Spectrophotometric Study of Cobalt (II) Chlorocomplexes in Methanol in the Visible Domain

Abstract

Cobalt(II) chlorocomplexes were studied in a polar protic solvent namely methanol at 25°C. The spectrophotometric technique in the visible region was used. The studied equilibrium is: Co2++ j Cl-CoClj↔(j-2)-. Formation of three chlorocomplexes and a structural modification (Oh → Td) were obtained from recorded spectra analysis. The stability of CoCl+was studied by the graphical method of Kruh and the overall stability constants were calculated with the SIRKO program based on the least-square method. Different models were tested and the model was retained for which the best values are: log β1 = 0.92, log β2 = 1.31 and log β3 = 1.08.

Probing Silica—Organic Hybrid Materials Using Small Probes: Simulation of Adsorption Equilibria Influenced by Cooperativity Effects

“…rather than CoCl 4 2were identified in ethanol, methanol and propan-2-ol solutions (Lechat et al 1993;Boulefred et al 2011).…”

“…The positive cooperativity effects can be attributed to the instability of the CoCl 4 2-complex that stimulates its conversion to CoCl 3 -species. Actually, chlorocomplexes CoCl + , CoCl 2 and CoCl 3 -rather than CoCl 4 2-were identified in ethanol, methanol and propan-2-ol solutions (Lechat et al 1993;Boulefred et al 2011).…”