Trivalent carbons, including radicals, anions, and cations, are fairly reactive species but they have important applications in diverse fields of chemistry. We have designed several polycyclic aromatic hydrocarbon radicals, anions, and cations with a cyclopentadienyl central unit that are stabilized through resonance delocalization and steric protection. Extensive efforts were directed toward the synthesis of several targets, including anthracene substituted tetrabenzofluorene/phencyclone radicals (3b/4b) and C55H55 “superbowl” cation (16a), radical (16b), and anion (16c), which adopt a bowl-like shape. Radical 3b, 4b, and 16b have potential applications in Dynamic Nuclear Polarization (DNP) to enhance NMR signals; anion 16c is potentially a pentahapto (η5-) ligand in coordination chemistry; and cation 16a could help us understand the limit of antiaromaticity. Several synthetic routes were developed for each target and initial DFT calculations were performed to understand spin/charge density distribution of the radical, anion, and cation. The radical precursors of 3b and 4b were successfully prepared in four and two steps, respectively, with 16-31% overall yields. Future directions will be discussed.

Trivalent carbons including organic radicals, anions, and cations are fairly reactive species yet have important applications in diverse fields of chemistry. Stable organic radicals are utilized in Dynamic Nuclear Polarization (DNP) to enhance NMR signals; some organic anions are pentahapto (_η_5-) ligands in coordination chemistry; and stabilized organic cations could help us understand the limit of antiaromaticity. We have designed several polycyclic aromatic hydrocarbon radicals, anions, and cations with a cyclopentadienyl central unit that are stabilized through resonance delocalization and steric protection. Extensive efforts were directed toward the synthesis of several targets, including anthracene/durene–tetrabenzofluorene radical **(1a/b)**, anthracene–phencyclone radical (**2**) and C55H55 “superbowl” radical (**3·**), anion (**3-**), and cation (**3+**), which adopt a bowl-like shape. Several synthetic routes were developed for each target and initial DFT calculations were performed to understand spin/charge distribution of radical, anion, and cation. The radical precursors **7a**/**b** (for **1a**/**b**) and **17** (for **2**) were successfully prepared in four and two steps, respectively, and with 6-31% overall yields. Future directions and hypothetical syntheses are also discussed.

Design, synthesis, and characterization of stable polycyclic aromatic hydrocarbon radicals, anions, and cations

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