Single crystals of [(Cp*Ru)2(η6, η6-(1,4)cyclophane)2+][(TCNQ) 42-] (Cp* = η5-C5Me 5, TCNQ = tetracyanoquinodimethane) have been examined by EPR spectroscopy at temperatures down to 4 K. The anisotropic spectrum measured in the 77-150 K range is characteristic of an excitonic triplet species (I). This behavior is attributed to interactions between electrons located in one of the TCNQ acceptor stacks present in the title compound. The direction of maximum electronic interaction coincides with the stacking axis of the crystals (the crystallographic a axis). Intensity measurements establish that I is a thermally excited triplet with a J = 560 ± 30 cm-1, exhibiting zero field splittings of \D\ = 187 MHz (66G) and \E\ = 32 MHz (10 G). A second although weaker feature in the spectrum is tentatively assigned to a second triplet (species II) having very much smaller values of \D| and J than those of I. Species II is attributed to an impurity present in very low concentrations.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry