Salts with the [NiBr3(L)]− complex anion (L = 1-methylimidazole, 1-methylbenzimidazole, quinoline, and triphenylphosphane) and low melting points: A comparative study

Four new salts with low melting points of the general formula (EMIm)[NiBr3(L)] (EMIm = 1-ethyl-3-methyl-imidazolium) with L = N-methylimidazole (NMIm), N-methylbenzimidazole (NMBIm), quinoline (quin), and triphenylphosphane (PPh3) were prepared and characterized by means of elemental analysis, IR, NMR, and UV–vis spectroscopy. Magnetic properties were deduced from NMR data using the EVANS method. All four compounds are paramagnetic with magnetic moments close to the spin-only values of the tetrahedrally coordinated Ni(II) ion. Molecular and crystal structures were obtained by single crystal X-ray diffraction investigations. Melting points are determined to have values between 110 °C, (EMIm)[NiBr3(NMIm)] and 168 °C, (EMIm)[NiBr3(PPh3)]. They exceed the maximum temperature required to call them “Ionic Liquids”. Decomposition has been found to occur above 200 °C and to depend largely on the type of organic ligand coordinated to Ni(II).

Graphical abstractFour new salts with low melting points of the general formula (EMIm)[NiBr3(L)] L = organic N- or P-ligand) were prepared and characterized by means of elemental analysis, IR, NMR, and UV-vis spectroscopy. All four compounds are paramagentic and the Ni(II) atoms are distorted tetrahedrally coordinated. Molecular and crystal structures were obtained by single crystal X-ray diffraction investigations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Four new salts with the EMIm cation and heteroleptic complex anions of Ni(II) with bromido and N- or P-based organic ligands were synthesized. ► The structures of the new coordination compounds were determined by single crystal X-ray diffraction. ► Spectroscopic, magnetic and especially melting and decomposition temperatures were determined.