Photolysis of FeSCN2+ complex ion in aqueous solution
Abstract
The absorption of light by the FeSCN2+ complex produces SCN radicals, [graphic omitted] The quantum yield for this process is 0.035 ± 0.002 at 25°C. In the absence of added radical scavengers the SCN radicals oxidize Fe2+:(1) Fe2++SCN →FeSCN2+; reduce FeSCN2+:(2) FeSCN2++SCN →Fe2++(SCN)2; reduce FeOH2+: (3) FeOH2++SCN →Fe2++HOSCN; and react with water by an acid-catalyzed reaction: (4) H3O++SCN →X. The ratios of the rate constants at 25°C and an ionic strength of 0.5 are k1/k2= 2.1 ± 0.2, k1/k3= 6.6 ± 0.6 and k1/k4= 610 ± 60. The SCN radicals, which can initiate polymerization of acrylonitrile, have also been produced by reaction of photo-chemically produced Cl atoms, Cl+SCN–→Cl–+SCN.