Substituted Carbonyl-Linked Bis(Dioxolene) Complexes: Is A Carbonyl An Effective Ferromagnetic Coupler?

Abstract

Bis-semiquinone complexes have been successfully synthesized and characterized to give triplet ground states from the use of typical coupling units. The typical coupling unit ethenylidene has produced compounds with ground state triplets, i.e. trimethylenemethane (TMM). Upon substitution of oxygen onto the ethenylidene coupler of TMM, to give oxyallyl, the degeneracy of the two non-bonding molecular orbitals is broken, which allows configuration interaction to take place between the ground configuration singlet and the excited configuration singlet. Therefore, it is conceivable that oxyallyl would produce a ground state singlet but computational methods have computed a triplet ground state.

We propose to use oxyallyl as the linker between two semiquinones to produce a ground state triplet. Previous work using oxyallyl as the linker was unsuccessful in producing the bis-semiquinone complex without the use of an oxidizing agent, which eventually decomposed the complex. We will use the same semiquinone backbone but substitute a more electron-donating group, methoxy, onto the phenyl ring increasing the oxidizability to produce the bis-semiquinone complex. Another approach in increasing the oxidizability is to use a less electronegative metal, manganese, on the complex. Once the bis-semiquinone is synthesized then characterization will enable us to determine the ground state of the bis-semiquinone and the type of spin coupling taking place between the two electrons.