Chemical Structures from the Analysis of Domain-Averaged Fermi Holes. The Nature of Ga−Ga Bonding in PhGaGaPh^2- and (PhGaGaPh)Na₂

Abstract

The nature of the Ga−Ga bond in the naked dianion PhGaGaPh2- and its Na+-coordinated counterpart is discussed using the recently proposed formalism based on the analysis of domain-averaged Fermi holes. The analysis shows clearly that three electron pairs, i.e., two σ and one π, contribute to the Ga−Ga bonding interactions in the free dianion PhGaGaPh2- and in the sodium-complexed species (PhGaGaPh)Na2. The eigenvalues and the eigenvectors of the Fermi hole indicate, however, that the Ga−Ga bonding situation does not correspond to classical triple bonds and should not be interpreted using classical bonding models. The reason is that only one of the three electron pairs involved in Ga−Ga bonding, namely that contributing to the Ga−Ga π bond, corresponds to an “ordinary” shared electron pair bond in the sense of Lewis. The bonding interactions of the other two pairs are much more complex and have no classical counterparts. The eigenvalues and the eigenvectors of the latter Fermi holes cannot be considered as fully bonding, but they have partial lone-pair character. This is why the calculated bond orders yield values which are close to a weak double bond. Essentially the same bonding picture holds also for the Na+-coordinated species, but the coordination of sodium causes further weakening of the contributions of all three electron pairs to the Ga−Ga bonding. This weakening yields an effective reduction of the multiplicity of the Ga−Ga bond. The calculated bond order therefore has a value which is otherwise typical for single bonds.

On the Electronic Structure ofmer,trans‐[RuCl3(1H‐indazole)2(NO)], a Hypothetical Metabolite of the Antitumor Drug Candidate KP1019: An Experimental and DFT Study

“…The negative sign of this index is typical for three-center-twoelectron (3c-2e) bonding. [68][69][70]99,100] This result, together with the axial symmetry of the bonds in the array (indicated by the negligible ellipticity of the Ru-N3 and N3-O1 bonds), clearly implies that the bonding in the Ru-N3-O1 unit involves two 3c-2e bonds of π symmetry formed by the overlap of the d-p-p orbitals on individual atoms in the array. The remaining bond indices for Ru-Cl1, Ru-Cl2, and Ru-N2 indicate that the corresponding bonds have the character of simple σ dative bonds.…”

“…[98][99][100][101][102][103] Its principles are described in the original literature. [39][40][41] Especially interesting and chemically relevant information can be extracted from the holes defined by atomic domains resulting from Bader or Mulliken analysis, but more complex domains, formed by the union of several atomic domains, which correspond, for example, to certain functional groups or interesting molecular fragments, can be analyzed as well.…”

Electron pairing and chemical bonds: Pair localization in ELF domains from the analysis of domain averaged Fermi holes

“…[29][30][31][32][33][34] The domain-averaged Fermi holes can most straightforwardly be introduced by eq. (1) in which (r 1 ,r 2 ) and (r 1 ) are the pair and first order density, respectively, and the averaging (integration) is performed over the finite domain O.…”

Structure and bonding in binuclear metal carbonyls from the analysis of domain averaged Fermi holes. I. Fe2(CO)9and Co2(CO)8

“…This analysis was repeatedly shown to provide a simple and chemically appealing picture of the bonding in various molecules with complicated bonding pattern including metal-metal bonds [40][41][42] and it was thus of interest to see whether or to what extent it can help in revealing and clarifying the final picture of bonding in the most stable binuclear iron and cobalt carbonyls. In the remainder of the article we first briefly summarize the theory and the technical details of DAFH analysis, then present the results of the analysis of the electronic structure of Fe 2 (CO) 9 and of Co 2 (CO) 8 , respectively.…”