Structural analysis and electronic properties of a homodinuclear erbium(III) complex bridged by the polyazine ligand 2,2′-bipyrimidine

Structural analysis of the previously reported homodinuclear complex [Er(tfa)3]2bpm (where tfa = 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione and bpm = 2,2′-bipyrimidine) synthesized by reaction of two equivalents of ErCl3 with six equivalents of tfa and one equivalent of bpm in a basic ethanol solution is presented. X-ray quality crystals were grown by slow evaporation of concentrated methanol solution containing the complex. The complex crystallizes in the monoclinic space group P21/n, with a planar bpm ligand. The erbium…erbium distance is 6.715(5) Å. Each erbium center is eight coordinate from six tfa oxygens and two bpm nitrogens. Electronic transitions of concentrated solutions of the complex reveal three sharp lines corresponding to the 4f–4f∗ transitions at 486 nm, 520 nm and 657 nm with the lowest energy transition corresponding to 4I15/2 → 4F9/2.