Theoretical and Photoluminescence Studies on the d¹⁰–s² Au^I–Tl^I Interaction in Extended Unsupported Chains

Abstract

The reactions of solutions of TlPF(6) and OPPh(3) in tetrahydrofuran or acetone with NBu(4)[AuR(2)] (R=C(6)Cl(5), C(6)F(5)) gave the new complexes [Au(C(6)Cl(5))(2)](2)[Tl(OPPh(3))][Tl(OPPh(3))(L)] (L=THF (1), acetone (2)) and the previously reported [Tl(OPPh(3))(2)][Au(C(6)F(5))(2)] (3). The crystal structures of complexes 1 and 2 display extended unsupported chains with short intermolecular interactions between alternating gold(I) and thallium(I) centres. Moreover, the Tl(I) centres show two different types of geometrical environments, such as pseudotetrahedral and distorted trigonal-bipyramidal, due to the presence of solvent molecules that act as ligands in the solid-state structure. Quasirelativistic and nonrelativistic ab initio calculations were performed to study the nature of the intermetallic Au(I)-Tl(I) interactions and are consistent with the presence of a high ionic contribution (80 %) and dispersion-type (van der Waals) interaction with a charge-transfer contribution (20 %) when relativistic effects are taken into account. All complexes are luminescent in the solid state at room temperature and at 77 K. Complexes 1 and 2 show site-selective excitation, probably due to the different environments around the Tl(I) centres. The DFT and time-dependent (TD)-DFT calculations are in agreement with the experimental excitation spectra for all complexes and confirm the site-selective excitation behaviour as a function of the Tl(I) geometrical environment.

Luminescence in Polymetallic Gold‐Heteronuclear Derivatives

“…For instance, the strength of the Au(I)?Tl(I) contacts in extended linear chains with an average metal-metal separation of 3.03 Å is estimated at B276 kJ mol 21 , of which 80% consists on ionic interaction. 48 Consequently, the rationalization of the bonding in these species still remains as a challenge for synthetic and theoretical chemists. Another challenge is now to tune the emissive properties of these compounds, which implies the study of all the factors that modify them, such as the intemetallic distance, the coordination number and geometry around the metal centers-which in the case of Tl(I) is variable 49 -or the donor characteristics of the ligands.…”

“…48 Their crystal structures also display extended linear chains with alternating metal centers in a zigzag disposition, with Au-Tl distances between 3.0529(3) and 3.3205(3) Å (L 5 tetrahydrofuran) or between 3.0937(3) and 3.2705(4) Å (L 5 acetone). It is interesting that in these cases the environments around the thallium atoms, considering the stereochemically active lone pair, are alternatively pseudotetrahedral and distorted trigonal-bipyramidal (Fig.…”

Gold–Heterometal Interactions and Bonds

“…Long X-Tl (X ¼ halogen) contacts between the thallium center and halogen atoms of the almost linear [AuR 2 ] À unit seem also to contribute to the stability of many of these systems. It is worth noting that theoretical studies revealed for the Au-Tl interaction in these systems a surprising calculated strength of about 276 kJ mol À1 , from which 80% is due to an ionic contribution and 20% to dispersion (van der Waals) [55]. [56].…”

“…A yellow-green complex of the same stoichiometry as found for 41, that is [Tl (OPPh 3 ) 2 {Au(C 6 F 5 ) 2 }] n 48, was obtained by reacting Li[Au(C 6 F 5 ) 2 ] with TlNO 3 and triphenylphosphine oxide in Et 2 O/MeOH [64] or [NBu 4 ][Au(C 6 F 5 ) 2 ], TlPF 6 and Ph 3 PO in THF [55]. Surprisingly, treatment of the gold(III) complex [Au(C 6 F 5 ) 2 Cl (PPh 3 )] with equimolecular amounts of Tl(acac) gave the same complex 48.…”

Homopolynuclear TlI and Heteropolynuclear AuI–TlI Complexes with Organodiselone Ligands: Activation of Luminescence by Intermetallic Interactions

“…For instance, we have described metallophilicity between gold(I) and thallium(I) centres that make use of a acid-base synthetic strategy that involves bis(perhalophenyl)aurate(I) precur-I and Heteropolynuclear Au I -Tl I Complexes sors and acid Tl I salts, thereby finding interaction energies as high as 276 kJ mol -1 , of which 80 % is determined by an ionic interaction. [24] In addition to the intriguing nature of this interaction from a theoretical viewpoint, it can be considered to be responsible for very important physical properties of the materials that contain it, for example, luminescence. [25] In those systems, this property is strongly dependent on the environment around the metal centres, the metal-metal distances and the nature of ligands bonded to them.…”