Lead(II) Imides: A New Family of Photoluminescent Heavy Main-Group Compounds With Oxidatively Induced Nitrene Reactivity.

A new family of low-valent lead(II) imide dimers, [R1,R2ArNPb]2 (1-4) (R1,R2ArNH2 = 2,6-((4-R1-C6H4)2CH)2-4-R2-C6H2NH2), features a rhombic Pb2N2 core stabilized by short intramolecular Pb⋯Pb contacts and bulky ligands. These complexes exhibit red/near-infrared solid-state phosphorescence (λmax ≈ 730-790 nm) at 77 K, characterized by sub-microsecond lifetimes and significant ligand-to-metal charge-transfer (LMCT) character. Computational analysis reveals that standard density functional theory (DFT) struggles to capture the energetics of this heavy-element emission, establishing these systems as critical benchmarks for validating relativistic quantum-chemical workflows that account for dynamic correlation and spin-orbit coupling. Beyond photophysics, the Pb(II) imides display distinctive nitrene-transfer and oxidative reactivity; reactions with ortho-benzoquinones and tetramethylthiuram disulfide yield sterically crowded azobenzenes, rare catecholate-supported Pb3 clusters, and sulfur-rich dimers. The observation that these oxidative transformations quench emission underscores the sensitivity of radiative pathways to the metal coordination environment, positioning these imides as a versatile platform for exploring heavy main-group reactivity and materials design.