Alkali-metal ortho-hydroxyphenolates:: Syntheses and crystal structures from powder X-ray diffraction

Colorless and highly air- and moisture-sensitive powders of M[o-C6H4O(OH)] with M = K, Rb, or Cs have been synthesized from reaction mixtures of the appropriate alkali metal and catechol in thf. All compounds were structurally characterized by means of powder X-ray diffraction using the Rietveld profile refinement technique including restraints for the C-C/C-O bond distances and the C-C-C angles. The atomic arrangements of M[o-C6H4O(OH)] (K: monoclinic P2(1)/c; Rb/Cs: orthorhombic Pbcm) are characterized by polymeric chains of (1)(infinity)[M(1)([4])O(2)([2])eta(6)] units connected by hydrogen bonds, thereby making up layered structures similar to the one of catechol. The coordinatively unsaturated alkali metals are forming edge-sharing MO4 pyramids and exhibit asymmetrical eta(6)-interactions with the phenylene rings. The symmetry of the unit cells increases with increasing size of the cation, and this results in a decrease of the monoclinic angle from 118.5degrees (catechol) to 93.7degrees (K compound), eventually leading to orthorhombic cells for the Rb and Cs compounds.