Near-UV photolysis of μ-dibromotetrabromo- dipalladate(II) in chloroform

Abstract

Broadband ( 4 320 nm) irradiation of (Bu 4 N) 2 Pd 2 Br 6 in chloroform causes the conversion of Pd 2 Br 2À 6 to Pd 2 Cl 2À 6 . During the conversion, chloroform is decomposed photocatalytically at a rate that accelerates then decelerates as coordinated bromines are replaced by chlorines. The primary bromine-containing product is CCl 3 Br. The observations are consistent with a mechanism in which Pd 2 Br 2À 6 and the intermediate Pd 2 Br 6Àn Cl 2À n complexes undergo homolytic photodissociation of a bromine or chlorine atom, which terminates with a trichloromethyl radical or abstracts a hydrogen from chloroform, respectively.