3,5,7,9-Substituted Hexaazaacridines: Toward Structures with Nearly Degenerate Singlet-Triplet Energy Separations Peter Langer,*,||,‡ Shadi Amiri,§ Anja Bodtke,¶ Nehad N. R. Saleh,|| Klaus Weisz,# Helmar Go¨rls,⊥ and Peter R. Schreiner*,§ Institut fu¨r Chemie, UniVersita¨t Rostock, Albert-Einstein-Str. 3a, D-18059 Rostock, Germany, Leibniz-Institut fu¨r Katalyse e. V. an der UniVersita¨t Rostock, Albert-Einstein-Str. 29a, D-18059 Rostock, Germany, Institut fu¨r Organische Chemie, Justus-Liebig-UniVersita¨t Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany, Institut fu¨r Pharmazie, UniVersita¨t Greifswald, Friedrich-Ludwig-Jahn-Str. 17, D-17487 Greifswald, Germany, Institut fu¨r Biochemie, UniVersita¨t Greifswald, Felix-Hausdorff-Str. 18, D-17467 Greifswald, Germany, and Institut fu¨r Anorganische and Analytische Chemie, UniVersita¨t Jena, August-Bebel-Str. 2, 07740 Jena, Germany
[email protected];
[email protected] ReceiVed March 24, 2008
Toward the goal of preparing stable, neutral open-shell systems, we synthesized a novel series of p-phenylsubstituted 3,5,7,9-hexaazaacridine and 3,5,7,9-hexaazaanthracene derivatives. The effects of substitution on the molecular electronic properties were probed both experimentally and computationally [B3LYP/ 6-311G(d,p)//B3LYP/6-31G(d,p)]. While the experimentally prepared structures already have small (20-25 kcal/mol) singlet-triplet energy gaps, systems with even smaller (
