Synthesis and characterization of zinc AP-MOCVD precursors and their utility in the growth of ZnO

A novel β-ketoimine, 4-N-(n-butylamino)-3-penten-2-one (1), and β-enaminoester, Ethyl 3-N-(isopropylamino)-2-butenoate (2), were synthesized by the reaction of the 2,4-pentanedione or ethyl 3-oxo butanoate with the n-butyl and isopropyl amine, respectively. The isolated free ligands 1 and 2 were reacted with diethylzinc to afford Zn(CH₃C(NCH₂CH₂CH₂CH₃)CHCOCH₃)₂ (3) and Zn(CH₃C(NCH(CH₃)₂)CHC(O)OCH₂CH₃)₂ (4) respectively. The isolated zinc complexes, 3 and 4, were characterized by elemental analysis, NMR, and MALDI-TOFMS. The molecular structure of 3 and 4 were determined via single crystal X-ray diffraction which revealed both compounds to be four coordinate, monomeric and homoleptic in the solid state. TG analysis showed the air stable compounds to be thermally robust as they both sublimed in a one-step process at atmospheric pressure. The compounds were utilized in the growth of ZnO via AP-MOCVD in the absence of additional oxidant. The carbon content of the film grown from 3 as determined by XPS was 26.2% while that of the film grown by 4 was 8.71%.