Representative examples of tetradentate ligands that appear in seesaw and planar configurations. The skeleton of each macrocycle is shown, with metal-coordinating atoms highlighted with translucent circles colored by coordinating atom identity: blue for N and red for O. Representative structures are shown with their CSD refcodes, metal, and assigned symmetry class in bold. Colors in structures are as follows: white for H, gray for C, blue for N, red for O, cyan for F, yellow for S, light green for Cl, purple for Mn, pink for Co, green for Ni, light blue for Zr, and aqua for W.