Mass spectrometric study of the overheated vapor over Ni(II), Cu(II), and Zn(II) N,N′-ethylenebis(acetylacetoniminato) complexes

A mass spectrometric study of the overheated vapor over the complexes Ni(acacen), Cu(acacen), and Zn(acacen) (H₂acacen = N,N′-ethylenebis(acetylacetonimine)) has been carried out in the temperature range of 180–760°C. Irrespective of the degree of overheating, the vapor phases over all of these compounds contain no ions heavier than the molecular ion MO₂N₂C₁₂H₁₈]⁺. The existence of molecular ions in the overheated vapor in the double-chamber two-temperature effusion cell is evidence of the high thermal stability of the complexes. The onset temperature of the thermal decomposition of Ni(acacen), Cu(acacen), and Zn(acacen) is 690, 610, and 560°C, respectively. The way of fragmentation of the chelates under electron impact ionization depends on the nature of the metal.