SYNTHESIS, CHARACTERIZATION, AND THERMAL-BEHAVIOR OF POLYDENTATE LIGAND ADDUCTS OF BARIUM TRIFLUOROACETATE

The reaction of BaH2 with polydentate ligands and CF3COOH in THF at -4 0 degrees C in 1:1:2 stoichiometries leads to compounds of general for mula [Ba(O2CCF3)(2)](m)L-n (L = 12-crown-4 (1), triglyme (2), 2-(hydro xymethyl)-15-crown-5 (15-crown-5CH(2)OH) (3), cryptand(222) (4), 18-cr own-6 . C5H5N (5), 2-(hydroxymethyl)-18-crown-6 (18-crown-6CH(2)OH) (6 )). A sulfonate compound, Ba(O3SCF3)(2)(tetraglyme) (7), was also prep ared by a similar reaction. The polydentate ligands of 1-6 are coordin ated to the barium atoms through all of their donating atoms, and the trifluoroacetate ligands are found in four distinct types of bonding m odes. The compounds were characterized by spectroscopic and analytical methods, and 1-6 are among the first examples of group 2 trifluoroace tate compounds with mononuclear or dinuclear structures in the solid s tate as determined by single-crystal X-ray diffraction. Ba-2(O2CCF3)(4 )(12-crown-4)(2) (1) crystallizes from ethanol in monoclinic space gro up P2(1)/n with a = 11.014(1) Angstrom, b = 12.016(1) Angstrom, c = 15 .269(1) Angstrom, beta = 104.47(1)degrees, and Z = 4. Ba-2(O2CCF3)(4)( triglyme)(2) (2) crystallizes from ethanol in monoclinic space group P 2(1)/n with a = 11.203(1) Angstrom, b = 12.220(1) Angstrom, c = 15.451 (1) Angstrom. beta = 107.61(1) and Z = 4. Ba-2(O2CCF3)(4)((15)-crown-S CH2OH)(2) (3) crystallizes from ethanol in monoclinic space group P2(1 )/(c) with a = 12.445(2) Angstrom, b = 12.499(3) Angstrom, c = 15.615( 2) Angstrom, beta = 111.11 (1)degrees, and Z = 4. Ba(O2CCF3)(2)(crypta nd(222)) (4) crystallizes from toluene in the tetragonal space group P 4(3)2(1)2 with a = b = 9.263(2) Angstrom c = 35.897(7) Angstrom, and Z = 4. Ba(O2CCF3)(2)(18-crown-6)(py) (5) crystallizes from pyridine in orthorhombic space group Pnma with a = 27.178(3) Angstrom, b = 11.417( 1) Angstrom, c = 9.133(1) Angstrom, and Z = 4. Ba(O2CCF3)(2)7(18-crown -6CH(2)OH) (6) crystallizes from ethanol in monoclinic space group Pn with a = 8.279(1) Angstrom, b = 11.410(1) Angstrom, c = 13.661(2) Angs trom, beta = 98.41(1)degrees, and Z = 2. Infrared spectroscopy on 1-6 supplied information on the relationships among v(asym)(CO2), bonding mode of the trifluoroacetate ligand, and donating ability of the polyd entate ligand. Thermogravimetric analysis of 1-7 shows loss of the org anic supporting ligands in the temperature range 250-600 degrees C wit h formation of BaF2.