Oxamate-based potassium–organic assembly with the uncommon binodal (6,12)-coordinated alb topology†

Herein, we report the design and crystal growth of the network of K₂H₂mpba (1) [H₄mpba = N,N′-1,3-phenylenebis(oxamic acid)], which exhibits the quite unusual (6,12)-connected alb topology. The characterization of 1 shows the following features: (i) the presence of deprotonated H₂mpba²⁻ moieties, (ii) thermal stability up to approximately 300 °C, and (iii) H₂mpba²⁻ acting as a 12-c molecular building block (MBB) and occupying the vertices of the double six-membered ring “d6R”. These rings combine with potassium ions, which fill the vertices of a trigonal prism. A discussion is provided on the role played by the type of metal centre (Mⁿ⁺, M = Mn, Ni, Co, Cu) and countercation [tetrabutylammonium (TBA⁺) or tetraethylammonium (TEA⁺)] in a series of structurally characterized Mⁿ⁺–H₂mpba²⁻ systems described in the literature.