Synergistic and Diminutive Effects between Regium and Aerogen Bonds

Abstract

The aerogen bond is formed in complexes of HCN−XeF2O and C2H4−XeF2O. The lone pair on the N atom of HCN is a better electron donor in the aerogen bond than the π electron on the C=C bond of C2H4. The coinage substitution strengthens the aerogen bond in MCN−XeF2O (M=Cu, Ag, and Au) and its enhancing effect becomes larger in the Au<Cu<Ag pattern. The aerogen bond is further enhanced by the regium bond in C2H2−MCN−XeF2O and C2H4−MCN−XeF2O, but is weakened by the regium bond in MCN−C2H4−XeF2O and C2(CN)4−MCN−XeF2O. Simultaneously, the regium bond is also strengthened or weakened in these triads. The synergistic and diminutive effects between regium and aerogen bonds have been explained by means of charge transfer and electrostatic potentials.

Noncovalent Bonds through Sigma and Pi-Hole Located on the Same Molecule. Guiding Principles and Comparisons

“…Unfortunately, this work did not delve into the σ or π-hole depths as background information. [111]. The σ-hole was able to interact with a N lone pair as well as the unsaturated π-system of a C=C bond.…”

“…where M= Cu, Ag or Au [111]. The σ-hole was able to interact with a N lone pair as well as the unsaturated πsystem of a C=C bond.…”

“…As work has progressed, there has been recognition of π-holes as providing a means by which an aerogen bond (involving rare gas atoms) can form [100][101][102][103][104]. Other newly introduced types of σ/π-hole directed interactions are alkali and alkaline earth bond (e.g., beryllium bond, magnesium bond) in which atoms of 1st and 2nd groups contribute [105][106][107][108][109] or regium and spodium bonds which employ transition metals from 11th (regium [110][111][112][113][114][115]) or 12th (spodium [105,[116][117][118][119]) groups of the periodic table. The full range of these sorts of bonds, along with their designations, is summarized in Figure 1.…”

Anion⋅⋅⋅Anion Coinage Bonds: The Case of Tetrachloridoaurate

“…[5] Seven years ago, a possible extension of this mindset to dblock elements was considered [6] and subsequently confirmed, first for elements of Group 11, [7] and then for elements of Groups 10 [8] and 12. [9] Various theoretical studies, [10][11][12][13] and a more limited number of experimental findings, [14,15] have shown that nanoparticles [16] and halide salts [14] of Cu, Ag, and Au form attractive interactions with a variety of donors of electron density by involving the regions with the most positive electrostatic potential at their outer surface. It has been proposed that such interactions involving Group 11 elements should be designated as regium bonds [10] or coinage bonds.…”

“…[9] Various theoretical studies, [10][11][12][13] and a more limited number of experimental findings, [14,15] have shown that nanoparticles [16] and halide salts [14] of Cu, Ag, and Au form attractive interactions with a variety of donors of electron density by involving the regions with the most positive electrostatic potential at their outer surface. It has been proposed that such interactions involving Group 11 elements should be designated as regium bonds [10] or coinage bonds. [13] Herein we report experimental and theoretical results that show that not only gold in neutral species, as mentioned above, but also gold in negatively charged species can function as an acceptor of electron density, namely, be a coinage-bond (CiB) donor.…”