Synthesis and characterization of polypiridine-based rhenium(I) complexes with pyrazino[2,3-f][1,10]phenanthroline
- A series of tricarbonyl rhenium(l) complexes of the type Jac-[Re-I(CO)(3)(ppl)(L)](0/+), where ppl is pyrazino[2,3-f] [1,10]phenanthroline, and where L is Cl-, TfO-, 4-(tert-butyl)pyridine ('Bu-py), 4-methoxypyridine (MeO-py), 4,4'-bipyridyl (bpy), or 10-(picolin-4-yl)phenothiazine (pptz), were synthesized and fully characterized. In all complexes, an increment in the electron-acceptor properties of ppl compared to the free ligand was observed. This effect was more significant for pyridine-type ligands, especially for pptz, compared to Cl- or TfO-. The properties of fac-[Re(CO)(3)(PPl)(pptz)]PF6 were compared with those of the analogous compound fac-[Re(CO)(3)(dppz)(pptz)]PF6, where dppz is dipyrido(3,2-a: 2',3'-c)phenazine, the goal being to generate long-lived excited charge-transfer (CT) states. In this respect, fac-[Re(CO)(3)(PPl)(pptz)]PF6 seems to be a promising candidate.