Visualizing the molecular wave function in σ-coordinated complexes

Abstract

The π-complex theory developed by Michael J. S. Dewar in 1949 has had its most profound impact as part of the Dewar-Chatt-Duncanson model, a seminal and foundational contribution to the field of organometallic chemistry. Over time it has demonstrated its utility in systems far from those originally envisaged, including σ-coordinated metal-complexes. This latter application is notable due to Dewar's original skepticism that his π-complex theory could be extended to σ-bonds. Separately it has previously been demonstrated that a one-electron wave function. can be shown to satisfy an exact one-electron Schrödinger equation describing the motion of the single electron in the average field of the remaining electrons. To celebrate the centenary of his birth this paper seeks to demonstrate that σ-coordinated metal-complexes present a perfect system to exemplify both the utility of the one-electron wave function and the power of the π-complex theory.

Topological Analysis of the Electron Density of Molecules with Bridging Hydrogens To Tackle the Chemical Structure Monolith

“…[17] However dividing the gradient norm of the electron density by 1(r) yields a simple real-space function for the display of both strong and weak interactions. [18,19] The isosurface map in Figure 7 shows how this normalized gradient function succeeds in detecting C-H/M agostic interactions as well as characterizing traditional 2-electron covalent bonds. In addition to strong attractions (shown in blue) this analysis also highlights weaker van der Waals interactions (green) as well as repulsions due to steric effects (red).…”

“…QTAIM analysis of the DFT‐generated ρ(r) at the experimental geometry does not yield a critical point between the metal and the agostic hydrogen because the interaction is too weak to allow for characterization of a bond path [17] . However dividing the gradient norm of the electron density by ρ(r) yields a simple real‐space function for the display of both strong and weak interactions [18,19] . The isosurface map in Figure 7 shows how this normalized gradient function succeeds in detecting C‐H/M agostic interactions as well as characterizing traditional 2‐electron covalent bonds.…”