Diindeno[2,1‑b:2′,1′‑h]biphenylenes: Syntheses, Structural Analyses, and Properties

A series of diindeno­[2,1-b:2′,1′-h]­biphenylenes with open-shell singlet ground states and interesting properties were prepared. The studied compounds consist of p-quinodimethane moieties, which suffer from geometric perturbation with bond angles of around 90°. The substituent effects on structural parameters, local aromaticity, and properties were systematically explored.