X-ray diffraction and DFT structures of the pentacyanocarbonylferrate(3-) ion

Recently (Soria, D.B.; Aymonino, P.J. Spectrochim. Acta 1999, A55, 1243), we reported improved C-13 NMR and IR and Raman spectra, as well as the TGA-DTA behavior of Na-3[Fe(CN)(5)CO].2H(2)O. We now report for the first time the structure of the anion obtained by x-ray diffraction (XRD) measurements performed with single crystals of the mixed Na(1)6{[Fe(CN)(5)CO](4)[Fe(CN)(6)]}. 32H(2)O salt which crystallizes in the tetragonal I4/m space group, with a = 16.308(2), c = 15.418(2) Angstrom, and Z = 2. The theoretical structure and the wave numbers corresponding to the normal modes of vibration of the [Fe(CN)(5)CO](3)- (carbonylprusside) anion were calculated with DFT methods and compared with experimental results.