The charge transfer in some alkaline salts of tetracyanoquinodimethane (TCNQ): A Zeeman perturbation study of the14N nuclear quadrupole resonance spectrum of polycrystalline Rbndash;TCNQ

摘要

Two14N nuclear quadrupole resonance absorption lines (2904.4 and 2967.7 kHz) detected in Rbndash;tetracyanoquinodimethane (TCNQ) at room temperature were studied by the Zeeman perturbation effect and the results interpreted in terms of the theory of Pissanetzky lsqb;J. Chem. Phys. 59, 4197 (1973)rsqb;. The two lines were identified as ngr;+with eegr; of 0.40plusmn;0.04 and 0.57plusmn;0.05 and coupling constants of 3490 and 3254 kHz, respectively. The observed spectrum is compatible with a crystal structure with two inequivalent nitrogen sites such as the monoclinic phase of Rbndash;TCNQ II. Using the Townes and Dailey theory and an estimation of the effects of the crystal field, and by comparison of the NQR data of K, Rb, and neutral TCNQ, we found an increase of about 10percnt; to 14percnt; in the pgr;xpopulation and a decrease of about 5percnt; in the sgr; population at the nitrogen. A twohyphen;way charge transfer within the CN group seems to take place upon the molecular charge transfer as predicted by Clementi and Klint lsqb;J. Chem. Phys. 50, 4899 (1969)rsqb;.