Synthesis of Tetrachalcogenide-Substituted Phenalenyl Derivatives: Preparation and Solid-State Characterization of Bis(3,4,6,7-tetrathioalkyl-phenalenyl)boron Radicals

We
report the synthesis and properties of a series of spiro-bis­(3,4,6,7-tetrachalcogenide-substituted-phenalenyl)­boron
salts and two of the corresponding tetrathioalkyl-substituted spiro-bis­(phenalenyl)­boron
radicals [tetrathiomethyl (10) and tetrathioethyl (11)] in which all of the active positions of the phenalenyl
(PLY) nucleus are functionalized. In the solid state, radicals 10 and 11 exist as a weak π-dimers due
to the steric congestion of the thioalkyl groups in the superimposed
PLY units. As a result, the spins are localized in the isolated (nonsuperimposed)
PLY rings, and the structure, magnetic susceptibility measurements,
and band structure calculations confirm that these PLY units are unable
to undergo strong intermolecular interaction as a result of the orientation
of the thioalkyl groups.