Key-to-Lock Halogen Bond-Based Tetragonal Pyramidal Association of Iodonium Cations with the Lacune Rims of Beta-Octamolybdate

The structure-directing “key-to-lock” interaction of double -(I(III))-hole donating iodonium cations with the O-flanked pseudo-lacune rims of [β-Mo8O26]4– gives halogen-bonded iodonium–beta-octamolybate supramolecular associates. In the occurrence of their tetragonal pyramidal motifs, deep and broad -(I(III))-holes of a cation recognize the molybdate backbone, which provides an electronic pool localized around the two lacunes. The halogen-bonded I∙∙∙O linkages in the structures were thoroughly studied computationally and classified as two-center, three-center bifurcated, and unconventional “orthogonal” I∙∙∙O halogen bonds. In the latter, the O-atom approaches orthogonally the C–I(III)–C plane of an iodonium cation and this geometry diverge from the IUPAC criteria for the identification of the halogen bond