Crystal structures of benzoxazolyl-copper(iII,II,I) complexes and investigation of Cu(II)-mediated aryl carbon-hydrogen bromination.

Copper complexes have been frequently involved in many Cu-mediated carbon-hydrogen halogenation reactions. We fortunately obtained three different valence benzoxazolyl-copper complexes, along with aryl carbon-hydrogen bromination, in the self-assembly reaction of ligands with CuBr2. The complexes have been successfully characterized by X-ray single crystal diffraction analyses. The results indicate that 1 consists of di-brominated p-benzoxazolylphenylamine (L) and an unusual high valence copper(III) complex with tetrahedral geometry, 2 is the first polymeric catenulate di-brominated benzoxazolyl-copper(I) complex and 3 is the mono-brominated benzoxazolyl-copper(II) complex. We speculate proposed mechanisms for the formation of these complexes and the bromination of aryl carbon-hydrogen based on these crystal structures.