Toward Activity Prediction: Unveiling the Role of Intra/Intermolecular Balance in Fe–N–C Catalysts for Hydrogen Evolution

Metal–nitrogen–carbon (M–N–C) molecular catalysts attract attention for the hydrogen evolution reaction (HER) owing to their well‐defined active sites and structural tunability. However, previous studies prioritize intramolecular regulation, leaving the cooperative role of intermolecular interactions insufficiently understood. Herein, we design and synthesize three Fe–N–C molecules, including iron phthalocyanine (FePc) and two pyridinic‐N–incorporated FePc derivatives (FeTAP and FeOM), and elucidate their structure–activity relationships via integrated structural and electronic analyses to enable performance prediction. We demonstrate that pyridinic‐N incorporation drives Fe centers from Fe 2+ to a more positively charged Fe 2+δ state, creating an “oxidation‐state reservoir” that promotes rapid electron transfer and proton adsorption for HER. Moreover, overall activity is governed by the balance between intramolecular electronic regulation and intermolecular π–π interactions: FePc is limited by weak intramolecular regulation; FeOM exhibits strong intramolecular effects but weakened intermolecular coupling; and FeTAP optimizes this balance, delivering the highest HER activity. Electrochemical measurements corroborate the predictions and further reveal that an optimal level of pyridinic‐N achieves the intra‐/intermolecular balance, thereby accelerating HER kinetics on these Fe–N–C catalysts. These findings provide a predictive basis and a clear design guideline centered on intra‐/intermolecular balance for molecular electrocatalysts.