Chalcogen bond activation in cation radical salts of naphthalene peri-diselenides with S = 5/2 magnetic anions

Abstract

The activation of strong σ-holes in the oxidized form of 2,7-dimethoxynaphthalene peri-diselenide (1) is demonstrated in its radical salts with magnetic (S = 5/2) FeX4- anions as well as their diamagnetic analogs GaX4- (X = Cl, Br). All four salts exhibit short and directional Se•••X chalcogen bonding (ChB) interactions, together with strong dimerization of the radical species into dicationic dimers along the stacks of 1+• . Magnetic analysis highlights the presence of antiferromagnetic interactions between paramagnetic FeX4- anions and reveals long-range antiferromagnetic order with T_N = 5.9 K only in the FeBr4- salt, attributable to the short Br•••Br distances induced by ChB interactions.