Structural and optical investigations of charge transfer complexes involving the radical anions of TCNQ and F(4)TCNQ

Abstract

The structures and optical band gaps of twelve radical anionic 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 7,7,8,8-tetracyano-2,3,4,5-tetrafluoroquinodimethane (F4TCNQ) based charge-transfer complexes are reported. The compounds described have been categorised into three general types based upon solid-state arrangements of the donor and acceptor molecules. Crystallographic, EPR and IR spectroscopic investigations indicated that both TCNQ and F4TCNQ in each of the compounds described exist in the radical monoanion form. Visible-NIR absorption measurements indicate optical band gaps in the range of 0.79 to 1.08 eV. Whilst the packing arrangements in CT complexes are known to affect the band ga..