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

Abstract

Tetrahedral AuI complexes [L3Au(SnCl3)] (L=PMe3 (1), PMe2Ph (2), PMePh2 (3), and PPh3 (4)) were prepared by treatment of the [(tht)Au(SnCl3)] (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, [SnCl3]− fragments covalently bonded to the corresponding [Au(PR3)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(PR3)3]+ and [SnCl3]− counterparts. Correlated MP2, SCS‐MP2, and ONIOM MP2/UFF calculations suggest a largely distorted lower triplet excited state (T1) for each model system. The AuP3+ moiety is distorted leading to a T‐shape, whereas the SnCl3− unit is left almost unaltered. Molecular orbital and population analysis suggest that the emission of these tetrahedral AuI complexes arises from a 3MC transition slightly perturbed by the SnCl3− fragment.

Double Jahn–Teller Distortion in AuGe Complexes Leading to a Dual Blue–Orange Emission

“…We have studied the photophysical properties of complexes of stoichiometry [Au(GeCl 3 )L 3 ] (L=PMe 3 ( 1 ), PPhMe 2 ( 2 ), PPh 2 Me ( 3 ), PPh 3 ( 4 )). The absorption spectra of all the complexes are similar to those of related derivatives with gold(I)–tin(II) interactions, previously reported by some of us . The four complexes show an intense absorption peak at 200 nm, with long tails that extend to 300 nm for complexes 3 and 4 .…”

“…Thus, this transition is probably the reason for the intense emissions detected in complexes 1 and 2 and for the most intense peak observed in the emission spectrum of 3 . In addition, the three‐coordinate [Au(PR 3 ) 3 ] + species show emissions in acetonitrile solution at 525 nm (PR 3 =PPhMe 2 , PPh 2 Me) and 505 nm (PPh 3 ), which can be assigned to gold‐centered transitions, while the [Au(PMe 3 ) 3 ] + cation is not luminescent in solution . The emission observed for complex 1 corresponds to the [GeCl 3 ] − synthon.…”

“…One exception is the P‐Au‐Ge‐Cl dihedral angle in complex 4 , which is close to 0° at MP2 and SCS‐MP2 levels as compared to 40.7° in the experimental structure due to the steric effects of the phenyl groups of the phosphine ligands. The structural trends are similar to those obtained in the previous studies of the corresponding AuSn systems …”

“…The character of the frontier orbitals of S 0, T 1 , and T 2 of [(PH 3 ) 3 Au(GeCl 3 )] ( A ) also suggests that there are two gold‐based phosphorescent emission states (see Figures and ). For S 0 , the shape of the molecular orbitals is very similar to that found in the analogous gold–tin compounds . The highest occupied molecular orbital (HOMO) is mainly a mixture of the and Ge II 5s/5p orbitals that belong to the a 1 irreducible representation of the C 3 v point group.…”

“…Three‐coordinate gold complexes are also among the best‐known luminescent units: their luminescence is characterized by long‐wavelength emissions of phosphorescent nature, making them suitable as emitters in phosphorescent organic light‐emitting diodes (POLEDs) . We recently reported the rich luminescent behavior of a series of gold–tin complexes [L 3 AuSnCl 3 ] where L is a tertiary phosphine . The bonding of the two synthons in [L 3 AuSnCl 3 ] led to a new type of phosphorescent red emitters through the combination of two independent distortions in the excited state, namely a first‐ and a second‐order Jahn–Teller effect at gold and tin, respectively.…”