Oxygenated N-Confused Porphyrins: Structural Elucidation and Distinct Vanadium(IV) Coordination Motifs

High Resolution Image Download MS PowerPoint Slide N-Confused porphyrinoids exhibit unusual structural and electronic properties arising from pyrrole inversion, yet the controlled oxygenation of these macrocycles remains underdeveloped because competing pathways often generate complex mixtures. Here, we identify a stepwise oxygenation sequence associated with vanadium metalation of an N-confused porphyrin (NCP) framework, providing access to structurally defined oxygenated NCP derivatives and their vanadium complexes. The lactam-containing NCP 3-oxo- H 2 PFNCP ( 3 ) was isolated as a minor coproduct in Lindsey’s N-confused porphyrin synthesis protocol using CF 3 SO 3 H as the acid catalyst. Subsequent reaction with vanadyl acetylacetonate afforded the free-base 3,21-dioxygenated NCP 3,21-dioxo- H 3 PFNCP ( 4 ) together with two distinct vanadium(IV) complexes, V(═O)(OH)(3-oxo-PFNCP) ( 5 ) and [ n -Bu 4 N][V(OH)(3,21-dioxo-PFNCP)] − ( 6 ). Single-crystal X-ray diffraction established that 6 adopts an unusual intramolecular V–O–C chelation motif arising directly from macrocycle oxygenation. UV–vis, NMR, HRMS, EPR, and electrochemical studies further revealed clear differences between 5 and 6 in their electronic structures and coordination environments. Both complexes mediate hydrogen peroxide-driven oxidation of cyclohexene and thioanisole, with 6 giving higher yields of the quantified cyclohexene oxidation products and higher selectivity for sulfone formation in thioanisole oxidation. These results demonstrate that controlled oxygenation of N-confused porphyrins can generate unusual vanadium coordination motifs with differentiated oxygen-transfer reactivity.