Solutions of complex copper salts in low-transition-temperature mixture (LTTM)Electronic supplementary information (ESI) available. See DOI: 10.1039/c5dt02941d

The structure and properties of diethanolamine complexes of copper( ii ) triflates dissolved in an excess of diethanolamine (DH 2 ) were studied. The copper containing substance was found to be a solution of copper( ii ) complex salt [Cu 2+ DH 2 (DH − )]OTf − in LTTM composition [(DH 2 ) 4 H + ](OTf − ), where LTTM = low-transition-temperature mixture, OTf − = triflate anion. According to the EXAFS data, the coordination number of copper( ii ) atoms in solution does not exceed four. Addition of even negligible amounts of acid significantly changes DH 2 volatility and decomposition conditions. Ionic liquids (IL) and low-transition-temperature mixtures (LTTM) based on amine alcohol were prepared and solitonic proton charge transfer proposed to occur in LTTM.