Relation between the Electronic Structure of Tin in Its Compounds and the Isomer Shifts in Mössbauer Spectra

Expressions relating isomer shifts in Mössbauer spectra with the electronic structure of tin in its compounds are obtained. These expressions give a description of isomer shifts for chemical compounds of different types: tetravalent tin when there is π bonding (tin tetrahalogenides), tetravalent tin in the absence of π bonding (compounds where tin is bound with alkyl, aryl, and carbonyl metal radicals), bivalent tin, etc. The expressions obtained were used for analysis of the electronic structure of tin in compounds of these classes. For tetravalent tin compounds with π bonding the change of isomer shift δ towards negative values (with respect to α-Sn) is found to be accounted for by a decrease, and for compounds without π bonds by an increase in the number of valence 5s electrons (S) at S>1.