Solid-State Properties of Hexaazatriphenylenehexacarbonitrile HAT(CN)6 .- Radical Anions in Crystalline Salts Containing Cryptand(M+ ) and Crystal Violet Cations.
Crystalline {Cryptand[2.2.2](Na+ )}{HAT(CN)6 .- }⋅0.5C6 H4 Cl2 (1), {Cryptand[2.2.2](K+ )}{HAT(CN)6 .- } (2), (CV+ ){HAT(CN)6 .- } (3), and (CV+ ){HAT(CN)6 .- }⋅2C6 H4 Cl2 (4) salts (where CV+ is the crystal violet cation) containing hexaazatriphenylenehexacarbonitrile radical anions have been obtained. The solid-state molecular structure as well as the optical and magnetic properties of HAT(CN)6 .- are studied. The formation of HAT(CN)6 .- in 1-4 leads to the appearance of new bands in the visible range, at 694 and 740 nm. The HAT(CN)6 .- radical anions have spin state S=1/2 and are packed in one-dimensional stacks containing the {HAT(CN)6 .- }2 dimers alternated with weaker interacting pairs of HAT(CN)6 .- in 1 and nearly isolated {HAT(CN)6 .- }2 dimers in 2. The {HAT(CN)6 .- }2 dimers are diamagnetic in 1 but they effectively mediate one-dimensional antiferromagnetic coupling of spins within the stacks with moderate exchange interaction of J/kB = -80 K. The behaviour of salt 2 is described by a singlet-triplet model for the {HAT(CN)6 .- }2 dimers with an energy gap of 434(±7) K. Magnetic behaviour of both salts agree well with the data of extended Hückel calculations. Salts 3 and 4 contain isolated stacks of alternated HAT(CN)6 .- and CV+ ions, and in this case, nearly paramagnetic behaviour is observed with Weiss temperatures of -1 and -7 K, respectively. Narrow Lorentzian EPR signals with g = 2.0033-2.0039 were found for the HAT(CN)6 .- radical anions in 1 and 4 but in solution g-factor shifts to 1.9964. The electronic structure of HAT(CN)6 .- is analysed based on X-ray diffraction data for 2, showing a Jahn-Teller distortion of the radical anion that reduces the symmetry from D3h to Cs and splits the initially degenerated LUMOs.
['Konarev|Dmitri V|DV|http://orcid.org/0000-0002-7326-8118', 'Khasanov|Salavat S|SS|', 'Kuzmin|Alexey V|AV|', 'Mikhailenko|Maxim V|MV|', 'Otsuka|Akihiro|A|http://orcid.org/0000-0002-3141-0702', 'Yamochi|Hideki|H|http://orcid.org/0000-0002-0127-6530', 'Kitagawa|Hiroshi|H|http://orcid.org/0000-0001-6955-3015', 'Lyubovskaya|Rimma N|RN|']
optical and magnetic properties Jahn-Teller distortions crystal structures reduction singlet-triplet transitions