Mixed-Valence Two-Legged MX-Ladder Complex with a Pair of Out-of-Phase Charge-Density Waves

A novel two-legged MX-ladder complex {[(dien)PtIVBr2-bpy-PtII(dien)]Br4·2H2O}∞ was synthesized and analyzed by single-crystal X-ray diffraction method and Raman and diffuse reflectance spectra. The electronic structure on two-legged MX-ladder is a pair of out-of-phase charge-density-waves state within each ladder, and these pairs of CDWs are also ordered from ladder to ladder. The intervalence charge-transfer (PtII to PtIV) excitation energy is significantly larger than that in the MX-chain system because of the intersite Coulomb repulsion along the rung.