Photochromic Rhenium-Based Molecular Rectangles: Syntheses, Structures, Photophysical Properties, and Electrochemistry.

Two novel fac-Re(CO)3-based rectangles {[(CO)3Re(μ-Cl)2Re(CO)3]2(μ-L)2} (1) and {[(CO)3Re(μ-OC4H9)2Re(CO)3]2(μ-L)2}(2) based on new photochromic dithienylethene-containing ligand 2,7-di(pyridin-4-yl)-9,10-bis(5-chloro-2-methylthien-3-yl)-phenanthrene (L) were prepared. They displayed varying photochromic properties both in solution and in the single-crystal state. Through a judicious choice of the bridging ligands along the short sides of the rectangles, the photophysical and electrochemical properties of the complexes could also be readily tuned.