“Potassium Potassates” Based on Dihydrotriazinide Ligands: Syntheses, Crystal Structures, and Comparison with Other Alkali Metal Dihydrotriazinide Compounds

Abstract

AbstractA series of dihydro‐s‐triazinidopotassium complexes have been synthesised and structurally characterised by X‐ray diffraction. Two of them, the sesqui‐pyridine solvate 2 and the mono‐THF solvate 3, can be classified 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)−] anions are linked to K+ cations in polymeric, zig‐zag chain arrangements. Solvate 3 also possesses a unique RK coordination as a direct result of having fewer solvent ligands. DMSO analogue 4 deviates from this uniformity in adopting a centrosymmetric, dimeric (OK)2 ring structure featuring both terminal and bridging DMSO ligands. The dihydro‐s‐triazinidosodium tris(THF) solvate 5 is found to be a monomer. For comparative purposes, the metal‐free, parent triazine molecule 6 has also been subjected to an X‐ray crystallographic study: it displays a 1,2‐dihydro 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 bridge in the dimeric structure of the lithium bromide bis (THF) solvate 7, a suspected hydrolysis product from the reaction of dihydro‐s‐triazinidolithium 8 and magnesium bromide bis(ether) adduct.