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![A fragment of crystal structure of (BMDT-TTF) 4 [8,8 0-Br 2-3,3 0-Co(1,2-C 2 B 9 H 10 ) 2 ] (3).](profile/Andrei-Kravchenko/publication/243330256/figure/fig4/AS:596067229908993@1519124910681/A-fragment-of-crystal-structure-of-BMDT-TTF-4-8-8-0-Br-2-3-3-0-Co1-2-C-2-B-9-H-10-2.png)
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New molecular conductors on the base of 8,8′-dibromo cobalt bis(dicarbollide) anion, (BEDT-TTF)2[8,8′-Br2-3,3′-Co(1,2-C2B9H10)2] (1), (BEDT-TTF)[8,8′-Br2-3,3′-Co(1,2-C2B9H10)2] (2) and (BMDT-TTF)4[8,8′-Br2-3,3′-Co(1,2-C2B9H10)2] (3) were synthesized and their crystal structures and electrical conductivities were determined. All the radical cation s...
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Context 1
... structure of 3 is formed by four BMDT-TTF radical cations (AeD) on general positions of a unit cell and two [8,8 0 -Br 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] À anions (A and B) in special centrosymmetric positions (Fig. S3). Compound 3 has a lay- ered structure with cationic and anionic layers alternating along the c axis (Fig. 4). The BMDT-TTF stacks in the con- ducting layers are not uniform. One type of stacks is formed by the A and B donor molecules alternating in the eAeAe BeBe order and the other one is formed by the C and D donor molecules alternating in the eCeCeDeDe order (Fig. S4). Dihedral angles formed by the donor molecules from different stacks ...
Context 2
... a lay- ered structure with cationic and anionic layers alternating along the c axis (Fig. 4). The BMDT-TTF stacks in the con- ducting layers are not uniform. One type of stacks is formed by the A and B donor molecules alternating in the eAeAe BeBe order and the other one is formed by the C and D donor molecules alternating in the eCeCeDeDe order (Fig. S4). Dihedral angles formed by the donor molecules from different stacks were found to be AeC 56.8 , AeD 51.7 , BeC 58.7 , and BeD 59.0 . Based on these data the BMDT-TTF cation packing in the conducting layer was attributed to the a-type [17]. The donor molecules of different types in stacks are near parallel (dihedral angles are 1.8e1.9 ...
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New molecular conductors on the base of 8,8’-dibromo cobalt bis(dicarbollide) anion, (BEDT-TTF)2[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (1), and (BEDT-TTF)[8,8’-Br2-3,3’-Co(1,2-C2B9H10)2] (2) were synthesized and their crystal structures and electrical conductivities were determined. Both radical cation salts prepared were found to be semiconductors. The...
Citations
... It should be noted that while the synthesis of the iodo derivative of nido-carborane was first described more than 50 years ago, 18 its hydroxy derivatives were not known until recently. The synthesis of the symmetrically substituted 10-hydroxy derivative [10-HO-7,8-C 2 B 9 H 11 ] − has been described very recently, 19 while the only available information on the asymmetrically substituted 9-hydroxy derivative [9-HO-7,8-C 2 B 9 H 11 ] − was its stick diagram of 11 B NMR spectrum in the review on NMR spectroscopy of carboranes by Heřmanek. 20 However, it was this information, combined with mass spectrometry data, that allowed us to quickly identify the resulting product. ...
... Thereafter, volatiles were removed under reduced pressure, and solution of KI (0.84 g, 5.1 mmol) in 10 ml of water was added to the residue, the reaction mixture was stirred at room temperature for 5 min. Then, the mixture was filtered, and the solid was washed with water and toluene and dried on air to give a white solid (Me 3 NH)[1] (1.47 g, yield 92%). 11 ...
... Under argon atmosphere N-bromosuccinimide (200 mg, 1.1 mmol) was added to (Me 3 NH)[2] (210 mg, 1.0 mmol) in 15 ml of tetrahydrofuran and the reaction mixture was heated under reflux for 15 min. Thereafter, the reaction mixture was cooled to ambient temperature, volatiles were removed under reduced pressure and the crude product was purified by column chromatography on silica using a mixture of dichloromethane and acetone (3 : 2, v/v) as eluent to give a pale-yellow solid (Me 3 NH) [4] (200 mg, yield 69%). 11 Under argon atmosphere potassium tert-butoxide (168 mg, 1.5 mmol) was added to (Me 3 NH)[1] (100 mg, 0.3 mmol) in 25 ml of pyridine and heated under reflux for 30 h. Thereafter, the reaction mixture was allowed to cool to ambient temperature, volatiles were removed under reduced pressure, and to the residue dichloromethane (10 ml) and water (10 ml) were added. ...
