Pergamon 0277-5387(95) 00179-4 Polyhedron Vol. 15. No. 2, pp. 31.%319, 1996 Copyright © 1995 Elsevier Science Ltd Printed in Great Britain, All rights reserved 0277 5387/96 $9.50+0.00 SYNTHESIS AND CHARACTERIZATION OF TWO COMPLEXES OF GLYCINE WITH LANTHANUM HEXACYANOFERRATE(III) AND HEXACYANOCOBALTATE(III) J. FERNANDEZ-BERTRAN,* E. REGUERA, A. DAGO and C. LOPEZ-HERNANDEZ National Center for Scientific Research, P. O. Box 6990, Havana, Cuba and G. INFANTE CIPIMM, Capdevila Road, Havana, Cuba (Received 13 December 1994; accepted 12 April 1995) Abstract--The synthesis and analytical characterization of two new glycine complexes, La[Fe(CN)6]3GIy" 2H20 and La[Co(CN)6]3Gly" 2H20, are reported, Both compounds are isostructural, with similar XRD patterns corresponding to a triclinic crystal structure with almost equal cell parameters. M6ssbauer and IR spectra indicated a very asymmetrical environment for the hexacyano anion. Not all CN ligands are coordinated to the lanthanum cation, which is also attached to glycine molecules in the zwitterion form and to one of the water molecules. The second water molecule is labile and does not affect the M6ssbauer spectra of the iron cation. Numerous complexes of glycine with transition, lanthanide and heavy metal cations have been reported in the literature. Many of them are mixed salts with the glycinate and inorganic anions in the coordination sphere of the cation. 1 However, no complexes of this amino acid with hexacyano- metallates have been reported. In this paper we present the synthesis and characterization of two novel glycine complexes with lanthanum ferri- cyanide and cobalticyanide in which the amino acid is in the neutral zwitterion form. EXPERIMENTAL The reagents used were analytical grade com- mercial products (K3[Fe(CN)6], K3[Co(CN)6], LaC13" 7H20 and glycine). The crystal density was * Author to whomcorrespondenceshould be addressed. 31 determined by picnometry. Water content was mea- sured by thermogravimetric analysis (TGA) using MOM Q-1500 equipment. The iron, cobalt and po- tassium contents were measured by atomic absorp- tion spectrophotometry (AAS) in a Pye-Unicam 9000 spectrophometer. Lanthanum content was determined gravimetrically by the oxalate method. IR spectra were run in Nujol mulls and KBr disks using a UR-20 spectrometer (Carl Zeiss). M6ssbauer spectra were recorded at room tem- perature with a 57Co in rhodium source using a constant acceleration spectrometer (MS 1101 from MossTech) in the transmission mode. The M6ssbauer parameters, isomer shift (~), qua- drupole splitting (A), linewidth (F) and absorption line area (A), were taken from the multiparameter fitting of M6ssbauer spectra using an iterative least- square minimization algorithm and Lorentzian line shapes. The ~ values are reported relative to sodium nitroprusside. The X-ray diffraction (XRD) data for single crys-