The Nature of Intermolecular Cu^I⋅⋅⋅Cu^IInteractions: A Combined Theoretical and Structural Database Analysis

Abstract

The nature of intermolecular interactions between dicoordinate Cu(I) ions is analyzed by means of combined theoretical and structural database studies. Energetically stable Cu(I).Cu(I) interactions are only found when the two monomers involved in the interaction are neutral or carry opposite charges, thus allowing us to speak of bonding between the components of the bimolecular aggregate. A perturbative evaluation of the components of the intermolecular interaction energies, by means the IMPT scheme of Stone, indicates that both the Coulombic and dispersion forces are important in determining the Cu(I).Cu(I) bonding interactions, because only a small part of that energy is attributable to Cu.Cu interactions, while a large component results from Cu.ligand interactions. The electrostatic component is the dominant one by far in the interaction between charged monomers, while in the interaction between neutral complexes, the electrostatic component is found to be of the same order of magnitude as the dispersion term. Bimolecular aggregates that have like charges are repulsive by themselves, and their presence in the solid state results from anion.cation interactions with ions external to this aggregate. In these cases, the short-contact Cu.Cu interactions here should be more properly called counterion-mediated Cu.Cu bonds.

Aurophilicity: The Effect of the Neutral Ligand L on [{ClAuL}2] Systems

“…[10] Copper still remains a bit of a puzzle. The experimental examples with potential Cu I ···Cu I interactions tend to have one or several bridges between the copper atoms, see references [12,[35][36][37]. (For one unbridged Cu···Cu of 265 pm, see work by Chiarella et al [38] ) As quoted by van Koten, [35] a simple model for such a bridging was proposed by Mason and Mingos.…”

Intertrimer and Intratrimer Metallophilic and Excimeric Bonding in the Ground and Phosphorescent States of Trinuclear Coinage Metal Pyrazolates: A Computational Study

“…Metallophilicity is an attractive interaction between a pair of d 10 atoms that is a result of long-range dispersion forces., [7][8][9][10][11] There has been some debate regarding the role of cuprophilicity versus electrostatic interaction and ligand assistance in binding Cu I dimers in general, 10,11 although the specific case of intertrimer interactions in trinuclear Cu I pyrazolates was suspected to be due to a genuine cuprophilic interaction. 2b,11 With multiple d 10 atoms in close contact, metallophilicity may reasonably be expected to play an important role in understanding the dimer-of-trimers interactions in the singlet ground state of {[Cu(Pz)] 3 } 2 .…”

An Unstable Ligand‐Unsupported CuIDimer Stabilized in a Supramolecular Framework

“…Nevertheless, the orbital interactions, including induction, charge transfer, and dispersion, are stabilized by À27.2 kJ mol À1 and so fall into the range of cuprophilic interactions estimated from spectroscopic or theoretical studies. [6][7][8] The results of the DFT calculations indicate that the HOMO-1 (HOMO = highest occupied molecular orbital) is a Cu i ···Cu i s bonding molecular orbital, the HOMO is a Cu i ···Cu i s antibonding molecular orbital, and the lowest unoccupied molecular orbital (LUMO) has Cu i ···Cu i bonding character with 4d, 5s, and 5p contributions from the Cu i center (Figure 2). The Mayer bond order [17,29] of the Cu i ···Cu i interaction is calculated to be 0.187 (see the Supporting Information), which is in agreement with the IMPT analysis and shows the orbital interactions to be weakly attractive.…”

“…[5] The existence of ligand-bridged Cu i ···Cu i interactions is supported by spectral evidence [6] and has been examined by a series of theoretical calculations, which have sometimes reached different conclusions. [7] However, a recent comprehensive analysis [8] has shown that only a small part of the intermolecular interaction energy is often gained in the ground state from the Cu i ···Cu i interaction, whereas a large component results from Cu i ···ligand interactions, even in the case of ligand-unsupported Cu i ···Cu i species. Only a few examples of ligand-unsupported Cu i aggregates have been described, most of which have been reported quite recently.…”

“…Bimolecular Cu i ···Cu i aggregates that have like charges have been calculated to be repulsive. [8] In the ground state, often only a small part of the intermolecular interaction energy gained results from the direct Cu i ···Cu i interaction, whereas a large component of this energy results from Cu i ···ligand interactions. In accordance with the calculations reported by Carvajal et al, the IMPT calculations show that the electrostatic repulsion, which is purely Coulombic in origin, is dominant in the current case (311.8 kJ mol À1 ; see the Supporting Information).…”