Metallophilic bonding in heterometallic complexes has recently attracted the attention of theoreticians and experimentalists focusing on intramolecular (d10-d10) interactions in hetero- and homo-metallic polynuclear structures. Besides the short distances that are up to 50-100 pm shorter than typical metallophilic distances in homometallic analogues, they have approximately 1-2 order-of-magnitude stronger M-M’ bonds than for typical M-M bonds. Here, we extend the study of the metallophilic bonding to pentanuclear ([M3M’2Mes]5, complexes (1) with short M-M distances shown in Figure 1. Gambarotta et al. reported synthesis of the pentameric ([CuMes]5), structure (1) having a pentagram-shaped structure with mesityl (Mes = 2,4,6-Me3C6H2) ligands, leading to a remarkably short Cu(I)-Cu(I) bond distance of 2.45 Å. The investigated molecules include M or M’ = Cu(I), Ag(I), or Au(I). Properties of the lowest excited states are studied at the time-dependent DFT level (TDDFT). The diamond-shaped metal core in the (Me3SiCH2Cu)4 (1) complex has a Cu(I)-Cu(I) bond distance of 2.35 Å. DFT calculations are using the TPSS and TPSSH functionals as well as using a modern range-separated functional. Dispersion interactions are considered by using a semi-empirical correction term. The molecular structures are also optimized at the second-order Møller-Plesset (MP2) perturbation. The reliability of the calculated excitation energies will be assessed by performing approximate second-order coupled-cluster (CC2) calculations and at the related ADC(2) level. Electronic excited states will also be studied since little is known about their properties for this class of molecules. One aim is to investigate whether the studied molecules can be starting structures for third generation emitting materials, that is, organic and inorganic compounds with thermally activated delayed fluorescence (TADF). Molecules containing Cu(I) instead of more expensive metals is a step towards more sustainable light-emitting materials. The quantum yield of luminescence can be obtained by calculating the fluorescence and phosphorescence emission rates and compare them with the rates of the nonradiative processes. Calculations of rate constants for nonradiative transitions require vibrational frequencies of the lowest electronic excited states. Spin-orbit coupling matrix elements are needed for the calculation of rate constants for intersystem crossing (ISC).

Experimental and theoretical study of multinuclear interaction in pentanuclear ([M3M’2Mes]5, complexes, where M or M’ = Cu(I), Ag(I), and Au(I)

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.