A new hybrid molecular metal assembling a BEDT-TTF conducting network and the magnetic chain anion [Mn2Cl5(H2O)5]−∞: α-(BEDT-TTF)2[Mn2Cl5(H2O)5]

The synthesis, X-ray crystal and electronic band structures as well as magnetotransport and magnetic properties of the α-(BEDT-TTF)2[Mn2Cl5(H2O)5] radical cation salt with a new type of magnetic polymeric complex anion, [Mn2Cl5(H2O)5]−∞, are reported. The crystal structure is characterized by radical cation layers alternating with layers of the polymeric 1-D chain anions constructed from MnCl3(H2O)3 and MnCl4(H2O)2 octahedra connected to each other via the apical Cl atoms. The calculated electronic band structure suggests that the salt should be a stable 2-D metal and the conductivity measurements show that it exhibits metallic behavior down to 0.4 K. Shubnikov-de Haas oscillations, observed at B > 10 T, are characterized by two fundamental frequencies, corresponding to cross-sections of the Fermi surface, in agreement with the electronic band structure calculations. Magnetic measurements reveal antiferromagnetic correlations in the anion network.