Photolysis primary products of alkylcobaloximes controlled by the cobalt-carbon bond strength

• Type: Article in International Scientific Journal
• Date: 1999

Authors

Rangel, M (Author) ICBAS; Arcos, T (Author) Other; de Castro, B (Author) FCUP

Journal

Title: Organometallics

Vol. 18

Pages: 3451-3456

ISSN: 0276-7333

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 16 Citations

Scopus - 19 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-001-3MR

DOI: 10.1021/om990078s

Abstract (EN): Anaerobic photolysis of several methyl- and benzylpyridinecobaloximes was studied by electron spin resonance spectroscopy in aprotic solvents, at three temperatures of irradiation and with use of visible and UV light sources, Homolysis of the cobalt-carbon bond is photochemically induced when irradiation with visible light is pet-formed at room temperature, giving risc to Co(II) five-coordinate species and organic radicals. Irradiation with visible light of fluid (250 K) or frozen (77 K) solutions does not cause homolysis of the cobalt-carbon bond, in contrast with the results reported for other alkylpyridinecobaloximes. Homolysis of the cobalt-carbon bond is achieved at all temperatures if a UV light source is used, and the results are rationalized in terms of the values of the cobalt-carbon bond dissociation energies. The results obtained at 250 K for a series of isotopically substituted methylpyridinecobaloximes allowed the definitive assignment of the spectrum obtained upon photolysis at 250 K to a cobalt(III) nitroxide radical and not to a Co(II) center as has been proposed earlier.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6