Double Photoinduced Jahn–Teller Distortion of Tetrahedral Au I Sn II Complexes

Tetrahedral Au I complexes [ L 3 Au(SnCl 3 )] ( L =PMe 3 ( 1 ), PMe 2 Ph ( 2 ), PMePh 2 ( 3 ), and PPh 3 ( 4 )) were prepared by treatment of the [(tht)Au(SnCl 3 )] (tht=tetrahydrothiophene) complex with three equivalents of the corresponding tertiary phosphine. The crystal structures of complexes  1 – 4 have been determined through X‐ray diffraction studies showing, in all cases, [SnCl 3 ] − fragments covalently bonded to the corresponding [Au(PR 3 ) 3 ] + units, which leads to a tetrahedral coordination environment for gold. Complexes  3 and 4 show phosphorescence in the solid state at room temperature and 77 K that is largely redshifted relative to the free [Au(PR 3 ) 3 ] + and [SnCl 3 ] − counterparts. Correlated MP2, SCS‐MP2, and ONIOM MP2/UFF calculations suggest a largely distorted lower triplet excited state (T 1 ) for each model system. The AuP 3 + moiety is distorted leading to a T‐shape, whereas the SnCl 3 − unit is left almost unaltered. Molecular orbital and population analysis suggest that the emission of these tetrahedral Au I complexes arises from a 3 MC transition slightly perturbed by the SnCl 3 − fragment.