Two Blatter Radicals Face-to-Face: A Constrained Diradical Architecture

Abstract

Cofacial arrangement of two Blatter radicals enforced by the peri-naphthalene scaffold represents a new approach to stable diradicals with strong through-space interactions. Two stereoisomers of the naphthalene-diradicals, anti and syn, are investigated by XRD, VT-EPR, UV–vis, electrochemical, kinetic, and DFT methods. In solutions, both stereoisomers exist as open-shell singlets with ΔE_S-T = −3.1 and −3.8 kcal mol^–1, respectively. The anti isomer was resolved into enantiomers and converts to syn with ΔG^‡₂₉₈ = 23.6(8) kcal mol^–1.