X-ray diffraction and vibrational spectroscopic studies of indolecarboxylic acids and their metal complexes Part VII. Indole-2-carboxylic acid and catena-poly[[diaquazinc(II)]-bis(μ2-indole-2-carboxylato-O:O′)]

The catena-poly[[diaquazinc(II)]-bis(mu(2)-indole-2-carboxylato-O:O')], [Zn(12CA)(2)(H2O)(2)](n) has been synthesized and characterized by X-ray diffraction analysis and the infrared and Raman spectroscopic methods. The co-ordination of the indole-2-carboxylate anion to Zn(II) results in the formation of the [Zn(12CA)(2)(H2O)(2)](n) in which the Zn(II) cations lie on inversion centres in space group P2(1/c), with water ligands in the apical sites of octahedral geometry. Moreover, the infrared and Raman spectra of indole-2-carboxylic acid (12CA) and the infrared spectrum of deuterated derivative of indole-2-carbocylic acid (12CA-d2) are recorded in the solid phase. The theoretical wavenumbers, infrared intensities and Raman scattering activities were calculated by density functional B3LYP and mPW1PW91 methods with the 6-311 ++G(d,p) basis set for 12CA and 12CA-d2 and with the 6-311 ++G(d,p)/LanL2DZ basis sets for the theoretical model of Zn(12CA)(2)(H2O)(2)](n). The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution for all molecules. (C) 2008 Elsevier B.V. All rights reserved.