POTASSIUM POTASSATES BASED ON DIHYDROTRIAZINIDE LIGANDS - SYNTHESES, CRYSTAL-STRUCTURES, AND COMPARISON WITH OTHER ALKALI-METAL DIHYDROTRIAZINIDE COMPOUNDS

A series of dihydro-s-triazinidopotassium complexes have been synthesi sed and structurally characterised by X-ray diffraction. Two of them, the sesqui-pyridine solvate 2 and the mono-THF solvate 3, can be class ified in formal terms as ''potassium potassates'' in conforming to the structural pattern established previously for the sesqui-THF solvate 1, the first reported 'ate of this type. Formally complex [(R2K)(-)] a nions are linked to K+ cations in polymeric, zig-zag chain arrangement s. Solvate 3 also possesses a unique RK coordination as a direct resul t of having fewer solvent Ligands. DMSO analogue 4 deviates from this uniformity in adopting a centrosymmetric, dimeric (OK)(2) ring structu re featuring both terminal and bridging DMSO ligands. The dihydro-s-tr iazinidosodium tris(THF) solvate 5 is found to be a monomer. For compa rative purposes, the metal-free, parent triazine molecule 6 has also b een subjected to an X-ray crystallographic study: it displays a 1,2-di hydro ring setup as opposed to the 1,4-dihydro alternative existing in the metallo examples. Triazine 6 is also found to form a N-H ... Br b ridge in the dimeric structure of the lithium bromide bis (THF) solvat e 7, a suspected hydrolysis product from the reaction of dihydro-s-tri azinidolithium 8 and magnesium bromide bis(ether) adduct.