Together, direct (UPS) and inverse photoemission spectroscopy (IPES) provide a picture of the entire band structure of a material. 30 Unlike PES, IPES has enjoyed relatively few applications in molecular chemistry. Simpler tools such as electrochemistry and optical spectroscopy have typically afforded the necessary insight into molecular excited states. That said, IPES does provide unique insight. While electrochemical reduction potentials afford information on the energetics of successive reductions (i.e., electron additions), IPES probes the energetics of unoccupied molecular orbitals (MOs) one at a time. To determine the potential usefulness of IPES in a coordination chemistry context, we carried out a direct and inverse photoemission study of coinage metal mesotriphenylcorrole complexes, M[TPC] (M = Cu, Ag, Au; Scheme 1). The solution-phase reduction potentials of the three complexes vary from -0.20 V for Cu[TPC] through -0.86 V for Ag[TPC] to -1.38 V for Au[TPC] (all vs. the saturated calomel electrode), indicating dramatically falling energies of the lowest unoccupied MO (LUMO) from Cu through Ag to Au. The electronic structures of the complexes also vary from a noninnocent Cu II -Cor •2-description for Cu[TPC] to an essentially innocent M III -Cor 3-description for Ag[TPC] 40 and Au[TPC]; 50,51,52,53,54,55,56,57,58,59,60,61 these differences are schematically summarized in Figure . We shall see that IPES-derived picture of unoccupied states is eminently consistent with that derived from electrochemistry and other spectroscopic methods (such as X-ray absorption spectroscopy ). Moreover, combining the UPS and IPES data give access to the solid-state band gap (Eg), a value that can be compared to the electrochemical HOMO-LUMO gap (Eox-red), which is the difference between solution-phase oxidation and reduction potentials obtained from electrochemical measurements. 70 Herein, all samples were prepared under ultra-high vacuum (UHV) conditions. The M[TPC] samples were sublimed from an Al2O3 crucible heated by a tungsten filament. For Cu-and Au[TPC], a sublimation temperature of 250 °C was used, while a lower temperature of 200 °C was used for Ag [TPC]. UPS and IPES experiments were performed in two distinct instruments. For IPES, the substrate was cut from a Si wafer covered by an amorphous carbon thin film. For UPS, an Au(111) film grown on a mica substrate was used. The cleanliness of the substrate and the thickness of the sample film were both probed by X-ray photoelectron spectroscopy and Auger electron spectroscopy. The film thickness used was large enough so to avoid any issue due to interface interaction or band bending.