Alkali metal complexes based on bisheterocyclomethanide ligands

Abstract

A series of new alkali metal complexes containing deprotonated bisheterocyclomethanide were synthesised and the potassium derivatives were exposed to hydrolysis.

A series of new alkali metal complexes containing deprotonated bisheterocyclomethanide were synthesised and structurally as well as spectroscopically characterised. Starting from the neutral bis-(benzoxazol-2-yl)methane ({NCOC 6 H 4 } 2 CH 2 ), the complexes were obtained by facile deprotonation of the methylene bridge with n butyllithium ( n BuLi) or potassium hydride. Each of the resulting complexes [({NCOC 6 H 4 } 2 CH)Li(OEt 2 ) 2 ] ( 1 ), [({NCOC 6 H 4 } 2 CH)K(thf)] n ( 2 ) and [({NCOC 6 H 4 } 2 CH)K(18-crown-6)] n ( 3 ) ( n → ∞) was analysed in the solid state by single crystal X-ray diffraction and in solution by various NMR techniques. All the compounds show a nearly planar ligand with the alkali metal ion chelated by the two ring nitrogen atoms of the conjugated C 3 N 2 moiety. Furthermore, water NMR titration experiments revealed that both compounds 2 and 3 are examples of water-stable reactive organo potassium compounds. Due to their hydrolysis stability, these complexes are under further investigations in deep eutectic solvents.