''Potassium potassates'' based on dihydrotriazinide ligands: syntheses, crystal structures, and comparison with other alkali metal dihydrotriazinide compounds

Clegg, W and Elsegood, M R J and Horsburgh, L and Mulvey, Robert and Ross, M J (1997) ''Potassium potassates'' based on dihydrotriazinide ligands: syntheses, crystal structures, and comparison with other alkali metal dihydrotriazinide compounds. Chemische berichte, 130 (5). pp. 621-631. ISSN 0009-2940 (https://doi.org/10.1002/cber.19971300513)

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Abstract

A 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.