Isomeric chemical shift (IS) of the Mössbauer γ-line of Sn119(23.8 keV), Sb121(37.2 keV), Te125(35.6 keV) have been studied in the isoelectronic complexes, SnHal–26, SbHal–16 and TeHal–26(Hal = F, Cl, Br, I). Some other compounds of antimony have been also measured. The IS-values for these compounds depend linearly on the electro-negativity differences of the Mössbauer atom and ligand. The relation between relative change of the mean-square charge nuclear radius for three γ-transitions, (δR/R)Sb/(δR/R)Sn=–(5.5 ± 0.3) and (δR/R)Te/(δR/R)Sn=+(1.1 ± 0.2), is obtained by comparing these dependences. In 37.2 keV and 35.6 keV γ-transitions, the calibration of the IS value associated with one 5s-electron was also carried out. We have obtained the recoilless fraction of the 37.2 keV γ-quanta from Sn121O2 source as equal to ƒ= 0.32+0.04–0.02. From the measurements of the dependence of resonance effect on the Sb2O5 absorber thickness the value of the total internal conversion coefficient for the 37.2 keV γ-transition is 10.