The interactions between Ln(dpm)3 [Ln3+ = Eu3+, Yb3+, Pr3+, Sm3+, Tb3+ and Ho3+; dpm=tris 2,2,6,6-tetramethylheptane-3,5-dionate] and acetamide in CCl4 solution were investigated using near IR absorption spectroscopy. From the measured 2 νc=o+ amide III combination band of acetamide in the region of 2130-2180 nm (4695-4587 cm-1), it was found that acetamide is coordinating through its carbonyl oxygen atom to Ln(dpm)3 [C=O⋯Ln(dpm)3)] and forms only 1:1 stoichiometric Ln(dpm)3- acetamide complex. The ΔH° values for the formation of Ln(dpm)3-acetamide obtained from the temperature studies are -39.1, -28.4, -25.5, -24.7, -21.1 and -17.7 kJ mol-1 for Eu(dpm)3, Yb(dpm)3, Pr(dpm)3, Sm(dpm)3, Tb(dpm)3 and Ho(dpm)3, respectively, which are larger than those of the hydrogen bond between amide and various hydrogen acceptors. Except Eu(dpm)3 and Yb(dpm)3, -ΔH° value increases as the ionic size increases.
|Number of pages||4|
|Journal||Bulletin of the Korean Chemical Society|
|Publication status||Published - 1996|
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