Me₃TTF–PO₃H₂, a Redox Phosphonic Acid and Its Monoanilinium Salt [PhNH₊₃][Me₃TTF–PO(OH)O‐], the Electrocrystallized Neutral (Zwitterionic) π Radical [Me₃TTF–PO(OH)O‐]·+, and Their Associated Lamellar Constructions in the Solid State

The reaction of Me 3 TTFLi (TTF = tetrathiafulvalene) with ClP(O)‐(OEt) 2 followed by hydrolysis with Me 3 SiBr affords the novel π‐donor molecule trimethyltetrathiafulvalenylphosphonic acid (Me 3 TTF–PO 3 H 2 ) in a partially oxidized form. Subsequent reduction and neutralization with aniline gives the corresponding phosphonate monoanilinium salt. A unique hydrogen‐bonded hexagonal net is identified within the lamellar structure of [PhNH +3 ][Me 3 TTF–PO(OH)O ‐ ], which is described by analogy with the anti‐CaSi 2 structure type. Electrocrystallization of the former salt yields single crystals of a neutral (zwitterionic) π radical, formulated as [Me 3 TTF–PO(OH)O ‐ ] ·+ . Their structure reveals the presence of hydrogen‐bonded molecular ribbons whose association creates a novel layered architecture similar to that obtained within radical cation salts of π‐donor molecules of larger spatial extension. The analysis of the calculated HO‐MO–HOMO intermolecular interaction energies demonstrates that these slabs contain strong π‐π intermolecular interactions despite the nonexistence of any 2D network of short S ⃛S contacts. The spin susceptibility of [Me 3 TTF–PO‐(OH)O ‐ ] ·+ , determined by single‐crystal ESR measurements, is characteristic of triplet excitons, the origin of which may be understood from the electronic structure of the compound.