Mass spectrometric study of the overheated vapor over lanthanide dipivaloylmethanates Ln(thd) 3 (Ln = Nd, Er, Yb, Lu)

A mass spectrometric study of the overheated vapor over neodymium, erbium, ytterbium, and lutetium dipivaloylmethanates has been carried out. The mass spectra of these compounds depend significantly on the degree of overheating. This fact can be interpreted in terms of the variation of the concentration and chemical composition of metal-containing molecular species with vapor temperature. As the vapor temperature is raised from 200 to 700°C, the intensity of the molecular ion [M(thd)3]+ decreases relative to the [M(thd)2]+ ion intensity by approximately one order of magnitude for M = Er, Yb, and Lu and by two orders of magnitude for M = Nd. This finding is evidence in favor of the thermal decomposition of the lanthanide tris(dipivaloylmethanates) occurring via a two-step mechanism initially yielding the M(thd)2 radical.