Bespoke Photoreductants: Tungsten Arylisocyanides

Modular syntheses of oligoarylisocyanide ligands that are derivatives of 2,6-diisopropylphenyl isocyanide (CNdipp) have been developed; tungsten complexes incorporating these oligoarylisocyanide ligands exhibit intense metal-to-ligand charge-transfer visible absorptions that are red-shifted and more intense than those of the parent W­(CNdipp)₆ complex. Additionally, these W­(CNAr)₆ complexes have enhanced excited-state properties, including longer lifetimes and very high quantum yields. The decay kinetics of electronically excited W­(CNAr)₆ complexes (*W­(CNAr)₆) show solvent dependences; faster decay is observed in higher dielectric solvents. *W­(CNAr)₆ lifetimes are temperature dependent, suggestive of a strong coupling nonradiative decay mechanism that promotes repopulation of the ground state. Notably, *W­(CNAr)₆ complexes are exceptionally strong reductants: [W­(CNAr)₆]⁺/*W­(CNAr)₆ potentials are more negative than −2.7 V vs [Cp₂Fe]⁺/Cp₂Fe.