Structure, Dynamics, and Photophysical Properties of a Series of [Pt(NH2R)4]-[PtX4] Complexes.

Abstract

Theoretical investigations of the structural, dynamics, and photophysical properties of Magnus' green salt complex and its derivatives obtained with different substituent were carried out at different levels of theory with a particular focus on the structure and the dynamics of the complex in the ground state and the excited state. The present work illustrates the results of both the quantum mechanics formulation of the time dependent density functional theory (TDDFT) (LR-TDDFT-QM) and TDDFT based Born-Oppenheimer molecular dynamics (LR-TDDFT-BOMD) within the linear response theory. The appropriate choice of the functional within the LR-TDDFT-QM approach appears to be of major importance to get relatively satisfactory results for the photophysical properties and the absorption spectra of such type of complexes. These effects were characterized through the polarization of the basis set function. Regarding our current knowledge of the properties of Magnus' salts, LR-TDDFT-QM and LR-TDDFT-BOMD were performed on a series of complexes of the type [Pt(NH2R)4]-[PtX4], with R denoting an alkyl group and X is a halogen. The effects of the low and medium range Pt-Pt distance upon the absorption wavelength were explored. Available data in the literature of the electronic structure of such material correlated to our results indicate that, the substituent has a double effect both on the shapes and position of the absorption bands. A perceptive shift of the absorption wavelengths is observed, a consequence of the structure and dynamics of the complex in the ground state. The distortion observed in the Pt-Pt distance is found to be a direct consequence of the rotational motion of groups of atoms. By association of the different theoretical approaches, several interesting properties in the ground state and the excited state were determined.