Valence-localised and valence-delocalised mixed-valence states; the effect of the substitution pattern of 1,2-, 1,3- and 1,4-[C6H4(NH)2]2 as bridging ligands

Abstract

The mixed-valence complexes [{MoL(NO)X}₂{µ-1, n-C₆H₄(NH)₂}]^–[L = tris(3,5-dimethylpyrazolyl)hydroborate; X = Cl, Br, I; n= 2,3,4] containing a 1,2-, 1,3- or 1,4-diamidobenzene bridge are prepared by electrochemical or chemical reduction of the diamagnetic neutral species; EPR spectroscopy shows that with 1,2- or 1,4-diamidobenzene as the bridge the mixed-valence state is delocalised on the EPR timescale, whereas with a 1,3-diamidobenzene bridge the mixed-valence state is valence-trapped.