A Study of the Development of CVD Precursors ￥2-Synthesis and Properties of New Lead ￥a-diketonate Derivatives

摘要

To improve the volatility and stability of lead complexes, the principle of stabilization by saturating the metal coordination sphere by intramolecular coordination through a モ-diketonates with an ethereal group has was tested. Several new lead complexes with alkoxyalkyl-substituted モ-diketonates, Pb(R1C(O)CHC(O)(CH2)3OR2)2(Rl=t-Bu, Me, OMe, i-Pr, R2=Me, Et), or carboxylate, Pb(OC(O)(CH2)3OEt)2, were prepared by the reaction between Pb(OAc)2 and corresponding alkoxyalkyl-substituted モ-diketonates, and they were found to have a viscous liquid phase. The nature of the head (モ-diketonate or carboxylate) or tails and substituents of モ-diketonates appeared not to be important for the formation of the liquid phase. It is worth mentioning that Pb(OAc)2, which has limited use due to its low solubility, was successfully adopted as a starting material for the preparation of new lead complexes. Easy hydrolysis, reaction with HCl, and 13C NMR spectra indicated that tail portions were not coordinated to the metal as a copper derivative, Cu(t-BuC(O)CHC(O)(CH2)3OMe)2. All these complexes were not volatile enough for the MOCVD experiments, but a methyl derivative, Pb(MeC(O)CHC(O)(CH2)3OEt)2, showed some sublimation. The methoxy derivative, Pb(MeOC(O)CHC(O)(CH2)3OEt)2, was thermally unstable due to possible equilibrium between species coordinating with a keto oxygen atom and an ethereal atom of a methoxy group, which was confirmed by IR and 13C NMR spectra.