-substituted derivatives of nido-7,8,9-C(3)B(8)H(12). These were characterized as 8-R-nido-7,8,9-C(3)B(8)H(11) [2: R = H(2)N (2a), tBuHN (2b), Me(2)N (2c)]. A possible rearrangement mechanism for their formation has been proposed. Deprotonation of compound 2a with proton sponge [PS = 1,8-bis(dimethylaminonaphthalene)] generated the [8-tBuHN-nido-7,8,9-C(3)B(8)H(10)](-) (2b(-)) anion, which can be reprotonated to give the original compound 2b and not the tautomeric zwitterion 8-tBuH(2)N-nido-7,8,9-C(3)B(8)H(10) (3b). All compounds were characterized by high-field ((11)B and (1)H) NMR and IR spectroscopy, and mass spectrometry. The molecular structures of the neutral carbaborane 2b and its salt PSH(+)2b were determined by single-crystal X-ray diffraction analyses. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

The reaction between arachno-4,6-C2B7H13 (1) and AsCl3 or AsI3 in CH2Cl2 in the presence of PS (PS = "proton sponge", 1,8-bis(dimethylamino)naphthalene) resulted in the isolation of the parent, isomeric eleven-vertex nido diarsadicarbaboranes 7,8,9,11-As2C2B7H9 (2) and 7,9,8,10-As2C2B7H9 (3). Isolated were also halogenated derivatives of 2, 3-Cl-7,8,9,11-As2C2B7H8 (3-Cl-2) and 3-I-7,8,9,11-As2C2B7H8 (3-I-2). The presence of Et3N·BH3 in the reaction mixture increased the yield of unsubstituted compounds and suppressed the formation of halogenated species. The reaction between the isomeric carborane arachno-4,5-C2B7H13 (4) and AsCl3 in CH2Cl2 in the presence of PS gave another isomer, nido-7,8,9,10-As2C2B7H9 (5), which was accompanied by small amounts of its chloroderivative 3-Cl-7,8,9,10-As2C2B7H8 (3-Cl-5) and compound 3. The structure of the iodinated derivative 3-I-2 was determined by an X-ray diffraction analysis. Moreover, the structures of all parent compounds and chloroderivatives, inclusive of that of the still missing nido-7,10,8,9-As2C2B7H9 (6) isomer, were geometry-optimised at the DFT-B3LYP/6-31G* level.

Treatment of the [2-Cp-9-tBuNH-closo-2,1,7,9-FeC(3)B(8)H(10)] (1) ferratricarbollide (Cp = eta(5)-C(5)H(5) (-)) with Na(+) C(10)H(8) (-) in 1,2-dimethoxyethane (DME) at room temperature produced an air-sensitive transient anion with a tentatively identified nido-[tBuNH-CpFeC(3)B(8)H(10)](2-) constitution. In-situ reaction of this low-stability ion with [CpFe(CO)(2)I] or [CpFe(CO)(2)](2) generated three violet diferratricarbaboranes identified as paramagnetic subcloso complexes [4,5-Cp(2-)-4,5,1,6,7-Fe(2)C(3)B(8)H(11)] (2; yield 2 %), [4,5-Cp(2-)-4,5,1,7,12-Fe(2)C(3)B(8)H(11)] (3; yield 2 %), and [7-tBuNH-4,5-Cp(2-)-4,5,1,7,12-Fe(2)C(3)B(8)H(10)] (4; yield 14 %). These first representatives of the 13-vertex dimetallatricarbaborane family were characterized by EPR and IR spectroscopy, and mass spectrometry, and their structures were determined by X-ray diffraction analysis.

Preparative routes to 8-hydroxy-bis(1,2-dicarbollido)-3-cobalt(1-)ate (2) and 8,8′-dihydroxy-bis(1,2-dicarbollido)-3-cobalt(1-)ate (3) ions are reported by the reductive acetoxylation of the parent bis(dicarbollido)cobaltate ion (1) followed by hydrolysis of the intermediates. The essential reagent is acetic anhydride, and strong acids are required as catalysts. For the hydroxyderivative ion 2 the simultaneous presence of acetic acid brings benefit, whereas it is detrimental for the formation of the dihydroxyderivative 3. Reaction intermediate leading to the dihydroxy derivative is the already reported [8,8′-μ-CH3C(O)2(1,2-C2B9H10)2-3-Co]0 zwitterion. This compound was adequately characterised for the first time and its molecular structure as determined by X-ray diffraction analysis is presented. Both B-hydroxylated bis(dicarbollido)-ions can be alternatively obtained on the direct hydroxylation of the parent ion by hot 60–80% sulphuric acid. Optimised synthetic procedures and the main physicochemical properties (MS, TLC, HPLC, 1H- and 11B-NMR) of the species are presented. The probable reaction course of the reductive acetoxylation is discussed.

