Third-Generation W(CNAr) Photoreductants (CNAr = Fused-Ring and Alkynyl-Bridged Arylisocyanides).

Homoleptic tungsten(0) arylisocyanides possess photophysical and photochemical properties that rival those of archetypal ruthenium(II) and iridium(III) polypyridine complexes. Previous studies established that extending the π-system of 2,6-diisopropylphenylisocyanide (CNDipp) by coupling aryl substituents to the isocyanide functionality results in W(CNDippAr) oligoarylisocyanide complexes with greatly enhanced metal-to-ligand charge transfer (MLCT) excited-state properties relative to those of W(CNDipp). Extending electronic modifications to delineate additional design principles for this class of photosensitizers, herein we report a series of W(CNAr) compounds with naphthalene-based fused-ring (CN-1-(2-Pr)-Naph) and CNDipp-based alkynyl-bridged (CNDippAr) arylisocyanide ligands. Systematic variation of the secondary aromatic system in the CNDippAr platform provides a straightforward method to modulate the photophysical properties of W(CNDippAr) complexes, allowing access to an extended range of absorption/luminescence profiles and highly reducing excited states, while maintaining the high molar absorptivity MLCT absorption bands, high photoluminescence quantum yields, and long excited-state lifetimes of previous W(CNAr) complexes. Notably, W(CN-1-(2-Pr)-Naph) exhibits the longest excited-state lifetime of all W(CNAr) complexes explored thus far, highlighting the potential benefits of utilizing fused-ring arylisocyanide ligands in the construction of tungsten(0) photoreductants.