Rhenium(I) Complexes with Alkynylphosphane Ligands: Structural, Photophysical, and Theoretical Studies

Abstract

AbstractA family of mono‐ and bidentate alkynylphosphanes has been used for the preparation of the rhenium(I) phenanthroline complexes [Re(phen)(CO)2(L)2]+ (L = monophosphane), [{Re(phen)(CO)3}2(L)]2+ (L = diphosphane), and [{Re(phen)(CO)2}2(L)2]2+ (L = diphosphane). The dicarbonyl compounds display intense luminescence at 298 K both in solution and in the solid state (Φem ≤ 44 %). The tricarbonyl complexes demonstrate a strong dependence of the emission efficiency on the ancillary ligand L through a pronounced π–π* contribution of the diphosphane to the electronic transitions, as confirmed by TDDFT studies. In the solid state, the complexes [Re(phen)(CO)2(L)2]+ display significant luminescence rigidochromism that is influenced by the structure of the phosphane substituents. The latter provide a means to fine‐tune the photophysical properties of this class of luminophores through variation of the stereochemical characteristics of the ligands that are not directly involved in the electronic transitions.