figshare
Browse
ic8b02416_si_001.pdf (1.48 MB)

Non-Innocent Base Properties of 3- and 4‑Pyridyl-dithia- and Diselenadiazolyl Radicals: The Effect of N‑Methylation

Download (1.48 MB)
journal contribution
posted on 2018-10-11, 14:07 authored by Anni I. Taponen, Joanne W. L. Wong, Kristina Lekin, Abdeljalil Assoud, Craig M. Robertson, Manu Lahtinen, Rodolphe Clérac, Heikki M. Tuononen, Aaron Mailman, Richard T. Oakley
Condensation of persilylated nicotinimideamide and isonicotinimideamide with sulfur monochloride affords double salts of the 3-, 4-pyridyl-substituted 1,2,3,5-dithiadiazolylium DTDA cations of the general formula [3-, 4-pyDTDA]­[Cl]­[HCl] in which the pyridyl nitrogen serves as a noninnocent base. Reduction of these salts with triphenylantimony followed by deprotonation of the intermediate-protonated radical affords the free base radicals [3-, 4-pyDTDA], the crystal structures of which, along with those of their diselenadiazolyl analogues [3-, 4-pyDSDA], have been characterized by powder or single-crystal X-ray diffraction. The crystal structures consist of “pancake” π-dimers linked head-to-tail into ribbonlike arrays by η2-S2---N­(py) intermolecular secondary bonding interactions. Methylation of the persilylated (iso)­nicotinimide-amides prior to condensation with sulfur monochloride leads to N-methylated double chloride salts Me­[3-, 4-pyDTDA]­[Cl]2, which can be converted by metathesis into the corresponding triflates Me­[3-, 4-pyDTDA]­[OTf]2 and then reduced to the N-methylated radical triflates Me­[3-, 4-pyDTDA]­[OTf]. The crystal structures of both the N-methylated double triflate and radical triflate salts have been determined by single-crystal X-ray diffraction. The latter consist of trans-cofacial π-dimers strongly ion-paired with triflate anions. Variable temperature magnetic susceptibility measurements on both the neutral and radical ion dimers indicate that they are diamagnetic over the temperature range 2–300 K.

History