Formation and isomerisation of theO-sulphito complex of 1,4,7,10,13-penta-azacyclohexadecanecobalt(III)

Summary

Dissolved SO₂ reacts rapidly with [Co([16]aneN₅)OH]²⁺ to give [Co([16]aneN₅OSO₂]⁺([16]aneN₅=1,4,7,10, 13-penta-azacyclohexadecane), which on immediate acidification loses SO₂ to give [Co([16]aneN₅)OH₂]³⁺. The O-bonded sulphito complex (λ_max 526 nm) undergoes a slow linkage isomerisation to give the S-bonded species [Co([16]aneN₅)SO₃]⁺ (λ_max 466 nm), rather than an internal redox reaction. The S-bonded complex has been isolated and characterised as the perchlorate salt [Co([16]aneN₅) (SO₃H)](ClO₄)₂.