APPROACHES TO ALKALINE-EARTH METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION PRECURSORS - SYNTHESIS AND CHARACTERIZATION OF BARIUM FLUORO-BETA-KETOIMINATE COMPLEXES HAVING APPENDED POLYETHER LARIATS

The synthesis and characterization of a family of beta-ketoimines deri ved from 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hfa) and the corresp onding volatile barium beta-ketoiminate-polyether complexes having the general formula Ba[CF3COCHC(NR)CF3](2) where R = (CH2CH2O)(2)CH3, (CH 2CH2O)(2)CH2CH3, and (CH2CH2O)(3)CH2CH3 is reported. These complexes c an be transported in the vapor phase at 160 degrees C/0.05 Torr withou t decomposition. The beta-ketoiminate ligands are synthesized by conde nsation of the appropriate amine-terminated poly(ethylene oxide)s with the trimethylsilyl enol ether derivative of hfa and converted to bari um beta-ketoiminate-polyether complexes by reaction with BaH2. The pol y(ethylene oxide) amines are in turn synthesized by triphenylphosphine -mediated reduction of the corresponding poly(ethylene oxide) azides ( synthesized via the tosylates) to afford the amines in good yields and analytical purity. The amines, beta-ketoimines, and barium complexes were characterized by elemental analysis, H-1, F-19, and C-13 NMR spec troscopy, mass spectroscopy, and thermogravimetric analysis. The eight - and ten-coordinate Ba2+ complexes having the formula Ba[CF3COCHC(NR) CF3](2) where R = (CH2CH2O)(2)CH2CH3 [C22H28N2F12O6Ba; space group = m onoclinic, P2(1); a = 12.1175(2) Angstrom, b = 14.9238(2) Angstrom, c = 16.9767(3) Angstrom, alpha = gamma = 90 degrees, beta = 90.0840(10)d egrees, Z = 4] and R = (CH2CH2O)(3)CH2CH3 [C26H36N2F12O8Ba; space grou p = triclinic, P (1) over bar (#2); a = 10.971(2) Angstrom, b = 12.134 (2) Angstrom, c = 15.280(4) Angstrom, alpha = 89.94(2)degrees, beta = 110.00(2)degrees, gamma = 116.75(2)degrees, Z = 2] were characterized by single-crystal X-ray diffraction. Both analyses reveal monomeric st ructures with the beta-ketoiminate ligands coordinated to the Ba2+ cen ter through all available oxygen and nitrogen atoms. These complexes a re substantially more volatile than Ba(2,2,6,6,-tetramethyl-3,5-heptan edionate)(2) but less so than the most volatile Ba(1,1,1,5,5,5-hexaflu oro-2,4-pentanedionate)(2). polyether complexes.