Investigation of lanthanide(III) coordination compounds with 4-pentynoic acid

Coordination compounds of a new type, Ln(C5H5O2)3⋅2H2O (where Ln = Pr3+, Nd3+, Eu3+; C5H5O2- = 4-pentynoic anion), have been obtained in solution and as crystals. Spectroscopic investigations of the title compounds at room and low temperatures were performed in order to understand the electrostatic nature of the Ln3+ligand bond. The influence of the CC triple connection in carboxylate ions on the distribution of charge, polarity, strength, and character of the LnO(L) coordination bond is analysed. The variation of spectroscopic parameters (e.g. δ) and their correlation with the nature of the Ln3+L bond are discussed. Investigation of these properties is very important because of the application of lanthanide carboxylates as catalyst precursors.