Oligomeric and polymeric organizations of potassium salts with compartmental Schiff-base complexes as ligands

Abstract

The complexation of K⁺ ions by mono-metallated bicompartmental Schiff-base complexes in double-decker-type arrangement was found to yield various supramolecular organizations as a function of the associated anions. A series of four [{LMK}_n{LM}]ⁿ⁺ aggregates with n = 1, 2, 3, and ∞ are reported (M = Ni²⁺ or Cu²⁺; L stands for the Schiff-base). Assembling KNCS with the metallo-ligand led to 1-D [L^3CCuK(NCS)]_n whereas KOH yielded the simplest possible case, [(L^2CNi)₂KOH]·H₂O. Oligomeric organizations containing two or three alkali ions were achieved in the presence of the [Mo(NCS)₆]³⁻ anion. Such stacks have not been found with Na²⁺ due to a different local arrangement with the metallo-ligand. The crystal packing for [(L^2CNi)₂KOH]·H₂O yields an open-framework structure with a void volume of 20%.