Implications for the Design of Organic Ferromagnets Based Upon Hexaazaoctadecahydrocoronene

The molecular and electronic structures of [HOC]n, n = 0–4+, have been studied by a variety of experimental and theoretical techniques. The ground state structures for n = 0 and 4+ are closed shell systems. The structures for n = 1 + and 3+ are doublets and show Jahn-Teller distortions. The structure for n = 2+ in the solid is a Jahn-Teller distorted closed shell singlet. The Jahn-Teller distorted structures all resemble two cyanine dyes coupled by single C-C bonds. The 1:1 complex of [HOC]·+[TCNE]·− was synthesized following McConnell's model for ferromagnetism but the complex was found to be antiferromagnetic. A number of suggestions for designing triplet dications and dianions with degenerate orbitals based on benzene derivatives are presented following our experience with [HOC]n.