A stable metallic state of (TTPCOO)2NH4 with a mobile dopant.

Ammonium tetrathiapentalene carboxylate [(TTPCOO)2NH4] was prepared via protonic defect-induction doping without electrochemical oxidation. The high electric conductivity of 13 S cm(-1) and Pauli paramagnetic-like behavior of magnetic susceptibility in a wide temperature range exhibit a melting of the charge degrees of freedom induced by a mobile dopant in a salt bridge. Solid-state (1)H NMR strongly indicates a stable metallic state of this compound down to 4 K.