Main Group metal ion coordination chemistry: factors influencing solid state structures of Group 1 complexes

Abstract

Analysis of published structures of alkali metal ion complexes of the isomeric 2-, 3- and 4-nitrophenoxides has been applied in an endeavour to identify the forces operative in determining the coordination modes adopted. Aside from a single instance in which hydrogen-bonding appears to exclude direct coordination, all three nitrophenoxide ligands exhibit the capacity to interact as unidentate, chelating and/or bridging species. In variously hydrated complexes, different balance points are reached in the competition between hydrogen-bonding and direct coordination. While stacking of the aromatic units is commonly observed, there is limited evidence to assign this to other than dispersion force interactions. With the heavier alkali metal ions, cation-π interactions can be detected in some cases.