Several closo-hydroborates bearing phosphite oxide, phosphine oxide or CMPO (carbamoylmethylphosphine oxide) groups, Cs[(Ph2P(O))2N(H)B12H11] (1), K[Ph2P(O)CH2C(O)N(H)2B12H11] (2), Na[Bz2N(H)B12H10OCH2CH2OCH2CH2P(O)(OBu)2] (5), Na[Bz2N(H)B12H10O(CH2)4N(R)C(O)CH2P(O)(Ph)2] (9, R=Pri; 10, R= Octyl), Na[Bz2N(H)B12H10OCH2CH2OCH2CH2N(Bui)C(O)CH2P(O)(Ph)2]− (11) were synthesised employing novel neutral bipolar intermediates [Bz2N(H)B12H10O(CH2)4] (3) and [Bz2N(H)B12H10O(CH2CH2)2O] (4) as useful synthons. All new compounds were characterised by NMR spectroscopy and mass spectrometry techniques. Their abilities to extract selectively the radionuclides 241Am and 152Eu from nuclear waste solutions were investigated using a liquid–liquid extraction technique. Promising results were obtained with compound 10, which exhibits enhanced hydrophobicity and solubility in organic extraction solvent.

The extraction of actinides and of cesium and strontium from nitric acid or sodium nitrate solutions is done with CMPO and crown ethers, respectively. As the extraction is done from a highly concentrated nitrate solution,and nitrate being a very hydrophilic anion, the extraction of the associated cation is severely restricted. A way to get round this difficulty is adding a lipophilic anion. The cobaltabisdicarbollide anion fulfills this requirement. It can be used alone for the extraction of cesium, or in the presence of polyethylene glycol for the extraction of strontium. In synergy with CMPO, Russian scientists from Khlopin Radium Institute proposed to their US homologues a mixture of CMPO and dicarbollides to treat the huge volumes of radioactive liquid waste stored in Idaho National Engineering and Environmental Laboratory (INEEL) using UNEX (UNiversal solvent EXtraction). In spite of high performances, as more than 99% of cesium, strontium and actinides are removed, this process presents some drawbacks: The implementation of a diluent, fluoropol, containing fluorine, that is unacceptable in facilities treating liquid waste free from fluoride, and the difficulty of implementing a process containing two components in the organic phase. The aim of this project was to provide extractants that can be used in more acceptable diluents than the fluorine based fluoropol and that have only one component in the diluent. (The unequal loss of the two components in the extraction process forces an adjustment of the concentration of the extracting agents, that makes the management of the process difficult). Moreover, it was likely that linking CMPO or crown ethers to the borane clusters could lead to compounds that would improve in terms of efficiency and selectivity. Besides, the search for simpler molecules or for molecules that can be purified easily was also one of the targets of this project. New ways of synthesis, enabling direct bonding of selective groups such as phosphorous oxides, crown ether rings of different size (or CMPO) on dicarbollide moieties was an important breakthrough in the chemistry of dicarbollides. From studies carrried out in this project, it can be concluded that crown ethers bonded to dicarbollide were more soluble in NPHE than the mixture of crown ethers and dicarbollides. Adequate comparisons were achieved using more lipophilic and more selective crown ethers (benzo or cyclohexano derivatives) than the basic crown ethers, that are too soluble in water to be used in liquid liquid experiments. In spite of this, dicarbollides bearing crown ethers are more efficient than the mixture of the two separated compounds at the same concentration in NPHE. The same trend is observed with CMPO linked to dicarbollides. With these, the extraction of trivalent actinides and lanthanides is extended at higher nitric acid concentrations. As for a mixture of CMPO and dicarbollides, stripping was not possible in pure water, it was proved that the addition of DTPA and salts to the stripping solution permitted the back extraction of lanthanides.

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