On the Origin of Solvent‐Dependent Ultraviolet–Visible Spectral Behavior of the Complexes [R ₃ PAuCl] _<i>n</i> (R = H, Me and Et, <i>n</i>  = 1,2)

A detailed computational study is performed on the structural and spectroscopic properties of R 3 PAuCl (R = H, Me, Et) compounds, combining density functional theory (DFT) and time‐dependent DFT (TD‐DFT) calculations. The investigation addresses the conformational behavior of monomeric and dimeric species in the gas phase and in solution using the conductor‐like screening model (COSMO). Dispersion‐corrected optimizations reveal that molecular aggregation significantly influences geometry and spectral response. Energy decomposition analysis is employed to quantify the nature of the noncovalent interactions stabilizing the dimeric arrangements. Simulated ultraviolet–visible (UV–vis) spectra, including both radiative and nonradiative transitions, are computed with and without spin‐orbit coupling (SOC), highlighting its impact on spectral intensity and agreement with experiment. Solvatochromic trends are analyzed across solvents (toluene, tetrahydrofuran, acetonitrile, and dimethyl sulfoxide), showing that excited‐state dipole moments play a central role in the observed shifts. A saturation effect in the solvent response is identified, suggesting limitations of the implicit solvation model at high polarity. The combined results provide a coherent framework to interpret the structural and photophysical properties of these systems and emphasize the relevance of accounting for aggregation state (monomer or dimer), dispersion, SOC, and solvent effects to achieve quantitative agreement with experimental UV–vis spectra.