X-ray diffraction and vibrational spectroscopic studies of indolecarboxylic acids and their metal complexes: Part VI. Indole-3-propionic acid and catena-poly[(di-μ3-aqua)(η2-:-μ2-indole-3-propionato-O,O′:-O)(μ3-indole-3-propionato-O)disodium]

In the present studies the novel catena-poly[(di-μ3-aqua)(η2-:-μ2-indole-3-propionato-O,O′:-O)(μ3-indole-3-propionato-O)disodium], [Na2(I3PA)2(H2O)2]n has been synthesized and characterized by X-ray diffraction analysis and infrared and Raman spectroscopic methods. In the [Na2(I3PA)2(H2O)2]n, there are two different crystallographic sites for the Na+ ions, which are coordinated by six and seven oxygen atoms. Moreover, two O-deprotonated I3PA ions exhibit different coordination modes. One I3PA ion acts as a tetradentate chelating-bridging ligand using two oxygen atoms of the carboxylic group, while the other behaves like a tridentate bridging using one oxygen atom of the carboxylic group, whereas the water molecules act as the tridentate bridging. The crystals of [Na2(I3PA)2(H2O)2]n are triclinic, space group P1¯, with a = 6.1281(8), b = 7.5812(9), c = 22.893(3) Å, α = 91.79(1), β = 96.56(1), γ = 90.35(1) o, V = 1056.0(2) Å3 and Z = 2.Moreover, the infrared and Raman spectra of indole-3-carboxylic acid (I3CA) and indole-3-propionic acid (I3PA) and the infrared spectra of their deuterated derivatives I3CA-d2 and I3PA-d2, respectively, have been recorded in the solid state. Experimental studies were combined with theoretical studies. Theoretical studies were performed using density functional B3LYP and mPW1PW91 methods with the 6-311++G(d,p) basis set for I3CA, I3PA, I3CA-d2, and I3PA-d2. Normal coordinate analysis was employed to obtain a clear-cut assignment of the vibrational spectra indole-3-carboxylic and indole-3-propionic acids, and their deuterated derivatives.