An unusual reactivity of 9-iodo-nido-carborane [9-I-7,8-C2B9H11]- towards nucleophiles under strong basic conditions was revealed. The nucleophilic substitution of iodine with O- and N-nucleophiles results in [9-RO-7,8-C2B9H11]- (R = H, CH2CH2OMe) and [9-L-7,8-C2B9H11] (L = Py, NEt3, Me2NCH2CH2NMe2), respectively. Reaction of [9-I-7,8-C2B9H11]- with CoCl2 in 1,2-dimethoxyethane in the presence of t-BuOK, depending on the order of addition of the reagents, leads either to a diastereomeric mixture of diiodo derivatives cobalt bis(dicarbollide) rac-[4,4’-I2-3,3’-Co(1,2-C2B9H10)2]- and meso-[4,7’-I2-3,3’-Co(1,2-C2B9H10)2]- or to the corresponding mixture of 2-methoxyethoxy derivatives rac-[4,4’-(MeOCH2CH2O)2-3,3’-Co(1,2-C2B9H10)2]- and meso-[4,7’-(MeOCH2CH2O)2-3,3’-Co(1,2-C2B9H10)2]-. In the presence of accidental admixture of sodium thiosulfate, the reactions of 9-iodo-nido-carborane and 9-(2’-methoxyethoxy)-nido-carborane with CoCl2 in 1,2-dimethoxyethane were found to produce additionally unprecedented tricobalt tris(dicarbollide) cluster Na[4,4’,4’’-(MeOCH2CH2O)3-3,3’,3’’-Co3(μ3-O)(μ3-S)(1,2-C2B9H10)3], the central fragment of which is a trigonal bipyramid with apical oxygen and sulfur atoms, and the base is formed by the Co3 triangle flanked by three dicarbollide ligands. In addition, the 2-methoxyethoxy substituents of the dicarbollide ligands chelate the sodium cation in such a way that they form a helix whose rotation direction depends on the enantiomer of the parent ligand. Thus, in this case, induction of the helical chirality of the complex occurs due to the point chirality of the initial inorganic ligand. It is worth noting that in the case of symmetrically substituted 2-methoxyethoxy derivative of nido-carborane [10-MeOCH2CH2O-7,8-C2B9H11]- only formation of the corresponding cobalt bis(dicarbollide) complex [8,8’-(MeOCH2CH2O)2-3,3’-Co(1,2-C2B9H10)2]- was observed.
... 13,31 In addition to the stabilization of certain rotamers of bis(dicarbollide) complexes due to intramolecular hydrogen bonding, exo-polyhedral substituents also can participate in intermolecular bonding with other anions and the tetrathiafulvalene radicalcations. [32][33][34][35][36] This prompted us to synthesize similar compounds with methylthio derivatives of cobalt bis(dicarbollide). It should be noted that our initial attempt to obtain the BEDT-TTF salt with the with [8,8 0 -(MeS) 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] À anion was unsuccessful due to the ease of oxidation of sulfur atoms, 24 which, probably, can be explained by the strong electrondonating effect of the cobaltacarborane cage bound via boron atom. ...
The C-methylthio derivatives of cobalt bis(dicarbollide) were synthesized by reaction of anhydrous CoCl2 with nido-carborane [7-MeS-7,8-C2B9H11]⁻ and isolated as a mixture of rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]⁻ and meso-[1,2′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]⁻ isomers. The structures of both isomers were studied using DFT quantum chemical calculations. The most preferable geometry of rotamers and the stabilization energy of C-methylthio derivatives of cobalt bis(dicarbolide) were calculated. The (BEDT-TTF)[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2] salt was prepared and its structure was determined by single crystal X-ray diffraction. The cisoid conformation of the rac-[1,1′-(MeS)2-3,3′-Co(1,2-C2B9H10)2]⁻ anion is stabilized by short intramolecular CH⋯S hydrogen and BH⋯S chalcogen bonds between the dicarbollide ligands, that is in good agreement with the data of quantum chemical calculations.
... The simplest type of such interactions is intramolecular CH…Hal hydrogen bonding between slightly acidic metallacarborane CH groups in one ligand and halogen substituents in other ligand. The CH…Hal hydrogen bonds were found to be responsible for stabilization of the transoid conformation in the solid-state structures of the 8,8′-dihalogen derivatives of transition metal bis(dicarbollides) [8,8′-X2-3,3′-M(1,2-C2B9H10)2] − (M = Co, X = Cl [66][67][68], Br [69], I [70,71]; M = Fe, X = Cl [66,72], Br [73], I [73]) ( Figure 25). According to Pauling's principle, the strength of a hydrogen bond should increase with the increase of the electronegativity of the acceptor atom [74], however in this case van der Waals radius of a halogen seems to be more important than its electronegatively. ...
