Unique Solvatochromic Behavior of Unsymmetrical Platinum‐Dithiolene Complexes Coordinated by 4,4’‐Dinonyl‐2,2’‐Bipyridine

Abstract

AbstractUnsymmetrical metal dithiolene complexes [(nonyl‐bpy)Pt(dmit)] (1) and [(nonyl‐bpy)Pt(C8H4S8)] (2) (nonyl‐bpy=4,4‐dinonyl‐2,2‐bypiridine, dmit=4,5‐disulphanyl‐1,3‐dithiol‐2‐thionate(2−), C8H4S82−=2‐{(4,5‐ethylenedithio)‐1,3‐dithiole‐2‐ylidene}‐1,3‐dithiole‐4,5‐dithiolate(2−)) are synthesized in this study. For 1, two electronic absorption bands at approximately 466 and 584 nm in chloroform are observed and assigned to an intra‐ligand π−π* transition in the dmit moiety and an intramolecular‐mixed metal/ligand‐to‐ligand charge transfer transition (LL'CT) from its highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), respectively. Complex 2 exhibits two absorption bands at approximately 450 and 676 nm in chloroform. Both bands correspond to LL'CT from HOMO‐1 to LUMO and HOMO to LUMO. With increasing solvent polarity, the absorption bands from the HOMO‐LUMO transitions for 1 and 2 shift hypsochromically. Conversely, the 1 and 2 absorption bands exhibit red and blue shifts, respectively.