1.3 V Inorganic Sequential Redox Chain with an All-Anionic Couple 1–/2– in a Single Framework

Abstract

The relatively low symmetry of [3,3′-Co(1,2-C 2 B 9 H 11 ) 2 ] − ([ 1 ] − ), along with the high number of available substitution sites, 18 on the boron atoms and 4 on the carbon atoms, allows a fairly regioselective and stepwise chlorination of the platform and therefore a very controlled tuning of the electrochemical potential tuning. This is not so easily found in other systems, e.g., ferrocene. In this work, we show how a single platform with boron and carbon in the ligand, and only cobalt can produce a tuning of potentials in a stepwise manner in the 1.3 V range. The platform used is made of two icosahedra sharing one vertex. The E 1/2 tuning has been achieved from [ 1 ] − by sequential chlorination, which has given potentials whose values increase sequentially and linearly with the number of chloro groups in the platform. [ Cl 8 -1 ] − , [ Cl 10 -1 ] − , and [ Cl 12 -1 ] − have been obtained, which are added to the existing [ Cl-1 ] − , [ Cl 2 -1 ] − , [ Cl 4 -1 ] − , and [ Cl 6 -1 ] − described earlier to give the 1.3 V range. It is envisaged to extend this range also sequentially by changing the metal from cobalt to iron. The last successful synthesis of the highest chlorinated derivatives of cobaltabis(dicarbollide) dates back to 1982, and since then, no more advances have occurred toward more substituted metallacarborane chlorinated compounds. [ Cl 8 -1 ] − , [ Cl 10 -1 ] − , and [ Cl 12 -1 ] − are made with an easy and fast method. The key point of the reaction is the use of the protonated form of [Co(C 2 B 9 H 11 ) 2 ] − , as a starting material, and the use of sulfuryl chloride, a less hazardous and easier to use chlorinating agent. In addition, we present a complete, spectroscopic, crystallographic, and electrochemical characterization, together with a study of the influence of the chlorination position in the electrochemical properties.

A Simple Way to Obtain a Decachloro Derivative of Cobalt Bis(dicarbollide)

“…Similarly, 13 C NMR spectrum consists of two signals from CH groups at 49.0 and 46.9 ppm (see Figure S1 and Figure S2, respectively, in the Supplementary Materials). These spectral data indicate that the complex is a gauche rotamer, which can also be confirmed by X-ray structural data obtained for NMe 4 [3,3 -Co(4,7,8,9,12-Cl 5 -1,2-C 2 B 9 H 6 ) 2 ] earlier [27].…”

“…It has recently been demonstrated that the reaction of the cobalt bis(dicarbollide) anion with sulfuryl chloride in the presence of AlCl 3 in an Ace pressure tube, depending on the amount of reagents and reaction time, results in the formation of chlorinated derivatives with a higher degree of substitution, such as Cl-8, Cl-10, and Cl-12 derivatives [27]. This work is the first example of the synthesis of pure chloro derivatives with a high degree of halogenation, in contrast to the previously described preparation of inseparable mixtures of chlorinated derivatives of cobalt bis(dicarbollide) (up to Cl-9) [33].…”

“…For many years, the hexachloro derivative was known as the derivative with the highest substitution degree; however, very recently it was reported that the reaction of cobalt bis(dicarbollide) with sulfuryl chloride in the presence of AlCl 3 , depending on the amount of reagents and reaction time, results in the formation of octa-, deca-, and dodecachloro derivatives of cobalt bis(dicarbollide) [27]. In this contribution, we describe a simple and convenient method for obtaining decachloro cobalt bis(dicarbollide) Cs[3,3 -Co(4,7,8,9,12-Cl 5 -1,2-C 2 B 9 H 6 ) 2 ] without using toxic, corrosive, and lachrymatory sulfuryl chloride.…”

Nickelacarborane-Supported Bis-N-heterocyclic Carbenes

“…The formation of 4 not only suggests that NHC 3 could serve as a novel Janus-type bis-carbene ligand but also indicates that it has the potential to be used in constructing metallocycles in self-assembly chemistry or in heterobimetallic complexes catalyzed tandem processes . Previous studies have successfully demonstrated the ability to systematically adjust the redox properties of nickelacarboranes through chemical functionalization . Hence, the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) of compound 4a were conducted in 0.1 M Bu 4 NPF 6 dichloromethane (Figures and S41).…”

Charge-compensatednido-carborane derivatives in the synthesis of iron(ii) bis(dicarbollide) complexes

“…Similarly, substitution of hydrogen atoms in cobalt bis(dicarbollide) with methyl groups results in a shift of the Co 3+ /Co 2+ redox potential values to more negative potentials, indicating an increase of the donating character of the dicarbollide anion, 23 while the substitution with chloride or iodine leads to a noticeable shift of the Co 3+ /Co 2+ redox potential towards less negative values which increases as the number of electron-withdrawing substituents increases. 23,24…”