Hard-to-detect CoIII/CoII reduction in a hexacyanocobaltate

Hydrogen-bonded assemblies of ruthenium(ii)-biimidazole complex cations and cyanometallate anions: structures and photophysics

“…9 To confirm this suggestion we performed an exactly similar titration of 2•(PF 6 ) 2 (10 −5 M in CH 2 Cl 2 ) with [Co(CN) 6 ] 3− , which is structurally and electrostatically almost identical to [Fe(CN) 6 ] 3− , 12 but lacks an accessible Co(III)/Co(II) couple. 13 The changes in the absorption spectrum of 2•(PF 6 ) 2 were identical to those caused by addition of hexacyanoferrate, but in this case the luminescence intensity of [2] 2+ steadily increased, trebling in intensity overall, until 0.5 equivalents of [Co(CN) 6 ] 3− had been added (Fig. 4).…”

Dielectric-dependent electron transfer behaviour of cobalt hexacyanides in a solid solution of sodium chloride

“…It should be noted that this reaction can't be observed in conventional solvents even if a mercury electrode is employed to extend the potential window further into the negative. 3 To elucidate the unique redox behavior of Co(CN) 6 3À/4À in the NaCl microcrystal, theoretical calculations were performed using a density functional theory (DFT) method. 5(1b) gives the corresponding optimization structure, and also the distance between the dissociated CN : and Co(CN) 5 3À anion, which is 10.57 Å.…”

“…Unfortunately, in an aqueous solution this redox behavior hasn't been observed experimentally. 3 However, in the NaCl solid-solution microcrystal, the S 0 , D 0 and Q 1 PEC are intersectional. For the reduction of the Co(CN) 6 3À anion, the reorganization energy is about 1.54 eV.…”

“…However, despite the similar molecular structure of cobalt hexacyanide (Co(CN) 6 3– ) to Fe(CN) 6 3– , redox behavior of Co(CN) 6 3– in conventional aqueous or nonaqueous solutions has been seldom reported to date. Although theoretical calculation implies the possibility of the dielectric constant of the electrolyte solution to be decreased to 5, this indication has never been validated experimentally due to the lack of a qualified solvent 3. Since the dielectric constant of NaCl ( ε : 6.0 F m –1 ) is very close to 5 F m –1 , based on our previous research on solid solutions of NaCl microcrystals,4 we synthesize Co(CN) 6 3– doped NaCl microcrystals and observed the direct electrochemical behavior of Co(CN) 6 3–/4– in the dielectric environment of the NaCl microcrystal.…”

Wave-Function Symmetry Control of Electron-Transfer Pathways within a Charge-Transfer Chromophore

“…RuCo − bears the same total charge and an almost identical ligand field toward the ruthenium ion than RuOs − . The reduction potential of the {Co III (CN) 6 } fragment is −1.8 V versus Ag/AgCl in dimethyl sulfoxide (DMSO) (Figure S1), 9 making it a very poor electron acceptor in comparison to the −0.6 V of {Os III (CN) 6 }. 10 RuCo − presents typical MLCT absorption and emission bands in water at room temperature, at 21 140 and 15 150 cm −1 , respectively (Figure S2), and an emission quantum yield of 3.3 × 10 −3 .…”