A kinetic study of the photolysis of tris(2,4-pentanedionato)cobalt(III) and bis(2,4-pentanedionato)cobalt(II) in chloroform

Authors

Son L. Phan
Keith J. Cendak
Patrick E. Hoggard, Santa Clara UniversityFollow

Document Type

Article

Publication Date

2001

Publisher

Old City Publishing/De Gruyter

Abstract

Under 254nm irradiation in chloroform, Co(acac)₃ (Hacac = 2,4-pentanedione) is converted to Co(acac)₂ and then to CoCl₂. The metal complex is the primary photoactive species in the photoreduction of Co(acac)₃, but the photosubstitution of Co(acac)₂ appears to occur primarily through absorption of light by the solvent, followed by a chain reaction in which chlorine atoms displace pentanedionyl radicals. The photosubstitution rate law is complex, and the apparent quantum yield (based on total light absorbed) varies with incident light intensity and Co(acac)₂ concentration, reaching values as high as 16 under the conditions of this study. Referred only to the light absorbed by CHCL₃, the highest quantum yield measured was 150. An observed partial inverse dependence of the photosubstitution rate on the initial concentration of Co(acac)₂ is explained in terms of a mechanism in which the pentanedione product competes with Co(acac)₂ for an intermediate.

Comments

Copyright © Walter de Gruyter GmbH. Reprinted with permission.

Recommended Citation

Son L. Phan, Keith J. Cendak, and Patrick E. Hoggard, "A kinetic study of the photolysis of tris(2,4-pentanedionato)cobalt(III) and bis(2,4-pentanedionato)cobalt(II) in chloroform", Inorg. React. Mech. 3, 137-146 (2001).