Electronic properties of novel donor–acceptor type charge transfer complexes, (BETS) 2(X 2TCNQ) ( X=Cl, Br): 1H, 77Se and 13C-NMR

Abstract

13 C and 77 Se NMR measurements were performed to investigate the electronic properties of (BETS) 2 (X 2 TCNQ) (X=Cl, Br). The susceptibility was decomposed into the contributions of BETS and X 2 TCNQ site. The line broadening of the 1 H/ 77 Se NMR spectra were observed in the Br 2 TCNQ complex at the metal insulator transition temperature, 12 K. Non magnetic spin singlet formation on the Br 2 TCNQ site was observed at 80 K by 13 C NMR. Line broadening of the 1 H NMR spectra were also observed in the Cl 2 TCNQ complex at the metal insulator transition temperature. The insulating state of the Br and Cl 2 TCNQ complexes under pressure are both magnetic. The holes on the BETS layers are relevant to the magnetic ordering.