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.