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The photochemical reactions of Co_2(CO)_6(PBu_3)_2 with various quinones and phenothia-zine were studied by ESR.The results indicate that the photolysis of Co_2(CO)_6(PBu_3)_2 in the pre-sence of o-quinones led to the observation of an ESR spectrum,showing a broad 8 or 12 groups ofhyperfine lines due to interaction with cobalt (Co,I=7/2).The results show that with o-quinonesthe cobalt radical adducts are formed via metal chelation to the carbonyl oxygens.However,whenCo_2(CO)_6(PBu_3)_2 was irradiated in the presence of p-quinones,only the para-semiquinone radicalswere observed.The photolysis of Co_2(CO)_6(PBu_3)_2 with phenothiazine in toluene yields pheno-thiazine radical.The sixteen and eighteen electrons rule have been used to account for these ob-servations.
The photochemical reactions of Co_2 (CO) _6 (PBu_3) _2 with various quinones and phenothia-zine were studied by ESR. The results indicate that the photolysis of Co_2 (CO) _6 (PBu_3) _2 in the pre-sence of o-quinones led to the observation of an ESR spectrum, showing a broad 8 or 12 groups of hyperfine lines due to interaction with cobalt (Co, I = 7/2). The results show that with o-quinonesthe cobalt radical adducts are formed via metal chelation to the carbonyl oxygens. However, whenCo_2 (CO) _6 (PBu_3) _2 was irradiated in the presence of p-quinones, only the para-semiquinone radicalswere observed.The photolysis of Co_2 (CO) _6 (PBu_3) _2 with phenothiazine in toluene yields pheno-thiazine radical.The sixteen and eighteen electrons rule have been used to account for these ob-servations.