New bis-o-iminosemiquinonate aluminium(III) complexes

• The first aluminium complexes based on sterically hindered o-iminobenzosemiquinone
• Pentacoordinated complexes with two radical-anion ligands
• The strong antiferromagnetic coupling between spins of o-iminosemiquinonate radicals

The first aluminium(III) complexes based on sterically hindered 4,6-di-tert-butyl-N-(2,6-di-iso-propyl-phenyl)-o-iminobenzoquinone (imQ) of general formula imSQ2AlR (where imSQ — is a radical anion of imQ, R = I (1), NCS (2) and N3 (3)) were synthesized. Compounds 1–3 demonstrate biradical X-band EPR spectra in frozen toluene matrix. The crystalline samples of 1–3 were characterized using magnetic susceptibility measurements. The antiferromagnetic coupling between spins of o-iminosemiquinonate radicals in 1–3 is predominant and, as the result, the singlet ground state for pentacoordinated biradical compounds is observed. The molecular structures of all the complexes obtained have been established by the single crystal X-ray analysis.

The first aluminium(III) complexes based on sterically hindered o-iminobenzosemiquinone were synthesized. Compounds have a biradical character. The antiferromagnetic coupling between spins of o-iminosemiquinonate radicals is predominant and the singlet ground state for pentacoordinated biradical compounds is observed.Figure optionsDownload as PowerPoint slide