Design of rotatory molecular switches based on extremely stable sandwich organometallic complexes ferrocene and bis(dicarbollide) complexes of transition metals is reviewed. The “on”–“off” switching in these systems can be controlled by various external stimuli such as change of the solution pH, interactions with coordinating species or redox reactions involving the central atom or substituents in the ligands.
... The effective stabilization of the transoid conformation through the formation of intramolecular C carb H···XB (X = Cl, Br, I) hydrogen bonds between the ligands can be achieved by the introduction of halogen atoms at the 8-and 8′-positions of the metallacarborane skeleton. [12][13][14] We suggest that bistability of the cobalt bis(dicarbollide) system can be achieved through the introduction of substituents that can form rather weak intramolecular hydrogen bonds between the dicarbollide ligands and stronger dative bonds with external transition metals. In this case, the external metal complexation will stabilize the cisoid conformation, whereas the stabilization of the transoid or gauche conformations (depending on the substituent position) will be caused by intramolecular hydrogen bonding between the dicarbollide ligands. ...
... Ohm À1 cm À1 (Fig. 6) what is comparable with the values of salts (5) and ( [28]. Crystal structure of (2) was formed by the ET radical-cation and (Fig. 7). ...
... Electroconductivity measurements on a polycrystalline sample of (2) revealed semiconducting properties of the salt, conductivity value at room temperature s 293~1 $10 À6 Ohm À1 cm À1 , what is three orders lower than the electroconductivity of the isostructural cobalt bromine substituted analog, (ЕТ)[8,8 0 -Br 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] (8) (s 293~1 .5$10 À3 Ohm À1 cm À1 ) [28]. This result can be explained by the less bulky bromine substituent's effect on the packing density of radical action layer in comparison to the impact of the larger iodine atom, loosening the conductive layer in (2). ...
New radical-cation salts based on bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) were synthesized: (ЕТ)2[8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2] (1) and (ЕТ)[8,8′-I2-3,3′-Fe(1,2-C2B9H10)2] (2). Their crystal structures were studied by X-ray analysis, electroconducting and magnetic properties were measured in a wide temperature range. Salts (1) and (2) appeared to be the first radical-cation salts with [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]⁻ and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]⁻ anions, respectively. In the literature [8,8′-I2-3,3′-Fe(1,2-C2B9H10)2]⁻ and [8,8′-Br2-3,3′-Fe(1,2-C2B9H10)2]⁻ anions are presented for the first time. Salts (1) and (2) were found to be paramagnetic. Their room temperature conductivities were 2 and 1·10⁻⁶ Ohm⁻¹cm⁻¹, respectively.
... Спектры ЯМР 11 Рентгеноструктурное исследование соли (BEDT TTF) 2 сти для соли 1 проводили при температурах от 2 до 300 К: в постоянном поле HDC = 100 Э и в переменном поле амп литудой hAC = 2 Э и частотой f = 100 Гц; диамагнитный вклад в восприимчивость определяли по аддитивной схеме Паскаля с инкрементами 21 . ...
A new radical cation salt of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iron(III) bis(1,2-dicarbollide) 8,8´-dichloro derivatives, that is (BEDT-TTF)2[8,8´-Cl2-3,3´-Fe-(1,2-C2B9H10)2], was synthesized. Its electroconducting and magnetic characteristics were studied, molecular and crystal structures were determined. The electroconductivity of crystals at room temperature was σ293 ~5 Ω–1 cm–1, which is close to the corresponding value for the salt of cobalt bis(1,2-dicarbollide) dichloro derivative and is considerably higher than the electroconductivity of a similar salt of unsubstituted iron bis(1,2-dicarbollide). The measurements of magnetic susceptibility at 2—300 K showed that this salt is paramagnetic.
... Recently we described synthesis and study of series of TTF-based radical cation salts containing cobalt bis(dicarbollide) anion [3,3'-Co(1,2-C 2 B 9 H 11 ) 2 ]and its derivatives as counterions [13][14][15][16][17][18][19][20]. Here we report synthesis, structure and electric conductivity of halogen and phenyl derivatives of cobalt bis(dicarbollide) anion, (BEDT-TTF) [ 2 ] were prepared as previously described [21,22]. ...
... Earlier we found that the introduction of halogen atoms into 8,8'-positions of the cobalt bis(dicarbollide) anion leads to stabilization of the transoid conformation of the anion due to the formation of intramolecular C-H…X-B (X = Cl, Br, I) hydrogen bonds as well as assists with formation of ordered counterion layers due to intermolecular C-H…X-B hydrogen bonds [15][16][17]. ...
