Structural characterization of the 1-metallo-2-t-butyl-1,2-dihydropyridyl rubidium and caesium complexes

With recent reports of alkali metal amides used in homogeneous catalytic chemistry where the reactivity down group one is dependent on identity, esoteric rubidium and caesium are finding new admirers amongst chemists who usually study lithium, sodium, potassium utility amides. Here, as a forerunner to their exploitation catalysis, we report X-ray crystallographic NMR solution structures 1-metallo-2-t-butyl-1,2-dihydropyridyl (DHP) complexes caesium, thereby completing homologous series. Crystallized monosolvated {[Rb(tBuDHP)·THF]2}∞ hemisolvated {[Cs(tBuDHP)]2·THF}∞, both form spectacular supramolecular structures. While each shares plethora metallo-π-contacts with DHP anion, subunits differ. The former dimerizes ‘slipped’ fashion via interactions between symmetrically-equivalent Rb centres π-system adjacent ring, but latter has distinct Cs within its dinuclear subunit, engaging σ-bonding two tBuDHP anions, whereas other binds more side-on ring.