Effects of Chain Length and Au Spin‐Orbit Coupling on ³(ππ*) Emission from Bridging C_n²⁻ Units: Theoretical Characterization of Spin‐Forbidden Radiative Transitions in Metal‐Capped One‐Dimensional Carbon Chains [H₃PAu(CC)_nAuPH₃]

Abstract

Density functional theory and CASSCF calculations have been used to optimize the geometries of binuclear gold(I) complexes [H(3)PAu(C[triple bond]C)(n)AuPH(3)] (n=1-6) in their ground states and selected lowest energy (3)(pi pi*) excited states. Vertical excitation energies obtained by time-dependent density functional calculations for the spin-forbidden singlet-triplet transitions have exponential-decay size dependence. The predicted singlet-triplet splitting limit of [H(3)PAu(C[triple bond]C)(proportional/variant)AuPH(3)] is about 8317 cm(-1). Calculated singlet-triplet transition energies are in reasonable agreement with available experimental observations. The effect of the heavy atom Au spin-orbit coupling on the (3)(pi pi*) emission of these metal-capped one-dimensional carbon allotropes has been investigated by MRCI calculations. The contribution of the spin- and dipole-allowed singlet excited state to the spin-orbit-coupling wave function of the (3)(pi pi*) excited state makes the low-lying acetylenic triplet excited states become sufficiently allowed so as to appear in both electronic absorption and emission.

Theoretical Chemistry of Gold

“…CIS calculations of the optical spectrum of the eight‐ring with the ligand combination [Au 2 (dpm)(HSCH 2 SH)] 2+ were published by Pan and Zhang 757. Both DFT and CASSCF calculations were reported for the optical spectra of two Au I atoms, coupled by a polyacetylide chain 758. Spin‐orbit effects will allow triplet→singlet transitions.…”

Theoretische Chemie des Golds

“…Über CIS‐Rechnungen des optischen Spektrums von [Au 2 (dpm)(HSCH 2 SH)] 2+ berichteten Pan und Zhang 757. Ein zweikerniger Goldkomplex mit einer Polyacetylid‐Kette zwischen zwei Au I ‐Atomen wurde sowohl durch DFT‐ als auch durch CAS‐SCF‐Methoden berechnet 758. Spin‐Bahn‐Kopplungen ermöglichen einen Triplett‐Singulett‐Übergang.…”