Synthesis,Structure, and Polarized Optical Spectra of a New Fluoromanganate(III): [(H3N(CH2)2)2NH2]2[MnF5(H2O)]3

The synthesis and crystal structure of a new fluoromanganate(III), (H₃N(CH₂)₂)₂NH₂]₂MnF₅(H₂O)]₃, is reported. The unit cell is unusually large: monoclinic, P2₁/c (no. 14), a = 41.0512(13) Å; b = 9.6469(4) Å; c = 12.8021(7) Å; β = 91.927(4)°; Z = 8, R = 0.0627 and wR₂ = 0.1347. The MnF₅(H₂O)]^2– anions are octahedral with a strong distortion along the F–Mn OH₂ axes due to the Jahn-Teller effect. A very rich intermolecular hydrogen bond framework is present, leading to chains of octahedra linked by double-hydrogen bonds. The polarized optical spectra on single crystals are explained in terms of the intraconfigurational d⁴ transitions split by a ligand field of C_4v symmetry.