Thermal and Photochemical Ring-Bromination in Naphthyl-, Naphthdiyl-, and Dicarboximideperyl-Platinum Complexes

Brominated polycyclic aromatic compounds are important synthons, but their synthesis can be difficult. Herein, we report that Pt(IV) centers σ-bonded to naphthalene and a dicarboximideperylene activate the ring systems to selective thermal and photochemical bromination. Thus, trans-Pt(PEt3)2(Br)3(4-bromo-1-naphthyl) and Br2 give trans-Pt(PEt3)2(Br)3(7,4-dibromo-1-naphthyl). Introduction of a second Pt(IV) center is achieved by double oxidative addition of 1,4-dibromonaphthalene to 2Pt(PEt3)4. Bromination of [trans-Pt(PEt3)2Br]2(1,4-naphthdiyl) yields [trans-Pt(PEt3)2(Br)3]2(1,4-naphthdiyl), which further brominates on the ring to give [trans-Pt(PEt3)2(Br)3]2(6,7-dibromo-1,4-naphthdiyl). Photoreduction of the Pt(IV) centers with 1-hexene gives first mixed-valent [trans-Pt(PEt3)2(Br)3][trans-Pt(PEt3)2(Br)](6,7-dibromo-1,4-naphthdiyl) and then [trans-Pt(PEt3)2Br]2(6,7-dibromo-1,4-naphthdiyl). Photoreduction of trans-Pt(PEt3)2(Br)3(PMI) (PMI = N-(2,5-di-tert-butylphenyl)perylen-3-yl-9,10-dicarboximide) withou...