DFT Study of Optical Properties of Pt-based Complexes

We report Density Functional Theory (DFT) calculations providing the geometrical and electronic structures, as well as the vibrational and optical properties of the homologous series of Pt-pyramidalized olefin complexes (CH2)(n)-(C8H10)Pt(PH3)(2), where n = 0, 1, and 2, in their neutral and oxidized states All complexes were geometry optimized for the singlet ground state in vacuum using DFT methods with B3LYP exchange-correlation functional and the Effective Core Potential LANL2DZ basis set, within the frame of Gaussian03 quantum chemistry package We find the coordination geometry of Pt to be distorted square planar, with dihedral angles ranging from 00, for n = 0 and 1, which have C-2v symmetry to 3.4 degrees, for n = 2 with C-2 symmetry. The Mulliken charge analysis allows a discussion of the oxidation state of the Pt ion. Electronic transitions were calculated at the same level of theory by means of Time Dependant-DFT. For n = 2 the electronic absorption bands are located in the UV region of the spectrum, the transitions being assigned to metal to ligand charge transfers. The relevance of these Pt-based compounds as possible pigments for dye-sensitized solar cells is discussed.