Hydrogen transfer in hydrogen-bonded chloranilic acid studied by 35Cl NQR I – a 1:2 complex with 1,4-diazine

35Cl NQR frequencies and spin-lattice relaxation time (T1Q) and 1H NMR relaxation times (T1H) in a H-bonded three molecular system, chloranilic acid–1,4-diazine (1:2) were measured to reveal H-motions in a symmetric two H-bonds in solid. A single 35Cl NQR frequency observed implies that the time-averaged structure of chloranilic acid is roughly monovalent in accordance with pKa values in both acid and base. T1H temperature dependence was explained by a single relaxation mechanism due to the correlated H-transfer in two H-bonds, while that of T1Q yielded two relaxation processes. One of these undetected by 1H NMR was explained by the uncorrelated H-transfer.