Introducing Diradicaloid Thiele's Hydrocarbon Derivatives as Ligand in Transition Metal Chemistry

Abstract

ABSTRACT Thiele's hydrocarbon (TH) derivatives, or p ‐quinodimethanes, are prototypical members of the organic diradicaloid family, predominantly explored in organic and main‐group organometallic chemistry. Herein, we introduce them to transition‐metal coordination by employing N‐doped TH derivatives as ligands. Pyridine‐ and pyrazine‐substituted p ‐quinodimethane ligands were synthesized, enabling the formation of mono‐ and dinuclear rhodium and cyclometalated iridium complexes ( Py∙Rh , Pz∙Rh , Py∙Ir , and Pz∙Ir ). We show the strong effects that simple metalation, and more importantly, orthometalation can have on the photophysical and electrochemical properties, as well as on singlet‐triplet gaps of these diradicaloids. Additionally, the metalated mixed‐valent forms are strongly electrochromic NIR absorbing dyes. Spectro‐electrochemical studies reveal distinct electronic interactions between the diradicaloid backbone and the metal centers, highlighting the potential of N‐doped TH derivatives as versatile redox‐active ligands in transition‐metal chemistry.