Continuing our recent works towards molecular conductors containing metallacarborane anions with the aim to study the effect of the anion structure on radical cation packing in these compounds we synthesized new radical cation salts based on organic -donors, BEDT-TTF and TMTTF, with halogen and phenyl derivatives of cobalt bis(dicarbollide) anion: (BEDT-TTF)[8-I-8'-Ph-3,3'-Co(1,2-C 2 B 9 H 10) 2 ]0.5(C 2 H 3 Cl 3) (1) and (TMTTF)[8,8'-Cl 2-3,3'-Co(1,2-C 2 B 9 H 10) 2 ] 2 (2). Their crystal structures were determined by X-ray single crystal analysis, electric conductivities were measured using standard dc-four-probe technique. Both compounds possess non-layered architectures and proved to be semiconductors at room temperature. Low values of electric conductivity well agree with the absence of layered or stacked crystal structures, typical for organic conductors. Unlike known BEDT-TTF salts, the [8,8'-Cl 2-3,3'-Co (1,2-C 2 B 9 H 10) 2 ]-anion in 2 adopts gauche conformation, that can be explained by the large gain in the crystal packing energy on the transoid-gauche transformation in comparison with the energy of intramolecular hydrogen bonds in the transoid conformation. We believe that this fact might be the reason for the formation of mixed donor and anion packing in the crystal structures of the salts.
... This marriage opened new areas for experimental and theoretical explorations that continue in full force to the present day [7]. Nowadays metallacarboranes find numerous applications in catalysis [8], medicine [9,10], design of new materials [11,12], extraction of radionuclides from nuclear waste [13] and many others [14]. ...
The review covers synthesis and chemistry of transition metal complexes with charge-compensating dicarbollide ligands including combination of the charge-compensated carboranes and metal complexes and chemical modification of preliminary synthesized metallacarboranes.
... Recently we studied the effect of iodo- [9][10][11], bromo- [12] and hydroxy- [13] substituents in cobalt bis(1,2-dicarbollide) complexes on crystal packing and physical properties of their salts with TTFbased radical cations. In this paper, we report the crystal structures and electrical conductivities of tetrathiafulvalenium salts of dichloro and mixed bromo-chloro and bromo-hydroxy derivatives of cobalt bis(dicarbollide) anion. ...
New radical cation salts (BEDT-TTF)[8,8',(7)-Cl2(Cl0.09)-3,3'-Co(1,2- C2B9H9.91)(1',2'-C2B9H10)] (1), (BEDT-TTF)[8,8'-Br0.75Cl1.25-3,3'-Co(1,2-C2B9H10)2] (2), and (BMDT-TTF)4[8,8'-Br1.16(OH)0.72-3,3'-Co(1,2-C2B9H10.06)2] (3) were synthesized, and their crystal structures and electrical conductivities were determined. All the radical cation salts are semiconductors. Compounds 1 and 2 were found to be isostructural, however their electrical conductivities strongly differ (σ293 = 2 Ω-1cm-1 and 10-5 Ω-1cm-1, respectively).
... 20,21 Earlier we found that the introduction of bromine or iodine atoms in the open pentagonal face of the dicarbollide ligand (positions 8 and 8 0 of the cobaltacarborane skeleton) favors the formation of intermolecular hydrogen bonds participating in the formation of the crystal supramolecular architecture. 15,16 At the same time, the halogen introduction results in stabilization of the transoid conformation due to the formation of intramolecular CH 3 3 3 XB (X = Br, I) hydrogen bonds, locking ligand rotation. The aim of this work was to study the effect of the hydroxy group as a classical hydrogen-bond-forming substituent on the rotational mobility of the dicarbollide ligands in a cobalt bis(dicarbollide) anion and the formation of the crystal structures of tetrathiafulvalenium salts of the [8-HO-3,3 0 -Co(1,2-C 2 B 9 H 10 )-(1 0 ,2 0 -C 2 B 9 H 11 )]anion. ...
... In all of these compounds, the anions adopt a transoid conformation, which is stabilized by the formation of CH 3 3 3 XB intramolecular hydrogen bonds. 15,16 As expected, a change of halogens for smaller hydroxy groups could prevent the formation of strong intramolecular hydrogen bonds, keeping the possibility of the formation of intermolecular bonds. Therefore, a study of the conformation mobility of the dicarbollide ligands in the hydroxy derivative was of a special interest. ...
Molecular conductors based on the 8-hydroxy cobalt bis(dicarbollide) anion, (TMTTF)[8-HO-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))] (1), (BMDT-TTF)[8-HO-3,3'-Co(1,2-C(2)B(9)H(10)) (1',2'-C(2)B(9)H(11))] (2), and (BEDT-TTF)[8-HO-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))] (3), were synthesized, and their crystal structures and electrical conductivities were determined. Compounds 2 and 3 are isostructural to the corresponding radical-cation salts of the parent cobalt bis(dicarbollide). All of the radical-cation salts prepared were found to be semiconductors. The relative stability of the rotation conformers of the [8-HO-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))](-) anion was estimated using DFT/BP86 quantum chemical calculations.
