Barium β-ketoiminate complexes containing appended ether "Lariats". Synthesis, characterization, and implementation as fluorine-free barium MOCVD precursors

Douglas L. Schulz, Bruce J. Hinds, Deborah A. Neumayer, Charlotte L. Stern, Tobin J Marks

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Abstract

The synthesis and characterization of six volatile fluorine-free barium coordination complexes based upon encapsulating β-ketoiminate ether/polyether ligation and having the general formula Ba(RCOCHC(NR′)R″)2 (R = tert-butyl; R′ = CH2CH2OCH3, -(CH2CH2O-)2CH3> -(CH2CH2O-)3CH2CH3; and R″ = methyl or tert-butyl) is reported. The complexes were prepared by a nonaqueous approach which employs BaH2 and the corresponding β-ketoimine. These complexes have been characterized by 1H and 13C NMR spectroscopy, elemental analysis, mass spectroscopy, cryoscopy, and thermogravimetric analysis. Single-crystal X-ray structural analysis of bis-[2,2-dimethyl-5-N-(2-(2-methoxy)ethoxyethylimino)-3-hexanonato]barium(II) reveals a monomeric eight-coordinate, distorted dodecahedral configuration about barium: space group = C2/c; a = 32.764(6) Å, b = 12.110(2) Å, c = 15.690(5) Å, β = 102.12(2), Z = 8; R(F) = 0.044, Rw(F) = 0.040 for 2776 reflections having I > 3σ(I). Single-crystal X-ray structural analysis of bis-[2,2-dimethyl-5-N-(2-(2-(2-ethoxy)ethoxy)ethoxyethylimino)-3-hexanonato] barium(II) also reveals a monomeric eight-coordinate distorted dodecahedral configuration about barium: space group = Pccn; a = 24.939(4) Å, b = 10.546(2) Å, c = 14.349(4) Å, Z = 4; R(F) = 0.036; Rw(F) = 0.035 for 1689 reflections having I > 3σ (I), Single-crystal X-ray structural analysis of bis-[5-N-(2-methoxyethylimino)-2,2,6,6-tetramethyl-3-heptanonato]barium(II) indicates a nearly symmetric Ba22-O-ketoiminate)2 dimeric structure. Each half of the dimer possesses a distorted pentagonal pyramidal local configuration about the barium ion with an unusual O, O coordination of one of the ketoiminate rings: space group = C2/c; a = 27.687(5) Å, b = 10.453(2) Å, c = 22.679(6) Å, β = 101.88(2), Z = 8; R(F) = 0.033, Rw(F) = 0.042 for 4881 reflections having I > 3σ(I). These complexes are volatile and can be used as MOCVD precursors. Thus, BaPbO3 films have been grown using these complexes and Pb(dipivaloylmethanate)2 and have been characterized by X-ray diffraction, scanning electron microscopy energy-dispersive X-ray spectroscopy, and variable-temperature resistivity measurements. Thermolytic decomposition of the barium β-ketoiminate complexes involves cleavage of the C-O bond β to nitrogen and affords pinacolone, 2,2-dimethyl-5-imino-3-hexanone, and 2-methyl-4-tert-butylpyridine as the major organic thermolysis products.

Original languageEnglish
Pages (from-to)1606-1617
Number of pages12
JournalChemistry of Materials
Volume5
Issue number11
Publication statusPublished - 1993

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ASJC Scopus subject areas

  • Materials Chemistry
  • Materials Science(all)

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