Infrared (IR) absorption spectra of 1-RE•0.5MeCN were acquired in the solid state, reported (Figure ) with tabulated data and assignments in Table . The spectra of all complexes are near identical, which is consistent with the isostructural nature of the complexes determined by X-ray crystallography. All tpa stretches, ν(C=C) and ν(C=N) were observed and consistent with previous measurements. Previous density functional theory vibrational analysis on o-dioxolene ligands allowed the assignment of key Br4catH -bands. In addition, a broad peak cantered at 3100 cm -1 is assigned to the ν(O-H) originating from the monoprotonated catecholate. Compared to typical O-H stretches, this peak has shifted to lower frequencies indicating H-bonding consistent with the crystal structures. Electronic Spectroscopy