Single-crystal absorption spectroscopy at variable temperature is used to determine exchange couplings between transition metal centers in both the electronic ground and excited states in two new homobimetallic complexes with the formula [LM(μ-O)(μ-CH3CO2)2ML′](ClO4)2, where M is iron(III) or manganese(III). L and L' denote 1,4,7-triazacyclononane and 1,4,7-trimethyl-1,4,7-triazacyclononane, respectively. Values for the ground state exchange coupling constant J are −295 cm−1 and +10 cm−1 for the iron and manganese compounds, respectively, using Hex = −JS1•S2. Exchange interactions in excited states are qualitatively analyzed, indicating that a spin-forbidden transition of the Fe–Fe binuclear unit occurs with significant intensity by the single-ion mechanism, and not as expected by the Tanabe pair intensity mechanism for spin-forbidden transitions, the dominant mechanism for isoelectronic complexes of manganese(II). Keywords: absorption spectra, exchange interaction, magnetic properties, bimetallic complexes of iron(III), bimetallic complexes of manganese(III)
Amorphous Gallium Phosphate Thin Films : Ga and O K-Edge Absorption Spectroscopy
