N. Shinohara et al., PHOTOCHEMISTRY OF MU-AMIDO-MU-HYPEROXO-DICOBALT(III) COMPLEXES WITH AMMINE AND POLYAMINE LIGANDS IN AQUEOUS-SOLUTIONS - EFFECTS OF LIGAND AND PH, Bulletin of the Chemical Society of Japan, 68(1), 1995, pp. 178-182
Photolyses of mu-amido-mu-hyperoxo-dicobalt(III) complexes, [LCo(NH2,O
-2(-))CoL](4+) (L=4NH(3) (1), en+ 2NH(3) (2), 2en (3), tren (4)), (tre
n: 2,2',2''-triaminotriethylamine, en: ethylenediamine) were investiga
ted. The photolysis of complex 4 in a neutral aqueous solution produce
d a mu-hydroxo-mu-peroxo-dicobalt(III) complex, [(tren)Co(OH,O-2(2-))C
o(tren)](3+), together with a mononuclear cobalt(III) complex, [Co(NH3
)(tren)-(H2O)](3+). A mononuclear complex and Co2+ were produced in th
e photolyses of mu-hyperoxo complexes 1 and 2 containing NH3 ligand in
neutral aqueous solutions. In acidic media, only mononuclear complex
and Co2+ were produced in the photolysis of all mu-hyperoxo complexes
examined. Quantum yields of the complexes with NH3 increased with incr
easing the number of coordinated NH3 (phi=0.25, 0.11, 0.023, and 0.028
for complexes 1, 2, 3, and 4, respectively, at 365 nm irradiation in
neutral region). The quantum yields obtained in acidic solutions were
similar in magnitude to those obtained in neutral solutions.