X-ray and vibrational spectra on metal complexes with indolecarboxylic acids: Part IV. Catena-poly[{aqua(η2-indole-3-carboxylato-O,O′)zinc}-μ-indole-3-carboxylato-O:O′]

The new zinc(II) coordination polymer catena-poly{aqua(η²-indole-3-carboxylato-O,O′)zinc}-μ-indole-3-carboxylato-O:O′], Zn(I3CA)₂(H₂O)]_n Zn(I3CA)₂(H₂O)]_n has been synthesized and characterized using infrared and Raman spectroscopy and X-ray single-crystal diffraction analysis. The crystals are monoclinic, space group Cc, with a = 33.319(7), b = 5.985(1), c = 8.291(2) Å, V = 1653.1(6) Å³ and z = 4. Each zinc centre is five-coordinated by the bidentate chelating indole-3-carboxylato, one oxygen atom bridging indole-3-carboxylato, water molecule and one oxygen atom bridging indole-3-carboxylato from an adjacent Zn(I3CA)₂(H₂O)] unit. The Zn–O distances of 1.978(4), 1.987(3), 1.977(4), 1.983(3) and 2.519(4) Å, are typical for distances of such complexes. The infrared and Raman spectroscopic data of Zn(I3CA)₂(H₂O)]_n in the solid state are supported by X-ray analysis. The theoretical wavenumbers, infrared intensities and Raman scattering activities have been calculated by the density functional methods (B3LYP and mPW1PW) with the D95V^**/LanL2DZ and 6-311++G(d,p)/LanL2DZ basis sets. The theoretical wavenumbers, infrared intensities and Raman scattering activities show a good agreement with experimental. Detailed band assignment has been made on the basis of the calculated potential energy distribution (PED). The results provide information on the strength of zinc-ligand bonding in complex.