Substituted pentacyanoferrate(II) complexes Na-3[Fe(CN)(5)L]. xH(2)O have been obtained for di-sec-butylamine, tri-n-amylamine, pyrazole, pyrazine, pyrrole, and 2-,3- and 4-cyanopyridine. Microanalysis, UV-visible, infrared, and Mossbauer 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. Mossbauer parameters are used to classify the various ligands according to their sigma- and pi-bonding abilities. The Mossbauer spectra of these complexes exhibit a quadrupole doublet, Delta E(Q) = 0.71-0.84 mm s(-1) at room temperature. The isomer shift (delta) values fall within 0.00 +/- 0.02 mm s(-1) 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.