The Energetic Significance of Metallophilic Interactions

Abstract

Metallophilic interactions are increasingly recognized as playing an important role in molecular assembly, catalysis, and bioimaging. However, present knowledge of these interactions is largely derived from solid-state structures and gas-phase computational studies rather than quantitative experimental measurements. Here, we have experimentally quantified the role of aurophilic (Au I •••Au I), platinophilic (Pt II •••Pt II), palladophilic (Pd II •••Pd II) and nickelophilic (Ni II •••Ni II) interactions in self-association and ligand-exchange processes. All of these metallophilic interactions were found to be too weak to be well-expressed in several solvents. Computational energy decomposition analyses supported the experimental finding that metallophilic interactions are overall weak, meaning that favorable dispersion and orbital hybridization contributions from M•••M binding are largely outcompeted by electrostatic or dispersion interactions involving ligand or solvent molecules. This combined experimental and computational study provides a general understanding of metallophilic interactions and indicates that great care must be taken to avoid over-attributing the energetic significance of metallophilic interactions.

Strong metal–metal Pauli repulsion leads to repulsive metallophilicity in closed-shell d8and d10organometallic complexes

“…In 2018, Guerra and coworkers observed an overall net repulsive MO interaction in the Au I dimer (32). In 2019, Cockroft and coworkers reported a combined theoretical and experimental study to argue that metallophilicity is indeed weak (33). While the academic community has gradually realized the In this work, we address the following topics: 1) the nature of the M-M′ interaction, 2) the role of the metal atom in the intermolecular interaction, 3) the electronic mechanism by which spd hybridization influences the M-M′ interaction, and 4) the role of the relativistic effect on the M-M′ interaction. )…”

“…However, the role of the metal in the intermolecular interaction and the nature of the M-M′ interaction remain obscure as the overall intermolecular interaction does not equally represent the M-M′ interaction. 5) In 2019, Cockroft and coworkers reported a combined experimental and computational investigation, arguing that metallophilic interactions are indeed very weak (33). Notably, Cockroft and coworkers (33) analyzed a series of Au I complexes with Au-Au contacts in the range from 3.3 to 3.5 Å, and these workers claimed the presence of weakly attractive M-M′ interactions.…”

“…5) In 2019, Cockroft and coworkers reported a combined experimental and computational investigation, arguing that metallophilic interactions are indeed very weak (33). Notably, Cockroft and coworkers (33) analyzed a series of Au I complexes with Au-Au contacts in the range from 3.3 to 3.5 Å, and these workers claimed the presence of weakly attractive M-M′ interactions. In this work, Au I /Ag I complexes with shorter M-M′ contacts (2.93 to 3.16 Å) are investigated, where strong M-M′ Pauli repulsion has been observed that leads to an overall repulsive M-M′ interaction.…”

Excimer and Exciplex Formation in Gold(I) Complexes Preconditioned by Aurophilic Interactions

“…[26] It is important to remember in all discussions that Au•••Aui nteractions-as weak forces-quite generally make only small contributions to the overall energetics of ag iven system and that only ac areful evaluation of all parameters can provide aconsistent picture of the true origin of related chemical and physical phenomena. Recent publications refer to these inherent problems [27,28] that had been pointed out also in most previous Reviews of the subject. [11][12][13][14] As expected, intermolecular aurophilic contacts are even more pronounced for aggregates of di-or polynuclear gold(I) complexes where more than one Au•••Auc ontact can be established.…”

Quantifying Interactions and Solvent Effects Using Molecular Balances and Model Complexes

“…The examination of the experimental behavior of organometallic supramolecular complexes and computational decomposition of the interaction energies has been used to unearth the basis and importance of metallophilic interactions. 4 The gold(I)-imidazole coordination bonds contained within the complex depicted in Figure 9A exchange slowly in solution at room temperature in the presence of excess imidazole ligands. Thus, a population of states exists in which the Au(I) … Au(I) contacts are either broken or formed.…”