Cu-I complexes with a noninnocent PNP ligand: Selective dearomatization and electrophilic addition reactivity

The neutral, T-shaped complex Cu-I((PN-PtBu)) (2), featuring a dearomatized 2,6-bis(diphosphino)pyridine (PNP)-pincer ligand, is shown to interact rapidly with electrophiles. This has enabled the synthesis of acetato complex 3. Furthermore, C-C bond formation onto the deprotonated methylene-bridgehead carbon is observed with MeOTf as the electrophile. This represents the first case of selective modification of the lutidine-based backbone of such noninnocent PNP ligands. Theoretical calculations support the formation of monomeric complex 2 and indicate the high reactivity of the methylene fragment in this Cu-I complex.