Demonstrating the Importance of Hydrogen Bonds through the Absence of Hydrogen Bonds

Only recently have noncovalent interactions (notably hydrogen bonds) been used in deliberate strategies for connecting coordination complexes into extended networks. The significance of such intermolecular forces is further demonstrated in this structural study of four different 1,8-bis(dimethylamino)naphthalenium, [HDMAN]+, halo-metalates. The cation is unable to engage in any strong hydrogen-bond interactions and the resulting structures do not display any repeating topologies or motifs. This is in stark contrast with previous work on halo-metalates with cations capable of forming directional hydrogen bonds, e.g., 4,4-bipyridinium(2+); those structures contain charge-assisted MX...HN+ interactions between anions and cations resulting in well-defined 1-D and 2-D motifs. The [HDMAN]+ structures presented here, however, are determined by close-packing principles; no repeating motifs are observed, which emphasizes that hydrogen bonding is an effective tool for directed assembly of substantial coordination c...