Theoretical Analysis of the Triplet Excited State of the [Pt₂(H₂P₂O₅)₄]^4- Ion and Comparison with Time-Resolved X-ray and Spectroscopic Results

Abstract

A full understanding of the nature of excited states of transition metal complexes is important for understanding their chemical reactivity and role as intermediates in photochemically induced reactions. The ground and excited states of the [Pt(2)(pop)(4)](4-) ion are investigated using density functional theory (DFT). Calculations with different functionals employing quasi-relativistic Pauli and ZORA formalisms all predict a Pt-Pt bond shortening and a slight Pt-P lengthening upon excitation to the lowest triplet state, the latter in apparent contradiction to experimental EXAFS results. The PW86LYP functional with the ZORA relativistic treatment is found to produce good agreement with time-resolved crystallographic and spectroscopic results. A topological bond path between the Pt atoms is found in both the ground and the excited states, though the electron localization function (ELF) indicates weak Pt-Pt covalent bonding for the excited state only. The spin density is mainly localized on the Pt atoms, giving insight into the ability of the triplet excited state to abstract hydrogen and halogen atoms from organic substrates.

Synchrotron ultrafast techniques for photoactive transition metal complexes

“…Van der Veen et al analysed the transient EXAFS spectrum in energy space directly, according to the method [158] mentioned in §3. A 0.31 Å contraction of Pt-Pt bonds was found, whereas a slight lengthening of 0.010 Å was observed for Pt-P bond distances with respect to GS values, in good agreement with theoretical calculations [214]. [68], the structure of which is shown in figure 7b, left-hand panel.…”

DFT calculations of light‐induced excited states and comparison with time‐resolved crystallographic results

“…The changes in the PtOPt distance and the lowest singlet-triplet excitation energy calculated with different functionals and two relativistic treatments, and, as observed, are graphically summarized in Figure 3 [23]. Examination of the figure shows that the calculated shortening of the PtOPt bond length and the corresponding TD-DFT singlet-triplet excitation energy are quite dependent on both the density functional and the relativistic treatment.…”

Ab initio Study on Luminescence and Aurophilicity of a Dinuclear [(AuPH3)2(i‐mnt)] Complex (i‐mnt = isomer‐Malononitriledithiolate)

“…0.29 Å relative to that in the ground state, which is supported by both the excitedstate structure from time-resolved X-ray diffraction and ab initio studies. [29,30] For Au I complexes containing both phosphane and thiolate ligands, the lower-energy emissions in the solid state have been experimentally attributed to AuǞthiolate charge transfer (MLCT). [11,17,24,31Ϫ36] Bruce's studies on a series of dinuclear (phosphane)Au I thiolates with or without AuϪAu interaction showed that the interaction is not a necessary condition for luminescence and that its presence does not significantly perturb the luminescence; [32] however, Fackler and co-workers found that the emission maximum in the luminescence of many mononuclear (phosphane)Au I thiolate complexes can be affected by an AuϪAu interaction.…”