Resonant Raman Scattering And Esr Study Of Et Salts With Rhenium-Containing Anions

Two charge-transfer salts of ET (bis(ethylenedithio)tetrathiafulvalene or BEDT-TTF) molecule and the anions containing multiple Re-Re bond have been investigated using Raman scattering and electron spin resonance (ESR) spectroscopies. Q-band ESR study allowed to record well-split ESR spectra and determine spectroscopic splitting coefficients of ET+center dot radicals. The ESR data show the existence of two types of ET molecules in ET2[Re2Cl8] and one type in ET[Re2Br6CH3COO]0.5(C2H3Cl3) that is consistent with the structural data. Additionally, the antiferromagnetic coupling within the ET dimers at low temperature was detected. The charge +1 e per ET molecule in both salts have been determined from the position of the vibrational modes (2) and (3) (A(g)) of the ET molecule and compared with values obtained from the bond lengths analysis. The excitation line 633nm was used to obtain the resonant Raman spectra of the salts. The enhanced anion fundamental vibrations and overtones show typical resonant behaviour. Moreover, the position of the band related to the Re-Re stretching vibration confirm the quadruple nature of the metal-metal bonds in the anions.