AbstractThe emergence of conductive 2D and less commonly 3D coordination polymers (CPs) and metal–organic frameworks (MOFs) promises novel applications in many fields. However, the synthetic parameters for these electronically complex materials are not thoroughly understood. Here we report a new 3D semiconducting CP Fe₅(C₆O₆)₃, which is a fusion of 2D Fe‐semiquinoid materials and 3D cubic Fe_x(C₆O₆)_y materials, by using a different initial redox‐state of the C₆O₆ linker. The material displays high electrical conductivity (0.02 S cm⁻¹), broad electronic transitions, promising thermoelectric behavior (S²σ=7.0×10⁻⁹ W m⁻¹ K⁻²), and strong antiferromagnetic interactions at room temperature. This material illustrates how controlling the oxidation states of redox‐active components in conducting CPs/MOFs can be a “pre‐synthetic” strategy to carefully tune material topologies and properties in contrast to more commonly encountered post‐synthetic modifications.