A luminescent rhenium(I) complex of 2,7-dimethyl-1,8-naphthyridine: synthesis, spectroscopy and X-ray crystal structure

Abstract

2,7-Dimethyl-1,8-naphthyridine (L1) reacts with pentacarbonylchlororhenium in toluene or chloroform to give the target complex fac-{ReCl(CO)3(L1)}. X-ray crystallographic data were obtained for fac-{ReCl(CO)3(L1)}. The structural and 1H NMR data suggest that the ligand coordinates to the rhenium in a bidentate fashion in both solid and solution states. The complex was also found to be luminescent in both solution and solid states. The fluxionality of the ligand in solution causes ligand-centred emission to be observed in solution, whereas only 3MLCT emission was observed in the solid state. Although the complex was air-stable, the lability of L1 was studied in 1H NMR experiments where CD3OD induced complete ligand dissociation over the course of 24 h, and also in reaction of fac-{ReCl(CO)3(L1)} with one equivalent of 2,2′-bipyridine in chloroform which resulted in quantitative ligand exchange.