Synthesis and structural characterization of heavier group 1 methyl tetrazolate complexes: New bridging coordination modes of the tetrazolate ligand

A series of sodium, potassium, rubidium, and cesium complexes of methyl tetrazolate was prepared and structurally characterized. Treatment of methyl tetrazole (MetetzH) with the group 1 hydroxides in water at ambient temperature afforded Na(Metetz)(H2O)2 (92%), K(Metetz) (92%), Rb(Metetz) (97%), and Cs(Metetz) (97%) as colorless solids after workup. These complexes were characterized by spectral and analytical methods, thermogravimetric analysis, and by X-ray crystallography. Na(Metetz)(H2O)2 adopts a structure that consists of approximately octahedrally coordinated sodium ions that form infinite chains built up by two μ2-aqua ligands and two μ2-N1,N2-tetrazolate ligands between each sodium atom. The aqua ligand hydrogen atoms engage in hydrogen bonding with uncoordinated nitrogen atoms to hold the chains together. K(Metetz) and Rb(Metetz) are isostructural, with eight-coordinate metal ions and two metal–nitrogen bonds per nitrogen atom in each Metetz ligand. Cs(Metetz) has 10-coordinate cesium ions with two cesium–nitrogen bonds to two of the Metetz ligand nitrogen atoms and three cesium–nitrogen bonds to the other two nitrogen atoms. K(Metetz), Rb(Metetz), and Cs(Metetz) exhibit new coordination modes for the tetrazolate ligand.

The group 1 methyl tetrazolate complexes Na(Metetz)(H2O)2, K(Metetz), Rb(Metetz), and Cs(Metetz) were prepared by deprotonation of methyl tetrazole by the metal hydroxides in water, and were characterized with respect to their spectral properties and thermal behavior. The X-ray crystal structures were also determined, and reveal several new coordination modes for the tetrazolate ligand.Figure optionsDownload as PowerPoint slide