Polarized single-crystal specular reflectance spectra of (TMTSF)2ClO4 in the visible and ultraviolet

One-Dimensional Collective Electronic Effects in the Helically Stacked Cs2[Ni(CN)4]·H2O and Cs2[Pt(CN)4]·H2O: X-ray Structure, Polarized Specular Reflectance, and ZINDO Calculations

“…Square planar tetracyano complexes of platinum metals have long been studied for their interesting electronic perturbation along the stacking axis. − In most cases, this leads to a “solid state effect” which causes the out-of-plane-polarized a 1g (d z 2 ) → a 2u (p z , π*) transition to red shift and intensify as the planes stack closer. ,− In extreme cases, such as with partially oxidized Pt(CN) 4 2.3+ where the stacking is extremely close (∼2.9 Å), the stack exhibits metallic reflection and moderate electrical conductivity in the stacking direction. ,, Our principal interest has been to identify the mechanism of spectral perturbation and its relationship to metallic conductivity. The perturbation has been described by some as band formation while others have suggested exciton formation .…”