Phenanthridine is the benzannulated version of the more well-known quinoline ligand fragment. Despite its promising electronic features, the inclusion of phenanthridine in ligands for transition metal coordination is currently underexplored. This work investigates the photophysical, spectroscopic, and electrochemical properties of transition metals complexes that contain the phenanthridine fragment in their ligand structure. Specifically, the complexes studied in this work are four-coordinate complexes of late transition metals – their structures range from tetrahedral to square planar, allowing us to examine the change in geometry as ligand structure changes. This document presents two projects. The first is an examination of the relationship between ligand Namido character and emission intensity in Zn(II) complexes. It includes the synthesis of three new Zn(II) complexes, the computational analysis of bonding, and the spectroscopic and computational investigation of the photophysical processes at work. The second project is a characterization of the Ni(II), Pd(II), and Cu(II) complexes of a new tetradentate NNNN diamido ligand. It presents the synthesis of the new ligand and its complexes, as well as the structural, spectroscopic, electrochemical, and computational analysis. Together, these projects demonstrate the versatility of the phenanthridine ligand fragment in coordination with late transition metals.