thermochimica acta ELSEVIER Thermochimica Acta 287 (1996) 111-129 M6ssbauer spectroscopic and thermal decomposition studies of alkylamine and nitrogen heterocyclic substituted pentacyanoferrate(II) complexes R.B. Lanjewar t, S. Kawata a, T. Nawa a, S. Kitagawa a A.N. Garg b M. Katada a,, " Radioisotope Research centre, Tokyo Metropolitan University, Minami osawa, Hachioji. Tokyo 192-03 Japan b Department of Chemistry, Nagpur University, Naypur. 440 010, India Received 24 January 1996; accepted 19 March 1996 Abstract Substituted pentacyanoferrate(II)complexes Na3[Fe(CN)sL]'xH20 have been obtained for di-sec-butylamine, tri-n-amylamine, pyrazole, pyrazine, pyrrole, and 2-,3- and 4-cyanopyridine. Microanalysis, UV-visible, infrared, and M6ssbauer spectroscopies, TGA DTG and XRD were used to characterize the complexes, Each complex has an absorption band in the visible region that is assigned to a d-d transition. M6ssbauer parameters are used to classify the various ligands according to their a- and ~- bonding abilities. The M/Sssbauer spectra of these complexes exhibit a quadrupole doublet, AE o = 0.71-0.84 mm s- 1 at room temperature. The isomer shift (6) values fall within 0.00 + 0.02 mm s- l which suggests that the iron atom is in a + 2 low-spin state. Thermolysis of the solids leads to water release, ligand release and/or decomposition, yielding elemental metal, metal carbides, haematite and magnetite. Keywords: Thermal decomposition; M6ssbauer spectroscopy; Pentacyanoferrates(II); Iron(I) complex 1. Introduction Substantial interest in substituted pentacyanoferrates(II) continues. A wide variety of substituted pentacyanoferrates(II) have been synthesized and extensively studied by * Corresponding author. 1 On leave from A.N. College, Anandwan 442 914, India. 0040-6031/96/$15.00 © 1996 - Elsevier Science B.V. All rights reserved PII." S0040-6031 (96)02989-9