Coordination capabilities of a novel organic polychlorotriphenylmethyl monosulfonate radical

The treatment of alpha-H-p-H-PTM (PTM = polychlorotriphenylmethane) with oleum 65% followed by deprotonation and oxidation leads to the isolation of a novel pure organic radical PTMSO3H x 3 H2O x 0.5 hexane (2). The X-ray diffraction of 2 reveals a layered structure with disordered H2O molecules between facing sulfonic acid groups. We have explored the coordination abilities of the sulfonate derivative using different metals. The treatment of 2 with mild bases yields the sulfonate radical PTMSO3Na x H2O (3). On the other hand, the new compound [Cu(py)2(H2O)4](PTMSO3)2 x 2 H2O x 2 EtOH (4) has been crystallized using Cu(II) as the metallic counterion in the presence of pyridine. The structure reveals a solvent-separated ion-pair-type compound, with no direct coordination of the metal ion with the sulfonate group, and the formation of organic layers between layers of transition metal complexes. This situation has been overcome by favoring the stabilization of the sulfonate group over the Cu(II) center by changing the pyridine ligand to cyclam. This has led to compound [Cu(cyclam)](PTMSO3)2 x 6 EtOH (5a), in which the sulfonate group acts as a monodentate axial ligand for the Cu(II) center. We have observed a single-to-single crystal rearrangement from 5a to [Cu(cyclam)](PTMSO3)2 (5b) because of the loss of the solvent of crystallization, without significant modification of the metal coordination environment. All species have been structurally and magnetically characterized, and the magnetic coupling between the organic radicals and the metal paramagnetic centers is discussed.