Crystal Structure, Photophysical Properties, and Theoretical Investigation of Extremely Distorted Pentacapped Trigonal-Prismatic Undecasilver Clusters

A new cluster family of the type [Ag-11(S){S2P(OR)(2)}(8)](+) (R = Et, Pr, Pr-i) has been synthesized and characterized as their hexafluorophosphate salts. These compounds are the first silver dithiophosph(in)ato complexes exhibiting photoluminescence at ambient temperature. Their unprecedented skeletal structure describes a very distorted pentacapped trigonal-prismatic polyhedron. Geometry optimizations by DFT calculations on the R = H model reproduce the same structural arrangement in the ground state. Its electronic structure exhibits a low-lying LUMO with a large Ag(5s/5p) character whereas the highest occupied levels have a major contribution from the ligand sulfur lone pairs. The above-mentioned orbitals are shown to be responsible for the optical absorption and emission properties of these compounds.