Novel Hydrogen-Bridged Molecular Aggregates: Design, Structures and Potential Calculations

Abstract

Despite of well over 10000 entries in the Cambridge Structural Data Base, still numerous novel aspects of hydrogen bonding in single crystals are discovered. Topics reported comprise: (i) the use of nonprotonable anions to prepare prototype salts with NH⊕N bridges, partly accompanied by both structure and color changes (chemical mimesis), (ii) cooperative effects in H-bridged dimers and polymers, (iii) the shortest hydrocarbon to oxygen bridge reported so far in (O₂N)₃CH…OR₂, (iv) triclinic and orthorhombic polymorphs of dipyridylamine dimers or isomorphic crystals of ditosyl-pphenylenediamine, which due to an H bridge enforced packing motif contain within identical unit cells solvent molecules as different as acetone or tetrahydrofurane, (v) chloride hydrates in single crystal lattice cavities of nitrogen heterocycles. All structures determined are rationalized by extensive energy hypersurface calculations.